Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1# SPDX-License-Identifier: GPL-2.0-only
2menu "Kernel hacking"
3
4menu "printk and dmesg options"
5
6config PRINTK_TIME
7 bool "Show timing information on printks"
8 depends on PRINTK
9 help
10 Selecting this option causes time stamps of the printk()
11 messages to be added to the output of the syslog() system
12 call and at the console.
13
14 The timestamp is always recorded internally, and exported
15 to /dev/kmsg. This flag just specifies if the timestamp should
16 be included, not that the timestamp is recorded.
17
18 The behavior is also controlled by the kernel command line
19 parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst
20
21config PRINTK_CALLER
22 bool "Show caller information on printks"
23 depends on PRINTK
24 help
25 Selecting this option causes printk() to add a caller "thread id" (if
26 in task context) or a caller "processor id" (if not in task context)
27 to every message.
28
29 This option is intended for environments where multiple threads
30 concurrently call printk() for many times, for it is difficult to
31 interpret without knowing where these lines (or sometimes individual
32 line which was divided into multiple lines due to race) came from.
33
34 Since toggling after boot makes the code racy, currently there is
35 no option to enable/disable at the kernel command line parameter or
36 sysfs interface.
37
38config STACKTRACE_BUILD_ID
39 bool "Show build ID information in stacktraces"
40 depends on PRINTK
41 help
42 Selecting this option adds build ID information for symbols in
43 stacktraces printed with the printk format '%p[SR]b'.
44
45 This option is intended for distros where debuginfo is not easily
46 accessible but can be downloaded given the build ID of the vmlinux or
47 kernel module where the function is located.
48
49config CONSOLE_LOGLEVEL_DEFAULT
50 int "Default console loglevel (1-15)"
51 range 1 15
52 default "7"
53 help
54 Default loglevel to determine what will be printed on the console.
55
56 Setting a default here is equivalent to passing in loglevel=<x> in
57 the kernel bootargs. loglevel=<x> continues to override whatever
58 value is specified here as well.
59
60 Note: This does not affect the log level of un-prefixed printk()
61 usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT
62 option.
63
64config CONSOLE_LOGLEVEL_QUIET
65 int "quiet console loglevel (1-15)"
66 range 1 15
67 default "4"
68 help
69 loglevel to use when "quiet" is passed on the kernel commandline.
70
71 When "quiet" is passed on the kernel commandline this loglevel
72 will be used as the loglevel. IOW passing "quiet" will be the
73 equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>"
74
75config MESSAGE_LOGLEVEL_DEFAULT
76 int "Default message log level (1-7)"
77 range 1 7
78 default "4"
79 help
80 Default log level for printk statements with no specified priority.
81
82 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
83 that are auditing their logs closely may want to set it to a lower
84 priority.
85
86 Note: This does not affect what message level gets printed on the console
87 by default. To change that, use loglevel=<x> in the kernel bootargs,
88 or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value.
89
90config BOOT_PRINTK_DELAY
91 bool "Delay each boot printk message by N milliseconds"
92 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
93 help
94 This build option allows you to read kernel boot messages
95 by inserting a short delay after each one. The delay is
96 specified in milliseconds on the kernel command line,
97 using "boot_delay=N".
98
99 It is likely that you would also need to use "lpj=M" to preset
100 the "loops per jiffie" value.
101 See a previous boot log for the "lpj" value to use for your
102 system, and then set "lpj=M" before setting "boot_delay=N".
103 NOTE: Using this option may adversely affect SMP systems.
104 I.e., processors other than the first one may not boot up.
105 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
106 what it believes to be lockup conditions.
107
108config DYNAMIC_DEBUG
109 bool "Enable dynamic printk() support"
110 default n
111 depends on PRINTK
112 depends on (DEBUG_FS || PROC_FS)
113 select DYNAMIC_DEBUG_CORE
114 help
115
116 Compiles debug level messages into the kernel, which would not
117 otherwise be available at runtime. These messages can then be
118 enabled/disabled based on various levels of scope - per source file,
119 function, module, format string, and line number. This mechanism
120 implicitly compiles in all pr_debug() and dev_dbg() calls, which
121 enlarges the kernel text size by about 2%.
122
123 If a source file is compiled with DEBUG flag set, any
124 pr_debug() calls in it are enabled by default, but can be
125 disabled at runtime as below. Note that DEBUG flag is
126 turned on by many CONFIG_*DEBUG* options.
127
128 Usage:
129
130 Dynamic debugging is controlled via the 'dynamic_debug/control' file,
131 which is contained in the 'debugfs' filesystem or procfs.
132 Thus, the debugfs or procfs filesystem must first be mounted before
133 making use of this feature.
134 We refer the control file as: <debugfs>/dynamic_debug/control. This
135 file contains a list of the debug statements that can be enabled. The
136 format for each line of the file is:
137
138 filename:lineno [module]function flags format
139
140 filename : source file of the debug statement
141 lineno : line number of the debug statement
142 module : module that contains the debug statement
143 function : function that contains the debug statement
144 flags : '=p' means the line is turned 'on' for printing
145 format : the format used for the debug statement
146
147 From a live system:
148
149 nullarbor:~ # cat <debugfs>/dynamic_debug/control
150 # filename:lineno [module]function flags format
151 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
152 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
153 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
154
155 Example usage:
156
157 // enable the message at line 1603 of file svcsock.c
158 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
159 <debugfs>/dynamic_debug/control
160
161 // enable all the messages in file svcsock.c
162 nullarbor:~ # echo -n 'file svcsock.c +p' >
163 <debugfs>/dynamic_debug/control
164
165 // enable all the messages in the NFS server module
166 nullarbor:~ # echo -n 'module nfsd +p' >
167 <debugfs>/dynamic_debug/control
168
169 // enable all 12 messages in the function svc_process()
170 nullarbor:~ # echo -n 'func svc_process +p' >
171 <debugfs>/dynamic_debug/control
172
173 // disable all 12 messages in the function svc_process()
174 nullarbor:~ # echo -n 'func svc_process -p' >
175 <debugfs>/dynamic_debug/control
176
177 See Documentation/admin-guide/dynamic-debug-howto.rst for additional
178 information.
179
180config DYNAMIC_DEBUG_CORE
181 bool "Enable core function of dynamic debug support"
182 depends on PRINTK
183 depends on (DEBUG_FS || PROC_FS)
184 help
185 Enable core functional support of dynamic debug. It is useful
186 when you want to tie dynamic debug to your kernel modules with
187 DYNAMIC_DEBUG_MODULE defined for each of them, especially for
188 the case of embedded system where the kernel image size is
189 sensitive for people.
190
191config SYMBOLIC_ERRNAME
192 bool "Support symbolic error names in printf"
193 default y if PRINTK
194 help
195 If you say Y here, the kernel's printf implementation will
196 be able to print symbolic error names such as ENOSPC instead
197 of the number 28. It makes the kernel image slightly larger
198 (about 3KB), but can make the kernel logs easier to read.
199
200config DEBUG_BUGVERBOSE
201 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
202 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
203 default y
204 help
205 Say Y here to make BUG() panics output the file name and line number
206 of the BUG call as well as the EIP and oops trace. This aids
207 debugging but costs about 70-100K of memory.
208
209endmenu # "printk and dmesg options"
210
211config DEBUG_KERNEL
212 bool "Kernel debugging"
213 help
214 Say Y here if you are developing drivers or trying to debug and
215 identify kernel problems.
216
217config DEBUG_MISC
218 bool "Miscellaneous debug code"
219 default DEBUG_KERNEL
220 depends on DEBUG_KERNEL
221 help
222 Say Y here if you need to enable miscellaneous debug code that should
223 be under a more specific debug option but isn't.
224
225menu "Compile-time checks and compiler options"
226
227config DEBUG_INFO
228 bool
229 help
230 A kernel debug info option other than "None" has been selected
231 in the "Debug information" choice below, indicating that debug
232 information will be generated for build targets.
233
234# Clang 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 !DEBUG_INFO_DWARF5 || PAHOLE_VERSION >= 121
383 # pahole uses elfutils, which does not have support for Hexagon relocations
384 depends on !HEXAGON
385 help
386 Generate deduplicated BTF type information from DWARF debug info.
387 Turning this on expects presence of pahole tool, which will convert
388 DWARF type info into equivalent deduplicated BTF type info.
389
390config PAHOLE_HAS_SPLIT_BTF
391 def_bool PAHOLE_VERSION >= 119
392
393config PAHOLE_HAS_BTF_TAG
394 def_bool PAHOLE_VERSION >= 123
395 depends on CC_IS_CLANG
396 help
397 Decide whether pahole emits btf_tag attributes (btf_type_tag and
398 btf_decl_tag) or not. Currently only clang compiler implements
399 these attributes, so make the config depend on CC_IS_CLANG.
400
401config PAHOLE_HAS_LANG_EXCLUDE
402 def_bool PAHOLE_VERSION >= 124
403 help
404 Support for the --lang_exclude flag which makes pahole exclude
405 compilation units from the supplied language. Used in Kbuild to
406 omit Rust CUs which are not supported in version 1.24 of pahole,
407 otherwise it would emit malformed kernel and module binaries when
408 using DEBUG_INFO_BTF_MODULES.
409
410config DEBUG_INFO_BTF_MODULES
411 bool "Generate BTF type information for kernel modules"
412 default y
413 depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF
414 help
415 Generate compact split BTF type information for kernel modules.
416
417config MODULE_ALLOW_BTF_MISMATCH
418 bool "Allow loading modules with non-matching BTF type info"
419 depends on DEBUG_INFO_BTF_MODULES
420 help
421 For modules whose split BTF does not match vmlinux, load without
422 BTF rather than refusing to load. The default behavior with
423 module BTF enabled is to reject modules with such mismatches;
424 this option will still load module BTF where possible but ignore
425 it when a mismatch is found.
426
427config GDB_SCRIPTS
428 bool "Provide GDB scripts for kernel debugging"
429 help
430 This creates the required links to GDB helper scripts in the
431 build directory. If you load vmlinux into gdb, the helper
432 scripts will be automatically imported by gdb as well, and
433 additional functions are available to analyze a Linux kernel
434 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
435 for further details.
436
437endif # DEBUG_INFO
438
439config FRAME_WARN
440 int "Warn for stack frames larger than"
441 range 0 8192
442 default 0 if KMSAN
443 default 2048 if GCC_PLUGIN_LATENT_ENTROPY
444 default 2048 if PARISC
445 default 1536 if (!64BIT && XTENSA)
446 default 1280 if KASAN && !64BIT
447 default 1024 if !64BIT
448 default 2048 if 64BIT
449 help
450 Tell the compiler to warn at build time for stack frames larger than this.
451 Setting this too low will cause a lot of warnings.
452 Setting it to 0 disables the warning.
453
454config STRIP_ASM_SYMS
455 bool "Strip assembler-generated symbols during link"
456 default n
457 help
458 Strip internal assembler-generated symbols during a link (symbols
459 that look like '.Lxxx') so they don't pollute the output of
460 get_wchan() and suchlike.
