xref: /openbmc/linux/lib/Kconfig.debug (revision 1b36955c)
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 !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_LEB128)
286	help
287	  Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc
288	  5.0+ accepts the -gdwarf-5 flag but only had partial support for some
289	  draft features until 7.0), and gdb 8.0+.
290
291	  Changes to the structure of debug info in Version 5 allow for around
292	  15-18% savings in resulting image and debug info section sizes as
293	  compared to DWARF Version 4. DWARF Version 5 standardizes previous
294	  extensions such as accelerators for symbol indexing and the format
295	  for fission (.dwo/.dwp) files. Users may not want to select this
296	  config if they rely on tooling that has not yet been updated to
297	  support DWARF Version 5.
298
299endchoice # "Debug information"
300
301if DEBUG_INFO
302
303config DEBUG_INFO_REDUCED
304	bool "Reduce debugging information"
305	help
306	  If you say Y here gcc is instructed to generate less debugging
307	  information for structure types. This means that tools that
308	  need full debugging information (like kgdb or systemtap) won't
309	  be happy. But if you merely need debugging information to
310	  resolve line numbers there is no loss. Advantage is that
311	  build directory object sizes shrink dramatically over a full
312	  DEBUG_INFO build and compile times are reduced too.
313	  Only works with newer gcc versions.
314
315choice
316	prompt "Compressed Debug information"
317	help
318	  Compress the resulting debug info. Results in smaller debug info sections,
319	  but requires that consumers are able to decompress the results.
320
321	  If unsure, choose DEBUG_INFO_COMPRESSED_NONE.
322
323config DEBUG_INFO_COMPRESSED_NONE
324	bool "Don't compress debug information"
325	help
326	  Don't compress debug info sections.
327
328config DEBUG_INFO_COMPRESSED_ZLIB
329	bool "Compress debugging information with zlib"
330	depends on $(cc-option,-gz=zlib)
331	depends on $(ld-option,--compress-debug-sections=zlib)
332	help
333	  Compress the debug information using zlib.  Requires GCC 5.0+ or Clang
334	  5.0+, binutils 2.26+, and zlib.
335
336	  Users of dpkg-deb via scripts/package/builddeb may find an increase in
337	  size of their debug .deb packages with this config set, due to the
338	  debug info being compressed with zlib, then the object files being
339	  recompressed with a different compression scheme. But this is still
340	  preferable to setting $KDEB_COMPRESS to "none" which would be even
341	  larger.
342
343config DEBUG_INFO_COMPRESSED_ZSTD
344	bool "Compress debugging information with zstd"
345	depends on $(cc-option,-gz=zstd)
346	depends on $(ld-option,--compress-debug-sections=zstd)
347	help
348	  Compress the debug information using zstd.  This may provide better
349	  compression than zlib, for about the same time costs, but requires newer
350	  toolchain support.  Requires GCC 13.0+ or Clang 16.0+, binutils 2.40+, and
351	  zstd.
352
353endchoice # "Compressed Debug information"
354
355config DEBUG_INFO_SPLIT
356	bool "Produce split debuginfo in .dwo files"
357	depends on $(cc-option,-gsplit-dwarf)
358	help
359	  Generate debug info into separate .dwo files. This significantly
360	  reduces the build directory size for builds with DEBUG_INFO,
361	  because it stores the information only once on disk in .dwo
362	  files instead of multiple times in object files and executables.
363	  In addition the debug information is also compressed.
364
365	  Requires recent gcc (4.7+) and recent gdb/binutils.
366	  Any tool that packages or reads debug information would need
367	  to know about the .dwo files and include them.
368	  Incompatible with older versions of ccache.
369
370config DEBUG_INFO_BTF
371	bool "Generate BTF typeinfo"
372	depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED
373	depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST
374	depends on BPF_SYSCALL
375	depends on !DEBUG_INFO_DWARF5 || PAHOLE_VERSION >= 121
376	help
377	  Generate deduplicated BTF type information from DWARF debug info.
378	  Turning this on expects presence of pahole tool, which will convert
379	  DWARF type info into equivalent deduplicated BTF type info.
380
381config PAHOLE_HAS_SPLIT_BTF
382	def_bool PAHOLE_VERSION >= 119
383
384config PAHOLE_HAS_BTF_TAG
385	def_bool PAHOLE_VERSION >= 123
386	depends on CC_IS_CLANG
387	help
388	  Decide whether pahole emits btf_tag attributes (btf_type_tag and
389	  btf_decl_tag) or not. Currently only clang compiler implements
390	  these attributes, so make the config depend on CC_IS_CLANG.
391
392config PAHOLE_HAS_LANG_EXCLUDE
393	def_bool PAHOLE_VERSION >= 124
394	help
395	  Support for the --lang_exclude flag which makes pahole exclude
396	  compilation units from the supplied language. Used in Kbuild to
397	  omit Rust CUs which are not supported in version 1.24 of pahole,
398	  otherwise it would emit malformed kernel and module binaries when
399	  using DEBUG_INFO_BTF_MODULES.
400
401config DEBUG_INFO_BTF_MODULES
402	def_bool y
403	depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF
404	help
405	  Generate compact split BTF type information for kernel modules.
406
407config MODULE_ALLOW_BTF_MISMATCH
408	bool "Allow loading modules with non-matching BTF type info"
409	depends on DEBUG_INFO_BTF_MODULES
410	help
411	  For modules whose split BTF does not match vmlinux, load without
412	  BTF rather than refusing to load. The default behavior with
413	  module BTF enabled is to reject modules with such mismatches;
414	  this option will still load module BTF where possible but ignore
415	  it when a mismatch is found.
416
417config GDB_SCRIPTS
418	bool "Provide GDB scripts for kernel debugging"
419	help
420	  This creates the required links to GDB helper scripts in the
421	  build directory. If you load vmlinux into gdb, the helper
422	  scripts will be automatically imported by gdb as well, and
423	  additional functions are available to analyze a Linux kernel
424	  instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
425	  for further details.
426
427endif # DEBUG_INFO
428
429config FRAME_WARN
430	int "Warn for stack frames larger than"
431	range 0 8192
432	default 0 if KMSAN
433	default 2048 if GCC_PLUGIN_LATENT_ENTROPY
434	default 2048 if PARISC
435	default 1536 if (!64BIT && XTENSA)
436	default 1280 if KASAN && !64BIT
437	default 1024 if !64BIT
438	default 2048 if 64BIT
439	help
440	  Tell the compiler to warn at build time for stack frames larger than this.
441	  Setting this too low will cause a lot of warnings.
442	  Setting it to 0 disables the warning.
443
444config STRIP_ASM_SYMS
445	bool "Strip assembler-generated symbols during link"
446	default n
447	help
448	  Strip internal assembler-generated symbols during a link (symbols
449	  that look like '.Lxxx') so they don't pollute the output of
450	  get_wchan() and suchlike.
451
452config READABLE_ASM
453	bool "Generate readable assembler code"
454	depends on DEBUG_KERNEL
455	depends on CC_IS_GCC
456	help
457	  Disable some compiler optimizations that tend to generate human unreadable
458	  assembler output. This may make the kernel slightly slower, but it helps
459	  to keep kernel developers who have to stare a lot at assembler listings
460	  sane.
461
462config HEADERS_INSTALL
463	bool "Install uapi headers to usr/include"
464	depends on !UML
465	help
466	  This option will install uapi headers (headers exported to user-space)
467	  into the usr/include directory for use during the kernel build.
468	  This is unneeded for building the kernel itself, but needed for some
469	  user-space program samples. It is also needed by some features such
470	  as uapi header sanity checks.
471
472config DEBUG_SECTION_MISMATCH
473	bool "Enable full Section mismatch analysis"
474	depends on CC_IS_GCC
475	help
476	  The section mismatch analysis checks if there are illegal
477	  references from one section to another section.
478	  During linktime or runtime, some sections are dropped;
479	  any use of code/data previously in these sections would
480	  most likely result in an oops.
481	  In the code, functions and variables are annotated with
482	  __init,, etc. (see the full list in include/linux/init.h),
483	  which results in the code/data being placed in specific sections.
484	  The section mismatch analysis is always performed after a full
485	  kernel build, and enabling this option causes the following
486	  additional step to occur:
487	  - Add the option -fno-inline-functions-called-once to gcc commands.
488	    When inlining a function annotated with __init in a non-init
489	    function, we would lose the section information and thus
490	    the analysis would not catch the illegal reference.
491	    This option tells gcc to inline less (but it does result in
492	    a larger kernel).
493
494config SECTION_MISMATCH_WARN_ONLY
495	bool "Make section mismatch errors non-fatal"
496	default y
497	help
498	  If you say N here, the build process will fail if there are any
499	  section mismatch, instead of just throwing warnings.
500
501	  If unsure, say Y.
502
503config DEBUG_FORCE_FUNCTION_ALIGN_64B
504	bool "Force all function address 64B aligned"
505	depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC || S390)
506	select FUNCTION_ALIGNMENT_64B
507	help
508	  There are cases that a commit from one domain changes the function
509	  address alignment of other domains, and cause magic performance
510	  bump (regression or improvement). Enable this option will help to
511	  verify if the bump is caused by function alignment changes, while
512	  it will slightly increase the kernel size and affect icache usage.
513
514	  It is mainly for debug and performance tuning use.
515
516#
517# Select this config option from the architecture Kconfig, if it
518# is preferred to always offer frame pointers as a config
519# option on the architecture (regardless of KERNEL_DEBUG):
520#
521config ARCH_WANT_FRAME_POINTERS
522	bool
523
524config FRAME_POINTER
525	bool "Compile the kernel with frame pointers"
526	depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
527	default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
528	help
529	  If you say Y here the resulting kernel image will be slightly
530	  larger and slower, but it gives very useful debugging information
531	  in case of kernel bugs. (precise oopses/stacktraces/warnings)
532
533config OBJTOOL
534	bool
535
536config STACK_VALIDATION
537	bool "Compile-time stack metadata validation"
538	depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER
539	select OBJTOOL
540	default n
541	help
542	  Validate frame pointer rules at compile-time.  This helps ensure that
543	  runtime stack traces are more reliable.
544
545	  For more information, see
546	  tools/objtool/Documentation/objtool.txt.
547
548config NOINSTR_VALIDATION
549	bool
550	depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY
551	select OBJTOOL
552	default y
553
554config VMLINUX_MAP
555	bool "Generate vmlinux.map file when linking"
556	depends on EXPERT
557	help
558	  Selecting this option will pass "-Map=vmlinux.map" to ld
559	  when linking vmlinux. That file can be useful for verifying
560	  and debugging magic section games, and for seeing which
561	  pieces of code get eliminated with
562	  CONFIG_LD_DEAD_CODE_DATA_ELIMINATION.
563
564config DEBUG_FORCE_WEAK_PER_CPU
565	bool "Force weak per-cpu definitions"
566	depends on DEBUG_KERNEL
567	help
568	  s390 and alpha require percpu variables in modules to be
569	  defined weak to work around addressing range issue which
570	  puts the following two restrictions on percpu variable
571	  definitions.
572
573	  1. percpu symbols must be unique whether static or not
574	  2. percpu variables can't be defined inside a function
575
576	  To ensure that generic code follows the above rules, this
577	  option forces all percpu variables to be defined as weak.
578
579endmenu # "Compiler options"
580
581menu "Generic Kernel Debugging Instruments"
582
583config MAGIC_SYSRQ
584	bool "Magic SysRq key"
585	depends on !UML
586	help
587	  If you say Y here, you will have some control over the system even
588	  if the system crashes for example during kernel debugging (e.g., you
589	  will be able to flush the buffer cache to disk, reboot the system
590	  immediately or dump some status information). This is accomplished
591	  by pressing various keys while holding SysRq (Alt+PrintScreen). It
592	  also works on a serial console (on PC hardware at least), if you
593	  send a BREAK and then within 5 seconds a command keypress. The
594	  keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
595	  Don't say Y unless you really know what this hack does.
596
597config MAGIC_SYSRQ_DEFAULT_ENABLE
598	hex "Enable magic SysRq key functions by default"
599	depends on MAGIC_SYSRQ
600	default 0x1
601	help
602	  Specifies which SysRq key functions are enabled by default.
603	  This may be set to 1 or 0 to enable or disable them all, or
604	  to a bitmask as described in Documentation/admin-guide/sysrq.rst.
