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1 # SPDX-License-Identifier: GPL-2.0-only
2 menu "Kernel hacking"
3
4 menu "printk and dmesg options"
5
6 config 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
21 config 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
38 config 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
49 config 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
64 config 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
75 config 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
90 config 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
108 config 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
180 config 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
191 config 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
200 config 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
209 endmenu # "printk and dmesg options"
210
211 menu "Compile-time checks and compiler options"
212
213 config DEBUG_INFO
214 bool "Compile the kernel with debug info"
215 depends on DEBUG_KERNEL && !COMPILE_TEST
216 help
217 If you say Y here the resulting kernel image will include
218 debugging info resulting in a larger kernel image.
219 This adds debug symbols to the kernel and modules (gcc -g), and
220 is needed if you intend to use kernel crashdump or binary object
221 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
222 Say Y here only if you plan to debug the kernel.
223
224 If unsure, say N.
225
226 if DEBUG_INFO
227
228 config DEBUG_INFO_REDUCED
229 bool "Reduce debugging information"
230 help
231 If you say Y here gcc is instructed to generate less debugging
232 information for structure types. This means that tools that
233 need full debugging information (like kgdb or systemtap) won't
234 be happy. But if you merely need debugging information to
235 resolve line numbers there is no loss. Advantage is that
236 build directory object sizes shrink dramatically over a full
237 DEBUG_INFO build and compile times are reduced too.
238 Only works with newer gcc versions.
239
240 config DEBUG_INFO_COMPRESSED
241 bool "Compressed debugging information"
242 depends on $(cc-option,-gz=zlib)
243 depends on $(ld-option,--compress-debug-sections=zlib)
244 help
245 Compress the debug information using zlib. Requires GCC 5.0+ or Clang
246 5.0+, binutils 2.26+, and zlib.
247
248 Users of dpkg-deb via scripts/package/builddeb may find an increase in
249 size of their debug .deb packages with this config set, due to the
250 debug info being compressed with zlib, then the object files being
251 recompressed with a different compression scheme. But this is still
252 preferable to setting $KDEB_COMPRESS to "none" which would be even
253 larger.
254
255 config DEBUG_INFO_SPLIT
256 bool "Produce split debuginfo in .dwo files"
257 depends on $(cc-option,-gsplit-dwarf)
258 help
259 Generate debug info into separate .dwo files. This significantly
260 reduces the build directory size for builds with DEBUG_INFO,
261 because it stores the information only once on disk in .dwo
262 files instead of multiple times in object files and executables.
263 In addition the debug information is also compressed.
264
265 Requires recent gcc (4.7+) and recent gdb/binutils.
266 Any tool that packages or reads debug information would need
267 to know about the .dwo files and include them.
268 Incompatible with older versions of ccache.
269
270 choice
271 prompt "DWARF version"
272 help
273 Which version of DWARF debug info to emit.
274
275 config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
276 bool "Rely on the toolchain's implicit default DWARF version"
277 help
278 The implicit default version of DWARF debug info produced by a
279 toolchain changes over time.
280
281 This can break consumers of the debug info that haven't upgraded to
282 support newer revisions, and prevent testing newer versions, but
283 those should be less common scenarios.
284
285 If unsure, say Y.
286
287 config DEBUG_INFO_DWARF4
288 bool "Generate DWARF Version 4 debuginfo"
289 help
290 Generate DWARF v4 debug info. This requires gcc 4.5+ and gdb 7.0+.
291
292 If you have consumers of DWARF debug info that are not ready for
293 newer revisions of DWARF, you may wish to choose this or have your
294 config select this.
295
296 config DEBUG_INFO_DWARF5
297 bool "Generate DWARF Version 5 debuginfo"
298 depends on !CC_IS_CLANG || (CC_IS_CLANG && (AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502)))
299 depends on !DEBUG_INFO_BTF
300 help
301 Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc
302 5.0+ accepts the -gdwarf-5 flag but only had partial support for some
303 draft features until 7.0), and gdb 8.0+.
304
305 Changes to the structure of debug info in Version 5 allow for around
306 15-18% savings in resulting image and debug info section sizes as
307 compared to DWARF Version 4. DWARF Version 5 standardizes previous
308 extensions such as accelerators for symbol indexing and the format
309 for fission (.dwo/.dwp) files. Users may not want to select this
310 config if they rely on tooling that has not yet been updated to
311 support DWARF Version 5.
312
313 endchoice # "DWARF version"
314
315 config DEBUG_INFO_BTF
316 bool "Generate BTF typeinfo"
317 depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED
318 depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST
319 help
320 Generate deduplicated BTF type information from DWARF debug info.
321 Turning this on expects presence of pahole tool, which will convert
322 DWARF type info into equivalent deduplicated BTF type info.
323
324 config PAHOLE_HAS_SPLIT_BTF
325 def_bool $(success, test `$(PAHOLE) --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/'` -ge "119")
326
327 config DEBUG_INFO_BTF_MODULES
328 def_bool y
329 depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF
330 help
331 Generate compact split BTF type information for kernel modules.
332
333 config GDB_SCRIPTS
334 bool "Provide GDB scripts for kernel debugging"
335 help
336 This creates the required links to GDB helper scripts in the
337 build directory. If you load vmlinux into gdb, the helper
338 scripts will be automatically imported by gdb as well, and
339 additional functions are available to analyze a Linux kernel
340 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
341 for further details.
342
343 endif # DEBUG_INFO
344
345 config FRAME_WARN
346 int "Warn for stack frames larger than"
347 range 0 8192
348 default 2048 if GCC_PLUGIN_LATENT_ENTROPY
349 default 1536 if (!64BIT && (PARISC || XTENSA))
350 default 1024 if (!64BIT && !PARISC)
351 default 2048 if 64BIT
352 help
353 Tell gcc to warn at build time for stack frames larger than this.
354 Setting this too low will cause a lot of warnings.
355 Setting it to 0 disables the warning.
356
357 config STRIP_ASM_SYMS
358 bool "Strip assembler-generated symbols during link"
359 default n
360 help
361 Strip internal assembler-generated symbols during a link (symbols
362 that look like '.Lxxx') so they don't pollute the output of
363 get_wchan() and suchlike.
364
365 config READABLE_ASM
366 bool "Generate readable assembler code"
367 depends on DEBUG_KERNEL
368 depends on CC_IS_GCC
369 help
370 Disable some compiler optimizations that tend to generate human unreadable
371 assembler output. This may make the kernel slightly slower, but it helps
372 to keep kernel developers who have to stare a lot at assembler listings
373 sane.
374
375 config HEADERS_INSTALL
376 bool "Install uapi headers to usr/include"
377 depends on !UML
378 help
379 This option will install uapi headers (headers exported to user-space)
380 into the usr/include directory for use during the kernel build.
381 This is unneeded for building the kernel itself, but needed for some
382 user-space program samples. It is also needed by some features such
383 as uapi header sanity checks.
384
385 config DEBUG_SECTION_MISMATCH
386 bool "Enable full Section mismatch analysis"
387 depends on CC_IS_GCC
388 help
389 The section mismatch analysis checks if there are illegal
390 references from one section to another section.
391 During linktime or runtime, some sections are dropped;
392 any use of code/data previously in these sections would
393 most likely result in an oops.
394 In the code, functions and variables are annotated with
395 __init,, etc. (see the full list in include/linux/init.h),
396 which results in the code/data being placed in specific sections.
397 The section mismatch analysis is always performed after a full
398 kernel build, and enabling this option causes the following
399 additional step to occur:
400 - Add the option -fno-inline-functions-called-once to gcc commands.
401 When inlining a function annotated with __init in a non-init
402 function, we would lose the section information and thus
403 the analysis would not catch the illegal reference.
404 This option tells gcc to inline less (but it does result in
405 a larger kernel).
406
407 config SECTION_MISMATCH_WARN_ONLY
408 bool "Make section mismatch errors non-fatal"
409 default y
410 help
411 If you say N here, the build process will fail if there are any
412 section mismatch, instead of just throwing warnings.
413
414 If unsure, say Y.
415
416 config DEBUG_FORCE_FUNCTION_ALIGN_64B
417 bool "Force all function address 64B aligned" if EXPERT
418 help
419 There are cases that a commit from one domain changes the function
420 address alignment of other domains, and cause magic performance
421 bump (regression or improvement). Enable this option will help to
422 verify if the bump is caused by function alignment changes, while
423 it will slightly increase the kernel size and affect icache usage.
424
425 It is mainly for debug and performance tuning use.
426
427 #
428 # Select this config option from the architecture Kconfig, if it
429 # is preferred to always offer frame pointers as a config
430 # option on the architecture (regardless of KERNEL_DEBUG):
431 #
432 config ARCH_WANT_FRAME_POINTERS
433 bool
434
435 config FRAME_POINTER
436 bool "Compile the kernel with frame pointers"
437 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
438 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
439 help
440 If you say Y here the resulting kernel image will be slightly
441 larger and slower, but it gives very useful debugging information
442 in case of kernel bugs. (precise oopses/stacktraces/warnings)
443
444 config STACK_VALIDATION
445 bool "Compile-time stack metadata validation"
446 depends on HAVE_STACK_VALIDATION
447 default n
448 help
449 Add compile-time checks to validate stack metadata, including frame
450 pointers (if CONFIG_FRAME_POINTER is enabled). This helps ensure
451 that runtime stack traces are more reliable.
452
453 This is also a prerequisite for generation of ORC unwind data, which
454 is needed for CONFIG_UNWINDER_ORC.
455
456 For more information, see
457 tools/objtool/Documentation/stack-validation.txt.
458
459 config VMLINUX_VALIDATION
460 bool
461 depends on STACK_VALIDATION && DEBUG_ENTRY && !PARAVIRT
462 default y
463
464 config VMLINUX_MAP
465 bool "Generate vmlinux.map file when linking"
466 depends on EXPERT
467 help
468 Selecting this option will pass "-Map=vmlinux.map" to ld
469 when linking vmlinux. That file can be useful for verifying
470 and debugging magic section games, and for seeing which
471 pieces of code get eliminated with
472 CONFIG_LD_DEAD_CODE_DATA_ELIMINATION.
473
474 config DEBUG_FORCE_WEAK_PER_CPU
475 bool "Force weak per-cpu definitions"
476 depends on DEBUG_KERNEL
477 help
478 s390 and alpha require percpu variables in modules to be
479 defined weak to work around addressing range issue which
480 puts the following two restrictions on percpu variable
481 definitions.
