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 || (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_TIMEOUT
1071 int "panic timeout"
1072 default 0
1073 help
1074 Set the timeout value (in seconds) until a reboot occurs when
1075 the kernel panics. If n = 0, then we wait forever. A timeout
1076 value n > 0 will wait n seconds before rebooting, while a timeout
1077 value n < 0 will reboot immediately. This setting can be overridden
1078 with the kernel command line option panic=, and from userspace via
1079 /proc/sys/kernel/panic.
1080
1081config LOCKUP_DETECTOR
1082 bool
1083
1084config SOFTLOCKUP_DETECTOR
1085 bool "Detect Soft Lockups"
1086 depends on DEBUG_KERNEL && !S390
1087 select LOCKUP_DETECTOR
1088 help
1089 Say Y here to enable the kernel to act as a watchdog to detect
1090 soft lockups.
1091
1092 Softlockups are bugs that cause the kernel to loop in kernel
1093 mode for more than 20 seconds, without giving other tasks a
1094 chance to run. The current stack trace is displayed upon
1095 detection and the system will stay locked up.
1096
1097config SOFTLOCKUP_DETECTOR_INTR_STORM
1098 bool "Detect Interrupt Storm in Soft Lockups"
1099 depends on SOFTLOCKUP_DETECTOR && IRQ_TIME_ACCOUNTING
1100 select GENERIC_IRQ_STAT_SNAPSHOT
1101 default y if NR_CPUS <= 128
1102 help
1103 Say Y here to enable the kernel to detect interrupt storm
1104 during "soft lockups".
1105
1106 "soft lockups" can be caused by a variety of reasons. If one is
1107 caused by an interrupt storm, then the storming interrupts will not
1108 be on the callstack. To detect this case, it is necessary to report
1109 the CPU stats and the interrupt counts during the "soft lockups".
1110
1111config BOOTPARAM_SOFTLOCKUP_PANIC
1112 bool "Panic (Reboot) On Soft Lockups"
1113 depends on SOFTLOCKUP_DETECTOR
1114 help
1115 Say Y here to enable the kernel to panic on "soft lockups",
1116 which are bugs that cause the kernel to loop in kernel
1117 mode for more than 20 seconds (configurable using the watchdog_thresh
1118 sysctl), without giving other tasks a chance to run.
1119
1120 The panic can be used in combination with panic_timeout,
1121 to cause the system to reboot automatically after a
1122 lockup has been detected. This feature is useful for
1123 high-availability systems that have uptime guarantees and
1124 where a lockup must be resolved ASAP.
1125
1126 Say N if unsure.
1127
1128config HAVE_HARDLOCKUP_DETECTOR_BUDDY
1129 bool
1130 depends on SMP
1131 default y
1132
1133#
1134# Global switch whether to build a hardlockup detector at all. It is available
1135# only when the architecture supports at least one implementation. There are
1136# two exceptions. The hardlockup detector is never enabled on:
1137#
1138# s390: it reported many false positives there
1139#
1140# sparc64: has a custom implementation which is not using the common
1141# hardlockup command line options and sysctl interface.
1142#
1143config HARDLOCKUP_DETECTOR
1144 bool "Detect Hard Lockups"
1145 depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64
1146 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH
1147 imply HARDLOCKUP_DETECTOR_PERF
1148 imply HARDLOCKUP_DETECTOR_BUDDY
1149 imply HARDLOCKUP_DETECTOR_ARCH
1150 select LOCKUP_DETECTOR
1151
1152 help
1153 Say Y here to enable the kernel to act as a watchdog to detect
1154 hard lockups.
1155
1156 Hardlockups are bugs that cause the CPU to loop in kernel mode
1157 for more than 10 seconds, without letting other interrupts have a
1158 chance to run. The current stack trace is displayed upon detection
1159 and the system will stay locked up.
1160
1161#
1162# Note that arch-specific variants are always preferred.
1163#
1164config HARDLOCKUP_DETECTOR_PREFER_BUDDY
1165 bool "Prefer the buddy CPU hardlockup detector"
1166 depends on HARDLOCKUP_DETECTOR
1167 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY
1168 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1169 help
1170 Say Y here to prefer the buddy hardlockup detector over the perf one.
1171
1172 With the buddy detector, each CPU uses its softlockup hrtimer
1173 to check that the next CPU is processing hrtimer interrupts by
1174 verifying that a counter is increasing.
1175
1176 This hardlockup detector is useful on systems that don't have
1177 an arch-specific hardlockup detector or if resources needed
1178 for the hardlockup detector are better used for other things.
1179
1180config HARDLOCKUP_DETECTOR_PERF
1181 bool
1182 depends on HARDLOCKUP_DETECTOR
1183 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY
1184 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1185 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1186
1187config HARDLOCKUP_DETECTOR_BUDDY
1188 bool
1189 depends on HARDLOCKUP_DETECTOR
1190 depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY
1191 depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY
1192 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1193 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1194
1195config HARDLOCKUP_DETECTOR_ARCH
1196 bool
1197 depends on HARDLOCKUP_DETECTOR
1198 depends on HAVE_HARDLOCKUP_DETECTOR_ARCH
1199 help
1200 The arch-specific implementation of the hardlockup detector will
1201 be used.
1202
1203#
1204# Both the "perf" and "buddy" hardlockup detectors count hrtimer
1205# interrupts. This config enables functions managing this common code.
1206#
1207config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1208 bool
1209 select SOFTLOCKUP_DETECTOR
1210
1211#
1212# Enables a timestamp based low pass filter to compensate for perf based
1213# hard lockup detection which runs too fast due to turbo modes.
1214#
1215config HARDLOCKUP_CHECK_TIMESTAMP
1216 bool
1217
1218config BOOTPARAM_HARDLOCKUP_PANIC
1219 bool "Panic (Reboot) On Hard Lockups"
1220 depends on HARDLOCKUP_DETECTOR
1221 help
1222 Say Y here to enable the kernel to panic on "hard lockups",
1223 which are bugs that cause the kernel to loop in kernel
1224 mode with interrupts disabled for more than 10 seconds (configurable
1225 using the watchdog_thresh sysctl).
1226
1227 Say N if unsure.
1228
1229config DETECT_HUNG_TASK
1230 bool "Detect Hung Tasks"
1231 depends on DEBUG_KERNEL
1232 default SOFTLOCKUP_DETECTOR
1233 help
1234 Say Y here to enable the kernel to detect "hung tasks",
1235 which are bugs that cause the task to be stuck in
1236 uninterruptible "D" state indefinitely.
1237
1238 When a hung task is detected, the kernel will print the
1239 current stack trace (which you should report), but the
1240 task will stay in uninterruptible state. If lockdep is
1241 enabled then all held locks will also be reported. This
1242 feature has negligible overhead.
1243
1244config DEFAULT_HUNG_TASK_TIMEOUT
1245 int "Default timeout for hung task detection (in seconds)"
1246 depends on DETECT_HUNG_TASK
1247 default 120
1248 help
1249 This option controls the default timeout (in seconds) used
1250 to determine when a task has become non-responsive and should
1251 be considered hung.
1252
1253 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
1254 sysctl or by writing a value to
1255 /proc/sys/kernel/hung_task_timeout_secs.
1256
1257 A timeout of 0 disables the check. The default is two minutes.
1258 Keeping the default should be fine in most cases.
1259
1260config BOOTPARAM_HUNG_TASK_PANIC
1261 bool "Panic (Reboot) On Hung Tasks"
1262 depends on DETECT_HUNG_TASK
1263 help
1264 Say Y here to enable the kernel to panic on "hung tasks",
1265 which are bugs that cause the kernel to leave a task stuck
1266 in uninterruptible "D" state.
1267
1268 The panic can be used in combination with panic_timeout,
1269 to cause the system to reboot automatically after a
1270 hung task has been detected. This feature is useful for
1271 high-availability systems that have uptime guarantees and
1272 where a hung tasks must be resolved ASAP.
1273
1274 Say N if unsure.
1275
1276config DETECT_HUNG_TASK_BLOCKER
1277 bool "Dump Hung Tasks Blocker"
1278 depends on DETECT_HUNG_TASK
1279 depends on !PREEMPT_RT
1280 default y
1281 help
1282 Say Y here to show the blocker task's stacktrace who acquires
1283 the mutex lock which "hung tasks" are waiting.
1284 This will add overhead a bit but shows suspicious tasks and
1285 call trace if it comes from waiting a mutex.
1286
1287config WQ_WATCHDOG
1288 bool "Detect Workqueue Stalls"
1289 depends on DEBUG_KERNEL
1290 help
1291 Say Y here to enable stall detection on workqueues. If a
1292 worker pool doesn't make forward progress on a pending work
1293 item for over a given amount of time, 30s by default, a
1294 warning message is printed along with dump of workqueue
1295 state. This can be configured through kernel parameter
1296 "workqueue.watchdog_thresh" and its sysfs counterpart.
1297
1298config WQ_CPU_INTENSIVE_REPORT
1299 bool "Report per-cpu work items which hog CPU for too long"
1300 depends on DEBUG_KERNEL
1301 help
1302 Say Y here to enable reporting of concurrency-managed per-cpu work
1303 items that hog CPUs for longer than
1304 workqueue.cpu_intensive_thresh_us. Workqueue automatically
1305 detects and excludes them from concurrency management to prevent
1306 them from stalling other per-cpu work items. Occassional
1307 triggering may not necessarily indicate a problem. Repeated
1308 triggering likely indicates that the work item should be switched
1309 to use an unbound workqueue.
1310
1311config TEST_LOCKUP
1312 tristate "Test module to generate lockups"
1313 depends on m
1314 help
1315 This builds the "test_lockup" module that helps to make sure
1316 that watchdogs and lockup detectors are working properly.
1317
1318 Depending on module parameters it could emulate soft or hard
1319 lockup, "hung task", or locking arbitrary lock for a long time.
1320 Also it could generate series of lockups with cooling-down periods.
1321
1322 If unsure, say N.
1323
1324endmenu # "Debug lockups and hangs"
1325
1326menu "Scheduler Debugging"
1327
1328config SCHED_INFO
1329 bool
1330 default n
1331
1332config SCHEDSTATS
1333 bool "Collect scheduler statistics"
1334 depends on PROC_FS
1335 select SCHED_INFO
1336 help
1337 If you say Y here, additional code will be inserted into the
1338 scheduler and related routines to collect statistics about
1339 scheduler behavior and provide them in /proc/schedstat. These
1340 stats may be useful for both tuning and debugging the scheduler
1341 If you aren't debugging the scheduler or trying to tune a specific
1342 application, you can say N to avoid the very slight overhead
1343 this adds.
1344
1345endmenu
1346
1347config DEBUG_PREEMPT
1348 bool "Debug preemptible kernel"
1349 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT
1350 help
1351 If you say Y here then the kernel will use a debug variant of the
1352 commonly used smp_processor_id() function and will print warnings
1353 if kernel code uses it in a preemption-unsafe way. Also, the kernel
1354 will detect preemption count underflows.
