Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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 jiffy" value.
101 See a previous boot log for the "lpj" value to use for your
102 system, and then set "lpj=M" before setting "boot_delay=N".
103 NOTE: Using this option may adversely affect SMP systems.
104 I.e., processors other than the first one may not boot up.
105 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
106 what it believes to be lockup conditions.
107
108config DYNAMIC_DEBUG
109 bool "Enable dynamic printk() support"
110 default n
111 depends on PRINTK
112 depends on (DEBUG_FS || PROC_FS)
113 select DYNAMIC_DEBUG_CORE
114 help
115
116 Compiles debug level messages into the kernel, which would not
117 otherwise be available at runtime. These messages can then be
118 enabled/disabled based on various levels of scope - per source file,
119 function, module, format string, and line number. This mechanism
120 implicitly compiles in all pr_debug() and dev_dbg() calls, which
121 enlarges the kernel text size by about 2%.
122
123 If a source file is compiled with DEBUG flag set, any
124 pr_debug() calls in it are enabled by default, but can be
125 disabled at runtime as below. Note that DEBUG flag is
126 turned on by many CONFIG_*DEBUG* options.
127
128 Usage:
129
130 Dynamic debugging is controlled via the 'dynamic_debug/control' file,
131 which is contained in the 'debugfs' filesystem or procfs.
132 Thus, the debugfs or procfs filesystem must first be mounted before
133 making use of this feature.
134 We refer the control file as: <debugfs>/dynamic_debug/control. This
135 file contains a list of the debug statements that can be enabled. The
136 format for each line of the file is:
137
138 filename:lineno [module]function flags format
139
140 filename : source file of the debug statement
141 lineno : line number of the debug statement
142 module : module that contains the debug statement
143 function : function that contains the debug statement
144 flags : '=p' means the line is turned 'on' for printing
145 format : the format used for the debug statement
146
147 From a live system:
148
149 nullarbor:~ # cat <debugfs>/dynamic_debug/control
150 # filename:lineno [module]function flags format
151 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
152 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
153 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
154
155 Example usage:
156
157 // enable the message at line 1603 of file svcsock.c
158 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
159 <debugfs>/dynamic_debug/control
160
161 // enable all the messages in file svcsock.c
162 nullarbor:~ # echo -n 'file svcsock.c +p' >
163 <debugfs>/dynamic_debug/control
164
165 // enable all the messages in the NFS server module
166 nullarbor:~ # echo -n 'module nfsd +p' >
167 <debugfs>/dynamic_debug/control
168
169 // enable all 12 messages in the function svc_process()
170 nullarbor:~ # echo -n 'func svc_process +p' >
171 <debugfs>/dynamic_debug/control
172
173 // disable all 12 messages in the function svc_process()
174 nullarbor:~ # echo -n 'func svc_process -p' >
175 <debugfs>/dynamic_debug/control
176
177 See Documentation/admin-guide/dynamic-debug-howto.rst for additional
178 information.
179
180config DYNAMIC_DEBUG_CORE
181 bool "Enable core function of dynamic debug support"
182 depends on PRINTK
183 depends on (DEBUG_FS || PROC_FS)
184 help
185 Enable core functional support of dynamic debug. It is useful
186 when you want to tie dynamic debug to your kernel modules with
187 DYNAMIC_DEBUG_MODULE defined for each of them, especially for
188 the case of embedded system where the kernel image size is
189 sensitive for people.
190
191config SYMBOLIC_ERRNAME
192 bool "Support symbolic error names in printf"
193 default y if PRINTK
194 help
195 If you say Y here, the kernel's printf implementation will
196 be able to print symbolic error names such as ENOSPC instead
197 of the number 28. It makes the kernel image slightly larger
198 (about 3KB), but can make the kernel logs easier to read.
199
200config DEBUG_BUGVERBOSE
201 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
202 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
203 default y
204 help
205 Say Y here to make BUG() panics output the file name and line number
206 of the BUG call as well as the EIP and oops trace. This aids
207 debugging but costs about 70-100K of memory.
208
209endmenu # "printk and dmesg options"
210
211config DEBUG_KERNEL
212 bool "Kernel debugging"
213 help
214 Say Y here if you are developing drivers or trying to debug and
215 identify kernel problems.
216
217config DEBUG_MISC
218 bool "Miscellaneous debug code"
219 default DEBUG_KERNEL
220 depends on DEBUG_KERNEL
221 help
222 Say Y here if you need to enable miscellaneous debug code that should
223 be under a more specific debug option but isn't.
224
225menu "Compile-time checks and compiler options"
226
227config DEBUG_INFO
228 bool
229 help
230 A kernel debug info option other than "None" has been selected
231 in the "Debug information" choice below, indicating that debug
232 information will be generated for build targets.
233
234# Clang generates .uleb128 with label differences for DWARF v5, a feature that
235# older binutils ports do not support when utilizing RISC-V style linker
236# relaxation: https://sourceware.org/bugzilla/show_bug.cgi?id=27215
237config AS_HAS_NON_CONST_ULEB128
238 def_bool $(as-instr,.uleb128 .Lexpr_end4 - .Lexpr_start3\n.Lexpr_start3:\n.Lexpr_end4:)
239
240choice
241 prompt "Debug information"
242 depends on DEBUG_KERNEL
243 help
244 Selecting something other than "None" results in a kernel image
245 that will include debugging info resulting in a larger kernel image.
246 This adds debug symbols to the kernel and modules (gcc -g), and
247 is needed if you intend to use kernel crashdump or binary object
248 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
249
250 Choose which version of DWARF debug info to emit. If unsure,
251 select "Toolchain default".
252
253config DEBUG_INFO_NONE
254 bool "Disable debug information"
255 help
256 Do not build the kernel with debugging information, which will
257 result in a faster and smaller build.
258
259config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
260 bool "Rely on the toolchain's implicit default DWARF version"
261 select DEBUG_INFO
262 depends on !CC_IS_CLANG || AS_IS_LLVM || CLANG_VERSION < 140000 || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128)
263 help
264 The implicit default version of DWARF debug info produced by a
265 toolchain changes over time.
266
267 This can break consumers of the debug info that haven't upgraded to
268 support newer revisions, and prevent testing newer versions, but
269 those should be less common scenarios.
270
271config DEBUG_INFO_DWARF4
272 bool "Generate DWARF Version 4 debuginfo"
273 select DEBUG_INFO
274 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502)
275 help
276 Generate DWARF v4 debug info. This requires gcc 4.5+, binutils 2.35.2
277 if using clang without clang's integrated assembler, and gdb 7.0+.
278
279 If you have consumers of DWARF debug info that are not ready for
280 newer revisions of DWARF, you may wish to choose this or have your
281 config select this.
282
283config DEBUG_INFO_DWARF5
284 bool "Generate DWARF Version 5 debuginfo"
285 select DEBUG_INFO
286 depends on !ARCH_HAS_BROKEN_DWARF5
287 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128)
288 help
289 Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc
290 5.0+ accepts the -gdwarf-5 flag but only had partial support for some
291 draft features until 7.0), and gdb 8.0+.
292
293 Changes to the structure of debug info in Version 5 allow for around
294 15-18% savings in resulting image and debug info section sizes as
295 compared to DWARF Version 4. DWARF Version 5 standardizes previous
296 extensions such as accelerators for symbol indexing and the format
297 for fission (.dwo/.dwp) files. Users may not want to select this
298 config if they rely on tooling that has not yet been updated to
299 support DWARF Version 5.
300
301endchoice # "Debug information"
302
303if DEBUG_INFO
304
305config DEBUG_INFO_REDUCED
306 bool "Reduce debugging information"
307 help
308 If you say Y here gcc is instructed to generate less debugging
309 information for structure types. This means that tools that
310 need full debugging information (like kgdb or systemtap) won't
311 be happy. But if you merely need debugging information to
312 resolve line numbers there is no loss. Advantage is that
313 build directory object sizes shrink dramatically over a full
314 DEBUG_INFO build and compile times are reduced too.
315 Only works with newer gcc versions.
316
317choice
318 prompt "Compressed Debug information"
319 help
320 Compress the resulting debug info. Results in smaller debug info sections,
321 but requires that consumers are able to decompress the results.
322
323 If unsure, choose DEBUG_INFO_COMPRESSED_NONE.
324
325config DEBUG_INFO_COMPRESSED_NONE
326 bool "Don't compress debug information"
327 help
328 Don't compress debug info sections.
329
330config DEBUG_INFO_COMPRESSED_ZLIB
331 bool "Compress debugging information with zlib"
332 depends on $(cc-option,-gz=zlib)
333 depends on $(ld-option,--compress-debug-sections=zlib)
334 help
335 Compress the debug information using zlib. Requires GCC 5.0+ or Clang
336 5.0+, binutils 2.26+, and zlib.
337
338 Users of dpkg-deb via scripts/package/builddeb may find an increase in
339 size of their debug .deb packages with this config set, due to the
340 debug info being compressed with zlib, then the object files being
341 recompressed with a different compression scheme. But this is still
342 preferable to setting $KDEB_COMPRESS to "none" which would be even
343 larger.
344
345config DEBUG_INFO_COMPRESSED_ZSTD
346 bool "Compress debugging information with zstd"
347 depends on $(cc-option,-gz=zstd)
348 depends on $(ld-option,--compress-debug-sections=zstd)
349 help
350 Compress the debug information using zstd. This may provide better
351 compression than zlib, for about the same time costs, but requires newer
352 toolchain support. Requires GCC 13.0+ or Clang 16.0+, binutils 2.40+, and
353 zstd.
354
355endchoice # "Compressed Debug information"
356
357config DEBUG_INFO_SPLIT
358 bool "Produce split debuginfo in .dwo files"
359 depends on $(cc-option,-gsplit-dwarf)
360 # RISC-V linker relaxation + -gsplit-dwarf has issues with LLVM and GCC
361 # prior to 12.x:
362 # https://github.com/llvm/llvm-project/issues/56642
363 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99090
364 depends on !RISCV || GCC_VERSION >= 120000
365 help
366 Generate debug info into separate .dwo files. This significantly
367 reduces the build directory size for builds with DEBUG_INFO,
368 because it stores the information only once on disk in .dwo
369 files instead of multiple times in object files and executables.
370 In addition the debug information is also compressed.
371
372 Requires recent gcc (4.7+) and recent gdb/binutils.
373 Any tool that packages or reads debug information would need
374 to know about the .dwo files and include them.
375 Incompatible with older versions of ccache.
376
377config DEBUG_INFO_BTF
378 bool "Generate BTF type information"
379 depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED
380 depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST
381 depends on BPF_SYSCALL
382 depends on PAHOLE_VERSION >= 116
383 depends on DEBUG_INFO_DWARF4 || PAHOLE_VERSION >= 121
384 # pahole uses elfutils, which does not have support for Hexagon relocations
385 depends on !HEXAGON
386 help
387 Generate deduplicated BTF type information from DWARF debug info.
388 Turning this on requires pahole v1.16 or later (v1.21 or later to
389 support DWARF 5), which will convert DWARF type info into equivalent
390 deduplicated BTF type info.
391
392config PAHOLE_HAS_SPLIT_BTF
393 def_bool PAHOLE_VERSION >= 119
394
395config PAHOLE_HAS_BTF_TAG
396 def_bool PAHOLE_VERSION >= 123
397 depends on CC_IS_CLANG
398 help
399 Decide whether pahole emits btf_tag attributes (btf_type_tag and
400 btf_decl_tag) or not. Currently only clang compiler implements
401 these attributes, so make the config depend on CC_IS_CLANG.
402
403config PAHOLE_HAS_LANG_EXCLUDE
404 def_bool PAHOLE_VERSION >= 124
405 help
406 Support for the --lang_exclude flag which makes pahole exclude
407 compilation units from the supplied language. Used in Kbuild to
408 omit Rust CUs which are not supported in version 1.24 of pahole,
409 otherwise it would emit malformed kernel and module binaries when
410 using DEBUG_INFO_BTF_MODULES.
411
412config DEBUG_INFO_BTF_MODULES
413 bool "Generate BTF type information for kernel modules"
414 default y
415 depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF
416 help
417 Generate compact split BTF type information for kernel modules.
418
419config MODULE_ALLOW_BTF_MISMATCH
420 bool "Allow loading modules with non-matching BTF type info"
421 depends on DEBUG_INFO_BTF_MODULES
422 help
423 For modules whose split BTF does not match vmlinux, load without
424 BTF rather than refusing to load. The default behavior with
425 module BTF enabled is to reject modules with such mismatches;
426 this option will still load module BTF where possible but ignore
427 it when a mismatch is found.
428
429config GDB_SCRIPTS
430 bool "Provide GDB scripts for kernel debugging"
431 help
432 This creates the required links to GDB helper scripts in the
433 build directory. If you load vmlinux into gdb, the helper
434 scripts will be automatically imported by gdb as well, and
435 additional functions are available to analyze a Linux kernel
436 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
437 for further details.
438
439endif # DEBUG_INFO
440
441config FRAME_WARN
442 int "Warn for stack frames larger than"
443 range 0 8192
444 default 0 if KMSAN
445 default 2048 if GCC_PLUGIN_LATENT_ENTROPY
446 default 2048 if PARISC
447 default 1536 if (!64BIT && XTENSA)
448 default 1280 if KASAN && !64BIT
449 default 1024 if !64BIT
450 default 2048 if 64BIT
451 help
452 Tell the compiler to warn at build time for stack frames larger than this.
453 Setting this too low will cause a lot of warnings.
454 Setting it to 0 disables the warning.
455
456config STRIP_ASM_SYMS
457 bool "Strip assembler-generated symbols during link"
458 default n
459 help
460 Strip internal assembler-generated symbols during a link (symbols
461 that look like '.Lxxx') so they don't pollute the output of
462 get_wchan() and suchlike.
