xref: /linux-6.15/lib/Kconfig.debug (revision 90ca2251)
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
1744config DEBUG_CREDENTIALS
1745	bool "Debug credential management"
1746	depends on DEBUG_KERNEL
1747	help
1748	  Enable this to turn on some debug checking for credential
1749	  management.  The additional code keeps track of the number of
1750	  pointers from task_structs to any given cred struct, and checks to
1751	  see that this number never exceeds the usage count of the cred
1752	  struct.
1753
1754	  Furthermore, if SELinux is enabled, this also checks that the
1755	  security pointer in the cred struct is never seen to be invalid.
1756
1757	  If unsure, say N.
1758
1759source "kernel/rcu/Kconfig.debug"
1760
1761config DEBUG_WQ_FORCE_RR_CPU
1762	bool "Force round-robin CPU selection for unbound work items"
1763	depends on DEBUG_KERNEL
1764	default n
1765	help
1766	  Workqueue used to implicitly guarantee that work items queued
1767	  without explicit CPU specified are put on the local CPU.  This
1768	  guarantee is no longer true and while local CPU is still
1769	  preferred work items may be put on foreign CPUs.  Kernel
1770	  parameter "workqueue.debug_force_rr_cpu" is added to force
1771	  round-robin CPU selection to flush out usages which depend on the
1772	  now broken guarantee.  This config option enables the debug
1773	  feature by default.  When enabled, memory and cache locality will
1774	  be impacted.
1775
1776config CPU_HOTPLUG_STATE_CONTROL
1777	bool "Enable CPU hotplug state control"
1778	depends on DEBUG_KERNEL
1779	depends on HOTPLUG_CPU
1780	default n
1781	help
1782	  Allows to write steps between "offline" and "online" to the CPUs
1783	  sysfs target file so states can be stepped granular. This is a debug
1784	  option for now as the hotplug machinery cannot be stopped and
1785	  restarted at arbitrary points yet.
1786
1787	  Say N if your are unsure.
1788
1789config LATENCYTOP
1790	bool "Latency measuring infrastructure"
1791	depends on DEBUG_KERNEL
1792	depends on STACKTRACE_SUPPORT
1793	depends on PROC_FS
1794	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
1795	select KALLSYMS
1796	select KALLSYMS_ALL
1797	select STACKTRACE
1798	select SCHEDSTATS
1799	help
1800	  Enable this option if you want to use the LatencyTOP tool
1801	  to find out which userspace is blocking on what kernel operations.
1802
1803config DEBUG_CGROUP_REF
1804	bool "Disable inlining of cgroup css reference count functions"
1805	depends on DEBUG_KERNEL
1806	depends on CGROUPS
1807	depends on KPROBES
1808	default n
1809	help
1810	  Force cgroup css reference count functions to not be inlined so
1811	  that they can be kprobed for debugging.
1812
1813source "kernel/trace/Kconfig"
1814
1815config PROVIDE_OHCI1394_DMA_INIT
1816	bool "Remote debugging over FireWire early on boot"
1817	depends on PCI && X86
1818	help
1819	  If you want to debug problems which hang or crash the kernel early
1820	  on boot and the crashing machine has a FireWire port, you can use
1821	  this feature to remotely access the memory of the crashed machine
1822	  over FireWire. This employs remote DMA as part of the OHCI1394
1823	  specification which is now the standard for FireWire controllers.
1824
1825	  With remote DMA, you can monitor the printk buffer remotely using
1826	  firescope and access all memory below 4GB using fireproxy from gdb.
1827	  Even controlling a kernel debugger is possible using remote DMA.
1828
1829	  Usage:
1830
1831	  If ohci1394_dma=early is used as boot parameter, it will initialize
1832	  all OHCI1394 controllers which are found in the PCI config space.
1833
1834	  As all changes to the FireWire bus such as enabling and disabling
1835	  devices cause a bus reset and thereby disable remote DMA for all
1836	  devices, be sure to have the cable plugged and FireWire enabled on
1837	  the debugging host before booting the debug target for debugging.
1838
1839	  This code (~1k) is freed after boot. By then, the firewire stack
1840	  in charge of the OHCI-1394 controllers should be used instead.
1841
1842	  See Documentation/core-api/debugging-via-ohci1394.rst for more information.
1843
1844source "samples/Kconfig"
1845
1846config ARCH_HAS_DEVMEM_IS_ALLOWED
1847	bool
1848
1849config STRICT_DEVMEM
1850	bool "Filter access to /dev/mem"
1851	depends on MMU && DEVMEM
1852	depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED
1853	default y if PPC || X86 || ARM64
1854	help
1855	  If this option is disabled, you allow userspace (root) access to all
1856	  of memory, including kernel and userspace memory. Accidental
1857	  access to this is obviously disastrous, but specific access can
1858	  be used by people debugging the kernel. Note that with PAT support
1859	  enabled, even in this case there are restrictions on /dev/mem
1860	  use due to the cache aliasing requirements.
1861
1862	  If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
1863	  file only allows userspace access to PCI space and the BIOS code and
1864	  data regions.  This is sufficient for dosemu and X and all common
1865	  users of /dev/mem.
1866
1867	  If in doubt, say Y.
1868
1869config IO_STRICT_DEVMEM
1870	bool "Filter I/O access to /dev/mem"
1871	depends on STRICT_DEVMEM
1872	help
1873	  If this option is disabled, you allow userspace (root) access to all
1874	  io-memory regardless of whether a driver is actively using that
1875	  range.  Accidental access to this is obviously disastrous, but
1876	  specific access can be used by people debugging kernel drivers.
1877
1878	  If this option is switched on, the /dev/mem file only allows
1879	  userspace access to *idle* io-memory ranges (see /proc/iomem) This
1880	  may break traditional users of /dev/mem (dosemu, legacy X, etc...)
1881	  if the driver using a given range cannot be disabled.