461
462config READABLE_ASM
463 bool "Generate readable assembler code"
464 depends on DEBUG_KERNEL
465 depends on CC_IS_GCC
466 help
467 Disable some compiler optimizations that tend to generate human unreadable
468 assembler output. This may make the kernel slightly slower, but it helps
469 to keep kernel developers who have to stare a lot at assembler listings
470 sane.
471
472config HEADERS_INSTALL
473 bool "Install uapi headers to usr/include"
474 depends on !UML
475 help
476 This option will install uapi headers (headers exported to user-space)
477 into the usr/include directory for use during the kernel build.
478 This is unneeded for building the kernel itself, but needed for some
479 user-space program samples. It is also needed by some features such
480 as uapi header sanity checks.
481
482config DEBUG_SECTION_MISMATCH
483 bool "Enable full Section mismatch analysis"
484 depends on CC_IS_GCC
485 help
486 The section mismatch analysis checks if there are illegal
487 references from one section to another section.
488 During linktime or runtime, some sections are dropped;
489 any use of code/data previously in these sections would
490 most likely result in an oops.
491 In the code, functions and variables are annotated with
492 __init,, etc. (see the full list in include/linux/init.h),
493 which results in the code/data being placed in specific sections.
494 The section mismatch analysis is always performed after a full
495 kernel build, and enabling this option causes the following
496 additional step to occur:
497 - Add the option -fno-inline-functions-called-once to gcc commands.
498 When inlining a function annotated with __init in a non-init
499 function, we would lose the section information and thus
500 the analysis would not catch the illegal reference.
501 This option tells gcc to inline less (but it does result in
502 a larger kernel).
503
504config SECTION_MISMATCH_WARN_ONLY
505 bool "Make section mismatch errors non-fatal"
506 default y
507 help
508 If you say N here, the build process will fail if there are any
509 section mismatch, instead of just throwing warnings.
510
511 If unsure, say Y.
512
513config DEBUG_FORCE_FUNCTION_ALIGN_64B
514 bool "Force all function address 64B aligned"
515 depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC || RISCV || S390)
516 select FUNCTION_ALIGNMENT_64B
517 help
518 There are cases that a commit from one domain changes the function
519 address alignment of other domains, and cause magic performance
520 bump (regression or improvement). Enable this option will help to
521 verify if the bump is caused by function alignment changes, while
522 it will slightly increase the kernel size and affect icache usage.
523
524 It is mainly for debug and performance tuning use.
525
526#
527# Select this config option from the architecture Kconfig, if it
528# is preferred to always offer frame pointers as a config
529# option on the architecture (regardless of KERNEL_DEBUG):
530#
531config ARCH_WANT_FRAME_POINTERS
532 bool
533
534config FRAME_POINTER
535 bool "Compile the kernel with frame pointers"
536 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
537 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
538 help
539 If you say Y here the resulting kernel image will be slightly
540 larger and slower, but it gives very useful debugging information
541 in case of kernel bugs. (precise oopses/stacktraces/warnings)
542
543config OBJTOOL
544 bool
545
546config STACK_VALIDATION
547 bool "Compile-time stack metadata validation"
548 depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER
549 select OBJTOOL
550 default n
551 help
552 Validate frame pointer rules at compile-time. This helps ensure that
553 runtime stack traces are more reliable.
554
555 For more information, see
556 tools/objtool/Documentation/objtool.txt.
557
558config NOINSTR_VALIDATION
559 bool
560 depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY
561 select OBJTOOL
562 default y
563
564config VMLINUX_MAP
565 bool "Generate vmlinux.map file when linking"
566 depends on EXPERT
567 help
568 Selecting this option will pass "-Map=vmlinux.map" to ld
569 when linking vmlinux. That file can be useful for verifying
570 and debugging magic section games, and for seeing which
571 pieces of code get eliminated with
572 CONFIG_LD_DEAD_CODE_DATA_ELIMINATION.
573
574config DEBUG_FORCE_WEAK_PER_CPU
575 bool "Force weak per-cpu definitions"
576 depends on DEBUG_KERNEL
577 help
578 s390 and alpha require percpu variables in modules to be
579 defined weak to work around addressing range issue which
580 puts the following two restrictions on percpu variable
581 definitions.
582
583 1. percpu symbols must be unique whether static or not
584 2. percpu variables can't be defined inside a function
585
586 To ensure that generic code follows the above rules, this
587 option forces all percpu variables to be defined as weak.
588
589endmenu # "Compiler options"
590
591menu "Generic Kernel Debugging Instruments"
592
593config MAGIC_SYSRQ
594 bool "Magic SysRq key"
595 depends on !UML
596 help
597 If you say Y here, you will have some control over the system even
598 if the system crashes for example during kernel debugging (e.g., you
599 will be able to flush the buffer cache to disk, reboot the system
600 immediately or dump some status information). This is accomplished
601 by pressing various keys while holding SysRq (Alt+PrintScreen). It
602 also works on a serial console (on PC hardware at least), if you
603 send a BREAK and then within 5 seconds a command keypress. The
604 keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
605 Don't say Y unless you really know what this hack does.
606
607config MAGIC_SYSRQ_DEFAULT_ENABLE
608 hex "Enable magic SysRq key functions by default"
609 depends on MAGIC_SYSRQ
610 default 0x1
611 help
612 Specifies which SysRq key functions are enabled by default.
613 This may be set to 1 or 0 to enable or disable them all, or
614 to a bitmask as described in Documentation/admin-guide/sysrq.rst.
615
616config MAGIC_SYSRQ_SERIAL
617 bool "Enable magic SysRq key over serial"
618 depends on MAGIC_SYSRQ
619 default y
620 help
621 Many embedded boards have a disconnected TTL level serial which can
622 generate some garbage that can lead to spurious false sysrq detects.
623 This option allows you to decide whether you want to enable the
624 magic SysRq key.
625
626config MAGIC_SYSRQ_SERIAL_SEQUENCE
627 string "Char sequence that enables magic SysRq over serial"
628 depends on MAGIC_SYSRQ_SERIAL
629 default ""
630 help
631 Specifies a sequence of characters that can follow BREAK to enable
632 SysRq on a serial console.
633
634 If unsure, leave an empty string and the option will not be enabled.
635
636config DEBUG_FS
637 bool "Debug Filesystem"
638 help
639 debugfs is a virtual file system that kernel developers use to put
640 debugging files into. Enable this option to be able to read and
641 write to these files.
642
643 For detailed documentation on the debugfs API, see
644 Documentation/filesystems/.
645
646 If unsure, say N.
647
648choice
649 prompt "Debugfs default access"
650 depends on DEBUG_FS
651 default DEBUG_FS_ALLOW_ALL
652 help
653 This selects the default access restrictions for debugfs.
654 It can be overridden with kernel command line option
655 debugfs=[on,no-mount,off]. The restrictions apply for API access
656 and filesystem registration.
657
658config DEBUG_FS_ALLOW_ALL
659 bool "Access normal"
660 help
661 No restrictions apply. Both API and filesystem registration
662 is on. This is the normal default operation.
663
664config DEBUG_FS_DISALLOW_MOUNT
665 bool "Do not register debugfs as filesystem"
666 help
667 The API is open but filesystem is not loaded. Clients can still do
668 their work and read with debug tools that do not need
669 debugfs filesystem.
670
671config DEBUG_FS_ALLOW_NONE
672 bool "No access"
673 help
674 Access is off. Clients get -PERM when trying to create nodes in
675 debugfs tree and debugfs is not registered as a filesystem.
676 Client can then back-off or continue without debugfs access.
677
678endchoice
679
680source "lib/Kconfig.kgdb"
681source "lib/Kconfig.ubsan"
682source "lib/Kconfig.kcsan"
683
684endmenu
685
686menu "Networking Debugging"
687
688source "net/Kconfig.debug"
689
690endmenu # "Networking Debugging"
691
692menu "Memory Debugging"
693
694source "mm/Kconfig.debug"
695
696config DEBUG_OBJECTS
697 bool "Debug object operations"
698 depends on DEBUG_KERNEL
699 help
700 If you say Y here, additional code will be inserted into the
701 kernel to track the life time of various objects and validate
702 the operations on those objects.
703
704config DEBUG_OBJECTS_SELFTEST
705 bool "Debug objects selftest"
706 depends on DEBUG_OBJECTS
707 help
708 This enables the selftest of the object debug code.
709
710config DEBUG_OBJECTS_FREE
711 bool "Debug objects in freed memory"
712 depends on DEBUG_OBJECTS
713 help
714 This enables checks whether a k/v free operation frees an area
715 which contains an object which has not been deactivated
716 properly. This can make kmalloc/kfree-intensive workloads
717 much slower.
718
719config DEBUG_OBJECTS_TIMERS
720 bool "Debug timer objects"
721 depends on DEBUG_OBJECTS
722 help
723 If you say Y here, additional code will be inserted into the
724 timer routines to track the life time of timer objects and
725 validate the timer operations.
726
727config DEBUG_OBJECTS_WORK
728 bool "Debug work objects"
729 depends on DEBUG_OBJECTS
730 help
731 If you say Y here, additional code will be inserted into the
732 work queue routines to track the life time of work objects and
733 validate the work operations.
734
735config DEBUG_OBJECTS_RCU_HEAD
736 bool "Debug RCU callbacks objects"
737 depends on DEBUG_OBJECTS
738 help
739 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
740
741config DEBUG_OBJECTS_PERCPU_COUNTER
742 bool "Debug percpu counter objects"
743 depends on DEBUG_OBJECTS
744 help
745 If you say Y here, additional code will be inserted into the
746 percpu counter routines to track the life time of percpu counter
747 objects and validate the percpu counter operations.
748
749config DEBUG_OBJECTS_ENABLE_DEFAULT
750 int "debug_objects bootup default value (0-1)"
751 range 0 1
752 default "1"
753 depends on DEBUG_OBJECTS
754 help
755 Debug objects boot parameter default value
756
757config SHRINKER_DEBUG
758 bool "Enable shrinker debugging support"
759 depends on DEBUG_FS
760 help
761 Say Y to enable the shrinker debugfs interface which provides
762 visibility into the kernel memory shrinkers subsystem.