605
606config MAGIC_SYSRQ_SERIAL
607	bool "Enable magic SysRq key over serial"
608	depends on MAGIC_SYSRQ
609	default y
610	help
611	  Many embedded boards have a disconnected TTL level serial which can
612	  generate some garbage that can lead to spurious false sysrq detects.
613	  This option allows you to decide whether you want to enable the
614	  magic SysRq key.
615
616config MAGIC_SYSRQ_SERIAL_SEQUENCE
617	string "Char sequence that enables magic SysRq over serial"
618	depends on MAGIC_SYSRQ_SERIAL
619	default ""
620	help
621	  Specifies a sequence of characters that can follow BREAK to enable
622	  SysRq on a serial console.
623
624	  If unsure, leave an empty string and the option will not be enabled.
625
626config DEBUG_FS
627	bool "Debug Filesystem"
628	help
629	  debugfs is a virtual file system that kernel developers use to put
630	  debugging files into.  Enable this option to be able to read and
631	  write to these files.
632
633	  For detailed documentation on the debugfs API, see
634	  Documentation/filesystems/.
635
636	  If unsure, say N.
637
638choice
639	prompt "Debugfs default access"
640	depends on DEBUG_FS
641	default DEBUG_FS_ALLOW_ALL
642	help
643	  This selects the default access restrictions for debugfs.
644	  It can be overridden with kernel command line option
645	  debugfs=[on,no-mount,off]. The restrictions apply for API access
646	  and filesystem registration.
647
648config DEBUG_FS_ALLOW_ALL
649	bool "Access normal"
650	help
651	  No restrictions apply. Both API and filesystem registration
652	  is on. This is the normal default operation.
653
654config DEBUG_FS_DISALLOW_MOUNT
655	bool "Do not register debugfs as filesystem"
656	help
657	  The API is open but filesystem is not loaded. Clients can still do
658	  their work and read with debug tools that do not need
659	  debugfs filesystem.
660
661config DEBUG_FS_ALLOW_NONE
662	bool "No access"
663	help
664	  Access is off. Clients get -PERM when trying to create nodes in
665	  debugfs tree and debugfs is not registered as a filesystem.
666	  Client can then back-off or continue without debugfs access.
667
668endchoice
669
670source "lib/Kconfig.kgdb"
671source "lib/Kconfig.ubsan"
672source "lib/Kconfig.kcsan"
673
674endmenu
675
676menu "Networking Debugging"
677
678source "net/Kconfig.debug"
679
680endmenu # "Networking Debugging"
681
682menu "Memory Debugging"
683
684source "mm/Kconfig.debug"
685
686config DEBUG_OBJECTS
687	bool "Debug object operations"
688	depends on DEBUG_KERNEL
689	help
690	  If you say Y here, additional code will be inserted into the
691	  kernel to track the life time of various objects and validate
692	  the operations on those objects.
693
694config DEBUG_OBJECTS_SELFTEST
695	bool "Debug objects selftest"
696	depends on DEBUG_OBJECTS
697	help
698	  This enables the selftest of the object debug code.
699
700config DEBUG_OBJECTS_FREE
701	bool "Debug objects in freed memory"
702	depends on DEBUG_OBJECTS
703	help
704	  This enables checks whether a k/v free operation frees an area
705	  which contains an object which has not been deactivated
706	  properly. This can make kmalloc/kfree-intensive workloads
707	  much slower.
708
709config DEBUG_OBJECTS_TIMERS
710	bool "Debug timer objects"
711	depends on DEBUG_OBJECTS
712	help
713	  If you say Y here, additional code will be inserted into the
714	  timer routines to track the life time of timer objects and
715	  validate the timer operations.
716
717config DEBUG_OBJECTS_WORK
718	bool "Debug work objects"
719	depends on DEBUG_OBJECTS
720	help
721	  If you say Y here, additional code will be inserted into the
722	  work queue routines to track the life time of work objects and
723	  validate the work operations.
724
725config DEBUG_OBJECTS_RCU_HEAD
726	bool "Debug RCU callbacks objects"
727	depends on DEBUG_OBJECTS
728	help
729	  Enable this to turn on debugging of RCU list heads (call_rcu() usage).
730
731config DEBUG_OBJECTS_PERCPU_COUNTER
732	bool "Debug percpu counter objects"
733	depends on DEBUG_OBJECTS
734	help
735	  If you say Y here, additional code will be inserted into the
736	  percpu counter routines to track the life time of percpu counter
737	  objects and validate the percpu counter operations.
738
739config DEBUG_OBJECTS_ENABLE_DEFAULT
740	int "debug_objects bootup default value (0-1)"
741	range 0 1
742	default "1"
743	depends on DEBUG_OBJECTS
744	help
745	  Debug objects boot parameter default value
746
747config SHRINKER_DEBUG
748	bool "Enable shrinker debugging support"
749	depends on DEBUG_FS
750	help
751	  Say Y to enable the shrinker debugfs interface which provides
752	  visibility into the kernel memory shrinkers subsystem.
753	  Disable it to avoid an extra memory footprint.
754
755config DEBUG_STACK_USAGE
756	bool "Stack utilization instrumentation"
757	depends on DEBUG_KERNEL && !IA64
758	help
759	  Enables the display of the minimum amount of free stack which each
760	  task has ever had available in the sysrq-T and sysrq-P debug output.
761
762	  This option will slow down process creation somewhat.
763
764config SCHED_STACK_END_CHECK
765	bool "Detect stack corruption on calls to schedule()"
766	depends on DEBUG_KERNEL
767	default n
768	help
769	  This option checks for a stack overrun on calls to schedule().
770	  If the stack end location is found to be over written always panic as
771	  the content of the corrupted region can no longer be trusted.
772	  This is to ensure no erroneous behaviour occurs which could result in
773	  data corruption or a sporadic crash at a later stage once the region
774	  is examined. The runtime overhead introduced is minimal.
775
776config ARCH_HAS_DEBUG_VM_PGTABLE
777	bool
778	help
779	  An architecture should select this when it can successfully
780	  build and run DEBUG_VM_PGTABLE.
781
782config DEBUG_VM_IRQSOFF
783	def_bool DEBUG_VM && !PREEMPT_RT
784
785config DEBUG_VM
786	bool "Debug VM"
787	depends on DEBUG_KERNEL
788	help
789	  Enable this to turn on extended checks in the virtual-memory system
790	  that may impact performance.
791
792	  If unsure, say N.
793
794config DEBUG_VM_SHOOT_LAZIES
795	bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation"
796	depends on DEBUG_VM
797	depends on MMU_LAZY_TLB_SHOOTDOWN
798	help
799	  Enable additional IPIs that ensure lazy tlb mm references are removed
800	  before the mm is freed.
801
802	  If unsure, say N.
803
804config DEBUG_VM_MAPLE_TREE
805	bool "Debug VM maple trees"
806	depends on DEBUG_VM
807	select DEBUG_MAPLE_TREE
808	help
809	  Enable VM maple tree debugging information and extra validations.
810
811	  If unsure, say N.
812
813config DEBUG_VM_RB
814	bool "Debug VM red-black trees"
815	depends on DEBUG_VM
816	help
817	  Enable VM red-black tree debugging information and extra validations.
818
819	  If unsure, say N.
820
821config DEBUG_VM_PGFLAGS
822	bool "Debug page-flags operations"
823	depends on DEBUG_VM
824	help
825	  Enables extra validation on page flags operations.
826
827	  If unsure, say N.
828
829config DEBUG_VM_PGTABLE
830	bool "Debug arch page table for semantics compliance"
831	depends on MMU
832	depends on ARCH_HAS_DEBUG_VM_PGTABLE
833	default y if DEBUG_VM
834	help
835	  This option provides a debug method which can be used to test
836	  architecture page table helper functions on various platforms in
837	  verifying if they comply with expected generic MM semantics. This
838	  will help architecture code in making sure that any changes or
839	  new additions of these helpers still conform to expected
840	  semantics of the generic MM. Platforms will have to opt in for
841	  this through ARCH_HAS_DEBUG_VM_PGTABLE.
842
843	  If unsure, say N.
844
845config ARCH_HAS_DEBUG_VIRTUAL
846	bool
847
848config DEBUG_VIRTUAL
849	bool "Debug VM translations"
850	depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
851	help
852	  Enable some costly sanity checks in virtual to page code. This can
853	  catch mistakes with virt_to_page() and friends.
854
855	  If unsure, say N.
856
857config DEBUG_NOMMU_REGIONS
858	bool "Debug the global anon/private NOMMU mapping region tree"
859	depends on DEBUG_KERNEL && !MMU
860	help
861	  This option causes the global tree of anonymous and private mapping
862	  regions to be regularly checked for invalid topology.
863
864config DEBUG_MEMORY_INIT
865	bool "Debug memory initialisation" if EXPERT
866	default !EXPERT
867	help
868	  Enable this for additional checks during memory initialisation.
869	  The sanity checks verify aspects of the VM such as the memory model
870	  and other information provided by the architecture. Verbose
871	  information will be printed at KERN_DEBUG loglevel depending
872	  on the mminit_loglevel= command-line option.
873
874	  If unsure, say Y
875
876config MEMORY_NOTIFIER_ERROR_INJECT
877	tristate "Memory hotplug notifier error injection module"
878	depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION
879	help
880	  This option provides the ability to inject artificial errors to
881	  memory hotplug notifier chain callbacks.  It is controlled through
882	  debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
883
884	  If the notifier call chain should be failed with some events
885	  notified, write the error code to "actions/<notifier event>/error".
886
887	  Example: Inject memory hotplug offline error (-12 == -ENOMEM)
888
889	  # cd /sys/kernel/debug/notifier-error-inject/memory
890	  # echo -12 > actions/MEM_GOING_OFFLINE/error
891	  # echo offline > /sys/devices/system/memory/memoryXXX/state
892	  bash: echo: write error: Cannot allocate memory
893
894	  To compile this code as a module, choose M here: the module will
895	  be called memory-notifier-error-inject.
896
897	  If unsure, say N.
898
899config DEBUG_PER_CPU_MAPS
900	bool "Debug access to per_cpu maps"
901	depends on DEBUG_KERNEL
902	depends on SMP
903	help
904	  Say Y to verify that the per_cpu map being accessed has
905	  been set up. This adds a fair amount of code to kernel memory
906	  and decreases performance.
907
908	  Say N if unsure.
909
910config DEBUG_KMAP_LOCAL
911	bool "Debug kmap_local temporary mappings"
912	depends on DEBUG_KERNEL && KMAP_LOCAL
913	help
914	  This option enables additional error checking for the kmap_local
915	  infrastructure.  Disable for production use.
916
917config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
918	bool
919
920config DEBUG_KMAP_LOCAL_FORCE_MAP
921	bool "Enforce kmap_local temporary mappings"
922	depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
923	select KMAP_LOCAL
924	select DEBUG_KMAP_LOCAL
925	help
926	  This option enforces temporary mappings through the kmap_local
927	  mechanism for non-highmem pages and on non-highmem systems.
928	  Disable this for production systems!
929
930config DEBUG_HIGHMEM
931	bool "Highmem debugging"
932	depends on DEBUG_KERNEL && HIGHMEM
933	select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
934	select DEBUG_KMAP_LOCAL
935	help
936	  This option enables additional error checking for high memory
937	  systems.  Disable for production systems.
938
939config HAVE_DEBUG_STACKOVERFLOW
940	bool
941
942config DEBUG_STACKOVERFLOW
943	bool "Check for stack overflows"
944	depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
945	help
946	  Say Y here if you want to check for overflows of kernel, IRQ
947	  and exception stacks (if your architecture uses them). This
948	  option will show detailed messages if free stack space drops
949	  below a certain limit.
950
951	  These kinds of bugs usually occur when call-chains in the
952	  kernel get too deep, especially when interrupts are
953	  involved.
954
955	  Use this in cases where you see apparently random memory
956	  corruption, especially if it appears in 'struct thread_info'
957
958	  If in doubt, say "N".
959
960source "lib/Kconfig.kasan"
961source "lib/Kconfig.kfence"
962source "lib/Kconfig.kmsan"
963
964endmenu # "Memory Debugging"
965
966config DEBUG_SHIRQ
967	bool "Debug shared IRQ handlers"
968	depends on DEBUG_KERNEL
969	help
970	  Enable this to generate a spurious interrupt just before a shared
971	  interrupt handler is deregistered (generating one when registering
972	  is currently disabled). Drivers need to handle this correctly. Some
973	  don't and need to be caught.