1882
1883	  If in doubt, say Y.
1884
1885menu "$(SRCARCH) Debugging"
1886
1887source "arch/$(SRCARCH)/Kconfig.debug"
1888
1889endmenu
1890
1891menu "Kernel Testing and Coverage"
1892
1893source "lib/kunit/Kconfig"
1894
1895config NOTIFIER_ERROR_INJECTION
1896	tristate "Notifier error injection"
1897	depends on DEBUG_KERNEL
1898	select DEBUG_FS
1899	help
1900	  This option provides the ability to inject artificial errors to
1901	  specified notifier chain callbacks. It is useful to test the error
1902	  handling of notifier call chain failures.
1903
1904	  Say N if unsure.
1905
1906config PM_NOTIFIER_ERROR_INJECT
1907	tristate "PM notifier error injection module"
1908	depends on PM && NOTIFIER_ERROR_INJECTION
1909	default m if PM_DEBUG
1910	help
1911	  This option provides the ability to inject artificial errors to
1912	  PM notifier chain callbacks.  It is controlled through debugfs
1913	  interface /sys/kernel/debug/notifier-error-inject/pm
1914
1915	  If the notifier call chain should be failed with some events
1916	  notified, write the error code to "actions/<notifier event>/error".
1917
1918	  Example: Inject PM suspend error (-12 = -ENOMEM)
1919
1920	  # cd /sys/kernel/debug/notifier-error-inject/pm/
1921	  # echo -12 > actions/PM_SUSPEND_PREPARE/error
1922	  # echo mem > /sys/power/state
1923	  bash: echo: write error: Cannot allocate memory
1924
1925	  To compile this code as a module, choose M here: the module will
1926	  be called pm-notifier-error-inject.
1927
1928	  If unsure, say N.
1929
1930config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1931	tristate "OF reconfig notifier error injection module"
1932	depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1933	help
1934	  This option provides the ability to inject artificial errors to
1935	  OF reconfig notifier chain callbacks.  It is controlled
1936	  through debugfs interface under
1937	  /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1938
1939	  If the notifier call chain should be failed with some events
1940	  notified, write the error code to "actions/<notifier event>/error".
1941
1942	  To compile this code as a module, choose M here: the module will
1943	  be called of-reconfig-notifier-error-inject.
1944
1945	  If unsure, say N.
1946
1947config NETDEV_NOTIFIER_ERROR_INJECT
1948	tristate "Netdev notifier error injection module"
1949	depends on NET && NOTIFIER_ERROR_INJECTION
1950	help
1951	  This option provides the ability to inject artificial errors to
1952	  netdevice notifier chain callbacks.  It is controlled through debugfs
1953	  interface /sys/kernel/debug/notifier-error-inject/netdev
1954
1955	  If the notifier call chain should be failed with some events
1956	  notified, write the error code to "actions/<notifier event>/error".
1957
1958	  Example: Inject netdevice mtu change error (-22 = -EINVAL)
1959
1960	  # cd /sys/kernel/debug/notifier-error-inject/netdev
1961	  # echo -22 > actions/NETDEV_CHANGEMTU/error
1962	  # ip link set eth0 mtu 1024
1963	  RTNETLINK answers: Invalid argument
1964
1965	  To compile this code as a module, choose M here: the module will
1966	  be called netdev-notifier-error-inject.
1967
1968	  If unsure, say N.
1969
1970config FUNCTION_ERROR_INJECTION
1971	bool "Fault-injections of functions"
1972	depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
1973	help
1974	  Add fault injections into various functions that are annotated with
1975	  ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return
1976	  value of these functions. This is useful to test error paths of code.
1977
1978	  If unsure, say N
1979
1980config FAULT_INJECTION
1981	bool "Fault-injection framework"
1982	depends on DEBUG_KERNEL
1983	help
1984	  Provide fault-injection framework.
1985	  For more details, see Documentation/fault-injection/.
1986
1987config FAILSLAB
1988	bool "Fault-injection capability for kmalloc"
1989	depends on FAULT_INJECTION
1990	depends on SLAB || SLUB
1991	help
1992	  Provide fault-injection capability for kmalloc.
1993
1994config FAIL_PAGE_ALLOC
1995	bool "Fault-injection capability for alloc_pages()"
1996	depends on FAULT_INJECTION
1997	help
1998	  Provide fault-injection capability for alloc_pages().
1999
2000config FAULT_INJECTION_USERCOPY
2001	bool "Fault injection capability for usercopy functions"
2002	depends on FAULT_INJECTION
2003	help
2004	  Provides fault-injection capability to inject failures
2005	  in usercopy functions (copy_from_user(), get_user(), ...).
2006
2007config FAIL_MAKE_REQUEST
2008	bool "Fault-injection capability for disk IO"
2009	depends on FAULT_INJECTION && BLOCK
2010	help
2011	  Provide fault-injection capability for disk IO.
2012
2013config FAIL_IO_TIMEOUT
2014	bool "Fault-injection capability for faking disk interrupts"
2015	depends on FAULT_INJECTION && BLOCK
2016	help
2017	  Provide fault-injection capability on end IO handling. This
2018	  will make the block layer "forget" an interrupt as configured,
2019	  thus exercising the error handling.
2020
2021	  Only works with drivers that use the generic timeout handling,
2022	  for others it won't do anything.
2023
2024config FAIL_FUTEX
2025	bool "Fault-injection capability for futexes"
2026	select DEBUG_FS
2027	depends on FAULT_INJECTION && FUTEX
2028	help
2029	  Provide fault-injection capability for futexes.
2030
2031config FAULT_INJECTION_DEBUG_FS
2032	bool "Debugfs entries for fault-injection capabilities"
2033	depends on FAULT_INJECTION && SYSFS && DEBUG_FS
2034	help
2035	  Enable configuration of fault-injection capabilities via debugfs.
2036
2037config FAIL_FUNCTION
2038	bool "Fault-injection capability for functions"
2039	depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
2040	help
2041	  Provide function-based fault-injection capability.
2042	  This will allow you to override a specific function with a return
2043	  with given return value. As a result, function caller will see
2044	  an error value and have to handle it. This is useful to test the
2045	  error handling in various subsystems.
