xref: /linux/lib/Kconfig.debug (revision 778e73d2411abc8f3a2d60dbf038acaec218792e)
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
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	  Also emits a message to dmesg when a process exits if that process
767	  used more stack space than previously exiting processes.
768
769	  This option will slow down process creation somewhat.
770
771config SCHED_STACK_END_CHECK
772	bool "Detect stack corruption on calls to schedule()"
773	depends on DEBUG_KERNEL
774	default n
775	help
776	  This option checks for a stack overrun on calls to schedule().
777	  If the stack end location is found to be over written always panic as
778	  the content of the corrupted region can no longer be trusted.
779	  This is to ensure no erroneous behaviour occurs which could result in
780	  data corruption or a sporadic crash at a later stage once the region
781	  is examined. The runtime overhead introduced is minimal.
782
783config ARCH_HAS_DEBUG_VM_PGTABLE
784	bool
785	help
786	  An architecture should select this when it can successfully
787	  build and run DEBUG_VM_PGTABLE.
788
789config DEBUG_VM_IRQSOFF
790	def_bool DEBUG_VM && !PREEMPT_RT
791
792config DEBUG_VM
793	bool "Debug VM"
794	depends on DEBUG_KERNEL
795	help
796	  Enable this to turn on extended checks in the virtual-memory system
797	  that may impact performance.
798
799	  If unsure, say N.
800
801config DEBUG_VM_SHOOT_LAZIES
802	bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation"
803	depends on DEBUG_VM
804	depends on MMU_LAZY_TLB_SHOOTDOWN
805	help
806	  Enable additional IPIs that ensure lazy tlb mm references are removed
807	  before the mm is freed.
808
809	  If unsure, say N.
810
811config DEBUG_VM_MAPLE_TREE
812	bool "Debug VM maple trees"
813	depends on DEBUG_VM
814	select DEBUG_MAPLE_TREE
815	help
816	  Enable VM maple tree debugging information and extra validations.
817
818	  If unsure, say N.
819
820config DEBUG_VM_RB
821	bool "Debug VM red-black trees"
822	depends on DEBUG_VM
823	help
824	  Enable VM red-black tree debugging information and extra validations.
825
826	  If unsure, say N.
827
828config DEBUG_VM_PGFLAGS
829	bool "Debug page-flags operations"
830	depends on DEBUG_VM
831	help
832	  Enables extra validation on page flags operations.
833
834	  If unsure, say N.
835
836config DEBUG_VM_PGTABLE
837	bool "Debug arch page table for semantics compliance"
838	depends on MMU
839	depends on ARCH_HAS_DEBUG_VM_PGTABLE
840	default y if DEBUG_VM
841	help
842	  This option provides a debug method which can be used to test
843	  architecture page table helper functions on various platforms in
844	  verifying if they comply with expected generic MM semantics. This
845	  will help architecture code in making sure that any changes or
846	  new additions of these helpers still conform to expected
847	  semantics of the generic MM. Platforms will have to opt in for
848	  this through ARCH_HAS_DEBUG_VM_PGTABLE.
849
850	  If unsure, say N.
851
852config ARCH_HAS_DEBUG_VIRTUAL
853	bool
854
855config DEBUG_VIRTUAL
856	bool "Debug VM translations"
857	depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
858	help
859	  Enable some costly sanity checks in virtual to page code. This can
860	  catch mistakes with virt_to_page() and friends.
861
862	  If unsure, say N.
863
864config DEBUG_NOMMU_REGIONS
865	bool "Debug the global anon/private NOMMU mapping region tree"
866	depends on DEBUG_KERNEL && !MMU
867	help
868	  This option causes the global tree of anonymous and private mapping
869	  regions to be regularly checked for invalid topology.
870
871config DEBUG_MEMORY_INIT
872	bool "Debug memory initialisation" if EXPERT
873	default !EXPERT
874	help
875	  Enable this for additional checks during memory initialisation.
876	  The sanity checks verify aspects of the VM such as the memory model
877	  and other information provided by the architecture. Verbose
878	  information will be printed at KERN_DEBUG loglevel depending
879	  on the mminit_loglevel= command-line option.
880
881	  If unsure, say Y
882
883config MEMORY_NOTIFIER_ERROR_INJECT
884	tristate "Memory hotplug notifier error injection module"
885	depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION
886	help
887	  This option provides the ability to inject artificial errors to
888	  memory hotplug notifier chain callbacks.  It is controlled through
889	  debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
890
891	  If the notifier call chain should be failed with some events
892	  notified, write the error code to "actions/<notifier event>/error".
893
894	  Example: Inject memory hotplug offline error (-12 == -ENOMEM)
895
896	  # cd /sys/kernel/debug/notifier-error-inject/memory
897	  # echo -12 > actions/MEM_GOING_OFFLINE/error
898	  # echo offline > /sys/devices/system/memory/memoryXXX/state
899	  bash: echo: write error: Cannot allocate memory
900
901	  To compile this code as a module, choose M here: the module will
902	  be called memory-notifier-error-inject.
903
904	  If unsure, say N.
905
906config DEBUG_PER_CPU_MAPS
907	bool "Debug access to per_cpu maps"
908	depends on DEBUG_KERNEL
909	depends on SMP
910	help
911	  Say Y to verify that the per_cpu map being accessed has
912	  been set up. This adds a fair amount of code to kernel memory
913	  and decreases performance.
914
915	  Say N if unsure.
916
917config DEBUG_KMAP_LOCAL
918	bool "Debug kmap_local temporary mappings"
919	depends on DEBUG_KERNEL && KMAP_LOCAL
920	help
921	  This option enables additional error checking for the kmap_local
922	  infrastructure.  Disable for production use.
923
924config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
925	bool
926
927config DEBUG_KMAP_LOCAL_FORCE_MAP
928	bool "Enforce kmap_local temporary mappings"
929	depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
930	select KMAP_LOCAL
931	select DEBUG_KMAP_LOCAL
932	help
933	  This option enforces temporary mappings through the kmap_local
934	  mechanism for non-highmem pages and on non-highmem systems.
935	  Disable this for production systems!
936
937config DEBUG_HIGHMEM
938	bool "Highmem debugging"
939	depends on DEBUG_KERNEL && HIGHMEM
940	select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
941	select DEBUG_KMAP_LOCAL
942	help
943	  This option enables additional error checking for high memory
944	  systems.  Disable for production systems.
945
946config HAVE_DEBUG_STACKOVERFLOW
947	bool
948
949config DEBUG_STACKOVERFLOW
950	bool "Check for stack overflows"
951	depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
952	help
953	  Say Y here if you want to check for overflows of kernel, IRQ
954	  and exception stacks (if your architecture uses them). This
955	  option will show detailed messages if free stack space drops
956	  below a certain limit.
957
958	  These kinds of bugs usually occur when call-chains in the
959	  kernel get too deep, especially when interrupts are
960	  involved.
961
962	  Use this in cases where you see apparently random memory
963	  corruption, especially if it appears in 'struct thread_info'
964
965	  If in doubt, say "N".
966
967source "lib/Kconfig.kasan"
968source "lib/Kconfig.kfence"
969source "lib/Kconfig.kmsan"
970
971endmenu # "Memory Debugging"
972
973config DEBUG_SHIRQ
974	bool "Debug shared IRQ handlers"
975	depends on DEBUG_KERNEL
976	help
977	  Enable this to generate a spurious interrupt just before a shared
978	  interrupt handler is deregistered (generating one when registering
979	  is currently disabled). Drivers need to handle this correctly. Some
980	  don't and need to be caught.
981
982menu "Debug Oops, Lockups and Hangs"
983
984config PANIC_ON_OOPS
985	bool "Panic on Oops"
986	help
987	  Say Y here to enable the kernel to panic when it oopses. This
988	  has the same effect as setting oops=panic on the kernel command
989	  line.
990
991	  This feature is useful to ensure that the kernel does not do
992	  anything erroneous after an oops which could result in data
993	  corruption or other issues.
994
995	  Say N if unsure.
996
997config PANIC_ON_OOPS_VALUE
998	int
999	range 0 1
1000	default 0 if !PANIC_ON_OOPS
1001	default 1 if PANIC_ON_OOPS
1002
1003config PANIC_TIMEOUT
1004	int "panic timeout"
1005	default 0
1006	help
1007	  Set the timeout value (in seconds) until a reboot occurs when
1008	  the kernel panics. If n = 0, then we wait forever. A timeout
1009	  value n > 0 will wait n seconds before rebooting, while a timeout
1010	  value n < 0 will reboot immediately.
1011
1012config LOCKUP_DETECTOR
1013	bool
1014
1015config SOFTLOCKUP_DETECTOR
1016	bool "Detect Soft Lockups"
1017	depends on DEBUG_KERNEL && !S390
1018	select LOCKUP_DETECTOR
1019	help
1020	  Say Y here to enable the kernel to act as a watchdog to detect
1021	  soft lockups.
1022
1023	  Softlockups are bugs that cause the kernel to loop in kernel
1024	  mode for more than 20 seconds, without giving other tasks a
1025	  chance to run.  The current stack trace is displayed upon
1026	  detection and the system will stay locked up.
1027
1028config BOOTPARAM_SOFTLOCKUP_PANIC
1029	bool "Panic (Reboot) On Soft Lockups"
1030	depends on SOFTLOCKUP_DETECTOR
1031	help
1032	  Say Y here to enable the kernel to panic on "soft lockups",
1033	  which are bugs that cause the kernel to loop in kernel
1034	  mode for more than 20 seconds (configurable using the watchdog_thresh
1035	  sysctl), without giving other tasks a chance to run.
1036
1037	  The panic can be used in combination with panic_timeout,
1038	  to cause the system to reboot automatically after a
1039	  lockup has been detected. This feature is useful for
1040	  high-availability systems that have uptime guarantees and
1041	  where a lockup must be resolved ASAP.
1042
1043	  Say N if unsure.
1044
1045config HAVE_HARDLOCKUP_DETECTOR_BUDDY
1046	bool
1047	depends on SMP
1048	default y
1049
1050#
1051# Global switch whether to build a hardlockup detector at all. It is available
1052# only when the architecture supports at least one implementation. There are
1053# two exceptions. The hardlockup detector is never enabled on:
1054#
1055#	s390: it reported many false positives there
1056#
1057#	sparc64: has a custom implementation which is not using the common
1058#		hardlockup command line options and sysctl interface.