463
464config READABLE_ASM
465 bool "Generate readable assembler code"
466 depends on DEBUG_KERNEL
467 depends on CC_IS_GCC
468 help
469 Disable some compiler optimizations that tend to generate human unreadable
470 assembler output. This may make the kernel slightly slower, but it helps
471 to keep kernel developers who have to stare a lot at assembler listings
472 sane.
473
474config HEADERS_INSTALL
475 bool "Install uapi headers to usr/include"
476 depends on !UML
477 help
478 This option will install uapi headers (headers exported to user-space)
479 into the usr/include directory for use during the kernel build.
480 This is unneeded for building the kernel itself, but needed for some
481 user-space program samples. It is also needed by some features such
482 as uapi header sanity checks.
483
484config DEBUG_SECTION_MISMATCH
485 bool "Enable full Section mismatch analysis"
486 depends on CC_IS_GCC
487 help
488 The section mismatch analysis checks if there are illegal
489 references from one section to another section.
490 During linktime or runtime, some sections are dropped;
491 any use of code/data previously in these sections would
492 most likely result in an oops.
493 In the code, functions and variables are annotated with
494 __init,, etc. (see the full list in include/linux/init.h),
495 which results in the code/data being placed in specific sections.
496 The section mismatch analysis is always performed after a full
497 kernel build, and enabling this option causes the following
498 additional step to occur:
499 - Add the option -fno-inline-functions-called-once to gcc commands.
500 When inlining a function annotated with __init in a non-init
501 function, we would lose the section information and thus
502 the analysis would not catch the illegal reference.
503 This option tells gcc to inline less (but it does result in
504 a larger kernel).
505
506config SECTION_MISMATCH_WARN_ONLY
507 bool "Make section mismatch errors non-fatal"
508 default y
509 help
510 If you say N here, the build process will fail if there are any
511 section mismatch, instead of just throwing warnings.
512
513 If unsure, say Y.
514
515config DEBUG_FORCE_FUNCTION_ALIGN_64B
516 bool "Force all function address 64B aligned"
517 depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC || RISCV || S390)
518 select FUNCTION_ALIGNMENT_64B
519 help
520 There are cases that a commit from one domain changes the function
521 address alignment of other domains, and cause magic performance
522 bump (regression or improvement). Enable this option will help to
523 verify if the bump is caused by function alignment changes, while
524 it will slightly increase the kernel size and affect icache usage.
525
526 It is mainly for debug and performance tuning use.
527
528#
529# Select this config option from the architecture Kconfig, if it
530# is preferred to always offer frame pointers as a config
531# option on the architecture (regardless of KERNEL_DEBUG):
532#
533config ARCH_WANT_FRAME_POINTERS
534 bool
535
536config FRAME_POINTER
537 bool "Compile the kernel with frame pointers"
538 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
539 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
540 help
541 If you say Y here the resulting kernel image will be slightly
542 larger and slower, but it gives very useful debugging information
543 in case of kernel bugs. (precise oopses/stacktraces/warnings)
544
545config OBJTOOL
546 bool
547
548config STACK_VALIDATION
549 bool "Compile-time stack metadata validation"
550 depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER
551 select OBJTOOL
552 default n
553 help
554 Validate frame pointer rules at compile-time. This helps ensure that
555 runtime stack traces are more reliable.
556
557 For more information, see
558 tools/objtool/Documentation/objtool.txt.
559
560config NOINSTR_VALIDATION
561 bool
562 depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY
563 select OBJTOOL
564 default y
565
566config VMLINUX_MAP
567 bool "Generate vmlinux.map file when linking"
568 depends on EXPERT
569 help
570 Selecting this option will pass "-Map=vmlinux.map" to ld
571 when linking vmlinux. That file can be useful for verifying
572 and debugging magic section games, and for seeing which
573 pieces of code get eliminated with
574 CONFIG_LD_DEAD_CODE_DATA_ELIMINATION.
575
576config BUILTIN_MODULE_RANGES
577 bool "Generate address range information for builtin modules"
578 depends on !LTO
579 depends on VMLINUX_MAP
580 help
581 When modules are built into the kernel, there will be no module name
582 associated with its symbols in /proc/kallsyms. Tracers may want to
583 identify symbols by module name and symbol name regardless of whether
584 the module is configured as loadable or not.
585
586 This option generates modules.builtin.ranges in the build tree with
587 offset ranges (per ELF section) for the module(s) they belong to.
588 It also records an anchor symbol to determine the load address of the
589 section.
590
591config DEBUG_FORCE_WEAK_PER_CPU
592 bool "Force weak per-cpu definitions"
593 depends on DEBUG_KERNEL
594 help
595 s390 and alpha require percpu variables in modules to be
596 defined weak to work around addressing range issue which
597 puts the following two restrictions on percpu variable
598 definitions.
599
600 1. percpu symbols must be unique whether static or not
601 2. percpu variables can't be defined inside a function
602
603 To ensure that generic code follows the above rules, this
604 option forces all percpu variables to be defined as weak.
605
606endmenu # "Compiler options"
607
608menu "Generic Kernel Debugging Instruments"
609
610config MAGIC_SYSRQ
611 bool "Magic SysRq key"
612 depends on !UML
613 help
614 If you say Y here, you will have some control over the system even
615 if the system crashes for example during kernel debugging (e.g., you
616 will be able to flush the buffer cache to disk, reboot the system
617 immediately or dump some status information). This is accomplished
618 by pressing various keys while holding SysRq (Alt+PrintScreen). It
619 also works on a serial console (on PC hardware at least), if you
620 send a BREAK and then within 5 seconds a command keypress. The
621 keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
622 Don't say Y unless you really know what this hack does.
623
624config MAGIC_SYSRQ_DEFAULT_ENABLE
625 hex "Enable magic SysRq key functions by default"
626 depends on MAGIC_SYSRQ
627 default 0x1
628 help
629 Specifies which SysRq key functions are enabled by default.
630 This may be set to 1 or 0 to enable or disable them all, or
631 to a bitmask as described in Documentation/admin-guide/sysrq.rst.
632
633config MAGIC_SYSRQ_SERIAL
634 bool "Enable magic SysRq key over serial"
635 depends on MAGIC_SYSRQ
636 default y
637 help
638 Many embedded boards have a disconnected TTL level serial which can
639 generate some garbage that can lead to spurious false sysrq detects.
640 This option allows you to decide whether you want to enable the
641 magic SysRq key.
642
643config MAGIC_SYSRQ_SERIAL_SEQUENCE
644 string "Char sequence that enables magic SysRq over serial"
645 depends on MAGIC_SYSRQ_SERIAL
646 default ""
647 help
648 Specifies a sequence of characters that can follow BREAK to enable
649 SysRq on a serial console.
650
651 If unsure, leave an empty string and the option will not be enabled.
652
653config DEBUG_FS
654 bool "Debug Filesystem"
655 help
656 debugfs is a virtual file system that kernel developers use to put
657 debugging files into. Enable this option to be able to read and
658 write to these files.
659
660 For detailed documentation on the debugfs API, see
661 Documentation/filesystems/.
662
663 If unsure, say N.
664
665choice
666 prompt "Debugfs default access"
667 depends on DEBUG_FS
668 default DEBUG_FS_ALLOW_ALL
669 help
670 This selects the default access restrictions for debugfs.
671 It can be overridden with kernel command line option
672 debugfs=[on,no-mount,off]. The restrictions apply for API access
673 and filesystem registration.
674
675config DEBUG_FS_ALLOW_ALL
676 bool "Access normal"
677 help
678 No restrictions apply. Both API and filesystem registration
679 is on. This is the normal default operation.
680
681config DEBUG_FS_DISALLOW_MOUNT
682 bool "Do not register debugfs as filesystem"
683 help
684 The API is open but filesystem is not loaded. Clients can still do
685 their work and read with debug tools that do not need
686 debugfs filesystem.
687
688config DEBUG_FS_ALLOW_NONE
689 bool "No access"
690 help
691 Access is off. Clients get -PERM when trying to create nodes in
692 debugfs tree and debugfs is not registered as a filesystem.
693 Client can then back-off or continue without debugfs access.
694
695endchoice
696
697source "lib/Kconfig.kgdb"
698source "lib/Kconfig.ubsan"
699source "lib/Kconfig.kcsan"
700
701endmenu
702
703menu "Networking Debugging"
704
705source "net/Kconfig.debug"
706
707endmenu # "Networking Debugging"
708
709menu "Memory Debugging"
710
711source "mm/Kconfig.debug"
712
713config DEBUG_OBJECTS
714 bool "Debug object operations"
715 depends on DEBUG_KERNEL
716 help
717 If you say Y here, additional code will be inserted into the
718 kernel to track the life time of various objects and validate
719 the operations on those objects.
720
721config DEBUG_OBJECTS_SELFTEST
722 bool "Debug objects selftest"
723 depends on DEBUG_OBJECTS
724 help
725 This enables the selftest of the object debug code.
726
727config DEBUG_OBJECTS_FREE
728 bool "Debug objects in freed memory"
729 depends on DEBUG_OBJECTS
730 help
731 This enables checks whether a k/v free operation frees an area
732 which contains an object which has not been deactivated
733 properly. This can make kmalloc/kfree-intensive workloads
734 much slower.
735
736config DEBUG_OBJECTS_TIMERS
737 bool "Debug timer objects"
738 depends on DEBUG_OBJECTS
739 help
740 If you say Y here, additional code will be inserted into the
741 timer routines to track the life time of timer objects and
742 validate the timer operations.
743
744config DEBUG_OBJECTS_WORK
745 bool "Debug work objects"
746 depends on DEBUG_OBJECTS
747 help
748 If you say Y here, additional code will be inserted into the
749 work queue routines to track the life time of work objects and
750 validate the work operations.
751
752config DEBUG_OBJECTS_RCU_HEAD
753 bool "Debug RCU callbacks objects"
754 depends on DEBUG_OBJECTS
755 help
756 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
757
758config DEBUG_OBJECTS_PERCPU_COUNTER
759 bool "Debug percpu counter objects"
760 depends on DEBUG_OBJECTS
761 help
762 If you say Y here, additional code will be inserted into the
763 percpu counter routines to track the life time of percpu counter
764 objects and validate the percpu counter operations.
765
766config DEBUG_OBJECTS_ENABLE_DEFAULT
767 int "debug_objects bootup default value (0-1)"
768 range 0 1
769 default "1"
770 depends on DEBUG_OBJECTS
771 help
772 Debug objects boot parameter default value
773
774config SHRINKER_DEBUG
775 bool "Enable shrinker debugging support"
776 depends on DEBUG_FS
777 help
778 Say Y to enable the shrinker debugfs interface which provides
779 visibility into the kernel memory shrinkers subsystem.
780 Disable it to avoid an extra memory footprint.
781
782config DEBUG_STACK_USAGE
783 bool "Stack utilization instrumentation"
784 depends on DEBUG_KERNEL
785 help
786 Enables the display of the minimum amount of free stack which each
787 task has ever had available in the sysrq-T and sysrq-P debug output.
788 Also emits a message to dmesg when a process exits if that process
789 used more stack space than previously exiting processes.
790
791 This option will slow down process creation somewhat.
792
793config SCHED_STACK_END_CHECK
794 bool "Detect stack corruption on calls to schedule()"
795 depends on DEBUG_KERNEL
796 default n
797 help
798 This option checks for a stack overrun on calls to schedule().
799 If the stack end location is found to be over written always panic as
800 the content of the corrupted region can no longer be trusted.
801 This is to ensure no erroneous behaviour occurs which could result in
802 data corruption or a sporadic crash at a later stage once the region
803 is examined. The runtime overhead introduced is minimal.
804
805config ARCH_HAS_DEBUG_VM_PGTABLE
806 bool
807 help
808 An architecture should select this when it can successfully
809 build and run DEBUG_VM_PGTABLE.
810
811config DEBUG_VM_IRQSOFF
812 def_bool DEBUG_VM && !PREEMPT_RT
813
814config DEBUG_VM
815 bool "Debug VM"
816 depends on DEBUG_KERNEL
817 help
818 Enable this to turn on extended checks in the virtual-memory system
819 that may impact performance.
820
821 If unsure, say N.
822
823config DEBUG_VM_SHOOT_LAZIES
824 bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation"
825 depends on DEBUG_VM
826 depends on MMU_LAZY_TLB_SHOOTDOWN
827 help
828 Enable additional IPIs that ensure lazy tlb mm references are removed
829 before the mm is freed.