974
975menu "Debug Oops, Lockups and Hangs"
976
977config PANIC_ON_OOPS
978	bool "Panic on Oops"
979	help
980	  Say Y here to enable the kernel to panic when it oopses. This
981	  has the same effect as setting oops=panic on the kernel command
982	  line.
983
984	  This feature is useful to ensure that the kernel does not do
985	  anything erroneous after an oops which could result in data
986	  corruption or other issues.
987
988	  Say N if unsure.
989
990config PANIC_ON_OOPS_VALUE
991	int
992	range 0 1
993	default 0 if !PANIC_ON_OOPS
994	default 1 if PANIC_ON_OOPS
995
996config PANIC_TIMEOUT
997	int "panic timeout"
998	default 0
999	help
1000	  Set the timeout value (in seconds) until a reboot occurs when
1001	  the kernel panics. If n = 0, then we wait forever. A timeout
1002	  value n > 0 will wait n seconds before rebooting, while a timeout
1003	  value n < 0 will reboot immediately.
1004
1005config LOCKUP_DETECTOR
1006	bool
1007
1008config SOFTLOCKUP_DETECTOR
1009	bool "Detect Soft Lockups"
1010	depends on DEBUG_KERNEL && !S390
1011	select LOCKUP_DETECTOR
1012	help
1013	  Say Y here to enable the kernel to act as a watchdog to detect
1014	  soft lockups.
1015
1016	  Softlockups are bugs that cause the kernel to loop in kernel
1017	  mode for more than 20 seconds, without giving other tasks a
1018	  chance to run.  The current stack trace is displayed upon
1019	  detection and the system will stay locked up.
1020
1021config BOOTPARAM_SOFTLOCKUP_PANIC
1022	bool "Panic (Reboot) On Soft Lockups"
1023	depends on SOFTLOCKUP_DETECTOR
1024	help
1025	  Say Y here to enable the kernel to panic on "soft lockups",
1026	  which are bugs that cause the kernel to loop in kernel
1027	  mode for more than 20 seconds (configurable using the watchdog_thresh
1028	  sysctl), without giving other tasks a chance to run.
1029
1030	  The panic can be used in combination with panic_timeout,
1031	  to cause the system to reboot automatically after a
1032	  lockup has been detected. This feature is useful for
1033	  high-availability systems that have uptime guarantees and
1034	  where a lockup must be resolved ASAP.
1035
1036	  Say N if unsure.
1037
1038config HAVE_HARDLOCKUP_DETECTOR_BUDDY
1039	bool
1040	depends on SMP
1041	default y
1042
1043#
1044# Global switch whether to build a hardlockup detector at all. It is available
1045# only when the architecture supports at least one implementation. There are
1046# two exceptions. The hardlockup detector is never enabled on:
1047#
1048#	s390: it reported many false positives there
1049#
1050#	sparc64: has a custom implementation which is not using the common
1051#		hardlockup command line options and sysctl interface.
1052#
1053config HARDLOCKUP_DETECTOR
1054	bool "Detect Hard Lockups"
1055	depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64
1056	depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH
1057	imply HARDLOCKUP_DETECTOR_PERF
1058	imply HARDLOCKUP_DETECTOR_BUDDY
1059	imply HARDLOCKUP_DETECTOR_ARCH
1060	select LOCKUP_DETECTOR
1061
1062	help
1063	  Say Y here to enable the kernel to act as a watchdog to detect
1064	  hard lockups.
1065
1066	  Hardlockups are bugs that cause the CPU to loop in kernel mode
1067	  for more than 10 seconds, without letting other interrupts have a
1068	  chance to run.  The current stack trace is displayed upon detection
1069	  and the system will stay locked up.
1070
1071#
1072# Note that arch-specific variants are always preferred.
1073#
1074config HARDLOCKUP_DETECTOR_PREFER_BUDDY
1075	bool "Prefer the buddy CPU hardlockup detector"
1076	depends on HARDLOCKUP_DETECTOR
1077	depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY
1078	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1079	help
1080	  Say Y here to prefer the buddy hardlockup detector over the perf one.
1081
1082	  With the buddy detector, each CPU uses its softlockup hrtimer
1083	  to check that the next CPU is processing hrtimer interrupts by
1084	  verifying that a counter is increasing.
1085
1086	  This hardlockup detector is useful on systems that don't have
1087	  an arch-specific hardlockup detector or if resources needed
1088	  for the hardlockup detector are better used for other things.
1089
1090config HARDLOCKUP_DETECTOR_PERF
1091	bool
1092	depends on HARDLOCKUP_DETECTOR
1093	depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY
1094	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1095	select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1096
1097config HARDLOCKUP_DETECTOR_BUDDY
1098	bool
1099	depends on HARDLOCKUP_DETECTOR
1100	depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY
1101	depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY
1102	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1103	select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1104
1105config HARDLOCKUP_DETECTOR_ARCH
1106	bool
1107	depends on HARDLOCKUP_DETECTOR
1108	depends on HAVE_HARDLOCKUP_DETECTOR_ARCH
1109	help
1110	  The arch-specific implementation of the hardlockup detector will
1111	  be used.
1112
1113#
1114# Both the "perf" and "buddy" hardlockup detectors count hrtimer
1115# interrupts. This config enables functions managing this common code.
1116#
1117config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1118	bool
1119	select SOFTLOCKUP_DETECTOR
1120
1121#
1122# Enables a timestamp based low pass filter to compensate for perf based
1123# hard lockup detection which runs too fast due to turbo modes.
1124#
1125config HARDLOCKUP_CHECK_TIMESTAMP
1126	bool
1127
1128config BOOTPARAM_HARDLOCKUP_PANIC
1129	bool "Panic (Reboot) On Hard Lockups"
1130	depends on HARDLOCKUP_DETECTOR
1131	help
1132	  Say Y here to enable the kernel to panic on "hard lockups",
1133	  which are bugs that cause the kernel to loop in kernel
1134	  mode with interrupts disabled for more than 10 seconds (configurable
1135	  using the watchdog_thresh sysctl).
1136
1137	  Say N if unsure.
1138
1139config DETECT_HUNG_TASK
1140	bool "Detect Hung Tasks"
1141	depends on DEBUG_KERNEL
1142	default SOFTLOCKUP_DETECTOR
1143	help
1144	  Say Y here to enable the kernel to detect "hung tasks",
1145	  which are bugs that cause the task to be stuck in
1146	  uninterruptible "D" state indefinitely.
1147
1148	  When a hung task is detected, the kernel will print the
1149	  current stack trace (which you should report), but the
1150	  task will stay in uninterruptible state. If lockdep is
1151	  enabled then all held locks will also be reported. This
1152	  feature has negligible overhead.
1153
1154config DEFAULT_HUNG_TASK_TIMEOUT
1155	int "Default timeout for hung task detection (in seconds)"
1156	depends on DETECT_HUNG_TASK
1157	default 120
1158	help
1159	  This option controls the default timeout (in seconds) used
1160	  to determine when a task has become non-responsive and should
1161	  be considered hung.
1162
1163	  It can be adjusted at runtime via the kernel.hung_task_timeout_secs
1164	  sysctl or by writing a value to
1165	  /proc/sys/kernel/hung_task_timeout_secs.
1166
1167	  A timeout of 0 disables the check.  The default is two minutes.
1168	  Keeping the default should be fine in most cases.
1169
1170config BOOTPARAM_HUNG_TASK_PANIC
1171	bool "Panic (Reboot) On Hung Tasks"
1172	depends on DETECT_HUNG_TASK
1173	help
1174	  Say Y here to enable the kernel to panic on "hung tasks",
1175	  which are bugs that cause the kernel to leave a task stuck
1176	  in uninterruptible "D" state.
1177
1178	  The panic can be used in combination with panic_timeout,
1179	  to cause the system to reboot automatically after a
1180	  hung task has been detected. This feature is useful for
1181	  high-availability systems that have uptime guarantees and
1182	  where a hung tasks must be resolved ASAP.
1183
1184	  Say N if unsure.
1185
1186config WQ_WATCHDOG
1187	bool "Detect Workqueue Stalls"
1188	depends on DEBUG_KERNEL
1189	help
1190	  Say Y here to enable stall detection on workqueues.  If a
1191	  worker pool doesn't make forward progress on a pending work
1192	  item for over a given amount of time, 30s by default, a
1193	  warning message is printed along with dump of workqueue
1194	  state.  This can be configured through kernel parameter
1195	  "workqueue.watchdog_thresh" and its sysfs counterpart.
1196
1197config WQ_CPU_INTENSIVE_REPORT
1198	bool "Report per-cpu work items which hog CPU for too long"
1199	depends on DEBUG_KERNEL
1200	help
1201	  Say Y here to enable reporting of concurrency-managed per-cpu work
1202	  items that hog CPUs for longer than
1203	  workqueue.cpu_intensive_thresh_us. Workqueue automatically
1204	  detects and excludes them from concurrency management to prevent
1205	  them from stalling other per-cpu work items. Occassional
1206	  triggering may not necessarily indicate a problem. Repeated
1207	  triggering likely indicates that the work item should be switched
1208	  to use an unbound workqueue.
1209
1210config TEST_LOCKUP
1211	tristate "Test module to generate lockups"
1212	depends on m
1213	help
1214	  This builds the "test_lockup" module that helps to make sure
1215	  that watchdogs and lockup detectors are working properly.
1216
1217	  Depending on module parameters it could emulate soft or hard
1218	  lockup, "hung task", or locking arbitrary lock for a long time.
1219	  Also it could generate series of lockups with cooling-down periods.
1220
1221	  If unsure, say N.
1222
1223endmenu # "Debug lockups and hangs"
1224
1225menu "Scheduler Debugging"
1226
1227config SCHED_DEBUG
1228	bool "Collect scheduler debugging info"
1229	depends on DEBUG_KERNEL && DEBUG_FS
1230	default y
1231	help
1232	  If you say Y here, the /sys/kernel/debug/sched file will be provided
1233	  that can help debug the scheduler. The runtime overhead of this
1234	  option is minimal.
1235
1236config SCHED_INFO
1237	bool
1238	default n
1239
1240config SCHEDSTATS
1241	bool "Collect scheduler statistics"
1242	depends on DEBUG_KERNEL && PROC_FS
1243	select SCHED_INFO
1244	help
1245	  If you say Y here, additional code will be inserted into the
1246	  scheduler and related routines to collect statistics about
1247	  scheduler behavior and provide them in /proc/schedstat.  These
1248	  stats may be useful for both tuning and debugging the scheduler
1249	  If you aren't debugging the scheduler or trying to tune a specific
1250	  application, you can say N to avoid the very slight overhead
1251	  this adds.
1252
1253endmenu
1254
1255config DEBUG_TIMEKEEPING
1256	bool "Enable extra timekeeping sanity checking"
1257	help
1258	  This option will enable additional timekeeping sanity checks
1259	  which may be helpful when diagnosing issues where timekeeping
1260	  problems are suspected.
1261
1262	  This may include checks in the timekeeping hotpaths, so this
1263	  option may have a (very small) performance impact to some
1264	  workloads.
1265
1266	  If unsure, say N.
1267
1268config DEBUG_PREEMPT
1269	bool "Debug preemptible kernel"
1270	depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT
1271	help
1272	  If you say Y here then the kernel will use a debug variant of the
1273	  commonly used smp_processor_id() function and will print warnings
1274	  if kernel code uses it in a preemption-unsafe way. Also, the kernel
1275	  will detect preemption count underflows.
1276
1277	  This option has potential to introduce high runtime overhead,
1278	  depending on workload as it triggers debugging routines for each
1279	  this_cpu operation. It should only be used for debugging purposes.
1280
1281menu "Lock Debugging (spinlocks, mutexes, etc...)"
1282
1283config LOCK_DEBUGGING_SUPPORT
1284	bool
1285	depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1286	default y
1287
1288config PROVE_LOCKING
1289	bool "Lock debugging: prove locking correctness"
1290	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1291	select LOCKDEP
1292	select DEBUG_SPINLOCK
1293	select DEBUG_MUTEXES if !PREEMPT_RT
1294	select DEBUG_RT_MUTEXES if RT_MUTEXES
1295	select DEBUG_RWSEMS
1296	select DEBUG_WW_MUTEX_SLOWPATH
1297	select DEBUG_LOCK_ALLOC
1298	select PREEMPT_COUNT if !ARCH_NO_PREEMPT
1299	select TRACE_IRQFLAGS
1300	default n
1301	help
1302	 This feature enables the kernel to prove that all locking
1303	 that occurs in the kernel runtime is mathematically
1304	 correct: that under no circumstance could an arbitrary (and
1305	 not yet triggered) combination of observed locking
1306	 sequences (on an arbitrary number of CPUs, running an
1307	 arbitrary number of tasks and interrupt contexts) cause a
1308	 deadlock.
