xref: /linux/lib/Kconfig.debug (revision 34dc1baba215b826e454b8d19e4f24adbeb7d00d)
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	# RISC-V linker relaxation + -gsplit-dwarf has issues with LLVM and GCC
359	# prior to 12.x:
360	# https://github.com/llvm/llvm-project/issues/56642
361	# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99090
362	depends on !RISCV || GCC_VERSION >= 120000
363	help
364	  Generate debug info into separate .dwo files. This significantly
365	  reduces the build directory size for builds with DEBUG_INFO,
366	  because it stores the information only once on disk in .dwo
367	  files instead of multiple times in object files and executables.
368	  In addition the debug information is also compressed.
369
370	  Requires recent gcc (4.7+) and recent gdb/binutils.
371	  Any tool that packages or reads debug information would need
372	  to know about the .dwo files and include them.
373	  Incompatible with older versions of ccache.
374
375config DEBUG_INFO_BTF
376	bool "Generate BTF typeinfo"
377	depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED
378	depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST
379	depends on BPF_SYSCALL
380	depends on !DEBUG_INFO_DWARF5 || PAHOLE_VERSION >= 121
381	help
382	  Generate deduplicated BTF type information from DWARF debug info.
383	  Turning this on expects presence of pahole tool, which will convert
384	  DWARF type info into equivalent deduplicated BTF type info.
385
386config PAHOLE_HAS_SPLIT_BTF
387	def_bool PAHOLE_VERSION >= 119
388
389config PAHOLE_HAS_BTF_TAG
390	def_bool PAHOLE_VERSION >= 123
391	depends on CC_IS_CLANG
392	help
393	  Decide whether pahole emits btf_tag attributes (btf_type_tag and
394	  btf_decl_tag) or not. Currently only clang compiler implements
395	  these attributes, so make the config depend on CC_IS_CLANG.
396
397config PAHOLE_HAS_LANG_EXCLUDE
398	def_bool PAHOLE_VERSION >= 124
399	help
400	  Support for the --lang_exclude flag which makes pahole exclude
401	  compilation units from the supplied language. Used in Kbuild to
402	  omit Rust CUs which are not supported in version 1.24 of pahole,
403	  otherwise it would emit malformed kernel and module binaries when
404	  using DEBUG_INFO_BTF_MODULES.
405
406config DEBUG_INFO_BTF_MODULES
407	def_bool y
408	depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF
409	help
410	  Generate compact split BTF type information for kernel modules.
411
412config MODULE_ALLOW_BTF_MISMATCH
413	bool "Allow loading modules with non-matching BTF type info"
414	depends on DEBUG_INFO_BTF_MODULES
415	help
416	  For modules whose split BTF does not match vmlinux, load without
417	  BTF rather than refusing to load. The default behavior with
418	  module BTF enabled is to reject modules with such mismatches;
419	  this option will still load module BTF where possible but ignore
420	  it when a mismatch is found.
421
422config GDB_SCRIPTS
423	bool "Provide GDB scripts for kernel debugging"
424	help
425	  This creates the required links to GDB helper scripts in the
426	  build directory. If you load vmlinux into gdb, the helper
427	  scripts will be automatically imported by gdb as well, and
428	  additional functions are available to analyze a Linux kernel
429	  instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
430	  for further details.
431
432endif # DEBUG_INFO
433
434config FRAME_WARN
435	int "Warn for stack frames larger than"
436	range 0 8192
437	default 0 if KMSAN
438	default 2048 if GCC_PLUGIN_LATENT_ENTROPY
439	default 2048 if PARISC
440	default 1536 if (!64BIT && XTENSA)
441	default 1280 if KASAN && !64BIT
442	default 1024 if !64BIT
443	default 2048 if 64BIT
444	help
445	  Tell the compiler to warn at build time for stack frames larger than this.
446	  Setting this too low will cause a lot of warnings.
447	  Setting it to 0 disables the warning.
448
449config STRIP_ASM_SYMS
450	bool "Strip assembler-generated symbols during link"
451	default n
452	help
453	  Strip internal assembler-generated symbols during a link (symbols
454	  that look like '.Lxxx') so they don't pollute the output of
455	  get_wchan() and suchlike.
456
457config READABLE_ASM
458	bool "Generate readable assembler code"
459	depends on DEBUG_KERNEL
460	depends on CC_IS_GCC
461	help
462	  Disable some compiler optimizations that tend to generate human unreadable
463	  assembler output. This may make the kernel slightly slower, but it helps
464	  to keep kernel developers who have to stare a lot at assembler listings
465	  sane.
466
467config HEADERS_INSTALL
468	bool "Install uapi headers to usr/include"
469	depends on !UML
470	help
471	  This option will install uapi headers (headers exported to user-space)
472	  into the usr/include directory for use during the kernel build.
473	  This is unneeded for building the kernel itself, but needed for some
474	  user-space program samples. It is also needed by some features such
475	  as uapi header sanity checks.
476
477config DEBUG_SECTION_MISMATCH
478	bool "Enable full Section mismatch analysis"
479	depends on CC_IS_GCC
480	help
481	  The section mismatch analysis checks if there are illegal
482	  references from one section to another section.
483	  During linktime or runtime, some sections are dropped;
484	  any use of code/data previously in these sections would
485	  most likely result in an oops.
486	  In the code, functions and variables are annotated with
487	  __init,, etc. (see the full list in include/linux/init.h),
488	  which results in the code/data being placed in specific sections.
489	  The section mismatch analysis is always performed after a full
490	  kernel build, and enabling this option causes the following
491	  additional step to occur:
492	  - Add the option -fno-inline-functions-called-once to gcc commands.
493	    When inlining a function annotated with __init in a non-init
494	    function, we would lose the section information and thus
495	    the analysis would not catch the illegal reference.
496	    This option tells gcc to inline less (but it does result in
497	    a larger kernel).
498
499config SECTION_MISMATCH_WARN_ONLY
500	bool "Make section mismatch errors non-fatal"
501	default y
502	help
503	  If you say N here, the build process will fail if there are any
504	  section mismatch, instead of just throwing warnings.
505
506	  If unsure, say Y.
507
508config DEBUG_FORCE_FUNCTION_ALIGN_64B
509	bool "Force all function address 64B aligned"
510	depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC || RISCV || S390)
511	select FUNCTION_ALIGNMENT_64B
512	help
513	  There are cases that a commit from one domain changes the function
514	  address alignment of other domains, and cause magic performance
515	  bump (regression or improvement). Enable this option will help to
516	  verify if the bump is caused by function alignment changes, while
517	  it will slightly increase the kernel size and affect icache usage.
518
519	  It is mainly for debug and performance tuning use.
520
521#
522# Select this config option from the architecture Kconfig, if it
523# is preferred to always offer frame pointers as a config
524# option on the architecture (regardless of KERNEL_DEBUG):
525#
526config ARCH_WANT_FRAME_POINTERS
527	bool
528
529config FRAME_POINTER
530	bool "Compile the kernel with frame pointers"
531	depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
532	default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
533	help
534	  If you say Y here the resulting kernel image will be slightly
535	  larger and slower, but it gives very useful debugging information
536	  in case of kernel bugs. (precise oopses/stacktraces/warnings)
537
538config OBJTOOL
539	bool
540
541config STACK_VALIDATION
542	bool "Compile-time stack metadata validation"
543	depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER
544	select OBJTOOL
545	default n
546	help
547	  Validate frame pointer rules at compile-time.  This helps ensure that
548	  runtime stack traces are more reliable.
549
550	  For more information, see
551	  tools/objtool/Documentation/objtool.txt.
552
553config NOINSTR_VALIDATION
554	bool
555	depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY
556	select OBJTOOL
557	default y
558
559config VMLINUX_MAP
560	bool "Generate vmlinux.map file when linking"
561	depends on EXPERT
562	help
563	  Selecting this option will pass "-Map=vmlinux.map" to ld
564	  when linking vmlinux. That file can be useful for verifying
565	  and debugging magic section games, and for seeing which
566	  pieces of code get eliminated with
567	  CONFIG_LD_DEAD_CODE_DATA_ELIMINATION.
568
569config DEBUG_FORCE_WEAK_PER_CPU
570	bool "Force weak per-cpu definitions"
571	depends on DEBUG_KERNEL
572	help
573	  s390 and alpha require percpu variables in modules to be
574	  defined weak to work around addressing range issue which
575	  puts the following two restrictions on percpu variable
576	  definitions.
577
578	  1. percpu symbols must be unique whether static or not
579	  2. percpu variables can't be defined inside a function
580
581	  To ensure that generic code follows the above rules, this
582	  option forces all percpu variables to be defined as weak.
583
584endmenu # "Compiler options"
585
586menu "Generic Kernel Debugging Instruments"
587
588config MAGIC_SYSRQ
589	bool "Magic SysRq key"
590	depends on !UML
591	help
592	  If you say Y here, you will have some control over the system even
593	  if the system crashes for example during kernel debugging (e.g., you
594	  will be able to flush the buffer cache to disk, reboot the system
595	  immediately or dump some status information). This is accomplished
596	  by pressing various keys while holding SysRq (Alt+PrintScreen). It
597	  also works on a serial console (on PC hardware at least), if you
598	  send a BREAK and then within 5 seconds a command keypress. The
599	  keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
600	  Don't say Y unless you really know what this hack does.
601
602config MAGIC_SYSRQ_DEFAULT_ENABLE
603	hex "Enable magic SysRq key functions by default"
604	depends on MAGIC_SYSRQ
605	default 0x1
606	help
607	  Specifies which SysRq key functions are enabled by default.
608	  This may be set to 1 or 0 to enable or disable them all, or
609	  to a bitmask as described in Documentation/admin-guide/sysrq.rst.
610
611config MAGIC_SYSRQ_SERIAL
612	bool "Enable magic SysRq key over serial"
613	depends on MAGIC_SYSRQ
614	default y
615	help
616	  Many embedded boards have a disconnected TTL level serial which can
617	  generate some garbage that can lead to spurious false sysrq detects.
618	  This option allows you to decide whether you want to enable the
619	  magic SysRq key.
620
621config MAGIC_SYSRQ_SERIAL_SEQUENCE
622	string "Char sequence that enables magic SysRq over serial"
623	depends on MAGIC_SYSRQ_SERIAL
624	default ""
625	help
626	  Specifies a sequence of characters that can follow BREAK to enable
627	  SysRq on a serial console.
628
629	  If unsure, leave an empty string and the option will not be enabled.
630
631config DEBUG_FS
632	bool "Debug Filesystem"
633	help
634	  debugfs is a virtual file system that kernel developers use to put
635	  debugging files into.  Enable this option to be able to read and
636	  write to these files.
637
638	  For detailed documentation on the debugfs API, see
639	  Documentation/filesystems/.
640
641	  If unsure, say N.
642
643choice
644	prompt "Debugfs default access"
645	depends on DEBUG_FS
646	default DEBUG_FS_ALLOW_ALL
647	help
648	  This selects the default access restrictions for debugfs.
649	  It can be overridden with kernel command line option
650	  debugfs=[on,no-mount,off]. The restrictions apply for API access
651	  and filesystem registration.
652
653config DEBUG_FS_ALLOW_ALL
654	bool "Access normal"
655	help
656	  No restrictions apply. Both API and filesystem registration
657	  is on. This is the normal default operation.
658
659config DEBUG_FS_DISALLOW_MOUNT
660	bool "Do not register debugfs as filesystem"
661	help
662	  The API is open but filesystem is not loaded. Clients can still do
663	  their work and read with debug tools that do not need
664	  debugfs filesystem.
665
666config DEBUG_FS_ALLOW_NONE
667	bool "No access"
668	help
669	  Access is off. Clients get -PERM when trying to create nodes in
670	  debugfs tree and debugfs is not registered as a filesystem.
671	  Client can then back-off or continue without debugfs access.
672
673endchoice
674
675source "lib/Kconfig.kgdb"
676source "lib/Kconfig.ubsan"
677source "lib/Kconfig.kcsan"
678
679endmenu
680
681menu "Networking Debugging"
682
683source "net/Kconfig.debug"
684
685endmenu # "Networking Debugging"
686
687menu "Memory Debugging"
688
689source "mm/Kconfig.debug"
690
691config DEBUG_OBJECTS
692	bool "Debug object operations"
693	depends on DEBUG_KERNEL
694	help
695	  If you say Y here, additional code will be inserted into the
696	  kernel to track the life time of various objects and validate
697	  the operations on those objects.