830
831 If unsure, say N.
832
833config DEBUG_VM_MAPLE_TREE
834 bool "Debug VM maple trees"
835 depends on DEBUG_VM
836 select DEBUG_MAPLE_TREE
837 help
838 Enable VM maple tree debugging information and extra validations.
839
840 If unsure, say N.
841
842config DEBUG_VM_RB
843 bool "Debug VM red-black trees"
844 depends on DEBUG_VM
845 help
846 Enable VM red-black tree debugging information and extra validations.
847
848 If unsure, say N.
849
850config DEBUG_VM_PGFLAGS
851 bool "Debug page-flags operations"
852 depends on DEBUG_VM
853 help
854 Enables extra validation on page flags operations.
855
856 If unsure, say N.
857
858config DEBUG_VM_PGTABLE
859 bool "Debug arch page table for semantics compliance"
860 depends on MMU
861 depends on ARCH_HAS_DEBUG_VM_PGTABLE
862 default y if DEBUG_VM
863 help
864 This option provides a debug method which can be used to test
865 architecture page table helper functions on various platforms in
866 verifying if they comply with expected generic MM semantics. This
867 will help architecture code in making sure that any changes or
868 new additions of these helpers still conform to expected
869 semantics of the generic MM. Platforms will have to opt in for
870 this through ARCH_HAS_DEBUG_VM_PGTABLE.
871
872 If unsure, say N.
873
874config ARCH_HAS_DEBUG_VIRTUAL
875 bool
876
877config DEBUG_VIRTUAL
878 bool "Debug VM translations"
879 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
880 help
881 Enable some costly sanity checks in virtual to page code. This can
882 catch mistakes with virt_to_page() and friends.
883
884 If unsure, say N.
885
886config DEBUG_NOMMU_REGIONS
887 bool "Debug the global anon/private NOMMU mapping region tree"
888 depends on DEBUG_KERNEL && !MMU
889 help
890 This option causes the global tree of anonymous and private mapping
891 regions to be regularly checked for invalid topology.
892
893config DEBUG_MEMORY_INIT
894 bool "Debug memory initialisation" if EXPERT
895 default !EXPERT
896 help
897 Enable this for additional checks during memory initialisation.
898 The sanity checks verify aspects of the VM such as the memory model
899 and other information provided by the architecture. Verbose
900 information will be printed at KERN_DEBUG loglevel depending
901 on the mminit_loglevel= command-line option.
902
903 If unsure, say Y
904
905config MEMORY_NOTIFIER_ERROR_INJECT
906 tristate "Memory hotplug notifier error injection module"
907 depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION
908 help
909 This option provides the ability to inject artificial errors to
910 memory hotplug notifier chain callbacks. It is controlled through
911 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
912
913 If the notifier call chain should be failed with some events
914 notified, write the error code to "actions/<notifier event>/error".
915
916 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
917
918 # cd /sys/kernel/debug/notifier-error-inject/memory
919 # echo -12 > actions/MEM_GOING_OFFLINE/error
920 # echo offline > /sys/devices/system/memory/memoryXXX/state
921 bash: echo: write error: Cannot allocate memory
922
923 To compile this code as a module, choose M here: the module will
924 be called memory-notifier-error-inject.
925
926 If unsure, say N.
927
928config DEBUG_PER_CPU_MAPS
929 bool "Debug access to per_cpu maps"
930 depends on DEBUG_KERNEL
931 depends on SMP
932 help
933 Say Y to verify that the per_cpu map being accessed has
934 been set up. This adds a fair amount of code to kernel memory
935 and decreases performance.
936
937 Say N if unsure.
938
939config DEBUG_KMAP_LOCAL
940 bool "Debug kmap_local temporary mappings"
941 depends on DEBUG_KERNEL && KMAP_LOCAL
942 help
943 This option enables additional error checking for the kmap_local
944 infrastructure. Disable for production use.
945
946config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
947 bool
948
949config DEBUG_KMAP_LOCAL_FORCE_MAP
950 bool "Enforce kmap_local temporary mappings"
951 depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
952 select KMAP_LOCAL
953 select DEBUG_KMAP_LOCAL
954 help
955 This option enforces temporary mappings through the kmap_local
956 mechanism for non-highmem pages and on non-highmem systems.
957 Disable this for production systems!
958
959config DEBUG_HIGHMEM
960 bool "Highmem debugging"
961 depends on DEBUG_KERNEL && HIGHMEM
962 select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
963 select DEBUG_KMAP_LOCAL
964 help
965 This option enables additional error checking for high memory
966 systems. Disable for production systems.
967
968config HAVE_DEBUG_STACKOVERFLOW
969 bool
970
971config DEBUG_STACKOVERFLOW
972 bool "Check for stack overflows"
973 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
974 help
975 Say Y here if you want to check for overflows of kernel, IRQ
976 and exception stacks (if your architecture uses them). This
977 option will show detailed messages if free stack space drops
978 below a certain limit.
979
980 These kinds of bugs usually occur when call-chains in the
981 kernel get too deep, especially when interrupts are
982 involved.
983
984 Use this in cases where you see apparently random memory
985 corruption, especially if it appears in 'struct thread_info'
986
987 If in doubt, say "N".
988
989config CODE_TAGGING
990 bool
991 select KALLSYMS
992
993config MEM_ALLOC_PROFILING
994 bool "Enable memory allocation profiling"
995 default n
996 depends on PROC_FS
997 depends on !DEBUG_FORCE_WEAK_PER_CPU
998 select CODE_TAGGING
999 select PAGE_EXTENSION
1000 select SLAB_OBJ_EXT
1001 help
1002 Track allocation source code and record total allocation size
1003 initiated at that code location. The mechanism can be used to track
1004 memory leaks with a low performance and memory impact.
1005
1006config MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT
1007 bool "Enable memory allocation profiling by default"
1008 default y
1009 depends on MEM_ALLOC_PROFILING
1010
1011config MEM_ALLOC_PROFILING_DEBUG
1012 bool "Memory allocation profiler debugging"
1013 default n
1014 depends on MEM_ALLOC_PROFILING
1015 select MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT
1016 help
1017 Adds warnings with helpful error messages for memory allocation
1018 profiling.
1019
1020source "lib/Kconfig.kasan"
1021source "lib/Kconfig.kfence"
1022source "lib/Kconfig.kmsan"
1023
1024endmenu # "Memory Debugging"
1025
1026config DEBUG_SHIRQ
1027 bool "Debug shared IRQ handlers"
1028 depends on DEBUG_KERNEL
1029 help
1030 Enable this to generate a spurious interrupt just before a shared
1031 interrupt handler is deregistered (generating one when registering
1032 is currently disabled). Drivers need to handle this correctly. Some
1033 don't and need to be caught.
1034
1035menu "Debug Oops, Lockups and Hangs"
1036
1037config PANIC_ON_OOPS
1038 bool "Panic on Oops"
1039 help
1040 Say Y here to enable the kernel to panic when it oopses. This
1041 has the same effect as setting oops=panic on the kernel command
1042 line.
1043
1044 This feature is useful to ensure that the kernel does not do
1045 anything erroneous after an oops which could result in data
1046 corruption or other issues.
1047
1048 Say N if unsure.
1049
1050config PANIC_ON_OOPS_VALUE
1051 int
1052 range 0 1
1053 default 0 if !PANIC_ON_OOPS
1054 default 1 if PANIC_ON_OOPS
1055
1056config PANIC_TIMEOUT
1057 int "panic timeout"
1058 default 0
1059 help
1060 Set the timeout value (in seconds) until a reboot occurs when
1061 the kernel panics. If n = 0, then we wait forever. A timeout
1062 value n > 0 will wait n seconds before rebooting, while a timeout
1063 value n < 0 will reboot immediately. This setting can be overridden
1064 with the kernel command line option panic=, and from userspace via
1065 /proc/sys/kernel/panic.
1066
1067config LOCKUP_DETECTOR
1068 bool
1069
1070config SOFTLOCKUP_DETECTOR
1071 bool "Detect Soft Lockups"
1072 depends on DEBUG_KERNEL && !S390
1073 select LOCKUP_DETECTOR
1074 help
1075 Say Y here to enable the kernel to act as a watchdog to detect
1076 soft lockups.
1077
1078 Softlockups are bugs that cause the kernel to loop in kernel
1079 mode for more than 20 seconds, without giving other tasks a
1080 chance to run. The current stack trace is displayed upon
1081 detection and the system will stay locked up.
1082
1083config SOFTLOCKUP_DETECTOR_INTR_STORM
1084 bool "Detect Interrupt Storm in Soft Lockups"
1085 depends on SOFTLOCKUP_DETECTOR && IRQ_TIME_ACCOUNTING
1086 select GENERIC_IRQ_STAT_SNAPSHOT
1087 default y if NR_CPUS <= 128
1088 help
1089 Say Y here to enable the kernel to detect interrupt storm
1090 during "soft lockups".
1091
1092 "soft lockups" can be caused by a variety of reasons. If one is
1093 caused by an interrupt storm, then the storming interrupts will not
1094 be on the callstack. To detect this case, it is necessary to report
1095 the CPU stats and the interrupt counts during the "soft lockups".
1096
1097config BOOTPARAM_SOFTLOCKUP_PANIC
1098 bool "Panic (Reboot) On Soft Lockups"
1099 depends on SOFTLOCKUP_DETECTOR
1100 help
1101 Say Y here to enable the kernel to panic on "soft lockups",
1102 which are bugs that cause the kernel to loop in kernel
1103 mode for more than 20 seconds (configurable using the watchdog_thresh
1104 sysctl), without giving other tasks a chance to run.
1105
1106 The panic can be used in combination with panic_timeout,
1107 to cause the system to reboot automatically after a
1108 lockup has been detected. This feature is useful for
1109 high-availability systems that have uptime guarantees and
1110 where a lockup must be resolved ASAP.
1111
1112 Say N if unsure.
1113
1114config HAVE_HARDLOCKUP_DETECTOR_BUDDY
1115 bool
1116 depends on SMP
1117 default y
1118
1119#
1120# Global switch whether to build a hardlockup detector at all. It is available
1121# only when the architecture supports at least one implementation. There are
1122# two exceptions. The hardlockup detector is never enabled on:
1123#
1124# s390: it reported many false positives there
1125#
1126# sparc64: has a custom implementation which is not using the common
1127# hardlockup command line options and sysctl interface.
1128#
1129config HARDLOCKUP_DETECTOR
1130 bool "Detect Hard Lockups"
1131 depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64
1132 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH
1133 imply HARDLOCKUP_DETECTOR_PERF
1134 imply HARDLOCKUP_DETECTOR_BUDDY
1135 imply HARDLOCKUP_DETECTOR_ARCH
1136 select LOCKUP_DETECTOR
1137
1138 help
1139 Say Y here to enable the kernel to act as a watchdog to detect
1140 hard lockups.
1141
1142 Hardlockups are bugs that cause the CPU to loop in kernel mode
1143 for more than 10 seconds, without letting other interrupts have a
1144 chance to run. The current stack trace is displayed upon detection
1145 and the system will stay locked up.
1146
1147#
1148# Note that arch-specific variants are always preferred.
1149#
1150config HARDLOCKUP_DETECTOR_PREFER_BUDDY
1151 bool "Prefer the buddy CPU hardlockup detector"
1152 depends on HARDLOCKUP_DETECTOR
1153 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY
1154 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1155 help
1156 Say Y here to prefer the buddy hardlockup detector over the perf one.
1157
1158 With the buddy detector, each CPU uses its softlockup hrtimer
1159 to check that the next CPU is processing hrtimer interrupts by
1160 verifying that a counter is increasing.
1161
1162 This hardlockup detector is useful on systems that don't have
1163 an arch-specific hardlockup detector or if resources needed
1164 for the hardlockup detector are better used for other things.
1165
1166config HARDLOCKUP_DETECTOR_PERF
1167 bool
1168 depends on HARDLOCKUP_DETECTOR
1169 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY
1170 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1171 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1172
1173config HARDLOCKUP_DETECTOR_BUDDY
1174 bool
1175 depends on HARDLOCKUP_DETECTOR
1176 depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY
1177 depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY
1178 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1179 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1180
1181config HARDLOCKUP_DETECTOR_ARCH
1182 bool
1183 depends on HARDLOCKUP_DETECTOR
1184 depends on HAVE_HARDLOCKUP_DETECTOR_ARCH
1185 help
1186 The arch-specific implementation of the hardlockup detector will
1187 be used.
1188
1189#
1190# Both the "perf" and "buddy" hardlockup detectors count hrtimer
1191# interrupts. This config enables functions managing this common code.
1192#
1193config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1194 bool
1195 select SOFTLOCKUP_DETECTOR
1196
1197#
1198# Enables a timestamp based low pass filter to compensate for perf based
1199# hard lockup detection which runs too fast due to turbo modes.
1200#
1201config HARDLOCKUP_CHECK_TIMESTAMP
1202 bool
1203
1204config BOOTPARAM_HARDLOCKUP_PANIC
1205 bool "Panic (Reboot) On Hard Lockups"
1206 depends on HARDLOCKUP_DETECTOR
1207 help
1208 Say Y here to enable the kernel to panic on "hard lockups",
1209 which are bugs that cause the kernel to loop in kernel
1210 mode with interrupts disabled for more than 10 seconds (configurable
1211 using the watchdog_thresh sysctl).
1212
1213 Say N if unsure.
1214
1215config DETECT_HUNG_TASK
1216 bool "Detect Hung Tasks"
1217 depends on DEBUG_KERNEL
1218 default SOFTLOCKUP_DETECTOR
1219 help
1220 Say Y here to enable the kernel to detect "hung tasks",
1221 which are bugs that cause the task to be stuck in
1222 uninterruptible "D" state indefinitely.
1223
1224 When a hung task is detected, the kernel will print the
1225 current stack trace (which you should report), but the
1226 task will stay in uninterruptible state. If lockdep is
1227 enabled then all held locks will also be reported. This
1228 feature has negligible overhead.
