linux - lib/Kconfig.debug

3630 lines · 118.4 KiB

1	# SPDX-License-Identifier: GPL-2.0-only
2	menu "Kernel hacking"
3
4	menu "printk and dmesg options"
5
6	config 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
21	config 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
38	config PRINTK_EXECUTION_CTX
39	bool
40	depends on PRINTK
41	help
42	This option extends struct printk_info to include extra execution
43	context in printk, such as task name and CPU number from where the
44	message originated. This is useful for correlating printk messages
45	with specific execution contexts.
46
47	This is automatically enabled when a console driver that supports
48	execution context is selected.
49
50	config STACKTRACE_BUILD_ID
51	bool "Show build ID information in stacktraces"
52	depends on PRINTK
53	help
54	Selecting this option adds build ID information for symbols in
55	stacktraces printed with the printk format '%p[SR]b'.
56
57	This option is intended for distros where debuginfo is not easily
58	accessible but can be downloaded given the build ID of the vmlinux or
59	kernel module where the function is located.
60
61	config CONSOLE_LOGLEVEL_DEFAULT
62	int "Default console loglevel (1-15)"
63	range 1 15
64	default "7"
65	help
66	Default loglevel to determine what will be printed on the console.
67
68	Setting a default here is equivalent to passing in loglevel=<x> in
69	the kernel bootargs. loglevel=<x> continues to override whatever
70	value is specified here as well.
71
72	Note: This does not affect the log level of un-prefixed printk()
73	usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT
74	option.
75
76	config CONSOLE_LOGLEVEL_QUIET
77	int "quiet console loglevel (1-15)"
78	range 1 15
79	default "4"
80	help
81	loglevel to use when "quiet" is passed on the kernel commandline.
82
83	When "quiet" is passed on the kernel commandline this loglevel
84	will be used as the loglevel. IOW passing "quiet" will be the
85	equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>"
86
87	config MESSAGE_LOGLEVEL_DEFAULT
88	int "Default message log level (1-7)"
89	range 1 7
90	default "4"
91	help
92	Default log level for printk statements with no specified priority.
93
94	This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
95	that are auditing their logs closely may want to set it to a lower
96	priority.
97
98	Note: This does not affect what message level gets printed on the console
99	by default. To change that, use loglevel=<x> in the kernel bootargs,
100	or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value.
101
102	config BOOT_PRINTK_DELAY
103	bool "Delay each boot printk message by N milliseconds"
104	depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
105	help
106	This build option allows you to read kernel boot messages
107	by inserting a short delay after each one. The delay is
108	specified in milliseconds on the kernel command line,
109	using "boot_delay=N".
110
111	It is likely that you would also need to use "lpj=M" to preset
112	the "loops per jiffy" value.
113	See a previous boot log for the "lpj" value to use for your
114	system, and then set "lpj=M" before setting "boot_delay=N".
115	NOTE: Using this option may adversely affect SMP systems.
116	I.e., processors other than the first one may not boot up.
117	BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
118	what it believes to be lockup conditions.
119
120	config DYNAMIC_DEBUG
121	bool "Enable dynamic printk() support"
122	default n
123	depends on PRINTK
124	depends on (DEBUG_FS \|\| PROC_FS)
125	select DYNAMIC_DEBUG_CORE
126	help
127
128	Compiles debug level messages into the kernel, which would not
129	otherwise be available at runtime. These messages can then be
130	enabled/disabled based on various levels of scope - per source file,
131	function, module, format string, and line number. This mechanism
132	implicitly compiles in all pr_debug() and dev_dbg() calls, which
133	enlarges the kernel text size by about 2%.
134
135	If a source file is compiled with DEBUG flag set, any
136	pr_debug() calls in it are enabled by default, but can be
137	disabled at runtime as below. Note that DEBUG flag is
138	turned on by many CONFIG_DEBUG options.
139
140	Usage:
141
142	Dynamic debugging is controlled via the 'dynamic_debug/control' file,
143	which is contained in the 'debugfs' filesystem or procfs.
144	Thus, the debugfs or procfs filesystem must first be mounted before
145	making use of this feature.
146	We refer the control file as: <debugfs>/dynamic_debug/control. This
147	file contains a list of the debug statements that can be enabled. The
148	format for each line of the file is:
149
150	filename:lineno [module]function flags format
151
152	filename : source file of the debug statement
153	lineno : line number of the debug statement
154	module : module that contains the debug statement
155	function : function that contains the debug statement
156	flags : '=p' means the line is turned 'on' for printing
157	format : the format used for the debug statement
158
159	From a live system:
160
161	nullarbor:~ # cat <debugfs>/dynamic_debug/control
162	# filename:lineno [module]function flags format
163	fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
164	fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
165	fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
166
167	Example usage:
168
169	// enable the message at line 1603 of file svcsock.c
170	nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
171	<debugfs>/dynamic_debug/control
172
173	// enable all the messages in file svcsock.c
174	nullarbor:~ # echo -n 'file svcsock.c +p' >
175	<debugfs>/dynamic_debug/control
176
177	// enable all the messages in the NFS server module
178	nullarbor:~ # echo -n 'module nfsd +p' >
179	<debugfs>/dynamic_debug/control
180
181	// enable all 12 messages in the function svc_process()
182	nullarbor:~ # echo -n 'func svc_process +p' >
183	<debugfs>/dynamic_debug/control
184
185	// disable all 12 messages in the function svc_process()
186	nullarbor:~ # echo -n 'func svc_process -p' >
187	<debugfs>/dynamic_debug/control
188
189	See Documentation/admin-guide/dynamic-debug-howto.rst for additional
190	information.
191
192	config DYNAMIC_DEBUG_CORE
193	bool "Enable core function of dynamic debug support"
194	depends on PRINTK
195	depends on (DEBUG_FS \|\| PROC_FS)
196	help
197	Enable core functional support of dynamic debug. It is useful
198	when you want to tie dynamic debug to your kernel modules with
199	DYNAMIC_DEBUG_MODULE defined for each of them, especially for
200	the case of embedded system where the kernel image size is
201	sensitive for people.
202
203	config SYMBOLIC_ERRNAME
204	bool "Support symbolic error names in printf"
205	default y if PRINTK
206	help
207	If you say Y here, the kernel's printf implementation will
208	be able to print symbolic error names such as ENOSPC instead
209	of the number 28. It makes the kernel image slightly larger
210	(about 3KB), but can make the kernel logs easier to read.
211
212	config DEBUG_BUGVERBOSE
213	bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
214	depends on BUG && (GENERIC_BUG \|\| HAVE_DEBUG_BUGVERBOSE)
215	default y
216	help
217	Say Y here to make BUG() panics output the file name and line number
218	of the BUG call as well as the EIP and oops trace. This aids
219	debugging but costs about 70-100K of memory.
220
221	config DEBUG_BUGVERBOSE_DETAILED
222	bool "Verbose WARN_ON_ONCE() reporting (adds 100K)" if DEBUG_BUGVERBOSE
223	help
224	Say Y here to make WARN_ON_ONCE() output the condition string of the
225	warning, in addition to the file name and line number.
226	This helps debugging, but costs about 100K of memory.
227
228	Say N if unsure.
229
230
231	endmenu # "printk and dmesg options"
232
233	config DEBUG_KERNEL
234	bool "Kernel debugging"
235	help
236	Say Y here if you are developing drivers or trying to debug and
237	identify kernel problems.
238
239	config DEBUG_MISC
240	bool "Miscellaneous debug code"
241	default DEBUG_KERNEL
242	depends on DEBUG_KERNEL
243	help
244	Say Y here if you need to enable miscellaneous debug code that should
245	be under a more specific debug option but isn't.
246
247	menu "Compile-time checks and compiler options"
248
249	config DEBUG_INFO
250	bool
251	help
252	A kernel debug info option other than "None" has been selected
253	in the "Debug information" choice below, indicating that debug
254	information will be generated for build targets.
255
256	# Clang generates .uleb128 with label differences for DWARF v5, a feature that
257	# older binutils ports do not support when utilizing RISC-V style linker
258	# relaxation: https://sourceware.org/bugzilla/show_bug.cgi?id=27215
259	config AS_HAS_NON_CONST_ULEB128
260	def_bool $(as-instr,.uleb128 .Lexpr_end4 - .Lexpr_start3\n.Lexpr_start3:\n.Lexpr_end4:)
261
262	choice
263	prompt "Debug information"
264	depends on DEBUG_KERNEL
265	help
266	Selecting something other than "None" results in a kernel image
267	that will include debugging info resulting in a larger kernel image.
268	This adds debug symbols to the kernel and modules (gcc -g), and
269	is needed if you intend to use kernel crashdump or binary object
270	tools like crash, kgdb, LKCD, gdb, etc on the kernel.
271
272	Choose which version of DWARF debug info to emit. If unsure,
273	select "Toolchain default".
274
275	config DEBUG_INFO_NONE
276	bool "Disable debug information"
277	help
278	Do not build the kernel with debugging information, which will
279	result in a faster and smaller build.
280
281	config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
282	bool "Rely on the toolchain's implicit default DWARF version"
283	select DEBUG_INFO
284	depends on !CC_IS_CLANG \|\| AS_IS_LLVM \|\| (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128)
285	help
286	The implicit default version of DWARF debug info produced by a
287	toolchain changes over time.
288
289	This can break consumers of the debug info that haven't upgraded to
290	support newer revisions, and prevent testing newer versions, but
291	those should be less common scenarios.
292
293	config DEBUG_INFO_DWARF4
294	bool "Generate DWARF Version 4 debuginfo"
295	select DEBUG_INFO
296	depends on !CC_IS_CLANG \|\| AS_IS_LLVM \|\| (AS_IS_GNU && AS_VERSION >= 23502)
297	help
298	Generate DWARF v4 debug info. This requires gcc 4.5+, binutils 2.35.2
299	if using clang without clang's integrated assembler, and gdb 7.0+.
300
301	If you have consumers of DWARF debug info that are not ready for
302	newer revisions of DWARF, you may wish to choose this or have your
303	config select this.
304
305	config DEBUG_INFO_DWARF5
306	bool "Generate DWARF Version 5 debuginfo"
307	select DEBUG_INFO
308	depends on !ARCH_HAS_BROKEN_DWARF5
309	depends on !CC_IS_CLANG \|\| AS_IS_LLVM \|\| (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128)
310	help
311	Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc
312	5.0+ accepts the -gdwarf-5 flag but only had partial support for some
313	draft features until 7.0), and gdb 8.0+.
314
315	Changes to the structure of debug info in Version 5 allow for around
316	15-18% savings in resulting image and debug info section sizes as
317	compared to DWARF Version 4. DWARF Version 5 standardizes previous
318	extensions such as accelerators for symbol indexing and the format
319	for fission (.dwo/.dwp) files. Users may not want to select this
320	config if they rely on tooling that has not yet been updated to
321	support DWARF Version 5.
322
323	endchoice # "Debug information"
324
325	if DEBUG_INFO
326
327	config DEBUG_INFO_REDUCED
328	bool "Reduce debugging information"
329	help
330	If you say Y here gcc is instructed to generate less debugging
331	information for structure types. This means that tools that
332	need full debugging information (like kgdb or systemtap) won't
333	be happy. But if you merely need debugging information to
334	resolve line numbers there is no loss. Advantage is that
335	build directory object sizes shrink dramatically over a full
336	DEBUG_INFO build and compile times are reduced too.
337	Only works with newer gcc versions.
338
339	choice
340	prompt "Compressed Debug information"
341	help
342	Compress the resulting debug info. Results in smaller debug info sections,
343	but requires that consumers are able to decompress the results.
344
345	If unsure, choose DEBUG_INFO_COMPRESSED_NONE.
346
347	config DEBUG_INFO_COMPRESSED_NONE
348	bool "Don't compress debug information"
349	help
350	Don't compress debug info sections.
351
352	config DEBUG_INFO_COMPRESSED_ZLIB
353	bool "Compress debugging information with zlib"
354	depends on $(cc-option,-gz=zlib)
355	depends on $(ld-option,--compress-debug-sections=zlib)
356	help
357	Compress the debug information using zlib.
358
359	Users of dpkg-deb via debian/rules may find an increase in
360	size of their debug .deb packages with this config set, due to the
361	debug info being compressed with zlib, then the object files being
362	recompressed with a different compression scheme. But this is still
363	preferable to setting KDEB_COMPRESS or DPKG_DEB_COMPRESSOR_TYPE to
364	"none" which would be even larger.
365
366	config DEBUG_INFO_COMPRESSED_ZSTD
367	bool "Compress debugging information with zstd"
368	depends on $(cc-option,-gz=zstd)
369	depends on $(ld-option,--compress-debug-sections=zstd)
370	help
371	Compress the debug information using zstd. This may provide better
372	compression than zlib, for about the same time costs, but requires newer
373	toolchain support. Requires GCC 13.0+ or Clang 16.0+, binutils 2.40+, and
374	zstd.
375
376	endchoice # "Compressed Debug information"
377
378	config DEBUG_INFO_SPLIT
379	bool "Produce split debuginfo in .dwo files"
380	depends on $(cc-option,-gsplit-dwarf)
381	# RISC-V linker relaxation + -gsplit-dwarf has issues with LLVM and GCC
382	# prior to 12.x:
383	# https://github.com/llvm/llvm-project/issues/56642
384	# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99090
385	depends on !RISCV \|\| GCC_VERSION >= 120000
386	help
387	Generate debug info into separate .dwo files. This significantly
388	reduces the build directory size for builds with DEBUG_INFO,
389	because it stores the information only once on disk in .dwo
390	files instead of multiple times in object files and executables.
391	In addition the debug information is also compressed.
392
393	Requires recent gcc (4.7+) and recent gdb/binutils.
394	Any tool that packages or reads debug information would need
395	to know about the .dwo files and include them.
396	Incompatible with older versions of ccache.
397
398	config DEBUG_INFO_BTF
399	bool "Generate BTF type information"
400	depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED
401	depends on !GCC_PLUGIN_RANDSTRUCT \|\| COMPILE_TEST
402	depends on BPF_SYSCALL
403	depends on PAHOLE_VERSION >= 122
404	# pahole uses elfutils, which does not have support for Hexagon relocations
405	depends on !HEXAGON
406	help
407	Generate deduplicated BTF type information from DWARF debug info.
408	Turning this on requires pahole v1.22 or later, which will convert
409	DWARF type info into equivalent deduplicated BTF type info.
410
411	config PAHOLE_HAS_BTF_TAG
412	def_bool PAHOLE_VERSION >= 123
413	depends on CC_IS_CLANG
414	help
415	Decide whether pahole emits btf_tag attributes (btf_type_tag and
416	btf_decl_tag) or not. Currently only clang compiler implements
417	these attributes, so make the config depend on CC_IS_CLANG.
418
419	config PAHOLE_HAS_LANG_EXCLUDE
420	def_bool PAHOLE_VERSION >= 124
421	help
422	Support for the --lang_exclude flag which makes pahole exclude
423	compilation units from the supplied language. Used in Kbuild to
424	omit Rust CUs which are not supported in version 1.24 of pahole,
425	otherwise it would emit malformed kernel and module binaries when
426	using DEBUG_INFO_BTF_MODULES.
427
428	config DEBUG_INFO_BTF_MODULES
429	bool "Generate BTF type information for kernel modules"
430	default y
431	depends on DEBUG_INFO_BTF && MODULES
432	help
433	Generate compact split BTF type information for kernel modules.
434
435	config MODULE_ALLOW_BTF_MISMATCH
436	bool "Allow loading modules with non-matching BTF type info"
437	depends on DEBUG_INFO_BTF_MODULES
438	help
439	For modules whose split BTF does not match vmlinux, load without
440	BTF rather than refusing to load. The default behavior with
441	module BTF enabled is to reject modules with such mismatches;
442	this option will still load module BTF where possible but ignore
443	it when a mismatch is found.
444
445	config GDB_SCRIPTS
446	bool "Provide GDB scripts for kernel debugging"
447	help
448	This creates the required links to GDB helper scripts in the
449	build directory. If you load vmlinux into gdb, the helper
450	scripts will be automatically imported by gdb as well, and
451	additional functions are available to analyze a Linux kernel
452	instance. See Documentation/process/debugging/gdb-kernel-debugging.rst
453	for further details.
454
455	endif # DEBUG_INFO
456
457	config FRAME_WARN
458	int "Warn for stack frames larger than"
459	range 0 8192
460	default 0 if KMSAN
461	default 2048 if GCC_PLUGIN_LATENT_ENTROPY
462	default 2048 if PARISC
463	default 1536 if (!64BIT && XTENSA)
464	default 1280 if !64BIT
465	default 2048 if 64BIT
466	help
467	Tell the compiler to warn at build time for stack frames larger than this.
468	Setting this too low will cause a lot of warnings.
469	Setting it to 0 disables the warning.
470
471	config STRIP_ASM_SYMS
472	bool "Strip assembler-generated symbols during link"
473	default n
474	help
475	Strip internal assembler-generated symbols during a link (symbols
476	that look like '.Lxxx') so they don't pollute the output of
477	get_wchan() and suchlike.