1059#
1060config HARDLOCKUP_DETECTOR
1061	bool "Detect Hard Lockups"
1062	depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64
1063	depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH
1064	imply HARDLOCKUP_DETECTOR_PERF
1065	imply HARDLOCKUP_DETECTOR_BUDDY
1066	imply HARDLOCKUP_DETECTOR_ARCH
1067	select LOCKUP_DETECTOR
1068
1069	help
1070	  Say Y here to enable the kernel to act as a watchdog to detect
1071	  hard lockups.
1072
1073	  Hardlockups are bugs that cause the CPU to loop in kernel mode
1074	  for more than 10 seconds, without letting other interrupts have a
1075	  chance to run.  The current stack trace is displayed upon detection
1076	  and the system will stay locked up.
1077
1078#
1079# Note that arch-specific variants are always preferred.
1080#
1081config HARDLOCKUP_DETECTOR_PREFER_BUDDY
1082	bool "Prefer the buddy CPU hardlockup detector"
1083	depends on HARDLOCKUP_DETECTOR
1084	depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY
1085	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1086	help
1087	  Say Y here to prefer the buddy hardlockup detector over the perf one.
1088
1089	  With the buddy detector, each CPU uses its softlockup hrtimer
1090	  to check that the next CPU is processing hrtimer interrupts by
1091	  verifying that a counter is increasing.
1092
1093	  This hardlockup detector is useful on systems that don't have
1094	  an arch-specific hardlockup detector or if resources needed
1095	  for the hardlockup detector are better used for other things.
1096
1097config HARDLOCKUP_DETECTOR_PERF
1098	bool
1099	depends on HARDLOCKUP_DETECTOR
1100	depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY
1101	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1102	select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1103
1104config HARDLOCKUP_DETECTOR_BUDDY
1105	bool
1106	depends on HARDLOCKUP_DETECTOR
1107	depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY
1108	depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY
1109	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1110	select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1111
1112config HARDLOCKUP_DETECTOR_ARCH
1113	bool
1114	depends on HARDLOCKUP_DETECTOR
1115	depends on HAVE_HARDLOCKUP_DETECTOR_ARCH
1116	help
1117	  The arch-specific implementation of the hardlockup detector will
1118	  be used.
1119
1120#
1121# Both the "perf" and "buddy" hardlockup detectors count hrtimer
1122# interrupts. This config enables functions managing this common code.
1123#
1124config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1125	bool
1126	select SOFTLOCKUP_DETECTOR
1127
1128#
1129# Enables a timestamp based low pass filter to compensate for perf based
1130# hard lockup detection which runs too fast due to turbo modes.
1131#
1132config HARDLOCKUP_CHECK_TIMESTAMP
1133	bool
1134
1135config BOOTPARAM_HARDLOCKUP_PANIC
1136	bool "Panic (Reboot) On Hard Lockups"
1137	depends on HARDLOCKUP_DETECTOR
1138	help
1139	  Say Y here to enable the kernel to panic on "hard lockups",
1140	  which are bugs that cause the kernel to loop in kernel
1141	  mode with interrupts disabled for more than 10 seconds (configurable
1142	  using the watchdog_thresh sysctl).
1143
1144	  Say N if unsure.
1145
1146config DETECT_HUNG_TASK
1147	bool "Detect Hung Tasks"
1148	depends on DEBUG_KERNEL
1149	default SOFTLOCKUP_DETECTOR
1150	help
1151	  Say Y here to enable the kernel to detect "hung tasks",
1152	  which are bugs that cause the task to be stuck in
1153	  uninterruptible "D" state indefinitely.
1154
1155	  When a hung task is detected, the kernel will print the
1156	  current stack trace (which you should report), but the
1157	  task will stay in uninterruptible state. If lockdep is
1158	  enabled then all held locks will also be reported. This
1159	  feature has negligible overhead.
1160
1161config DEFAULT_HUNG_TASK_TIMEOUT
1162	int "Default timeout for hung task detection (in seconds)"
1163	depends on DETECT_HUNG_TASK
1164	default 120
1165	help
1166	  This option controls the default timeout (in seconds) used
1167	  to determine when a task has become non-responsive and should
1168	  be considered hung.
1169
1170	  It can be adjusted at runtime via the kernel.hung_task_timeout_secs
1171	  sysctl or by writing a value to
1172	  /proc/sys/kernel/hung_task_timeout_secs.
1173
1174	  A timeout of 0 disables the check.  The default is two minutes.
1175	  Keeping the default should be fine in most cases.
1176
1177config BOOTPARAM_HUNG_TASK_PANIC
1178	bool "Panic (Reboot) On Hung Tasks"
1179	depends on DETECT_HUNG_TASK
1180	help
1181	  Say Y here to enable the kernel to panic on "hung tasks",
1182	  which are bugs that cause the kernel to leave a task stuck
1183	  in uninterruptible "D" state.
1184
1185	  The panic can be used in combination with panic_timeout,
1186	  to cause the system to reboot automatically after a
1187	  hung task has been detected. This feature is useful for
1188	  high-availability systems that have uptime guarantees and
1189	  where a hung tasks must be resolved ASAP.
1190
1191	  Say N if unsure.
1192
1193config WQ_WATCHDOG
1194	bool "Detect Workqueue Stalls"
1195	depends on DEBUG_KERNEL
1196	help
1197	  Say Y here to enable stall detection on workqueues.  If a
1198	  worker pool doesn't make forward progress on a pending work
1199	  item for over a given amount of time, 30s by default, a
1200	  warning message is printed along with dump of workqueue
1201	  state.  This can be configured through kernel parameter
1202	  "workqueue.watchdog_thresh" and its sysfs counterpart.
1203
1204config WQ_CPU_INTENSIVE_REPORT
1205	bool "Report per-cpu work items which hog CPU for too long"
1206	depends on DEBUG_KERNEL
1207	help
1208	  Say Y here to enable reporting of concurrency-managed per-cpu work
1209	  items that hog CPUs for longer than
1210	  workqueue.cpu_intensive_thresh_us. Workqueue automatically
1211	  detects and excludes them from concurrency management to prevent
1212	  them from stalling other per-cpu work items. Occassional
1213	  triggering may not necessarily indicate a problem. Repeated
1214	  triggering likely indicates that the work item should be switched
1215	  to use an unbound workqueue.
1216
1217config TEST_LOCKUP
1218	tristate "Test module to generate lockups"
1219	depends on m
1220	help
1221	  This builds the "test_lockup" module that helps to make sure
1222	  that watchdogs and lockup detectors are working properly.
1223
1224	  Depending on module parameters it could emulate soft or hard
1225	  lockup, "hung task", or locking arbitrary lock for a long time.
1226	  Also it could generate series of lockups with cooling-down periods.
1227
1228	  If unsure, say N.
1229
1230endmenu # "Debug lockups and hangs"
1231
1232menu "Scheduler Debugging"
1233
1234config SCHED_DEBUG
1235	bool "Collect scheduler debugging info"
1236	depends on DEBUG_KERNEL && DEBUG_FS
1237	default y
1238	help
1239	  If you say Y here, the /sys/kernel/debug/sched file will be provided
1240	  that can help debug the scheduler. The runtime overhead of this
1241	  option is minimal.
1242
1243config SCHED_INFO
1244	bool
1245	default n
1246
1247config SCHEDSTATS
1248	bool "Collect scheduler statistics"
1249	depends on DEBUG_KERNEL && PROC_FS
1250	select SCHED_INFO
1251	help
1252	  If you say Y here, additional code will be inserted into the
1253	  scheduler and related routines to collect statistics about
1254	  scheduler behavior and provide them in /proc/schedstat.  These
1255	  stats may be useful for both tuning and debugging the scheduler
1256	  If you aren't debugging the scheduler or trying to tune a specific
1257	  application, you can say N to avoid the very slight overhead
1258	  this adds.
1259
1260endmenu
1261
1262config DEBUG_TIMEKEEPING
1263	bool "Enable extra timekeeping sanity checking"
1264	help
1265	  This option will enable additional timekeeping sanity checks
1266	  which may be helpful when diagnosing issues where timekeeping
1267	  problems are suspected.
1268
1269	  This may include checks in the timekeeping hotpaths, so this
1270	  option may have a (very small) performance impact to some
1271	  workloads.
1272
1273	  If unsure, say N.
1274
1275config DEBUG_PREEMPT
1276	bool "Debug preemptible kernel"
1277	depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT
1278	help
1279	  If you say Y here then the kernel will use a debug variant of the
1280	  commonly used smp_processor_id() function and will print warnings
1281	  if kernel code uses it in a preemption-unsafe way. Also, the kernel
1282	  will detect preemption count underflows.
1283
1284	  This option has potential to introduce high runtime overhead,
1285	  depending on workload as it triggers debugging routines for each
1286	  this_cpu operation. It should only be used for debugging purposes.
1287
1288menu "Lock Debugging (spinlocks, mutexes, etc...)"
1289
1290config LOCK_DEBUGGING_SUPPORT
1291	bool
1292	depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1293	default y
1294
1295config PROVE_LOCKING
1296	bool "Lock debugging: prove locking correctness"
1297	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1298	select LOCKDEP
1299	select DEBUG_SPINLOCK
1300	select DEBUG_MUTEXES if !PREEMPT_RT
1301	select DEBUG_RT_MUTEXES if RT_MUTEXES
1302	select DEBUG_RWSEMS
1303	select DEBUG_WW_MUTEX_SLOWPATH
1304	select DEBUG_LOCK_ALLOC
1305	select PREEMPT_COUNT if !ARCH_NO_PREEMPT
1306	select TRACE_IRQFLAGS
1307	default n
1308	help
1309	 This feature enables the kernel to prove that all locking
1310	 that occurs in the kernel runtime is mathematically
1311	 correct: that under no circumstance could an arbitrary (and
1312	 not yet triggered) combination of observed locking
1313	 sequences (on an arbitrary number of CPUs, running an
1314	 arbitrary number of tasks and interrupt contexts) cause a
1315	 deadlock.
1316
1317	 In short, this feature enables the kernel to report locking
1318	 related deadlocks before they actually occur.