1229
1230config DEFAULT_HUNG_TASK_TIMEOUT
1231 int "Default timeout for hung task detection (in seconds)"
1232 depends on DETECT_HUNG_TASK
1233 default 120
1234 help
1235 This option controls the default timeout (in seconds) used
1236 to determine when a task has become non-responsive and should
1237 be considered hung.
1238
1239 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
1240 sysctl or by writing a value to
1241 /proc/sys/kernel/hung_task_timeout_secs.
1242
1243 A timeout of 0 disables the check. The default is two minutes.
1244 Keeping the default should be fine in most cases.
1245
1246config BOOTPARAM_HUNG_TASK_PANIC
1247 bool "Panic (Reboot) On Hung Tasks"
1248 depends on DETECT_HUNG_TASK
1249 help
1250 Say Y here to enable the kernel to panic on "hung tasks",
1251 which are bugs that cause the kernel to leave a task stuck
1252 in uninterruptible "D" state.
1253
1254 The panic can be used in combination with panic_timeout,
1255 to cause the system to reboot automatically after a
1256 hung task has been detected. This feature is useful for
1257 high-availability systems that have uptime guarantees and
1258 where a hung tasks must be resolved ASAP.
1259
1260 Say N if unsure.
1261
1262config WQ_WATCHDOG
1263 bool "Detect Workqueue Stalls"
1264 depends on DEBUG_KERNEL
1265 help
1266 Say Y here to enable stall detection on workqueues. If a
1267 worker pool doesn't make forward progress on a pending work
1268 item for over a given amount of time, 30s by default, a
1269 warning message is printed along with dump of workqueue
1270 state. This can be configured through kernel parameter
1271 "workqueue.watchdog_thresh" and its sysfs counterpart.
1272
1273config WQ_CPU_INTENSIVE_REPORT
1274 bool "Report per-cpu work items which hog CPU for too long"
1275 depends on DEBUG_KERNEL
1276 help
1277 Say Y here to enable reporting of concurrency-managed per-cpu work
1278 items that hog CPUs for longer than
1279 workqueue.cpu_intensive_thresh_us. Workqueue automatically
1280 detects and excludes them from concurrency management to prevent
1281 them from stalling other per-cpu work items. Occassional
1282 triggering may not necessarily indicate a problem. Repeated
1283 triggering likely indicates that the work item should be switched
1284 to use an unbound workqueue.
1285
1286config TEST_LOCKUP
1287 tristate "Test module to generate lockups"
1288 depends on m
1289 help
1290 This builds the "test_lockup" module that helps to make sure
1291 that watchdogs and lockup detectors are working properly.
1292
1293 Depending on module parameters it could emulate soft or hard
1294 lockup, "hung task", or locking arbitrary lock for a long time.
1295 Also it could generate series of lockups with cooling-down periods.
1296
1297 If unsure, say N.
1298
1299endmenu # "Debug lockups and hangs"
1300
1301menu "Scheduler Debugging"
1302
1303config SCHED_DEBUG
1304 bool "Collect scheduler debugging info"
1305 depends on DEBUG_KERNEL && DEBUG_FS
1306 default y
1307 help
1308 If you say Y here, the /sys/kernel/debug/sched file will be provided
1309 that can help debug the scheduler. The runtime overhead of this
1310 option is minimal.
1311
1312config SCHED_INFO
1313 bool
1314 default n
1315
1316config SCHEDSTATS
1317 bool "Collect scheduler statistics"
1318 depends on PROC_FS
1319 select SCHED_INFO
1320 help
1321 If you say Y here, additional code will be inserted into the
1322 scheduler and related routines to collect statistics about
1323 scheduler behavior and provide them in /proc/schedstat. These
1324 stats may be useful for both tuning and debugging the scheduler
1325 If you aren't debugging the scheduler or trying to tune a specific
1326 application, you can say N to avoid the very slight overhead
1327 this adds.
1328
1329endmenu
1330
1331config DEBUG_TIMEKEEPING
1332 bool "Enable extra timekeeping sanity checking"
1333 help
1334 This option will enable additional timekeeping sanity checks
1335 which may be helpful when diagnosing issues where timekeeping
1336 problems are suspected.
1337
1338 This may include checks in the timekeeping hotpaths, so this
1339 option may have a (very small) performance impact to some
1340 workloads.
1341
1342 If unsure, say N.
1343
1344config DEBUG_PREEMPT
1345 bool "Debug preemptible kernel"
1346 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT
1347 help
1348 If you say Y here then the kernel will use a debug variant of the
1349 commonly used smp_processor_id() function and will print warnings
1350 if kernel code uses it in a preemption-unsafe way. Also, the kernel
1351 will detect preemption count underflows.
1352
1353 This option has potential to introduce high runtime overhead,
1354 depending on workload as it triggers debugging routines for each
1355 this_cpu operation. It should only be used for debugging purposes.
1356
1357menu "Lock Debugging (spinlocks, mutexes, etc...)"
1358
1359config LOCK_DEBUGGING_SUPPORT
1360 bool
1361 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1362 default y
1363
1364config PROVE_LOCKING
1365 bool "Lock debugging: prove locking correctness"
1366 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1367 select LOCKDEP
1368 select DEBUG_SPINLOCK
1369 select DEBUG_MUTEXES if !PREEMPT_RT
1370 select DEBUG_RT_MUTEXES if RT_MUTEXES
1371 select DEBUG_RWSEMS if !PREEMPT_RT
1372 select DEBUG_WW_MUTEX_SLOWPATH
1373 select DEBUG_LOCK_ALLOC
1374 select PREEMPT_COUNT if !ARCH_NO_PREEMPT
1375 select TRACE_IRQFLAGS
1376 default n
1377 help
1378 This feature enables the kernel to prove that all locking
1379 that occurs in the kernel runtime is mathematically
1380 correct: that under no circumstance could an arbitrary (and
1381 not yet triggered) combination of observed locking
1382 sequences (on an arbitrary number of CPUs, running an
1383 arbitrary number of tasks and interrupt contexts) cause a
1384 deadlock.
1385
1386 In short, this feature enables the kernel to report locking
1387 related deadlocks before they actually occur.
1388
1389 The proof does not depend on how hard and complex a
1390 deadlock scenario would be to trigger: how many
1391 participant CPUs, tasks and irq-contexts would be needed
1392 for it to trigger. The proof also does not depend on
1393 timing: if a race and a resulting deadlock is possible
1394 theoretically (no matter how unlikely the race scenario
1395 is), it will be proven so and will immediately be
1396 reported by the kernel (once the event is observed that
1397 makes the deadlock theoretically possible).
1398
1399 If a deadlock is impossible (i.e. the locking rules, as
1400 observed by the kernel, are mathematically correct), the
1401 kernel reports nothing.
1402
1403 NOTE: this feature can also be enabled for rwlocks, mutexes
1404 and rwsems - in which case all dependencies between these
1405 different locking variants are observed and mapped too, and
1406 the proof of observed correctness is also maintained for an
1407 arbitrary combination of these separate locking variants.
1408
1409 For more details, see Documentation/locking/lockdep-design.rst.
1410
1411config PROVE_RAW_LOCK_NESTING
1412 bool "Enable raw_spinlock - spinlock nesting checks"
1413 depends on PROVE_LOCKING
1414 default n
1415 help
1416 Enable the raw_spinlock vs. spinlock nesting checks which ensure
1417 that the lock nesting rules for PREEMPT_RT enabled kernels are
1418 not violated.
1419
1420 NOTE: There are known nesting problems. So if you enable this
1421 option expect lockdep splats until these problems have been fully
1422 addressed which is work in progress. This config switch allows to
1423 identify and analyze these problems. It will be removed and the
1424 check permanently enabled once the main issues have been fixed.
1425
1426 If unsure, select N.
1427
1428config LOCK_STAT
1429 bool "Lock usage statistics"
1430 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1431 select LOCKDEP
1432 select DEBUG_SPINLOCK
1433 select DEBUG_MUTEXES if !PREEMPT_RT
1434 select DEBUG_RT_MUTEXES if RT_MUTEXES
1435 select DEBUG_LOCK_ALLOC
1436 default n
1437 help
1438 This feature enables tracking lock contention points
1439
1440 For more details, see Documentation/locking/lockstat.rst
1441
1442 This also enables lock events required by "perf lock",
1443 subcommand of perf.
1444 If you want to use "perf lock", you also need to turn on
1445 CONFIG_EVENT_TRACING.
1446
1447 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1448 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1449
1450config DEBUG_RT_MUTEXES
1451 bool "RT Mutex debugging, deadlock detection"
1452 depends on DEBUG_KERNEL && RT_MUTEXES
1453 help
1454 This allows rt mutex semantics violations and rt mutex related
1455 deadlocks (lockups) to be detected and reported automatically.
1456
1457config DEBUG_SPINLOCK
1458 bool "Spinlock and rw-lock debugging: basic checks"
1459 depends on DEBUG_KERNEL
1460 select UNINLINE_SPIN_UNLOCK
1461 help
1462 Say Y here and build SMP to catch missing spinlock initialization
1463 and certain other kinds of spinlock errors commonly made. This is
1464 best used in conjunction with the NMI watchdog so that spinlock
1465 deadlocks are also debuggable.
1466
1467config DEBUG_MUTEXES
1468 bool "Mutex debugging: basic checks"
1469 depends on DEBUG_KERNEL && !PREEMPT_RT
1470 help
1471 This feature allows mutex semantics violations to be detected and
1472 reported.
1473
1474config DEBUG_WW_MUTEX_SLOWPATH
1475 bool "Wait/wound mutex debugging: Slowpath testing"
1476 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1477 select DEBUG_LOCK_ALLOC
1478 select DEBUG_SPINLOCK
1479 select DEBUG_MUTEXES if !PREEMPT_RT
1480 select DEBUG_RT_MUTEXES if PREEMPT_RT
1481 help
1482 This feature enables slowpath testing for w/w mutex users by
1483 injecting additional -EDEADLK wound/backoff cases. Together with
1484 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1485 will test all possible w/w mutex interface abuse with the
1486 exception of simply not acquiring all the required locks.
1487 Note that this feature can introduce significant overhead, so
1488 it really should not be enabled in a production or distro kernel,
1489 even a debug kernel. If you are a driver writer, enable it. If
1490 you are a distro, do not.
1491
1492config DEBUG_RWSEMS
1493 bool "RW Semaphore debugging: basic checks"
1494 depends on DEBUG_KERNEL && !PREEMPT_RT
1495 help
1496 This debugging feature allows mismatched rw semaphore locks
1497 and unlocks to be detected and reported.
1498
1499config DEBUG_LOCK_ALLOC
1500 bool "Lock debugging: detect incorrect freeing of live locks"
1501 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1502 select DEBUG_SPINLOCK
1503 select DEBUG_MUTEXES if !PREEMPT_RT
1504 select DEBUG_RT_MUTEXES if RT_MUTEXES
1505 select LOCKDEP
1506 help
1507 This feature will check whether any held lock (spinlock, rwlock,
1508 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1509 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1510 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1511 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1512 held during task exit.
1513
1514config LOCKDEP
1515 bool
1516 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1517 select STACKTRACE
1518 select KALLSYMS
1519 select KALLSYMS_ALL
1520
1521config LOCKDEP_SMALL
1522 bool
1523
1524config LOCKDEP_BITS
1525 int "Bitsize for MAX_LOCKDEP_ENTRIES"
1526 depends on LOCKDEP && !LOCKDEP_SMALL
1527 range 10 30
1528 default 15
1529 help
1530 Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message.
1531
1532config LOCKDEP_CHAINS_BITS
1533 int "Bitsize for MAX_LOCKDEP_CHAINS"
1534 depends on LOCKDEP && !LOCKDEP_SMALL
1535 range 10 21
1536 default 16
1537 help
1538 Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message.
1539
1540config LOCKDEP_STACK_TRACE_BITS
1541 int "Bitsize for MAX_STACK_TRACE_ENTRIES"
1542 depends on LOCKDEP && !LOCKDEP_SMALL
1543 range 10 30
1544 default 19
1545 help
1546 Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message.
1547
1548config LOCKDEP_STACK_TRACE_HASH_BITS
1549 int "Bitsize for STACK_TRACE_HASH_SIZE"
1550 depends on LOCKDEP && !LOCKDEP_SMALL
1551 range 10 30
1552 default 14
1553 help
1554 Try increasing this value if you need large STACK_TRACE_HASH_SIZE.
1555
1556config LOCKDEP_CIRCULAR_QUEUE_BITS
1557 int "Bitsize for elements in circular_queue struct"
1558 depends on LOCKDEP
1559 range 10 30
1560 default 12
1561 help
1562 Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure.
1563
1564config DEBUG_LOCKDEP
1565 bool "Lock dependency engine debugging"
1566 depends on DEBUG_KERNEL && LOCKDEP
1567 select DEBUG_IRQFLAGS
1568 help
1569 If you say Y here, the lock dependency engine will do
1570 additional runtime checks to debug itself, at the price
1571 of more runtime overhead.
1572
1573config DEBUG_ATOMIC_SLEEP
1574 bool "Sleep inside atomic section checking"
1575 select PREEMPT_COUNT
1576 depends on DEBUG_KERNEL
1577 depends on !ARCH_NO_PREEMPT
1578 help
1579 If you say Y here, various routines which may sleep will become very
1580 noisy if they are called inside atomic sections: when a spinlock is
1581 held, inside an rcu read side critical section, inside preempt disabled
1582 sections, inside an interrupt, etc...
