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1# SPDX-License-Identifier: GPL-2.0-only
2menu "Kernel hacking"
3
4menu "printk and dmesg options"
5
6config PRINTK_TIME
7	bool "Show timing information on printks"
8	depends on PRINTK
9	help
10	  Selecting this option causes time stamps of the printk()
11	  messages to be added to the output of the syslog() system
12	  call and at the console.
13
14	  The timestamp is always recorded internally, and exported
15	  to /dev/kmsg. This flag just specifies if the timestamp should
16	  be included, not that the timestamp is recorded.
17
18	  The behavior is also controlled by the kernel command line
19	  parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst
20
21config PRINTK_CALLER
22	bool "Show caller information on printks"
23	depends on PRINTK
24	help
25	  Selecting this option causes printk() to add a caller "thread id" (if
26	  in task context) or a caller "processor id" (if not in task context)
27	  to every message.
28
29	  This option is intended for environments where multiple threads
30	  concurrently call printk() for many times, for it is difficult to
31	  interpret without knowing where these lines (or sometimes individual
32	  line which was divided into multiple lines due to race) came from.
33
34	  Since toggling after boot makes the code racy, currently there is
35	  no option to enable/disable at the kernel command line parameter or
36	  sysfs interface.
37
38config STACKTRACE_BUILD_ID
39	bool "Show build ID information in stacktraces"
40	depends on PRINTK
41	help
42	  Selecting this option adds build ID information for symbols in
43	  stacktraces printed with the printk format '%p[SR]b'.
44
45	  This option is intended for distros where debuginfo is not easily
46	  accessible but can be downloaded given the build ID of the vmlinux or
47	  kernel module where the function is located.
48
49config CONSOLE_LOGLEVEL_DEFAULT
50	int "Default console loglevel (1-15)"
51	range 1 15
52	default "7"
53	help
54	  Default loglevel to determine what will be printed on the console.
55
56	  Setting a default here is equivalent to passing in loglevel=<x> in
57	  the kernel bootargs. loglevel=<x> continues to override whatever
58	  value is specified here as well.
59
60	  Note: This does not affect the log level of un-prefixed printk()
61	  usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT
62	  option.
63
64config CONSOLE_LOGLEVEL_QUIET
65	int "quiet console loglevel (1-15)"
66	range 1 15
67	default "4"
68	help
69	  loglevel to use when "quiet" is passed on the kernel commandline.
70
71	  When "quiet" is passed on the kernel commandline this loglevel
72	  will be used as the loglevel. IOW passing "quiet" will be the
73	  equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>"
74
75config MESSAGE_LOGLEVEL_DEFAULT
76	int "Default message log level (1-7)"
77	range 1 7
78	default "4"
79	help
80	  Default log level for printk statements with no specified priority.
81
82	  This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
83	  that are auditing their logs closely may want to set it to a lower
84	  priority.
85
86	  Note: This does not affect what message level gets printed on the console
87	  by default. To change that, use loglevel=<x> in the kernel bootargs,
88	  or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value.
89
90config BOOT_PRINTK_DELAY
91	bool "Delay each boot printk message by N milliseconds"
92	depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
93	help
94	  This build option allows you to read kernel boot messages
95	  by inserting a short delay after each one.  The delay is
96	  specified in milliseconds on the kernel command line,
97	  using "boot_delay=N".
98
99	  It is likely that you would also need to use "lpj=M" to preset
100	  the "loops per jiffie" value.
101	  See a previous boot log for the "lpj" value to use for your
102	  system, and then set "lpj=M" before setting "boot_delay=N".
103	  NOTE:  Using this option may adversely affect SMP systems.
104	  I.e., processors other than the first one may not boot up.
105	  BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
106	  what it believes to be lockup conditions.
107
108config DYNAMIC_DEBUG
109	bool "Enable dynamic printk() support"
110	default n
111	depends on PRINTK
112	depends on (DEBUG_FS || PROC_FS)
113	select DYNAMIC_DEBUG_CORE
114	help
115
116	  Compiles debug level messages into the kernel, which would not
117	  otherwise be available at runtime. These messages can then be
118	  enabled/disabled based on various levels of scope - per source file,
119	  function, module, format string, and line number. This mechanism
120	  implicitly compiles in all pr_debug() and dev_dbg() calls, which
121	  enlarges the kernel text size by about 2%.
122
123	  If a source file is compiled with DEBUG flag set, any
124	  pr_debug() calls in it are enabled by default, but can be
125	  disabled at runtime as below.  Note that DEBUG flag is
126	  turned on by many CONFIG_*DEBUG* options.
127
128	  Usage:
129
130	  Dynamic debugging is controlled via the 'dynamic_debug/control' file,
131	  which is contained in the 'debugfs' filesystem or procfs.
132	  Thus, the debugfs or procfs filesystem must first be mounted before
133	  making use of this feature.
134	  We refer the control file as: <debugfs>/dynamic_debug/control. This
135	  file contains a list of the debug statements that can be enabled. The
136	  format for each line of the file is:
137
138		filename:lineno [module]function flags format
139
140	  filename : source file of the debug statement
141	  lineno : line number of the debug statement
142	  module : module that contains the debug statement
143	  function : function that contains the debug statement
144	  flags : '=p' means the line is turned 'on' for printing
145	  format : the format used for the debug statement
146
147	  From a live system:
148
149		nullarbor:~ # cat <debugfs>/dynamic_debug/control
150		# filename:lineno [module]function flags format
151		fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
152		fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
153		fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
154
155	  Example usage:
156
157		// enable the message at line 1603 of file svcsock.c
158		nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
159						<debugfs>/dynamic_debug/control
160
161		// enable all the messages in file svcsock.c
162		nullarbor:~ # echo -n 'file svcsock.c +p' >
163						<debugfs>/dynamic_debug/control
164
165		// enable all the messages in the NFS server module
166		nullarbor:~ # echo -n 'module nfsd +p' >
167						<debugfs>/dynamic_debug/control
168
169		// enable all 12 messages in the function svc_process()
170		nullarbor:~ # echo -n 'func svc_process +p' >
171						<debugfs>/dynamic_debug/control
172
173		// disable all 12 messages in the function svc_process()
174		nullarbor:~ # echo -n 'func svc_process -p' >
175						<debugfs>/dynamic_debug/control
176
177	  See Documentation/admin-guide/dynamic-debug-howto.rst for additional
178	  information.
179
180config DYNAMIC_DEBUG_CORE
181	bool "Enable core function of dynamic debug support"
182	depends on PRINTK
183	depends on (DEBUG_FS || PROC_FS)
184	help
185	  Enable core functional support of dynamic debug. It is useful
186	  when you want to tie dynamic debug to your kernel modules with
187	  DYNAMIC_DEBUG_MODULE defined for each of them, especially for
188	  the case of embedded system where the kernel image size is
189	  sensitive for people.
190
191config SYMBOLIC_ERRNAME
192	bool "Support symbolic error names in printf"
193	default y if PRINTK
194	help
195	  If you say Y here, the kernel's printf implementation will
196	  be able to print symbolic error names such as ENOSPC instead
197	  of the number 28. It makes the kernel image slightly larger
198	  (about 3KB), but can make the kernel logs easier to read.
199
200config DEBUG_BUGVERBOSE
201	bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
202	depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
203	default y
204	help
205	  Say Y here to make BUG() panics output the file name and line number
206	  of the BUG call as well as the EIP and oops trace.  This aids
207	  debugging but costs about 70-100K of memory.
208
209endmenu # "printk and dmesg options"
210
211config DEBUG_KERNEL
212	bool "Kernel debugging"
213	help
214	  Say Y here if you are developing drivers or trying to debug and
215	  identify kernel problems.
216
217config DEBUG_MISC
218	bool "Miscellaneous debug code"
219	default DEBUG_KERNEL
220	depends on DEBUG_KERNEL
221	help
222	  Say Y here if you need to enable miscellaneous debug code that should
223	  be under a more specific debug option but isn't.
224
225menu "Compile-time checks and compiler options"
226
227config DEBUG_INFO
228	bool
229	help
230	  A kernel debug info option other than "None" has been selected
231	  in the "Debug information" choice below, indicating that debug
232	  information will be generated for build targets.
233
234# Clang is known to generate .{s,u}leb128 with symbol deltas with DWARF5, which
235# some targets may not support: https://sourceware.org/bugzilla/show_bug.cgi?id=27215
236config AS_HAS_NON_CONST_LEB128
237	def_bool $(as-instr,.uleb128 .Lexpr_end4 - .Lexpr_start3\n.Lexpr_start3:\n.Lexpr_end4:)
238
239choice
240	prompt "Debug information"
241	depends on DEBUG_KERNEL
242	help
243	  Selecting something other than "None" results in a kernel image
244	  that will include debugging info resulting in a larger kernel image.
245	  This adds debug symbols to the kernel and modules (gcc -g), and
246	  is needed if you intend to use kernel crashdump or binary object
247	  tools like crash, kgdb, LKCD, gdb, etc on the kernel.
248
249	  Choose which version of DWARF debug info to emit. If unsure,
250	  select "Toolchain default".
251
252config DEBUG_INFO_NONE
253	bool "Disable debug information"
254	help
255	  Do not build the kernel with debugging information, which will
256	  result in a faster and smaller build.
257
258config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
259	bool "Rely on the toolchain's implicit default DWARF version"
260	select DEBUG_INFO
261	depends on !CC_IS_CLANG || AS_IS_LLVM || CLANG_VERSION < 140000 || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_LEB128)
262	help
263	  The implicit default version of DWARF debug info produced by a
264	  toolchain changes over time.
265
266	  This can break consumers of the debug info that haven't upgraded to
267	  support newer revisions, and prevent testing newer versions, but
268	  those should be less common scenarios.
269
270config DEBUG_INFO_DWARF4
271	bool "Generate DWARF Version 4 debuginfo"
272	select DEBUG_INFO
273	depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502)
274	help
275	  Generate DWARF v4 debug info. This requires gcc 4.5+, binutils 2.35.2
276	  if using clang without clang's integrated assembler, and gdb 7.0+.
277
278	  If you have consumers of DWARF debug info that are not ready for
279	  newer revisions of DWARF, you may wish to choose this or have your
280	  config select this.
281
282config DEBUG_INFO_DWARF5
283	bool "Generate DWARF Version 5 debuginfo"
284	select DEBUG_INFO
285	depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_LEB128)
286	help
287	  Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc
288	  5.0+ accepts the -gdwarf-5 flag but only had partial support for some
289	  draft features until 7.0), and gdb 8.0+.
290
291	  Changes to the structure of debug info in Version 5 allow for around
292	  15-18% savings in resulting image and debug info section sizes as
293	  compared to DWARF Version 4. DWARF Version 5 standardizes previous
294	  extensions such as accelerators for symbol indexing and the format
295	  for fission (.dwo/.dwp) files. Users may not want to select this
296	  config if they rely on tooling that has not yet been updated to
297	  support DWARF Version 5.
298
299endchoice # "Debug information"
300
301if DEBUG_INFO
302
303config DEBUG_INFO_REDUCED
304	bool "Reduce debugging information"
305	help
306	  If you say Y here gcc is instructed to generate less debugging
307	  information for structure types. This means that tools that
308	  need full debugging information (like kgdb or systemtap) won't
309	  be happy. But if you merely need debugging information to
310	  resolve line numbers there is no loss. Advantage is that
311	  build directory object sizes shrink dramatically over a full
312	  DEBUG_INFO build and compile times are reduced too.
313	  Only works with newer gcc versions.
314
315choice
316	prompt "Compressed Debug information"
317	help
318	  Compress the resulting debug info. Results in smaller debug info sections,
319	  but requires that consumers are able to decompress the results.
320
321	  If unsure, choose DEBUG_INFO_COMPRESSED_NONE.
322
323config DEBUG_INFO_COMPRESSED_NONE
324	bool "Don't compress debug information"
325	help
326	  Don't compress debug info sections.
327
328config DEBUG_INFO_COMPRESSED_ZLIB
329	bool "Compress debugging information with zlib"
330	depends on $(cc-option,-gz=zlib)
331	depends on $(ld-option,--compress-debug-sections=zlib)
332	help
333	  Compress the debug information using zlib.  Requires GCC 5.0+ or Clang
334	  5.0+, binutils 2.26+, and zlib.
335
336	  Users of dpkg-deb via scripts/package/builddeb may find an increase in
337	  size of their debug .deb packages with this config set, due to the
338	  debug info being compressed with zlib, then the object files being
339	  recompressed with a different compression scheme. But this is still
340	  preferable to setting $KDEB_COMPRESS to "none" which would be even
341	  larger.
342
343config DEBUG_INFO_COMPRESSED_ZSTD
344	bool "Compress debugging information with zstd"
345	depends on $(cc-option,-gz=zstd)
346	depends on $(ld-option,--compress-debug-sections=zstd)
347	help
348	  Compress the debug information using zstd.  This may provide better
349	  compression than zlib, for about the same time costs, but requires newer
350	  toolchain support.  Requires GCC 13.0+ or Clang 16.0+, binutils 2.40+, and
351	  zstd.
352
353endchoice # "Compressed Debug information"
354
355config DEBUG_INFO_SPLIT
356	bool "Produce split debuginfo in .dwo files"
357	depends on $(cc-option,-gsplit-dwarf)
358	# RISC-V linker relaxation + -gsplit-dwarf has issues with LLVM and GCC
359	# prior to 12.x:
360	# https://github.com/llvm/llvm-project/issues/56642
361	# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99090
362	depends on !RISCV || GCC_VERSION >= 120000
363	help
364	  Generate debug info into separate .dwo files. This significantly
365	  reduces the build directory size for builds with DEBUG_INFO,
366	  because it stores the information only once on disk in .dwo
367	  files instead of multiple times in object files and executables.