698
699config DEBUG_OBJECTS_SELFTEST
700	bool "Debug objects selftest"
701	depends on DEBUG_OBJECTS
702	help
703	  This enables the selftest of the object debug code.
704
705config DEBUG_OBJECTS_FREE
706	bool "Debug objects in freed memory"
707	depends on DEBUG_OBJECTS
708	help
709	  This enables checks whether a k/v free operation frees an area
710	  which contains an object which has not been deactivated
711	  properly. This can make kmalloc/kfree-intensive workloads
712	  much slower.
713
714config DEBUG_OBJECTS_TIMERS
715	bool "Debug timer objects"
716	depends on DEBUG_OBJECTS
717	help
718	  If you say Y here, additional code will be inserted into the
719	  timer routines to track the life time of timer objects and
720	  validate the timer operations.
721
722config DEBUG_OBJECTS_WORK
723	bool "Debug work objects"
724	depends on DEBUG_OBJECTS
725	help
726	  If you say Y here, additional code will be inserted into the
727	  work queue routines to track the life time of work objects and
728	  validate the work operations.
729
730config DEBUG_OBJECTS_RCU_HEAD
731	bool "Debug RCU callbacks objects"
732	depends on DEBUG_OBJECTS
733	help
734	  Enable this to turn on debugging of RCU list heads (call_rcu() usage).
735
736config DEBUG_OBJECTS_PERCPU_COUNTER
737	bool "Debug percpu counter objects"
738	depends on DEBUG_OBJECTS
739	help
740	  If you say Y here, additional code will be inserted into the
741	  percpu counter routines to track the life time of percpu counter
742	  objects and validate the percpu counter operations.
743
744config DEBUG_OBJECTS_ENABLE_DEFAULT
745	int "debug_objects bootup default value (0-1)"
746	range 0 1
747	default "1"
748	depends on DEBUG_OBJECTS
749	help
750	  Debug objects boot parameter default value
751
752config SHRINKER_DEBUG
753	bool "Enable shrinker debugging support"
754	depends on DEBUG_FS
755	help
756	  Say Y to enable the shrinker debugfs interface which provides
757	  visibility into the kernel memory shrinkers subsystem.
758	  Disable it to avoid an extra memory footprint.
759
760config DEBUG_STACK_USAGE
761	bool "Stack utilization instrumentation"
762	depends on DEBUG_KERNEL && !IA64
763	help
764	  Enables the display of the minimum amount of free stack which each
765	  task has ever had available in the sysrq-T and sysrq-P debug output.
766
767	  This option will slow down process creation somewhat.
768
769config SCHED_STACK_END_CHECK
770	bool "Detect stack corruption on calls to schedule()"
771	depends on DEBUG_KERNEL
772	default n
773	help
774	  This option checks for a stack overrun on calls to schedule().
775	  If the stack end location is found to be over written always panic as
776	  the content of the corrupted region can no longer be trusted.
777	  This is to ensure no erroneous behaviour occurs which could result in
778	  data corruption or a sporadic crash at a later stage once the region
779	  is examined. The runtime overhead introduced is minimal.
780
781config ARCH_HAS_DEBUG_VM_PGTABLE
782	bool
783	help
784	  An architecture should select this when it can successfully
785	  build and run DEBUG_VM_PGTABLE.
786
787config DEBUG_VM_IRQSOFF
788	def_bool DEBUG_VM && !PREEMPT_RT
789
790config DEBUG_VM
791	bool "Debug VM"
792	depends on DEBUG_KERNEL
793	help
794	  Enable this to turn on extended checks in the virtual-memory system
795	  that may impact performance.
796
797	  If unsure, say N.
798
799config DEBUG_VM_SHOOT_LAZIES
800	bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation"
801	depends on DEBUG_VM
802	depends on MMU_LAZY_TLB_SHOOTDOWN
803	help
804	  Enable additional IPIs that ensure lazy tlb mm references are removed
805	  before the mm is freed.
806
807	  If unsure, say N.
808
809config DEBUG_VM_MAPLE_TREE
810	bool "Debug VM maple trees"
811	depends on DEBUG_VM
812	select DEBUG_MAPLE_TREE
813	help
814	  Enable VM maple tree debugging information and extra validations.
815
816	  If unsure, say N.
817
818config DEBUG_VM_RB
819	bool "Debug VM red-black trees"
820	depends on DEBUG_VM
821	help
822	  Enable VM red-black tree debugging information and extra validations.
823
824	  If unsure, say N.
825
826config DEBUG_VM_PGFLAGS
827	bool "Debug page-flags operations"
828	depends on DEBUG_VM
829	help
830	  Enables extra validation on page flags operations.
831
832	  If unsure, say N.
833
834config DEBUG_VM_PGTABLE
835	bool "Debug arch page table for semantics compliance"
836	depends on MMU
837	depends on ARCH_HAS_DEBUG_VM_PGTABLE
838	default y if DEBUG_VM
839	help
840	  This option provides a debug method which can be used to test
841	  architecture page table helper functions on various platforms in
842	  verifying if they comply with expected generic MM semantics. This
843	  will help architecture code in making sure that any changes or
844	  new additions of these helpers still conform to expected
845	  semantics of the generic MM. Platforms will have to opt in for
846	  this through ARCH_HAS_DEBUG_VM_PGTABLE.
847
848	  If unsure, say N.
849
850config ARCH_HAS_DEBUG_VIRTUAL
851	bool
852
853config DEBUG_VIRTUAL
854	bool "Debug VM translations"
855	depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
856	help
857	  Enable some costly sanity checks in virtual to page code. This can
858	  catch mistakes with virt_to_page() and friends.
859
860	  If unsure, say N.
861
862config DEBUG_NOMMU_REGIONS
863	bool "Debug the global anon/private NOMMU mapping region tree"
864	depends on DEBUG_KERNEL && !MMU
865	help
866	  This option causes the global tree of anonymous and private mapping
867	  regions to be regularly checked for invalid topology.
868
869config DEBUG_MEMORY_INIT
870	bool "Debug memory initialisation" if EXPERT
871	default !EXPERT
872	help
873	  Enable this for additional checks during memory initialisation.
874	  The sanity checks verify aspects of the VM such as the memory model
875	  and other information provided by the architecture. Verbose
876	  information will be printed at KERN_DEBUG loglevel depending
877	  on the mminit_loglevel= command-line option.
878
879	  If unsure, say Y
880
881config MEMORY_NOTIFIER_ERROR_INJECT
882	tristate "Memory hotplug notifier error injection module"
883	depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION
884	help
885	  This option provides the ability to inject artificial errors to
886	  memory hotplug notifier chain callbacks.  It is controlled through
887	  debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
888
889	  If the notifier call chain should be failed with some events
890	  notified, write the error code to "actions/<notifier event>/error".
891
892	  Example: Inject memory hotplug offline error (-12 == -ENOMEM)
893
894	  # cd /sys/kernel/debug/notifier-error-inject/memory
895	  # echo -12 > actions/MEM_GOING_OFFLINE/error
896	  # echo offline > /sys/devices/system/memory/memoryXXX/state
897	  bash: echo: write error: Cannot allocate memory
898
899	  To compile this code as a module, choose M here: the module will
900	  be called memory-notifier-error-inject.
901
902	  If unsure, say N.
903
904config DEBUG_PER_CPU_MAPS
905	bool "Debug access to per_cpu maps"
906	depends on DEBUG_KERNEL
907	depends on SMP
908	help
909	  Say Y to verify that the per_cpu map being accessed has
910	  been set up. This adds a fair amount of code to kernel memory
911	  and decreases performance.
912
913	  Say N if unsure.
914
915config DEBUG_KMAP_LOCAL
916	bool "Debug kmap_local temporary mappings"
917	depends on DEBUG_KERNEL && KMAP_LOCAL
918	help
919	  This option enables additional error checking for the kmap_local
920	  infrastructure.  Disable for production use.
921
922config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
923	bool
924
925config DEBUG_KMAP_LOCAL_FORCE_MAP
926	bool "Enforce kmap_local temporary mappings"
927	depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
928	select KMAP_LOCAL
929	select DEBUG_KMAP_LOCAL
930	help
931	  This option enforces temporary mappings through the kmap_local
932	  mechanism for non-highmem pages and on non-highmem systems.
933	  Disable this for production systems!
934
935config DEBUG_HIGHMEM
936	bool "Highmem debugging"
937	depends on DEBUG_KERNEL && HIGHMEM
938	select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
939	select DEBUG_KMAP_LOCAL
940	help
941	  This option enables additional error checking for high memory
942	  systems.  Disable for production systems.
943
944config HAVE_DEBUG_STACKOVERFLOW
945	bool
946
947config DEBUG_STACKOVERFLOW
948	bool "Check for stack overflows"
949	depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
950	help
951	  Say Y here if you want to check for overflows of kernel, IRQ
952	  and exception stacks (if your architecture uses them). This
953	  option will show detailed messages if free stack space drops
954	  below a certain limit.
955
956	  These kinds of bugs usually occur when call-chains in the
957	  kernel get too deep, especially when interrupts are
958	  involved.
959
960	  Use this in cases where you see apparently random memory
961	  corruption, especially if it appears in 'struct thread_info'
962
963	  If in doubt, say "N".
964
965source "lib/Kconfig.kasan"
966source "lib/Kconfig.kfence"
967source "lib/Kconfig.kmsan"
968
969endmenu # "Memory Debugging"
970
971config DEBUG_SHIRQ
972	bool "Debug shared IRQ handlers"
973	depends on DEBUG_KERNEL
974	help
975	  Enable this to generate a spurious interrupt just before a shared
976	  interrupt handler is deregistered (generating one when registering
977	  is currently disabled). Drivers need to handle this correctly. Some
978	  don't and need to be caught.
979
980menu "Debug Oops, Lockups and Hangs"
981
982config PANIC_ON_OOPS
983	bool "Panic on Oops"
984	help
985	  Say Y here to enable the kernel to panic when it oopses. This
986	  has the same effect as setting oops=panic on the kernel command
987	  line.
988
989	  This feature is useful to ensure that the kernel does not do
990	  anything erroneous after an oops which could result in data
991	  corruption or other issues.
992
993	  Say N if unsure.
994
995config PANIC_ON_OOPS_VALUE
996	int
997	range 0 1
998	default 0 if !PANIC_ON_OOPS
999	default 1 if PANIC_ON_OOPS
1000
1001config PANIC_TIMEOUT
1002	int "panic timeout"
1003	default 0
1004	help
1005	  Set the timeout value (in seconds) until a reboot occurs when
1006	  the kernel panics. If n = 0, then we wait forever. A timeout
1007	  value n > 0 will wait n seconds before rebooting, while a timeout
1008	  value n < 0 will reboot immediately.
1009
1010config LOCKUP_DETECTOR
1011	bool
1012
1013config SOFTLOCKUP_DETECTOR
1014	bool "Detect Soft Lockups"
1015	depends on DEBUG_KERNEL && !S390
1016	select LOCKUP_DETECTOR
1017	help
1018	  Say Y here to enable the kernel to act as a watchdog to detect
1019	  soft lockups.
1020
1021	  Softlockups are bugs that cause the kernel to loop in kernel
1022	  mode for more than 20 seconds, without giving other tasks a
1023	  chance to run.  The current stack trace is displayed upon
1024	  detection and the system will stay locked up.
1025
1026config BOOTPARAM_SOFTLOCKUP_PANIC
1027	bool "Panic (Reboot) On Soft Lockups"
1028	depends on SOFTLOCKUP_DETECTOR
1029	help
1030	  Say Y here to enable the kernel to panic on "soft lockups",
1031	  which are bugs that cause the kernel to loop in kernel
1032	  mode for more than 20 seconds (configurable using the watchdog_thresh
1033	  sysctl), without giving other tasks a chance to run.
