xref: /linux/lib/Kconfig.debug (revision a16219bdd34777cce35b9b6a704bfbaad28adb72)
1# SPDX-License-Identifier: GPL-2.0-only
2menu "Kernel hacking"
3
4menu "printk and dmesg options"
5
6config PRINTK_TIME
7	bool "Show timing information on printks"
8	depends on PRINTK
9	help
10	  Selecting this option causes time stamps of the printk()
11	  messages to be added to the output of the syslog() system
12	  call and at the console.
13
14	  The timestamp is always recorded internally, and exported
15	  to /dev/kmsg. This flag just specifies if the timestamp should
16	  be included, not that the timestamp is recorded.
17
18	  The behavior is also controlled by the kernel command line
19	  parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst
20
21config PRINTK_CALLER
22	bool "Show caller information on printks"
23	depends on PRINTK
24	help
25	  Selecting this option causes printk() to add a caller "thread id" (if
26	  in task context) or a caller "processor id" (if not in task context)
27	  to every message.
28
29	  This option is intended for environments where multiple threads
30	  concurrently call printk() for many times, for it is difficult to
31	  interpret without knowing where these lines (or sometimes individual
32	  line which was divided into multiple lines due to race) came from.
33
34	  Since toggling after boot makes the code racy, currently there is
35	  no option to enable/disable at the kernel command line parameter or
36	  sysfs interface.
37
38config STACKTRACE_BUILD_ID
39	bool "Show build ID information in stacktraces"
40	depends on PRINTK
41	help
42	  Selecting this option adds build ID information for symbols in
43	  stacktraces printed with the printk format '%p[SR]b'.
44
45	  This option is intended for distros where debuginfo is not easily
46	  accessible but can be downloaded given the build ID of the vmlinux or
47	  kernel module where the function is located.
48
49config CONSOLE_LOGLEVEL_DEFAULT
50	int "Default console loglevel (1-15)"
51	range 1 15
52	default "7"
53	help
54	  Default loglevel to determine what will be printed on the console.
55
56	  Setting a default here is equivalent to passing in loglevel=<x> in
57	  the kernel bootargs. loglevel=<x> continues to override whatever
58	  value is specified here as well.
59
60	  Note: This does not affect the log level of un-prefixed printk()
61	  usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT
62	  option.
63
64config CONSOLE_LOGLEVEL_QUIET
65	int "quiet console loglevel (1-15)"
66	range 1 15
67	default "4"
68	help
69	  loglevel to use when "quiet" is passed on the kernel commandline.
70
71	  When "quiet" is passed on the kernel commandline this loglevel
72	  will be used as the loglevel. IOW passing "quiet" will be the
73	  equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>"
74
75config MESSAGE_LOGLEVEL_DEFAULT
76	int "Default message log level (1-7)"
77	range 1 7
78	default "4"
79	help
80	  Default log level for printk statements with no specified priority.
81
82	  This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
83	  that are auditing their logs closely may want to set it to a lower
84	  priority.
85
86	  Note: This does not affect what message level gets printed on the console
87	  by default. To change that, use loglevel=<x> in the kernel bootargs,
88	  or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value.
89
90config BOOT_PRINTK_DELAY
91	bool "Delay each boot printk message by N milliseconds"
92	depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
93	help
94	  This build option allows you to read kernel boot messages
95	  by inserting a short delay after each one.  The delay is
96	  specified in milliseconds on the kernel command line,
97	  using "boot_delay=N".
98
99	  It is likely that you would also need to use "lpj=M" to preset
100	  the "loops per jiffie" value.
101	  See a previous boot log for the "lpj" value to use for your
102	  system, and then set "lpj=M" before setting "boot_delay=N".
103	  NOTE:  Using this option may adversely affect SMP systems.
104	  I.e., processors other than the first one may not boot up.
105	  BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
106	  what it believes to be lockup conditions.
107
108config DYNAMIC_DEBUG
109	bool "Enable dynamic printk() support"
110	default n
111	depends on PRINTK
112	depends on (DEBUG_FS || PROC_FS)
113	select DYNAMIC_DEBUG_CORE
114	help
115
116	  Compiles debug level messages into the kernel, which would not
117	  otherwise be available at runtime. These messages can then be
118	  enabled/disabled based on various levels of scope - per source file,
119	  function, module, format string, and line number. This mechanism
120	  implicitly compiles in all pr_debug() and dev_dbg() calls, which
121	  enlarges the kernel text size by about 2%.
122
123	  If a source file is compiled with DEBUG flag set, any
124	  pr_debug() calls in it are enabled by default, but can be
125	  disabled at runtime as below.  Note that DEBUG flag is
126	  turned on by many CONFIG_*DEBUG* options.
127
128	  Usage:
129
130	  Dynamic debugging is controlled via the 'dynamic_debug/control' file,
131	  which is contained in the 'debugfs' filesystem or procfs.
132	  Thus, the debugfs or procfs filesystem must first be mounted before
133	  making use of this feature.
134	  We refer the control file as: <debugfs>/dynamic_debug/control. This
135	  file contains a list of the debug statements that can be enabled. The
136	  format for each line of the file is:
137
138		filename:lineno [module]function flags format
139
140	  filename : source file of the debug statement
141	  lineno : line number of the debug statement
142	  module : module that contains the debug statement
143	  function : function that contains the debug statement
144	  flags : '=p' means the line is turned 'on' for printing
145	  format : the format used for the debug statement
146
147	  From a live system:
148
149		nullarbor:~ # cat <debugfs>/dynamic_debug/control
150		# filename:lineno [module]function flags format
151		fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
152		fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
153		fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
154
155	  Example usage:
156
157		// enable the message at line 1603 of file svcsock.c
158		nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
159						<debugfs>/dynamic_debug/control
160
161		// enable all the messages in file svcsock.c
162		nullarbor:~ # echo -n 'file svcsock.c +p' >
163						<debugfs>/dynamic_debug/control
164
165		// enable all the messages in the NFS server module
166		nullarbor:~ # echo -n 'module nfsd +p' >
167						<debugfs>/dynamic_debug/control
168
169		// enable all 12 messages in the function svc_process()
170		nullarbor:~ # echo -n 'func svc_process +p' >
171						<debugfs>/dynamic_debug/control
172
173		// disable all 12 messages in the function svc_process()
174		nullarbor:~ # echo -n 'func svc_process -p' >
175						<debugfs>/dynamic_debug/control
176
177	  See Documentation/admin-guide/dynamic-debug-howto.rst for additional
178	  information.
179
180config DYNAMIC_DEBUG_CORE
181	bool "Enable core function of dynamic debug support"
182	depends on PRINTK
183	depends on (DEBUG_FS || PROC_FS)
184	help
185	  Enable core functional support of dynamic debug. It is useful
186	  when you want to tie dynamic debug to your kernel modules with
187	  DYNAMIC_DEBUG_MODULE defined for each of them, especially for
188	  the case of embedded system where the kernel image size is
189	  sensitive for people.
190
191config SYMBOLIC_ERRNAME
192	bool "Support symbolic error names in printf"
193	default y if PRINTK
194	help
195	  If you say Y here, the kernel's printf implementation will
196	  be able to print symbolic error names such as ENOSPC instead
197	  of the number 28. It makes the kernel image slightly larger
198	  (about 3KB), but can make the kernel logs easier to read.
199
200config DEBUG_BUGVERBOSE
201	bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
202	depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
203	default y
204	help
205	  Say Y here to make BUG() panics output the file name and line number
206	  of the BUG call as well as the EIP and oops trace.  This aids
207	  debugging but costs about 70-100K of memory.
208
209endmenu # "printk and dmesg options"
210
211config DEBUG_KERNEL
212	bool "Kernel debugging"
213	help
214	  Say Y here if you are developing drivers or trying to debug and
215	  identify kernel problems.
216
217config DEBUG_MISC
218	bool "Miscellaneous debug code"
219	default DEBUG_KERNEL
220	depends on DEBUG_KERNEL
221	help
222	  Say Y here if you need to enable miscellaneous debug code that should
223	  be under a more specific debug option but isn't.
224
225menu "Compile-time checks and compiler options"
226
227config DEBUG_INFO
228	bool
229	help
230	  A kernel debug info option other than "None" has been selected
231	  in the "Debug information" choice below, indicating that debug
232	  information will be generated for build targets.
233
234# Clang 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
237config AS_HAS_NON_CONST_ULEB128
238	def_bool $(as-instr,.uleb128 .Lexpr_end4 - .Lexpr_start3\n.Lexpr_start3:\n.Lexpr_end4:)
239
240choice
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
253config 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
259config 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
271config 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
283config 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
301endchoice # "Debug information"
302
303if DEBUG_INFO
304
305config 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
317choice
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
325config DEBUG_INFO_COMPRESSED_NONE
326	bool "Don't compress debug information"
327	help
328	  Don't compress debug info sections.
329
330config 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 scripts/package/builddeb 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 to "none" which would be even
343	  larger.
344
345config 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
355endchoice # "Compressed Debug information"
356
357config 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
377config 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 !DEBUG_INFO_DWARF5 || PAHOLE_VERSION >= 121
383	# pahole uses elfutils, which does not have support for Hexagon relocations
384	depends on !HEXAGON
385	help
386	  Generate deduplicated BTF type information from DWARF debug info.
387	  Turning this on expects presence of pahole tool, which will convert
388	  DWARF type info into equivalent deduplicated BTF type info.
389
390config PAHOLE_HAS_SPLIT_BTF
391	def_bool PAHOLE_VERSION >= 119
392
393config PAHOLE_HAS_BTF_TAG
394	def_bool PAHOLE_VERSION >= 123
395	depends on CC_IS_CLANG
396	help
397	  Decide whether pahole emits btf_tag attributes (btf_type_tag and
398	  btf_decl_tag) or not. Currently only clang compiler implements
399	  these attributes, so make the config depend on CC_IS_CLANG.
400
401config PAHOLE_HAS_LANG_EXCLUDE
402	def_bool PAHOLE_VERSION >= 124
403	help
404	  Support for the --lang_exclude flag which makes pahole exclude
405	  compilation units from the supplied language. Used in Kbuild to
406	  omit Rust CUs which are not supported in version 1.24 of pahole,
407	  otherwise it would emit malformed kernel and module binaries when
408	  using DEBUG_INFO_BTF_MODULES.
409
410config DEBUG_INFO_BTF_MODULES
411	bool "Generate BTF type information for kernel modules"
412	default y
413	depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF
414	help
415	  Generate compact split BTF type information for kernel modules.
416
417config MODULE_ALLOW_BTF_MISMATCH
418	bool "Allow loading modules with non-matching BTF type info"
419	depends on DEBUG_INFO_BTF_MODULES
420	help
421	  For modules whose split BTF does not match vmlinux, load without
422	  BTF rather than refusing to load. The default behavior with
423	  module BTF enabled is to reject modules with such mismatches;
424	  this option will still load module BTF where possible but ignore
425	  it when a mismatch is found.
426
427config GDB_SCRIPTS
428	bool "Provide GDB scripts for kernel debugging"
429	help
430	  This creates the required links to GDB helper scripts in the
431	  build directory. If you load vmlinux into gdb, the helper
432	  scripts will be automatically imported by gdb as well, and
433	  additional functions are available to analyze a Linux kernel
434	  instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
435	  for further details.
436
437endif # DEBUG_INFO
438
439config FRAME_WARN
440	int "Warn for stack frames larger than"
441	range 0 8192
442	default 0 if KMSAN
443	default 2048 if GCC_PLUGIN_LATENT_ENTROPY
444	default 2048 if PARISC
445	default 1536 if (!64BIT && XTENSA)
446	default 1280 if KASAN && !64BIT
447	default 1024 if !64BIT
448	default 2048 if 64BIT
449	help
450	  Tell the compiler to warn at build time for stack frames larger than this.
451	  Setting this too low will cause a lot of warnings.
452	  Setting it to 0 disables the warning.
453
454config STRIP_ASM_SYMS
455	bool "Strip assembler-generated symbols during link"
456	default n
457	help
458	  Strip internal assembler-generated symbols during a link (symbols
459	  that look like '.Lxxx') so they don't pollute the output of
460	  get_wchan() and suchlike.
461
462config READABLE_ASM
463	bool "Generate readable assembler code"
464	depends on DEBUG_KERNEL
465	depends on CC_IS_GCC
466	help
467	  Disable some compiler optimizations that tend to generate human unreadable
468	  assembler output. This may make the kernel slightly slower, but it helps
469	  to keep kernel developers who have to stare a lot at assembler listings
470	  sane.
471
472config HEADERS_INSTALL
473	bool "Install uapi headers to usr/include"
474	depends on !UML
475	help
476	  This option will install uapi headers (headers exported to user-space)
477	  into the usr/include directory for use during the kernel build.
478	  This is unneeded for building the kernel itself, but needed for some
479	  user-space program samples. It is also needed by some features such
480	  as uapi header sanity checks.
481
482config DEBUG_SECTION_MISMATCH
483	bool "Enable full Section mismatch analysis"
484	depends on CC_IS_GCC
485	help
486	  The section mismatch analysis checks if there are illegal
487	  references from one section to another section.
488	  During linktime or runtime, some sections are dropped;
489	  any use of code/data previously in these sections would
490	  most likely result in an oops.
