linux - lib/Kconfig.debug

3411 lines · 111.2 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 STACKTRACE_BUILD_ID
39	bool "Show build ID information in stacktraces"
40	depends on PRINTK
41	help
42	Selecting this option adds build ID information for symbols in
43	stacktraces printed with the printk format '%p[SR]b'.
44
45	This option is intended for distros where debuginfo is not easily
46	accessible but can be downloaded given the build ID of the vmlinux or
47	kernel module where the function is located.
48
49	config CONSOLE_LOGLEVEL_DEFAULT
50	int "Default console loglevel (1-15)"
51	range 1 15
52	default "7"
53	help
54	Default loglevel to determine what will be printed on the console.
55
56	Setting a default here is equivalent to passing in loglevel=<x> in
57	the kernel bootargs. loglevel=<x> continues to override whatever
58	value is specified here as well.
59
60	Note: This does not affect the log level of un-prefixed printk()
61	usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT
62	option.
63
64	config CONSOLE_LOGLEVEL_QUIET
65	int "quiet console loglevel (1-15)"
66	range 1 15
67	default "4"
68	help
69	loglevel to use when "quiet" is passed on the kernel commandline.
70
71	When "quiet" is passed on the kernel commandline this loglevel
72	will be used as the loglevel. IOW passing "quiet" will be the
73	equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>"
74
75	config MESSAGE_LOGLEVEL_DEFAULT
76	int "Default message log level (1-7)"
77	range 1 7
78	default "4"
79	help
80	Default log level for printk statements with no specified priority.
81
82	This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
83	that are auditing their logs closely may want to set it to a lower
84	priority.
85
86	Note: This does not affect what message level gets printed on the console
87	by default. To change that, use loglevel=<x> in the kernel bootargs,
88	or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value.
89
90	config BOOT_PRINTK_DELAY
91	bool "Delay each boot printk message by N milliseconds"
92	depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
93	help
94	This build option allows you to read kernel boot messages
95	by inserting a short delay after each one. The delay is
96	specified in milliseconds on the kernel command line,
97	using "boot_delay=N".
98
99	It is likely that you would also need to use "lpj=M" to preset
100	the "loops per jiffy" value.
101	See a previous boot log for the "lpj" value to use for your
102	system, and then set "lpj=M" before setting "boot_delay=N".
103	NOTE: Using this option may adversely affect SMP systems.
104	I.e., processors other than the first one may not boot up.
105	BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
106	what it believes to be lockup conditions.
107
108	config DYNAMIC_DEBUG
109	bool "Enable dynamic printk() support"
110	default n
111	depends on PRINTK
112	depends on (DEBUG_FS \|\| PROC_FS)
113	select DYNAMIC_DEBUG_CORE
114	help
115
116	Compiles debug level messages into the kernel, which would not
117	otherwise be available at runtime. These messages can then be
118	enabled/disabled based on various levels of scope - per source file,
119	function, module, format string, and line number. This mechanism
120	implicitly compiles in all pr_debug() and dev_dbg() calls, which
121	enlarges the kernel text size by about 2%.
122
123	If a source file is compiled with DEBUG flag set, any
124	pr_debug() calls in it are enabled by default, but can be
125	disabled at runtime as below. Note that DEBUG flag is
126	turned on by many CONFIG_DEBUG options.
127
128	Usage:
129
130	Dynamic debugging is controlled via the 'dynamic_debug/control' file,
131	which is contained in the 'debugfs' filesystem or procfs.
132	Thus, the debugfs or procfs filesystem must first be mounted before
133	making use of this feature.
134	We refer the control file as: <debugfs>/dynamic_debug/control. This
135	file contains a list of the debug statements that can be enabled. The
136	format for each line of the file is:
137
138	filename:lineno [module]function flags format
139
140	filename : source file of the debug statement
141	lineno : line number of the debug statement
142	module : module that contains the debug statement
143	function : function that contains the debug statement
144	flags : '=p' means the line is turned 'on' for printing
145	format : the format used for the debug statement
146
147	From a live system:
148
149	nullarbor:~ # cat <debugfs>/dynamic_debug/control
150	# filename:lineno [module]function flags format
151	fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
152	fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
153	fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
154
155	Example usage:
156
157	// enable the message at line 1603 of file svcsock.c
158	nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
159	<debugfs>/dynamic_debug/control
160
161	// enable all the messages in file svcsock.c
162	nullarbor:~ # echo -n 'file svcsock.c +p' >
163	<debugfs>/dynamic_debug/control
164
165	// enable all the messages in the NFS server module
166	nullarbor:~ # echo -n 'module nfsd +p' >
167	<debugfs>/dynamic_debug/control
168
169	// enable all 12 messages in the function svc_process()
170	nullarbor:~ # echo -n 'func svc_process +p' >
171	<debugfs>/dynamic_debug/control
172
173	// disable all 12 messages in the function svc_process()
174	nullarbor:~ # echo -n 'func svc_process -p' >
175	<debugfs>/dynamic_debug/control
176
177	See Documentation/admin-guide/dynamic-debug-howto.rst for additional
178	information.
179
180	config DYNAMIC_DEBUG_CORE
181	bool "Enable core function of dynamic debug support"
182	depends on PRINTK
183	depends on (DEBUG_FS \|\| PROC_FS)
184	help
185	Enable core functional support of dynamic debug. It is useful
186	when you want to tie dynamic debug to your kernel modules with
187	DYNAMIC_DEBUG_MODULE defined for each of them, especially for
188	the case of embedded system where the kernel image size is
189	sensitive for people.
190
191	config SYMBOLIC_ERRNAME
192	bool "Support symbolic error names in printf"
193	default y if PRINTK
194	help
195	If you say Y here, the kernel's printf implementation will
196	be able to print symbolic error names such as ENOSPC instead
197	of the number 28. It makes the kernel image slightly larger
198	(about 3KB), but can make the kernel logs easier to read.
199
200	config DEBUG_BUGVERBOSE
201	bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
202	depends on BUG && (GENERIC_BUG \|\| HAVE_DEBUG_BUGVERBOSE)
203	default y
204	help
205	Say Y here to make BUG() panics output the file name and line number
206	of the BUG call as well as the EIP and oops trace. This aids
207	debugging but costs about 70-100K of memory.
208
209	endmenu # "printk and dmesg options"
210
211	config DEBUG_KERNEL
212	bool "Kernel debugging"
213	help
214	Say Y here if you are developing drivers or trying to debug and
215	identify kernel problems.
216
217	config DEBUG_MISC
218	bool "Miscellaneous debug code"
219	default DEBUG_KERNEL
220	depends on DEBUG_KERNEL
221	help
222	Say Y here if you need to enable miscellaneous debug code that should
223	be under a more specific debug option but isn't.
224
225	menu "Compile-time checks and compiler options"
226
227	config DEBUG_INFO
228	bool
229	help
230	A kernel debug info option other than "None" has been selected
231	in the "Debug information" choice below, indicating that debug
232	information will be generated for build targets.
233
234	# Clang generates .uleb128 with label differences for DWARF v5, a feature that
235	# older binutils ports do not support when utilizing RISC-V style linker
236	# relaxation: https://sourceware.org/bugzilla/show_bug.cgi?id=27215
237	config AS_HAS_NON_CONST_ULEB128
238	def_bool $(as-instr,.uleb128 .Lexpr_end4 - .Lexpr_start3\n.Lexpr_start3:\n.Lexpr_end4:)
239
240	choice
241	prompt "Debug information"
242	depends on DEBUG_KERNEL
243	help
244	Selecting something other than "None" results in a kernel image
245	that will include debugging info resulting in a larger kernel image.
246	This adds debug symbols to the kernel and modules (gcc -g), and
247	is needed if you intend to use kernel crashdump or binary object
248	tools like crash, kgdb, LKCD, gdb, etc on the kernel.
249
250	Choose which version of DWARF debug info to emit. If unsure,
251	select "Toolchain default".
252
253	config DEBUG_INFO_NONE
254	bool "Disable debug information"
255	help
256	Do not build the kernel with debugging information, which will
257	result in a faster and smaller build.
258
259	config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
260	bool "Rely on the toolchain's implicit default DWARF version"
261	select DEBUG_INFO
262	depends on !CC_IS_CLANG \|\| AS_IS_LLVM \|\| CLANG_VERSION < 140000 \|\| (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128)
263	help
264	The implicit default version of DWARF debug info produced by a
265	toolchain changes over time.
266
267	This can break consumers of the debug info that haven't upgraded to
268	support newer revisions, and prevent testing newer versions, but
269	those should be less common scenarios.
270
271	config DEBUG_INFO_DWARF4
272	bool "Generate DWARF Version 4 debuginfo"
273	select DEBUG_INFO
274	depends on !CC_IS_CLANG \|\| AS_IS_LLVM \|\| (AS_IS_GNU && AS_VERSION >= 23502)
275	help
276	Generate DWARF v4 debug info. This requires gcc 4.5+, binutils 2.35.2
277	if using clang without clang's integrated assembler, and gdb 7.0+.
278
279	If you have consumers of DWARF debug info that are not ready for
280	newer revisions of DWARF, you may wish to choose this or have your
281	config select this.
282
283	config DEBUG_INFO_DWARF5
284	bool "Generate DWARF Version 5 debuginfo"
285	select DEBUG_INFO
286	depends on !ARCH_HAS_BROKEN_DWARF5
287	depends on !CC_IS_CLANG \|\| AS_IS_LLVM \|\| (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128)
288	help
289	Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc
290	5.0+ accepts the -gdwarf-5 flag but only had partial support for some
291	draft features until 7.0), and gdb 8.0+.
292
293	Changes to the structure of debug info in Version 5 allow for around
294	15-18% savings in resulting image and debug info section sizes as
295	compared to DWARF Version 4. DWARF Version 5 standardizes previous
296	extensions such as accelerators for symbol indexing and the format
297	for fission (.dwo/.dwp) files. Users may not want to select this
298	config if they rely on tooling that has not yet been updated to
299	support DWARF Version 5.
300
301	endchoice # "Debug information"
302
303	if DEBUG_INFO
304
305	config DEBUG_INFO_REDUCED
306	bool "Reduce debugging information"
307	help
308	If you say Y here gcc is instructed to generate less debugging
309	information for structure types. This means that tools that
310	need full debugging information (like kgdb or systemtap) won't
311	be happy. But if you merely need debugging information to
312	resolve line numbers there is no loss. Advantage is that
313	build directory object sizes shrink dramatically over a full
314	DEBUG_INFO build and compile times are reduced too.
315	Only works with newer gcc versions.
316
317	choice
318	prompt "Compressed Debug information"
319	help
320	Compress the resulting debug info. Results in smaller debug info sections,
321	but requires that consumers are able to decompress the results.
322
323	If unsure, choose DEBUG_INFO_COMPRESSED_NONE.
324
325	config DEBUG_INFO_COMPRESSED_NONE
326	bool "Don't compress debug information"
327	help
328	Don't compress debug info sections.
329
330	config DEBUG_INFO_COMPRESSED_ZLIB
331	bool "Compress debugging information with zlib"
332	depends on $(cc-option,-gz=zlib)
333	depends on $(ld-option,--compress-debug-sections=zlib)
334	help
335	Compress the debug information using zlib. Requires GCC 5.0+ or Clang
336	5.0+, binutils 2.26+, and zlib.
337
338	Users of dpkg-deb via debian/rules may find an increase in
339	size of their debug .deb packages with this config set, due to the
340	debug info being compressed with zlib, then the object files being
341	recompressed with a different compression scheme. But this is still
342	preferable to setting KDEB_COMPRESS or DPKG_DEB_COMPRESSOR_TYPE to
343	"none" which would be even larger.
344
345	config DEBUG_INFO_COMPRESSED_ZSTD
346	bool "Compress debugging information with zstd"
347	depends on $(cc-option,-gz=zstd)
348	depends on $(ld-option,--compress-debug-sections=zstd)
349	help
350	Compress the debug information using zstd. This may provide better
351	compression than zlib, for about the same time costs, but requires newer
352	toolchain support. Requires GCC 13.0+ or Clang 16.0+, binutils 2.40+, and
353	zstd.
354
355	endchoice # "Compressed Debug information"
356
357	config DEBUG_INFO_SPLIT
358	bool "Produce split debuginfo in .dwo files"
359	depends on $(cc-option,-gsplit-dwarf)
360	# RISC-V linker relaxation + -gsplit-dwarf has issues with LLVM and GCC
361	# prior to 12.x:
362	# https://github.com/llvm/llvm-project/issues/56642
363	# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99090
364	depends on !RISCV \|\| GCC_VERSION >= 120000
365	help
366	Generate debug info into separate .dwo files. This significantly
367	reduces the build directory size for builds with DEBUG_INFO,
368	because it stores the information only once on disk in .dwo
369	files instead of multiple times in object files and executables.
370	In addition the debug information is also compressed.
371
372	Requires recent gcc (4.7+) and recent gdb/binutils.
373	Any tool that packages or reads debug information would need
374	to know about the .dwo files and include them.
375	Incompatible with older versions of ccache.
376
377	config DEBUG_INFO_BTF
378	bool "Generate BTF type information"
379	depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED
380	depends on !GCC_PLUGIN_RANDSTRUCT \|\| COMPILE_TEST
381	depends on BPF_SYSCALL
382	depends on PAHOLE_VERSION >= 116
383	depends on DEBUG_INFO_DWARF4 \|\| PAHOLE_VERSION >= 121
384	# pahole uses elfutils, which does not have support for Hexagon relocations
385	depends on !HEXAGON
386	help
387	Generate deduplicated BTF type information from DWARF debug info.
388	Turning this on requires pahole v1.16 or later (v1.21 or later to
389	support DWARF 5), which will convert DWARF type info into equivalent
390	deduplicated BTF type info.
391
392	config PAHOLE_HAS_SPLIT_BTF
393	def_bool PAHOLE_VERSION >= 119
394
395	config PAHOLE_HAS_BTF_TAG
396	def_bool PAHOLE_VERSION >= 123
397	depends on CC_IS_CLANG
398	help
399	Decide whether pahole emits btf_tag attributes (btf_type_tag and
400	btf_decl_tag) or not. Currently only clang compiler implements
401	these attributes, so make the config depend on CC_IS_CLANG.
402
403	config PAHOLE_HAS_LANG_EXCLUDE
404	def_bool PAHOLE_VERSION >= 124
405	help
406	Support for the --lang_exclude flag which makes pahole exclude
407	compilation units from the supplied language. Used in Kbuild to
408	omit Rust CUs which are not supported in version 1.24 of pahole,
409	otherwise it would emit malformed kernel and module binaries when
410	using DEBUG_INFO_BTF_MODULES.
411
412	config DEBUG_INFO_BTF_MODULES
413	bool "Generate BTF type information for kernel modules"
414	default y
415	depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF
416	help
417	Generate compact split BTF type information for kernel modules.
418
419	config MODULE_ALLOW_BTF_MISMATCH
420	bool "Allow loading modules with non-matching BTF type info"
421	depends on DEBUG_INFO_BTF_MODULES
422	help
423	For modules whose split BTF does not match vmlinux, load without
424	BTF rather than refusing to load. The default behavior with
425	module BTF enabled is to reject modules with such mismatches;
426	this option will still load module BTF where possible but ignore
427	it when a mismatch is found.
428
429	config GDB_SCRIPTS
430	bool "Provide GDB scripts for kernel debugging"
431	help
432	This creates the required links to GDB helper scripts in the
433	build directory. If you load vmlinux into gdb, the helper
434	scripts will be automatically imported by gdb as well, and
435	additional functions are available to analyze a Linux kernel
436	instance. See Documentation/process/debugging/gdb-kernel-debugging.rst
437	for further details.