1034
1035	  The panic can be used in combination with panic_timeout,
1036	  to cause the system to reboot automatically after a
1037	  lockup has been detected. This feature is useful for
1038	  high-availability systems that have uptime guarantees and
1039	  where a lockup must be resolved ASAP.
1040
1041	  Say N if unsure.
1042
1043config HAVE_HARDLOCKUP_DETECTOR_BUDDY
1044	bool
1045	depends on SMP
1046	default y
1047
1048#
1049# Global switch whether to build a hardlockup detector at all. It is available
1050# only when the architecture supports at least one implementation. There are
1051# two exceptions. The hardlockup detector is never enabled on:
1052#
1053#	s390: it reported many false positives there
1054#
1055#	sparc64: has a custom implementation which is not using the common
1056#		hardlockup command line options and sysctl interface.
1057#
1058config HARDLOCKUP_DETECTOR
1059	bool "Detect Hard Lockups"
1060	depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64
1061	depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH
1062	imply HARDLOCKUP_DETECTOR_PERF
1063	imply HARDLOCKUP_DETECTOR_BUDDY
1064	imply HARDLOCKUP_DETECTOR_ARCH
1065	select LOCKUP_DETECTOR
1066
1067	help
1068	  Say Y here to enable the kernel to act as a watchdog to detect
1069	  hard lockups.
1070
1071	  Hardlockups are bugs that cause the CPU to loop in kernel mode
1072	  for more than 10 seconds, without letting other interrupts have a
1073	  chance to run.  The current stack trace is displayed upon detection
1074	  and the system will stay locked up.
1075
1076#
1077# Note that arch-specific variants are always preferred.
1078#
1079config HARDLOCKUP_DETECTOR_PREFER_BUDDY
1080	bool "Prefer the buddy CPU hardlockup detector"
1081	depends on HARDLOCKUP_DETECTOR
1082	depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY
1083	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1084	help
1085	  Say Y here to prefer the buddy hardlockup detector over the perf one.
1086
1087	  With the buddy detector, each CPU uses its softlockup hrtimer
1088	  to check that the next CPU is processing hrtimer interrupts by
1089	  verifying that a counter is increasing.
1090
1091	  This hardlockup detector is useful on systems that don't have
1092	  an arch-specific hardlockup detector or if resources needed
1093	  for the hardlockup detector are better used for other things.
1094
1095config HARDLOCKUP_DETECTOR_PERF
1096	bool
1097	depends on HARDLOCKUP_DETECTOR
1098	depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY
1099	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1100	select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1101
1102config HARDLOCKUP_DETECTOR_BUDDY
1103	bool
1104	depends on HARDLOCKUP_DETECTOR
1105	depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY
1106	depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY
1107	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1108	select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1109
1110config HARDLOCKUP_DETECTOR_ARCH
1111	bool
1112	depends on HARDLOCKUP_DETECTOR
1113	depends on HAVE_HARDLOCKUP_DETECTOR_ARCH
1114	help
1115	  The arch-specific implementation of the hardlockup detector will
1116	  be used.
1117
1118#
1119# Both the "perf" and "buddy" hardlockup detectors count hrtimer
1120# interrupts. This config enables functions managing this common code.
1121#
1122config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1123	bool
1124	select SOFTLOCKUP_DETECTOR
1125
1126#
1127# Enables a timestamp based low pass filter to compensate for perf based
1128# hard lockup detection which runs too fast due to turbo modes.
1129#
1130config HARDLOCKUP_CHECK_TIMESTAMP
1131	bool
1132
1133config BOOTPARAM_HARDLOCKUP_PANIC
1134	bool "Panic (Reboot) On Hard Lockups"
1135	depends on HARDLOCKUP_DETECTOR
1136	help
1137	  Say Y here to enable the kernel to panic on "hard lockups",
1138	  which are bugs that cause the kernel to loop in kernel
1139	  mode with interrupts disabled for more than 10 seconds (configurable
1140	  using the watchdog_thresh sysctl).
1141
1142	  Say N if unsure.
1143
1144config DETECT_HUNG_TASK
1145	bool "Detect Hung Tasks"
1146	depends on DEBUG_KERNEL
1147	default SOFTLOCKUP_DETECTOR
1148	help
1149	  Say Y here to enable the kernel to detect "hung tasks",
1150	  which are bugs that cause the task to be stuck in
1151	  uninterruptible "D" state indefinitely.
1152
1153	  When a hung task is detected, the kernel will print the
1154	  current stack trace (which you should report), but the
1155	  task will stay in uninterruptible state. If lockdep is
1156	  enabled then all held locks will also be reported. This
1157	  feature has negligible overhead.
1158
1159config DEFAULT_HUNG_TASK_TIMEOUT
1160	int "Default timeout for hung task detection (in seconds)"
1161	depends on DETECT_HUNG_TASK
1162	default 120
1163	help
1164	  This option controls the default timeout (in seconds) used
1165	  to determine when a task has become non-responsive and should
1166	  be considered hung.
1167
1168	  It can be adjusted at runtime via the kernel.hung_task_timeout_secs
1169	  sysctl or by writing a value to
1170	  /proc/sys/kernel/hung_task_timeout_secs.
1171
1172	  A timeout of 0 disables the check.  The default is two minutes.
1173	  Keeping the default should be fine in most cases.
1174
1175config BOOTPARAM_HUNG_TASK_PANIC
1176	bool "Panic (Reboot) On Hung Tasks"
1177	depends on DETECT_HUNG_TASK
1178	help
1179	  Say Y here to enable the kernel to panic on "hung tasks",
1180	  which are bugs that cause the kernel to leave a task stuck
1181	  in uninterruptible "D" state.
1182
1183	  The panic can be used in combination with panic_timeout,
1184	  to cause the system to reboot automatically after a
1185	  hung task has been detected. This feature is useful for
1186	  high-availability systems that have uptime guarantees and
1187	  where a hung tasks must be resolved ASAP.
1188
1189	  Say N if unsure.
1190
1191config WQ_WATCHDOG
1192	bool "Detect Workqueue Stalls"
1193	depends on DEBUG_KERNEL
1194	help
1195	  Say Y here to enable stall detection on workqueues.  If a
1196	  worker pool doesn't make forward progress on a pending work
1197	  item for over a given amount of time, 30s by default, a
1198	  warning message is printed along with dump of workqueue
1199	  state.  This can be configured through kernel parameter
1200	  "workqueue.watchdog_thresh" and its sysfs counterpart.
1201
1202config WQ_CPU_INTENSIVE_REPORT
1203	bool "Report per-cpu work items which hog CPU for too long"
1204	depends on DEBUG_KERNEL
1205	help
1206	  Say Y here to enable reporting of concurrency-managed per-cpu work
1207	  items that hog CPUs for longer than
1208	  workqueue.cpu_intensive_thresh_us. Workqueue automatically
1209	  detects and excludes them from concurrency management to prevent
1210	  them from stalling other per-cpu work items. Occassional
1211	  triggering may not necessarily indicate a problem. Repeated
1212	  triggering likely indicates that the work item should be switched
1213	  to use an unbound workqueue.
1214
1215config TEST_LOCKUP
1216	tristate "Test module to generate lockups"
1217	depends on m
1218	help
1219	  This builds the "test_lockup" module that helps to make sure
1220	  that watchdogs and lockup detectors are working properly.
1221
1222	  Depending on module parameters it could emulate soft or hard
1223	  lockup, "hung task", or locking arbitrary lock for a long time.
1224	  Also it could generate series of lockups with cooling-down periods.
1225
1226	  If unsure, say N.
1227
1228endmenu # "Debug lockups and hangs"
1229
1230menu "Scheduler Debugging"
1231
1232config SCHED_DEBUG
1233	bool "Collect scheduler debugging info"
1234	depends on DEBUG_KERNEL && DEBUG_FS
1235	default y
1236	help
1237	  If you say Y here, the /sys/kernel/debug/sched file will be provided
1238	  that can help debug the scheduler. The runtime overhead of this
1239	  option is minimal.
1240
1241config SCHED_INFO
1242	bool
1243	default n
1244
1245config SCHEDSTATS
1246	bool "Collect scheduler statistics"
1247	depends on DEBUG_KERNEL && PROC_FS
1248	select SCHED_INFO
1249	help
1250	  If you say Y here, additional code will be inserted into the
1251	  scheduler and related routines to collect statistics about
1252	  scheduler behavior and provide them in /proc/schedstat.  These
1253	  stats may be useful for both tuning and debugging the scheduler
1254	  If you aren't debugging the scheduler or trying to tune a specific
1255	  application, you can say N to avoid the very slight overhead
1256	  this adds.
1257
1258endmenu
1259
1260config DEBUG_TIMEKEEPING
1261	bool "Enable extra timekeeping sanity checking"
1262	help
1263	  This option will enable additional timekeeping sanity checks
1264	  which may be helpful when diagnosing issues where timekeeping
1265	  problems are suspected.
1266
1267	  This may include checks in the timekeeping hotpaths, so this
1268	  option may have a (very small) performance impact to some
1269	  workloads.
1270
1271	  If unsure, say N.
1272
1273config DEBUG_PREEMPT
1274	bool "Debug preemptible kernel"
1275	depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT
1276	help
1277	  If you say Y here then the kernel will use a debug variant of the
1278	  commonly used smp_processor_id() function and will print warnings
1279	  if kernel code uses it in a preemption-unsafe way. Also, the kernel
1280	  will detect preemption count underflows.
1281
1282	  This option has potential to introduce high runtime overhead,
1283	  depending on workload as it triggers debugging routines for each
1284	  this_cpu operation. It should only be used for debugging purposes.
1285
1286menu "Lock Debugging (spinlocks, mutexes, etc...)"
1287
1288config LOCK_DEBUGGING_SUPPORT
1289	bool
1290	depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1291	default y
1292
1293config PROVE_LOCKING
1294	bool "Lock debugging: prove locking correctness"
1295	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1296	select LOCKDEP
1297	select DEBUG_SPINLOCK
1298	select DEBUG_MUTEXES if !PREEMPT_RT
1299	select DEBUG_RT_MUTEXES if RT_MUTEXES
1300	select DEBUG_RWSEMS
1301	select DEBUG_WW_MUTEX_SLOWPATH
1302	select DEBUG_LOCK_ALLOC
1303	select PREEMPT_COUNT if !ARCH_NO_PREEMPT
1304	select TRACE_IRQFLAGS
1305	default n
1306	help
1307	 This feature enables the kernel to prove that all locking
1308	 that occurs in the kernel runtime is mathematically
1309	 correct: that under no circumstance could an arbitrary (and
1310	 not yet triggered) combination of observed locking
1311	 sequences (on an arbitrary number of CPUs, running an
1312	 arbitrary number of tasks and interrupt contexts) cause a
1313	 deadlock.
1314
1315	 In short, this feature enables the kernel to report locking
1316	 related deadlocks before they actually occur.
1317
1318	 The proof does not depend on how hard and complex a
1319	 deadlock scenario would be to trigger: how many
1320	 participant CPUs, tasks and irq-contexts would be needed
1321	 for it to trigger. The proof also does not depend on
1322	 timing: if a race and a resulting deadlock is possible
1323	 theoretically (no matter how unlikely the race scenario
1324	 is), it will be proven so and will immediately be
1325	 reported by the kernel (once the event is observed that
1326	 makes the deadlock theoretically possible).
1327
1328	 If a deadlock is impossible (i.e. the locking rules, as
1329	 observed by the kernel, are mathematically correct), the
1330	 kernel reports nothing.
1331
1332	 NOTE: this feature can also be enabled for rwlocks, mutexes
1333	 and rwsems - in which case all dependencies between these
1334	 different locking variants are observed and mapped too, and
1335	 the proof of observed correctness is also maintained for an
1336	 arbitrary combination of these separate locking variants.
1337
1338	 For more details, see Documentation/locking/lockdep-design.rst.
1339
1340config PROVE_RAW_LOCK_NESTING
1341	bool "Enable raw_spinlock - spinlock nesting checks"
1342	depends on PROVE_LOCKING
1343	default n
1344	help
1345	 Enable the raw_spinlock vs. spinlock nesting checks which ensure
1346	 that the lock nesting rules for PREEMPT_RT enabled kernels are
1347	 not violated.
