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1# SPDX-License-Identifier: GPL-2.0-only
2menu "Kernel hacking"
3
4menu "printk and dmesg options"
5
6config PRINTK_TIME
7 bool "Show timing information on printks"
8 depends on PRINTK
9 help
10 Selecting this option causes time stamps of the printk()
11 messages to be added to the output of the syslog() system
12 call and at the console.
13
14 The timestamp is always recorded internally, and exported
15 to /dev/kmsg. This flag just specifies if the timestamp should
16 be included, not that the timestamp is recorded.
17
18 The behavior is also controlled by the kernel command line
19 parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst
20
21config PRINTK_CALLER
22 bool "Show caller information on printks"
23 depends on PRINTK
24 help
25 Selecting this option causes printk() to add a caller "thread id" (if
26 in task context) or a caller "processor id" (if not in task context)
27 to every message.
28
29 This option is intended for environments where multiple threads
30 concurrently call printk() for many times, for it is difficult to
31 interpret without knowing where these lines (or sometimes individual
32 line which was divided into multiple lines due to race) came from.
33
34 Since toggling after boot makes the code racy, currently there is
35 no option to enable/disable at the kernel command line parameter or
36 sysfs interface.
37
38config STACKTRACE_BUILD_ID
39 bool "Show build ID information in stacktraces"
40 depends on PRINTK
41 help
42 Selecting this option adds build ID information for symbols in
43 stacktraces printed with the printk format '%p[SR]b'.
44
45 This option is intended for distros where debuginfo is not easily
46 accessible but can be downloaded given the build ID of the vmlinux or
47 kernel module where the function is located.
48
49config CONSOLE_LOGLEVEL_DEFAULT
50 int "Default console loglevel (1-15)"
51 range 1 15
52 default "7"
53 help
54 Default loglevel to determine what will be printed on the console.
55
56 Setting a default here is equivalent to passing in loglevel=<x> in
57 the kernel bootargs. loglevel=<x> continues to override whatever
58 value is specified here as well.
59
60 Note: This does not affect the log level of un-prefixed printk()
61 usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT
62 option.
63
64config CONSOLE_LOGLEVEL_QUIET
65 int "quiet console loglevel (1-15)"
66 range 1 15
67 default "4"
68 help
69 loglevel to use when "quiet" is passed on the kernel commandline.
70
71 When "quiet" is passed on the kernel commandline this loglevel
72 will be used as the loglevel. IOW passing "quiet" will be the
73 equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>"
74
75config MESSAGE_LOGLEVEL_DEFAULT
76 int "Default message log level (1-7)"
77 range 1 7
78 default "4"
79 help
80 Default log level for printk statements with no specified priority.
81
82 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
83 that are auditing their logs closely may want to set it to a lower
84 priority.
85
86 Note: This does not affect what message level gets printed on the console
87 by default. To change that, use loglevel=<x> in the kernel bootargs,
88 or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value.
89
90config BOOT_PRINTK_DELAY
91 bool "Delay each boot printk message by N milliseconds"
92 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
93 help
94 This build option allows you to read kernel boot messages
95 by inserting a short delay after each one. The delay is
96 specified in milliseconds on the kernel command line,
97 using "boot_delay=N".
98
99 It is likely that you would also need to use "lpj=M" to preset
100 the "loops per jiffy" value.
101 See a previous boot log for the "lpj" value to use for your
102 system, and then set "lpj=M" before setting "boot_delay=N".
103 NOTE: Using this option may adversely affect SMP systems.
104 I.e., processors other than the first one may not boot up.
105 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
106 what it believes to be lockup conditions.
107
108config DYNAMIC_DEBUG
109 bool "Enable dynamic printk() support"
110 default n
111 depends on PRINTK
112 depends on (DEBUG_FS || PROC_FS)
113 select DYNAMIC_DEBUG_CORE
114 help
115
116 Compiles debug level messages into the kernel, which would not
117 otherwise be available at runtime. These messages can then be
118 enabled/disabled based on various levels of scope - per source file,
119 function, module, format string, and line number. This mechanism
120 implicitly compiles in all pr_debug() and dev_dbg() calls, which
121 enlarges the kernel text size by about 2%.
122
123 If a source file is compiled with DEBUG flag set, any
124 pr_debug() calls in it are enabled by default, but can be
125 disabled at runtime as below. Note that DEBUG flag is
126 turned on by many CONFIG_*DEBUG* options.
127
128 Usage:
129
130 Dynamic debugging is controlled via the 'dynamic_debug/control' file,
131 which is contained in the 'debugfs' filesystem or procfs.
132 Thus, the debugfs or procfs filesystem must first be mounted before
133 making use of this feature.
134 We refer the control file as: <debugfs>/dynamic_debug/control. This
135 file contains a list of the debug statements that can be enabled. The
136 format for each line of the file is:
137
138 filename:lineno [module]function flags format
139
140 filename : source file of the debug statement
141 lineno : line number of the debug statement
142 module : module that contains the debug statement
143 function : function that contains the debug statement
144 flags : '=p' means the line is turned 'on' for printing
145 format : the format used for the debug statement
146
147 From a live system:
148
149 nullarbor:~ # cat <debugfs>/dynamic_debug/control
150 # filename:lineno [module]function flags format
151 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
152 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
153 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
154
155 Example usage:
156
157 // enable the message at line 1603 of file svcsock.c
158 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
159 <debugfs>/dynamic_debug/control
160
161 // enable all the messages in file svcsock.c
162 nullarbor:~ # echo -n 'file svcsock.c +p' >
163 <debugfs>/dynamic_debug/control
164
165 // enable all the messages in the NFS server module
166 nullarbor:~ # echo -n 'module nfsd +p' >
167 <debugfs>/dynamic_debug/control
168
169 // enable all 12 messages in the function svc_process()
170 nullarbor:~ # echo -n 'func svc_process +p' >
171 <debugfs>/dynamic_debug/control
172
173 // disable all 12 messages in the function svc_process()
174 nullarbor:~ # echo -n 'func svc_process -p' >
175 <debugfs>/dynamic_debug/control
176
177 See Documentation/admin-guide/dynamic-debug-howto.rst for additional
178 information.
179
180config DYNAMIC_DEBUG_CORE
181 bool "Enable core function of dynamic debug support"
182 depends on PRINTK
183 depends on (DEBUG_FS || PROC_FS)
184 help
185 Enable core functional support of dynamic debug. It is useful
186 when you want to tie dynamic debug to your kernel modules with
187 DYNAMIC_DEBUG_MODULE defined for each of them, especially for
188 the case of embedded system where the kernel image size is
189 sensitive for people.
190
191config SYMBOLIC_ERRNAME
192 bool "Support symbolic error names in printf"
193 default y if PRINTK
194 help
195 If you say Y here, the kernel's printf implementation will
196 be able to print symbolic error names such as ENOSPC instead
197 of the number 28. It makes the kernel image slightly larger
198 (about 3KB), but can make the kernel logs easier to read.
199
200config DEBUG_BUGVERBOSE
201 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
202 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
203 default y
204 help
205 Say Y here to make BUG() panics output the file name and line number
206 of the BUG call as well as the EIP and oops trace. This aids
207 debugging but costs about 70-100K of memory.
208
209endmenu # "printk and dmesg options"
210
211config DEBUG_KERNEL
212 bool "Kernel debugging"
213 help
214 Say Y here if you are developing drivers or trying to debug and
215 identify kernel problems.
216
217config DEBUG_MISC
218 bool "Miscellaneous debug code"
219 default DEBUG_KERNEL
220 depends on DEBUG_KERNEL
221 help
222 Say Y here if you need to enable miscellaneous debug code that should
223 be under a more specific debug option but isn't.
224
225menu "Compile-time checks and compiler options"
226
227config DEBUG_INFO
228 bool
229 help
230 A kernel debug info option other than "None" has been selected
231 in the "Debug information" choice below, indicating that debug
232 information will be generated for build targets.
233
234# Clang generates .uleb128 with label differences for DWARF v5, a feature that
235# older binutils ports do not support when utilizing RISC-V style linker
236# relaxation: https://sourceware.org/bugzilla/show_bug.cgi?id=27215
237config AS_HAS_NON_CONST_ULEB128
238 def_bool $(as-instr,.uleb128 .Lexpr_end4 - .Lexpr_start3\n.Lexpr_start3:\n.Lexpr_end4:)
239
240choice
241 prompt "Debug information"
242 depends on DEBUG_KERNEL
243 help
244 Selecting something other than "None" results in a kernel image
245 that will include debugging info resulting in a larger kernel image.
246 This adds debug symbols to the kernel and modules (gcc -g), and
247 is needed if you intend to use kernel crashdump or binary object
248 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
249
250 Choose which version of DWARF debug info to emit. If unsure,
251 select "Toolchain default".
252
253config DEBUG_INFO_NONE
254 bool "Disable debug information"
255 help
256 Do not build the kernel with debugging information, which will
257 result in a faster and smaller build.
258
259config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
260 bool "Rely on the toolchain's implicit default DWARF version"
261 select DEBUG_INFO
262 depends on !CC_IS_CLANG || AS_IS_LLVM || CLANG_VERSION < 140000 || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128)
263 help
264 The implicit default version of DWARF debug info produced by a
265 toolchain changes over time.
266
267 This can break consumers of the debug info that haven't upgraded to
268 support newer revisions, and prevent testing newer versions, but
269 those should be less common scenarios.
270
271config DEBUG_INFO_DWARF4
272 bool "Generate DWARF Version 4 debuginfo"
273 select DEBUG_INFO
274 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502)
275 help
276 Generate DWARF v4 debug info. This requires gcc 4.5+, binutils 2.35.2
277 if using clang without clang's integrated assembler, and gdb 7.0+.
278
279 If you have consumers of DWARF debug info that are not ready for
280 newer revisions of DWARF, you may wish to choose this or have your
281 config select this.
282
283config DEBUG_INFO_DWARF5
284 bool "Generate DWARF Version 5 debuginfo"
285 select DEBUG_INFO
286 depends on !ARCH_HAS_BROKEN_DWARF5
287 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128)
288 help
289 Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc
290 5.0+ accepts the -gdwarf-5 flag but only had partial support for some
291 draft features until 7.0), and gdb 8.0+.
292
293 Changes to the structure of debug info in Version 5 allow for around
294 15-18% savings in resulting image and debug info section sizes as
295 compared to DWARF Version 4. DWARF Version 5 standardizes previous
296 extensions such as accelerators for symbol indexing and the format
297 for fission (.dwo/.dwp) files. Users may not want to select this
298 config if they rely on tooling that has not yet been updated to
299 support DWARF Version 5.
300
301endchoice # "Debug information"
302
303if DEBUG_INFO
304
305config DEBUG_INFO_REDUCED
306 bool "Reduce debugging information"
307 help
308 If you say Y here gcc is instructed to generate less debugging
309 information for structure types. This means that tools that
310 need full debugging information (like kgdb or systemtap) won't
311 be happy. But if you merely need debugging information to
312 resolve line numbers there is no loss. Advantage is that
313 build directory object sizes shrink dramatically over a full
314 DEBUG_INFO build and compile times are reduced too.
315 Only works with newer gcc versions.
316
317choice
318 prompt "Compressed Debug information"
319 help
320 Compress the resulting debug info. Results in smaller debug info sections,
321 but requires that consumers are able to decompress the results.
322
323 If unsure, choose DEBUG_INFO_COMPRESSED_NONE.
324
325config DEBUG_INFO_COMPRESSED_NONE
326 bool "Don't compress debug information"
327 help
328 Don't compress debug info sections.
329
330config DEBUG_INFO_COMPRESSED_ZLIB
331 bool "Compress debugging information with zlib"
332 depends on $(cc-option,-gz=zlib)
333 depends on $(ld-option,--compress-debug-sections=zlib)
334 help
335 Compress the debug information using zlib. Requires GCC 5.0+ or Clang
336 5.0+, binutils 2.26+, and zlib.
337
338 Users of dpkg-deb via scripts/package/builddeb may find an increase in
339 size of their debug .deb packages with this config set, due to the
340 debug info being compressed with zlib, then the object files being
341 recompressed with a different compression scheme. But this is still
342 preferable to setting $KDEB_COMPRESS to "none" which would be even
343 larger.
344
345config DEBUG_INFO_COMPRESSED_ZSTD
346 bool "Compress debugging information with zstd"
347 depends on $(cc-option,-gz=zstd)
348 depends on $(ld-option,--compress-debug-sections=zstd)
349 help
350 Compress the debug information using zstd. This may provide better
351 compression than zlib, for about the same time costs, but requires newer
352 toolchain support. Requires GCC 13.0+ or Clang 16.0+, binutils 2.40+, and
353 zstd.
354
355endchoice # "Compressed Debug information"
356
357config DEBUG_INFO_SPLIT
358 bool "Produce split debuginfo in .dwo files"
359 depends on $(cc-option,-gsplit-dwarf)
360 # RISC-V linker relaxation + -gsplit-dwarf has issues with LLVM and GCC
361 # prior to 12.x:
362 # https://github.com/llvm/llvm-project/issues/56642
363 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99090
364 depends on !RISCV || GCC_VERSION >= 120000
365 help
366 Generate debug info into separate .dwo files. This significantly
367 reduces the build directory size for builds with DEBUG_INFO,
368 because it stores the information only once on disk in .dwo
369 files instead of multiple times in object files and executables.
370 In addition the debug information is also compressed.
371
372 Requires recent gcc (4.7+) and recent gdb/binutils.
373 Any tool that packages or reads debug information would need
374 to know about the .dwo files and include them.
375 Incompatible with older versions of ccache.
376
377config DEBUG_INFO_BTF
378 bool "Generate BTF type information"
379 depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED
380 depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST
381 depends on BPF_SYSCALL
382 depends on PAHOLE_VERSION >= 116
383 depends on DEBUG_INFO_DWARF4 || PAHOLE_VERSION >= 121
384 # pahole uses elfutils, which does not have support for Hexagon relocations
385 depends on !HEXAGON
386 help
387 Generate deduplicated BTF type information from DWARF debug info.
388 Turning this on requires pahole v1.16 or later (v1.21 or later to
389 support DWARF 5), which will convert DWARF type info into equivalent
390 deduplicated BTF type info.
391
392config PAHOLE_HAS_SPLIT_BTF
393 def_bool PAHOLE_VERSION >= 119
394
395config PAHOLE_HAS_BTF_TAG
396 def_bool PAHOLE_VERSION >= 123
397 depends on CC_IS_CLANG
398 help
399 Decide whether pahole emits btf_tag attributes (btf_type_tag and
400 btf_decl_tag) or not. Currently only clang compiler implements
401 these attributes, so make the config depend on CC_IS_CLANG.