1355
1356 This option has potential to introduce high runtime overhead,
1357 depending on workload as it triggers debugging routines for each
1358 this_cpu operation. It should only be used for debugging purposes.
1359
1360menu "Lock Debugging (spinlocks, mutexes, etc...)"
1361
1362config LOCK_DEBUGGING_SUPPORT
1363 bool
1364 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1365 default y
1366
1367config PROVE_LOCKING
1368 bool "Lock debugging: prove locking correctness"
1369 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1370 select LOCKDEP
1371 select DEBUG_SPINLOCK
1372 select DEBUG_MUTEXES if !PREEMPT_RT
1373 select DEBUG_RT_MUTEXES if RT_MUTEXES
1374 select DEBUG_RWSEMS if !PREEMPT_RT
1375 select DEBUG_WW_MUTEX_SLOWPATH
1376 select DEBUG_LOCK_ALLOC
1377 select PREEMPT_COUNT if !ARCH_NO_PREEMPT
1378 select TRACE_IRQFLAGS
1379 default n
1380 help
1381 This feature enables the kernel to prove that all locking
1382 that occurs in the kernel runtime is mathematically
1383 correct: that under no circumstance could an arbitrary (and
1384 not yet triggered) combination of observed locking
1385 sequences (on an arbitrary number of CPUs, running an
1386 arbitrary number of tasks and interrupt contexts) cause a
1387 deadlock.
1388
1389 In short, this feature enables the kernel to report locking
1390 related deadlocks before they actually occur.
1391
1392 The proof does not depend on how hard and complex a
1393 deadlock scenario would be to trigger: how many
1394 participant CPUs, tasks and irq-contexts would be needed
1395 for it to trigger. The proof also does not depend on
1396 timing: if a race and a resulting deadlock is possible
1397 theoretically (no matter how unlikely the race scenario
1398 is), it will be proven so and will immediately be
1399 reported by the kernel (once the event is observed that
1400 makes the deadlock theoretically possible).
1401
1402 If a deadlock is impossible (i.e. the locking rules, as
1403 observed by the kernel, are mathematically correct), the
1404 kernel reports nothing.
1405
1406 NOTE: this feature can also be enabled for rwlocks, mutexes
1407 and rwsems - in which case all dependencies between these
1408 different locking variants are observed and mapped too, and
1409 the proof of observed correctness is also maintained for an
1410 arbitrary combination of these separate locking variants.
1411
1412 For more details, see Documentation/locking/lockdep-design.rst.
1413
1414config PROVE_RAW_LOCK_NESTING
1415 bool "Enable raw_spinlock - spinlock nesting checks" if !ARCH_SUPPORTS_RT
1416 depends on PROVE_LOCKING
1417 default y if ARCH_SUPPORTS_RT
1418 help
1419 Enable the raw_spinlock vs. spinlock nesting checks which ensure
1420 that the lock nesting rules for PREEMPT_RT enabled kernels are
1421 not violated.
1422
1423config LOCK_STAT
1424 bool "Lock usage statistics"
1425 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1426 select LOCKDEP
1427 select DEBUG_SPINLOCK
1428 select DEBUG_MUTEXES if !PREEMPT_RT
1429 select DEBUG_RT_MUTEXES if RT_MUTEXES
1430 select DEBUG_LOCK_ALLOC
1431 default n
1432 help
1433 This feature enables tracking lock contention points
1434
1435 For more details, see Documentation/locking/lockstat.rst
1436
1437 This also enables lock events required by "perf lock",
1438 subcommand of perf.
1439 If you want to use "perf lock", you also need to turn on
1440 CONFIG_EVENT_TRACING.
1441
1442 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1443 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1444
1445config DEBUG_RT_MUTEXES
1446 bool "RT Mutex debugging, deadlock detection"
1447 depends on DEBUG_KERNEL && RT_MUTEXES
1448 help
1449 This allows rt mutex semantics violations and rt mutex related
1450 deadlocks (lockups) to be detected and reported automatically.
1451
1452config DEBUG_SPINLOCK
1453 bool "Spinlock and rw-lock debugging: basic checks"
1454 depends on DEBUG_KERNEL
1455 select UNINLINE_SPIN_UNLOCK
1456 help
1457 Say Y here and build SMP to catch missing spinlock initialization
1458 and certain other kinds of spinlock errors commonly made. This is
1459 best used in conjunction with the NMI watchdog so that spinlock
1460 deadlocks are also debuggable.
1461
1462config DEBUG_MUTEXES
1463 bool "Mutex debugging: basic checks"
1464 depends on DEBUG_KERNEL && !PREEMPT_RT
1465 help
1466 This feature allows mutex semantics violations to be detected and
1467 reported.
1468
1469config DEBUG_WW_MUTEX_SLOWPATH
1470 bool "Wait/wound mutex debugging: Slowpath testing"
1471 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1472 select DEBUG_LOCK_ALLOC
1473 select DEBUG_SPINLOCK
1474 select DEBUG_MUTEXES if !PREEMPT_RT
1475 select DEBUG_RT_MUTEXES if PREEMPT_RT
1476 help
1477 This feature enables slowpath testing for w/w mutex users by
1478 injecting additional -EDEADLK wound/backoff cases. Together with
1479 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1480 will test all possible w/w mutex interface abuse with the
1481 exception of simply not acquiring all the required locks.
1482 Note that this feature can introduce significant overhead, so
1483 it really should not be enabled in a production or distro kernel,
1484 even a debug kernel. If you are a driver writer, enable it. If
1485 you are a distro, do not.
1486
1487config DEBUG_RWSEMS
1488 bool "RW Semaphore debugging: basic checks"
1489 depends on DEBUG_KERNEL && !PREEMPT_RT
1490 help
1491 This debugging feature allows mismatched rw semaphore locks
1492 and unlocks to be detected and reported.
1493
1494config DEBUG_LOCK_ALLOC
1495 bool "Lock debugging: detect incorrect freeing of live locks"
1496 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1497 select DEBUG_SPINLOCK
1498 select DEBUG_MUTEXES if !PREEMPT_RT
1499 select DEBUG_RT_MUTEXES if RT_MUTEXES
1500 select LOCKDEP
1501 help
1502 This feature will check whether any held lock (spinlock, rwlock,
1503 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1504 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1505 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1506 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1507 held during task exit.
1508
1509config LOCKDEP
1510 bool
1511 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1512 select STACKTRACE
1513 select KALLSYMS
1514 select KALLSYMS_ALL
1515
1516config LOCKDEP_SMALL
1517 bool
1518
1519config LOCKDEP_BITS
1520 int "Size for MAX_LOCKDEP_ENTRIES (as Nth power of 2)"
1521 depends on LOCKDEP && !LOCKDEP_SMALL
1522 range 10 24
1523 default 15
1524 help
1525 Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message.
1526
1527config LOCKDEP_CHAINS_BITS
1528 int "Size for MAX_LOCKDEP_CHAINS (as Nth power of 2)"
1529 depends on LOCKDEP && !LOCKDEP_SMALL
1530 range 10 21
1531 default 16
1532 help
1533 Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message.
1534
1535config LOCKDEP_STACK_TRACE_BITS
1536 int "Size for MAX_STACK_TRACE_ENTRIES (as Nth power of 2)"
1537 depends on LOCKDEP && !LOCKDEP_SMALL
1538 range 10 26
1539 default 19
1540 help
1541 Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message.
1542
1543config LOCKDEP_STACK_TRACE_HASH_BITS
1544 int "Size for STACK_TRACE_HASH_SIZE (as Nth power of 2)"
1545 depends on LOCKDEP && !LOCKDEP_SMALL
1546 range 10 26
1547 default 14
1548 help
1549 Try increasing this value if you need large STACK_TRACE_HASH_SIZE.
1550
1551config LOCKDEP_CIRCULAR_QUEUE_BITS
1552 int "Size for elements in circular_queue struct (as Nth power of 2)"
1553 depends on LOCKDEP
1554 range 10 26
1555 default 12
1556 help
1557 Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure.
1558
1559config DEBUG_LOCKDEP
1560 bool "Lock dependency engine debugging"
1561 depends on DEBUG_KERNEL && LOCKDEP
1562 select DEBUG_IRQFLAGS
1563 help
1564 If you say Y here, the lock dependency engine will do
1565 additional runtime checks to debug itself, at the price
1566 of more runtime overhead.
1567
1568config DEBUG_ATOMIC_SLEEP
1569 bool "Sleep inside atomic section checking"
1570 select PREEMPT_COUNT
1571 depends on DEBUG_KERNEL
1572 depends on !ARCH_NO_PREEMPT
1573 help
1574 If you say Y here, various routines which may sleep will become very
1575 noisy if they are called inside atomic sections: when a spinlock is
1576 held, inside an rcu read side critical section, inside preempt disabled
1577 sections, inside an interrupt, etc...
1578
1579config DEBUG_LOCKING_API_SELFTESTS
1580 bool "Locking API boot-time self-tests"
1581 depends on DEBUG_KERNEL
1582 help
1583 Say Y here if you want the kernel to run a short self-test during
1584 bootup. The self-test checks whether common types of locking bugs
1585 are detected by debugging mechanisms or not. (if you disable
1586 lock debugging then those bugs won't be detected of course.)
1587 The following locking APIs are covered: spinlocks, rwlocks,
1588 mutexes and rwsems.
1589
1590config LOCK_TORTURE_TEST
1591 tristate "torture tests for locking"
1592 depends on DEBUG_KERNEL
1593 select TORTURE_TEST
1594 help
1595 This option provides a kernel module that runs torture tests
1596 on kernel locking primitives. The kernel module may be built
1597 after the fact on the running kernel to be tested, if desired.
1598
1599 Say Y here if you want kernel locking-primitive torture tests
1600 to be built into the kernel.
1601 Say M if you want these torture tests to build as a module.
1602 Say N if you are unsure.
1603
1604config WW_MUTEX_SELFTEST
1605 tristate "Wait/wound mutex selftests"
1606 help
1607 This option provides a kernel module that runs tests on the
1608 on the struct ww_mutex locking API.
1609
1610 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1611 with this test harness.
1612
1613 Say M if you want these self tests to build as a module.
1614 Say N if you are unsure.
1615
1616config SCF_TORTURE_TEST
1617 tristate "torture tests for smp_call_function*()"
1618 depends on DEBUG_KERNEL
1619 select TORTURE_TEST
1620 help
1621 This option provides a kernel module that runs torture tests
1622 on the smp_call_function() family of primitives. The kernel
1623 module may be built after the fact on the running kernel to
1624 be tested, if desired.