1309
1310	 In short, this feature enables the kernel to report locking
1311	 related deadlocks before they actually occur.
1312
1313	 The proof does not depend on how hard and complex a
1314	 deadlock scenario would be to trigger: how many
1315	 participant CPUs, tasks and irq-contexts would be needed
1316	 for it to trigger. The proof also does not depend on
1317	 timing: if a race and a resulting deadlock is possible
1318	 theoretically (no matter how unlikely the race scenario
1319	 is), it will be proven so and will immediately be
1320	 reported by the kernel (once the event is observed that
1321	 makes the deadlock theoretically possible).
1322
1323	 If a deadlock is impossible (i.e. the locking rules, as
1324	 observed by the kernel, are mathematically correct), the
1325	 kernel reports nothing.
1326
1327	 NOTE: this feature can also be enabled for rwlocks, mutexes
1328	 and rwsems - in which case all dependencies between these
1329	 different locking variants are observed and mapped too, and
1330	 the proof of observed correctness is also maintained for an
1331	 arbitrary combination of these separate locking variants.
1332
1333	 For more details, see Documentation/locking/lockdep-design.rst.
1334
1335config PROVE_RAW_LOCK_NESTING
1336	bool "Enable raw_spinlock - spinlock nesting checks"
1337	depends on PROVE_LOCKING
1338	default n
1339	help
1340	 Enable the raw_spinlock vs. spinlock nesting checks which ensure
1341	 that the lock nesting rules for PREEMPT_RT enabled kernels are
1342	 not violated.
1343
1344	 NOTE: There are known nesting problems. So if you enable this
1345	 option expect lockdep splats until these problems have been fully
1346	 addressed which is work in progress. This config switch allows to
1347	 identify and analyze these problems. It will be removed and the
1348	 check permanently enabled once the main issues have been fixed.
1349
1350	 If unsure, select N.
1351
1352config LOCK_STAT
1353	bool "Lock usage statistics"
1354	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1355	select LOCKDEP
1356	select DEBUG_SPINLOCK
1357	select DEBUG_MUTEXES if !PREEMPT_RT
1358	select DEBUG_RT_MUTEXES if RT_MUTEXES
1359	select DEBUG_LOCK_ALLOC
1360	default n
1361	help
1362	 This feature enables tracking lock contention points
1363
1364	 For more details, see Documentation/locking/lockstat.rst
1365
1366	 This also enables lock events required by "perf lock",
1367	 subcommand of perf.
1368	 If you want to use "perf lock", you also need to turn on
1369	 CONFIG_EVENT_TRACING.
1370
1371	 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1372	 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1373
1374config DEBUG_RT_MUTEXES
1375	bool "RT Mutex debugging, deadlock detection"
1376	depends on DEBUG_KERNEL && RT_MUTEXES
1377	help
1378	 This allows rt mutex semantics violations and rt mutex related
1379	 deadlocks (lockups) to be detected and reported automatically.
1380
1381config DEBUG_SPINLOCK
1382	bool "Spinlock and rw-lock debugging: basic checks"
1383	depends on DEBUG_KERNEL
1384	select UNINLINE_SPIN_UNLOCK
1385	help
1386	  Say Y here and build SMP to catch missing spinlock initialization
1387	  and certain other kinds of spinlock errors commonly made.  This is
1388	  best used in conjunction with the NMI watchdog so that spinlock
1389	  deadlocks are also debuggable.
1390
1391config DEBUG_MUTEXES
1392	bool "Mutex debugging: basic checks"
1393	depends on DEBUG_KERNEL && !PREEMPT_RT
1394	help
1395	 This feature allows mutex semantics violations to be detected and
1396	 reported.
1397
1398config DEBUG_WW_MUTEX_SLOWPATH
1399	bool "Wait/wound mutex debugging: Slowpath testing"
1400	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1401	select DEBUG_LOCK_ALLOC
1402	select DEBUG_SPINLOCK
1403	select DEBUG_MUTEXES if !PREEMPT_RT
1404	select DEBUG_RT_MUTEXES if PREEMPT_RT
1405	help
1406	 This feature enables slowpath testing for w/w mutex users by
1407	 injecting additional -EDEADLK wound/backoff cases. Together with
1408	 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1409	 will test all possible w/w mutex interface abuse with the
1410	 exception of simply not acquiring all the required locks.
1411	 Note that this feature can introduce significant overhead, so
1412	 it really should not be enabled in a production or distro kernel,
1413	 even a debug kernel.  If you are a driver writer, enable it.  If
1414	 you are a distro, do not.
1415
1416config DEBUG_RWSEMS
1417	bool "RW Semaphore debugging: basic checks"
1418	depends on DEBUG_KERNEL
1419	help
1420	  This debugging feature allows mismatched rw semaphore locks
1421	  and unlocks to be detected and reported.
1422
1423config DEBUG_LOCK_ALLOC
1424	bool "Lock debugging: detect incorrect freeing of live locks"
1425	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1426	select DEBUG_SPINLOCK
1427	select DEBUG_MUTEXES if !PREEMPT_RT
1428	select DEBUG_RT_MUTEXES if RT_MUTEXES
1429	select LOCKDEP
1430	help
1431	 This feature will check whether any held lock (spinlock, rwlock,
1432	 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1433	 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1434	 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1435	 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1436	 held during task exit.
1437
1438config LOCKDEP
1439	bool
1440	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1441	select STACKTRACE
1442	select KALLSYMS
1443	select KALLSYMS_ALL
1444
1445config LOCKDEP_SMALL
1446	bool
1447
1448config LOCKDEP_BITS
1449	int "Bitsize for MAX_LOCKDEP_ENTRIES"
1450	depends on LOCKDEP && !LOCKDEP_SMALL
1451	range 10 30
1452	default 15
1453	help
1454	  Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message.
1455
1456config LOCKDEP_CHAINS_BITS
1457	int "Bitsize for MAX_LOCKDEP_CHAINS"
1458	depends on LOCKDEP && !LOCKDEP_SMALL
1459	range 10 30
1460	default 16
1461	help
1462	  Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message.
1463
1464config LOCKDEP_STACK_TRACE_BITS
1465	int "Bitsize for MAX_STACK_TRACE_ENTRIES"
1466	depends on LOCKDEP && !LOCKDEP_SMALL
1467	range 10 30
1468	default 19
1469	help
1470	  Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message.
1471
1472config LOCKDEP_STACK_TRACE_HASH_BITS
1473	int "Bitsize for STACK_TRACE_HASH_SIZE"
1474	depends on LOCKDEP && !LOCKDEP_SMALL
1475	range 10 30
1476	default 14
1477	help
1478	  Try increasing this value if you need large STACK_TRACE_HASH_SIZE.
1479
1480config LOCKDEP_CIRCULAR_QUEUE_BITS
1481	int "Bitsize for elements in circular_queue struct"
1482	depends on LOCKDEP
1483	range 10 30
1484	default 12
1485	help
1486	  Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure.
1487
1488config DEBUG_LOCKDEP
1489	bool "Lock dependency engine debugging"
1490	depends on DEBUG_KERNEL && LOCKDEP
1491	select DEBUG_IRQFLAGS
1492	help
1493	  If you say Y here, the lock dependency engine will do
1494	  additional runtime checks to debug itself, at the price
1495	  of more runtime overhead.
1496
1497config DEBUG_ATOMIC_SLEEP
1498	bool "Sleep inside atomic section checking"
1499	select PREEMPT_COUNT
1500	depends on DEBUG_KERNEL
1501	depends on !ARCH_NO_PREEMPT
1502	help
1503	  If you say Y here, various routines which may sleep will become very
1504	  noisy if they are called inside atomic sections: when a spinlock is
1505	  held, inside an rcu read side critical section, inside preempt disabled
1506	  sections, inside an interrupt, etc...
1507
1508config DEBUG_LOCKING_API_SELFTESTS
1509	bool "Locking API boot-time self-tests"
1510	depends on DEBUG_KERNEL
1511	help
1512	  Say Y here if you want the kernel to run a short self-test during
1513	  bootup. The self-test checks whether common types of locking bugs
1514	  are detected by debugging mechanisms or not. (if you disable
1515	  lock debugging then those bugs won't be detected of course.)
1516	  The following locking APIs are covered: spinlocks, rwlocks,
1517	  mutexes and rwsems.
1518
1519config LOCK_TORTURE_TEST
1520	tristate "torture tests for locking"
1521	depends on DEBUG_KERNEL
1522	select TORTURE_TEST
1523	help
1524	  This option provides a kernel module that runs torture tests
1525	  on kernel locking primitives.  The kernel module may be built
1526	  after the fact on the running kernel to be tested, if desired.
1527
1528	  Say Y here if you want kernel locking-primitive torture tests
1529	  to be built into the kernel.
1530	  Say M if you want these torture tests to build as a module.
1531	  Say N if you are unsure.
1532
1533config WW_MUTEX_SELFTEST
1534	tristate "Wait/wound mutex selftests"
1535	help
1536	  This option provides a kernel module that runs tests on the
1537	  on the struct ww_mutex locking API.
1538
1539	  It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1540	  with this test harness.
1541
1542	  Say M if you want these self tests to build as a module.
1543	  Say N if you are unsure.
1544
1545config SCF_TORTURE_TEST
1546	tristate "torture tests for smp_call_function*()"
1547	depends on DEBUG_KERNEL
1548	select TORTURE_TEST
1549	help
1550	  This option provides a kernel module that runs torture tests
1551	  on the smp_call_function() family of primitives.  The kernel
1552	  module may be built after the fact on the running kernel to
1553	  be tested, if desired.
1554
1555config CSD_LOCK_WAIT_DEBUG
1556	bool "Debugging for csd_lock_wait(), called from smp_call_function*()"
1557	depends on DEBUG_KERNEL
1558	depends on 64BIT
1559	default n
1560	help
1561	  This option enables debug prints when CPUs are slow to respond
1562	  to the smp_call_function*() IPI wrappers.  These debug prints
1563	  include the IPI handler function currently executing (if any)
1564	  and relevant stack traces.
1565
1566config CSD_LOCK_WAIT_DEBUG_DEFAULT
1567	bool "Default csd_lock_wait() debugging on at boot time"
1568	depends on CSD_LOCK_WAIT_DEBUG
1569	depends on 64BIT
1570	default n
1571	help
1572	  This option causes the csdlock_debug= kernel boot parameter to
1573	  default to 1 (basic debugging) instead of 0 (no debugging).
1574
1575endmenu # lock debugging
1576
1577config TRACE_IRQFLAGS
1578	depends on TRACE_IRQFLAGS_SUPPORT
1579	bool
1580	help
1581	  Enables hooks to interrupt enabling and disabling for
1582	  either tracing or lock debugging.
1583
1584config TRACE_IRQFLAGS_NMI
1585	def_bool y
1586	depends on TRACE_IRQFLAGS
1587	depends on TRACE_IRQFLAGS_NMI_SUPPORT
1588
1589config NMI_CHECK_CPU
1590	bool "Debugging for CPUs failing to respond to backtrace requests"
1591	depends on DEBUG_KERNEL
1592	depends on X86
1593	default n
1594	help
1595	  Enables debug prints when a CPU fails to respond to a given
1596	  backtrace NMI.  These prints provide some reasons why a CPU
1597	  might legitimately be failing to respond, for example, if it
1598	  is offline of if ignore_nmis is set.
1599
1600config DEBUG_IRQFLAGS
1601	bool "Debug IRQ flag manipulation"
1602	help
1603	  Enables checks for potentially unsafe enabling or disabling of
1604	  interrupts, such as calling raw_local_irq_restore() when interrupts
1605	  are enabled.
1606
1607config STACKTRACE
1608	bool "Stack backtrace support"
1609	depends on STACKTRACE_SUPPORT
1610	help
1611	  This option causes the kernel to create a /proc/pid/stack for
1612	  every process, showing its current stack trace.
1613	  It is also used by various kernel debugging features that require
1614	  stack trace generation.
1615
1616config WARN_ALL_UNSEEDED_RANDOM
1617	bool "Warn for all uses of unseeded randomness"
1618	default n
1619	help
1620	  Some parts of the kernel contain bugs relating to their use of
1621	  cryptographically secure random numbers before it's actually possible
1622	  to generate those numbers securely. This setting ensures that these
1623	  flaws don't go unnoticed, by enabling a message, should this ever
1624	  occur. This will allow people with obscure setups to know when things
1625	  are going wrong, so that they might contact developers about fixing
1626	  it.