482
483 1. percpu symbols must be unique whether static or not
484 2. percpu variables can't be defined inside a function
485
486 To ensure that generic code follows the above rules, this
487 option forces all percpu variables to be defined as weak.
488
489 endmenu # "Compiler options"
490
491 menu "Generic Kernel Debugging Instruments"
492
493 config MAGIC_SYSRQ
494 bool "Magic SysRq key"
495 depends on !UML
496 help
497 If you say Y here, you will have some control over the system even
498 if the system crashes for example during kernel debugging (e.g., you
499 will be able to flush the buffer cache to disk, reboot the system
500 immediately or dump some status information). This is accomplished
501 by pressing various keys while holding SysRq (Alt+PrintScreen). It
502 also works on a serial console (on PC hardware at least), if you
503 send a BREAK and then within 5 seconds a command keypress. The
504 keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
505 Don't say Y unless you really know what this hack does.
506
507 config MAGIC_SYSRQ_DEFAULT_ENABLE
508 hex "Enable magic SysRq key functions by default"
509 depends on MAGIC_SYSRQ
510 default 0x1
511 help
512 Specifies which SysRq key functions are enabled by default.
513 This may be set to 1 or 0 to enable or disable them all, or
514 to a bitmask as described in Documentation/admin-guide/sysrq.rst.
515
516 config MAGIC_SYSRQ_SERIAL
517 bool "Enable magic SysRq key over serial"
518 depends on MAGIC_SYSRQ
519 default y
520 help
521 Many embedded boards have a disconnected TTL level serial which can
522 generate some garbage that can lead to spurious false sysrq detects.
523 This option allows you to decide whether you want to enable the
524 magic SysRq key.
525
526 config MAGIC_SYSRQ_SERIAL_SEQUENCE
527 string "Char sequence that enables magic SysRq over serial"
528 depends on MAGIC_SYSRQ_SERIAL
529 default ""
530 help
531 Specifies a sequence of characters that can follow BREAK to enable
532 SysRq on a serial console.
533
534 If unsure, leave an empty string and the option will not be enabled.
535
536 config DEBUG_FS
537 bool "Debug Filesystem"
538 help
539 debugfs is a virtual file system that kernel developers use to put
540 debugging files into. Enable this option to be able to read and
541 write to these files.
542
543 For detailed documentation on the debugfs API, see
544 Documentation/filesystems/.
545
546 If unsure, say N.
547
548 choice
549 prompt "Debugfs default access"
550 depends on DEBUG_FS
551 default DEBUG_FS_ALLOW_ALL
552 help
553 This selects the default access restrictions for debugfs.
554 It can be overridden with kernel command line option
555 debugfs=[on,no-mount,off]. The restrictions apply for API access
556 and filesystem registration.
557
558 config DEBUG_FS_ALLOW_ALL
559 bool "Access normal"
560 help
561 No restrictions apply. Both API and filesystem registration
562 is on. This is the normal default operation.
563
564 config DEBUG_FS_DISALLOW_MOUNT
565 bool "Do not register debugfs as filesystem"
566 help
567 The API is open but filesystem is not loaded. Clients can still do
568 their work and read with debug tools that do not need
569 debugfs filesystem.
570
571 config DEBUG_FS_ALLOW_NONE
572 bool "No access"
573 help
574 Access is off. Clients get -PERM when trying to create nodes in
575 debugfs tree and debugfs is not registered as a filesystem.
576 Client can then back-off or continue without debugfs access.
577
578 endchoice
579
580 source "lib/Kconfig.kgdb"
581 source "lib/Kconfig.ubsan"
582 source "lib/Kconfig.kcsan"
583
584 endmenu
585
586 config DEBUG_KERNEL
587 bool "Kernel debugging"
588 help
589 Say Y here if you are developing drivers or trying to debug and
590 identify kernel problems.
591
592 config DEBUG_MISC
593 bool "Miscellaneous debug code"
594 default DEBUG_KERNEL
595 depends on DEBUG_KERNEL
596 help
597 Say Y here if you need to enable miscellaneous debug code that should
598 be under a more specific debug option but isn't.
599
600
601 menu "Memory Debugging"
602
603 source "mm/Kconfig.debug"
604
605 config DEBUG_OBJECTS
606 bool "Debug object operations"
607 depends on DEBUG_KERNEL
608 help
609 If you say Y here, additional code will be inserted into the
610 kernel to track the life time of various objects and validate
611 the operations on those objects.
612
613 config DEBUG_OBJECTS_SELFTEST
614 bool "Debug objects selftest"
615 depends on DEBUG_OBJECTS
616 help
617 This enables the selftest of the object debug code.
618
619 config DEBUG_OBJECTS_FREE
620 bool "Debug objects in freed memory"
621 depends on DEBUG_OBJECTS
622 help
623 This enables checks whether a k/v free operation frees an area
624 which contains an object which has not been deactivated
625 properly. This can make kmalloc/kfree-intensive workloads
626 much slower.
627
628 config DEBUG_OBJECTS_TIMERS
629 bool "Debug timer objects"
630 depends on DEBUG_OBJECTS
631 help
632 If you say Y here, additional code will be inserted into the
633 timer routines to track the life time of timer objects and
634 validate the timer operations.
635
636 config DEBUG_OBJECTS_WORK
637 bool "Debug work objects"
638 depends on DEBUG_OBJECTS
639 help
640 If you say Y here, additional code will be inserted into the
641 work queue routines to track the life time of work objects and
642 validate the work operations.
643
644 config DEBUG_OBJECTS_RCU_HEAD
645 bool "Debug RCU callbacks objects"
646 depends on DEBUG_OBJECTS
647 help
648 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
649
650 config DEBUG_OBJECTS_PERCPU_COUNTER
651 bool "Debug percpu counter objects"
652 depends on DEBUG_OBJECTS
653 help
654 If you say Y here, additional code will be inserted into the
655 percpu counter routines to track the life time of percpu counter
656 objects and validate the percpu counter operations.
657
658 config DEBUG_OBJECTS_ENABLE_DEFAULT
659 int "debug_objects bootup default value (0-1)"
660 range 0 1
661 default "1"
662 depends on DEBUG_OBJECTS
663 help
664 Debug objects boot parameter default value
665
666 config DEBUG_SLAB
667 bool "Debug slab memory allocations"
668 depends on DEBUG_KERNEL && SLAB
669 help
670 Say Y here to have the kernel do limited verification on memory
671 allocation as well as poisoning memory on free to catch use of freed
672 memory. This can make kmalloc/kfree-intensive workloads much slower.
673
674 config SLUB_DEBUG_ON
675 bool "SLUB debugging on by default"
676 depends on SLUB && SLUB_DEBUG
677 default n
678 help
679 Boot with debugging on by default. SLUB boots by default with
680 the runtime debug capabilities switched off. Enabling this is
681 equivalent to specifying the "slub_debug" parameter on boot.
682 There is no support for more fine grained debug control like
683 possible with slub_debug=xxx. SLUB debugging may be switched
684 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
685 "slub_debug=-".
686
687 config SLUB_STATS
688 default n
689 bool "Enable SLUB performance statistics"
690 depends on SLUB && SYSFS
691 help
692 SLUB statistics are useful to debug SLUBs allocation behavior in
693 order find ways to optimize the allocator. This should never be
694 enabled for production use since keeping statistics slows down
695 the allocator by a few percentage points. The slabinfo command
696 supports the determination of the most active slabs to figure
697 out which slabs are relevant to a particular load.
698 Try running: slabinfo -DA
699
700 config HAVE_DEBUG_KMEMLEAK
701 bool
702
703 config DEBUG_KMEMLEAK
704 bool "Kernel memory leak detector"
705 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
706 select DEBUG_FS
707 select STACKTRACE if STACKTRACE_SUPPORT
708 select KALLSYMS
709 select CRC32
710 help
711 Say Y here if you want to enable the memory leak
712 detector. The memory allocation/freeing is traced in a way
713 similar to the Boehm's conservative garbage collector, the
714 difference being that the orphan objects are not freed but
715 only shown in /sys/kernel/debug/kmemleak. Enabling this
716 feature will introduce an overhead to memory
717 allocations. See Documentation/dev-tools/kmemleak.rst for more
718 details.
719
720 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
721 of finding leaks due to the slab objects poisoning.
722
723 In order to access the kmemleak file, debugfs needs to be
724 mounted (usually at /sys/kernel/debug).
725
726 config DEBUG_KMEMLEAK_MEM_POOL_SIZE
727 int "Kmemleak memory pool size"
728 depends on DEBUG_KMEMLEAK
729 range 200 1000000
730 default 16000
731 help
732 Kmemleak must track all the memory allocations to avoid
733 reporting false positives. Since memory may be allocated or
734 freed before kmemleak is fully initialised, use a static pool
735 of metadata objects to track such callbacks. After kmemleak is
736 fully initialised, this memory pool acts as an emergency one
737 if slab allocations fail.
738
739 config DEBUG_KMEMLEAK_TEST
740 tristate "Simple test for the kernel memory leak detector"
741 depends on DEBUG_KMEMLEAK && m
742 help
743 This option enables a module that explicitly leaks memory.
744
745 If unsure, say N.
746
747 config DEBUG_KMEMLEAK_DEFAULT_OFF
748 bool "Default kmemleak to off"
749 depends on DEBUG_KMEMLEAK
750 help
751 Say Y here to disable kmemleak by default. It can then be enabled
752 on the command line via kmemleak=on.
753
754 config DEBUG_KMEMLEAK_AUTO_SCAN
755 bool "Enable kmemleak auto scan thread on boot up"
756 default y
757 depends on DEBUG_KMEMLEAK
758 help
759 Depending on the cpu, kmemleak scan may be cpu intensive and can
760 stall user tasks at times. This option enables/disables automatic
761 kmemleak scan at boot up.
762
763 Say N here to disable kmemleak auto scan thread to stop automatic
764 scanning. Disabling this option disables automatic reporting of
765 memory leaks.
766
767 If unsure, say Y.
768
769 config DEBUG_STACK_USAGE
770 bool "Stack utilization instrumentation"
771 depends on DEBUG_KERNEL && !IA64
772 help
773 Enables the display of the minimum amount of free stack which each
774 task has ever had available in the sysrq-T and sysrq-P debug output.
775
776 This option will slow down process creation somewhat.
777
778 config SCHED_STACK_END_CHECK
779 bool "Detect stack corruption on calls to schedule()"
780 depends on DEBUG_KERNEL
781 default n
782 help
783 This option checks for a stack overrun on calls to schedule().
784 If the stack end location is found to be over written always panic as
785 the content of the corrupted region can no longer be trusted.