1583
1584config DEBUG_LOCKING_API_SELFTESTS
1585 bool "Locking API boot-time self-tests"
1586 depends on DEBUG_KERNEL
1587 help
1588 Say Y here if you want the kernel to run a short self-test during
1589 bootup. The self-test checks whether common types of locking bugs
1590 are detected by debugging mechanisms or not. (if you disable
1591 lock debugging then those bugs won't be detected of course.)
1592 The following locking APIs are covered: spinlocks, rwlocks,
1593 mutexes and rwsems.
1594
1595config LOCK_TORTURE_TEST
1596 tristate "torture tests for locking"
1597 depends on DEBUG_KERNEL
1598 select TORTURE_TEST
1599 help
1600 This option provides a kernel module that runs torture tests
1601 on kernel locking primitives. The kernel module may be built
1602 after the fact on the running kernel to be tested, if desired.
1603
1604 Say Y here if you want kernel locking-primitive torture tests
1605 to be built into the kernel.
1606 Say M if you want these torture tests to build as a module.
1607 Say N if you are unsure.
1608
1609config WW_MUTEX_SELFTEST
1610 tristate "Wait/wound mutex selftests"
1611 help
1612 This option provides a kernel module that runs tests on the
1613 on the struct ww_mutex locking API.
1614
1615 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1616 with this test harness.
1617
1618 Say M if you want these self tests to build as a module.
1619 Say N if you are unsure.
1620
1621config SCF_TORTURE_TEST
1622 tristate "torture tests for smp_call_function*()"
1623 depends on DEBUG_KERNEL
1624 select TORTURE_TEST
1625 help
1626 This option provides a kernel module that runs torture tests
1627 on the smp_call_function() family of primitives. The kernel
1628 module may be built after the fact on the running kernel to
1629 be tested, if desired.
1630
1631config CSD_LOCK_WAIT_DEBUG
1632 bool "Debugging for csd_lock_wait(), called from smp_call_function*()"
1633 depends on DEBUG_KERNEL
1634 depends on SMP
1635 depends on 64BIT
1636 default n
1637 help
1638 This option enables debug prints when CPUs are slow to respond
1639 to the smp_call_function*() IPI wrappers. These debug prints
1640 include the IPI handler function currently executing (if any)
1641 and relevant stack traces.
1642
1643config CSD_LOCK_WAIT_DEBUG_DEFAULT
1644 bool "Default csd_lock_wait() debugging on at boot time"
1645 depends on CSD_LOCK_WAIT_DEBUG
1646 depends on 64BIT
1647 default n
1648 help
1649 This option causes the csdlock_debug= kernel boot parameter to
1650 default to 1 (basic debugging) instead of 0 (no debugging).
1651
1652endmenu # lock debugging
1653
1654config TRACE_IRQFLAGS
1655 depends on TRACE_IRQFLAGS_SUPPORT
1656 bool
1657 help
1658 Enables hooks to interrupt enabling and disabling for
1659 either tracing or lock debugging.
1660
1661config TRACE_IRQFLAGS_NMI
1662 def_bool y
1663 depends on TRACE_IRQFLAGS
1664 depends on TRACE_IRQFLAGS_NMI_SUPPORT
1665
1666config NMI_CHECK_CPU
1667 bool "Debugging for CPUs failing to respond to backtrace requests"
1668 depends on DEBUG_KERNEL
1669 depends on X86
1670 default n
1671 help
1672 Enables debug prints when a CPU fails to respond to a given
1673 backtrace NMI. These prints provide some reasons why a CPU
1674 might legitimately be failing to respond, for example, if it
1675 is offline of if ignore_nmis is set.
1676
1677config DEBUG_IRQFLAGS
1678 bool "Debug IRQ flag manipulation"
1679 help
1680 Enables checks for potentially unsafe enabling or disabling of
1681 interrupts, such as calling raw_local_irq_restore() when interrupts
1682 are enabled.
1683
1684config STACKTRACE
1685 bool "Stack backtrace support"
1686 depends on STACKTRACE_SUPPORT
1687 help
1688 This option causes the kernel to create a /proc/pid/stack for
1689 every process, showing its current stack trace.
1690 It is also used by various kernel debugging features that require
1691 stack trace generation.
1692
1693config WARN_ALL_UNSEEDED_RANDOM
1694 bool "Warn for all uses of unseeded randomness"
1695 default n
1696 help
1697 Some parts of the kernel contain bugs relating to their use of
1698 cryptographically secure random numbers before it's actually possible
1699 to generate those numbers securely. This setting ensures that these
1700 flaws don't go unnoticed, by enabling a message, should this ever
1701 occur. This will allow people with obscure setups to know when things
1702 are going wrong, so that they might contact developers about fixing
1703 it.
1704
1705 Unfortunately, on some models of some architectures getting
1706 a fully seeded CRNG is extremely difficult, and so this can
1707 result in dmesg getting spammed for a surprisingly long
1708 time. This is really bad from a security perspective, and
1709 so architecture maintainers really need to do what they can
1710 to get the CRNG seeded sooner after the system is booted.
1711 However, since users cannot do anything actionable to
1712 address this, by default this option is disabled.
1713
1714 Say Y here if you want to receive warnings for all uses of
1715 unseeded randomness. This will be of use primarily for
1716 those developers interested in improving the security of
1717 Linux kernels running on their architecture (or
1718 subarchitecture).
1719
1720config DEBUG_KOBJECT
1721 bool "kobject debugging"
1722 depends on DEBUG_KERNEL
1723 help
1724 If you say Y here, some extra kobject debugging messages will be sent
1725 to the syslog.
1726
1727config DEBUG_KOBJECT_RELEASE
1728 bool "kobject release debugging"
1729 depends on DEBUG_OBJECTS_TIMERS
1730 help
1731 kobjects are reference counted objects. This means that their
1732 last reference count put is not predictable, and the kobject can
1733 live on past the point at which a driver decides to drop its
1734 initial reference to the kobject gained on allocation. An
1735 example of this would be a struct device which has just been
1736 unregistered.
1737
1738 However, some buggy drivers assume that after such an operation,
1739 the memory backing the kobject can be immediately freed. This
1740 goes completely against the principles of a refcounted object.
1741
1742 If you say Y here, the kernel will delay the release of kobjects
1743 on the last reference count to improve the visibility of this
1744 kind of kobject release bug.
1745
1746config HAVE_DEBUG_BUGVERBOSE
1747 bool
1748
1749menu "Debug kernel data structures"
1750
1751config DEBUG_LIST
1752 bool "Debug linked list manipulation"
1753 depends on DEBUG_KERNEL
1754 select LIST_HARDENED
1755 help
1756 Enable this to turn on extended checks in the linked-list walking
1757 routines.
1758
1759 This option trades better quality error reports for performance, and
1760 is more suitable for kernel debugging. If you care about performance,
1761 you should only enable CONFIG_LIST_HARDENED instead.
1762
1763 If unsure, say N.
1764
1765config DEBUG_PLIST
1766 bool "Debug priority linked list manipulation"
1767 depends on DEBUG_KERNEL
1768 help
1769 Enable this to turn on extended checks in the priority-ordered
1770 linked-list (plist) walking routines. This checks the entire
1771 list multiple times during each manipulation.
1772
1773 If unsure, say N.
1774
1775config DEBUG_SG
1776 bool "Debug SG table operations"
1777 depends on DEBUG_KERNEL
1778 help
1779 Enable this to turn on checks on scatter-gather tables. This can
1780 help find problems with drivers that do not properly initialize
1781 their sg tables.
1782
1783 If unsure, say N.
1784
1785config DEBUG_NOTIFIERS
1786 bool "Debug notifier call chains"
1787 depends on DEBUG_KERNEL
1788 help
1789 Enable this to turn on sanity checking for notifier call chains.
1790 This is most useful for kernel developers to make sure that
1791 modules properly unregister themselves from notifier chains.
1792 This is a relatively cheap check but if you care about maximum
1793 performance, say N.
1794
1795config DEBUG_CLOSURES
1796 bool "Debug closures (bcache async widgits)"
1797 depends on CLOSURES
1798 select DEBUG_FS
1799 help
1800 Keeps all active closures in a linked list and provides a debugfs
1801 interface to list them, which makes it possible to see asynchronous
1802 operations that get stuck.
1803
1804config DEBUG_MAPLE_TREE
1805 bool "Debug maple trees"
1806 depends on DEBUG_KERNEL
1807 help
1808 Enable maple tree debugging information and extra validations.
1809
1810 If unsure, say N.
1811
1812endmenu
1813
1814source "kernel/rcu/Kconfig.debug"
1815
1816config DEBUG_WQ_FORCE_RR_CPU
1817 bool "Force round-robin CPU selection for unbound work items"
1818 depends on DEBUG_KERNEL
1819 default n
1820 help
1821 Workqueue used to implicitly guarantee that work items queued
1822 without explicit CPU specified are put on the local CPU. This
1823 guarantee is no longer true and while local CPU is still
1824 preferred work items may be put on foreign CPUs. Kernel
1825 parameter "workqueue.debug_force_rr_cpu" is added to force
1826 round-robin CPU selection to flush out usages which depend on the
1827 now broken guarantee. This config option enables the debug
1828 feature by default. When enabled, memory and cache locality will
1829 be impacted.
1830
1831config CPU_HOTPLUG_STATE_CONTROL
1832 bool "Enable CPU hotplug state control"
1833 depends on DEBUG_KERNEL
1834 depends on HOTPLUG_CPU
1835 default n
1836 help
1837 Allows to write steps between "offline" and "online" to the CPUs
1838 sysfs target file so states can be stepped granular. This is a debug
1839 option for now as the hotplug machinery cannot be stopped and
1840 restarted at arbitrary points yet.
1841
1842 Say N if your are unsure.
1843
1844config LATENCYTOP
1845 bool "Latency measuring infrastructure"
1846 depends on DEBUG_KERNEL
1847 depends on STACKTRACE_SUPPORT
1848 depends on PROC_FS
1849 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
1850 select KALLSYMS
1851 select KALLSYMS_ALL
1852 select STACKTRACE
1853 select SCHEDSTATS
1854 help
1855 Enable this option if you want to use the LatencyTOP tool
1856 to find out which userspace is blocking on what kernel operations.
1857
1858config DEBUG_CGROUP_REF
1859 bool "Disable inlining of cgroup css reference count functions"
1860 depends on DEBUG_KERNEL
1861 depends on CGROUPS
1862 depends on KPROBES
1863 default n
1864 help
1865 Force cgroup css reference count functions to not be inlined so
1866 that they can be kprobed for debugging.
1867
1868source "kernel/trace/Kconfig"
1869
1870config PROVIDE_OHCI1394_DMA_INIT
1871 bool "Remote debugging over FireWire early on boot"
1872 depends on PCI && X86
1873 help
1874 If you want to debug problems which hang or crash the kernel early
1875 on boot and the crashing machine has a FireWire port, you can use
1876 this feature to remotely access the memory of the crashed machine
1877 over FireWire. This employs remote DMA as part of the OHCI1394
1878 specification which is now the standard for FireWire controllers.
1879
1880 With remote DMA, you can monitor the printk buffer remotely using
1881 firescope and access all memory below 4GB using fireproxy from gdb.
1882 Even controlling a kernel debugger is possible using remote DMA.
1883
1884 Usage:
1885
1886 If ohci1394_dma=early is used as boot parameter, it will initialize
1887 all OHCI1394 controllers which are found in the PCI config space.
1888
1889 As all changes to the FireWire bus such as enabling and disabling
1890 devices cause a bus reset and thereby disable remote DMA for all
1891 devices, be sure to have the cable plugged and FireWire enabled on
1892 the debugging host before booting the debug target for debugging.
1893
1894 This code (~1k) is freed after boot. By then, the firewire stack
1895 in charge of the OHCI-1394 controllers should be used instead.
1896
1897 See Documentation/core-api/debugging-via-ohci1394.rst for more information.
1898
1899source "samples/Kconfig"
1900
1901config ARCH_HAS_DEVMEM_IS_ALLOWED
1902 bool
1903
1904config STRICT_DEVMEM
1905 bool "Filter access to /dev/mem"
1906 depends on MMU && DEVMEM
1907 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED
1908 default y if PPC || X86 || ARM64
1909 help
1910 If this option is disabled, you allow userspace (root) access to all
1911 of memory, including kernel and userspace memory. Accidental
1912 access to this is obviously disastrous, but specific access can
1913 be used by people debugging the kernel. Note that with PAT support
1914 enabled, even in this case there are restrictions on /dev/mem
1915 use due to the cache aliasing requirements.
1916
1917 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
1918 file only allows userspace access to PCI space and the BIOS code and
1919 data regions. This is sufficient for dosemu and X and all common
1920 users of /dev/mem.
1921
1922 If in doubt, say Y.
1923
1924config IO_STRICT_DEVMEM
1925 bool "Filter I/O access to /dev/mem"
1926 depends on STRICT_DEVMEM
1927 help
1928 If this option is disabled, you allow userspace (root) access to all
1929 io-memory regardless of whether a driver is actively using that
1930 range. Accidental access to this is obviously disastrous, but
1931 specific access can be used by people debugging kernel drivers.
1932
1933 If this option is switched on, the /dev/mem file only allows
1934 userspace access to *idle* io-memory ranges (see /proc/iomem) This
1935 may break traditional users of /dev/mem (dosemu, legacy X, etc...)