763 Disable it to avoid an extra memory footprint.
764
765config DEBUG_STACK_USAGE
766 bool "Stack utilization instrumentation"
767 depends on DEBUG_KERNEL
768 help
769 Enables the display of the minimum amount of free stack which each
770 task has ever had available in the sysrq-T and sysrq-P debug output.
771 Also emits a message to dmesg when a process exits if that process
772 used more stack space than previously exiting processes.
773
774 This option will slow down process creation somewhat.
775
776config SCHED_STACK_END_CHECK
777 bool "Detect stack corruption on calls to schedule()"
778 depends on DEBUG_KERNEL
779 default n
780 help
781 This option checks for a stack overrun on calls to schedule().
782 If the stack end location is found to be over written always panic as
783 the content of the corrupted region can no longer be trusted.
784 This is to ensure no erroneous behaviour occurs which could result in
785 data corruption or a sporadic crash at a later stage once the region
786 is examined. The runtime overhead introduced is minimal.
787
788config ARCH_HAS_DEBUG_VM_PGTABLE
789 bool
790 help
791 An architecture should select this when it can successfully
792 build and run DEBUG_VM_PGTABLE.
793
794config DEBUG_VM_IRQSOFF
795 def_bool DEBUG_VM && !PREEMPT_RT
796
797config DEBUG_VM
798 bool "Debug VM"
799 depends on DEBUG_KERNEL
800 help
801 Enable this to turn on extended checks in the virtual-memory system
802 that may impact performance.
803
804 If unsure, say N.
805
806config DEBUG_VM_SHOOT_LAZIES
807 bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation"
808 depends on DEBUG_VM
809 depends on MMU_LAZY_TLB_SHOOTDOWN
810 help
811 Enable additional IPIs that ensure lazy tlb mm references are removed
812 before the mm is freed.
813
814 If unsure, say N.
815
816config DEBUG_VM_MAPLE_TREE
817 bool "Debug VM maple trees"
818 depends on DEBUG_VM
819 select DEBUG_MAPLE_TREE
820 help
821 Enable VM maple tree debugging information and extra validations.
822
823 If unsure, say N.
824
825config DEBUG_VM_RB
826 bool "Debug VM red-black trees"
827 depends on DEBUG_VM
828 help
829 Enable VM red-black tree debugging information and extra validations.
830
831 If unsure, say N.
832
833config DEBUG_VM_PGFLAGS
834 bool "Debug page-flags operations"
835 depends on DEBUG_VM
836 help
837 Enables extra validation on page flags operations.
838
839 If unsure, say N.
840
841config DEBUG_VM_PGTABLE
842 bool "Debug arch page table for semantics compliance"
843 depends on MMU
844 depends on ARCH_HAS_DEBUG_VM_PGTABLE
845 default y if DEBUG_VM
846 help
847 This option provides a debug method which can be used to test
848 architecture page table helper functions on various platforms in
849 verifying if they comply with expected generic MM semantics. This
850 will help architecture code in making sure that any changes or
851 new additions of these helpers still conform to expected
852 semantics of the generic MM. Platforms will have to opt in for
853 this through ARCH_HAS_DEBUG_VM_PGTABLE.
854
855 If unsure, say N.
856
857config ARCH_HAS_DEBUG_VIRTUAL
858 bool
859
860config DEBUG_VIRTUAL
861 bool "Debug VM translations"
862 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
863 help
864 Enable some costly sanity checks in virtual to page code. This can
865 catch mistakes with virt_to_page() and friends.
866
867 If unsure, say N.
868
869config DEBUG_NOMMU_REGIONS
870 bool "Debug the global anon/private NOMMU mapping region tree"
871 depends on DEBUG_KERNEL && !MMU
872 help
873 This option causes the global tree of anonymous and private mapping
874 regions to be regularly checked for invalid topology.
875
876config DEBUG_MEMORY_INIT
877 bool "Debug memory initialisation" if EXPERT
878 default !EXPERT
879 help
880 Enable this for additional checks during memory initialisation.
881 The sanity checks verify aspects of the VM such as the memory model
882 and other information provided by the architecture. Verbose
883 information will be printed at KERN_DEBUG loglevel depending
884 on the mminit_loglevel= command-line option.
885
886 If unsure, say Y
887
888config MEMORY_NOTIFIER_ERROR_INJECT
889 tristate "Memory hotplug notifier error injection module"
890 depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION
891 help
892 This option provides the ability to inject artificial errors to
893 memory hotplug notifier chain callbacks. It is controlled through
894 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
895
896 If the notifier call chain should be failed with some events
897 notified, write the error code to "actions/<notifier event>/error".
898
899 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
900
901 # cd /sys/kernel/debug/notifier-error-inject/memory
902 # echo -12 > actions/MEM_GOING_OFFLINE/error
903 # echo offline > /sys/devices/system/memory/memoryXXX/state
904 bash: echo: write error: Cannot allocate memory
905
906 To compile this code as a module, choose M here: the module will
907 be called memory-notifier-error-inject.
908
909 If unsure, say N.
910
911config DEBUG_PER_CPU_MAPS
912 bool "Debug access to per_cpu maps"
913 depends on DEBUG_KERNEL
914 depends on SMP
915 help
916 Say Y to verify that the per_cpu map being accessed has
917 been set up. This adds a fair amount of code to kernel memory
918 and decreases performance.
919
920 Say N if unsure.
921
922config DEBUG_KMAP_LOCAL
923 bool "Debug kmap_local temporary mappings"
924 depends on DEBUG_KERNEL && KMAP_LOCAL
925 help
926 This option enables additional error checking for the kmap_local
927 infrastructure. Disable for production use.
928
929config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
930 bool
931
932config DEBUG_KMAP_LOCAL_FORCE_MAP
933 bool "Enforce kmap_local temporary mappings"
934 depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
935 select KMAP_LOCAL
936 select DEBUG_KMAP_LOCAL
937 help
938 This option enforces temporary mappings through the kmap_local
939 mechanism for non-highmem pages and on non-highmem systems.
940 Disable this for production systems!
941
942config DEBUG_HIGHMEM
943 bool "Highmem debugging"
944 depends on DEBUG_KERNEL && HIGHMEM
945 select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
946 select DEBUG_KMAP_LOCAL
947 help
948 This option enables additional error checking for high memory
949 systems. Disable for production systems.
950
951config HAVE_DEBUG_STACKOVERFLOW
952 bool
953
954config DEBUG_STACKOVERFLOW
955 bool "Check for stack overflows"
956 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
957 help
958 Say Y here if you want to check for overflows of kernel, IRQ
959 and exception stacks (if your architecture uses them). This
960 option will show detailed messages if free stack space drops
961 below a certain limit.
962
963 These kinds of bugs usually occur when call-chains in the
964 kernel get too deep, especially when interrupts are
965 involved.
966
967 Use this in cases where you see apparently random memory
968 corruption, especially if it appears in 'struct thread_info'
969
970 If in doubt, say "N".
971
972config CODE_TAGGING
973 bool
974 select KALLSYMS
975
976config MEM_ALLOC_PROFILING
977 bool "Enable memory allocation profiling"
978 default n
979 depends on PROC_FS
980 depends on !DEBUG_FORCE_WEAK_PER_CPU
981 select CODE_TAGGING
982 select PAGE_EXTENSION
983 select SLAB_OBJ_EXT
984 help
985 Track allocation source code and record total allocation size
986 initiated at that code location. The mechanism can be used to track
987 memory leaks with a low performance and memory impact.
988
989config MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT
990 bool "Enable memory allocation profiling by default"
991 default y
992 depends on MEM_ALLOC_PROFILING
993
994config MEM_ALLOC_PROFILING_DEBUG
995 bool "Memory allocation profiler debugging"
996 default n
997 depends on MEM_ALLOC_PROFILING
998 select MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT
999 help
1000 Adds warnings with helpful error messages for memory allocation
1001 profiling.
1002
1003source "lib/Kconfig.kasan"
1004source "lib/Kconfig.kfence"
1005source "lib/Kconfig.kmsan"
1006
1007endmenu # "Memory Debugging"
1008
1009config DEBUG_SHIRQ
1010 bool "Debug shared IRQ handlers"
1011 depends on DEBUG_KERNEL
1012 help
1013 Enable this to generate a spurious interrupt just before a shared
1014 interrupt handler is deregistered (generating one when registering
1015 is currently disabled). Drivers need to handle this correctly. Some
1016 don't and need to be caught.
1017
1018menu "Debug Oops, Lockups and Hangs"
1019
1020config PANIC_ON_OOPS
1021 bool "Panic on Oops"
1022 help
1023 Say Y here to enable the kernel to panic when it oopses. This
1024 has the same effect as setting oops=panic on the kernel command
1025 line.
1026
1027 This feature is useful to ensure that the kernel does not do
1028 anything erroneous after an oops which could result in data
1029 corruption or other issues.
1030
1031 Say N if unsure.
1032
1033config PANIC_ON_OOPS_VALUE
1034 int
1035 range 0 1
1036 default 0 if !PANIC_ON_OOPS
1037 default 1 if PANIC_ON_OOPS
1038
1039config PANIC_TIMEOUT
1040 int "panic timeout"
1041 default 0
1042 help
1043 Set the timeout value (in seconds) until a reboot occurs when
1044 the kernel panics. If n = 0, then we wait forever. A timeout
1045 value n > 0 will wait n seconds before rebooting, while a timeout
1046 value n < 0 will reboot immediately.
1047
1048config LOCKUP_DETECTOR
1049 bool
1050
1051config SOFTLOCKUP_DETECTOR
1052 bool "Detect Soft Lockups"
1053 depends on DEBUG_KERNEL && !S390
1054 select LOCKUP_DETECTOR
1055 help
1056 Say Y here to enable the kernel to act as a watchdog to detect
1057 soft lockups.
1058
1059 Softlockups are bugs that cause the kernel to loop in kernel
1060 mode for more than 20 seconds, without giving other tasks a
1061 chance to run. The current stack trace is displayed upon
1062 detection and the system will stay locked up.
1063
1064config SOFTLOCKUP_DETECTOR_INTR_STORM
1065 bool "Detect Interrupt Storm in Soft Lockups"
1066 depends on SOFTLOCKUP_DETECTOR && IRQ_TIME_ACCOUNTING
1067 select GENERIC_IRQ_STAT_SNAPSHOT
1068 default y if NR_CPUS <= 128
1069 help
1070 Say Y here to enable the kernel to detect interrupt storm
1071 during "soft lockups".