1625
1626config CSD_LOCK_WAIT_DEBUG
1627 bool "Debugging for csd_lock_wait(), called from smp_call_function*()"
1628 depends on DEBUG_KERNEL
1629 depends on SMP
1630 depends on 64BIT
1631 default n
1632 help
1633 This option enables debug prints when CPUs are slow to respond
1634 to the smp_call_function*() IPI wrappers. These debug prints
1635 include the IPI handler function currently executing (if any)
1636 and relevant stack traces.
1637
1638config CSD_LOCK_WAIT_DEBUG_DEFAULT
1639 bool "Default csd_lock_wait() debugging on at boot time"
1640 depends on CSD_LOCK_WAIT_DEBUG
1641 depends on 64BIT
1642 default n
1643 help
1644 This option causes the csdlock_debug= kernel boot parameter to
1645 default to 1 (basic debugging) instead of 0 (no debugging).
1646
1647endmenu # lock debugging
1648
1649config TRACE_IRQFLAGS
1650 depends on TRACE_IRQFLAGS_SUPPORT
1651 bool
1652 help
1653 Enables hooks to interrupt enabling and disabling for
1654 either tracing or lock debugging.
1655
1656config TRACE_IRQFLAGS_NMI
1657 def_bool y
1658 depends on TRACE_IRQFLAGS
1659 depends on TRACE_IRQFLAGS_NMI_SUPPORT
1660
1661config NMI_CHECK_CPU
1662 bool "Debugging for CPUs failing to respond to backtrace requests"
1663 depends on DEBUG_KERNEL
1664 depends on X86
1665 default n
1666 help
1667 Enables debug prints when a CPU fails to respond to a given
1668 backtrace NMI. These prints provide some reasons why a CPU
1669 might legitimately be failing to respond, for example, if it
1670 is offline of if ignore_nmis is set.
1671
1672config DEBUG_IRQFLAGS
1673 bool "Debug IRQ flag manipulation"
1674 help
1675 Enables checks for potentially unsafe enabling or disabling of
1676 interrupts, such as calling raw_local_irq_restore() when interrupts
1677 are enabled.
1678
1679config STACKTRACE
1680 bool "Stack backtrace support"
1681 depends on STACKTRACE_SUPPORT
1682 help
1683 This option causes the kernel to create a /proc/pid/stack for
1684 every process, showing its current stack trace.
1685 It is also used by various kernel debugging features that require
1686 stack trace generation.
1687
1688config WARN_ALL_UNSEEDED_RANDOM
1689 bool "Warn for all uses of unseeded randomness"
1690 default n
1691 help
1692 Some parts of the kernel contain bugs relating to their use of
1693 cryptographically secure random numbers before it's actually possible
1694 to generate those numbers securely. This setting ensures that these
1695 flaws don't go unnoticed, by enabling a message, should this ever
1696 occur. This will allow people with obscure setups to know when things
1697 are going wrong, so that they might contact developers about fixing
1698 it.
1699
1700 Unfortunately, on some models of some architectures getting
1701 a fully seeded CRNG is extremely difficult, and so this can
1702 result in dmesg getting spammed for a surprisingly long
1703 time. This is really bad from a security perspective, and
1704 so architecture maintainers really need to do what they can
1705 to get the CRNG seeded sooner after the system is booted.
1706 However, since users cannot do anything actionable to
1707 address this, by default this option is disabled.
1708
1709 Say Y here if you want to receive warnings for all uses of
1710 unseeded randomness. This will be of use primarily for
1711 those developers interested in improving the security of
1712 Linux kernels running on their architecture (or
1713 subarchitecture).
1714
1715config DEBUG_KOBJECT
1716 bool "kobject debugging"
1717 depends on DEBUG_KERNEL
1718 help
1719 If you say Y here, some extra kobject debugging messages will be sent
1720 to the syslog.
1721
1722config DEBUG_KOBJECT_RELEASE
1723 bool "kobject release debugging"
1724 depends on DEBUG_OBJECTS_TIMERS
1725 help
1726 kobjects are reference counted objects. This means that their
1727 last reference count put is not predictable, and the kobject can
1728 live on past the point at which a driver decides to drop its
1729 initial reference to the kobject gained on allocation. An
1730 example of this would be a struct device which has just been
1731 unregistered.
1732
1733 However, some buggy drivers assume that after such an operation,
1734 the memory backing the kobject can be immediately freed. This
1735 goes completely against the principles of a refcounted object.
1736
1737 If you say Y here, the kernel will delay the release of kobjects
1738 on the last reference count to improve the visibility of this
1739 kind of kobject release bug.
1740
1741config HAVE_DEBUG_BUGVERBOSE
1742 bool
1743
1744menu "Debug kernel data structures"
1745
1746config DEBUG_LIST
1747 bool "Debug linked list manipulation"
1748 depends on DEBUG_KERNEL
1749 select LIST_HARDENED
1750 help
1751 Enable this to turn on extended checks in the linked-list walking
1752 routines.
1753
1754 This option trades better quality error reports for performance, and
1755 is more suitable for kernel debugging. If you care about performance,
1756 you should only enable CONFIG_LIST_HARDENED instead.
1757
1758 If unsure, say N.
1759
1760config DEBUG_PLIST
1761 bool "Debug priority linked list manipulation"
1762 depends on DEBUG_KERNEL
1763 help
1764 Enable this to turn on extended checks in the priority-ordered
1765 linked-list (plist) walking routines. This checks the entire
1766 list multiple times during each manipulation.
1767
1768 If unsure, say N.
1769
1770config DEBUG_SG
1771 bool "Debug SG table operations"
1772 depends on DEBUG_KERNEL
1773 help
1774 Enable this to turn on checks on scatter-gather tables. This can
1775 help find problems with drivers that do not properly initialize
1776 their sg tables.
1777
1778 If unsure, say N.
1779
1780config DEBUG_NOTIFIERS
1781 bool "Debug notifier call chains"
1782 depends on DEBUG_KERNEL
1783 help
1784 Enable this to turn on sanity checking for notifier call chains.
1785 This is most useful for kernel developers to make sure that
1786 modules properly unregister themselves from notifier chains.
1787 This is a relatively cheap check but if you care about maximum
1788 performance, say N.
1789
1790config DEBUG_CLOSURES
1791 bool "Debug closures (bcache async widgits)"
1792 depends on CLOSURES
1793 select DEBUG_FS
1794 help
1795 Keeps all active closures in a linked list and provides a debugfs
1796 interface to list them, which makes it possible to see asynchronous
1797 operations that get stuck.
1798
1799config DEBUG_MAPLE_TREE
1800 bool "Debug maple trees"
1801 depends on DEBUG_KERNEL
1802 help
1803 Enable maple tree debugging information and extra validations.
1804
1805 If unsure, say N.
1806
1807endmenu
1808
1809source "kernel/rcu/Kconfig.debug"
1810
1811config DEBUG_WQ_FORCE_RR_CPU
1812 bool "Force round-robin CPU selection for unbound work items"
1813 depends on DEBUG_KERNEL
1814 default n
1815 help
1816 Workqueue used to implicitly guarantee that work items queued
1817 without explicit CPU specified are put on the local CPU. This
1818 guarantee is no longer true and while local CPU is still
1819 preferred work items may be put on foreign CPUs. Kernel
1820 parameter "workqueue.debug_force_rr_cpu" is added to force
1821 round-robin CPU selection to flush out usages which depend on the
1822 now broken guarantee. This config option enables the debug
1823 feature by default. When enabled, memory and cache locality will
1824 be impacted.
1825
1826config CPU_HOTPLUG_STATE_CONTROL
1827 bool "Enable CPU hotplug state control"
1828 depends on DEBUG_KERNEL
1829 depends on HOTPLUG_CPU
1830 default n
1831 help
1832 Allows to write steps between "offline" and "online" to the CPUs
1833 sysfs target file so states can be stepped granular. This is a debug
1834 option for now as the hotplug machinery cannot be stopped and
1835 restarted at arbitrary points yet.
1836
1837 Say N if your are unsure.
1838
1839config LATENCYTOP
1840 bool "Latency measuring infrastructure"
1841 depends on DEBUG_KERNEL
1842 depends on STACKTRACE_SUPPORT
1843 depends on PROC_FS
1844 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
1845 select KALLSYMS
1846 select KALLSYMS_ALL
1847 select STACKTRACE
1848 select SCHEDSTATS
1849 help
1850 Enable this option if you want to use the LatencyTOP tool
1851 to find out which userspace is blocking on what kernel operations.
1852
1853config DEBUG_CGROUP_REF
1854 bool "Disable inlining of cgroup css reference count functions"
1855 depends on DEBUG_KERNEL
1856 depends on CGROUPS
1857 depends on KPROBES
1858 default n
1859 help
1860 Force cgroup css reference count functions to not be inlined so
1861 that they can be kprobed for debugging.
1862
1863source "kernel/trace/Kconfig"
1864
1865config PROVIDE_OHCI1394_DMA_INIT
1866 bool "Remote debugging over FireWire early on boot"
1867 depends on PCI && X86
1868 help
1869 If you want to debug problems which hang or crash the kernel early
1870 on boot and the crashing machine has a FireWire port, you can use
1871 this feature to remotely access the memory of the crashed machine
1872 over FireWire. This employs remote DMA as part of the OHCI1394
1873 specification which is now the standard for FireWire controllers.
1874
1875 With remote DMA, you can monitor the printk buffer remotely using
1876 firescope and access all memory below 4GB using fireproxy from gdb.
1877 Even controlling a kernel debugger is possible using remote DMA.
1878
1879 Usage:
1880
1881 If ohci1394_dma=early is used as boot parameter, it will initialize
1882 all OHCI1394 controllers which are found in the PCI config space.
1883
1884 As all changes to the FireWire bus such as enabling and disabling
1885 devices cause a bus reset and thereby disable remote DMA for all
1886 devices, be sure to have the cable plugged and FireWire enabled on
1887 the debugging host before booting the debug target for debugging.
1888
1889 This code (~1k) is freed after boot. By then, the firewire stack
1890 in charge of the OHCI-1394 controllers should be used instead.
1891
1892 See Documentation/core-api/debugging-via-ohci1394.rst for more information.
1893
1894source "samples/Kconfig"
1895
1896config ARCH_HAS_DEVMEM_IS_ALLOWED
1897 bool
1898
1899config STRICT_DEVMEM
1900 bool "Filter access to /dev/mem"
1901 depends on MMU && DEVMEM
1902 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED
1903 default y if PPC || X86 || ARM64 || S390
1904 help
1905 If this option is disabled, you allow userspace (root) access to all
1906 of memory, including kernel and userspace memory. Accidental
1907 access to this is obviously disastrous, but specific access can
1908 be used by people debugging the kernel. Note that with PAT support
1909 enabled, even in this case there are restrictions on /dev/mem
1910 use due to the cache aliasing requirements.
1911
1912 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
1913 file only allows userspace access to PCI space and the BIOS code and
1914 data regions. This is sufficient for dosemu and X and all common
1915 users of /dev/mem.