1319
1320	 The proof does not depend on how hard and complex a
1321	 deadlock scenario would be to trigger: how many
1322	 participant CPUs, tasks and irq-contexts would be needed
1323	 for it to trigger. The proof also does not depend on
1324	 timing: if a race and a resulting deadlock is possible
1325	 theoretically (no matter how unlikely the race scenario
1326	 is), it will be proven so and will immediately be
1327	 reported by the kernel (once the event is observed that
1328	 makes the deadlock theoretically possible).
1329
1330	 If a deadlock is impossible (i.e. the locking rules, as
1331	 observed by the kernel, are mathematically correct), the
1332	 kernel reports nothing.
1333
1334	 NOTE: this feature can also be enabled for rwlocks, mutexes
1335	 and rwsems - in which case all dependencies between these
1336	 different locking variants are observed and mapped too, and
1337	 the proof of observed correctness is also maintained for an
1338	 arbitrary combination of these separate locking variants.
1339
1340	 For more details, see Documentation/locking/lockdep-design.rst.
1341
1342config PROVE_RAW_LOCK_NESTING
1343	bool "Enable raw_spinlock - spinlock nesting checks"
1344	depends on PROVE_LOCKING
1345	default n
1346	help
1347	 Enable the raw_spinlock vs. spinlock nesting checks which ensure
1348	 that the lock nesting rules for PREEMPT_RT enabled kernels are
1349	 not violated.
1350
1351	 NOTE: There are known nesting problems. So if you enable this
1352	 option expect lockdep splats until these problems have been fully
1353	 addressed which is work in progress. This config switch allows to
1354	 identify and analyze these problems. It will be removed and the
1355	 check permanently enabled once the main issues have been fixed.
1356
1357	 If unsure, select N.
1358
1359config LOCK_STAT
1360	bool "Lock usage statistics"
1361	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1362	select LOCKDEP
1363	select DEBUG_SPINLOCK
1364	select DEBUG_MUTEXES if !PREEMPT_RT
1365	select DEBUG_RT_MUTEXES if RT_MUTEXES
1366	select DEBUG_LOCK_ALLOC
1367	default n
1368	help
1369	 This feature enables tracking lock contention points
1370
1371	 For more details, see Documentation/locking/lockstat.rst
1372
1373	 This also enables lock events required by "perf lock",
1374	 subcommand of perf.
1375	 If you want to use "perf lock", you also need to turn on
1376	 CONFIG_EVENT_TRACING.
1377
1378	 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1379	 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1380
1381config DEBUG_RT_MUTEXES
1382	bool "RT Mutex debugging, deadlock detection"
1383	depends on DEBUG_KERNEL && RT_MUTEXES
1384	help
1385	 This allows rt mutex semantics violations and rt mutex related
1386	 deadlocks (lockups) to be detected and reported automatically.
1387
1388config DEBUG_SPINLOCK
1389	bool "Spinlock and rw-lock debugging: basic checks"
1390	depends on DEBUG_KERNEL
1391	select UNINLINE_SPIN_UNLOCK
1392	help
1393	  Say Y here and build SMP to catch missing spinlock initialization
1394	  and certain other kinds of spinlock errors commonly made.  This is
1395	  best used in conjunction with the NMI watchdog so that spinlock
1396	  deadlocks are also debuggable.
1397
1398config DEBUG_MUTEXES
1399	bool "Mutex debugging: basic checks"
1400	depends on DEBUG_KERNEL && !PREEMPT_RT
1401	help
1402	 This feature allows mutex semantics violations to be detected and
1403	 reported.
1404
1405config DEBUG_WW_MUTEX_SLOWPATH
1406	bool "Wait/wound mutex debugging: Slowpath testing"
1407	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1408	select DEBUG_LOCK_ALLOC
1409	select DEBUG_SPINLOCK
1410	select DEBUG_MUTEXES if !PREEMPT_RT
1411	select DEBUG_RT_MUTEXES if PREEMPT_RT
1412	help
1413	 This feature enables slowpath testing for w/w mutex users by
1414	 injecting additional -EDEADLK wound/backoff cases. Together with
1415	 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1416	 will test all possible w/w mutex interface abuse with the
1417	 exception of simply not acquiring all the required locks.
1418	 Note that this feature can introduce significant overhead, so
1419	 it really should not be enabled in a production or distro kernel,
1420	 even a debug kernel.  If you are a driver writer, enable it.  If
1421	 you are a distro, do not.
1422
1423config DEBUG_RWSEMS
1424	bool "RW Semaphore debugging: basic checks"
1425	depends on DEBUG_KERNEL
1426	help
1427	  This debugging feature allows mismatched rw semaphore locks
1428	  and unlocks to be detected and reported.
1429
1430config DEBUG_LOCK_ALLOC
1431	bool "Lock debugging: detect incorrect freeing of live locks"
1432	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1433	select DEBUG_SPINLOCK
1434	select DEBUG_MUTEXES if !PREEMPT_RT
1435	select DEBUG_RT_MUTEXES if RT_MUTEXES
1436	select LOCKDEP
1437	help
1438	 This feature will check whether any held lock (spinlock, rwlock,
1439	 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1440	 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1441	 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1442	 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1443	 held during task exit.
1444
1445config LOCKDEP
1446	bool
1447	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1448	select STACKTRACE
1449	select KALLSYMS
1450	select KALLSYMS_ALL
1451
1452config LOCKDEP_SMALL
1453	bool
1454
1455config LOCKDEP_BITS
1456	int "Bitsize for MAX_LOCKDEP_ENTRIES"
1457	depends on LOCKDEP && !LOCKDEP_SMALL
1458	range 10 30
1459	default 15
1460	help
1461	  Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message.
1462
1463config LOCKDEP_CHAINS_BITS
1464	int "Bitsize for MAX_LOCKDEP_CHAINS"
1465	depends on LOCKDEP && !LOCKDEP_SMALL
1466	range 10 30
1467	default 16
1468	help
1469	  Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message.
1470
1471config LOCKDEP_STACK_TRACE_BITS
1472	int "Bitsize for MAX_STACK_TRACE_ENTRIES"
1473	depends on LOCKDEP && !LOCKDEP_SMALL
1474	range 10 30
1475	default 19
1476	help
1477	  Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message.
1478
1479config LOCKDEP_STACK_TRACE_HASH_BITS
1480	int "Bitsize for STACK_TRACE_HASH_SIZE"
1481	depends on LOCKDEP && !LOCKDEP_SMALL
1482	range 10 30
1483	default 14
1484	help
1485	  Try increasing this value if you need large STACK_TRACE_HASH_SIZE.
1486
1487config LOCKDEP_CIRCULAR_QUEUE_BITS
1488	int "Bitsize for elements in circular_queue struct"
1489	depends on LOCKDEP
1490	range 10 30
1491	default 12
1492	help
1493	  Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure.
1494
1495config DEBUG_LOCKDEP
1496	bool "Lock dependency engine debugging"
1497	depends on DEBUG_KERNEL && LOCKDEP
1498	select DEBUG_IRQFLAGS
1499	help
1500	  If you say Y here, the lock dependency engine will do
1501	  additional runtime checks to debug itself, at the price
1502	  of more runtime overhead.
1503
1504config DEBUG_ATOMIC_SLEEP
1505	bool "Sleep inside atomic section checking"
1506	select PREEMPT_COUNT
1507	depends on DEBUG_KERNEL
1508	depends on !ARCH_NO_PREEMPT
1509	help
1510	  If you say Y here, various routines which may sleep will become very
1511	  noisy if they are called inside atomic sections: when a spinlock is
1512	  held, inside an rcu read side critical section, inside preempt disabled
1513	  sections, inside an interrupt, etc...
1514
1515config DEBUG_LOCKING_API_SELFTESTS
1516	bool "Locking API boot-time self-tests"
1517	depends on DEBUG_KERNEL
1518	help
1519	  Say Y here if you want the kernel to run a short self-test during
1520	  bootup. The self-test checks whether common types of locking bugs
1521	  are detected by debugging mechanisms or not. (if you disable
1522	  lock debugging then those bugs won't be detected of course.)
1523	  The following locking APIs are covered: spinlocks, rwlocks,
1524	  mutexes and rwsems.
1525
1526config LOCK_TORTURE_TEST
1527	tristate "torture tests for locking"
1528	depends on DEBUG_KERNEL
1529	select TORTURE_TEST
1530	help
1531	  This option provides a kernel module that runs torture tests
1532	  on kernel locking primitives.  The kernel module may be built
1533	  after the fact on the running kernel to be tested, if desired.
1534
1535	  Say Y here if you want kernel locking-primitive torture tests
1536	  to be built into the kernel.
1537	  Say M if you want these torture tests to build as a module.
1538	  Say N if you are unsure.
1539
1540config WW_MUTEX_SELFTEST
1541	tristate "Wait/wound mutex selftests"
1542	help
1543	  This option provides a kernel module that runs tests on the
1544	  on the struct ww_mutex locking API.
1545
1546	  It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1547	  with this test harness.
1548
1549	  Say M if you want these self tests to build as a module.
1550	  Say N if you are unsure.
1551
1552config SCF_TORTURE_TEST
1553	tristate "torture tests for smp_call_function*()"
1554	depends on DEBUG_KERNEL
1555	select TORTURE_TEST
1556	help
1557	  This option provides a kernel module that runs torture tests
1558	  on the smp_call_function() family of primitives.  The kernel
1559	  module may be built after the fact on the running kernel to
1560	  be tested, if desired.
1561
1562config CSD_LOCK_WAIT_DEBUG
1563	bool "Debugging for csd_lock_wait(), called from smp_call_function*()"
1564	depends on DEBUG_KERNEL
1565	depends on 64BIT
1566	default n
1567	help
1568	  This option enables debug prints when CPUs are slow to respond
1569	  to the smp_call_function*() IPI wrappers.  These debug prints
1570	  include the IPI handler function currently executing (if any)
1571	  and relevant stack traces.
1572
1573config CSD_LOCK_WAIT_DEBUG_DEFAULT
1574	bool "Default csd_lock_wait() debugging on at boot time"
1575	depends on CSD_LOCK_WAIT_DEBUG
1576	depends on 64BIT
1577	default n
1578	help
1579	  This option causes the csdlock_debug= kernel boot parameter to
1580	  default to 1 (basic debugging) instead of 0 (no debugging).
1581
1582endmenu # lock debugging
1583
1584config TRACE_IRQFLAGS
1585	depends on TRACE_IRQFLAGS_SUPPORT
1586	bool
1587	help
1588	  Enables hooks to interrupt enabling and disabling for
1589	  either tracing or lock debugging.
