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