1916
1917 If in doubt, say Y.
1918
1919config IO_STRICT_DEVMEM
1920 bool "Filter I/O access to /dev/mem"
1921 depends on STRICT_DEVMEM
1922 help
1923 If this option is disabled, you allow userspace (root) access to all
1924 io-memory regardless of whether a driver is actively using that
1925 range. Accidental access to this is obviously disastrous, but
1926 specific access can be used by people debugging kernel drivers.
1927
1928 If this option is switched on, the /dev/mem file only allows
1929 userspace access to *idle* io-memory ranges (see /proc/iomem) This
1930 may break traditional users of /dev/mem (dosemu, legacy X, etc...)
1931 if the driver using a given range cannot be disabled.
1932
1933 If in doubt, say Y.
1934
1935menu "$(SRCARCH) Debugging"
1936
1937source "arch/$(SRCARCH)/Kconfig.debug"
1938
1939endmenu
1940
1941menu "Kernel Testing and Coverage"
1942
1943source "lib/kunit/Kconfig"
1944
1945config NOTIFIER_ERROR_INJECTION
1946 tristate "Notifier error injection"
1947 depends on DEBUG_KERNEL
1948 select DEBUG_FS
1949 help
1950 This option provides the ability to inject artificial errors to
1951 specified notifier chain callbacks. It is useful to test the error
1952 handling of notifier call chain failures.
1953
1954 Say N if unsure.
1955
1956config PM_NOTIFIER_ERROR_INJECT
1957 tristate "PM notifier error injection module"
1958 depends on PM && NOTIFIER_ERROR_INJECTION
1959 default m if PM_DEBUG
1960 help
1961 This option provides the ability to inject artificial errors to
1962 PM notifier chain callbacks. It is controlled through debugfs
1963 interface /sys/kernel/debug/notifier-error-inject/pm
1964
1965 If the notifier call chain should be failed with some events
1966 notified, write the error code to "actions/<notifier event>/error".
1967
1968 Example: Inject PM suspend error (-12 = -ENOMEM)
1969
1970 # cd /sys/kernel/debug/notifier-error-inject/pm/
1971 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1972 # echo mem > /sys/power/state
1973 bash: echo: write error: Cannot allocate memory
1974
1975 To compile this code as a module, choose M here: the module will
1976 be called pm-notifier-error-inject.
1977
1978 If unsure, say N.
1979
1980config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1981 tristate "OF reconfig notifier error injection module"
1982 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1983 help
1984 This option provides the ability to inject artificial errors to
1985 OF reconfig notifier chain callbacks. It is controlled
1986 through debugfs interface under
1987 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1988
1989 If the notifier call chain should be failed with some events
1990 notified, write the error code to "actions/<notifier event>/error".
1991
1992 To compile this code as a module, choose M here: the module will
1993 be called of-reconfig-notifier-error-inject.
1994
1995 If unsure, say N.
1996
1997config NETDEV_NOTIFIER_ERROR_INJECT
1998 tristate "Netdev notifier error injection module"
1999 depends on NET && NOTIFIER_ERROR_INJECTION
2000 help
2001 This option provides the ability to inject artificial errors to
2002 netdevice notifier chain callbacks. It is controlled through debugfs
2003 interface /sys/kernel/debug/notifier-error-inject/netdev
2004
2005 If the notifier call chain should be failed with some events
2006 notified, write the error code to "actions/<notifier event>/error".
2007
2008 Example: Inject netdevice mtu change error (-22 = -EINVAL)
2009
2010 # cd /sys/kernel/debug/notifier-error-inject/netdev
2011 # echo -22 > actions/NETDEV_CHANGEMTU/error
2012 # ip link set eth0 mtu 1024
2013 RTNETLINK answers: Invalid argument
2014
2015 To compile this code as a module, choose M here: the module will
2016 be called netdev-notifier-error-inject.
2017
2018 If unsure, say N.
2019
2020config FUNCTION_ERROR_INJECTION
2021 bool "Fault-injections of functions"
2022 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
2023 help
2024 Add fault injections into various functions that are annotated with
2025 ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return
2026 value of these functions. This is useful to test error paths of code.
2027
2028 If unsure, say N
2029
2030config FAULT_INJECTION
2031 bool "Fault-injection framework"
2032 depends on DEBUG_KERNEL
2033 help
2034 Provide fault-injection framework.
2035 For more details, see Documentation/fault-injection/.
2036
2037config FAILSLAB
2038 bool "Fault-injection capability for kmalloc"
2039 depends on FAULT_INJECTION
2040 help
2041 Provide fault-injection capability for kmalloc.
2042
2043config FAIL_PAGE_ALLOC
2044 bool "Fault-injection capability for alloc_pages()"
2045 depends on FAULT_INJECTION
2046 help
2047 Provide fault-injection capability for alloc_pages().
2048
2049config FAULT_INJECTION_USERCOPY
2050 bool "Fault injection capability for usercopy functions"
2051 depends on FAULT_INJECTION
2052 help
2053 Provides fault-injection capability to inject failures
2054 in usercopy functions (copy_from_user(), get_user(), ...).
2055
2056config FAIL_MAKE_REQUEST
2057 bool "Fault-injection capability for disk IO"
2058 depends on FAULT_INJECTION && BLOCK
2059 help
2060 Provide fault-injection capability for disk IO.
2061
2062config FAIL_IO_TIMEOUT
2063 bool "Fault-injection capability for faking disk interrupts"
2064 depends on FAULT_INJECTION && BLOCK
2065 help
2066 Provide fault-injection capability on end IO handling. This
2067 will make the block layer "forget" an interrupt as configured,
2068 thus exercising the error handling.
2069
2070 Only works with drivers that use the generic timeout handling,
2071 for others it won't do anything.
2072
2073config FAIL_FUTEX
2074 bool "Fault-injection capability for futexes"
2075 select DEBUG_FS
2076 depends on FAULT_INJECTION && FUTEX
2077 help
2078 Provide fault-injection capability for futexes.
2079
2080config FAULT_INJECTION_DEBUG_FS
2081 bool "Debugfs entries for fault-injection capabilities"
2082 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
2083 help
2084 Enable configuration of fault-injection capabilities via debugfs.
2085
2086config FAIL_FUNCTION
2087 bool "Fault-injection capability for functions"
2088 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
2089 help
2090 Provide function-based fault-injection capability.
2091 This will allow you to override a specific function with a return
2092 with given return value. As a result, function caller will see
2093 an error value and have to handle it. This is useful to test the
2094 error handling in various subsystems.
2095
2096config FAIL_MMC_REQUEST
2097 bool "Fault-injection capability for MMC IO"
2098 depends on FAULT_INJECTION_DEBUG_FS && MMC
2099 help
2100 Provide fault-injection capability for MMC IO.
2101 This will make the mmc core return data errors. This is
2102 useful to test the error handling in the mmc block device
2103 and to test how the mmc host driver handles retries from
2104 the block device.
2105
2106config FAIL_SUNRPC
2107 bool "Fault-injection capability for SunRPC"
2108 depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG
2109 help
2110 Provide fault-injection capability for SunRPC and
2111 its consumers.
2112
2113config FAIL_SKB_REALLOC
2114 bool "Fault-injection capability forcing skb to reallocate"
2115 depends on FAULT_INJECTION_DEBUG_FS
2116 help
2117 Provide fault-injection capability that forces the skb to be
2118 reallocated, catching possible invalid pointers to the skb.
2119
2120 For more information, check
2121 Documentation/fault-injection/fault-injection.rst
2122
2123config FAULT_INJECTION_CONFIGFS
2124 bool "Configfs interface for fault-injection capabilities"
2125 depends on FAULT_INJECTION
2126 select CONFIGFS_FS
2127 help
2128 This option allows configfs-based drivers to dynamically configure
2129 fault-injection via configfs. Each parameter for driver-specific
2130 fault-injection can be made visible as a configfs attribute in a
2131 configfs group.
2132
2133
2134config FAULT_INJECTION_STACKTRACE_FILTER
2135 bool "stacktrace filter for fault-injection capabilities"
2136 depends on FAULT_INJECTION
2137 depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT
2138 select STACKTRACE
2139 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
2140 help
2141 Provide stacktrace filter for fault-injection capabilities
2142
2143config ARCH_HAS_KCOV
2144 bool
2145 help
2146 An architecture should select this when it can successfully
2147 build and run with CONFIG_KCOV. This typically requires
2148 disabling instrumentation for some early boot code.
2149
2150config KCOV
2151 bool "Code coverage for fuzzing"
2152 depends on ARCH_HAS_KCOV
2153 depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \
2154 GCC_VERSION >= 120000 || CC_IS_CLANG
2155 select DEBUG_FS
2156 select OBJTOOL if HAVE_NOINSTR_HACK
2157 help
2158 KCOV exposes kernel code coverage information in a form suitable
2159 for coverage-guided fuzzing (randomized testing).
2160
2161 For more details, see Documentation/dev-tools/kcov.rst.
2162
2163config KCOV_ENABLE_COMPARISONS
2164 bool "Enable comparison operands collection by KCOV"
2165 depends on KCOV
2166 depends on $(cc-option,-fsanitize-coverage=trace-cmp)
2167 help
2168 KCOV also exposes operands of every comparison in the instrumented
2169 code along with operand sizes and PCs of the comparison instructions.
2170 These operands can be used by fuzzing engines to improve the quality
2171 of fuzzing coverage.
2172
2173config KCOV_INSTRUMENT_ALL
2174 bool "Instrument all code by default"
2175 depends on KCOV
2176 default y
2177 help
2178 If you are doing generic system call fuzzing (like e.g. syzkaller),
2179 then you will want to instrument the whole kernel and you should
2180 say y here. If you are doing more targeted fuzzing (like e.g.
2181 filesystem fuzzing with AFL) then you will want to enable coverage
2182 for more specific subsets of files, and should say n here.
2183
2184config KCOV_IRQ_AREA_SIZE
2185 hex "Size of interrupt coverage collection area in words"
2186 depends on KCOV
2187 default 0x40000
2188 help
2189 KCOV uses preallocated per-cpu areas to collect coverage from
2190 soft interrupts. This specifies the size of those areas in the
2191 number of unsigned long words.
2192
2193config KCOV_SELFTEST
2194 bool "Perform short selftests on boot"
2195 depends on KCOV
2196 help
2197 Run short KCOV coverage collection selftests on boot.
2198 On test failure, causes the kernel to panic. Recommended to be
2199 enabled, ensuring critical functionality works as intended.
2200
2201menuconfig RUNTIME_TESTING_MENU
2202 bool "Runtime Testing"
2203 default y
2204
2205if RUNTIME_TESTING_MENU
2206
2207config TEST_DHRY
2208 tristate "Dhrystone benchmark test"
2209 help
2210 Enable this to include the Dhrystone 2.1 benchmark. This test
2211 calculates the number of Dhrystones per second, and the number of
2212 DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided
2213 by 1757 (the number of Dhrystones per second obtained on the VAX
2214 11/780, nominally a 1 MIPS machine).