438
439	endif # DEBUG_INFO
440
441	config FRAME_WARN
442	int "Warn for stack frames larger than"
443	range 0 8192
444	default 0 if KMSAN
445	default 2048 if GCC_PLUGIN_LATENT_ENTROPY
446	default 2048 if PARISC
447	default 1536 if (!64BIT && XTENSA)
448	default 1280 if KASAN && !64BIT
449	default 1024 if !64BIT
450	default 2048 if 64BIT
451	help
452	Tell the compiler to warn at build time for stack frames larger than this.
453	Setting this too low will cause a lot of warnings.
454	Setting it to 0 disables the warning.
455
456	config STRIP_ASM_SYMS
457	bool "Strip assembler-generated symbols during link"
458	default n
459	help
460	Strip internal assembler-generated symbols during a link (symbols
461	that look like '.Lxxx') so they don't pollute the output of
462	get_wchan() and suchlike.
463
464	config READABLE_ASM
465	bool "Generate readable assembler code"
466	depends on DEBUG_KERNEL
467	depends on CC_IS_GCC
468	help
469	Disable some compiler optimizations that tend to generate human unreadable
470	assembler output. This may make the kernel slightly slower, but it helps
471	to keep kernel developers who have to stare a lot at assembler listings
472	sane.
473
474	config HEADERS_INSTALL
475	bool "Install uapi headers to usr/include"
476	help
477	This option will install uapi headers (headers exported to user-space)
478	into the usr/include directory for use during the kernel build.
479	This is unneeded for building the kernel itself, but needed for some
480	user-space program samples. It is also needed by some features such
481	as uapi header sanity checks.
482
483	config DEBUG_SECTION_MISMATCH
484	bool "Enable full Section mismatch analysis"
485	depends on CC_IS_GCC
486	help
487	The section mismatch analysis checks if there are illegal
488	references from one section to another section.
489	During linktime or runtime, some sections are dropped;
490	any use of code/data previously in these sections would
491	most likely result in an oops.
492	In the code, functions and variables are annotated with
493	__init,, etc. (see the full list in include/linux/init.h),
494	which results in the code/data being placed in specific sections.
495	The section mismatch analysis is always performed after a full
496	kernel build, and enabling this option causes the following
497	additional step to occur:
498	- Add the option -fno-inline-functions-called-once to gcc commands.
499	When inlining a function annotated with __init in a non-init
500	function, we would lose the section information and thus
501	the analysis would not catch the illegal reference.
502	This option tells gcc to inline less (but it does result in
503	a larger kernel).
504
505	config SECTION_MISMATCH_WARN_ONLY
506	bool "Make section mismatch errors non-fatal"
507	default y
508	help
509	If you say N here, the build process will fail if there are any
510	section mismatch, instead of just throwing warnings.
511
512	If unsure, say Y.
513
514	config DEBUG_FORCE_FUNCTION_ALIGN_64B
515	bool "Force all function address 64B aligned"
516	depends on EXPERT && (X86_64 \|\| ARM64 \|\| PPC32 \|\| PPC64 \|\| ARC \|\| RISCV \|\| S390)
517	select FUNCTION_ALIGNMENT_64B
518	help
519	There are cases that a commit from one domain changes the function
520	address alignment of other domains, and cause magic performance
521	bump (regression or improvement). Enable this option will help to
522	verify if the bump is caused by function alignment changes, while
523	it will slightly increase the kernel size and affect icache usage.
524
525	It is mainly for debug and performance tuning use.
526
527	#
528	# Select this config option from the architecture Kconfig, if it
529	# is preferred to always offer frame pointers as a config
530	# option on the architecture (regardless of KERNEL_DEBUG):
531	#
532	config ARCH_WANT_FRAME_POINTERS
533	bool
534
535	config FRAME_POINTER
536	bool "Compile the kernel with frame pointers"
537	depends on DEBUG_KERNEL && (M68K \|\| UML \|\| SUPERH) \|\| ARCH_WANT_FRAME_POINTERS
538	default y if (DEBUG_INFO && UML) \|\| ARCH_WANT_FRAME_POINTERS
539	help
540	If you say Y here the resulting kernel image will be slightly
541	larger and slower, but it gives very useful debugging information
542	in case of kernel bugs. (precise oopses/stacktraces/warnings)
543
544	config OBJTOOL
545	bool
546
547	config OBJTOOL_WERROR
548	bool "Upgrade objtool warnings to errors"
549	depends on OBJTOOL && !COMPILE_TEST
550	help
551	Fail the build on objtool warnings.
552
553	Objtool warnings can indicate kernel instability, including boot
554	failures. This option is highly recommended.
555
556	If unsure, say Y.
557
558	config STACK_VALIDATION
559	bool "Compile-time stack metadata validation"
560	depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER
561	select OBJTOOL
562	default n
563	help
564	Validate frame pointer rules at compile-time. This helps ensure that
565	runtime stack traces are more reliable.
566
567	For more information, see
568	tools/objtool/Documentation/objtool.txt.
569
570	config NOINSTR_VALIDATION
571	bool
572	depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY
573	select OBJTOOL
574	default y
575
576	config VMLINUX_MAP
577	bool "Generate vmlinux.map file when linking"
578	depends on EXPERT
579	help
580	Selecting this option will pass "-Map=vmlinux.map" to ld
581	when linking vmlinux. That file can be useful for verifying
582	and debugging magic section games, and for seeing which
583	pieces of code get eliminated with
584	CONFIG_LD_DEAD_CODE_DATA_ELIMINATION.
585
586	config BUILTIN_MODULE_RANGES
587	bool "Generate address range information for builtin modules"
588	depends on !LTO
589	depends on VMLINUX_MAP
590	help
591	When modules are built into the kernel, there will be no module name
592	associated with its symbols in /proc/kallsyms. Tracers may want to
593	identify symbols by module name and symbol name regardless of whether
594	the module is configured as loadable or not.
595
596	This option generates modules.builtin.ranges in the build tree with
597	offset ranges (per ELF section) for the module(s) they belong to.
598	It also records an anchor symbol to determine the load address of the
599	section.
600
601	config DEBUG_FORCE_WEAK_PER_CPU
602	bool "Force weak per-cpu definitions"
603	depends on DEBUG_KERNEL
604	help
605	s390 and alpha require percpu variables in modules to be
606	defined weak to work around addressing range issue which
607	puts the following two restrictions on percpu variable
608	definitions.
609
610	1. percpu symbols must be unique whether static or not
611	2. percpu variables can't be defined inside a function
612
613	To ensure that generic code follows the above rules, this
614	option forces all percpu variables to be defined as weak.
615
616	endmenu # "Compiler options"
617
618	menu "Generic Kernel Debugging Instruments"
619
620	config MAGIC_SYSRQ
621	bool "Magic SysRq key"
622	depends on !UML
623	help
624	If you say Y here, you will have some control over the system even
625	if the system crashes for example during kernel debugging (e.g., you
626	will be able to flush the buffer cache to disk, reboot the system
627	immediately or dump some status information). This is accomplished
628	by pressing various keys while holding SysRq (Alt+PrintScreen). It
629	also works on a serial console (on PC hardware at least), if you
630	send a BREAK and then within 5 seconds a command keypress. The
631	keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
632	Don't say Y unless you really know what this hack does.
633
634	config MAGIC_SYSRQ_DEFAULT_ENABLE
635	hex "Enable magic SysRq key functions by default"
636	depends on MAGIC_SYSRQ
637	default 0x1
638	help
639	Specifies which SysRq key functions are enabled by default.
640	This may be set to 1 or 0 to enable or disable them all, or
641	to a bitmask as described in Documentation/admin-guide/sysrq.rst.
642
643	config MAGIC_SYSRQ_SERIAL
644	bool "Enable magic SysRq key over serial"
645	depends on MAGIC_SYSRQ
646	default y
647	help
648	Many embedded boards have a disconnected TTL level serial which can
649	generate some garbage that can lead to spurious false sysrq detects.
650	This option allows you to decide whether you want to enable the
651	magic SysRq key.
652
653	config MAGIC_SYSRQ_SERIAL_SEQUENCE
654	string "Char sequence that enables magic SysRq over serial"
655	depends on MAGIC_SYSRQ_SERIAL
656	default ""
657	help
658	Specifies a sequence of characters that can follow BREAK to enable
659	SysRq on a serial console.
660
661	If unsure, leave an empty string and the option will not be enabled.
662
663	config DEBUG_FS
664	bool "Debug Filesystem"
665	help
666	debugfs is a virtual file system that kernel developers use to put
667	debugging files into. Enable this option to be able to read and
668	write to these files.
669
670	For detailed documentation on the debugfs API, see
671	Documentation/filesystems/.
672
673	If unsure, say N.
674
675	choice
676	prompt "Debugfs default access"
677	depends on DEBUG_FS
678	default DEBUG_FS_ALLOW_ALL
679	help
680	This selects the default access restrictions for debugfs.
681	It can be overridden with kernel command line option
682	debugfs=[on,no-mount,off]. The restrictions apply for API access
683	and filesystem registration.
684
685	config DEBUG_FS_ALLOW_ALL
686	bool "Access normal"
687	help
688	No restrictions apply. Both API and filesystem registration
689	is on. This is the normal default operation.
690
691	config DEBUG_FS_DISALLOW_MOUNT
692	bool "Do not register debugfs as filesystem"
693	help
694	The API is open but filesystem is not loaded. Clients can still do
695	their work and read with debug tools that do not need
696	debugfs filesystem.
697
698	config DEBUG_FS_ALLOW_NONE
699	bool "No access"
700	help
701	Access is off. Clients get -PERM when trying to create nodes in
702	debugfs tree and debugfs is not registered as a filesystem.
703	Client can then back-off or continue without debugfs access.
704
705	endchoice
706
707	source "lib/Kconfig.kgdb"
708	source "lib/Kconfig.ubsan"
709	source "lib/Kconfig.kcsan"
710
711	endmenu
712
713	menu "Networking Debugging"
714
715	source "net/Kconfig.debug"
716
717	endmenu # "Networking Debugging"
718
719	menu "Memory Debugging"
720
721	source "mm/Kconfig.debug"
722
723	config DEBUG_OBJECTS
724	bool "Debug object operations"
725	depends on DEBUG_KERNEL
726	help
727	If you say Y here, additional code will be inserted into the
728	kernel to track the life time of various objects and validate
729	the operations on those objects.
730
731	config DEBUG_OBJECTS_SELFTEST
732	bool "Debug objects selftest"
733	depends on DEBUG_OBJECTS
734	help
735	This enables the selftest of the object debug code.
736
737	config DEBUG_OBJECTS_FREE
738	bool "Debug objects in freed memory"
739	depends on DEBUG_OBJECTS
740	help
741	This enables checks whether a k/v free operation frees an area
742	which contains an object which has not been deactivated
743	properly. This can make kmalloc/kfree-intensive workloads
744	much slower.
745
746	config DEBUG_OBJECTS_TIMERS
747	bool "Debug timer objects"
748	depends on DEBUG_OBJECTS
749	help
750	If you say Y here, additional code will be inserted into the
751	timer routines to track the life time of timer objects and
752	validate the timer operations.
753
754	config DEBUG_OBJECTS_WORK
755	bool "Debug work objects"
756	depends on DEBUG_OBJECTS
757	help
758	If you say Y here, additional code will be inserted into the
759	work queue routines to track the life time of work objects and
760	validate the work operations.
761
762	config DEBUG_OBJECTS_RCU_HEAD
763	bool "Debug RCU callbacks objects"
764	depends on DEBUG_OBJECTS
765	help
766	Enable this to turn on debugging of RCU list heads (call_rcu() usage).
767
768	config DEBUG_OBJECTS_PERCPU_COUNTER
769	bool "Debug percpu counter objects"
770	depends on DEBUG_OBJECTS
771	help
772	If you say Y here, additional code will be inserted into the
773	percpu counter routines to track the life time of percpu counter
774	objects and validate the percpu counter operations.
775
776	config DEBUG_OBJECTS_ENABLE_DEFAULT
777	int "debug_objects bootup default value (0-1)"
778	range 0 1
779	default "1"
780	depends on DEBUG_OBJECTS
781	help
782	Debug objects boot parameter default value
783
784	config SHRINKER_DEBUG
785	bool "Enable shrinker debugging support"
786	depends on DEBUG_FS
787	help
788	Say Y to enable the shrinker debugfs interface which provides
789	visibility into the kernel memory shrinkers subsystem.
790	Disable it to avoid an extra memory footprint.
791
792	config DEBUG_STACK_USAGE
793	bool "Stack utilization instrumentation"
794	depends on DEBUG_KERNEL
795	help
796	Enables the display of the minimum amount of free stack which each
797	task has ever had available in the sysrq-T and sysrq-P debug output.
798	Also emits a message to dmesg when a process exits if that process
799	used more stack space than previously exiting processes.
800
801	This option will slow down process creation somewhat.
802
803	config SCHED_STACK_END_CHECK
804	bool "Detect stack corruption on calls to schedule()"
805	depends on DEBUG_KERNEL
806	default n
807	help
808	This option checks for a stack overrun on calls to schedule().
809	If the stack end location is found to be over written always panic as
810	the content of the corrupted region can no longer be trusted.
811	This is to ensure no erroneous behaviour occurs which could result in
812	data corruption or a sporadic crash at a later stage once the region
813	is examined. The runtime overhead introduced is minimal.
814
815	config ARCH_HAS_DEBUG_VM_PGTABLE
816	bool
817	help
818	An architecture should select this when it can successfully
819	build and run DEBUG_VM_PGTABLE.
820
821	config DEBUG_VFS
822	bool "Debug VFS"
823	depends on DEBUG_KERNEL
824	help
825	Enable this to turn on extended checks in the VFS layer that may impact
826	performance.
827
828	If unsure, say N.
829
830	config DEBUG_VM_IRQSOFF
831	def_bool DEBUG_VM && !PREEMPT_RT
832
833	config DEBUG_VM
834	bool "Debug VM"
835	depends on DEBUG_KERNEL
836	help
837	Enable this to turn on extended checks in the virtual-memory system
838	that may impact performance.
839
840	If unsure, say N.
841
842	config DEBUG_VM_SHOOT_LAZIES
843	bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation"
844	depends on DEBUG_VM
845	depends on MMU_LAZY_TLB_SHOOTDOWN
846	help
847	Enable additional IPIs that ensure lazy tlb mm references are removed
848	before the mm is freed.
849
850	If unsure, say N.
851
852	config DEBUG_VM_MAPLE_TREE
853	bool "Debug VM maple trees"
854	depends on DEBUG_VM
855	select DEBUG_MAPLE_TREE
856	help
857	Enable VM maple tree debugging information and extra validations.
858
859	If unsure, say N.
860
861	config DEBUG_VM_RB
862	bool "Debug VM red-black trees"
863	depends on DEBUG_VM
864	help
865	Enable VM red-black tree debugging information and extra validations.
866
867	If unsure, say N.
868
869	config DEBUG_VM_PGFLAGS
870	bool "Debug page-flags operations"
871	depends on DEBUG_VM
872	help
873	Enables extra validation on page flags operations.
874
875	If unsure, say N.
876
877	config DEBUG_VM_PGTABLE
878	bool "Debug arch page table for semantics compliance"
879	depends on MMU
880	depends on ARCH_HAS_DEBUG_VM_PGTABLE
881	default y if DEBUG_VM
882	help
883	This option provides a debug method which can be used to test
884	architecture page table helper functions on various platforms in
885	verifying if they comply with expected generic MM semantics. This
886	will help architecture code in making sure that any changes or
887	new additions of these helpers still conform to expected
888	semantics of the generic MM. Platforms will have to opt in for
889	this through ARCH_HAS_DEBUG_VM_PGTABLE.