1072
1073 "soft lockups" can be caused by a variety of reasons. If one is
1074 caused by an interrupt storm, then the storming interrupts will not
1075 be on the callstack. To detect this case, it is necessary to report
1076 the CPU stats and the interrupt counts during the "soft lockups".
1077
1078config BOOTPARAM_SOFTLOCKUP_PANIC
1079 bool "Panic (Reboot) On Soft Lockups"
1080 depends on SOFTLOCKUP_DETECTOR
1081 help
1082 Say Y here to enable the kernel to panic on "soft lockups",
1083 which are bugs that cause the kernel to loop in kernel
1084 mode for more than 20 seconds (configurable using the watchdog_thresh
1085 sysctl), without giving other tasks a chance to run.
1086
1087 The panic can be used in combination with panic_timeout,
1088 to cause the system to reboot automatically after a
1089 lockup has been detected. This feature is useful for
1090 high-availability systems that have uptime guarantees and
1091 where a lockup must be resolved ASAP.
1092
1093 Say N if unsure.
1094
1095config HAVE_HARDLOCKUP_DETECTOR_BUDDY
1096 bool
1097 depends on SMP
1098 default y
1099
1100#
1101# Global switch whether to build a hardlockup detector at all. It is available
1102# only when the architecture supports at least one implementation. There are
1103# two exceptions. The hardlockup detector is never enabled on:
1104#
1105# s390: it reported many false positives there
1106#
1107# sparc64: has a custom implementation which is not using the common
1108# hardlockup command line options and sysctl interface.
1109#
1110config HARDLOCKUP_DETECTOR
1111 bool "Detect Hard Lockups"
1112 depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64
1113 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH
1114 imply HARDLOCKUP_DETECTOR_PERF
1115 imply HARDLOCKUP_DETECTOR_BUDDY
1116 imply HARDLOCKUP_DETECTOR_ARCH
1117 select LOCKUP_DETECTOR
1118
1119 help
1120 Say Y here to enable the kernel to act as a watchdog to detect
1121 hard lockups.
1122
1123 Hardlockups are bugs that cause the CPU to loop in kernel mode
1124 for more than 10 seconds, without letting other interrupts have a
1125 chance to run. The current stack trace is displayed upon detection
1126 and the system will stay locked up.
1127
1128#
1129# Note that arch-specific variants are always preferred.
1130#
1131config HARDLOCKUP_DETECTOR_PREFER_BUDDY
1132 bool "Prefer the buddy CPU hardlockup detector"
1133 depends on HARDLOCKUP_DETECTOR
1134 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY
1135 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1136 help
1137 Say Y here to prefer the buddy hardlockup detector over the perf one.
1138
1139 With the buddy detector, each CPU uses its softlockup hrtimer
1140 to check that the next CPU is processing hrtimer interrupts by
1141 verifying that a counter is increasing.
1142
1143 This hardlockup detector is useful on systems that don't have
1144 an arch-specific hardlockup detector or if resources needed
1145 for the hardlockup detector are better used for other things.
1146
1147config HARDLOCKUP_DETECTOR_PERF
1148 bool
1149 depends on HARDLOCKUP_DETECTOR
1150 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY
1151 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1152 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1153
1154config HARDLOCKUP_DETECTOR_BUDDY
1155 bool
1156 depends on HARDLOCKUP_DETECTOR
1157 depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY
1158 depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY
1159 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1160 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1161
1162config HARDLOCKUP_DETECTOR_ARCH
1163 bool
1164 depends on HARDLOCKUP_DETECTOR
1165 depends on HAVE_HARDLOCKUP_DETECTOR_ARCH
1166 help
1167 The arch-specific implementation of the hardlockup detector will
1168 be used.
1169
1170#
1171# Both the "perf" and "buddy" hardlockup detectors count hrtimer
1172# interrupts. This config enables functions managing this common code.
1173#
1174config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1175 bool
1176 select SOFTLOCKUP_DETECTOR
1177
1178#
1179# Enables a timestamp based low pass filter to compensate for perf based
1180# hard lockup detection which runs too fast due to turbo modes.
1181#
1182config HARDLOCKUP_CHECK_TIMESTAMP
1183 bool
1184
1185config BOOTPARAM_HARDLOCKUP_PANIC
1186 bool "Panic (Reboot) On Hard Lockups"
1187 depends on HARDLOCKUP_DETECTOR
1188 help
1189 Say Y here to enable the kernel to panic on "hard lockups",
1190 which are bugs that cause the kernel to loop in kernel
1191 mode with interrupts disabled for more than 10 seconds (configurable
1192 using the watchdog_thresh sysctl).
1193
1194 Say N if unsure.
1195
1196config DETECT_HUNG_TASK
1197 bool "Detect Hung Tasks"
1198 depends on DEBUG_KERNEL
1199 default SOFTLOCKUP_DETECTOR
1200 help
1201 Say Y here to enable the kernel to detect "hung tasks",
1202 which are bugs that cause the task to be stuck in
1203 uninterruptible "D" state indefinitely.
1204
1205 When a hung task is detected, the kernel will print the
1206 current stack trace (which you should report), but the
1207 task will stay in uninterruptible state. If lockdep is
1208 enabled then all held locks will also be reported. This
1209 feature has negligible overhead.
1210
1211config DEFAULT_HUNG_TASK_TIMEOUT
1212 int "Default timeout for hung task detection (in seconds)"
1213 depends on DETECT_HUNG_TASK
1214 default 120
1215 help
1216 This option controls the default timeout (in seconds) used
1217 to determine when a task has become non-responsive and should
1218 be considered hung.
1219
1220 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
1221 sysctl or by writing a value to
1222 /proc/sys/kernel/hung_task_timeout_secs.
1223
1224 A timeout of 0 disables the check. The default is two minutes.
1225 Keeping the default should be fine in most cases.
1226
1227config BOOTPARAM_HUNG_TASK_PANIC
1228 bool "Panic (Reboot) On Hung Tasks"
1229 depends on DETECT_HUNG_TASK
1230 help
1231 Say Y here to enable the kernel to panic on "hung tasks",
1232 which are bugs that cause the kernel to leave a task stuck
1233 in uninterruptible "D" state.
1234
1235 The panic can be used in combination with panic_timeout,
1236 to cause the system to reboot automatically after a
1237 hung task has been detected. This feature is useful for
1238 high-availability systems that have uptime guarantees and
1239 where a hung tasks must be resolved ASAP.
1240
1241 Say N if unsure.
1242
1243config WQ_WATCHDOG
1244 bool "Detect Workqueue Stalls"
1245 depends on DEBUG_KERNEL
1246 help
1247 Say Y here to enable stall detection on workqueues. If a
1248 worker pool doesn't make forward progress on a pending work
1249 item for over a given amount of time, 30s by default, a
1250 warning message is printed along with dump of workqueue
1251 state. This can be configured through kernel parameter
1252 "workqueue.watchdog_thresh" and its sysfs counterpart.
1253
1254config WQ_CPU_INTENSIVE_REPORT
1255 bool "Report per-cpu work items which hog CPU for too long"
1256 depends on DEBUG_KERNEL
1257 help
1258 Say Y here to enable reporting of concurrency-managed per-cpu work
1259 items that hog CPUs for longer than
1260 workqueue.cpu_intensive_thresh_us. Workqueue automatically
1261 detects and excludes them from concurrency management to prevent
1262 them from stalling other per-cpu work items. Occassional
1263 triggering may not necessarily indicate a problem. Repeated
1264 triggering likely indicates that the work item should be switched
1265 to use an unbound workqueue.
1266
1267config TEST_LOCKUP
1268 tristate "Test module to generate lockups"
1269 depends on m
1270 help
1271 This builds the "test_lockup" module that helps to make sure
1272 that watchdogs and lockup detectors are working properly.
1273
1274 Depending on module parameters it could emulate soft or hard
1275 lockup, "hung task", or locking arbitrary lock for a long time.
1276 Also it could generate series of lockups with cooling-down periods.
1277
1278 If unsure, say N.
1279
1280endmenu # "Debug lockups and hangs"
1281
1282menu "Scheduler Debugging"
1283
1284config SCHED_DEBUG
1285 bool "Collect scheduler debugging info"
1286 depends on DEBUG_KERNEL && DEBUG_FS
1287 default y
1288 help
1289 If you say Y here, the /sys/kernel/debug/sched file will be provided
1290 that can help debug the scheduler. The runtime overhead of this
1291 option is minimal.
1292
1293config SCHED_INFO
1294 bool
1295 default n
1296
1297config SCHEDSTATS
1298 bool "Collect scheduler statistics"
1299 depends on PROC_FS
1300 select SCHED_INFO
1301 help
1302 If you say Y here, additional code will be inserted into the
1303 scheduler and related routines to collect statistics about
1304 scheduler behavior and provide them in /proc/schedstat. These
1305 stats may be useful for both tuning and debugging the scheduler
1306 If you aren't debugging the scheduler or trying to tune a specific
1307 application, you can say N to avoid the very slight overhead
1308 this adds.
1309
1310endmenu
1311
1312config DEBUG_TIMEKEEPING
1313 bool "Enable extra timekeeping sanity checking"
1314 help
1315 This option will enable additional timekeeping sanity checks
1316 which may be helpful when diagnosing issues where timekeeping
1317 problems are suspected.
1318
1319 This may include checks in the timekeeping hotpaths, so this
1320 option may have a (very small) performance impact to some
1321 workloads.
1322
1323 If unsure, say N.
1324
1325config DEBUG_PREEMPT
1326 bool "Debug preemptible kernel"
1327 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT
1328 help
1329 If you say Y here then the kernel will use a debug variant of the
1330 commonly used smp_processor_id() function and will print warnings
1331 if kernel code uses it in a preemption-unsafe way. Also, the kernel
1332 will detect preemption count underflows.
1333
1334 This option has potential to introduce high runtime overhead,
1335 depending on workload as it triggers debugging routines for each
1336 this_cpu operation. It should only be used for debugging purposes.
1337
1338menu "Lock Debugging (spinlocks, mutexes, etc...)"
1339
1340config LOCK_DEBUGGING_SUPPORT
1341 bool
1342 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1343 default y
1344
1345config PROVE_LOCKING
1346 bool "Lock debugging: prove locking correctness"
1347 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1348 select LOCKDEP
1349 select DEBUG_SPINLOCK
1350 select DEBUG_MUTEXES if !PREEMPT_RT
1351 select DEBUG_RT_MUTEXES if RT_MUTEXES
1352 select DEBUG_RWSEMS if !PREEMPT_RT
1353 select DEBUG_WW_MUTEX_SLOWPATH
1354 select DEBUG_LOCK_ALLOC
1355 select PREEMPT_COUNT if !ARCH_NO_PREEMPT
1356 select TRACE_IRQFLAGS
1357 default n
1358 help
1359 This feature enables the kernel to prove that all locking
1360 that occurs in the kernel runtime is mathematically
1361 correct: that under no circumstance could an arbitrary (and
1362 not yet triggered) combination of observed locking
1363 sequences (on an arbitrary number of CPUs, running an
1364 arbitrary number of tasks and interrupt contexts) cause a
1365 deadlock.