2046
2047config FAIL_MMC_REQUEST
2048	bool "Fault-injection capability for MMC IO"
2049	depends on FAULT_INJECTION_DEBUG_FS && MMC
2050	help
2051	  Provide fault-injection capability for MMC IO.
2052	  This will make the mmc core return data errors. This is
2053	  useful to test the error handling in the mmc block device
2054	  and to test how the mmc host driver handles retries from
2055	  the block device.
2056
2057config FAIL_SUNRPC
2058	bool "Fault-injection capability for SunRPC"
2059	depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG
2060	help
2061	  Provide fault-injection capability for SunRPC and
2062	  its consumers.
2063
2064config FAULT_INJECTION_CONFIGFS
2065	bool "Configfs interface for fault-injection capabilities"
2066	depends on FAULT_INJECTION
2067	select CONFIGFS_FS
2068	help
2069	  This option allows configfs-based drivers to dynamically configure
2070	  fault-injection via configfs.  Each parameter for driver-specific
2071	  fault-injection can be made visible as a configfs attribute in a
2072	  configfs group.
2073
2074
2075config FAULT_INJECTION_STACKTRACE_FILTER
2076	bool "stacktrace filter for fault-injection capabilities"
2077	depends on FAULT_INJECTION
2078	depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT
2079	select STACKTRACE
2080	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
2081	help
2082	  Provide stacktrace filter for fault-injection capabilities
2083
2084config ARCH_HAS_KCOV
2085	bool
2086	help
2087	  An architecture should select this when it can successfully
2088	  build and run with CONFIG_KCOV. This typically requires
2089	  disabling instrumentation for some early boot code.
2090
2091config CC_HAS_SANCOV_TRACE_PC
2092	def_bool $(cc-option,-fsanitize-coverage=trace-pc)
2093
2094
2095config KCOV
2096	bool "Code coverage for fuzzing"
2097	depends on ARCH_HAS_KCOV
2098	depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
2099	depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \
2100		   GCC_VERSION >= 120000 || CLANG_VERSION >= 130000
2101	select DEBUG_FS
2102	select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
2103	select OBJTOOL if HAVE_NOINSTR_HACK
2104	help
2105	  KCOV exposes kernel code coverage information in a form suitable
2106	  for coverage-guided fuzzing (randomized testing).
2107
2108	  For more details, see Documentation/dev-tools/kcov.rst.
2109
2110config KCOV_ENABLE_COMPARISONS
2111	bool "Enable comparison operands collection by KCOV"
2112	depends on KCOV
2113	depends on $(cc-option,-fsanitize-coverage=trace-cmp)
2114	help
2115	  KCOV also exposes operands of every comparison in the instrumented
2116	  code along with operand sizes and PCs of the comparison instructions.
2117	  These operands can be used by fuzzing engines to improve the quality
2118	  of fuzzing coverage.
2119
2120config KCOV_INSTRUMENT_ALL
2121	bool "Instrument all code by default"
2122	depends on KCOV
2123	default y
2124	help
2125	  If you are doing generic system call fuzzing (like e.g. syzkaller),
2126	  then you will want to instrument the whole kernel and you should
2127	  say y here. If you are doing more targeted fuzzing (like e.g.
2128	  filesystem fuzzing with AFL) then you will want to enable coverage
2129	  for more specific subsets of files, and should say n here.
2130
2131config KCOV_IRQ_AREA_SIZE
2132	hex "Size of interrupt coverage collection area in words"
2133	depends on KCOV
2134	default 0x40000
2135	help
2136	  KCOV uses preallocated per-cpu areas to collect coverage from
2137	  soft interrupts. This specifies the size of those areas in the
2138	  number of unsigned long words.
2139
2140menuconfig RUNTIME_TESTING_MENU
2141	bool "Runtime Testing"
2142	def_bool y
2143
2144if RUNTIME_TESTING_MENU
2145
2146config TEST_DHRY
2147	tristate "Dhrystone benchmark test"
2148	help
2149	  Enable this to include the Dhrystone 2.1 benchmark.  This test
2150	  calculates the number of Dhrystones per second, and the number of
2151	  DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided
2152	  by 1757 (the number of Dhrystones per second obtained on the VAX
2153	  11/780, nominally a 1 MIPS machine).
2154
2155	  To run the benchmark, it needs to be enabled explicitly, either from
2156	  the kernel command line (when built-in), or from userspace (when
2157	  built-in or modular.
2158
2159	  Run once during kernel boot:
2160
2161	      test_dhry.run
2162
2163	  Set number of iterations from kernel command line:
2164
2165	      test_dhry.iterations=<n>
2166
2167	  Set number of iterations from userspace:
2168
2169	      echo <n> > /sys/module/test_dhry/parameters/iterations
2170
2171	  Trigger manual run from userspace:
2172
2173	      echo y > /sys/module/test_dhry/parameters/run
2174
2175	  If the number of iterations is <= 0, the test will devise a suitable
2176	  number of iterations (test runs for at least 2s) automatically.
2177	  This process takes ca. 4s.
2178
2179	  If unsure, say N.
2180
2181config LKDTM
2182	tristate "Linux Kernel Dump Test Tool Module"
2183	depends on DEBUG_FS
2184	help
2185	This module enables testing of the different dumping mechanisms by
2186	inducing system failures at predefined crash points.
2187	If you don't need it: say N
2188	Choose M here to compile this code as a module. The module will be
2189	called lkdtm.