890
891	If unsure, say N.
892
893	config ARCH_HAS_DEBUG_VIRTUAL
894	bool
895
896	config DEBUG_VIRTUAL
897	bool "Debug VM translations"
898	depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
899	help
900	Enable some costly sanity checks in virtual to page code. This can
901	catch mistakes with virt_to_page() and friends.
902
903	If unsure, say N.
904
905	config DEBUG_NOMMU_REGIONS
906	bool "Debug the global anon/private NOMMU mapping region tree"
907	depends on DEBUG_KERNEL && !MMU
908	help
909	This option causes the global tree of anonymous and private mapping
910	regions to be regularly checked for invalid topology.
911
912	config DEBUG_MEMORY_INIT
913	bool "Debug memory initialisation" if EXPERT
914	default !EXPERT
915	help
916	Enable this for additional checks during memory initialisation.
917	The sanity checks verify aspects of the VM such as the memory model
918	and other information provided by the architecture. Verbose
919	information will be printed at KERN_DEBUG loglevel depending
920	on the mminit_loglevel= command-line option.
921
922	If unsure, say Y
923
924	config MEMORY_NOTIFIER_ERROR_INJECT
925	tristate "Memory hotplug notifier error injection module"
926	depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION
927	help
928	This option provides the ability to inject artificial errors to
929	memory hotplug notifier chain callbacks. It is controlled through
930	debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
931
932	If the notifier call chain should be failed with some events
933	notified, write the error code to "actions/<notifier event>/error".
934
935	Example: Inject memory hotplug offline error (-12 == -ENOMEM)
936
937	# cd /sys/kernel/debug/notifier-error-inject/memory
938	# echo -12 > actions/MEM_GOING_OFFLINE/error
939	# echo offline > /sys/devices/system/memory/memoryXXX/state
940	bash: echo: write error: Cannot allocate memory
941
942	To compile this code as a module, choose M here: the module will
943	be called memory-notifier-error-inject.
944
945	If unsure, say N.
946
947	config DEBUG_PER_CPU_MAPS
948	bool "Debug access to per_cpu maps"
949	depends on DEBUG_KERNEL
950	depends on SMP
951	help
952	Say Y to verify that the per_cpu map being accessed has
953	been set up. This adds a fair amount of code to kernel memory
954	and decreases performance.
955
956	Say N if unsure.
957
958	config DEBUG_KMAP_LOCAL
959	bool "Debug kmap_local temporary mappings"
960	depends on DEBUG_KERNEL && KMAP_LOCAL
961	help
962	This option enables additional error checking for the kmap_local
963	infrastructure. Disable for production use.
964
965	config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
966	bool
967
968	config DEBUG_KMAP_LOCAL_FORCE_MAP
969	bool "Enforce kmap_local temporary mappings"
970	depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
971	select KMAP_LOCAL
972	select DEBUG_KMAP_LOCAL
973	help
974	This option enforces temporary mappings through the kmap_local
975	mechanism for non-highmem pages and on non-highmem systems.
976	Disable this for production systems!
977
978	config DEBUG_HIGHMEM
979	bool "Highmem debugging"
980	depends on DEBUG_KERNEL && HIGHMEM
981	select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
982	select DEBUG_KMAP_LOCAL
983	help
984	This option enables additional error checking for high memory
985	systems. Disable for production systems.
986
987	config HAVE_DEBUG_STACKOVERFLOW
988	bool
989
990	config DEBUG_STACKOVERFLOW
991	bool "Check for stack overflows"
992	depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
993	help
994	Say Y here if you want to check for overflows of kernel, IRQ
995	and exception stacks (if your architecture uses them). This
996	option will show detailed messages if free stack space drops
997	below a certain limit.
998
999	These kinds of bugs usually occur when call-chains in the
1000	kernel get too deep, especially when interrupts are
1001	involved.
1002
1003	Use this in cases where you see apparently random memory
1004	corruption, especially if it appears in 'struct thread_info'
1005
1006	If in doubt, say "N".
1007
1008	config CODE_TAGGING
1009	bool
1010	select KALLSYMS
1011
1012	config MEM_ALLOC_PROFILING
1013	bool "Enable memory allocation profiling"
1014	default n
1015	depends on MMU
1016	depends on PROC_FS
1017	depends on !DEBUG_FORCE_WEAK_PER_CPU
1018	select CODE_TAGGING
1019	select PAGE_EXTENSION
1020	select SLAB_OBJ_EXT
1021	help
1022	Track allocation source code and record total allocation size
1023	initiated at that code location. The mechanism can be used to track
1024	memory leaks with a low performance and memory impact.
1025
1026	config MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT
1027	bool "Enable memory allocation profiling by default"
1028	default y
1029	depends on MEM_ALLOC_PROFILING
1030
1031	config MEM_ALLOC_PROFILING_DEBUG
1032	bool "Memory allocation profiler debugging"
1033	default n
1034	depends on MEM_ALLOC_PROFILING
1035	select MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT
1036	help
1037	Adds warnings with helpful error messages for memory allocation
1038	profiling.
1039
1040	source "lib/Kconfig.kasan"
1041	source "lib/Kconfig.kfence"
1042	source "lib/Kconfig.kmsan"
1043
1044	endmenu # "Memory Debugging"
1045
1046	config DEBUG_SHIRQ
1047	bool "Debug shared IRQ handlers"
1048	depends on DEBUG_KERNEL
1049	help
1050	Enable this to generate a spurious interrupt just before a shared
1051	interrupt handler is deregistered (generating one when registering
1052	is currently disabled). Drivers need to handle this correctly. Some
1053	don't and need to be caught.
1054
1055	menu "Debug Oops, Lockups and Hangs"
1056
1057	config PANIC_ON_OOPS
1058	bool "Panic on Oops"
1059	help
1060	Say Y here to enable the kernel to panic when it oopses. This
1061	has the same effect as setting oops=panic on the kernel command
1062	line.
1063
1064	This feature is useful to ensure that the kernel does not do
1065	anything erroneous after an oops which could result in data
1066	corruption or other issues.
1067
1068	Say N if unsure.
1069
1070	config PANIC_ON_OOPS_VALUE
1071	int
1072	range 0 1
1073	default 0 if !PANIC_ON_OOPS
1074	default 1 if PANIC_ON_OOPS
1075
1076	config PANIC_TIMEOUT
1077	int "panic timeout"
1078	default 0
1079	help
1080	Set the timeout value (in seconds) until a reboot occurs when
1081	the kernel panics. If n = 0, then we wait forever. A timeout
1082	value n > 0 will wait n seconds before rebooting, while a timeout
1083	value n < 0 will reboot immediately. This setting can be overridden
1084	with the kernel command line option panic=, and from userspace via
1085	/proc/sys/kernel/panic.
1086
1087	config LOCKUP_DETECTOR
1088	bool
1089
1090	config SOFTLOCKUP_DETECTOR
1091	bool "Detect Soft Lockups"
1092	depends on DEBUG_KERNEL && !S390
1093	select LOCKUP_DETECTOR
1094	help
1095	Say Y here to enable the kernel to act as a watchdog to detect
1096	soft lockups.
1097
1098	Softlockups are bugs that cause the kernel to loop in kernel
1099	mode for more than 20 seconds, without giving other tasks a
1100	chance to run. The current stack trace is displayed upon
1101	detection and the system will stay locked up.
1102
1103	config SOFTLOCKUP_DETECTOR_INTR_STORM
1104	bool "Detect Interrupt Storm in Soft Lockups"
1105	depends on SOFTLOCKUP_DETECTOR && IRQ_TIME_ACCOUNTING
1106	select GENERIC_IRQ_STAT_SNAPSHOT
1107	default y if NR_CPUS <= 128
1108	help
1109	Say Y here to enable the kernel to detect interrupt storm
1110	during "soft lockups".
1111
1112	"soft lockups" can be caused by a variety of reasons. If one is
1113	caused by an interrupt storm, then the storming interrupts will not
1114	be on the callstack. To detect this case, it is necessary to report
1115	the CPU stats and the interrupt counts during the "soft lockups".
1116
1117	config BOOTPARAM_SOFTLOCKUP_PANIC
1118	bool "Panic (Reboot) On Soft Lockups"
1119	depends on SOFTLOCKUP_DETECTOR
1120	help
1121	Say Y here to enable the kernel to panic on "soft lockups",
1122	which are bugs that cause the kernel to loop in kernel
1123	mode for more than 20 seconds (configurable using the watchdog_thresh
1124	sysctl), without giving other tasks a chance to run.
1125
1126	The panic can be used in combination with panic_timeout,
1127	to cause the system to reboot automatically after a
1128	lockup has been detected. This feature is useful for
1129	high-availability systems that have uptime guarantees and
1130	where a lockup must be resolved ASAP.
1131
1132	Say N if unsure.
1133
1134	config HAVE_HARDLOCKUP_DETECTOR_BUDDY
1135	bool
1136	depends on SMP
1137	default y
1138
1139	#
1140	# Global switch whether to build a hardlockup detector at all. It is available
1141	# only when the architecture supports at least one implementation. There are
1142	# two exceptions. The hardlockup detector is never enabled on:
1143	#
1144	# s390: it reported many false positives there
1145	#
1146	# sparc64: has a custom implementation which is not using the common
1147	# hardlockup command line options and sysctl interface.
1148	#
1149	config HARDLOCKUP_DETECTOR
1150	bool "Detect Hard Lockups"
1151	depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64
1152	depends on HAVE_HARDLOCKUP_DETECTOR_PERF \|\| HAVE_HARDLOCKUP_DETECTOR_BUDDY \|\| HAVE_HARDLOCKUP_DETECTOR_ARCH
1153	imply HARDLOCKUP_DETECTOR_PERF
1154	imply HARDLOCKUP_DETECTOR_BUDDY
1155	imply HARDLOCKUP_DETECTOR_ARCH
1156	select LOCKUP_DETECTOR
1157
1158	help
1159	Say Y here to enable the kernel to act as a watchdog to detect
1160	hard lockups.
1161
1162	Hardlockups are bugs that cause the CPU to loop in kernel mode
1163	for more than 10 seconds, without letting other interrupts have a
1164	chance to run. The current stack trace is displayed upon detection
1165	and the system will stay locked up.
1166
1167	#
1168	# Note that arch-specific variants are always preferred.
1169	#
1170	config HARDLOCKUP_DETECTOR_PREFER_BUDDY
1171	bool "Prefer the buddy CPU hardlockup detector"
1172	depends on HARDLOCKUP_DETECTOR
1173	depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY
1174	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1175	help
1176	Say Y here to prefer the buddy hardlockup detector over the perf one.
1177
1178	With the buddy detector, each CPU uses its softlockup hrtimer
1179	to check that the next CPU is processing hrtimer interrupts by
1180	verifying that a counter is increasing.
1181
1182	This hardlockup detector is useful on systems that don't have
1183	an arch-specific hardlockup detector or if resources needed
1184	for the hardlockup detector are better used for other things.
1185
1186	config HARDLOCKUP_DETECTOR_PERF
1187	bool
1188	depends on HARDLOCKUP_DETECTOR
1189	depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY
1190	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1191	select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1192
1193	config HARDLOCKUP_DETECTOR_BUDDY
1194	bool
1195	depends on HARDLOCKUP_DETECTOR
1196	depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY
1197	depends on !HAVE_HARDLOCKUP_DETECTOR_PERF \|\| HARDLOCKUP_DETECTOR_PREFER_BUDDY
1198	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1199	select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1200
1201	config HARDLOCKUP_DETECTOR_ARCH
1202	bool
1203	depends on HARDLOCKUP_DETECTOR
1204	depends on HAVE_HARDLOCKUP_DETECTOR_ARCH
1205	help
1206	The arch-specific implementation of the hardlockup detector will
1207	be used.
1208
1209	#
1210	# Both the "perf" and "buddy" hardlockup detectors count hrtimer
1211	# interrupts. This config enables functions managing this common code.
1212	#
1213	config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1214	bool
1215	select SOFTLOCKUP_DETECTOR
1216
1217	#
1218	# Enables a timestamp based low pass filter to compensate for perf based
1219	# hard lockup detection which runs too fast due to turbo modes.
1220	#
1221	config HARDLOCKUP_CHECK_TIMESTAMP
1222	bool
1223
1224	config BOOTPARAM_HARDLOCKUP_PANIC
1225	bool "Panic (Reboot) On Hard Lockups"
1226	depends on HARDLOCKUP_DETECTOR
1227	help
1228	Say Y here to enable the kernel to panic on "hard lockups",
1229	which are bugs that cause the kernel to loop in kernel
1230	mode with interrupts disabled for more than 10 seconds (configurable
1231	using the watchdog_thresh sysctl).
1232
1233	Say N if unsure.
1234
1235	config DETECT_HUNG_TASK
1236	bool "Detect Hung Tasks"
1237	depends on DEBUG_KERNEL
1238	default SOFTLOCKUP_DETECTOR
1239	help
1240	Say Y here to enable the kernel to detect "hung tasks",
1241	which are bugs that cause the task to be stuck in
1242	uninterruptible "D" state indefinitely.
1243
1244	When a hung task is detected, the kernel will print the
1245	current stack trace (which you should report), but the
1246	task will stay in uninterruptible state. If lockdep is
1247	enabled then all held locks will also be reported. This
1248	feature has negligible overhead.
1249
1250	config DEFAULT_HUNG_TASK_TIMEOUT
1251	int "Default timeout for hung task detection (in seconds)"
1252	depends on DETECT_HUNG_TASK
1253	default 120
1254	help
1255	This option controls the default timeout (in seconds) used
1256	to determine when a task has become non-responsive and should
1257	be considered hung.
1258
1259	It can be adjusted at runtime via the kernel.hung_task_timeout_secs
1260	sysctl or by writing a value to
1261	/proc/sys/kernel/hung_task_timeout_secs.
1262
1263	A timeout of 0 disables the check. The default is two minutes.
1264	Keeping the default should be fine in most cases.
1265
1266	config BOOTPARAM_HUNG_TASK_PANIC
1267	bool "Panic (Reboot) On Hung Tasks"
1268	depends on DETECT_HUNG_TASK
1269	help
1270	Say Y here to enable the kernel to panic on "hung tasks",
1271	which are bugs that cause the kernel to leave a task stuck
1272	in uninterruptible "D" state.
1273
1274	The panic can be used in combination with panic_timeout,
1275	to cause the system to reboot automatically after a
1276	hung task has been detected. This feature is useful for
1277	high-availability systems that have uptime guarantees and
1278	where a hung tasks must be resolved ASAP.
1279
1280	Say N if unsure.
1281
1282	config DETECT_HUNG_TASK_BLOCKER
1283	bool "Dump Hung Tasks Blocker"
1284	depends on DETECT_HUNG_TASK
1285	depends on !PREEMPT_RT
1286	default y
1287	help
1288	Say Y here to show the blocker task's stacktrace who acquires
1289	the mutex lock which "hung tasks" are waiting.
1290	This will add overhead a bit but shows suspicious tasks and
1291	call trace if it comes from waiting a mutex.
1292
1293	config WQ_WATCHDOG
1294	bool "Detect Workqueue Stalls"
1295	depends on DEBUG_KERNEL
1296	help
1297	Say Y here to enable stall detection on workqueues. If a
1298	worker pool doesn't make forward progress on a pending work
1299	item for over a given amount of time, 30s by default, a
1300	warning message is printed along with dump of workqueue
1301	state. This can be configured through kernel parameter
1302	"workqueue.watchdog_thresh" and its sysfs counterpart.