368	  In addition the debug information is also compressed.
369
370	  Requires recent gcc (4.7+) and recent gdb/binutils.
371	  Any tool that packages or reads debug information would need
372	  to know about the .dwo files and include them.
373	  Incompatible with older versions of ccache.
374
375config DEBUG_INFO_BTF
376	bool "Generate BTF type information"
377	depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED
378	depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST
379	depends on BPF_SYSCALL
380	depends on !DEBUG_INFO_DWARF5 || PAHOLE_VERSION >= 121
381	help
382	  Generate deduplicated BTF type information from DWARF debug info.
383	  Turning this on expects presence of pahole tool, which will convert
384	  DWARF type info into equivalent deduplicated BTF type info.
385
386config PAHOLE_HAS_SPLIT_BTF
387	def_bool PAHOLE_VERSION >= 119
388
389config PAHOLE_HAS_BTF_TAG
390	def_bool PAHOLE_VERSION >= 123
391	depends on CC_IS_CLANG
392	help
393	  Decide whether pahole emits btf_tag attributes (btf_type_tag and
394	  btf_decl_tag) or not. Currently only clang compiler implements
395	  these attributes, so make the config depend on CC_IS_CLANG.
396
397config PAHOLE_HAS_LANG_EXCLUDE
398	def_bool PAHOLE_VERSION >= 124
399	help
400	  Support for the --lang_exclude flag which makes pahole exclude
401	  compilation units from the supplied language. Used in Kbuild to
402	  omit Rust CUs which are not supported in version 1.24 of pahole,
403	  otherwise it would emit malformed kernel and module binaries when
404	  using DEBUG_INFO_BTF_MODULES.
405
406config DEBUG_INFO_BTF_MODULES
407	bool "Generate BTF type information for kernel modules"
408	default y
409	depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF
410	help
411	  Generate compact split BTF type information for kernel modules.
412
413config MODULE_ALLOW_BTF_MISMATCH
414	bool "Allow loading modules with non-matching BTF type info"
415	depends on DEBUG_INFO_BTF_MODULES
416	help
417	  For modules whose split BTF does not match vmlinux, load without
418	  BTF rather than refusing to load. The default behavior with
419	  module BTF enabled is to reject modules with such mismatches;
420	  this option will still load module BTF where possible but ignore
421	  it when a mismatch is found.
422
423config GDB_SCRIPTS
424	bool "Provide GDB scripts for kernel debugging"
425	help
426	  This creates the required links to GDB helper scripts in the
427	  build directory. If you load vmlinux into gdb, the helper
428	  scripts will be automatically imported by gdb as well, and
429	  additional functions are available to analyze a Linux kernel
430	  instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
431	  for further details.
432
433endif # DEBUG_INFO
434
435config FRAME_WARN
436	int "Warn for stack frames larger than"
437	range 0 8192
438	default 0 if KMSAN
439	default 2048 if GCC_PLUGIN_LATENT_ENTROPY
440	default 2048 if PARISC
441	default 1536 if (!64BIT && XTENSA)
442	default 1280 if KASAN && !64BIT
443	default 1024 if !64BIT
444	default 2048 if 64BIT
445	help
446	  Tell the compiler to warn at build time for stack frames larger than this.
447	  Setting this too low will cause a lot of warnings.
448	  Setting it to 0 disables the warning.
449
450config STRIP_ASM_SYMS
451	bool "Strip assembler-generated symbols during link"
452	default n
453	help
454	  Strip internal assembler-generated symbols during a link (symbols
455	  that look like '.Lxxx') so they don't pollute the output of
456	  get_wchan() and suchlike.
457
458config READABLE_ASM
459	bool "Generate readable assembler code"
460	depends on DEBUG_KERNEL
461	depends on CC_IS_GCC
462	help
463	  Disable some compiler optimizations that tend to generate human unreadable
464	  assembler output. This may make the kernel slightly slower, but it helps
465	  to keep kernel developers who have to stare a lot at assembler listings
466	  sane.
467
468config HEADERS_INSTALL
469	bool "Install uapi headers to usr/include"
470	depends on !UML
471	help
472	  This option will install uapi headers (headers exported to user-space)
473	  into the usr/include directory for use during the kernel build.
474	  This is unneeded for building the kernel itself, but needed for some
475	  user-space program samples. It is also needed by some features such
476	  as uapi header sanity checks.
477
478config DEBUG_SECTION_MISMATCH
479	bool "Enable full Section mismatch analysis"
480	depends on CC_IS_GCC
481	help
482	  The section mismatch analysis checks if there are illegal
483	  references from one section to another section.
484	  During linktime or runtime, some sections are dropped;
485	  any use of code/data previously in these sections would
486	  most likely result in an oops.
487	  In the code, functions and variables are annotated with
488	  __init,, etc. (see the full list in include/linux/init.h),
489	  which results in the code/data being placed in specific sections.
490	  The section mismatch analysis is always performed after a full
491	  kernel build, and enabling this option causes the following
492	  additional step to occur:
493	  - Add the option -fno-inline-functions-called-once to gcc commands.
494	    When inlining a function annotated with __init in a non-init
495	    function, we would lose the section information and thus
496	    the analysis would not catch the illegal reference.
497	    This option tells gcc to inline less (but it does result in
498	    a larger kernel).
499
500config SECTION_MISMATCH_WARN_ONLY
501	bool "Make section mismatch errors non-fatal"
502	default y
503	help
504	  If you say N here, the build process will fail if there are any
505	  section mismatch, instead of just throwing warnings.
506
507	  If unsure, say Y.
508
509config DEBUG_FORCE_FUNCTION_ALIGN_64B
510	bool "Force all function address 64B aligned"
511	depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC || RISCV || S390)
512	select FUNCTION_ALIGNMENT_64B
513	help
514	  There are cases that a commit from one domain changes the function
515	  address alignment of other domains, and cause magic performance
516	  bump (regression or improvement). Enable this option will help to
517	  verify if the bump is caused by function alignment changes, while
518	  it will slightly increase the kernel size and affect icache usage.
519
520	  It is mainly for debug and performance tuning use.
521
522#
523# Select this config option from the architecture Kconfig, if it
524# is preferred to always offer frame pointers as a config
525# option on the architecture (regardless of KERNEL_DEBUG):
526#
527config ARCH_WANT_FRAME_POINTERS
528	bool
529
530config FRAME_POINTER
531	bool "Compile the kernel with frame pointers"
532	depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
533	default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
534	help
535	  If you say Y here the resulting kernel image will be slightly
536	  larger and slower, but it gives very useful debugging information
537	  in case of kernel bugs. (precise oopses/stacktraces/warnings)
538
539config OBJTOOL
540	bool
541
542config STACK_VALIDATION
543	bool "Compile-time stack metadata validation"
544	depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER
545	select OBJTOOL
546	default n
547	help
548	  Validate frame pointer rules at compile-time.  This helps ensure that
549	  runtime stack traces are more reliable.
550
551	  For more information, see
552	  tools/objtool/Documentation/objtool.txt.
553
554config NOINSTR_VALIDATION
555	bool
556	depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY
557	select OBJTOOL
558	default y
559
560config VMLINUX_MAP
561	bool "Generate vmlinux.map file when linking"
562	depends on EXPERT
563	help
564	  Selecting this option will pass "-Map=vmlinux.map" to ld
565	  when linking vmlinux. That file can be useful for verifying
566	  and debugging magic section games, and for seeing which
567	  pieces of code get eliminated with
568	  CONFIG_LD_DEAD_CODE_DATA_ELIMINATION.
569
570config DEBUG_FORCE_WEAK_PER_CPU
571	bool "Force weak per-cpu definitions"
572	depends on DEBUG_KERNEL
573	help
574	  s390 and alpha require percpu variables in modules to be
575	  defined weak to work around addressing range issue which
576	  puts the following two restrictions on percpu variable
577	  definitions.
578
579	  1. percpu symbols must be unique whether static or not
580	  2. percpu variables can't be defined inside a function
581
582	  To ensure that generic code follows the above rules, this
583	  option forces all percpu variables to be defined as weak.
584
585endmenu # "Compiler options"
586
587menu "Generic Kernel Debugging Instruments"
588
589config MAGIC_SYSRQ
590	bool "Magic SysRq key"
591	depends on !UML
592	help
593	  If you say Y here, you will have some control over the system even
594	  if the system crashes for example during kernel debugging (e.g., you
595	  will be able to flush the buffer cache to disk, reboot the system
596	  immediately or dump some status information). This is accomplished
597	  by pressing various keys while holding SysRq (Alt+PrintScreen). It
598	  also works on a serial console (on PC hardware at least), if you
599	  send a BREAK and then within 5 seconds a command keypress. The
600	  keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
601	  Don't say Y unless you really know what this hack does.
602
603config MAGIC_SYSRQ_DEFAULT_ENABLE
604	hex "Enable magic SysRq key functions by default"
605	depends on MAGIC_SYSRQ
606	default 0x1
607	help
608	  Specifies which SysRq key functions are enabled by default.
609	  This may be set to 1 or 0 to enable or disable them all, or
610	  to a bitmask as described in Documentation/admin-guide/sysrq.rst.
611
612config MAGIC_SYSRQ_SERIAL
613	bool "Enable magic SysRq key over serial"
614	depends on MAGIC_SYSRQ
615	default y
616	help
617	  Many embedded boards have a disconnected TTL level serial which can
618	  generate some garbage that can lead to spurious false sysrq detects.
619	  This option allows you to decide whether you want to enable the
620	  magic SysRq key.
621
622config MAGIC_SYSRQ_SERIAL_SEQUENCE
623	string "Char sequence that enables magic SysRq over serial"
624	depends on MAGIC_SYSRQ_SERIAL
625	default ""
626	help
627	  Specifies a sequence of characters that can follow BREAK to enable
628	  SysRq on a serial console.
629
630	  If unsure, leave an empty string and the option will not be enabled.
631
632config DEBUG_FS
633	bool "Debug Filesystem"
634	help
635	  debugfs is a virtual file system that kernel developers use to put
636	  debugging files into.  Enable this option to be able to read and
637	  write to these files.
638
639	  For detailed documentation on the debugfs API, see
640	  Documentation/filesystems/.
641
642	  If unsure, say N.
643
644choice
645	prompt "Debugfs default access"
646	depends on DEBUG_FS
647	default DEBUG_FS_ALLOW_ALL
648	help
649	  This selects the default access restrictions for debugfs.
650	  It can be overridden with kernel command line option
651	  debugfs=[on,no-mount,off]. The restrictions apply for API access
652	  and filesystem registration.
653
654config DEBUG_FS_ALLOW_ALL
655	bool "Access normal"
656	help
657	  No restrictions apply. Both API and filesystem registration
658	  is on. This is the normal default operation.
659
660config DEBUG_FS_DISALLOW_MOUNT
661	bool "Do not register debugfs as filesystem"
662	help
663	  The API is open but filesystem is not loaded. Clients can still do
664	  their work and read with debug tools that do not need
665	  debugfs filesystem.
666
667config DEBUG_FS_ALLOW_NONE
668	bool "No access"
669	help
670	  Access is off. Clients get -PERM when trying to create nodes in
671	  debugfs tree and debugfs is not registered as a filesystem.
672	  Client can then back-off or continue without debugfs access.
673
674endchoice
675
676source "lib/Kconfig.kgdb"
677source "lib/Kconfig.ubsan"
678source "lib/Kconfig.kcsan"
679
680endmenu
681
682menu "Networking Debugging"
683
684source "net/Kconfig.debug"
685
686endmenu # "Networking Debugging"
687
688menu "Memory Debugging"
689
690source "mm/Kconfig.debug"
691
692config DEBUG_OBJECTS
693	bool "Debug object operations"
694	depends on DEBUG_KERNEL
695	help
696	  If you say Y here, additional code will be inserted into the
697	  kernel to track the life time of various objects and validate
698	  the operations on those objects.
699
700config DEBUG_OBJECTS_SELFTEST
701	bool "Debug objects selftest"
702	depends on DEBUG_OBJECTS
703	help
704	  This enables the selftest of the object debug code.
705
706config DEBUG_OBJECTS_FREE
707	bool "Debug objects in freed memory"
708	depends on DEBUG_OBJECTS
709	help
710	  This enables checks whether a k/v free operation frees an area
711	  which contains an object which has not been deactivated
712	  properly. This can make kmalloc/kfree-intensive workloads
713	  much slower.
714
715config DEBUG_OBJECTS_TIMERS
716	bool "Debug timer objects"
717	depends on DEBUG_OBJECTS
718	help
719	  If you say Y here, additional code will be inserted into the
720	  timer routines to track the life time of timer objects and
721	  validate the timer operations.
722
723config DEBUG_OBJECTS_WORK
724	bool "Debug work objects"
725	depends on DEBUG_OBJECTS
726	help
727	  If you say Y here, additional code will be inserted into the
728	  work queue routines to track the life time of work objects and
729	  validate the work operations.
730
731config DEBUG_OBJECTS_RCU_HEAD
732	bool "Debug RCU callbacks objects"
733	depends on DEBUG_OBJECTS
734	help
735	  Enable this to turn on debugging of RCU list heads (call_rcu() usage).
736
737config DEBUG_OBJECTS_PERCPU_COUNTER
738	bool "Debug percpu counter objects"
739	depends on DEBUG_OBJECTS
740	help
741	  If you say Y here, additional code will be inserted into the
742	  percpu counter routines to track the life time of percpu counter
743	  objects and validate the percpu counter operations.
744
745config DEBUG_OBJECTS_ENABLE_DEFAULT
746	int "debug_objects bootup default value (0-1)"
747	range 0 1
748	default "1"
749	depends on DEBUG_OBJECTS
750	help
751	  Debug objects boot parameter default value
752
753config SHRINKER_DEBUG
754	bool "Enable shrinker debugging support"
755	depends on DEBUG_FS
756	help
757	  Say Y to enable the shrinker debugfs interface which provides
758	  visibility into the kernel memory shrinkers subsystem.