478
479	config READABLE_ASM
480	bool "Generate readable assembler code"
481	depends on DEBUG_KERNEL
482	depends on CC_IS_GCC
483	help
484	Disable some compiler optimizations that tend to generate human unreadable
485	assembler output. This may make the kernel slightly slower, but it helps
486	to keep kernel developers who have to stare a lot at assembler listings
487	sane.
488
489	config HEADERS_INSTALL
490	bool "Install uapi headers to usr/include"
491	help
492	This option will install uapi headers (headers exported to user-space)
493	into the usr/include directory for use during the kernel build.
494	This is unneeded for building the kernel itself, but needed for some
495	user-space program samples. It is also needed by some features such
496	as uapi header sanity checks.
497
498	config DEBUG_SECTION_MISMATCH
499	bool "Enable full Section mismatch analysis"
500	depends on CC_IS_GCC
501	help
502	The section mismatch analysis checks if there are illegal references
503	from one section to another. During linktime or runtime, some
504	sections are dropped; any use of code/data previously in these
505	sections would most likely result in an oops.
506
507	In the code, functions and variables are annotated with __init,
508	__initdata, and so on (see the full list in include/linux/init.h).
509	This directs the toolchain to place code/data in specific sections.
510
511	The section mismatch analysis is always performed after a full
512	kernel build, and enabling this option causes the option
513	-fno-inline-functions-called-once to be added to gcc commands.
514
515	However, when inlining a function annotated with __init in
516	a non-init function, we would lose the section information and thus
517	the analysis would not catch the illegal reference. This option
518	tells gcc to inline less (but it does result in a larger kernel).
519
520	config SECTION_MISMATCH_WARN_ONLY
521	bool "Make section mismatch errors non-fatal"
522	default y
523	help
524	If you say N here, the build process will fail if there are any
525	section mismatch, instead of just throwing warnings.
526
527	If unsure, say Y.
528
529	config DEBUG_FORCE_FUNCTION_ALIGN_64B
530	bool "Force all function address 64B aligned"
531	depends on EXPERT && (X86_64 \|\| ARM64 \|\| PPC32 \|\| PPC64 \|\| ARC \|\| RISCV \|\| S390)
532	select FUNCTION_ALIGNMENT_64B
533	help
534	There are cases that a commit from one domain changes the function
535	address alignment of other domains, and cause magic performance
536	bump (regression or improvement). Enable this option will help to
537	verify if the bump is caused by function alignment changes, while
538	it will slightly increase the kernel size and affect icache usage.
539
540	It is mainly for debug and performance tuning use.
541
542	#
543	# Select this config option from the architecture Kconfig, if it
544	# is preferred to always offer frame pointers as a config
545	# option on the architecture (regardless of KERNEL_DEBUG):
546	#
547	config ARCH_WANT_FRAME_POINTERS
548	bool
549
550	config FRAME_POINTER
551	bool "Compile the kernel with frame pointers"
552	depends on DEBUG_KERNEL && (M68K \|\| UML \|\| SUPERH) \|\| ARCH_WANT_FRAME_POINTERS
553	default y if (DEBUG_INFO && UML) \|\| ARCH_WANT_FRAME_POINTERS
554	help
555	If you say Y here the resulting kernel image will be slightly
556	larger and slower, but it gives very useful debugging information
557	in case of kernel bugs. (precise oopses/stacktraces/warnings)
558
559	config OBJTOOL
560	bool
561
562	config OBJTOOL_WERROR
563	bool "Upgrade objtool warnings to errors"
564	depends on OBJTOOL && !COMPILE_TEST
565	help
566	Fail the build on objtool warnings.
567
568	Objtool warnings can indicate kernel instability, including boot
569	failures. This option is highly recommended.
570
571	If unsure, say Y.
572
573	config STACK_VALIDATION
574	bool "Compile-time stack metadata validation"
575	depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER
576	select OBJTOOL
577	default n
578	help
579	Validate frame pointer rules at compile-time. This helps ensure that
580	runtime stack traces are more reliable.
581
582	For more information, see
583	tools/objtool/Documentation/objtool.txt.
584
585	config NOINSTR_VALIDATION
586	bool
587	depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY
588	select OBJTOOL
589	default y
590
591	config VMLINUX_MAP
592	bool "Generate vmlinux.map file when linking"
593	depends on EXPERT
594	help
595	Selecting this option will pass "-Map=vmlinux.map" to ld
596	when linking vmlinux. That file can be useful for verifying
597	and debugging magic section games, and for seeing which
598	pieces of code get eliminated with
599	CONFIG_LD_DEAD_CODE_DATA_ELIMINATION.
600
601	config BUILTIN_MODULE_RANGES
602	bool "Generate address range information for builtin modules"
603	depends on !LTO
604	depends on VMLINUX_MAP
605	help
606	When modules are built into the kernel, there will be no module name
607	associated with its symbols in /proc/kallsyms. Tracers may want to
608	identify symbols by module name and symbol name regardless of whether
609	the module is configured as loadable or not.
610
611	This option generates modules.builtin.ranges in the build tree with
612	offset ranges (per ELF section) for the module(s) they belong to.
613	It also records an anchor symbol to determine the load address of the
614	section.
615
616	config DEBUG_FORCE_WEAK_PER_CPU
617	bool "Force weak per-cpu definitions"
618	depends on DEBUG_KERNEL
619	help
620	s390 and alpha require percpu variables in modules to be
621	defined weak to work around addressing range issue which
622	puts the following two restrictions on percpu variable
623	definitions.
624
625	1. percpu symbols must be unique whether static or not
626	2. percpu variables can't be defined inside a function
627
628	To ensure that generic code follows the above rules, this
629	option forces all percpu variables to be defined as weak.
630
631	config WARN_CONTEXT_ANALYSIS
632	bool "Compiler context-analysis warnings"
633	depends on CC_IS_CLANG && CLANG_VERSION >= 220100
634	# Branch profiling re-defines "if", which messes with the compiler's
635	# ability to analyze __cond_acquires(..), resulting in false positives.
636	depends on !TRACE_BRANCH_PROFILING
637	default y
638	help
639	Context Analysis is a language extension, which enables statically
640	checking that required contexts are active (or inactive) by acquiring
641	and releasing user-definable "context locks".
642
643	Clang's name of the feature is "Thread Safety Analysis". Requires
644	Clang 22.1.0 or later.
645
646	Produces warnings by default. Select CONFIG_WERROR if you wish to
647	turn these warnings into errors.
648
649	For more details, see Documentation/dev-tools/context-analysis.rst.
650
651	config WARN_CONTEXT_ANALYSIS_ALL
652	bool "Enable context analysis for all source files"
653	depends on WARN_CONTEXT_ANALYSIS
654	depends on EXPERT && !COMPILE_TEST
655	help
656	Enable tree-wide context analysis. This is likely to produce a
657	large number of false positives - enable at your own risk.
658
659	If unsure, say N.
660
661	endmenu # "Compiler options"
662
663	menu "Generic Kernel Debugging Instruments"
664
665	config MAGIC_SYSRQ
666	bool "Magic SysRq key"
667	depends on !UML
668	help
669	If you say Y here, you will have some control over the system even
670	if the system crashes for example during kernel debugging (e.g., you
671	will be able to flush the buffer cache to disk, reboot the system
672	immediately or dump some status information). This is accomplished
673	by pressing various keys while holding SysRq (Alt+PrintScreen). It
674	also works on a serial console (on PC hardware at least), if you
675	send a BREAK and then within 5 seconds a command keypress. The
676	keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
677	Don't say Y unless you really know what this hack does.
678
679	config MAGIC_SYSRQ_DEFAULT_ENABLE
680	hex "Enable magic SysRq key functions by default"
681	depends on MAGIC_SYSRQ
682	default 0x1
683	help
684	Specifies which SysRq key functions are enabled by default.
685	This may be set to 1 or 0 to enable or disable them all, or
686	to a bitmask as described in Documentation/admin-guide/sysrq.rst.
687
688	config MAGIC_SYSRQ_SERIAL
689	bool "Enable magic SysRq key over serial"
690	depends on MAGIC_SYSRQ
691	default y
692	help
693	Many embedded boards have a disconnected TTL level serial which can
694	generate some garbage that can lead to spurious false sysrq detects.
695	This option allows you to decide whether you want to enable the
696	magic SysRq key.
697
698	config MAGIC_SYSRQ_SERIAL_SEQUENCE
699	string "Char sequence that enables magic SysRq over serial"
700	depends on MAGIC_SYSRQ_SERIAL
701	default ""
702	help
703	Specifies a sequence of characters that can follow BREAK to enable
704	SysRq on a serial console.
705
706	If unsure, leave an empty string and the option will not be enabled.
707
708	config DEBUG_FS
709	bool "Debug Filesystem"
710	help
711	debugfs is a virtual file system that kernel developers use to put
712	debugging files into. Enable this option to be able to read and
713	write to these files.
714
715	For detailed documentation on the debugfs API, see
716	Documentation/filesystems/.
717
718	If unsure, say N.
719
720	choice
721	prompt "Debugfs default access"
722	depends on DEBUG_FS
723	default DEBUG_FS_ALLOW_ALL
724	help
725	This selects the default access restrictions for debugfs.
726	It can be overridden with kernel command line option
727	debugfs=[on,off]. The restrictions apply for API access
728	and filesystem registration.
729
730	config DEBUG_FS_ALLOW_ALL
731	bool "Access normal"
732	help
733	No restrictions apply. Both API and filesystem registration
734	is on. This is the normal default operation.
735
736	config DEBUG_FS_ALLOW_NONE
737	bool "No access"
738	help
739	Access is off. Clients get -PERM when trying to create nodes in
740	debugfs tree and debugfs is not registered as a filesystem.
741	Client can then back-off or continue without debugfs access.
742
743	endchoice
744
745	source "lib/Kconfig.kgdb"
746	source "lib/Kconfig.ubsan"
747	source "lib/Kconfig.kcsan"
748
749	endmenu
750
751	menu "Networking Debugging"
752
753	source "net/Kconfig.debug"
754
755	endmenu # "Networking Debugging"
756
757	menu "Memory Debugging"
758
759	source "mm/Kconfig.debug"
760
761	config DEBUG_OBJECTS
762	bool "Debug object operations"
763	depends on PREEMPT_COUNT \|\| !DEFERRED_STRUCT_PAGE_INIT
764	depends on DEBUG_KERNEL
765	help
766	If you say Y here, additional code will be inserted into the
767	kernel to track the life time of various objects and validate
768	the operations on those objects.
769
770	config DEBUG_OBJECTS_SELFTEST
771	bool "Debug objects selftest"
772	depends on DEBUG_OBJECTS
773	help
774	This enables the selftest of the object debug code.
775
776	config DEBUG_OBJECTS_FREE
777	bool "Debug objects in freed memory"
778	depends on DEBUG_OBJECTS
779	help
780	This enables checks whether a k/v free operation frees an area
781	which contains an object which has not been deactivated
782	properly. This can make kmalloc/kfree-intensive workloads
783	much slower.
784
785	config DEBUG_OBJECTS_TIMERS
786	bool "Debug timer objects"
787	depends on DEBUG_OBJECTS
788	help
789	If you say Y here, additional code will be inserted into the
790	timer routines to track the life time of timer objects and
791	validate the timer operations.
792
793	config DEBUG_OBJECTS_WORK
794	bool "Debug work objects"
795	depends on DEBUG_OBJECTS
796	help
797	If you say Y here, additional code will be inserted into the
798	work queue routines to track the life time of work objects and
799	validate the work operations.
800
801	config DEBUG_OBJECTS_RCU_HEAD
802	bool "Debug RCU callbacks objects"
803	depends on DEBUG_OBJECTS
804	help
805	Enable this to turn on debugging of RCU list heads (call_rcu() usage).
806
807	config DEBUG_OBJECTS_PERCPU_COUNTER
808	bool "Debug percpu counter objects"
809	depends on DEBUG_OBJECTS
810	help
811	If you say Y here, additional code will be inserted into the
812	percpu counter routines to track the life time of percpu counter
813	objects and validate the percpu counter operations.
814
815	config DEBUG_OBJECTS_ENABLE_DEFAULT
816	int "debug_objects bootup default value (0-1)"
817	range 0 1
818	default "1"
819	depends on DEBUG_OBJECTS
820	help
821	Debug objects boot parameter default value
822
823	config SHRINKER_DEBUG
824	bool "Enable shrinker debugging support"
825	depends on DEBUG_FS
826	help
827	Say Y to enable the shrinker debugfs interface which provides
828	visibility into the kernel memory shrinkers subsystem.
829	Disable it to avoid an extra memory footprint.
830
831	config DEBUG_STACK_USAGE
832	bool "Stack utilization instrumentation"
833	depends on DEBUG_KERNEL
834	help
835	Enables the display of the minimum amount of free stack which each
836	task has ever had available in the sysrq-T and sysrq-P debug output.
837	Also emits a message to dmesg when a process exits if that process
838	used more stack space than previously exiting processes.
839
840	This option will slow down process creation somewhat.
841
842	config SCHED_STACK_END_CHECK
843	bool "Detect stack corruption on calls to schedule()"
844	depends on DEBUG_KERNEL
845	default n
846	help
847	This option checks for a stack overrun on calls to schedule().
848	If the stack end location is found to be over written always panic as
849	the content of the corrupted region can no longer be trusted.
850	This is to ensure no erroneous behaviour occurs which could result in
851	data corruption or a sporadic crash at a later stage once the region
852	is examined. The runtime overhead introduced is minimal.
853
854	config ARCH_HAS_DEBUG_VM_PGTABLE
855	bool
856	help
857	An architecture should select this when it can successfully
858	build and run DEBUG_VM_PGTABLE.
859
860	config DEBUG_VFS
861	bool "Debug VFS"
862	depends on DEBUG_KERNEL
863	help
864	Enable this to turn on extended checks in the VFS layer that may impact
865	performance.
866
867	If unsure, say N.
868
869	config DEBUG_VM_IRQSOFF
870	def_bool DEBUG_VM && !PREEMPT_RT
871
872	config DEBUG_VM
873	bool "Debug VM"
874	depends on DEBUG_KERNEL
875	help
876	Enable this to turn on extended checks in the virtual-memory system
877	that may impact performance.
878
879	If unsure, say N.
880
881	config DEBUG_VM_SHOOT_LAZIES
882	bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation"
883	depends on DEBUG_VM
884	depends on MMU_LAZY_TLB_SHOOTDOWN
885	help
886	Enable additional IPIs that ensure lazy tlb mm references are removed
887	before the mm is freed.
888
889	If unsure, say N.
890
891	config DEBUG_VM_MAPLE_TREE
892	bool "Debug VM maple trees"
893	depends on DEBUG_VM
894	select DEBUG_MAPLE_TREE
895	help
896	Enable VM maple tree debugging information and extra validations.
897
898	If unsure, say N.
899
900	config DEBUG_VM_RB
901	bool "Debug VM red-black trees"
902	depends on DEBUG_VM
903	help
904	Enable VM red-black tree debugging information and extra validations.
905
906	If unsure, say N.
907
908	config DEBUG_VM_PGFLAGS
909	bool "Debug page-flags operations"
910	depends on DEBUG_VM
911	help
912	Enables extra validation on page flags operations.
913
914	If unsure, say N.
915
916	config DEBUG_VM_PGTABLE
917	bool "Debug arch page table for semantics compliance"
918	depends on MMU
919	depends on ARCH_HAS_DEBUG_VM_PGTABLE
920	default y if DEBUG_VM
921	help
922	This option provides a debug method which can be used to test
923	architecture page table helper functions on various platforms in
924	verifying if they comply with expected generic MM semantics. This
925	will help architecture code in making sure that any changes or
926	new additions of these helpers still conform to expected
927	semantics of the generic MM. Platforms will have to opt in for
928	this through ARCH_HAS_DEBUG_VM_PGTABLE.
929
930	If unsure, say N.
931
932	config ARCH_HAS_DEBUG_VIRTUAL
933	bool
934
935	config DEBUG_VIRTUAL
936	bool "Debug VM translations"
937	depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
938	help
939	Enable some costly sanity checks in virtual to page code. This can
940	catch mistakes with virt_to_page() and friends.
941
942	If unsure, say N.
943
944	config DEBUG_NOMMU_REGIONS
945	bool "Debug the global anon/private NOMMU mapping region tree"
946	depends on DEBUG_KERNEL && !MMU
947	help
948	This option causes the global tree of anonymous and private mapping
949	regions to be regularly checked for invalid topology.