1303
1304	config WQ_CPU_INTENSIVE_REPORT
1305	bool "Report per-cpu work items which hog CPU for too long"
1306	depends on DEBUG_KERNEL
1307	help
1308	Say Y here to enable reporting of concurrency-managed per-cpu work
1309	items that hog CPUs for longer than
1310	workqueue.cpu_intensive_thresh_us. Workqueue automatically
1311	detects and excludes them from concurrency management to prevent
1312	them from stalling other per-cpu work items. Occassional
1313	triggering may not necessarily indicate a problem. Repeated
1314	triggering likely indicates that the work item should be switched
1315	to use an unbound workqueue.
1316
1317	config TEST_LOCKUP
1318	tristate "Test module to generate lockups"
1319	depends on m
1320	help
1321	This builds the "test_lockup" module that helps to make sure
1322	that watchdogs and lockup detectors are working properly.
1323
1324	Depending on module parameters it could emulate soft or hard
1325	lockup, "hung task", or locking arbitrary lock for a long time.
1326	Also it could generate series of lockups with cooling-down periods.
1327
1328	If unsure, say N.
1329
1330	endmenu # "Debug lockups and hangs"
1331
1332	menu "Scheduler Debugging"
1333
1334	config SCHED_INFO
1335	bool
1336	default n
1337
1338	config SCHEDSTATS
1339	bool "Collect scheduler statistics"
1340	depends on PROC_FS
1341	select SCHED_INFO
1342	help
1343	If you say Y here, additional code will be inserted into the
1344	scheduler and related routines to collect statistics about
1345	scheduler behavior and provide them in /proc/schedstat. These
1346	stats may be useful for both tuning and debugging the scheduler
1347	If you aren't debugging the scheduler or trying to tune a specific
1348	application, you can say N to avoid the very slight overhead
1349	this adds.
1350
1351	endmenu
1352
1353	config DEBUG_PREEMPT
1354	bool "Debug preemptible kernel"
1355	depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT
1356	help
1357	If you say Y here then the kernel will use a debug variant of the
1358	commonly used smp_processor_id() function and will print warnings
1359	if kernel code uses it in a preemption-unsafe way. Also, the kernel
1360	will detect preemption count underflows.
1361
1362	This option has potential to introduce high runtime overhead,
1363	depending on workload as it triggers debugging routines for each
1364	this_cpu operation. It should only be used for debugging purposes.
1365
1366	menu "Lock Debugging (spinlocks, mutexes, etc...)"
1367
1368	config LOCK_DEBUGGING_SUPPORT
1369	bool
1370	depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1371	default y
1372
1373	config PROVE_LOCKING
1374	bool "Lock debugging: prove locking correctness"
1375	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1376	select LOCKDEP
1377	select DEBUG_SPINLOCK
1378	select DEBUG_MUTEXES if !PREEMPT_RT
1379	select DEBUG_RT_MUTEXES if RT_MUTEXES
1380	select DEBUG_RWSEMS if !PREEMPT_RT
1381	select DEBUG_WW_MUTEX_SLOWPATH
1382	select DEBUG_LOCK_ALLOC
1383	select PREEMPT_COUNT if !ARCH_NO_PREEMPT
1384	select TRACE_IRQFLAGS
1385	default n
1386	help
1387	This feature enables the kernel to prove that all locking
1388	that occurs in the kernel runtime is mathematically
1389	correct: that under no circumstance could an arbitrary (and
1390	not yet triggered) combination of observed locking
1391	sequences (on an arbitrary number of CPUs, running an
1392	arbitrary number of tasks and interrupt contexts) cause a
1393	deadlock.
1394
1395	In short, this feature enables the kernel to report locking
1396	related deadlocks before they actually occur.
1397
1398	The proof does not depend on how hard and complex a
1399	deadlock scenario would be to trigger: how many
1400	participant CPUs, tasks and irq-contexts would be needed
1401	for it to trigger. The proof also does not depend on
1402	timing: if a race and a resulting deadlock is possible
1403	theoretically (no matter how unlikely the race scenario
1404	is), it will be proven so and will immediately be
1405	reported by the kernel (once the event is observed that
1406	makes the deadlock theoretically possible).
1407
1408	If a deadlock is impossible (i.e. the locking rules, as
1409	observed by the kernel, are mathematically correct), the
1410	kernel reports nothing.
1411
1412	NOTE: this feature can also be enabled for rwlocks, mutexes
1413	and rwsems - in which case all dependencies between these
1414	different locking variants are observed and mapped too, and
1415	the proof of observed correctness is also maintained for an
1416	arbitrary combination of these separate locking variants.
1417
1418	For more details, see Documentation/locking/lockdep-design.rst.
1419
1420	config PROVE_RAW_LOCK_NESTING
1421	bool "Enable raw_spinlock - spinlock nesting checks" if !ARCH_SUPPORTS_RT
1422	depends on PROVE_LOCKING
1423	default y if ARCH_SUPPORTS_RT
1424	help
1425	Enable the raw_spinlock vs. spinlock nesting checks which ensure
1426	that the lock nesting rules for PREEMPT_RT enabled kernels are
1427	not violated.
1428
1429	config LOCK_STAT
1430	bool "Lock usage statistics"
1431	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1432	select LOCKDEP
1433	select DEBUG_SPINLOCK
1434	select DEBUG_MUTEXES if !PREEMPT_RT
1435	select DEBUG_RT_MUTEXES if RT_MUTEXES
1436	select DEBUG_LOCK_ALLOC
1437	default n
1438	help
1439	This feature enables tracking lock contention points
1440
1441	For more details, see Documentation/locking/lockstat.rst
1442
1443	This also enables lock events required by "perf lock",
1444	subcommand of perf.
1445	If you want to use "perf lock", you also need to turn on
1446	CONFIG_EVENT_TRACING.
1447
1448	CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1449	(CONFIG_LOCKDEP defines "acquire" and "release" events.)
1450
1451	config DEBUG_RT_MUTEXES
1452	bool "RT Mutex debugging, deadlock detection"
1453	depends on DEBUG_KERNEL && RT_MUTEXES
1454	help
1455	This allows rt mutex semantics violations and rt mutex related
1456	deadlocks (lockups) to be detected and reported automatically.
1457
1458	config DEBUG_SPINLOCK
1459	bool "Spinlock and rw-lock debugging: basic checks"
1460	depends on DEBUG_KERNEL
1461	select UNINLINE_SPIN_UNLOCK
1462	help
1463	Say Y here and build SMP to catch missing spinlock initialization
1464	and certain other kinds of spinlock errors commonly made. This is
1465	best used in conjunction with the NMI watchdog so that spinlock
1466	deadlocks are also debuggable.
1467
1468	config DEBUG_MUTEXES
1469	bool "Mutex debugging: basic checks"
1470	depends on DEBUG_KERNEL && !PREEMPT_RT
1471	help
1472	This feature allows mutex semantics violations to be detected and
1473	reported.
1474
1475	config DEBUG_WW_MUTEX_SLOWPATH
1476	bool "Wait/wound mutex debugging: Slowpath testing"
1477	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1478	select DEBUG_LOCK_ALLOC
1479	select DEBUG_SPINLOCK
1480	select DEBUG_MUTEXES if !PREEMPT_RT
1481	select DEBUG_RT_MUTEXES if PREEMPT_RT
1482	help
1483	This feature enables slowpath testing for w/w mutex users by
1484	injecting additional -EDEADLK wound/backoff cases. Together with
1485	the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1486	will test all possible w/w mutex interface abuse with the
1487	exception of simply not acquiring all the required locks.
1488	Note that this feature can introduce significant overhead, so
1489	it really should not be enabled in a production or distro kernel,
1490	even a debug kernel. If you are a driver writer, enable it. If
1491	you are a distro, do not.
1492
1493	config DEBUG_RWSEMS
1494	bool "RW Semaphore debugging: basic checks"
1495	depends on DEBUG_KERNEL && !PREEMPT_RT
1496	help
1497	This debugging feature allows mismatched rw semaphore locks
1498	and unlocks to be detected and reported.
1499
1500	config DEBUG_LOCK_ALLOC
1501	bool "Lock debugging: detect incorrect freeing of live locks"
1502	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1503	select DEBUG_SPINLOCK
1504	select DEBUG_MUTEXES if !PREEMPT_RT
1505	select DEBUG_RT_MUTEXES if RT_MUTEXES
1506	select LOCKDEP
1507	help
1508	This feature will check whether any held lock (spinlock, rwlock,
1509	mutex or rwsem) is incorrectly freed by the kernel, via any of the
1510	memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1511	vfree(), etc.), whether a live lock is incorrectly reinitialized via
1512	spin_lock_init()/mutex_init()/etc., or whether there is any lock
1513	held during task exit.
1514
1515	config LOCKDEP
1516	bool
1517	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1518	select STACKTRACE
1519	select KALLSYMS
1520	select KALLSYMS_ALL
1521
1522	config LOCKDEP_SMALL
1523	bool
1524
1525	config LOCKDEP_BITS
1526	int "Size for MAX_LOCKDEP_ENTRIES (as Nth power of 2)"
1527	depends on LOCKDEP && !LOCKDEP_SMALL
1528	range 10 24
1529	default 15
1530	help
1531	Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message.
1532
1533	config LOCKDEP_CHAINS_BITS
1534	int "Size for MAX_LOCKDEP_CHAINS (as Nth power of 2)"
1535	depends on LOCKDEP && !LOCKDEP_SMALL
1536	range 10 21
1537	default 16
1538	help
1539	Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message.
1540
1541	config LOCKDEP_STACK_TRACE_BITS
1542	int "Size for MAX_STACK_TRACE_ENTRIES (as Nth power of 2)"
1543	depends on LOCKDEP && !LOCKDEP_SMALL
1544	range 10 26
1545	default 19
1546	help
1547	Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message.
1548
1549	config LOCKDEP_STACK_TRACE_HASH_BITS
1550	int "Size for STACK_TRACE_HASH_SIZE (as Nth power of 2)"
1551	depends on LOCKDEP && !LOCKDEP_SMALL
1552	range 10 26
1553	default 14
1554	help
1555	Try increasing this value if you need large STACK_TRACE_HASH_SIZE.
1556
1557	config LOCKDEP_CIRCULAR_QUEUE_BITS
1558	int "Size for elements in circular_queue struct (as Nth power of 2)"
1559	depends on LOCKDEP
1560	range 10 26
1561	default 12
1562	help
1563	Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure.
1564
1565	config DEBUG_LOCKDEP
1566	bool "Lock dependency engine debugging"
1567	depends on DEBUG_KERNEL && LOCKDEP
1568	select DEBUG_IRQFLAGS
1569	help
1570	If you say Y here, the lock dependency engine will do
1571	additional runtime checks to debug itself, at the price
1572	of more runtime overhead.
1573
1574	config DEBUG_ATOMIC_SLEEP
1575	bool "Sleep inside atomic section checking"
1576	select PREEMPT_COUNT
1577	depends on DEBUG_KERNEL
1578	depends on !ARCH_NO_PREEMPT
1579	help
1580	If you say Y here, various routines which may sleep will become very
1581	noisy if they are called inside atomic sections: when a spinlock is
1582	held, inside an rcu read side critical section, inside preempt disabled
1583	sections, inside an interrupt, etc...
1584
1585	config DEBUG_LOCKING_API_SELFTESTS
1586	bool "Locking API boot-time self-tests"
1587	depends on DEBUG_KERNEL
1588	help
1589	Say Y here if you want the kernel to run a short self-test during
1590	bootup. The self-test checks whether common types of locking bugs
1591	are detected by debugging mechanisms or not. (if you disable
1592	lock debugging then those bugs won't be detected of course.)
1593	The following locking APIs are covered: spinlocks, rwlocks,
1594	mutexes and rwsems.
1595
1596	config LOCK_TORTURE_TEST
1597	tristate "torture tests for locking"
1598	depends on DEBUG_KERNEL
1599	select TORTURE_TEST
1600	help
1601	This option provides a kernel module that runs torture tests
1602	on kernel locking primitives. The kernel module may be built
1603	after the fact on the running kernel to be tested, if desired.
1604
1605	Say Y here if you want kernel locking-primitive torture tests
1606	to be built into the kernel.
1607	Say M if you want these torture tests to build as a module.
1608	Say N if you are unsure.
1609
1610	config WW_MUTEX_SELFTEST
1611	tristate "Wait/wound mutex selftests"
1612	help
1613	This option provides a kernel module that runs tests on the
1614	on the struct ww_mutex locking API.
1615
1616	It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1617	with this test harness.
1618
1619	Say M if you want these self tests to build as a module.
1620	Say N if you are unsure.
1621
1622	config SCF_TORTURE_TEST
1623	tristate "torture tests for smp_call_function*()"
1624	depends on DEBUG_KERNEL
1625	select TORTURE_TEST
1626	help
1627	This option provides a kernel module that runs torture tests
1628	on the smp_call_function() family of primitives. The kernel
1629	module may be built after the fact on the running kernel to
1630	be tested, if desired.
1631
1632	config CSD_LOCK_WAIT_DEBUG
1633	bool "Debugging for csd_lock_wait(), called from smp_call_function*()"
1634	depends on DEBUG_KERNEL
1635	depends on SMP
1636	depends on 64BIT
1637	default n
1638	help
1639	This option enables debug prints when CPUs are slow to respond
1640	to the smp_call_function*() IPI wrappers. These debug prints
1641	include the IPI handler function currently executing (if any)
1642	and relevant stack traces.
1643
1644	config CSD_LOCK_WAIT_DEBUG_DEFAULT
1645	bool "Default csd_lock_wait() debugging on at boot time"
1646	depends on CSD_LOCK_WAIT_DEBUG
1647	depends on 64BIT
1648	default n
1649	help
1650	This option causes the csdlock_debug= kernel boot parameter to
1651	default to 1 (basic debugging) instead of 0 (no debugging).
1652
1653	endmenu # lock debugging
1654
1655	config TRACE_IRQFLAGS
1656	depends on TRACE_IRQFLAGS_SUPPORT
1657	bool
1658	help
1659	Enables hooks to interrupt enabling and disabling for
1660	either tracing or lock debugging.
1661
1662	config TRACE_IRQFLAGS_NMI
1663	def_bool y
1664	depends on TRACE_IRQFLAGS
1665	depends on TRACE_IRQFLAGS_NMI_SUPPORT
1666
1667	config NMI_CHECK_CPU
1668	bool "Debugging for CPUs failing to respond to backtrace requests"
1669	depends on DEBUG_KERNEL
1670	depends on X86
1671	default n
1672	help
1673	Enables debug prints when a CPU fails to respond to a given
1674	backtrace NMI. These prints provide some reasons why a CPU
1675	might legitimately be failing to respond, for example, if it
1676	is offline of if ignore_nmis is set.
1677
1678	config DEBUG_IRQFLAGS
1679	bool "Debug IRQ flag manipulation"
1680	help
1681	Enables checks for potentially unsafe enabling or disabling of
1682	interrupts, such as calling raw_local_irq_restore() when interrupts
1683	are enabled.
1684
1685	config STACKTRACE
1686	bool "Stack backtrace support"
1687	depends on STACKTRACE_SUPPORT
1688	help
1689	This option causes the kernel to create a /proc/pid/stack for
1690	every process, showing its current stack trace.
1691	It is also used by various kernel debugging features that require
1692	stack trace generation.
1693
1694	config WARN_ALL_UNSEEDED_RANDOM
1695	bool "Warn for all uses of unseeded randomness"
1696	default n
1697	help
1698	Some parts of the kernel contain bugs relating to their use of
1699	cryptographically secure random numbers before it's actually possible
1700	to generate those numbers securely. This setting ensures that these
1701	flaws don't go unnoticed, by enabling a message, should this ever
1702	occur. This will allow people with obscure setups to know when things
1703	are going wrong, so that they might contact developers about fixing
1704	it.