402
403config PAHOLE_HAS_LANG_EXCLUDE
404 def_bool PAHOLE_VERSION >= 124
405 help
406 Support for the --lang_exclude flag which makes pahole exclude
407 compilation units from the supplied language. Used in Kbuild to
408 omit Rust CUs which are not supported in version 1.24 of pahole,
409 otherwise it would emit malformed kernel and module binaries when
410 using DEBUG_INFO_BTF_MODULES.
411
412config DEBUG_INFO_BTF_MODULES
413 bool "Generate BTF type information for kernel modules"
414 default y
415 depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF
416 help
417 Generate compact split BTF type information for kernel modules.
418
419config MODULE_ALLOW_BTF_MISMATCH
420 bool "Allow loading modules with non-matching BTF type info"
421 depends on DEBUG_INFO_BTF_MODULES
422 help
423 For modules whose split BTF does not match vmlinux, load without
424 BTF rather than refusing to load. The default behavior with
425 module BTF enabled is to reject modules with such mismatches;
426 this option will still load module BTF where possible but ignore
427 it when a mismatch is found.
428
429config GDB_SCRIPTS
430 bool "Provide GDB scripts for kernel debugging"
431 help
432 This creates the required links to GDB helper scripts in the
433 build directory. If you load vmlinux into gdb, the helper
434 scripts will be automatically imported by gdb as well, and
435 additional functions are available to analyze a Linux kernel
436 instance. See Documentation/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 depends on !UML
477 help
478 This option will install uapi headers (headers exported to user-space)
479 into the usr/include directory for use during the kernel build.
480 This is unneeded for building the kernel itself, but needed for some
481 user-space program samples. It is also needed by some features such
482 as uapi header sanity checks.
483
484config DEBUG_SECTION_MISMATCH
485 bool "Enable full Section mismatch analysis"
486 depends on CC_IS_GCC
487 help
488 The section mismatch analysis checks if there are illegal
489 references from one section to another section.
490 During linktime or runtime, some sections are dropped;
491 any use of code/data previously in these sections would
492 most likely result in an oops.
493 In the code, functions and variables are annotated with
494 __init,, etc. (see the full list in include/linux/init.h),
495 which results in the code/data being placed in specific sections.
496 The section mismatch analysis is always performed after a full
497 kernel build, and enabling this option causes the following
498 additional step to occur:
499 - Add the option -fno-inline-functions-called-once to gcc commands.
500 When inlining a function annotated with __init in a non-init
501 function, we would lose the section information and thus
502 the analysis would not catch the illegal reference.
503 This option tells gcc to inline less (but it does result in
504 a larger kernel).
505
506config SECTION_MISMATCH_WARN_ONLY
507 bool "Make section mismatch errors non-fatal"
508 default y
509 help
510 If you say N here, the build process will fail if there are any
511 section mismatch, instead of just throwing warnings.
512
513 If unsure, say Y.
514
515config DEBUG_FORCE_FUNCTION_ALIGN_64B
516 bool "Force all function address 64B aligned"
517 depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC || RISCV || S390)
518 select FUNCTION_ALIGNMENT_64B
519 help
520 There are cases that a commit from one domain changes the function
521 address alignment of other domains, and cause magic performance
522 bump (regression or improvement). Enable this option will help to
523 verify if the bump is caused by function alignment changes, while
524 it will slightly increase the kernel size and affect icache usage.
525
526 It is mainly for debug and performance tuning use.
527
528#
529# Select this config option from the architecture Kconfig, if it
530# is preferred to always offer frame pointers as a config
531# option on the architecture (regardless of KERNEL_DEBUG):
532#
533config ARCH_WANT_FRAME_POINTERS
534 bool
535
536config FRAME_POINTER
537 bool "Compile the kernel with frame pointers"
538 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
539 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
540 help
541 If you say Y here the resulting kernel image will be slightly
542 larger and slower, but it gives very useful debugging information
543 in case of kernel bugs. (precise oopses/stacktraces/warnings)
544
545config OBJTOOL
546 bool
547
548config STACK_VALIDATION
549 bool "Compile-time stack metadata validation"
550 depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER
551 select OBJTOOL
552 default n
553 help
554 Validate frame pointer rules at compile-time. This helps ensure that
555 runtime stack traces are more reliable.
556
557 For more information, see
558 tools/objtool/Documentation/objtool.txt.
559
560config NOINSTR_VALIDATION
561 bool
562 depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY
563 select OBJTOOL
564 default y
565
566config VMLINUX_MAP
567 bool "Generate vmlinux.map file when linking"
568 depends on EXPERT
569 help
570 Selecting this option will pass "-Map=vmlinux.map" to ld
571 when linking vmlinux. That file can be useful for verifying
572 and debugging magic section games, and for seeing which
573 pieces of code get eliminated with
574 CONFIG_LD_DEAD_CODE_DATA_ELIMINATION.
575
576config BUILTIN_MODULE_RANGES
577 bool "Generate address range information for builtin modules"
578 depends on !LTO
579 depends on VMLINUX_MAP
580 help
581 When modules are built into the kernel, there will be no module name
582 associated with its symbols in /proc/kallsyms. Tracers may want to
583 identify symbols by module name and symbol name regardless of whether
584 the module is configured as loadable or not.
585
586 This option generates modules.builtin.ranges in the build tree with
587 offset ranges (per ELF section) for the module(s) they belong to.
588 It also records an anchor symbol to determine the load address of the
589 section.
590
591config DEBUG_FORCE_WEAK_PER_CPU
592 bool "Force weak per-cpu definitions"
593 depends on DEBUG_KERNEL
594 help
595 s390 and alpha require percpu variables in modules to be
596 defined weak to work around addressing range issue which
597 puts the following two restrictions on percpu variable
598 definitions.
599
600 1. percpu symbols must be unique whether static or not
601 2. percpu variables can't be defined inside a function
602
603 To ensure that generic code follows the above rules, this
604 option forces all percpu variables to be defined as weak.
605
606endmenu # "Compiler options"
607
608menu "Generic Kernel Debugging Instruments"
609
610config MAGIC_SYSRQ
611 bool "Magic SysRq key"
612 depends on !UML
613 help
614 If you say Y here, you will have some control over the system even
615 if the system crashes for example during kernel debugging (e.g., you
616 will be able to flush the buffer cache to disk, reboot the system
617 immediately or dump some status information). This is accomplished
618 by pressing various keys while holding SysRq (Alt+PrintScreen). It
619 also works on a serial console (on PC hardware at least), if you
620 send a BREAK and then within 5 seconds a command keypress. The
621 keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
622 Don't say Y unless you really know what this hack does.
623
624config MAGIC_SYSRQ_DEFAULT_ENABLE
625 hex "Enable magic SysRq key functions by default"
626 depends on MAGIC_SYSRQ
627 default 0x1
628 help
629 Specifies which SysRq key functions are enabled by default.
630 This may be set to 1 or 0 to enable or disable them all, or
631 to a bitmask as described in Documentation/admin-guide/sysrq.rst.
632
633config MAGIC_SYSRQ_SERIAL
634 bool "Enable magic SysRq key over serial"
635 depends on MAGIC_SYSRQ
636 default y
637 help
638 Many embedded boards have a disconnected TTL level serial which can
639 generate some garbage that can lead to spurious false sysrq detects.
640 This option allows you to decide whether you want to enable the
641 magic SysRq key.
642
643config MAGIC_SYSRQ_SERIAL_SEQUENCE
644 string "Char sequence that enables magic SysRq over serial"
645 depends on MAGIC_SYSRQ_SERIAL
646 default ""
647 help
648 Specifies a sequence of characters that can follow BREAK to enable
649 SysRq on a serial console.
650
651 If unsure, leave an empty string and the option will not be enabled.
652
653config DEBUG_FS
654 bool "Debug Filesystem"
655 help
656 debugfs is a virtual file system that kernel developers use to put
657 debugging files into. Enable this option to be able to read and
658 write to these files.
659
660 For detailed documentation on the debugfs API, see
661 Documentation/filesystems/.
662
663 If unsure, say N.
664
665choice
666 prompt "Debugfs default access"
667 depends on DEBUG_FS
668 default DEBUG_FS_ALLOW_ALL
669 help
670 This selects the default access restrictions for debugfs.
671 It can be overridden with kernel command line option
672 debugfs=[on,no-mount,off]. The restrictions apply for API access
673 and filesystem registration.
674
675config DEBUG_FS_ALLOW_ALL
676 bool "Access normal"
677 help
678 No restrictions apply. Both API and filesystem registration
679 is on. This is the normal default operation.
680
681config DEBUG_FS_DISALLOW_MOUNT
682 bool "Do not register debugfs as filesystem"
683 help
684 The API is open but filesystem is not loaded. Clients can still do
685 their work and read with debug tools that do not need
686 debugfs filesystem.
687
688config DEBUG_FS_ALLOW_NONE
689 bool "No access"
690 help
691 Access is off. Clients get -PERM when trying to create nodes in
692 debugfs tree and debugfs is not registered as a filesystem.
693 Client can then back-off or continue without debugfs access.
694
695endchoice
696
697source "lib/Kconfig.kgdb"
698source "lib/Kconfig.ubsan"
699source "lib/Kconfig.kcsan"
700
701endmenu
702
703menu "Networking Debugging"
704
705source "net/Kconfig.debug"
706
707endmenu # "Networking Debugging"
708
709menu "Memory Debugging"
710
711source "mm/Kconfig.debug"
712
713config DEBUG_OBJECTS
714 bool "Debug object operations"
715 depends on DEBUG_KERNEL
716 help
717 If you say Y here, additional code will be inserted into the
718 kernel to track the life time of various objects and validate
719 the operations on those objects.
720
721config DEBUG_OBJECTS_SELFTEST
722 bool "Debug objects selftest"
723 depends on DEBUG_OBJECTS
724 help
725 This enables the selftest of the object debug code.
726
727config DEBUG_OBJECTS_FREE
728 bool "Debug objects in freed memory"
729 depends on DEBUG_OBJECTS
730 help
731 This enables checks whether a k/v free operation frees an area
732 which contains an object which has not been deactivated
733 properly. This can make kmalloc/kfree-intensive workloads
734 much slower.
735
736config DEBUG_OBJECTS_TIMERS
737 bool "Debug timer objects"
738 depends on DEBUG_OBJECTS
739 help
740 If you say Y here, additional code will be inserted into the
741 timer routines to track the life time of timer objects and
742 validate the timer operations.
743
744config DEBUG_OBJECTS_WORK
745 bool "Debug work objects"
746 depends on DEBUG_OBJECTS
747 help
748 If you say Y here, additional code will be inserted into the
749 work queue routines to track the life time of work objects and
750 validate the work operations.
751
752config DEBUG_OBJECTS_RCU_HEAD
753 bool "Debug RCU callbacks objects"
754 depends on DEBUG_OBJECTS
755 help
756 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
757
758config DEBUG_OBJECTS_PERCPU_COUNTER
759 bool "Debug percpu counter objects"
760 depends on DEBUG_OBJECTS
761 help
762 If you say Y here, additional code will be inserted into the
763 percpu counter routines to track the life time of percpu counter
764 objects and validate the percpu counter operations.
765
766config DEBUG_OBJECTS_ENABLE_DEFAULT
767 int "debug_objects bootup default value (0-1)"
768 range 0 1
769 default "1"
770 depends on DEBUG_OBJECTS
771 help
772 Debug objects boot parameter default value
773
774config SHRINKER_DEBUG
775 bool "Enable shrinker debugging support"
776 depends on DEBUG_FS
777 help
778 Say Y to enable the shrinker debugfs interface which provides
779 visibility into the kernel memory shrinkers subsystem.
780 Disable it to avoid an extra memory footprint.
781
782config DEBUG_STACK_USAGE
783 bool "Stack utilization instrumentation"
784 depends on DEBUG_KERNEL
785 help
786 Enables the display of the minimum amount of free stack which each
787 task has ever had available in the sysrq-T and sysrq-P debug output.
788 Also emits a message to dmesg when a process exits if that process
789 used more stack space than previously exiting processes.
790
791 This option will slow down process creation somewhat.
792
793config SCHED_STACK_END_CHECK
794 bool "Detect stack corruption on calls to schedule()"
795 depends on DEBUG_KERNEL
796 default n
797 help
798 This option checks for a stack overrun on calls to schedule().
799 If the stack end location is found to be over written always panic as
800 the content of the corrupted region can no longer be trusted.
801 This is to ensure no erroneous behaviour occurs which could result in
802 data corruption or a sporadic crash at a later stage once the region
803 is examined. The runtime overhead introduced is minimal.
804
805config ARCH_HAS_DEBUG_VM_PGTABLE
806 bool
807 help
808 An architecture should select this when it can successfully
809 build and run DEBUG_VM_PGTABLE.
810
811config DEBUG_VM_IRQSOFF
812 def_bool DEBUG_VM && !PREEMPT_RT
813
814config DEBUG_VM
815 bool "Debug VM"
816 depends on DEBUG_KERNEL
817 help
818 Enable this to turn on extended checks in the virtual-memory system
819 that may impact performance.
820
821 If unsure, say N.
822
823config DEBUG_VM_SHOOT_LAZIES
824 bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation"
825 depends on DEBUG_VM
826 depends on MMU_LAZY_TLB_SHOOTDOWN
827 help
828 Enable additional IPIs that ensure lazy tlb mm references are removed
829 before the mm is freed.
830
831 If unsure, say N.
832
833config DEBUG_VM_MAPLE_TREE
834 bool "Debug VM maple trees"
835 depends on DEBUG_VM
836 select DEBUG_MAPLE_TREE
837 help
838 Enable VM maple tree debugging information and extra validations.
839
840 If unsure, say N.
841
842config DEBUG_VM_RB
843 bool "Debug VM red-black trees"
844 depends on DEBUG_VM
845 help
846 Enable VM red-black tree debugging information and extra validations.
847
848 If unsure, say N.
849
850config DEBUG_VM_PGFLAGS
851 bool "Debug page-flags operations"
852 depends on DEBUG_VM
853 help
854 Enables extra validation on page flags operations.
855
856 If unsure, say N.
857
858config DEBUG_VM_PGTABLE
859 bool "Debug arch page table for semantics compliance"
860 depends on MMU
861 depends on ARCH_HAS_DEBUG_VM_PGTABLE
862 default y if DEBUG_VM
863 help
864 This option provides a debug method which can be used to test
865 architecture page table helper functions on various platforms in
866 verifying if they comply with expected generic MM semantics. This
867 will help architecture code in making sure that any changes or
868 new additions of these helpers still conform to expected
869 semantics of the generic MM. Platforms will have to opt in for
870 this through ARCH_HAS_DEBUG_VM_PGTABLE.