950
951	config DEBUG_MEMORY_INIT
952	bool "Debug memory initialisation" if EXPERT
953	default !EXPERT
954	help
955	Enable this for additional checks during memory initialisation.
956	The sanity checks verify aspects of the VM such as the memory model
957	and other information provided by the architecture. Verbose
958	information will be printed at KERN_DEBUG loglevel depending
959	on the mminit_loglevel= command-line option.
960
961	If unsure, say Y
962
963	config MEMORY_NOTIFIER_ERROR_INJECT
964	tristate "Memory hotplug notifier error injection module"
965	depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION
966	help
967	This option provides the ability to inject artificial errors to
968	memory hotplug notifier chain callbacks. It is controlled through
969	debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
970
971	If the notifier call chain should be failed with some events
972	notified, write the error code to "actions/<notifier event>/error".
973
974	Example: Inject memory hotplug offline error (-12 == -ENOMEM)
975
976	# cd /sys/kernel/debug/notifier-error-inject/memory
977	# echo -12 > actions/MEM_GOING_OFFLINE/error
978	# echo offline > /sys/devices/system/memory/memoryXXX/state
979	bash: echo: write error: Cannot allocate memory
980
981	To compile this code as a module, choose M here: the module will
982	be called memory-notifier-error-inject.
983
984	If unsure, say N.
985
986	config DEBUG_PER_CPU_MAPS
987	bool "Debug access to per_cpu maps"
988	depends on DEBUG_KERNEL
989	depends on SMP
990	help
991	Say Y to verify that the per_cpu map being accessed has
992	been set up. This adds a fair amount of code to kernel memory
993	and decreases performance.
994
995	Say N if unsure.
996
997	config DEBUG_KMAP_LOCAL
998	bool "Debug kmap_local temporary mappings"
999	depends on DEBUG_KERNEL && KMAP_LOCAL
1000	help
1001	This option enables additional error checking for the kmap_local
1002	infrastructure. Disable for production use.
1003
1004	config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
1005	bool
1006
1007	config DEBUG_KMAP_LOCAL_FORCE_MAP
1008	bool "Enforce kmap_local temporary mappings"
1009	depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
1010	select KMAP_LOCAL
1011	select DEBUG_KMAP_LOCAL
1012	help
1013	This option enforces temporary mappings through the kmap_local
1014	mechanism for non-highmem pages and on non-highmem systems.
1015	Disable this for production systems!
1016
1017	config DEBUG_HIGHMEM
1018	bool "Highmem debugging"
1019	depends on DEBUG_KERNEL && HIGHMEM
1020	select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
1021	select DEBUG_KMAP_LOCAL
1022	help
1023	This option enables additional error checking for high memory
1024	systems. Disable for production systems.
1025
1026	config HAVE_DEBUG_STACKOVERFLOW
1027	bool
1028
1029	config DEBUG_STACKOVERFLOW
1030	bool "Check for stack overflows"
1031	depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
1032	help
1033	Say Y here if you want to check for overflows of kernel, IRQ
1034	and exception stacks (if your architecture uses them). This
1035	option will show detailed messages if free stack space drops
1036	below a certain limit.
1037
1038	These kinds of bugs usually occur when call-chains in the
1039	kernel get too deep, especially when interrupts are
1040	involved.
1041
1042	Use this in cases where you see apparently random memory
1043	corruption, especially if it appears in 'struct thread_info'
1044
1045	If in doubt, say "N".
1046
1047	config CODE_TAGGING
1048	bool
1049	select KALLSYMS
1050
1051	config MEM_ALLOC_PROFILING
1052	bool "Enable memory allocation profiling"
1053	default n
1054	depends on MMU
1055	depends on PROC_FS
1056	depends on !DEBUG_FORCE_WEAK_PER_CPU
1057	select CODE_TAGGING
1058	select PAGE_EXTENSION
1059	select SLAB_OBJ_EXT
1060	help
1061	Track allocation source code and record total allocation size
1062	initiated at that code location. The mechanism can be used to track
1063	memory leaks with a low performance and memory impact.
1064
1065	config MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT
1066	bool "Enable memory allocation profiling by default"
1067	default y
1068	depends on MEM_ALLOC_PROFILING
1069
1070	config MEM_ALLOC_PROFILING_DEBUG
1071	bool "Memory allocation profiler debugging"
1072	default n
1073	depends on MEM_ALLOC_PROFILING
1074	select MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT
1075	help
1076	Adds warnings with helpful error messages for memory allocation
1077	profiling.
1078
1079	source "lib/Kconfig.kasan"
1080	source "lib/Kconfig.kfence"
1081	source "lib/Kconfig.kmsan"
1082
1083	endmenu # "Memory Debugging"
1084
1085	config DEBUG_SHIRQ
1086	bool "Debug shared IRQ handlers"
1087	depends on DEBUG_KERNEL
1088	help
1089	Enable this to generate a spurious interrupt just before a shared
1090	interrupt handler is deregistered (generating one when registering
1091	is currently disabled). Drivers need to handle this correctly. Some
1092	don't and need to be caught.
1093
1094	menu "Debug Oops, Lockups and Hangs"
1095
1096	config PANIC_ON_OOPS
1097	bool "Panic on Oops"
1098	help
1099	Say Y here to enable the kernel to panic when it oopses. This
1100	has the same effect as setting oops=panic on the kernel command
1101	line.
1102
1103	This feature is useful to ensure that the kernel does not do
1104	anything erroneous after an oops which could result in data
1105	corruption or other issues.
1106
1107	Say N if unsure.
1108
1109	config PANIC_TIMEOUT
1110	int "panic timeout"
1111	default 0
1112	help
1113	Set the timeout value (in seconds) until a reboot occurs when
1114	the kernel panics. If n = 0, then we wait forever. A timeout
1115	value n > 0 will wait n seconds before rebooting, while a timeout
1116	value n < 0 will reboot immediately. This setting can be overridden
1117	with the kernel command line option panic=, and from userspace via
1118	/proc/sys/kernel/panic.
1119
1120	config LOCKUP_DETECTOR
1121	bool
1122
1123	config SOFTLOCKUP_DETECTOR
1124	bool "Detect Soft Lockups"
1125	depends on DEBUG_KERNEL && !S390
1126	select LOCKUP_DETECTOR
1127	help
1128	Say Y here to enable the kernel to act as a watchdog to detect
1129	soft lockups.
1130
1131	Softlockups are bugs that cause the kernel to loop in kernel
1132	mode for more than 20 seconds, without giving other tasks a
1133	chance to run. The current stack trace is displayed upon
1134	detection and the system will stay locked up.
1135
1136	config SOFTLOCKUP_DETECTOR_INTR_STORM
1137	bool "Detect Interrupt Storm in Soft Lockups"
1138	depends on SOFTLOCKUP_DETECTOR && IRQ_TIME_ACCOUNTING
1139	select GENERIC_IRQ_STAT_SNAPSHOT
1140	default y if NR_CPUS <= 128
1141	help
1142	Say Y here to enable the kernel to detect interrupt storm
1143	during "soft lockups".
1144
1145	"soft lockups" can be caused by a variety of reasons. If one is
1146	caused by an interrupt storm, then the storming interrupts will not
1147	be on the callstack. To detect this case, it is necessary to report
1148	the CPU stats and the interrupt counts during the "soft lockups".
1149
1150	config BOOTPARAM_SOFTLOCKUP_PANIC
1151	int "Panic (Reboot) On Soft Lockups"
1152	depends on SOFTLOCKUP_DETECTOR
1153	default 0
1154	help
1155	Set to a non-zero value N to enable the kernel to panic on "soft
1156	lockups", which are bugs that cause the kernel to loop in kernel
1157	mode for more than (N * 20 seconds) (configurable using the
1158	watchdog_thresh sysctl), without giving other tasks a chance to run.
1159
1160	The panic can be used in combination with panic_timeout,
1161	to cause the system to reboot automatically after a
1162	lockup has been detected. This feature is useful for
1163	high-availability systems that have uptime guarantees and
1164	where a lockup must be resolved ASAP.
1165
1166	Say 0 if unsure.
1167
1168	config HAVE_HARDLOCKUP_DETECTOR_BUDDY
1169	bool
1170	depends on SMP
1171	default y
1172
1173	#
1174	# Global switch whether to build a hardlockup detector at all. It is available
1175	# only when the architecture supports at least one implementation. There are
1176	# two exceptions. The hardlockup detector is never enabled on:
1177	#
1178	# s390: it reported many false positives there
1179	#
1180	# sparc64: has a custom implementation which is not using the common
1181	# hardlockup command line options and sysctl interface.
1182	#
1183	config HARDLOCKUP_DETECTOR
1184	bool "Detect Hard Lockups"
1185	depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64
1186	depends on HAVE_HARDLOCKUP_DETECTOR_PERF \|\| HAVE_HARDLOCKUP_DETECTOR_BUDDY \|\| HAVE_HARDLOCKUP_DETECTOR_ARCH
1187	imply HARDLOCKUP_DETECTOR_PERF
1188	imply HARDLOCKUP_DETECTOR_BUDDY
1189	imply HARDLOCKUP_DETECTOR_ARCH
1190	select LOCKUP_DETECTOR
1191
1192	help
1193	Say Y here to enable the kernel to act as a watchdog to detect
1194	hard lockups.
1195
1196	Hardlockups are bugs that cause the CPU to loop in kernel mode
1197	for more than 10 seconds, without letting other interrupts have a
1198	chance to run. The current stack trace is displayed upon detection
1199	and the system will stay locked up.
1200
1201	#
1202	# Note that arch-specific variants are always preferred.
1203	#
1204	config HARDLOCKUP_DETECTOR_PREFER_BUDDY
1205	bool "Prefer the buddy CPU hardlockup detector"
1206	depends on HARDLOCKUP_DETECTOR
1207	depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY
1208	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1209	help
1210	Say Y here to prefer the buddy hardlockup detector over the perf one.
1211
1212	With the buddy detector, each CPU uses its softlockup hrtimer
1213	to check that the next CPU is processing hrtimer interrupts by
1214	verifying that a counter is increasing.
1215
1216	This hardlockup detector is useful on systems that don't have
1217	an arch-specific hardlockup detector or if resources needed
1218	for the hardlockup detector are better used for other things.
1219
1220	config HARDLOCKUP_DETECTOR_PERF
1221	bool
1222	depends on HARDLOCKUP_DETECTOR
1223	depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY
1224	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1225	select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1226
1227	config HARDLOCKUP_DETECTOR_BUDDY
1228	bool
1229	depends on HARDLOCKUP_DETECTOR
1230	depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY
1231	depends on !HAVE_HARDLOCKUP_DETECTOR_PERF \|\| HARDLOCKUP_DETECTOR_PREFER_BUDDY
1232	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1233	select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1234
1235	config HARDLOCKUP_DETECTOR_ARCH
1236	bool
1237	depends on HARDLOCKUP_DETECTOR
1238	depends on HAVE_HARDLOCKUP_DETECTOR_ARCH
1239	help
1240	The arch-specific implementation of the hardlockup detector will
1241	be used.
1242
1243	#
1244	# Both the "perf" and "buddy" hardlockup detectors count hrtimer
1245	# interrupts. This config enables functions managing this common code.
1246	#
1247	config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1248	bool
1249	select SOFTLOCKUP_DETECTOR
1250
1251	#
1252	# Enables a timestamp based low pass filter to compensate for perf based
1253	# hard lockup detection which runs too fast due to turbo modes.
1254	#
1255	config HARDLOCKUP_CHECK_TIMESTAMP
1256	bool
1257
1258	config BOOTPARAM_HARDLOCKUP_PANIC
1259	bool "Panic (Reboot) On Hard Lockups"
1260	depends on HARDLOCKUP_DETECTOR
1261	help
1262	Say Y here to enable the kernel to panic on "hard lockups",
1263	which are bugs that cause the kernel to loop in kernel
1264	mode with interrupts disabled for more than 10 seconds (configurable
1265	using the watchdog_thresh sysctl).
1266
1267	Say N if unsure.
1268
1269	config DETECT_HUNG_TASK
1270	bool "Detect Hung Tasks"
1271	depends on DEBUG_KERNEL
1272	default SOFTLOCKUP_DETECTOR
1273	help
1274	Say Y here to enable the kernel to detect "hung tasks",
1275	which are bugs that cause the task to be stuck in
1276	uninterruptible "D" state indefinitely.
1277
1278	When a hung task is detected, the kernel will print the
1279	current stack trace (which you should report), but the
1280	task will stay in uninterruptible state. If lockdep is
1281	enabled then all held locks will also be reported. This
1282	feature has negligible overhead.
1283
1284	config DEFAULT_HUNG_TASK_TIMEOUT
1285	int "Default timeout for hung task detection (in seconds)"
1286	depends on DETECT_HUNG_TASK
1287	default 120
1288	help
1289	This option controls the default timeout (in seconds) used
1290	to determine when a task has become non-responsive and should
1291	be considered hung.
1292
1293	It can be adjusted at runtime via the kernel.hung_task_timeout_secs
1294	sysctl or by writing a value to
1295	/proc/sys/kernel/hung_task_timeout_secs.
1296
1297	A timeout of 0 disables the check. The default is two minutes.
1298	Keeping the default should be fine in most cases.
1299
1300	config BOOTPARAM_HUNG_TASK_PANIC
1301	int "Number of hung tasks to trigger kernel panic"
1302	depends on DETECT_HUNG_TASK
1303	default 0
1304	help
1305	When set to a non-zero value, a kernel panic will be triggered
1306	if the number of hung tasks found during a single scan reaches
1307	this value.
1308
1309	The panic can be used in combination with panic_timeout,
1310	to cause the system to reboot automatically after a
1311	hung task has been detected. This feature is useful for
1312	high-availability systems that have uptime guarantees and
1313	where a hung tasks must be resolved ASAP.
1314
1315	Say 0 if unsure.
1316
1317	config DETECT_HUNG_TASK_BLOCKER
1318	bool "Dump Hung Tasks Blocker"
1319	depends on DETECT_HUNG_TASK
1320	depends on !PREEMPT_RT
1321	default y
1322	help
1323	Say Y here to show the blocker task's stacktrace who acquires
1324	the mutex lock which "hung tasks" are waiting.
1325	This will add overhead a bit but shows suspicious tasks and
1326	call trace if it comes from waiting a mutex.
1327
1328	config WQ_WATCHDOG
1329	bool "Detect Workqueue Stalls"
1330	depends on DEBUG_KERNEL
1331	help
1332	Say Y here to enable stall detection on workqueues. If a
1333	worker pool doesn't make forward progress on a pending work
1334	item for over a given amount of time, 30s by default, a
1335	warning message is printed along with dump of workqueue
1336	state. This can be configured through kernel parameter
1337	"workqueue.watchdog_thresh" and its sysfs counterpart.
1338
1339	config BOOTPARAM_WQ_STALL_PANIC
1340	int "Panic on Nth workqueue stall"
1341	default 0
1342	range 0 100
1343	depends on WQ_WATCHDOG
1344	help
1345	Set the number of workqueue stalls to trigger a kernel panic.
1346	A workqueue stall occurs when a worker pool doesn't make forward
1347	progress on a pending work item for over 30 seconds (configurable
1348	using the workqueue.watchdog_thresh parameter).
1349
1350	If n = 0, the kernel will not panic on stall. If n > 0, the kernel
1351	will panic after n stall warnings.
1352
1353	The panic can be used in combination with panic_timeout,
1354	to cause the system to reboot automatically after a
1355	stall has been detected. This feature is useful for
1356	high-availability systems that have uptime guarantees and
1357	where a stall must be resolved ASAP.
1358
1359	This setting can be overridden at runtime via the
1360	workqueue.panic_on_stall kernel parameter.
1361
1362	config WQ_CPU_INTENSIVE_REPORT
1363	bool "Report per-cpu work items which hog CPU for too long"
1364	depends on DEBUG_KERNEL
1365	help
1366	Say Y here to enable reporting of concurrency-managed per-cpu work
1367	items that hog CPUs for longer than
1368	workqueue.cpu_intensive_thresh_us. Workqueue automatically
1369	detects and excludes them from concurrency management to prevent
1370	them from stalling other per-cpu work items. Occassional
1371	triggering may not necessarily indicate a problem. Repeated
1372	triggering likely indicates that the work item should be switched
1373	to use an unbound workqueue.
1374
1375	config TEST_LOCKUP
1376	tristate "Test module to generate lockups"
1377	depends on m
1378	help
1379	This builds the "test_lockup" module that helps to make sure
1380	that watchdogs and lockup detectors are working properly.