786 This is to ensure no erroneous behaviour occurs which could result in
787 data corruption or a sporadic crash at a later stage once the region
788 is examined. The runtime overhead introduced is minimal.
789
790 config ARCH_HAS_DEBUG_VM_PGTABLE
791 bool
792 help
793 An architecture should select this when it can successfully
794 build and run DEBUG_VM_PGTABLE.
795
796 config DEBUG_VM
797 bool "Debug VM"
798 depends on DEBUG_KERNEL
799 help
800 Enable this to turn on extended checks in the virtual-memory system
801 that may impact performance.
802
803 If unsure, say N.
804
805 config DEBUG_VM_VMACACHE
806 bool "Debug VMA caching"
807 depends on DEBUG_VM
808 help
809 Enable this to turn on VMA caching debug information. Doing so
810 can cause significant overhead, so only enable it in non-production
811 environments.
812
813 If unsure, say N.
814
815 config DEBUG_VM_RB
816 bool "Debug VM red-black trees"
817 depends on DEBUG_VM
818 help
819 Enable VM red-black tree debugging information and extra validations.
820
821 If unsure, say N.
822
823 config DEBUG_VM_PGFLAGS
824 bool "Debug page-flags operations"
825 depends on DEBUG_VM
826 help
827 Enables extra validation on page flags operations.
828
829 If unsure, say N.
830
831 config DEBUG_VM_PGTABLE
832 bool "Debug arch page table for semantics compliance"
833 depends on MMU
834 depends on ARCH_HAS_DEBUG_VM_PGTABLE
835 default y if DEBUG_VM
836 help
837 This option provides a debug method which can be used to test
838 architecture page table helper functions on various platforms in
839 verifying if they comply with expected generic MM semantics. This
840 will help architecture code in making sure that any changes or
841 new additions of these helpers still conform to expected
842 semantics of the generic MM. Platforms will have to opt in for
843 this through ARCH_HAS_DEBUG_VM_PGTABLE.
844
845 If unsure, say N.
846
847 config ARCH_HAS_DEBUG_VIRTUAL
848 bool
849
850 config DEBUG_VIRTUAL
851 bool "Debug VM translations"
852 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
853 help
854 Enable some costly sanity checks in virtual to page code. This can
855 catch mistakes with virt_to_page() and friends.
856
857 If unsure, say N.
858
859 config DEBUG_NOMMU_REGIONS
860 bool "Debug the global anon/private NOMMU mapping region tree"
861 depends on DEBUG_KERNEL && !MMU
862 help
863 This option causes the global tree of anonymous and private mapping
864 regions to be regularly checked for invalid topology.
865
866 config DEBUG_MEMORY_INIT
867 bool "Debug memory initialisation" if EXPERT
868 default !EXPERT
869 help
870 Enable this for additional checks during memory initialisation.
871 The sanity checks verify aspects of the VM such as the memory model
872 and other information provided by the architecture. Verbose
873 information will be printed at KERN_DEBUG loglevel depending
874 on the mminit_loglevel= command-line option.
875
876 If unsure, say Y
877
878 config MEMORY_NOTIFIER_ERROR_INJECT
879 tristate "Memory hotplug notifier error injection module"
880 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
881 help
882 This option provides the ability to inject artificial errors to
883 memory hotplug notifier chain callbacks. It is controlled through
884 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
885
886 If the notifier call chain should be failed with some events
887 notified, write the error code to "actions/<notifier event>/error".
888
889 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
890
891 # cd /sys/kernel/debug/notifier-error-inject/memory
892 # echo -12 > actions/MEM_GOING_OFFLINE/error
893 # echo offline > /sys/devices/system/memory/memoryXXX/state
894 bash: echo: write error: Cannot allocate memory
895
896 To compile this code as a module, choose M here: the module will
897 be called memory-notifier-error-inject.
898
899 If unsure, say N.
900
901 config DEBUG_PER_CPU_MAPS
902 bool "Debug access to per_cpu maps"
903 depends on DEBUG_KERNEL
904 depends on SMP
905 help
906 Say Y to verify that the per_cpu map being accessed has
907 been set up. This adds a fair amount of code to kernel memory
908 and decreases performance.
909
910 Say N if unsure.
911
912 config DEBUG_KMAP_LOCAL
913 bool "Debug kmap_local temporary mappings"
914 depends on DEBUG_KERNEL && KMAP_LOCAL
915 help
916 This option enables additional error checking for the kmap_local
917 infrastructure. Disable for production use.
918
919 config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
920 bool
921
922 config DEBUG_KMAP_LOCAL_FORCE_MAP
923 bool "Enforce kmap_local temporary mappings"
924 depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
925 select KMAP_LOCAL
926 select DEBUG_KMAP_LOCAL
927 help
928 This option enforces temporary mappings through the kmap_local
929 mechanism for non-highmem pages and on non-highmem systems.
930 Disable this for production systems!
931
932 config DEBUG_HIGHMEM
933 bool "Highmem debugging"
934 depends on DEBUG_KERNEL && HIGHMEM
935 select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
936 select DEBUG_KMAP_LOCAL
937 help
938 This option enables additional error checking for high memory
939 systems. Disable for production systems.
940
941 config HAVE_DEBUG_STACKOVERFLOW
942 bool
943
944 config DEBUG_STACKOVERFLOW
945 bool "Check for stack overflows"
946 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
947 help
948 Say Y here if you want to check for overflows of kernel, IRQ
949 and exception stacks (if your architecture uses them). This
950 option will show detailed messages if free stack space drops
951 below a certain limit.
952
953 These kinds of bugs usually occur when call-chains in the
954 kernel get too deep, especially when interrupts are
955 involved.
956
957 Use this in cases where you see apparently random memory
958 corruption, especially if it appears in 'struct thread_info'
959
960 If in doubt, say "N".
961
962 source "lib/Kconfig.kasan"
963 source "lib/Kconfig.kfence"
964
965 endmenu # "Memory Debugging"
966
967 config DEBUG_SHIRQ
968 bool "Debug shared IRQ handlers"
969 depends on DEBUG_KERNEL
970 help
971 Enable this to generate a spurious interrupt just before a shared
972 interrupt handler is deregistered (generating one when registering
973 is currently disabled). Drivers need to handle this correctly. Some
974 don't and need to be caught.
975
976 menu "Debug Oops, Lockups and Hangs"
977
978 config PANIC_ON_OOPS
979 bool "Panic on Oops"
980 help
981 Say Y here to enable the kernel to panic when it oopses. This
982 has the same effect as setting oops=panic on the kernel command
983 line.
984
985 This feature is useful to ensure that the kernel does not do
986 anything erroneous after an oops which could result in data
987 corruption or other issues.
988
989 Say N if unsure.
990
991 config PANIC_ON_OOPS_VALUE
992 int
993 range 0 1
994 default 0 if !PANIC_ON_OOPS
995 default 1 if PANIC_ON_OOPS
996
997 config PANIC_TIMEOUT
998 int "panic timeout"
999 default 0
1000 help
1001 Set the timeout value (in seconds) until a reboot occurs when
1002 the kernel panics. If n = 0, then we wait forever. A timeout
1003 value n > 0 will wait n seconds before rebooting, while a timeout
1004 value n < 0 will reboot immediately.
1005
1006 config LOCKUP_DETECTOR
1007 bool
1008
1009 config SOFTLOCKUP_DETECTOR
1010 bool "Detect Soft Lockups"
1011 depends on DEBUG_KERNEL && !S390
1012 select LOCKUP_DETECTOR
1013 help
1014 Say Y here to enable the kernel to act as a watchdog to detect
1015 soft lockups.
1016
1017 Softlockups are bugs that cause the kernel to loop in kernel
1018 mode for more than 20 seconds, without giving other tasks a
1019 chance to run. The current stack trace is displayed upon
1020 detection and the system will stay locked up.
1021
1022 config BOOTPARAM_SOFTLOCKUP_PANIC
1023 bool "Panic (Reboot) On Soft Lockups"
1024 depends on SOFTLOCKUP_DETECTOR
1025 help
1026 Say Y here to enable the kernel to panic on "soft lockups",
1027 which are bugs that cause the kernel to loop in kernel
1028 mode for more than 20 seconds (configurable using the watchdog_thresh
1029 sysctl), without giving other tasks a chance to run.
1030
1031 The panic can be used in combination with panic_timeout,
1032 to cause the system to reboot automatically after a
1033 lockup has been detected. This feature is useful for
1034 high-availability systems that have uptime guarantees and
1035 where a lockup must be resolved ASAP.
1036
1037 Say N if unsure.
1038
1039 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
1040 int
1041 depends on SOFTLOCKUP_DETECTOR
1042 range 0 1
1043 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
1044 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
1045
1046 config HARDLOCKUP_DETECTOR_PERF
1047 bool
1048 select SOFTLOCKUP_DETECTOR
1049
1050 #
1051 # Enables a timestamp based low pass filter to compensate for perf based
1052 # hard lockup detection which runs too fast due to turbo modes.
1053 #
1054 config HARDLOCKUP_CHECK_TIMESTAMP
1055 bool
1056
1057 #
1058 # arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard
1059 # lockup detector rather than the perf based detector.
1060 #
1061 config HARDLOCKUP_DETECTOR
1062 bool "Detect Hard Lockups"
1063 depends on DEBUG_KERNEL && !S390
1064 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH
1065 select LOCKUP_DETECTOR
1066 select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF
1067 help
1068 Say Y here to enable the kernel to act as a watchdog to detect
1069 hard lockups.
1070
1071 Hardlockups are bugs that cause the CPU to loop in kernel mode
1072 for more than 10 seconds, without letting other interrupts have a
1073 chance to run. The current stack trace is displayed upon detection
1074 and the system will stay locked up.
1075
1076 config BOOTPARAM_HARDLOCKUP_PANIC
1077 bool "Panic (Reboot) On Hard Lockups"
1078 depends on HARDLOCKUP_DETECTOR
1079 help
1080 Say Y here to enable the kernel to panic on "hard lockups",
1081 which are bugs that cause the kernel to loop in kernel
1082 mode with interrupts disabled for more than 10 seconds (configurable
1083 using the watchdog_thresh sysctl).