871
872 If unsure, say N.
873
874config ARCH_HAS_DEBUG_VIRTUAL
875 bool
876
877config DEBUG_VIRTUAL
878 bool "Debug VM translations"
879 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
880 help
881 Enable some costly sanity checks in virtual to page code. This can
882 catch mistakes with virt_to_page() and friends.
883
884 If unsure, say N.
885
886config DEBUG_NOMMU_REGIONS
887 bool "Debug the global anon/private NOMMU mapping region tree"
888 depends on DEBUG_KERNEL && !MMU
889 help
890 This option causes the global tree of anonymous and private mapping
891 regions to be regularly checked for invalid topology.
892
893config DEBUG_MEMORY_INIT
894 bool "Debug memory initialisation" if EXPERT
895 default !EXPERT
896 help
897 Enable this for additional checks during memory initialisation.
898 The sanity checks verify aspects of the VM such as the memory model
899 and other information provided by the architecture. Verbose
900 information will be printed at KERN_DEBUG loglevel depending
901 on the mminit_loglevel= command-line option.
902
903 If unsure, say Y
904
905config MEMORY_NOTIFIER_ERROR_INJECT
906 tristate "Memory hotplug notifier error injection module"
907 depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION
908 help
909 This option provides the ability to inject artificial errors to
910 memory hotplug notifier chain callbacks. It is controlled through
911 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
912
913 If the notifier call chain should be failed with some events
914 notified, write the error code to "actions/<notifier event>/error".
915
916 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
917
918 # cd /sys/kernel/debug/notifier-error-inject/memory
919 # echo -12 > actions/MEM_GOING_OFFLINE/error
920 # echo offline > /sys/devices/system/memory/memoryXXX/state
921 bash: echo: write error: Cannot allocate memory
922
923 To compile this code as a module, choose M here: the module will
924 be called memory-notifier-error-inject.
925
926 If unsure, say N.
927
928config DEBUG_PER_CPU_MAPS
929 bool "Debug access to per_cpu maps"
930 depends on DEBUG_KERNEL
931 depends on SMP
932 help
933 Say Y to verify that the per_cpu map being accessed has
934 been set up. This adds a fair amount of code to kernel memory
935 and decreases performance.
936
937 Say N if unsure.
938
939config DEBUG_KMAP_LOCAL
940 bool "Debug kmap_local temporary mappings"
941 depends on DEBUG_KERNEL && KMAP_LOCAL
942 help
943 This option enables additional error checking for the kmap_local
944 infrastructure. Disable for production use.
945
946config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
947 bool
948
949config DEBUG_KMAP_LOCAL_FORCE_MAP
950 bool "Enforce kmap_local temporary mappings"
951 depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
952 select KMAP_LOCAL
953 select DEBUG_KMAP_LOCAL
954 help
955 This option enforces temporary mappings through the kmap_local
956 mechanism for non-highmem pages and on non-highmem systems.
957 Disable this for production systems!
958
959config DEBUG_HIGHMEM
960 bool "Highmem debugging"
961 depends on DEBUG_KERNEL && HIGHMEM
962 select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
963 select DEBUG_KMAP_LOCAL
964 help
965 This option enables additional error checking for high memory
966 systems. Disable for production systems.
967
968config HAVE_DEBUG_STACKOVERFLOW
969 bool
970
971config DEBUG_STACKOVERFLOW
972 bool "Check for stack overflows"
973 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
974 help
975 Say Y here if you want to check for overflows of kernel, IRQ
976 and exception stacks (if your architecture uses them). This
977 option will show detailed messages if free stack space drops
978 below a certain limit.
979
980 These kinds of bugs usually occur when call-chains in the
981 kernel get too deep, especially when interrupts are
982 involved.
983
984 Use this in cases where you see apparently random memory
985 corruption, especially if it appears in 'struct thread_info'
986
987 If in doubt, say "N".
988
989config CODE_TAGGING
990 bool
991 select KALLSYMS
992
993config MEM_ALLOC_PROFILING
994 bool "Enable memory allocation profiling"
995 default n
996 depends on MMU
997 depends on PROC_FS
998 depends on !DEBUG_FORCE_WEAK_PER_CPU
999 select CODE_TAGGING
1000 select PAGE_EXTENSION
1001 select SLAB_OBJ_EXT
1002 help
1003 Track allocation source code and record total allocation size
1004 initiated at that code location. The mechanism can be used to track
1005 memory leaks with a low performance and memory impact.
1006
1007config MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT
1008 bool "Enable memory allocation profiling by default"
1009 default y
1010 depends on MEM_ALLOC_PROFILING
1011
1012config MEM_ALLOC_PROFILING_DEBUG
1013 bool "Memory allocation profiler debugging"
1014 default n
1015 depends on MEM_ALLOC_PROFILING
1016 select MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT
1017 help
1018 Adds warnings with helpful error messages for memory allocation
1019 profiling.
1020
1021source "lib/Kconfig.kasan"
1022source "lib/Kconfig.kfence"
1023source "lib/Kconfig.kmsan"
1024
1025endmenu # "Memory Debugging"
1026
1027config DEBUG_SHIRQ
1028 bool "Debug shared IRQ handlers"
1029 depends on DEBUG_KERNEL
1030 help
1031 Enable this to generate a spurious interrupt just before a shared
1032 interrupt handler is deregistered (generating one when registering
1033 is currently disabled). Drivers need to handle this correctly. Some
1034 don't and need to be caught.
1035
1036menu "Debug Oops, Lockups and Hangs"
1037
1038config PANIC_ON_OOPS
1039 bool "Panic on Oops"
1040 help
1041 Say Y here to enable the kernel to panic when it oopses. This
1042 has the same effect as setting oops=panic on the kernel command
1043 line.
1044
1045 This feature is useful to ensure that the kernel does not do
1046 anything erroneous after an oops which could result in data
1047 corruption or other issues.
1048
1049 Say N if unsure.
1050
1051config PANIC_ON_OOPS_VALUE
1052 int
1053 range 0 1
1054 default 0 if !PANIC_ON_OOPS
1055 default 1 if PANIC_ON_OOPS
1056
1057config PANIC_TIMEOUT
1058 int "panic timeout"
1059 default 0
1060 help
1061 Set the timeout value (in seconds) until a reboot occurs when
1062 the kernel panics. If n = 0, then we wait forever. A timeout
1063 value n > 0 will wait n seconds before rebooting, while a timeout
1064 value n < 0 will reboot immediately. This setting can be overridden
1065 with the kernel command line option panic=, and from userspace via
1066 /proc/sys/kernel/panic.
1067
1068config LOCKUP_DETECTOR
1069 bool
1070
1071config SOFTLOCKUP_DETECTOR
1072 bool "Detect Soft Lockups"
1073 depends on DEBUG_KERNEL && !S390
1074 select LOCKUP_DETECTOR
1075 help
1076 Say Y here to enable the kernel to act as a watchdog to detect
1077 soft lockups.
1078
1079 Softlockups are bugs that cause the kernel to loop in kernel
1080 mode for more than 20 seconds, without giving other tasks a
1081 chance to run. The current stack trace is displayed upon
1082 detection and the system will stay locked up.
1083
1084config SOFTLOCKUP_DETECTOR_INTR_STORM
1085 bool "Detect Interrupt Storm in Soft Lockups"
1086 depends on SOFTLOCKUP_DETECTOR && IRQ_TIME_ACCOUNTING
1087 select GENERIC_IRQ_STAT_SNAPSHOT
1088 default y if NR_CPUS <= 128
1089 help
1090 Say Y here to enable the kernel to detect interrupt storm
1091 during "soft lockups".
1092
1093 "soft lockups" can be caused by a variety of reasons. If one is
1094 caused by an interrupt storm, then the storming interrupts will not
1095 be on the callstack. To detect this case, it is necessary to report
1096 the CPU stats and the interrupt counts during the "soft lockups".
1097
1098config BOOTPARAM_SOFTLOCKUP_PANIC
1099 bool "Panic (Reboot) On Soft Lockups"
1100 depends on SOFTLOCKUP_DETECTOR
1101 help
1102 Say Y here to enable the kernel to panic on "soft lockups",
1103 which are bugs that cause the kernel to loop in kernel
1104 mode for more than 20 seconds (configurable using the watchdog_thresh
1105 sysctl), without giving other tasks a chance to run.
1106
1107 The panic can be used in combination with panic_timeout,
1108 to cause the system to reboot automatically after a
1109 lockup has been detected. This feature is useful for
1110 high-availability systems that have uptime guarantees and
1111 where a lockup must be resolved ASAP.
1112
1113 Say N if unsure.
1114
1115config HAVE_HARDLOCKUP_DETECTOR_BUDDY
1116 bool
1117 depends on SMP
1118 default y
1119
1120#
1121# Global switch whether to build a hardlockup detector at all. It is available
1122# only when the architecture supports at least one implementation. There are
1123# two exceptions. The hardlockup detector is never enabled on:
1124#
1125# s390: it reported many false positives there
1126#
1127# sparc64: has a custom implementation which is not using the common
1128# hardlockup command line options and sysctl interface.
1129#
1130config HARDLOCKUP_DETECTOR
1131 bool "Detect Hard Lockups"
1132 depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64
1133 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH
1134 imply HARDLOCKUP_DETECTOR_PERF
1135 imply HARDLOCKUP_DETECTOR_BUDDY
1136 imply HARDLOCKUP_DETECTOR_ARCH
1137 select LOCKUP_DETECTOR
1138
1139 help
1140 Say Y here to enable the kernel to act as a watchdog to detect
1141 hard lockups.
1142
1143 Hardlockups are bugs that cause the CPU to loop in kernel mode
1144 for more than 10 seconds, without letting other interrupts have a
1145 chance to run. The current stack trace is displayed upon detection
1146 and the system will stay locked up.
1147
1148#
1149# Note that arch-specific variants are always preferred.
1150#
1151config HARDLOCKUP_DETECTOR_PREFER_BUDDY
1152 bool "Prefer the buddy CPU hardlockup detector"
1153 depends on HARDLOCKUP_DETECTOR
1154 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY
1155 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1156 help
1157 Say Y here to prefer the buddy hardlockup detector over the perf one.
1158
1159 With the buddy detector, each CPU uses its softlockup hrtimer
1160 to check that the next CPU is processing hrtimer interrupts by
1161 verifying that a counter is increasing.
1162
1163 This hardlockup detector is useful on systems that don't have
1164 an arch-specific hardlockup detector or if resources needed
1165 for the hardlockup detector are better used for other things.
1166
1167config HARDLOCKUP_DETECTOR_PERF
1168 bool
1169 depends on HARDLOCKUP_DETECTOR
1170 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY
1171 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1172 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1173
1174config HARDLOCKUP_DETECTOR_BUDDY
1175 bool
1176 depends on HARDLOCKUP_DETECTOR
1177 depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY
1178 depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY
1179 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1180 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1181
1182config HARDLOCKUP_DETECTOR_ARCH
1183 bool
1184 depends on HARDLOCKUP_DETECTOR
1185 depends on HAVE_HARDLOCKUP_DETECTOR_ARCH
1186 help
1187 The arch-specific implementation of the hardlockup detector will
1188 be used.
1189
1190#
1191# Both the "perf" and "buddy" hardlockup detectors count hrtimer
1192# interrupts. This config enables functions managing this common code.
1193#
1194config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1195 bool
1196 select SOFTLOCKUP_DETECTOR
1197
1198#
1199# Enables a timestamp based low pass filter to compensate for perf based
1200# hard lockup detection which runs too fast due to turbo modes.
1201#
1202config HARDLOCKUP_CHECK_TIMESTAMP
1203 bool
1204
1205config BOOTPARAM_HARDLOCKUP_PANIC
1206 bool "Panic (Reboot) On Hard Lockups"
1207 depends on HARDLOCKUP_DETECTOR
1208 help
1209 Say Y here to enable the kernel to panic on "hard lockups",
1210 which are bugs that cause the kernel to loop in kernel
1211 mode with interrupts disabled for more than 10 seconds (configurable
1212 using the watchdog_thresh sysctl).
1213
1214 Say N if unsure.
1215
1216config DETECT_HUNG_TASK
1217 bool "Detect Hung Tasks"
1218 depends on DEBUG_KERNEL
1219 default SOFTLOCKUP_DETECTOR
1220 help
1221 Say Y here to enable the kernel to detect "hung tasks",
1222 which are bugs that cause the task to be stuck in
1223 uninterruptible "D" state indefinitely.
1224
1225 When a hung task is detected, the kernel will print the
1226 current stack trace (which you should report), but the
1227 task will stay in uninterruptible state. If lockdep is
1228 enabled then all held locks will also be reported. This
1229 feature has negligible overhead.
1230
1231config DEFAULT_HUNG_TASK_TIMEOUT
1232 int "Default timeout for hung task detection (in seconds)"
1233 depends on DETECT_HUNG_TASK
1234 default 120
1235 help
1236 This option controls the default timeout (in seconds) used
1237 to determine when a task has become non-responsive and should
1238 be considered hung.
1239
1240 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
1241 sysctl or by writing a value to
1242 /proc/sys/kernel/hung_task_timeout_secs.
1243
1244 A timeout of 0 disables the check. The default is two minutes.
1245 Keeping the default should be fine in most cases.
1246
1247config BOOTPARAM_HUNG_TASK_PANIC
1248 bool "Panic (Reboot) On Hung Tasks"
1249 depends on DETECT_HUNG_TASK
1250 help
1251 Say Y here to enable the kernel to panic on "hung tasks",
1252 which are bugs that cause the kernel to leave a task stuck
1253 in uninterruptible "D" state.
1254
1255 The panic can be used in combination with panic_timeout,
1256 to cause the system to reboot automatically after a
1257 hung task has been detected. This feature is useful for
1258 high-availability systems that have uptime guarantees and
1259 where a hung tasks must be resolved ASAP.
1260
1261 Say N if unsure.
1262
1263config WQ_WATCHDOG
1264 bool "Detect Workqueue Stalls"
1265 depends on DEBUG_KERNEL
1266 help
1267 Say Y here to enable stall detection on workqueues. If a
1268 worker pool doesn't make forward progress on a pending work
1269 item for over a given amount of time, 30s by default, a
1270 warning message is printed along with dump of workqueue
1271 state. This can be configured through kernel parameter
1272 "workqueue.watchdog_thresh" and its sysfs counterpart.