1348
1349	 NOTE: There are known nesting problems. So if you enable this
1350	 option expect lockdep splats until these problems have been fully
1351	 addressed which is work in progress. This config switch allows to
1352	 identify and analyze these problems. It will be removed and the
1353	 check permanently enabled once the main issues have been fixed.
1354
1355	 If unsure, select N.
1356
1357config LOCK_STAT
1358	bool "Lock usage statistics"
1359	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1360	select LOCKDEP
1361	select DEBUG_SPINLOCK
1362	select DEBUG_MUTEXES if !PREEMPT_RT
1363	select DEBUG_RT_MUTEXES if RT_MUTEXES
1364	select DEBUG_LOCK_ALLOC
1365	default n
1366	help
1367	 This feature enables tracking lock contention points
1368
1369	 For more details, see Documentation/locking/lockstat.rst
1370
1371	 This also enables lock events required by "perf lock",
1372	 subcommand of perf.
1373	 If you want to use "perf lock", you also need to turn on
1374	 CONFIG_EVENT_TRACING.
1375
1376	 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1377	 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1378
1379config DEBUG_RT_MUTEXES
1380	bool "RT Mutex debugging, deadlock detection"
1381	depends on DEBUG_KERNEL && RT_MUTEXES
1382	help
1383	 This allows rt mutex semantics violations and rt mutex related
1384	 deadlocks (lockups) to be detected and reported automatically.
1385
1386config DEBUG_SPINLOCK
1387	bool "Spinlock and rw-lock debugging: basic checks"
1388	depends on DEBUG_KERNEL
1389	select UNINLINE_SPIN_UNLOCK
1390	help
1391	  Say Y here and build SMP to catch missing spinlock initialization
1392	  and certain other kinds of spinlock errors commonly made.  This is
1393	  best used in conjunction with the NMI watchdog so that spinlock
1394	  deadlocks are also debuggable.
1395
1396config DEBUG_MUTEXES
1397	bool "Mutex debugging: basic checks"
1398	depends on DEBUG_KERNEL && !PREEMPT_RT
1399	help
1400	 This feature allows mutex semantics violations to be detected and
1401	 reported.
1402
1403config DEBUG_WW_MUTEX_SLOWPATH
1404	bool "Wait/wound mutex debugging: Slowpath testing"
1405	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1406	select DEBUG_LOCK_ALLOC
1407	select DEBUG_SPINLOCK
1408	select DEBUG_MUTEXES if !PREEMPT_RT
1409	select DEBUG_RT_MUTEXES if PREEMPT_RT
1410	help
1411	 This feature enables slowpath testing for w/w mutex users by
1412	 injecting additional -EDEADLK wound/backoff cases. Together with
1413	 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1414	 will test all possible w/w mutex interface abuse with the
1415	 exception of simply not acquiring all the required locks.
1416	 Note that this feature can introduce significant overhead, so
1417	 it really should not be enabled in a production or distro kernel,
1418	 even a debug kernel.  If you are a driver writer, enable it.  If
1419	 you are a distro, do not.
1420
1421config DEBUG_RWSEMS
1422	bool "RW Semaphore debugging: basic checks"
1423	depends on DEBUG_KERNEL
1424	help
1425	  This debugging feature allows mismatched rw semaphore locks
1426	  and unlocks to be detected and reported.
1427
1428config DEBUG_LOCK_ALLOC
1429	bool "Lock debugging: detect incorrect freeing of live locks"
1430	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1431	select DEBUG_SPINLOCK
1432	select DEBUG_MUTEXES if !PREEMPT_RT
1433	select DEBUG_RT_MUTEXES if RT_MUTEXES
1434	select LOCKDEP
1435	help
1436	 This feature will check whether any held lock (spinlock, rwlock,
1437	 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1438	 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1439	 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1440	 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1441	 held during task exit.
1442
1443config LOCKDEP
1444	bool
1445	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1446	select STACKTRACE
1447	select KALLSYMS
1448	select KALLSYMS_ALL
1449
1450config LOCKDEP_SMALL
1451	bool
1452
1453config LOCKDEP_BITS
1454	int "Bitsize for MAX_LOCKDEP_ENTRIES"
1455	depends on LOCKDEP && !LOCKDEP_SMALL
1456	range 10 30
1457	default 15
1458	help
1459	  Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message.
1460
1461config LOCKDEP_CHAINS_BITS
1462	int "Bitsize for MAX_LOCKDEP_CHAINS"
1463	depends on LOCKDEP && !LOCKDEP_SMALL
1464	range 10 30
1465	default 16
1466	help
1467	  Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message.
1468
1469config LOCKDEP_STACK_TRACE_BITS
1470	int "Bitsize for MAX_STACK_TRACE_ENTRIES"
1471	depends on LOCKDEP && !LOCKDEP_SMALL
1472	range 10 30
1473	default 19
1474	help
1475	  Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message.
1476
1477config LOCKDEP_STACK_TRACE_HASH_BITS
1478	int "Bitsize for STACK_TRACE_HASH_SIZE"
1479	depends on LOCKDEP && !LOCKDEP_SMALL
1480	range 10 30
1481	default 14
1482	help
1483	  Try increasing this value if you need large STACK_TRACE_HASH_SIZE.
1484
1485config LOCKDEP_CIRCULAR_QUEUE_BITS
1486	int "Bitsize for elements in circular_queue struct"
1487	depends on LOCKDEP
1488	range 10 30
1489	default 12
1490	help
1491	  Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure.
1492
1493config DEBUG_LOCKDEP
1494	bool "Lock dependency engine debugging"
1495	depends on DEBUG_KERNEL && LOCKDEP
1496	select DEBUG_IRQFLAGS
1497	help
1498	  If you say Y here, the lock dependency engine will do
1499	  additional runtime checks to debug itself, at the price
1500	  of more runtime overhead.
1501
1502config DEBUG_ATOMIC_SLEEP
1503	bool "Sleep inside atomic section checking"
1504	select PREEMPT_COUNT
1505	depends on DEBUG_KERNEL
1506	depends on !ARCH_NO_PREEMPT
1507	help
1508	  If you say Y here, various routines which may sleep will become very
1509	  noisy if they are called inside atomic sections: when a spinlock is
1510	  held, inside an rcu read side critical section, inside preempt disabled
1511	  sections, inside an interrupt, etc...
1512
1513config DEBUG_LOCKING_API_SELFTESTS
1514	bool "Locking API boot-time self-tests"
1515	depends on DEBUG_KERNEL
1516	help
1517	  Say Y here if you want the kernel to run a short self-test during
1518	  bootup. The self-test checks whether common types of locking bugs
1519	  are detected by debugging mechanisms or not. (if you disable
1520	  lock debugging then those bugs won't be detected of course.)
1521	  The following locking APIs are covered: spinlocks, rwlocks,
1522	  mutexes and rwsems.
1523
1524config LOCK_TORTURE_TEST
1525	tristate "torture tests for locking"
1526	depends on DEBUG_KERNEL
1527	select TORTURE_TEST
1528	help
1529	  This option provides a kernel module that runs torture tests
1530	  on kernel locking primitives.  The kernel module may be built
1531	  after the fact on the running kernel to be tested, if desired.
1532
1533	  Say Y here if you want kernel locking-primitive torture tests
1534	  to be built into the kernel.
1535	  Say M if you want these torture tests to build as a module.
1536	  Say N if you are unsure.
1537
1538config WW_MUTEX_SELFTEST
1539	tristate "Wait/wound mutex selftests"
1540	help
1541	  This option provides a kernel module that runs tests on the
1542	  on the struct ww_mutex locking API.
1543
1544	  It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1545	  with this test harness.
1546
1547	  Say M if you want these self tests to build as a module.
1548	  Say N if you are unsure.
1549
1550config SCF_TORTURE_TEST
1551	tristate "torture tests for smp_call_function*()"
1552	depends on DEBUG_KERNEL
1553	select TORTURE_TEST
1554	help
1555	  This option provides a kernel module that runs torture tests
1556	  on the smp_call_function() family of primitives.  The kernel
1557	  module may be built after the fact on the running kernel to
1558	  be tested, if desired.
1559
1560config CSD_LOCK_WAIT_DEBUG
1561	bool "Debugging for csd_lock_wait(), called from smp_call_function*()"
1562	depends on DEBUG_KERNEL
1563	depends on 64BIT
1564	default n
1565	help
1566	  This option enables debug prints when CPUs are slow to respond
1567	  to the smp_call_function*() IPI wrappers.  These debug prints
1568	  include the IPI handler function currently executing (if any)
1569	  and relevant stack traces.
1570
1571config CSD_LOCK_WAIT_DEBUG_DEFAULT
1572	bool "Default csd_lock_wait() debugging on at boot time"
1573	depends on CSD_LOCK_WAIT_DEBUG
1574	depends on 64BIT
1575	default n
1576	help
1577	  This option causes the csdlock_debug= kernel boot parameter to
1578	  default to 1 (basic debugging) instead of 0 (no debugging).
1579
1580endmenu # lock debugging
1581
1582config TRACE_IRQFLAGS
1583	depends on TRACE_IRQFLAGS_SUPPORT
1584	bool
1585	help
1586	  Enables hooks to interrupt enabling and disabling for
1587	  either tracing or lock debugging.
1588
1589config TRACE_IRQFLAGS_NMI
1590	def_bool y
1591	depends on TRACE_IRQFLAGS
1592	depends on TRACE_IRQFLAGS_NMI_SUPPORT
1593
1594config NMI_CHECK_CPU
1595	bool "Debugging for CPUs failing to respond to backtrace requests"
1596	depends on DEBUG_KERNEL
1597	depends on X86
1598	default n
1599	help
1600	  Enables debug prints when a CPU fails to respond to a given
1601	  backtrace NMI.  These prints provide some reasons why a CPU
1602	  might legitimately be failing to respond, for example, if it
1603	  is offline of if ignore_nmis is set.
1604
1605config DEBUG_IRQFLAGS
1606	bool "Debug IRQ flag manipulation"
1607	help
1608	  Enables checks for potentially unsafe enabling or disabling of
1609	  interrupts, such as calling raw_local_irq_restore() when interrupts
1610	  are enabled.
1611
1612config STACKTRACE
1613	bool "Stack backtrace support"
1614	depends on STACKTRACE_SUPPORT
1615	help
1616	  This option causes the kernel to create a /proc/pid/stack for
1617	  every process, showing its current stack trace.
1618	  It is also used by various kernel debugging features that require
1619	  stack trace generation.
1620
1621config WARN_ALL_UNSEEDED_RANDOM
1622	bool "Warn for all uses of unseeded randomness"
1623	default n
1624	help
1625	  Some parts of the kernel contain bugs relating to their use of
1626	  cryptographically secure random numbers before it's actually possible
1627	  to generate those numbers securely. This setting ensures that these
1628	  flaws don't go unnoticed, by enabling a message, should this ever
1629	  occur. This will allow people with obscure setups to know when things
1630	  are going wrong, so that they might contact developers about fixing
1631	  it.
1632
1633	  Unfortunately, on some models of some architectures getting
1634	  a fully seeded CRNG is extremely difficult, and so this can
1635	  result in dmesg getting spammed for a surprisingly long
1636	  time.  This is really bad from a security perspective, and
1637	  so architecture maintainers really need to do what they can
1638	  to get the CRNG seeded sooner after the system is booted.
1639	  However, since users cannot do anything actionable to
1640	  address this, by default this option is disabled.
1641
1642	  Say Y here if you want to receive warnings for all uses of
1643	  unseeded randomness.  This will be of use primarily for
1644	  those developers interested in improving the security of
1645	  Linux kernels running on their architecture (or
1646	  subarchitecture).
1647
1648config DEBUG_KOBJECT
1649	bool "kobject debugging"
1650	depends on DEBUG_KERNEL
1651	help
1652	  If you say Y here, some extra kobject debugging messages will be sent
1653	  to the syslog.
1654
1655config DEBUG_KOBJECT_RELEASE
1656	bool "kobject release debugging"
1657	depends on DEBUG_OBJECTS_TIMERS
1658	help
1659	  kobjects are reference counted objects.  This means that their
1660	  last reference count put is not predictable, and the kobject can
1661	  live on past the point at which a driver decides to drop its
1662	  initial reference to the kobject gained on allocation.  An
1663	  example of this would be a struct device which has just been
1664	  unregistered.