1084
1085 Say N if unsure.
1086
1087 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
1088 int
1089 depends on HARDLOCKUP_DETECTOR
1090 range 0 1
1091 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
1092 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
1093
1094 config DETECT_HUNG_TASK
1095 bool "Detect Hung Tasks"
1096 depends on DEBUG_KERNEL
1097 default SOFTLOCKUP_DETECTOR
1098 help
1099 Say Y here to enable the kernel to detect "hung tasks",
1100 which are bugs that cause the task to be stuck in
1101 uninterruptible "D" state indefinitely.
1102
1103 When a hung task is detected, the kernel will print the
1104 current stack trace (which you should report), but the
1105 task will stay in uninterruptible state. If lockdep is
1106 enabled then all held locks will also be reported. This
1107 feature has negligible overhead.
1108
1109 config DEFAULT_HUNG_TASK_TIMEOUT
1110 int "Default timeout for hung task detection (in seconds)"
1111 depends on DETECT_HUNG_TASK
1112 default 120
1113 help
1114 This option controls the default timeout (in seconds) used
1115 to determine when a task has become non-responsive and should
1116 be considered hung.
1117
1118 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
1119 sysctl or by writing a value to
1120 /proc/sys/kernel/hung_task_timeout_secs.
1121
1122 A timeout of 0 disables the check. The default is two minutes.
1123 Keeping the default should be fine in most cases.
1124
1125 config BOOTPARAM_HUNG_TASK_PANIC
1126 bool "Panic (Reboot) On Hung Tasks"
1127 depends on DETECT_HUNG_TASK
1128 help
1129 Say Y here to enable the kernel to panic on "hung tasks",
1130 which are bugs that cause the kernel to leave a task stuck
1131 in uninterruptible "D" state.
1132
1133 The panic can be used in combination with panic_timeout,
1134 to cause the system to reboot automatically after a
1135 hung task has been detected. This feature is useful for
1136 high-availability systems that have uptime guarantees and
1137 where a hung tasks must be resolved ASAP.
1138
1139 Say N if unsure.
1140
1141 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
1142 int
1143 depends on DETECT_HUNG_TASK
1144 range 0 1
1145 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
1146 default 1 if BOOTPARAM_HUNG_TASK_PANIC
1147
1148 config WQ_WATCHDOG
1149 bool "Detect Workqueue Stalls"
1150 depends on DEBUG_KERNEL
1151 help
1152 Say Y here to enable stall detection on workqueues. If a
1153 worker pool doesn't make forward progress on a pending work
1154 item for over a given amount of time, 30s by default, a
1155 warning message is printed along with dump of workqueue
1156 state. This can be configured through kernel parameter
1157 "workqueue.watchdog_thresh" and its sysfs counterpart.
1158
1159 config TEST_LOCKUP
1160 tristate "Test module to generate lockups"
1161 depends on m
1162 help
1163 This builds the "test_lockup" module that helps to make sure
1164 that watchdogs and lockup detectors are working properly.
1165
1166 Depending on module parameters it could emulate soft or hard
1167 lockup, "hung task", or locking arbitrary lock for a long time.
1168 Also it could generate series of lockups with cooling-down periods.
1169
1170 If unsure, say N.
1171
1172 endmenu # "Debug lockups and hangs"
1173
1174 menu "Scheduler Debugging"
1175
1176 config SCHED_DEBUG
1177 bool "Collect scheduler debugging info"
1178 depends on DEBUG_KERNEL && PROC_FS
1179 default y
1180 help
1181 If you say Y here, the /proc/sched_debug file will be provided
1182 that can help debug the scheduler. The runtime overhead of this
1183 option is minimal.
1184
1185 config SCHED_INFO
1186 bool
1187 default n
1188
1189 config SCHEDSTATS
1190 bool "Collect scheduler statistics"
1191 depends on DEBUG_KERNEL && PROC_FS
1192 select SCHED_INFO
1193 help
1194 If you say Y here, additional code will be inserted into the
1195 scheduler and related routines to collect statistics about
1196 scheduler behavior and provide them in /proc/schedstat. These
1197 stats may be useful for both tuning and debugging the scheduler
1198 If you aren't debugging the scheduler or trying to tune a specific
1199 application, you can say N to avoid the very slight overhead
1200 this adds.
1201
1202 endmenu
1203
1204 config DEBUG_TIMEKEEPING
1205 bool "Enable extra timekeeping sanity checking"
1206 help
1207 This option will enable additional timekeeping sanity checks
1208 which may be helpful when diagnosing issues where timekeeping
1209 problems are suspected.
1210
1211 This may include checks in the timekeeping hotpaths, so this
1212 option may have a (very small) performance impact to some
1213 workloads.
1214
1215 If unsure, say N.
1216
1217 config DEBUG_PREEMPT
1218 bool "Debug preemptible kernel"
1219 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT
1220 default y
1221 help
1222 If you say Y here then the kernel will use a debug variant of the
1223 commonly used smp_processor_id() function and will print warnings
1224 if kernel code uses it in a preemption-unsafe way. Also, the kernel
1225 will detect preemption count underflows.
1226
1227 menu "Lock Debugging (spinlocks, mutexes, etc...)"
1228
1229 config LOCK_DEBUGGING_SUPPORT
1230 bool
1231 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1232 default y
1233
1234 config PROVE_LOCKING
1235 bool "Lock debugging: prove locking correctness"
1236 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1237 select LOCKDEP
1238 select DEBUG_SPINLOCK
1239 select DEBUG_MUTEXES if !PREEMPT_RT
1240 select DEBUG_RT_MUTEXES if RT_MUTEXES
1241 select DEBUG_RWSEMS
1242 select DEBUG_WW_MUTEX_SLOWPATH
1243 select DEBUG_LOCK_ALLOC
1244 select PREEMPT_COUNT if !ARCH_NO_PREEMPT
1245 select TRACE_IRQFLAGS
1246 default n
1247 help
1248 This feature enables the kernel to prove that all locking
1249 that occurs in the kernel runtime is mathematically
1250 correct: that under no circumstance could an arbitrary (and
1251 not yet triggered) combination of observed locking
1252 sequences (on an arbitrary number of CPUs, running an
1253 arbitrary number of tasks and interrupt contexts) cause a
1254 deadlock.
1255
1256 In short, this feature enables the kernel to report locking
1257 related deadlocks before they actually occur.
1258
1259 The proof does not depend on how hard and complex a
1260 deadlock scenario would be to trigger: how many
1261 participant CPUs, tasks and irq-contexts would be needed
1262 for it to trigger. The proof also does not depend on
1263 timing: if a race and a resulting deadlock is possible
1264 theoretically (no matter how unlikely the race scenario
1265 is), it will be proven so and will immediately be
1266 reported by the kernel (once the event is observed that
1267 makes the deadlock theoretically possible).
1268
1269 If a deadlock is impossible (i.e. the locking rules, as
1270 observed by the kernel, are mathematically correct), the
1271 kernel reports nothing.
1272
1273 NOTE: this feature can also be enabled for rwlocks, mutexes
1274 and rwsems - in which case all dependencies between these
1275 different locking variants are observed and mapped too, and
1276 the proof of observed correctness is also maintained for an
1277 arbitrary combination of these separate locking variants.
1278
1279 For more details, see Documentation/locking/lockdep-design.rst.
1280
1281 config PROVE_RAW_LOCK_NESTING
1282 bool "Enable raw_spinlock - spinlock nesting checks"
1283 depends on PROVE_LOCKING
1284 default n
1285 help
1286 Enable the raw_spinlock vs. spinlock nesting checks which ensure
1287 that the lock nesting rules for PREEMPT_RT enabled kernels are
1288 not violated.
1289
1290 NOTE: There are known nesting problems. So if you enable this
1291 option expect lockdep splats until these problems have been fully
1292 addressed which is work in progress. This config switch allows to
1293 identify and analyze these problems. It will be removed and the
1294 check permanently enabled once the main issues have been fixed.
1295
1296 If unsure, select N.
1297
1298 config LOCK_STAT
1299 bool "Lock usage statistics"
1300 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1301 select LOCKDEP
1302 select DEBUG_SPINLOCK
1303 select DEBUG_MUTEXES if !PREEMPT_RT
1304 select DEBUG_RT_MUTEXES if RT_MUTEXES
1305 select DEBUG_LOCK_ALLOC
1306 default n
1307 help
1308 This feature enables tracking lock contention points
1309
1310 For more details, see Documentation/locking/lockstat.rst
1311
1312 This also enables lock events required by "perf lock",
1313 subcommand of perf.
1314 If you want to use "perf lock", you also need to turn on
1315 CONFIG_EVENT_TRACING.
1316
1317 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1318 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1319
1320 config DEBUG_RT_MUTEXES
1321 bool "RT Mutex debugging, deadlock detection"
1322 depends on DEBUG_KERNEL && RT_MUTEXES
1323 help
1324 This allows rt mutex semantics violations and rt mutex related
1325 deadlocks (lockups) to be detected and reported automatically.
1326
1327 config DEBUG_SPINLOCK
1328 bool "Spinlock and rw-lock debugging: basic checks"
1329 depends on DEBUG_KERNEL
1330 select UNINLINE_SPIN_UNLOCK
1331 help
1332 Say Y here and build SMP to catch missing spinlock initialization
1333 and certain other kinds of spinlock errors commonly made. This is
1334 best used in conjunction with the NMI watchdog so that spinlock
1335 deadlocks are also debuggable.
1336
1337 config DEBUG_MUTEXES
1338 bool "Mutex debugging: basic checks"
1339 depends on DEBUG_KERNEL && !PREEMPT_RT
1340 help
1341 This feature allows mutex semantics violations to be detected and
1342 reported.
1343
1344 config DEBUG_WW_MUTEX_SLOWPATH
1345 bool "Wait/wound mutex debugging: Slowpath testing"
1346 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1347 select DEBUG_LOCK_ALLOC
1348 select DEBUG_SPINLOCK
1349 select DEBUG_MUTEXES if !PREEMPT_RT
1350 select DEBUG_RT_MUTEXES if PREEMPT_RT
1351 help
1352 This feature enables slowpath testing for w/w mutex users by
1353 injecting additional -EDEADLK wound/backoff cases. Together with
1354 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1355 will test all possible w/w mutex interface abuse with the
1356 exception of simply not acquiring all the required locks.
1357 Note that this feature can introduce significant overhead, so
1358 it really should not be enabled in a production or distro kernel,
1359 even a debug kernel. If you are a driver writer, enable it. If
1360 you are a distro, do not.