2190
2191	Documentation on how to use the module can be found in
2192	Documentation/fault-injection/provoke-crashes.rst
2193
2194config CPUMASK_KUNIT_TEST
2195	tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS
2196	depends on KUNIT
2197	default KUNIT_ALL_TESTS
2198	help
2199	  Enable to turn on cpumask tests, running at boot or module load time.
2200
2201	  For more information on KUnit and unit tests in general, please refer
2202	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2203
2204	  If unsure, say N.
2205
2206config TEST_LIST_SORT
2207	tristate "Linked list sorting test" if !KUNIT_ALL_TESTS
2208	depends on KUNIT
2209	default KUNIT_ALL_TESTS
2210	help
2211	  Enable this to turn on 'list_sort()' function test. This test is
2212	  executed only once during system boot (so affects only boot time),
2213	  or at module load time.
2214
2215	  If unsure, say N.
2216
2217config TEST_MIN_HEAP
2218	tristate "Min heap test"
2219	depends on DEBUG_KERNEL || m
2220	help
2221	  Enable this to turn on min heap function tests. This test is
2222	  executed only once during system boot (so affects only boot time),
2223	  or at module load time.
2224
2225	  If unsure, say N.
2226
2227config TEST_SORT
2228	tristate "Array-based sort test" if !KUNIT_ALL_TESTS
2229	depends on KUNIT
2230	default KUNIT_ALL_TESTS
2231	help
2232	  This option enables the self-test function of 'sort()' at boot,
2233	  or at module load time.
2234
2235	  If unsure, say N.
2236
2237config TEST_DIV64
2238	tristate "64bit/32bit division and modulo test"
2239	depends on DEBUG_KERNEL || m
2240	help
2241	  Enable this to turn on 'do_div()' function test. This test is
2242	  executed only once during system boot (so affects only boot time),
2243	  or at module load time.
2244
2245	  If unsure, say N.
2246
2247config TEST_IOV_ITER
2248	tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS
2249	depends on KUNIT
2250	default KUNIT_ALL_TESTS
2251	help
2252	  Enable this to turn on testing of the operation of the I/O iterator
2253	  (iov_iter). This test is executed only once during system boot (so
2254	  affects only boot time), or at module load time.
2255
2256	  If unsure, say N.
2257
2258config KPROBES_SANITY_TEST
2259	tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS
2260	depends on DEBUG_KERNEL
2261	depends on KPROBES
2262	depends on KUNIT
2263	select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
2264	default KUNIT_ALL_TESTS
2265	help
2266	  This option provides for testing basic kprobes functionality on
2267	  boot. Samples of kprobe and kretprobe are inserted and
2268	  verified for functionality.
2269
2270	  Say N if you are unsure.
2271
2272config FPROBE_SANITY_TEST
2273	bool "Self test for fprobe"
2274	depends on DEBUG_KERNEL
2275	depends on FPROBE
2276	depends on KUNIT=y
2277	help
2278	  This option will enable testing the fprobe when the system boot.
2279	  A series of tests are made to verify that the fprobe is functioning
2280	  properly.
2281
2282	  Say N if you are unsure.
2283
2284config BACKTRACE_SELF_TEST
2285	tristate "Self test for the backtrace code"
2286	depends on DEBUG_KERNEL
2287	help
2288	  This option provides a kernel module that can be used to test
2289	  the kernel stack backtrace code. This option is not useful
2290	  for distributions or general kernels, but only for kernel
2291	  developers working on architecture code.
2292
2293	  Note that if you want to also test saved backtraces, you will
2294	  have to enable STACKTRACE as well.
2295
2296	  Say N if you are unsure.
2297
2298config TEST_REF_TRACKER
2299	tristate "Self test for reference tracker"
2300	depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
2301	select REF_TRACKER
2302	help
2303	  This option provides a kernel module performing tests
2304	  using reference tracker infrastructure.
2305
2306	  Say N if you are unsure.
2307
2308config RBTREE_TEST
2309	tristate "Red-Black tree test"
2310	depends on DEBUG_KERNEL
2311	help
2312	  A benchmark measuring the performance of the rbtree library.
2313	  Also includes rbtree invariant checks.
2314
2315config REED_SOLOMON_TEST
2316	tristate "Reed-Solomon library test"
2317	depends on DEBUG_KERNEL || m
2318	select REED_SOLOMON
2319	select REED_SOLOMON_ENC16
2320	select REED_SOLOMON_DEC16
2321	help
2322	  This option enables the self-test function of rslib at boot,
2323	  or at module load time.
2324
2325	  If unsure, say N.
2326
2327config INTERVAL_TREE_TEST
2328	tristate "Interval tree test"
2329	depends on DEBUG_KERNEL
2330	select INTERVAL_TREE
2331	help
2332	  A benchmark measuring the performance of the interval tree library
2333
2334config PERCPU_TEST
2335	tristate "Per cpu operations test"
2336	depends on m && DEBUG_KERNEL
2337	help
2338	  Enable this option to build test module which validates per-cpu
2339	  operations.
2340
2341	  If unsure, say N.
2342
2343config ATOMIC64_SELFTEST
2344	tristate "Perform an atomic64_t self-test"
2345	help
2346	  Enable this option to test the atomic64_t functions at boot or
2347	  at module load time.
2348
2349	  If unsure, say N.
2350
2351config ASYNC_RAID6_TEST
2352	tristate "Self test for hardware accelerated raid6 recovery"
2353	depends on ASYNC_RAID6_RECOV
2354	select ASYNC_MEMCPY
2355	help
2356	  This is a one-shot self test that permutes through the
2357	  recovery of all the possible two disk failure scenarios for a
2358	  N-disk array.  Recovery is performed with the asynchronous
2359	  raid6 recovery routines, and will optionally use an offload
2360	  engine if one is available.