1366
1367 In short, this feature enables the kernel to report locking
1368 related deadlocks before they actually occur.
1369
1370 The proof does not depend on how hard and complex a
1371 deadlock scenario would be to trigger: how many
1372 participant CPUs, tasks and irq-contexts would be needed
1373 for it to trigger. The proof also does not depend on
1374 timing: if a race and a resulting deadlock is possible
1375 theoretically (no matter how unlikely the race scenario
1376 is), it will be proven so and will immediately be
1377 reported by the kernel (once the event is observed that
1378 makes the deadlock theoretically possible).
1379
1380 If a deadlock is impossible (i.e. the locking rules, as
1381 observed by the kernel, are mathematically correct), the
1382 kernel reports nothing.
1383
1384 NOTE: this feature can also be enabled for rwlocks, mutexes
1385 and rwsems - in which case all dependencies between these
1386 different locking variants are observed and mapped too, and
1387 the proof of observed correctness is also maintained for an
1388 arbitrary combination of these separate locking variants.
1389
1390 For more details, see Documentation/locking/lockdep-design.rst.
1391
1392config PROVE_RAW_LOCK_NESTING
1393 bool "Enable raw_spinlock - spinlock nesting checks"
1394 depends on PROVE_LOCKING
1395 default n
1396 help
1397 Enable the raw_spinlock vs. spinlock nesting checks which ensure
1398 that the lock nesting rules for PREEMPT_RT enabled kernels are
1399 not violated.
1400
1401 NOTE: There are known nesting problems. So if you enable this
1402 option expect lockdep splats until these problems have been fully
1403 addressed which is work in progress. This config switch allows to
1404 identify and analyze these problems. It will be removed and the
1405 check permanently enabled once the main issues have been fixed.
1406
1407 If unsure, select N.
1408
1409config LOCK_STAT
1410 bool "Lock usage statistics"
1411 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1412 select LOCKDEP
1413 select DEBUG_SPINLOCK
1414 select DEBUG_MUTEXES if !PREEMPT_RT
1415 select DEBUG_RT_MUTEXES if RT_MUTEXES
1416 select DEBUG_LOCK_ALLOC
1417 default n
1418 help
1419 This feature enables tracking lock contention points
1420
1421 For more details, see Documentation/locking/lockstat.rst
1422
1423 This also enables lock events required by "perf lock",
1424 subcommand of perf.
1425 If you want to use "perf lock", you also need to turn on
1426 CONFIG_EVENT_TRACING.
1427
1428 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1429 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1430
1431config DEBUG_RT_MUTEXES
1432 bool "RT Mutex debugging, deadlock detection"
1433 depends on DEBUG_KERNEL && RT_MUTEXES
1434 help
1435 This allows rt mutex semantics violations and rt mutex related
1436 deadlocks (lockups) to be detected and reported automatically.
1437
1438config DEBUG_SPINLOCK
1439 bool "Spinlock and rw-lock debugging: basic checks"
1440 depends on DEBUG_KERNEL
1441 select UNINLINE_SPIN_UNLOCK
1442 help
1443 Say Y here and build SMP to catch missing spinlock initialization
1444 and certain other kinds of spinlock errors commonly made. This is
1445 best used in conjunction with the NMI watchdog so that spinlock
1446 deadlocks are also debuggable.
1447
1448config DEBUG_MUTEXES
1449 bool "Mutex debugging: basic checks"
1450 depends on DEBUG_KERNEL && !PREEMPT_RT
1451 help
1452 This feature allows mutex semantics violations to be detected and
1453 reported.
1454
1455config DEBUG_WW_MUTEX_SLOWPATH
1456 bool "Wait/wound mutex debugging: Slowpath testing"
1457 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1458 select DEBUG_LOCK_ALLOC
1459 select DEBUG_SPINLOCK
1460 select DEBUG_MUTEXES if !PREEMPT_RT
1461 select DEBUG_RT_MUTEXES if PREEMPT_RT
1462 help
1463 This feature enables slowpath testing for w/w mutex users by
1464 injecting additional -EDEADLK wound/backoff cases. Together with
1465 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1466 will test all possible w/w mutex interface abuse with the
1467 exception of simply not acquiring all the required locks.
1468 Note that this feature can introduce significant overhead, so
1469 it really should not be enabled in a production or distro kernel,
1470 even a debug kernel. If you are a driver writer, enable it. If
1471 you are a distro, do not.
1472
1473config DEBUG_RWSEMS
1474 bool "RW Semaphore debugging: basic checks"
1475 depends on DEBUG_KERNEL && !PREEMPT_RT
1476 help
1477 This debugging feature allows mismatched rw semaphore locks
1478 and unlocks to be detected and reported.
1479
1480config DEBUG_LOCK_ALLOC
1481 bool "Lock debugging: detect incorrect freeing of live locks"
1482 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1483 select DEBUG_SPINLOCK
1484 select DEBUG_MUTEXES if !PREEMPT_RT
1485 select DEBUG_RT_MUTEXES if RT_MUTEXES
1486 select LOCKDEP
1487 help
1488 This feature will check whether any held lock (spinlock, rwlock,
1489 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1490 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1491 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1492 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1493 held during task exit.
1494
1495config LOCKDEP
1496 bool
1497 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1498 select STACKTRACE
1499 select KALLSYMS
1500 select KALLSYMS_ALL
1501
1502config LOCKDEP_SMALL
1503 bool
1504
1505config LOCKDEP_BITS
1506 int "Bitsize for MAX_LOCKDEP_ENTRIES"
1507 depends on LOCKDEP && !LOCKDEP_SMALL
1508 range 10 30
1509 default 15
1510 help
1511 Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message.
1512
1513config LOCKDEP_CHAINS_BITS
1514 int "Bitsize for MAX_LOCKDEP_CHAINS"
1515 depends on LOCKDEP && !LOCKDEP_SMALL
1516 range 10 30
1517 default 16
1518 help
1519 Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message.
1520
1521config LOCKDEP_STACK_TRACE_BITS
1522 int "Bitsize for MAX_STACK_TRACE_ENTRIES"
1523 depends on LOCKDEP && !LOCKDEP_SMALL
1524 range 10 30
1525 default 19
1526 help
1527 Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message.
1528
1529config LOCKDEP_STACK_TRACE_HASH_BITS
1530 int "Bitsize for STACK_TRACE_HASH_SIZE"
1531 depends on LOCKDEP && !LOCKDEP_SMALL
1532 range 10 30
1533 default 14
1534 help
1535 Try increasing this value if you need large STACK_TRACE_HASH_SIZE.
1536
1537config LOCKDEP_CIRCULAR_QUEUE_BITS
1538 int "Bitsize for elements in circular_queue struct"
1539 depends on LOCKDEP
1540 range 10 30
1541 default 12
1542 help
1543 Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure.
1544
1545config DEBUG_LOCKDEP
1546 bool "Lock dependency engine debugging"
1547 depends on DEBUG_KERNEL && LOCKDEP
1548 select DEBUG_IRQFLAGS
1549 help
1550 If you say Y here, the lock dependency engine will do
1551 additional runtime checks to debug itself, at the price
1552 of more runtime overhead.
1553
1554config DEBUG_ATOMIC_SLEEP
1555 bool "Sleep inside atomic section checking"
1556 select PREEMPT_COUNT
1557 depends on DEBUG_KERNEL
1558 depends on !ARCH_NO_PREEMPT
1559 help
1560 If you say Y here, various routines which may sleep will become very
1561 noisy if they are called inside atomic sections: when a spinlock is
1562 held, inside an rcu read side critical section, inside preempt disabled
1563 sections, inside an interrupt, etc...
1564
1565config DEBUG_LOCKING_API_SELFTESTS
1566 bool "Locking API boot-time self-tests"
1567 depends on DEBUG_KERNEL
1568 help
1569 Say Y here if you want the kernel to run a short self-test during
1570 bootup. The self-test checks whether common types of locking bugs
1571 are detected by debugging mechanisms or not. (if you disable
1572 lock debugging then those bugs won't be detected of course.)
1573 The following locking APIs are covered: spinlocks, rwlocks,
1574 mutexes and rwsems.
1575
1576config LOCK_TORTURE_TEST
1577 tristate "torture tests for locking"
1578 depends on DEBUG_KERNEL
1579 select TORTURE_TEST
1580 help
1581 This option provides a kernel module that runs torture tests
1582 on kernel locking primitives. The kernel module may be built
1583 after the fact on the running kernel to be tested, if desired.
1584
1585 Say Y here if you want kernel locking-primitive torture tests
1586 to be built into the kernel.
1587 Say M if you want these torture tests to build as a module.
1588 Say N if you are unsure.
1589
1590config WW_MUTEX_SELFTEST
1591 tristate "Wait/wound mutex selftests"
1592 help
1593 This option provides a kernel module that runs tests on the
1594 on the struct ww_mutex locking API.
1595
1596 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1597 with this test harness.
1598
1599 Say M if you want these self tests to build as a module.
1600 Say N if you are unsure.
1601
1602config SCF_TORTURE_TEST
1603 tristate "torture tests for smp_call_function*()"
1604 depends on DEBUG_KERNEL
1605 select TORTURE_TEST
1606 help
1607 This option provides a kernel module that runs torture tests
1608 on the smp_call_function() family of primitives. The kernel
1609 module may be built after the fact on the running kernel to
1610 be tested, if desired.
1611
1612config CSD_LOCK_WAIT_DEBUG
1613 bool "Debugging for csd_lock_wait(), called from smp_call_function*()"
1614 depends on DEBUG_KERNEL
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
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 FAULT_INJECTION_CONFIGFS
2099 bool "Configfs interface for fault-injection capabilities"
2100 depends on FAULT_INJECTION
2101 select CONFIGFS_FS
2102 help
2103 This option allows configfs-based drivers to dynamically configure
2104 fault-injection via configfs. Each parameter for driver-specific
2105 fault-injection can be made visible as a configfs attribute in a
2106 configfs group.