1665
1666	  However, some buggy drivers assume that after such an operation,
1667	  the memory backing the kobject can be immediately freed.  This
1668	  goes completely against the principles of a refcounted object.
1669
1670	  If you say Y here, the kernel will delay the release of kobjects
1671	  on the last reference count to improve the visibility of this
1672	  kind of kobject release bug.
1673
1674config HAVE_DEBUG_BUGVERBOSE
1675	bool
1676
1677menu "Debug kernel data structures"
1678
1679config DEBUG_LIST
1680	bool "Debug linked list manipulation"
1681	depends on DEBUG_KERNEL
1682	select LIST_HARDENED
1683	help
1684	  Enable this to turn on extended checks in the linked-list walking
1685	  routines.
1686
1687	  This option trades better quality error reports for performance, and
1688	  is more suitable for kernel debugging. If you care about performance,
1689	  you should only enable CONFIG_LIST_HARDENED instead.
1690
1691	  If unsure, say N.
1692
1693config DEBUG_PLIST
1694	bool "Debug priority linked list manipulation"
1695	depends on DEBUG_KERNEL
1696	help
1697	  Enable this to turn on extended checks in the priority-ordered
1698	  linked-list (plist) walking routines.  This checks the entire
1699	  list multiple times during each manipulation.
1700
1701	  If unsure, say N.
1702
1703config DEBUG_SG
1704	bool "Debug SG table operations"
1705	depends on DEBUG_KERNEL
1706	help
1707	  Enable this to turn on checks on scatter-gather tables. This can
1708	  help find problems with drivers that do not properly initialize
1709	  their sg tables.
1710
1711	  If unsure, say N.
1712
1713config DEBUG_NOTIFIERS
1714	bool "Debug notifier call chains"
1715	depends on DEBUG_KERNEL
1716	help
1717	  Enable this to turn on sanity checking for notifier call chains.
1718	  This is most useful for kernel developers to make sure that
1719	  modules properly unregister themselves from notifier chains.
1720	  This is a relatively cheap check but if you care about maximum
1721	  performance, say N.
1722
1723config DEBUG_MAPLE_TREE
1724	bool "Debug maple trees"
1725	depends on DEBUG_KERNEL
1726	help
1727	  Enable maple tree debugging information and extra validations.
1728
1729	  If unsure, say N.
1730
1731endmenu
1732
1733config DEBUG_CREDENTIALS
1734	bool "Debug credential management"
1735	depends on DEBUG_KERNEL
1736	help
1737	  Enable this to turn on some debug checking for credential
1738	  management.  The additional code keeps track of the number of
1739	  pointers from task_structs to any given cred struct, and checks to
1740	  see that this number never exceeds the usage count of the cred
1741	  struct.
1742
1743	  Furthermore, if SELinux is enabled, this also checks that the
1744	  security pointer in the cred struct is never seen to be invalid.
1745
1746	  If unsure, say N.
1747
1748source "kernel/rcu/Kconfig.debug"
1749
1750config DEBUG_WQ_FORCE_RR_CPU
1751	bool "Force round-robin CPU selection for unbound work items"
1752	depends on DEBUG_KERNEL
1753	default n
1754	help
1755	  Workqueue used to implicitly guarantee that work items queued
1756	  without explicit CPU specified are put on the local CPU.  This
1757	  guarantee is no longer true and while local CPU is still
1758	  preferred work items may be put on foreign CPUs.  Kernel
1759	  parameter "workqueue.debug_force_rr_cpu" is added to force
1760	  round-robin CPU selection to flush out usages which depend on the
1761	  now broken guarantee.  This config option enables the debug
1762	  feature by default.  When enabled, memory and cache locality will
1763	  be impacted.
1764
1765config CPU_HOTPLUG_STATE_CONTROL
1766	bool "Enable CPU hotplug state control"
1767	depends on DEBUG_KERNEL
1768	depends on HOTPLUG_CPU
1769	default n
1770	help
1771	  Allows to write steps between "offline" and "online" to the CPUs
1772	  sysfs target file so states can be stepped granular. This is a debug
1773	  option for now as the hotplug machinery cannot be stopped and
1774	  restarted at arbitrary points yet.
1775
1776	  Say N if your are unsure.
1777
1778config LATENCYTOP
1779	bool "Latency measuring infrastructure"
1780	depends on DEBUG_KERNEL
1781	depends on STACKTRACE_SUPPORT
1782	depends on PROC_FS
1783	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
1784	select KALLSYMS
1785	select KALLSYMS_ALL
1786	select STACKTRACE
1787	select SCHEDSTATS
1788	help
1789	  Enable this option if you want to use the LatencyTOP tool
1790	  to find out which userspace is blocking on what kernel operations.
1791
1792config DEBUG_CGROUP_REF
1793	bool "Disable inlining of cgroup css reference count functions"
1794	depends on DEBUG_KERNEL
1795	depends on CGROUPS
1796	depends on KPROBES
1797	default n
1798	help
1799	  Force cgroup css reference count functions to not be inlined so
1800	  that they can be kprobed for debugging.
1801
1802source "kernel/trace/Kconfig"
1803
1804config PROVIDE_OHCI1394_DMA_INIT
1805	bool "Remote debugging over FireWire early on boot"
1806	depends on PCI && X86
1807	help
1808	  If you want to debug problems which hang or crash the kernel early
1809	  on boot and the crashing machine has a FireWire port, you can use
1810	  this feature to remotely access the memory of the crashed machine
1811	  over FireWire. This employs remote DMA as part of the OHCI1394
1812	  specification which is now the standard for FireWire controllers.
1813
1814	  With remote DMA, you can monitor the printk buffer remotely using
1815	  firescope and access all memory below 4GB using fireproxy from gdb.
1816	  Even controlling a kernel debugger is possible using remote DMA.
1817
1818	  Usage:
1819
1820	  If ohci1394_dma=early is used as boot parameter, it will initialize
1821	  all OHCI1394 controllers which are found in the PCI config space.
1822
1823	  As all changes to the FireWire bus such as enabling and disabling
1824	  devices cause a bus reset and thereby disable remote DMA for all
1825	  devices, be sure to have the cable plugged and FireWire enabled on
1826	  the debugging host before booting the debug target for debugging.
1827
1828	  This code (~1k) is freed after boot. By then, the firewire stack
1829	  in charge of the OHCI-1394 controllers should be used instead.
1830
1831	  See Documentation/core-api/debugging-via-ohci1394.rst for more information.
1832
1833source "samples/Kconfig"
1834
1835config ARCH_HAS_DEVMEM_IS_ALLOWED
1836	bool
1837
1838config STRICT_DEVMEM
1839	bool "Filter access to /dev/mem"
1840	depends on MMU && DEVMEM
1841	depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED
1842	default y if PPC || X86 || ARM64
1843	help
1844	  If this option is disabled, you allow userspace (root) access to all
1845	  of memory, including kernel and userspace memory. Accidental
1846	  access to this is obviously disastrous, but specific access can
1847	  be used by people debugging the kernel. Note that with PAT support
1848	  enabled, even in this case there are restrictions on /dev/mem
1849	  use due to the cache aliasing requirements.
1850
1851	  If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
1852	  file only allows userspace access to PCI space and the BIOS code and
1853	  data regions.  This is sufficient for dosemu and X and all common
1854	  users of /dev/mem.
1855
1856	  If in doubt, say Y.
1857
1858config IO_STRICT_DEVMEM
1859	bool "Filter I/O access to /dev/mem"
1860	depends on STRICT_DEVMEM
1861	help
1862	  If this option is disabled, you allow userspace (root) access to all
1863	  io-memory regardless of whether a driver is actively using that
1864	  range.  Accidental access to this is obviously disastrous, but
1865	  specific access can be used by people debugging kernel drivers.
1866
1867	  If this option is switched on, the /dev/mem file only allows
1868	  userspace access to *idle* io-memory ranges (see /proc/iomem) This
1869	  may break traditional users of /dev/mem (dosemu, legacy X, etc...)
1870	  if the driver using a given range cannot be disabled.
1871
1872	  If in doubt, say Y.
1873
1874menu "$(SRCARCH) Debugging"
1875
1876source "arch/$(SRCARCH)/Kconfig.debug"
1877
1878endmenu
1879
1880menu "Kernel Testing and Coverage"
1881
1882source "lib/kunit/Kconfig"
1883
1884config NOTIFIER_ERROR_INJECTION
1885	tristate "Notifier error injection"
1886	depends on DEBUG_KERNEL
1887	select DEBUG_FS
1888	help
1889	  This option provides the ability to inject artificial errors to
1890	  specified notifier chain callbacks. It is useful to test the error
1891	  handling of notifier call chain failures.
1892
1893	  Say N if unsure.
1894
1895config PM_NOTIFIER_ERROR_INJECT
1896	tristate "PM notifier error injection module"
1897	depends on PM && NOTIFIER_ERROR_INJECTION
1898	default m if PM_DEBUG
1899	help
1900	  This option provides the ability to inject artificial errors to
1901	  PM notifier chain callbacks.  It is controlled through debugfs
1902	  interface /sys/kernel/debug/notifier-error-inject/pm
1903
1904	  If the notifier call chain should be failed with some events
1905	  notified, write the error code to "actions/<notifier event>/error".
1906
1907	  Example: Inject PM suspend error (-12 = -ENOMEM)
1908
1909	  # cd /sys/kernel/debug/notifier-error-inject/pm/
1910	  # echo -12 > actions/PM_SUSPEND_PREPARE/error
1911	  # echo mem > /sys/power/state
1912	  bash: echo: write error: Cannot allocate memory
1913
1914	  To compile this code as a module, choose M here: the module will
1915	  be called pm-notifier-error-inject.
1916
1917	  If unsure, say N.
1918
1919config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1920	tristate "OF reconfig notifier error injection module"
1921	depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1922	help
1923	  This option provides the ability to inject artificial errors to
1924	  OF reconfig notifier chain callbacks.  It is controlled
1925	  through debugfs interface under
1926	  /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1927
1928	  If the notifier call chain should be failed with some events
1929	  notified, write the error code to "actions/<notifier event>/error".
1930
1931	  To compile this code as a module, choose M here: the module will
1932	  be called of-reconfig-notifier-error-inject.
1933
1934	  If unsure, say N.
1935
1936config NETDEV_NOTIFIER_ERROR_INJECT
1937	tristate "Netdev notifier error injection module"
1938	depends on NET && NOTIFIER_ERROR_INJECTION
1939	help
1940	  This option provides the ability to inject artificial errors to
1941	  netdevice notifier chain callbacks.  It is controlled through debugfs
1942	  interface /sys/kernel/debug/notifier-error-inject/netdev
1943
1944	  If the notifier call chain should be failed with some events
1945	  notified, write the error code to "actions/<notifier event>/error".
1946
1947	  Example: Inject netdevice mtu change error (-22 = -EINVAL)
1948
1949	  # cd /sys/kernel/debug/notifier-error-inject/netdev
1950	  # echo -22 > actions/NETDEV_CHANGEMTU/error
1951	  # ip link set eth0 mtu 1024
1952	  RTNETLINK answers: Invalid argument
1953
1954	  To compile this code as a module, choose M here: the module will
1955	  be called netdev-notifier-error-inject.
1956
1957	  If unsure, say N.
1958
1959config FUNCTION_ERROR_INJECTION
1960	bool "Fault-injections of functions"
1961	depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
1962	help
1963	  Add fault injections into various functions that are annotated with
1964	  ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return
1965	  value of these functions. This is useful to test error paths of code.
1966
1967	  If unsure, say N
1968
1969config FAULT_INJECTION
1970	bool "Fault-injection framework"
1971	depends on DEBUG_KERNEL
1972	help
1973	  Provide fault-injection framework.
1974	  For more details, see Documentation/fault-injection/.
1975
1976config FAILSLAB
1977	bool "Fault-injection capability for kmalloc"
1978	depends on FAULT_INJECTION
1979	depends on SLAB || SLUB
1980	help
1981	  Provide fault-injection capability for kmalloc.
1982
1983config FAIL_PAGE_ALLOC
1984	bool "Fault-injection capability for alloc_pages()"
1985	depends on FAULT_INJECTION
1986	help
1987	  Provide fault-injection capability for alloc_pages().
1988
1989config FAULT_INJECTION_USERCOPY
1990	bool "Fault injection capability for usercopy functions"
1991	depends on FAULT_INJECTION
1992	help
1993	  Provides fault-injection capability to inject failures
1994	  in usercopy functions (copy_from_user(), get_user(), ...).