491	  In the code, functions and variables are annotated with
492	  __init,, etc. (see the full list in include/linux/init.h),
493	  which results in the code/data being placed in specific sections.
494	  The section mismatch analysis is always performed after a full
495	  kernel build, and enabling this option causes the following
496	  additional step to occur:
497	  - Add the option -fno-inline-functions-called-once to gcc commands.
498	    When inlining a function annotated with __init in a non-init
499	    function, we would lose the section information and thus
500	    the analysis would not catch the illegal reference.
501	    This option tells gcc to inline less (but it does result in
502	    a larger kernel).
503
504config SECTION_MISMATCH_WARN_ONLY
505	bool "Make section mismatch errors non-fatal"
506	default y
507	help
508	  If you say N here, the build process will fail if there are any
509	  section mismatch, instead of just throwing warnings.
510
511	  If unsure, say Y.
512
513config DEBUG_FORCE_FUNCTION_ALIGN_64B
514	bool "Force all function address 64B aligned"
515	depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC || RISCV || S390)
516	select FUNCTION_ALIGNMENT_64B
517	help
518	  There are cases that a commit from one domain changes the function
519	  address alignment of other domains, and cause magic performance
520	  bump (regression or improvement). Enable this option will help to
521	  verify if the bump is caused by function alignment changes, while
522	  it will slightly increase the kernel size and affect icache usage.
523
524	  It is mainly for debug and performance tuning use.
525
526#
527# Select this config option from the architecture Kconfig, if it
528# is preferred to always offer frame pointers as a config
529# option on the architecture (regardless of KERNEL_DEBUG):
530#
531config ARCH_WANT_FRAME_POINTERS
532	bool
533
534config FRAME_POINTER
535	bool "Compile the kernel with frame pointers"
536	depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
537	default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
538	help
539	  If you say Y here the resulting kernel image will be slightly
540	  larger and slower, but it gives very useful debugging information
541	  in case of kernel bugs. (precise oopses/stacktraces/warnings)
542
543config OBJTOOL
544	bool
545
546config STACK_VALIDATION
547	bool "Compile-time stack metadata validation"
548	depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER
549	select OBJTOOL
550	default n
551	help
552	  Validate frame pointer rules at compile-time.  This helps ensure that
553	  runtime stack traces are more reliable.
554
555	  For more information, see
556	  tools/objtool/Documentation/objtool.txt.
557
558config NOINSTR_VALIDATION
559	bool
560	depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY
561	select OBJTOOL
562	default y
563
564config VMLINUX_MAP
565	bool "Generate vmlinux.map file when linking"
566	depends on EXPERT
567	help
568	  Selecting this option will pass "-Map=vmlinux.map" to ld
569	  when linking vmlinux. That file can be useful for verifying
570	  and debugging magic section games, and for seeing which
571	  pieces of code get eliminated with
572	  CONFIG_LD_DEAD_CODE_DATA_ELIMINATION.
573
574config BUILTIN_MODULE_RANGES
575	bool "Generate address range information for builtin modules"
576	depends on !LTO
577	depends on VMLINUX_MAP
578	help
579	 When modules are built into the kernel, there will be no module name
580	 associated with its symbols in /proc/kallsyms.  Tracers may want to
581	 identify symbols by module name and symbol name regardless of whether
582	 the module is configured as loadable or not.
583
584	 This option generates modules.builtin.ranges in the build tree with
585	 offset ranges (per ELF section) for the module(s) they belong to.
586	 It also records an anchor symbol to determine the load address of the
587	 section.
588
589config DEBUG_FORCE_WEAK_PER_CPU
590	bool "Force weak per-cpu definitions"
591	depends on DEBUG_KERNEL
592	help
593	  s390 and alpha require percpu variables in modules to be
594	  defined weak to work around addressing range issue which
595	  puts the following two restrictions on percpu variable
596	  definitions.
597
598	  1. percpu symbols must be unique whether static or not
599	  2. percpu variables can't be defined inside a function
600
601	  To ensure that generic code follows the above rules, this
602	  option forces all percpu variables to be defined as weak.
603
604endmenu # "Compiler options"
605
606menu "Generic Kernel Debugging Instruments"
607
608config MAGIC_SYSRQ
609	bool "Magic SysRq key"
610	depends on !UML
611	help
612	  If you say Y here, you will have some control over the system even
613	  if the system crashes for example during kernel debugging (e.g., you
614	  will be able to flush the buffer cache to disk, reboot the system
615	  immediately or dump some status information). This is accomplished
616	  by pressing various keys while holding SysRq (Alt+PrintScreen). It
617	  also works on a serial console (on PC hardware at least), if you
618	  send a BREAK and then within 5 seconds a command keypress. The
619	  keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
620	  Don't say Y unless you really know what this hack does.
621
622config MAGIC_SYSRQ_DEFAULT_ENABLE
623	hex "Enable magic SysRq key functions by default"
624	depends on MAGIC_SYSRQ
625	default 0x1
626	help
627	  Specifies which SysRq key functions are enabled by default.
628	  This may be set to 1 or 0 to enable or disable them all, or
629	  to a bitmask as described in Documentation/admin-guide/sysrq.rst.
630
631config MAGIC_SYSRQ_SERIAL
632	bool "Enable magic SysRq key over serial"
633	depends on MAGIC_SYSRQ
634	default y
635	help
636	  Many embedded boards have a disconnected TTL level serial which can
637	  generate some garbage that can lead to spurious false sysrq detects.
638	  This option allows you to decide whether you want to enable the
639	  magic SysRq key.
640
641config MAGIC_SYSRQ_SERIAL_SEQUENCE
642	string "Char sequence that enables magic SysRq over serial"
643	depends on MAGIC_SYSRQ_SERIAL
644	default ""
645	help
646	  Specifies a sequence of characters that can follow BREAK to enable
647	  SysRq on a serial console.
648
649	  If unsure, leave an empty string and the option will not be enabled.
650
651config DEBUG_FS
652	bool "Debug Filesystem"
653	help
654	  debugfs is a virtual file system that kernel developers use to put
655	  debugging files into.  Enable this option to be able to read and
656	  write to these files.
657
658	  For detailed documentation on the debugfs API, see
659	  Documentation/filesystems/.
660
661	  If unsure, say N.
662
663choice
664	prompt "Debugfs default access"
665	depends on DEBUG_FS
666	default DEBUG_FS_ALLOW_ALL
667	help
668	  This selects the default access restrictions for debugfs.
669	  It can be overridden with kernel command line option
670	  debugfs=[on,no-mount,off]. The restrictions apply for API access
671	  and filesystem registration.
672
673config DEBUG_FS_ALLOW_ALL
674	bool "Access normal"
675	help
676	  No restrictions apply. Both API and filesystem registration
677	  is on. This is the normal default operation.
678
679config DEBUG_FS_DISALLOW_MOUNT
680	bool "Do not register debugfs as filesystem"
681	help
682	  The API is open but filesystem is not loaded. Clients can still do
683	  their work and read with debug tools that do not need
684	  debugfs filesystem.
685
686config DEBUG_FS_ALLOW_NONE
687	bool "No access"
688	help
689	  Access is off. Clients get -PERM when trying to create nodes in
690	  debugfs tree and debugfs is not registered as a filesystem.
691	  Client can then back-off or continue without debugfs access.
692
693endchoice
694
695source "lib/Kconfig.kgdb"
696source "lib/Kconfig.ubsan"
697source "lib/Kconfig.kcsan"
698
699endmenu
700
701menu "Networking Debugging"
702
703source "net/Kconfig.debug"
704
705endmenu # "Networking Debugging"
706
707menu "Memory Debugging"
708
709source "mm/Kconfig.debug"
710
711config DEBUG_OBJECTS
712	bool "Debug object operations"
713	depends on DEBUG_KERNEL
714	help
715	  If you say Y here, additional code will be inserted into the
716	  kernel to track the life time of various objects and validate
717	  the operations on those objects.
718
719config DEBUG_OBJECTS_SELFTEST
720	bool "Debug objects selftest"
721	depends on DEBUG_OBJECTS
722	help
723	  This enables the selftest of the object debug code.
724
725config DEBUG_OBJECTS_FREE
726	bool "Debug objects in freed memory"
727	depends on DEBUG_OBJECTS
728	help
729	  This enables checks whether a k/v free operation frees an area
730	  which contains an object which has not been deactivated
731	  properly. This can make kmalloc/kfree-intensive workloads
732	  much slower.
733
734config DEBUG_OBJECTS_TIMERS
735	bool "Debug timer objects"
736	depends on DEBUG_OBJECTS
737	help
738	  If you say Y here, additional code will be inserted into the
739	  timer routines to track the life time of timer objects and
740	  validate the timer operations.
741
742config DEBUG_OBJECTS_WORK
743	bool "Debug work objects"
744	depends on DEBUG_OBJECTS
745	help
746	  If you say Y here, additional code will be inserted into the
747	  work queue routines to track the life time of work objects and
748	  validate the work operations.
749
750config DEBUG_OBJECTS_RCU_HEAD
751	bool "Debug RCU callbacks objects"
752	depends on DEBUG_OBJECTS
753	help
754	  Enable this to turn on debugging of RCU list heads (call_rcu() usage).
755
756config DEBUG_OBJECTS_PERCPU_COUNTER
757	bool "Debug percpu counter objects"
758	depends on DEBUG_OBJECTS
759	help
760	  If you say Y here, additional code will be inserted into the
761	  percpu counter routines to track the life time of percpu counter
762	  objects and validate the percpu counter operations.
763
764config DEBUG_OBJECTS_ENABLE_DEFAULT
765	int "debug_objects bootup default value (0-1)"
766	range 0 1
767	default "1"
768	depends on DEBUG_OBJECTS
769	help
770	  Debug objects boot parameter default value
771
772config SHRINKER_DEBUG
773	bool "Enable shrinker debugging support"
774	depends on DEBUG_FS
775	help
776	  Say Y to enable the shrinker debugfs interface which provides
777	  visibility into the kernel memory shrinkers subsystem.
778	  Disable it to avoid an extra memory footprint.
779
780config DEBUG_STACK_USAGE
781	bool "Stack utilization instrumentation"
782	depends on DEBUG_KERNEL
783	help
784	  Enables the display of the minimum amount of free stack which each
785	  task has ever had available in the sysrq-T and sysrq-P debug output.
786	  Also emits a message to dmesg when a process exits if that process
787	  used more stack space than previously exiting processes.
788
789	  This option will slow down process creation somewhat.
790
791config SCHED_STACK_END_CHECK
792	bool "Detect stack corruption on calls to schedule()"
793	depends on DEBUG_KERNEL
794	default n
795	help
796	  This option checks for a stack overrun on calls to schedule().
797	  If the stack end location is found to be over written always panic as
798	  the content of the corrupted region can no longer be trusted.
799	  This is to ensure no erroneous behaviour occurs which could result in
800	  data corruption or a sporadic crash at a later stage once the region
801	  is examined. The runtime overhead introduced is minimal.
802
803config ARCH_HAS_DEBUG_VM_PGTABLE
804	bool
805	help
806	  An architecture should select this when it can successfully
807	  build and run DEBUG_VM_PGTABLE.
808
809config DEBUG_VM_IRQSOFF
810	def_bool DEBUG_VM && !PREEMPT_RT
811
812config DEBUG_VM
813	bool "Debug VM"
814	depends on DEBUG_KERNEL
815	help
816	  Enable this to turn on extended checks in the virtual-memory system
817	  that may impact performance.
818
819	  If unsure, say N.
820
821config DEBUG_VM_SHOOT_LAZIES
822	bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation"
823	depends on DEBUG_VM
824	depends on MMU_LAZY_TLB_SHOOTDOWN
825	help
826	  Enable additional IPIs that ensure lazy tlb mm references are removed
827	  before the mm is freed.
828
829	  If unsure, say N.
830
831config DEBUG_VM_MAPLE_TREE
832	bool "Debug VM maple trees"
833	depends on DEBUG_VM
834	select DEBUG_MAPLE_TREE
835	help
836	  Enable VM maple tree debugging information and extra validations.
837
838	  If unsure, say N.
839
840config DEBUG_VM_RB
841	bool "Debug VM red-black trees"
842	depends on DEBUG_VM
843	help
844	  Enable VM red-black tree debugging information and extra validations.
845
846	  If unsure, say N.
847
848config DEBUG_VM_PGFLAGS
849	bool "Debug page-flags operations"
850	depends on DEBUG_VM
851	help
852	  Enables extra validation on page flags operations.
853
854	  If unsure, say N.
855
856config DEBUG_VM_PGTABLE
857	bool "Debug arch page table for semantics compliance"
858	depends on MMU
859	depends on ARCH_HAS_DEBUG_VM_PGTABLE
860	default y if DEBUG_VM
861	help
862	  This option provides a debug method which can be used to test
863	  architecture page table helper functions on various platforms in
864	  verifying if they comply with expected generic MM semantics. This
865	  will help architecture code in making sure that any changes or
866	  new additions of these helpers still conform to expected
867	  semantics of the generic MM. Platforms will have to opt in for
868	  this through ARCH_HAS_DEBUG_VM_PGTABLE.
869
870	  If unsure, say N.
871
872config ARCH_HAS_DEBUG_VIRTUAL
873	bool
874
875config DEBUG_VIRTUAL
876	bool "Debug VM translations"
877	depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
878	help
879	  Enable some costly sanity checks in virtual to page code. This can
880	  catch mistakes with virt_to_page() and friends.