1273
1274config WQ_CPU_INTENSIVE_REPORT
1275 bool "Report per-cpu work items which hog CPU for too long"
1276 depends on DEBUG_KERNEL
1277 help
1278 Say Y here to enable reporting of concurrency-managed per-cpu work
1279 items that hog CPUs for longer than
1280 workqueue.cpu_intensive_thresh_us. Workqueue automatically
1281 detects and excludes them from concurrency management to prevent
1282 them from stalling other per-cpu work items. Occassional
1283 triggering may not necessarily indicate a problem. Repeated
1284 triggering likely indicates that the work item should be switched
1285 to use an unbound workqueue.
1286
1287config TEST_LOCKUP
1288 tristate "Test module to generate lockups"
1289 depends on m
1290 help
1291 This builds the "test_lockup" module that helps to make sure
1292 that watchdogs and lockup detectors are working properly.
1293
1294 Depending on module parameters it could emulate soft or hard
1295 lockup, "hung task", or locking arbitrary lock for a long time.
1296 Also it could generate series of lockups with cooling-down periods.
1297
1298 If unsure, say N.
1299
1300endmenu # "Debug lockups and hangs"
1301
1302menu "Scheduler Debugging"
1303
1304config SCHED_DEBUG
1305 bool "Collect scheduler debugging info"
1306 depends on DEBUG_KERNEL && DEBUG_FS
1307 default y
1308 help
1309 If you say Y here, the /sys/kernel/debug/sched file will be provided
1310 that can help debug the scheduler. The runtime overhead of this
1311 option is minimal.
1312
1313config SCHED_INFO
1314 bool
1315 default n
1316
1317config SCHEDSTATS
1318 bool "Collect scheduler statistics"
1319 depends on PROC_FS
1320 select SCHED_INFO
1321 help
1322 If you say Y here, additional code will be inserted into the
1323 scheduler and related routines to collect statistics about
1324 scheduler behavior and provide them in /proc/schedstat. These
1325 stats may be useful for both tuning and debugging the scheduler
1326 If you aren't debugging the scheduler or trying to tune a specific
1327 application, you can say N to avoid the very slight overhead
1328 this adds.
1329
1330endmenu
1331
1332config DEBUG_PREEMPT
1333 bool "Debug preemptible kernel"
1334 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT
1335 help
1336 If you say Y here then the kernel will use a debug variant of the
1337 commonly used smp_processor_id() function and will print warnings
1338 if kernel code uses it in a preemption-unsafe way. Also, the kernel
1339 will detect preemption count underflows.
1340
1341 This option has potential to introduce high runtime overhead,
1342 depending on workload as it triggers debugging routines for each
1343 this_cpu operation. It should only be used for debugging purposes.
1344
1345menu "Lock Debugging (spinlocks, mutexes, etc...)"
1346
1347config LOCK_DEBUGGING_SUPPORT
1348 bool
1349 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1350 default y
1351
1352config PROVE_LOCKING
1353 bool "Lock debugging: prove locking correctness"
1354 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1355 select LOCKDEP
1356 select DEBUG_SPINLOCK
1357 select DEBUG_MUTEXES if !PREEMPT_RT
1358 select DEBUG_RT_MUTEXES if RT_MUTEXES
1359 select DEBUG_RWSEMS if !PREEMPT_RT
1360 select DEBUG_WW_MUTEX_SLOWPATH
1361 select DEBUG_LOCK_ALLOC
1362 select PREEMPT_COUNT if !ARCH_NO_PREEMPT
1363 select TRACE_IRQFLAGS
1364 default n
1365 help
1366 This feature enables the kernel to prove that all locking
1367 that occurs in the kernel runtime is mathematically
1368 correct: that under no circumstance could an arbitrary (and
1369 not yet triggered) combination of observed locking
1370 sequences (on an arbitrary number of CPUs, running an
1371 arbitrary number of tasks and interrupt contexts) cause a
1372 deadlock.
1373
1374 In short, this feature enables the kernel to report locking
1375 related deadlocks before they actually occur.
1376
1377 The proof does not depend on how hard and complex a
1378 deadlock scenario would be to trigger: how many
1379 participant CPUs, tasks and irq-contexts would be needed
1380 for it to trigger. The proof also does not depend on
1381 timing: if a race and a resulting deadlock is possible
1382 theoretically (no matter how unlikely the race scenario
1383 is), it will be proven so and will immediately be
1384 reported by the kernel (once the event is observed that
1385 makes the deadlock theoretically possible).
1386
1387 If a deadlock is impossible (i.e. the locking rules, as
1388 observed by the kernel, are mathematically correct), the
1389 kernel reports nothing.
1390
1391 NOTE: this feature can also be enabled for rwlocks, mutexes
1392 and rwsems - in which case all dependencies between these
1393 different locking variants are observed and mapped too, and
1394 the proof of observed correctness is also maintained for an
1395 arbitrary combination of these separate locking variants.
1396
1397 For more details, see Documentation/locking/lockdep-design.rst.
1398
1399config PROVE_RAW_LOCK_NESTING
1400 bool "Enable raw_spinlock - spinlock nesting checks" if !ARCH_SUPPORTS_RT
1401 depends on PROVE_LOCKING
1402 default y if ARCH_SUPPORTS_RT
1403 help
1404 Enable the raw_spinlock vs. spinlock nesting checks which ensure
1405 that the lock nesting rules for PREEMPT_RT enabled kernels are
1406 not violated.
1407
1408config LOCK_STAT
1409 bool "Lock usage statistics"
1410 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1411 select LOCKDEP
1412 select DEBUG_SPINLOCK
1413 select DEBUG_MUTEXES if !PREEMPT_RT
1414 select DEBUG_RT_MUTEXES if RT_MUTEXES
1415 select DEBUG_LOCK_ALLOC
1416 default n
1417 help
1418 This feature enables tracking lock contention points
1419
1420 For more details, see Documentation/locking/lockstat.rst
1421
1422 This also enables lock events required by "perf lock",
1423 subcommand of perf.
1424 If you want to use "perf lock", you also need to turn on
1425 CONFIG_EVENT_TRACING.
1426
1427 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1428 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1429
1430config DEBUG_RT_MUTEXES
1431 bool "RT Mutex debugging, deadlock detection"
1432 depends on DEBUG_KERNEL && RT_MUTEXES
1433 help
1434 This allows rt mutex semantics violations and rt mutex related
1435 deadlocks (lockups) to be detected and reported automatically.
1436
1437config DEBUG_SPINLOCK
1438 bool "Spinlock and rw-lock debugging: basic checks"
1439 depends on DEBUG_KERNEL
1440 select UNINLINE_SPIN_UNLOCK
1441 help
1442 Say Y here and build SMP to catch missing spinlock initialization
1443 and certain other kinds of spinlock errors commonly made. This is
1444 best used in conjunction with the NMI watchdog so that spinlock
1445 deadlocks are also debuggable.
1446
1447config DEBUG_MUTEXES
1448 bool "Mutex debugging: basic checks"
1449 depends on DEBUG_KERNEL && !PREEMPT_RT
1450 help
1451 This feature allows mutex semantics violations to be detected and
1452 reported.
1453
1454config DEBUG_WW_MUTEX_SLOWPATH
1455 bool "Wait/wound mutex debugging: Slowpath testing"
1456 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1457 select DEBUG_LOCK_ALLOC
1458 select DEBUG_SPINLOCK
1459 select DEBUG_MUTEXES if !PREEMPT_RT
1460 select DEBUG_RT_MUTEXES if PREEMPT_RT
1461 help
1462 This feature enables slowpath testing for w/w mutex users by
1463 injecting additional -EDEADLK wound/backoff cases. Together with
1464 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1465 will test all possible w/w mutex interface abuse with the
1466 exception of simply not acquiring all the required locks.
1467 Note that this feature can introduce significant overhead, so
1468 it really should not be enabled in a production or distro kernel,
1469 even a debug kernel. If you are a driver writer, enable it. If
1470 you are a distro, do not.
1471
1472config DEBUG_RWSEMS
1473 bool "RW Semaphore debugging: basic checks"
1474 depends on DEBUG_KERNEL && !PREEMPT_RT
1475 help
1476 This debugging feature allows mismatched rw semaphore locks
1477 and unlocks to be detected and reported.
1478
1479config DEBUG_LOCK_ALLOC
1480 bool "Lock debugging: detect incorrect freeing of live locks"
1481 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1482 select DEBUG_SPINLOCK
1483 select DEBUG_MUTEXES if !PREEMPT_RT
1484 select DEBUG_RT_MUTEXES if RT_MUTEXES
1485 select LOCKDEP
1486 help
1487 This feature will check whether any held lock (spinlock, rwlock,
1488 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1489 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1490 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1491 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1492 held during task exit.
1493
1494config LOCKDEP
1495 bool
1496 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1497 select STACKTRACE
1498 select KALLSYMS
1499 select KALLSYMS_ALL
1500
1501config LOCKDEP_SMALL
1502 bool
1503
1504config LOCKDEP_BITS
1505 int "Size for MAX_LOCKDEP_ENTRIES (as Nth power of 2)"
1506 depends on LOCKDEP && !LOCKDEP_SMALL
1507 range 10 24
1508 default 15
1509 help
1510 Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message.
1511
1512config LOCKDEP_CHAINS_BITS
1513 int "Size for MAX_LOCKDEP_CHAINS (as Nth power of 2)"
1514 depends on LOCKDEP && !LOCKDEP_SMALL
1515 range 10 21
1516 default 16
1517 help
1518 Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message.
1519
1520config LOCKDEP_STACK_TRACE_BITS
1521 int "Size for MAX_STACK_TRACE_ENTRIES (as Nth power of 2)"
1522 depends on LOCKDEP && !LOCKDEP_SMALL
1523 range 10 26
1524 default 19
1525 help
1526 Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message.
1527
1528config LOCKDEP_STACK_TRACE_HASH_BITS
1529 int "Size for STACK_TRACE_HASH_SIZE (as Nth power of 2)"
1530 depends on LOCKDEP && !LOCKDEP_SMALL
1531 range 10 26
1532 default 14
1533 help
1534 Try increasing this value if you need large STACK_TRACE_HASH_SIZE.
1535
1536config LOCKDEP_CIRCULAR_QUEUE_BITS
1537 int "Size for elements in circular_queue struct (as Nth power of 2)"
1538 depends on LOCKDEP
1539 range 10 26
1540 default 12
1541 help
1542 Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure.
1543
1544config DEBUG_LOCKDEP
1545 bool "Lock dependency engine debugging"
1546 depends on DEBUG_KERNEL && LOCKDEP
1547 select DEBUG_IRQFLAGS
1548 help
1549 If you say Y here, the lock dependency engine will do
1550 additional runtime checks to debug itself, at the price
1551 of more runtime overhead.
1552
1553config DEBUG_ATOMIC_SLEEP
1554 bool "Sleep inside atomic section checking"
1555 select PREEMPT_COUNT
1556 depends on DEBUG_KERNEL
1557 depends on !ARCH_NO_PREEMPT
1558 help
1559 If you say Y here, various routines which may sleep will become very
1560 noisy if they are called inside atomic sections: when a spinlock is
1561 held, inside an rcu read side critical section, inside preempt disabled
1562 sections, inside an interrupt, etc...
1563
1564config DEBUG_LOCKING_API_SELFTESTS
1565 bool "Locking API boot-time self-tests"
1566 depends on DEBUG_KERNEL
1567 help
1568 Say Y here if you want the kernel to run a short self-test during
1569 bootup. The self-test checks whether common types of locking bugs
1570 are detected by debugging mechanisms or not. (if you disable
1571 lock debugging then those bugs won't be detected of course.)
1572 The following locking APIs are covered: spinlocks, rwlocks,
1573 mutexes and rwsems.
1574
1575config LOCK_TORTURE_TEST
1576 tristate "torture tests for locking"
1577 depends on DEBUG_KERNEL
1578 select TORTURE_TEST
1579 help
1580 This option provides a kernel module that runs torture tests
1581 on kernel locking primitives. The kernel module may be built
1582 after the fact on the running kernel to be tested, if desired.
1583
1584 Say Y here if you want kernel locking-primitive torture tests
1585 to be built into the kernel.
1586 Say M if you want these torture tests to build as a module.
1587 Say N if you are unsure.
1588
1589config WW_MUTEX_SELFTEST
1590 tristate "Wait/wound mutex selftests"
1591 help
1592 This option provides a kernel module that runs tests on the
1593 on the struct ww_mutex locking API.
1594
1595 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1596 with this test harness.
1597
1598 Say M if you want these self tests to build as a module.
1599 Say N if you are unsure.
1600
1601config SCF_TORTURE_TEST
1602 tristate "torture tests for smp_call_function*()"
1603 depends on DEBUG_KERNEL
1604 select TORTURE_TEST
1605 help
1606 This option provides a kernel module that runs torture tests
1607 on the smp_call_function() family of primitives. The kernel
1608 module may be built after the fact on the running kernel to
1609 be tested, if desired.
1610
1611config CSD_LOCK_WAIT_DEBUG
1612 bool "Debugging for csd_lock_wait(), called from smp_call_function*()"
1613 depends on DEBUG_KERNEL
1614 depends on SMP
1615 depends on 64BIT
1616 default n
1617 help
1618 This option enables debug prints when CPUs are slow to respond
1619 to the smp_call_function*() IPI wrappers. These debug prints
1620 include the IPI handler function currently executing (if any)
1621 and relevant stack traces.
1622
1623config CSD_LOCK_WAIT_DEBUG_DEFAULT
1624 bool "Default csd_lock_wait() debugging on at boot time"
1625 depends on CSD_LOCK_WAIT_DEBUG
1626 depends on 64BIT
1627 default n
1628 help
1629 This option causes the csdlock_debug= kernel boot parameter to
1630 default to 1 (basic debugging) instead of 0 (no debugging).
1631
1632endmenu # lock debugging
1633
1634config TRACE_IRQFLAGS
1635 depends on TRACE_IRQFLAGS_SUPPORT
1636 bool
1637 help
1638 Enables hooks to interrupt enabling and disabling for
1639 either tracing or lock debugging.
1640
1641config TRACE_IRQFLAGS_NMI
1642 def_bool y
1643 depends on TRACE_IRQFLAGS
1644 depends on TRACE_IRQFLAGS_NMI_SUPPORT
1645
1646config NMI_CHECK_CPU
1647 bool "Debugging for CPUs failing to respond to backtrace requests"
1648 depends on DEBUG_KERNEL
1649 depends on X86
1650 default n
1651 help
1652 Enables debug prints when a CPU fails to respond to a given
1653 backtrace NMI. These prints provide some reasons why a CPU
1654 might legitimately be failing to respond, for example, if it
1655 is offline of if ignore_nmis is set.