2361
2362	  If unsure, say N.
2363
2364config TEST_HEXDUMP
2365	tristate "Test functions located in the hexdump module at runtime"
2366
2367config STRING_SELFTEST
2368	tristate "Test string functions at runtime"
2369
2370config TEST_STRING_HELPERS
2371	tristate "Test functions located in the string_helpers module at runtime"
2372
2373config TEST_KSTRTOX
2374	tristate "Test kstrto*() family of functions at runtime"
2375
2376config TEST_PRINTF
2377	tristate "Test printf() family of functions at runtime"
2378
2379config TEST_SCANF
2380	tristate "Test scanf() family of functions at runtime"
2381
2382config TEST_BITMAP
2383	tristate "Test bitmap_*() family of functions at runtime"
2384	help
2385	  Enable this option to test the bitmap functions at boot.
2386
2387	  If unsure, say N.
2388
2389config TEST_UUID
2390	tristate "Test functions located in the uuid module at runtime"
2391
2392config TEST_XARRAY
2393	tristate "Test the XArray code at runtime"
2394
2395config TEST_MAPLE_TREE
2396	tristate "Test the Maple Tree code at runtime or module load"
2397	help
2398	  Enable this option to test the maple tree code functions at boot, or
2399	  when the module is loaded. Enable "Debug Maple Trees" will enable
2400	  more verbose output on failures.
2401
2402	  If unsure, say N.
2403
2404config TEST_RHASHTABLE
2405	tristate "Perform selftest on resizable hash table"
2406	help
2407	  Enable this option to test the rhashtable functions at boot.
2408
2409	  If unsure, say N.
2410
2411config TEST_IDA
2412	tristate "Perform selftest on IDA functions"
2413
2414config TEST_PARMAN
2415	tristate "Perform selftest on priority array manager"
2416	depends on PARMAN
2417	help
2418	  Enable this option to test priority array manager on boot
2419	  (or module load).
2420
2421	  If unsure, say N.
2422
2423config TEST_IRQ_TIMINGS
2424	bool "IRQ timings selftest"
2425	depends on IRQ_TIMINGS
2426	help
2427	  Enable this option to test the irq timings code on boot.
2428
2429	  If unsure, say N.
2430
2431config TEST_LKM
2432	tristate "Test module loading with 'hello world' module"
2433	depends on m
2434	help
2435	  This builds the "test_module" module that emits "Hello, world"
2436	  on printk when loaded. It is designed to be used for basic
2437	  evaluation of the module loading subsystem (for example when
2438	  validating module verification). It lacks any extra dependencies,
2439	  and will not normally be loaded by the system unless explicitly
2440	  requested by name.
2441
2442	  If unsure, say N.
2443
2444config TEST_BITOPS
2445	tristate "Test module for compilation of bitops operations"
2446	depends on m
2447	help
2448	  This builds the "test_bitops" module that is much like the
2449	  TEST_LKM module except that it does a basic exercise of the
2450	  set/clear_bit macros and get_count_order/long to make sure there are
2451	  no compiler warnings from C=1 sparse checker or -Wextra
2452	  compilations. It has no dependencies and doesn't run or load unless
2453	  explicitly requested by name.  for example: modprobe test_bitops.
2454
2455	  If unsure, say N.
2456
2457config TEST_VMALLOC
2458	tristate "Test module for stress/performance analysis of vmalloc allocator"
2459	default n
2460       depends on MMU
2461	depends on m
2462	help
2463	  This builds the "test_vmalloc" module that should be used for
2464	  stress and performance analysis. So, any new change for vmalloc
2465	  subsystem can be evaluated from performance and stability point
2466	  of view.
2467
2468	  If unsure, say N.
2469
2470config TEST_USER_COPY
2471	tristate "Test user/kernel boundary protections"
2472	depends on m
2473	help
2474	  This builds the "test_user_copy" module that runs sanity checks
2475	  on the copy_to/from_user infrastructure, making sure basic
2476	  user/kernel boundary testing is working. If it fails to load,
2477	  a regression has been detected in the user/kernel memory boundary
2478	  protections.
2479
2480	  If unsure, say N.
2481
2482config TEST_BPF
2483	tristate "Test BPF filter functionality"
2484	depends on m && NET
2485	help
2486	  This builds the "test_bpf" module that runs various test vectors
2487	  against the BPF interpreter or BPF JIT compiler depending on the
2488	  current setting. This is in particular useful for BPF JIT compiler
2489	  development, but also to run regression tests against changes in
2490	  the interpreter code. It also enables test stubs for eBPF maps and
2491	  verifier used by user space verifier testsuite.
2492
2493	  If unsure, say N.
2494
2495config TEST_BLACKHOLE_DEV
2496	tristate "Test blackhole netdev functionality"
2497	depends on m && NET
2498	help
2499	  This builds the "test_blackhole_dev" module that validates the
2500	  data path through this blackhole netdev.
2501
2502	  If unsure, say N.
2503
2504config FIND_BIT_BENCHMARK
2505	tristate "Test find_bit functions"
2506	help
2507	  This builds the "test_find_bit" module that measure find_*_bit()
2508	  functions performance.
2509
2510	  If unsure, say N.
2511
2512config TEST_FIRMWARE
2513	tristate "Test firmware loading via userspace interface"
2514	depends on FW_LOADER
2515	help
2516	  This builds the "test_firmware" module that creates a userspace
2517	  interface for testing firmware loading. This can be used to
2518	  control the triggering of firmware loading without needing an
2519	  actual firmware-using device. The contents can be rechecked by
2520	  userspace.
2521
2522	  If unsure, say N.
2523
2524config TEST_SYSCTL
2525	tristate "sysctl test driver"
2526	depends on PROC_SYSCTL
2527	help
2528	  This builds the "test_sysctl" module. This driver enables to test the
2529	  proc sysctl interfaces available to drivers safely without affecting
2530	  production knobs which might alter system functionality.
2531
2532	  If unsure, say N.
2533
2534config BITFIELD_KUNIT
2535	tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS
2536	depends on KUNIT
2537	default KUNIT_ALL_TESTS
2538	help
2539	  Enable this option to test the bitfield functions at boot.
2540
2541	  KUnit tests run during boot and output the results to the debug log
2542	  in TAP format (http://testanything.org/). Only useful for kernel devs
2543	  running the KUnit test harness, and not intended for inclusion into a
2544	  production build.