881
882	  If unsure, say N.
883
884config DEBUG_NOMMU_REGIONS
885	bool "Debug the global anon/private NOMMU mapping region tree"
886	depends on DEBUG_KERNEL && !MMU
887	help
888	  This option causes the global tree of anonymous and private mapping
889	  regions to be regularly checked for invalid topology.
890
891config DEBUG_MEMORY_INIT
892	bool "Debug memory initialisation" if EXPERT
893	default !EXPERT
894	help
895	  Enable this for additional checks during memory initialisation.
896	  The sanity checks verify aspects of the VM such as the memory model
897	  and other information provided by the architecture. Verbose
898	  information will be printed at KERN_DEBUG loglevel depending
899	  on the mminit_loglevel= command-line option.
900
901	  If unsure, say Y
902
903config MEMORY_NOTIFIER_ERROR_INJECT
904	tristate "Memory hotplug notifier error injection module"
905	depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION
906	help
907	  This option provides the ability to inject artificial errors to
908	  memory hotplug notifier chain callbacks.  It is controlled through
909	  debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
910
911	  If the notifier call chain should be failed with some events
912	  notified, write the error code to "actions/<notifier event>/error".
913
914	  Example: Inject memory hotplug offline error (-12 == -ENOMEM)
915
916	  # cd /sys/kernel/debug/notifier-error-inject/memory
917	  # echo -12 > actions/MEM_GOING_OFFLINE/error
918	  # echo offline > /sys/devices/system/memory/memoryXXX/state
919	  bash: echo: write error: Cannot allocate memory
920
921	  To compile this code as a module, choose M here: the module will
922	  be called memory-notifier-error-inject.
923
924	  If unsure, say N.
925
926config DEBUG_PER_CPU_MAPS
927	bool "Debug access to per_cpu maps"
928	depends on DEBUG_KERNEL
929	depends on SMP
930	help
931	  Say Y to verify that the per_cpu map being accessed has
932	  been set up. This adds a fair amount of code to kernel memory
933	  and decreases performance.
934
935	  Say N if unsure.
936
937config DEBUG_KMAP_LOCAL
938	bool "Debug kmap_local temporary mappings"
939	depends on DEBUG_KERNEL && KMAP_LOCAL
940	help
941	  This option enables additional error checking for the kmap_local
942	  infrastructure.  Disable for production use.
943
944config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
945	bool
946
947config DEBUG_KMAP_LOCAL_FORCE_MAP
948	bool "Enforce kmap_local temporary mappings"
949	depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
950	select KMAP_LOCAL
951	select DEBUG_KMAP_LOCAL
952	help
953	  This option enforces temporary mappings through the kmap_local
954	  mechanism for non-highmem pages and on non-highmem systems.
955	  Disable this for production systems!
956
957config DEBUG_HIGHMEM
958	bool "Highmem debugging"
959	depends on DEBUG_KERNEL && HIGHMEM
960	select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
961	select DEBUG_KMAP_LOCAL
962	help
963	  This option enables additional error checking for high memory
964	  systems.  Disable for production systems.
965
966config HAVE_DEBUG_STACKOVERFLOW
967	bool
968
969config DEBUG_STACKOVERFLOW
970	bool "Check for stack overflows"
971	depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
972	help
973	  Say Y here if you want to check for overflows of kernel, IRQ
974	  and exception stacks (if your architecture uses them). This
975	  option will show detailed messages if free stack space drops
976	  below a certain limit.
977
978	  These kinds of bugs usually occur when call-chains in the
979	  kernel get too deep, especially when interrupts are
980	  involved.
981
982	  Use this in cases where you see apparently random memory
983	  corruption, especially if it appears in 'struct thread_info'
984
985	  If in doubt, say "N".
986
987config CODE_TAGGING
988	bool
989	select KALLSYMS
990
991config MEM_ALLOC_PROFILING
992	bool "Enable memory allocation profiling"
993	default n
994	depends on PROC_FS
995	depends on !DEBUG_FORCE_WEAK_PER_CPU
996	select CODE_TAGGING
997	select PAGE_EXTENSION
998	select SLAB_OBJ_EXT
999	help
1000	  Track allocation source code and record total allocation size
1001	  initiated at that code location. The mechanism can be used to track
1002	  memory leaks with a low performance and memory impact.
1003
1004config MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT
1005	bool "Enable memory allocation profiling by default"
1006	default y
1007	depends on MEM_ALLOC_PROFILING
1008
1009config MEM_ALLOC_PROFILING_DEBUG
1010	bool "Memory allocation profiler debugging"
1011	default n
1012	depends on MEM_ALLOC_PROFILING
1013	select MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT
1014	help
1015	  Adds warnings with helpful error messages for memory allocation
1016	  profiling.
1017
1018source "lib/Kconfig.kasan"
1019source "lib/Kconfig.kfence"
1020source "lib/Kconfig.kmsan"
1021
1022endmenu # "Memory Debugging"
1023
1024config DEBUG_SHIRQ
1025	bool "Debug shared IRQ handlers"
1026	depends on DEBUG_KERNEL
1027	help
1028	  Enable this to generate a spurious interrupt just before a shared
1029	  interrupt handler is deregistered (generating one when registering
1030	  is currently disabled). Drivers need to handle this correctly. Some
1031	  don't and need to be caught.
1032
1033menu "Debug Oops, Lockups and Hangs"
1034
1035config PANIC_ON_OOPS
1036	bool "Panic on Oops"
1037	help
1038	  Say Y here to enable the kernel to panic when it oopses. This
1039	  has the same effect as setting oops=panic on the kernel command
1040	  line.
1041
1042	  This feature is useful to ensure that the kernel does not do
1043	  anything erroneous after an oops which could result in data
1044	  corruption or other issues.
1045
1046	  Say N if unsure.
1047
1048config PANIC_ON_OOPS_VALUE
1049	int
1050	range 0 1
1051	default 0 if !PANIC_ON_OOPS
1052	default 1 if PANIC_ON_OOPS
1053
1054config PANIC_TIMEOUT
1055	int "panic timeout"
1056	default 0
1057	help
1058	  Set the timeout value (in seconds) until a reboot occurs when
1059	  the kernel panics. If n = 0, then we wait forever. A timeout
1060	  value n > 0 will wait n seconds before rebooting, while a timeout
1061	  value n < 0 will reboot immediately. This setting can be overridden
1062	  with the kernel command line option panic=, and from userspace via
1063	  /proc/sys/kernel/panic.
1064
1065config LOCKUP_DETECTOR
1066	bool
1067
1068config SOFTLOCKUP_DETECTOR
1069	bool "Detect Soft Lockups"
1070	depends on DEBUG_KERNEL && !S390
1071	select LOCKUP_DETECTOR
1072	help
1073	  Say Y here to enable the kernel to act as a watchdog to detect
1074	  soft lockups.
1075
1076	  Softlockups are bugs that cause the kernel to loop in kernel
1077	  mode for more than 20 seconds, without giving other tasks a
1078	  chance to run.  The current stack trace is displayed upon
1079	  detection and the system will stay locked up.
1080
1081config SOFTLOCKUP_DETECTOR_INTR_STORM
1082	bool "Detect Interrupt Storm in Soft Lockups"
1083	depends on SOFTLOCKUP_DETECTOR && IRQ_TIME_ACCOUNTING
1084	select GENERIC_IRQ_STAT_SNAPSHOT
1085	default y if NR_CPUS <= 128
1086	help
1087	  Say Y here to enable the kernel to detect interrupt storm
1088	  during "soft lockups".
1089
1090	  "soft lockups" can be caused by a variety of reasons. If one is
1091	  caused by an interrupt storm, then the storming interrupts will not
1092	  be on the callstack. To detect this case, it is necessary to report
1093	  the CPU stats and the interrupt counts during the "soft lockups".
1094
1095config BOOTPARAM_SOFTLOCKUP_PANIC
1096	bool "Panic (Reboot) On Soft Lockups"
1097	depends on SOFTLOCKUP_DETECTOR
1098	help
1099	  Say Y here to enable the kernel to panic on "soft lockups",
1100	  which are bugs that cause the kernel to loop in kernel
1101	  mode for more than 20 seconds (configurable using the watchdog_thresh
1102	  sysctl), without giving other tasks a chance to run.
1103
1104	  The panic can be used in combination with panic_timeout,
1105	  to cause the system to reboot automatically after a
1106	  lockup has been detected. This feature is useful for
1107	  high-availability systems that have uptime guarantees and
1108	  where a lockup must be resolved ASAP.
1109
1110	  Say N if unsure.
1111
1112config HAVE_HARDLOCKUP_DETECTOR_BUDDY
1113	bool
1114	depends on SMP
1115	default y
1116
1117#
1118# Global switch whether to build a hardlockup detector at all. It is available
1119# only when the architecture supports at least one implementation. There are
1120# two exceptions. The hardlockup detector is never enabled on:
1121#
1122#	s390: it reported many false positives there
1123#
1124#	sparc64: has a custom implementation which is not using the common
1125#		hardlockup command line options and sysctl interface.
1126#
1127config HARDLOCKUP_DETECTOR
1128	bool "Detect Hard Lockups"
1129	depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64
1130	depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH
1131	imply HARDLOCKUP_DETECTOR_PERF
1132	imply HARDLOCKUP_DETECTOR_BUDDY
1133	imply HARDLOCKUP_DETECTOR_ARCH
1134	select LOCKUP_DETECTOR
1135
1136	help
1137	  Say Y here to enable the kernel to act as a watchdog to detect
1138	  hard lockups.
1139
1140	  Hardlockups are bugs that cause the CPU to loop in kernel mode
1141	  for more than 10 seconds, without letting other interrupts have a
1142	  chance to run.  The current stack trace is displayed upon detection
1143	  and the system will stay locked up.
1144
1145#
1146# Note that arch-specific variants are always preferred.
1147#
1148config HARDLOCKUP_DETECTOR_PREFER_BUDDY
1149	bool "Prefer the buddy CPU hardlockup detector"
1150	depends on HARDLOCKUP_DETECTOR
1151	depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY
1152	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1153	help
1154	  Say Y here to prefer the buddy hardlockup detector over the perf one.
1155
1156	  With the buddy detector, each CPU uses its softlockup hrtimer
1157	  to check that the next CPU is processing hrtimer interrupts by
1158	  verifying that a counter is increasing.
1159
1160	  This hardlockup detector is useful on systems that don't have
1161	  an arch-specific hardlockup detector or if resources needed
1162	  for the hardlockup detector are better used for other things.
1163
1164config HARDLOCKUP_DETECTOR_PERF
1165	bool
1166	depends on HARDLOCKUP_DETECTOR
1167	depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY
1168	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1169	select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1170
1171config HARDLOCKUP_DETECTOR_BUDDY
1172	bool
1173	depends on HARDLOCKUP_DETECTOR
1174	depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY
1175	depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY
1176	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1177	select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1178
1179config HARDLOCKUP_DETECTOR_ARCH
1180	bool
1181	depends on HARDLOCKUP_DETECTOR
1182	depends on HAVE_HARDLOCKUP_DETECTOR_ARCH
1183	help
1184	  The arch-specific implementation of the hardlockup detector will
1185	  be used.
1186
1187#
1188# Both the "perf" and "buddy" hardlockup detectors count hrtimer
1189# interrupts. This config enables functions managing this common code.
1190#
1191config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1192	bool
1193	select SOFTLOCKUP_DETECTOR
1194
1195#
1196# Enables a timestamp based low pass filter to compensate for perf based
1197# hard lockup detection which runs too fast due to turbo modes.
1198#
1199config HARDLOCKUP_CHECK_TIMESTAMP
1200	bool
1201
1202config BOOTPARAM_HARDLOCKUP_PANIC
1203	bool "Panic (Reboot) On Hard Lockups"
1204	depends on HARDLOCKUP_DETECTOR
1205	help
1206	  Say Y here to enable the kernel to panic on "hard lockups",
1207	  which are bugs that cause the kernel to loop in kernel
1208	  mode with interrupts disabled for more than 10 seconds (configurable
1209	  using the watchdog_thresh sysctl).
1210
1211	  Say N if unsure.
1212
1213config DETECT_HUNG_TASK
1214	bool "Detect Hung Tasks"
1215	depends on DEBUG_KERNEL
1216	default SOFTLOCKUP_DETECTOR
1217	help
1218	  Say Y here to enable the kernel to detect "hung tasks",
1219	  which are bugs that cause the task to be stuck in
1220	  uninterruptible "D" state indefinitely.
1221
1222	  When a hung task is detected, the kernel will print the
1223	  current stack trace (which you should report), but the
1224	  task will stay in uninterruptible state. If lockdep is
1225	  enabled then all held locks will also be reported. This
1226	  feature has negligible overhead.
1227
1228config DEFAULT_HUNG_TASK_TIMEOUT
1229	int "Default timeout for hung task detection (in seconds)"
1230	depends on DETECT_HUNG_TASK
1231	default 120
1232	help
1233	  This option controls the default timeout (in seconds) used
1234	  to determine when a task has become non-responsive and should
1235	  be considered hung.
1236
1237	  It can be adjusted at runtime via the kernel.hung_task_timeout_secs
1238	  sysctl or by writing a value to
1239	  /proc/sys/kernel/hung_task_timeout_secs.