1656
1657config DEBUG_IRQFLAGS
1658 bool "Debug IRQ flag manipulation"
1659 help
1660 Enables checks for potentially unsafe enabling or disabling of
1661 interrupts, such as calling raw_local_irq_restore() when interrupts
1662 are enabled.
1663
1664config STACKTRACE
1665 bool "Stack backtrace support"
1666 depends on STACKTRACE_SUPPORT
1667 help
1668 This option causes the kernel to create a /proc/pid/stack for
1669 every process, showing its current stack trace.
1670 It is also used by various kernel debugging features that require
1671 stack trace generation.
1672
1673config WARN_ALL_UNSEEDED_RANDOM
1674 bool "Warn for all uses of unseeded randomness"
1675 default n
1676 help
1677 Some parts of the kernel contain bugs relating to their use of
1678 cryptographically secure random numbers before it's actually possible
1679 to generate those numbers securely. This setting ensures that these
1680 flaws don't go unnoticed, by enabling a message, should this ever
1681 occur. This will allow people with obscure setups to know when things
1682 are going wrong, so that they might contact developers about fixing
1683 it.
1684
1685 Unfortunately, on some models of some architectures getting
1686 a fully seeded CRNG is extremely difficult, and so this can
1687 result in dmesg getting spammed for a surprisingly long
1688 time. This is really bad from a security perspective, and
1689 so architecture maintainers really need to do what they can
1690 to get the CRNG seeded sooner after the system is booted.
1691 However, since users cannot do anything actionable to
1692 address this, by default this option is disabled.
1693
1694 Say Y here if you want to receive warnings for all uses of
1695 unseeded randomness. This will be of use primarily for
1696 those developers interested in improving the security of
1697 Linux kernels running on their architecture (or
1698 subarchitecture).
1699
1700config DEBUG_KOBJECT
1701 bool "kobject debugging"
1702 depends on DEBUG_KERNEL
1703 help
1704 If you say Y here, some extra kobject debugging messages will be sent
1705 to the syslog.
1706
1707config DEBUG_KOBJECT_RELEASE
1708 bool "kobject release debugging"
1709 depends on DEBUG_OBJECTS_TIMERS
1710 help
1711 kobjects are reference counted objects. This means that their
1712 last reference count put is not predictable, and the kobject can
1713 live on past the point at which a driver decides to drop its
1714 initial reference to the kobject gained on allocation. An
1715 example of this would be a struct device which has just been
1716 unregistered.
1717
1718 However, some buggy drivers assume that after such an operation,
1719 the memory backing the kobject can be immediately freed. This
1720 goes completely against the principles of a refcounted object.
1721
1722 If you say Y here, the kernel will delay the release of kobjects
1723 on the last reference count to improve the visibility of this
1724 kind of kobject release bug.
1725
1726config HAVE_DEBUG_BUGVERBOSE
1727 bool
1728
1729menu "Debug kernel data structures"
1730
1731config DEBUG_LIST
1732 bool "Debug linked list manipulation"
1733 depends on DEBUG_KERNEL
1734 select LIST_HARDENED
1735 help
1736 Enable this to turn on extended checks in the linked-list walking
1737 routines.
1738
1739 This option trades better quality error reports for performance, and
1740 is more suitable for kernel debugging. If you care about performance,
1741 you should only enable CONFIG_LIST_HARDENED instead.
1742
1743 If unsure, say N.
1744
1745config DEBUG_PLIST
1746 bool "Debug priority linked list manipulation"
1747 depends on DEBUG_KERNEL
1748 help
1749 Enable this to turn on extended checks in the priority-ordered
1750 linked-list (plist) walking routines. This checks the entire
1751 list multiple times during each manipulation.
1752
1753 If unsure, say N.
1754
1755config DEBUG_SG
1756 bool "Debug SG table operations"
1757 depends on DEBUG_KERNEL
1758 help
1759 Enable this to turn on checks on scatter-gather tables. This can
1760 help find problems with drivers that do not properly initialize
1761 their sg tables.
1762
1763 If unsure, say N.
1764
1765config DEBUG_NOTIFIERS
1766 bool "Debug notifier call chains"
1767 depends on DEBUG_KERNEL
1768 help
1769 Enable this to turn on sanity checking for notifier call chains.
1770 This is most useful for kernel developers to make sure that
1771 modules properly unregister themselves from notifier chains.
1772 This is a relatively cheap check but if you care about maximum
1773 performance, say N.
1774
1775config DEBUG_CLOSURES
1776 bool "Debug closures (bcache async widgits)"
1777 depends on CLOSURES
1778 select DEBUG_FS
1779 help
1780 Keeps all active closures in a linked list and provides a debugfs
1781 interface to list them, which makes it possible to see asynchronous
1782 operations that get stuck.
1783
1784config DEBUG_MAPLE_TREE
1785 bool "Debug maple trees"
1786 depends on DEBUG_KERNEL
1787 help
1788 Enable maple tree debugging information and extra validations.
1789
1790 If unsure, say N.
1791
1792endmenu
1793
1794source "kernel/rcu/Kconfig.debug"
1795
1796config DEBUG_WQ_FORCE_RR_CPU
1797 bool "Force round-robin CPU selection for unbound work items"
1798 depends on DEBUG_KERNEL
1799 default n
1800 help
1801 Workqueue used to implicitly guarantee that work items queued
1802 without explicit CPU specified are put on the local CPU. This
1803 guarantee is no longer true and while local CPU is still
1804 preferred work items may be put on foreign CPUs. Kernel
1805 parameter "workqueue.debug_force_rr_cpu" is added to force
1806 round-robin CPU selection to flush out usages which depend on the
1807 now broken guarantee. This config option enables the debug
1808 feature by default. When enabled, memory and cache locality will
1809 be impacted.
1810
1811config CPU_HOTPLUG_STATE_CONTROL
1812 bool "Enable CPU hotplug state control"
1813 depends on DEBUG_KERNEL
1814 depends on HOTPLUG_CPU
1815 default n
1816 help
1817 Allows to write steps between "offline" and "online" to the CPUs
1818 sysfs target file so states can be stepped granular. This is a debug
1819 option for now as the hotplug machinery cannot be stopped and
1820 restarted at arbitrary points yet.
1821
1822 Say N if your are unsure.
1823
1824config LATENCYTOP
1825 bool "Latency measuring infrastructure"
1826 depends on DEBUG_KERNEL
1827 depends on STACKTRACE_SUPPORT
1828 depends on PROC_FS
1829 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
1830 select KALLSYMS
1831 select KALLSYMS_ALL
1832 select STACKTRACE
1833 select SCHEDSTATS
1834 help
1835 Enable this option if you want to use the LatencyTOP tool
1836 to find out which userspace is blocking on what kernel operations.
1837
1838config DEBUG_CGROUP_REF
1839 bool "Disable inlining of cgroup css reference count functions"
1840 depends on DEBUG_KERNEL
1841 depends on CGROUPS
1842 depends on KPROBES
1843 default n
1844 help
1845 Force cgroup css reference count functions to not be inlined so
1846 that they can be kprobed for debugging.
1847
1848source "kernel/trace/Kconfig"
1849
1850config PROVIDE_OHCI1394_DMA_INIT
1851 bool "Remote debugging over FireWire early on boot"
1852 depends on PCI && X86
1853 help
1854 If you want to debug problems which hang or crash the kernel early
1855 on boot and the crashing machine has a FireWire port, you can use
1856 this feature to remotely access the memory of the crashed machine
1857 over FireWire. This employs remote DMA as part of the OHCI1394
1858 specification which is now the standard for FireWire controllers.
1859
1860 With remote DMA, you can monitor the printk buffer remotely using
1861 firescope and access all memory below 4GB using fireproxy from gdb.
1862 Even controlling a kernel debugger is possible using remote DMA.
1863
1864 Usage:
1865
1866 If ohci1394_dma=early is used as boot parameter, it will initialize
1867 all OHCI1394 controllers which are found in the PCI config space.
1868
1869 As all changes to the FireWire bus such as enabling and disabling
1870 devices cause a bus reset and thereby disable remote DMA for all
1871 devices, be sure to have the cable plugged and FireWire enabled on
1872 the debugging host before booting the debug target for debugging.
1873
1874 This code (~1k) is freed after boot. By then, the firewire stack
1875 in charge of the OHCI-1394 controllers should be used instead.
1876
1877 See Documentation/core-api/debugging-via-ohci1394.rst for more information.
1878
1879source "samples/Kconfig"
1880
1881config ARCH_HAS_DEVMEM_IS_ALLOWED
1882 bool
1883
1884config STRICT_DEVMEM
1885 bool "Filter access to /dev/mem"
1886 depends on MMU && DEVMEM
1887 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED
1888 default y if PPC || X86 || ARM64 || S390
1889 help
1890 If this option is disabled, you allow userspace (root) access to all
1891 of memory, including kernel and userspace memory. Accidental
1892 access to this is obviously disastrous, but specific access can
1893 be used by people debugging the kernel. Note that with PAT support
1894 enabled, even in this case there are restrictions on /dev/mem
1895 use due to the cache aliasing requirements.
1896
1897 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
1898 file only allows userspace access to PCI space and the BIOS code and
1899 data regions. This is sufficient for dosemu and X and all common
1900 users of /dev/mem.
1901
1902 If in doubt, say Y.
1903
1904config IO_STRICT_DEVMEM
1905 bool "Filter I/O access to /dev/mem"
1906 depends on STRICT_DEVMEM
1907 help
1908 If this option is disabled, you allow userspace (root) access to all
1909 io-memory regardless of whether a driver is actively using that
1910 range. Accidental access to this is obviously disastrous, but
1911 specific access can be used by people debugging kernel drivers.
1912
1913 If this option is switched on, the /dev/mem file only allows
1914 userspace access to *idle* io-memory ranges (see /proc/iomem) This
1915 may break traditional users of /dev/mem (dosemu, legacy X, etc...)
1916 if the driver using a given range cannot be disabled.
1917
1918 If in doubt, say Y.
1919
1920menu "$(SRCARCH) Debugging"
1921
1922source "arch/$(SRCARCH)/Kconfig.debug"
1923
1924endmenu
1925
1926menu "Kernel Testing and Coverage"
1927
1928source "lib/kunit/Kconfig"
1929
1930config NOTIFIER_ERROR_INJECTION
1931 tristate "Notifier error injection"
1932 depends on DEBUG_KERNEL
1933 select DEBUG_FS
1934 help
1935 This option provides the ability to inject artificial errors to
1936 specified notifier chain callbacks. It is useful to test the error
1937 handling of notifier call chain failures.
1938
1939 Say N if unsure.
1940
1941config PM_NOTIFIER_ERROR_INJECT
1942 tristate "PM notifier error injection module"
1943 depends on PM && NOTIFIER_ERROR_INJECTION
1944 default m if PM_DEBUG
1945 help
1946 This option provides the ability to inject artificial errors to
1947 PM notifier chain callbacks. It is controlled through debugfs
1948 interface /sys/kernel/debug/notifier-error-inject/pm
1949
1950 If the notifier call chain should be failed with some events
1951 notified, write the error code to "actions/<notifier event>/error".
1952
1953 Example: Inject PM suspend error (-12 = -ENOMEM)
1954
1955 # cd /sys/kernel/debug/notifier-error-inject/pm/
1956 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1957 # echo mem > /sys/power/state
1958 bash: echo: write error: Cannot allocate memory
1959
1960 To compile this code as a module, choose M here: the module will
1961 be called pm-notifier-error-inject.
1962
1963 If unsure, say N.
1964
1965config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1966 tristate "OF reconfig notifier error injection module"
1967 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1968 help
1969 This option provides the ability to inject artificial errors to
1970 OF reconfig notifier chain callbacks. It is controlled
1971 through debugfs interface under
1972 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1973
1974 If the notifier call chain should be failed with some events
1975 notified, write the error code to "actions/<notifier event>/error".
1976
1977 To compile this code as a module, choose M here: the module will
1978 be called of-reconfig-notifier-error-inject.
1979
1980 If unsure, say N.
1981
1982config NETDEV_NOTIFIER_ERROR_INJECT
1983 tristate "Netdev notifier error injection module"
1984 depends on NET && NOTIFIER_ERROR_INJECTION
1985 help
1986 This option provides the ability to inject artificial errors to
1987 netdevice notifier chain callbacks. It is controlled through debugfs
1988 interface /sys/kernel/debug/notifier-error-inject/netdev
1989
1990 If the notifier call chain should be failed with some events
1991 notified, write the error code to "actions/<notifier event>/error".
1992
1993 Example: Inject netdevice mtu change error (-22 = -EINVAL)
1994
1995 # cd /sys/kernel/debug/notifier-error-inject/netdev
1996 # echo -22 > actions/NETDEV_CHANGEMTU/error
1997 # ip link set eth0 mtu 1024
1998 RTNETLINK answers: Invalid argument
1999
2000 To compile this code as a module, choose M here: the module will
2001 be called netdev-notifier-error-inject.
2002
2003 If unsure, say N.
2004
2005config FUNCTION_ERROR_INJECTION
2006 bool "Fault-injections of functions"
2007 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
2008 help
2009 Add fault injections into various functions that are annotated with
2010 ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return
2011 value of these functions. This is useful to test error paths of code.
2012
2013 If unsure, say N
2014
2015config FAULT_INJECTION
2016 bool "Fault-injection framework"
2017 depends on DEBUG_KERNEL
2018 help
2019 Provide fault-injection framework.
2020 For more details, see Documentation/fault-injection/.
2021
2022config FAILSLAB
2023 bool "Fault-injection capability for kmalloc"
2024 depends on FAULT_INJECTION
2025 help
2026 Provide fault-injection capability for kmalloc.
2027
2028config FAIL_PAGE_ALLOC
2029 bool "Fault-injection capability for alloc_pages()"
2030 depends on FAULT_INJECTION
2031 help
2032 Provide fault-injection capability for alloc_pages().
2033
2034config FAULT_INJECTION_USERCOPY
2035 bool "Fault injection capability for usercopy functions"
2036 depends on FAULT_INJECTION
2037 help
2038 Provides fault-injection capability to inject failures
2039 in usercopy functions (copy_from_user(), get_user(), ...).