759	  Disable it to avoid an extra memory footprint.
760
761config DEBUG_STACK_USAGE
762	bool "Stack utilization instrumentation"
763	depends on DEBUG_KERNEL && !IA64
764	help
765	  Enables the display of the minimum amount of free stack which each
766	  task has ever had available in the sysrq-T and sysrq-P debug output.
767
768	  This option will slow down process creation somewhat.
769
770config SCHED_STACK_END_CHECK
771	bool "Detect stack corruption on calls to schedule()"
772	depends on DEBUG_KERNEL
773	default n
774	help
775	  This option checks for a stack overrun on calls to schedule().
776	  If the stack end location is found to be over written always panic as
777	  the content of the corrupted region can no longer be trusted.
778	  This is to ensure no erroneous behaviour occurs which could result in
779	  data corruption or a sporadic crash at a later stage once the region
780	  is examined. The runtime overhead introduced is minimal.
781
782config ARCH_HAS_DEBUG_VM_PGTABLE
783	bool
784	help
785	  An architecture should select this when it can successfully
786	  build and run DEBUG_VM_PGTABLE.
787
788config DEBUG_VM_IRQSOFF
789	def_bool DEBUG_VM && !PREEMPT_RT
790
791config DEBUG_VM
792	bool "Debug VM"
793	depends on DEBUG_KERNEL
794	help
795	  Enable this to turn on extended checks in the virtual-memory system
796	  that may impact performance.
797
798	  If unsure, say N.
799
800config DEBUG_VM_SHOOT_LAZIES
801	bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation"
802	depends on DEBUG_VM
803	depends on MMU_LAZY_TLB_SHOOTDOWN
804	help
805	  Enable additional IPIs that ensure lazy tlb mm references are removed
806	  before the mm is freed.
807
808	  If unsure, say N.
809
810config DEBUG_VM_MAPLE_TREE
811	bool "Debug VM maple trees"
812	depends on DEBUG_VM
813	select DEBUG_MAPLE_TREE
814	help
815	  Enable VM maple tree debugging information and extra validations.
816
817	  If unsure, say N.
818
819config DEBUG_VM_RB
820	bool "Debug VM red-black trees"
821	depends on DEBUG_VM
822	help
823	  Enable VM red-black tree debugging information and extra validations.
824
825	  If unsure, say N.
826
827config DEBUG_VM_PGFLAGS
828	bool "Debug page-flags operations"
829	depends on DEBUG_VM
830	help
831	  Enables extra validation on page flags operations.
832
833	  If unsure, say N.
834
835config DEBUG_VM_PGTABLE
836	bool "Debug arch page table for semantics compliance"
837	depends on MMU
838	depends on ARCH_HAS_DEBUG_VM_PGTABLE
839	default y if DEBUG_VM
840	help
841	  This option provides a debug method which can be used to test
842	  architecture page table helper functions on various platforms in
843	  verifying if they comply with expected generic MM semantics. This
844	  will help architecture code in making sure that any changes or
845	  new additions of these helpers still conform to expected
846	  semantics of the generic MM. Platforms will have to opt in for
847	  this through ARCH_HAS_DEBUG_VM_PGTABLE.
848
849	  If unsure, say N.
850
851config ARCH_HAS_DEBUG_VIRTUAL
852	bool
853
854config DEBUG_VIRTUAL
855	bool "Debug VM translations"
856	depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
857	help
858	  Enable some costly sanity checks in virtual to page code. This can
859	  catch mistakes with virt_to_page() and friends.
860
861	  If unsure, say N.
862
863config DEBUG_NOMMU_REGIONS
864	bool "Debug the global anon/private NOMMU mapping region tree"
865	depends on DEBUG_KERNEL && !MMU
866	help
867	  This option causes the global tree of anonymous and private mapping
868	  regions to be regularly checked for invalid topology.
869
870config DEBUG_MEMORY_INIT
871	bool "Debug memory initialisation" if EXPERT
872	default !EXPERT
873	help
874	  Enable this for additional checks during memory initialisation.
875	  The sanity checks verify aspects of the VM such as the memory model
876	  and other information provided by the architecture. Verbose
877	  information will be printed at KERN_DEBUG loglevel depending
878	  on the mminit_loglevel= command-line option.
879
880	  If unsure, say Y
881
882config MEMORY_NOTIFIER_ERROR_INJECT
883	tristate "Memory hotplug notifier error injection module"
884	depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION
885	help
886	  This option provides the ability to inject artificial errors to
887	  memory hotplug notifier chain callbacks.  It is controlled through
888	  debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
889
890	  If the notifier call chain should be failed with some events
891	  notified, write the error code to "actions/<notifier event>/error".
892
893	  Example: Inject memory hotplug offline error (-12 == -ENOMEM)
894
895	  # cd /sys/kernel/debug/notifier-error-inject/memory
896	  # echo -12 > actions/MEM_GOING_OFFLINE/error
897	  # echo offline > /sys/devices/system/memory/memoryXXX/state
898	  bash: echo: write error: Cannot allocate memory
899
900	  To compile this code as a module, choose M here: the module will
901	  be called memory-notifier-error-inject.
902
903	  If unsure, say N.
904
905config DEBUG_PER_CPU_MAPS
906	bool "Debug access to per_cpu maps"
907	depends on DEBUG_KERNEL
908	depends on SMP
909	help
910	  Say Y to verify that the per_cpu map being accessed has
911	  been set up. This adds a fair amount of code to kernel memory
912	  and decreases performance.
913
914	  Say N if unsure.
915
916config DEBUG_KMAP_LOCAL
917	bool "Debug kmap_local temporary mappings"
918	depends on DEBUG_KERNEL && KMAP_LOCAL
919	help
920	  This option enables additional error checking for the kmap_local
921	  infrastructure.  Disable for production use.
922
923config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
924	bool
925
926config DEBUG_KMAP_LOCAL_FORCE_MAP
927	bool "Enforce kmap_local temporary mappings"
928	depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
929	select KMAP_LOCAL
930	select DEBUG_KMAP_LOCAL
931	help
932	  This option enforces temporary mappings through the kmap_local
933	  mechanism for non-highmem pages and on non-highmem systems.
934	  Disable this for production systems!
935
936config DEBUG_HIGHMEM
937	bool "Highmem debugging"
938	depends on DEBUG_KERNEL && HIGHMEM
939	select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
940	select DEBUG_KMAP_LOCAL
941	help
942	  This option enables additional error checking for high memory
943	  systems.  Disable for production systems.
944
945config HAVE_DEBUG_STACKOVERFLOW
946	bool
947
948config DEBUG_STACKOVERFLOW
949	bool "Check for stack overflows"
950	depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
951	help
952	  Say Y here if you want to check for overflows of kernel, IRQ
953	  and exception stacks (if your architecture uses them). This
954	  option will show detailed messages if free stack space drops
955	  below a certain limit.
956
957	  These kinds of bugs usually occur when call-chains in the
958	  kernel get too deep, especially when interrupts are
959	  involved.
960
961	  Use this in cases where you see apparently random memory
962	  corruption, especially if it appears in 'struct thread_info'
963
964	  If in doubt, say "N".
965
966source "lib/Kconfig.kasan"
967source "lib/Kconfig.kfence"
968source "lib/Kconfig.kmsan"
969
970endmenu # "Memory Debugging"
971
972config DEBUG_SHIRQ
973	bool "Debug shared IRQ handlers"
974	depends on DEBUG_KERNEL
975	help
976	  Enable this to generate a spurious interrupt just before a shared
977	  interrupt handler is deregistered (generating one when registering
978	  is currently disabled). Drivers need to handle this correctly. Some
979	  don't and need to be caught.
980
981menu "Debug Oops, Lockups and Hangs"
982
983config PANIC_ON_OOPS
984	bool "Panic on Oops"
985	help
986	  Say Y here to enable the kernel to panic when it oopses. This
987	  has the same effect as setting oops=panic on the kernel command
988	  line.
989
990	  This feature is useful to ensure that the kernel does not do
991	  anything erroneous after an oops which could result in data
992	  corruption or other issues.
993
994	  Say N if unsure.
995
996config PANIC_ON_OOPS_VALUE
997	int
998	range 0 1
999	default 0 if !PANIC_ON_OOPS
1000	default 1 if PANIC_ON_OOPS
1001
1002config PANIC_TIMEOUT
1003	int "panic timeout"
1004	default 0
1005	help
1006	  Set the timeout value (in seconds) until a reboot occurs when
1007	  the kernel panics. If n = 0, then we wait forever. A timeout
1008	  value n > 0 will wait n seconds before rebooting, while a timeout
1009	  value n < 0 will reboot immediately.
1010
1011config LOCKUP_DETECTOR
1012	bool
1013
1014config SOFTLOCKUP_DETECTOR
1015	bool "Detect Soft Lockups"
1016	depends on DEBUG_KERNEL && !S390
1017	select LOCKUP_DETECTOR
1018	help
1019	  Say Y here to enable the kernel to act as a watchdog to detect
1020	  soft lockups.
1021
1022	  Softlockups are bugs that cause the kernel to loop in kernel
1023	  mode for more than 20 seconds, without giving other tasks a
1024	  chance to run.  The current stack trace is displayed upon
1025	  detection and the system will stay locked up.
1026
1027config SOFTLOCKUP_DETECTOR_INTR_STORM
1028	bool "Detect Interrupt Storm in Soft Lockups"
1029	depends on SOFTLOCKUP_DETECTOR && IRQ_TIME_ACCOUNTING
1030	select GENERIC_IRQ_STAT_SNAPSHOT
1031	default y if NR_CPUS <= 128
1032	help
1033	  Say Y here to enable the kernel to detect interrupt storm
1034	  during "soft lockups".
1035
1036	  "soft lockups" can be caused by a variety of reasons. If one is
1037	  caused by an interrupt storm, then the storming interrupts will not
1038	  be on the callstack. To detect this case, it is necessary to report
1039	  the CPU stats and the interrupt counts during the "soft lockups".
1040
1041config BOOTPARAM_SOFTLOCKUP_PANIC
1042	bool "Panic (Reboot) On Soft Lockups"
1043	depends on SOFTLOCKUP_DETECTOR
1044	help
1045	  Say Y here to enable the kernel to panic on "soft lockups",
1046	  which are bugs that cause the kernel to loop in kernel
1047	  mode for more than 20 seconds (configurable using the watchdog_thresh
1048	  sysctl), without giving other tasks a chance to run.
1049
1050	  The panic can be used in combination with panic_timeout,
1051	  to cause the system to reboot automatically after a
1052	  lockup has been detected. This feature is useful for
1053	  high-availability systems that have uptime guarantees and
1054	  where a lockup must be resolved ASAP.
1055
1056	  Say N if unsure.
1057
1058config HAVE_HARDLOCKUP_DETECTOR_BUDDY
1059	bool
1060	depends on SMP
1061	default y
1062
1063#
1064# Global switch whether to build a hardlockup detector at all. It is available
1065# only when the architecture supports at least one implementation. There are
1066# two exceptions. The hardlockup detector is never enabled on:
1067#
1068#	s390: it reported many false positives there
1069#
1070#	sparc64: has a custom implementation which is not using the common
1071#		hardlockup command line options and sysctl interface.
1072#
1073config HARDLOCKUP_DETECTOR
1074	bool "Detect Hard Lockups"
1075	depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64
1076	depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH
1077	imply HARDLOCKUP_DETECTOR_PERF
1078	imply HARDLOCKUP_DETECTOR_BUDDY
1079	imply HARDLOCKUP_DETECTOR_ARCH
1080	select LOCKUP_DETECTOR
1081
1082	help
1083	  Say Y here to enable the kernel to act as a watchdog to detect
1084	  hard lockups.
1085
1086	  Hardlockups are bugs that cause the CPU to loop in kernel mode
1087	  for more than 10 seconds, without letting other interrupts have a
1088	  chance to run.  The current stack trace is displayed upon detection
1089	  and the system will stay locked up.
1090
1091#
1092# Note that arch-specific variants are always preferred.
1093#
1094config HARDLOCKUP_DETECTOR_PREFER_BUDDY
1095	bool "Prefer the buddy CPU hardlockup detector"
1096	depends on HARDLOCKUP_DETECTOR
1097	depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY
1098	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1099	help
1100	  Say Y here to prefer the buddy hardlockup detector over the perf one.
1101
1102	  With the buddy detector, each CPU uses its softlockup hrtimer
1103	  to check that the next CPU is processing hrtimer interrupts by
1104	  verifying that a counter is increasing.
1105
1106	  This hardlockup detector is useful on systems that don't have
1107	  an arch-specific hardlockup detector or if resources needed
1108	  for the hardlockup detector are better used for other things.
1109
1110config HARDLOCKUP_DETECTOR_PERF
1111	bool
1112	depends on HARDLOCKUP_DETECTOR
1113	depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY
1114	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1115	select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1116
1117config HARDLOCKUP_DETECTOR_BUDDY
1118	bool
1119	depends on HARDLOCKUP_DETECTOR
1120	depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY
1121	depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY
1122	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1123	select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1124
1125config HARDLOCKUP_DETECTOR_ARCH
1126	bool
1127	depends on HARDLOCKUP_DETECTOR
1128	depends on HAVE_HARDLOCKUP_DETECTOR_ARCH
1129	help
1130	  The arch-specific implementation of the hardlockup detector will
1131	  be used.
1132
1133#
1134# Both the "perf" and "buddy" hardlockup detectors count hrtimer
1135# interrupts. This config enables functions managing this common code.
1136#
1137config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1138	bool
1139	select SOFTLOCKUP_DETECTOR
1140
1141#
1142# Enables a timestamp based low pass filter to compensate for perf based
1143# hard lockup detection which runs too fast due to turbo modes.