1240
1241	  A timeout of 0 disables the check.  The default is two minutes.
1242	  Keeping the default should be fine in most cases.
1243
1244config BOOTPARAM_HUNG_TASK_PANIC
1245	bool "Panic (Reboot) On Hung Tasks"
1246	depends on DETECT_HUNG_TASK
1247	help
1248	  Say Y here to enable the kernel to panic on "hung tasks",
1249	  which are bugs that cause the kernel to leave a task stuck
1250	  in uninterruptible "D" state.
1251
1252	  The panic can be used in combination with panic_timeout,
1253	  to cause the system to reboot automatically after a
1254	  hung task has been detected. This feature is useful for
1255	  high-availability systems that have uptime guarantees and
1256	  where a hung tasks must be resolved ASAP.
1257
1258	  Say N if unsure.
1259
1260config WQ_WATCHDOG
1261	bool "Detect Workqueue Stalls"
1262	depends on DEBUG_KERNEL
1263	help
1264	  Say Y here to enable stall detection on workqueues.  If a
1265	  worker pool doesn't make forward progress on a pending work
1266	  item for over a given amount of time, 30s by default, a
1267	  warning message is printed along with dump of workqueue
1268	  state.  This can be configured through kernel parameter
1269	  "workqueue.watchdog_thresh" and its sysfs counterpart.
1270
1271config WQ_CPU_INTENSIVE_REPORT
1272	bool "Report per-cpu work items which hog CPU for too long"
1273	depends on DEBUG_KERNEL
1274	help
1275	  Say Y here to enable reporting of concurrency-managed per-cpu work
1276	  items that hog CPUs for longer than
1277	  workqueue.cpu_intensive_thresh_us. Workqueue automatically
1278	  detects and excludes them from concurrency management to prevent
1279	  them from stalling other per-cpu work items. Occassional
1280	  triggering may not necessarily indicate a problem. Repeated
1281	  triggering likely indicates that the work item should be switched
1282	  to use an unbound workqueue.
1283
1284config TEST_LOCKUP
1285	tristate "Test module to generate lockups"
1286	depends on m
1287	help
1288	  This builds the "test_lockup" module that helps to make sure
1289	  that watchdogs and lockup detectors are working properly.
1290
1291	  Depending on module parameters it could emulate soft or hard
1292	  lockup, "hung task", or locking arbitrary lock for a long time.
1293	  Also it could generate series of lockups with cooling-down periods.
1294
1295	  If unsure, say N.
1296
1297endmenu # "Debug lockups and hangs"
1298
1299menu "Scheduler Debugging"
1300
1301config SCHED_DEBUG
1302	bool "Collect scheduler debugging info"
1303	depends on DEBUG_KERNEL && DEBUG_FS
1304	default y
1305	help
1306	  If you say Y here, the /sys/kernel/debug/sched file will be provided
1307	  that can help debug the scheduler. The runtime overhead of this
1308	  option is minimal.
1309
1310config SCHED_INFO
1311	bool
1312	default n
1313
1314config SCHEDSTATS
1315	bool "Collect scheduler statistics"
1316	depends on PROC_FS
1317	select SCHED_INFO
1318	help
1319	  If you say Y here, additional code will be inserted into the
1320	  scheduler and related routines to collect statistics about
1321	  scheduler behavior and provide them in /proc/schedstat.  These
1322	  stats may be useful for both tuning and debugging the scheduler
1323	  If you aren't debugging the scheduler or trying to tune a specific
1324	  application, you can say N to avoid the very slight overhead
1325	  this adds.
1326
1327endmenu
1328
1329config DEBUG_TIMEKEEPING
1330	bool "Enable extra timekeeping sanity checking"
1331	help
1332	  This option will enable additional timekeeping sanity checks
1333	  which may be helpful when diagnosing issues where timekeeping
1334	  problems are suspected.
1335
1336	  This may include checks in the timekeeping hotpaths, so this
1337	  option may have a (very small) performance impact to some
1338	  workloads.
1339
1340	  If unsure, say N.
1341
1342config DEBUG_PREEMPT
1343	bool "Debug preemptible kernel"
1344	depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT
1345	help
1346	  If you say Y here then the kernel will use a debug variant of the
1347	  commonly used smp_processor_id() function and will print warnings
1348	  if kernel code uses it in a preemption-unsafe way. Also, the kernel
1349	  will detect preemption count underflows.
1350
1351	  This option has potential to introduce high runtime overhead,
1352	  depending on workload as it triggers debugging routines for each
1353	  this_cpu operation. It should only be used for debugging purposes.
1354
1355menu "Lock Debugging (spinlocks, mutexes, etc...)"
1356
1357config LOCK_DEBUGGING_SUPPORT
1358	bool
1359	depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1360	default y
1361
1362config PROVE_LOCKING
1363	bool "Lock debugging: prove locking correctness"
1364	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1365	select LOCKDEP
1366	select DEBUG_SPINLOCK
1367	select DEBUG_MUTEXES if !PREEMPT_RT
1368	select DEBUG_RT_MUTEXES if RT_MUTEXES
1369	select DEBUG_RWSEMS if !PREEMPT_RT
1370	select DEBUG_WW_MUTEX_SLOWPATH
1371	select DEBUG_LOCK_ALLOC
1372	select PREEMPT_COUNT if !ARCH_NO_PREEMPT
1373	select TRACE_IRQFLAGS
1374	default n
1375	help
1376	 This feature enables the kernel to prove that all locking
1377	 that occurs in the kernel runtime is mathematically
1378	 correct: that under no circumstance could an arbitrary (and
1379	 not yet triggered) combination of observed locking
1380	 sequences (on an arbitrary number of CPUs, running an
1381	 arbitrary number of tasks and interrupt contexts) cause a
1382	 deadlock.
1383
1384	 In short, this feature enables the kernel to report locking
1385	 related deadlocks before they actually occur.
1386
1387	 The proof does not depend on how hard and complex a
1388	 deadlock scenario would be to trigger: how many
1389	 participant CPUs, tasks and irq-contexts would be needed
1390	 for it to trigger. The proof also does not depend on
1391	 timing: if a race and a resulting deadlock is possible
1392	 theoretically (no matter how unlikely the race scenario
1393	 is), it will be proven so and will immediately be
1394	 reported by the kernel (once the event is observed that
1395	 makes the deadlock theoretically possible).
1396
1397	 If a deadlock is impossible (i.e. the locking rules, as
1398	 observed by the kernel, are mathematically correct), the
1399	 kernel reports nothing.
1400
1401	 NOTE: this feature can also be enabled for rwlocks, mutexes
1402	 and rwsems - in which case all dependencies between these
1403	 different locking variants are observed and mapped too, and
1404	 the proof of observed correctness is also maintained for an
1405	 arbitrary combination of these separate locking variants.
1406
1407	 For more details, see Documentation/locking/lockdep-design.rst.
1408
1409config PROVE_RAW_LOCK_NESTING
1410	bool "Enable raw_spinlock - spinlock nesting checks"
1411	depends on PROVE_LOCKING
1412	default n
1413	help
1414	 Enable the raw_spinlock vs. spinlock nesting checks which ensure
1415	 that the lock nesting rules for PREEMPT_RT enabled kernels are
1416	 not violated.
1417
1418	 NOTE: There are known nesting problems. So if you enable this
1419	 option expect lockdep splats until these problems have been fully
1420	 addressed which is work in progress. This config switch allows to
1421	 identify and analyze these problems. It will be removed and the
1422	 check permanently enabled once the main issues have been fixed.
1423
1424	 If unsure, select N.
1425
1426config LOCK_STAT
1427	bool "Lock usage statistics"
1428	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1429	select LOCKDEP
1430	select DEBUG_SPINLOCK
1431	select DEBUG_MUTEXES if !PREEMPT_RT
1432	select DEBUG_RT_MUTEXES if RT_MUTEXES
1433	select DEBUG_LOCK_ALLOC
1434	default n
1435	help
1436	 This feature enables tracking lock contention points
1437
1438	 For more details, see Documentation/locking/lockstat.rst
1439
1440	 This also enables lock events required by "perf lock",
1441	 subcommand of perf.
1442	 If you want to use "perf lock", you also need to turn on
1443	 CONFIG_EVENT_TRACING.
1444
1445	 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1446	 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1447
1448config DEBUG_RT_MUTEXES
1449	bool "RT Mutex debugging, deadlock detection"
1450	depends on DEBUG_KERNEL && RT_MUTEXES
1451	help
1452	 This allows rt mutex semantics violations and rt mutex related
1453	 deadlocks (lockups) to be detected and reported automatically.
1454
1455config DEBUG_SPINLOCK
1456	bool "Spinlock and rw-lock debugging: basic checks"
1457	depends on DEBUG_KERNEL
1458	select UNINLINE_SPIN_UNLOCK
1459	help
1460	  Say Y here and build SMP to catch missing spinlock initialization
1461	  and certain other kinds of spinlock errors commonly made.  This is
1462	  best used in conjunction with the NMI watchdog so that spinlock
1463	  deadlocks are also debuggable.
1464
1465config DEBUG_MUTEXES
1466	bool "Mutex debugging: basic checks"
1467	depends on DEBUG_KERNEL && !PREEMPT_RT
1468	help
1469	 This feature allows mutex semantics violations to be detected and
1470	 reported.
1471
1472config DEBUG_WW_MUTEX_SLOWPATH
1473	bool "Wait/wound mutex debugging: Slowpath testing"
1474	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1475	select DEBUG_LOCK_ALLOC
1476	select DEBUG_SPINLOCK
1477	select DEBUG_MUTEXES if !PREEMPT_RT
1478	select DEBUG_RT_MUTEXES if PREEMPT_RT
1479	help
1480	 This feature enables slowpath testing for w/w mutex users by
1481	 injecting additional -EDEADLK wound/backoff cases. Together with
1482	 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1483	 will test all possible w/w mutex interface abuse with the
1484	 exception of simply not acquiring all the required locks.
1485	 Note that this feature can introduce significant overhead, so
1486	 it really should not be enabled in a production or distro kernel,
1487	 even a debug kernel.  If you are a driver writer, enable it.  If
1488	 you are a distro, do not.
1489
1490config DEBUG_RWSEMS
1491	bool "RW Semaphore debugging: basic checks"
1492	depends on DEBUG_KERNEL && !PREEMPT_RT
1493	help
1494	  This debugging feature allows mismatched rw semaphore locks
1495	  and unlocks to be detected and reported.
1496
1497config DEBUG_LOCK_ALLOC
1498	bool "Lock debugging: detect incorrect freeing of live locks"
1499	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1500	select DEBUG_SPINLOCK
1501	select DEBUG_MUTEXES if !PREEMPT_RT
1502	select DEBUG_RT_MUTEXES if RT_MUTEXES
1503	select LOCKDEP
1504	help
1505	 This feature will check whether any held lock (spinlock, rwlock,
1506	 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1507	 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1508	 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1509	 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1510	 held during task exit.
1511
1512config LOCKDEP
1513	bool
1514	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1515	select STACKTRACE
1516	select KALLSYMS
1517	select KALLSYMS_ALL
1518
1519config LOCKDEP_SMALL
1520	bool
1521
1522config LOCKDEP_BITS
1523	int "Bitsize for MAX_LOCKDEP_ENTRIES"
1524	depends on LOCKDEP && !LOCKDEP_SMALL
1525	range 10 30
1526	default 15
1527	help
1528	  Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message.
1529
1530config LOCKDEP_CHAINS_BITS
1531	int "Bitsize for MAX_LOCKDEP_CHAINS"
1532	depends on LOCKDEP && !LOCKDEP_SMALL
1533	range 10 30
1534	default 16
1535	help
1536	  Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message.
1537
1538config LOCKDEP_STACK_TRACE_BITS
1539	int "Bitsize for MAX_STACK_TRACE_ENTRIES"
1540	depends on LOCKDEP && !LOCKDEP_SMALL
1541	range 10 30
1542	default 19
1543	help
1544	  Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message.
1545
1546config LOCKDEP_STACK_TRACE_HASH_BITS
1547	int "Bitsize for STACK_TRACE_HASH_SIZE"
1548	depends on LOCKDEP && !LOCKDEP_SMALL
1549	range 10 30
1550	default 14
1551	help
1552	  Try increasing this value if you need large STACK_TRACE_HASH_SIZE.
1553
1554config LOCKDEP_CIRCULAR_QUEUE_BITS
1555	int "Bitsize for elements in circular_queue struct"
1556	depends on LOCKDEP
1557	range 10 30
1558	default 12
1559	help
1560	  Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure.
1561
1562config DEBUG_LOCKDEP
1563	bool "Lock dependency engine debugging"
1564	depends on DEBUG_KERNEL && LOCKDEP
1565	select DEBUG_IRQFLAGS
1566	help
1567	  If you say Y here, the lock dependency engine will do
1568	  additional runtime checks to debug itself, at the price
1569	  of more runtime overhead.
1570
1571config DEBUG_ATOMIC_SLEEP
1572	bool "Sleep inside atomic section checking"
1573	select PREEMPT_COUNT
1574	depends on DEBUG_KERNEL
1575	depends on !ARCH_NO_PREEMPT
1576	help
1577	  If you say Y here, various routines which may sleep will become very
1578	  noisy if they are called inside atomic sections: when a spinlock is
1579	  held, inside an rcu read side critical section, inside preempt disabled
1580	  sections, inside an interrupt, etc...