2215
2216 To run the benchmark, it needs to be enabled explicitly, either from
2217 the kernel command line (when built-in), or from userspace (when
2218 built-in or modular).
2219
2220 Run once during kernel boot:
2221
2222 test_dhry.run
2223
2224 Set number of iterations from kernel command line:
2225
2226 test_dhry.iterations=<n>
2227
2228 Set number of iterations from userspace:
2229
2230 echo <n> > /sys/module/test_dhry/parameters/iterations
2231
2232 Trigger manual run from userspace:
2233
2234 echo y > /sys/module/test_dhry/parameters/run
2235
2236 If the number of iterations is <= 0, the test will devise a suitable
2237 number of iterations (test runs for at least 2s) automatically.
2238 This process takes ca. 4s.
2239
2240 If unsure, say N.
2241
2242config LKDTM
2243 tristate "Linux Kernel Dump Test Tool Module"
2244 depends on DEBUG_FS
2245 help
2246 This module enables testing of the different dumping mechanisms by
2247 inducing system failures at predefined crash points.
2248 If you don't need it: say N
2249 Choose M here to compile this code as a module. The module will be
2250 called lkdtm.
2251
2252 Documentation on how to use the module can be found in
2253 Documentation/fault-injection/provoke-crashes.rst
2254
2255config CPUMASK_KUNIT_TEST
2256 tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS
2257 depends on KUNIT
2258 default KUNIT_ALL_TESTS
2259 help
2260 Enable to turn on cpumask tests, running at boot or module load time.
2261
2262 For more information on KUnit and unit tests in general, please refer
2263 to the KUnit documentation in Documentation/dev-tools/kunit/.
2264
2265 If unsure, say N.
2266
2267config TEST_LIST_SORT
2268 tristate "Linked list sorting test" if !KUNIT_ALL_TESTS
2269 depends on KUNIT
2270 default KUNIT_ALL_TESTS
2271 help
2272 Enable this to turn on 'list_sort()' function test. This test is
2273 executed only once during system boot (so affects only boot time),
2274 or at module load time.
2275
2276 If unsure, say N.
2277
2278config TEST_MIN_HEAP
2279 tristate "Min heap test"
2280 depends on DEBUG_KERNEL || m
2281 help
2282 Enable this to turn on min heap function tests. This test is
2283 executed only once during system boot (so affects only boot time),
2284 or at module load time.
2285
2286 If unsure, say N.
2287
2288config TEST_SORT
2289 tristate "Array-based sort test" if !KUNIT_ALL_TESTS
2290 depends on KUNIT
2291 default KUNIT_ALL_TESTS
2292 help
2293 This option enables the self-test function of 'sort()' at boot,
2294 or at module load time.
2295
2296 If unsure, say N.
2297
2298config TEST_DIV64
2299 tristate "64bit/32bit division and modulo test"
2300 depends on DEBUG_KERNEL || m
2301 help
2302 Enable this to turn on 'do_div()' function test. This test is
2303 executed only once during system boot (so affects only boot time),
2304 or at module load time.
2305
2306 If unsure, say N.
2307
2308config TEST_MULDIV64
2309 tristate "mul_u64_u64_div_u64() test"
2310 depends on DEBUG_KERNEL || m
2311 help
2312 Enable this to turn on 'mul_u64_u64_div_u64()' function test.
2313 This test is executed only once during system boot (so affects
2314 only boot time), or at module load time.
2315
2316 If unsure, say N.
2317
2318config TEST_IOV_ITER
2319 tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS
2320 depends on KUNIT
2321 depends on MMU
2322 default KUNIT_ALL_TESTS
2323 help
2324 Enable this to turn on testing of the operation of the I/O iterator
2325 (iov_iter). This test is executed only once during system boot (so
2326 affects only boot time), or at module load time.
2327
2328 If unsure, say N.
2329
2330config KPROBES_SANITY_TEST
2331 tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS
2332 depends on DEBUG_KERNEL
2333 depends on KPROBES
2334 depends on KUNIT
2335 select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
2336 default KUNIT_ALL_TESTS
2337 help
2338 This option provides for testing basic kprobes functionality on
2339 boot. Samples of kprobe and kretprobe are inserted and
2340 verified for functionality.
2341
2342 Say N if you are unsure.
2343
2344config FPROBE_SANITY_TEST
2345 bool "Self test for fprobe"
2346 depends on DEBUG_KERNEL
2347 depends on FPROBE
2348 depends on KUNIT=y
2349 help
2350 This option will enable testing the fprobe when the system boot.
2351 A series of tests are made to verify that the fprobe is functioning
2352 properly.
2353
2354 Say N if you are unsure.
2355
2356config BACKTRACE_SELF_TEST
2357 tristate "Self test for the backtrace code"
2358 depends on DEBUG_KERNEL
2359 help
2360 This option provides a kernel module that can be used to test
2361 the kernel stack backtrace code. This option is not useful
2362 for distributions or general kernels, but only for kernel
2363 developers working on architecture code.
2364
2365 Note that if you want to also test saved backtraces, you will
2366 have to enable STACKTRACE as well.
2367
2368 Say N if you are unsure.
2369
2370config TEST_REF_TRACKER
2371 tristate "Self test for reference tracker"
2372 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
2373 select REF_TRACKER
2374 help
2375 This option provides a kernel module performing tests
2376 using reference tracker infrastructure.
2377
2378 Say N if you are unsure.
2379
2380config RBTREE_TEST
2381 tristate "Red-Black tree test"
2382 depends on DEBUG_KERNEL
2383 help
2384 A benchmark measuring the performance of the rbtree library.
2385 Also includes rbtree invariant checks.
2386
2387config REED_SOLOMON_TEST
2388 tristate "Reed-Solomon library test"
2389 depends on DEBUG_KERNEL || m
2390 select REED_SOLOMON
2391 select REED_SOLOMON_ENC16
2392 select REED_SOLOMON_DEC16
2393 help
2394 This option enables the self-test function of rslib at boot,
2395 or at module load time.
2396
2397 If unsure, say N.
2398
2399config INTERVAL_TREE_TEST
2400 tristate "Interval tree test"
2401 depends on DEBUG_KERNEL
2402 select INTERVAL_TREE
2403 help
2404 A benchmark measuring the performance of the interval tree library
2405
2406config PERCPU_TEST
2407 tristate "Per cpu operations test"
2408 depends on m && DEBUG_KERNEL
2409 help
2410 Enable this option to build test module which validates per-cpu
2411 operations.
2412
2413 If unsure, say N.
2414
2415config ATOMIC64_SELFTEST
2416 tristate "Perform an atomic64_t self-test"
2417 help
2418 Enable this option to test the atomic64_t functions at boot or
2419 at module load time.
2420
2421 If unsure, say N.
2422
2423config ASYNC_RAID6_TEST
2424 tristate "Self test for hardware accelerated raid6 recovery"
2425 depends on ASYNC_RAID6_RECOV
2426 select ASYNC_MEMCPY
2427 help
2428 This is a one-shot self test that permutes through the
2429 recovery of all the possible two disk failure scenarios for a
2430 N-disk array. Recovery is performed with the asynchronous
2431 raid6 recovery routines, and will optionally use an offload
2432 engine if one is available.
2433
2434 If unsure, say N.
2435
2436config TEST_HEXDUMP
2437 tristate "Test functions located in the hexdump module at runtime"
2438
2439config PRINTF_KUNIT_TEST
2440 tristate "KUnit test printf() family of functions at runtime" if !KUNIT_ALL_TESTS
2441 depends on KUNIT
2442 default KUNIT_ALL_TESTS
2443 help
2444 Enable this option to test the printf functions at runtime.
2445
2446 If unsure, say N.
2447
2448config SCANF_KUNIT_TEST
2449 tristate "KUnit test scanf() family of functions at runtime" if !KUNIT_ALL_TESTS
2450 depends on KUNIT
2451 default KUNIT_ALL_TESTS
2452 help
2453 Enable this option to test the scanf functions at runtime.
2454
2455 If unsure, say N.
2456
2457config SEQ_BUF_KUNIT_TEST
2458 tristate "KUnit test for seq_buf" if !KUNIT_ALL_TESTS
2459 depends on KUNIT
2460 default KUNIT_ALL_TESTS
2461 help
2462 This builds unit tests for the seq_buf library.
2463
2464 If unsure, say N.
2465
2466config STRING_KUNIT_TEST
2467 tristate "KUnit test string functions at runtime" if !KUNIT_ALL_TESTS
2468 depends on KUNIT
2469 default KUNIT_ALL_TESTS
2470
2471config STRING_HELPERS_KUNIT_TEST
2472 tristate "KUnit test string helpers at runtime" if !KUNIT_ALL_TESTS
2473 depends on KUNIT
2474 default KUNIT_ALL_TESTS
2475
2476config FFS_KUNIT_TEST
2477 tristate "KUnit test ffs-family functions at runtime" if !KUNIT_ALL_TESTS
2478 depends on KUNIT
2479 default KUNIT_ALL_TESTS
2480 help
2481 This builds KUnit tests for ffs-family bit manipulation functions
2482 including ffs(), __ffs(), fls(), __fls(), fls64(), and __ffs64().
2483
2484 These tests validate mathematical correctness, edge case handling,
2485 and cross-architecture consistency of bit scanning functions.
2486
2487 For more information on KUnit and unit tests in general,
2488 please refer to Documentation/dev-tools/kunit/.
2489
2490config TEST_KSTRTOX
2491 tristate "Test kstrto*() family of functions at runtime"
2492
2493config TEST_BITMAP
2494 tristate "Test bitmap_*() family of functions at runtime"
2495 help
2496 Enable this option to test the bitmap functions at boot.
2497
2498 If unsure, say N.
2499
2500config TEST_UUID
2501 tristate "Test functions located in the uuid module at runtime"
2502
2503config TEST_XARRAY
2504 tristate "Test the XArray code at runtime"
2505
2506config TEST_MAPLE_TREE
2507 tristate "Test the Maple Tree code at runtime or module load"
2508 help
2509 Enable this option to test the maple tree code functions at boot, or
2510 when the module is loaded. Enable "Debug Maple Trees" will enable
2511 more verbose output on failures.
2512
2513 If unsure, say N.
2514
2515config TEST_RHASHTABLE
2516 tristate "Perform selftest on resizable hash table"
2517 help
2518 Enable this option to test the rhashtable functions at boot.
2519
2520 If unsure, say N.
2521
2522config TEST_IDA
2523 tristate "Perform selftest on IDA functions"
2524
2525config TEST_MISC_MINOR
2526 bool "miscdevice KUnit test" if !KUNIT_ALL_TESTS
2527 depends on KUNIT=y
2528 default KUNIT_ALL_TESTS
2529 help
2530 Kunit test for miscdevice API, specially its behavior in respect to
2531 static and dynamic minor numbers.