1936 if the driver using a given range cannot be disabled.
1937
1938 If in doubt, say Y.
1939
1940menu "$(SRCARCH) Debugging"
1941
1942source "arch/$(SRCARCH)/Kconfig.debug"
1943
1944endmenu
1945
1946menu "Kernel Testing and Coverage"
1947
1948source "lib/kunit/Kconfig"
1949
1950config NOTIFIER_ERROR_INJECTION
1951 tristate "Notifier error injection"
1952 depends on DEBUG_KERNEL
1953 select DEBUG_FS
1954 help
1955 This option provides the ability to inject artificial errors to
1956 specified notifier chain callbacks. It is useful to test the error
1957 handling of notifier call chain failures.
1958
1959 Say N if unsure.
1960
1961config PM_NOTIFIER_ERROR_INJECT
1962 tristate "PM notifier error injection module"
1963 depends on PM && NOTIFIER_ERROR_INJECTION
1964 default m if PM_DEBUG
1965 help
1966 This option provides the ability to inject artificial errors to
1967 PM notifier chain callbacks. It is controlled through debugfs
1968 interface /sys/kernel/debug/notifier-error-inject/pm
1969
1970 If the notifier call chain should be failed with some events
1971 notified, write the error code to "actions/<notifier event>/error".
1972
1973 Example: Inject PM suspend error (-12 = -ENOMEM)
1974
1975 # cd /sys/kernel/debug/notifier-error-inject/pm/
1976 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1977 # echo mem > /sys/power/state
1978 bash: echo: write error: Cannot allocate memory
1979
1980 To compile this code as a module, choose M here: the module will
1981 be called pm-notifier-error-inject.
1982
1983 If unsure, say N.
1984
1985config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1986 tristate "OF reconfig notifier error injection module"
1987 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1988 help
1989 This option provides the ability to inject artificial errors to
1990 OF reconfig notifier chain callbacks. It is controlled
1991 through debugfs interface under
1992 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1993
1994 If the notifier call chain should be failed with some events
1995 notified, write the error code to "actions/<notifier event>/error".
1996
1997 To compile this code as a module, choose M here: the module will
1998 be called of-reconfig-notifier-error-inject.
1999
2000 If unsure, say N.
2001
2002config NETDEV_NOTIFIER_ERROR_INJECT
2003 tristate "Netdev notifier error injection module"
2004 depends on NET && NOTIFIER_ERROR_INJECTION
2005 help
2006 This option provides the ability to inject artificial errors to
2007 netdevice notifier chain callbacks. It is controlled through debugfs
2008 interface /sys/kernel/debug/notifier-error-inject/netdev
2009
2010 If the notifier call chain should be failed with some events
2011 notified, write the error code to "actions/<notifier event>/error".
2012
2013 Example: Inject netdevice mtu change error (-22 = -EINVAL)
2014
2015 # cd /sys/kernel/debug/notifier-error-inject/netdev
2016 # echo -22 > actions/NETDEV_CHANGEMTU/error
2017 # ip link set eth0 mtu 1024
2018 RTNETLINK answers: Invalid argument
2019
2020 To compile this code as a module, choose M here: the module will
2021 be called netdev-notifier-error-inject.
2022
2023 If unsure, say N.
2024
2025config FUNCTION_ERROR_INJECTION
2026 bool "Fault-injections of functions"
2027 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
2028 help
2029 Add fault injections into various functions that are annotated with
2030 ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return
2031 value of these functions. This is useful to test error paths of code.
2032
2033 If unsure, say N
2034
2035config FAULT_INJECTION
2036 bool "Fault-injection framework"
2037 depends on DEBUG_KERNEL
2038 help
2039 Provide fault-injection framework.
2040 For more details, see Documentation/fault-injection/.
2041
2042config FAILSLAB
2043 bool "Fault-injection capability for kmalloc"
2044 depends on FAULT_INJECTION
2045 help
2046 Provide fault-injection capability for kmalloc.
2047
2048config FAIL_PAGE_ALLOC
2049 bool "Fault-injection capability for alloc_pages()"
2050 depends on FAULT_INJECTION
2051 help
2052 Provide fault-injection capability for alloc_pages().
2053
2054config FAULT_INJECTION_USERCOPY
2055 bool "Fault injection capability for usercopy functions"
2056 depends on FAULT_INJECTION
2057 help
2058 Provides fault-injection capability to inject failures
2059 in usercopy functions (copy_from_user(), get_user(), ...).
2060
2061config FAIL_MAKE_REQUEST
2062 bool "Fault-injection capability for disk IO"
2063 depends on FAULT_INJECTION && BLOCK
2064 help
2065 Provide fault-injection capability for disk IO.
2066
2067config FAIL_IO_TIMEOUT
2068 bool "Fault-injection capability for faking disk interrupts"
2069 depends on FAULT_INJECTION && BLOCK
2070 help
2071 Provide fault-injection capability on end IO handling. This
2072 will make the block layer "forget" an interrupt as configured,
2073 thus exercising the error handling.
2074
2075 Only works with drivers that use the generic timeout handling,
2076 for others it won't do anything.
2077
2078config FAIL_FUTEX
2079 bool "Fault-injection capability for futexes"
2080 select DEBUG_FS
2081 depends on FAULT_INJECTION && FUTEX
2082 help
2083 Provide fault-injection capability for futexes.
2084
2085config FAULT_INJECTION_DEBUG_FS
2086 bool "Debugfs entries for fault-injection capabilities"
2087 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
2088 help
2089 Enable configuration of fault-injection capabilities via debugfs.
2090
2091config FAIL_FUNCTION
2092 bool "Fault-injection capability for functions"
2093 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
2094 help
2095 Provide function-based fault-injection capability.
2096 This will allow you to override a specific function with a return
2097 with given return value. As a result, function caller will see
2098 an error value and have to handle it. This is useful to test the
2099 error handling in various subsystems.
2100
2101config FAIL_MMC_REQUEST
2102 bool "Fault-injection capability for MMC IO"
2103 depends on FAULT_INJECTION_DEBUG_FS && MMC
2104 help
2105 Provide fault-injection capability for MMC IO.
2106 This will make the mmc core return data errors. This is
2107 useful to test the error handling in the mmc block device
2108 and to test how the mmc host driver handles retries from
2109 the block device.
2110
2111config FAIL_SUNRPC
2112 bool "Fault-injection capability for SunRPC"
2113 depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG
2114 help
2115 Provide fault-injection capability for SunRPC and
2116 its consumers.
2117
2118config FAULT_INJECTION_CONFIGFS
2119 bool "Configfs interface for fault-injection capabilities"
2120 depends on FAULT_INJECTION
2121 select CONFIGFS_FS
2122 help
2123 This option allows configfs-based drivers to dynamically configure
2124 fault-injection via configfs. Each parameter for driver-specific
2125 fault-injection can be made visible as a configfs attribute in a
2126 configfs group.
2127
2128
2129config FAULT_INJECTION_STACKTRACE_FILTER
2130 bool "stacktrace filter for fault-injection capabilities"
2131 depends on FAULT_INJECTION
2132 depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT
2133 select STACKTRACE
2134 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
2135 help
2136 Provide stacktrace filter for fault-injection capabilities
2137
2138config ARCH_HAS_KCOV
2139 bool
2140 help
2141 An architecture should select this when it can successfully
2142 build and run with CONFIG_KCOV. This typically requires
2143 disabling instrumentation for some early boot code.
2144
2145config CC_HAS_SANCOV_TRACE_PC
2146 def_bool $(cc-option,-fsanitize-coverage=trace-pc)
2147
2148
2149config KCOV
2150 bool "Code coverage for fuzzing"
2151 depends on ARCH_HAS_KCOV
2152 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
2153 depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \
2154 GCC_VERSION >= 120000 || CC_IS_CLANG
2155 select DEBUG_FS
2156 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
2157 select OBJTOOL if HAVE_NOINSTR_HACK
2158 help
2159 KCOV exposes kernel code coverage information in a form suitable
2160 for coverage-guided fuzzing (randomized testing).
2161
2162 For more details, see Documentation/dev-tools/kcov.rst.
2163
2164config KCOV_ENABLE_COMPARISONS
2165 bool "Enable comparison operands collection by KCOV"
2166 depends on KCOV
2167 depends on $(cc-option,-fsanitize-coverage=trace-cmp)
2168 help
2169 KCOV also exposes operands of every comparison in the instrumented
2170 code along with operand sizes and PCs of the comparison instructions.
2171 These operands can be used by fuzzing engines to improve the quality
2172 of fuzzing coverage.
2173
2174config KCOV_INSTRUMENT_ALL
2175 bool "Instrument all code by default"
2176 depends on KCOV
2177 default y
2178 help
2179 If you are doing generic system call fuzzing (like e.g. syzkaller),
2180 then you will want to instrument the whole kernel and you should
2181 say y here. If you are doing more targeted fuzzing (like e.g.
2182 filesystem fuzzing with AFL) then you will want to enable coverage
2183 for more specific subsets of files, and should say n here.
2184
2185config KCOV_IRQ_AREA_SIZE
2186 hex "Size of interrupt coverage collection area in words"
2187 depends on KCOV
2188 default 0x40000
2189 help
2190 KCOV uses preallocated per-cpu areas to collect coverage from
2191 soft interrupts. This specifies the size of those areas in the
2192 number of unsigned long words.
2193
2194config KCOV_SELFTEST
2195 bool "Perform short selftests on boot"
2196 depends on KCOV
2197 help
2198 Run short KCOV coverage collection selftests on boot.
2199 On test failure, causes the kernel to panic. Recommended to be
2200 enabled, ensuring critical functionality works as intended.
2201
2202menuconfig RUNTIME_TESTING_MENU
2203 bool "Runtime Testing"
2204 default y
2205
2206if RUNTIME_TESTING_MENU
2207
2208config TEST_DHRY
2209 tristate "Dhrystone benchmark test"
2210 help
2211 Enable this to include the Dhrystone 2.1 benchmark. This test
2212 calculates the number of Dhrystones per second, and the number of
2213 DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided
2214 by 1757 (the number of Dhrystones per second obtained on the VAX
2215 11/780, nominally a 1 MIPS machine).
2216
2217 To run the benchmark, it needs to be enabled explicitly, either from
2218 the kernel command line (when built-in), or from userspace (when
2219 built-in or modular).
2220
2221 Run once during kernel boot:
2222
2223 test_dhry.run
2224
2225 Set number of iterations from kernel command line:
2226
2227 test_dhry.iterations=<n>
2228
2229 Set number of iterations from userspace:
2230
2231 echo <n> > /sys/module/test_dhry/parameters/iterations
2232
2233 Trigger manual run from userspace:
2234
2235 echo y > /sys/module/test_dhry/parameters/run
2236
2237 If the number of iterations is <= 0, the test will devise a suitable
2238 number of iterations (test runs for at least 2s) automatically.
2239 This process takes ca. 4s.
2240
2241 If unsure, say N.
2242
2243config LKDTM
2244 tristate "Linux Kernel Dump Test Tool Module"
2245 depends on DEBUG_FS
2246 help
2247 This module enables testing of the different dumping mechanisms by
2248 inducing system failures at predefined crash points.
2249 If you don't need it: say N
2250 Choose M here to compile this code as a module. The module will be
2251 called lkdtm.
2252
2253 Documentation on how to use the module can be found in
2254 Documentation/fault-injection/provoke-crashes.rst
2255
2256config CPUMASK_KUNIT_TEST
2257 tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS
2258 depends on KUNIT
2259 default KUNIT_ALL_TESTS
2260 help
2261 Enable to turn on cpumask tests, running at boot or module load time.
2262
2263 For more information on KUnit and unit tests in general, please refer
2264 to the KUnit documentation in Documentation/dev-tools/kunit/.
2265
2266 If unsure, say N.
2267
2268config TEST_LIST_SORT
2269 tristate "Linked list sorting test" if !KUNIT_ALL_TESTS
2270 depends on KUNIT
2271 default KUNIT_ALL_TESTS
2272 help
2273 Enable this to turn on 'list_sort()' function test. This test is
2274 executed only once during system boot (so affects only boot time),
2275 or at module load time.
2276
2277 If unsure, say N.
2278
2279config TEST_MIN_HEAP
2280 tristate "Min heap test"
2281 depends on DEBUG_KERNEL || m
2282 help
2283 Enable this to turn on min heap function tests. This test is
2284 executed only once during system boot (so affects only boot time),
2285 or at module load time.
2286
2287 If unsure, say N.
2288
2289config TEST_SORT
2290 tristate "Array-based sort test" if !KUNIT_ALL_TESTS
2291 depends on KUNIT
2292 default KUNIT_ALL_TESTS
2293 help
2294 This option enables the self-test function of 'sort()' at boot,
2295 or at module load time.
2296
2297 If unsure, say N.
2298
2299config TEST_DIV64
2300 tristate "64bit/32bit division and modulo test"
2301 depends on DEBUG_KERNEL || m
2302 help
2303 Enable this to turn on 'do_div()' function test. This test is
2304 executed only once during system boot (so affects only boot time),
2305 or at module load time.
2306
2307 If unsure, say N.
2308
2309config TEST_MULDIV64
2310 tristate "mul_u64_u64_div_u64() test"
2311 depends on DEBUG_KERNEL || m
2312 help
2313 Enable this to turn on 'mul_u64_u64_div_u64()' function test.
2314 This test is executed only once during system boot (so affects
2315 only boot time), or at module load time.