1381
1382	Depending on module parameters it could emulate soft or hard
1383	lockup, "hung task", or locking arbitrary lock for a long time.
1384	Also it could generate series of lockups with cooling-down periods.
1385
1386	If unsure, say N.
1387
1388	endmenu # "Debug lockups and hangs"
1389
1390	menu "Scheduler Debugging"
1391
1392	config SCHED_INFO
1393	bool
1394	default n
1395
1396	config SCHEDSTATS
1397	bool "Collect scheduler statistics"
1398	depends on PROC_FS
1399	select SCHED_INFO
1400	help
1401	If you say Y here, additional code will be inserted into the
1402	scheduler and related routines to collect statistics about
1403	scheduler behavior and provide them in /proc/schedstat. These
1404	stats may be useful for both tuning and debugging the scheduler
1405	If you aren't debugging the scheduler or trying to tune a specific
1406	application, you can say N to avoid the very slight overhead
1407	this adds.
1408
1409	endmenu
1410
1411	config DEBUG_PREEMPT
1412	bool "Debug preemptible kernel"
1413	depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT
1414	help
1415	If you say Y here then the kernel will use a debug variant of the
1416	commonly used smp_processor_id() function and will print warnings
1417	if kernel code uses it in a preemption-unsafe way. Also, the kernel
1418	will detect preemption count underflows.
1419
1420	This option has potential to introduce high runtime overhead,
1421	depending on workload as it triggers debugging routines for each
1422	this_cpu operation. It should only be used for debugging purposes.
1423
1424	config DEBUG_ATOMIC
1425	bool "Debug atomic variables"
1426	depends on DEBUG_KERNEL
1427	help
1428	If you say Y here then the kernel will add a runtime alignment check
1429	to atomic accesses. Useful for architectures that do not have trap on
1430	mis-aligned access.
1431
1432	This option has potentially significant overhead.
1433
1434	config DEBUG_ATOMIC_LARGEST_ALIGN
1435	bool "Check alignment only up to __aligned_largest"
1436	depends on DEBUG_ATOMIC
1437	help
1438	If you say Y here then the check for natural alignment of
1439	atomic accesses will be constrained to the compiler's largest
1440	alignment for scalar types.
1441
1442	menu "Lock Debugging (spinlocks, mutexes, etc...)"
1443
1444	config LOCK_DEBUGGING_SUPPORT
1445	bool
1446	depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1447	default y
1448
1449	config PROVE_LOCKING
1450	bool "Lock debugging: prove locking correctness"
1451	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1452	select LOCKDEP
1453	select DEBUG_SPINLOCK
1454	select DEBUG_MUTEXES if !PREEMPT_RT
1455	select DEBUG_RT_MUTEXES if RT_MUTEXES
1456	select DEBUG_RWSEMS if !PREEMPT_RT
1457	select DEBUG_WW_MUTEX_SLOWPATH
1458	select DEBUG_LOCK_ALLOC
1459	select PREEMPT_COUNT if !ARCH_NO_PREEMPT
1460	select TRACE_IRQFLAGS
1461	default n
1462	help
1463	This feature enables the kernel to prove that all locking
1464	that occurs in the kernel runtime is mathematically
1465	correct: that under no circumstance could an arbitrary (and
1466	not yet triggered) combination of observed locking
1467	sequences (on an arbitrary number of CPUs, running an
1468	arbitrary number of tasks and interrupt contexts) cause a
1469	deadlock.
1470
1471	In short, this feature enables the kernel to report locking
1472	related deadlocks before they actually occur.
1473
1474	The proof does not depend on how hard and complex a
1475	deadlock scenario would be to trigger: how many
1476	participant CPUs, tasks and irq-contexts would be needed
1477	for it to trigger. The proof also does not depend on
1478	timing: if a race and a resulting deadlock is possible
1479	theoretically (no matter how unlikely the race scenario
1480	is), it will be proven so and will immediately be
1481	reported by the kernel (once the event is observed that
1482	makes the deadlock theoretically possible).
1483
1484	If a deadlock is impossible (i.e. the locking rules, as
1485	observed by the kernel, are mathematically correct), the
1486	kernel reports nothing.
1487
1488	NOTE: this feature can also be enabled for rwlocks, mutexes
1489	and rwsems - in which case all dependencies between these
1490	different locking variants are observed and mapped too, and
1491	the proof of observed correctness is also maintained for an
1492	arbitrary combination of these separate locking variants.
1493
1494	For more details, see Documentation/locking/lockdep-design.rst.
1495
1496	config PROVE_RAW_LOCK_NESTING
1497	bool "Enable raw_spinlock - spinlock nesting checks" if !ARCH_SUPPORTS_RT
1498	depends on PROVE_LOCKING
1499	default y if ARCH_SUPPORTS_RT
1500	help
1501	Enable the raw_spinlock vs. spinlock nesting checks which ensure
1502	that the lock nesting rules for PREEMPT_RT enabled kernels are
1503	not violated.
1504
1505	config LOCK_STAT
1506	bool "Lock usage statistics"
1507	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1508	select LOCKDEP
1509	select DEBUG_SPINLOCK
1510	select DEBUG_MUTEXES if !PREEMPT_RT
1511	select DEBUG_RT_MUTEXES if RT_MUTEXES
1512	select DEBUG_LOCK_ALLOC
1513	default n
1514	help
1515	This feature enables tracking lock contention points
1516
1517	For more details, see Documentation/locking/lockstat.rst
1518
1519	This also enables lock events required by "perf lock",
1520	subcommand of perf.
1521	If you want to use "perf lock", you also need to turn on
1522	CONFIG_EVENT_TRACING.
1523
1524	CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1525	(CONFIG_LOCKDEP defines "acquire" and "release" events.)
1526
1527	config DEBUG_RT_MUTEXES
1528	bool "RT Mutex debugging, deadlock detection"
1529	depends on DEBUG_KERNEL && RT_MUTEXES
1530	help
1531	This allows rt mutex semantics violations and rt mutex related
1532	deadlocks (lockups) to be detected and reported automatically.
1533
1534	config DEBUG_SPINLOCK
1535	bool "Spinlock and rw-lock debugging: basic checks"
1536	depends on DEBUG_KERNEL
1537	select UNINLINE_SPIN_UNLOCK
1538	help
1539	Say Y here and build SMP to catch missing spinlock initialization
1540	and certain other kinds of spinlock errors commonly made. This is
1541	best used in conjunction with the NMI watchdog so that spinlock
1542	deadlocks are also debuggable.
1543
1544	config DEBUG_MUTEXES
1545	bool "Mutex debugging: basic checks"
1546	depends on DEBUG_KERNEL && !PREEMPT_RT
1547	help
1548	This feature allows mutex semantics violations to be detected and
1549	reported.
1550
1551	config DEBUG_WW_MUTEX_SLOWPATH
1552	bool "Wait/wound mutex debugging: Slowpath testing"
1553	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1554	select DEBUG_LOCK_ALLOC
1555	select DEBUG_SPINLOCK
1556	select DEBUG_MUTEXES if !PREEMPT_RT
1557	select DEBUG_RT_MUTEXES if PREEMPT_RT
1558	help
1559	This feature enables slowpath testing for w/w mutex users by
1560	injecting additional -EDEADLK wound/backoff cases. Together with
1561	the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1562	will test all possible w/w mutex interface abuse with the
1563	exception of simply not acquiring all the required locks.
1564	Note that this feature can introduce significant overhead, so
1565	it really should not be enabled in a production or distro kernel,
1566	even a debug kernel. If you are a driver writer, enable it. If
1567	you are a distro, do not.
1568
1569	config DEBUG_RWSEMS
1570	bool "RW Semaphore debugging: basic checks"
1571	depends on DEBUG_KERNEL && !PREEMPT_RT
1572	help
1573	This debugging feature allows mismatched rw semaphore locks
1574	and unlocks to be detected and reported.
1575
1576	config DEBUG_LOCK_ALLOC
1577	bool "Lock debugging: detect incorrect freeing of live locks"
1578	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1579	select DEBUG_SPINLOCK
1580	select DEBUG_MUTEXES if !PREEMPT_RT
1581	select DEBUG_RT_MUTEXES if RT_MUTEXES
1582	select LOCKDEP
1583	help
1584	This feature will check whether any held lock (spinlock, rwlock,
1585	mutex or rwsem) is incorrectly freed by the kernel, via any of the
1586	memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1587	vfree(), etc.), whether a live lock is incorrectly reinitialized via
1588	spin_lock_init()/mutex_init()/etc., or whether there is any lock
1589	held during task exit.
1590
1591	config LOCKDEP
1592	bool
1593	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1594	select STACKTRACE
1595	select KALLSYMS
1596	select KALLSYMS_ALL
1597
1598	config LOCKDEP_SMALL
1599	bool
1600
1601	config LOCKDEP_BITS
1602	int "Size for MAX_LOCKDEP_ENTRIES (as Nth power of 2)"
1603	depends on LOCKDEP && !LOCKDEP_SMALL
1604	range 10 24
1605	default 15
1606	help
1607	Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message.
1608
1609	config LOCKDEP_CHAINS_BITS
1610	int "Size for MAX_LOCKDEP_CHAINS (as Nth power of 2)"
1611	depends on LOCKDEP && !LOCKDEP_SMALL
1612	range 10 21
1613	default 16
1614	help
1615	Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message.
1616
1617	config LOCKDEP_STACK_TRACE_BITS
1618	int "Size for MAX_STACK_TRACE_ENTRIES (as Nth power of 2)"
1619	depends on LOCKDEP && !LOCKDEP_SMALL
1620	range 10 26
1621	default 21 if KASAN
1622	default 19
1623	help
1624	Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message.
1625
1626	KASAN significantly increases stack trace consumption because its
1627	slab tracking interacts with lockdep's dependency validation under
1628	PREEMPT_FULL, creating a feedback loop. The higher default when
1629	KASAN is enabled costs ~12MB extra, which is negligible compared to
1630	KASAN's own shadow memory overhead.
1631
1632	config LOCKDEP_STACK_TRACE_HASH_BITS
1633	int "Size for STACK_TRACE_HASH_SIZE (as Nth power of 2)"
1634	depends on LOCKDEP && !LOCKDEP_SMALL
1635	range 10 26
1636	default 16 if KASAN
1637	default 14
1638	help
1639	Try increasing this value if you need large STACK_TRACE_HASH_SIZE.
1640
1641	config LOCKDEP_CIRCULAR_QUEUE_BITS
1642	int "Size for elements in circular_queue struct (as Nth power of 2)"
1643	depends on LOCKDEP
1644	range 10 26
1645	default 12
1646	help
1647	Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure.
1648
1649	config DEBUG_LOCKDEP
1650	bool "Lock dependency engine debugging"
1651	depends on DEBUG_KERNEL && LOCKDEP
1652	select DEBUG_IRQFLAGS
1653	help
1654	If you say Y here, the lock dependency engine will do
1655	additional runtime checks to debug itself, at the price
1656	of more runtime overhead.
1657
1658	config DEBUG_ATOMIC_SLEEP
1659	bool "Sleep inside atomic section checking"
1660	select PREEMPT_COUNT
1661	depends on DEBUG_KERNEL
1662	depends on !ARCH_NO_PREEMPT
1663	help
1664	If you say Y here, various routines which may sleep will become very
1665	noisy if they are called inside atomic sections: when a spinlock is
1666	held, inside an rcu read side critical section, inside preempt disabled
1667	sections, inside an interrupt, etc...
1668
1669	config DEBUG_LOCKING_API_SELFTESTS
1670	bool "Locking API boot-time self-tests"
1671	depends on DEBUG_KERNEL
1672	help
1673	Say Y here if you want the kernel to run a short self-test during
1674	bootup. The self-test checks whether common types of locking bugs
1675	are detected by debugging mechanisms or not. (if you disable
1676	lock debugging then those bugs won't be detected of course.)
1677	The following locking APIs are covered: spinlocks, rwlocks,
1678	mutexes and rwsems.
1679
1680	config LOCK_TORTURE_TEST
1681	tristate "torture tests for locking"
1682	depends on DEBUG_KERNEL
1683	select TORTURE_TEST
1684	help
1685	This option provides a kernel module that runs torture tests
1686	on kernel locking primitives. The kernel module may be built
1687	after the fact on the running kernel to be tested, if desired.
1688
1689	Say Y here if you want kernel locking-primitive torture tests
1690	to be built into the kernel.
1691	Say M if you want these torture tests to build as a module.
1692	Say N if you are unsure.
1693
1694	config WW_MUTEX_SELFTEST
1695	tristate "Wait/wound mutex selftests"
1696	help
1697	This option provides a kernel module that runs tests on the
1698	on the struct ww_mutex locking API.
1699
1700	It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1701	with this test harness.
1702
1703	Say M if you want these self tests to build as a module.
1704	Say N if you are unsure.
1705
1706	config SCF_TORTURE_TEST
1707	tristate "torture tests for smp_call_function*()"
1708	depends on DEBUG_KERNEL
1709	select TORTURE_TEST
1710	help
1711	This option provides a kernel module that runs torture tests
1712	on the smp_call_function() family of primitives. The kernel
1713	module may be built after the fact on the running kernel to
1714	be tested, if desired.
1715
1716	config CSD_LOCK_WAIT_DEBUG
1717	bool "Debugging for csd_lock_wait(), called from smp_call_function*()"
1718	depends on DEBUG_KERNEL
1719	depends on SMP
1720	depends on 64BIT
1721	default n
1722	help
1723	This option enables debug prints when CPUs are slow to respond
1724	to the smp_call_function*() IPI wrappers. These debug prints
1725	include the IPI handler function currently executing (if any)
1726	and relevant stack traces.
1727
1728	config CSD_LOCK_WAIT_DEBUG_DEFAULT
1729	bool "Default csd_lock_wait() debugging on at boot time"
1730	depends on CSD_LOCK_WAIT_DEBUG
1731	depends on 64BIT
1732	default n
1733	help
1734	This option causes the csdlock_debug= kernel boot parameter to
1735	default to 1 (basic debugging) instead of 0 (no debugging).
1736
1737	endmenu # lock debugging
1738
1739	config TRACE_IRQFLAGS
1740	depends on TRACE_IRQFLAGS_SUPPORT
1741	bool
1742	help
1743	Enables hooks to interrupt enabling and disabling for
1744	either tracing or lock debugging.
1745
1746	config TRACE_IRQFLAGS_NMI
1747	def_bool y
1748	depends on TRACE_IRQFLAGS
1749	depends on TRACE_IRQFLAGS_NMI_SUPPORT
1750
1751	config NMI_CHECK_CPU
1752	bool "Debugging for CPUs failing to respond to backtrace requests"
1753	depends on DEBUG_KERNEL
1754	depends on X86
1755	default n
1756	help
1757	Enables debug prints when a CPU fails to respond to a given
1758	backtrace NMI. These prints provide some reasons why a CPU
1759	might legitimately be failing to respond, for example, if it
1760	is offline of if ignore_nmis is set.
1761
1762	config DEBUG_IRQFLAGS
1763	bool "Debug IRQ flag manipulation"
1764	help
1765	Enables checks for potentially unsafe enabling or disabling of
1766	interrupts, such as calling raw_local_irq_restore() when interrupts
1767	are enabled.
1768
1769	config STACKTRACE
1770	bool "Stack backtrace support"
1771	depends on STACKTRACE_SUPPORT
1772	help
1773	This option causes the kernel to create a /proc/pid/stack for
1774	every process, showing its current stack trace.
1775	It is also used by various kernel debugging features that require
1776	stack trace generation.
1777
1778	config DEBUG_KOBJECT
1779	bool "kobject debugging"
1780	depends on DEBUG_KERNEL
1781	help
1782	If you say Y here, some extra kobject debugging messages will be sent
1783	to the syslog.
1784
1785	config DEBUG_KOBJECT_RELEASE
1786	bool "kobject release debugging"
1787	depends on DEBUG_OBJECTS_TIMERS
1788	help
1789	kobjects are reference counted objects. This means that their
1790	last reference count put is not predictable, and the kobject can
1791	live on past the point at which a driver decides to drop its
1792	initial reference to the kobject gained on allocation. An
1793	example of this would be a struct device which has just been
1794	unregistered.
1795
1796	However, some buggy drivers assume that after such an operation,
1797	the memory backing the kobject can be immediately freed. This
1798	goes completely against the principles of a refcounted object.
1799
1800	If you say Y here, the kernel will delay the release of kobjects
1801	on the last reference count to improve the visibility of this
1802	kind of kobject release bug.
1803
1804	config HAVE_DEBUG_BUGVERBOSE
1805	bool
1806
1807	menu "Debug kernel data structures"
1808
1809	config DEBUG_LIST
1810	bool "Debug linked list manipulation"
1811	depends on DEBUG_KERNEL
1812	select LIST_HARDENED
1813	help
1814	Enable this to turn on extended checks in the linked-list walking
1815	routines.