1590
1591config TRACE_IRQFLAGS_NMI
1592	def_bool y
1593	depends on TRACE_IRQFLAGS
1594	depends on TRACE_IRQFLAGS_NMI_SUPPORT
1595
1596config NMI_CHECK_CPU
1597	bool "Debugging for CPUs failing to respond to backtrace requests"
1598	depends on DEBUG_KERNEL
1599	depends on X86
1600	default n
1601	help
1602	  Enables debug prints when a CPU fails to respond to a given
1603	  backtrace NMI.  These prints provide some reasons why a CPU
1604	  might legitimately be failing to respond, for example, if it
1605	  is offline of if ignore_nmis is set.
1606
1607config DEBUG_IRQFLAGS
1608	bool "Debug IRQ flag manipulation"
1609	help
1610	  Enables checks for potentially unsafe enabling or disabling of
1611	  interrupts, such as calling raw_local_irq_restore() when interrupts
1612	  are enabled.
1613
1614config STACKTRACE
1615	bool "Stack backtrace support"
1616	depends on STACKTRACE_SUPPORT
1617	help
1618	  This option causes the kernel to create a /proc/pid/stack for
1619	  every process, showing its current stack trace.
1620	  It is also used by various kernel debugging features that require
1621	  stack trace generation.
1622
1623config WARN_ALL_UNSEEDED_RANDOM
1624	bool "Warn for all uses of unseeded randomness"
1625	default n
1626	help
1627	  Some parts of the kernel contain bugs relating to their use of
1628	  cryptographically secure random numbers before it's actually possible
1629	  to generate those numbers securely. This setting ensures that these
1630	  flaws don't go unnoticed, by enabling a message, should this ever
1631	  occur. This will allow people with obscure setups to know when things
1632	  are going wrong, so that they might contact developers about fixing
1633	  it.
1634
1635	  Unfortunately, on some models of some architectures getting
1636	  a fully seeded CRNG is extremely difficult, and so this can
1637	  result in dmesg getting spammed for a surprisingly long
1638	  time.  This is really bad from a security perspective, and
1639	  so architecture maintainers really need to do what they can
1640	  to get the CRNG seeded sooner after the system is booted.
1641	  However, since users cannot do anything actionable to
1642	  address this, by default this option is disabled.
1643
1644	  Say Y here if you want to receive warnings for all uses of
1645	  unseeded randomness.  This will be of use primarily for
1646	  those developers interested in improving the security of
1647	  Linux kernels running on their architecture (or
1648	  subarchitecture).
1649
1650config DEBUG_KOBJECT
1651	bool "kobject debugging"
1652	depends on DEBUG_KERNEL
1653	help
1654	  If you say Y here, some extra kobject debugging messages will be sent
1655	  to the syslog.
1656
1657config DEBUG_KOBJECT_RELEASE
1658	bool "kobject release debugging"
1659	depends on DEBUG_OBJECTS_TIMERS
1660	help
1661	  kobjects are reference counted objects.  This means that their
1662	  last reference count put is not predictable, and the kobject can
1663	  live on past the point at which a driver decides to drop its
1664	  initial reference to the kobject gained on allocation.  An
1665	  example of this would be a struct device which has just been
1666	  unregistered.
1667
1668	  However, some buggy drivers assume that after such an operation,
1669	  the memory backing the kobject can be immediately freed.  This
1670	  goes completely against the principles of a refcounted object.
1671
1672	  If you say Y here, the kernel will delay the release of kobjects
1673	  on the last reference count to improve the visibility of this
1674	  kind of kobject release bug.
1675
1676config HAVE_DEBUG_BUGVERBOSE
1677	bool
1678
1679menu "Debug kernel data structures"
1680
1681config DEBUG_LIST
1682	bool "Debug linked list manipulation"
1683	depends on DEBUG_KERNEL
1684	select LIST_HARDENED
1685	help
1686	  Enable this to turn on extended checks in the linked-list walking
1687	  routines.
1688
1689	  This option trades better quality error reports for performance, and
1690	  is more suitable for kernel debugging. If you care about performance,
1691	  you should only enable CONFIG_LIST_HARDENED instead.
1692
1693	  If unsure, say N.
1694
1695config DEBUG_PLIST
1696	bool "Debug priority linked list manipulation"
1697	depends on DEBUG_KERNEL
1698	help
1699	  Enable this to turn on extended checks in the priority-ordered
1700	  linked-list (plist) walking routines.  This checks the entire
1701	  list multiple times during each manipulation.
1702
1703	  If unsure, say N.
1704
1705config DEBUG_SG
1706	bool "Debug SG table operations"
1707	depends on DEBUG_KERNEL
1708	help
1709	  Enable this to turn on checks on scatter-gather tables. This can
1710	  help find problems with drivers that do not properly initialize
1711	  their sg tables.
1712
1713	  If unsure, say N.
1714
1715config DEBUG_NOTIFIERS
1716	bool "Debug notifier call chains"
1717	depends on DEBUG_KERNEL
1718	help
1719	  Enable this to turn on sanity checking for notifier call chains.
1720	  This is most useful for kernel developers to make sure that
1721	  modules properly unregister themselves from notifier chains.
1722	  This is a relatively cheap check but if you care about maximum
1723	  performance, say N.
1724
1725config DEBUG_CLOSURES
1726	bool "Debug closures (bcache async widgits)"
1727	depends on CLOSURES
1728	select DEBUG_FS
1729	help
1730	  Keeps all active closures in a linked list and provides a debugfs
1731	  interface to list them, which makes it possible to see asynchronous
1732	  operations that get stuck.
1733
1734config DEBUG_MAPLE_TREE
1735	bool "Debug maple trees"
1736	depends on DEBUG_KERNEL
1737	help
1738	  Enable maple tree debugging information and extra validations.
1739
1740	  If unsure, say N.
1741
1742endmenu
1743
1744source "kernel/rcu/Kconfig.debug"
1745
1746config DEBUG_WQ_FORCE_RR_CPU
1747	bool "Force round-robin CPU selection for unbound work items"
1748	depends on DEBUG_KERNEL
1749	default n
1750	help
1751	  Workqueue used to implicitly guarantee that work items queued
1752	  without explicit CPU specified are put on the local CPU.  This
1753	  guarantee is no longer true and while local CPU is still
1754	  preferred work items may be put on foreign CPUs.  Kernel
1755	  parameter "workqueue.debug_force_rr_cpu" is added to force
1756	  round-robin CPU selection to flush out usages which depend on the
1757	  now broken guarantee.  This config option enables the debug
1758	  feature by default.  When enabled, memory and cache locality will
1759	  be impacted.
1760
1761config CPU_HOTPLUG_STATE_CONTROL
1762	bool "Enable CPU hotplug state control"
1763	depends on DEBUG_KERNEL
1764	depends on HOTPLUG_CPU
1765	default n
1766	help
1767	  Allows to write steps between "offline" and "online" to the CPUs
1768	  sysfs target file so states can be stepped granular. This is a debug
1769	  option for now as the hotplug machinery cannot be stopped and
1770	  restarted at arbitrary points yet.
1771
1772	  Say N if your are unsure.
1773
1774config LATENCYTOP
1775	bool "Latency measuring infrastructure"
1776	depends on DEBUG_KERNEL
1777	depends on STACKTRACE_SUPPORT
1778	depends on PROC_FS
1779	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
1780	select KALLSYMS
1781	select KALLSYMS_ALL
1782	select STACKTRACE
1783	select SCHEDSTATS
1784	help
1785	  Enable this option if you want to use the LatencyTOP tool
1786	  to find out which userspace is blocking on what kernel operations.
1787
1788config DEBUG_CGROUP_REF
1789	bool "Disable inlining of cgroup css reference count functions"
1790	depends on DEBUG_KERNEL
1791	depends on CGROUPS
1792	depends on KPROBES
1793	default n
1794	help
1795	  Force cgroup css reference count functions to not be inlined so
1796	  that they can be kprobed for debugging.
1797
1798source "kernel/trace/Kconfig"
1799
1800config PROVIDE_OHCI1394_DMA_INIT
1801	bool "Remote debugging over FireWire early on boot"
1802	depends on PCI && X86
1803	help
1804	  If you want to debug problems which hang or crash the kernel early
1805	  on boot and the crashing machine has a FireWire port, you can use
1806	  this feature to remotely access the memory of the crashed machine
1807	  over FireWire. This employs remote DMA as part of the OHCI1394
1808	  specification which is now the standard for FireWire controllers.
1809
1810	  With remote DMA, you can monitor the printk buffer remotely using
1811	  firescope and access all memory below 4GB using fireproxy from gdb.
1812	  Even controlling a kernel debugger is possible using remote DMA.
1813
1814	  Usage:
1815
1816	  If ohci1394_dma=early is used as boot parameter, it will initialize
1817	  all OHCI1394 controllers which are found in the PCI config space.
1818
1819	  As all changes to the FireWire bus such as enabling and disabling
1820	  devices cause a bus reset and thereby disable remote DMA for all
1821	  devices, be sure to have the cable plugged and FireWire enabled on
1822	  the debugging host before booting the debug target for debugging.
1823
1824	  This code (~1k) is freed after boot. By then, the firewire stack
1825	  in charge of the OHCI-1394 controllers should be used instead.
1826
1827	  See Documentation/core-api/debugging-via-ohci1394.rst for more information.
1828
1829source "samples/Kconfig"
1830
1831config ARCH_HAS_DEVMEM_IS_ALLOWED
1832	bool
1833
1834config STRICT_DEVMEM
1835	bool "Filter access to /dev/mem"
1836	depends on MMU && DEVMEM
1837	depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED
1838	default y if PPC || X86 || ARM64
1839	help
1840	  If this option is disabled, you allow userspace (root) access to all
1841	  of memory, including kernel and userspace memory. Accidental
1842	  access to this is obviously disastrous, but specific access can
1843	  be used by people debugging the kernel. Note that with PAT support
1844	  enabled, even in this case there are restrictions on /dev/mem
1845	  use due to the cache aliasing requirements.
1846
1847	  If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
1848	  file only allows userspace access to PCI space and the BIOS code and
1849	  data regions.  This is sufficient for dosemu and X and all common
1850	  users of /dev/mem.