2107
2108
2109config FAULT_INJECTION_STACKTRACE_FILTER
2110 bool "stacktrace filter for fault-injection capabilities"
2111 depends on FAULT_INJECTION
2112 depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT
2113 select STACKTRACE
2114 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
2115 help
2116 Provide stacktrace filter for fault-injection capabilities
2117
2118config ARCH_HAS_KCOV
2119 bool
2120 help
2121 An architecture should select this when it can successfully
2122 build and run with CONFIG_KCOV. This typically requires
2123 disabling instrumentation for some early boot code.
2124
2125config CC_HAS_SANCOV_TRACE_PC
2126 def_bool $(cc-option,-fsanitize-coverage=trace-pc)
2127
2128
2129config KCOV
2130 bool "Code coverage for fuzzing"
2131 depends on ARCH_HAS_KCOV
2132 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
2133 depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \
2134 GCC_VERSION >= 120000 || CC_IS_CLANG
2135 select DEBUG_FS
2136 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
2137 select OBJTOOL if HAVE_NOINSTR_HACK
2138 help
2139 KCOV exposes kernel code coverage information in a form suitable
2140 for coverage-guided fuzzing (randomized testing).
2141
2142 For more details, see Documentation/dev-tools/kcov.rst.
2143
2144config KCOV_ENABLE_COMPARISONS
2145 bool "Enable comparison operands collection by KCOV"
2146 depends on KCOV
2147 depends on $(cc-option,-fsanitize-coverage=trace-cmp)
2148 help
2149 KCOV also exposes operands of every comparison in the instrumented
2150 code along with operand sizes and PCs of the comparison instructions.
2151 These operands can be used by fuzzing engines to improve the quality
2152 of fuzzing coverage.
2153
2154config KCOV_INSTRUMENT_ALL
2155 bool "Instrument all code by default"
2156 depends on KCOV
2157 default y
2158 help
2159 If you are doing generic system call fuzzing (like e.g. syzkaller),
2160 then you will want to instrument the whole kernel and you should
2161 say y here. If you are doing more targeted fuzzing (like e.g.
2162 filesystem fuzzing with AFL) then you will want to enable coverage
2163 for more specific subsets of files, and should say n here.
2164
2165config KCOV_IRQ_AREA_SIZE
2166 hex "Size of interrupt coverage collection area in words"
2167 depends on KCOV
2168 default 0x40000
2169 help
2170 KCOV uses preallocated per-cpu areas to collect coverage from
2171 soft interrupts. This specifies the size of those areas in the
2172 number of unsigned long words.
2173
2174menuconfig RUNTIME_TESTING_MENU
2175 bool "Runtime Testing"
2176 default y
2177
2178if RUNTIME_TESTING_MENU
2179
2180config TEST_DHRY
2181 tristate "Dhrystone benchmark test"
2182 help
2183 Enable this to include the Dhrystone 2.1 benchmark. This test
2184 calculates the number of Dhrystones per second, and the number of
2185 DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided
2186 by 1757 (the number of Dhrystones per second obtained on the VAX
2187 11/780, nominally a 1 MIPS machine).
2188
2189 To run the benchmark, it needs to be enabled explicitly, either from
2190 the kernel command line (when built-in), or from userspace (when
2191 built-in or modular).
2192
2193 Run once during kernel boot:
2194
2195 test_dhry.run
2196
2197 Set number of iterations from kernel command line:
2198
2199 test_dhry.iterations=<n>
2200
2201 Set number of iterations from userspace:
2202
2203 echo <n> > /sys/module/test_dhry/parameters/iterations
2204
2205 Trigger manual run from userspace:
2206
2207 echo y > /sys/module/test_dhry/parameters/run
2208
2209 If the number of iterations is <= 0, the test will devise a suitable
2210 number of iterations (test runs for at least 2s) automatically.
2211 This process takes ca. 4s.
2212
2213 If unsure, say N.
2214
2215config LKDTM
2216 tristate "Linux Kernel Dump Test Tool Module"
2217 depends on DEBUG_FS
2218 help
2219 This module enables testing of the different dumping mechanisms by
2220 inducing system failures at predefined crash points.
2221 If you don't need it: say N
2222 Choose M here to compile this code as a module. The module will be
2223 called lkdtm.
2224
2225 Documentation on how to use the module can be found in
2226 Documentation/fault-injection/provoke-crashes.rst
2227
2228config CPUMASK_KUNIT_TEST
2229 tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS
2230 depends on KUNIT
2231 default KUNIT_ALL_TESTS
2232 help
2233 Enable to turn on cpumask tests, running at boot or module load time.
2234
2235 For more information on KUnit and unit tests in general, please refer
2236 to the KUnit documentation in Documentation/dev-tools/kunit/.
2237
2238 If unsure, say N.
2239
2240config TEST_LIST_SORT
2241 tristate "Linked list sorting test" if !KUNIT_ALL_TESTS
2242 depends on KUNIT
2243 default KUNIT_ALL_TESTS
2244 help
2245 Enable this to turn on 'list_sort()' function test. This test is
2246 executed only once during system boot (so affects only boot time),
2247 or at module load time.
2248
2249 If unsure, say N.
2250
2251config TEST_MIN_HEAP
2252 tristate "Min heap test"
2253 depends on DEBUG_KERNEL || m
2254 help
2255 Enable this to turn on min heap function tests. This test is
2256 executed only once during system boot (so affects only boot time),
2257 or at module load time.
2258
2259 If unsure, say N.
2260
2261config TEST_SORT
2262 tristate "Array-based sort test" if !KUNIT_ALL_TESTS
2263 depends on KUNIT
2264 default KUNIT_ALL_TESTS
2265 help
2266 This option enables the self-test function of 'sort()' at boot,
2267 or at module load time.
2268
2269 If unsure, say N.
2270
2271config TEST_DIV64
2272 tristate "64bit/32bit division and modulo test"
2273 depends on DEBUG_KERNEL || m
2274 help
2275 Enable this to turn on 'do_div()' function test. This test is
2276 executed only once during system boot (so affects only boot time),
2277 or at module load time.
2278
2279 If unsure, say N.
2280
2281config TEST_IOV_ITER
2282 tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS
2283 depends on KUNIT
2284 depends on MMU
2285 default KUNIT_ALL_TESTS
2286 help
2287 Enable this to turn on testing of the operation of the I/O iterator
2288 (iov_iter). This test is executed only once during system boot (so
2289 affects only boot time), or at module load time.
2290
2291 If unsure, say N.
2292
2293config KPROBES_SANITY_TEST
2294 tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS
2295 depends on DEBUG_KERNEL
2296 depends on KPROBES
2297 depends on KUNIT
2298 select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
2299 default KUNIT_ALL_TESTS
2300 help
2301 This option provides for testing basic kprobes functionality on
2302 boot. Samples of kprobe and kretprobe are inserted and
2303 verified for functionality.
2304
2305 Say N if you are unsure.
2306
2307config FPROBE_SANITY_TEST
2308 bool "Self test for fprobe"
2309 depends on DEBUG_KERNEL
2310 depends on FPROBE
2311 depends on KUNIT=y
2312 help
2313 This option will enable testing the fprobe when the system boot.
2314 A series of tests are made to verify that the fprobe is functioning
2315 properly.
2316
2317 Say N if you are unsure.
2318
2319config BACKTRACE_SELF_TEST
2320 tristate "Self test for the backtrace code"
2321 depends on DEBUG_KERNEL
2322 help
2323 This option provides a kernel module that can be used to test
2324 the kernel stack backtrace code. This option is not useful
2325 for distributions or general kernels, but only for kernel
2326 developers working on architecture code.
2327
2328 Note that if you want to also test saved backtraces, you will
2329 have to enable STACKTRACE as well.
2330
2331 Say N if you are unsure.
2332
2333config TEST_REF_TRACKER
2334 tristate "Self test for reference tracker"
2335 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
2336 select REF_TRACKER
2337 help
2338 This option provides a kernel module performing tests
2339 using reference tracker infrastructure.
2340
2341 Say N if you are unsure.
2342
2343config RBTREE_TEST
2344 tristate "Red-Black tree test"
2345 depends on DEBUG_KERNEL
2346 help
2347 A benchmark measuring the performance of the rbtree library.
2348 Also includes rbtree invariant checks.
2349
2350config REED_SOLOMON_TEST
2351 tristate "Reed-Solomon library test"
2352 depends on DEBUG_KERNEL || m
2353 select REED_SOLOMON
2354 select REED_SOLOMON_ENC16
2355 select REED_SOLOMON_DEC16
2356 help
2357 This option enables the self-test function of rslib at boot,
2358 or at module load time.
2359
2360 If unsure, say N.
2361
2362config INTERVAL_TREE_TEST
2363 tristate "Interval tree test"
2364 depends on DEBUG_KERNEL
2365 select INTERVAL_TREE
2366 help
2367 A benchmark measuring the performance of the interval tree library
2368
2369config PERCPU_TEST
2370 tristate "Per cpu operations test"
2371 depends on m && DEBUG_KERNEL
2372 help
2373 Enable this option to build test module which validates per-cpu
2374 operations.
2375
2376 If unsure, say N.
2377
2378config ATOMIC64_SELFTEST
2379 tristate "Perform an atomic64_t self-test"
2380 help
2381 Enable this option to test the atomic64_t functions at boot or
2382 at module load time.
2383
2384 If unsure, say N.
2385
2386config ASYNC_RAID6_TEST
2387 tristate "Self test for hardware accelerated raid6 recovery"
2388 depends on ASYNC_RAID6_RECOV
2389 select ASYNC_MEMCPY
2390 help
2391 This is a one-shot self test that permutes through the
2392 recovery of all the possible two disk failure scenarios for a
2393 N-disk array. Recovery is performed with the asynchronous
2394 raid6 recovery routines, and will optionally use an offload
2395 engine if one is available.
2396
2397 If unsure, say N.
2398
2399config TEST_HEXDUMP
2400 tristate "Test functions located in the hexdump module at runtime"
2401
2402config STRING_KUNIT_TEST
2403 tristate "KUnit test string functions at runtime" if !KUNIT_ALL_TESTS
2404 depends on KUNIT
2405 default KUNIT_ALL_TESTS
2406
2407config STRING_HELPERS_KUNIT_TEST
2408 tristate "KUnit test string helpers at runtime" if !KUNIT_ALL_TESTS
2409 depends on KUNIT
2410 default KUNIT_ALL_TESTS
2411
2412config TEST_KSTRTOX
2413 tristate "Test kstrto*() family of functions at runtime"
2414
2415config TEST_PRINTF
2416 tristate "Test printf() family of functions at runtime"
2417
2418config TEST_SCANF
2419 tristate "Test scanf() family of functions at runtime"
2420
2421config TEST_BITMAP
2422 tristate "Test bitmap_*() family of functions at runtime"
2423 help
2424 Enable this option to test the bitmap functions at boot.
2425
2426 If unsure, say N.
2427
2428config TEST_UUID
2429 tristate "Test functions located in the uuid module at runtime"
2430
2431config TEST_XARRAY
2432 tristate "Test the XArray code at runtime"
2433
2434config TEST_MAPLE_TREE
2435 tristate "Test the Maple Tree code at runtime or module load"
2436 help
2437 Enable this option to test the maple tree code functions at boot, or
2438 when the module is loaded. Enable "Debug Maple Trees" will enable
2439 more verbose output on failures.