1816
1817	This option trades better quality error reports for performance, and
1818	is more suitable for kernel debugging. If you care about performance,
1819	you should only enable CONFIG_LIST_HARDENED instead.
1820
1821	If unsure, say N.
1822
1823	config DEBUG_PLIST
1824	bool "Debug priority linked list manipulation"
1825	depends on DEBUG_KERNEL
1826	help
1827	Enable this to turn on extended checks in the priority-ordered
1828	linked-list (plist) walking routines. This checks the entire
1829	list multiple times during each manipulation.
1830
1831	If unsure, say N.
1832
1833	config DEBUG_SG
1834	bool "Debug SG table operations"
1835	depends on DEBUG_KERNEL
1836	help
1837	Enable this to turn on checks on scatter-gather tables. This can
1838	help find problems with drivers that do not properly initialize
1839	their sg tables.
1840
1841	If unsure, say N.
1842
1843	config DEBUG_NOTIFIERS
1844	bool "Debug notifier call chains"
1845	depends on DEBUG_KERNEL
1846	help
1847	Enable this to turn on sanity checking for notifier call chains.
1848	This is most useful for kernel developers to make sure that
1849	modules properly unregister themselves from notifier chains.
1850	This is a relatively cheap check but if you care about maximum
1851	performance, say N.
1852
1853	config DEBUG_CLOSURES
1854	bool "Debug closures (bcache async widgits)"
1855	depends on CLOSURES
1856	select DEBUG_FS
1857	help
1858	Keeps all active closures in a linked list and provides a debugfs
1859	interface to list them, which makes it possible to see asynchronous
1860	operations that get stuck.
1861
1862	config DEBUG_MAPLE_TREE
1863	bool "Debug maple trees"
1864	depends on DEBUG_KERNEL
1865	help
1866	Enable maple tree debugging information and extra validations.
1867
1868	If unsure, say N.
1869
1870	endmenu
1871
1872	source "kernel/rcu/Kconfig.debug"
1873
1874	config DEBUG_WQ_FORCE_RR_CPU
1875	bool "Force round-robin CPU selection for unbound work items"
1876	depends on DEBUG_KERNEL
1877	default n
1878	help
1879	Workqueue used to implicitly guarantee that work items queued
1880	without explicit CPU specified are put on the local CPU. This
1881	guarantee is no longer true and while local CPU is still
1882	preferred work items may be put on foreign CPUs. Kernel
1883	parameter "workqueue.debug_force_rr_cpu" is added to force
1884	round-robin CPU selection to flush out usages which depend on the
1885	now broken guarantee. This config option enables the debug
1886	feature by default. When enabled, memory and cache locality will
1887	be impacted.
1888
1889	config CPU_HOTPLUG_STATE_CONTROL
1890	bool "Enable CPU hotplug state control"
1891	depends on DEBUG_KERNEL
1892	depends on HOTPLUG_CPU
1893	default n
1894	help
1895	Allows to write steps between "offline" and "online" to the CPUs
1896	sysfs target file so states can be stepped granular. This is a debug
1897	option for now as the hotplug machinery cannot be stopped and
1898	restarted at arbitrary points yet.
1899
1900	Say N if your are unsure.
1901
1902	config LATENCYTOP
1903	bool "Latency measuring infrastructure"
1904	depends on DEBUG_KERNEL
1905	depends on STACKTRACE_SUPPORT
1906	depends on PROC_FS
1907	depends on FRAME_POINTER \|\| MIPS \|\| PPC \|\| S390 \|\| MICROBLAZE \|\| ARM \|\| ARC \|\| X86
1908	select KALLSYMS
1909	select KALLSYMS_ALL
1910	select STACKTRACE
1911	select SCHEDSTATS
1912	help
1913	Enable this option if you want to use the LatencyTOP tool
1914	to find out which userspace is blocking on what kernel operations.
1915
1916	config DEBUG_CGROUP_REF
1917	bool "Disable inlining of cgroup css reference count functions"
1918	depends on DEBUG_KERNEL
1919	depends on CGROUPS
1920	depends on KPROBES
1921	default n
1922	help
1923	Force cgroup css reference count functions to not be inlined so
1924	that they can be kprobed for debugging.
1925
1926	source "kernel/trace/Kconfig"
1927
1928	config PROVIDE_OHCI1394_DMA_INIT
1929	bool "Remote debugging over FireWire early on boot"
1930	depends on PCI && X86
1931	help
1932	If you want to debug problems which hang or crash the kernel early
1933	on boot and the crashing machine has a FireWire port, you can use
1934	this feature to remotely access the memory of the crashed machine
1935	over FireWire. This employs remote DMA as part of the OHCI1394
1936	specification which is now the standard for FireWire controllers.
1937
1938	With remote DMA, you can monitor the printk buffer remotely using
1939	firescope and access all memory below 4GB using fireproxy from gdb.
1940	Even controlling a kernel debugger is possible using remote DMA.
1941
1942	Usage:
1943
1944	If ohci1394_dma=early is used as boot parameter, it will initialize
1945	all OHCI1394 controllers which are found in the PCI config space.
1946
1947	As all changes to the FireWire bus such as enabling and disabling
1948	devices cause a bus reset and thereby disable remote DMA for all
1949	devices, be sure to have the cable plugged and FireWire enabled on
1950	the debugging host before booting the debug target for debugging.
1951
1952	This code (~1k) is freed after boot. By then, the firewire stack
1953	in charge of the OHCI-1394 controllers should be used instead.
1954
1955	See Documentation/core-api/debugging-via-ohci1394.rst for more information.
1956
1957	source "samples/Kconfig"
1958
1959	config ARCH_HAS_DEVMEM_IS_ALLOWED
1960	bool
1961
1962	config STRICT_DEVMEM
1963	bool "Filter access to /dev/mem"
1964	depends on MMU && DEVMEM
1965	depends on ARCH_HAS_DEVMEM_IS_ALLOWED \|\| GENERIC_LIB_DEVMEM_IS_ALLOWED
1966	default y if PPC \|\| X86 \|\| ARM64 \|\| S390
1967	help
1968	If this option is disabled, you allow userspace (root) access to all
1969	of memory, including kernel and userspace memory. Accidental
1970	access to this is obviously disastrous, but specific access can
1971	be used by people debugging the kernel. Note that with PAT support
1972	enabled, even in this case there are restrictions on /dev/mem
1973	use due to the cache aliasing requirements.
1974
1975	If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
1976	file only allows userspace access to PCI space and the BIOS code and
1977	data regions. This is sufficient for dosemu and X and all common
1978	users of /dev/mem.
1979
1980	If in doubt, say Y.
1981
1982	config IO_STRICT_DEVMEM
1983	bool "Filter I/O access to /dev/mem"
1984	depends on STRICT_DEVMEM
1985	help
1986	If this option is disabled, you allow userspace (root) access to all
1987	io-memory regardless of whether a driver is actively using that
1988	range. Accidental access to this is obviously disastrous, but
1989	specific access can be used by people debugging kernel drivers.
1990
1991	If this option is switched on, the /dev/mem file only allows
1992	userspace access to idle io-memory ranges (see /proc/iomem) This
1993	may break traditional users of /dev/mem (dosemu, legacy X, etc...)
1994	if the driver using a given range cannot be disabled.
1995
1996	If in doubt, say Y.
1997
1998	menu "$(SRCARCH) Debugging"
1999
2000	source "arch/$(SRCARCH)/Kconfig.debug"
2001
2002	endmenu
2003
2004	menu "Kernel Testing and Coverage"
2005
2006	source "lib/kunit/Kconfig"
2007
2008	config NOTIFIER_ERROR_INJECTION
2009	tristate "Notifier error injection"
2010	depends on DEBUG_KERNEL
2011	select DEBUG_FS
2012	help
2013	This option provides the ability to inject artificial errors to
2014	specified notifier chain callbacks. It is useful to test the error
2015	handling of notifier call chain failures.
2016
2017	Say N if unsure.
2018
2019	config PM_NOTIFIER_ERROR_INJECT
2020	tristate "PM notifier error injection module"
2021	depends on PM && NOTIFIER_ERROR_INJECTION
2022	default m if PM_DEBUG
2023	help
2024	This option provides the ability to inject artificial errors to
2025	PM notifier chain callbacks. It is controlled through debugfs
2026	interface /sys/kernel/debug/notifier-error-inject/pm
2027
2028	If the notifier call chain should be failed with some events
2029	notified, write the error code to "actions/<notifier event>/error".
2030
2031	Example: Inject PM suspend error (-12 = -ENOMEM)
2032
2033	# cd /sys/kernel/debug/notifier-error-inject/pm/
2034	# echo -12 > actions/PM_SUSPEND_PREPARE/error
2035	# echo mem > /sys/power/state
2036	bash: echo: write error: Cannot allocate memory
2037
2038	To compile this code as a module, choose M here: the module will
2039	be called pm-notifier-error-inject.
2040
2041	If unsure, say N.
2042
2043	config OF_RECONFIG_NOTIFIER_ERROR_INJECT
2044	tristate "OF reconfig notifier error injection module"
2045	depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
2046	help
2047	This option provides the ability to inject artificial errors to
2048	OF reconfig notifier chain callbacks. It is controlled
2049	through debugfs interface under
2050	/sys/kernel/debug/notifier-error-inject/OF-reconfig/
2051
2052	If the notifier call chain should be failed with some events
2053	notified, write the error code to "actions/<notifier event>/error".
2054
2055	To compile this code as a module, choose M here: the module will
2056	be called of-reconfig-notifier-error-inject.
2057
2058	If unsure, say N.
2059
2060	config NETDEV_NOTIFIER_ERROR_INJECT
2061	tristate "Netdev notifier error injection module"
2062	depends on NET && NOTIFIER_ERROR_INJECTION
2063	help
2064	This option provides the ability to inject artificial errors to
2065	netdevice notifier chain callbacks. It is controlled through debugfs
2066	interface /sys/kernel/debug/notifier-error-inject/netdev
2067
2068	If the notifier call chain should be failed with some events
2069	notified, write the error code to "actions/<notifier event>/error".
2070
2071	Example: Inject netdevice mtu change error (-22 = -EINVAL)
2072
2073	# cd /sys/kernel/debug/notifier-error-inject/netdev
2074	# echo -22 > actions/NETDEV_CHANGEMTU/error
2075	# ip link set eth0 mtu 1024
2076	RTNETLINK answers: Invalid argument
2077
2078	To compile this code as a module, choose M here: the module will
2079	be called netdev-notifier-error-inject.
2080
2081	If unsure, say N.
2082
2083	config FUNCTION_ERROR_INJECTION
2084	bool "Fault-injections of functions"
2085	depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
2086	help
2087	Add fault injections into various functions that are annotated with
2088	ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return
2089	value of these functions. This is useful to test error paths of code.
2090
2091	If unsure, say N
2092
2093	config FAULT_INJECTION
2094	bool "Fault-injection framework"
2095	depends on DEBUG_KERNEL
2096	help
2097	Provide fault-injection framework.
2098	For more details, see Documentation/fault-injection/.
2099
2100	config FAILSLAB
2101	bool "Fault-injection capability for kmalloc"
2102	depends on FAULT_INJECTION
2103	help
2104	Provide fault-injection capability for kmalloc.
2105
2106	config FAIL_PAGE_ALLOC
2107	bool "Fault-injection capability for alloc_pages()"
2108	depends on FAULT_INJECTION
2109	help
2110	Provide fault-injection capability for alloc_pages().
2111
2112	config FAULT_INJECTION_USERCOPY
2113	bool "Fault injection capability for usercopy functions"
2114	depends on FAULT_INJECTION
2115	help
2116	Provides fault-injection capability to inject failures
2117	in usercopy functions (copy_from_user(), get_user(), ...).
2118
2119	config FAIL_MAKE_REQUEST
2120	bool "Fault-injection capability for disk IO"
2121	depends on FAULT_INJECTION && BLOCK
2122	help
2123	Provide fault-injection capability for disk IO.
2124
2125	config FAIL_IO_TIMEOUT
2126	bool "Fault-injection capability for faking disk interrupts"
2127	depends on FAULT_INJECTION && BLOCK
2128	help
2129	Provide fault-injection capability on end IO handling. This
2130	will make the block layer "forget" an interrupt as configured,
2131	thus exercising the error handling.
2132
2133	Only works with drivers that use the generic timeout handling,
2134	for others it won't do anything.
2135
2136	config FAIL_FUTEX
2137	bool "Fault-injection capability for futexes"
2138	select DEBUG_FS
2139	depends on FAULT_INJECTION && FUTEX
2140	help
2141	Provide fault-injection capability for futexes.
2142
2143	config FAULT_INJECTION_DEBUG_FS
2144	bool "Debugfs entries for fault-injection capabilities"
2145	depends on FAULT_INJECTION && SYSFS && DEBUG_FS
2146	help
2147	Enable configuration of fault-injection capabilities via debugfs.
2148
2149	config FAIL_FUNCTION
2150	bool "Fault-injection capability for functions"
2151	depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
2152	help
2153	Provide function-based fault-injection capability.
2154	This will allow you to override a specific function with a return
2155	with given return value. As a result, function caller will see
2156	an error value and have to handle it. This is useful to test the
2157	error handling in various subsystems.
2158
2159	config FAIL_MMC_REQUEST
2160	bool "Fault-injection capability for MMC IO"
2161	depends on FAULT_INJECTION_DEBUG_FS && MMC
2162	help
2163	Provide fault-injection capability for MMC IO.
2164	This will make the mmc core return data errors. This is
2165	useful to test the error handling in the mmc block device
2166	and to test how the mmc host driver handles retries from
2167	the block device.
2168
2169	config FAIL_SUNRPC
2170	bool "Fault-injection capability for SunRPC"
2171	depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG
2172	help
2173	Provide fault-injection capability for SunRPC and
2174	its consumers.
2175
2176	config FAIL_SKB_REALLOC
2177	bool "Fault-injection capability forcing skb to reallocate"
2178	depends on FAULT_INJECTION_DEBUG_FS
2179	help
2180	Provide fault-injection capability that forces the skb to be
2181	reallocated, catching possible invalid pointers to the skb.
2182
2183	For more information, check
2184	Documentation/fault-injection/fault-injection.rst
2185
2186	config FAULT_INJECTION_CONFIGFS
2187	bool "Configfs interface for fault-injection capabilities"
2188	depends on FAULT_INJECTION
2189	select CONFIGFS_FS
2190	help
2191	This option allows configfs-based drivers to dynamically configure
2192	fault-injection via configfs. Each parameter for driver-specific
2193	fault-injection can be made visible as a configfs attribute in a
2194	configfs group.
2195
2196
2197	config FAULT_INJECTION_STACKTRACE_FILTER
2198	bool "stacktrace filter for fault-injection capabilities"
2199	depends on FAULT_INJECTION
2200	depends on (FAULT_INJECTION_DEBUG_FS \|\| FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT
2201	select STACKTRACE
2202	depends on FRAME_POINTER \|\| MIPS \|\| PPC \|\| S390 \|\| MICROBLAZE \|\| ARM \|\| ARC \|\| X86
2203	help
2204	Provide stacktrace filter for fault-injection capabilities
2205
2206	config ARCH_HAS_KCOV
2207	bool
2208	help
2209	An architecture should select this when it can successfully
2210	build and run with CONFIG_KCOV. This typically requires
2211	disabling instrumentation for some early boot code.
2212
2213	config KCOV
2214	bool "Code coverage for fuzzing"
2215	depends on ARCH_HAS_KCOV
2216	depends on !ARCH_WANTS_NO_INSTR \|\| HAVE_NOINSTR_HACK \|\| \
2217	GCC_VERSION >= 120000 \|\| CC_IS_CLANG
2218	select DEBUG_FS
2219	select OBJTOOL if HAVE_NOINSTR_HACK
2220	help
2221	KCOV exposes kernel code coverage information in a form suitable
2222	for coverage-guided fuzzing (randomized testing).
2223
2224	For more details, see Documentation/dev-tools/kcov.rst.
2225
2226	config KCOV_ENABLE_COMPARISONS
2227	bool "Enable comparison operands collection by KCOV"
2228	depends on KCOV
2229	depends on $(cc-option,-fsanitize-coverage=trace-cmp)
2230	help
2231	KCOV also exposes operands of every comparison in the instrumented
2232	code along with operand sizes and PCs of the comparison instructions.
2233	These operands can be used by fuzzing engines to improve the quality
2234	of fuzzing coverage.
2235
2236	config KCOV_INSTRUMENT_ALL
2237	bool "Instrument all code by default"
2238	depends on KCOV
2239	default y
2240	help
2241	If you are doing generic system call fuzzing (like e.g. syzkaller),
2242	then you will want to instrument the whole kernel and you should
2243	say y here. If you are doing more targeted fuzzing (like e.g.