1851
1852	  If in doubt, say Y.
1853
1854config IO_STRICT_DEVMEM
1855	bool "Filter I/O access to /dev/mem"
1856	depends on STRICT_DEVMEM
1857	help
1858	  If this option is disabled, you allow userspace (root) access to all
1859	  io-memory regardless of whether a driver is actively using that
1860	  range.  Accidental access to this is obviously disastrous, but
1861	  specific access can be used by people debugging kernel drivers.
1862
1863	  If this option is switched on, the /dev/mem file only allows
1864	  userspace access to *idle* io-memory ranges (see /proc/iomem) This
1865	  may break traditional users of /dev/mem (dosemu, legacy X, etc...)
1866	  if the driver using a given range cannot be disabled.
1867
1868	  If in doubt, say Y.
1869
1870menu "$(SRCARCH) Debugging"
1871
1872source "arch/$(SRCARCH)/Kconfig.debug"
1873
1874endmenu
1875
1876menu "Kernel Testing and Coverage"
1877
1878source "lib/kunit/Kconfig"
1879
1880config NOTIFIER_ERROR_INJECTION
1881	tristate "Notifier error injection"
1882	depends on DEBUG_KERNEL
1883	select DEBUG_FS
1884	help
1885	  This option provides the ability to inject artificial errors to
1886	  specified notifier chain callbacks. It is useful to test the error
1887	  handling of notifier call chain failures.
1888
1889	  Say N if unsure.
1890
1891config PM_NOTIFIER_ERROR_INJECT
1892	tristate "PM notifier error injection module"
1893	depends on PM && NOTIFIER_ERROR_INJECTION
1894	default m if PM_DEBUG
1895	help
1896	  This option provides the ability to inject artificial errors to
1897	  PM notifier chain callbacks.  It is controlled through debugfs
1898	  interface /sys/kernel/debug/notifier-error-inject/pm
1899
1900	  If the notifier call chain should be failed with some events
1901	  notified, write the error code to "actions/<notifier event>/error".
1902
1903	  Example: Inject PM suspend error (-12 = -ENOMEM)
1904
1905	  # cd /sys/kernel/debug/notifier-error-inject/pm/
1906	  # echo -12 > actions/PM_SUSPEND_PREPARE/error
1907	  # echo mem > /sys/power/state
1908	  bash: echo: write error: Cannot allocate memory
1909
1910	  To compile this code as a module, choose M here: the module will
1911	  be called pm-notifier-error-inject.
1912
1913	  If unsure, say N.
1914
1915config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1916	tristate "OF reconfig notifier error injection module"
1917	depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1918	help
1919	  This option provides the ability to inject artificial errors to
1920	  OF reconfig notifier chain callbacks.  It is controlled
1921	  through debugfs interface under
1922	  /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1923
1924	  If the notifier call chain should be failed with some events
1925	  notified, write the error code to "actions/<notifier event>/error".
1926
1927	  To compile this code as a module, choose M here: the module will
1928	  be called of-reconfig-notifier-error-inject.
1929
1930	  If unsure, say N.
1931
1932config NETDEV_NOTIFIER_ERROR_INJECT
1933	tristate "Netdev notifier error injection module"
1934	depends on NET && NOTIFIER_ERROR_INJECTION
1935	help
1936	  This option provides the ability to inject artificial errors to
1937	  netdevice notifier chain callbacks.  It is controlled through debugfs
1938	  interface /sys/kernel/debug/notifier-error-inject/netdev
1939
1940	  If the notifier call chain should be failed with some events
1941	  notified, write the error code to "actions/<notifier event>/error".
1942
1943	  Example: Inject netdevice mtu change error (-22 = -EINVAL)
1944
1945	  # cd /sys/kernel/debug/notifier-error-inject/netdev
1946	  # echo -22 > actions/NETDEV_CHANGEMTU/error
1947	  # ip link set eth0 mtu 1024
1948	  RTNETLINK answers: Invalid argument
1949
1950	  To compile this code as a module, choose M here: the module will
1951	  be called netdev-notifier-error-inject.
1952
1953	  If unsure, say N.
1954
1955config FUNCTION_ERROR_INJECTION
1956	bool "Fault-injections of functions"
1957	depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
1958	help
1959	  Add fault injections into various functions that are annotated with
1960	  ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return
1961	  value of these functions. This is useful to test error paths of code.
1962
1963	  If unsure, say N
1964
1965config FAULT_INJECTION
1966	bool "Fault-injection framework"
1967	depends on DEBUG_KERNEL
1968	help
1969	  Provide fault-injection framework.
1970	  For more details, see Documentation/fault-injection/.
1971
1972config FAILSLAB
1973	bool "Fault-injection capability for kmalloc"
1974	depends on FAULT_INJECTION
1975	help
1976	  Provide fault-injection capability for kmalloc.
1977
1978config FAIL_PAGE_ALLOC
1979	bool "Fault-injection capability for alloc_pages()"
1980	depends on FAULT_INJECTION
1981	help
1982	  Provide fault-injection capability for alloc_pages().
1983
1984config FAULT_INJECTION_USERCOPY
1985	bool "Fault injection capability for usercopy functions"
1986	depends on FAULT_INJECTION
1987	help
1988	  Provides fault-injection capability to inject failures
1989	  in usercopy functions (copy_from_user(), get_user(), ...).
1990
1991config FAIL_MAKE_REQUEST
1992	bool "Fault-injection capability for disk IO"
1993	depends on FAULT_INJECTION && BLOCK
1994	help
1995	  Provide fault-injection capability for disk IO.
1996
1997config FAIL_IO_TIMEOUT
1998	bool "Fault-injection capability for faking disk interrupts"
1999	depends on FAULT_INJECTION && BLOCK
2000	help
2001	  Provide fault-injection capability on end IO handling. This
2002	  will make the block layer "forget" an interrupt as configured,
2003	  thus exercising the error handling.
2004
2005	  Only works with drivers that use the generic timeout handling,
2006	  for others it won't do anything.
2007
2008config FAIL_FUTEX
2009	bool "Fault-injection capability for futexes"
2010	select DEBUG_FS
2011	depends on FAULT_INJECTION && FUTEX
2012	help
2013	  Provide fault-injection capability for futexes.
2014
2015config FAULT_INJECTION_DEBUG_FS
2016	bool "Debugfs entries for fault-injection capabilities"
2017	depends on FAULT_INJECTION && SYSFS && DEBUG_FS
2018	help
2019	  Enable configuration of fault-injection capabilities via debugfs.
2020
2021config FAIL_FUNCTION
2022	bool "Fault-injection capability for functions"
2023	depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
2024	help
2025	  Provide function-based fault-injection capability.
2026	  This will allow you to override a specific function with a return
2027	  with given return value. As a result, function caller will see
2028	  an error value and have to handle it. This is useful to test the
2029	  error handling in various subsystems.
2030
2031config FAIL_MMC_REQUEST
2032	bool "Fault-injection capability for MMC IO"
2033	depends on FAULT_INJECTION_DEBUG_FS && MMC
2034	help
2035	  Provide fault-injection capability for MMC IO.
2036	  This will make the mmc core return data errors. This is
2037	  useful to test the error handling in the mmc block device
2038	  and to test how the mmc host driver handles retries from
2039	  the block device.
2040
2041config FAIL_SUNRPC
2042	bool "Fault-injection capability for SunRPC"
2043	depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG
2044	help
2045	  Provide fault-injection capability for SunRPC and
2046	  its consumers.
2047
2048config FAULT_INJECTION_CONFIGFS
2049	bool "Configfs interface for fault-injection capabilities"
2050	depends on FAULT_INJECTION
2051	select CONFIGFS_FS
2052	help
2053	  This option allows configfs-based drivers to dynamically configure
2054	  fault-injection via configfs.  Each parameter for driver-specific
2055	  fault-injection can be made visible as a configfs attribute in a
2056	  configfs group.
2057
2058
2059config FAULT_INJECTION_STACKTRACE_FILTER
2060	bool "stacktrace filter for fault-injection capabilities"
2061	depends on FAULT_INJECTION
2062	depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT
2063	select STACKTRACE
2064	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
2065	help
2066	  Provide stacktrace filter for fault-injection capabilities
2067
2068config ARCH_HAS_KCOV
2069	bool
2070	help
2071	  An architecture should select this when it can successfully
2072	  build and run with CONFIG_KCOV. This typically requires
2073	  disabling instrumentation for some early boot code.
2074
2075config CC_HAS_SANCOV_TRACE_PC
2076	def_bool $(cc-option,-fsanitize-coverage=trace-pc)
2077
2078
2079config KCOV
2080	bool "Code coverage for fuzzing"
2081	depends on ARCH_HAS_KCOV
2082	depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
2083	depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \
2084		   GCC_VERSION >= 120000 || CLANG_VERSION >= 130000
2085	select DEBUG_FS
2086	select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
2087	select OBJTOOL if HAVE_NOINSTR_HACK
2088	help
2089	  KCOV exposes kernel code coverage information in a form suitable
2090	  for coverage-guided fuzzing (randomized testing).
2091
2092	  For more details, see Documentation/dev-tools/kcov.rst.
2093
2094config KCOV_ENABLE_COMPARISONS
2095	bool "Enable comparison operands collection by KCOV"
2096	depends on KCOV
2097	depends on $(cc-option,-fsanitize-coverage=trace-cmp)
2098	help
2099	  KCOV also exposes operands of every comparison in the instrumented
2100	  code along with operand sizes and PCs of the comparison instructions.
2101	  These operands can be used by fuzzing engines to improve the quality
2102	  of fuzzing coverage.
2103
2104config KCOV_INSTRUMENT_ALL
2105	bool "Instrument all code by default"
2106	depends on KCOV
2107	default y
2108	help
2109	  If you are doing generic system call fuzzing (like e.g. syzkaller),
2110	  then you will want to instrument the whole kernel and you should
2111	  say y here. If you are doing more targeted fuzzing (like e.g.
2112	  filesystem fuzzing with AFL) then you will want to enable coverage
2113	  for more specific subsets of files, and should say n here.
2114
2115config KCOV_IRQ_AREA_SIZE
2116	hex "Size of interrupt coverage collection area in words"
2117	depends on KCOV
2118	default 0x40000
2119	help
2120	  KCOV uses preallocated per-cpu areas to collect coverage from
2121	  soft interrupts. This specifies the size of those areas in the
2122	  number of unsigned long words.