1705
1706	Unfortunately, on some models of some architectures getting
1707	a fully seeded CRNG is extremely difficult, and so this can
1708	result in dmesg getting spammed for a surprisingly long
1709	time. This is really bad from a security perspective, and
1710	so architecture maintainers really need to do what they can
1711	to get the CRNG seeded sooner after the system is booted.
1712	However, since users cannot do anything actionable to
1713	address this, by default this option is disabled.
1714
1715	Say Y here if you want to receive warnings for all uses of
1716	unseeded randomness. This will be of use primarily for
1717	those developers interested in improving the security of
1718	Linux kernels running on their architecture (or
1719	subarchitecture).
1720
1721	config DEBUG_KOBJECT
1722	bool "kobject debugging"
1723	depends on DEBUG_KERNEL
1724	help
1725	If you say Y here, some extra kobject debugging messages will be sent
1726	to the syslog.
1727
1728	config DEBUG_KOBJECT_RELEASE
1729	bool "kobject release debugging"
1730	depends on DEBUG_OBJECTS_TIMERS
1731	help
1732	kobjects are reference counted objects. This means that their
1733	last reference count put is not predictable, and the kobject can
1734	live on past the point at which a driver decides to drop its
1735	initial reference to the kobject gained on allocation. An
1736	example of this would be a struct device which has just been
1737	unregistered.
1738
1739	However, some buggy drivers assume that after such an operation,
1740	the memory backing the kobject can be immediately freed. This
1741	goes completely against the principles of a refcounted object.
1742
1743	If you say Y here, the kernel will delay the release of kobjects
1744	on the last reference count to improve the visibility of this
1745	kind of kobject release bug.
1746
1747	config HAVE_DEBUG_BUGVERBOSE
1748	bool
1749
1750	menu "Debug kernel data structures"
1751
1752	config DEBUG_LIST
1753	bool "Debug linked list manipulation"
1754	depends on DEBUG_KERNEL
1755	select LIST_HARDENED
1756	help
1757	Enable this to turn on extended checks in the linked-list walking
1758	routines.
1759
1760	This option trades better quality error reports for performance, and
1761	is more suitable for kernel debugging. If you care about performance,
1762	you should only enable CONFIG_LIST_HARDENED instead.
1763
1764	If unsure, say N.
1765
1766	config DEBUG_PLIST
1767	bool "Debug priority linked list manipulation"
1768	depends on DEBUG_KERNEL
1769	help
1770	Enable this to turn on extended checks in the priority-ordered
1771	linked-list (plist) walking routines. This checks the entire
1772	list multiple times during each manipulation.
1773
1774	If unsure, say N.
1775
1776	config DEBUG_SG
1777	bool "Debug SG table operations"
1778	depends on DEBUG_KERNEL
1779	help
1780	Enable this to turn on checks on scatter-gather tables. This can
1781	help find problems with drivers that do not properly initialize
1782	their sg tables.
1783
1784	If unsure, say N.
1785
1786	config DEBUG_NOTIFIERS
1787	bool "Debug notifier call chains"
1788	depends on DEBUG_KERNEL
1789	help
1790	Enable this to turn on sanity checking for notifier call chains.
1791	This is most useful for kernel developers to make sure that
1792	modules properly unregister themselves from notifier chains.
1793	This is a relatively cheap check but if you care about maximum
1794	performance, say N.
1795
1796	config DEBUG_CLOSURES
1797	bool "Debug closures (bcache async widgits)"
1798	depends on CLOSURES
1799	select DEBUG_FS
1800	help
1801	Keeps all active closures in a linked list and provides a debugfs
1802	interface to list them, which makes it possible to see asynchronous
1803	operations that get stuck.
1804
1805	config DEBUG_MAPLE_TREE
1806	bool "Debug maple trees"
1807	depends on DEBUG_KERNEL
1808	help
1809	Enable maple tree debugging information and extra validations.
1810
1811	If unsure, say N.
1812
1813	endmenu
1814
1815	source "kernel/rcu/Kconfig.debug"
1816
1817	config DEBUG_WQ_FORCE_RR_CPU
1818	bool "Force round-robin CPU selection for unbound work items"
1819	depends on DEBUG_KERNEL
1820	default n
1821	help
1822	Workqueue used to implicitly guarantee that work items queued
1823	without explicit CPU specified are put on the local CPU. This
1824	guarantee is no longer true and while local CPU is still
1825	preferred work items may be put on foreign CPUs. Kernel
1826	parameter "workqueue.debug_force_rr_cpu" is added to force
1827	round-robin CPU selection to flush out usages which depend on the
1828	now broken guarantee. This config option enables the debug
1829	feature by default. When enabled, memory and cache locality will
1830	be impacted.
1831
1832	config CPU_HOTPLUG_STATE_CONTROL
1833	bool "Enable CPU hotplug state control"
1834	depends on DEBUG_KERNEL
1835	depends on HOTPLUG_CPU
1836	default n
1837	help
1838	Allows to write steps between "offline" and "online" to the CPUs
1839	sysfs target file so states can be stepped granular. This is a debug
1840	option for now as the hotplug machinery cannot be stopped and
1841	restarted at arbitrary points yet.
1842
1843	Say N if your are unsure.
1844
1845	config LATENCYTOP
1846	bool "Latency measuring infrastructure"
1847	depends on DEBUG_KERNEL
1848	depends on STACKTRACE_SUPPORT
1849	depends on PROC_FS
1850	depends on FRAME_POINTER \|\| MIPS \|\| PPC \|\| S390 \|\| MICROBLAZE \|\| ARM \|\| ARC \|\| X86
1851	select KALLSYMS
1852	select KALLSYMS_ALL
1853	select STACKTRACE
1854	select SCHEDSTATS
1855	help
1856	Enable this option if you want to use the LatencyTOP tool
1857	to find out which userspace is blocking on what kernel operations.
1858
1859	config DEBUG_CGROUP_REF
1860	bool "Disable inlining of cgroup css reference count functions"
1861	depends on DEBUG_KERNEL
1862	depends on CGROUPS
1863	depends on KPROBES
1864	default n
1865	help
1866	Force cgroup css reference count functions to not be inlined so
1867	that they can be kprobed for debugging.
1868
1869	source "kernel/trace/Kconfig"
1870
1871	config PROVIDE_OHCI1394_DMA_INIT
1872	bool "Remote debugging over FireWire early on boot"
1873	depends on PCI && X86
1874	help
1875	If you want to debug problems which hang or crash the kernel early
1876	on boot and the crashing machine has a FireWire port, you can use
1877	this feature to remotely access the memory of the crashed machine
1878	over FireWire. This employs remote DMA as part of the OHCI1394
1879	specification which is now the standard for FireWire controllers.
1880
1881	With remote DMA, you can monitor the printk buffer remotely using
1882	firescope and access all memory below 4GB using fireproxy from gdb.
1883	Even controlling a kernel debugger is possible using remote DMA.
1884
1885	Usage:
1886
1887	If ohci1394_dma=early is used as boot parameter, it will initialize
1888	all OHCI1394 controllers which are found in the PCI config space.
1889
1890	As all changes to the FireWire bus such as enabling and disabling
1891	devices cause a bus reset and thereby disable remote DMA for all
1892	devices, be sure to have the cable plugged and FireWire enabled on
1893	the debugging host before booting the debug target for debugging.
1894
1895	This code (~1k) is freed after boot. By then, the firewire stack
1896	in charge of the OHCI-1394 controllers should be used instead.
1897
1898	See Documentation/core-api/debugging-via-ohci1394.rst for more information.
1899
1900	source "samples/Kconfig"
1901
1902	config ARCH_HAS_DEVMEM_IS_ALLOWED
1903	bool
1904
1905	config STRICT_DEVMEM
1906	bool "Filter access to /dev/mem"
1907	depends on MMU && DEVMEM
1908	depends on ARCH_HAS_DEVMEM_IS_ALLOWED \|\| GENERIC_LIB_DEVMEM_IS_ALLOWED
1909	default y if PPC \|\| X86 \|\| ARM64 \|\| S390
1910	help
1911	If this option is disabled, you allow userspace (root) access to all
1912	of memory, including kernel and userspace memory. Accidental
1913	access to this is obviously disastrous, but specific access can
1914	be used by people debugging the kernel. Note that with PAT support
1915	enabled, even in this case there are restrictions on /dev/mem
1916	use due to the cache aliasing requirements.
1917
1918	If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
1919	file only allows userspace access to PCI space and the BIOS code and
1920	data regions. This is sufficient for dosemu and X and all common
1921	users of /dev/mem.
1922
1923	If in doubt, say Y.
1924
1925	config IO_STRICT_DEVMEM
1926	bool "Filter I/O access to /dev/mem"
1927	depends on STRICT_DEVMEM
1928	help
1929	If this option is disabled, you allow userspace (root) access to all
1930	io-memory regardless of whether a driver is actively using that
1931	range. Accidental access to this is obviously disastrous, but
1932	specific access can be used by people debugging kernel drivers.
1933
1934	If this option is switched on, the /dev/mem file only allows
1935	userspace access to idle io-memory ranges (see /proc/iomem) This
1936	may break traditional users of /dev/mem (dosemu, legacy X, etc...)
1937	if the driver using a given range cannot be disabled.
1938
1939	If in doubt, say Y.
1940
1941	menu "$(SRCARCH) Debugging"
1942
1943	source "arch/$(SRCARCH)/Kconfig.debug"
1944
1945	endmenu
1946
1947	menu "Kernel Testing and Coverage"
1948
1949	source "lib/kunit/Kconfig"
1950
1951	config NOTIFIER_ERROR_INJECTION
1952	tristate "Notifier error injection"
1953	depends on DEBUG_KERNEL
1954	select DEBUG_FS
1955	help
1956	This option provides the ability to inject artificial errors to
1957	specified notifier chain callbacks. It is useful to test the error
1958	handling of notifier call chain failures.
1959
1960	Say N if unsure.
1961
1962	config PM_NOTIFIER_ERROR_INJECT
1963	tristate "PM notifier error injection module"
1964	depends on PM && NOTIFIER_ERROR_INJECTION
1965	default m if PM_DEBUG
1966	help
1967	This option provides the ability to inject artificial errors to
1968	PM notifier chain callbacks. It is controlled through debugfs
1969	interface /sys/kernel/debug/notifier-error-inject/pm
1970
1971	If the notifier call chain should be failed with some events
1972	notified, write the error code to "actions/<notifier event>/error".
1973
1974	Example: Inject PM suspend error (-12 = -ENOMEM)
1975
1976	# cd /sys/kernel/debug/notifier-error-inject/pm/
1977	# echo -12 > actions/PM_SUSPEND_PREPARE/error
1978	# echo mem > /sys/power/state
1979	bash: echo: write error: Cannot allocate memory
1980
1981	To compile this code as a module, choose M here: the module will
1982	be called pm-notifier-error-inject.
1983
1984	If unsure, say N.
1985
1986	config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1987	tristate "OF reconfig notifier error injection module"
1988	depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1989	help
1990	This option provides the ability to inject artificial errors to
1991	OF reconfig notifier chain callbacks. It is controlled
1992	through debugfs interface under
1993	/sys/kernel/debug/notifier-error-inject/OF-reconfig/
1994
1995	If the notifier call chain should be failed with some events
1996	notified, write the error code to "actions/<notifier event>/error".
1997
1998	To compile this code as a module, choose M here: the module will
1999	be called of-reconfig-notifier-error-inject.
2000
2001	If unsure, say N.
2002
2003	config NETDEV_NOTIFIER_ERROR_INJECT
2004	tristate "Netdev notifier error injection module"
2005	depends on NET && NOTIFIER_ERROR_INJECTION
2006	help
2007	This option provides the ability to inject artificial errors to
2008	netdevice notifier chain callbacks. It is controlled through debugfs
2009	interface /sys/kernel/debug/notifier-error-inject/netdev
2010
2011	If the notifier call chain should be failed with some events
2012	notified, write the error code to "actions/<notifier event>/error".
2013
2014	Example: Inject netdevice mtu change error (-22 = -EINVAL)
2015
2016	# cd /sys/kernel/debug/notifier-error-inject/netdev
2017	# echo -22 > actions/NETDEV_CHANGEMTU/error
2018	# ip link set eth0 mtu 1024
2019	RTNETLINK answers: Invalid argument
2020
2021	To compile this code as a module, choose M here: the module will
2022	be called netdev-notifier-error-inject.
2023
2024	If unsure, say N.
2025
2026	config FUNCTION_ERROR_INJECTION
2027	bool "Fault-injections of functions"
2028	depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
2029	help
2030	Add fault injections into various functions that are annotated with
2031	ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return
2032	value of these functions. This is useful to test error paths of code.
2033
2034	If unsure, say N
2035
2036	config FAULT_INJECTION
2037	bool "Fault-injection framework"
2038	depends on DEBUG_KERNEL
2039	help
2040	Provide fault-injection framework.
2041	For more details, see Documentation/fault-injection/.
2042
2043	config FAILSLAB
2044	bool "Fault-injection capability for kmalloc"
2045	depends on FAULT_INJECTION
2046	help
2047	Provide fault-injection capability for kmalloc.
2048
2049	config FAIL_PAGE_ALLOC
2050	bool "Fault-injection capability for alloc_pages()"
2051	depends on FAULT_INJECTION
2052	help
2053	Provide fault-injection capability for alloc_pages().
2054
2055	config FAULT_INJECTION_USERCOPY
2056	bool "Fault injection capability for usercopy functions"
2057	depends on FAULT_INJECTION
2058	help
2059	Provides fault-injection capability to inject failures
2060	in usercopy functions (copy_from_user(), get_user(), ...).
2061
2062	config FAIL_MAKE_REQUEST
2063	bool "Fault-injection capability for disk IO"
2064	depends on FAULT_INJECTION && BLOCK
2065	help
2066	Provide fault-injection capability for disk IO.
2067
2068	config FAIL_IO_TIMEOUT
2069	bool "Fault-injection capability for faking disk interrupts"
2070	depends on FAULT_INJECTION && BLOCK
2071	help
2072	Provide fault-injection capability on end IO handling. This
2073	will make the block layer "forget" an interrupt as configured,
2074	thus exercising the error handling.
2075
2076	Only works with drivers that use the generic timeout handling,
2077	for others it won't do anything.
2078
2079	config FAIL_FUTEX
2080	bool "Fault-injection capability for futexes"
2081	select DEBUG_FS
2082	depends on FAULT_INJECTION && FUTEX
2083	help
2084	Provide fault-injection capability for futexes.
2085
2086	config FAULT_INJECTION_DEBUG_FS
2087	bool "Debugfs entries for fault-injection capabilities"
2088	depends on FAULT_INJECTION && SYSFS && DEBUG_FS
2089	help
2090	Enable configuration of fault-injection capabilities via debugfs.
2091
2092	config FAIL_FUNCTION
2093	bool "Fault-injection capability for functions"
2094	depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
2095	help
2096	Provide function-based fault-injection capability.
2097	This will allow you to override a specific function with a return
2098	with given return value. As a result, function caller will see
2099	an error value and have to handle it. This is useful to test the
2100	error handling in various subsystems.
2101
2102	config FAIL_MMC_REQUEST
2103	bool "Fault-injection capability for MMC IO"
2104	depends on FAULT_INJECTION_DEBUG_FS && MMC
2105	help
2106	Provide fault-injection capability for MMC IO.
2107	This will make the mmc core return data errors. This is
2108	useful to test the error handling in the mmc block device
2109	and to test how the mmc host driver handles retries from
2110	the block device.