1144#
1145config HARDLOCKUP_CHECK_TIMESTAMP
1146	bool
1147
1148config BOOTPARAM_HARDLOCKUP_PANIC
1149	bool "Panic (Reboot) On Hard Lockups"
1150	depends on HARDLOCKUP_DETECTOR
1151	help
1152	  Say Y here to enable the kernel to panic on "hard lockups",
1153	  which are bugs that cause the kernel to loop in kernel
1154	  mode with interrupts disabled for more than 10 seconds (configurable
1155	  using the watchdog_thresh sysctl).
1156
1157	  Say N if unsure.
1158
1159config DETECT_HUNG_TASK
1160	bool "Detect Hung Tasks"
1161	depends on DEBUG_KERNEL
1162	default SOFTLOCKUP_DETECTOR
1163	help
1164	  Say Y here to enable the kernel to detect "hung tasks",
1165	  which are bugs that cause the task to be stuck in
1166	  uninterruptible "D" state indefinitely.
1167
1168	  When a hung task is detected, the kernel will print the
1169	  current stack trace (which you should report), but the
1170	  task will stay in uninterruptible state. If lockdep is
1171	  enabled then all held locks will also be reported. This
1172	  feature has negligible overhead.
1173
1174config DEFAULT_HUNG_TASK_TIMEOUT
1175	int "Default timeout for hung task detection (in seconds)"
1176	depends on DETECT_HUNG_TASK
1177	default 120
1178	help
1179	  This option controls the default timeout (in seconds) used
1180	  to determine when a task has become non-responsive and should
1181	  be considered hung.
1182
1183	  It can be adjusted at runtime via the kernel.hung_task_timeout_secs
1184	  sysctl or by writing a value to
1185	  /proc/sys/kernel/hung_task_timeout_secs.
1186
1187	  A timeout of 0 disables the check.  The default is two minutes.
1188	  Keeping the default should be fine in most cases.
1189
1190config BOOTPARAM_HUNG_TASK_PANIC
1191	bool "Panic (Reboot) On Hung Tasks"
1192	depends on DETECT_HUNG_TASK
1193	help
1194	  Say Y here to enable the kernel to panic on "hung tasks",
1195	  which are bugs that cause the kernel to leave a task stuck
1196	  in uninterruptible "D" state.
1197
1198	  The panic can be used in combination with panic_timeout,
1199	  to cause the system to reboot automatically after a
1200	  hung task has been detected. This feature is useful for
1201	  high-availability systems that have uptime guarantees and
1202	  where a hung tasks must be resolved ASAP.
1203
1204	  Say N if unsure.
1205
1206config WQ_WATCHDOG
1207	bool "Detect Workqueue Stalls"
1208	depends on DEBUG_KERNEL
1209	help
1210	  Say Y here to enable stall detection on workqueues.  If a
1211	  worker pool doesn't make forward progress on a pending work
1212	  item for over a given amount of time, 30s by default, a
1213	  warning message is printed along with dump of workqueue
1214	  state.  This can be configured through kernel parameter
1215	  "workqueue.watchdog_thresh" and its sysfs counterpart.
1216
1217config WQ_CPU_INTENSIVE_REPORT
1218	bool "Report per-cpu work items which hog CPU for too long"
1219	depends on DEBUG_KERNEL
1220	help
1221	  Say Y here to enable reporting of concurrency-managed per-cpu work
1222	  items that hog CPUs for longer than
1223	  workqueue.cpu_intensive_thresh_us. Workqueue automatically
1224	  detects and excludes them from concurrency management to prevent
1225	  them from stalling other per-cpu work items. Occassional
1226	  triggering may not necessarily indicate a problem. Repeated
1227	  triggering likely indicates that the work item should be switched
1228	  to use an unbound workqueue.
1229
1230config TEST_LOCKUP
1231	tristate "Test module to generate lockups"
1232	depends on m
1233	help
1234	  This builds the "test_lockup" module that helps to make sure
1235	  that watchdogs and lockup detectors are working properly.
1236
1237	  Depending on module parameters it could emulate soft or hard
1238	  lockup, "hung task", or locking arbitrary lock for a long time.
1239	  Also it could generate series of lockups with cooling-down periods.
1240
1241	  If unsure, say N.
1242
1243endmenu # "Debug lockups and hangs"
1244
1245menu "Scheduler Debugging"
1246
1247config SCHED_DEBUG
1248	bool "Collect scheduler debugging info"
1249	depends on DEBUG_KERNEL && DEBUG_FS
1250	default y
1251	help
1252	  If you say Y here, the /sys/kernel/debug/sched file will be provided
1253	  that can help debug the scheduler. The runtime overhead of this
1254	  option is minimal.
1255
1256config SCHED_INFO
1257	bool
1258	default n
1259
1260config SCHEDSTATS
1261	bool "Collect scheduler statistics"
1262	depends on DEBUG_KERNEL && PROC_FS
1263	select SCHED_INFO
1264	help
1265	  If you say Y here, additional code will be inserted into the
1266	  scheduler and related routines to collect statistics about
1267	  scheduler behavior and provide them in /proc/schedstat.  These
1268	  stats may be useful for both tuning and debugging the scheduler
1269	  If you aren't debugging the scheduler or trying to tune a specific
1270	  application, you can say N to avoid the very slight overhead
1271	  this adds.
1272
1273endmenu
1274
1275config DEBUG_TIMEKEEPING
1276	bool "Enable extra timekeeping sanity checking"
1277	help
1278	  This option will enable additional timekeeping sanity checks
1279	  which may be helpful when diagnosing issues where timekeeping
1280	  problems are suspected.
1281
1282	  This may include checks in the timekeeping hotpaths, so this
1283	  option may have a (very small) performance impact to some
1284	  workloads.
1285
1286	  If unsure, say N.
1287
1288config DEBUG_PREEMPT
1289	bool "Debug preemptible kernel"
1290	depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT
1291	help
1292	  If you say Y here then the kernel will use a debug variant of the
1293	  commonly used smp_processor_id() function and will print warnings
1294	  if kernel code uses it in a preemption-unsafe way. Also, the kernel
1295	  will detect preemption count underflows.
1296
1297	  This option has potential to introduce high runtime overhead,
1298	  depending on workload as it triggers debugging routines for each
1299	  this_cpu operation. It should only be used for debugging purposes.
1300
1301menu "Lock Debugging (spinlocks, mutexes, etc...)"
1302
1303config LOCK_DEBUGGING_SUPPORT
1304	bool
1305	depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1306	default y
1307
1308config PROVE_LOCKING
1309	bool "Lock debugging: prove locking correctness"
1310	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1311	select LOCKDEP
1312	select DEBUG_SPINLOCK
1313	select DEBUG_MUTEXES if !PREEMPT_RT
1314	select DEBUG_RT_MUTEXES if RT_MUTEXES
1315	select DEBUG_RWSEMS
1316	select DEBUG_WW_MUTEX_SLOWPATH
1317	select DEBUG_LOCK_ALLOC
1318	select PREEMPT_COUNT if !ARCH_NO_PREEMPT
1319	select TRACE_IRQFLAGS
1320	default n
1321	help
1322	 This feature enables the kernel to prove that all locking
1323	 that occurs in the kernel runtime is mathematically
1324	 correct: that under no circumstance could an arbitrary (and
1325	 not yet triggered) combination of observed locking
1326	 sequences (on an arbitrary number of CPUs, running an
1327	 arbitrary number of tasks and interrupt contexts) cause a
1328	 deadlock.
1329
1330	 In short, this feature enables the kernel to report locking
1331	 related deadlocks before they actually occur.
1332
1333	 The proof does not depend on how hard and complex a
1334	 deadlock scenario would be to trigger: how many
1335	 participant CPUs, tasks and irq-contexts would be needed
1336	 for it to trigger. The proof also does not depend on
1337	 timing: if a race and a resulting deadlock is possible
1338	 theoretically (no matter how unlikely the race scenario
1339	 is), it will be proven so and will immediately be
1340	 reported by the kernel (once the event is observed that
1341	 makes the deadlock theoretically possible).
1342
1343	 If a deadlock is impossible (i.e. the locking rules, as
1344	 observed by the kernel, are mathematically correct), the
1345	 kernel reports nothing.
1346
1347	 NOTE: this feature can also be enabled for rwlocks, mutexes
1348	 and rwsems - in which case all dependencies between these
1349	 different locking variants are observed and mapped too, and
1350	 the proof of observed correctness is also maintained for an
1351	 arbitrary combination of these separate locking variants.
1352
1353	 For more details, see Documentation/locking/lockdep-design.rst.
1354
1355config PROVE_RAW_LOCK_NESTING
1356	bool "Enable raw_spinlock - spinlock nesting checks"
1357	depends on PROVE_LOCKING
1358	default n
1359	help
1360	 Enable the raw_spinlock vs. spinlock nesting checks which ensure
1361	 that the lock nesting rules for PREEMPT_RT enabled kernels are
1362	 not violated.
1363
1364	 NOTE: There are known nesting problems. So if you enable this
1365	 option expect lockdep splats until these problems have been fully
1366	 addressed which is work in progress. This config switch allows to
1367	 identify and analyze these problems. It will be removed and the
1368	 check permanently enabled once the main issues have been fixed.
1369
1370	 If unsure, select N.
1371
1372config LOCK_STAT
1373	bool "Lock usage statistics"
1374	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1375	select LOCKDEP
1376	select DEBUG_SPINLOCK
1377	select DEBUG_MUTEXES if !PREEMPT_RT
1378	select DEBUG_RT_MUTEXES if RT_MUTEXES
1379	select DEBUG_LOCK_ALLOC
1380	default n
1381	help
1382	 This feature enables tracking lock contention points
1383
1384	 For more details, see Documentation/locking/lockstat.rst
1385
1386	 This also enables lock events required by "perf lock",
1387	 subcommand of perf.
1388	 If you want to use "perf lock", you also need to turn on
1389	 CONFIG_EVENT_TRACING.
1390
1391	 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1392	 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1393
1394config DEBUG_RT_MUTEXES
1395	bool "RT Mutex debugging, deadlock detection"
1396	depends on DEBUG_KERNEL && RT_MUTEXES
1397	help
1398	 This allows rt mutex semantics violations and rt mutex related
1399	 deadlocks (lockups) to be detected and reported automatically.
1400
1401config DEBUG_SPINLOCK
1402	bool "Spinlock and rw-lock debugging: basic checks"
1403	depends on DEBUG_KERNEL
1404	select UNINLINE_SPIN_UNLOCK
1405	help
1406	  Say Y here and build SMP to catch missing spinlock initialization
1407	  and certain other kinds of spinlock errors commonly made.  This is
1408	  best used in conjunction with the NMI watchdog so that spinlock
1409	  deadlocks are also debuggable.
1410
1411config DEBUG_MUTEXES
1412	bool "Mutex debugging: basic checks"
1413	depends on DEBUG_KERNEL && !PREEMPT_RT
1414	help
1415	 This feature allows mutex semantics violations to be detected and
1416	 reported.
1417
1418config DEBUG_WW_MUTEX_SLOWPATH
1419	bool "Wait/wound mutex debugging: Slowpath testing"
1420	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1421	select DEBUG_LOCK_ALLOC
1422	select DEBUG_SPINLOCK
1423	select DEBUG_MUTEXES if !PREEMPT_RT
1424	select DEBUG_RT_MUTEXES if PREEMPT_RT
1425	help
1426	 This feature enables slowpath testing for w/w mutex users by
1427	 injecting additional -EDEADLK wound/backoff cases. Together with
1428	 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1429	 will test all possible w/w mutex interface abuse with the
1430	 exception of simply not acquiring all the required locks.
1431	 Note that this feature can introduce significant overhead, so
1432	 it really should not be enabled in a production or distro kernel,
1433	 even a debug kernel.  If you are a driver writer, enable it.  If
1434	 you are a distro, do not.
1435
1436config DEBUG_RWSEMS
1437	bool "RW Semaphore debugging: basic checks"
1438	depends on DEBUG_KERNEL
1439	help
1440	  This debugging feature allows mismatched rw semaphore locks
1441	  and unlocks to be detected and reported.
1442
1443config DEBUG_LOCK_ALLOC
1444	bool "Lock debugging: detect incorrect freeing of live locks"
1445	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1446	select DEBUG_SPINLOCK
1447	select DEBUG_MUTEXES if !PREEMPT_RT
1448	select DEBUG_RT_MUTEXES if RT_MUTEXES
1449	select LOCKDEP
1450	help
1451	 This feature will check whether any held lock (spinlock, rwlock,
1452	 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1453	 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1454	 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1455	 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1456	 held during task exit.
1457
1458config LOCKDEP
1459	bool
1460	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1461	select STACKTRACE
1462	select KALLSYMS
1463	select KALLSYMS_ALL
1464
1465config LOCKDEP_SMALL
1466	bool
1467
1468config LOCKDEP_BITS
1469	int "Bitsize for MAX_LOCKDEP_ENTRIES"
1470	depends on LOCKDEP && !LOCKDEP_SMALL
1471	range 10 30
1472	default 15
1473	help
1474	  Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message.
1475
1476config LOCKDEP_CHAINS_BITS
1477	int "Bitsize for MAX_LOCKDEP_CHAINS"
1478	depends on LOCKDEP && !LOCKDEP_SMALL
1479	range 10 30
1480	default 16
1481	help
1482	  Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message.
1483
1484config LOCKDEP_STACK_TRACE_BITS
1485	int "Bitsize for MAX_STACK_TRACE_ENTRIES"
1486	depends on LOCKDEP && !LOCKDEP_SMALL
1487	range 10 30
1488	default 19
1489	help
1490	  Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message.