2123
2124menuconfig RUNTIME_TESTING_MENU
2125	bool "Runtime Testing"
2126	def_bool y
2127
2128if RUNTIME_TESTING_MENU
2129
2130config TEST_DHRY
2131	tristate "Dhrystone benchmark test"
2132	help
2133	  Enable this to include the Dhrystone 2.1 benchmark.  This test
2134	  calculates the number of Dhrystones per second, and the number of
2135	  DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided
2136	  by 1757 (the number of Dhrystones per second obtained on the VAX
2137	  11/780, nominally a 1 MIPS machine).
2138
2139	  To run the benchmark, it needs to be enabled explicitly, either from
2140	  the kernel command line (when built-in), or from userspace (when
2141	  built-in or modular.
2142
2143	  Run once during kernel boot:
2144
2145	      test_dhry.run
2146
2147	  Set number of iterations from kernel command line:
2148
2149	      test_dhry.iterations=<n>
2150
2151	  Set number of iterations from userspace:
2152
2153	      echo <n> > /sys/module/test_dhry/parameters/iterations
2154
2155	  Trigger manual run from userspace:
2156
2157	      echo y > /sys/module/test_dhry/parameters/run
2158
2159	  If the number of iterations is <= 0, the test will devise a suitable
2160	  number of iterations (test runs for at least 2s) automatically.
2161	  This process takes ca. 4s.
2162
2163	  If unsure, say N.
2164
2165config LKDTM
2166	tristate "Linux Kernel Dump Test Tool Module"
2167	depends on DEBUG_FS
2168	help
2169	This module enables testing of the different dumping mechanisms by
2170	inducing system failures at predefined crash points.
2171	If you don't need it: say N
2172	Choose M here to compile this code as a module. The module will be
2173	called lkdtm.
2174
2175	Documentation on how to use the module can be found in
2176	Documentation/fault-injection/provoke-crashes.rst
2177
2178config CPUMASK_KUNIT_TEST
2179	tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS
2180	depends on KUNIT
2181	default KUNIT_ALL_TESTS
2182	help
2183	  Enable to turn on cpumask tests, running at boot or module load time.
2184
2185	  For more information on KUnit and unit tests in general, please refer
2186	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2187
2188	  If unsure, say N.
2189
2190config TEST_LIST_SORT
2191	tristate "Linked list sorting test" if !KUNIT_ALL_TESTS
2192	depends on KUNIT
2193	default KUNIT_ALL_TESTS
2194	help
2195	  Enable this to turn on 'list_sort()' function test. This test is
2196	  executed only once during system boot (so affects only boot time),
2197	  or at module load time.
2198
2199	  If unsure, say N.
2200
2201config TEST_MIN_HEAP
2202	tristate "Min heap test"
2203	depends on DEBUG_KERNEL || m
2204	help
2205	  Enable this to turn on min heap function tests. This test is
2206	  executed only once during system boot (so affects only boot time),
2207	  or at module load time.
2208
2209	  If unsure, say N.
2210
2211config TEST_SORT
2212	tristate "Array-based sort test" if !KUNIT_ALL_TESTS
2213	depends on KUNIT
2214	default KUNIT_ALL_TESTS
2215	help
2216	  This option enables the self-test function of 'sort()' at boot,
2217	  or at module load time.
2218
2219	  If unsure, say N.
2220
2221config TEST_DIV64
2222	tristate "64bit/32bit division and modulo test"
2223	depends on DEBUG_KERNEL || m
2224	help
2225	  Enable this to turn on 'do_div()' function test. This test is
2226	  executed only once during system boot (so affects only boot time),
2227	  or at module load time.
2228
2229	  If unsure, say N.
2230
2231config TEST_IOV_ITER
2232	tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS
2233	depends on KUNIT
2234	default KUNIT_ALL_TESTS
2235	help
2236	  Enable this to turn on testing of the operation of the I/O iterator
2237	  (iov_iter). This test is executed only once during system boot (so
2238	  affects only boot time), or at module load time.
2239
2240	  If unsure, say N.
2241
2242config KPROBES_SANITY_TEST
2243	tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS
2244	depends on DEBUG_KERNEL
2245	depends on KPROBES
2246	depends on KUNIT
2247	select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
2248	default KUNIT_ALL_TESTS
2249	help
2250	  This option provides for testing basic kprobes functionality on
2251	  boot. Samples of kprobe and kretprobe are inserted and
2252	  verified for functionality.
2253
2254	  Say N if you are unsure.
2255
2256config FPROBE_SANITY_TEST
2257	bool "Self test for fprobe"
2258	depends on DEBUG_KERNEL
2259	depends on FPROBE
2260	depends on KUNIT=y
2261	help
2262	  This option will enable testing the fprobe when the system boot.
2263	  A series of tests are made to verify that the fprobe is functioning
2264	  properly.
2265
2266	  Say N if you are unsure.
2267
2268config BACKTRACE_SELF_TEST
2269	tristate "Self test for the backtrace code"
2270	depends on DEBUG_KERNEL
2271	help
2272	  This option provides a kernel module that can be used to test
2273	  the kernel stack backtrace code. This option is not useful
2274	  for distributions or general kernels, but only for kernel
2275	  developers working on architecture code.
2276
2277	  Note that if you want to also test saved backtraces, you will
2278	  have to enable STACKTRACE as well.
2279
2280	  Say N if you are unsure.
2281
2282config TEST_REF_TRACKER
2283	tristate "Self test for reference tracker"
2284	depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
2285	select REF_TRACKER
2286	help
2287	  This option provides a kernel module performing tests
2288	  using reference tracker infrastructure.
2289
2290	  Say N if you are unsure.
2291
2292config RBTREE_TEST
2293	tristate "Red-Black tree test"
2294	depends on DEBUG_KERNEL
2295	help
2296	  A benchmark measuring the performance of the rbtree library.
2297	  Also includes rbtree invariant checks.
2298
2299config REED_SOLOMON_TEST
2300	tristate "Reed-Solomon library test"
2301	depends on DEBUG_KERNEL || m
2302	select REED_SOLOMON
2303	select REED_SOLOMON_ENC16
2304	select REED_SOLOMON_DEC16
2305	help
2306	  This option enables the self-test function of rslib at boot,
2307	  or at module load time.
2308
2309	  If unsure, say N.
2310
2311config INTERVAL_TREE_TEST
2312	tristate "Interval tree test"
2313	depends on DEBUG_KERNEL
2314	select INTERVAL_TREE
2315	help
2316	  A benchmark measuring the performance of the interval tree library
2317
2318config PERCPU_TEST
2319	tristate "Per cpu operations test"
2320	depends on m && DEBUG_KERNEL
2321	help
2322	  Enable this option to build test module which validates per-cpu
2323	  operations.
2324
2325	  If unsure, say N.
2326
2327config ATOMIC64_SELFTEST
2328	tristate "Perform an atomic64_t self-test"
2329	help
2330	  Enable this option to test the atomic64_t functions at boot or
2331	  at module load time.
2332
2333	  If unsure, say N.
2334
2335config ASYNC_RAID6_TEST
2336	tristate "Self test for hardware accelerated raid6 recovery"
2337	depends on ASYNC_RAID6_RECOV
2338	select ASYNC_MEMCPY
2339	help
2340	  This is a one-shot self test that permutes through the
2341	  recovery of all the possible two disk failure scenarios for a
2342	  N-disk array.  Recovery is performed with the asynchronous
2343	  raid6 recovery routines, and will optionally use an offload
2344	  engine if one is available.
2345
2346	  If unsure, say N.
2347
2348config TEST_HEXDUMP
2349	tristate "Test functions located in the hexdump module at runtime"
2350
2351config STRING_SELFTEST
2352	tristate "Test string functions at runtime"
2353
2354config TEST_STRING_HELPERS
2355	tristate "Test functions located in the string_helpers module at runtime"
2356
2357config TEST_KSTRTOX
2358	tristate "Test kstrto*() family of functions at runtime"
2359
2360config TEST_PRINTF
2361	tristate "Test printf() family of functions at runtime"
2362
2363config TEST_SCANF
2364	tristate "Test scanf() family of functions at runtime"
2365
2366config TEST_BITMAP
2367	tristate "Test bitmap_*() family of functions at runtime"
2368	help
2369	  Enable this option to test the bitmap functions at boot.
2370
2371	  If unsure, say N.
2372
2373config TEST_UUID
2374	tristate "Test functions located in the uuid module at runtime"
2375
2376config TEST_XARRAY
2377	tristate "Test the XArray code at runtime"
2378
2379config TEST_MAPLE_TREE
2380	tristate "Test the Maple Tree code at runtime or module load"
2381	help
2382	  Enable this option to test the maple tree code functions at boot, or
2383	  when the module is loaded. Enable "Debug Maple Trees" will enable
2384	  more verbose output on failures.
2385
2386	  If unsure, say N.
2387
2388config TEST_RHASHTABLE
2389	tristate "Perform selftest on resizable hash table"
2390	help
2391	  Enable this option to test the rhashtable functions at boot.
2392
2393	  If unsure, say N.
2394
2395config TEST_IDA
2396	tristate "Perform selftest on IDA functions"
2397
2398config TEST_PARMAN
2399	tristate "Perform selftest on priority array manager"
2400	depends on PARMAN
2401	help
2402	  Enable this option to test priority array manager on boot
2403	  (or module load).
2404
2405	  If unsure, say N.
2406
2407config TEST_IRQ_TIMINGS
2408	bool "IRQ timings selftest"
2409	depends on IRQ_TIMINGS
2410	help
2411	  Enable this option to test the irq timings code on boot.
2412
2413	  If unsure, say N.
2414
2415config TEST_LKM
2416	tristate "Test module loading with 'hello world' module"
2417	depends on m
2418	help
2419	  This builds the "test_module" module that emits "Hello, world"
2420	  on printk when loaded. It is designed to be used for basic
2421	  evaluation of the module loading subsystem (for example when
2422	  validating module verification). It lacks any extra dependencies,
2423	  and will not normally be loaded by the system unless explicitly
2424	  requested by name.
2425
2426	  If unsure, say N.
2427
2428config TEST_BITOPS
2429	tristate "Test module for compilation of bitops operations"
2430	depends on m
2431	help
2432	  This builds the "test_bitops" module that is much like the
2433	  TEST_LKM module except that it does a basic exercise of the
2434	  set/clear_bit macros and get_count_order/long to make sure there are
2435	  no compiler warnings from C=1 sparse checker or -Wextra
2436	  compilations. It has no dependencies and doesn't run or load unless
2437	  explicitly requested by name.  for example: modprobe test_bitops.