2040
2041config FAIL_MAKE_REQUEST
2042 bool "Fault-injection capability for disk IO"
2043 depends on FAULT_INJECTION && BLOCK
2044 help
2045 Provide fault-injection capability for disk IO.
2046
2047config FAIL_IO_TIMEOUT
2048 bool "Fault-injection capability for faking disk interrupts"
2049 depends on FAULT_INJECTION && BLOCK
2050 help
2051 Provide fault-injection capability on end IO handling. This
2052 will make the block layer "forget" an interrupt as configured,
2053 thus exercising the error handling.
2054
2055 Only works with drivers that use the generic timeout handling,
2056 for others it won't do anything.
2057
2058config FAIL_FUTEX
2059 bool "Fault-injection capability for futexes"
2060 select DEBUG_FS
2061 depends on FAULT_INJECTION && FUTEX
2062 help
2063 Provide fault-injection capability for futexes.
2064
2065config FAULT_INJECTION_DEBUG_FS
2066 bool "Debugfs entries for fault-injection capabilities"
2067 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
2068 help
2069 Enable configuration of fault-injection capabilities via debugfs.
2070
2071config FAIL_FUNCTION
2072 bool "Fault-injection capability for functions"
2073 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
2074 help
2075 Provide function-based fault-injection capability.
2076 This will allow you to override a specific function with a return
2077 with given return value. As a result, function caller will see
2078 an error value and have to handle it. This is useful to test the
2079 error handling in various subsystems.
2080
2081config FAIL_MMC_REQUEST
2082 bool "Fault-injection capability for MMC IO"
2083 depends on FAULT_INJECTION_DEBUG_FS && MMC
2084 help
2085 Provide fault-injection capability for MMC IO.
2086 This will make the mmc core return data errors. This is
2087 useful to test the error handling in the mmc block device
2088 and to test how the mmc host driver handles retries from
2089 the block device.
2090
2091config FAIL_SUNRPC
2092 bool "Fault-injection capability for SunRPC"
2093 depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG
2094 help
2095 Provide fault-injection capability for SunRPC and
2096 its consumers.
2097
2098config FAIL_SKB_REALLOC
2099 bool "Fault-injection capability forcing skb to reallocate"
2100 depends on FAULT_INJECTION_DEBUG_FS
2101 help
2102 Provide fault-injection capability that forces the skb to be
2103 reallocated, catching possible invalid pointers to the skb.
2104
2105 For more information, check
2106 Documentation/dev-tools/fault-injection/fault-injection.rst
2107
2108config FAULT_INJECTION_CONFIGFS
2109 bool "Configfs interface for fault-injection capabilities"
2110 depends on FAULT_INJECTION
2111 select CONFIGFS_FS
2112 help
2113 This option allows configfs-based drivers to dynamically configure
2114 fault-injection via configfs. Each parameter for driver-specific
2115 fault-injection can be made visible as a configfs attribute in a
2116 configfs group.
2117
2118
2119config FAULT_INJECTION_STACKTRACE_FILTER
2120 bool "stacktrace filter for fault-injection capabilities"
2121 depends on FAULT_INJECTION
2122 depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT
2123 select STACKTRACE
2124 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
2125 help
2126 Provide stacktrace filter for fault-injection capabilities
2127
2128config ARCH_HAS_KCOV
2129 bool
2130 help
2131 An architecture should select this when it can successfully
2132 build and run with CONFIG_KCOV. This typically requires
2133 disabling instrumentation for some early boot code.
2134
2135config CC_HAS_SANCOV_TRACE_PC
2136 def_bool $(cc-option,-fsanitize-coverage=trace-pc)
2137
2138
2139config KCOV
2140 bool "Code coverage for fuzzing"
2141 depends on ARCH_HAS_KCOV
2142 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
2143 depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \
2144 GCC_VERSION >= 120000 || CC_IS_CLANG
2145 select DEBUG_FS
2146 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
2147 select OBJTOOL if HAVE_NOINSTR_HACK
2148 help
2149 KCOV exposes kernel code coverage information in a form suitable
2150 for coverage-guided fuzzing (randomized testing).
2151
2152 For more details, see Documentation/dev-tools/kcov.rst.
2153
2154config KCOV_ENABLE_COMPARISONS
2155 bool "Enable comparison operands collection by KCOV"
2156 depends on KCOV
2157 depends on $(cc-option,-fsanitize-coverage=trace-cmp)
2158 help
2159 KCOV also exposes operands of every comparison in the instrumented
2160 code along with operand sizes and PCs of the comparison instructions.
2161 These operands can be used by fuzzing engines to improve the quality
2162 of fuzzing coverage.
2163
2164config KCOV_INSTRUMENT_ALL
2165 bool "Instrument all code by default"
2166 depends on KCOV
2167 default y
2168 help
2169 If you are doing generic system call fuzzing (like e.g. syzkaller),
2170 then you will want to instrument the whole kernel and you should
2171 say y here. If you are doing more targeted fuzzing (like e.g.
2172 filesystem fuzzing with AFL) then you will want to enable coverage
2173 for more specific subsets of files, and should say n here.
2174
2175config KCOV_IRQ_AREA_SIZE
2176 hex "Size of interrupt coverage collection area in words"
2177 depends on KCOV
2178 default 0x40000
2179 help
2180 KCOV uses preallocated per-cpu areas to collect coverage from
2181 soft interrupts. This specifies the size of those areas in the
2182 number of unsigned long words.
2183
2184config KCOV_SELFTEST
2185 bool "Perform short selftests on boot"
2186 depends on KCOV
2187 help
2188 Run short KCOV coverage collection selftests on boot.
2189 On test failure, causes the kernel to panic. Recommended to be
2190 enabled, ensuring critical functionality works as intended.
2191
2192menuconfig RUNTIME_TESTING_MENU
2193 bool "Runtime Testing"
2194 default y
2195
2196if RUNTIME_TESTING_MENU
2197
2198config TEST_DHRY
2199 tristate "Dhrystone benchmark test"
2200 help
2201 Enable this to include the Dhrystone 2.1 benchmark. This test
2202 calculates the number of Dhrystones per second, and the number of
2203 DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided
2204 by 1757 (the number of Dhrystones per second obtained on the VAX
2205 11/780, nominally a 1 MIPS machine).
2206
2207 To run the benchmark, it needs to be enabled explicitly, either from
2208 the kernel command line (when built-in), or from userspace (when
2209 built-in or modular).
2210
2211 Run once during kernel boot:
2212
2213 test_dhry.run
2214
2215 Set number of iterations from kernel command line:
2216
2217 test_dhry.iterations=<n>
2218
2219 Set number of iterations from userspace:
2220
2221 echo <n> > /sys/module/test_dhry/parameters/iterations
2222
2223 Trigger manual run from userspace:
2224
2225 echo y > /sys/module/test_dhry/parameters/run
2226
2227 If the number of iterations is <= 0, the test will devise a suitable
2228 number of iterations (test runs for at least 2s) automatically.
2229 This process takes ca. 4s.
2230
2231 If unsure, say N.
2232
2233config LKDTM
2234 tristate "Linux Kernel Dump Test Tool Module"
2235 depends on DEBUG_FS
2236 help
2237 This module enables testing of the different dumping mechanisms by
2238 inducing system failures at predefined crash points.
2239 If you don't need it: say N
2240 Choose M here to compile this code as a module. The module will be
2241 called lkdtm.
2242
2243 Documentation on how to use the module can be found in
2244 Documentation/fault-injection/provoke-crashes.rst
2245
2246config CPUMASK_KUNIT_TEST
2247 tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS
2248 depends on KUNIT
2249 default KUNIT_ALL_TESTS
2250 help
2251 Enable to turn on cpumask tests, running at boot or module load time.
2252
2253 For more information on KUnit and unit tests in general, please refer
2254 to the KUnit documentation in Documentation/dev-tools/kunit/.
2255
2256 If unsure, say N.
2257
2258config TEST_LIST_SORT
2259 tristate "Linked list sorting test" if !KUNIT_ALL_TESTS
2260 depends on KUNIT
2261 default KUNIT_ALL_TESTS
2262 help
2263 Enable this to turn on 'list_sort()' function test. This test is
2264 executed only once during system boot (so affects only boot time),
2265 or at module load time.
2266
2267 If unsure, say N.
2268
2269config TEST_MIN_HEAP
2270 tristate "Min heap test"
2271 depends on DEBUG_KERNEL || m
2272 help
2273 Enable this to turn on min heap function tests. This test is
2274 executed only once during system boot (so affects only boot time),
2275 or at module load time.
2276
2277 If unsure, say N.
2278
2279config TEST_SORT
2280 tristate "Array-based sort test" if !KUNIT_ALL_TESTS
2281 depends on KUNIT
2282 default KUNIT_ALL_TESTS
2283 help
2284 This option enables the self-test function of 'sort()' at boot,
2285 or at module load time.
2286
2287 If unsure, say N.
2288
2289config TEST_DIV64
2290 tristate "64bit/32bit division and modulo test"
2291 depends on DEBUG_KERNEL || m
2292 help
2293 Enable this to turn on 'do_div()' function test. This test is
2294 executed only once during system boot (so affects only boot time),
2295 or at module load time.
2296
2297 If unsure, say N.
2298
2299config TEST_MULDIV64
2300 tristate "mul_u64_u64_div_u64() test"
2301 depends on DEBUG_KERNEL || m
2302 help
2303 Enable this to turn on 'mul_u64_u64_div_u64()' function test.
2304 This test is executed only once during system boot (so affects
2305 only boot time), or at module load time.
2306
2307 If unsure, say N.
2308
2309config TEST_IOV_ITER
2310 tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS
2311 depends on KUNIT
2312 depends on MMU
2313 default KUNIT_ALL_TESTS
2314 help
2315 Enable this to turn on testing of the operation of the I/O iterator
2316 (iov_iter). This test is executed only once during system boot (so
2317 affects only boot time), or at module load time.
2318
2319 If unsure, say N.
2320
2321config KPROBES_SANITY_TEST
2322 tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS
2323 depends on DEBUG_KERNEL
2324 depends on KPROBES
2325 depends on KUNIT
2326 select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
2327 default KUNIT_ALL_TESTS
2328 help
2329 This option provides for testing basic kprobes functionality on
2330 boot. Samples of kprobe and kretprobe are inserted and
2331 verified for functionality.
2332
2333 Say N if you are unsure.
2334
2335config FPROBE_SANITY_TEST
2336 bool "Self test for fprobe"
2337 depends on DEBUG_KERNEL
2338 depends on FPROBE
2339 depends on KUNIT=y
2340 help
2341 This option will enable testing the fprobe when the system boot.
2342 A series of tests are made to verify that the fprobe is functioning
2343 properly.
2344
2345 Say N if you are unsure.
2346
2347config BACKTRACE_SELF_TEST
2348 tristate "Self test for the backtrace code"
2349 depends on DEBUG_KERNEL
2350 help
2351 This option provides a kernel module that can be used to test
2352 the kernel stack backtrace code. This option is not useful
2353 for distributions or general kernels, but only for kernel
2354 developers working on architecture code.
2355
2356 Note that if you want to also test saved backtraces, you will
2357 have to enable STACKTRACE as well.
2358
2359 Say N if you are unsure.
2360
2361config TEST_REF_TRACKER
2362 tristate "Self test for reference tracker"
2363 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
2364 select REF_TRACKER
2365 help
2366 This option provides a kernel module performing tests
2367 using reference tracker infrastructure.
2368
2369 Say N if you are unsure.
2370
2371config RBTREE_TEST
2372 tristate "Red-Black tree test"
2373 depends on DEBUG_KERNEL
2374 help
2375 A benchmark measuring the performance of the rbtree library.
2376 Also includes rbtree invariant checks.
2377
2378config REED_SOLOMON_TEST
2379 tristate "Reed-Solomon library test"
2380 depends on DEBUG_KERNEL || m
2381 select REED_SOLOMON
2382 select REED_SOLOMON_ENC16
2383 select REED_SOLOMON_DEC16
2384 help
2385 This option enables the self-test function of rslib at boot,
2386 or at module load time.
2387
2388 If unsure, say N.
2389
2390config INTERVAL_TREE_TEST
2391 tristate "Interval tree test"
2392 depends on DEBUG_KERNEL
2393 select INTERVAL_TREE
2394 help
2395 A benchmark measuring the performance of the interval tree library
2396
2397config PERCPU_TEST
2398 tristate "Per cpu operations test"
2399 depends on m && DEBUG_KERNEL
2400 help
2401 Enable this option to build test module which validates per-cpu
2402 operations.
2403
2404 If unsure, say N.
2405
2406config ATOMIC64_SELFTEST
2407 tristate "Perform an atomic64_t self-test"
2408 help
2409 Enable this option to test the atomic64_t functions at boot or
2410 at module load time.
2411
2412 If unsure, say N.
2413
2414config ASYNC_RAID6_TEST
2415 tristate "Self test for hardware accelerated raid6 recovery"
2416 depends on ASYNC_RAID6_RECOV
2417 select ASYNC_MEMCPY
2418 help
2419 This is a one-shot self test that permutes through the
2420 recovery of all the possible two disk failure scenarios for a
2421 N-disk array. Recovery is performed with the asynchronous
2422 raid6 recovery routines, and will optionally use an offload
2423 engine if one is available.
2424
2425 If unsure, say N.
2426
2427config TEST_HEXDUMP
2428 tristate "Test functions located in the hexdump module at runtime"
2429
2430config STRING_KUNIT_TEST
2431 tristate "KUnit test string functions at runtime" if !KUNIT_ALL_TESTS
2432 depends on KUNIT
2433 default KUNIT_ALL_TESTS
2434
2435config STRING_HELPERS_KUNIT_TEST
2436 tristate "KUnit test string helpers at runtime" if !KUNIT_ALL_TESTS
2437 depends on KUNIT
2438 default KUNIT_ALL_TESTS
2439
2440config TEST_KSTRTOX
2441 tristate "Test kstrto*() family of functions at runtime"
2442
2443config TEST_PRINTF
2444 tristate "Test printf() family of functions at runtime"
2445
2446config TEST_SCANF
2447 tristate "Test scanf() family of functions at runtime"
2448
2449config TEST_BITMAP
2450 tristate "Test bitmap_*() family of functions at runtime"
2451 help
2452 Enable this option to test the bitmap functions at boot.
2453
2454 If unsure, say N.
2455
2456config TEST_UUID
2457 tristate "Test functions located in the uuid module at runtime"
2458
2459config TEST_XARRAY
2460 tristate "Test the XArray code at runtime"
2461
2462config TEST_MAPLE_TREE
2463 tristate "Test the Maple Tree code at runtime or module load"
2464 help
2465 Enable this option to test the maple tree code functions at boot, or
2466 when the module is loaded. Enable "Debug Maple Trees" will enable
2467 more verbose output on failures.