1361
1362 config DEBUG_RWSEMS
1363 bool "RW Semaphore debugging: basic checks"
1364 depends on DEBUG_KERNEL
1365 help
1366 This debugging feature allows mismatched rw semaphore locks
1367 and unlocks to be detected and reported.
1368
1369 config DEBUG_LOCK_ALLOC
1370 bool "Lock debugging: detect incorrect freeing of live locks"
1371 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1372 select DEBUG_SPINLOCK
1373 select DEBUG_MUTEXES if !PREEMPT_RT
1374 select DEBUG_RT_MUTEXES if RT_MUTEXES
1375 select LOCKDEP
1376 help
1377 This feature will check whether any held lock (spinlock, rwlock,
1378 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1379 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1380 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1381 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1382 held during task exit.
1383
1384 config LOCKDEP
1385 bool
1386 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1387 select STACKTRACE
1388 select KALLSYMS
1389 select KALLSYMS_ALL
1390
1391 config LOCKDEP_SMALL
1392 bool
1393
1394 config LOCKDEP_BITS
1395 int "Bitsize for MAX_LOCKDEP_ENTRIES"
1396 depends on LOCKDEP && !LOCKDEP_SMALL
1397 range 10 30
1398 default 15
1399 help
1400 Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message.
1401
1402 config LOCKDEP_CHAINS_BITS
1403 int "Bitsize for MAX_LOCKDEP_CHAINS"
1404 depends on LOCKDEP && !LOCKDEP_SMALL
1405 range 10 30
1406 default 16
1407 help
1408 Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message.
1409
1410 config LOCKDEP_STACK_TRACE_BITS
1411 int "Bitsize for MAX_STACK_TRACE_ENTRIES"
1412 depends on LOCKDEP && !LOCKDEP_SMALL
1413 range 10 30
1414 default 19
1415 help
1416 Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message.
1417
1418 config LOCKDEP_STACK_TRACE_HASH_BITS
1419 int "Bitsize for STACK_TRACE_HASH_SIZE"
1420 depends on LOCKDEP && !LOCKDEP_SMALL
1421 range 10 30
1422 default 14
1423 help
1424 Try increasing this value if you need large MAX_STACK_TRACE_ENTRIES.
1425
1426 config LOCKDEP_CIRCULAR_QUEUE_BITS
1427 int "Bitsize for elements in circular_queue struct"
1428 depends on LOCKDEP
1429 range 10 30
1430 default 12
1431 help
1432 Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure.
1433
1434 config DEBUG_LOCKDEP
1435 bool "Lock dependency engine debugging"
1436 depends on DEBUG_KERNEL && LOCKDEP
1437 select DEBUG_IRQFLAGS
1438 help
1439 If you say Y here, the lock dependency engine will do
1440 additional runtime checks to debug itself, at the price
1441 of more runtime overhead.
1442
1443 config DEBUG_ATOMIC_SLEEP
1444 bool "Sleep inside atomic section checking"
1445 select PREEMPT_COUNT
1446 depends on DEBUG_KERNEL
1447 depends on !ARCH_NO_PREEMPT
1448 help
1449 If you say Y here, various routines which may sleep will become very
1450 noisy if they are called inside atomic sections: when a spinlock is
1451 held, inside an rcu read side critical section, inside preempt disabled
1452 sections, inside an interrupt, etc...
1453
1454 config DEBUG_LOCKING_API_SELFTESTS
1455 bool "Locking API boot-time self-tests"
1456 depends on DEBUG_KERNEL
1457 help
1458 Say Y here if you want the kernel to run a short self-test during
1459 bootup. The self-test checks whether common types of locking bugs
1460 are detected by debugging mechanisms or not. (if you disable
1461 lock debugging then those bugs won't be detected of course.)
1462 The following locking APIs are covered: spinlocks, rwlocks,
1463 mutexes and rwsems.
1464
1465 config LOCK_TORTURE_TEST
1466 tristate "torture tests for locking"
1467 depends on DEBUG_KERNEL
1468 select TORTURE_TEST
1469 help
1470 This option provides a kernel module that runs torture tests
1471 on kernel locking primitives. The kernel module may be built
1472 after the fact on the running kernel to be tested, if desired.
1473
1474 Say Y here if you want kernel locking-primitive torture tests
1475 to be built into the kernel.
1476 Say M if you want these torture tests to build as a module.
1477 Say N if you are unsure.
1478
1479 config WW_MUTEX_SELFTEST
1480 tristate "Wait/wound mutex selftests"
1481 help
1482 This option provides a kernel module that runs tests on the
1483 on the struct ww_mutex locking API.
1484
1485 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1486 with this test harness.
1487
1488 Say M if you want these self tests to build as a module.
1489 Say N if you are unsure.
1490
1491 config SCF_TORTURE_TEST
1492 tristate "torture tests for smp_call_function*()"
1493 depends on DEBUG_KERNEL
1494 select TORTURE_TEST
1495 help
1496 This option provides a kernel module that runs torture tests
1497 on the smp_call_function() family of primitives. The kernel
1498 module may be built after the fact on the running kernel to
1499 be tested, if desired.
1500
1501 config CSD_LOCK_WAIT_DEBUG
1502 bool "Debugging for csd_lock_wait(), called from smp_call_function*()"
1503 depends on DEBUG_KERNEL
1504 depends on 64BIT
1505 default n
1506 help
1507 This option enables debug prints when CPUs are slow to respond
1508 to the smp_call_function*() IPI wrappers. These debug prints
1509 include the IPI handler function currently executing (if any)
1510 and relevant stack traces.
1511
1512 endmenu # lock debugging
1513
1514 config TRACE_IRQFLAGS
1515 depends on TRACE_IRQFLAGS_SUPPORT
1516 bool
1517 help
1518 Enables hooks to interrupt enabling and disabling for
1519 either tracing or lock debugging.
1520
1521 config TRACE_IRQFLAGS_NMI
1522 def_bool y
1523 depends on TRACE_IRQFLAGS
1524 depends on TRACE_IRQFLAGS_NMI_SUPPORT
1525
1526 config DEBUG_IRQFLAGS
1527 bool "Debug IRQ flag manipulation"
1528 help
1529 Enables checks for potentially unsafe enabling or disabling of
1530 interrupts, such as calling raw_local_irq_restore() when interrupts
1531 are enabled.
1532
1533 config STACKTRACE
1534 bool "Stack backtrace support"
1535 depends on STACKTRACE_SUPPORT
1536 help
1537 This option causes the kernel to create a /proc/pid/stack for
1538 every process, showing its current stack trace.
1539 It is also used by various kernel debugging features that require
1540 stack trace generation.
1541
1542 config WARN_ALL_UNSEEDED_RANDOM
1543 bool "Warn for all uses of unseeded randomness"
1544 default n
1545 help
1546 Some parts of the kernel contain bugs relating to their use of
1547 cryptographically secure random numbers before it's actually possible
1548 to generate those numbers securely. This setting ensures that these
1549 flaws don't go unnoticed, by enabling a message, should this ever
1550 occur. This will allow people with obscure setups to know when things
1551 are going wrong, so that they might contact developers about fixing
1552 it.
1553
1554 Unfortunately, on some models of some architectures getting
1555 a fully seeded CRNG is extremely difficult, and so this can
1556 result in dmesg getting spammed for a surprisingly long
1557 time. This is really bad from a security perspective, and
1558 so architecture maintainers really need to do what they can
1559 to get the CRNG seeded sooner after the system is booted.
1560 However, since users cannot do anything actionable to
1561 address this, by default the kernel will issue only a single
1562 warning for the first use of unseeded randomness.
1563
1564 Say Y here if you want to receive warnings for all uses of
1565 unseeded randomness. This will be of use primarily for
1566 those developers interested in improving the security of
1567 Linux kernels running on their architecture (or
1568 subarchitecture).
1569
1570 config DEBUG_KOBJECT
1571 bool "kobject debugging"
1572 depends on DEBUG_KERNEL
1573 help
1574 If you say Y here, some extra kobject debugging messages will be sent
1575 to the syslog.
1576
1577 config DEBUG_KOBJECT_RELEASE
1578 bool "kobject release debugging"
1579 depends on DEBUG_OBJECTS_TIMERS
1580 help
1581 kobjects are reference counted objects. This means that their
1582 last reference count put is not predictable, and the kobject can
1583 live on past the point at which a driver decides to drop it's
1584 initial reference to the kobject gained on allocation. An
1585 example of this would be a struct device which has just been
1586 unregistered.
1587
1588 However, some buggy drivers assume that after such an operation,
1589 the memory backing the kobject can be immediately freed. This
1590 goes completely against the principles of a refcounted object.
1591
1592 If you say Y here, the kernel will delay the release of kobjects
1593 on the last reference count to improve the visibility of this
1594 kind of kobject release bug.
1595
1596 config HAVE_DEBUG_BUGVERBOSE
1597 bool
1598
1599 menu "Debug kernel data structures"
1600
1601 config DEBUG_LIST
1602 bool "Debug linked list manipulation"
1603 depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION
1604 help
1605 Enable this to turn on extended checks in the linked-list
1606 walking routines.
1607
1608 If unsure, say N.
1609
1610 config DEBUG_PLIST
1611 bool "Debug priority linked list manipulation"
1612 depends on DEBUG_KERNEL
1613 help
1614 Enable this to turn on extended checks in the priority-ordered
1615 linked-list (plist) walking routines. This checks the entire
1616 list multiple times during each manipulation.
1617
1618 If unsure, say N.
1619
1620 config DEBUG_SG
1621 bool "Debug SG table operations"
1622 depends on DEBUG_KERNEL
1623 help
1624 Enable this to turn on checks on scatter-gather tables. This can
1625 help find problems with drivers that do not properly initialize
1626 their sg tables.
1627
1628 If unsure, say N.
1629
1630 config DEBUG_NOTIFIERS
1631 bool "Debug notifier call chains"
1632 depends on DEBUG_KERNEL
1633 help
1634 Enable this to turn on sanity checking for notifier call chains.
1635 This is most useful for kernel developers to make sure that
1636 modules properly unregister themselves from notifier chains.
1637 This is a relatively cheap check but if you care about maximum
1638 performance, say N.
1639
1640 config BUG_ON_DATA_CORRUPTION
1641 bool "Trigger a BUG when data corruption is detected"
1642 select DEBUG_LIST
1643 help
1644 Select this option if the kernel should BUG when it encounters
1645 data corruption in kernel memory structures when they get checked
1646 for validity.