1581
1582config DEBUG_LOCKING_API_SELFTESTS
1583	bool "Locking API boot-time self-tests"
1584	depends on DEBUG_KERNEL
1585	help
1586	  Say Y here if you want the kernel to run a short self-test during
1587	  bootup. The self-test checks whether common types of locking bugs
1588	  are detected by debugging mechanisms or not. (if you disable
1589	  lock debugging then those bugs won't be detected of course.)
1590	  The following locking APIs are covered: spinlocks, rwlocks,
1591	  mutexes and rwsems.
1592
1593config LOCK_TORTURE_TEST
1594	tristate "torture tests for locking"
1595	depends on DEBUG_KERNEL
1596	select TORTURE_TEST
1597	help
1598	  This option provides a kernel module that runs torture tests
1599	  on kernel locking primitives.  The kernel module may be built
1600	  after the fact on the running kernel to be tested, if desired.
1601
1602	  Say Y here if you want kernel locking-primitive torture tests
1603	  to be built into the kernel.
1604	  Say M if you want these torture tests to build as a module.
1605	  Say N if you are unsure.
1606
1607config WW_MUTEX_SELFTEST
1608	tristate "Wait/wound mutex selftests"
1609	help
1610	  This option provides a kernel module that runs tests on the
1611	  on the struct ww_mutex locking API.
1612
1613	  It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1614	  with this test harness.
1615
1616	  Say M if you want these self tests to build as a module.
1617	  Say N if you are unsure.
1618
1619config SCF_TORTURE_TEST
1620	tristate "torture tests for smp_call_function*()"
1621	depends on DEBUG_KERNEL
1622	select TORTURE_TEST
1623	help
1624	  This option provides a kernel module that runs torture tests
1625	  on the smp_call_function() family of primitives.  The kernel
1626	  module may be built after the fact on the running kernel to
1627	  be tested, if desired.
1628
1629config CSD_LOCK_WAIT_DEBUG
1630	bool "Debugging for csd_lock_wait(), called from smp_call_function*()"
1631	depends on DEBUG_KERNEL
1632	depends on 64BIT
1633	default n
1634	help
1635	  This option enables debug prints when CPUs are slow to respond
1636	  to the smp_call_function*() IPI wrappers.  These debug prints
1637	  include the IPI handler function currently executing (if any)
1638	  and relevant stack traces.
1639
1640config CSD_LOCK_WAIT_DEBUG_DEFAULT
1641	bool "Default csd_lock_wait() debugging on at boot time"
1642	depends on CSD_LOCK_WAIT_DEBUG
1643	depends on 64BIT
1644	default n
1645	help
1646	  This option causes the csdlock_debug= kernel boot parameter to
1647	  default to 1 (basic debugging) instead of 0 (no debugging).
1648
1649endmenu # lock debugging
1650
1651config TRACE_IRQFLAGS
1652	depends on TRACE_IRQFLAGS_SUPPORT
1653	bool
1654	help
1655	  Enables hooks to interrupt enabling and disabling for
1656	  either tracing or lock debugging.
1657
1658config TRACE_IRQFLAGS_NMI
1659	def_bool y
1660	depends on TRACE_IRQFLAGS
1661	depends on TRACE_IRQFLAGS_NMI_SUPPORT
1662
1663config NMI_CHECK_CPU
1664	bool "Debugging for CPUs failing to respond to backtrace requests"
1665	depends on DEBUG_KERNEL
1666	depends on X86
1667	default n
1668	help
1669	  Enables debug prints when a CPU fails to respond to a given
1670	  backtrace NMI.  These prints provide some reasons why a CPU
1671	  might legitimately be failing to respond, for example, if it
1672	  is offline of if ignore_nmis is set.
1673
1674config DEBUG_IRQFLAGS
1675	bool "Debug IRQ flag manipulation"
1676	help
1677	  Enables checks for potentially unsafe enabling or disabling of
1678	  interrupts, such as calling raw_local_irq_restore() when interrupts
1679	  are enabled.
1680
1681config STACKTRACE
1682	bool "Stack backtrace support"
1683	depends on STACKTRACE_SUPPORT
1684	help
1685	  This option causes the kernel to create a /proc/pid/stack for
1686	  every process, showing its current stack trace.
1687	  It is also used by various kernel debugging features that require
1688	  stack trace generation.
1689
1690config WARN_ALL_UNSEEDED_RANDOM
1691	bool "Warn for all uses of unseeded randomness"
1692	default n
1693	help
1694	  Some parts of the kernel contain bugs relating to their use of
1695	  cryptographically secure random numbers before it's actually possible
1696	  to generate those numbers securely. This setting ensures that these
1697	  flaws don't go unnoticed, by enabling a message, should this ever
1698	  occur. This will allow people with obscure setups to know when things
1699	  are going wrong, so that they might contact developers about fixing
1700	  it.
1701
1702	  Unfortunately, on some models of some architectures getting
1703	  a fully seeded CRNG is extremely difficult, and so this can
1704	  result in dmesg getting spammed for a surprisingly long
1705	  time.  This is really bad from a security perspective, and
1706	  so architecture maintainers really need to do what they can
1707	  to get the CRNG seeded sooner after the system is booted.
1708	  However, since users cannot do anything actionable to
1709	  address this, by default this option is disabled.
1710
1711	  Say Y here if you want to receive warnings for all uses of
1712	  unseeded randomness.  This will be of use primarily for
1713	  those developers interested in improving the security of
1714	  Linux kernels running on their architecture (or
1715	  subarchitecture).
1716
1717config DEBUG_KOBJECT
1718	bool "kobject debugging"
1719	depends on DEBUG_KERNEL
1720	help
1721	  If you say Y here, some extra kobject debugging messages will be sent
1722	  to the syslog.
1723
1724config DEBUG_KOBJECT_RELEASE
1725	bool "kobject release debugging"
1726	depends on DEBUG_OBJECTS_TIMERS
1727	help
1728	  kobjects are reference counted objects.  This means that their
1729	  last reference count put is not predictable, and the kobject can
1730	  live on past the point at which a driver decides to drop its
1731	  initial reference to the kobject gained on allocation.  An
1732	  example of this would be a struct device which has just been
1733	  unregistered.
1734
1735	  However, some buggy drivers assume that after such an operation,
1736	  the memory backing the kobject can be immediately freed.  This
1737	  goes completely against the principles of a refcounted object.
1738
1739	  If you say Y here, the kernel will delay the release of kobjects
1740	  on the last reference count to improve the visibility of this
1741	  kind of kobject release bug.
1742
1743config HAVE_DEBUG_BUGVERBOSE
1744	bool
1745
1746menu "Debug kernel data structures"
1747
1748config DEBUG_LIST
1749	bool "Debug linked list manipulation"
1750	depends on DEBUG_KERNEL
1751	select LIST_HARDENED
1752	help
1753	  Enable this to turn on extended checks in the linked-list walking
1754	  routines.
1755
1756	  This option trades better quality error reports for performance, and
1757	  is more suitable for kernel debugging. If you care about performance,
1758	  you should only enable CONFIG_LIST_HARDENED instead.
1759
1760	  If unsure, say N.
1761
1762config DEBUG_PLIST
1763	bool "Debug priority linked list manipulation"
1764	depends on DEBUG_KERNEL
1765	help
1766	  Enable this to turn on extended checks in the priority-ordered
1767	  linked-list (plist) walking routines.  This checks the entire
1768	  list multiple times during each manipulation.
1769
1770	  If unsure, say N.
1771
1772config DEBUG_SG
1773	bool "Debug SG table operations"
1774	depends on DEBUG_KERNEL
1775	help
1776	  Enable this to turn on checks on scatter-gather tables. This can
1777	  help find problems with drivers that do not properly initialize
1778	  their sg tables.
1779
1780	  If unsure, say N.
1781
1782config DEBUG_NOTIFIERS
1783	bool "Debug notifier call chains"
1784	depends on DEBUG_KERNEL
1785	help
1786	  Enable this to turn on sanity checking for notifier call chains.
1787	  This is most useful for kernel developers to make sure that
1788	  modules properly unregister themselves from notifier chains.
1789	  This is a relatively cheap check but if you care about maximum
1790	  performance, say N.
1791
1792config DEBUG_CLOSURES
1793	bool "Debug closures (bcache async widgits)"
1794	depends on CLOSURES
1795	select DEBUG_FS
1796	help
1797	  Keeps all active closures in a linked list and provides a debugfs
1798	  interface to list them, which makes it possible to see asynchronous
1799	  operations that get stuck.
1800
1801config DEBUG_MAPLE_TREE
1802	bool "Debug maple trees"
1803	depends on DEBUG_KERNEL
1804	help
1805	  Enable maple tree debugging information and extra validations.
1806
1807	  If unsure, say N.
1808
1809endmenu
1810
1811source "kernel/rcu/Kconfig.debug"
1812
1813config DEBUG_WQ_FORCE_RR_CPU
1814	bool "Force round-robin CPU selection for unbound work items"
1815	depends on DEBUG_KERNEL
1816	default n
1817	help
1818	  Workqueue used to implicitly guarantee that work items queued
1819	  without explicit CPU specified are put on the local CPU.  This
1820	  guarantee is no longer true and while local CPU is still
1821	  preferred work items may be put on foreign CPUs.  Kernel
1822	  parameter "workqueue.debug_force_rr_cpu" is added to force
1823	  round-robin CPU selection to flush out usages which depend on the
1824	  now broken guarantee.  This config option enables the debug
1825	  feature by default.  When enabled, memory and cache locality will
1826	  be impacted.
1827
1828config CPU_HOTPLUG_STATE_CONTROL
1829	bool "Enable CPU hotplug state control"
1830	depends on DEBUG_KERNEL
1831	depends on HOTPLUG_CPU
1832	default n
1833	help
1834	  Allows to write steps between "offline" and "online" to the CPUs
1835	  sysfs target file so states can be stepped granular. This is a debug
1836	  option for now as the hotplug machinery cannot be stopped and
1837	  restarted at arbitrary points yet.
1838
1839	  Say N if your are unsure.
1840
1841config LATENCYTOP
1842	bool "Latency measuring infrastructure"
1843	depends on DEBUG_KERNEL
1844	depends on STACKTRACE_SUPPORT
1845	depends on PROC_FS
1846	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
1847	select KALLSYMS
1848	select KALLSYMS_ALL
1849	select STACKTRACE
1850	select SCHEDSTATS
1851	help
1852	  Enable this option if you want to use the LatencyTOP tool
1853	  to find out which userspace is blocking on what kernel operations.
1854
1855config DEBUG_CGROUP_REF
1856	bool "Disable inlining of cgroup css reference count functions"
1857	depends on DEBUG_KERNEL
1858	depends on CGROUPS
1859	depends on KPROBES
1860	default n
1861	help
1862	  Force cgroup css reference count functions to not be inlined so
1863	  that they can be kprobed for debugging.
1864
1865source "kernel/trace/Kconfig"
1866
1867config PROVIDE_OHCI1394_DMA_INIT
1868	bool "Remote debugging over FireWire early on boot"
1869	depends on PCI && X86
1870	help
1871	  If you want to debug problems which hang or crash the kernel early
1872	  on boot and the crashing machine has a FireWire port, you can use
1873	  this feature to remotely access the memory of the crashed machine
1874	  over FireWire. This employs remote DMA as part of the OHCI1394
1875	  specification which is now the standard for FireWire controllers.
1876
1877	  With remote DMA, you can monitor the printk buffer remotely using
1878	  firescope and access all memory below 4GB using fireproxy from gdb.
1879	  Even controlling a kernel debugger is possible using remote DMA.
1880
1881	  Usage:
1882
1883	  If ohci1394_dma=early is used as boot parameter, it will initialize
1884	  all OHCI1394 controllers which are found in the PCI config space.
1885
1886	  As all changes to the FireWire bus such as enabling and disabling
1887	  devices cause a bus reset and thereby disable remote DMA for all
1888	  devices, be sure to have the cable plugged and FireWire enabled on
1889	  the debugging host before booting the debug target for debugging.
1890
1891	  This code (~1k) is freed after boot. By then, the firewire stack
1892	  in charge of the OHCI-1394 controllers should be used instead.
1893
1894	  See Documentation/core-api/debugging-via-ohci1394.rst for more information.
1895
1896source "samples/Kconfig"
1897
1898config ARCH_HAS_DEVMEM_IS_ALLOWED
1899	bool
1900
1901config STRICT_DEVMEM
1902	bool "Filter access to /dev/mem"
1903	depends on MMU && DEVMEM
1904	depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED
1905	default y if PPC || X86 || ARM64
1906	help
1907	  If this option is disabled, you allow userspace (root) access to all
1908	  of memory, including kernel and userspace memory. Accidental
1909	  access to this is obviously disastrous, but specific access can
1910	  be used by people debugging the kernel. Note that with PAT support
1911	  enabled, even in this case there are restrictions on /dev/mem
1912	  use due to the cache aliasing requirements.
1913
1914	  If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
1915	  file only allows userspace access to PCI space and the BIOS code and
1916	  data regions.  This is sufficient for dosemu and X and all common
1917	  users of /dev/mem.