2440
2441 If unsure, say N.
2442
2443config TEST_RHASHTABLE
2444 tristate "Perform selftest on resizable hash table"
2445 help
2446 Enable this option to test the rhashtable functions at boot.
2447
2448 If unsure, say N.
2449
2450config TEST_IDA
2451 tristate "Perform selftest on IDA functions"
2452
2453config TEST_PARMAN
2454 tristate "Perform selftest on priority array manager"
2455 depends on PARMAN
2456 help
2457 Enable this option to test priority array manager on boot
2458 (or module load).
2459
2460 If unsure, say N.
2461
2462config TEST_IRQ_TIMINGS
2463 bool "IRQ timings selftest"
2464 depends on IRQ_TIMINGS
2465 help
2466 Enable this option to test the irq timings code on boot.
2467
2468 If unsure, say N.
2469
2470config TEST_LKM
2471 tristate "Test module loading with 'hello world' module"
2472 depends on m
2473 help
2474 This builds the "test_module" module that emits "Hello, world"
2475 on printk when loaded. It is designed to be used for basic
2476 evaluation of the module loading subsystem (for example when
2477 validating module verification). It lacks any extra dependencies,
2478 and will not normally be loaded by the system unless explicitly
2479 requested by name.
2480
2481 If unsure, say N.
2482
2483config TEST_BITOPS
2484 tristate "Test module for compilation of bitops operations"
2485 help
2486 This builds the "test_bitops" module that is much like the
2487 TEST_LKM module except that it does a basic exercise of the
2488 set/clear_bit macros and get_count_order/long to make sure there are
2489 no compiler warnings from C=1 sparse checker or -Wextra
2490 compilations. It has no dependencies and doesn't run or load unless
2491 explicitly requested by name. for example: modprobe test_bitops.
2492
2493 If unsure, say N.
2494
2495config TEST_VMALLOC
2496 tristate "Test module for stress/performance analysis of vmalloc allocator"
2497 default n
2498 depends on MMU
2499 depends on m
2500 help
2501 This builds the "test_vmalloc" module that should be used for
2502 stress and performance analysis. So, any new change for vmalloc
2503 subsystem can be evaluated from performance and stability point
2504 of view.
2505
2506 If unsure, say N.
2507
2508config TEST_USER_COPY
2509 tristate "Test user/kernel boundary protections"
2510 depends on m
2511 help
2512 This builds the "test_user_copy" module that runs sanity checks
2513 on the copy_to/from_user infrastructure, making sure basic
2514 user/kernel boundary testing is working. If it fails to load,
2515 a regression has been detected in the user/kernel memory boundary
2516 protections.
2517
2518 If unsure, say N.
2519
2520config TEST_BPF
2521 tristate "Test BPF filter functionality"
2522 depends on m && NET
2523 help
2524 This builds the "test_bpf" module that runs various test vectors
2525 against the BPF interpreter or BPF JIT compiler depending on the
2526 current setting. This is in particular useful for BPF JIT compiler
2527 development, but also to run regression tests against changes in
2528 the interpreter code. It also enables test stubs for eBPF maps and
2529 verifier used by user space verifier testsuite.
2530
2531 If unsure, say N.
2532
2533config TEST_BLACKHOLE_DEV
2534 tristate "Test blackhole netdev functionality"
2535 depends on m && NET
2536 help
2537 This builds the "test_blackhole_dev" module that validates the
2538 data path through this blackhole netdev.
2539
2540 If unsure, say N.
2541
2542config FIND_BIT_BENCHMARK
2543 tristate "Test find_bit functions"
2544 help
2545 This builds the "test_find_bit" module that measure find_*_bit()
2546 functions performance.
2547
2548 If unsure, say N.
2549
2550config TEST_FIRMWARE
2551 tristate "Test firmware loading via userspace interface"
2552 depends on FW_LOADER
2553 help
2554 This builds the "test_firmware" module that creates a userspace
2555 interface for testing firmware loading. This can be used to
2556 control the triggering of firmware loading without needing an
2557 actual firmware-using device. The contents can be rechecked by
2558 userspace.
2559
2560 If unsure, say N.
2561
2562config TEST_SYSCTL
2563 tristate "sysctl test driver"
2564 depends on PROC_SYSCTL
2565 help
2566 This builds the "test_sysctl" module. This driver enables to test the
2567 proc sysctl interfaces available to drivers safely without affecting
2568 production knobs which might alter system functionality.
2569
2570 If unsure, say N.
2571
2572config BITFIELD_KUNIT
2573 tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS
2574 depends on KUNIT
2575 default KUNIT_ALL_TESTS
2576 help
2577 Enable this option to test the bitfield functions at boot.
2578
2579 KUnit tests run during boot and output the results to the debug log
2580 in TAP format (http://testanything.org/). Only useful for kernel devs
2581 running the KUnit test harness, and not intended for inclusion into a
2582 production build.
2583
2584 For more information on KUnit and unit tests in general please refer
2585 to the KUnit documentation in Documentation/dev-tools/kunit/.
2586
2587 If unsure, say N.
2588
2589config CHECKSUM_KUNIT
2590 tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS
2591 depends on KUNIT
2592 default KUNIT_ALL_TESTS
2593 help
2594 Enable this option to test the checksum functions at boot.
2595
2596 KUnit tests run during boot and output the results to the debug log
2597 in TAP format (http://testanything.org/). Only useful for kernel devs
2598 running the KUnit test harness, and not intended for inclusion into a
2599 production build.
2600
2601 For more information on KUnit and unit tests in general please refer
2602 to the KUnit documentation in Documentation/dev-tools/kunit/.
2603
2604 If unsure, say N.
2605
2606config HASH_KUNIT_TEST
2607 tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS
2608 depends on KUNIT
2609 default KUNIT_ALL_TESTS
2610 help
2611 Enable this option to test the kernel's string (<linux/stringhash.h>), and
2612 integer (<linux/hash.h>) hash functions on boot.
2613
2614 KUnit tests run during boot and output the results to the debug log
2615 in TAP format (https://testanything.org/). Only useful for kernel devs
2616 running the KUnit test harness, and not intended for inclusion into a
2617 production build.
2618
2619 For more information on KUnit and unit tests in general please refer
2620 to the KUnit documentation in Documentation/dev-tools/kunit/.
2621
2622 This is intended to help people writing architecture-specific
2623 optimized versions. If unsure, say N.
2624
2625config RESOURCE_KUNIT_TEST
2626 tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS
2627 depends on KUNIT
2628 default KUNIT_ALL_TESTS
2629 help
2630 This builds the resource API unit test.
2631 Tests the logic of API provided by resource.c and ioport.h.
2632 For more information on KUnit and unit tests in general please refer
2633 to the KUnit documentation in Documentation/dev-tools/kunit/.
2634
2635 If unsure, say N.
2636
2637config SYSCTL_KUNIT_TEST
2638 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS
2639 depends on KUNIT
2640 default KUNIT_ALL_TESTS
2641 help
2642 This builds the proc sysctl unit test, which runs on boot.
2643 Tests the API contract and implementation correctness of sysctl.
2644 For more information on KUnit and unit tests in general please refer
2645 to the KUnit documentation in Documentation/dev-tools/kunit/.
2646
2647 If unsure, say N.
2648
2649config LIST_KUNIT_TEST
2650 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS
2651 depends on KUNIT
2652 default KUNIT_ALL_TESTS
2653 help
2654 This builds the linked list KUnit test suite.
2655 It tests that the API and basic functionality of the list_head type
2656 and associated macros.
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 If unsure, say N.
2667
2668config HASHTABLE_KUNIT_TEST
2669 tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS
2670 depends on KUNIT
2671 default KUNIT_ALL_TESTS
2672 help
2673 This builds the hashtable KUnit test suite.
2674 It tests the basic functionality of the API defined in
2675 include/linux/hashtable.h. For more information on KUnit and
2676 unit tests in general please refer to the KUnit documentation
2677 in Documentation/dev-tools/kunit/.
2678
2679 If unsure, say N.
2680
2681config LINEAR_RANGES_TEST
2682 tristate "KUnit test for linear_ranges"
2683 depends on KUNIT
2684 select LINEAR_RANGES
2685 help
2686 This builds the linear_ranges unit test, which runs on boot.
2687 Tests the linear_ranges logic correctness.
2688 For more information on KUnit and unit tests in general please refer
2689 to the KUnit documentation in Documentation/dev-tools/kunit/.
2690
2691 If unsure, say N.
2692
2693config CMDLINE_KUNIT_TEST
2694 tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS
2695 depends on KUNIT
2696 default KUNIT_ALL_TESTS
2697 help
2698 This builds the cmdline API unit test.
2699 Tests the logic of API provided by cmdline.c.
2700 For more information on KUnit and unit tests in general please refer
2701 to the KUnit documentation in Documentation/dev-tools/kunit/.
2702
2703 If unsure, say N.
2704
2705config BITS_TEST
2706 tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS
2707 depends on KUNIT
2708 default KUNIT_ALL_TESTS
2709 help
2710 This builds the bits unit test.
2711 Tests the logic of macros defined in bits.h.
2712 For more information on KUnit and unit tests in general please refer
2713 to the KUnit documentation in Documentation/dev-tools/kunit/.
2714
2715 If unsure, say N.
2716
2717config SLUB_KUNIT_TEST
2718 tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS
2719 depends on SLUB_DEBUG && KUNIT
2720 default KUNIT_ALL_TESTS
2721 help
2722 This builds SLUB allocator unit test.
2723 Tests SLUB cache debugging functionality.
2724 For more information on KUnit and unit tests in general please refer
2725 to the KUnit documentation in Documentation/dev-tools/kunit/.
2726
2727 If unsure, say N.
2728
2729config RATIONAL_KUNIT_TEST
2730 tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS
2731 depends on KUNIT && RATIONAL
2732 default KUNIT_ALL_TESTS
2733 help
2734 This builds the rational math unit test.
2735 For more information on KUnit and unit tests in general please refer
2736 to the KUnit documentation in Documentation/dev-tools/kunit/.