2111
2112	config FAIL_SUNRPC
2113	bool "Fault-injection capability for SunRPC"
2114	depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG
2115	help
2116	Provide fault-injection capability for SunRPC and
2117	its consumers.
2118
2119	config FAIL_SKB_REALLOC
2120	bool "Fault-injection capability forcing skb to reallocate"
2121	depends on FAULT_INJECTION_DEBUG_FS
2122	help
2123	Provide fault-injection capability that forces the skb to be
2124	reallocated, catching possible invalid pointers to the skb.
2125
2126	For more information, check
2127	Documentation/fault-injection/fault-injection.rst
2128
2129	config FAULT_INJECTION_CONFIGFS
2130	bool "Configfs interface for fault-injection capabilities"
2131	depends on FAULT_INJECTION
2132	select CONFIGFS_FS
2133	help
2134	This option allows configfs-based drivers to dynamically configure
2135	fault-injection via configfs. Each parameter for driver-specific
2136	fault-injection can be made visible as a configfs attribute in a
2137	configfs group.
2138
2139
2140	config FAULT_INJECTION_STACKTRACE_FILTER
2141	bool "stacktrace filter for fault-injection capabilities"
2142	depends on FAULT_INJECTION
2143	depends on (FAULT_INJECTION_DEBUG_FS \|\| FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT
2144	select STACKTRACE
2145	depends on FRAME_POINTER \|\| MIPS \|\| PPC \|\| S390 \|\| MICROBLAZE \|\| ARM \|\| ARC \|\| X86
2146	help
2147	Provide stacktrace filter for fault-injection capabilities
2148
2149	config ARCH_HAS_KCOV
2150	bool
2151	help
2152	An architecture should select this when it can successfully
2153	build and run with CONFIG_KCOV. This typically requires
2154	disabling instrumentation for some early boot code.
2155
2156	config KCOV
2157	bool "Code coverage for fuzzing"
2158	depends on ARCH_HAS_KCOV
2159	depends on !ARCH_WANTS_NO_INSTR \|\| HAVE_NOINSTR_HACK \|\| \
2160	GCC_VERSION >= 120000 \|\| CC_IS_CLANG
2161	select DEBUG_FS
2162	select OBJTOOL if HAVE_NOINSTR_HACK
2163	help
2164	KCOV exposes kernel code coverage information in a form suitable
2165	for coverage-guided fuzzing (randomized testing).
2166
2167	For more details, see Documentation/dev-tools/kcov.rst.
2168
2169	config KCOV_ENABLE_COMPARISONS
2170	bool "Enable comparison operands collection by KCOV"
2171	depends on KCOV
2172	depends on $(cc-option,-fsanitize-coverage=trace-cmp)
2173	help
2174	KCOV also exposes operands of every comparison in the instrumented
2175	code along with operand sizes and PCs of the comparison instructions.
2176	These operands can be used by fuzzing engines to improve the quality
2177	of fuzzing coverage.
2178
2179	config KCOV_INSTRUMENT_ALL
2180	bool "Instrument all code by default"
2181	depends on KCOV
2182	default y
2183	help
2184	If you are doing generic system call fuzzing (like e.g. syzkaller),
2185	then you will want to instrument the whole kernel and you should
2186	say y here. If you are doing more targeted fuzzing (like e.g.
2187	filesystem fuzzing with AFL) then you will want to enable coverage
2188	for more specific subsets of files, and should say n here.
2189
2190	config KCOV_IRQ_AREA_SIZE
2191	hex "Size of interrupt coverage collection area in words"
2192	depends on KCOV
2193	default 0x40000
2194	help
2195	KCOV uses preallocated per-cpu areas to collect coverage from
2196	soft interrupts. This specifies the size of those areas in the
2197	number of unsigned long words.
2198
2199	config KCOV_SELFTEST
2200	bool "Perform short selftests on boot"
2201	depends on KCOV
2202	help
2203	Run short KCOV coverage collection selftests on boot.
2204	On test failure, causes the kernel to panic. Recommended to be
2205	enabled, ensuring critical functionality works as intended.
2206
2207	menuconfig RUNTIME_TESTING_MENU
2208	bool "Runtime Testing"
2209	default y
2210
2211	if RUNTIME_TESTING_MENU
2212
2213	config TEST_DHRY
2214	tristate "Dhrystone benchmark test"
2215	help
2216	Enable this to include the Dhrystone 2.1 benchmark. This test
2217	calculates the number of Dhrystones per second, and the number of
2218	DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided
2219	by 1757 (the number of Dhrystones per second obtained on the VAX
2220	11/780, nominally a 1 MIPS machine).
2221
2222	To run the benchmark, it needs to be enabled explicitly, either from
2223	the kernel command line (when built-in), or from userspace (when
2224	built-in or modular).
2225
2226	Run once during kernel boot:
2227
2228	test_dhry.run
2229
2230	Set number of iterations from kernel command line:
2231
2232	test_dhry.iterations=<n>
2233
2234	Set number of iterations from userspace:
2235
2236	echo <n> > /sys/module/test_dhry/parameters/iterations
2237
2238	Trigger manual run from userspace:
2239
2240	echo y > /sys/module/test_dhry/parameters/run
2241
2242	If the number of iterations is <= 0, the test will devise a suitable
2243	number of iterations (test runs for at least 2s) automatically.
2244	This process takes ca. 4s.
2245
2246	If unsure, say N.
2247
2248	config LKDTM
2249	tristate "Linux Kernel Dump Test Tool Module"
2250	depends on DEBUG_FS
2251	help
2252	This module enables testing of the different dumping mechanisms by
2253	inducing system failures at predefined crash points.
2254	If you don't need it: say N
2255	Choose M here to compile this code as a module. The module will be
2256	called lkdtm.
2257
2258	Documentation on how to use the module can be found in
2259	Documentation/fault-injection/provoke-crashes.rst
2260
2261	config CPUMASK_KUNIT_TEST
2262	tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS
2263	depends on KUNIT
2264	default KUNIT_ALL_TESTS
2265	help
2266	Enable to turn on cpumask tests, running at boot or module load time.
2267
2268	For more information on KUnit and unit tests in general, please refer
2269	to the KUnit documentation in Documentation/dev-tools/kunit/.
2270
2271	If unsure, say N.
2272
2273	config TEST_LIST_SORT
2274	tristate "Linked list sorting test" if !KUNIT_ALL_TESTS
2275	depends on KUNIT
2276	default KUNIT_ALL_TESTS
2277	help
2278	Enable this to turn on 'list_sort()' function test. This test is
2279	executed only once during system boot (so affects only boot time),
2280	or at module load time.
2281
2282	If unsure, say N.
2283
2284	config TEST_MIN_HEAP
2285	tristate "Min heap test"
2286	depends on DEBUG_KERNEL \|\| m
2287	help
2288	Enable this to turn on min heap function tests. This test is
2289	executed only once during system boot (so affects only boot time),
2290	or at module load time.
2291
2292	If unsure, say N.
2293
2294	config TEST_SORT
2295	tristate "Array-based sort test" if !KUNIT_ALL_TESTS
2296	depends on KUNIT
2297	default KUNIT_ALL_TESTS
2298	help
2299	This option enables the self-test function of 'sort()' at boot,
2300	or at module load time.
2301
2302	If unsure, say N.
2303
2304	config TEST_DIV64
2305	tristate "64bit/32bit division and modulo test"
2306	depends on DEBUG_KERNEL \|\| m
2307	help
2308	Enable this to turn on 'do_div()' function test. This test is
2309	executed only once during system boot (so affects only boot time),
2310	or at module load time.
2311
2312	If unsure, say N.
2313
2314	config TEST_MULDIV64
2315	tristate "mul_u64_u64_div_u64() test"
2316	depends on DEBUG_KERNEL \|\| m
2317	help
2318	Enable this to turn on 'mul_u64_u64_div_u64()' function test.
2319	This test is executed only once during system boot (so affects
2320	only boot time), or at module load time.
2321
2322	If unsure, say N.
2323
2324	config TEST_IOV_ITER
2325	tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS
2326	depends on KUNIT
2327	depends on MMU
2328	default KUNIT_ALL_TESTS
2329	help
2330	Enable this to turn on testing of the operation of the I/O iterator
2331	(iov_iter). This test is executed only once during system boot (so
2332	affects only boot time), or at module load time.
2333
2334	If unsure, say N.
2335
2336	config KPROBES_SANITY_TEST
2337	tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS
2338	depends on DEBUG_KERNEL
2339	depends on KPROBES
2340	depends on KUNIT
2341	select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
2342	default KUNIT_ALL_TESTS
2343	help
2344	This option provides for testing basic kprobes functionality on
2345	boot. Samples of kprobe and kretprobe are inserted and
2346	verified for functionality.
2347
2348	Say N if you are unsure.
2349
2350	config FPROBE_SANITY_TEST
2351	bool "Self test for fprobe"
2352	depends on DEBUG_KERNEL
2353	depends on FPROBE
2354	depends on KUNIT=y
2355	help
2356	This option will enable testing the fprobe when the system boot.
2357	A series of tests are made to verify that the fprobe is functioning
2358	properly.
2359
2360	Say N if you are unsure.
2361
2362	config BACKTRACE_SELF_TEST
2363	tristate "Self test for the backtrace code"
2364	depends on DEBUG_KERNEL
2365	help
2366	This option provides a kernel module that can be used to test
2367	the kernel stack backtrace code. This option is not useful
2368	for distributions or general kernels, but only for kernel
2369	developers working on architecture code.
2370
2371	Note that if you want to also test saved backtraces, you will
2372	have to enable STACKTRACE as well.
2373
2374	Say N if you are unsure.
2375
2376	config TEST_REF_TRACKER
2377	tristate "Self test for reference tracker"
2378	depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
2379	select REF_TRACKER
2380	help
2381	This option provides a kernel module performing tests
2382	using reference tracker infrastructure.
2383
2384	Say N if you are unsure.
2385
2386	config RBTREE_TEST
2387	tristate "Red-Black tree test"
2388	depends on DEBUG_KERNEL
2389	help
2390	A benchmark measuring the performance of the rbtree library.
2391	Also includes rbtree invariant checks.
2392
2393	config REED_SOLOMON_TEST
2394	tristate "Reed-Solomon library test"
2395	depends on DEBUG_KERNEL \|\| m
2396	select REED_SOLOMON
2397	select REED_SOLOMON_ENC16
2398	select REED_SOLOMON_DEC16
2399	help
2400	This option enables the self-test function of rslib at boot,
2401	or at module load time.
2402
2403	If unsure, say N.
2404
2405	config INTERVAL_TREE_TEST
2406	tristate "Interval tree test"
2407	depends on DEBUG_KERNEL
2408	select INTERVAL_TREE
2409	help
2410	A benchmark measuring the performance of the interval tree library
2411
2412	config PERCPU_TEST
2413	tristate "Per cpu operations test"
2414	depends on m && DEBUG_KERNEL
2415	help
2416	Enable this option to build test module which validates per-cpu
2417	operations.
2418
2419	If unsure, say N.
2420
2421	config ATOMIC64_SELFTEST
2422	tristate "Perform an atomic64_t self-test"
2423	help
2424	Enable this option to test the atomic64_t functions at boot or
2425	at module load time.
2426
2427	If unsure, say N.
2428
2429	config ASYNC_RAID6_TEST
2430	tristate "Self test for hardware accelerated raid6 recovery"
2431	depends on ASYNC_RAID6_RECOV
2432	select ASYNC_MEMCPY
2433	help
2434	This is a one-shot self test that permutes through the
2435	recovery of all the possible two disk failure scenarios for a
2436	N-disk array. Recovery is performed with the asynchronous
2437	raid6 recovery routines, and will optionally use an offload
2438	engine if one is available.
2439
2440	If unsure, say N.
2441
2442	config TEST_HEXDUMP
2443	tristate "Test functions located in the hexdump module at runtime"
2444
2445	config PRINTF_KUNIT_TEST
2446	tristate "KUnit test printf() family of functions at runtime" if !KUNIT_ALL_TESTS
2447	depends on KUNIT
2448	default KUNIT_ALL_TESTS
2449	help
2450	Enable this option to test the printf functions at runtime.
2451
2452	If unsure, say N.
2453
2454	config SCANF_KUNIT_TEST
2455	tristate "KUnit test scanf() family of functions at runtime" if !KUNIT_ALL_TESTS
2456	depends on KUNIT
2457	default KUNIT_ALL_TESTS
2458	help
2459	Enable this option to test the scanf functions at runtime.
2460
2461	If unsure, say N.
2462
2463	config SEQ_BUF_KUNIT_TEST
2464	tristate "KUnit test for seq_buf" if !KUNIT_ALL_TESTS
2465	depends on KUNIT
2466	default KUNIT_ALL_TESTS
2467	help
2468	This builds unit tests for the seq_buf library.
2469
2470	If unsure, say N.
2471
2472	config STRING_KUNIT_TEST
2473	tristate "KUnit test string functions at runtime" if !KUNIT_ALL_TESTS
2474	depends on KUNIT
2475	default KUNIT_ALL_TESTS
2476
2477	config STRING_HELPERS_KUNIT_TEST
2478	tristate "KUnit test string helpers at runtime" if !KUNIT_ALL_TESTS
2479	depends on KUNIT
2480	default KUNIT_ALL_TESTS
2481
2482	config TEST_KSTRTOX
2483	tristate "Test kstrto*() family of functions at runtime"
2484
2485	config TEST_BITMAP
2486	tristate "Test bitmap_*() family of functions at runtime"
2487	help
2488	Enable this option to test the bitmap functions at boot.
2489
2490	If unsure, say N.
2491
2492	config TEST_UUID
2493	tristate "Test functions located in the uuid module at runtime"
2494
2495	config TEST_XARRAY
2496	tristate "Test the XArray code at runtime"
2497
2498	config TEST_MAPLE_TREE
2499	tristate "Test the Maple Tree code at runtime or module load"
2500	help
2501	Enable this option to test the maple tree code functions at boot, or
2502	when the module is loaded. Enable "Debug Maple Trees" will enable
2503	more verbose output on failures.
2504
2505	If unsure, say N.
2506
2507	config TEST_RHASHTABLE
2508	tristate "Perform selftest on resizable hash table"
2509	help
2510	Enable this option to test the rhashtable functions at boot.
2511
2512	If unsure, say N.
2513
2514	config TEST_IDA
2515	tristate "Perform selftest on IDA functions"
2516
2517	config TEST_MISC_MINOR
2518	bool "miscdevice KUnit test" if !KUNIT_ALL_TESTS
2519	depends on KUNIT=y
2520	default KUNIT_ALL_TESTS
2521	help
2522	Kunit test for miscdevice API, specially its behavior in respect to
2523	static and dynamic minor numbers.
2524
2525	KUnit tests run during boot and output the results to the debug log
2526	in TAP format (https://testanything.org/). Only useful for kernel devs
2527	running the KUnit test harness, and not intended for inclusion into a
2528	production build.
2529
2530	For more information on KUnit and unit tests in general please refer
2531	to the KUnit documentation in Documentation/dev-tools/kunit/.
2532
2533	If unsure, say N.
2534
2535	config TEST_PARMAN
2536	tristate "Perform selftest on priority array manager"
2537	depends on PARMAN
2538	help
2539	Enable this option to test priority array manager on boot
2540	(or module load).
2541
2542	If unsure, say N.
2543
2544	config TEST_IRQ_TIMINGS
2545	bool "IRQ timings selftest"
2546	depends on IRQ_TIMINGS
2547	help
2548	Enable this option to test the irq timings code on boot.
2549
2550	If unsure, say N.
2551
2552	config TEST_LKM
2553	tristate "Test module loading with 'hello world' module"
2554	depends on m
2555	help
2556	This builds the "test_module" module that emits "Hello, world"
2557	on printk when loaded. It is designed to be used for basic
2558	evaluation of the module loading subsystem (for example when
2559	validating module verification). It lacks any extra dependencies,
2560	and will not normally be loaded by the system unless explicitly
2561	requested by name.