2532
2533 KUnit tests run during boot and output the results to the debug log
2534 in TAP format (https://testanything.org/). Only useful for kernel devs
2535 running the KUnit test harness, and not intended for inclusion into a
2536 production build.
2537
2538 For more information on KUnit and unit tests in general please refer
2539 to the KUnit documentation in Documentation/dev-tools/kunit/.
2540
2541 If unsure, say N.
2542
2543config TEST_PARMAN
2544 tristate "Perform selftest on priority array manager"
2545 depends on PARMAN
2546 help
2547 Enable this option to test priority array manager on boot
2548 (or module load).
2549
2550 If unsure, say N.
2551
2552config TEST_IRQ_TIMINGS
2553 bool "IRQ timings selftest"
2554 depends on IRQ_TIMINGS
2555 help
2556 Enable this option to test the irq timings code on boot.
2557
2558 If unsure, say N.
2559
2560config TEST_LKM
2561 tristate "Test module loading with 'hello world' module"
2562 depends on m
2563 help
2564 This builds the "test_module" module that emits "Hello, world"
2565 on printk when loaded. It is designed to be used for basic
2566 evaluation of the module loading subsystem (for example when
2567 validating module verification). It lacks any extra dependencies,
2568 and will not normally be loaded by the system unless explicitly
2569 requested by name.
2570
2571 If unsure, say N.
2572
2573config TEST_BITOPS
2574 tristate "Test module for compilation of bitops operations"
2575 help
2576 This builds the "test_bitops" module that is much like the
2577 TEST_LKM module except that it does a basic exercise of the
2578 set/clear_bit macros and get_count_order/long to make sure there are
2579 no compiler warnings from C=1 sparse checker or -Wextra
2580 compilations. It has no dependencies and doesn't run or load unless
2581 explicitly requested by name. for example: modprobe test_bitops.
2582
2583 If unsure, say N.
2584
2585config TEST_VMALLOC
2586 tristate "Test module for stress/performance analysis of vmalloc allocator"
2587 default n
2588 depends on MMU
2589 help
2590 This builds the "test_vmalloc" module that should be used for
2591 stress and performance analysis. So, any new change for vmalloc
2592 subsystem can be evaluated from performance and stability point
2593 of view.
2594
2595 If unsure, say N.
2596
2597config TEST_BPF
2598 tristate "Test BPF filter functionality"
2599 depends on m && NET
2600 help
2601 This builds the "test_bpf" module that runs various test vectors
2602 against the BPF interpreter or BPF JIT compiler depending on the
2603 current setting. This is in particular useful for BPF JIT compiler
2604 development, but also to run regression tests against changes in
2605 the interpreter code. It also enables test stubs for eBPF maps and
2606 verifier used by user space verifier testsuite.
2607
2608 If unsure, say N.
2609
2610config FIND_BIT_BENCHMARK
2611 tristate "Test find_bit functions"
2612 help
2613 This builds the "test_find_bit" module that measure find_*_bit()
2614 functions performance.
2615
2616 If unsure, say N.
2617
2618config FIND_BIT_BENCHMARK_RUST
2619 tristate "Test find_bit functions in Rust"
2620 depends on RUST
2621 help
2622 This builds the "find_bit_benchmark_rust" module. It is a micro
2623 benchmark that measures the performance of Rust functions that
2624 correspond to the find_*_bit() operations in C. It follows the
2625 FIND_BIT_BENCHMARK closely but will in general not yield same
2626 numbers due to extra bounds checks and overhead of foreign
2627 function calls.
2628
2629 If unsure, say N.
2630
2631config TEST_FIRMWARE
2632 tristate "Test firmware loading via userspace interface"
2633 depends on FW_LOADER
2634 help
2635 This builds the "test_firmware" module that creates a userspace
2636 interface for testing firmware loading. This can be used to
2637 control the triggering of firmware loading without needing an
2638 actual firmware-using device. The contents can be rechecked by
2639 userspace.
2640
2641 If unsure, say N.
2642
2643config TEST_SYSCTL
2644 tristate "sysctl test driver"
2645 depends on PROC_SYSCTL
2646 help
2647 This builds the "test_sysctl" module. This driver enables to test the
2648 proc sysctl interfaces available to drivers safely without affecting
2649 production knobs which might alter system functionality.
2650
2651 If unsure, say N.
2652
2653config BITFIELD_KUNIT
2654 tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS
2655 depends on KUNIT
2656 default KUNIT_ALL_TESTS
2657 help
2658 Enable this option to test the bitfield functions at boot.
2659
2660 KUnit tests run during boot and output the results to the debug log
2661 in TAP format (http://testanything.org/). Only useful for kernel devs
2662 running the KUnit test harness, and not intended for inclusion into a
2663 production build.
2664
2665 For more information on KUnit and unit tests in general please refer
2666 to the KUnit documentation in Documentation/dev-tools/kunit/.
2667
2668 If unsure, say N.
2669
2670config CHECKSUM_KUNIT
2671 tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS
2672 depends on KUNIT
2673 default KUNIT_ALL_TESTS
2674 help
2675 Enable this option to test the checksum functions at boot.
2676
2677 KUnit tests run during boot and output the results to the debug log
2678 in TAP format (http://testanything.org/). Only useful for kernel devs
2679 running the KUnit test harness, and not intended for inclusion into a
2680 production build.
2681
2682 For more information on KUnit and unit tests in general please refer
2683 to the KUnit documentation in Documentation/dev-tools/kunit/.
2684
2685 If unsure, say N.
2686
2687config UTIL_MACROS_KUNIT
2688 tristate "KUnit test util_macros.h functions at runtime" if !KUNIT_ALL_TESTS
2689 depends on KUNIT
2690 default KUNIT_ALL_TESTS
2691 help
2692 Enable this option to test the util_macros.h function at boot.
2693
2694 KUnit tests run during boot and output the results to the debug log
2695 in TAP format (http://testanything.org/). Only useful for kernel devs
2696 running the KUnit test harness, and not intended for inclusion into a
2697 production build.
2698
2699 For more information on KUnit and unit tests in general please refer
2700 to the KUnit documentation in Documentation/dev-tools/kunit/.
2701
2702 If unsure, say N.
2703
2704config HASH_KUNIT_TEST
2705 tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS
2706 depends on KUNIT
2707 default KUNIT_ALL_TESTS
2708 help
2709 Enable this option to test the kernel's string (<linux/stringhash.h>), and
2710 integer (<linux/hash.h>) hash functions on boot.
2711
2712 KUnit tests run during boot and output the results to the debug log
2713 in TAP format (https://testanything.org/). Only useful for kernel devs
2714 running the KUnit test harness, and not intended for inclusion into a
2715 production build.
2716
2717 For more information on KUnit and unit tests in general please refer
2718 to the KUnit documentation in Documentation/dev-tools/kunit/.
2719
2720 This is intended to help people writing architecture-specific
2721 optimized versions. If unsure, say N.
2722
2723config RESOURCE_KUNIT_TEST
2724 tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS
2725 depends on KUNIT
2726 default KUNIT_ALL_TESTS
2727 select GET_FREE_REGION
2728 help
2729 This builds the resource API unit test.
2730 Tests the logic of API provided by resource.c and ioport.h.
2731 For more information on KUnit and unit tests in general please refer
2732 to the KUnit documentation in Documentation/dev-tools/kunit/.
2733
2734 If unsure, say N.
2735
2736config SYSCTL_KUNIT_TEST
2737 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS
2738 depends on KUNIT
2739 default KUNIT_ALL_TESTS
2740 help
2741 This builds the proc sysctl unit test, which runs on boot.
2742 Tests the API contract and implementation correctness of sysctl.
2743 For more information on KUnit and unit tests in general please refer
2744 to the KUnit documentation in Documentation/dev-tools/kunit/.
2745
2746 If unsure, say N.
2747
2748config KFIFO_KUNIT_TEST
2749 tristate "KUnit Test for the generic kernel FIFO implementation" if !KUNIT_ALL_TESTS
2750 depends on KUNIT
2751 default KUNIT_ALL_TESTS
2752 help
2753 This builds the generic FIFO implementation KUnit test suite.
2754 It tests that the API and basic functionality of the kfifo type
2755 and associated macros.
2756
2757 For more information on KUnit and unit tests in general please refer
2758 to the KUnit documentation in Documentation/dev-tools/kunit/.
2759
2760 If unsure, say N.
2761
2762config LIST_KUNIT_TEST
2763 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS
2764 depends on KUNIT
2765 default KUNIT_ALL_TESTS
2766 help
2767 This builds the linked list KUnit test suite.
2768 It tests that the API and basic functionality of the list_head type
2769 and associated macros.
2770
2771 KUnit tests run during boot and output the results to the debug log
2772 in TAP format (https://testanything.org/). Only useful for kernel devs
2773 running the KUnit test harness, and not intended for inclusion into a
2774 production build.
2775
2776 For more information on KUnit and unit tests in general please refer
2777 to the KUnit documentation in Documentation/dev-tools/kunit/.
2778
2779 If unsure, say N.
2780
2781config HASHTABLE_KUNIT_TEST
2782 tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS
2783 depends on KUNIT
2784 default KUNIT_ALL_TESTS
2785 help
2786 This builds the hashtable KUnit test suite.
2787 It tests the basic functionality of the API defined in
2788 include/linux/hashtable.h. For more information on KUnit and
2789 unit tests in general please refer to the KUnit documentation
2790 in Documentation/dev-tools/kunit/.
2791
2792 If unsure, say N.
2793
2794config LINEAR_RANGES_TEST
2795 tristate "KUnit test for linear_ranges"
2796 depends on KUNIT
2797 select LINEAR_RANGES
2798 help
2799 This builds the linear_ranges unit test, which runs on boot.
2800 Tests the linear_ranges logic correctness.
2801 For more information on KUnit and unit tests in general please refer
2802 to the KUnit documentation in Documentation/dev-tools/kunit/.
2803
2804 If unsure, say N.
2805
2806config CMDLINE_KUNIT_TEST
2807 tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS
2808 depends on KUNIT
2809 default KUNIT_ALL_TESTS
2810 help
2811 This builds the cmdline API unit test.
2812 Tests the logic of API provided by cmdline.c.
2813 For more information on KUnit and unit tests in general please refer
2814 to the KUnit documentation in Documentation/dev-tools/kunit/.
2815
2816 If unsure, say N.
2817
2818config BITS_TEST
2819 tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS
2820 depends on KUNIT
2821 default KUNIT_ALL_TESTS
2822 help
2823 This builds the bits unit test.
2824 Tests the logic of macros defined in bits.h.
2825 For more information on KUnit and unit tests in general please refer
2826 to the KUnit documentation in Documentation/dev-tools/kunit/.