2316
2317 If unsure, say N.
2318
2319config TEST_IOV_ITER
2320 tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS
2321 depends on KUNIT
2322 depends on MMU
2323 default KUNIT_ALL_TESTS
2324 help
2325 Enable this to turn on testing of the operation of the I/O iterator
2326 (iov_iter). This test is executed only once during system boot (so
2327 affects only boot time), or at module load time.
2328
2329 If unsure, say N.
2330
2331config KPROBES_SANITY_TEST
2332 tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS
2333 depends on DEBUG_KERNEL
2334 depends on KPROBES
2335 depends on KUNIT
2336 select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
2337 default KUNIT_ALL_TESTS
2338 help
2339 This option provides for testing basic kprobes functionality on
2340 boot. Samples of kprobe and kretprobe are inserted and
2341 verified for functionality.
2342
2343 Say N if you are unsure.
2344
2345config FPROBE_SANITY_TEST
2346 bool "Self test for fprobe"
2347 depends on DEBUG_KERNEL
2348 depends on FPROBE
2349 depends on KUNIT=y
2350 help
2351 This option will enable testing the fprobe when the system boot.
2352 A series of tests are made to verify that the fprobe is functioning
2353 properly.
2354
2355 Say N if you are unsure.
2356
2357config BACKTRACE_SELF_TEST
2358 tristate "Self test for the backtrace code"
2359 depends on DEBUG_KERNEL
2360 help
2361 This option provides a kernel module that can be used to test
2362 the kernel stack backtrace code. This option is not useful
2363 for distributions or general kernels, but only for kernel
2364 developers working on architecture code.
2365
2366 Note that if you want to also test saved backtraces, you will
2367 have to enable STACKTRACE as well.
2368
2369 Say N if you are unsure.
2370
2371config TEST_REF_TRACKER
2372 tristate "Self test for reference tracker"
2373 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
2374 select REF_TRACKER
2375 help
2376 This option provides a kernel module performing tests
2377 using reference tracker infrastructure.
2378
2379 Say N if you are unsure.
2380
2381config RBTREE_TEST
2382 tristate "Red-Black tree test"
2383 depends on DEBUG_KERNEL
2384 help
2385 A benchmark measuring the performance of the rbtree library.
2386 Also includes rbtree invariant checks.
2387
2388config REED_SOLOMON_TEST
2389 tristate "Reed-Solomon library test"
2390 depends on DEBUG_KERNEL || m
2391 select REED_SOLOMON
2392 select REED_SOLOMON_ENC16
2393 select REED_SOLOMON_DEC16
2394 help
2395 This option enables the self-test function of rslib at boot,
2396 or at module load time.
2397
2398 If unsure, say N.
2399
2400config INTERVAL_TREE_TEST
2401 tristate "Interval tree test"
2402 depends on DEBUG_KERNEL
2403 select INTERVAL_TREE
2404 help
2405 A benchmark measuring the performance of the interval tree library
2406
2407config PERCPU_TEST
2408 tristate "Per cpu operations test"
2409 depends on m && DEBUG_KERNEL
2410 help
2411 Enable this option to build test module which validates per-cpu
2412 operations.
2413
2414 If unsure, say N.
2415
2416config ATOMIC64_SELFTEST
2417 tristate "Perform an atomic64_t self-test"
2418 help
2419 Enable this option to test the atomic64_t functions at boot or
2420 at module load time.
2421
2422 If unsure, say N.
2423
2424config ASYNC_RAID6_TEST
2425 tristate "Self test for hardware accelerated raid6 recovery"
2426 depends on ASYNC_RAID6_RECOV
2427 select ASYNC_MEMCPY
2428 help
2429 This is a one-shot self test that permutes through the
2430 recovery of all the possible two disk failure scenarios for a
2431 N-disk array. Recovery is performed with the asynchronous
2432 raid6 recovery routines, and will optionally use an offload
2433 engine if one is available.
2434
2435 If unsure, say N.
2436
2437config TEST_HEXDUMP
2438 tristate "Test functions located in the hexdump module at runtime"
2439
2440config STRING_KUNIT_TEST
2441 tristate "KUnit test string functions at runtime" if !KUNIT_ALL_TESTS
2442 depends on KUNIT
2443 default KUNIT_ALL_TESTS
2444
2445config STRING_HELPERS_KUNIT_TEST
2446 tristate "KUnit test string helpers at runtime" if !KUNIT_ALL_TESTS
2447 depends on KUNIT
2448 default KUNIT_ALL_TESTS
2449
2450config TEST_KSTRTOX
2451 tristate "Test kstrto*() family of functions at runtime"
2452
2453config TEST_PRINTF
2454 tristate "Test printf() family of functions at runtime"
2455
2456config TEST_SCANF
2457 tristate "Test scanf() family of functions at runtime"
2458
2459config TEST_BITMAP
2460 tristate "Test bitmap_*() family of functions at runtime"
2461 help
2462 Enable this option to test the bitmap functions at boot.
2463
2464 If unsure, say N.
2465
2466config TEST_UUID
2467 tristate "Test functions located in the uuid module at runtime"
2468
2469config TEST_XARRAY
2470 tristate "Test the XArray code at runtime"
2471
2472config TEST_MAPLE_TREE
2473 tristate "Test the Maple Tree code at runtime or module load"
2474 help
2475 Enable this option to test the maple tree code functions at boot, or
2476 when the module is loaded. Enable "Debug Maple Trees" will enable
2477 more verbose output on failures.
2478
2479 If unsure, say N.
2480
2481config TEST_RHASHTABLE
2482 tristate "Perform selftest on resizable hash table"
2483 help
2484 Enable this option to test the rhashtable functions at boot.
2485
2486 If unsure, say N.
2487
2488config TEST_IDA
2489 tristate "Perform selftest on IDA functions"
2490
2491config TEST_PARMAN
2492 tristate "Perform selftest on priority array manager"
2493 depends on PARMAN
2494 help
2495 Enable this option to test priority array manager on boot
2496 (or module load).
2497
2498 If unsure, say N.
2499
2500config TEST_IRQ_TIMINGS
2501 bool "IRQ timings selftest"
2502 depends on IRQ_TIMINGS
2503 help
2504 Enable this option to test the irq timings code on boot.
2505
2506 If unsure, say N.
2507
2508config TEST_LKM
2509 tristate "Test module loading with 'hello world' module"
2510 depends on m
2511 help
2512 This builds the "test_module" module that emits "Hello, world"
2513 on printk when loaded. It is designed to be used for basic
2514 evaluation of the module loading subsystem (for example when
2515 validating module verification). It lacks any extra dependencies,
2516 and will not normally be loaded by the system unless explicitly
2517 requested by name.
2518
2519 If unsure, say N.
2520
2521config TEST_BITOPS
2522 tristate "Test module for compilation of bitops operations"
2523 help
2524 This builds the "test_bitops" module that is much like the
2525 TEST_LKM module except that it does a basic exercise of the
2526 set/clear_bit macros and get_count_order/long to make sure there are
2527 no compiler warnings from C=1 sparse checker or -Wextra
2528 compilations. It has no dependencies and doesn't run or load unless
2529 explicitly requested by name. for example: modprobe test_bitops.
2530
2531 If unsure, say N.
2532
2533config TEST_VMALLOC
2534 tristate "Test module for stress/performance analysis of vmalloc allocator"
2535 default n
2536 depends on MMU
2537 depends on m
2538 help
2539 This builds the "test_vmalloc" module that should be used for
2540 stress and performance analysis. So, any new change for vmalloc
2541 subsystem can be evaluated from performance and stability point
2542 of view.
2543
2544 If unsure, say N.
2545
2546config TEST_BPF
2547 tristate "Test BPF filter functionality"
2548 depends on m && NET
2549 help
2550 This builds the "test_bpf" module that runs various test vectors
2551 against the BPF interpreter or BPF JIT compiler depending on the
2552 current setting. This is in particular useful for BPF JIT compiler
2553 development, but also to run regression tests against changes in
2554 the interpreter code. It also enables test stubs for eBPF maps and
2555 verifier used by user space verifier testsuite.
2556
2557 If unsure, say N.
2558
2559config TEST_BLACKHOLE_DEV
2560 tristate "Test blackhole netdev functionality"
2561 depends on m && NET
2562 help
2563 This builds the "test_blackhole_dev" module that validates the
2564 data path through this blackhole netdev.
2565
2566 If unsure, say N.
2567
2568config FIND_BIT_BENCHMARK
2569 tristate "Test find_bit functions"
2570 help
2571 This builds the "test_find_bit" module that measure find_*_bit()
2572 functions performance.
2573
2574 If unsure, say N.
2575
2576config TEST_FIRMWARE
2577 tristate "Test firmware loading via userspace interface"
2578 depends on FW_LOADER
2579 help
2580 This builds the "test_firmware" module that creates a userspace
2581 interface for testing firmware loading. This can be used to
2582 control the triggering of firmware loading without needing an
2583 actual firmware-using device. The contents can be rechecked by
2584 userspace.
2585
2586 If unsure, say N.
2587
2588config TEST_SYSCTL
2589 tristate "sysctl test driver"
2590 depends on PROC_SYSCTL
2591 help
2592 This builds the "test_sysctl" module. This driver enables to test the
2593 proc sysctl interfaces available to drivers safely without affecting
2594 production knobs which might alter system functionality.
2595
2596 If unsure, say N.
2597
2598config BITFIELD_KUNIT
2599 tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS
2600 depends on KUNIT
2601 default KUNIT_ALL_TESTS
2602 help
2603 Enable this option to test the bitfield functions at boot.
2604
2605 KUnit tests run during boot and output the results to the debug log
2606 in TAP format (http://testanything.org/). Only useful for kernel devs
2607 running the KUnit test harness, and not intended for inclusion into a
2608 production build.
2609
2610 For more information on KUnit and unit tests in general please refer
2611 to the KUnit documentation in Documentation/dev-tools/kunit/.
2612
2613 If unsure, say N.
2614
2615config CHECKSUM_KUNIT
2616 tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS
2617 depends on KUNIT
2618 default KUNIT_ALL_TESTS
2619 help
2620 Enable this option to test the checksum functions at boot.
2621
2622 KUnit tests run during boot and output the results to the debug log
2623 in TAP format (http://testanything.org/). Only useful for kernel devs
2624 running the KUnit test harness, and not intended for inclusion into a
2625 production build.
2626
2627 For more information on KUnit and unit tests in general please refer
2628 to the KUnit documentation in Documentation/dev-tools/kunit/.
2629
2630 If unsure, say N.
2631
2632config HASH_KUNIT_TEST
2633 tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS
2634 depends on KUNIT
2635 default KUNIT_ALL_TESTS
2636 help
2637 Enable this option to test the kernel's string (<linux/stringhash.h>), and
2638 integer (<linux/hash.h>) hash functions on boot.
2639
2640 KUnit tests run during boot and output the results to the debug log
2641 in TAP format (https://testanything.org/). Only useful for kernel devs
2642 running the KUnit test harness, and not intended for inclusion into a
2643 production build.
2644
2645 For more information on KUnit and unit tests in general please refer
2646 to the KUnit documentation in Documentation/dev-tools/kunit/.
2647
2648 This is intended to help people writing architecture-specific
2649 optimized versions. If unsure, say N.
2650
2651config RESOURCE_KUNIT_TEST
2652 tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS
2653 depends on KUNIT
2654 default KUNIT_ALL_TESTS
2655 select GET_FREE_REGION
2656 help
2657 This builds the resource API unit test.
2658 Tests the logic of API provided by resource.c and ioport.h.
2659 For more information on KUnit and unit tests in general please refer
2660 to the KUnit documentation in Documentation/dev-tools/kunit/.
2661
2662 If unsure, say N.
2663
2664config SYSCTL_KUNIT_TEST
2665 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS
2666 depends on KUNIT
2667 default KUNIT_ALL_TESTS
2668 help
2669 This builds the proc sysctl unit test, which runs on boot.
2670 Tests the API contract and implementation correctness of sysctl.
2671 For more information on KUnit and unit tests in general please refer
2672 to the KUnit documentation in Documentation/dev-tools/kunit/.
2673
2674 If unsure, say N.
2675
2676config LIST_KUNIT_TEST
2677 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS
2678 depends on KUNIT
2679 default KUNIT_ALL_TESTS
2680 help
2681 This builds the linked list KUnit test suite.
2682 It tests that the API and basic functionality of the list_head type
2683 and associated macros.
2684
2685 KUnit tests run during boot and output the results to the debug log
2686 in TAP format (https://testanything.org/). Only useful for kernel devs
2687 running the KUnit test harness, and not intended for inclusion into a
2688 production build.
2689
2690 For more information on KUnit and unit tests in general please refer
2691 to the KUnit documentation in Documentation/dev-tools/kunit/.
2692
2693 If unsure, say N.
2694
2695config HASHTABLE_KUNIT_TEST
2696 tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS
2697 depends on KUNIT
2698 default KUNIT_ALL_TESTS
2699 help
2700 This builds the hashtable KUnit test suite.
2701 It tests the basic functionality of the API defined in
2702 include/linux/hashtable.h. For more information on KUnit and
2703 unit tests in general please refer to the KUnit documentation
2704 in Documentation/dev-tools/kunit/.