2438
2439	  If unsure, say N.
2440
2441config TEST_VMALLOC
2442	tristate "Test module for stress/performance analysis of vmalloc allocator"
2443	default n
2444       depends on MMU
2445	depends on m
2446	help
2447	  This builds the "test_vmalloc" module that should be used for
2448	  stress and performance analysis. So, any new change for vmalloc
2449	  subsystem can be evaluated from performance and stability point
2450	  of view.
2451
2452	  If unsure, say N.
2453
2454config TEST_USER_COPY
2455	tristate "Test user/kernel boundary protections"
2456	depends on m
2457	help
2458	  This builds the "test_user_copy" module that runs sanity checks
2459	  on the copy_to/from_user infrastructure, making sure basic
2460	  user/kernel boundary testing is working. If it fails to load,
2461	  a regression has been detected in the user/kernel memory boundary
2462	  protections.
2463
2464	  If unsure, say N.
2465
2466config TEST_BPF
2467	tristate "Test BPF filter functionality"
2468	depends on m && NET
2469	help
2470	  This builds the "test_bpf" module that runs various test vectors
2471	  against the BPF interpreter or BPF JIT compiler depending on the
2472	  current setting. This is in particular useful for BPF JIT compiler
2473	  development, but also to run regression tests against changes in
2474	  the interpreter code. It also enables test stubs for eBPF maps and
2475	  verifier used by user space verifier testsuite.
2476
2477	  If unsure, say N.
2478
2479config TEST_BLACKHOLE_DEV
2480	tristate "Test blackhole netdev functionality"
2481	depends on m && NET
2482	help
2483	  This builds the "test_blackhole_dev" module that validates the
2484	  data path through this blackhole netdev.
2485
2486	  If unsure, say N.
2487
2488config FIND_BIT_BENCHMARK
2489	tristate "Test find_bit functions"
2490	help
2491	  This builds the "test_find_bit" module that measure find_*_bit()
2492	  functions performance.
2493
2494	  If unsure, say N.
2495
2496config TEST_FIRMWARE
2497	tristate "Test firmware loading via userspace interface"
2498	depends on FW_LOADER
2499	help
2500	  This builds the "test_firmware" module that creates a userspace
2501	  interface for testing firmware loading. This can be used to
2502	  control the triggering of firmware loading without needing an
2503	  actual firmware-using device. The contents can be rechecked by
2504	  userspace.
2505
2506	  If unsure, say N.
2507
2508config TEST_SYSCTL
2509	tristate "sysctl test driver"
2510	depends on PROC_SYSCTL
2511	help
2512	  This builds the "test_sysctl" module. This driver enables to test the
2513	  proc sysctl interfaces available to drivers safely without affecting
2514	  production knobs which might alter system functionality.
2515
2516	  If unsure, say N.
2517
2518config BITFIELD_KUNIT
2519	tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS
2520	depends on KUNIT
2521	default KUNIT_ALL_TESTS
2522	help
2523	  Enable this option to test the bitfield functions at boot.
2524
2525	  KUnit tests run during boot and output the results to the debug log
2526	  in TAP format (http://testanything.org/). Only useful for kernel devs
2527	  running the KUnit test harness, and not intended for inclusion into a
2528	  production build.
2529
2530	  For more information on KUnit and unit tests in general please refer
2531	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2532
2533	  If unsure, say N.
2534
2535config CHECKSUM_KUNIT
2536	tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS
2537	depends on KUNIT
2538	default KUNIT_ALL_TESTS
2539	help
2540	  Enable this option to test the checksum functions at boot.
2541
2542	  KUnit tests run during boot and output the results to the debug log
2543	  in TAP format (http://testanything.org/). Only useful for kernel devs
2544	  running the KUnit test harness, and not intended for inclusion into a
2545	  production build.
2546
2547	  For more information on KUnit and unit tests in general please refer
2548	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2549
2550	  If unsure, say N.
2551
2552config HASH_KUNIT_TEST
2553	tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS
2554	depends on KUNIT
2555	default KUNIT_ALL_TESTS
2556	help
2557	  Enable this option to test the kernel's string (<linux/stringhash.h>), and
2558	  integer (<linux/hash.h>) hash functions on boot.
2559
2560	  KUnit tests run during boot and output the results to the debug log
2561	  in TAP format (https://testanything.org/). Only useful for kernel devs
2562	  running the KUnit test harness, and not intended for inclusion into a
2563	  production build.
2564
2565	  For more information on KUnit and unit tests in general please refer
2566	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2567
2568	  This is intended to help people writing architecture-specific
2569	  optimized versions. If unsure, say N.
2570
2571config RESOURCE_KUNIT_TEST
2572	tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS
2573	depends on KUNIT
2574	default KUNIT_ALL_TESTS
2575	help
2576	  This builds the resource API unit test.
2577	  Tests the logic of API provided by resource.c and ioport.h.
2578	  For more information on KUnit and unit tests in general please refer
2579	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2580
2581	  If unsure, say N.
2582
2583config SYSCTL_KUNIT_TEST
2584	tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS
2585	depends on KUNIT
2586	default KUNIT_ALL_TESTS
2587	help
2588	  This builds the proc sysctl unit test, which runs on boot.
2589	  Tests the API contract and implementation correctness of sysctl.
2590	  For more information on KUnit and unit tests in general please refer
2591	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2592
2593	  If unsure, say N.
2594
2595config LIST_KUNIT_TEST
2596	tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS
2597	depends on KUNIT
2598	default KUNIT_ALL_TESTS
2599	help
2600	  This builds the linked list KUnit test suite.
2601	  It tests that the API and basic functionality of the list_head type
2602	  and associated macros.
2603
2604	  KUnit tests run during boot and output the results to the debug log
2605	  in TAP format (https://testanything.org/). Only useful for kernel devs
2606	  running the KUnit test harness, and not intended for inclusion into a
2607	  production build.
2608
2609	  For more information on KUnit and unit tests in general please refer
2610	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2611
2612	  If unsure, say N.
2613
2614config HASHTABLE_KUNIT_TEST
2615	tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS
2616	depends on KUNIT
2617	default KUNIT_ALL_TESTS
2618	help
2619	  This builds the hashtable KUnit test suite.
2620	  It tests the basic functionality of the API defined in
2621	  include/linux/hashtable.h. For more information on KUnit and
2622	  unit tests in general please refer to the KUnit documentation
2623	  in Documentation/dev-tools/kunit/.
2624
2625	  If unsure, say N.
2626
2627config LINEAR_RANGES_TEST
2628	tristate "KUnit test for linear_ranges"
2629	depends on KUNIT
2630	select LINEAR_RANGES
2631	help
2632	  This builds the linear_ranges unit test, which runs on boot.
2633	  Tests the linear_ranges logic correctness.
2634	  For more information on KUnit and unit tests in general please refer
2635	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2636
2637	  If unsure, say N.
2638
2639config CMDLINE_KUNIT_TEST
2640	tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS
2641	depends on KUNIT
2642	default KUNIT_ALL_TESTS
2643	help
2644	  This builds the cmdline API unit test.
2645	  Tests the logic of API provided by cmdline.c.
2646	  For more information on KUnit and unit tests in general please refer
2647	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2648
2649	  If unsure, say N.
2650
2651config BITS_TEST
2652	tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS
2653	depends on KUNIT
2654	default KUNIT_ALL_TESTS
2655	help
2656	  This builds the bits unit test.
2657	  Tests the logic of macros defined in bits.h.
2658	  For more information on KUnit and unit tests in general please refer
2659	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2660
2661	  If unsure, say N.
2662
2663config SLUB_KUNIT_TEST
2664	tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS
2665	depends on SLUB_DEBUG && KUNIT
2666	default KUNIT_ALL_TESTS
2667	help
2668	  This builds SLUB allocator unit test.
2669	  Tests SLUB cache debugging functionality.
2670	  For more information on KUnit and unit tests in general please refer
2671	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2672
2673	  If unsure, say N.
2674
2675config RATIONAL_KUNIT_TEST
2676	tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS
2677	depends on KUNIT && RATIONAL
2678	default KUNIT_ALL_TESTS
2679	help
2680	  This builds the rational math unit test.
2681	  For more information on KUnit and unit tests in general please refer
2682	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2683
2684	  If unsure, say N.
2685
2686config MEMCPY_KUNIT_TEST
2687	tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS
2688	depends on KUNIT
2689	default KUNIT_ALL_TESTS
2690	help
2691	  Builds unit tests for memcpy(), memmove(), and memset() functions.
2692	  For more information on KUnit and unit tests in general please refer
2693	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2694
2695	  If unsure, say N.
2696
2697config MEMCPY_SLOW_KUNIT_TEST
2698	bool "Include exhaustive memcpy tests"
2699	depends on MEMCPY_KUNIT_TEST
2700	default y
2701	help
2702	  Some memcpy tests are quite exhaustive in checking for overlaps
2703	  and bit ranges. These can be very slow, so they are split out
2704	  as a separate config, in case they need to be disabled.
2705
2706	  Note this config option will be replaced by the use of KUnit test
2707	  attributes.
2708
2709config IS_SIGNED_TYPE_KUNIT_TEST
2710	tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS
2711	depends on KUNIT
2712	default KUNIT_ALL_TESTS
2713	help
2714	  Builds unit tests for the is_signed_type() macro.
2715
2716	  For more information on KUnit and unit tests in general please refer
2717	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2718
2719	  If unsure, say N.
2720
2721config OVERFLOW_KUNIT_TEST
2722	tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS
2723	depends on KUNIT
2724	default KUNIT_ALL_TESTS
2725	help
2726	  Builds unit tests for the check_*_overflow(), size_*(), allocation, and
2727	  related functions.
2728
2729	  For more information on KUnit and unit tests in general please refer
2730	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2731
2732	  If unsure, say N.
2733
2734config STACKINIT_KUNIT_TEST
2735	tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS
2736	depends on KUNIT
2737	default KUNIT_ALL_TESTS
2738	help
2739	  Test if the kernel is zero-initializing stack variables and
2740	  padding. Coverage is controlled by compiler flags,
2741	  CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO,
2742	  CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2743	  or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2744
2745config FORTIFY_KUNIT_TEST
2746	tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS
2747	depends on KUNIT && FORTIFY_SOURCE
2748	default KUNIT_ALL_TESTS
2749	help
2750	  Builds unit tests for checking internals of FORTIFY_SOURCE as used
2751	  by the str*() and mem*() family of functions. For testing runtime
2752	  traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests.