1627
1628	  Unfortunately, on some models of some architectures getting
1629	  a fully seeded CRNG is extremely difficult, and so this can
1630	  result in dmesg getting spammed for a surprisingly long
1631	  time.  This is really bad from a security perspective, and
1632	  so architecture maintainers really need to do what they can
1633	  to get the CRNG seeded sooner after the system is booted.
1634	  However, since users cannot do anything actionable to
1635	  address this, by default this option is disabled.
1636
1637	  Say Y here if you want to receive warnings for all uses of
1638	  unseeded randomness.  This will be of use primarily for
1639	  those developers interested in improving the security of
1640	  Linux kernels running on their architecture (or
1641	  subarchitecture).
1642
1643config DEBUG_KOBJECT
1644	bool "kobject debugging"
1645	depends on DEBUG_KERNEL
1646	help
1647	  If you say Y here, some extra kobject debugging messages will be sent
1648	  to the syslog.
1649
1650config DEBUG_KOBJECT_RELEASE
1651	bool "kobject release debugging"
1652	depends on DEBUG_OBJECTS_TIMERS
1653	help
1654	  kobjects are reference counted objects.  This means that their
1655	  last reference count put is not predictable, and the kobject can
1656	  live on past the point at which a driver decides to drop its
1657	  initial reference to the kobject gained on allocation.  An
1658	  example of this would be a struct device which has just been
1659	  unregistered.
1660
1661	  However, some buggy drivers assume that after such an operation,
1662	  the memory backing the kobject can be immediately freed.  This
1663	  goes completely against the principles of a refcounted object.
1664
1665	  If you say Y here, the kernel will delay the release of kobjects
1666	  on the last reference count to improve the visibility of this
1667	  kind of kobject release bug.
1668
1669config HAVE_DEBUG_BUGVERBOSE
1670	bool
1671
1672menu "Debug kernel data structures"
1673
1674config DEBUG_LIST
1675	bool "Debug linked list manipulation"
1676	depends on DEBUG_KERNEL
1677	select LIST_HARDENED
1678	help
1679	  Enable this to turn on extended checks in the linked-list walking
1680	  routines.
1681
1682	  This option trades better quality error reports for performance, and
1683	  is more suitable for kernel debugging. If you care about performance,
1684	  you should only enable CONFIG_LIST_HARDENED instead.
1685
1686	  If unsure, say N.
1687
1688config DEBUG_PLIST
1689	bool "Debug priority linked list manipulation"
1690	depends on DEBUG_KERNEL
1691	help
1692	  Enable this to turn on extended checks in the priority-ordered
1693	  linked-list (plist) walking routines.  This checks the entire
1694	  list multiple times during each manipulation.
1695
1696	  If unsure, say N.
1697
1698config DEBUG_SG
1699	bool "Debug SG table operations"
1700	depends on DEBUG_KERNEL
1701	help
1702	  Enable this to turn on checks on scatter-gather tables. This can
1703	  help find problems with drivers that do not properly initialize
1704	  their sg tables.
1705
1706	  If unsure, say N.
1707
1708config DEBUG_NOTIFIERS
1709	bool "Debug notifier call chains"
1710	depends on DEBUG_KERNEL
1711	help
1712	  Enable this to turn on sanity checking for notifier call chains.
1713	  This is most useful for kernel developers to make sure that
1714	  modules properly unregister themselves from notifier chains.
1715	  This is a relatively cheap check but if you care about maximum
1716	  performance, say N.
1717
1718config DEBUG_MAPLE_TREE
1719	bool "Debug maple trees"
1720	depends on DEBUG_KERNEL
1721	help
1722	  Enable maple tree debugging information and extra validations.
1723
1724	  If unsure, say N.
1725
1726endmenu
1727
1728config DEBUG_CREDENTIALS
1729	bool "Debug credential management"
1730	depends on DEBUG_KERNEL
1731	help
1732	  Enable this to turn on some debug checking for credential
1733	  management.  The additional code keeps track of the number of
1734	  pointers from task_structs to any given cred struct, and checks to
1735	  see that this number never exceeds the usage count of the cred
1736	  struct.
1737
1738	  Furthermore, if SELinux is enabled, this also checks that the
1739	  security pointer in the cred struct is never seen to be invalid.
1740
1741	  If unsure, say N.
1742
1743source "kernel/rcu/Kconfig.debug"
1744
1745config DEBUG_WQ_FORCE_RR_CPU
1746	bool "Force round-robin CPU selection for unbound work items"
1747	depends on DEBUG_KERNEL
1748	default n
1749	help
1750	  Workqueue used to implicitly guarantee that work items queued
1751	  without explicit CPU specified are put on the local CPU.  This
1752	  guarantee is no longer true and while local CPU is still
1753	  preferred work items may be put on foreign CPUs.  Kernel
1754	  parameter "workqueue.debug_force_rr_cpu" is added to force
1755	  round-robin CPU selection to flush out usages which depend on the
1756	  now broken guarantee.  This config option enables the debug
1757	  feature by default.  When enabled, memory and cache locality will
1758	  be impacted.
1759
1760config CPU_HOTPLUG_STATE_CONTROL
1761	bool "Enable CPU hotplug state control"
1762	depends on DEBUG_KERNEL
1763	depends on HOTPLUG_CPU
1764	default n
1765	help
1766	  Allows to write steps between "offline" and "online" to the CPUs
1767	  sysfs target file so states can be stepped granular. This is a debug
1768	  option for now as the hotplug machinery cannot be stopped and
1769	  restarted at arbitrary points yet.
1770
1771	  Say N if your are unsure.
1772
1773config LATENCYTOP
1774	bool "Latency measuring infrastructure"
1775	depends on DEBUG_KERNEL
1776	depends on STACKTRACE_SUPPORT
1777	depends on PROC_FS
1778	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
1779	select KALLSYMS
1780	select KALLSYMS_ALL
1781	select STACKTRACE
1782	select SCHEDSTATS
1783	help
1784	  Enable this option if you want to use the LatencyTOP tool
1785	  to find out which userspace is blocking on what kernel operations.
1786
1787config DEBUG_CGROUP_REF
1788	bool "Disable inlining of cgroup css reference count functions"
1789	depends on DEBUG_KERNEL
1790	depends on CGROUPS
1791	depends on KPROBES
1792	default n
1793	help
1794	  Force cgroup css reference count functions to not be inlined so
1795	  that they can be kprobed for debugging.
1796
1797source "kernel/trace/Kconfig"
1798
1799config PROVIDE_OHCI1394_DMA_INIT
1800	bool "Remote debugging over FireWire early on boot"
1801	depends on PCI && X86
1802	help
1803	  If you want to debug problems which hang or crash the kernel early
1804	  on boot and the crashing machine has a FireWire port, you can use
1805	  this feature to remotely access the memory of the crashed machine
1806	  over FireWire. This employs remote DMA as part of the OHCI1394
1807	  specification which is now the standard for FireWire controllers.
1808
1809	  With remote DMA, you can monitor the printk buffer remotely using
1810	  firescope and access all memory below 4GB using fireproxy from gdb.
1811	  Even controlling a kernel debugger is possible using remote DMA.
1812
1813	  Usage:
1814
1815	  If ohci1394_dma=early is used as boot parameter, it will initialize
1816	  all OHCI1394 controllers which are found in the PCI config space.
1817
1818	  As all changes to the FireWire bus such as enabling and disabling
1819	  devices cause a bus reset and thereby disable remote DMA for all
1820	  devices, be sure to have the cable plugged and FireWire enabled on
1821	  the debugging host before booting the debug target for debugging.
1822
1823	  This code (~1k) is freed after boot. By then, the firewire stack
1824	  in charge of the OHCI-1394 controllers should be used instead.
1825
1826	  See Documentation/core-api/debugging-via-ohci1394.rst for more information.
1827
1828source "samples/Kconfig"
1829
1830config ARCH_HAS_DEVMEM_IS_ALLOWED
1831	bool
1832
1833config STRICT_DEVMEM
1834	bool "Filter access to /dev/mem"
1835	depends on MMU && DEVMEM
1836	depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED
1837	default y if PPC || X86 || ARM64
1838	help
1839	  If this option is disabled, you allow userspace (root) access to all
1840	  of memory, including kernel and userspace memory. Accidental
1841	  access to this is obviously disastrous, but specific access can
1842	  be used by people debugging the kernel. Note that with PAT support
1843	  enabled, even in this case there are restrictions on /dev/mem
1844	  use due to the cache aliasing requirements.
1845
1846	  If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
1847	  file only allows userspace access to PCI space and the BIOS code and
1848	  data regions.  This is sufficient for dosemu and X and all common
1849	  users of /dev/mem.
1850
1851	  If in doubt, say Y.
1852
1853config IO_STRICT_DEVMEM
1854	bool "Filter I/O access to /dev/mem"
1855	depends on STRICT_DEVMEM
1856	help
1857	  If this option is disabled, you allow userspace (root) access to all
1858	  io-memory regardless of whether a driver is actively using that
1859	  range.  Accidental access to this is obviously disastrous, but
1860	  specific access can be used by people debugging kernel drivers.
1861
1862	  If this option is switched on, the /dev/mem file only allows
1863	  userspace access to *idle* io-memory ranges (see /proc/iomem) This
1864	  may break traditional users of /dev/mem (dosemu, legacy X, etc...)
1865	  if the driver using a given range cannot be disabled.
1866
1867	  If in doubt, say Y.
1868
1869menu "$(SRCARCH) Debugging"
1870
1871source "arch/$(SRCARCH)/Kconfig.debug"
1872
1873endmenu
1874
1875menu "Kernel Testing and Coverage"
1876
1877source "lib/kunit/Kconfig"
1878
1879config NOTIFIER_ERROR_INJECTION
1880	tristate "Notifier error injection"
1881	depends on DEBUG_KERNEL
1882	select DEBUG_FS
1883	help
1884	  This option provides the ability to inject artificial errors to
1885	  specified notifier chain callbacks. It is useful to test the error
1886	  handling of notifier call chain failures.
1887
1888	  Say N if unsure.
1889
1890config PM_NOTIFIER_ERROR_INJECT
1891	tristate "PM notifier error injection module"
1892	depends on PM && NOTIFIER_ERROR_INJECTION
1893	default m if PM_DEBUG
1894	help
1895	  This option provides the ability to inject artificial errors to
1896	  PM notifier chain callbacks.  It is controlled through debugfs
1897	  interface /sys/kernel/debug/notifier-error-inject/pm
1898
1899	  If the notifier call chain should be failed with some events
1900	  notified, write the error code to "actions/<notifier event>/error".
1901
1902	  Example: Inject PM suspend error (-12 = -ENOMEM)
1903
1904	  # cd /sys/kernel/debug/notifier-error-inject/pm/
1905	  # echo -12 > actions/PM_SUSPEND_PREPARE/error
1906	  # echo mem > /sys/power/state
1907	  bash: echo: write error: Cannot allocate memory
1908
1909	  To compile this code as a module, choose M here: the module will
1910	  be called pm-notifier-error-inject.
1911
1912	  If unsure, say N.
1913
1914config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1915	tristate "OF reconfig notifier error injection module"
1916	depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1917	help
1918	  This option provides the ability to inject artificial errors to
1919	  OF reconfig notifier chain callbacks.  It is controlled
1920	  through debugfs interface under
1921	  /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1922
1923	  If the notifier call chain should be failed with some events
1924	  notified, write the error code to "actions/<notifier event>/error".
1925
1926	  To compile this code as a module, choose M here: the module will
1927	  be called of-reconfig-notifier-error-inject.
1928
1929	  If unsure, say N.
1930
1931config NETDEV_NOTIFIER_ERROR_INJECT
1932	tristate "Netdev notifier error injection module"
1933	depends on NET && NOTIFIER_ERROR_INJECTION
1934	help
1935	  This option provides the ability to inject artificial errors to
1936	  netdevice notifier chain callbacks.  It is controlled through debugfs
1937	  interface /sys/kernel/debug/notifier-error-inject/netdev
1938
1939	  If the notifier call chain should be failed with some events
1940	  notified, write the error code to "actions/<notifier event>/error".