1647
1648 If unsure, say N.
1649
1650 endmenu
1651
1652 config DEBUG_CREDENTIALS
1653 bool "Debug credential management"
1654 depends on DEBUG_KERNEL
1655 help
1656 Enable this to turn on some debug checking for credential
1657 management. The additional code keeps track of the number of
1658 pointers from task_structs to any given cred struct, and checks to
1659 see that this number never exceeds the usage count of the cred
1660 struct.
1661
1662 Furthermore, if SELinux is enabled, this also checks that the
1663 security pointer in the cred struct is never seen to be invalid.
1664
1665 If unsure, say N.
1666
1667 source "kernel/rcu/Kconfig.debug"
1668
1669 config DEBUG_WQ_FORCE_RR_CPU
1670 bool "Force round-robin CPU selection for unbound work items"
1671 depends on DEBUG_KERNEL
1672 default n
1673 help
1674 Workqueue used to implicitly guarantee that work items queued
1675 without explicit CPU specified are put on the local CPU. This
1676 guarantee is no longer true and while local CPU is still
1677 preferred work items may be put on foreign CPUs. Kernel
1678 parameter "workqueue.debug_force_rr_cpu" is added to force
1679 round-robin CPU selection to flush out usages which depend on the
1680 now broken guarantee. This config option enables the debug
1681 feature by default. When enabled, memory and cache locality will
1682 be impacted.
1683
1684 config CPU_HOTPLUG_STATE_CONTROL
1685 bool "Enable CPU hotplug state control"
1686 depends on DEBUG_KERNEL
1687 depends on HOTPLUG_CPU
1688 default n
1689 help
1690 Allows to write steps between "offline" and "online" to the CPUs
1691 sysfs target file so states can be stepped granular. This is a debug
1692 option for now as the hotplug machinery cannot be stopped and
1693 restarted at arbitrary points yet.
1694
1695 Say N if your are unsure.
1696
1697 config LATENCYTOP
1698 bool "Latency measuring infrastructure"
1699 depends on DEBUG_KERNEL
1700 depends on STACKTRACE_SUPPORT
1701 depends on PROC_FS
1702 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
1703 select KALLSYMS
1704 select KALLSYMS_ALL
1705 select STACKTRACE
1706 select SCHEDSTATS
1707 help
1708 Enable this option if you want to use the LatencyTOP tool
1709 to find out which userspace is blocking on what kernel operations.
1710
1711 source "kernel/trace/Kconfig"
1712
1713 config PROVIDE_OHCI1394_DMA_INIT
1714 bool "Remote debugging over FireWire early on boot"
1715 depends on PCI && X86
1716 help
1717 If you want to debug problems which hang or crash the kernel early
1718 on boot and the crashing machine has a FireWire port, you can use
1719 this feature to remotely access the memory of the crashed machine
1720 over FireWire. This employs remote DMA as part of the OHCI1394
1721 specification which is now the standard for FireWire controllers.
1722
1723 With remote DMA, you can monitor the printk buffer remotely using
1724 firescope and access all memory below 4GB using fireproxy from gdb.
1725 Even controlling a kernel debugger is possible using remote DMA.
1726
1727 Usage:
1728
1729 If ohci1394_dma=early is used as boot parameter, it will initialize
1730 all OHCI1394 controllers which are found in the PCI config space.
1731
1732 As all changes to the FireWire bus such as enabling and disabling
1733 devices cause a bus reset and thereby disable remote DMA for all
1734 devices, be sure to have the cable plugged and FireWire enabled on
1735 the debugging host before booting the debug target for debugging.
1736
1737 This code (~1k) is freed after boot. By then, the firewire stack
1738 in charge of the OHCI-1394 controllers should be used instead.
1739
1740 See Documentation/core-api/debugging-via-ohci1394.rst for more information.
1741
1742 source "samples/Kconfig"
1743
1744 config ARCH_HAS_DEVMEM_IS_ALLOWED
1745 bool
1746
1747 config STRICT_DEVMEM
1748 bool "Filter access to /dev/mem"
1749 depends on MMU && DEVMEM
1750 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED
1751 default y if PPC || X86 || ARM64
1752 help
1753 If this option is disabled, you allow userspace (root) access to all
1754 of memory, including kernel and userspace memory. Accidental
1755 access to this is obviously disastrous, but specific access can
1756 be used by people debugging the kernel. Note that with PAT support
1757 enabled, even in this case there are restrictions on /dev/mem
1758 use due to the cache aliasing requirements.
1759
1760 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
1761 file only allows userspace access to PCI space and the BIOS code and
1762 data regions. This is sufficient for dosemu and X and all common
1763 users of /dev/mem.
1764
1765 If in doubt, say Y.
1766
1767 config IO_STRICT_DEVMEM
1768 bool "Filter I/O access to /dev/mem"
1769 depends on STRICT_DEVMEM
1770 help
1771 If this option is disabled, you allow userspace (root) access to all
1772 io-memory regardless of whether a driver is actively using that
1773 range. Accidental access to this is obviously disastrous, but
1774 specific access can be used by people debugging kernel drivers.
1775
1776 If this option is switched on, the /dev/mem file only allows
1777 userspace access to *idle* io-memory ranges (see /proc/iomem) This
1778 may break traditional users of /dev/mem (dosemu, legacy X, etc...)
1779 if the driver using a given range cannot be disabled.
1780
1781 If in doubt, say Y.
1782
1783 menu "$(SRCARCH) Debugging"
1784
1785 source "arch/$(SRCARCH)/Kconfig.debug"
1786
1787 endmenu
1788
1789 menu "Kernel Testing and Coverage"
1790
1791 source "lib/kunit/Kconfig"
1792
1793 config NOTIFIER_ERROR_INJECTION
1794 tristate "Notifier error injection"
1795 depends on DEBUG_KERNEL
1796 select DEBUG_FS
1797 help
1798 This option provides the ability to inject artificial errors to
1799 specified notifier chain callbacks. It is useful to test the error
1800 handling of notifier call chain failures.
1801
1802 Say N if unsure.
1803
1804 config PM_NOTIFIER_ERROR_INJECT
1805 tristate "PM notifier error injection module"
1806 depends on PM && NOTIFIER_ERROR_INJECTION
1807 default m if PM_DEBUG
1808 help
1809 This option provides the ability to inject artificial errors to
1810 PM notifier chain callbacks. It is controlled through debugfs
1811 interface /sys/kernel/debug/notifier-error-inject/pm
1812
1813 If the notifier call chain should be failed with some events
1814 notified, write the error code to "actions/<notifier event>/error".
1815
1816 Example: Inject PM suspend error (-12 = -ENOMEM)
1817
1818 # cd /sys/kernel/debug/notifier-error-inject/pm/
1819 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1820 # echo mem > /sys/power/state
1821 bash: echo: write error: Cannot allocate memory
1822
1823 To compile this code as a module, choose M here: the module will
1824 be called pm-notifier-error-inject.
1825
1826 If unsure, say N.
1827
1828 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1829 tristate "OF reconfig notifier error injection module"
1830 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1831 help
1832 This option provides the ability to inject artificial errors to
1833 OF reconfig notifier chain callbacks. It is controlled
1834 through debugfs interface under
1835 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1836
1837 If the notifier call chain should be failed with some events
1838 notified, write the error code to "actions/<notifier event>/error".
1839
1840 To compile this code as a module, choose M here: the module will
1841 be called of-reconfig-notifier-error-inject.
1842
1843 If unsure, say N.
1844
1845 config NETDEV_NOTIFIER_ERROR_INJECT
1846 tristate "Netdev notifier error injection module"
1847 depends on NET && NOTIFIER_ERROR_INJECTION
1848 help
1849 This option provides the ability to inject artificial errors to
1850 netdevice notifier chain callbacks. It is controlled through debugfs
1851 interface /sys/kernel/debug/notifier-error-inject/netdev
1852
1853 If the notifier call chain should be failed with some events
1854 notified, write the error code to "actions/<notifier event>/error".
1855
1856 Example: Inject netdevice mtu change error (-22 = -EINVAL)
1857
1858 # cd /sys/kernel/debug/notifier-error-inject/netdev
1859 # echo -22 > actions/NETDEV_CHANGEMTU/error
1860 # ip link set eth0 mtu 1024
1861 RTNETLINK answers: Invalid argument
1862
1863 To compile this code as a module, choose M here: the module will
1864 be called netdev-notifier-error-inject.
1865
1866 If unsure, say N.
1867
1868 config FUNCTION_ERROR_INJECTION
1869 def_bool y
1870 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
1871
1872 config FAULT_INJECTION
1873 bool "Fault-injection framework"
1874 depends on DEBUG_KERNEL
1875 help
1876 Provide fault-injection framework.
1877 For more details, see Documentation/fault-injection/.
1878
1879 config FAILSLAB
1880 bool "Fault-injection capability for kmalloc"
1881 depends on FAULT_INJECTION
1882 depends on SLAB || SLUB
1883 help
1884 Provide fault-injection capability for kmalloc.
1885
1886 config FAIL_PAGE_ALLOC
1887 bool "Fault-injection capability for alloc_pages()"
1888 depends on FAULT_INJECTION
1889 help
1890 Provide fault-injection capability for alloc_pages().
1891
1892 config FAULT_INJECTION_USERCOPY
1893 bool "Fault injection capability for usercopy functions"
1894 depends on FAULT_INJECTION
1895 help
1896 Provides fault-injection capability to inject failures
1897 in usercopy functions (copy_from_user(), get_user(), ...).
1898
1899 config FAIL_MAKE_REQUEST
1900 bool "Fault-injection capability for disk IO"
1901 depends on FAULT_INJECTION && BLOCK
1902 help
1903 Provide fault-injection capability for disk IO.
1904
1905 config FAIL_IO_TIMEOUT
1906 bool "Fault-injection capability for faking disk interrupts"
1907 depends on FAULT_INJECTION && BLOCK
1908 help
1909 Provide fault-injection capability on end IO handling. This
1910 will make the block layer "forget" an interrupt as configured,
1911 thus exercising the error handling.
1912
1913 Only works with drivers that use the generic timeout handling,
1914 for others it won't do anything.
1915
1916 config FAIL_FUTEX
1917 bool "Fault-injection capability for futexes"
1918 select DEBUG_FS
1919 depends on FAULT_INJECTION && FUTEX
1920 help
1921 Provide fault-injection capability for futexes.
1922
1923 config FAULT_INJECTION_DEBUG_FS
1924 bool "Debugfs entries for fault-injection capabilities"
1925 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1926 help
1927 Enable configuration of fault-injection capabilities via debugfs.
1928
1929 config FAIL_FUNCTION
1930 bool "Fault-injection capability for functions"
1931 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
1932 help
1933 Provide function-based fault-injection capability.
1934 This will allow you to override a specific function with a return
1935 with given return value. As a result, function caller will see
1936 an error value and have to handle it. This is useful to test the
1937 error handling in various subsystems.