2545
2546	  For more information on KUnit and unit tests in general please refer
2547	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2548
2549	  If unsure, say N.
2550
2551config CHECKSUM_KUNIT
2552	tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS
2553	depends on KUNIT
2554	default KUNIT_ALL_TESTS
2555	help
2556	  Enable this option to test the checksum functions at boot.
2557
2558	  KUnit tests run during boot and output the results to the debug log
2559	  in TAP format (http://testanything.org/). Only useful for kernel devs
2560	  running the KUnit test harness, and not intended for inclusion into a
2561	  production build.
2562
2563	  For more information on KUnit and unit tests in general please refer
2564	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2565
2566	  If unsure, say N.
2567
2568config HASH_KUNIT_TEST
2569	tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS
2570	depends on KUNIT
2571	default KUNIT_ALL_TESTS
2572	help
2573	  Enable this option to test the kernel's string (<linux/stringhash.h>), and
2574	  integer (<linux/hash.h>) hash functions on boot.
2575
2576	  KUnit tests run during boot and output the results to the debug log
2577	  in TAP format (https://testanything.org/). Only useful for kernel devs
2578	  running the KUnit test harness, and not intended for inclusion into a
2579	  production build.
2580
2581	  For more information on KUnit and unit tests in general please refer
2582	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2583
2584	  This is intended to help people writing architecture-specific
2585	  optimized versions. If unsure, say N.
2586
2587config RESOURCE_KUNIT_TEST
2588	tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS
2589	depends on KUNIT
2590	default KUNIT_ALL_TESTS
2591	help
2592	  This builds the resource API unit test.
2593	  Tests the logic of API provided by resource.c and ioport.h.
2594	  For more information on KUnit and unit tests in general please refer
2595	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2596
2597	  If unsure, say N.
2598
2599config SYSCTL_KUNIT_TEST
2600	tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS
2601	depends on KUNIT
2602	default KUNIT_ALL_TESTS
2603	help
2604	  This builds the proc sysctl unit test, which runs on boot.
2605	  Tests the API contract and implementation correctness of sysctl.
2606	  For more information on KUnit and unit tests in general please refer
2607	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2608
2609	  If unsure, say N.
2610
2611config LIST_KUNIT_TEST
2612	tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS
2613	depends on KUNIT
2614	default KUNIT_ALL_TESTS
2615	help
2616	  This builds the linked list KUnit test suite.
2617	  It tests that the API and basic functionality of the list_head type
2618	  and associated macros.
2619
2620	  KUnit tests run during boot and output the results to the debug log
2621	  in TAP format (https://testanything.org/). Only useful for kernel devs
2622	  running the KUnit test harness, and not intended for inclusion into a
2623	  production build.
2624
2625	  For more information on KUnit and unit tests in general please refer
2626	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2627
2628	  If unsure, say N.
2629
2630config HASHTABLE_KUNIT_TEST
2631	tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS
2632	depends on KUNIT
2633	default KUNIT_ALL_TESTS
2634	help
2635	  This builds the hashtable KUnit test suite.
2636	  It tests the basic functionality of the API defined in
2637	  include/linux/hashtable.h. For more information on KUnit and
2638	  unit tests in general please refer to the KUnit documentation
2639	  in Documentation/dev-tools/kunit/.
2640
2641	  If unsure, say N.
2642
2643config LINEAR_RANGES_TEST
2644	tristate "KUnit test for linear_ranges"
2645	depends on KUNIT
2646	select LINEAR_RANGES
2647	help
2648	  This builds the linear_ranges unit test, which runs on boot.
2649	  Tests the linear_ranges logic correctness.
2650	  For more information on KUnit and unit tests in general please refer
2651	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2652
2653	  If unsure, say N.
2654
2655config CMDLINE_KUNIT_TEST
2656	tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS
2657	depends on KUNIT
2658	default KUNIT_ALL_TESTS
2659	help
2660	  This builds the cmdline API unit test.
2661	  Tests the logic of API provided by cmdline.c.
2662	  For more information on KUnit and unit tests in general please refer
2663	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2664
2665	  If unsure, say N.
2666
2667config BITS_TEST
2668	tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS
2669	depends on KUNIT
2670	default KUNIT_ALL_TESTS
2671	help
2672	  This builds the bits unit test.
2673	  Tests the logic of macros defined in bits.h.
2674	  For more information on KUnit and unit tests in general please refer
2675	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2676
2677	  If unsure, say N.
2678
2679config SLUB_KUNIT_TEST
2680	tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS
2681	depends on SLUB_DEBUG && KUNIT
2682	default KUNIT_ALL_TESTS
2683	help
2684	  This builds SLUB allocator unit test.
2685	  Tests SLUB cache debugging functionality.
2686	  For more information on KUnit and unit tests in general please refer
2687	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2688
2689	  If unsure, say N.
2690
2691config RATIONAL_KUNIT_TEST
2692	tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS
2693	depends on KUNIT && RATIONAL
2694	default KUNIT_ALL_TESTS
2695	help
2696	  This builds the rational math unit test.
2697	  For more information on KUnit and unit tests in general please refer
2698	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2699
2700	  If unsure, say N.
2701
2702config MEMCPY_KUNIT_TEST
2703	tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS
2704	depends on KUNIT
2705	default KUNIT_ALL_TESTS
2706	help
2707	  Builds unit tests for memcpy(), memmove(), and memset() functions.
2708	  For more information on KUnit and unit tests in general please refer
2709	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2710
2711	  If unsure, say N.
2712
2713config MEMCPY_SLOW_KUNIT_TEST
2714	bool "Include exhaustive memcpy tests"
2715	depends on MEMCPY_KUNIT_TEST
2716	default y
2717	help
2718	  Some memcpy tests are quite exhaustive in checking for overlaps
2719	  and bit ranges. These can be very slow, so they are split out
2720	  as a separate config, in case they need to be disabled.