1941
1942	  Example: Inject netdevice mtu change error (-22 = -EINVAL)
1943
1944	  # cd /sys/kernel/debug/notifier-error-inject/netdev
1945	  # echo -22 > actions/NETDEV_CHANGEMTU/error
1946	  # ip link set eth0 mtu 1024
1947	  RTNETLINK answers: Invalid argument
1948
1949	  To compile this code as a module, choose M here: the module will
1950	  be called netdev-notifier-error-inject.
1951
1952	  If unsure, say N.
1953
1954config FUNCTION_ERROR_INJECTION
1955	bool "Fault-injections of functions"
1956	depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
1957	help
1958	  Add fault injections into various functions that are annotated with
1959	  ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return
1960	  value of these functions. This is useful to test error paths of code.
1961
1962	  If unsure, say N
1963
1964config FAULT_INJECTION
1965	bool "Fault-injection framework"
1966	depends on DEBUG_KERNEL
1967	help
1968	  Provide fault-injection framework.
1969	  For more details, see Documentation/fault-injection/.
1970
1971config FAILSLAB
1972	bool "Fault-injection capability for kmalloc"
1973	depends on FAULT_INJECTION
1974	depends on SLAB || SLUB
1975	help
1976	  Provide fault-injection capability for kmalloc.
1977
1978config FAIL_PAGE_ALLOC
1979	bool "Fault-injection capability for alloc_pages()"
1980	depends on FAULT_INJECTION
1981	help
1982	  Provide fault-injection capability for alloc_pages().
1983
1984config FAULT_INJECTION_USERCOPY
1985	bool "Fault injection capability for usercopy functions"
1986	depends on FAULT_INJECTION
1987	help
1988	  Provides fault-injection capability to inject failures
1989	  in usercopy functions (copy_from_user(), get_user(), ...).
1990
1991config FAIL_MAKE_REQUEST
1992	bool "Fault-injection capability for disk IO"
1993	depends on FAULT_INJECTION && BLOCK
1994	help
1995	  Provide fault-injection capability for disk IO.
1996
1997config FAIL_IO_TIMEOUT
1998	bool "Fault-injection capability for faking disk interrupts"
1999	depends on FAULT_INJECTION && BLOCK
2000	help
2001	  Provide fault-injection capability on end IO handling. This
2002	  will make the block layer "forget" an interrupt as configured,
2003	  thus exercising the error handling.
2004
2005	  Only works with drivers that use the generic timeout handling,
2006	  for others it won't do anything.
2007
2008config FAIL_FUTEX
2009	bool "Fault-injection capability for futexes"
2010	select DEBUG_FS
2011	depends on FAULT_INJECTION && FUTEX
2012	help
2013	  Provide fault-injection capability for futexes.
2014
2015config FAULT_INJECTION_DEBUG_FS
2016	bool "Debugfs entries for fault-injection capabilities"
2017	depends on FAULT_INJECTION && SYSFS && DEBUG_FS
2018	help
2019	  Enable configuration of fault-injection capabilities via debugfs.
2020
2021config FAIL_FUNCTION
2022	bool "Fault-injection capability for functions"
2023	depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
2024	help
2025	  Provide function-based fault-injection capability.
2026	  This will allow you to override a specific function with a return
2027	  with given return value. As a result, function caller will see
2028	  an error value and have to handle it. This is useful to test the
2029	  error handling in various subsystems.
2030
2031config FAIL_MMC_REQUEST
2032	bool "Fault-injection capability for MMC IO"
2033	depends on FAULT_INJECTION_DEBUG_FS && MMC
2034	help
2035	  Provide fault-injection capability for MMC IO.
2036	  This will make the mmc core return data errors. This is
2037	  useful to test the error handling in the mmc block device
2038	  and to test how the mmc host driver handles retries from
2039	  the block device.
2040
2041config FAIL_SUNRPC
2042	bool "Fault-injection capability for SunRPC"
2043	depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG
2044	help
2045	  Provide fault-injection capability for SunRPC and
2046	  its consumers.
2047
2048config FAULT_INJECTION_CONFIGFS
2049	bool "Configfs interface for fault-injection capabilities"
2050	depends on FAULT_INJECTION
2051	select CONFIGFS_FS
2052	help
2053	  This option allows configfs-based drivers to dynamically configure
2054	  fault-injection via configfs.  Each parameter for driver-specific
2055	  fault-injection can be made visible as a configfs attribute in a
2056	  configfs group.
2057
2058
2059config FAULT_INJECTION_STACKTRACE_FILTER
2060	bool "stacktrace filter for fault-injection capabilities"
2061	depends on FAULT_INJECTION
2062	depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT
2063	select STACKTRACE
2064	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
2065	help
2066	  Provide stacktrace filter for fault-injection capabilities
2067
2068config ARCH_HAS_KCOV
2069	bool
2070	help
2071	  An architecture should select this when it can successfully
2072	  build and run with CONFIG_KCOV. This typically requires
2073	  disabling instrumentation for some early boot code.
2074
2075config CC_HAS_SANCOV_TRACE_PC
2076	def_bool $(cc-option,-fsanitize-coverage=trace-pc)
2077
2078
2079config KCOV
2080	bool "Code coverage for fuzzing"
2081	depends on ARCH_HAS_KCOV
2082	depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
2083	depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \
2084		   GCC_VERSION >= 120000 || CLANG_VERSION >= 130000
2085	select DEBUG_FS
2086	select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
2087	select OBJTOOL if HAVE_NOINSTR_HACK
2088	help
2089	  KCOV exposes kernel code coverage information in a form suitable
2090	  for coverage-guided fuzzing (randomized testing).
2091
2092	  If RANDOMIZE_BASE is enabled, PC values will not be stable across
2093	  different machines and across reboots. If you need stable PC values,
2094	  disable RANDOMIZE_BASE.
2095
2096	  For more details, see Documentation/dev-tools/kcov.rst.
2097
2098config KCOV_ENABLE_COMPARISONS
2099	bool "Enable comparison operands collection by KCOV"
2100	depends on KCOV
2101	depends on $(cc-option,-fsanitize-coverage=trace-cmp)
2102	help
2103	  KCOV also exposes operands of every comparison in the instrumented
2104	  code along with operand sizes and PCs of the comparison instructions.
2105	  These operands can be used by fuzzing engines to improve the quality
2106	  of fuzzing coverage.
2107
2108config KCOV_INSTRUMENT_ALL
2109	bool "Instrument all code by default"
2110	depends on KCOV
2111	default y
2112	help
2113	  If you are doing generic system call fuzzing (like e.g. syzkaller),
2114	  then you will want to instrument the whole kernel and you should
2115	  say y here. If you are doing more targeted fuzzing (like e.g.
2116	  filesystem fuzzing with AFL) then you will want to enable coverage
2117	  for more specific subsets of files, and should say n here.
2118
2119config KCOV_IRQ_AREA_SIZE
2120	hex "Size of interrupt coverage collection area in words"
2121	depends on KCOV
2122	default 0x40000
2123	help
2124	  KCOV uses preallocated per-cpu areas to collect coverage from
2125	  soft interrupts. This specifies the size of those areas in the
2126	  number of unsigned long words.
2127
2128menuconfig RUNTIME_TESTING_MENU
2129	bool "Runtime Testing"
2130	def_bool y
2131
2132if RUNTIME_TESTING_MENU
2133
2134config TEST_DHRY
2135	tristate "Dhrystone benchmark test"
2136	help
2137	  Enable this to include the Dhrystone 2.1 benchmark.  This test
2138	  calculates the number of Dhrystones per second, and the number of
2139	  DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided
2140	  by 1757 (the number of Dhrystones per second obtained on the VAX
2141	  11/780, nominally a 1 MIPS machine).
2142
2143	  To run the benchmark, it needs to be enabled explicitly, either from
2144	  the kernel command line (when built-in), or from userspace (when
2145	  built-in or modular.
2146
2147	  Run once during kernel boot:
2148
2149	      test_dhry.run
2150
2151	  Set number of iterations from kernel command line:
2152
2153	      test_dhry.iterations=<n>
2154
2155	  Set number of iterations from userspace:
2156
2157	      echo <n> > /sys/module/test_dhry/parameters/iterations
2158
2159	  Trigger manual run from userspace:
2160
2161	      echo y > /sys/module/test_dhry/parameters/run
2162
2163	  If the number of iterations is <= 0, the test will devise a suitable
2164	  number of iterations (test runs for at least 2s) automatically.
2165	  This process takes ca. 4s.
2166
2167	  If unsure, say N.
2168
2169config LKDTM
2170	tristate "Linux Kernel Dump Test Tool Module"
2171	depends on DEBUG_FS
2172	help
2173	This module enables testing of the different dumping mechanisms by
2174	inducing system failures at predefined crash points.
2175	If you don't need it: say N
2176	Choose M here to compile this code as a module. The module will be
2177	called lkdtm.
2178
2179	Documentation on how to use the module can be found in
2180	Documentation/fault-injection/provoke-crashes.rst
2181
2182config CPUMASK_KUNIT_TEST
2183	tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS
2184	depends on KUNIT
2185	default KUNIT_ALL_TESTS
2186	help
2187	  Enable to turn on cpumask tests, running at boot or module load time.
2188
2189	  For more information on KUnit and unit tests in general, please refer
2190	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2191
2192	  If unsure, say N.
2193
2194config TEST_LIST_SORT
2195	tristate "Linked list sorting test" if !KUNIT_ALL_TESTS
2196	depends on KUNIT
2197	default KUNIT_ALL_TESTS
2198	help
2199	  Enable this to turn on 'list_sort()' function test. This test is
2200	  executed only once during system boot (so affects only boot time),
2201	  or at module load time.
2202
2203	  If unsure, say N.
2204
2205config TEST_MIN_HEAP
2206	tristate "Min heap test"
2207	depends on DEBUG_KERNEL || m
2208	help
2209	  Enable this to turn on min heap function tests. This test is
2210	  executed only once during system boot (so affects only boot time),
2211	  or at module load time.
2212
2213	  If unsure, say N.
2214
2215config TEST_SORT
2216	tristate "Array-based sort test" if !KUNIT_ALL_TESTS
2217	depends on KUNIT
2218	default KUNIT_ALL_TESTS
2219	help
2220	  This option enables the self-test function of 'sort()' at boot,
2221	  or at module load time.
2222
2223	  If unsure, say N.
2224
2225config TEST_DIV64
2226	tristate "64bit/32bit division and modulo test"
2227	depends on DEBUG_KERNEL || m
2228	help
2229	  Enable this to turn on 'do_div()' function test. This test is
2230	  executed only once during system boot (so affects only boot time),
2231	  or at module load time.
2232
2233	  If unsure, say N.
2234
2235config KPROBES_SANITY_TEST
2236	tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS
2237	depends on DEBUG_KERNEL
2238	depends on KPROBES
2239	depends on KUNIT
2240	select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
2241	default KUNIT_ALL_TESTS
2242	help
2243	  This option provides for testing basic kprobes functionality on
2244	  boot. Samples of kprobe and kretprobe are inserted and
2245	  verified for functionality.
2246
2247	  Say N if you are unsure.
2248
2249config FPROBE_SANITY_TEST
2250	bool "Self test for fprobe"
2251	depends on DEBUG_KERNEL
2252	depends on FPROBE
2253	depends on KUNIT=y
2254	help
2255	  This option will enable testing the fprobe when the system boot.
2256	  A series of tests are made to verify that the fprobe is functioning
2257	  properly.
2258
2259	  Say N if you are unsure.
2260
2261config BACKTRACE_SELF_TEST
2262	tristate "Self test for the backtrace code"
2263	depends on DEBUG_KERNEL
2264	help
2265	  This option provides a kernel module that can be used to test
2266	  the kernel stack backtrace code. This option is not useful
2267	  for distributions or general kernels, but only for kernel
2268	  developers working on architecture code.
2269
2270	  Note that if you want to also test saved backtraces, you will
2271	  have to enable STACKTRACE as well.
2272
2273	  Say N if you are unsure.
2274
2275config TEST_REF_TRACKER
2276	tristate "Self test for reference tracker"
2277	depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
2278	select REF_TRACKER
2279	help
2280	  This option provides a kernel module performing tests
2281	  using reference tracker infrastructure.
2282
2283	  Say N if you are unsure.
2284
2285config RBTREE_TEST
2286	tristate "Red-Black tree test"
2287	depends on DEBUG_KERNEL
2288	help
2289	  A benchmark measuring the performance of the rbtree library.
2290	  Also includes rbtree invariant checks.
2291
2292config REED_SOLOMON_TEST
2293	tristate "Reed-Solomon library test"
2294	depends on DEBUG_KERNEL || m
2295	select REED_SOLOMON
2296	select REED_SOLOMON_ENC16
2297	select REED_SOLOMON_DEC16
2298	help
2299	  This option enables the self-test function of rslib at boot,
2300	  or at module load time.