2244	filesystem fuzzing with AFL) then you will want to enable coverage
2245	for more specific subsets of files, and should say n here.
2246
2247	config KCOV_IRQ_AREA_SIZE
2248	hex "Size of interrupt coverage collection area in words"
2249	depends on KCOV
2250	default 0x40000
2251	help
2252	KCOV uses preallocated per-cpu areas to collect coverage from
2253	soft interrupts. This specifies the size of those areas in the
2254	number of unsigned long words.
2255
2256	config KCOV_SELFTEST
2257	bool "Perform short selftests on boot"
2258	depends on KCOV
2259	help
2260	Run short KCOV coverage collection selftests on boot.
2261	On test failure, causes the kernel to panic. Recommended to be
2262	enabled, ensuring critical functionality works as intended.
2263
2264	menuconfig RUNTIME_TESTING_MENU
2265	bool "Runtime Testing"
2266	default y
2267
2268	if RUNTIME_TESTING_MENU
2269
2270	config TEST_DHRY
2271	tristate "Dhrystone benchmark test"
2272	help
2273	Enable this to include the Dhrystone 2.1 benchmark. This test
2274	calculates the number of Dhrystones per second, and the number of
2275	DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided
2276	by 1757 (the number of Dhrystones per second obtained on the VAX
2277	11/780, nominally a 1 MIPS machine).
2278
2279	To run the benchmark, it needs to be enabled explicitly, either from
2280	the kernel command line (when built-in), or from userspace (when
2281	built-in or modular).
2282
2283	Run once during kernel boot:
2284
2285	test_dhry.run
2286
2287	Set number of iterations from kernel command line:
2288
2289	test_dhry.iterations=<n>
2290
2291	Set number of iterations from userspace:
2292
2293	echo <n> > /sys/module/test_dhry/parameters/iterations
2294
2295	Trigger manual run from userspace:
2296
2297	echo y > /sys/module/test_dhry/parameters/run
2298
2299	If the number of iterations is <= 0, the test will devise a suitable
2300	number of iterations (test runs for at least 2s) automatically.
2301	This process takes ca. 4s.
2302
2303	If unsure, say N.
2304
2305	config LKDTM
2306	tristate "Linux Kernel Dump Test Tool Module"
2307	depends on DEBUG_FS
2308	help
2309	This module enables testing of the different dumping mechanisms by
2310	inducing system failures at predefined crash points.
2311	If you don't need it: say N
2312	Choose M here to compile this code as a module. The module will be
2313	called lkdtm.
2314
2315	Documentation on how to use the module can be found in
2316	Documentation/fault-injection/provoke-crashes.rst
2317
2318	config CPUMASK_KUNIT_TEST
2319	tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS
2320	depends on KUNIT
2321	default KUNIT_ALL_TESTS
2322	help
2323	Enable to turn on cpumask tests, running at boot or module load time.
2324
2325	For more information on KUnit and unit tests in general, please refer
2326	to the KUnit documentation in Documentation/dev-tools/kunit/.
2327
2328	If unsure, say N.
2329
2330	config TEST_LIST_SORT
2331	tristate "Linked list sorting test" if !KUNIT_ALL_TESTS
2332	depends on KUNIT
2333	default KUNIT_ALL_TESTS
2334	help
2335	Enable this to turn on 'list_sort()' function test. This test is
2336	executed only once during system boot (so affects only boot time),
2337	or at module load time.
2338
2339	If unsure, say N.
2340
2341	config TEST_SORT
2342	tristate "Array-based sort test" if !KUNIT_ALL_TESTS
2343	depends on KUNIT
2344	default KUNIT_ALL_TESTS
2345	help
2346	This option enables the self-test function of 'sort()' at boot,
2347	or at module load time.
2348
2349	If unsure, say N.
2350
2351	config TEST_DIV64
2352	tristate "64bit/32bit division and modulo test"
2353	depends on DEBUG_KERNEL \|\| m
2354	help
2355	Enable this to turn on 'do_div()' function test. This test is
2356	executed only once during system boot (so affects only boot time),
2357	or at module load time.
2358
2359	If unsure, say N.
2360
2361	config TEST_MULDIV64
2362	tristate "mul_u64_u64_div_u64() test"
2363	depends on DEBUG_KERNEL \|\| m
2364	help
2365	Enable this to turn on 'mul_u64_u64_div_u64()' function test.
2366	This test is executed only once during system boot (so affects
2367	only boot time), or at module load time.
2368
2369	If unsure, say N.
2370
2371	config TEST_IOV_ITER
2372	tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS
2373	depends on KUNIT
2374	depends on MMU
2375	default KUNIT_ALL_TESTS
2376	help
2377	Enable this to turn on testing of the operation of the I/O iterator
2378	(iov_iter). This test is executed only once during system boot (so
2379	affects only boot time), or at module load time.
2380
2381	If unsure, say N.
2382
2383	config KPROBES_SANITY_TEST
2384	tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS
2385	depends on DEBUG_KERNEL
2386	depends on KPROBES
2387	depends on KUNIT
2388	select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
2389	default KUNIT_ALL_TESTS
2390	help
2391	This option provides for testing basic kprobes functionality on
2392	boot. Samples of kprobe and kretprobe are inserted and
2393	verified for functionality.
2394
2395	Say N if you are unsure.
2396
2397	config FPROBE_SANITY_TEST
2398	bool "Self test for fprobe"
2399	depends on DEBUG_KERNEL
2400	depends on FPROBE
2401	depends on KUNIT=y
2402	help
2403	This option will enable testing the fprobe when the system boot.
2404	A series of tests are made to verify that the fprobe is functioning
2405	properly.
2406
2407	Say N if you are unsure.
2408
2409	config BACKTRACE_SELF_TEST
2410	tristate "Self test for the backtrace code"
2411	depends on DEBUG_KERNEL
2412	help
2413	This option provides a kernel module that can be used to test
2414	the kernel stack backtrace code. This option is not useful
2415	for distributions or general kernels, but only for kernel
2416	developers working on architecture code.
2417
2418	Note that if you want to also test saved backtraces, you will
2419	have to enable STACKTRACE as well.
2420
2421	Say N if you are unsure.
2422
2423	config TEST_REF_TRACKER
2424	tristate "Self test for reference tracker"
2425	depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
2426	select REF_TRACKER
2427	help
2428	This option provides a kernel module performing tests
2429	using reference tracker infrastructure.
2430
2431	Say N if you are unsure.
2432
2433	config RBTREE_TEST
2434	tristate "Red-Black tree test"
2435	depends on DEBUG_KERNEL
2436	help
2437	A benchmark measuring the performance of the rbtree library.
2438	Also includes rbtree invariant checks.
2439
2440	config REED_SOLOMON_TEST
2441	tristate "Reed-Solomon library test"
2442	depends on DEBUG_KERNEL \|\| m
2443	select REED_SOLOMON
2444	select REED_SOLOMON_ENC16
2445	select REED_SOLOMON_DEC16
2446	help
2447	This option enables the self-test function of rslib at boot,
2448	or at module load time.
2449
2450	If unsure, say N.
2451
2452	config INTERVAL_TREE_TEST
2453	tristate "Interval tree test"
2454	depends on DEBUG_KERNEL
2455	select INTERVAL_TREE
2456	help
2457	A benchmark measuring the performance of the interval tree library
2458
2459	config PERCPU_TEST
2460	tristate "Per cpu operations test"
2461	depends on m && DEBUG_KERNEL
2462	help
2463	Enable this option to build test module which validates per-cpu
2464	operations.
2465
2466	If unsure, say N.
2467
2468	config ATOMIC64_SELFTEST
2469	tristate "Perform an atomic64_t self-test"
2470	help
2471	Enable this option to test the atomic64_t functions at boot or
2472	at module load time.
2473
2474	If unsure, say N.
2475
2476	config ASYNC_RAID6_TEST
2477	tristate "Self test for hardware accelerated raid6 recovery"
2478	depends on ASYNC_RAID6_RECOV
2479	select ASYNC_MEMCPY
2480	help
2481	This is a one-shot self test that permutes through the
2482	recovery of all the possible two disk failure scenarios for a
2483	N-disk array. Recovery is performed with the asynchronous
2484	raid6 recovery routines, and will optionally use an offload
2485	engine if one is available.
2486
2487	If unsure, say N.
2488
2489	config TEST_HEXDUMP
2490	tristate "Test functions located in the hexdump module at runtime"
2491
2492	config PRINTF_KUNIT_TEST
2493	tristate "KUnit test printf() family of functions at runtime" if !KUNIT_ALL_TESTS
2494	depends on KUNIT
2495	default KUNIT_ALL_TESTS
2496	help
2497	Enable this option to test the printf functions at runtime.
2498
2499	If unsure, say N.
2500
2501	config SCANF_KUNIT_TEST
2502	tristate "KUnit test scanf() family of functions at runtime" if !KUNIT_ALL_TESTS
2503	depends on KUNIT
2504	default KUNIT_ALL_TESTS
2505	help
2506	Enable this option to test the scanf functions at runtime.
2507
2508	If unsure, say N.
2509
2510	config SEQ_BUF_KUNIT_TEST
2511	tristate "KUnit test for seq_buf" if !KUNIT_ALL_TESTS
2512	depends on KUNIT
2513	default KUNIT_ALL_TESTS
2514	help
2515	This builds unit tests for the seq_buf library.
2516
2517	If unsure, say N.
2518
2519	config STRING_KUNIT_TEST
2520	tristate "KUnit test string functions at runtime" if !KUNIT_ALL_TESTS
2521	depends on KUNIT
2522	default KUNIT_ALL_TESTS
2523
2524	config STRING_HELPERS_KUNIT_TEST
2525	tristate "KUnit test string helpers at runtime" if !KUNIT_ALL_TESTS
2526	depends on KUNIT
2527	default KUNIT_ALL_TESTS
2528
2529	config STRING_KUNIT_BENCH
2530	bool "Benchmark string functions at runtime"
2531	depends on STRING_KUNIT_TEST
2532	help
2533	Enable performance measurement for string functions.
2534
2535	This measures the execution efficiency of string functions
2536	during the KUnit test run.
2537
2538	If unsure, say N.
2539
2540	config FFS_KUNIT_TEST
2541	tristate "KUnit test ffs-family functions at runtime" if !KUNIT_ALL_TESTS
2542	depends on KUNIT
2543	default KUNIT_ALL_TESTS
2544	help
2545	This builds KUnit tests for ffs-family bit manipulation functions
2546	including ffs(), __ffs(), fls(), __fls(), fls64(), and __ffs64().
2547
2548	These tests validate mathematical correctness, edge case handling,
2549	and cross-architecture consistency of bit scanning functions.
2550
2551	For more information on KUnit and unit tests in general,
2552	please refer to Documentation/dev-tools/kunit/.
2553
2554	config TEST_KSTRTOX
2555	tristate "Test kstrto*() family of functions at runtime"
2556
2557	config TEST_BITMAP
2558	tristate "Test bitmap_*() family of functions at runtime"
2559	help
2560	Enable this option to test the bitmap functions at boot.
2561
2562	If unsure, say N.
2563
2564	config TEST_XARRAY
2565	tristate "Test the XArray code at runtime"
2566
2567	config TEST_MAPLE_TREE
2568	tristate "Test the Maple Tree code at runtime or module load"
2569	help
2570	Enable this option to test the maple tree code functions at boot, or
2571	when the module is loaded. Enable "Debug Maple Trees" will enable
2572	more verbose output on failures.
2573
2574	If unsure, say N.
2575
2576	config TEST_RHASHTABLE
2577	tristate "Perform selftest on resizable hash table"
2578	help
2579	Enable this option to test the rhashtable functions at boot.
2580
2581	If unsure, say N.
2582
2583	config TEST_IDA
2584	tristate "Perform selftest on IDA functions"
2585
2586	config TEST_MISC_MINOR
2587	bool "miscdevice KUnit test" if !KUNIT_ALL_TESTS
2588	depends on KUNIT=y
2589	default KUNIT_ALL_TESTS
2590	help
2591	Kunit test for miscdevice API, specially its behavior in respect to
2592	static and dynamic minor numbers.
2593
2594	KUnit tests run during boot and output the results to the debug log
2595	in TAP format (https://testanything.org/). Only useful for kernel devs
2596	running the KUnit test harness, and not intended for inclusion into a
2597	production build.
2598
2599	For more information on KUnit and unit tests in general please refer
2600	to the KUnit documentation in Documentation/dev-tools/kunit/.
2601
2602	If unsure, say N.
2603
2604	config TEST_PARMAN
2605	tristate "Perform selftest on priority array manager"
2606	depends on PARMAN
2607	help
2608	Enable this option to test priority array manager on boot
2609	(or module load).
2610
2611	If unsure, say N.
2612
2613	config TEST_LKM
2614	tristate "Test module loading with 'hello world' module"
2615	depends on m
2616	help
2617	This builds the "test_module" module that emits "Hello, world"
2618	on printk when loaded. It is designed to be used for basic
2619	evaluation of the module loading subsystem (for example when
2620	validating module verification). It lacks any extra dependencies,
2621	and will not normally be loaded by the system unless explicitly
2622	requested by name.
2623
2624	If unsure, say N.
2625
2626	config TEST_BITOPS
2627	tristate "Test module for compilation of bitops operations"
2628	help
2629	This builds the "test_bitops" module that is much like the
2630	TEST_LKM module except that it does a basic exercise of the
2631	set/clear_bit macros and get_count_order/long to make sure there are
2632	no compiler warnings from C=1 sparse checker or -Wextra
2633	compilations. It has no dependencies and doesn't run or load unless
2634	explicitly requested by name. for example: modprobe test_bitops.
2635
2636	If unsure, say N.
2637
2638	config TEST_VMALLOC
2639	tristate "Test module for stress/performance analysis of vmalloc allocator"
2640	default n
2641	depends on MMU
2642	help
2643	This builds the "test_vmalloc" module that should be used for
2644	stress and performance analysis. So, any new change for vmalloc
2645	subsystem can be evaluated from performance and stability point
2646	of view.
2647
2648	If unsure, say N.
2649
2650	config TEST_WORKQUEUE
2651	tristate "Test module for stress/performance analysis of workqueue"
2652	default n
2653	help
2654	This builds the "test_workqueue" module for benchmarking
2655	workqueue throughput under contention. Useful for evaluating
2656	affinity scope changes (e.g., cache_shard vs cache).
2657
2658	If unsure, say N.
2659
2660	config TEST_BPF
2661	tristate "Test BPF filter functionality"
2662	depends on m && NET
2663	help
2664	This builds the "test_bpf" module that runs various test vectors
2665	against the BPF interpreter or BPF JIT compiler depending on the
2666	current setting. This is in particular useful for BPF JIT compiler
2667	development, but also to run regression tests against changes in
2668	the interpreter code. It also enables test stubs for eBPF maps and
2669	verifier used by user space verifier testsuite.
2670
2671	If unsure, say N.
2672
2673	config FIND_BIT_BENCHMARK
2674	tristate "Test find_bit functions"
2675	help
2676	This builds the "test_find_bit" module that measure find_*_bit()
2677	functions performance.
2678
2679	If unsure, say N.
2680
2681	config FIND_BIT_BENCHMARK_RUST
2682	tristate "Test find_bit functions in Rust"
2683	depends on RUST
2684	help
2685	This builds the "find_bit_benchmark_rust" module. It is a micro
2686	benchmark that measures the performance of Rust functions that
2687	correspond to the find_*_bit() operations in C. It follows the
2688	FIND_BIT_BENCHMARK closely but will in general not yield same
2689	numbers due to extra bounds checks and overhead of foreign
2690	function calls.
2691
2692	If unsure, say N.
2693
2694	config TEST_FIRMWARE
2695	tristate "Test firmware loading via userspace interface"
2696	depends on FW_LOADER
2697	help
2698	This builds the "test_firmware" module that creates a userspace
2699	interface for testing firmware loading. This can be used to
2700	control the triggering of firmware loading without needing an
2701	actual firmware-using device. The contents can be rechecked by
2702	userspace.
2703
2704	If unsure, say N.
2705
2706	config TEST_SYSCTL
2707	tristate "sysctl test driver"
2708	depends on PROC_SYSCTL
2709	help
2710	This builds the "test_sysctl" module. This driver enables to test the
2711	proc sysctl interfaces available to drivers safely without affecting
2712	production knobs which might alter system functionality.
2713
2714	If unsure, say N.
2715
2716	config BITOPS_KUNIT
2717	tristate "KUnit test for bitops" if !KUNIT_ALL_TESTS
2718	depends on KUNIT
2719	default KUNIT_ALL_TESTS
2720	help
2721	This option enables the KUnit test for the bitops library
2722	which provides functions for bit operations.