1995
1996config FAIL_MAKE_REQUEST
1997	bool "Fault-injection capability for disk IO"
1998	depends on FAULT_INJECTION && BLOCK
1999	help
2000	  Provide fault-injection capability for disk IO.
2001
2002config FAIL_IO_TIMEOUT
2003	bool "Fault-injection capability for faking disk interrupts"
2004	depends on FAULT_INJECTION && BLOCK
2005	help
2006	  Provide fault-injection capability on end IO handling. This
2007	  will make the block layer "forget" an interrupt as configured,
2008	  thus exercising the error handling.
2009
2010	  Only works with drivers that use the generic timeout handling,
2011	  for others it won't do anything.
2012
2013config FAIL_FUTEX
2014	bool "Fault-injection capability for futexes"
2015	select DEBUG_FS
2016	depends on FAULT_INJECTION && FUTEX
2017	help
2018	  Provide fault-injection capability for futexes.
2019
2020config FAULT_INJECTION_DEBUG_FS
2021	bool "Debugfs entries for fault-injection capabilities"
2022	depends on FAULT_INJECTION && SYSFS && DEBUG_FS
2023	help
2024	  Enable configuration of fault-injection capabilities via debugfs.
2025
2026config FAIL_FUNCTION
2027	bool "Fault-injection capability for functions"
2028	depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
2029	help
2030	  Provide function-based fault-injection capability.
2031	  This will allow you to override a specific function with a return
2032	  with given return value. As a result, function caller will see
2033	  an error value and have to handle it. This is useful to test the
2034	  error handling in various subsystems.
2035
2036config FAIL_MMC_REQUEST
2037	bool "Fault-injection capability for MMC IO"
2038	depends on FAULT_INJECTION_DEBUG_FS && MMC
2039	help
2040	  Provide fault-injection capability for MMC IO.
2041	  This will make the mmc core return data errors. This is
2042	  useful to test the error handling in the mmc block device
2043	  and to test how the mmc host driver handles retries from
2044	  the block device.
2045
2046config FAIL_SUNRPC
2047	bool "Fault-injection capability for SunRPC"
2048	depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG
2049	help
2050	  Provide fault-injection capability for SunRPC and
2051	  its consumers.
2052
2053config FAULT_INJECTION_CONFIGFS
2054	bool "Configfs interface for fault-injection capabilities"
2055	depends on FAULT_INJECTION
2056	select CONFIGFS_FS
2057	help
2058	  This option allows configfs-based drivers to dynamically configure
2059	  fault-injection via configfs.  Each parameter for driver-specific
2060	  fault-injection can be made visible as a configfs attribute in a
2061	  configfs group.
2062
2063
2064config FAULT_INJECTION_STACKTRACE_FILTER
2065	bool "stacktrace filter for fault-injection capabilities"
2066	depends on FAULT_INJECTION
2067	depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT
2068	select STACKTRACE
2069	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
2070	help
2071	  Provide stacktrace filter for fault-injection capabilities
2072
2073config ARCH_HAS_KCOV
2074	bool
2075	help
2076	  An architecture should select this when it can successfully
2077	  build and run with CONFIG_KCOV. This typically requires
2078	  disabling instrumentation for some early boot code.
2079
2080config CC_HAS_SANCOV_TRACE_PC
2081	def_bool $(cc-option,-fsanitize-coverage=trace-pc)
2082
2083
2084config KCOV
2085	bool "Code coverage for fuzzing"
2086	depends on ARCH_HAS_KCOV
2087	depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
2088	depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \
2089		   GCC_VERSION >= 120000 || CLANG_VERSION >= 130000
2090	select DEBUG_FS
2091	select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
2092	select OBJTOOL if HAVE_NOINSTR_HACK
2093	help
2094	  KCOV exposes kernel code coverage information in a form suitable
2095	  for coverage-guided fuzzing (randomized testing).
2096
2097	  If RANDOMIZE_BASE is enabled, PC values will not be stable across
2098	  different machines and across reboots. If you need stable PC values,
2099	  disable RANDOMIZE_BASE.
2100
2101	  For more details, see Documentation/dev-tools/kcov.rst.
2102
2103config KCOV_ENABLE_COMPARISONS
2104	bool "Enable comparison operands collection by KCOV"
2105	depends on KCOV
2106	depends on $(cc-option,-fsanitize-coverage=trace-cmp)
2107	help
2108	  KCOV also exposes operands of every comparison in the instrumented
2109	  code along with operand sizes and PCs of the comparison instructions.
2110	  These operands can be used by fuzzing engines to improve the quality
2111	  of fuzzing coverage.
2112
2113config KCOV_INSTRUMENT_ALL
2114	bool "Instrument all code by default"
2115	depends on KCOV
2116	default y
2117	help
2118	  If you are doing generic system call fuzzing (like e.g. syzkaller),
2119	  then you will want to instrument the whole kernel and you should
2120	  say y here. If you are doing more targeted fuzzing (like e.g.
2121	  filesystem fuzzing with AFL) then you will want to enable coverage
2122	  for more specific subsets of files, and should say n here.
2123
2124config KCOV_IRQ_AREA_SIZE
2125	hex "Size of interrupt coverage collection area in words"
2126	depends on KCOV
2127	default 0x40000
2128	help
2129	  KCOV uses preallocated per-cpu areas to collect coverage from
2130	  soft interrupts. This specifies the size of those areas in the
2131	  number of unsigned long words.
2132
2133menuconfig RUNTIME_TESTING_MENU
2134	bool "Runtime Testing"
2135	def_bool y
2136
2137if RUNTIME_TESTING_MENU
2138
2139config TEST_DHRY
2140	tristate "Dhrystone benchmark test"
2141	help
2142	  Enable this to include the Dhrystone 2.1 benchmark.  This test
2143	  calculates the number of Dhrystones per second, and the number of
2144	  DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided
2145	  by 1757 (the number of Dhrystones per second obtained on the VAX
2146	  11/780, nominally a 1 MIPS machine).
2147
2148	  To run the benchmark, it needs to be enabled explicitly, either from
2149	  the kernel command line (when built-in), or from userspace (when
2150	  built-in or modular.
2151
2152	  Run once during kernel boot:
2153
2154	      test_dhry.run
2155
2156	  Set number of iterations from kernel command line:
2157
2158	      test_dhry.iterations=<n>
2159
2160	  Set number of iterations from userspace:
2161
2162	      echo <n> > /sys/module/test_dhry/parameters/iterations
2163
2164	  Trigger manual run from userspace:
2165
2166	      echo y > /sys/module/test_dhry/parameters/run
2167
2168	  If the number of iterations is <= 0, the test will devise a suitable
2169	  number of iterations (test runs for at least 2s) automatically.
2170	  This process takes ca. 4s.
2171
2172	  If unsure, say N.
2173
2174config LKDTM
2175	tristate "Linux Kernel Dump Test Tool Module"
2176	depends on DEBUG_FS
2177	help
2178	This module enables testing of the different dumping mechanisms by
2179	inducing system failures at predefined crash points.
2180	If you don't need it: say N
2181	Choose M here to compile this code as a module. The module will be
2182	called lkdtm.
2183
2184	Documentation on how to use the module can be found in
2185	Documentation/fault-injection/provoke-crashes.rst
2186
2187config CPUMASK_KUNIT_TEST
2188	tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS
2189	depends on KUNIT
2190	default KUNIT_ALL_TESTS
2191	help
2192	  Enable to turn on cpumask tests, running at boot or module load time.
2193
2194	  For more information on KUnit and unit tests in general, please refer
2195	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2196
2197	  If unsure, say N.
2198
2199config TEST_LIST_SORT
2200	tristate "Linked list sorting test" if !KUNIT_ALL_TESTS
2201	depends on KUNIT
2202	default KUNIT_ALL_TESTS
2203	help
2204	  Enable this to turn on 'list_sort()' function test. This test is
2205	  executed only once during system boot (so affects only boot time),
2206	  or at module load time.
2207
2208	  If unsure, say N.
2209
2210config TEST_MIN_HEAP
2211	tristate "Min heap test"
2212	depends on DEBUG_KERNEL || m
2213	help
2214	  Enable this to turn on min heap function tests. This test is
2215	  executed only once during system boot (so affects only boot time),
2216	  or at module load time.
2217
2218	  If unsure, say N.
2219
2220config TEST_SORT
2221	tristate "Array-based sort test" if !KUNIT_ALL_TESTS
2222	depends on KUNIT
2223	default KUNIT_ALL_TESTS
2224	help
2225	  This option enables the self-test function of 'sort()' at boot,
2226	  or at module load time.
2227
2228	  If unsure, say N.
2229
2230config TEST_DIV64
2231	tristate "64bit/32bit division and modulo test"
2232	depends on DEBUG_KERNEL || m
2233	help
2234	  Enable this to turn on 'do_div()' function test. This test is
2235	  executed only once during system boot (so affects only boot time),
2236	  or at module load time.
2237
2238	  If unsure, say N.
2239
2240config TEST_IOV_ITER
2241	tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS
2242	depends on KUNIT
2243	default KUNIT_ALL_TESTS
2244	help
2245	  Enable this to turn on testing of the operation of the I/O iterator
2246	  (iov_iter). This test is executed only once during system boot (so
2247	  affects only boot time), or at module load time.
2248
2249	  If unsure, say N.
2250
2251config KPROBES_SANITY_TEST
2252	tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS
2253	depends on DEBUG_KERNEL
2254	depends on KPROBES
2255	depends on KUNIT
2256	select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
2257	default KUNIT_ALL_TESTS
2258	help
2259	  This option provides for testing basic kprobes functionality on
2260	  boot. Samples of kprobe and kretprobe are inserted and
2261	  verified for functionality.
2262
2263	  Say N if you are unsure.
2264
2265config FPROBE_SANITY_TEST
2266	bool "Self test for fprobe"
2267	depends on DEBUG_KERNEL
2268	depends on FPROBE
2269	depends on KUNIT=y
2270	help
2271	  This option will enable testing the fprobe when the system boot.
2272	  A series of tests are made to verify that the fprobe is functioning
2273	  properly.
2274
2275	  Say N if you are unsure.
2276
2277config BACKTRACE_SELF_TEST
2278	tristate "Self test for the backtrace code"
2279	depends on DEBUG_KERNEL
2280	help
2281	  This option provides a kernel module that can be used to test
2282	  the kernel stack backtrace code. This option is not useful
2283	  for distributions or general kernels, but only for kernel
2284	  developers working on architecture code.
2285
2286	  Note that if you want to also test saved backtraces, you will
2287	  have to enable STACKTRACE as well.
2288
2289	  Say N if you are unsure.
2290
2291config TEST_REF_TRACKER
2292	tristate "Self test for reference tracker"
2293	depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
2294	select REF_TRACKER
2295	help
2296	  This option provides a kernel module performing tests
2297	  using reference tracker infrastructure.
2298
2299	  Say N if you are unsure.
2300
2301config RBTREE_TEST
2302	tristate "Red-Black tree test"
2303	depends on DEBUG_KERNEL
2304	help
2305	  A benchmark measuring the performance of the rbtree library.
2306	  Also includes rbtree invariant checks.
2307
2308config REED_SOLOMON_TEST
2309	tristate "Reed-Solomon library test"
2310	depends on DEBUG_KERNEL || m
2311	select REED_SOLOMON
2312	select REED_SOLOMON_ENC16
2313	select REED_SOLOMON_DEC16
2314	help
2315	  This option enables the self-test function of rslib at boot,
2316	  or at module load time.
2317
2318	  If unsure, say N.
2319
2320config INTERVAL_TREE_TEST
2321	tristate "Interval tree test"
2322	depends on DEBUG_KERNEL
2323	select INTERVAL_TREE
2324	help
2325	  A benchmark measuring the performance of the interval tree library
2326
2327config PERCPU_TEST
2328	tristate "Per cpu operations test"
2329	depends on m && DEBUG_KERNEL
2330	help
2331	  Enable this option to build test module which validates per-cpu
2332	  operations.