1491
1492config LOCKDEP_STACK_TRACE_HASH_BITS
1493	int "Bitsize for STACK_TRACE_HASH_SIZE"
1494	depends on LOCKDEP && !LOCKDEP_SMALL
1495	range 10 30
1496	default 14
1497	help
1498	  Try increasing this value if you need large STACK_TRACE_HASH_SIZE.
1499
1500config LOCKDEP_CIRCULAR_QUEUE_BITS
1501	int "Bitsize for elements in circular_queue struct"
1502	depends on LOCKDEP
1503	range 10 30
1504	default 12
1505	help
1506	  Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure.
1507
1508config DEBUG_LOCKDEP
1509	bool "Lock dependency engine debugging"
1510	depends on DEBUG_KERNEL && LOCKDEP
1511	select DEBUG_IRQFLAGS
1512	help
1513	  If you say Y here, the lock dependency engine will do
1514	  additional runtime checks to debug itself, at the price
1515	  of more runtime overhead.
1516
1517config DEBUG_ATOMIC_SLEEP
1518	bool "Sleep inside atomic section checking"
1519	select PREEMPT_COUNT
1520	depends on DEBUG_KERNEL
1521	depends on !ARCH_NO_PREEMPT
1522	help
1523	  If you say Y here, various routines which may sleep will become very
1524	  noisy if they are called inside atomic sections: when a spinlock is
1525	  held, inside an rcu read side critical section, inside preempt disabled
1526	  sections, inside an interrupt, etc...
1527
1528config DEBUG_LOCKING_API_SELFTESTS
1529	bool "Locking API boot-time self-tests"
1530	depends on DEBUG_KERNEL
1531	help
1532	  Say Y here if you want the kernel to run a short self-test during
1533	  bootup. The self-test checks whether common types of locking bugs
1534	  are detected by debugging mechanisms or not. (if you disable
1535	  lock debugging then those bugs won't be detected of course.)
1536	  The following locking APIs are covered: spinlocks, rwlocks,
1537	  mutexes and rwsems.
1538
1539config LOCK_TORTURE_TEST
1540	tristate "torture tests for locking"
1541	depends on DEBUG_KERNEL
1542	select TORTURE_TEST
1543	help
1544	  This option provides a kernel module that runs torture tests
1545	  on kernel locking primitives.  The kernel module may be built
1546	  after the fact on the running kernel to be tested, if desired.
1547
1548	  Say Y here if you want kernel locking-primitive torture tests
1549	  to be built into the kernel.
1550	  Say M if you want these torture tests to build as a module.
1551	  Say N if you are unsure.
1552
1553config WW_MUTEX_SELFTEST
1554	tristate "Wait/wound mutex selftests"
1555	help
1556	  This option provides a kernel module that runs tests on the
1557	  on the struct ww_mutex locking API.
1558
1559	  It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1560	  with this test harness.
1561
1562	  Say M if you want these self tests to build as a module.
1563	  Say N if you are unsure.
1564
1565config SCF_TORTURE_TEST
1566	tristate "torture tests for smp_call_function*()"
1567	depends on DEBUG_KERNEL
1568	select TORTURE_TEST
1569	help
1570	  This option provides a kernel module that runs torture tests
1571	  on the smp_call_function() family of primitives.  The kernel
1572	  module may be built after the fact on the running kernel to
1573	  be tested, if desired.
1574
1575config CSD_LOCK_WAIT_DEBUG
1576	bool "Debugging for csd_lock_wait(), called from smp_call_function*()"
1577	depends on DEBUG_KERNEL
1578	depends on 64BIT
1579	default n
1580	help
1581	  This option enables debug prints when CPUs are slow to respond
1582	  to the smp_call_function*() IPI wrappers.  These debug prints
1583	  include the IPI handler function currently executing (if any)
1584	  and relevant stack traces.
1585
1586config CSD_LOCK_WAIT_DEBUG_DEFAULT
1587	bool "Default csd_lock_wait() debugging on at boot time"
1588	depends on CSD_LOCK_WAIT_DEBUG
1589	depends on 64BIT
1590	default n
1591	help
1592	  This option causes the csdlock_debug= kernel boot parameter to
1593	  default to 1 (basic debugging) instead of 0 (no debugging).
1594
1595endmenu # lock debugging
1596
1597config TRACE_IRQFLAGS
1598	depends on TRACE_IRQFLAGS_SUPPORT
1599	bool
1600	help
1601	  Enables hooks to interrupt enabling and disabling for
1602	  either tracing or lock debugging.
1603
1604config TRACE_IRQFLAGS_NMI
1605	def_bool y
1606	depends on TRACE_IRQFLAGS
1607	depends on TRACE_IRQFLAGS_NMI_SUPPORT
1608
1609config NMI_CHECK_CPU
1610	bool "Debugging for CPUs failing to respond to backtrace requests"
1611	depends on DEBUG_KERNEL
1612	depends on X86
1613	default n
1614	help
1615	  Enables debug prints when a CPU fails to respond to a given
1616	  backtrace NMI.  These prints provide some reasons why a CPU
1617	  might legitimately be failing to respond, for example, if it
1618	  is offline of if ignore_nmis is set.
1619
1620config DEBUG_IRQFLAGS
1621	bool "Debug IRQ flag manipulation"
1622	help
1623	  Enables checks for potentially unsafe enabling or disabling of
1624	  interrupts, such as calling raw_local_irq_restore() when interrupts
1625	  are enabled.
1626
1627config STACKTRACE
1628	bool "Stack backtrace support"
1629	depends on STACKTRACE_SUPPORT
1630	help
1631	  This option causes the kernel to create a /proc/pid/stack for
1632	  every process, showing its current stack trace.
1633	  It is also used by various kernel debugging features that require
1634	  stack trace generation.
1635
1636config WARN_ALL_UNSEEDED_RANDOM
1637	bool "Warn for all uses of unseeded randomness"
1638	default n
1639	help
1640	  Some parts of the kernel contain bugs relating to their use of
1641	  cryptographically secure random numbers before it's actually possible
1642	  to generate those numbers securely. This setting ensures that these
1643	  flaws don't go unnoticed, by enabling a message, should this ever
1644	  occur. This will allow people with obscure setups to know when things
1645	  are going wrong, so that they might contact developers about fixing
1646	  it.
1647
1648	  Unfortunately, on some models of some architectures getting
1649	  a fully seeded CRNG is extremely difficult, and so this can
1650	  result in dmesg getting spammed for a surprisingly long
1651	  time.  This is really bad from a security perspective, and
1652	  so architecture maintainers really need to do what they can
1653	  to get the CRNG seeded sooner after the system is booted.
1654	  However, since users cannot do anything actionable to
1655	  address this, by default this option is disabled.
1656
1657	  Say Y here if you want to receive warnings for all uses of
1658	  unseeded randomness.  This will be of use primarily for
1659	  those developers interested in improving the security of
1660	  Linux kernels running on their architecture (or
1661	  subarchitecture).
1662
1663config DEBUG_KOBJECT
1664	bool "kobject debugging"
1665	depends on DEBUG_KERNEL
1666	help
1667	  If you say Y here, some extra kobject debugging messages will be sent
1668	  to the syslog.
1669
1670config DEBUG_KOBJECT_RELEASE
1671	bool "kobject release debugging"
1672	depends on DEBUG_OBJECTS_TIMERS
1673	help
1674	  kobjects are reference counted objects.  This means that their
1675	  last reference count put is not predictable, and the kobject can
1676	  live on past the point at which a driver decides to drop its
1677	  initial reference to the kobject gained on allocation.  An
1678	  example of this would be a struct device which has just been
1679	  unregistered.
1680
1681	  However, some buggy drivers assume that after such an operation,
1682	  the memory backing the kobject can be immediately freed.  This
1683	  goes completely against the principles of a refcounted object.
1684
1685	  If you say Y here, the kernel will delay the release of kobjects
1686	  on the last reference count to improve the visibility of this
1687	  kind of kobject release bug.
1688
1689config HAVE_DEBUG_BUGVERBOSE
1690	bool
1691
1692menu "Debug kernel data structures"
1693
1694config DEBUG_LIST
1695	bool "Debug linked list manipulation"
1696	depends on DEBUG_KERNEL
1697	select LIST_HARDENED
1698	help
1699	  Enable this to turn on extended checks in the linked-list walking
1700	  routines.
1701
1702	  This option trades better quality error reports for performance, and
1703	  is more suitable for kernel debugging. If you care about performance,
1704	  you should only enable CONFIG_LIST_HARDENED instead.
1705
1706	  If unsure, say N.
1707
1708config DEBUG_PLIST
1709	bool "Debug priority linked list manipulation"
1710	depends on DEBUG_KERNEL
1711	help
1712	  Enable this to turn on extended checks in the priority-ordered
1713	  linked-list (plist) walking routines.  This checks the entire
1714	  list multiple times during each manipulation.
1715
1716	  If unsure, say N.
1717
1718config DEBUG_SG
1719	bool "Debug SG table operations"
1720	depends on DEBUG_KERNEL
1721	help
1722	  Enable this to turn on checks on scatter-gather tables. This can
1723	  help find problems with drivers that do not properly initialize
1724	  their sg tables.
1725
1726	  If unsure, say N.
1727
1728config DEBUG_NOTIFIERS
1729	bool "Debug notifier call chains"
1730	depends on DEBUG_KERNEL
1731	help
1732	  Enable this to turn on sanity checking for notifier call chains.
1733	  This is most useful for kernel developers to make sure that
1734	  modules properly unregister themselves from notifier chains.
1735	  This is a relatively cheap check but if you care about maximum
1736	  performance, say N.
1737
1738config DEBUG_MAPLE_TREE
1739	bool "Debug maple trees"
1740	depends on DEBUG_KERNEL
1741	help
1742	  Enable maple tree debugging information and extra validations.
1743
1744	  If unsure, say N.
1745
1746endmenu
1747
1748source "kernel/rcu/Kconfig.debug"
1749
1750config DEBUG_WQ_FORCE_RR_CPU
1751	bool "Force round-robin CPU selection for unbound work items"
1752	depends on DEBUG_KERNEL
1753	default n
1754	help
1755	  Workqueue used to implicitly guarantee that work items queued
1756	  without explicit CPU specified are put on the local CPU.  This
1757	  guarantee is no longer true and while local CPU is still
1758	  preferred work items may be put on foreign CPUs.  Kernel
1759	  parameter "workqueue.debug_force_rr_cpu" is added to force
1760	  round-robin CPU selection to flush out usages which depend on the
1761	  now broken guarantee.  This config option enables the debug
1762	  feature by default.  When enabled, memory and cache locality will
1763	  be impacted.
1764
1765config CPU_HOTPLUG_STATE_CONTROL
1766	bool "Enable CPU hotplug state control"
1767	depends on DEBUG_KERNEL
1768	depends on HOTPLUG_CPU
1769	default n
1770	help
1771	  Allows to write steps between "offline" and "online" to the CPUs
1772	  sysfs target file so states can be stepped granular. This is a debug
1773	  option for now as the hotplug machinery cannot be stopped and
1774	  restarted at arbitrary points yet.
1775
1776	  Say N if your are unsure.
1777
1778config LATENCYTOP
1779	bool "Latency measuring infrastructure"
1780	depends on DEBUG_KERNEL
1781	depends on STACKTRACE_SUPPORT
1782	depends on PROC_FS
1783	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
1784	select KALLSYMS
1785	select KALLSYMS_ALL
1786	select STACKTRACE
1787	select SCHEDSTATS
1788	help
1789	  Enable this option if you want to use the LatencyTOP tool
1790	  to find out which userspace is blocking on what kernel operations.
1791
1792config DEBUG_CGROUP_REF
1793	bool "Disable inlining of cgroup css reference count functions"
1794	depends on DEBUG_KERNEL
1795	depends on CGROUPS
1796	depends on KPROBES
1797	default n
1798	help
1799	  Force cgroup css reference count functions to not be inlined so
1800	  that they can be kprobed for debugging.
1801
1802source "kernel/trace/Kconfig"
1803
1804config PROVIDE_OHCI1394_DMA_INIT
1805	bool "Remote debugging over FireWire early on boot"
1806	depends on PCI && X86
1807	help
1808	  If you want to debug problems which hang or crash the kernel early
1809	  on boot and the crashing machine has a FireWire port, you can use
1810	  this feature to remotely access the memory of the crashed machine
1811	  over FireWire. This employs remote DMA as part of the OHCI1394
1812	  specification which is now the standard for FireWire controllers.
1813
1814	  With remote DMA, you can monitor the printk buffer remotely using
1815	  firescope and access all memory below 4GB using fireproxy from gdb.
1816	  Even controlling a kernel debugger is possible using remote DMA.
1817
1818	  Usage:
1819
1820	  If ohci1394_dma=early is used as boot parameter, it will initialize
1821	  all OHCI1394 controllers which are found in the PCI config space.
1822
1823	  As all changes to the FireWire bus such as enabling and disabling
1824	  devices cause a bus reset and thereby disable remote DMA for all
1825	  devices, be sure to have the cable plugged and FireWire enabled on
1826	  the debugging host before booting the debug target for debugging.
1827
1828	  This code (~1k) is freed after boot. By then, the firewire stack
1829	  in charge of the OHCI-1394 controllers should be used instead.
1830
1831	  See Documentation/core-api/debugging-via-ohci1394.rst for more information.
1832
1833source "samples/Kconfig"
1834
1835config ARCH_HAS_DEVMEM_IS_ALLOWED
1836	bool
1837
1838config STRICT_DEVMEM
1839	bool "Filter access to /dev/mem"
1840	depends on MMU && DEVMEM
1841	depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED
1842	default y if PPC || X86 || ARM64
1843	help
1844	  If this option is disabled, you allow userspace (root) access to all
1845	  of memory, including kernel and userspace memory. Accidental
1846	  access to this is obviously disastrous, but specific access can
1847	  be used by people debugging the kernel. Note that with PAT support
1848	  enabled, even in this case there are restrictions on /dev/mem
1849	  use due to the cache aliasing requirements.