2723
2724	Note that this is derived from the original test_bitops module.
2725	For micro-benchmarks and compiler warning checks, enable TEST_BITOPS.
2726
2727	If unsure, say N.
2728
2729	config BITFIELD_KUNIT
2730	tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS
2731	depends on KUNIT
2732	default KUNIT_ALL_TESTS
2733	help
2734	Enable this option to test the bitfield functions at boot.
2735
2736	KUnit tests run during boot and output the results to the debug log
2737	in TAP format (http://testanything.org/). Only useful for kernel devs
2738	running the KUnit test harness, and not intended for inclusion into a
2739	production build.
2740
2741	For more information on KUnit and unit tests in general please refer
2742	to the KUnit documentation in Documentation/dev-tools/kunit/.
2743
2744	If unsure, say N.
2745
2746	config CHECKSUM_KUNIT
2747	tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS
2748	depends on KUNIT
2749	default KUNIT_ALL_TESTS
2750	help
2751	Enable this option to test the checksum functions at boot.
2752
2753	KUnit tests run during boot and output the results to the debug log
2754	in TAP format (http://testanything.org/). Only useful for kernel devs
2755	running the KUnit test harness, and not intended for inclusion into a
2756	production build.
2757
2758	For more information on KUnit and unit tests in general please refer
2759	to the KUnit documentation in Documentation/dev-tools/kunit/.
2760
2761	If unsure, say N.
2762
2763	config UTIL_MACROS_KUNIT
2764	tristate "KUnit test util_macros.h functions at runtime" if !KUNIT_ALL_TESTS
2765	depends on KUNIT
2766	default KUNIT_ALL_TESTS
2767	help
2768	Enable this option to test the util_macros.h function at boot.
2769
2770	KUnit tests run during boot and output the results to the debug log
2771	in TAP format (http://testanything.org/). Only useful for kernel devs
2772	running the KUnit test harness, and not intended for inclusion into a
2773	production build.
2774
2775	For more information on KUnit and unit tests in general please refer
2776	to the KUnit documentation in Documentation/dev-tools/kunit/.
2777
2778	If unsure, say N.
2779
2780	config HASH_KUNIT_TEST
2781	tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS
2782	depends on KUNIT
2783	default KUNIT_ALL_TESTS
2784	help
2785	Enable this option to test the kernel's string (<linux/stringhash.h>), and
2786	integer (<linux/hash.h>) hash functions on boot.
2787
2788	KUnit tests run during boot and output the results to the debug log
2789	in TAP format (https://testanything.org/). Only useful for kernel devs
2790	running the KUnit test harness, and not intended for inclusion into a
2791	production build.
2792
2793	For more information on KUnit and unit tests in general please refer
2794	to the KUnit documentation in Documentation/dev-tools/kunit/.
2795
2796	This is intended to help people writing architecture-specific
2797	optimized versions. If unsure, say N.
2798
2799	config RESOURCE_KUNIT_TEST
2800	tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS
2801	depends on KUNIT
2802	default KUNIT_ALL_TESTS
2803	select GET_FREE_REGION
2804	help
2805	This builds the resource API unit test.
2806	Tests the logic of API provided by resource.c and ioport.h.
2807	For more information on KUnit and unit tests in general please refer
2808	to the KUnit documentation in Documentation/dev-tools/kunit/.
2809
2810	If unsure, say N.
2811
2812	config SYSCTL_KUNIT_TEST
2813	tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS
2814	depends on KUNIT
2815	default KUNIT_ALL_TESTS
2816	help
2817	This builds the proc sysctl unit test, which runs on boot.
2818	Tests the API contract and implementation correctness of sysctl.
2819	For more information on KUnit and unit tests in general please refer
2820	to the KUnit documentation in Documentation/dev-tools/kunit/.
2821
2822	If unsure, say N.
2823
2824	config KFIFO_KUNIT_TEST
2825	tristate "KUnit Test for the generic kernel FIFO implementation" if !KUNIT_ALL_TESTS
2826	depends on KUNIT
2827	default KUNIT_ALL_TESTS
2828	help
2829	This builds the generic FIFO implementation KUnit test suite.
2830	It tests that the API and basic functionality of the kfifo type
2831	and associated macros.
2832
2833	For more information on KUnit and unit tests in general please refer
2834	to the KUnit documentation in Documentation/dev-tools/kunit/.
2835
2836	If unsure, say N.
2837
2838	config LIST_KUNIT_TEST
2839	tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS
2840	depends on KUNIT
2841	default KUNIT_ALL_TESTS
2842	help
2843	This builds the linked list KUnit test suite.
2844	It tests that the API and basic functionality of the list_head type
2845	and associated macros.
2846
2847	KUnit tests run during boot and output the results to the debug log
2848	in TAP format (https://testanything.org/). Only useful for kernel devs
2849	running the KUnit test harness, and not intended for inclusion into a
2850	production build.
2851
2852	For more information on KUnit and unit tests in general please refer
2853	to the KUnit documentation in Documentation/dev-tools/kunit/.
2854
2855	If unsure, say N.
2856
2857	config LIST_PRIVATE_KUNIT_TEST
2858	tristate "KUnit Test for Kernel Private Linked-list structures" if !KUNIT_ALL_TESTS
2859	depends on KUNIT
2860	default KUNIT_ALL_TESTS
2861	help
2862	This builds the KUnit test for the private linked-list primitives
2863	defined in include/linux/list_private.h.
2864
2865	These primitives allow manipulation of list_head members that are
2866	marked as private and require special accessors (ACCESS_PRIVATE)
2867	to strip qualifiers or handle encapsulation.
2868
2869	If unsure, say N.
2870
2871	config HASHTABLE_KUNIT_TEST
2872	tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS
2873	depends on KUNIT
2874	default KUNIT_ALL_TESTS
2875	help
2876	This builds the hashtable KUnit test suite.
2877	It tests the basic functionality of the API defined in
2878	include/linux/hashtable.h. For more information on KUnit and
2879	unit tests in general please refer to the KUnit documentation
2880	in Documentation/dev-tools/kunit/.
2881
2882	If unsure, say N.
2883
2884	config LINEAR_RANGES_TEST
2885	tristate "KUnit test for linear_ranges"
2886	depends on KUNIT
2887	select LINEAR_RANGES
2888	help
2889	This builds the linear_ranges unit test, which runs on boot.
2890	Tests the linear_ranges logic correctness.
2891	For more information on KUnit and unit tests in general please refer
2892	to the KUnit documentation in Documentation/dev-tools/kunit/.
2893
2894	If unsure, say N.
2895
2896	config CONTEXT_ANALYSIS_TEST
2897	bool "Compiler context-analysis warnings test"
2898	depends on EXPERT
2899	help
2900	This builds the test for compiler-based context analysis. The test
2901	does not add executable code to the kernel, but is meant to test that
2902	common patterns supported by the analysis do not result in false
2903	positive warnings.
2904
2905	When adding support for new context locks, it is strongly recommended
2906	to add supported patterns to this test.
2907
2908	If unsure, say N.
2909
2910	config LIVEUPDATE_TEST
2911	bool "Live Update Kernel Test"
2912	default n
2913	depends on LIVEUPDATE
2914	help
2915	Enable a built-in kernel test module for the Live Update
2916	Orchestrator.
2917
2918	This module validates the File-Lifecycle-Bound subsystem by
2919	registering a set of mock FLB objects with any real file handlers
2920	that support live update (such as the memfd handler).
2921
2922	When live update operations are performed, this test module will
2923	output messages to the kernel log (dmesg), confirming that its
2924	registration and various callback functions (preserve, retrieve,
2925	finish, etc.) are being invoked correctly.
2926
2927	This is a debugging and regression testing tool for developers
2928	working on the Live Update subsystem. It should not be enabled in
2929	production kernels.
2930
2931	If unsure, say N
2932
2933	config CMDLINE_KUNIT_TEST
2934	tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS
2935	depends on KUNIT
2936	default KUNIT_ALL_TESTS
2937	help
2938	This builds the cmdline API unit test.
2939	Tests the logic of API provided by cmdline.c.
2940	For more information on KUnit and unit tests in general please refer
2941	to the KUnit documentation in Documentation/dev-tools/kunit/.
2942
2943	If unsure, say N.
2944
2945	config BASE64_KUNIT
2946	tristate "KUnit test for base64 decoding and encoding" if !KUNIT_ALL_TESTS
2947	depends on KUNIT
2948	default KUNIT_ALL_TESTS
2949	help
2950	This builds the base64 unit tests.
2951
2952	The tests cover the encoding and decoding logic of Base64 functions
2953	in the kernel.
2954	In addition to correctness checks, simple performance benchmarks
2955	for both encoding and decoding are also included.
2956
2957	For more information on KUnit and unit tests in general please refer
2958	to the KUnit documentation in Documentation/dev-tools/kunit/.
2959
2960	If unsure, say N.
2961
2962	config BITS_TEST
2963	tristate "KUnit test for bit functions and macros" if !KUNIT_ALL_TESTS
2964	depends on KUNIT
2965	default KUNIT_ALL_TESTS
2966	help
2967	This builds the bits unit test.
2968	Tests the logic of macros defined in bits.h.
2969	For more information on KUnit and unit tests in general please refer
2970	to the KUnit documentation in Documentation/dev-tools/kunit/.
2971
2972	If unsure, say N.
2973
2974	config SLUB_KUNIT_TEST
2975	tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS
2976	depends on SLUB_DEBUG && KUNIT
2977	default KUNIT_ALL_TESTS
2978	help
2979	This builds SLUB allocator unit test.
2980	Tests SLUB cache debugging functionality.
2981	For more information on KUnit and unit tests in general please refer
2982	to the KUnit documentation in Documentation/dev-tools/kunit/.
2983
2984	If unsure, say N.
2985
2986	config RATIONAL_KUNIT_TEST
2987	tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS
2988	depends on KUNIT && RATIONAL
2989	default KUNIT_ALL_TESTS
2990	help
2991	This builds the rational math unit test.
2992	For more information on KUnit and unit tests in general please refer
2993	to the KUnit documentation in Documentation/dev-tools/kunit/.
2994
2995	If unsure, say N.
2996
2997	config MEMCPY_KUNIT_TEST
2998	tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS
2999	depends on KUNIT
3000	default KUNIT_ALL_TESTS
3001	help
3002	Builds unit tests for memcpy(), memmove(), and memset() functions.
3003	For more information on KUnit and unit tests in general please refer
3004	to the KUnit documentation in Documentation/dev-tools/kunit/.
3005
3006	If unsure, say N.
3007
3008	config MIN_HEAP_KUNIT_TEST
3009	tristate "Min heap test" if !KUNIT_ALL_TESTS
3010	depends on KUNIT
3011	default KUNIT_ALL_TESTS
3012	help
3013	This option enables the KUnit test suite for the min heap library
3014	which provides functions for creating and managing min heaps.
3015	The test suite checks the functionality of the min heap library.
3016
3017	If unsure, say N
3018
3019	config IS_SIGNED_TYPE_KUNIT_TEST
3020	tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS
3021	depends on KUNIT
3022	default KUNIT_ALL_TESTS
3023	help
3024	Builds unit tests for the is_signed_type() macro.
3025
3026	For more information on KUnit and unit tests in general please refer
3027	to the KUnit documentation in Documentation/dev-tools/kunit/.
3028
3029	If unsure, say N.
3030
3031	config OVERFLOW_KUNIT_TEST
3032	tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS
3033	depends on KUNIT
3034	default KUNIT_ALL_TESTS
3035	help
3036	Builds unit tests for the check__overflow(), size_(), allocation, and
3037	related functions.
3038
3039	For more information on KUnit and unit tests in general please refer
3040	to the KUnit documentation in Documentation/dev-tools/kunit/.
3041
3042	If unsure, say N.
3043
3044	config RANDSTRUCT_KUNIT_TEST
3045	tristate "Test randstruct structure layout randomization at runtime" if !KUNIT_ALL_TESTS
3046	depends on KUNIT
3047	default KUNIT_ALL_TESTS
3048	help
3049	Builds unit tests for the checking CONFIG_RANDSTRUCT=y, which
3050	randomizes structure layouts.
3051
3052	config STACKINIT_KUNIT_TEST
3053	tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS
3054	depends on KUNIT
3055	default KUNIT_ALL_TESTS
3056	help
3057	Test if the kernel is zero-initializing stack variables and
3058	padding. Coverage is controlled by compiler flags,
3059	CONFIG_INIT_STACK_ALL_PATTERN or CONFIG_INIT_STACK_ALL_ZERO.
3060
3061	config FORTIFY_KUNIT_TEST
3062	tristate "Test fortified str() and mem() function internals at runtime" if !KUNIT_ALL_TESTS
3063	depends on KUNIT
3064	default KUNIT_ALL_TESTS
3065	help
3066	Builds unit tests for checking internals of FORTIFY_SOURCE as used
3067	by the str() and mem() family of functions. For testing runtime
3068	traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests.
3069
3070	config LONGEST_SYM_KUNIT_TEST
3071	tristate "Test the longest symbol possible" if !KUNIT_ALL_TESTS
3072	depends on KUNIT && KPROBES
3073	depends on !PREFIX_SYMBOLS && !CFI && !GCOV_KERNEL
3074	default KUNIT_ALL_TESTS
3075	help
3076	Tests the longest symbol possible
3077
3078	If unsure, say N.
3079
3080	config HW_BREAKPOINT_KUNIT_TEST
3081	bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS
3082	depends on HAVE_HW_BREAKPOINT
3083	depends on KUNIT=y
3084	default KUNIT_ALL_TESTS
3085	help
3086	Tests for hw_breakpoint constraints accounting.
3087
3088	If unsure, say N.
3089
3090	source "lib/crypto/tests/Kconfig"
3091
3092	config SIPHASH_KUNIT_TEST
3093	tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS
3094	depends on KUNIT
3095	default KUNIT_ALL_TESTS
3096	help
3097	Enable this option to test the kernel's siphash (<linux/siphash.h>) hash
3098	functions on boot (or module load).
3099
3100	This is intended to help people writing architecture-specific
3101	optimized versions. If unsure, say N.
3102
3103	config USERCOPY_KUNIT_TEST
3104	tristate "KUnit Test for user/kernel boundary protections"
3105	depends on KUNIT
3106	default KUNIT_ALL_TESTS
3107	help
3108	This builds the "usercopy_kunit" module that runs sanity checks
3109	on the copy_to/from_user infrastructure, making sure basic
3110	user/kernel boundary testing is working.
3111
3112	config BLACKHOLE_DEV_KUNIT_TEST
3113	tristate "Test blackhole netdev functionality" if !KUNIT_ALL_TESTS
3114	depends on NET
3115	depends on KUNIT
3116	default KUNIT_ALL_TESTS
3117	help
3118	This builds the "blackhole_dev_kunit" module that validates the
3119	data path through this blackhole netdev.
3120
3121	If unsure, say N.
3122
3123	config TEST_UDELAY
3124	tristate "udelay test driver"
3125	help
3126	This builds the "udelay_test" module that helps to make sure
3127	that udelay() is working properly.
3128
3129	If unsure, say N.
3130
3131	config TEST_STATIC_KEYS
3132	tristate "Test static keys"
3133	depends on m
3134	help
3135	Test the static key interfaces.
3136
3137	If unsure, say N.
3138
3139	config TEST_DYNAMIC_DEBUG
3140	tristate "Test DYNAMIC_DEBUG"
3141	depends on DYNAMIC_DEBUG
3142	help
3143	This module registers a tracer callback to count enabled
3144	pr_debugs in a 'do_debugging' function, then alters their
3145	enablements, calls the function, and compares counts.
3146
3147	If unsure, say N.
3148
3149	config TEST_KMOD
3150	tristate "kmod stress tester"
3151	depends on m
3152	select TEST_LKM
3153	help
3154	Test the kernel's module loading mechanism: kmod. kmod implements
3155	support to load modules using the Linux kernel's usermode helper.
3156	This test provides a series of tests against kmod.
3157
3158	Although technically you can either build test_kmod as a module or
3159	into the kernel we disallow building it into the kernel since
3160	it stress tests request_module() and this will very likely cause
3161	some issues by taking over precious threads available from other
3162	module load requests, ultimately this could be fatal.