2721
2722	  Note this config option will be replaced by the use of KUnit test
2723	  attributes.
2724
2725config IS_SIGNED_TYPE_KUNIT_TEST
2726	tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS
2727	depends on KUNIT
2728	default KUNIT_ALL_TESTS
2729	help
2730	  Builds unit tests for the is_signed_type() macro.
2731
2732	  For more information on KUnit and unit tests in general please refer
2733	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2734
2735	  If unsure, say N.
2736
2737config OVERFLOW_KUNIT_TEST
2738	tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS
2739	depends on KUNIT
2740	default KUNIT_ALL_TESTS
2741	help
2742	  Builds unit tests for the check_*_overflow(), size_*(), allocation, and
2743	  related functions.
2744
2745	  For more information on KUnit and unit tests in general please refer
2746	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2747
2748	  If unsure, say N.
2749
2750config STACKINIT_KUNIT_TEST
2751	tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS
2752	depends on KUNIT
2753	default KUNIT_ALL_TESTS
2754	help
2755	  Test if the kernel is zero-initializing stack variables and
2756	  padding. Coverage is controlled by compiler flags,
2757	  CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO,
2758	  CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2759	  or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2760
2761config FORTIFY_KUNIT_TEST
2762	tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS
2763	depends on KUNIT && FORTIFY_SOURCE
2764	default KUNIT_ALL_TESTS
2765	help
2766	  Builds unit tests for checking internals of FORTIFY_SOURCE as used
2767	  by the str*() and mem*() family of functions. For testing runtime
2768	  traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests.
2769
2770config HW_BREAKPOINT_KUNIT_TEST
2771	bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS
2772	depends on HAVE_HW_BREAKPOINT
2773	depends on KUNIT=y
2774	default KUNIT_ALL_TESTS
2775	help
2776	  Tests for hw_breakpoint constraints accounting.
2777
2778	  If unsure, say N.
2779
2780config STRCAT_KUNIT_TEST
2781	tristate "Test strcat() family of functions at runtime" if !KUNIT_ALL_TESTS
2782	depends on KUNIT
2783	default KUNIT_ALL_TESTS
2784
2785config STRSCPY_KUNIT_TEST
2786	tristate "Test strscpy*() family of functions at runtime" if !KUNIT_ALL_TESTS
2787	depends on KUNIT
2788	default KUNIT_ALL_TESTS
2789
2790config SIPHASH_KUNIT_TEST
2791	tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS
2792	depends on KUNIT
2793	default KUNIT_ALL_TESTS
2794	help
2795	  Enable this option to test the kernel's siphash (<linux/siphash.h>) hash
2796	  functions on boot (or module load).
2797
2798	  This is intended to help people writing architecture-specific
2799	  optimized versions.  If unsure, say N.
2800
2801config TEST_UDELAY
2802	tristate "udelay test driver"
2803	help
2804	  This builds the "udelay_test" module that helps to make sure
2805	  that udelay() is working properly.
2806
2807	  If unsure, say N.
2808
2809config TEST_STATIC_KEYS
2810	tristate "Test static keys"
2811	depends on m
2812	help
2813	  Test the static key interfaces.
2814
2815	  If unsure, say N.
2816
2817config TEST_DYNAMIC_DEBUG
2818	tristate "Test DYNAMIC_DEBUG"
2819	depends on DYNAMIC_DEBUG
2820	help
2821	  This module registers a tracer callback to count enabled
2822	  pr_debugs in a 'do_debugging' function, then alters their
2823	  enablements, calls the function, and compares counts.
2824
2825	  If unsure, say N.
2826
2827config TEST_KMOD
2828	tristate "kmod stress tester"
2829	depends on m
2830	depends on NETDEVICES && NET_CORE && INET # for TUN
2831	depends on BLOCK
2832	depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS
2833	select TEST_LKM
2834	select XFS_FS
2835	select TUN
2836	select BTRFS_FS
2837	help
2838	  Test the kernel's module loading mechanism: kmod. kmod implements
2839	  support to load modules using the Linux kernel's usermode helper.
2840	  This test provides a series of tests against kmod.
2841
2842	  Although technically you can either build test_kmod as a module or
2843	  into the kernel we disallow building it into the kernel since
2844	  it stress tests request_module() and this will very likely cause
2845	  some issues by taking over precious threads available from other
2846	  module load requests, ultimately this could be fatal.
2847
2848	  To run tests run:
2849
2850	  tools/testing/selftests/kmod/kmod.sh --help
2851
2852	  If unsure, say N.
2853
2854config TEST_DEBUG_VIRTUAL
2855	tristate "Test CONFIG_DEBUG_VIRTUAL feature"
2856	depends on DEBUG_VIRTUAL
2857	help
2858	  Test the kernel's ability to detect incorrect calls to
2859	  virt_to_phys() done against the non-linear part of the
2860	  kernel's virtual address map.
2861
2862	  If unsure, say N.
2863
2864config TEST_MEMCAT_P
2865	tristate "Test memcat_p() helper function"
2866	help
2867	  Test the memcat_p() helper for correctly merging two
2868	  pointer arrays together.
2869
2870	  If unsure, say N.
2871
2872config TEST_LIVEPATCH
2873	tristate "Test livepatching"
2874	default n
2875	depends on DYNAMIC_DEBUG
2876	depends on LIVEPATCH
2877	depends on m
2878	help
2879	  Test kernel livepatching features for correctness.  The tests will
2880	  load test modules that will be livepatched in various scenarios.
2881
2882	  To run all the livepatching tests:
2883
2884	  make -C tools/testing/selftests TARGETS=livepatch run_tests
2885
2886	  Alternatively, individual tests may be invoked:
2887
2888	  tools/testing/selftests/livepatch/test-callbacks.sh
2889	  tools/testing/selftests/livepatch/test-livepatch.sh
2890	  tools/testing/selftests/livepatch/test-shadow-vars.sh
2891
2892	  If unsure, say N.
2893
2894config TEST_OBJAGG
2895	tristate "Perform selftest on object aggreration manager"
2896	default n
2897	depends on OBJAGG
2898	help
2899	  Enable this option to test object aggregation manager on boot
2900	  (or module load).