2468
2469 If unsure, say N.
2470
2471config TEST_RHASHTABLE
2472 tristate "Perform selftest on resizable hash table"
2473 help
2474 Enable this option to test the rhashtable functions at boot.
2475
2476 If unsure, say N.
2477
2478config TEST_IDA
2479 tristate "Perform selftest on IDA functions"
2480
2481config TEST_MISC_MINOR
2482 tristate "Basic misc minor Kunit test" if !KUNIT_ALL_TESTS
2483 depends on KUNIT
2484 default KUNIT_ALL_TESTS
2485 help
2486 Kunit test for the misc minor.
2487 It tests misc minor functions for dynamic and misc dynamic minor.
2488 This include misc_xxx functions
2489
2490 If unsure, say N.
2491
2492config TEST_PARMAN
2493 tristate "Perform selftest on priority array manager"
2494 depends on PARMAN
2495 help
2496 Enable this option to test priority array manager on boot
2497 (or module load).
2498
2499 If unsure, say N.
2500
2501config TEST_IRQ_TIMINGS
2502 bool "IRQ timings selftest"
2503 depends on IRQ_TIMINGS
2504 help
2505 Enable this option to test the irq timings code on boot.
2506
2507 If unsure, say N.
2508
2509config TEST_LKM
2510 tristate "Test module loading with 'hello world' module"
2511 depends on m
2512 help
2513 This builds the "test_module" module that emits "Hello, world"
2514 on printk when loaded. It is designed to be used for basic
2515 evaluation of the module loading subsystem (for example when
2516 validating module verification). It lacks any extra dependencies,
2517 and will not normally be loaded by the system unless explicitly
2518 requested by name.
2519
2520 If unsure, say N.
2521
2522config TEST_BITOPS
2523 tristate "Test module for compilation of bitops operations"
2524 help
2525 This builds the "test_bitops" module that is much like the
2526 TEST_LKM module except that it does a basic exercise of the
2527 set/clear_bit macros and get_count_order/long to make sure there are
2528 no compiler warnings from C=1 sparse checker or -Wextra
2529 compilations. It has no dependencies and doesn't run or load unless
2530 explicitly requested by name. for example: modprobe test_bitops.
2531
2532 If unsure, say N.
2533
2534config TEST_VMALLOC
2535 tristate "Test module for stress/performance analysis of vmalloc allocator"
2536 default n
2537 depends on MMU
2538 depends on m
2539 help
2540 This builds the "test_vmalloc" module that should be used for
2541 stress and performance analysis. So, any new change for vmalloc
2542 subsystem can be evaluated from performance and stability point
2543 of view.
2544
2545 If unsure, say N.
2546
2547config TEST_BPF
2548 tristate "Test BPF filter functionality"
2549 depends on m && NET
2550 help
2551 This builds the "test_bpf" module that runs various test vectors
2552 against the BPF interpreter or BPF JIT compiler depending on the
2553 current setting. This is in particular useful for BPF JIT compiler
2554 development, but also to run regression tests against changes in
2555 the interpreter code. It also enables test stubs for eBPF maps and
2556 verifier used by user space verifier testsuite.
2557
2558 If unsure, say N.
2559
2560config TEST_BLACKHOLE_DEV
2561 tristate "Test blackhole netdev functionality"
2562 depends on m && NET
2563 help
2564 This builds the "test_blackhole_dev" module that validates the
2565 data path through this blackhole netdev.
2566
2567 If unsure, say N.
2568
2569config FIND_BIT_BENCHMARK
2570 tristate "Test find_bit functions"
2571 help
2572 This builds the "test_find_bit" module that measure find_*_bit()
2573 functions performance.
2574
2575 If unsure, say N.
2576
2577config TEST_FIRMWARE
2578 tristate "Test firmware loading via userspace interface"
2579 depends on FW_LOADER
2580 help
2581 This builds the "test_firmware" module that creates a userspace
2582 interface for testing firmware loading. This can be used to
2583 control the triggering of firmware loading without needing an
2584 actual firmware-using device. The contents can be rechecked by
2585 userspace.
2586
2587 If unsure, say N.
2588
2589config TEST_SYSCTL
2590 tristate "sysctl test driver"
2591 depends on PROC_SYSCTL
2592 help
2593 This builds the "test_sysctl" module. This driver enables to test the
2594 proc sysctl interfaces available to drivers safely without affecting
2595 production knobs which might alter system functionality.
2596
2597 If unsure, say N.
2598
2599config BITFIELD_KUNIT
2600 tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS
2601 depends on KUNIT
2602 default KUNIT_ALL_TESTS
2603 help
2604 Enable this option to test the bitfield functions at boot.
2605
2606 KUnit tests run during boot and output the results to the debug log
2607 in TAP format (http://testanything.org/). Only useful for kernel devs
2608 running the KUnit test harness, and not intended for inclusion into a
2609 production build.
2610
2611 For more information on KUnit and unit tests in general please refer
2612 to the KUnit documentation in Documentation/dev-tools/kunit/.
2613
2614 If unsure, say N.
2615
2616config CHECKSUM_KUNIT
2617 tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS
2618 depends on KUNIT
2619 default KUNIT_ALL_TESTS
2620 help
2621 Enable this option to test the checksum functions at boot.
2622
2623 KUnit tests run during boot and output the results to the debug log
2624 in TAP format (http://testanything.org/). Only useful for kernel devs
2625 running the KUnit test harness, and not intended for inclusion into a
2626 production build.
2627
2628 For more information on KUnit and unit tests in general please refer
2629 to the KUnit documentation in Documentation/dev-tools/kunit/.
2630
2631 If unsure, say N.
2632
2633config UTIL_MACROS_KUNIT
2634 tristate "KUnit test util_macros.h functions at runtime" if !KUNIT_ALL_TESTS
2635 depends on KUNIT
2636 default KUNIT_ALL_TESTS
2637 help
2638 Enable this option to test the util_macros.h function at boot.
2639
2640 KUnit tests run during boot and output the results to the debug log
2641 in TAP format (http://testanything.org/). Only useful for kernel devs
2642 running the KUnit test harness, and not intended for inclusion into a
2643 production build.
2644
2645 For more information on KUnit and unit tests in general please refer
2646 to the KUnit documentation in Documentation/dev-tools/kunit/.
2647
2648 If unsure, say N.
2649
2650config HASH_KUNIT_TEST
2651 tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS
2652 depends on KUNIT
2653 default KUNIT_ALL_TESTS
2654 help
2655 Enable this option to test the kernel's string (<linux/stringhash.h>), and
2656 integer (<linux/hash.h>) hash functions on boot.
2657
2658 KUnit tests run during boot and output the results to the debug log
2659 in TAP format (https://testanything.org/). Only useful for kernel devs
2660 running the KUnit test harness, and not intended for inclusion into a
2661 production build.
2662
2663 For more information on KUnit and unit tests in general please refer
2664 to the KUnit documentation in Documentation/dev-tools/kunit/.
2665
2666 This is intended to help people writing architecture-specific
2667 optimized versions. If unsure, say N.
2668
2669config RESOURCE_KUNIT_TEST
2670 tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS
2671 depends on KUNIT
2672 default KUNIT_ALL_TESTS
2673 select GET_FREE_REGION
2674 help
2675 This builds the resource API unit test.
2676 Tests the logic of API provided by resource.c and ioport.h.
2677 For more information on KUnit and unit tests in general please refer
2678 to the KUnit documentation in Documentation/dev-tools/kunit/.
2679
2680 If unsure, say N.
2681
2682config SYSCTL_KUNIT_TEST
2683 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS
2684 depends on KUNIT
2685 default KUNIT_ALL_TESTS
2686 help
2687 This builds the proc sysctl unit test, which runs on boot.
2688 Tests the API contract and implementation correctness of sysctl.
2689 For more information on KUnit and unit tests in general please refer
2690 to the KUnit documentation in Documentation/dev-tools/kunit/.
2691
2692 If unsure, say N.
2693
2694config LIST_KUNIT_TEST
2695 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS
2696 depends on KUNIT
2697 default KUNIT_ALL_TESTS
2698 help
2699 This builds the linked list KUnit test suite.
2700 It tests that the API and basic functionality of the list_head type
2701 and associated macros.
2702
2703 KUnit tests run during boot and output the results to the debug log
2704 in TAP format (https://testanything.org/). Only useful for kernel devs
2705 running the KUnit test harness, and not intended for inclusion into a
2706 production build.
2707
2708 For more information on KUnit and unit tests in general please refer
2709 to the KUnit documentation in Documentation/dev-tools/kunit/.
2710
2711 If unsure, say N.
2712
2713config HASHTABLE_KUNIT_TEST
2714 tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS
2715 depends on KUNIT
2716 default KUNIT_ALL_TESTS
2717 help
2718 This builds the hashtable KUnit test suite.
2719 It tests the basic functionality of the API defined in
2720 include/linux/hashtable.h. For more information on KUnit and
2721 unit tests in general please refer to the KUnit documentation
2722 in Documentation/dev-tools/kunit/.
2723
2724 If unsure, say N.
2725
2726config LINEAR_RANGES_TEST
2727 tristate "KUnit test for linear_ranges"
2728 depends on KUNIT
2729 select LINEAR_RANGES
2730 help
2731 This builds the linear_ranges unit test, which runs on boot.
2732 Tests the linear_ranges logic correctness.
2733 For more information on KUnit and unit tests in general please refer
2734 to the KUnit documentation in Documentation/dev-tools/kunit/.
2735
2736 If unsure, say N.
2737
2738config CMDLINE_KUNIT_TEST
2739 tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS
2740 depends on KUNIT
2741 default KUNIT_ALL_TESTS
2742 help
2743 This builds the cmdline API unit test.
2744 Tests the logic of API provided by cmdline.c.
2745 For more information on KUnit and unit tests in general please refer
2746 to the KUnit documentation in Documentation/dev-tools/kunit/.
2747
2748 If unsure, say N.
2749
2750config BITS_TEST
2751 tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS
2752 depends on KUNIT
2753 default KUNIT_ALL_TESTS
2754 help
2755 This builds the bits unit test.
2756 Tests the logic of macros defined in bits.h.
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 SLUB_KUNIT_TEST
2763 tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS
2764 depends on SLUB_DEBUG && KUNIT
2765 default KUNIT_ALL_TESTS
2766 help
2767 This builds SLUB allocator unit test.
2768 Tests SLUB cache debugging functionality.
2769 For more information on KUnit and unit tests in general please refer
2770 to the KUnit documentation in Documentation/dev-tools/kunit/.
2771
2772 If unsure, say N.
2773
2774config RATIONAL_KUNIT_TEST
2775 tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS
2776 depends on KUNIT && RATIONAL
2777 default KUNIT_ALL_TESTS
2778 help
2779 This builds the rational math unit test.
2780 For more information on KUnit and unit tests in general please refer
2781 to the KUnit documentation in Documentation/dev-tools/kunit/.
2782
2783 If unsure, say N.
2784
2785config MEMCPY_KUNIT_TEST
2786 tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS
2787 depends on KUNIT
2788 default KUNIT_ALL_TESTS
2789 help
2790 Builds unit tests for memcpy(), memmove(), and memset() functions.
2791 For more information on KUnit and unit tests in general please refer
2792 to the KUnit documentation in Documentation/dev-tools/kunit/.
2793
2794 If unsure, say N.
2795
2796config IS_SIGNED_TYPE_KUNIT_TEST
2797 tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS
2798 depends on KUNIT
2799 default KUNIT_ALL_TESTS
2800 help
2801 Builds unit tests for the is_signed_type() macro.
2802
2803 For more information on KUnit and unit tests in general please refer
2804 to the KUnit documentation in Documentation/dev-tools/kunit/.
2805
2806 If unsure, say N.
2807
2808config OVERFLOW_KUNIT_TEST
2809 tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS
2810 depends on KUNIT
2811 default KUNIT_ALL_TESTS
2812 help
2813 Builds unit tests for the check_*_overflow(), size_*(), allocation, and
2814 related functions.
2815
2816 For more information on KUnit and unit tests in general please refer
2817 to the KUnit documentation in Documentation/dev-tools/kunit/.
2818
2819 If unsure, say N.
2820
2821config STACKINIT_KUNIT_TEST
2822 tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS
2823 depends on KUNIT
2824 default KUNIT_ALL_TESTS
2825 help
2826 Test if the kernel is zero-initializing stack variables and
2827 padding. Coverage is controlled by compiler flags,
2828 CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO,
2829 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2830 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2831
2832config FORTIFY_KUNIT_TEST
2833 tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS
2834 depends on KUNIT
2835 default KUNIT_ALL_TESTS
2836 help
2837 Builds unit tests for checking internals of FORTIFY_SOURCE as used
2838 by the str*() and mem*() family of functions. For testing runtime
2839 traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests.
2840
2841config HW_BREAKPOINT_KUNIT_TEST
2842 bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS
2843 depends on HAVE_HW_BREAKPOINT
2844 depends on KUNIT=y
2845 default KUNIT_ALL_TESTS
2846 help
2847 Tests for hw_breakpoint constraints accounting.
2848
2849 If unsure, say N.
2850
2851config CRC_KUNIT_TEST
2852 tristate "KUnit tests for CRC functions" if !KUNIT_ALL_TESTS
2853 depends on KUNIT
2854 default KUNIT_ALL_TESTS
2855 select CRC16
2856 select CRC_T10DIF
2857 select CRC32
2858 select CRC64
2859 help
2860 Unit tests for the CRC library functions.
2861
2862 This is intended to help people writing architecture-specific
2863 optimized versions. If unsure, say N.
2864
2865config CRC_BENCHMARK
2866 bool "Benchmark for the CRC functions"
2867 depends on CRC_KUNIT_TEST
2868 help
2869 Include benchmarks in the KUnit test suite for the CRC functions.
2870
2871config SIPHASH_KUNIT_TEST
2872 tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS
2873 depends on KUNIT
2874 default KUNIT_ALL_TESTS
2875 help
2876 Enable this option to test the kernel's siphash (<linux/siphash.h>) hash
2877 functions on boot (or module load).
2878
2879 This is intended to help people writing architecture-specific
2880 optimized versions. If unsure, say N.
2881
2882config USERCOPY_KUNIT_TEST
2883 tristate "KUnit Test for user/kernel boundary protections"
2884 depends on KUNIT
2885 default KUNIT_ALL_TESTS
2886 help
2887 This builds the "usercopy_kunit" module that runs sanity checks
2888 on the copy_to/from_user infrastructure, making sure basic
2889 user/kernel boundary testing is working.