1850
1851	  If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
1852	  file only allows userspace access to PCI space and the BIOS code and
1853	  data regions.  This is sufficient for dosemu and X and all common
1854	  users of /dev/mem.
1855
1856	  If in doubt, say Y.
1857
1858config IO_STRICT_DEVMEM
1859	bool "Filter I/O access to /dev/mem"
1860	depends on STRICT_DEVMEM
1861	help
1862	  If this option is disabled, you allow userspace (root) access to all
1863	  io-memory regardless of whether a driver is actively using that
1864	  range.  Accidental access to this is obviously disastrous, but
1865	  specific access can be used by people debugging kernel drivers.
1866
1867	  If this option is switched on, the /dev/mem file only allows
1868	  userspace access to *idle* io-memory ranges (see /proc/iomem) This
1869	  may break traditional users of /dev/mem (dosemu, legacy X, etc...)
1870	  if the driver using a given range cannot be disabled.
1871
1872	  If in doubt, say Y.
1873
1874menu "$(SRCARCH) Debugging"
1875
1876source "arch/$(SRCARCH)/Kconfig.debug"
1877
1878endmenu
1879
1880menu "Kernel Testing and Coverage"
1881
1882source "lib/kunit/Kconfig"
1883
1884config NOTIFIER_ERROR_INJECTION
1885	tristate "Notifier error injection"
1886	depends on DEBUG_KERNEL
1887	select DEBUG_FS
1888	help
1889	  This option provides the ability to inject artificial errors to
1890	  specified notifier chain callbacks. It is useful to test the error
1891	  handling of notifier call chain failures.
1892
1893	  Say N if unsure.
1894
1895config PM_NOTIFIER_ERROR_INJECT
1896	tristate "PM notifier error injection module"
1897	depends on PM && NOTIFIER_ERROR_INJECTION
1898	default m if PM_DEBUG
1899	help
1900	  This option provides the ability to inject artificial errors to
1901	  PM notifier chain callbacks.  It is controlled through debugfs
1902	  interface /sys/kernel/debug/notifier-error-inject/pm
1903
1904	  If the notifier call chain should be failed with some events
1905	  notified, write the error code to "actions/<notifier event>/error".
1906
1907	  Example: Inject PM suspend error (-12 = -ENOMEM)
1908
1909	  # cd /sys/kernel/debug/notifier-error-inject/pm/
1910	  # echo -12 > actions/PM_SUSPEND_PREPARE/error
1911	  # echo mem > /sys/power/state
1912	  bash: echo: write error: Cannot allocate memory
1913
1914	  To compile this code as a module, choose M here: the module will
1915	  be called pm-notifier-error-inject.
1916
1917	  If unsure, say N.
1918
1919config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1920	tristate "OF reconfig notifier error injection module"
1921	depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1922	help
1923	  This option provides the ability to inject artificial errors to
1924	  OF reconfig notifier chain callbacks.  It is controlled
1925	  through debugfs interface under
1926	  /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1927
1928	  If the notifier call chain should be failed with some events
1929	  notified, write the error code to "actions/<notifier event>/error".
1930
1931	  To compile this code as a module, choose M here: the module will
1932	  be called of-reconfig-notifier-error-inject.
1933
1934	  If unsure, say N.
1935
1936config NETDEV_NOTIFIER_ERROR_INJECT
1937	tristate "Netdev notifier error injection module"
1938	depends on NET && NOTIFIER_ERROR_INJECTION
1939	help
1940	  This option provides the ability to inject artificial errors to
1941	  netdevice notifier chain callbacks.  It is controlled through debugfs
1942	  interface /sys/kernel/debug/notifier-error-inject/netdev
1943
1944	  If the notifier call chain should be failed with some events
1945	  notified, write the error code to "actions/<notifier event>/error".
1946
1947	  Example: Inject netdevice mtu change error (-22 = -EINVAL)
1948
1949	  # cd /sys/kernel/debug/notifier-error-inject/netdev
1950	  # echo -22 > actions/NETDEV_CHANGEMTU/error
1951	  # ip link set eth0 mtu 1024
1952	  RTNETLINK answers: Invalid argument
1953
1954	  To compile this code as a module, choose M here: the module will
1955	  be called netdev-notifier-error-inject.
1956
1957	  If unsure, say N.
1958
1959config FUNCTION_ERROR_INJECTION
1960	bool "Fault-injections of functions"
1961	depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
1962	help
1963	  Add fault injections into various functions that are annotated with
1964	  ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return
1965	  value of these functions. This is useful to test error paths of code.
1966
1967	  If unsure, say N
1968
1969config FAULT_INJECTION
1970	bool "Fault-injection framework"
1971	depends on DEBUG_KERNEL
1972	help
1973	  Provide fault-injection framework.
1974	  For more details, see Documentation/fault-injection/.
1975
1976config FAILSLAB
1977	bool "Fault-injection capability for kmalloc"
1978	depends on FAULT_INJECTION
1979	depends on SLAB || SLUB
1980	help
1981	  Provide fault-injection capability for kmalloc.
1982
1983config FAIL_PAGE_ALLOC
1984	bool "Fault-injection capability for alloc_pages()"
1985	depends on FAULT_INJECTION
1986	help
1987	  Provide fault-injection capability for alloc_pages().
1988
1989config FAULT_INJECTION_USERCOPY
1990	bool "Fault injection capability for usercopy functions"
1991	depends on FAULT_INJECTION
1992	help
1993	  Provides fault-injection capability to inject failures
1994	  in usercopy functions (copy_from_user(), get_user(), ...).
1995
1996config FAIL_MAKE_REQUEST
1997	bool "Fault-injection capability for disk IO"
1998	depends on FAULT_INJECTION && BLOCK
1999	help
2000	  Provide fault-injection capability for disk IO.
2001
2002config FAIL_IO_TIMEOUT
2003	bool "Fault-injection capability for faking disk interrupts"
2004	depends on FAULT_INJECTION && BLOCK
2005	help
2006	  Provide fault-injection capability on end IO handling. This
2007	  will make the block layer "forget" an interrupt as configured,
2008	  thus exercising the error handling.
2009
2010	  Only works with drivers that use the generic timeout handling,
2011	  for others it won't do anything.
2012
2013config FAIL_FUTEX
2014	bool "Fault-injection capability for futexes"
2015	select DEBUG_FS
2016	depends on FAULT_INJECTION && FUTEX
2017	help
2018	  Provide fault-injection capability for futexes.
2019
2020config FAULT_INJECTION_DEBUG_FS
2021	bool "Debugfs entries for fault-injection capabilities"
2022	depends on FAULT_INJECTION && SYSFS && DEBUG_FS
2023	help
2024	  Enable configuration of fault-injection capabilities via debugfs.
2025
2026config FAIL_FUNCTION
2027	bool "Fault-injection capability for functions"
2028	depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
2029	help
2030	  Provide function-based fault-injection capability.
2031	  This will allow you to override a specific function with a return
2032	  with given return value. As a result, function caller will see
2033	  an error value and have to handle it. This is useful to test the
2034	  error handling in various subsystems.
2035
2036config FAIL_MMC_REQUEST
2037	bool "Fault-injection capability for MMC IO"
2038	depends on FAULT_INJECTION_DEBUG_FS && MMC
2039	help
2040	  Provide fault-injection capability for MMC IO.
2041	  This will make the mmc core return data errors. This is
2042	  useful to test the error handling in the mmc block device
2043	  and to test how the mmc host driver handles retries from
2044	  the block device.
2045
2046config FAIL_SUNRPC
2047	bool "Fault-injection capability for SunRPC"
2048	depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG
2049	help
2050	  Provide fault-injection capability for SunRPC and
2051	  its consumers.
2052
2053config FAULT_INJECTION_CONFIGFS
2054	bool "Configfs interface for fault-injection capabilities"
2055	depends on FAULT_INJECTION
2056	select CONFIGFS_FS
2057	help
2058	  This option allows configfs-based drivers to dynamically configure
2059	  fault-injection via configfs.  Each parameter for driver-specific
2060	  fault-injection can be made visible as a configfs attribute in a
2061	  configfs group.
2062
2063
2064config FAULT_INJECTION_STACKTRACE_FILTER
2065	bool "stacktrace filter for fault-injection capabilities"
2066	depends on FAULT_INJECTION
2067	depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT
2068	select STACKTRACE
2069	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
2070	help
2071	  Provide stacktrace filter for fault-injection capabilities
2072
2073config ARCH_HAS_KCOV
2074	bool
2075	help
2076	  An architecture should select this when it can successfully
2077	  build and run with CONFIG_KCOV. This typically requires
2078	  disabling instrumentation for some early boot code.
2079
2080config CC_HAS_SANCOV_TRACE_PC
2081	def_bool $(cc-option,-fsanitize-coverage=trace-pc)
2082
2083
2084config KCOV
2085	bool "Code coverage for fuzzing"
2086	depends on ARCH_HAS_KCOV
2087	depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
2088	depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \
2089		   GCC_VERSION >= 120000 || CLANG_VERSION >= 130000
2090	select DEBUG_FS
2091	select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
2092	select OBJTOOL if HAVE_NOINSTR_HACK
2093	help
2094	  KCOV exposes kernel code coverage information in a form suitable
2095	  for coverage-guided fuzzing (randomized testing).
2096
2097	  If RANDOMIZE_BASE is enabled, PC values will not be stable across
2098	  different machines and across reboots. If you need stable PC values,
2099	  disable RANDOMIZE_BASE.
2100
2101	  For more details, see Documentation/dev-tools/kcov.rst.
2102
2103config KCOV_ENABLE_COMPARISONS
2104	bool "Enable comparison operands collection by KCOV"
2105	depends on KCOV
2106	depends on $(cc-option,-fsanitize-coverage=trace-cmp)
2107	help
2108	  KCOV also exposes operands of every comparison in the instrumented
2109	  code along with operand sizes and PCs of the comparison instructions.
2110	  These operands can be used by fuzzing engines to improve the quality
2111	  of fuzzing coverage.
2112
2113config KCOV_INSTRUMENT_ALL
2114	bool "Instrument all code by default"
2115	depends on KCOV
2116	default y
2117	help
2118	  If you are doing generic system call fuzzing (like e.g. syzkaller),
2119	  then you will want to instrument the whole kernel and you should
2120	  say y here. If you are doing more targeted fuzzing (like e.g.
2121	  filesystem fuzzing with AFL) then you will want to enable coverage
2122	  for more specific subsets of files, and should say n here.
2123
2124config KCOV_IRQ_AREA_SIZE
2125	hex "Size of interrupt coverage collection area in words"
2126	depends on KCOV
2127	default 0x40000
2128	help
2129	  KCOV uses preallocated per-cpu areas to collect coverage from
2130	  soft interrupts. This specifies the size of those areas in the
2131	  number of unsigned long words.
2132
2133menuconfig RUNTIME_TESTING_MENU
2134	bool "Runtime Testing"
2135	def_bool y
2136
2137if RUNTIME_TESTING_MENU
2138
2139config TEST_DHRY
2140	tristate "Dhrystone benchmark test"
2141	help
2142	  Enable this to include the Dhrystone 2.1 benchmark.  This test
2143	  calculates the number of Dhrystones per second, and the number of
2144	  DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided
2145	  by 1757 (the number of Dhrystones per second obtained on the VAX
2146	  11/780, nominally a 1 MIPS machine).
2147
2148	  To run the benchmark, it needs to be enabled explicitly, either from
2149	  the kernel command line (when built-in), or from userspace (when
2150	  built-in or modular.
2151
2152	  Run once during kernel boot:
2153
2154	      test_dhry.run
2155
2156	  Set number of iterations from kernel command line:
2157
2158	      test_dhry.iterations=<n>
2159
2160	  Set number of iterations from userspace:
2161
2162	      echo <n> > /sys/module/test_dhry/parameters/iterations
2163
2164	  Trigger manual run from userspace:
2165
2166	      echo y > /sys/module/test_dhry/parameters/run
2167
2168	  If the number of iterations is <= 0, the test will devise a suitable
2169	  number of iterations (test runs for at least 2s) automatically.
2170	  This process takes ca. 4s.
2171
2172	  If unsure, say N.
2173
2174config LKDTM
2175	tristate "Linux Kernel Dump Test Tool Module"
2176	depends on DEBUG_FS
2177	help
2178	This module enables testing of the different dumping mechanisms by
2179	inducing system failures at predefined crash points.
2180	If you don't need it: say N
2181	Choose M here to compile this code as a module. The module will be
2182	called lkdtm.
2183
2184	Documentation on how to use the module can be found in
2185	Documentation/fault-injection/provoke-crashes.rst
2186
2187config CPUMASK_KUNIT_TEST
2188	tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS
2189	depends on KUNIT
2190	default KUNIT_ALL_TESTS
2191	help
2192	  Enable to turn on cpumask tests, running at boot or module load time.
2193
2194	  For more information on KUnit and unit tests in general, please refer
2195	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2196
2197	  If unsure, say N.
2198
2199config TEST_LIST_SORT
2200	tristate "Linked list sorting test" if !KUNIT_ALL_TESTS
2201	depends on KUNIT
2202	default KUNIT_ALL_TESTS
2203	help
2204	  Enable this to turn on 'list_sort()' function test. This test is
2205	  executed only once during system boot (so affects only boot time),
2206	  or at module load time.
2207
2208	  If unsure, say N.
2209
2210config TEST_MIN_HEAP
2211	tristate "Min heap test"
2212	depends on DEBUG_KERNEL || m
2213	help
2214	  Enable this to turn on min heap function tests. This test is
2215	  executed only once during system boot (so affects only boot time),
2216	  or at module load time.