1918
1919	  If in doubt, say Y.
1920
1921config IO_STRICT_DEVMEM
1922	bool "Filter I/O access to /dev/mem"
1923	depends on STRICT_DEVMEM
1924	help
1925	  If this option is disabled, you allow userspace (root) access to all
1926	  io-memory regardless of whether a driver is actively using that
1927	  range.  Accidental access to this is obviously disastrous, but
1928	  specific access can be used by people debugging kernel drivers.
1929
1930	  If this option is switched on, the /dev/mem file only allows
1931	  userspace access to *idle* io-memory ranges (see /proc/iomem) This
1932	  may break traditional users of /dev/mem (dosemu, legacy X, etc...)
1933	  if the driver using a given range cannot be disabled.
1934
1935	  If in doubt, say Y.
1936
1937menu "$(SRCARCH) Debugging"
1938
1939source "arch/$(SRCARCH)/Kconfig.debug"
1940
1941endmenu
1942
1943menu "Kernel Testing and Coverage"
1944
1945source "lib/kunit/Kconfig"
1946
1947config NOTIFIER_ERROR_INJECTION
1948	tristate "Notifier error injection"
1949	depends on DEBUG_KERNEL
1950	select DEBUG_FS
1951	help
1952	  This option provides the ability to inject artificial errors to
1953	  specified notifier chain callbacks. It is useful to test the error
1954	  handling of notifier call chain failures.
1955
1956	  Say N if unsure.
1957
1958config PM_NOTIFIER_ERROR_INJECT
1959	tristate "PM notifier error injection module"
1960	depends on PM && NOTIFIER_ERROR_INJECTION
1961	default m if PM_DEBUG
1962	help
1963	  This option provides the ability to inject artificial errors to
1964	  PM notifier chain callbacks.  It is controlled through debugfs
1965	  interface /sys/kernel/debug/notifier-error-inject/pm
1966
1967	  If the notifier call chain should be failed with some events
1968	  notified, write the error code to "actions/<notifier event>/error".
1969
1970	  Example: Inject PM suspend error (-12 = -ENOMEM)
1971
1972	  # cd /sys/kernel/debug/notifier-error-inject/pm/
1973	  # echo -12 > actions/PM_SUSPEND_PREPARE/error
1974	  # echo mem > /sys/power/state
1975	  bash: echo: write error: Cannot allocate memory
1976
1977	  To compile this code as a module, choose M here: the module will
1978	  be called pm-notifier-error-inject.
1979
1980	  If unsure, say N.
1981
1982config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1983	tristate "OF reconfig notifier error injection module"
1984	depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1985	help
1986	  This option provides the ability to inject artificial errors to
1987	  OF reconfig notifier chain callbacks.  It is controlled
1988	  through debugfs interface under
1989	  /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1990
1991	  If the notifier call chain should be failed with some events
1992	  notified, write the error code to "actions/<notifier event>/error".
1993
1994	  To compile this code as a module, choose M here: the module will
1995	  be called of-reconfig-notifier-error-inject.
1996
1997	  If unsure, say N.
1998
1999config NETDEV_NOTIFIER_ERROR_INJECT
2000	tristate "Netdev notifier error injection module"
2001	depends on NET && NOTIFIER_ERROR_INJECTION
2002	help
2003	  This option provides the ability to inject artificial errors to
2004	  netdevice notifier chain callbacks.  It is controlled through debugfs
2005	  interface /sys/kernel/debug/notifier-error-inject/netdev
2006
2007	  If the notifier call chain should be failed with some events
2008	  notified, write the error code to "actions/<notifier event>/error".
2009
2010	  Example: Inject netdevice mtu change error (-22 = -EINVAL)
2011
2012	  # cd /sys/kernel/debug/notifier-error-inject/netdev
2013	  # echo -22 > actions/NETDEV_CHANGEMTU/error
2014	  # ip link set eth0 mtu 1024
2015	  RTNETLINK answers: Invalid argument
2016
2017	  To compile this code as a module, choose M here: the module will
2018	  be called netdev-notifier-error-inject.
2019
2020	  If unsure, say N.
2021
2022config FUNCTION_ERROR_INJECTION
2023	bool "Fault-injections of functions"
2024	depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
2025	help
2026	  Add fault injections into various functions that are annotated with
2027	  ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return
2028	  value of these functions. This is useful to test error paths of code.
2029
2030	  If unsure, say N
2031
2032config FAULT_INJECTION
2033	bool "Fault-injection framework"
2034	depends on DEBUG_KERNEL
2035	help
2036	  Provide fault-injection framework.
2037	  For more details, see Documentation/fault-injection/.
2038
2039config FAILSLAB
2040	bool "Fault-injection capability for kmalloc"
2041	depends on FAULT_INJECTION
2042	help
2043	  Provide fault-injection capability for kmalloc.
2044
2045config FAIL_PAGE_ALLOC
2046	bool "Fault-injection capability for alloc_pages()"
2047	depends on FAULT_INJECTION
2048	help
2049	  Provide fault-injection capability for alloc_pages().
2050
2051config FAULT_INJECTION_USERCOPY
2052	bool "Fault injection capability for usercopy functions"
2053	depends on FAULT_INJECTION
2054	help
2055	  Provides fault-injection capability to inject failures
2056	  in usercopy functions (copy_from_user(), get_user(), ...).
2057
2058config FAIL_MAKE_REQUEST
2059	bool "Fault-injection capability for disk IO"
2060	depends on FAULT_INJECTION && BLOCK
2061	help
2062	  Provide fault-injection capability for disk IO.
2063
2064config FAIL_IO_TIMEOUT
2065	bool "Fault-injection capability for faking disk interrupts"
2066	depends on FAULT_INJECTION && BLOCK
2067	help
2068	  Provide fault-injection capability on end IO handling. This
2069	  will make the block layer "forget" an interrupt as configured,
2070	  thus exercising the error handling.
2071
2072	  Only works with drivers that use the generic timeout handling,
2073	  for others it won't do anything.
2074
2075config FAIL_FUTEX
2076	bool "Fault-injection capability for futexes"
2077	select DEBUG_FS
2078	depends on FAULT_INJECTION && FUTEX
2079	help
2080	  Provide fault-injection capability for futexes.
2081
2082config FAULT_INJECTION_DEBUG_FS
2083	bool "Debugfs entries for fault-injection capabilities"
2084	depends on FAULT_INJECTION && SYSFS && DEBUG_FS
2085	help
2086	  Enable configuration of fault-injection capabilities via debugfs.
2087
2088config FAIL_FUNCTION
2089	bool "Fault-injection capability for functions"
2090	depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
2091	help
2092	  Provide function-based fault-injection capability.
2093	  This will allow you to override a specific function with a return
2094	  with given return value. As a result, function caller will see
2095	  an error value and have to handle it. This is useful to test the
2096	  error handling in various subsystems.
2097
2098config FAIL_MMC_REQUEST
2099	bool "Fault-injection capability for MMC IO"
2100	depends on FAULT_INJECTION_DEBUG_FS && MMC
2101	help
2102	  Provide fault-injection capability for MMC IO.
2103	  This will make the mmc core return data errors. This is
2104	  useful to test the error handling in the mmc block device
2105	  and to test how the mmc host driver handles retries from
2106	  the block device.
2107
2108config FAIL_SUNRPC
2109	bool "Fault-injection capability for SunRPC"
2110	depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG
2111	help
2112	  Provide fault-injection capability for SunRPC and
2113	  its consumers.
2114
2115config FAULT_INJECTION_CONFIGFS
2116	bool "Configfs interface for fault-injection capabilities"
2117	depends on FAULT_INJECTION
2118	select CONFIGFS_FS
2119	help
2120	  This option allows configfs-based drivers to dynamically configure
2121	  fault-injection via configfs.  Each parameter for driver-specific
2122	  fault-injection can be made visible as a configfs attribute in a
2123	  configfs group.
2124
2125
2126config FAULT_INJECTION_STACKTRACE_FILTER
2127	bool "stacktrace filter for fault-injection capabilities"
2128	depends on FAULT_INJECTION
2129	depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT
2130	select STACKTRACE
2131	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
2132	help
2133	  Provide stacktrace filter for fault-injection capabilities
2134
2135config ARCH_HAS_KCOV
2136	bool
2137	help
2138	  An architecture should select this when it can successfully
2139	  build and run with CONFIG_KCOV. This typically requires
2140	  disabling instrumentation for some early boot code.
2141
2142config CC_HAS_SANCOV_TRACE_PC
2143	def_bool $(cc-option,-fsanitize-coverage=trace-pc)
2144
2145
2146config KCOV
2147	bool "Code coverage for fuzzing"
2148	depends on ARCH_HAS_KCOV
2149	depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
2150	depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \
2151		   GCC_VERSION >= 120000 || CC_IS_CLANG
2152	select DEBUG_FS
2153	select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
2154	select OBJTOOL if HAVE_NOINSTR_HACK
2155	help
2156	  KCOV exposes kernel code coverage information in a form suitable
2157	  for coverage-guided fuzzing (randomized testing).
2158
2159	  For more details, see Documentation/dev-tools/kcov.rst.
2160
2161config KCOV_ENABLE_COMPARISONS
2162	bool "Enable comparison operands collection by KCOV"
2163	depends on KCOV
2164	depends on $(cc-option,-fsanitize-coverage=trace-cmp)
2165	help
2166	  KCOV also exposes operands of every comparison in the instrumented
2167	  code along with operand sizes and PCs of the comparison instructions.
2168	  These operands can be used by fuzzing engines to improve the quality
2169	  of fuzzing coverage.
2170
2171config KCOV_INSTRUMENT_ALL
2172	bool "Instrument all code by default"
2173	depends on KCOV
2174	default y
2175	help
2176	  If you are doing generic system call fuzzing (like e.g. syzkaller),
2177	  then you will want to instrument the whole kernel and you should
2178	  say y here. If you are doing more targeted fuzzing (like e.g.
2179	  filesystem fuzzing with AFL) then you will want to enable coverage
2180	  for more specific subsets of files, and should say n here.
2181
2182config KCOV_IRQ_AREA_SIZE
2183	hex "Size of interrupt coverage collection area in words"
2184	depends on KCOV
2185	default 0x40000
2186	help
2187	  KCOV uses preallocated per-cpu areas to collect coverage from
2188	  soft interrupts. This specifies the size of those areas in the
2189	  number of unsigned long words.
2190
2191menuconfig RUNTIME_TESTING_MENU
2192	bool "Runtime Testing"
2193	default y
2194
2195if RUNTIME_TESTING_MENU
2196
2197config TEST_DHRY
2198	tristate "Dhrystone benchmark test"
2199	help
2200	  Enable this to include the Dhrystone 2.1 benchmark.  This test
2201	  calculates the number of Dhrystones per second, and the number of
2202	  DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided
2203	  by 1757 (the number of Dhrystones per second obtained on the VAX
2204	  11/780, nominally a 1 MIPS machine).
2205
2206	  To run the benchmark, it needs to be enabled explicitly, either from
2207	  the kernel command line (when built-in), or from userspace (when
2208	  built-in or modular).
2209
2210	  Run once during kernel boot:
2211
2212	      test_dhry.run
2213
2214	  Set number of iterations from kernel command line:
2215
2216	      test_dhry.iterations=<n>
2217
2218	  Set number of iterations from userspace:
2219
2220	      echo <n> > /sys/module/test_dhry/parameters/iterations
2221
2222	  Trigger manual run from userspace:
2223
2224	      echo y > /sys/module/test_dhry/parameters/run
2225
2226	  If the number of iterations is <= 0, the test will devise a suitable
2227	  number of iterations (test runs for at least 2s) automatically.
2228	  This process takes ca. 4s.
2229
2230	  If unsure, say N.
2231
2232config LKDTM
2233	tristate "Linux Kernel Dump Test Tool Module"
2234	depends on DEBUG_FS
2235	help
2236	This module enables testing of the different dumping mechanisms by
2237	inducing system failures at predefined crash points.
2238	If you don't need it: say N
2239	Choose M here to compile this code as a module. The module will be
2240	called lkdtm.
2241
2242	Documentation on how to use the module can be found in
2243	Documentation/fault-injection/provoke-crashes.rst
2244
2245config CPUMASK_KUNIT_TEST
2246	tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS
2247	depends on KUNIT
2248	default KUNIT_ALL_TESTS
2249	help
2250	  Enable to turn on cpumask tests, running at boot or module load time.
2251
2252	  For more information on KUnit and unit tests in general, please refer
2253	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2254
2255	  If unsure, say N.
2256
2257config TEST_LIST_SORT
2258	tristate "Linked list sorting test" if !KUNIT_ALL_TESTS
2259	depends on KUNIT
2260	default KUNIT_ALL_TESTS
2261	help
2262	  Enable this to turn on 'list_sort()' function test. This test is
2263	  executed only once during system boot (so affects only boot time),
2264	  or at module load time.
2265
2266	  If unsure, say N.
2267
2268config TEST_MIN_HEAP
2269	tristate "Min heap test"
2270	depends on DEBUG_KERNEL || m
2271	help
2272	  Enable this to turn on min heap function tests. This test is
2273	  executed only once during system boot (so affects only boot time),
2274	  or at module load time.