2827
2828 If unsure, say N.
2829
2830config SLUB_KUNIT_TEST
2831 tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS
2832 depends on SLUB_DEBUG && KUNIT
2833 default KUNIT_ALL_TESTS
2834 help
2835 This builds SLUB allocator unit test.
2836 Tests SLUB cache debugging functionality.
2837 For more information on KUnit and unit tests in general please refer
2838 to the KUnit documentation in Documentation/dev-tools/kunit/.
2839
2840 If unsure, say N.
2841
2842config RATIONAL_KUNIT_TEST
2843 tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS
2844 depends on KUNIT && RATIONAL
2845 default KUNIT_ALL_TESTS
2846 help
2847 This builds the rational math unit test.
2848 For more information on KUnit and unit tests in general please refer
2849 to the KUnit documentation in Documentation/dev-tools/kunit/.
2850
2851 If unsure, say N.
2852
2853config MEMCPY_KUNIT_TEST
2854 tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS
2855 depends on KUNIT
2856 default KUNIT_ALL_TESTS
2857 help
2858 Builds unit tests for memcpy(), memmove(), and memset() functions.
2859 For more information on KUnit and unit tests in general please refer
2860 to the KUnit documentation in Documentation/dev-tools/kunit/.
2861
2862 If unsure, say N.
2863
2864config IS_SIGNED_TYPE_KUNIT_TEST
2865 tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS
2866 depends on KUNIT
2867 default KUNIT_ALL_TESTS
2868 help
2869 Builds unit tests for the is_signed_type() macro.
2870
2871 For more information on KUnit and unit tests in general please refer
2872 to the KUnit documentation in Documentation/dev-tools/kunit/.
2873
2874 If unsure, say N.
2875
2876config OVERFLOW_KUNIT_TEST
2877 tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS
2878 depends on KUNIT
2879 default KUNIT_ALL_TESTS
2880 help
2881 Builds unit tests for the check_*_overflow(), size_*(), allocation, and
2882 related functions.
2883
2884 For more information on KUnit and unit tests in general please refer
2885 to the KUnit documentation in Documentation/dev-tools/kunit/.
2886
2887 If unsure, say N.
2888
2889config RANDSTRUCT_KUNIT_TEST
2890 tristate "Test randstruct structure layout randomization at runtime" if !KUNIT_ALL_TESTS
2891 depends on KUNIT
2892 default KUNIT_ALL_TESTS
2893 help
2894 Builds unit tests for the checking CONFIG_RANDSTRUCT=y, which
2895 randomizes structure layouts.
2896
2897config STACKINIT_KUNIT_TEST
2898 tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS
2899 depends on KUNIT
2900 default KUNIT_ALL_TESTS
2901 help
2902 Test if the kernel is zero-initializing stack variables and
2903 padding. Coverage is controlled by compiler flags,
2904 CONFIG_INIT_STACK_ALL_PATTERN or CONFIG_INIT_STACK_ALL_ZERO.
2905
2906config FORTIFY_KUNIT_TEST
2907 tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS
2908 depends on KUNIT
2909 default KUNIT_ALL_TESTS
2910 help
2911 Builds unit tests for checking internals of FORTIFY_SOURCE as used
2912 by the str*() and mem*() family of functions. For testing runtime
2913 traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests.
2914
2915config LONGEST_SYM_KUNIT_TEST
2916 tristate "Test the longest symbol possible" if !KUNIT_ALL_TESTS
2917 depends on KUNIT && KPROBES
2918 depends on !PREFIX_SYMBOLS && !CFI && !GCOV_KERNEL
2919 default KUNIT_ALL_TESTS
2920 help
2921 Tests the longest symbol possible
2922
2923 If unsure, say N.
2924
2925config HW_BREAKPOINT_KUNIT_TEST
2926 bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS
2927 depends on HAVE_HW_BREAKPOINT
2928 depends on KUNIT=y
2929 default KUNIT_ALL_TESTS
2930 help
2931 Tests for hw_breakpoint constraints accounting.
2932
2933 If unsure, say N.
2934
2935config SIPHASH_KUNIT_TEST
2936 tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS
2937 depends on KUNIT
2938 default KUNIT_ALL_TESTS
2939 help
2940 Enable this option to test the kernel's siphash (<linux/siphash.h>) hash
2941 functions on boot (or module load).
2942
2943 This is intended to help people writing architecture-specific
2944 optimized versions. If unsure, say N.
2945
2946config USERCOPY_KUNIT_TEST
2947 tristate "KUnit Test for user/kernel boundary protections"
2948 depends on KUNIT
2949 default KUNIT_ALL_TESTS
2950 help
2951 This builds the "usercopy_kunit" module that runs sanity checks
2952 on the copy_to/from_user infrastructure, making sure basic
2953 user/kernel boundary testing is working.
2954
2955config BLACKHOLE_DEV_KUNIT_TEST
2956 tristate "Test blackhole netdev functionality" if !KUNIT_ALL_TESTS
2957 depends on NET
2958 depends on KUNIT
2959 default KUNIT_ALL_TESTS
2960 help
2961 This builds the "blackhole_dev_kunit" module that validates the
2962 data path through this blackhole netdev.
2963
2964 If unsure, say N.
2965
2966config TEST_UDELAY
2967 tristate "udelay test driver"
2968 help
2969 This builds the "udelay_test" module that helps to make sure
2970 that udelay() is working properly.
2971
2972 If unsure, say N.
2973
2974config TEST_STATIC_KEYS
2975 tristate "Test static keys"
2976 depends on m
2977 help
2978 Test the static key interfaces.
2979
2980 If unsure, say N.
2981
2982config TEST_DYNAMIC_DEBUG
2983 tristate "Test DYNAMIC_DEBUG"
2984 depends on DYNAMIC_DEBUG
2985 help
2986 This module registers a tracer callback to count enabled
2987 pr_debugs in a 'do_debugging' function, then alters their
2988 enablements, calls the function, and compares counts.
2989
2990 If unsure, say N.
2991
2992config TEST_KMOD
2993 tristate "kmod stress tester"
2994 depends on m
2995 select TEST_LKM
2996 help
2997 Test the kernel's module loading mechanism: kmod. kmod implements
2998 support to load modules using the Linux kernel's usermode helper.
2999 This test provides a series of tests against kmod.
3000
3001 Although technically you can either build test_kmod as a module or
3002 into the kernel we disallow building it into the kernel since
3003 it stress tests request_module() and this will very likely cause
3004 some issues by taking over precious threads available from other
3005 module load requests, ultimately this could be fatal.
3006
3007 To run tests run:
3008
3009 tools/testing/selftests/kmod/kmod.sh --help
3010
3011 If unsure, say N.
3012
3013config TEST_RUNTIME
3014 bool
3015
3016config TEST_RUNTIME_MODULE
3017 bool
3018
3019config TEST_KALLSYMS
3020 tristate "module kallsyms find_symbol() test"
3021 depends on m
3022 select TEST_RUNTIME
3023 select TEST_RUNTIME_MODULE
3024 select TEST_KALLSYMS_A
3025 select TEST_KALLSYMS_B
3026 select TEST_KALLSYMS_C
3027 select TEST_KALLSYMS_D
3028 help
3029 This allows us to stress test find_symbol() through the kallsyms
3030 used to place symbols on the kernel ELF kallsyms and modules kallsyms
3031 where we place kernel symbols such as exported symbols.
3032
3033 We have four test modules:
3034
3035 A: has KALLSYSMS_NUMSYMS exported symbols
3036 B: uses one of A's symbols
3037 C: adds KALLSYMS_SCALE_FACTOR * KALLSYSMS_NUMSYMS exported
3038 D: adds 2 * the symbols than C
3039
3040 We stress test find_symbol() through two means:
3041
3042 1) Upon load of B it will trigger simplify_symbols() to look for the
3043 one symbol it uses from the module A with tons of symbols. This is an
3044 indirect way for us to have B call resolve_symbol_wait() upon module
3045 load. This will eventually call find_symbol() which will eventually
3046 try to find the symbols used with find_exported_symbol_in_section().
3047 find_exported_symbol_in_section() uses bsearch() so a binary search
3048 for each symbol. Binary search will at worst be O(log(n)) so the
3049 larger TEST_MODULE_KALLSYSMS the worse the search.
3050
3051 2) The selftests should load C first, before B. Upon B's load towards
3052 the end right before we call module B's init routine we get
3053 complete_formation() called on the module. That will first check
3054 for duplicate symbols with the call to verify_exported_symbols().
3055 That is when we'll force iteration on module C's insane symbol list.
3056 Since it has 10 * KALLSYMS_NUMSYMS it means we can first test
3057 just loading B without C. The amount of time it takes to load C Vs
3058 B can give us an idea of the impact growth of the symbol space and
3059 give us projection. Module A only uses one symbol from B so to allow
3060 this scaling in module C to be proportional, if it used more symbols
3061 then the first test would be doing more and increasing just the
3062 search space would be slightly different. The last module, module D
3063 will just increase the search space by twice the number of symbols in
3064 C so to allow for full projects.
3065
3066 tools/testing/selftests/module/find_symbol.sh
3067
3068 The current defaults will incur a build delay of about 7 minutes
3069 on an x86_64 with only 8 cores. Enable this only if you want to
3070 stress test find_symbol() with thousands of symbols. At the same
3071 time this is also useful to test building modules with thousands of
3072 symbols, and if BTF is enabled this also stress tests adding BTF
3073 information for each module. Currently enabling many more symbols
3074 will segfault the build system.
3075
3076 If unsure, say N.
3077
3078if TEST_KALLSYMS
3079
3080config TEST_KALLSYMS_A
3081 tristate
3082 depends on m
3083
3084config TEST_KALLSYMS_B
3085 tristate
3086 depends on m
3087
3088config TEST_KALLSYMS_C
3089 tristate
3090 depends on m
3091
3092config TEST_KALLSYMS_D
3093 tristate
3094 depends on m
3095
3096choice
3097 prompt "Kallsym test range"
3098 default TEST_KALLSYMS_LARGE
3099 help
3100 Selecting something other than "Fast" will enable tests which slow
3101 down the build and may crash your build.
3102
3103config TEST_KALLSYMS_FAST
3104 bool "Fast builds"
3105 help
3106 You won't really be testing kallsysms, so this just helps fast builds
3107 when allmodconfig is used..
3108
3109config TEST_KALLSYMS_LARGE
3110 bool "Enable testing kallsyms with large exports"
3111 help
3112 This will enable larger number of symbols. This will slow down
3113 your build considerably.
3114
3115config TEST_KALLSYMS_MAX
3116 bool "Known kallsysms limits"
3117 help
3118 This will enable exports to the point we know we'll start crashing
3119 builds.
3120
3121endchoice
3122
3123config TEST_KALLSYMS_NUMSYMS
3124 int "test kallsyms number of symbols"
3125 range 2 10000
3126 default 2 if TEST_KALLSYMS_FAST
3127 default 100 if TEST_KALLSYMS_LARGE
3128 default 10000 if TEST_KALLSYMS_MAX
3129 help
3130 The number of symbols to create on TEST_KALLSYMS_A, only one of which
3131 module TEST_KALLSYMS_B will use. This also will be used
3132 for how many symbols TEST_KALLSYMS_C will have, scaled up by
3133 TEST_KALLSYMS_SCALE_FACTOR. Note that setting this to 10,000 will
3134 trigger a segfault today, don't use anything close to it unless
3135 you are aware that this should not be used for automated build tests.