2562
2563	If unsure, say N.
2564
2565	config TEST_BITOPS
2566	tristate "Test module for compilation of bitops operations"
2567	help
2568	This builds the "test_bitops" module that is much like the
2569	TEST_LKM module except that it does a basic exercise of the
2570	set/clear_bit macros and get_count_order/long to make sure there are
2571	no compiler warnings from C=1 sparse checker or -Wextra
2572	compilations. It has no dependencies and doesn't run or load unless
2573	explicitly requested by name. for example: modprobe test_bitops.
2574
2575	If unsure, say N.
2576
2577	config TEST_VMALLOC
2578	tristate "Test module for stress/performance analysis of vmalloc allocator"
2579	default n
2580	depends on MMU
2581	help
2582	This builds the "test_vmalloc" module that should be used for
2583	stress and performance analysis. So, any new change for vmalloc
2584	subsystem can be evaluated from performance and stability point
2585	of view.
2586
2587	If unsure, say N.
2588
2589	config TEST_BPF
2590	tristate "Test BPF filter functionality"
2591	depends on m && NET
2592	help
2593	This builds the "test_bpf" module that runs various test vectors
2594	against the BPF interpreter or BPF JIT compiler depending on the
2595	current setting. This is in particular useful for BPF JIT compiler
2596	development, but also to run regression tests against changes in
2597	the interpreter code. It also enables test stubs for eBPF maps and
2598	verifier used by user space verifier testsuite.
2599
2600	If unsure, say N.
2601
2602	config FIND_BIT_BENCHMARK
2603	tristate "Test find_bit functions"
2604	help
2605	This builds the "test_find_bit" module that measure find_*_bit()
2606	functions performance.
2607
2608	If unsure, say N.
2609
2610	config TEST_FIRMWARE
2611	tristate "Test firmware loading via userspace interface"
2612	depends on FW_LOADER
2613	help
2614	This builds the "test_firmware" module that creates a userspace
2615	interface for testing firmware loading. This can be used to
2616	control the triggering of firmware loading without needing an
2617	actual firmware-using device. The contents can be rechecked by
2618	userspace.
2619
2620	If unsure, say N.
2621
2622	config TEST_SYSCTL
2623	tristate "sysctl test driver"
2624	depends on PROC_SYSCTL
2625	help
2626	This builds the "test_sysctl" module. This driver enables to test the
2627	proc sysctl interfaces available to drivers safely without affecting
2628	production knobs which might alter system functionality.
2629
2630	If unsure, say N.
2631
2632	config BITFIELD_KUNIT
2633	tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS
2634	depends on KUNIT
2635	default KUNIT_ALL_TESTS
2636	help
2637	Enable this option to test the bitfield functions at boot.
2638
2639	KUnit tests run during boot and output the results to the debug log
2640	in TAP format (http://testanything.org/). Only useful for kernel devs
2641	running the KUnit test harness, and not intended for inclusion into a
2642	production build.
2643
2644	For more information on KUnit and unit tests in general please refer
2645	to the KUnit documentation in Documentation/dev-tools/kunit/.
2646
2647	If unsure, say N.
2648
2649	config CHECKSUM_KUNIT
2650	tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS
2651	depends on KUNIT
2652	default KUNIT_ALL_TESTS
2653	help
2654	Enable this option to test the checksum functions at boot.
2655
2656	KUnit tests run during boot and output the results to the debug log
2657	in TAP format (http://testanything.org/). Only useful for kernel devs
2658	running the KUnit test harness, and not intended for inclusion into a
2659	production build.
2660
2661	For more information on KUnit and unit tests in general please refer
2662	to the KUnit documentation in Documentation/dev-tools/kunit/.
2663
2664	If unsure, say N.
2665
2666	config UTIL_MACROS_KUNIT
2667	tristate "KUnit test util_macros.h functions at runtime" if !KUNIT_ALL_TESTS
2668	depends on KUNIT
2669	default KUNIT_ALL_TESTS
2670	help
2671	Enable this option to test the util_macros.h function at boot.
2672
2673	KUnit tests run during boot and output the results to the debug log
2674	in TAP format (http://testanything.org/). Only useful for kernel devs
2675	running the KUnit test harness, and not intended for inclusion into a
2676	production build.
2677
2678	For more information on KUnit and unit tests in general please refer
2679	to the KUnit documentation in Documentation/dev-tools/kunit/.
2680
2681	If unsure, say N.
2682
2683	config HASH_KUNIT_TEST
2684	tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS
2685	depends on KUNIT
2686	default KUNIT_ALL_TESTS
2687	help
2688	Enable this option to test the kernel's string (<linux/stringhash.h>), and
2689	integer (<linux/hash.h>) hash functions on boot.
2690
2691	KUnit tests run during boot and output the results to the debug log
2692	in TAP format (https://testanything.org/). Only useful for kernel devs
2693	running the KUnit test harness, and not intended for inclusion into a
2694	production build.
2695
2696	For more information on KUnit and unit tests in general please refer
2697	to the KUnit documentation in Documentation/dev-tools/kunit/.
2698
2699	This is intended to help people writing architecture-specific
2700	optimized versions. If unsure, say N.
2701
2702	config RESOURCE_KUNIT_TEST
2703	tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS
2704	depends on KUNIT
2705	default KUNIT_ALL_TESTS
2706	select GET_FREE_REGION
2707	help
2708	This builds the resource API unit test.
2709	Tests the logic of API provided by resource.c and ioport.h.
2710	For more information on KUnit and unit tests in general please refer
2711	to the KUnit documentation in Documentation/dev-tools/kunit/.
2712
2713	If unsure, say N.
2714
2715	config SYSCTL_KUNIT_TEST
2716	tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS
2717	depends on KUNIT
2718	default KUNIT_ALL_TESTS
2719	help
2720	This builds the proc sysctl unit test, which runs on boot.
2721	Tests the API contract and implementation correctness of sysctl.
2722	For more information on KUnit and unit tests in general please refer
2723	to the KUnit documentation in Documentation/dev-tools/kunit/.
2724
2725	If unsure, say N.
2726
2727	config KFIFO_KUNIT_TEST
2728	tristate "KUnit Test for the generic kernel FIFO implementation" if !KUNIT_ALL_TESTS
2729	depends on KUNIT
2730	default KUNIT_ALL_TESTS
2731	help
2732	This builds the generic FIFO implementation KUnit test suite.
2733	It tests that the API and basic functionality of the kfifo type
2734	and associated macros.
2735
2736	For more information on KUnit and unit tests in general please refer
2737	to the KUnit documentation in Documentation/dev-tools/kunit/.
2738
2739	If unsure, say N.
2740
2741	config LIST_KUNIT_TEST
2742	tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS
2743	depends on KUNIT
2744	default KUNIT_ALL_TESTS
2745	help
2746	This builds the linked list KUnit test suite.
2747	It tests that the API and basic functionality of the list_head type
2748	and associated macros.
2749
2750	KUnit tests run during boot and output the results to the debug log
2751	in TAP format (https://testanything.org/). Only useful for kernel devs
2752	running the KUnit test harness, and not intended for inclusion into a
2753	production build.
2754
2755	For more information on KUnit and unit tests in general please refer
2756	to the KUnit documentation in Documentation/dev-tools/kunit/.
2757
2758	If unsure, say N.
2759
2760	config HASHTABLE_KUNIT_TEST
2761	tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS
2762	depends on KUNIT
2763	default KUNIT_ALL_TESTS
2764	help
2765	This builds the hashtable KUnit test suite.
2766	It tests the basic functionality of the API defined in
2767	include/linux/hashtable.h. For more information on KUnit and
2768	unit tests in general please refer to the KUnit documentation
2769	in Documentation/dev-tools/kunit/.
2770
2771	If unsure, say N.
2772
2773	config LINEAR_RANGES_TEST
2774	tristate "KUnit test for linear_ranges"
2775	depends on KUNIT
2776	select LINEAR_RANGES
2777	help
2778	This builds the linear_ranges unit test, which runs on boot.
2779	Tests the linear_ranges logic correctness.
2780	For more information on KUnit and unit tests in general please refer
2781	to the KUnit documentation in Documentation/dev-tools/kunit/.
2782
2783	If unsure, say N.
2784
2785	config CMDLINE_KUNIT_TEST
2786	tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS
2787	depends on KUNIT
2788	default KUNIT_ALL_TESTS
2789	help
2790	This builds the cmdline API unit test.
2791	Tests the logic of API provided by cmdline.c.
2792	For more information on KUnit and unit tests in general please refer
2793	to the KUnit documentation in Documentation/dev-tools/kunit/.
2794
2795	If unsure, say N.
2796
2797	config BITS_TEST
2798	tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS
2799	depends on KUNIT
2800	default KUNIT_ALL_TESTS
2801	help
2802	This builds the bits unit test.
2803	Tests the logic of macros defined in bits.h.
2804	For more information on KUnit and unit tests in general please refer
2805	to the KUnit documentation in Documentation/dev-tools/kunit/.
2806
2807	If unsure, say N.
2808
2809	config SLUB_KUNIT_TEST
2810	tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS
2811	depends on SLUB_DEBUG && KUNIT
2812	default KUNIT_ALL_TESTS
2813	help
2814	This builds SLUB allocator unit test.
2815	Tests SLUB cache debugging functionality.
2816	For more information on KUnit and unit tests in general please refer
2817	to the KUnit documentation in Documentation/dev-tools/kunit/.
2818
2819	If unsure, say N.
2820
2821	config RATIONAL_KUNIT_TEST
2822	tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS
2823	depends on KUNIT && RATIONAL
2824	default KUNIT_ALL_TESTS
2825	help
2826	This builds the rational math unit test.
2827	For more information on KUnit and unit tests in general please refer
2828	to the KUnit documentation in Documentation/dev-tools/kunit/.
2829
2830	If unsure, say N.
2831
2832	config MEMCPY_KUNIT_TEST
2833	tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS
2834	depends on KUNIT
2835	default KUNIT_ALL_TESTS
2836	help
2837	Builds unit tests for memcpy(), memmove(), and memset() functions.
2838	For more information on KUnit and unit tests in general please refer
2839	to the KUnit documentation in Documentation/dev-tools/kunit/.
2840
2841	If unsure, say N.
2842
2843	config IS_SIGNED_TYPE_KUNIT_TEST
2844	tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS
2845	depends on KUNIT
2846	default KUNIT_ALL_TESTS
2847	help
2848	Builds unit tests for the is_signed_type() macro.
2849
2850	For more information on KUnit and unit tests in general please refer
2851	to the KUnit documentation in Documentation/dev-tools/kunit/.
2852
2853	If unsure, say N.
2854
2855	config OVERFLOW_KUNIT_TEST
2856	tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS
2857	depends on KUNIT
2858	default KUNIT_ALL_TESTS
2859	help
2860	Builds unit tests for the check__overflow(), size_(), allocation, and
2861	related functions.
2862
2863	For more information on KUnit and unit tests in general please refer
2864	to the KUnit documentation in Documentation/dev-tools/kunit/.
2865
2866	If unsure, say N.
2867
2868	config RANDSTRUCT_KUNIT_TEST
2869	tristate "Test randstruct structure layout randomization at runtime" if !KUNIT_ALL_TESTS
2870	depends on KUNIT
2871	default KUNIT_ALL_TESTS
2872	help
2873	Builds unit tests for the checking CONFIG_RANDSTRUCT=y, which
2874	randomizes structure layouts.
2875
2876	config STACKINIT_KUNIT_TEST
2877	tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS
2878	depends on KUNIT
2879	default KUNIT_ALL_TESTS
2880	help
2881	Test if the kernel is zero-initializing stack variables and
2882	padding. Coverage is controlled by compiler flags,
2883	CONFIG_INIT_STACK_ALL_PATTERN or CONFIG_INIT_STACK_ALL_ZERO.
2884
2885	config FORTIFY_KUNIT_TEST
2886	tristate "Test fortified str() and mem() function internals at runtime" if !KUNIT_ALL_TESTS
2887	depends on KUNIT
2888	default KUNIT_ALL_TESTS
2889	help
2890	Builds unit tests for checking internals of FORTIFY_SOURCE as used
2891	by the str() and mem() family of functions. For testing runtime
2892	traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests.
2893
2894	config LONGEST_SYM_KUNIT_TEST
2895	tristate "Test the longest symbol possible" if !KUNIT_ALL_TESTS
2896	depends on KUNIT && KPROBES
2897	depends on !PREFIX_SYMBOLS && !CFI_CLANG && !GCOV_KERNEL
2898	default KUNIT_ALL_TESTS
2899	help
2900	Tests the longest symbol possible
2901
2902	If unsure, say N.
2903
2904	config HW_BREAKPOINT_KUNIT_TEST
2905	bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS
2906	depends on HAVE_HW_BREAKPOINT
2907	depends on KUNIT=y
2908	default KUNIT_ALL_TESTS
2909	help
2910	Tests for hw_breakpoint constraints accounting.
2911
2912	If unsure, say N.
2913
2914	config SIPHASH_KUNIT_TEST
2915	tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS
2916	depends on KUNIT
2917	default KUNIT_ALL_TESTS
2918	help
2919	Enable this option to test the kernel's siphash (<linux/siphash.h>) hash
2920	functions on boot (or module load).
2921
2922	This is intended to help people writing architecture-specific
2923	optimized versions. If unsure, say N.
2924
2925	config USERCOPY_KUNIT_TEST
2926	tristate "KUnit Test for user/kernel boundary protections"
2927	depends on KUNIT
2928	default KUNIT_ALL_TESTS
2929	help
2930	This builds the "usercopy_kunit" module that runs sanity checks
2931	on the copy_to/from_user infrastructure, making sure basic
2932	user/kernel boundary testing is working.
2933
2934	config BLACKHOLE_DEV_KUNIT_TEST
2935	tristate "Test blackhole netdev functionality" if !KUNIT_ALL_TESTS
2936	depends on NET
2937	depends on KUNIT
2938	default KUNIT_ALL_TESTS
2939	help
2940	This builds the "blackhole_dev_kunit" module that validates the
2941	data path through this blackhole netdev.
2942
2943	If unsure, say N.
2944
2945	config TEST_UDELAY
2946	tristate "udelay test driver"
2947	help
2948	This builds the "udelay_test" module that helps to make sure
2949	that udelay() is working properly.
2950
2951	If unsure, say N.
2952
2953	config TEST_STATIC_KEYS
2954	tristate "Test static keys"
2955	depends on m
2956	help
2957	Test the static key interfaces.
2958
2959	If unsure, say N.
2960
2961	config TEST_DYNAMIC_DEBUG
2962	tristate "Test DYNAMIC_DEBUG"
2963	depends on DYNAMIC_DEBUG
2964	help
2965	This module registers a tracer callback to count enabled
2966	pr_debugs in a 'do_debugging' function, then alters their
2967	enablements, calls the function, and compares counts.
2968
2969	If unsure, say N.
2970
2971	config TEST_KMOD
2972	tristate "kmod stress tester"
2973	depends on m
2974	select TEST_LKM
2975	help
2976	Test the kernel's module loading mechanism: kmod. kmod implements
2977	support to load modules using the Linux kernel's usermode helper.
2978	This test provides a series of tests against kmod.
2979
2980	Although technically you can either build test_kmod as a module or
2981	into the kernel we disallow building it into the kernel since
2982	it stress tests request_module() and this will very likely cause
2983	some issues by taking over precious threads available from other
2984	module load requests, ultimately this could be fatal.