2275
2276	  If unsure, say N.
2277
2278config TEST_SORT
2279	tristate "Array-based sort test" if !KUNIT_ALL_TESTS
2280	depends on KUNIT
2281	default KUNIT_ALL_TESTS
2282	help
2283	  This option enables the self-test function of 'sort()' at boot,
2284	  or at module load time.
2285
2286	  If unsure, say N.
2287
2288config TEST_DIV64
2289	tristate "64bit/32bit division and modulo test"
2290	depends on DEBUG_KERNEL || m
2291	help
2292	  Enable this to turn on 'do_div()' function test. This test is
2293	  executed only once during system boot (so affects only boot time),
2294	  or at module load time.
2295
2296	  If unsure, say N.
2297
2298config TEST_IOV_ITER
2299	tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS
2300	depends on KUNIT
2301	depends on MMU
2302	default KUNIT_ALL_TESTS
2303	help
2304	  Enable this to turn on testing of the operation of the I/O iterator
2305	  (iov_iter). This test is executed only once during system boot (so
2306	  affects only boot time), or at module load time.
2307
2308	  If unsure, say N.
2309
2310config KPROBES_SANITY_TEST
2311	tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS
2312	depends on DEBUG_KERNEL
2313	depends on KPROBES
2314	depends on KUNIT
2315	select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
2316	default KUNIT_ALL_TESTS
2317	help
2318	  This option provides for testing basic kprobes functionality on
2319	  boot. Samples of kprobe and kretprobe are inserted and
2320	  verified for functionality.
2321
2322	  Say N if you are unsure.
2323
2324config FPROBE_SANITY_TEST
2325	bool "Self test for fprobe"
2326	depends on DEBUG_KERNEL
2327	depends on FPROBE
2328	depends on KUNIT=y
2329	help
2330	  This option will enable testing the fprobe when the system boot.
2331	  A series of tests are made to verify that the fprobe is functioning
2332	  properly.
2333
2334	  Say N if you are unsure.
2335
2336config BACKTRACE_SELF_TEST
2337	tristate "Self test for the backtrace code"
2338	depends on DEBUG_KERNEL
2339	help
2340	  This option provides a kernel module that can be used to test
2341	  the kernel stack backtrace code. This option is not useful
2342	  for distributions or general kernels, but only for kernel
2343	  developers working on architecture code.
2344
2345	  Note that if you want to also test saved backtraces, you will
2346	  have to enable STACKTRACE as well.
2347
2348	  Say N if you are unsure.
2349
2350config TEST_REF_TRACKER
2351	tristate "Self test for reference tracker"
2352	depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
2353	select REF_TRACKER
2354	help
2355	  This option provides a kernel module performing tests
2356	  using reference tracker infrastructure.
2357
2358	  Say N if you are unsure.
2359
2360config RBTREE_TEST
2361	tristate "Red-Black tree test"
2362	depends on DEBUG_KERNEL
2363	help
2364	  A benchmark measuring the performance of the rbtree library.
2365	  Also includes rbtree invariant checks.
2366
2367config REED_SOLOMON_TEST
2368	tristate "Reed-Solomon library test"
2369	depends on DEBUG_KERNEL || m
2370	select REED_SOLOMON
2371	select REED_SOLOMON_ENC16
2372	select REED_SOLOMON_DEC16
2373	help
2374	  This option enables the self-test function of rslib at boot,
2375	  or at module load time.
2376
2377	  If unsure, say N.
2378
2379config INTERVAL_TREE_TEST
2380	tristate "Interval tree test"
2381	depends on DEBUG_KERNEL
2382	select INTERVAL_TREE
2383	help
2384	  A benchmark measuring the performance of the interval tree library
2385
2386config PERCPU_TEST
2387	tristate "Per cpu operations test"
2388	depends on m && DEBUG_KERNEL
2389	help
2390	  Enable this option to build test module which validates per-cpu
2391	  operations.
2392
2393	  If unsure, say N.
2394
2395config ATOMIC64_SELFTEST
2396	tristate "Perform an atomic64_t self-test"
2397	help
2398	  Enable this option to test the atomic64_t functions at boot or
2399	  at module load time.
2400
2401	  If unsure, say N.
2402
2403config ASYNC_RAID6_TEST
2404	tristate "Self test for hardware accelerated raid6 recovery"
2405	depends on ASYNC_RAID6_RECOV
2406	select ASYNC_MEMCPY
2407	help
2408	  This is a one-shot self test that permutes through the
2409	  recovery of all the possible two disk failure scenarios for a
2410	  N-disk array.  Recovery is performed with the asynchronous
2411	  raid6 recovery routines, and will optionally use an offload
2412	  engine if one is available.
2413
2414	  If unsure, say N.
2415
2416config TEST_HEXDUMP
2417	tristate "Test functions located in the hexdump module at runtime"
2418
2419config STRING_KUNIT_TEST
2420	tristate "KUnit test string functions at runtime" if !KUNIT_ALL_TESTS
2421	depends on KUNIT
2422	default KUNIT_ALL_TESTS
2423
2424config STRING_HELPERS_KUNIT_TEST
2425	tristate "KUnit test string helpers at runtime" if !KUNIT_ALL_TESTS
2426	depends on KUNIT
2427	default KUNIT_ALL_TESTS
2428
2429config TEST_KSTRTOX
2430	tristate "Test kstrto*() family of functions at runtime"
2431
2432config TEST_PRINTF
2433	tristate "Test printf() family of functions at runtime"
2434
2435config TEST_SCANF
2436	tristate "Test scanf() family of functions at runtime"
2437
2438config TEST_BITMAP
2439	tristate "Test bitmap_*() family of functions at runtime"
2440	help
2441	  Enable this option to test the bitmap functions at boot.
2442
2443	  If unsure, say N.
2444
2445config TEST_UUID
2446	tristate "Test functions located in the uuid module at runtime"
2447
2448config TEST_XARRAY
2449	tristate "Test the XArray code at runtime"
2450
2451config TEST_MAPLE_TREE
2452	tristate "Test the Maple Tree code at runtime or module load"
2453	help
2454	  Enable this option to test the maple tree code functions at boot, or
2455	  when the module is loaded. Enable "Debug Maple Trees" will enable
2456	  more verbose output on failures.
2457
2458	  If unsure, say N.
2459
2460config TEST_RHASHTABLE
2461	tristate "Perform selftest on resizable hash table"
2462	help
2463	  Enable this option to test the rhashtable functions at boot.
2464
2465	  If unsure, say N.
2466
2467config TEST_IDA
2468	tristate "Perform selftest on IDA functions"
2469
2470config TEST_PARMAN
2471	tristate "Perform selftest on priority array manager"
2472	depends on PARMAN
2473	help
2474	  Enable this option to test priority array manager on boot
2475	  (or module load).
2476
2477	  If unsure, say N.
2478
2479config TEST_IRQ_TIMINGS
2480	bool "IRQ timings selftest"
2481	depends on IRQ_TIMINGS
2482	help
2483	  Enable this option to test the irq timings code on boot.
2484
2485	  If unsure, say N.
2486
2487config TEST_LKM
2488	tristate "Test module loading with 'hello world' module"
2489	depends on m
2490	help
2491	  This builds the "test_module" module that emits "Hello, world"
2492	  on printk when loaded. It is designed to be used for basic
2493	  evaluation of the module loading subsystem (for example when
2494	  validating module verification). It lacks any extra dependencies,
2495	  and will not normally be loaded by the system unless explicitly
2496	  requested by name.
2497
2498	  If unsure, say N.
2499
2500config TEST_BITOPS
2501	tristate "Test module for compilation of bitops operations"
2502	help
2503	  This builds the "test_bitops" module that is much like the
2504	  TEST_LKM module except that it does a basic exercise of the
2505	  set/clear_bit macros and get_count_order/long to make sure there are
2506	  no compiler warnings from C=1 sparse checker or -Wextra
2507	  compilations. It has no dependencies and doesn't run or load unless
2508	  explicitly requested by name.  for example: modprobe test_bitops.
2509
2510	  If unsure, say N.
2511
2512config TEST_VMALLOC
2513	tristate "Test module for stress/performance analysis of vmalloc allocator"
2514	default n
2515       depends on MMU
2516	depends on m
2517	help
2518	  This builds the "test_vmalloc" module that should be used for
2519	  stress and performance analysis. So, any new change for vmalloc
2520	  subsystem can be evaluated from performance and stability point
2521	  of view.
2522
2523	  If unsure, say N.
2524
2525config TEST_BPF
2526	tristate "Test BPF filter functionality"
2527	depends on m && NET
2528	help
2529	  This builds the "test_bpf" module that runs various test vectors
2530	  against the BPF interpreter or BPF JIT compiler depending on the
2531	  current setting. This is in particular useful for BPF JIT compiler
2532	  development, but also to run regression tests against changes in
2533	  the interpreter code. It also enables test stubs for eBPF maps and
2534	  verifier used by user space verifier testsuite.
2535
2536	  If unsure, say N.
2537
2538config TEST_BLACKHOLE_DEV
2539	tristate "Test blackhole netdev functionality"
2540	depends on m && NET
2541	help
2542	  This builds the "test_blackhole_dev" module that validates the
2543	  data path through this blackhole netdev.
2544
2545	  If unsure, say N.
2546
2547config FIND_BIT_BENCHMARK
2548	tristate "Test find_bit functions"
2549	help
2550	  This builds the "test_find_bit" module that measure find_*_bit()
2551	  functions performance.
2552
2553	  If unsure, say N.
2554
2555config TEST_FIRMWARE
2556	tristate "Test firmware loading via userspace interface"
2557	depends on FW_LOADER
2558	help
2559	  This builds the "test_firmware" module that creates a userspace
2560	  interface for testing firmware loading. This can be used to
2561	  control the triggering of firmware loading without needing an
2562	  actual firmware-using device. The contents can be rechecked by
2563	  userspace.
2564
2565	  If unsure, say N.
2566
2567config TEST_SYSCTL
2568	tristate "sysctl test driver"
2569	depends on PROC_SYSCTL
2570	help
2571	  This builds the "test_sysctl" module. This driver enables to test the
2572	  proc sysctl interfaces available to drivers safely without affecting
2573	  production knobs which might alter system functionality.
2574
2575	  If unsure, say N.
2576
2577config BITFIELD_KUNIT
2578	tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS
2579	depends on KUNIT
2580	default KUNIT_ALL_TESTS
2581	help
2582	  Enable this option to test the bitfield functions at boot.
2583
2584	  KUnit tests run during boot and output the results to the debug log
2585	  in TAP format (http://testanything.org/). Only useful for kernel devs
2586	  running the KUnit test harness, and not intended for inclusion into a
2587	  production build.
2588
2589	  For more information on KUnit and unit tests in general please refer
2590	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2591
2592	  If unsure, say N.
2593
2594config CHECKSUM_KUNIT
2595	tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS
2596	depends on KUNIT
2597	default KUNIT_ALL_TESTS
2598	help
2599	  Enable this option to test the checksum functions at boot.
2600
2601	  KUnit tests run during boot and output the results to the debug log
2602	  in TAP format (http://testanything.org/). Only useful for kernel devs
2603	  running the KUnit test harness, and not intended for inclusion into a
2604	  production build.
2605
2606	  For more information on KUnit and unit tests in general please refer
2607	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2608
2609	  If unsure, say N.
2610
2611config HASH_KUNIT_TEST
2612	tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS
2613	depends on KUNIT
2614	default KUNIT_ALL_TESTS
2615	help
2616	  Enable this option to test the kernel's string (<linux/stringhash.h>), and
2617	  integer (<linux/hash.h>) hash functions on boot.
2618
2619	  KUnit tests run during boot and output the results to the debug log
2620	  in TAP format (https://testanything.org/). Only useful for kernel devs
2621	  running the KUnit test harness, and not intended for inclusion into a
2622	  production build.
2623
2624	  For more information on KUnit and unit tests in general please refer
2625	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2626
2627	  This is intended to help people writing architecture-specific
2628	  optimized versions. If unsure, say N.
2629
2630config RESOURCE_KUNIT_TEST
2631	tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS
2632	depends on KUNIT
2633	default KUNIT_ALL_TESTS
2634	help
2635	  This builds the resource API unit test.
2636	  Tests the logic of API provided by resource.c and ioport.h.
2637	  For more information on KUnit and unit tests in general please refer
2638	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2639
2640	  If unsure, say N.
2641
2642config SYSCTL_KUNIT_TEST
2643	tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS
2644	depends on KUNIT
2645	default KUNIT_ALL_TESTS
2646	help
2647	  This builds the proc sysctl unit test, which runs on boot.
2648	  Tests the API contract and implementation correctness of sysctl.
2649	  For more information on KUnit and unit tests in general please refer
2650	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2651
2652	  If unsure, say N.
2653
2654config LIST_KUNIT_TEST
2655	tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS
2656	depends on KUNIT
2657	default KUNIT_ALL_TESTS
2658	help
2659	  This builds the linked list KUnit test suite.
2660	  It tests that the API and basic functionality of the list_head type
2661	  and associated macros.
2662
2663	  KUnit tests run during boot and output the results to the debug log
2664	  in TAP format (https://testanything.org/). Only useful for kernel devs
2665	  running the KUnit test harness, and not intended for inclusion into a
2666	  production build.