1938
1939 config FAIL_MMC_REQUEST
1940 bool "Fault-injection capability for MMC IO"
1941 depends on FAULT_INJECTION_DEBUG_FS && MMC
1942 help
1943 Provide fault-injection capability for MMC IO.
1944 This will make the mmc core return data errors. This is
1945 useful to test the error handling in the mmc block device
1946 and to test how the mmc host driver handles retries from
1947 the block device.
1948
1949 config FAIL_SUNRPC
1950 bool "Fault-injection capability for SunRPC"
1951 depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG
1952 help
1953 Provide fault-injection capability for SunRPC and
1954 its consumers.
1955
1956 config FAULT_INJECTION_STACKTRACE_FILTER
1957 bool "stacktrace filter for fault-injection capabilities"
1958 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1959 depends on !X86_64
1960 select STACKTRACE
1961 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
1962 help
1963 Provide stacktrace filter for fault-injection capabilities
1964
1965 config ARCH_HAS_KCOV
1966 bool
1967 help
1968 An architecture should select this when it can successfully
1969 build and run with CONFIG_KCOV. This typically requires
1970 disabling instrumentation for some early boot code.
1971
1972 config CC_HAS_SANCOV_TRACE_PC
1973 def_bool $(cc-option,-fsanitize-coverage=trace-pc)
1974
1975
1976 config KCOV
1977 bool "Code coverage for fuzzing"
1978 depends on ARCH_HAS_KCOV
1979 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
1980 select DEBUG_FS
1981 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
1982 help
1983 KCOV exposes kernel code coverage information in a form suitable
1984 for coverage-guided fuzzing (randomized testing).
1985
1986 If RANDOMIZE_BASE is enabled, PC values will not be stable across
1987 different machines and across reboots. If you need stable PC values,
1988 disable RANDOMIZE_BASE.
1989
1990 For more details, see Documentation/dev-tools/kcov.rst.
1991
1992 config KCOV_ENABLE_COMPARISONS
1993 bool "Enable comparison operands collection by KCOV"
1994 depends on KCOV
1995 depends on $(cc-option,-fsanitize-coverage=trace-cmp)
1996 help
1997 KCOV also exposes operands of every comparison in the instrumented
1998 code along with operand sizes and PCs of the comparison instructions.
1999 These operands can be used by fuzzing engines to improve the quality
2000 of fuzzing coverage.
2001
2002 config KCOV_INSTRUMENT_ALL
2003 bool "Instrument all code by default"
2004 depends on KCOV
2005 default y
2006 help
2007 If you are doing generic system call fuzzing (like e.g. syzkaller),
2008 then you will want to instrument the whole kernel and you should
2009 say y here. If you are doing more targeted fuzzing (like e.g.
2010 filesystem fuzzing with AFL) then you will want to enable coverage
2011 for more specific subsets of files, and should say n here.
2012
2013 config KCOV_IRQ_AREA_SIZE
2014 hex "Size of interrupt coverage collection area in words"
2015 depends on KCOV
2016 default 0x40000
2017 help
2018 KCOV uses preallocated per-cpu areas to collect coverage from
2019 soft interrupts. This specifies the size of those areas in the
2020 number of unsigned long words.
2021
2022 menuconfig RUNTIME_TESTING_MENU
2023 bool "Runtime Testing"
2024 def_bool y
2025
2026 if RUNTIME_TESTING_MENU
2027
2028 config LKDTM
2029 tristate "Linux Kernel Dump Test Tool Module"
2030 depends on DEBUG_FS
2031 help
2032 This module enables testing of the different dumping mechanisms by
2033 inducing system failures at predefined crash points.
2034 If you don't need it: say N
2035 Choose M here to compile this code as a module. The module will be
2036 called lkdtm.
2037
2038 Documentation on how to use the module can be found in
2039 Documentation/fault-injection/provoke-crashes.rst
2040
2041 config TEST_LIST_SORT
2042 tristate "Linked list sorting test" if !KUNIT_ALL_TESTS
2043 depends on KUNIT
2044 default KUNIT_ALL_TESTS
2045 help
2046 Enable this to turn on 'list_sort()' function test. This test is
2047 executed only once during system boot (so affects only boot time),
2048 or at module load time.
2049
2050 If unsure, say N.
2051
2052 config TEST_MIN_HEAP
2053 tristate "Min heap test"
2054 depends on DEBUG_KERNEL || m
2055 help
2056 Enable this to turn on min heap function tests. This test is
2057 executed only once during system boot (so affects only boot time),
2058 or at module load time.
2059
2060 If unsure, say N.
2061
2062 config TEST_SORT
2063 tristate "Array-based sort test" if !KUNIT_ALL_TESTS
2064 depends on KUNIT
2065 default KUNIT_ALL_TESTS
2066 help
2067 This option enables the self-test function of 'sort()' at boot,
2068 or at module load time.
2069
2070 If unsure, say N.
2071
2072 config TEST_DIV64
2073 tristate "64bit/32bit division and modulo test"
2074 depends on DEBUG_KERNEL || m
2075 help
2076 Enable this to turn on 'do_div()' function test. This test is
2077 executed only once during system boot (so affects only boot time),
2078 or at module load time.
2079
2080 If unsure, say N.
2081
2082 config KPROBES_SANITY_TEST
2083 bool "Kprobes sanity tests"
2084 depends on DEBUG_KERNEL
2085 depends on KPROBES
2086 help
2087 This option provides for testing basic kprobes functionality on
2088 boot. Samples of kprobe and kretprobe are inserted and
2089 verified for functionality.
2090
2091 Say N if you are unsure.
2092
2093 config BACKTRACE_SELF_TEST
2094 tristate "Self test for the backtrace code"
2095 depends on DEBUG_KERNEL
2096 help
2097 This option provides a kernel module that can be used to test
2098 the kernel stack backtrace code. This option is not useful
2099 for distributions or general kernels, but only for kernel
2100 developers working on architecture code.
2101
2102 Note that if you want to also test saved backtraces, you will
2103 have to enable STACKTRACE as well.
2104
2105 Say N if you are unsure.
2106
2107 config RBTREE_TEST
2108 tristate "Red-Black tree test"
2109 depends on DEBUG_KERNEL
2110 help
2111 A benchmark measuring the performance of the rbtree library.
2112 Also includes rbtree invariant checks.
2113
2114 config REED_SOLOMON_TEST
2115 tristate "Reed-Solomon library test"
2116 depends on DEBUG_KERNEL || m
2117 select REED_SOLOMON
2118 select REED_SOLOMON_ENC16
2119 select REED_SOLOMON_DEC16
2120 help
2121 This option enables the self-test function of rslib at boot,
2122 or at module load time.
2123
2124 If unsure, say N.
2125
2126 config INTERVAL_TREE_TEST
2127 tristate "Interval tree test"
2128 depends on DEBUG_KERNEL
2129 select INTERVAL_TREE
2130 help
2131 A benchmark measuring the performance of the interval tree library
2132
2133 config PERCPU_TEST
2134 tristate "Per cpu operations test"
2135 depends on m && DEBUG_KERNEL
2136 help
2137 Enable this option to build test module which validates per-cpu
2138 operations.
2139
2140 If unsure, say N.
2141
2142 config ATOMIC64_SELFTEST
2143 tristate "Perform an atomic64_t self-test"
2144 help
2145 Enable this option to test the atomic64_t functions at boot or
2146 at module load time.
2147
2148 If unsure, say N.
2149
2150 config ASYNC_RAID6_TEST
2151 tristate "Self test for hardware accelerated raid6 recovery"
2152 depends on ASYNC_RAID6_RECOV
2153 select ASYNC_MEMCPY
2154 help
2155 This is a one-shot self test that permutes through the
2156 recovery of all the possible two disk failure scenarios for a
2157 N-disk array. Recovery is performed with the asynchronous
2158 raid6 recovery routines, and will optionally use an offload
2159 engine if one is available.
2160
2161 If unsure, say N.
2162
2163 config TEST_HEXDUMP
2164 tristate "Test functions located in the hexdump module at runtime"
2165
2166 config STRING_SELFTEST
2167 tristate "Test string functions at runtime"
2168
2169 config TEST_STRING_HELPERS
2170 tristate "Test functions located in the string_helpers module at runtime"
2171
2172 config TEST_STRSCPY
2173 tristate "Test strscpy*() family of functions at runtime"
2174
2175 config TEST_KSTRTOX
2176 tristate "Test kstrto*() family of functions at runtime"
2177
2178 config TEST_PRINTF
2179 tristate "Test printf() family of functions at runtime"
2180
2181 config TEST_SCANF
2182 tristate "Test scanf() family of functions at runtime"
2183
2184 config TEST_BITMAP
2185 tristate "Test bitmap_*() family of functions at runtime"
2186 help
2187 Enable this option to test the bitmap functions at boot.
2188
2189 If unsure, say N.
2190
2191 config TEST_UUID
2192 tristate "Test functions located in the uuid module at runtime"
2193
2194 config TEST_XARRAY
2195 tristate "Test the XArray code at runtime"
2196
2197 config TEST_OVERFLOW
2198 tristate "Test check_*_overflow() functions at runtime"
2199
2200 config TEST_RHASHTABLE
2201 tristate "Perform selftest on resizable hash table"
2202 help
2203 Enable this option to test the rhashtable functions at boot.
2204
2205 If unsure, say N.
2206
2207 config TEST_HASH
2208 tristate "Perform selftest on hash functions"
2209 help
2210 Enable this option to test the kernel's integer (<linux/hash.h>),
2211 string (<linux/stringhash.h>), and siphash (<linux/siphash.h>)
2212 hash functions on boot (or module load).
2213
2214 This is intended to help people writing architecture-specific
2215 optimized versions. If unsure, say N.
2216
2217 config TEST_IDA
2218 tristate "Perform selftest on IDA functions"
2219
2220 config TEST_PARMAN
2221 tristate "Perform selftest on priority array manager"
2222 depends on PARMAN
2223 help
2224 Enable this option to test priority array manager on boot
2225 (or module load).