2705
2706 If unsure, say N.
2707
2708config LINEAR_RANGES_TEST
2709 tristate "KUnit test for linear_ranges"
2710 depends on KUNIT
2711 select LINEAR_RANGES
2712 help
2713 This builds the linear_ranges unit test, which runs on boot.
2714 Tests the linear_ranges logic correctness.
2715 For more information on KUnit and unit tests in general please refer
2716 to the KUnit documentation in Documentation/dev-tools/kunit/.
2717
2718 If unsure, say N.
2719
2720config CMDLINE_KUNIT_TEST
2721 tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS
2722 depends on KUNIT
2723 default KUNIT_ALL_TESTS
2724 help
2725 This builds the cmdline API unit test.
2726 Tests the logic of API provided by cmdline.c.
2727 For more information on KUnit and unit tests in general please refer
2728 to the KUnit documentation in Documentation/dev-tools/kunit/.
2729
2730 If unsure, say N.
2731
2732config BITS_TEST
2733 tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS
2734 depends on KUNIT
2735 default KUNIT_ALL_TESTS
2736 help
2737 This builds the bits unit test.
2738 Tests the logic of macros defined in bits.h.
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 SLUB_KUNIT_TEST
2745 tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS
2746 depends on SLUB_DEBUG && KUNIT
2747 default KUNIT_ALL_TESTS
2748 help
2749 This builds SLUB allocator unit test.
2750 Tests SLUB cache debugging functionality.
2751 For more information on KUnit and unit tests in general please refer
2752 to the KUnit documentation in Documentation/dev-tools/kunit/.
2753
2754 If unsure, say N.
2755
2756config RATIONAL_KUNIT_TEST
2757 tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS
2758 depends on KUNIT && RATIONAL
2759 default KUNIT_ALL_TESTS
2760 help
2761 This builds the rational math unit test.
2762 For more information on KUnit and unit tests in general please refer
2763 to the KUnit documentation in Documentation/dev-tools/kunit/.
2764
2765 If unsure, say N.
2766
2767config MEMCPY_KUNIT_TEST
2768 tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS
2769 depends on KUNIT
2770 default KUNIT_ALL_TESTS
2771 help
2772 Builds unit tests for memcpy(), memmove(), and memset() functions.
2773 For more information on KUnit and unit tests in general please refer
2774 to the KUnit documentation in Documentation/dev-tools/kunit/.
2775
2776 If unsure, say N.
2777
2778config IS_SIGNED_TYPE_KUNIT_TEST
2779 tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS
2780 depends on KUNIT
2781 default KUNIT_ALL_TESTS
2782 help
2783 Builds unit tests for the is_signed_type() macro.
2784
2785 For more information on KUnit and unit tests in general please refer
2786 to the KUnit documentation in Documentation/dev-tools/kunit/.
2787
2788 If unsure, say N.
2789
2790config OVERFLOW_KUNIT_TEST
2791 tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS
2792 depends on KUNIT
2793 default KUNIT_ALL_TESTS
2794 help
2795 Builds unit tests for the check_*_overflow(), size_*(), allocation, and
2796 related functions.
2797
2798 For more information on KUnit and unit tests in general please refer
2799 to the KUnit documentation in Documentation/dev-tools/kunit/.
2800
2801 If unsure, say N.
2802
2803config STACKINIT_KUNIT_TEST
2804 tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS
2805 depends on KUNIT
2806 default KUNIT_ALL_TESTS
2807 help
2808 Test if the kernel is zero-initializing stack variables and
2809 padding. Coverage is controlled by compiler flags,
2810 CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO,
2811 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2812 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2813
2814config FORTIFY_KUNIT_TEST
2815 tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS
2816 depends on KUNIT
2817 default KUNIT_ALL_TESTS
2818 help
2819 Builds unit tests for checking internals of FORTIFY_SOURCE as used
2820 by the str*() and mem*() family of functions. For testing runtime
2821 traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests.
2822
2823config HW_BREAKPOINT_KUNIT_TEST
2824 bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS
2825 depends on HAVE_HW_BREAKPOINT
2826 depends on KUNIT=y
2827 default KUNIT_ALL_TESTS
2828 help
2829 Tests for hw_breakpoint constraints accounting.
2830
2831 If unsure, say N.
2832
2833config SIPHASH_KUNIT_TEST
2834 tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS
2835 depends on KUNIT
2836 default KUNIT_ALL_TESTS
2837 help
2838 Enable this option to test the kernel's siphash (<linux/siphash.h>) hash
2839 functions on boot (or module load).
2840
2841 This is intended to help people writing architecture-specific
2842 optimized versions. If unsure, say N.
2843
2844config USERCOPY_KUNIT_TEST
2845 tristate "KUnit Test for user/kernel boundary protections"
2846 depends on KUNIT
2847 default KUNIT_ALL_TESTS
2848 help
2849 This builds the "usercopy_kunit" module that runs sanity checks
2850 on the copy_to/from_user infrastructure, making sure basic
2851 user/kernel boundary testing is working.
2852
2853config TEST_UDELAY
2854 tristate "udelay test driver"
2855 help
2856 This builds the "udelay_test" module that helps to make sure
2857 that udelay() is working properly.
2858
2859 If unsure, say N.
2860
2861config TEST_STATIC_KEYS
2862 tristate "Test static keys"
2863 depends on m
2864 help
2865 Test the static key interfaces.
2866
2867 If unsure, say N.
2868
2869config TEST_DYNAMIC_DEBUG
2870 tristate "Test DYNAMIC_DEBUG"
2871 depends on DYNAMIC_DEBUG
2872 help
2873 This module registers a tracer callback to count enabled
2874 pr_debugs in a 'do_debugging' function, then alters their
2875 enablements, calls the function, and compares counts.
2876
2877 If unsure, say N.
2878
2879config TEST_KMOD
2880 tristate "kmod stress tester"
2881 depends on m
2882 depends on NETDEVICES && NET_CORE && INET # for TUN
2883 depends on BLOCK
2884 depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS
2885 select TEST_LKM
2886 select XFS_FS
2887 select TUN
2888 select BTRFS_FS
2889 help
2890 Test the kernel's module loading mechanism: kmod. kmod implements
2891 support to load modules using the Linux kernel's usermode helper.
2892 This test provides a series of tests against kmod.
2893
2894 Although technically you can either build test_kmod as a module or
2895 into the kernel we disallow building it into the kernel since
2896 it stress tests request_module() and this will very likely cause
2897 some issues by taking over precious threads available from other
2898 module load requests, ultimately this could be fatal.
2899
2900 To run tests run:
2901
2902 tools/testing/selftests/kmod/kmod.sh --help
2903
2904 If unsure, say N.
2905
2906config TEST_DEBUG_VIRTUAL
2907 tristate "Test CONFIG_DEBUG_VIRTUAL feature"
2908 depends on DEBUG_VIRTUAL
2909 help
2910 Test the kernel's ability to detect incorrect calls to
2911 virt_to_phys() done against the non-linear part of the
2912 kernel's virtual address map.
2913
2914 If unsure, say N.
2915
2916config TEST_MEMCAT_P
2917 tristate "Test memcat_p() helper function"
2918 help
2919 Test the memcat_p() helper for correctly merging two
2920 pointer arrays together.
2921
2922 If unsure, say N.
2923
2924config TEST_OBJAGG
2925 tristate "Perform selftest on object aggreration manager"
2926 default n
2927 depends on OBJAGG
2928 help
2929 Enable this option to test object aggregation manager on boot
2930 (or module load).
2931
2932config TEST_MEMINIT
2933 tristate "Test heap/page initialization"
2934 help
2935 Test if the kernel is zero-initializing heap and page allocations.
2936 This can be useful to test init_on_alloc and init_on_free features.
2937
2938 If unsure, say N.
2939
2940config TEST_HMM
2941 tristate "Test HMM (Heterogeneous Memory Management)"
2942 depends on TRANSPARENT_HUGEPAGE
2943 depends on DEVICE_PRIVATE
2944 select HMM_MIRROR
2945 select MMU_NOTIFIER
2946 help
2947 This is a pseudo device driver solely for testing HMM.
2948 Say M here if you want to build the HMM test module.
2949 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests.
2950
2951 If unsure, say N.
2952
2953config TEST_FREE_PAGES
2954 tristate "Test freeing pages"
2955 help
2956 Test that a memory leak does not occur due to a race between
2957 freeing a block of pages and a speculative page reference.
2958 Loading this module is safe if your kernel has the bug fixed.
2959 If the bug is not fixed, it will leak gigabytes of memory and
2960 probably OOM your system.
2961
2962config TEST_FPU
2963 tristate "Test floating point operations in kernel space"
2964 depends on ARCH_HAS_KERNEL_FPU_SUPPORT && !KCOV_INSTRUMENT_ALL
2965 help
2966 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu
2967 which will trigger a sequence of floating point operations. This is used
2968 for self-testing floating point control register setting in
2969 kernel_fpu_begin().
2970
2971 If unsure, say N.
2972
2973config TEST_CLOCKSOURCE_WATCHDOG
2974 tristate "Test clocksource watchdog in kernel space"
2975 depends on CLOCKSOURCE_WATCHDOG
2976 help
2977 Enable this option to create a kernel module that will trigger
2978 a test of the clocksource watchdog. This module may be loaded
2979 via modprobe or insmod in which case it will run upon being
2980 loaded, or it may be built in, in which case it will run
2981 shortly after boot.
2982
2983 If unsure, say N.
2984
2985config TEST_OBJPOOL
2986 tristate "Test module for correctness and stress of objpool"
2987 default n
2988 depends on m && DEBUG_KERNEL
2989 help
2990 This builds the "test_objpool" module that should be used for
2991 correctness verification and concurrent testings of objects
2992 allocation and reclamation.
2993
2994 If unsure, say N.
2995
2996endif # RUNTIME_TESTING_MENU
2997
2998config ARCH_USE_MEMTEST
2999 bool
3000 help
3001 An architecture should select this when it uses early_memtest()
3002 during boot process.
3003
3004config MEMTEST
3005 bool "Memtest"
3006 depends on ARCH_USE_MEMTEST
3007 help
3008 This option adds a kernel parameter 'memtest', which allows memtest
3009 to be set and executed.
3010 memtest=0, mean disabled; -- default
3011 memtest=1, mean do 1 test pattern;
3012 ...
3013 memtest=17, mean do 17 test patterns.
3014 If you are unsure how to answer this question, answer N.
3015
3016
3017
3018config HYPERV_TESTING
3019 bool "Microsoft Hyper-V driver testing"
3020 default n
3021 depends on HYPERV && DEBUG_FS
3022 help
3023 Select this option to enable Hyper-V vmbus testing.
3024
3025endmenu # "Kernel Testing and Coverage"
3026
3027menu "Rust hacking"
3028
3029config RUST_DEBUG_ASSERTIONS
3030 bool "Debug assertions"
3031 depends on RUST
3032 help
3033 Enables rustc's `-Cdebug-assertions` codegen option.
3034
3035 This flag lets you turn `cfg(debug_assertions)` conditional
3036 compilation on or off. This can be used to enable extra debugging
3037 code in development but not in production. For example, it controls
3038 the behavior of the standard library's `debug_assert!` macro.
3039
3040 Note that this will apply to all Rust code, including `core`.
3041
3042 If unsure, say N.
3043
3044config RUST_OVERFLOW_CHECKS
3045 bool "Overflow checks"
3046 default y
3047 depends on RUST
3048 help
3049 Enables rustc's `-Coverflow-checks` codegen option.
3050
3051 This flag allows you to control the behavior of runtime integer
3052 overflow. When overflow-checks are enabled, a Rust panic will occur
3053 on overflow.
3054
3055 Note that this will apply to all Rust code, including `core`.
3056
3057 If unsure, say Y.
3058
3059config RUST_BUILD_ASSERT_ALLOW
3060 bool "Allow unoptimized build-time assertions"
3061 depends on RUST
3062 help
3063 Controls how `build_error!` and `build_assert!` are handled during the build.
3064
3065 If calls to them exist in the binary, it may indicate a violated invariant
3066 or that the optimizer failed to verify the invariant during compilation.
3067
3068 This should not happen, thus by default the build is aborted. However,
3069 as an escape hatch, you can choose Y here to ignore them during build
3070 and let the check be carried at runtime (with `panic!` being called if
3071 the check fails).
3072
3073 If unsure, say N.
3074
3075config RUST_KERNEL_DOCTESTS
3076 bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS
3077 depends on RUST && KUNIT=y
3078 default KUNIT_ALL_TESTS
3079 help
3080 This builds the documentation tests of the `kernel` crate
3081 as KUnit tests.
3082
3083 For more information on KUnit and unit tests in general,
3084 please refer to the KUnit documentation in Documentation/dev-tools/kunit/.
3085
3086 If unsure, say N.
3087
3088endmenu # "Rust"
3089
3090endmenu # Kernel hacking
3091
3092config INT_POW_TEST
3093 tristate "Integer exponentiation (int_pow) test" if !KUNIT_ALL_TESTS
3094 depends on KUNIT
3095 default KUNIT_ALL_TESTS
3096 help
3097 This option enables the KUnit test suite for the int_pow function,
3098 which performs integer exponentiation. The test suite is designed to
3099 verify that the implementation of int_pow correctly computes the power
3100 of a given base raised to a given exponent.
3101
3102 Enabling this option will include tests that check various scenarios
3103 and edge cases to ensure the accuracy and reliability of the exponentiation
3104 function.
3105
3106 If unsure, say N