2901
2902config TEST_MEMINIT
2903	tristate "Test heap/page initialization"
2904	help
2905	  Test if the kernel is zero-initializing heap and page allocations.
2906	  This can be useful to test init_on_alloc and init_on_free features.
2907
2908	  If unsure, say N.
2909
2910config TEST_HMM
2911	tristate "Test HMM (Heterogeneous Memory Management)"
2912	depends on TRANSPARENT_HUGEPAGE
2913	depends on DEVICE_PRIVATE
2914	select HMM_MIRROR
2915	select MMU_NOTIFIER
2916	help
2917	  This is a pseudo device driver solely for testing HMM.
2918	  Say M here if you want to build the HMM test module.
2919	  Doing so will allow you to run tools/testing/selftest/vm/hmm-tests.
2920
2921	  If unsure, say N.
2922
2923config TEST_FREE_PAGES
2924	tristate "Test freeing pages"
2925	help
2926	  Test that a memory leak does not occur due to a race between
2927	  freeing a block of pages and a speculative page reference.
2928	  Loading this module is safe if your kernel has the bug fixed.
2929	  If the bug is not fixed, it will leak gigabytes of memory and
2930	  probably OOM your system.
2931
2932config TEST_FPU
2933	tristate "Test floating point operations in kernel space"
2934	depends on X86 && !KCOV_INSTRUMENT_ALL
2935	help
2936	  Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu
2937	  which will trigger a sequence of floating point operations. This is used
2938	  for self-testing floating point control register setting in
2939	  kernel_fpu_begin().
2940
2941	  If unsure, say N.
2942
2943config TEST_CLOCKSOURCE_WATCHDOG
2944	tristate "Test clocksource watchdog in kernel space"
2945	depends on CLOCKSOURCE_WATCHDOG
2946	help
2947	  Enable this option to create a kernel module that will trigger
2948	  a test of the clocksource watchdog.  This module may be loaded
2949	  via modprobe or insmod in which case it will run upon being
2950	  loaded, or it may be built in, in which case it will run
2951	  shortly after boot.
2952
2953	  If unsure, say N.
2954
2955config TEST_OBJPOOL
2956	tristate "Test module for correctness and stress of objpool"
2957	default n
2958	depends on m && DEBUG_KERNEL
2959	help
2960	  This builds the "test_objpool" module that should be used for
2961	  correctness verification and concurrent testings of objects
2962	  allocation and reclamation.
2963
2964	  If unsure, say N.
2965
2966endif # RUNTIME_TESTING_MENU
2967
2968config ARCH_USE_MEMTEST
2969	bool
2970	help
2971	  An architecture should select this when it uses early_memtest()
2972	  during boot process.
2973
2974config MEMTEST
2975	bool "Memtest"
2976	depends on ARCH_USE_MEMTEST
2977	help
2978	  This option adds a kernel parameter 'memtest', which allows memtest
2979	  to be set and executed.
2980	        memtest=0, mean disabled; -- default
2981	        memtest=1, mean do 1 test pattern;
2982	        ...
2983	        memtest=17, mean do 17 test patterns.
2984	  If you are unsure how to answer this question, answer N.
2985
2986
2987
2988config HYPERV_TESTING
2989	bool "Microsoft Hyper-V driver testing"
2990	default n
2991	depends on HYPERV && DEBUG_FS
2992	help
2993	  Select this option to enable Hyper-V vmbus testing.
2994
2995endmenu # "Kernel Testing and Coverage"
2996
2997menu "Rust hacking"
2998
2999config RUST_DEBUG_ASSERTIONS
3000	bool "Debug assertions"
3001	depends on RUST
3002	help
3003	  Enables rustc's `-Cdebug-assertions` codegen option.
3004
3005	  This flag lets you turn `cfg(debug_assertions)` conditional
3006	  compilation on or off. This can be used to enable extra debugging
3007	  code in development but not in production. For example, it controls
3008	  the behavior of the standard library's `debug_assert!` macro.
3009
3010	  Note that this will apply to all Rust code, including `core`.
3011
3012	  If unsure, say N.
3013
3014config RUST_OVERFLOW_CHECKS
3015	bool "Overflow checks"
3016	default y
3017	depends on RUST
3018	help
3019	  Enables rustc's `-Coverflow-checks` codegen option.
3020
3021	  This flag allows you to control the behavior of runtime integer
3022	  overflow. When overflow-checks are enabled, a Rust panic will occur
3023	  on overflow.
3024
3025	  Note that this will apply to all Rust code, including `core`.
3026
3027	  If unsure, say Y.
3028
3029config RUST_BUILD_ASSERT_ALLOW
3030	bool "Allow unoptimized build-time assertions"
3031	depends on RUST
3032	help
3033	  Controls how are `build_error!` and `build_assert!` handled during build.
3034
3035	  If calls to them exist in the binary, it may indicate a violated invariant
3036	  or that the optimizer failed to verify the invariant during compilation.
3037
3038	  This should not happen, thus by default the build is aborted. However,
3039	  as an escape hatch, you can choose Y here to ignore them during build
3040	  and let the check be carried at runtime (with `panic!` being called if
3041	  the check fails).
3042
3043	  If unsure, say N.
3044
3045config RUST_KERNEL_DOCTESTS
3046	bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS
3047	depends on RUST && KUNIT=y
3048	default KUNIT_ALL_TESTS
3049	help
3050	  This builds the documentation tests of the `kernel` crate
3051	  as KUnit tests.
3052
3053	  For more information on KUnit and unit tests in general,
3054	  please refer to the KUnit documentation in Documentation/dev-tools/kunit/.
3055
3056	  If unsure, say N.
3057
3058endmenu # "Rust"
3059
3060endmenu # Kernel hacking
3061