3136
3137config TEST_KALLSYMS_SCALE_FACTOR
3138 int "test kallsyms scale factor"
3139 default 8
3140 help
3141 How many more unusued symbols will TEST_KALLSYSMS_C have than
3142 TEST_KALLSYMS_A. If 8, then module C will have 8 * syms
3143 than module A. Then TEST_KALLSYMS_D will have double the amount
3144 of symbols than C so to allow projections.
3145
3146endif # TEST_KALLSYMS
3147
3148config TEST_DEBUG_VIRTUAL
3149 tristate "Test CONFIG_DEBUG_VIRTUAL feature"
3150 depends on DEBUG_VIRTUAL
3151 help
3152 Test the kernel's ability to detect incorrect calls to
3153 virt_to_phys() done against the non-linear part of the
3154 kernel's virtual address map.
3155
3156 If unsure, say N.
3157
3158config TEST_MEMCAT_P
3159 tristate "Test memcat_p() helper function"
3160 help
3161 Test the memcat_p() helper for correctly merging two
3162 pointer arrays together.
3163
3164 If unsure, say N.
3165
3166config TEST_OBJAGG
3167 tristate "Perform selftest on object aggreration manager"
3168 default n
3169 depends on OBJAGG
3170 help
3171 Enable this option to test object aggregation manager on boot
3172 (or module load).
3173
3174config TEST_MEMINIT
3175 tristate "Test heap/page initialization"
3176 help
3177 Test if the kernel is zero-initializing heap and page allocations.
3178 This can be useful to test init_on_alloc and init_on_free features.
3179
3180 If unsure, say N.
3181
3182config TEST_HMM
3183 tristate "Test HMM (Heterogeneous Memory Management)"
3184 depends on TRANSPARENT_HUGEPAGE
3185 depends on DEVICE_PRIVATE
3186 select HMM_MIRROR
3187 select MMU_NOTIFIER
3188 help
3189 This is a pseudo device driver solely for testing HMM.
3190 Say M here if you want to build the HMM test module.
3191 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests.
3192
3193 If unsure, say N.
3194
3195config TEST_FREE_PAGES
3196 tristate "Test freeing pages"
3197 help
3198 Test that a memory leak does not occur due to a race between
3199 freeing a block of pages and a speculative page reference.
3200 Loading this module is safe if your kernel has the bug fixed.
3201 If the bug is not fixed, it will leak gigabytes of memory and
3202 probably OOM your system.
3203
3204config TEST_FPU
3205 tristate "Test floating point operations in kernel space"
3206 depends on ARCH_HAS_KERNEL_FPU_SUPPORT && !KCOV_INSTRUMENT_ALL
3207 help
3208 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu
3209 which will trigger a sequence of floating point operations. This is used
3210 for self-testing floating point control register setting in
3211 kernel_fpu_begin().
3212
3213 If unsure, say N.
3214
3215config TEST_CLOCKSOURCE_WATCHDOG
3216 tristate "Test clocksource watchdog in kernel space"
3217 depends on CLOCKSOURCE_WATCHDOG
3218 help
3219 Enable this option to create a kernel module that will trigger
3220 a test of the clocksource watchdog. This module may be loaded
3221 via modprobe or insmod in which case it will run upon being
3222 loaded, or it may be built in, in which case it will run
3223 shortly after boot.
3224
3225 If unsure, say N.
3226
3227config TEST_OBJPOOL
3228 tristate "Test module for correctness and stress of objpool"
3229 default n
3230 depends on m && DEBUG_KERNEL
3231 help
3232 This builds the "test_objpool" module that should be used for
3233 correctness verification and concurrent testings of objects
3234 allocation and reclamation.
3235
3236 If unsure, say N.
3237
3238config TEST_KEXEC_HANDOVER
3239 bool "Test for Kexec HandOver"
3240 default n
3241 depends on KEXEC_HANDOVER
3242 help
3243 This option enables test for Kexec HandOver (KHO).
3244 The test consists of two parts: saving kernel data before kexec and
3245 restoring the data after kexec and verifying that it was properly
3246 handed over. This test module creates and saves data on the boot of
3247 the first kernel and restores and verifies the data on the boot of
3248 kexec'ed kernel.
3249
3250 For detailed documentation about KHO, see Documentation/core-api/kho.
3251
3252 To run the test run:
3253
3254 tools/testing/selftests/kho/vmtest.sh -h
3255
3256 If unsure, say N.
3257
3258config RATELIMIT_KUNIT_TEST
3259 tristate "KUnit Test for correctness and stress of ratelimit" if !KUNIT_ALL_TESTS
3260 depends on KUNIT
3261 default KUNIT_ALL_TESTS
3262 help
3263 This builds the "test_ratelimit" module that should be used
3264 for correctness verification and concurrent testings of rate
3265 limiting.
3266
3267 If unsure, say N.
3268
3269config INT_POW_KUNIT_TEST
3270 tristate "Integer exponentiation (int_pow) test" if !KUNIT_ALL_TESTS
3271 depends on KUNIT
3272 default KUNIT_ALL_TESTS
3273 help
3274 This option enables the KUnit test suite for the int_pow function,
3275 which performs integer exponentiation. The test suite is designed to
3276 verify that the implementation of int_pow correctly computes the power
3277 of a given base raised to a given exponent.
3278
3279 Enabling this option will include tests that check various scenarios
3280 and edge cases to ensure the accuracy and reliability of the exponentiation
3281 function.
3282
3283 If unsure, say N
3284
3285config INT_SQRT_KUNIT_TEST
3286 tristate "Integer square root test" if !KUNIT_ALL_TESTS
3287 depends on KUNIT
3288 default KUNIT_ALL_TESTS
3289 help
3290 This option enables the KUnit test suite for the int_sqrt() function,
3291 which performs square root calculation. The test suite checks
3292 various scenarios, including edge cases, to ensure correctness.
3293
3294 Enabling this option will include tests that check various scenarios
3295 and edge cases to ensure the accuracy and reliability of the square root
3296 function.
3297
3298 If unsure, say N
3299
3300config INT_LOG_KUNIT_TEST
3301 tristate "Integer log (int_log) test" if !KUNIT_ALL_TESTS
3302 depends on KUNIT
3303 default KUNIT_ALL_TESTS
3304 help
3305 This option enables the KUnit test suite for the int_log library, which
3306 provides two functions to compute the integer logarithm in base 2 and
3307 base 10, called respectively as intlog2 and intlog10.
3308
3309 If unsure, say N
3310
3311config GCD_KUNIT_TEST
3312 tristate "Greatest common divisor test" if !KUNIT_ALL_TESTS
3313 depends on KUNIT
3314 default KUNIT_ALL_TESTS
3315 help
3316 This option enables the KUnit test suite for the gcd() function,
3317 which computes the greatest common divisor of two numbers.
3318
3319 This test suite verifies the correctness of gcd() across various
3320 scenarios, including edge cases.
3321
3322 If unsure, say N
3323
3324config PRIME_NUMBERS_KUNIT_TEST
3325 tristate "Prime number generator test" if !KUNIT_ALL_TESTS
3326 depends on KUNIT
3327 depends on PRIME_NUMBERS
3328 default KUNIT_ALL_TESTS
3329 help
3330 This option enables the KUnit test suite for the {is,next}_prime_number
3331 functions.
3332
3333 Enabling this option will include tests that compare the prime number
3334 generator functions against a brute force implementation.
3335
3336 If unsure, say N
3337
3338endif # RUNTIME_TESTING_MENU
3339
3340config ARCH_USE_MEMTEST
3341 bool
3342 help
3343 An architecture should select this when it uses early_memtest()
3344 during boot process.
3345
3346config MEMTEST
3347 bool "Memtest"
3348 depends on ARCH_USE_MEMTEST
3349 help
3350 This option adds a kernel parameter 'memtest', which allows memtest
3351 to be set and executed.
3352 memtest=0, mean disabled; -- default
3353 memtest=1, mean do 1 test pattern;
3354 ...
3355 memtest=17, mean do 17 test patterns.
3356 If you are unsure how to answer this question, answer N.
3357
3358
3359
3360config HYPERV_TESTING
3361 bool "Microsoft Hyper-V driver testing"
3362 default n
3363 depends on HYPERV && DEBUG_FS
3364 help
3365 Select this option to enable Hyper-V vmbus testing.
3366
3367endmenu # "Kernel Testing and Coverage"
3368
3369menu "Rust hacking"
3370
3371config RUST_DEBUG_ASSERTIONS
3372 bool "Debug assertions"
3373 depends on RUST
3374 help
3375 Enables rustc's `-Cdebug-assertions` codegen option.
3376
3377 This flag lets you turn `cfg(debug_assertions)` conditional
3378 compilation on or off. This can be used to enable extra debugging
3379 code in development but not in production. For example, it controls
3380 the behavior of the standard library's `debug_assert!` macro.
3381
3382 Note that this will apply to all Rust code, including `core`.
3383
3384 If unsure, say N.
3385
3386config RUST_OVERFLOW_CHECKS
3387 bool "Overflow checks"
3388 default y
3389 depends on RUST
3390 help
3391 Enables rustc's `-Coverflow-checks` codegen option.
3392
3393 This flag allows you to control the behavior of runtime integer
3394 overflow. When overflow-checks are enabled, a Rust panic will occur
3395 on overflow.
3396
3397 Note that this will apply to all Rust code, including `core`.
3398
3399 If unsure, say Y.
3400
3401config RUST_BUILD_ASSERT_ALLOW
3402 bool "Allow unoptimized build-time assertions"
3403 depends on RUST
3404 help
3405 Controls how `build_error!` and `build_assert!` are handled during the build.
3406
3407 If calls to them exist in the binary, it may indicate a violated invariant
3408 or that the optimizer failed to verify the invariant during compilation.
3409
3410 This should not happen, thus by default the build is aborted. However,
3411 as an escape hatch, you can choose Y here to ignore them during build
3412 and let the check be carried at runtime (with `panic!` being called if
3413 the check fails).
3414
3415 If unsure, say N.
3416
3417config RUST_KERNEL_DOCTESTS
3418 bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS
3419 depends on RUST && KUNIT=y
3420 default KUNIT_ALL_TESTS
3421 help
3422 This builds the documentation tests of the `kernel` crate
3423 as KUnit tests.
3424
3425 For more information on KUnit and unit tests in general,
3426 please refer to the KUnit documentation in Documentation/dev-tools/kunit/.
3427
3428 If unsure, say N.
3429
3430endmenu # "Rust"
3431
3432endmenu # Kernel hacking