2890
2891config TEST_UDELAY
2892 tristate "udelay test driver"
2893 help
2894 This builds the "udelay_test" module that helps to make sure
2895 that udelay() is working properly.
2896
2897 If unsure, say N.
2898
2899config TEST_STATIC_KEYS
2900 tristate "Test static keys"
2901 depends on m
2902 help
2903 Test the static key interfaces.
2904
2905 If unsure, say N.
2906
2907config TEST_DYNAMIC_DEBUG
2908 tristate "Test DYNAMIC_DEBUG"
2909 depends on DYNAMIC_DEBUG
2910 help
2911 This module registers a tracer callback to count enabled
2912 pr_debugs in a 'do_debugging' function, then alters their
2913 enablements, calls the function, and compares counts.
2914
2915 If unsure, say N.
2916
2917config TEST_KMOD
2918 tristate "kmod stress tester"
2919 depends on m
2920 depends on NETDEVICES && NET_CORE && INET # for TUN
2921 depends on BLOCK
2922 depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS
2923 select TEST_LKM
2924 select XFS_FS
2925 select TUN
2926 select BTRFS_FS
2927 help
2928 Test the kernel's module loading mechanism: kmod. kmod implements
2929 support to load modules using the Linux kernel's usermode helper.
2930 This test provides a series of tests against kmod.
2931
2932 Although technically you can either build test_kmod as a module or
2933 into the kernel we disallow building it into the kernel since
2934 it stress tests request_module() and this will very likely cause
2935 some issues by taking over precious threads available from other
2936 module load requests, ultimately this could be fatal.
2937
2938 To run tests run:
2939
2940 tools/testing/selftests/kmod/kmod.sh --help
2941
2942 If unsure, say N.
2943
2944config TEST_RUNTIME
2945 bool
2946
2947config TEST_RUNTIME_MODULE
2948 bool
2949
2950config TEST_KALLSYMS
2951 tristate "module kallsyms find_symbol() test"
2952 depends on m
2953 select TEST_RUNTIME
2954 select TEST_RUNTIME_MODULE
2955 select TEST_KALLSYMS_A
2956 select TEST_KALLSYMS_B
2957 select TEST_KALLSYMS_C
2958 select TEST_KALLSYMS_D
2959 help
2960 This allows us to stress test find_symbol() through the kallsyms
2961 used to place symbols on the kernel ELF kallsyms and modules kallsyms
2962 where we place kernel symbols such as exported symbols.
2963
2964 We have four test modules:
2965
2966 A: has KALLSYSMS_NUMSYMS exported symbols
2967 B: uses one of A's symbols
2968 C: adds KALLSYMS_SCALE_FACTOR * KALLSYSMS_NUMSYMS exported
2969 D: adds 2 * the symbols than C
2970
2971 We stress test find_symbol() through two means:
2972
2973 1) Upon load of B it will trigger simplify_symbols() to look for the
2974 one symbol it uses from the module A with tons of symbols. This is an
2975 indirect way for us to have B call resolve_symbol_wait() upon module
2976 load. This will eventually call find_symbol() which will eventually
2977 try to find the symbols used with find_exported_symbol_in_section().
2978 find_exported_symbol_in_section() uses bsearch() so a binary search
2979 for each symbol. Binary search will at worst be O(log(n)) so the
2980 larger TEST_MODULE_KALLSYSMS the worse the search.
2981
2982 2) The selftests should load C first, before B. Upon B's load towards
2983 the end right before we call module B's init routine we get
2984 complete_formation() called on the module. That will first check
2985 for duplicate symbols with the call to verify_exported_symbols().
2986 That is when we'll force iteration on module C's insane symbol list.
2987 Since it has 10 * KALLSYMS_NUMSYMS it means we can first test
2988 just loading B without C. The amount of time it takes to load C Vs
2989 B can give us an idea of the impact growth of the symbol space and
2990 give us projection. Module A only uses one symbol from B so to allow
2991 this scaling in module C to be proportional, if it used more symbols
2992 then the first test would be doing more and increasing just the
2993 search space would be slightly different. The last module, module D
2994 will just increase the search space by twice the number of symbols in
2995 C so to allow for full projects.
2996
2997 tools/testing/selftests/module/find_symbol.sh
2998
2999 The current defaults will incur a build delay of about 7 minutes
3000 on an x86_64 with only 8 cores. Enable this only if you want to
3001 stress test find_symbol() with thousands of symbols. At the same
3002 time this is also useful to test building modules with thousands of
3003 symbols, and if BTF is enabled this also stress tests adding BTF
3004 information for each module. Currently enabling many more symbols
3005 will segfault the build system.
3006
3007 If unsure, say N.
3008
3009if TEST_KALLSYMS
3010
3011config TEST_KALLSYMS_A
3012 tristate
3013 depends on m
3014
3015config TEST_KALLSYMS_B
3016 tristate
3017 depends on m
3018
3019config TEST_KALLSYMS_C
3020 tristate
3021 depends on m
3022
3023config TEST_KALLSYMS_D
3024 tristate
3025 depends on m
3026
3027choice
3028 prompt "Kallsym test range"
3029 default TEST_KALLSYMS_LARGE
3030 help
3031 Selecting something other than "Fast" will enable tests which slow
3032 down the build and may crash your build.
3033
3034config TEST_KALLSYMS_FAST
3035 bool "Fast builds"
3036 help
3037 You won't really be testing kallsysms, so this just helps fast builds
3038 when allmodconfig is used..
3039
3040config TEST_KALLSYMS_LARGE
3041 bool "Enable testing kallsyms with large exports"
3042 help
3043 This will enable larger number of symbols. This will slow down
3044 your build considerably.
3045
3046config TEST_KALLSYMS_MAX
3047 bool "Known kallsysms limits"
3048 help
3049 This will enable exports to the point we know we'll start crashing
3050 builds.
3051
3052endchoice
3053
3054config TEST_KALLSYMS_NUMSYMS
3055 int "test kallsyms number of symbols"
3056 range 2 10000
3057 default 2 if TEST_KALLSYMS_FAST
3058 default 100 if TEST_KALLSYMS_LARGE
3059 default 10000 if TEST_KALLSYMS_MAX
3060 help
3061 The number of symbols to create on TEST_KALLSYMS_A, only one of which
3062 module TEST_KALLSYMS_B will use. This also will be used
3063 for how many symbols TEST_KALLSYMS_C will have, scaled up by
3064 TEST_KALLSYMS_SCALE_FACTOR. Note that setting this to 10,000 will
3065 trigger a segfault today, don't use anything close to it unless
3066 you are aware that this should not be used for automated build tests.
3067
3068config TEST_KALLSYMS_SCALE_FACTOR
3069 int "test kallsyms scale factor"
3070 default 8
3071 help
3072 How many more unusued symbols will TEST_KALLSYSMS_C have than
3073 TEST_KALLSYMS_A. If 8, then module C will have 8 * syms
3074 than module A. Then TEST_KALLSYMS_D will have double the amount
3075 of symbols than C so to allow projections.
3076
3077endif # TEST_KALLSYMS
3078
3079config TEST_DEBUG_VIRTUAL
3080 tristate "Test CONFIG_DEBUG_VIRTUAL feature"
3081 depends on DEBUG_VIRTUAL
3082 help
3083 Test the kernel's ability to detect incorrect calls to
3084 virt_to_phys() done against the non-linear part of the
3085 kernel's virtual address map.
3086
3087 If unsure, say N.
3088
3089config TEST_MEMCAT_P
3090 tristate "Test memcat_p() helper function"
3091 help
3092 Test the memcat_p() helper for correctly merging two
3093 pointer arrays together.
3094
3095 If unsure, say N.
3096
3097config TEST_OBJAGG
3098 tristate "Perform selftest on object aggreration manager"
3099 default n
3100 depends on OBJAGG
3101 help
3102 Enable this option to test object aggregation manager on boot
3103 (or module load).
3104
3105config TEST_MEMINIT
3106 tristate "Test heap/page initialization"
3107 help
3108 Test if the kernel is zero-initializing heap and page allocations.
3109 This can be useful to test init_on_alloc and init_on_free features.
3110
3111 If unsure, say N.
3112
3113config TEST_HMM
3114 tristate "Test HMM (Heterogeneous Memory Management)"
3115 depends on TRANSPARENT_HUGEPAGE
3116 depends on DEVICE_PRIVATE
3117 select HMM_MIRROR
3118 select MMU_NOTIFIER
3119 help
3120 This is a pseudo device driver solely for testing HMM.
3121 Say M here if you want to build the HMM test module.
3122 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests.
3123
3124 If unsure, say N.
3125
3126config TEST_FREE_PAGES
3127 tristate "Test freeing pages"
3128 help
3129 Test that a memory leak does not occur due to a race between
3130 freeing a block of pages and a speculative page reference.
3131 Loading this module is safe if your kernel has the bug fixed.
3132 If the bug is not fixed, it will leak gigabytes of memory and
3133 probably OOM your system.
3134
3135config TEST_FPU
3136 tristate "Test floating point operations in kernel space"
3137 depends on ARCH_HAS_KERNEL_FPU_SUPPORT && !KCOV_INSTRUMENT_ALL
3138 help
3139 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu
3140 which will trigger a sequence of floating point operations. This is used
3141 for self-testing floating point control register setting in
3142 kernel_fpu_begin().
3143
3144 If unsure, say N.
3145
3146config TEST_CLOCKSOURCE_WATCHDOG
3147 tristate "Test clocksource watchdog in kernel space"
3148 depends on CLOCKSOURCE_WATCHDOG
3149 help
3150 Enable this option to create a kernel module that will trigger
3151 a test of the clocksource watchdog. This module may be loaded
3152 via modprobe or insmod in which case it will run upon being
3153 loaded, or it may be built in, in which case it will run
3154 shortly after boot.
3155
3156 If unsure, say N.
3157
3158config TEST_OBJPOOL
3159 tristate "Test module for correctness and stress of objpool"
3160 default n
3161 depends on m && DEBUG_KERNEL
3162 help
3163 This builds the "test_objpool" module that should be used for
3164 correctness verification and concurrent testings of objects
3165 allocation and reclamation.
3166
3167 If unsure, say N.
3168
3169config INT_POW_TEST
3170 tristate "Integer exponentiation (int_pow) test" if !KUNIT_ALL_TESTS
3171 depends on KUNIT
3172 default KUNIT_ALL_TESTS
3173 help
3174 This option enables the KUnit test suite for the int_pow function,
3175 which performs integer exponentiation. The test suite is designed to
3176 verify that the implementation of int_pow correctly computes the power
3177 of a given base raised to a given exponent.
3178
3179 Enabling this option will include tests that check various scenarios
3180 and edge cases to ensure the accuracy and reliability of the exponentiation
3181 function.
3182
3183 If unsure, say N
3184
3185config INT_SQRT_KUNIT_TEST
3186 tristate "Integer square root test" if !KUNIT_ALL_TESTS
3187 depends on KUNIT
3188 default KUNIT_ALL_TESTS
3189 help
3190 This option enables the KUnit test suite for the int_sqrt() function,
3191 which performs square root calculation. The test suite checks
3192 various scenarios, including edge cases, to ensure correctness.
3193
3194 Enabling this option will include tests that check various scenarios
3195 and edge cases to ensure the accuracy and reliability of the square root
3196 function.
3197
3198 If unsure, say N
3199
3200endif # RUNTIME_TESTING_MENU
3201
3202config ARCH_USE_MEMTEST
3203 bool
3204 help
3205 An architecture should select this when it uses early_memtest()
3206 during boot process.
3207
3208config MEMTEST
3209 bool "Memtest"
3210 depends on ARCH_USE_MEMTEST
3211 help
3212 This option adds a kernel parameter 'memtest', which allows memtest
3213 to be set and executed.
3214 memtest=0, mean disabled; -- default
3215 memtest=1, mean do 1 test pattern;
3216 ...
3217 memtest=17, mean do 17 test patterns.
3218 If you are unsure how to answer this question, answer N.
3219
3220
3221
3222config HYPERV_TESTING
3223 bool "Microsoft Hyper-V driver testing"
3224 default n
3225 depends on HYPERV && DEBUG_FS
3226 help
3227 Select this option to enable Hyper-V vmbus testing.
3228
3229endmenu # "Kernel Testing and Coverage"
3230
3231menu "Rust hacking"
3232
3233config RUST_DEBUG_ASSERTIONS
3234 bool "Debug assertions"
3235 depends on RUST
3236 help
3237 Enables rustc's `-Cdebug-assertions` codegen option.
3238
3239 This flag lets you turn `cfg(debug_assertions)` conditional
3240 compilation on or off. This can be used to enable extra debugging
3241 code in development but not in production. For example, it controls
3242 the behavior of the standard library's `debug_assert!` macro.
3243
3244 Note that this will apply to all Rust code, including `core`.
3245
3246 If unsure, say N.
3247
3248config RUST_OVERFLOW_CHECKS
3249 bool "Overflow checks"
3250 default y
3251 depends on RUST
3252 help
3253 Enables rustc's `-Coverflow-checks` codegen option.
3254
3255 This flag allows you to control the behavior of runtime integer
3256 overflow. When overflow-checks are enabled, a Rust panic will occur
3257 on overflow.
3258
3259 Note that this will apply to all Rust code, including `core`.
3260
3261 If unsure, say Y.
3262
3263config RUST_BUILD_ASSERT_ALLOW
3264 bool "Allow unoptimized build-time assertions"
3265 depends on RUST
3266 help
3267 Controls how `build_error!` and `build_assert!` are handled during the build.
3268
3269 If calls to them exist in the binary, it may indicate a violated invariant
3270 or that the optimizer failed to verify the invariant during compilation.
3271
3272 This should not happen, thus by default the build is aborted. However,
3273 as an escape hatch, you can choose Y here to ignore them during build
3274 and let the check be carried at runtime (with `panic!` being called if
3275 the check fails).
3276
3277 If unsure, say N.
3278
3279config RUST_KERNEL_DOCTESTS
3280 bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS
3281 depends on RUST && KUNIT=y
3282 default KUNIT_ALL_TESTS
3283 help
3284 This builds the documentation tests of the `kernel` crate
3285 as KUnit tests.
3286
3287 For more information on KUnit and unit tests in general,
3288 please refer to the KUnit documentation in Documentation/dev-tools/kunit/.
3289
3290 If unsure, say N.
3291
3292endmenu # "Rust"
3293
3294endmenu # Kernel hacking
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