2301
2302	  If unsure, say N.
2303
2304config INTERVAL_TREE_TEST
2305	tristate "Interval tree test"
2306	depends on DEBUG_KERNEL
2307	select INTERVAL_TREE
2308	help
2309	  A benchmark measuring the performance of the interval tree library
2310
2311config PERCPU_TEST
2312	tristate "Per cpu operations test"
2313	depends on m && DEBUG_KERNEL
2314	help
2315	  Enable this option to build test module which validates per-cpu
2316	  operations.
2317
2318	  If unsure, say N.
2319
2320config ATOMIC64_SELFTEST
2321	tristate "Perform an atomic64_t self-test"
2322	help
2323	  Enable this option to test the atomic64_t functions at boot or
2324	  at module load time.
2325
2326	  If unsure, say N.
2327
2328config ASYNC_RAID6_TEST
2329	tristate "Self test for hardware accelerated raid6 recovery"
2330	depends on ASYNC_RAID6_RECOV
2331	select ASYNC_MEMCPY
2332	help
2333	  This is a one-shot self test that permutes through the
2334	  recovery of all the possible two disk failure scenarios for a
2335	  N-disk array.  Recovery is performed with the asynchronous
2336	  raid6 recovery routines, and will optionally use an offload
2337	  engine if one is available.
2338
2339	  If unsure, say N.
2340
2341config TEST_HEXDUMP
2342	tristate "Test functions located in the hexdump module at runtime"
2343
2344config STRING_SELFTEST
2345	tristate "Test string functions at runtime"
2346
2347config TEST_STRING_HELPERS
2348	tristate "Test functions located in the string_helpers module at runtime"
2349
2350config TEST_KSTRTOX
2351	tristate "Test kstrto*() family of functions at runtime"
2352
2353config TEST_PRINTF
2354	tristate "Test printf() family of functions at runtime"
2355
2356config TEST_SCANF
2357	tristate "Test scanf() family of functions at runtime"
2358
2359config TEST_BITMAP
2360	tristate "Test bitmap_*() family of functions at runtime"
2361	help
2362	  Enable this option to test the bitmap functions at boot.
2363
2364	  If unsure, say N.
2365
2366config TEST_UUID
2367	tristate "Test functions located in the uuid module at runtime"
2368
2369config TEST_XARRAY
2370	tristate "Test the XArray code at runtime"
2371
2372config TEST_MAPLE_TREE
2373	tristate "Test the Maple Tree code at runtime or module load"
2374	help
2375	  Enable this option to test the maple tree code functions at boot, or
2376	  when the module is loaded. Enable "Debug Maple Trees" will enable
2377	  more verbose output on failures.
2378
2379	  If unsure, say N.
2380
2381config TEST_RHASHTABLE
2382	tristate "Perform selftest on resizable hash table"
2383	help
2384	  Enable this option to test the rhashtable functions at boot.
2385
2386	  If unsure, say N.
2387
2388config TEST_IDA
2389	tristate "Perform selftest on IDA functions"
2390
2391config TEST_PARMAN
2392	tristate "Perform selftest on priority array manager"
2393	depends on PARMAN
2394	help
2395	  Enable this option to test priority array manager on boot
2396	  (or module load).
2397
2398	  If unsure, say N.
2399
2400config TEST_IRQ_TIMINGS
2401	bool "IRQ timings selftest"
2402	depends on IRQ_TIMINGS
2403	help
2404	  Enable this option to test the irq timings code on boot.
2405
2406	  If unsure, say N.
2407
2408config TEST_LKM
2409	tristate "Test module loading with 'hello world' module"
2410	depends on m
2411	help
2412	  This builds the "test_module" module that emits "Hello, world"
2413	  on printk when loaded. It is designed to be used for basic
2414	  evaluation of the module loading subsystem (for example when
2415	  validating module verification). It lacks any extra dependencies,
2416	  and will not normally be loaded by the system unless explicitly
2417	  requested by name.
2418
2419	  If unsure, say N.
2420
2421config TEST_BITOPS
2422	tristate "Test module for compilation of bitops operations"
2423	depends on m
2424	help
2425	  This builds the "test_bitops" module that is much like the
2426	  TEST_LKM module except that it does a basic exercise of the
2427	  set/clear_bit macros and get_count_order/long to make sure there are
2428	  no compiler warnings from C=1 sparse checker or -Wextra
2429	  compilations. It has no dependencies and doesn't run or load unless
2430	  explicitly requested by name.  for example: modprobe test_bitops.
2431
2432	  If unsure, say N.
2433
2434config TEST_VMALLOC
2435	tristate "Test module for stress/performance analysis of vmalloc allocator"
2436	default n
2437       depends on MMU
2438	depends on m
2439	help
2440	  This builds the "test_vmalloc" module that should be used for
2441	  stress and performance analysis. So, any new change for vmalloc
2442	  subsystem can be evaluated from performance and stability point
2443	  of view.
2444
2445	  If unsure, say N.
2446
2447config TEST_USER_COPY
2448	tristate "Test user/kernel boundary protections"
2449	depends on m
2450	help
2451	  This builds the "test_user_copy" module that runs sanity checks
2452	  on the copy_to/from_user infrastructure, making sure basic
2453	  user/kernel boundary testing is working. If it fails to load,
2454	  a regression has been detected in the user/kernel memory boundary
2455	  protections.
2456
2457	  If unsure, say N.
2458
2459config TEST_BPF
2460	tristate "Test BPF filter functionality"
2461	depends on m && NET
2462	help
2463	  This builds the "test_bpf" module that runs various test vectors
2464	  against the BPF interpreter or BPF JIT compiler depending on the
2465	  current setting. This is in particular useful for BPF JIT compiler
2466	  development, but also to run regression tests against changes in
2467	  the interpreter code. It also enables test stubs for eBPF maps and
2468	  verifier used by user space verifier testsuite.
2469
2470	  If unsure, say N.
2471
2472config TEST_BLACKHOLE_DEV
2473	tristate "Test blackhole netdev functionality"
2474	depends on m && NET
2475	help
2476	  This builds the "test_blackhole_dev" module that validates the
2477	  data path through this blackhole netdev.
2478
2479	  If unsure, say N.
2480
2481config FIND_BIT_BENCHMARK
2482	tristate "Test find_bit functions"
2483	help
2484	  This builds the "test_find_bit" module that measure find_*_bit()
2485	  functions performance.
2486
2487	  If unsure, say N.
2488
2489config TEST_FIRMWARE
2490	tristate "Test firmware loading via userspace interface"
2491	depends on FW_LOADER
2492	help
2493	  This builds the "test_firmware" module that creates a userspace
2494	  interface for testing firmware loading. This can be used to
2495	  control the triggering of firmware loading without needing an
2496	  actual firmware-using device. The contents can be rechecked by
2497	  userspace.
2498
2499	  If unsure, say N.
2500
2501config TEST_SYSCTL
2502	tristate "sysctl test driver"
2503	depends on PROC_SYSCTL
2504	help
2505	  This builds the "test_sysctl" module. This driver enables to test the
2506	  proc sysctl interfaces available to drivers safely without affecting
2507	  production knobs which might alter system functionality.
2508
2509	  If unsure, say N.
2510
2511config BITFIELD_KUNIT
2512	tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS
2513	depends on KUNIT
2514	default KUNIT_ALL_TESTS
2515	help
2516	  Enable this option to test the bitfield functions at boot.
2517
2518	  KUnit tests run during boot and output the results to the debug log
2519	  in TAP format (http://testanything.org/). Only useful for kernel devs
2520	  running the KUnit test harness, and not intended for inclusion into a
2521	  production build.
2522
2523	  For more information on KUnit and unit tests in general please refer
2524	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2525
2526	  If unsure, say N.
2527
2528config CHECKSUM_KUNIT
2529	tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS
2530	depends on KUNIT
2531	default KUNIT_ALL_TESTS
2532	help
2533	  Enable this option to test the checksum functions at boot.
2534
2535	  KUnit tests run during boot and output the results to the debug log
2536	  in TAP format (http://testanything.org/). Only useful for kernel devs
2537	  running the KUnit test harness, and not intended for inclusion into a
2538	  production build.
2539
2540	  For more information on KUnit and unit tests in general please refer
2541	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2542
2543	  If unsure, say N.
2544
2545config HASH_KUNIT_TEST
2546	tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS
2547	depends on KUNIT
2548	default KUNIT_ALL_TESTS
2549	help
2550	  Enable this option to test the kernel's string (<linux/stringhash.h>), and
2551	  integer (<linux/hash.h>) hash functions on boot.
2552
2553	  KUnit tests run during boot and output the results to the debug log
2554	  in TAP format (https://testanything.org/). Only useful for kernel devs
2555	  running the KUnit test harness, and not intended for inclusion into a
2556	  production build.
2557
2558	  For more information on KUnit and unit tests in general please refer
2559	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2560
2561	  This is intended to help people writing architecture-specific
2562	  optimized versions. If unsure, say N.
2563
2564config RESOURCE_KUNIT_TEST
2565	tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS
2566	depends on KUNIT
2567	default KUNIT_ALL_TESTS
2568	help
2569	  This builds the resource API unit test.
2570	  Tests the logic of API provided by resource.c and ioport.h.
2571	  For more information on KUnit and unit tests in general please refer
2572	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2573
2574	  If unsure, say N.
2575
2576config SYSCTL_KUNIT_TEST
2577	tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS
2578	depends on KUNIT
2579	default KUNIT_ALL_TESTS
2580	help
2581	  This builds the proc sysctl unit test, which runs on boot.
2582	  Tests the API contract and implementation correctness of sysctl.
2583	  For more information on KUnit and unit tests in general please refer
2584	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2585
2586	  If unsure, say N.
2587
2588config LIST_KUNIT_TEST
2589	tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS
2590	depends on KUNIT
2591	default KUNIT_ALL_TESTS
2592	help
2593	  This builds the linked list KUnit test suite.
2594	  It tests that the API and basic functionality of the list_head type
2595	  and associated macros.
2596
2597	  KUnit tests run during boot and output the results to the debug log
2598	  in TAP format (https://testanything.org/). Only useful for kernel devs
2599	  running the KUnit test harness, and not intended for inclusion into a
2600	  production build.
2601
2602	  For more information on KUnit and unit tests in general please refer
2603	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2604
2605	  If unsure, say N.
2606
2607config HASHTABLE_KUNIT_TEST
2608	tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS
2609	depends on KUNIT
2610	default KUNIT_ALL_TESTS
2611	help
2612	  This builds the hashtable KUnit test suite.
2613	  It tests the basic functionality of the API defined in
2614	  include/linux/hashtable.h. For more information on KUnit and
2615	  unit tests in general please refer to the KUnit documentation
2616	  in Documentation/dev-tools/kunit/.
2617
2618	  If unsure, say N.
2619
2620config LINEAR_RANGES_TEST
2621	tristate "KUnit test for linear_ranges"
2622	depends on KUNIT
2623	select LINEAR_RANGES
2624	help
2625	  This builds the linear_ranges unit test, which runs on boot.
2626	  Tests the linear_ranges logic correctness.
2627	  For more information on KUnit and unit tests in general please refer
2628	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2629
2630	  If unsure, say N.
2631
2632config CMDLINE_KUNIT_TEST
2633	tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS
2634	depends on KUNIT
2635	default KUNIT_ALL_TESTS
2636	help
2637	  This builds the cmdline API unit test.
2638	  Tests the logic of API provided by cmdline.c.
2639	  For more information on KUnit and unit tests in general please refer
2640	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2641
2642	  If unsure, say N.
2643
2644config BITS_TEST
2645	tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS
2646	depends on KUNIT
2647	default KUNIT_ALL_TESTS
2648	help
2649	  This builds the bits unit test.
2650	  Tests the logic of macros defined in bits.h.
2651	  For more information on KUnit and unit tests in general please refer
2652	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2653
2654	  If unsure, say N.
2655
2656config SLUB_KUNIT_TEST
2657	tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS
2658	depends on SLUB_DEBUG && KUNIT
2659	default KUNIT_ALL_TESTS
2660	help
2661	  This builds SLUB allocator unit test.
2662	  Tests SLUB cache debugging functionality.
2663	  For more information on KUnit and unit tests in general please refer
2664	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2665
2666	  If unsure, say N.
2667
2668config RATIONAL_KUNIT_TEST
2669	tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS
2670	depends on KUNIT && RATIONAL
2671	default KUNIT_ALL_TESTS
2672	help
2673	  This builds the rational math unit test.
2674	  For more information on KUnit and unit tests in general please refer
2675	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2676
2677	  If unsure, say N.
2678
2679config MEMCPY_KUNIT_TEST
2680	tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS
2681	depends on KUNIT
2682	default KUNIT_ALL_TESTS
2683	help
2684	  Builds unit tests for memcpy(), memmove(), and memset() functions.
2685	  For more information on KUnit and unit tests in general please refer
2686	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2687
2688	  If unsure, say N.
2689
2690config MEMCPY_SLOW_KUNIT_TEST
2691	bool "Include exhaustive memcpy tests"
2692	depends on MEMCPY_KUNIT_TEST
2693	default y
2694	help
2695	  Some memcpy tests are quite exhaustive in checking for overlaps
2696	  and bit ranges. These can be very slow, so they are split out
2697	  as a separate config, in case they need to be disabled.