2217
2218	  If unsure, say N.
2219
2220config TEST_SORT
2221	tristate "Array-based sort test" if !KUNIT_ALL_TESTS
2222	depends on KUNIT
2223	default KUNIT_ALL_TESTS
2224	help
2225	  This option enables the self-test function of 'sort()' at boot,
2226	  or at module load time.
2227
2228	  If unsure, say N.
2229
2230config TEST_DIV64
2231	tristate "64bit/32bit division and modulo test"
2232	depends on DEBUG_KERNEL || m
2233	help
2234	  Enable this to turn on 'do_div()' function test. This test is
2235	  executed only once during system boot (so affects only boot time),
2236	  or at module load time.
2237
2238	  If unsure, say N.
2239
2240config TEST_IOV_ITER
2241	tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS
2242	depends on KUNIT
2243	depends on MMU
2244	default KUNIT_ALL_TESTS
2245	help
2246	  Enable this to turn on testing of the operation of the I/O iterator
2247	  (iov_iter). This test is executed only once during system boot (so
2248	  affects only boot time), or at module load time.
2249
2250	  If unsure, say N.
2251
2252config KPROBES_SANITY_TEST
2253	tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS
2254	depends on DEBUG_KERNEL
2255	depends on KPROBES
2256	depends on KUNIT
2257	select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
2258	default KUNIT_ALL_TESTS
2259	help
2260	  This option provides for testing basic kprobes functionality on
2261	  boot. Samples of kprobe and kretprobe are inserted and
2262	  verified for functionality.
2263
2264	  Say N if you are unsure.
2265
2266config FPROBE_SANITY_TEST
2267	bool "Self test for fprobe"
2268	depends on DEBUG_KERNEL
2269	depends on FPROBE
2270	depends on KUNIT=y
2271	help
2272	  This option will enable testing the fprobe when the system boot.
2273	  A series of tests are made to verify that the fprobe is functioning
2274	  properly.
2275
2276	  Say N if you are unsure.
2277
2278config BACKTRACE_SELF_TEST
2279	tristate "Self test for the backtrace code"
2280	depends on DEBUG_KERNEL
2281	help
2282	  This option provides a kernel module that can be used to test
2283	  the kernel stack backtrace code. This option is not useful
2284	  for distributions or general kernels, but only for kernel
2285	  developers working on architecture code.
2286
2287	  Note that if you want to also test saved backtraces, you will
2288	  have to enable STACKTRACE as well.
2289
2290	  Say N if you are unsure.
2291
2292config TEST_REF_TRACKER
2293	tristate "Self test for reference tracker"
2294	depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
2295	select REF_TRACKER
2296	help
2297	  This option provides a kernel module performing tests
2298	  using reference tracker infrastructure.
2299
2300	  Say N if you are unsure.
2301
2302config RBTREE_TEST
2303	tristate "Red-Black tree test"
2304	depends on DEBUG_KERNEL
2305	help
2306	  A benchmark measuring the performance of the rbtree library.
2307	  Also includes rbtree invariant checks.
2308
2309config REED_SOLOMON_TEST
2310	tristate "Reed-Solomon library test"
2311	depends on DEBUG_KERNEL || m
2312	select REED_SOLOMON
2313	select REED_SOLOMON_ENC16
2314	select REED_SOLOMON_DEC16
2315	help
2316	  This option enables the self-test function of rslib at boot,
2317	  or at module load time.
2318
2319	  If unsure, say N.
2320
2321config INTERVAL_TREE_TEST
2322	tristate "Interval tree test"
2323	depends on DEBUG_KERNEL
2324	select INTERVAL_TREE
2325	help
2326	  A benchmark measuring the performance of the interval tree library
2327
2328config PERCPU_TEST
2329	tristate "Per cpu operations test"
2330	depends on m && DEBUG_KERNEL
2331	help
2332	  Enable this option to build test module which validates per-cpu
2333	  operations.
2334
2335	  If unsure, say N.
2336
2337config ATOMIC64_SELFTEST
2338	tristate "Perform an atomic64_t self-test"
2339	help
2340	  Enable this option to test the atomic64_t functions at boot or
2341	  at module load time.
2342
2343	  If unsure, say N.
2344
2345config ASYNC_RAID6_TEST
2346	tristate "Self test for hardware accelerated raid6 recovery"
2347	depends on ASYNC_RAID6_RECOV
2348	select ASYNC_MEMCPY
2349	help
2350	  This is a one-shot self test that permutes through the
2351	  recovery of all the possible two disk failure scenarios for a
2352	  N-disk array.  Recovery is performed with the asynchronous
2353	  raid6 recovery routines, and will optionally use an offload
2354	  engine if one is available.
2355
2356	  If unsure, say N.
2357
2358config TEST_HEXDUMP
2359	tristate "Test functions located in the hexdump module at runtime"
2360
2361config STRING_SELFTEST
2362	tristate "Test string functions at runtime"
2363
2364config TEST_STRING_HELPERS
2365	tristate "Test functions located in the string_helpers module at runtime"
2366
2367config TEST_KSTRTOX
2368	tristate "Test kstrto*() family of functions at runtime"
2369
2370config TEST_PRINTF
2371	tristate "Test printf() family of functions at runtime"
2372
2373config TEST_SCANF
2374	tristate "Test scanf() family of functions at runtime"
2375
2376config TEST_BITMAP
2377	tristate "Test bitmap_*() family of functions at runtime"
2378	help
2379	  Enable this option to test the bitmap functions at boot.
2380
2381	  If unsure, say N.
2382
2383config TEST_UUID
2384	tristate "Test functions located in the uuid module at runtime"
2385
2386config TEST_XARRAY
2387	tristate "Test the XArray code at runtime"
2388
2389config TEST_MAPLE_TREE
2390	tristate "Test the Maple Tree code at runtime or module load"
2391	help
2392	  Enable this option to test the maple tree code functions at boot, or
2393	  when the module is loaded. Enable "Debug Maple Trees" will enable
2394	  more verbose output on failures.
2395
2396	  If unsure, say N.
2397
2398config TEST_RHASHTABLE
2399	tristate "Perform selftest on resizable hash table"
2400	help
2401	  Enable this option to test the rhashtable functions at boot.
2402
2403	  If unsure, say N.
2404
2405config TEST_IDA
2406	tristate "Perform selftest on IDA functions"
2407
2408config TEST_PARMAN
2409	tristate "Perform selftest on priority array manager"
2410	depends on PARMAN
2411	help
2412	  Enable this option to test priority array manager on boot
2413	  (or module load).
2414
2415	  If unsure, say N.
2416
2417config TEST_IRQ_TIMINGS
2418	bool "IRQ timings selftest"
2419	depends on IRQ_TIMINGS
2420	help
2421	  Enable this option to test the irq timings code on boot.
2422
2423	  If unsure, say N.
2424
2425config TEST_LKM
2426	tristate "Test module loading with 'hello world' module"
2427	depends on m
2428	help
2429	  This builds the "test_module" module that emits "Hello, world"
2430	  on printk when loaded. It is designed to be used for basic
2431	  evaluation of the module loading subsystem (for example when
2432	  validating module verification). It lacks any extra dependencies,
2433	  and will not normally be loaded by the system unless explicitly
2434	  requested by name.
2435
2436	  If unsure, say N.
2437
2438config TEST_BITOPS
2439	tristate "Test module for compilation of bitops operations"
2440	depends on m
2441	help
2442	  This builds the "test_bitops" module that is much like the
2443	  TEST_LKM module except that it does a basic exercise of the
2444	  set/clear_bit macros and get_count_order/long to make sure there are
2445	  no compiler warnings from C=1 sparse checker or -Wextra
2446	  compilations. It has no dependencies and doesn't run or load unless
2447	  explicitly requested by name.  for example: modprobe test_bitops.
2448
2449	  If unsure, say N.
2450
2451config TEST_VMALLOC
2452	tristate "Test module for stress/performance analysis of vmalloc allocator"
2453	default n
2454       depends on MMU
2455	depends on m
2456	help
2457	  This builds the "test_vmalloc" module that should be used for
2458	  stress and performance analysis. So, any new change for vmalloc
2459	  subsystem can be evaluated from performance and stability point
2460	  of view.
2461
2462	  If unsure, say N.
2463
2464config TEST_USER_COPY
2465	tristate "Test user/kernel boundary protections"
2466	depends on m
2467	help
2468	  This builds the "test_user_copy" module that runs sanity checks
2469	  on the copy_to/from_user infrastructure, making sure basic
2470	  user/kernel boundary testing is working. If it fails to load,
2471	  a regression has been detected in the user/kernel memory boundary
2472	  protections.
2473
2474	  If unsure, say N.
2475
2476config TEST_BPF
2477	tristate "Test BPF filter functionality"
2478	depends on m && NET
2479	help
2480	  This builds the "test_bpf" module that runs various test vectors
2481	  against the BPF interpreter or BPF JIT compiler depending on the
2482	  current setting. This is in particular useful for BPF JIT compiler
2483	  development, but also to run regression tests against changes in
2484	  the interpreter code. It also enables test stubs for eBPF maps and
2485	  verifier used by user space verifier testsuite.
2486
2487	  If unsure, say N.
2488
2489config TEST_BLACKHOLE_DEV
2490	tristate "Test blackhole netdev functionality"
2491	depends on m && NET
2492	help
2493	  This builds the "test_blackhole_dev" module that validates the
2494	  data path through this blackhole netdev.
2495
2496	  If unsure, say N.
2497
2498config FIND_BIT_BENCHMARK
2499	tristate "Test find_bit functions"
2500	help
2501	  This builds the "test_find_bit" module that measure find_*_bit()
2502	  functions performance.
2503
2504	  If unsure, say N.
2505
2506config TEST_FIRMWARE
2507	tristate "Test firmware loading via userspace interface"
2508	depends on FW_LOADER
2509	help
2510	  This builds the "test_firmware" module that creates a userspace
2511	  interface for testing firmware loading. This can be used to
2512	  control the triggering of firmware loading without needing an
2513	  actual firmware-using device. The contents can be rechecked by
2514	  userspace.
2515
2516	  If unsure, say N.
2517
2518config TEST_SYSCTL
2519	tristate "sysctl test driver"
2520	depends on PROC_SYSCTL
2521	help
2522	  This builds the "test_sysctl" module. This driver enables to test the
2523	  proc sysctl interfaces available to drivers safely without affecting
2524	  production knobs which might alter system functionality.
2525
2526	  If unsure, say N.
2527
2528config BITFIELD_KUNIT
2529	tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS
2530	depends on KUNIT
2531	default KUNIT_ALL_TESTS
2532	help
2533	  Enable this option to test the bitfield functions at boot.
2534
2535	  KUnit tests run during boot and output the results to the debug log
2536	  in TAP format (http://testanything.org/). Only useful for kernel devs
2537	  running the KUnit test harness, and not intended for inclusion into a
2538	  production build.
2539
2540	  For more information on KUnit and unit tests in general please refer
2541	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2542
2543	  If unsure, say N.
2544
2545config CHECKSUM_KUNIT
2546	tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS
2547	depends on KUNIT
2548	default KUNIT_ALL_TESTS
2549	help
2550	  Enable this option to test the checksum functions at boot.
2551
2552	  KUnit tests run during boot and output the results to the debug log
2553	  in TAP format (http://testanything.org/). Only useful for kernel devs
2554	  running the KUnit test harness, and not intended for inclusion into a
2555	  production build.
2556
2557	  For more information on KUnit and unit tests in general please refer
2558	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2559
2560	  If unsure, say N.
2561
2562config HASH_KUNIT_TEST
2563	tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS
2564	depends on KUNIT
2565	default KUNIT_ALL_TESTS
2566	help
2567	  Enable this option to test the kernel's string (<linux/stringhash.h>), and
2568	  integer (<linux/hash.h>) hash functions on boot.
2569
2570	  KUnit tests run during boot and output the results to the debug log
2571	  in TAP format (https://testanything.org/). Only useful for kernel devs
2572	  running the KUnit test harness, and not intended for inclusion into a
2573	  production build.
2574
2575	  For more information on KUnit and unit tests in general please refer
2576	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2577
2578	  This is intended to help people writing architecture-specific
2579	  optimized versions. If unsure, say N.
2580
2581config RESOURCE_KUNIT_TEST
2582	tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS
2583	depends on KUNIT
2584	default KUNIT_ALL_TESTS
2585	help
2586	  This builds the resource API unit test.
2587	  Tests the logic of API provided by resource.c and ioport.h.
2588	  For more information on KUnit and unit tests in general please refer
2589	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2590
2591	  If unsure, say N.
2592
2593config SYSCTL_KUNIT_TEST
2594	tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS
2595	depends on KUNIT
2596	default KUNIT_ALL_TESTS
2597	help
2598	  This builds the proc sysctl unit test, which runs on boot.
2599	  Tests the API contract and implementation correctness of sysctl.
2600	  For more information on KUnit and unit tests in general please refer
2601	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2602
2603	  If unsure, say N.
2604
2605config LIST_KUNIT_TEST
2606	tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS
2607	depends on KUNIT
2608	default KUNIT_ALL_TESTS
2609	help
2610	  This builds the linked list KUnit test suite.
2611	  It tests that the API and basic functionality of the list_head type
2612	  and associated macros.
2613
2614	  KUnit tests run during boot and output the results to the debug log
2615	  in TAP format (https://testanything.org/). Only useful for kernel devs
2616	  running the KUnit test harness, and not intended for inclusion into a
2617	  production build.
2618
2619	  For more information on KUnit and unit tests in general please refer
2620	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2621
2622	  If unsure, say N.
2623
2624config HASHTABLE_KUNIT_TEST
2625	tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS
2626	depends on KUNIT
2627	default KUNIT_ALL_TESTS
2628	help
2629	  This builds the hashtable KUnit test suite.
2630	  It tests the basic functionality of the API defined in
2631	  include/linux/hashtable.h. For more information on KUnit and
2632	  unit tests in general please refer to the KUnit documentation
2633	  in Documentation/dev-tools/kunit/.