3163
3164	To run tests run:
3165
3166	tools/testing/selftests/kmod/kmod.sh --help
3167
3168	If unsure, say N.
3169
3170	config TEST_RUNTIME
3171	bool
3172
3173	config TEST_RUNTIME_MODULE
3174	bool
3175
3176	config TEST_KALLSYMS
3177	tristate "module kallsyms find_symbol() test"
3178	depends on m
3179	select TEST_RUNTIME
3180	select TEST_RUNTIME_MODULE
3181	select TEST_KALLSYMS_A
3182	select TEST_KALLSYMS_B
3183	select TEST_KALLSYMS_C
3184	select TEST_KALLSYMS_D
3185	help
3186	This allows us to stress test find_symbol() through the kallsyms
3187	used to place symbols on the kernel ELF kallsyms and modules kallsyms
3188	where we place kernel symbols such as exported symbols.
3189
3190	We have four test modules:
3191
3192	A: has KALLSYSMS_NUMSYMS exported symbols
3193	B: uses one of A's symbols
3194	C: adds KALLSYMS_SCALE_FACTOR * KALLSYSMS_NUMSYMS exported
3195	D: adds 2 * the symbols than C
3196
3197	We stress test find_symbol() through two means:
3198
3199	1) Upon load of B it will trigger simplify_symbols() to look for the
3200	one symbol it uses from the module A with tons of symbols. This is an
3201	indirect way for us to have B call resolve_symbol_wait() upon module
3202	load. This will eventually call find_symbol() which will eventually
3203	try to find the symbols used with find_exported_symbol_in_section().
3204	find_exported_symbol_in_section() uses bsearch() so a binary search
3205	for each symbol. Binary search will at worst be O(log(n)) so the
3206	larger TEST_MODULE_KALLSYSMS the worse the search.
3207
3208	2) The selftests should load C first, before B. Upon B's load towards
3209	the end right before we call module B's init routine we get
3210	complete_formation() called on the module. That will first check
3211	for duplicate symbols with the call to verify_exported_symbols().
3212	That is when we'll force iteration on module C's insane symbol list.
3213	Since it has 10 * KALLSYMS_NUMSYMS it means we can first test
3214	just loading B without C. The amount of time it takes to load C Vs
3215	B can give us an idea of the impact growth of the symbol space and
3216	give us projection. Module A only uses one symbol from B so to allow
3217	this scaling in module C to be proportional, if it used more symbols
3218	then the first test would be doing more and increasing just the
3219	search space would be slightly different. The last module, module D
3220	will just increase the search space by twice the number of symbols in
3221	C so to allow for full projects.
3222
3223	tools/testing/selftests/module/find_symbol.sh
3224
3225	The current defaults will incur a build delay of about 7 minutes
3226	on an x86_64 with only 8 cores. Enable this only if you want to
3227	stress test find_symbol() with thousands of symbols. At the same
3228	time this is also useful to test building modules with thousands of
3229	symbols, and if BTF is enabled this also stress tests adding BTF
3230	information for each module. Currently enabling many more symbols
3231	will segfault the build system.
3232
3233	If unsure, say N.
3234
3235	if TEST_KALLSYMS
3236
3237	config TEST_KALLSYMS_A
3238	tristate
3239	depends on m
3240
3241	config TEST_KALLSYMS_B
3242	tristate
3243	depends on m
3244
3245	config TEST_KALLSYMS_C
3246	tristate
3247	depends on m
3248
3249	config TEST_KALLSYMS_D
3250	tristate
3251	depends on m
3252
3253	choice
3254	prompt "Kallsym test range"
3255	default TEST_KALLSYMS_LARGE
3256	help
3257	Selecting something other than "Fast" will enable tests which slow
3258	down the build and may crash your build.
3259
3260	config TEST_KALLSYMS_FAST
3261	bool "Fast builds"
3262	help
3263	You won't really be testing kallsysms, so this just helps fast builds
3264	when allmodconfig is used..
3265
3266	config TEST_KALLSYMS_LARGE
3267	bool "Enable testing kallsyms with large exports"
3268	help
3269	This will enable larger number of symbols. This will slow down
3270	your build considerably.
3271
3272	config TEST_KALLSYMS_MAX
3273	bool "Known kallsysms limits"
3274	help
3275	This will enable exports to the point we know we'll start crashing
3276	builds.
3277
3278	endchoice
3279
3280	config TEST_KALLSYMS_NUMSYMS
3281	int "test kallsyms number of symbols"
3282	range 2 10000
3283	default 2 if TEST_KALLSYMS_FAST
3284	default 100 if TEST_KALLSYMS_LARGE
3285	default 10000 if TEST_KALLSYMS_MAX
3286	help
3287	The number of symbols to create on TEST_KALLSYMS_A, only one of which
3288	module TEST_KALLSYMS_B will use. This also will be used
3289	for how many symbols TEST_KALLSYMS_C will have, scaled up by
3290	TEST_KALLSYMS_SCALE_FACTOR. Note that setting this to 10,000 will
3291	trigger a segfault today, don't use anything close to it unless
3292	you are aware that this should not be used for automated build tests.
3293
3294	config TEST_KALLSYMS_SCALE_FACTOR
3295	int "test kallsyms scale factor"
3296	default 8
3297	help
3298	How many more unusued symbols will TEST_KALLSYSMS_C have than
3299	TEST_KALLSYMS_A. If 8, then module C will have 8 * syms
3300	than module A. Then TEST_KALLSYMS_D will have double the amount
3301	of symbols than C so to allow projections.
3302
3303	endif # TEST_KALLSYMS
3304
3305	config TEST_DEBUG_VIRTUAL
3306	tristate "Test CONFIG_DEBUG_VIRTUAL feature"
3307	depends on DEBUG_VIRTUAL
3308	help
3309	Test the kernel's ability to detect incorrect calls to
3310	virt_to_phys() done against the non-linear part of the
3311	kernel's virtual address map.
3312
3313	If unsure, say N.
3314
3315	config TEST_MEMCAT_P
3316	tristate "Test memcat_p() helper function"
3317	help
3318	Test the memcat_p() helper for correctly merging two
3319	pointer arrays together.
3320
3321	If unsure, say N.
3322
3323	config TEST_OBJAGG
3324	tristate "Perform selftest on object aggreration manager"
3325	default n
3326	depends on OBJAGG
3327	help
3328	Enable this option to test object aggregation manager on boot
3329	(or module load).
3330
3331	config TEST_MEMINIT
3332	tristate "Test heap/page initialization"
3333	help
3334	Test if the kernel is zero-initializing heap and page allocations.
3335	This can be useful to test init_on_alloc and init_on_free features.
3336
3337	If unsure, say N.
3338
3339	config TEST_HMM
3340	tristate "Test HMM (Heterogeneous Memory Management)"
3341	depends on TRANSPARENT_HUGEPAGE
3342	depends on DEVICE_PRIVATE
3343	select HMM_MIRROR
3344	select MMU_NOTIFIER
3345	help
3346	This is a pseudo device driver solely for testing HMM.
3347	Say M here if you want to build the HMM test module.
3348	Doing so will allow you to run tools/testing/selftest/vm/hmm-tests.
3349
3350	If unsure, say N.
3351
3352	config TEST_FREE_PAGES
3353	tristate "Test freeing pages"
3354	help
3355	Test that a memory leak does not occur due to a race between
3356	freeing a block of pages and a speculative page reference.
3357	Loading this module is safe if your kernel has the bug fixed.
3358	If the bug is not fixed, it will leak gigabytes of memory and
3359	probably OOM your system.
3360
3361	config TEST_FPU
3362	tristate "Test floating point operations in kernel space"
3363	depends on ARCH_HAS_KERNEL_FPU_SUPPORT && !KCOV_INSTRUMENT_ALL
3364	help
3365	Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu
3366	which will trigger a sequence of floating point operations. This is used
3367	for self-testing floating point control register setting in
3368	kernel_fpu_begin().
3369
3370	If unsure, say N.
3371
3372	config TEST_CLOCKSOURCE_WATCHDOG
3373	tristate "Test clocksource watchdog in kernel space"
3374	depends on CLOCKSOURCE_WATCHDOG
3375	help
3376	Enable this option to create a kernel module that will trigger
3377	a test of the clocksource watchdog. This module may be loaded
3378	via modprobe or insmod in which case it will run upon being
3379	loaded, or it may be built in, in which case it will run
3380	shortly after boot.
3381
3382	If unsure, say N.
3383
3384	config TEST_OBJPOOL
3385	tristate "Test module for correctness and stress of objpool"
3386	default n
3387	depends on m && DEBUG_KERNEL
3388	help
3389	This builds the "test_objpool" module that should be used for
3390	correctness verification and concurrent testings of objects
3391	allocation and reclamation.
3392
3393	If unsure, say N.
3394
3395	config TEST_KEXEC_HANDOVER
3396	bool "Test for Kexec HandOver"
3397	default n
3398	depends on KEXEC_HANDOVER
3399	help
3400	This option enables test for Kexec HandOver (KHO).
3401	The test consists of two parts: saving kernel data before kexec and
3402	restoring the data after kexec and verifying that it was properly
3403	handed over. This test module creates and saves data on the boot of
3404	the first kernel and restores and verifies the data on the boot of
3405	kexec'ed kernel.
3406
3407	For detailed documentation about KHO, see Documentation/core-api/kho.
3408
3409	To run the test run:
3410
3411	tools/testing/selftests/kho/vmtest.sh -h
3412
3413	If unsure, say N.
3414
3415	config RATELIMIT_KUNIT_TEST
3416	tristate "KUnit Test for correctness and stress of ratelimit" if !KUNIT_ALL_TESTS
3417	depends on KUNIT
3418	default KUNIT_ALL_TESTS
3419	help
3420	This builds the "test_ratelimit" module that should be used
3421	for correctness verification and concurrent testings of rate
3422	limiting.
3423
3424	If unsure, say N.
3425
3426	config UUID_KUNIT_TEST
3427	tristate "KUnit test for UUID" if !KUNIT_ALL_TESTS
3428	depends on KUNIT
3429	default KUNIT_ALL_TESTS
3430	help
3431	This option enables the KUnit test suite for the uuid library,
3432	which provides functions for generating and parsing UUID and GUID.
3433	The test suite checks parsing of UUID and GUID strings.
3434
3435	If unsure, say N.
3436
3437	config INT_POW_KUNIT_TEST
3438	tristate "Integer exponentiation (int_pow) test" if !KUNIT_ALL_TESTS
3439	depends on KUNIT
3440	default KUNIT_ALL_TESTS
3441	help
3442	This option enables the KUnit test suite for the int_pow function,
3443	which performs integer exponentiation. The test suite is designed to
3444	verify that the implementation of int_pow correctly computes the power
3445	of a given base raised to a given exponent.
3446
3447	Enabling this option will include tests that check various scenarios
3448	and edge cases to ensure the accuracy and reliability of the exponentiation
3449	function.
3450
3451	If unsure, say N
3452
3453	config INT_SQRT_KUNIT_TEST
3454	tristate "Integer square root test" if !KUNIT_ALL_TESTS
3455	depends on KUNIT
3456	default KUNIT_ALL_TESTS
3457	help
3458	This option enables the KUnit test suite for the int_sqrt() function,
3459	which performs square root calculation. The test suite checks
3460	various scenarios, including edge cases, to ensure correctness.
3461
3462	Enabling this option will include tests that check various scenarios
3463	and edge cases to ensure the accuracy and reliability of the square root
3464	function.
3465
3466	If unsure, say N
3467
3468	config INT_LOG_KUNIT_TEST
3469	tristate "Integer log (int_log) test" if !KUNIT_ALL_TESTS
3470	depends on KUNIT
3471	default KUNIT_ALL_TESTS
3472	help
3473	This option enables the KUnit test suite for the int_log library, which
3474	provides two functions to compute the integer logarithm in base 2 and
3475	base 10, called respectively as intlog2 and intlog10.
3476
3477	If unsure, say N
3478
3479	config GCD_KUNIT_TEST
3480	tristate "Greatest common divisor test" if !KUNIT_ALL_TESTS
3481	depends on KUNIT
3482	default KUNIT_ALL_TESTS
3483	help
3484	This option enables the KUnit test suite for the gcd() function,
3485	which computes the greatest common divisor of two numbers.
3486
3487	This test suite verifies the correctness of gcd() across various
3488	scenarios, including edge cases.
3489
3490	If unsure, say N
3491
3492	config PRIME_NUMBERS_KUNIT_TEST
3493	tristate "Prime number generator test" if !KUNIT_ALL_TESTS
3494	depends on KUNIT
3495	depends on PRIME_NUMBERS
3496	default KUNIT_ALL_TESTS
3497	help
3498	This option enables the KUnit test suite for the {is,next}_prime_number
3499	functions.
3500
3501	Enabling this option will include tests that compare the prime number
3502	generator functions against a brute force implementation.
3503
3504	If unsure, say N
3505
3506	config GLOB_KUNIT_TEST
3507	tristate "Glob matching test" if !KUNIT_ALL_TESTS
3508	depends on GLOB
3509	depends on KUNIT
3510	default KUNIT_ALL_TESTS
3511	help
3512	Enable this option to test the glob functions at runtime.
3513
3514	This test suite verifies the correctness of glob_match() across various
3515	scenarios, including edge cases.
3516
3517	If unsure, say N
3518
3519	endif # RUNTIME_TESTING_MENU
3520
3521	config ARCH_USE_MEMTEST
3522	bool
3523	help
3524	An architecture should select this when it uses early_memtest()
3525	during boot process.
3526
3527	config MEMTEST
3528	bool "Memtest"
3529	depends on ARCH_USE_MEMTEST
3530	help
3531	This option adds a kernel parameter 'memtest', which allows memtest
3532	to be set and executed.
3533	memtest=0, mean disabled; -- default
3534	memtest=1, mean do 1 test pattern;
3535	...
3536	memtest=17, mean do 17 test patterns.
3537	If you are unsure how to answer this question, answer N.
3538
3539
3540
3541	config HYPERV_TESTING
3542	bool "Microsoft Hyper-V driver testing"
3543	default n
3544	depends on HYPERV && DEBUG_FS
3545	help
3546	Select this option to enable Hyper-V vmbus testing.
3547
3548	endmenu # "Kernel Testing and Coverage"
3549
3550	menu "Rust hacking"
3551
3552	config RUST_DEBUG_ASSERTIONS
3553	bool "Debug assertions"
3554	depends on RUST
3555	help
3556	Enables rustc's `-Cdebug-assertions` codegen option.
3557
3558	This flag lets you turn `cfg(debug_assertions)` conditional
3559	compilation on or off. This can be used to enable extra debugging
3560	code in development but not in production. For example, it controls
3561	the behavior of the standard library's `debug_assert!` macro.
3562
3563	Note that this will apply to all Rust code, including `core`.
3564
3565	If unsure, say N.
3566
3567	config RUST_OVERFLOW_CHECKS
3568	bool "Overflow checks"
3569	default y
3570	depends on RUST
3571	help
3572	Enables rustc's `-Coverflow-checks` codegen option.
3573
3574	This flag allows you to control the behavior of runtime integer
3575	overflow. When overflow-checks are enabled, a Rust panic will occur
3576	on overflow.
3577
3578	Note that this will apply to all Rust code, including `core`.
3579
3580	If unsure, say Y.
3581
3582	config RUST_BUILD_ASSERT_ALLOW
3583	bool "Allow unoptimized build-time assertions"
3584	depends on RUST
3585	help
3586	Controls how `build_error!` and `build_assert!` are handled during the build.
3587
3588	If calls to them exist in the binary, it may indicate a violated invariant
3589	or that the optimizer failed to verify the invariant during compilation.
3590
3591	This should not happen, thus by default the build is aborted. However,
3592	as an escape hatch, you can choose Y here to ignore them during build
3593	and let the check be carried at runtime (with `panic!` being called if
3594	the check fails).
3595
3596	If unsure, say N.
3597
3598	config RUST_KERNEL_DOCTESTS
3599	bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS
3600	depends on RUST && KUNIT=y
3601	default KUNIT_ALL_TESTS
3602	help
3603	This builds the documentation tests of the `kernel` crate
3604	as KUnit tests.
3605
3606	For more information on KUnit and unit tests in general,
3607	please refer to the KUnit documentation in Documentation/dev-tools/kunit/.
3608
3609	If unsure, say N.
3610
3611	config RUST_INLINE_HELPERS
3612	bool "Inline C helpers into Rust code (EXPERIMENTAL)"
3613	depends on RUST && RUSTC_CLANG_LLVM_COMPATIBLE
3614	depends on EXPERT
3615	depends on ARM64 \|\| X86_64
3616	depends on !UML
3617	help
3618	Inlines C helpers into Rust code using Link Time Optimization.
3619
3620	If this option is enabled, C helper functions declared in
3621	rust/helpers/ are inlined into Rust code, which is helpful for
3622	performance of Rust code. This requires a matching LLVM version for
3623	Clang and rustc.
3624
3625	If you are sure that you're using Clang and rustc with matching LLVM
3626	versions, say Y. Otherwise say N.
3627
3628	endmenu # "Rust"
3629
3630	endmenu # Kernel hacking