2698
2699	  Note this config option will be replaced by the use of KUnit test
2700	  attributes.
2701
2702config IS_SIGNED_TYPE_KUNIT_TEST
2703	tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS
2704	depends on KUNIT
2705	default KUNIT_ALL_TESTS
2706	help
2707	  Builds unit tests for the is_signed_type() macro.
2708
2709	  For more information on KUnit and unit tests in general please refer
2710	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2711
2712	  If unsure, say N.
2713
2714config OVERFLOW_KUNIT_TEST
2715	tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS
2716	depends on KUNIT
2717	default KUNIT_ALL_TESTS
2718	help
2719	  Builds unit tests for the check_*_overflow(), size_*(), allocation, and
2720	  related functions.
2721
2722	  For more information on KUnit and unit tests in general please refer
2723	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2724
2725	  If unsure, say N.
2726
2727config STACKINIT_KUNIT_TEST
2728	tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS
2729	depends on KUNIT
2730	default KUNIT_ALL_TESTS
2731	help
2732	  Test if the kernel is zero-initializing stack variables and
2733	  padding. Coverage is controlled by compiler flags,
2734	  CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO,
2735	  CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2736	  or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2737
2738config FORTIFY_KUNIT_TEST
2739	tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS
2740	depends on KUNIT && FORTIFY_SOURCE
2741	default KUNIT_ALL_TESTS
2742	help
2743	  Builds unit tests for checking internals of FORTIFY_SOURCE as used
2744	  by the str*() and mem*() family of functions. For testing runtime
2745	  traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests.
2746
2747config HW_BREAKPOINT_KUNIT_TEST
2748	bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS
2749	depends on HAVE_HW_BREAKPOINT
2750	depends on KUNIT=y
2751	default KUNIT_ALL_TESTS
2752	help
2753	  Tests for hw_breakpoint constraints accounting.
2754
2755	  If unsure, say N.
2756
2757config STRCAT_KUNIT_TEST
2758	tristate "Test strcat() family of functions at runtime" if !KUNIT_ALL_TESTS
2759	depends on KUNIT
2760	default KUNIT_ALL_TESTS
2761
2762config STRSCPY_KUNIT_TEST
2763	tristate "Test strscpy*() family of functions at runtime" if !KUNIT_ALL_TESTS
2764	depends on KUNIT
2765	default KUNIT_ALL_TESTS
2766
2767config SIPHASH_KUNIT_TEST
2768	tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS
2769	depends on KUNIT
2770	default KUNIT_ALL_TESTS
2771	help
2772	  Enable this option to test the kernel's siphash (<linux/siphash.h>) hash
2773	  functions on boot (or module load).
2774
2775	  This is intended to help people writing architecture-specific
2776	  optimized versions.  If unsure, say N.
2777
2778config TEST_UDELAY
2779	tristate "udelay test driver"
2780	help
2781	  This builds the "udelay_test" module that helps to make sure
2782	  that udelay() is working properly.
2783
2784	  If unsure, say N.
2785
2786config TEST_STATIC_KEYS
2787	tristate "Test static keys"
2788	depends on m
2789	help
2790	  Test the static key interfaces.
2791
2792	  If unsure, say N.
2793
2794config TEST_DYNAMIC_DEBUG
2795	tristate "Test DYNAMIC_DEBUG"
2796	depends on DYNAMIC_DEBUG
2797	help
2798	  This module registers a tracer callback to count enabled
2799	  pr_debugs in a 'do_debugging' function, then alters their
2800	  enablements, calls the function, and compares counts.
2801
2802	  If unsure, say N.
2803
2804config TEST_KMOD
2805	tristate "kmod stress tester"
2806	depends on m
2807	depends on NETDEVICES && NET_CORE && INET # for TUN
2808	depends on BLOCK
2809	depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS
2810	select TEST_LKM
2811	select XFS_FS
2812	select TUN
2813	select BTRFS_FS
2814	help
2815	  Test the kernel's module loading mechanism: kmod. kmod implements
2816	  support to load modules using the Linux kernel's usermode helper.
2817	  This test provides a series of tests against kmod.
2818
2819	  Although technically you can either build test_kmod as a module or
2820	  into the kernel we disallow building it into the kernel since
2821	  it stress tests request_module() and this will very likely cause
2822	  some issues by taking over precious threads available from other
2823	  module load requests, ultimately this could be fatal.
2824
2825	  To run tests run:
2826
2827	  tools/testing/selftests/kmod/kmod.sh --help
2828
2829	  If unsure, say N.
2830
2831config TEST_DEBUG_VIRTUAL
2832	tristate "Test CONFIG_DEBUG_VIRTUAL feature"
2833	depends on DEBUG_VIRTUAL
2834	help
2835	  Test the kernel's ability to detect incorrect calls to
2836	  virt_to_phys() done against the non-linear part of the
2837	  kernel's virtual address map.
2838
2839	  If unsure, say N.
2840
2841config TEST_MEMCAT_P
2842	tristate "Test memcat_p() helper function"
2843	help
2844	  Test the memcat_p() helper for correctly merging two
2845	  pointer arrays together.
2846
2847	  If unsure, say N.
2848
2849config TEST_LIVEPATCH
2850	tristate "Test livepatching"
2851	default n
2852	depends on DYNAMIC_DEBUG
2853	depends on LIVEPATCH
2854	depends on m
2855	help
2856	  Test kernel livepatching features for correctness.  The tests will
2857	  load test modules that will be livepatched in various scenarios.
2858
2859	  To run all the livepatching tests:
2860
2861	  make -C tools/testing/selftests TARGETS=livepatch run_tests
2862
2863	  Alternatively, individual tests may be invoked:
2864
2865	  tools/testing/selftests/livepatch/test-callbacks.sh
2866	  tools/testing/selftests/livepatch/test-livepatch.sh
2867	  tools/testing/selftests/livepatch/test-shadow-vars.sh
2868
2869	  If unsure, say N.
2870
2871config TEST_OBJAGG
2872	tristate "Perform selftest on object aggreration manager"
2873	default n
2874	depends on OBJAGG
2875	help
2876	  Enable this option to test object aggregation manager on boot
2877	  (or module load).
2878
2879config TEST_MEMINIT
2880	tristate "Test heap/page initialization"
2881	help
2882	  Test if the kernel is zero-initializing heap and page allocations.
2883	  This can be useful to test init_on_alloc and init_on_free features.
2884
2885	  If unsure, say N.
2886
2887config TEST_HMM
2888	tristate "Test HMM (Heterogeneous Memory Management)"
2889	depends on TRANSPARENT_HUGEPAGE
2890	depends on DEVICE_PRIVATE
2891	select HMM_MIRROR
2892	select MMU_NOTIFIER
2893	help
2894	  This is a pseudo device driver solely for testing HMM.
2895	  Say M here if you want to build the HMM test module.
2896	  Doing so will allow you to run tools/testing/selftest/vm/hmm-tests.
2897
2898	  If unsure, say N.
2899
2900config TEST_FREE_PAGES
2901	tristate "Test freeing pages"
2902	help
2903	  Test that a memory leak does not occur due to a race between
2904	  freeing a block of pages and a speculative page reference.
2905	  Loading this module is safe if your kernel has the bug fixed.
2906	  If the bug is not fixed, it will leak gigabytes of memory and
2907	  probably OOM your system.
2908
2909config TEST_FPU
2910	tristate "Test floating point operations in kernel space"
2911	depends on X86 && !KCOV_INSTRUMENT_ALL
2912	help
2913	  Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu
2914	  which will trigger a sequence of floating point operations. This is used
2915	  for self-testing floating point control register setting in
2916	  kernel_fpu_begin().
2917
2918	  If unsure, say N.
2919
2920config TEST_CLOCKSOURCE_WATCHDOG
2921	tristate "Test clocksource watchdog in kernel space"
2922	depends on CLOCKSOURCE_WATCHDOG
2923	help
2924	  Enable this option to create a kernel module that will trigger
2925	  a test of the clocksource watchdog.  This module may be loaded
2926	  via modprobe or insmod in which case it will run upon being
2927	  loaded, or it may be built in, in which case it will run
2928	  shortly after boot.
2929
2930	  If unsure, say N.
2931
2932endif # RUNTIME_TESTING_MENU
2933
2934config ARCH_USE_MEMTEST
2935	bool
2936	help
2937	  An architecture should select this when it uses early_memtest()
2938	  during boot process.
2939
2940config MEMTEST
2941	bool "Memtest"
2942	depends on ARCH_USE_MEMTEST
2943	help
2944	  This option adds a kernel parameter 'memtest', which allows memtest
2945	  to be set and executed.
2946	        memtest=0, mean disabled; -- default
2947	        memtest=1, mean do 1 test pattern;
2948	        ...
2949	        memtest=17, mean do 17 test patterns.
2950	  If you are unsure how to answer this question, answer N.
2951
2952
2953
2954config HYPERV_TESTING
2955	bool "Microsoft Hyper-V driver testing"
2956	default n
2957	depends on HYPERV && DEBUG_FS
2958	help
2959	  Select this option to enable Hyper-V vmbus testing.
2960
2961endmenu # "Kernel Testing and Coverage"
2962
2963menu "Rust hacking"
2964
2965config RUST_DEBUG_ASSERTIONS
2966	bool "Debug assertions"
2967	depends on RUST
2968	help
2969	  Enables rustc's `-Cdebug-assertions` codegen option.
2970
2971	  This flag lets you turn `cfg(debug_assertions)` conditional
2972	  compilation on or off. This can be used to enable extra debugging
2973	  code in development but not in production. For example, it controls
2974	  the behavior of the standard library's `debug_assert!` macro.
2975
2976	  Note that this will apply to all Rust code, including `core`.
2977
2978	  If unsure, say N.
2979
2980config RUST_OVERFLOW_CHECKS
2981	bool "Overflow checks"
2982	default y
2983	depends on RUST
2984	help
2985	  Enables rustc's `-Coverflow-checks` codegen option.
2986
2987	  This flag allows you to control the behavior of runtime integer
2988	  overflow. When overflow-checks are enabled, a Rust panic will occur
2989	  on overflow.
2990
2991	  Note that this will apply to all Rust code, including `core`.
2992
2993	  If unsure, say Y.
2994
2995config RUST_BUILD_ASSERT_ALLOW
2996	bool "Allow unoptimized build-time assertions"
2997	depends on RUST
2998	help
2999	  Controls how are `build_error!` and `build_assert!` handled during build.
3000
3001	  If calls to them exist in the binary, it may indicate a violated invariant
3002	  or that the optimizer failed to verify the invariant during compilation.
3003
3004	  This should not happen, thus by default the build is aborted. However,
3005	  as an escape hatch, you can choose Y here to ignore them during build
3006	  and let the check be carried at runtime (with `panic!` being called if
3007	  the check fails).
3008
3009	  If unsure, say N.
3010
3011config RUST_KERNEL_DOCTESTS
3012	bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS
3013	depends on RUST && KUNIT=y
3014	default KUNIT_ALL_TESTS
3015	help
3016	  This builds the documentation tests of the `kernel` crate
3017	  as KUnit tests.
3018
3019	  For more information on KUnit and unit tests in general,
3020	  please refer to the KUnit documentation in Documentation/dev-tools/kunit/.
3021
3022	  If unsure, say N.
3023
3024endmenu # "Rust"
3025
3026endmenu # Kernel hacking
3027