2737
2738 If unsure, say N.
2739
2740config MEMCPY_KUNIT_TEST
2741 tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS
2742 depends on KUNIT
2743 default KUNIT_ALL_TESTS
2744 help
2745 Builds unit tests for memcpy(), memmove(), and memset() functions.
2746 For more information on KUnit and unit tests in general please refer
2747 to the KUnit documentation in Documentation/dev-tools/kunit/.
2748
2749 If unsure, say N.
2750
2751config IS_SIGNED_TYPE_KUNIT_TEST
2752 tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS
2753 depends on KUNIT
2754 default KUNIT_ALL_TESTS
2755 help
2756 Builds unit tests for the is_signed_type() macro.
2757
2758 For more information on KUnit and unit tests in general please refer
2759 to the KUnit documentation in Documentation/dev-tools/kunit/.
2760
2761 If unsure, say N.
2762
2763config OVERFLOW_KUNIT_TEST
2764 tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS
2765 depends on KUNIT
2766 default KUNIT_ALL_TESTS
2767 help
2768 Builds unit tests for the check_*_overflow(), size_*(), allocation, and
2769 related functions.
2770
2771 For more information on KUnit and unit tests in general please refer
2772 to the KUnit documentation in Documentation/dev-tools/kunit/.
2773
2774 If unsure, say N.
2775
2776config STACKINIT_KUNIT_TEST
2777 tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS
2778 depends on KUNIT
2779 default KUNIT_ALL_TESTS
2780 help
2781 Test if the kernel is zero-initializing stack variables and
2782 padding. Coverage is controlled by compiler flags,
2783 CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO,
2784 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2785 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2786
2787config FORTIFY_KUNIT_TEST
2788 tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS
2789 depends on KUNIT
2790 default KUNIT_ALL_TESTS
2791 help
2792 Builds unit tests for checking internals of FORTIFY_SOURCE as used
2793 by the str*() and mem*() family of functions. For testing runtime
2794 traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests.
2795
2796config HW_BREAKPOINT_KUNIT_TEST
2797 bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS
2798 depends on HAVE_HW_BREAKPOINT
2799 depends on KUNIT=y
2800 default KUNIT_ALL_TESTS
2801 help
2802 Tests for hw_breakpoint constraints accounting.
2803
2804 If unsure, say N.
2805
2806config SIPHASH_KUNIT_TEST
2807 tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS
2808 depends on KUNIT
2809 default KUNIT_ALL_TESTS
2810 help
2811 Enable this option to test the kernel's siphash (<linux/siphash.h>) hash
2812 functions on boot (or module load).
2813
2814 This is intended to help people writing architecture-specific
2815 optimized versions. If unsure, say N.
2816
2817config TEST_UDELAY
2818 tristate "udelay test driver"
2819 help
2820 This builds the "udelay_test" module that helps to make sure
2821 that udelay() is working properly.
2822
2823 If unsure, say N.
2824
2825config TEST_STATIC_KEYS
2826 tristate "Test static keys"
2827 depends on m
2828 help
2829 Test the static key interfaces.
2830
2831 If unsure, say N.
2832
2833config TEST_DYNAMIC_DEBUG
2834 tristate "Test DYNAMIC_DEBUG"
2835 depends on DYNAMIC_DEBUG
2836 help
2837 This module registers a tracer callback to count enabled
2838 pr_debugs in a 'do_debugging' function, then alters their
2839 enablements, calls the function, and compares counts.
2840
2841 If unsure, say N.
2842
2843config TEST_KMOD
2844 tristate "kmod stress tester"
2845 depends on m
2846 depends on NETDEVICES && NET_CORE && INET # for TUN
2847 depends on BLOCK
2848 depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS
2849 select TEST_LKM
2850 select XFS_FS
2851 select TUN
2852 select BTRFS_FS
2853 help
2854 Test the kernel's module loading mechanism: kmod. kmod implements
2855 support to load modules using the Linux kernel's usermode helper.
2856 This test provides a series of tests against kmod.
2857
2858 Although technically you can either build test_kmod as a module or
2859 into the kernel we disallow building it into the kernel since
2860 it stress tests request_module() and this will very likely cause
2861 some issues by taking over precious threads available from other
2862 module load requests, ultimately this could be fatal.
2863
2864 To run tests run:
2865
2866 tools/testing/selftests/kmod/kmod.sh --help
2867
2868 If unsure, say N.
2869
2870config TEST_DEBUG_VIRTUAL
2871 tristate "Test CONFIG_DEBUG_VIRTUAL feature"
2872 depends on DEBUG_VIRTUAL
2873 help
2874 Test the kernel's ability to detect incorrect calls to
2875 virt_to_phys() done against the non-linear part of the
2876 kernel's virtual address map.
2877
2878 If unsure, say N.
2879
2880config TEST_MEMCAT_P
2881 tristate "Test memcat_p() helper function"
2882 help
2883 Test the memcat_p() helper for correctly merging two
2884 pointer arrays together.
2885
2886 If unsure, say N.
2887
2888config TEST_OBJAGG
2889 tristate "Perform selftest on object aggreration manager"
2890 default n
2891 depends on OBJAGG
2892 help
2893 Enable this option to test object aggregation manager on boot
2894 (or module load).
2895
2896config TEST_MEMINIT
2897 tristate "Test heap/page initialization"
2898 help
2899 Test if the kernel is zero-initializing heap and page allocations.
2900 This can be useful to test init_on_alloc and init_on_free features.
2901
2902 If unsure, say N.
2903
2904config TEST_HMM
2905 tristate "Test HMM (Heterogeneous Memory Management)"
2906 depends on TRANSPARENT_HUGEPAGE
2907 depends on DEVICE_PRIVATE
2908 select HMM_MIRROR
2909 select MMU_NOTIFIER
2910 help
2911 This is a pseudo device driver solely for testing HMM.
2912 Say M here if you want to build the HMM test module.
2913 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests.
2914
2915 If unsure, say N.
2916
2917config TEST_FREE_PAGES
2918 tristate "Test freeing pages"
2919 help
2920 Test that a memory leak does not occur due to a race between
2921 freeing a block of pages and a speculative page reference.
2922 Loading this module is safe if your kernel has the bug fixed.
2923 If the bug is not fixed, it will leak gigabytes of memory and
2924 probably OOM your system.
2925
2926config TEST_FPU
2927 tristate "Test floating point operations in kernel space"
2928 depends on ARCH_HAS_KERNEL_FPU_SUPPORT && !KCOV_INSTRUMENT_ALL
2929 help
2930 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu
2931 which will trigger a sequence of floating point operations. This is used
2932 for self-testing floating point control register setting in
2933 kernel_fpu_begin().
2934
2935 If unsure, say N.
2936
2937config TEST_CLOCKSOURCE_WATCHDOG
2938 tristate "Test clocksource watchdog in kernel space"
2939 depends on CLOCKSOURCE_WATCHDOG
2940 help
2941 Enable this option to create a kernel module that will trigger
2942 a test of the clocksource watchdog. This module may be loaded
2943 via modprobe or insmod in which case it will run upon being
2944 loaded, or it may be built in, in which case it will run
2945 shortly after boot.
2946
2947 If unsure, say N.
2948
2949config TEST_OBJPOOL
2950 tristate "Test module for correctness and stress of objpool"
2951 default n
2952 depends on m && DEBUG_KERNEL
2953 help
2954 This builds the "test_objpool" module that should be used for
2955 correctness verification and concurrent testings of objects
2956 allocation and reclamation.
2957
2958 If unsure, say N.
2959
2960endif # RUNTIME_TESTING_MENU
2961
2962config ARCH_USE_MEMTEST
2963 bool
2964 help
2965 An architecture should select this when it uses early_memtest()
2966 during boot process.
2967
2968config MEMTEST
2969 bool "Memtest"
2970 depends on ARCH_USE_MEMTEST
2971 help
2972 This option adds a kernel parameter 'memtest', which allows memtest
2973 to be set and executed.
2974 memtest=0, mean disabled; -- default
2975 memtest=1, mean do 1 test pattern;
2976 ...
2977 memtest=17, mean do 17 test patterns.
2978 If you are unsure how to answer this question, answer N.
2979
2980
2981
2982config HYPERV_TESTING
2983 bool "Microsoft Hyper-V driver testing"
2984 default n
2985 depends on HYPERV && DEBUG_FS
2986 help
2987 Select this option to enable Hyper-V vmbus testing.
2988
2989endmenu # "Kernel Testing and Coverage"
2990
2991menu "Rust hacking"
2992
2993config RUST_DEBUG_ASSERTIONS
2994 bool "Debug assertions"
2995 depends on RUST
2996 help
2997 Enables rustc's `-Cdebug-assertions` codegen option.
2998
2999 This flag lets you turn `cfg(debug_assertions)` conditional
3000 compilation on or off. This can be used to enable extra debugging
3001 code in development but not in production. For example, it controls
3002 the behavior of the standard library's `debug_assert!` macro.
3003
3004 Note that this will apply to all Rust code, including `core`.
3005
3006 If unsure, say N.
3007
3008config RUST_OVERFLOW_CHECKS
3009 bool "Overflow checks"
3010 default y
3011 depends on RUST
3012 help
3013 Enables rustc's `-Coverflow-checks` codegen option.
3014
3015 This flag allows you to control the behavior of runtime integer
3016 overflow. When overflow-checks are enabled, a Rust panic will occur
3017 on overflow.
3018
3019 Note that this will apply to all Rust code, including `core`.
3020
3021 If unsure, say Y.
3022
3023config RUST_BUILD_ASSERT_ALLOW
3024 bool "Allow unoptimized build-time assertions"
3025 depends on RUST
3026 help
3027 Controls how are `build_error!` and `build_assert!` handled during build.
3028
3029 If calls to them exist in the binary, it may indicate a violated invariant
3030 or that the optimizer failed to verify the invariant during compilation.
3031
3032 This should not happen, thus by default the build is aborted. However,
3033 as an escape hatch, you can choose Y here to ignore them during build
3034 and let the check be carried at runtime (with `panic!` being called if
3035 the check fails).
3036
3037 If unsure, say N.
3038
3039config RUST_KERNEL_DOCTESTS
3040 bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS
3041 depends on RUST && KUNIT=y
3042 default KUNIT_ALL_TESTS
3043 help
3044 This builds the documentation tests of the `kernel` crate
3045 as KUnit tests.
3046
3047 For more information on KUnit and unit tests in general,
3048 please refer to the KUnit documentation in Documentation/dev-tools/kunit/.
3049
3050 If unsure, say N.
3051
3052endmenu # "Rust"
3053
3054endmenu # Kernel hacking