2333
2334	  If unsure, say N.
2335
2336config ATOMIC64_SELFTEST
2337	tristate "Perform an atomic64_t self-test"
2338	help
2339	  Enable this option to test the atomic64_t functions at boot or
2340	  at module load time.
2341
2342	  If unsure, say N.
2343
2344config ASYNC_RAID6_TEST
2345	tristate "Self test for hardware accelerated raid6 recovery"
2346	depends on ASYNC_RAID6_RECOV
2347	select ASYNC_MEMCPY
2348	help
2349	  This is a one-shot self test that permutes through the
2350	  recovery of all the possible two disk failure scenarios for a
2351	  N-disk array.  Recovery is performed with the asynchronous
2352	  raid6 recovery routines, and will optionally use an offload
2353	  engine if one is available.
2354
2355	  If unsure, say N.
2356
2357config TEST_HEXDUMP
2358	tristate "Test functions located in the hexdump module at runtime"
2359
2360config STRING_SELFTEST
2361	tristate "Test string functions at runtime"
2362
2363config TEST_STRING_HELPERS
2364	tristate "Test functions located in the string_helpers module at runtime"
2365
2366config TEST_KSTRTOX
2367	tristate "Test kstrto*() family of functions at runtime"
2368
2369config TEST_PRINTF
2370	tristate "Test printf() family of functions at runtime"
2371
2372config TEST_SCANF
2373	tristate "Test scanf() family of functions at runtime"
2374
2375config TEST_BITMAP
2376	tristate "Test bitmap_*() family of functions at runtime"
2377	help
2378	  Enable this option to test the bitmap functions at boot.
2379
2380	  If unsure, say N.
2381
2382config TEST_UUID
2383	tristate "Test functions located in the uuid module at runtime"
2384
2385config TEST_XARRAY
2386	tristate "Test the XArray code at runtime"
2387
2388config TEST_MAPLE_TREE
2389	tristate "Test the Maple Tree code at runtime or module load"
2390	help
2391	  Enable this option to test the maple tree code functions at boot, or
2392	  when the module is loaded. Enable "Debug Maple Trees" will enable
2393	  more verbose output on failures.
2394
2395	  If unsure, say N.
2396
2397config TEST_RHASHTABLE
2398	tristate "Perform selftest on resizable hash table"
2399	help
2400	  Enable this option to test the rhashtable functions at boot.
2401
2402	  If unsure, say N.
2403
2404config TEST_IDA
2405	tristate "Perform selftest on IDA functions"
2406
2407config TEST_PARMAN
2408	tristate "Perform selftest on priority array manager"
2409	depends on PARMAN
2410	help
2411	  Enable this option to test priority array manager on boot
2412	  (or module load).
2413
2414	  If unsure, say N.
2415
2416config TEST_IRQ_TIMINGS
2417	bool "IRQ timings selftest"
2418	depends on IRQ_TIMINGS
2419	help
2420	  Enable this option to test the irq timings code on boot.
2421
2422	  If unsure, say N.
2423
2424config TEST_LKM
2425	tristate "Test module loading with 'hello world' module"
2426	depends on m
2427	help
2428	  This builds the "test_module" module that emits "Hello, world"
2429	  on printk when loaded. It is designed to be used for basic
2430	  evaluation of the module loading subsystem (for example when
2431	  validating module verification). It lacks any extra dependencies,
2432	  and will not normally be loaded by the system unless explicitly
2433	  requested by name.
2434
2435	  If unsure, say N.
2436
2437config TEST_BITOPS
2438	tristate "Test module for compilation of bitops operations"
2439	depends on m
2440	help
2441	  This builds the "test_bitops" module that is much like the
2442	  TEST_LKM module except that it does a basic exercise of the
2443	  set/clear_bit macros and get_count_order/long to make sure there are
2444	  no compiler warnings from C=1 sparse checker or -Wextra
2445	  compilations. It has no dependencies and doesn't run or load unless
2446	  explicitly requested by name.  for example: modprobe test_bitops.
2447
2448	  If unsure, say N.
2449
2450config TEST_VMALLOC
2451	tristate "Test module for stress/performance analysis of vmalloc allocator"
2452	default n
2453       depends on MMU
2454	depends on m
2455	help
2456	  This builds the "test_vmalloc" module that should be used for
2457	  stress and performance analysis. So, any new change for vmalloc
2458	  subsystem can be evaluated from performance and stability point
2459	  of view.
2460
2461	  If unsure, say N.
2462
2463config TEST_USER_COPY
2464	tristate "Test user/kernel boundary protections"
2465	depends on m
2466	help
2467	  This builds the "test_user_copy" module that runs sanity checks
2468	  on the copy_to/from_user infrastructure, making sure basic
2469	  user/kernel boundary testing is working. If it fails to load,
2470	  a regression has been detected in the user/kernel memory boundary
2471	  protections.
2472
2473	  If unsure, say N.
2474
2475config TEST_BPF
2476	tristate "Test BPF filter functionality"
2477	depends on m && NET
2478	help
2479	  This builds the "test_bpf" module that runs various test vectors
2480	  against the BPF interpreter or BPF JIT compiler depending on the
2481	  current setting. This is in particular useful for BPF JIT compiler
2482	  development, but also to run regression tests against changes in
2483	  the interpreter code. It also enables test stubs for eBPF maps and
2484	  verifier used by user space verifier testsuite.
2485
2486	  If unsure, say N.
2487
2488config TEST_BLACKHOLE_DEV
2489	tristate "Test blackhole netdev functionality"
2490	depends on m && NET
2491	help
2492	  This builds the "test_blackhole_dev" module that validates the
2493	  data path through this blackhole netdev.
2494
2495	  If unsure, say N.
2496
2497config FIND_BIT_BENCHMARK
2498	tristate "Test find_bit functions"
2499	help
2500	  This builds the "test_find_bit" module that measure find_*_bit()
2501	  functions performance.
2502
2503	  If unsure, say N.
2504
2505config TEST_FIRMWARE
2506	tristate "Test firmware loading via userspace interface"
2507	depends on FW_LOADER
2508	help
2509	  This builds the "test_firmware" module that creates a userspace
2510	  interface for testing firmware loading. This can be used to
2511	  control the triggering of firmware loading without needing an
2512	  actual firmware-using device. The contents can be rechecked by
2513	  userspace.
2514
2515	  If unsure, say N.
2516
2517config TEST_SYSCTL
2518	tristate "sysctl test driver"
2519	depends on PROC_SYSCTL
2520	help
2521	  This builds the "test_sysctl" module. This driver enables to test the
2522	  proc sysctl interfaces available to drivers safely without affecting
2523	  production knobs which might alter system functionality.
2524
2525	  If unsure, say N.
2526
2527config BITFIELD_KUNIT
2528	tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS
2529	depends on KUNIT
2530	default KUNIT_ALL_TESTS
2531	help
2532	  Enable this option to test the bitfield functions at boot.
2533
2534	  KUnit tests run during boot and output the results to the debug log
2535	  in TAP format (http://testanything.org/). Only useful for kernel devs
2536	  running the KUnit test harness, and not intended for inclusion into a
2537	  production build.
2538
2539	  For more information on KUnit and unit tests in general please refer
2540	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2541
2542	  If unsure, say N.
2543
2544config CHECKSUM_KUNIT
2545	tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS
2546	depends on KUNIT
2547	default KUNIT_ALL_TESTS
2548	help
2549	  Enable this option to test the checksum functions at boot.
2550
2551	  KUnit tests run during boot and output the results to the debug log
2552	  in TAP format (http://testanything.org/). Only useful for kernel devs
2553	  running the KUnit test harness, and not intended for inclusion into a
2554	  production build.
2555
2556	  For more information on KUnit and unit tests in general please refer
2557	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2558
2559	  If unsure, say N.
2560
2561config HASH_KUNIT_TEST
2562	tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS
2563	depends on KUNIT
2564	default KUNIT_ALL_TESTS
2565	help
2566	  Enable this option to test the kernel's string (<linux/stringhash.h>), and
2567	  integer (<linux/hash.h>) hash functions on boot.
2568
2569	  KUnit tests run during boot and output the results to the debug log
2570	  in TAP format (https://testanything.org/). Only useful for kernel devs
2571	  running the KUnit test harness, and not intended for inclusion into a
2572	  production build.
2573
2574	  For more information on KUnit and unit tests in general please refer
2575	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2576
2577	  This is intended to help people writing architecture-specific
2578	  optimized versions. If unsure, say N.
2579
2580config RESOURCE_KUNIT_TEST
2581	tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS
2582	depends on KUNIT
2583	default KUNIT_ALL_TESTS
2584	help
2585	  This builds the resource API unit test.
2586	  Tests the logic of API provided by resource.c and ioport.h.
2587	  For more information on KUnit and unit tests in general please refer
2588	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2589
2590	  If unsure, say N.
2591
2592config SYSCTL_KUNIT_TEST
2593	tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS
2594	depends on KUNIT
2595	default KUNIT_ALL_TESTS
2596	help
2597	  This builds the proc sysctl unit test, which runs on boot.
2598	  Tests the API contract and implementation correctness of sysctl.
2599	  For more information on KUnit and unit tests in general please refer
2600	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2601
2602	  If unsure, say N.
2603
2604config LIST_KUNIT_TEST
2605	tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS
2606	depends on KUNIT
2607	default KUNIT_ALL_TESTS
2608	help
2609	  This builds the linked list KUnit test suite.
2610	  It tests that the API and basic functionality of the list_head type
2611	  and associated macros.
2612
2613	  KUnit tests run during boot and output the results to the debug log
2614	  in TAP format (https://testanything.org/). Only useful for kernel devs
2615	  running the KUnit test harness, and not intended for inclusion into a
2616	  production build.
2617
2618	  For more information on KUnit and unit tests in general please refer
2619	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2620
2621	  If unsure, say N.
2622
2623config HASHTABLE_KUNIT_TEST
2624	tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS
2625	depends on KUNIT
2626	default KUNIT_ALL_TESTS
2627	help
2628	  This builds the hashtable KUnit test suite.
2629	  It tests the basic functionality of the API defined in
2630	  include/linux/hashtable.h. For more information on KUnit and
2631	  unit tests in general please refer to the KUnit documentation
2632	  in Documentation/dev-tools/kunit/.
2633
2634	  If unsure, say N.
2635
2636config LINEAR_RANGES_TEST
2637	tristate "KUnit test for linear_ranges"
2638	depends on KUNIT
2639	select LINEAR_RANGES
2640	help
2641	  This builds the linear_ranges unit test, which runs on boot.
2642	  Tests the linear_ranges logic correctness.
2643	  For more information on KUnit and unit tests in general please refer
2644	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2645
2646	  If unsure, say N.
2647
2648config CMDLINE_KUNIT_TEST
2649	tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS
2650	depends on KUNIT
2651	default KUNIT_ALL_TESTS
2652	help
2653	  This builds the cmdline API unit test.
2654	  Tests the logic of API provided by cmdline.c.
2655	  For more information on KUnit and unit tests in general please refer
2656	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2657
2658	  If unsure, say N.
2659
2660config BITS_TEST
2661	tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS
2662	depends on KUNIT
2663	default KUNIT_ALL_TESTS
2664	help
2665	  This builds the bits unit test.
2666	  Tests the logic of macros defined in bits.h.
2667	  For more information on KUnit and unit tests in general please refer
2668	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2669
2670	  If unsure, say N.
2671
2672config SLUB_KUNIT_TEST
2673	tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS
2674	depends on SLUB_DEBUG && KUNIT
2675	default KUNIT_ALL_TESTS
2676	help
2677	  This builds SLUB allocator unit test.
2678	  Tests SLUB cache debugging functionality.
2679	  For more information on KUnit and unit tests in general please refer
2680	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2681
2682	  If unsure, say N.
2683
2684config RATIONAL_KUNIT_TEST
2685	tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS
2686	depends on KUNIT && RATIONAL
2687	default KUNIT_ALL_TESTS
2688	help
2689	  This builds the rational math unit test.
2690	  For more information on KUnit and unit tests in general please refer
2691	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2692
2693	  If unsure, say N.
2694
2695config MEMCPY_KUNIT_TEST
2696	tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS
2697	depends on KUNIT
2698	default KUNIT_ALL_TESTS
2699	help
2700	  Builds unit tests for memcpy(), memmove(), and memset() functions.
2701	  For more information on KUnit and unit tests in general please refer
2702	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2703
2704	  If unsure, say N.
2705
2706config MEMCPY_SLOW_KUNIT_TEST
2707	bool "Include exhaustive memcpy tests"
2708	depends on MEMCPY_KUNIT_TEST
2709	default y
2710	help
2711	  Some memcpy tests are quite exhaustive in checking for overlaps
2712	  and bit ranges. These can be very slow, so they are split out
2713	  as a separate config, in case they need to be disabled.