2753
2754config HW_BREAKPOINT_KUNIT_TEST
2755	bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS
2756	depends on HAVE_HW_BREAKPOINT
2757	depends on KUNIT=y
2758	default KUNIT_ALL_TESTS
2759	help
2760	  Tests for hw_breakpoint constraints accounting.
2761
2762	  If unsure, say N.
2763
2764config STRCAT_KUNIT_TEST
2765	tristate "Test strcat() family of functions at runtime" if !KUNIT_ALL_TESTS
2766	depends on KUNIT
2767	default KUNIT_ALL_TESTS
2768
2769config STRSCPY_KUNIT_TEST
2770	tristate "Test strscpy*() family of functions at runtime" if !KUNIT_ALL_TESTS
2771	depends on KUNIT
2772	default KUNIT_ALL_TESTS
2773
2774config SIPHASH_KUNIT_TEST
2775	tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS
2776	depends on KUNIT
2777	default KUNIT_ALL_TESTS
2778	help
2779	  Enable this option to test the kernel's siphash (<linux/siphash.h>) hash
2780	  functions on boot (or module load).
2781
2782	  This is intended to help people writing architecture-specific
2783	  optimized versions.  If unsure, say N.
2784
2785config TEST_UDELAY
2786	tristate "udelay test driver"
2787	help
2788	  This builds the "udelay_test" module that helps to make sure
2789	  that udelay() is working properly.
2790
2791	  If unsure, say N.
2792
2793config TEST_STATIC_KEYS
2794	tristate "Test static keys"
2795	depends on m
2796	help
2797	  Test the static key interfaces.
2798
2799	  If unsure, say N.
2800
2801config TEST_DYNAMIC_DEBUG
2802	tristate "Test DYNAMIC_DEBUG"
2803	depends on DYNAMIC_DEBUG
2804	help
2805	  This module registers a tracer callback to count enabled
2806	  pr_debugs in a 'do_debugging' function, then alters their
2807	  enablements, calls the function, and compares counts.
2808
2809	  If unsure, say N.
2810
2811config TEST_KMOD
2812	tristate "kmod stress tester"
2813	depends on m
2814	depends on NETDEVICES && NET_CORE && INET # for TUN
2815	depends on BLOCK
2816	depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS
2817	select TEST_LKM
2818	select XFS_FS
2819	select TUN
2820	select BTRFS_FS
2821	help
2822	  Test the kernel's module loading mechanism: kmod. kmod implements
2823	  support to load modules using the Linux kernel's usermode helper.
2824	  This test provides a series of tests against kmod.
2825
2826	  Although technically you can either build test_kmod as a module or
2827	  into the kernel we disallow building it into the kernel since
2828	  it stress tests request_module() and this will very likely cause
2829	  some issues by taking over precious threads available from other
2830	  module load requests, ultimately this could be fatal.
2831
2832	  To run tests run:
2833
2834	  tools/testing/selftests/kmod/kmod.sh --help
2835
2836	  If unsure, say N.
2837
2838config TEST_DEBUG_VIRTUAL
2839	tristate "Test CONFIG_DEBUG_VIRTUAL feature"
2840	depends on DEBUG_VIRTUAL
2841	help
2842	  Test the kernel's ability to detect incorrect calls to
2843	  virt_to_phys() done against the non-linear part of the
2844	  kernel's virtual address map.
2845
2846	  If unsure, say N.
2847
2848config TEST_MEMCAT_P
2849	tristate "Test memcat_p() helper function"
2850	help
2851	  Test the memcat_p() helper for correctly merging two
2852	  pointer arrays together.
2853
2854	  If unsure, say N.
2855
2856config TEST_LIVEPATCH
2857	tristate "Test livepatching"
2858	default n
2859	depends on DYNAMIC_DEBUG
2860	depends on LIVEPATCH
2861	depends on m
2862	help
2863	  Test kernel livepatching features for correctness.  The tests will
2864	  load test modules that will be livepatched in various scenarios.
2865
2866	  To run all the livepatching tests:
2867
2868	  make -C tools/testing/selftests TARGETS=livepatch run_tests
2869
2870	  Alternatively, individual tests may be invoked:
2871
2872	  tools/testing/selftests/livepatch/test-callbacks.sh
2873	  tools/testing/selftests/livepatch/test-livepatch.sh
2874	  tools/testing/selftests/livepatch/test-shadow-vars.sh
2875
2876	  If unsure, say N.
2877
2878config TEST_OBJAGG
2879	tristate "Perform selftest on object aggreration manager"
2880	default n
2881	depends on OBJAGG
2882	help
2883	  Enable this option to test object aggregation manager on boot
2884	  (or module load).
2885
2886config TEST_MEMINIT
2887	tristate "Test heap/page initialization"
2888	help
2889	  Test if the kernel is zero-initializing heap and page allocations.
2890	  This can be useful to test init_on_alloc and init_on_free features.
2891
2892	  If unsure, say N.
2893
2894config TEST_HMM
2895	tristate "Test HMM (Heterogeneous Memory Management)"
2896	depends on TRANSPARENT_HUGEPAGE
2897	depends on DEVICE_PRIVATE
2898	select HMM_MIRROR
2899	select MMU_NOTIFIER
2900	help
2901	  This is a pseudo device driver solely for testing HMM.
2902	  Say M here if you want to build the HMM test module.
2903	  Doing so will allow you to run tools/testing/selftest/vm/hmm-tests.
2904
2905	  If unsure, say N.
2906
2907config TEST_FREE_PAGES
2908	tristate "Test freeing pages"
2909	help
2910	  Test that a memory leak does not occur due to a race between
2911	  freeing a block of pages and a speculative page reference.
2912	  Loading this module is safe if your kernel has the bug fixed.
2913	  If the bug is not fixed, it will leak gigabytes of memory and
2914	  probably OOM your system.
2915
2916config TEST_FPU
2917	tristate "Test floating point operations in kernel space"
2918	depends on X86 && !KCOV_INSTRUMENT_ALL
2919	help
2920	  Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu
2921	  which will trigger a sequence of floating point operations. This is used
2922	  for self-testing floating point control register setting in
2923	  kernel_fpu_begin().
2924
2925	  If unsure, say N.
2926
2927config TEST_CLOCKSOURCE_WATCHDOG
2928	tristate "Test clocksource watchdog in kernel space"
2929	depends on CLOCKSOURCE_WATCHDOG
2930	help
2931	  Enable this option to create a kernel module that will trigger
2932	  a test of the clocksource watchdog.  This module may be loaded
2933	  via modprobe or insmod in which case it will run upon being
2934	  loaded, or it may be built in, in which case it will run
2935	  shortly after boot.
2936
2937	  If unsure, say N.
2938
2939config TEST_OBJPOOL
2940	tristate "Test module for correctness and stress of objpool"
2941	default n
2942	depends on m && DEBUG_KERNEL
2943	help
2944	  This builds the "test_objpool" module that should be used for
2945	  correctness verification and concurrent testings of objects
2946	  allocation and reclamation.
2947
2948	  If unsure, say N.
2949
2950endif # RUNTIME_TESTING_MENU
2951
2952config ARCH_USE_MEMTEST
2953	bool
2954	help
2955	  An architecture should select this when it uses early_memtest()
2956	  during boot process.
2957
2958config MEMTEST
2959	bool "Memtest"
2960	depends on ARCH_USE_MEMTEST
2961	help
2962	  This option adds a kernel parameter 'memtest', which allows memtest
2963	  to be set and executed.
2964	        memtest=0, mean disabled; -- default
2965	        memtest=1, mean do 1 test pattern;
2966	        ...
2967	        memtest=17, mean do 17 test patterns.
2968	  If you are unsure how to answer this question, answer N.
2969
2970
2971
2972config HYPERV_TESTING
2973	bool "Microsoft Hyper-V driver testing"
2974	default n
2975	depends on HYPERV && DEBUG_FS
2976	help
2977	  Select this option to enable Hyper-V vmbus testing.
2978
2979endmenu # "Kernel Testing and Coverage"
2980
2981menu "Rust hacking"
2982
2983config RUST_DEBUG_ASSERTIONS
2984	bool "Debug assertions"
2985	depends on RUST
2986	help
2987	  Enables rustc's `-Cdebug-assertions` codegen option.
2988
2989	  This flag lets you turn `cfg(debug_assertions)` conditional
2990	  compilation on or off. This can be used to enable extra debugging
2991	  code in development but not in production. For example, it controls
2992	  the behavior of the standard library's `debug_assert!` macro.
2993
2994	  Note that this will apply to all Rust code, including `core`.
2995
2996	  If unsure, say N.
2997
2998config RUST_OVERFLOW_CHECKS
2999	bool "Overflow checks"
3000	default y
3001	depends on RUST
3002	help
3003	  Enables rustc's `-Coverflow-checks` codegen option.
3004
3005	  This flag allows you to control the behavior of runtime integer
3006	  overflow. When overflow-checks are enabled, a Rust panic will occur
3007	  on overflow.
3008
3009	  Note that this will apply to all Rust code, including `core`.
3010
3011	  If unsure, say Y.
3012
3013config RUST_BUILD_ASSERT_ALLOW
3014	bool "Allow unoptimized build-time assertions"
3015	depends on RUST
3016	help
3017	  Controls how are `build_error!` and `build_assert!` handled during build.
3018
3019	  If calls to them exist in the binary, it may indicate a violated invariant
3020	  or that the optimizer failed to verify the invariant during compilation.
3021
3022	  This should not happen, thus by default the build is aborted. However,
3023	  as an escape hatch, you can choose Y here to ignore them during build
3024	  and let the check be carried at runtime (with `panic!` being called if
3025	  the check fails).
3026
3027	  If unsure, say N.
3028
3029config RUST_KERNEL_DOCTESTS
3030	bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS
3031	depends on RUST && KUNIT=y
3032	default KUNIT_ALL_TESTS
3033	help
3034	  This builds the documentation tests of the `kernel` crate
3035	  as KUnit tests.
3036
3037	  For more information on KUnit and unit tests in general,
3038	  please refer to the KUnit documentation in Documentation/dev-tools/kunit/.
3039
3040	  If unsure, say N.
3041
3042endmenu # "Rust"
3043
3044endmenu # Kernel hacking
3045