2634
2635	  If unsure, say N.
2636
2637config LINEAR_RANGES_TEST
2638	tristate "KUnit test for linear_ranges"
2639	depends on KUNIT
2640	select LINEAR_RANGES
2641	help
2642	  This builds the linear_ranges unit test, which runs on boot.
2643	  Tests the linear_ranges logic correctness.
2644	  For more information on KUnit and unit tests in general please refer
2645	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2646
2647	  If unsure, say N.
2648
2649config CMDLINE_KUNIT_TEST
2650	tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS
2651	depends on KUNIT
2652	default KUNIT_ALL_TESTS
2653	help
2654	  This builds the cmdline API unit test.
2655	  Tests the logic of API provided by cmdline.c.
2656	  For more information on KUnit and unit tests in general please refer
2657	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2658
2659	  If unsure, say N.
2660
2661config BITS_TEST
2662	tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS
2663	depends on KUNIT
2664	default KUNIT_ALL_TESTS
2665	help
2666	  This builds the bits unit test.
2667	  Tests the logic of macros defined in bits.h.
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 SLUB_KUNIT_TEST
2674	tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS
2675	depends on SLUB_DEBUG && KUNIT
2676	default KUNIT_ALL_TESTS
2677	help
2678	  This builds SLUB allocator unit test.
2679	  Tests SLUB cache debugging functionality.
2680	  For more information on KUnit and unit tests in general please refer
2681	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2682
2683	  If unsure, say N.
2684
2685config RATIONAL_KUNIT_TEST
2686	tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS
2687	depends on KUNIT && RATIONAL
2688	default KUNIT_ALL_TESTS
2689	help
2690	  This builds the rational math unit test.
2691	  For more information on KUnit and unit tests in general please refer
2692	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2693
2694	  If unsure, say N.
2695
2696config MEMCPY_KUNIT_TEST
2697	tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS
2698	depends on KUNIT
2699	default KUNIT_ALL_TESTS
2700	help
2701	  Builds unit tests for memcpy(), memmove(), and memset() functions.
2702	  For more information on KUnit and unit tests in general please refer
2703	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2704
2705	  If unsure, say N.
2706
2707config MEMCPY_SLOW_KUNIT_TEST
2708	bool "Include exhaustive memcpy tests"
2709	depends on MEMCPY_KUNIT_TEST
2710	default y
2711	help
2712	  Some memcpy tests are quite exhaustive in checking for overlaps
2713	  and bit ranges. These can be very slow, so they are split out
2714	  as a separate config, in case they need to be disabled.
2715
2716	  Note this config option will be replaced by the use of KUnit test
2717	  attributes.
2718
2719config IS_SIGNED_TYPE_KUNIT_TEST
2720	tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS
2721	depends on KUNIT
2722	default KUNIT_ALL_TESTS
2723	help
2724	  Builds unit tests for the is_signed_type() macro.
2725
2726	  For more information on KUnit and unit tests in general please refer
2727	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2728
2729	  If unsure, say N.
2730
2731config OVERFLOW_KUNIT_TEST
2732	tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS
2733	depends on KUNIT
2734	default KUNIT_ALL_TESTS
2735	help
2736	  Builds unit tests for the check_*_overflow(), size_*(), allocation, and
2737	  related functions.
2738
2739	  For more information on KUnit and unit tests in general please refer
2740	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2741
2742	  If unsure, say N.
2743
2744config STACKINIT_KUNIT_TEST
2745	tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS
2746	depends on KUNIT
2747	default KUNIT_ALL_TESTS
2748	help
2749	  Test if the kernel is zero-initializing stack variables and
2750	  padding. Coverage is controlled by compiler flags,
2751	  CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO,
2752	  CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2753	  or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2754
2755config FORTIFY_KUNIT_TEST
2756	tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS
2757	depends on KUNIT && FORTIFY_SOURCE
2758	default KUNIT_ALL_TESTS
2759	help
2760	  Builds unit tests for checking internals of FORTIFY_SOURCE as used
2761	  by the str*() and mem*() family of functions. For testing runtime
2762	  traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests.
2763
2764config HW_BREAKPOINT_KUNIT_TEST
2765	bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS
2766	depends on HAVE_HW_BREAKPOINT
2767	depends on KUNIT=y
2768	default KUNIT_ALL_TESTS
2769	help
2770	  Tests for hw_breakpoint constraints accounting.
2771
2772	  If unsure, say N.
2773
2774config STRCAT_KUNIT_TEST
2775	tristate "Test strcat() family of functions at runtime" if !KUNIT_ALL_TESTS
2776	depends on KUNIT
2777	default KUNIT_ALL_TESTS
2778
2779config STRSCPY_KUNIT_TEST
2780	tristate "Test strscpy*() family of functions at runtime" if !KUNIT_ALL_TESTS
2781	depends on KUNIT
2782	default KUNIT_ALL_TESTS
2783
2784config SIPHASH_KUNIT_TEST
2785	tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS
2786	depends on KUNIT
2787	default KUNIT_ALL_TESTS
2788	help
2789	  Enable this option to test the kernel's siphash (<linux/siphash.h>) hash
2790	  functions on boot (or module load).
2791
2792	  This is intended to help people writing architecture-specific
2793	  optimized versions.  If unsure, say N.
2794
2795config TEST_UDELAY
2796	tristate "udelay test driver"
2797	help
2798	  This builds the "udelay_test" module that helps to make sure
2799	  that udelay() is working properly.
2800
2801	  If unsure, say N.
2802
2803config TEST_STATIC_KEYS
2804	tristate "Test static keys"
2805	depends on m
2806	help
2807	  Test the static key interfaces.
2808
2809	  If unsure, say N.
2810
2811config TEST_DYNAMIC_DEBUG
2812	tristate "Test DYNAMIC_DEBUG"
2813	depends on DYNAMIC_DEBUG
2814	help
2815	  This module registers a tracer callback to count enabled
2816	  pr_debugs in a 'do_debugging' function, then alters their
2817	  enablements, calls the function, and compares counts.
2818
2819	  If unsure, say N.
2820
2821config TEST_KMOD
2822	tristate "kmod stress tester"
2823	depends on m
2824	depends on NETDEVICES && NET_CORE && INET # for TUN
2825	depends on BLOCK
2826	depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS
2827	select TEST_LKM
2828	select XFS_FS
2829	select TUN
2830	select BTRFS_FS
2831	help
2832	  Test the kernel's module loading mechanism: kmod. kmod implements
2833	  support to load modules using the Linux kernel's usermode helper.
2834	  This test provides a series of tests against kmod.
2835
2836	  Although technically you can either build test_kmod as a module or
2837	  into the kernel we disallow building it into the kernel since
2838	  it stress tests request_module() and this will very likely cause
2839	  some issues by taking over precious threads available from other
2840	  module load requests, ultimately this could be fatal.
2841
2842	  To run tests run:
2843
2844	  tools/testing/selftests/kmod/kmod.sh --help
2845
2846	  If unsure, say N.
2847
2848config TEST_DEBUG_VIRTUAL
2849	tristate "Test CONFIG_DEBUG_VIRTUAL feature"
2850	depends on DEBUG_VIRTUAL
2851	help
2852	  Test the kernel's ability to detect incorrect calls to
2853	  virt_to_phys() done against the non-linear part of the
2854	  kernel's virtual address map.
2855
2856	  If unsure, say N.
2857
2858config TEST_MEMCAT_P
2859	tristate "Test memcat_p() helper function"
2860	help
2861	  Test the memcat_p() helper for correctly merging two
2862	  pointer arrays together.
2863
2864	  If unsure, say N.
2865
2866config TEST_LIVEPATCH
2867	tristate "Test livepatching"
2868	default n
2869	depends on DYNAMIC_DEBUG
2870	depends on LIVEPATCH
2871	depends on m
2872	help
2873	  Test kernel livepatching features for correctness.  The tests will
2874	  load test modules that will be livepatched in various scenarios.
2875
2876	  To run all the livepatching tests:
2877
2878	  make -C tools/testing/selftests TARGETS=livepatch run_tests
2879
2880	  Alternatively, individual tests may be invoked:
2881
2882	  tools/testing/selftests/livepatch/test-callbacks.sh
2883	  tools/testing/selftests/livepatch/test-livepatch.sh
2884	  tools/testing/selftests/livepatch/test-shadow-vars.sh
2885
2886	  If unsure, say N.
2887
2888config TEST_OBJAGG
2889	tristate "Perform selftest on object aggreration manager"
2890	default n
2891	depends on OBJAGG
2892	help
2893	  Enable this option to test object aggregation manager on boot
2894	  (or module load).
2895
2896config TEST_MEMINIT
2897	tristate "Test heap/page initialization"
2898	help
2899	  Test if the kernel is zero-initializing heap and page allocations.
2900	  This can be useful to test init_on_alloc and init_on_free features.
2901
2902	  If unsure, say N.
2903
2904config TEST_HMM
2905	tristate "Test HMM (Heterogeneous Memory Management)"
2906	depends on TRANSPARENT_HUGEPAGE
2907	depends on DEVICE_PRIVATE
2908	select HMM_MIRROR
2909	select MMU_NOTIFIER
2910	help
2911	  This is a pseudo device driver solely for testing HMM.
2912	  Say M here if you want to build the HMM test module.
2913	  Doing so will allow you to run tools/testing/selftest/vm/hmm-tests.
2914
2915	  If unsure, say N.
2916
2917config TEST_FREE_PAGES
2918	tristate "Test freeing pages"
2919	help
2920	  Test that a memory leak does not occur due to a race between
2921	  freeing a block of pages and a speculative page reference.
2922	  Loading this module is safe if your kernel has the bug fixed.
2923	  If the bug is not fixed, it will leak gigabytes of memory and
2924	  probably OOM your system.
2925
2926config TEST_FPU
2927	tristate "Test floating point operations in kernel space"
2928	depends on X86 && !KCOV_INSTRUMENT_ALL
2929	help
2930	  Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu
2931	  which will trigger a sequence of floating point operations. This is used
2932	  for self-testing floating point control register setting in
2933	  kernel_fpu_begin().
2934
2935	  If unsure, say N.
2936
2937config TEST_CLOCKSOURCE_WATCHDOG
2938	tristate "Test clocksource watchdog in kernel space"
2939	depends on CLOCKSOURCE_WATCHDOG
2940	help
2941	  Enable this option to create a kernel module that will trigger
2942	  a test of the clocksource watchdog.  This module may be loaded
2943	  via modprobe or insmod in which case it will run upon being
2944	  loaded, or it may be built in, in which case it will run
2945	  shortly after boot.
2946
2947	  If unsure, say N.
2948
2949endif # RUNTIME_TESTING_MENU
2950
2951config ARCH_USE_MEMTEST
2952	bool
2953	help
2954	  An architecture should select this when it uses early_memtest()
2955	  during boot process.
2956
2957config MEMTEST
2958	bool "Memtest"
2959	depends on ARCH_USE_MEMTEST
2960	help
2961	  This option adds a kernel parameter 'memtest', which allows memtest
2962	  to be set and executed.
2963	        memtest=0, mean disabled; -- default
2964	        memtest=1, mean do 1 test pattern;
2965	        ...
2966	        memtest=17, mean do 17 test patterns.
2967	  If you are unsure how to answer this question, answer N.
2968
2969
2970
2971config HYPERV_TESTING
2972	bool "Microsoft Hyper-V driver testing"
2973	default n
2974	depends on HYPERV && DEBUG_FS
2975	help
2976	  Select this option to enable Hyper-V vmbus testing.
2977
2978endmenu # "Kernel Testing and Coverage"
2979
2980menu "Rust hacking"
2981
2982config RUST_DEBUG_ASSERTIONS
2983	bool "Debug assertions"
2984	depends on RUST
2985	help
2986	  Enables rustc's `-Cdebug-assertions` codegen option.
2987
2988	  This flag lets you turn `cfg(debug_assertions)` conditional
2989	  compilation on or off. This can be used to enable extra debugging
2990	  code in development but not in production. For example, it controls
2991	  the behavior of the standard library's `debug_assert!` macro.
2992
2993	  Note that this will apply to all Rust code, including `core`.
2994
2995	  If unsure, say N.
2996
2997config RUST_OVERFLOW_CHECKS
2998	bool "Overflow checks"
2999	default y
3000	depends on RUST
3001	help
3002	  Enables rustc's `-Coverflow-checks` codegen option.
3003
3004	  This flag allows you to control the behavior of runtime integer
3005	  overflow. When overflow-checks are enabled, a Rust panic will occur
3006	  on overflow.
3007
3008	  Note that this will apply to all Rust code, including `core`.
3009
3010	  If unsure, say Y.
3011
3012config RUST_BUILD_ASSERT_ALLOW
3013	bool "Allow unoptimized build-time assertions"
3014	depends on RUST
3015	help
3016	  Controls how are `build_error!` and `build_assert!` handled during build.
3017
3018	  If calls to them exist in the binary, it may indicate a violated invariant
3019	  or that the optimizer failed to verify the invariant during compilation.
3020
3021	  This should not happen, thus by default the build is aborted. However,
3022	  as an escape hatch, you can choose Y here to ignore them during build
3023	  and let the check be carried at runtime (with `panic!` being called if
3024	  the check fails).
3025
3026	  If unsure, say N.
3027
3028config RUST_KERNEL_DOCTESTS
3029	bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS
3030	depends on RUST && KUNIT=y
3031	default KUNIT_ALL_TESTS
3032	help
3033	  This builds the documentation tests of the `kernel` crate
3034	  as KUnit tests.
3035
3036	  For more information on KUnit and unit tests in general,
3037	  please refer to the KUnit documentation in Documentation/dev-tools/kunit/.
3038
3039	  If unsure, say N.
3040
3041endmenu # "Rust"
3042
3043endmenu # Kernel hacking
3044