2714
2715	  Note this config option will be replaced by the use of KUnit test
2716	  attributes.
2717
2718config IS_SIGNED_TYPE_KUNIT_TEST
2719	tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS
2720	depends on KUNIT
2721	default KUNIT_ALL_TESTS
2722	help
2723	  Builds unit tests for the is_signed_type() macro.
2724
2725	  For more information on KUnit and unit tests in general please refer
2726	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2727
2728	  If unsure, say N.
2729
2730config OVERFLOW_KUNIT_TEST
2731	tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS
2732	depends on KUNIT
2733	default KUNIT_ALL_TESTS
2734	help
2735	  Builds unit tests for the check_*_overflow(), size_*(), allocation, and
2736	  related functions.
2737
2738	  For more information on KUnit and unit tests in general please refer
2739	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2740
2741	  If unsure, say N.
2742
2743config STACKINIT_KUNIT_TEST
2744	tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS
2745	depends on KUNIT
2746	default KUNIT_ALL_TESTS
2747	help
2748	  Test if the kernel is zero-initializing stack variables and
2749	  padding. Coverage is controlled by compiler flags,
2750	  CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO,
2751	  CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2752	  or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2753
2754config FORTIFY_KUNIT_TEST
2755	tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS
2756	depends on KUNIT && FORTIFY_SOURCE
2757	default KUNIT_ALL_TESTS
2758	help
2759	  Builds unit tests for checking internals of FORTIFY_SOURCE as used
2760	  by the str*() and mem*() family of functions. For testing runtime
2761	  traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests.
2762
2763config HW_BREAKPOINT_KUNIT_TEST
2764	bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS
2765	depends on HAVE_HW_BREAKPOINT
2766	depends on KUNIT=y
2767	default KUNIT_ALL_TESTS
2768	help
2769	  Tests for hw_breakpoint constraints accounting.
2770
2771	  If unsure, say N.
2772
2773config STRCAT_KUNIT_TEST
2774	tristate "Test strcat() family of functions at runtime" if !KUNIT_ALL_TESTS
2775	depends on KUNIT
2776	default KUNIT_ALL_TESTS
2777
2778config STRSCPY_KUNIT_TEST
2779	tristate "Test strscpy*() family of functions at runtime" if !KUNIT_ALL_TESTS
2780	depends on KUNIT
2781	default KUNIT_ALL_TESTS
2782
2783config SIPHASH_KUNIT_TEST
2784	tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS
2785	depends on KUNIT
2786	default KUNIT_ALL_TESTS
2787	help
2788	  Enable this option to test the kernel's siphash (<linux/siphash.h>) hash
2789	  functions on boot (or module load).
2790
2791	  This is intended to help people writing architecture-specific
2792	  optimized versions.  If unsure, say N.
2793
2794config TEST_UDELAY
2795	tristate "udelay test driver"
2796	help
2797	  This builds the "udelay_test" module that helps to make sure
2798	  that udelay() is working properly.
2799
2800	  If unsure, say N.
2801
2802config TEST_STATIC_KEYS
2803	tristate "Test static keys"
2804	depends on m
2805	help
2806	  Test the static key interfaces.
2807
2808	  If unsure, say N.
2809
2810config TEST_DYNAMIC_DEBUG
2811	tristate "Test DYNAMIC_DEBUG"
2812	depends on DYNAMIC_DEBUG
2813	help
2814	  This module registers a tracer callback to count enabled
2815	  pr_debugs in a 'do_debugging' function, then alters their
2816	  enablements, calls the function, and compares counts.
2817
2818	  If unsure, say N.
2819
2820config TEST_KMOD
2821	tristate "kmod stress tester"
2822	depends on m
2823	depends on NETDEVICES && NET_CORE && INET # for TUN
2824	depends on BLOCK
2825	depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS
2826	select TEST_LKM
2827	select XFS_FS
2828	select TUN
2829	select BTRFS_FS
2830	help
2831	  Test the kernel's module loading mechanism: kmod. kmod implements
2832	  support to load modules using the Linux kernel's usermode helper.
2833	  This test provides a series of tests against kmod.
2834
2835	  Although technically you can either build test_kmod as a module or
2836	  into the kernel we disallow building it into the kernel since
2837	  it stress tests request_module() and this will very likely cause
2838	  some issues by taking over precious threads available from other
2839	  module load requests, ultimately this could be fatal.
2840
2841	  To run tests run:
2842
2843	  tools/testing/selftests/kmod/kmod.sh --help
2844
2845	  If unsure, say N.
2846
2847config TEST_DEBUG_VIRTUAL
2848	tristate "Test CONFIG_DEBUG_VIRTUAL feature"
2849	depends on DEBUG_VIRTUAL
2850	help
2851	  Test the kernel's ability to detect incorrect calls to
2852	  virt_to_phys() done against the non-linear part of the
2853	  kernel's virtual address map.
2854
2855	  If unsure, say N.
2856
2857config TEST_MEMCAT_P
2858	tristate "Test memcat_p() helper function"
2859	help
2860	  Test the memcat_p() helper for correctly merging two
2861	  pointer arrays together.
2862
2863	  If unsure, say N.
2864
2865config TEST_LIVEPATCH
2866	tristate "Test livepatching"
2867	default n
2868	depends on DYNAMIC_DEBUG
2869	depends on LIVEPATCH
2870	depends on m
2871	help
2872	  Test kernel livepatching features for correctness.  The tests will
2873	  load test modules that will be livepatched in various scenarios.
2874
2875	  To run all the livepatching tests:
2876
2877	  make -C tools/testing/selftests TARGETS=livepatch run_tests
2878
2879	  Alternatively, individual tests may be invoked:
2880
2881	  tools/testing/selftests/livepatch/test-callbacks.sh
2882	  tools/testing/selftests/livepatch/test-livepatch.sh
2883	  tools/testing/selftests/livepatch/test-shadow-vars.sh
2884
2885	  If unsure, say N.
2886
2887config TEST_OBJAGG
2888	tristate "Perform selftest on object aggreration manager"
2889	default n
2890	depends on OBJAGG
2891	help
2892	  Enable this option to test object aggregation manager on boot
2893	  (or module load).
2894
2895config TEST_MEMINIT
2896	tristate "Test heap/page initialization"
2897	help
2898	  Test if the kernel is zero-initializing heap and page allocations.
2899	  This can be useful to test init_on_alloc and init_on_free features.
2900
2901	  If unsure, say N.
2902
2903config TEST_HMM
2904	tristate "Test HMM (Heterogeneous Memory Management)"
2905	depends on TRANSPARENT_HUGEPAGE
2906	depends on DEVICE_PRIVATE
2907	select HMM_MIRROR
2908	select MMU_NOTIFIER
2909	help
2910	  This is a pseudo device driver solely for testing HMM.
2911	  Say M here if you want to build the HMM test module.
2912	  Doing so will allow you to run tools/testing/selftest/vm/hmm-tests.
2913
2914	  If unsure, say N.
2915
2916config TEST_FREE_PAGES
2917	tristate "Test freeing pages"
2918	help
2919	  Test that a memory leak does not occur due to a race between
2920	  freeing a block of pages and a speculative page reference.
2921	  Loading this module is safe if your kernel has the bug fixed.
2922	  If the bug is not fixed, it will leak gigabytes of memory and
2923	  probably OOM your system.
2924
2925config TEST_FPU
2926	tristate "Test floating point operations in kernel space"
2927	depends on X86 && !KCOV_INSTRUMENT_ALL
2928	help
2929	  Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu
2930	  which will trigger a sequence of floating point operations. This is used
2931	  for self-testing floating point control register setting in
2932	  kernel_fpu_begin().
2933
2934	  If unsure, say N.
2935
2936config TEST_CLOCKSOURCE_WATCHDOG
2937	tristate "Test clocksource watchdog in kernel space"
2938	depends on CLOCKSOURCE_WATCHDOG
2939	help
2940	  Enable this option to create a kernel module that will trigger
2941	  a test of the clocksource watchdog.  This module may be loaded
2942	  via modprobe or insmod in which case it will run upon being
2943	  loaded, or it may be built in, in which case it will run
2944	  shortly after boot.
2945
2946	  If unsure, say N.
2947
2948endif # RUNTIME_TESTING_MENU
2949
2950config ARCH_USE_MEMTEST
2951	bool
2952	help
2953	  An architecture should select this when it uses early_memtest()
2954	  during boot process.
2955
2956config MEMTEST
2957	bool "Memtest"
2958	depends on ARCH_USE_MEMTEST
2959	help
2960	  This option adds a kernel parameter 'memtest', which allows memtest
2961	  to be set and executed.
2962	        memtest=0, mean disabled; -- default
2963	        memtest=1, mean do 1 test pattern;
2964	        ...
2965	        memtest=17, mean do 17 test patterns.
2966	  If you are unsure how to answer this question, answer N.
2967
2968
2969
2970config HYPERV_TESTING
2971	bool "Microsoft Hyper-V driver testing"
2972	default n
2973	depends on HYPERV && DEBUG_FS
2974	help
2975	  Select this option to enable Hyper-V vmbus testing.
2976
2977endmenu # "Kernel Testing and Coverage"
2978
2979menu "Rust hacking"
2980
2981config RUST_DEBUG_ASSERTIONS
2982	bool "Debug assertions"
2983	depends on RUST
2984	help
2985	  Enables rustc's `-Cdebug-assertions` codegen option.
2986
2987	  This flag lets you turn `cfg(debug_assertions)` conditional
2988	  compilation on or off. This can be used to enable extra debugging
2989	  code in development but not in production. For example, it controls
2990	  the behavior of the standard library's `debug_assert!` macro.
2991
2992	  Note that this will apply to all Rust code, including `core`.
2993
2994	  If unsure, say N.
2995
2996config RUST_OVERFLOW_CHECKS
2997	bool "Overflow checks"
2998	default y
2999	depends on RUST
3000	help
3001	  Enables rustc's `-Coverflow-checks` codegen option.
3002
3003	  This flag allows you to control the behavior of runtime integer
3004	  overflow. When overflow-checks are enabled, a Rust panic will occur
3005	  on overflow.
3006
3007	  Note that this will apply to all Rust code, including `core`.
3008
3009	  If unsure, say Y.
3010
3011config RUST_BUILD_ASSERT_ALLOW
3012	bool "Allow unoptimized build-time assertions"
3013	depends on RUST
3014	help
3015	  Controls how are `build_error!` and `build_assert!` handled during build.
3016
3017	  If calls to them exist in the binary, it may indicate a violated invariant
3018	  or that the optimizer failed to verify the invariant during compilation.
3019
3020	  This should not happen, thus by default the build is aborted. However,
3021	  as an escape hatch, you can choose Y here to ignore them during build
3022	  and let the check be carried at runtime (with `panic!` being called if
3023	  the check fails).
3024
3025	  If unsure, say N.
3026
3027config RUST_KERNEL_DOCTESTS
3028	bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS
3029	depends on RUST && KUNIT=y
3030	default KUNIT_ALL_TESTS
3031	help
3032	  This builds the documentation tests of the `kernel` crate
3033	  as KUnit tests.
3034
3035	  For more information on KUnit and unit tests in general,
3036	  please refer to the KUnit documentation in Documentation/dev-tools/kunit/.
3037
3038	  If unsure, say N.
3039
3040endmenu # "Rust"
3041
3042endmenu # Kernel hacking
3043