2667
2668	  For more information on KUnit and unit tests in general please refer
2669	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2670
2671	  If unsure, say N.
2672
2673config HASHTABLE_KUNIT_TEST
2674	tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS
2675	depends on KUNIT
2676	default KUNIT_ALL_TESTS
2677	help
2678	  This builds the hashtable KUnit test suite.
2679	  It tests the basic functionality of the API defined in
2680	  include/linux/hashtable.h. For more information on KUnit and
2681	  unit tests in general please refer to the KUnit documentation
2682	  in Documentation/dev-tools/kunit/.
2683
2684	  If unsure, say N.
2685
2686config LINEAR_RANGES_TEST
2687	tristate "KUnit test for linear_ranges"
2688	depends on KUNIT
2689	select LINEAR_RANGES
2690	help
2691	  This builds the linear_ranges unit test, which runs on boot.
2692	  Tests the linear_ranges logic correctness.
2693	  For more information on KUnit and unit tests in general please refer
2694	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2695
2696	  If unsure, say N.
2697
2698config CMDLINE_KUNIT_TEST
2699	tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS
2700	depends on KUNIT
2701	default KUNIT_ALL_TESTS
2702	help
2703	  This builds the cmdline API unit test.
2704	  Tests the logic of API provided by cmdline.c.
2705	  For more information on KUnit and unit tests in general please refer
2706	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2707
2708	  If unsure, say N.
2709
2710config BITS_TEST
2711	tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS
2712	depends on KUNIT
2713	default KUNIT_ALL_TESTS
2714	help
2715	  This builds the bits unit test.
2716	  Tests the logic of macros defined in bits.h.
2717	  For more information on KUnit and unit tests in general please refer
2718	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2719
2720	  If unsure, say N.
2721
2722config SLUB_KUNIT_TEST
2723	tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS
2724	depends on SLUB_DEBUG && KUNIT
2725	default KUNIT_ALL_TESTS
2726	help
2727	  This builds SLUB allocator unit test.
2728	  Tests SLUB cache debugging functionality.
2729	  For more information on KUnit and unit tests in general please refer
2730	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2731
2732	  If unsure, say N.
2733
2734config RATIONAL_KUNIT_TEST
2735	tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS
2736	depends on KUNIT && RATIONAL
2737	default KUNIT_ALL_TESTS
2738	help
2739	  This builds the rational math unit test.
2740	  For more information on KUnit and unit tests in general please refer
2741	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2742
2743	  If unsure, say N.
2744
2745config MEMCPY_KUNIT_TEST
2746	tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS
2747	depends on KUNIT
2748	default KUNIT_ALL_TESTS
2749	help
2750	  Builds unit tests for memcpy(), memmove(), and memset() functions.
2751	  For more information on KUnit and unit tests in general please refer
2752	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2753
2754	  If unsure, say N.
2755
2756config IS_SIGNED_TYPE_KUNIT_TEST
2757	tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS
2758	depends on KUNIT
2759	default KUNIT_ALL_TESTS
2760	help
2761	  Builds unit tests for the is_signed_type() macro.
2762
2763	  For more information on KUnit and unit tests in general please refer
2764	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2765
2766	  If unsure, say N.
2767
2768config OVERFLOW_KUNIT_TEST
2769	tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS
2770	depends on KUNIT
2771	default KUNIT_ALL_TESTS
2772	help
2773	  Builds unit tests for the check_*_overflow(), size_*(), allocation, and
2774	  related functions.
2775
2776	  For more information on KUnit and unit tests in general please refer
2777	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2778
2779	  If unsure, say N.
2780
2781config STACKINIT_KUNIT_TEST
2782	tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS
2783	depends on KUNIT
2784	default KUNIT_ALL_TESTS
2785	help
2786	  Test if the kernel is zero-initializing stack variables and
2787	  padding. Coverage is controlled by compiler flags,
2788	  CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO,
2789	  CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2790	  or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2791
2792config FORTIFY_KUNIT_TEST
2793	tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS
2794	depends on KUNIT
2795	default KUNIT_ALL_TESTS
2796	help
2797	  Builds unit tests for checking internals of FORTIFY_SOURCE as used
2798	  by the str*() and mem*() family of functions. For testing runtime
2799	  traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests.
2800
2801config HW_BREAKPOINT_KUNIT_TEST
2802	bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS
2803	depends on HAVE_HW_BREAKPOINT
2804	depends on KUNIT=y
2805	default KUNIT_ALL_TESTS
2806	help
2807	  Tests for hw_breakpoint constraints accounting.
2808
2809	  If unsure, say N.
2810
2811config SIPHASH_KUNIT_TEST
2812	tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS
2813	depends on KUNIT
2814	default KUNIT_ALL_TESTS
2815	help
2816	  Enable this option to test the kernel's siphash (<linux/siphash.h>) hash
2817	  functions on boot (or module load).
2818
2819	  This is intended to help people writing architecture-specific
2820	  optimized versions.  If unsure, say N.
2821
2822config USERCOPY_KUNIT_TEST
2823	tristate "KUnit Test for user/kernel boundary protections"
2824	depends on KUNIT
2825	default KUNIT_ALL_TESTS
2826	help
2827	  This builds the "usercopy_kunit" module that runs sanity checks
2828	  on the copy_to/from_user infrastructure, making sure basic
2829	  user/kernel boundary testing is working.
2830
2831config TEST_UDELAY
2832	tristate "udelay test driver"
2833	help
2834	  This builds the "udelay_test" module that helps to make sure
2835	  that udelay() is working properly.
2836
2837	  If unsure, say N.
2838
2839config TEST_STATIC_KEYS
2840	tristate "Test static keys"
2841	depends on m
2842	help
2843	  Test the static key interfaces.
2844
2845	  If unsure, say N.
2846
2847config TEST_DYNAMIC_DEBUG
2848	tristate "Test DYNAMIC_DEBUG"
2849	depends on DYNAMIC_DEBUG
2850	help
2851	  This module registers a tracer callback to count enabled
2852	  pr_debugs in a 'do_debugging' function, then alters their
2853	  enablements, calls the function, and compares counts.
2854
2855	  If unsure, say N.
2856
2857config TEST_KMOD
2858	tristate "kmod stress tester"
2859	depends on m
2860	depends on NETDEVICES && NET_CORE && INET # for TUN
2861	depends on BLOCK
2862	depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS
2863	select TEST_LKM
2864	select XFS_FS
2865	select TUN
2866	select BTRFS_FS
2867	help
2868	  Test the kernel's module loading mechanism: kmod. kmod implements
2869	  support to load modules using the Linux kernel's usermode helper.
2870	  This test provides a series of tests against kmod.
2871
2872	  Although technically you can either build test_kmod as a module or
2873	  into the kernel we disallow building it into the kernel since
2874	  it stress tests request_module() and this will very likely cause
2875	  some issues by taking over precious threads available from other
2876	  module load requests, ultimately this could be fatal.
2877
2878	  To run tests run:
2879
2880	  tools/testing/selftests/kmod/kmod.sh --help
2881
2882	  If unsure, say N.
2883
2884config TEST_DEBUG_VIRTUAL
2885	tristate "Test CONFIG_DEBUG_VIRTUAL feature"
2886	depends on DEBUG_VIRTUAL
2887	help
2888	  Test the kernel's ability to detect incorrect calls to
2889	  virt_to_phys() done against the non-linear part of the
2890	  kernel's virtual address map.
2891
2892	  If unsure, say N.
2893
2894config TEST_MEMCAT_P
2895	tristate "Test memcat_p() helper function"
2896	help
2897	  Test the memcat_p() helper for correctly merging two
2898	  pointer arrays together.
2899
2900	  If unsure, say N.
2901
2902config TEST_OBJAGG
2903	tristate "Perform selftest on object aggreration manager"
2904	default n
2905	depends on OBJAGG
2906	help
2907	  Enable this option to test object aggregation manager on boot
2908	  (or module load).
2909
2910config TEST_MEMINIT
2911	tristate "Test heap/page initialization"
2912	help
2913	  Test if the kernel is zero-initializing heap and page allocations.
2914	  This can be useful to test init_on_alloc and init_on_free features.
2915
2916	  If unsure, say N.
2917
2918config TEST_HMM
2919	tristate "Test HMM (Heterogeneous Memory Management)"
2920	depends on TRANSPARENT_HUGEPAGE
2921	depends on DEVICE_PRIVATE
2922	select HMM_MIRROR
2923	select MMU_NOTIFIER
2924	help
2925	  This is a pseudo device driver solely for testing HMM.
2926	  Say M here if you want to build the HMM test module.
2927	  Doing so will allow you to run tools/testing/selftest/vm/hmm-tests.
2928
2929	  If unsure, say N.
2930
2931config TEST_FREE_PAGES
2932	tristate "Test freeing pages"
2933	help
2934	  Test that a memory leak does not occur due to a race between
2935	  freeing a block of pages and a speculative page reference.
2936	  Loading this module is safe if your kernel has the bug fixed.
2937	  If the bug is not fixed, it will leak gigabytes of memory and
2938	  probably OOM your system.
2939
2940config TEST_FPU
2941	tristate "Test floating point operations in kernel space"
2942	depends on ARCH_HAS_KERNEL_FPU_SUPPORT && !KCOV_INSTRUMENT_ALL
2943	help
2944	  Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu
2945	  which will trigger a sequence of floating point operations. This is used
2946	  for self-testing floating point control register setting in
2947	  kernel_fpu_begin().
2948
2949	  If unsure, say N.
2950
2951config TEST_CLOCKSOURCE_WATCHDOG
2952	tristate "Test clocksource watchdog in kernel space"
2953	depends on CLOCKSOURCE_WATCHDOG
2954	help
2955	  Enable this option to create a kernel module that will trigger
2956	  a test of the clocksource watchdog.  This module may be loaded
2957	  via modprobe or insmod in which case it will run upon being
2958	  loaded, or it may be built in, in which case it will run
2959	  shortly after boot.
2960
2961	  If unsure, say N.
2962
2963config TEST_OBJPOOL
2964	tristate "Test module for correctness and stress of objpool"
2965	default n
2966	depends on m && DEBUG_KERNEL
2967	help
2968	  This builds the "test_objpool" module that should be used for
2969	  correctness verification and concurrent testings of objects
2970	  allocation and reclamation.
2971
2972	  If unsure, say N.
2973
2974endif # RUNTIME_TESTING_MENU
2975
2976config ARCH_USE_MEMTEST
2977	bool
2978	help
2979	  An architecture should select this when it uses early_memtest()
2980	  during boot process.
2981
2982config MEMTEST
2983	bool "Memtest"
2984	depends on ARCH_USE_MEMTEST
2985	help
2986	  This option adds a kernel parameter 'memtest', which allows memtest
2987	  to be set and executed.
2988	        memtest=0, mean disabled; -- default
2989	        memtest=1, mean do 1 test pattern;
2990	        ...
2991	        memtest=17, mean do 17 test patterns.
2992	  If you are unsure how to answer this question, answer N.
2993
2994
2995
2996config HYPERV_TESTING
2997	bool "Microsoft Hyper-V driver testing"
2998	default n
2999	depends on HYPERV && DEBUG_FS
3000	help
3001	  Select this option to enable Hyper-V vmbus testing.
3002
3003endmenu # "Kernel Testing and Coverage"
3004
3005menu "Rust hacking"
3006
3007config RUST_DEBUG_ASSERTIONS
3008	bool "Debug assertions"
3009	depends on RUST
3010	help
3011	  Enables rustc's `-Cdebug-assertions` codegen option.
3012
3013	  This flag lets you turn `cfg(debug_assertions)` conditional
3014	  compilation on or off. This can be used to enable extra debugging
3015	  code in development but not in production. For example, it controls
3016	  the behavior of the standard library's `debug_assert!` macro.
3017
3018	  Note that this will apply to all Rust code, including `core`.
3019
3020	  If unsure, say N.
3021
3022config RUST_OVERFLOW_CHECKS
3023	bool "Overflow checks"
3024	default y
3025	depends on RUST
3026	help
3027	  Enables rustc's `-Coverflow-checks` codegen option.
3028
3029	  This flag allows you to control the behavior of runtime integer
3030	  overflow. When overflow-checks are enabled, a Rust panic will occur
3031	  on overflow.
3032
3033	  Note that this will apply to all Rust code, including `core`.
3034
3035	  If unsure, say Y.
3036
3037config RUST_BUILD_ASSERT_ALLOW
3038	bool "Allow unoptimized build-time assertions"
3039	depends on RUST
3040	help
3041	  Controls how are `build_error!` and `build_assert!` handled during build.
3042
3043	  If calls to them exist in the binary, it may indicate a violated invariant
3044	  or that the optimizer failed to verify the invariant during compilation.
3045
3046	  This should not happen, thus by default the build is aborted. However,
3047	  as an escape hatch, you can choose Y here to ignore them during build
3048	  and let the check be carried at runtime (with `panic!` being called if
3049	  the check fails).
3050
3051	  If unsure, say N.
3052
3053config RUST_KERNEL_DOCTESTS
3054	bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS
3055	depends on RUST && KUNIT=y
3056	default KUNIT_ALL_TESTS
3057	help
3058	  This builds the documentation tests of the `kernel` crate
3059	  as KUnit tests.
3060
3061	  For more information on KUnit and unit tests in general,
3062	  please refer to the KUnit documentation in Documentation/dev-tools/kunit/.
3063
3064	  If unsure, say N.
3065
3066endmenu # "Rust"
3067
3068endmenu # Kernel hacking
3069