2985
2986	To run tests run:
2987
2988	tools/testing/selftests/kmod/kmod.sh --help
2989
2990	If unsure, say N.
2991
2992	config TEST_RUNTIME
2993	bool
2994
2995	config TEST_RUNTIME_MODULE
2996	bool
2997
2998	config TEST_KALLSYMS
2999	tristate "module kallsyms find_symbol() test"
3000	depends on m
3001	select TEST_RUNTIME
3002	select TEST_RUNTIME_MODULE
3003	select TEST_KALLSYMS_A
3004	select TEST_KALLSYMS_B
3005	select TEST_KALLSYMS_C
3006	select TEST_KALLSYMS_D
3007	help
3008	This allows us to stress test find_symbol() through the kallsyms
3009	used to place symbols on the kernel ELF kallsyms and modules kallsyms
3010	where we place kernel symbols such as exported symbols.
3011
3012	We have four test modules:
3013
3014	A: has KALLSYSMS_NUMSYMS exported symbols
3015	B: uses one of A's symbols
3016	C: adds KALLSYMS_SCALE_FACTOR * KALLSYSMS_NUMSYMS exported
3017	D: adds 2 * the symbols than C
3018
3019	We stress test find_symbol() through two means:
3020
3021	1) Upon load of B it will trigger simplify_symbols() to look for the
3022	one symbol it uses from the module A with tons of symbols. This is an
3023	indirect way for us to have B call resolve_symbol_wait() upon module
3024	load. This will eventually call find_symbol() which will eventually
3025	try to find the symbols used with find_exported_symbol_in_section().
3026	find_exported_symbol_in_section() uses bsearch() so a binary search
3027	for each symbol. Binary search will at worst be O(log(n)) so the
3028	larger TEST_MODULE_KALLSYSMS the worse the search.
3029
3030	2) The selftests should load C first, before B. Upon B's load towards
3031	the end right before we call module B's init routine we get
3032	complete_formation() called on the module. That will first check
3033	for duplicate symbols with the call to verify_exported_symbols().
3034	That is when we'll force iteration on module C's insane symbol list.
3035	Since it has 10 * KALLSYMS_NUMSYMS it means we can first test
3036	just loading B without C. The amount of time it takes to load C Vs
3037	B can give us an idea of the impact growth of the symbol space and
3038	give us projection. Module A only uses one symbol from B so to allow
3039	this scaling in module C to be proportional, if it used more symbols
3040	then the first test would be doing more and increasing just the
3041	search space would be slightly different. The last module, module D
3042	will just increase the search space by twice the number of symbols in
3043	C so to allow for full projects.
3044
3045	tools/testing/selftests/module/find_symbol.sh
3046
3047	The current defaults will incur a build delay of about 7 minutes
3048	on an x86_64 with only 8 cores. Enable this only if you want to
3049	stress test find_symbol() with thousands of symbols. At the same
3050	time this is also useful to test building modules with thousands of
3051	symbols, and if BTF is enabled this also stress tests adding BTF
3052	information for each module. Currently enabling many more symbols
3053	will segfault the build system.
3054
3055	If unsure, say N.
3056
3057	if TEST_KALLSYMS
3058
3059	config TEST_KALLSYMS_A
3060	tristate
3061	depends on m
3062
3063	config TEST_KALLSYMS_B
3064	tristate
3065	depends on m
3066
3067	config TEST_KALLSYMS_C
3068	tristate
3069	depends on m
3070
3071	config TEST_KALLSYMS_D
3072	tristate
3073	depends on m
3074
3075	choice
3076	prompt "Kallsym test range"
3077	default TEST_KALLSYMS_LARGE
3078	help
3079	Selecting something other than "Fast" will enable tests which slow
3080	down the build and may crash your build.
3081
3082	config TEST_KALLSYMS_FAST
3083	bool "Fast builds"
3084	help
3085	You won't really be testing kallsysms, so this just helps fast builds
3086	when allmodconfig is used..
3087
3088	config TEST_KALLSYMS_LARGE
3089	bool "Enable testing kallsyms with large exports"
3090	help
3091	This will enable larger number of symbols. This will slow down
3092	your build considerably.
3093
3094	config TEST_KALLSYMS_MAX
3095	bool "Known kallsysms limits"
3096	help
3097	This will enable exports to the point we know we'll start crashing
3098	builds.
3099
3100	endchoice
3101
3102	config TEST_KALLSYMS_NUMSYMS
3103	int "test kallsyms number of symbols"
3104	range 2 10000
3105	default 2 if TEST_KALLSYMS_FAST
3106	default 100 if TEST_KALLSYMS_LARGE
3107	default 10000 if TEST_KALLSYMS_MAX
3108	help
3109	The number of symbols to create on TEST_KALLSYMS_A, only one of which
3110	module TEST_KALLSYMS_B will use. This also will be used
3111	for how many symbols TEST_KALLSYMS_C will have, scaled up by
3112	TEST_KALLSYMS_SCALE_FACTOR. Note that setting this to 10,000 will
3113	trigger a segfault today, don't use anything close to it unless
3114	you are aware that this should not be used for automated build tests.
3115
3116	config TEST_KALLSYMS_SCALE_FACTOR
3117	int "test kallsyms scale factor"
3118	default 8
3119	help
3120	How many more unusued symbols will TEST_KALLSYSMS_C have than
3121	TEST_KALLSYMS_A. If 8, then module C will have 8 * syms
3122	than module A. Then TEST_KALLSYMS_D will have double the amount
3123	of symbols than C so to allow projections.
3124
3125	endif # TEST_KALLSYMS
3126
3127	config TEST_DEBUG_VIRTUAL
3128	tristate "Test CONFIG_DEBUG_VIRTUAL feature"
3129	depends on DEBUG_VIRTUAL
3130	help
3131	Test the kernel's ability to detect incorrect calls to
3132	virt_to_phys() done against the non-linear part of the
3133	kernel's virtual address map.
3134
3135	If unsure, say N.
3136
3137	config TEST_MEMCAT_P
3138	tristate "Test memcat_p() helper function"
3139	help
3140	Test the memcat_p() helper for correctly merging two
3141	pointer arrays together.
3142
3143	If unsure, say N.
3144
3145	config TEST_OBJAGG
3146	tristate "Perform selftest on object aggreration manager"
3147	default n
3148	depends on OBJAGG
3149	help
3150	Enable this option to test object aggregation manager on boot
3151	(or module load).
3152
3153	config TEST_MEMINIT
3154	tristate "Test heap/page initialization"
3155	help
3156	Test if the kernel is zero-initializing heap and page allocations.
3157	This can be useful to test init_on_alloc and init_on_free features.
3158
3159	If unsure, say N.
3160
3161	config TEST_HMM
3162	tristate "Test HMM (Heterogeneous Memory Management)"
3163	depends on TRANSPARENT_HUGEPAGE
3164	depends on DEVICE_PRIVATE
3165	select HMM_MIRROR
3166	select MMU_NOTIFIER
3167	help
3168	This is a pseudo device driver solely for testing HMM.
3169	Say M here if you want to build the HMM test module.
3170	Doing so will allow you to run tools/testing/selftest/vm/hmm-tests.
3171
3172	If unsure, say N.
3173
3174	config TEST_FREE_PAGES
3175	tristate "Test freeing pages"
3176	help
3177	Test that a memory leak does not occur due to a race between
3178	freeing a block of pages and a speculative page reference.
3179	Loading this module is safe if your kernel has the bug fixed.
3180	If the bug is not fixed, it will leak gigabytes of memory and
3181	probably OOM your system.
3182
3183	config TEST_FPU
3184	tristate "Test floating point operations in kernel space"
3185	depends on ARCH_HAS_KERNEL_FPU_SUPPORT && !KCOV_INSTRUMENT_ALL
3186	help
3187	Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu
3188	which will trigger a sequence of floating point operations. This is used
3189	for self-testing floating point control register setting in
3190	kernel_fpu_begin().
3191
3192	If unsure, say N.
3193
3194	config TEST_CLOCKSOURCE_WATCHDOG
3195	tristate "Test clocksource watchdog in kernel space"
3196	depends on CLOCKSOURCE_WATCHDOG
3197	help
3198	Enable this option to create a kernel module that will trigger
3199	a test of the clocksource watchdog. This module may be loaded
3200	via modprobe or insmod in which case it will run upon being
3201	loaded, or it may be built in, in which case it will run
3202	shortly after boot.
3203
3204	If unsure, say N.
3205
3206	config TEST_OBJPOOL
3207	tristate "Test module for correctness and stress of objpool"
3208	default n
3209	depends on m && DEBUG_KERNEL
3210	help
3211	This builds the "test_objpool" module that should be used for
3212	correctness verification and concurrent testings of objects
3213	allocation and reclamation.
3214
3215	If unsure, say N.
3216
3217	config TEST_KEXEC_HANDOVER
3218	bool "Test for Kexec HandOver"
3219	default n
3220	depends on KEXEC_HANDOVER
3221	help
3222	This option enables test for Kexec HandOver (KHO).
3223	The test consists of two parts: saving kernel data before kexec and
3224	restoring the data after kexec and verifying that it was properly
3225	handed over. This test module creates and saves data on the boot of
3226	the first kernel and restores and verifies the data on the boot of
3227	kexec'ed kernel.
3228
3229	For detailed documentation about KHO, see Documentation/core-api/kho.
3230
3231	To run the test run:
3232
3233	tools/testing/selftests/kho/vmtest.sh -h
3234
3235	If unsure, say N.
3236
3237	config RATELIMIT_KUNIT_TEST
3238	tristate "KUnit Test for correctness and stress of ratelimit" if !KUNIT_ALL_TESTS
3239	depends on KUNIT
3240	default KUNIT_ALL_TESTS
3241	help
3242	This builds the "test_ratelimit" module that should be used
3243	for correctness verification and concurrent testings of rate
3244	limiting.
3245
3246	If unsure, say N.
3247
3248	config INT_POW_KUNIT_TEST
3249	tristate "Integer exponentiation (int_pow) test" if !KUNIT_ALL_TESTS
3250	depends on KUNIT
3251	default KUNIT_ALL_TESTS
3252	help
3253	This option enables the KUnit test suite for the int_pow function,
3254	which performs integer exponentiation. The test suite is designed to
3255	verify that the implementation of int_pow correctly computes the power
3256	of a given base raised to a given exponent.
3257
3258	Enabling this option will include tests that check various scenarios
3259	and edge cases to ensure the accuracy and reliability of the exponentiation
3260	function.
3261
3262	If unsure, say N
3263
3264	config INT_SQRT_KUNIT_TEST
3265	tristate "Integer square root test" if !KUNIT_ALL_TESTS
3266	depends on KUNIT
3267	default KUNIT_ALL_TESTS
3268	help
3269	This option enables the KUnit test suite for the int_sqrt() function,
3270	which performs square root calculation. The test suite checks
3271	various scenarios, including edge cases, to ensure correctness.
3272
3273	Enabling this option will include tests that check various scenarios
3274	and edge cases to ensure the accuracy and reliability of the square root
3275	function.
3276
3277	If unsure, say N
3278
3279	config INT_LOG_KUNIT_TEST
3280	tristate "Integer log (int_log) test" if !KUNIT_ALL_TESTS
3281	depends on KUNIT
3282	default KUNIT_ALL_TESTS
3283	help
3284	This option enables the KUnit test suite for the int_log library, which
3285	provides two functions to compute the integer logarithm in base 2 and
3286	base 10, called respectively as intlog2 and intlog10.
3287
3288	If unsure, say N
3289
3290	config GCD_KUNIT_TEST
3291	tristate "Greatest common divisor test" if !KUNIT_ALL_TESTS
3292	depends on KUNIT
3293	default KUNIT_ALL_TESTS
3294	help
3295	This option enables the KUnit test suite for the gcd() function,
3296	which computes the greatest common divisor of two numbers.
3297
3298	This test suite verifies the correctness of gcd() across various
3299	scenarios, including edge cases.
3300
3301	If unsure, say N
3302
3303	config PRIME_NUMBERS_KUNIT_TEST
3304	tristate "Prime number generator test" if !KUNIT_ALL_TESTS
3305	depends on KUNIT
3306	depends on PRIME_NUMBERS
3307	default KUNIT_ALL_TESTS
3308	help
3309	This option enables the KUnit test suite for the {is,next}_prime_number
3310	functions.
3311
3312	Enabling this option will include tests that compare the prime number
3313	generator functions against a brute force implementation.
3314
3315	If unsure, say N
3316
3317	endif # RUNTIME_TESTING_MENU
3318
3319	config ARCH_USE_MEMTEST
3320	bool
3321	help
3322	An architecture should select this when it uses early_memtest()
3323	during boot process.
3324
3325	config MEMTEST
3326	bool "Memtest"
3327	depends on ARCH_USE_MEMTEST
3328	help
3329	This option adds a kernel parameter 'memtest', which allows memtest
3330	to be set and executed.
3331	memtest=0, mean disabled; -- default
3332	memtest=1, mean do 1 test pattern;
3333	...
3334	memtest=17, mean do 17 test patterns.
3335	If you are unsure how to answer this question, answer N.
3336
3337
3338
3339	config HYPERV_TESTING
3340	bool "Microsoft Hyper-V driver testing"
3341	default n
3342	depends on HYPERV && DEBUG_FS
3343	help
3344	Select this option to enable Hyper-V vmbus testing.
3345
3346	endmenu # "Kernel Testing and Coverage"
3347
3348	menu "Rust hacking"
3349
3350	config RUST_DEBUG_ASSERTIONS
3351	bool "Debug assertions"
3352	depends on RUST
3353	help
3354	Enables rustc's `-Cdebug-assertions` codegen option.
3355
3356	This flag lets you turn `cfg(debug_assertions)` conditional
3357	compilation on or off. This can be used to enable extra debugging
3358	code in development but not in production. For example, it controls
3359	the behavior of the standard library's `debug_assert!` macro.
3360
3361	Note that this will apply to all Rust code, including `core`.
3362
3363	If unsure, say N.
3364
3365	config RUST_OVERFLOW_CHECKS
3366	bool "Overflow checks"
3367	default y
3368	depends on RUST
3369	help
3370	Enables rustc's `-Coverflow-checks` codegen option.
3371
3372	This flag allows you to control the behavior of runtime integer
3373	overflow. When overflow-checks are enabled, a Rust panic will occur
3374	on overflow.
3375
3376	Note that this will apply to all Rust code, including `core`.
3377
3378	If unsure, say Y.
3379
3380	config RUST_BUILD_ASSERT_ALLOW
3381	bool "Allow unoptimized build-time assertions"
3382	depends on RUST
3383	help
3384	Controls how `build_error!` and `build_assert!` are handled during the build.
3385
3386	If calls to them exist in the binary, it may indicate a violated invariant
3387	or that the optimizer failed to verify the invariant during compilation.
3388
3389	This should not happen, thus by default the build is aborted. However,
3390	as an escape hatch, you can choose Y here to ignore them during build
3391	and let the check be carried at runtime (with `panic!` being called if
3392	the check fails).
3393
3394	If unsure, say N.
3395
3396	config RUST_KERNEL_DOCTESTS
3397	bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS
3398	depends on RUST && KUNIT=y
3399	default KUNIT_ALL_TESTS
3400	help
3401	This builds the documentation tests of the `kernel` crate
3402	as KUnit tests.
3403
3404	For more information on KUnit and unit tests in general,
3405	please refer to the KUnit documentation in Documentation/dev-tools/kunit/.
3406
3407	If unsure, say N.
3408
3409	endmenu # "Rust"
3410
3411	endmenu # Kernel hacking