2226
2227 If unsure, say N.
2228
2229 config TEST_IRQ_TIMINGS
2230 bool "IRQ timings selftest"
2231 depends on IRQ_TIMINGS
2232 help
2233 Enable this option to test the irq timings code on boot.
2234
2235 If unsure, say N.
2236
2237 config TEST_LKM
2238 tristate "Test module loading with 'hello world' module"
2239 depends on m
2240 help
2241 This builds the "test_module" module that emits "Hello, world"
2242 on printk when loaded. It is designed to be used for basic
2243 evaluation of the module loading subsystem (for example when
2244 validating module verification). It lacks any extra dependencies,
2245 and will not normally be loaded by the system unless explicitly
2246 requested by name.
2247
2248 If unsure, say N.
2249
2250 config TEST_BITOPS
2251 tristate "Test module for compilation of bitops operations"
2252 depends on m
2253 help
2254 This builds the "test_bitops" module that is much like the
2255 TEST_LKM module except that it does a basic exercise of the
2256 set/clear_bit macros and get_count_order/long to make sure there are
2257 no compiler warnings from C=1 sparse checker or -Wextra
2258 compilations. It has no dependencies and doesn't run or load unless
2259 explicitly requested by name. for example: modprobe test_bitops.
2260
2261 If unsure, say N.
2262
2263 config TEST_VMALLOC
2264 tristate "Test module for stress/performance analysis of vmalloc allocator"
2265 default n
2266 depends on MMU
2267 depends on m
2268 help
2269 This builds the "test_vmalloc" module that should be used for
2270 stress and performance analysis. So, any new change for vmalloc
2271 subsystem can be evaluated from performance and stability point
2272 of view.
2273
2274 If unsure, say N.
2275
2276 config TEST_USER_COPY
2277 tristate "Test user/kernel boundary protections"
2278 depends on m
2279 help
2280 This builds the "test_user_copy" module that runs sanity checks
2281 on the copy_to/from_user infrastructure, making sure basic
2282 user/kernel boundary testing is working. If it fails to load,
2283 a regression has been detected in the user/kernel memory boundary
2284 protections.
2285
2286 If unsure, say N.
2287
2288 config TEST_BPF
2289 tristate "Test BPF filter functionality"
2290 depends on m && NET
2291 help
2292 This builds the "test_bpf" module that runs various test vectors
2293 against the BPF interpreter or BPF JIT compiler depending on the
2294 current setting. This is in particular useful for BPF JIT compiler
2295 development, but also to run regression tests against changes in
2296 the interpreter code. It also enables test stubs for eBPF maps and
2297 verifier used by user space verifier testsuite.
2298
2299 If unsure, say N.
2300
2301 config TEST_BLACKHOLE_DEV
2302 tristate "Test blackhole netdev functionality"
2303 depends on m && NET
2304 help
2305 This builds the "test_blackhole_dev" module that validates the
2306 data path through this blackhole netdev.
2307
2308 If unsure, say N.
2309
2310 config FIND_BIT_BENCHMARK
2311 tristate "Test find_bit functions"
2312 help
2313 This builds the "test_find_bit" module that measure find_*_bit()
2314 functions performance.
2315
2316 If unsure, say N.
2317
2318 config TEST_FIRMWARE
2319 tristate "Test firmware loading via userspace interface"
2320 depends on FW_LOADER
2321 help
2322 This builds the "test_firmware" module that creates a userspace
2323 interface for testing firmware loading. This can be used to
2324 control the triggering of firmware loading without needing an
2325 actual firmware-using device. The contents can be rechecked by
2326 userspace.
2327
2328 If unsure, say N.
2329
2330 config TEST_SYSCTL
2331 tristate "sysctl test driver"
2332 depends on PROC_SYSCTL
2333 help
2334 This builds the "test_sysctl" module. This driver enables to test the
2335 proc sysctl interfaces available to drivers safely without affecting
2336 production knobs which might alter system functionality.
2337
2338 If unsure, say N.
2339
2340 config BITFIELD_KUNIT
2341 tristate "KUnit test bitfield functions at runtime"
2342 depends on KUNIT
2343 help
2344 Enable this option to test the bitfield functions at boot.
2345
2346 KUnit tests run during boot and output the results to the debug log
2347 in TAP format (http://testanything.org/). Only useful for kernel devs
2348 running the KUnit test harness, and not intended for inclusion into a
2349 production build.
2350
2351 For more information on KUnit and unit tests in general please refer
2352 to the KUnit documentation in Documentation/dev-tools/kunit/.
2353
2354 If unsure, say N.
2355
2356 config RESOURCE_KUNIT_TEST
2357 tristate "KUnit test for resource API"
2358 depends on KUNIT
2359 help
2360 This builds the resource API unit test.
2361 Tests the logic of API provided by resource.c and ioport.h.
2362 For more information on KUnit and unit tests in general please refer
2363 to the KUnit documentation in Documentation/dev-tools/kunit/.
2364
2365 If unsure, say N.
2366
2367 config SYSCTL_KUNIT_TEST
2368 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS
2369 depends on KUNIT
2370 default KUNIT_ALL_TESTS
2371 help
2372 This builds the proc sysctl unit test, which runs on boot.
2373 Tests the API contract and implementation correctness of sysctl.
2374 For more information on KUnit and unit tests in general please refer
2375 to the KUnit documentation in Documentation/dev-tools/kunit/.
2376
2377 If unsure, say N.
2378
2379 config LIST_KUNIT_TEST
2380 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS
2381 depends on KUNIT
2382 default KUNIT_ALL_TESTS
2383 help
2384 This builds the linked list KUnit test suite.
2385 It tests that the API and basic functionality of the list_head type
2386 and associated macros.
2387
2388 KUnit tests run during boot and output the results to the debug log
2389 in TAP format (https://testanything.org/). Only useful for kernel devs
2390 running the KUnit test harness, and not intended for inclusion into a
2391 production build.
2392
2393 For more information on KUnit and unit tests in general please refer
2394 to the KUnit documentation in Documentation/dev-tools/kunit/.
2395
2396 If unsure, say N.
2397
2398 config LINEAR_RANGES_TEST
2399 tristate "KUnit test for linear_ranges"
2400 depends on KUNIT
2401 select LINEAR_RANGES
2402 help
2403 This builds the linear_ranges unit test, which runs on boot.
2404 Tests the linear_ranges logic correctness.
2405 For more information on KUnit and unit tests in general please refer
2406 to the KUnit documentation in Documentation/dev-tools/kunit/.
2407
2408 If unsure, say N.
2409
2410 config CMDLINE_KUNIT_TEST
2411 tristate "KUnit test for cmdline API"
2412 depends on KUNIT
2413 help
2414 This builds the cmdline API unit test.
2415 Tests the logic of API provided by cmdline.c.
2416 For more information on KUnit and unit tests in general please refer
2417 to the KUnit documentation in Documentation/dev-tools/kunit/.
2418
2419 If unsure, say N.
2420
2421 config BITS_TEST
2422 tristate "KUnit test for bits.h"
2423 depends on KUNIT
2424 help
2425 This builds the bits unit test.
2426 Tests the logic of macros defined in bits.h.
2427 For more information on KUnit and unit tests in general please refer
2428 to the KUnit documentation in Documentation/dev-tools/kunit/.
2429
2430 If unsure, say N.
2431
2432 config SLUB_KUNIT_TEST
2433 tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS
2434 depends on SLUB_DEBUG && KUNIT
2435 default KUNIT_ALL_TESTS
2436 help
2437 This builds SLUB allocator unit test.
2438 Tests SLUB cache debugging functionality.
2439 For more information on KUnit and unit tests in general please refer
2440 to the KUnit documentation in Documentation/dev-tools/kunit/.
2441
2442 If unsure, say N.
2443
2444 config RATIONAL_KUNIT_TEST
2445 tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS
2446 depends on KUNIT && RATIONAL
2447 default KUNIT_ALL_TESTS
2448 help
2449 This builds the rational math unit test.
2450 For more information on KUnit and unit tests in general please refer
2451 to the KUnit documentation in Documentation/dev-tools/kunit/.
2452
2453 If unsure, say N.
2454
2455 config TEST_UDELAY
2456 tristate "udelay test driver"
2457 help
2458 This builds the "udelay_test" module that helps to make sure
2459 that udelay() is working properly.
2460
2461 If unsure, say N.
2462
2463 config TEST_STATIC_KEYS
2464 tristate "Test static keys"
2465 depends on m
2466 help
2467 Test the static key interfaces.
2468
2469 If unsure, say N.
2470
2471 config TEST_KMOD
2472 tristate "kmod stress tester"
2473 depends on m
2474 depends on NETDEVICES && NET_CORE && INET # for TUN
2475 depends on BLOCK
2476 select TEST_LKM
2477 select XFS_FS
2478 select TUN
2479 select BTRFS_FS
2480 help
2481 Test the kernel's module loading mechanism: kmod. kmod implements
2482 support to load modules using the Linux kernel's usermode helper.
2483 This test provides a series of tests against kmod.
2484
2485 Although technically you can either build test_kmod as a module or
2486 into the kernel we disallow building it into the kernel since
2487 it stress tests request_module() and this will very likely cause
2488 some issues by taking over precious threads available from other
2489 module load requests, ultimately this could be fatal.
2490
2491 To run tests run:
2492
2493 tools/testing/selftests/kmod/kmod.sh --help
2494
2495 If unsure, say N.
2496
2497 config TEST_DEBUG_VIRTUAL
2498 tristate "Test CONFIG_DEBUG_VIRTUAL feature"
2499 depends on DEBUG_VIRTUAL
2500 help
2501 Test the kernel's ability to detect incorrect calls to
2502 virt_to_phys() done against the non-linear part of the
2503 kernel's virtual address map.
2504
2505 If unsure, say N.
2506
2507 config TEST_MEMCAT_P
2508 tristate "Test memcat_p() helper function"
2509 help
2510 Test the memcat_p() helper for correctly merging two
2511 pointer arrays together.
2512
2513 If unsure, say N.
2514
2515 config TEST_LIVEPATCH
2516 tristate "Test livepatching"
2517 default n
2518 depends on DYNAMIC_DEBUG
2519 depends on LIVEPATCH
2520 depends on m
2521 help
2522 Test kernel livepatching features for correctness. The tests will
2523 load test modules that will be livepatched in various scenarios.
2524
2525 To run all the livepatching tests:
2526
2527 make -C tools/testing/selftests TARGETS=livepatch run_tests
2528
2529 Alternatively, individual tests may be invoked:
2530
2531 tools/testing/selftests/livepatch/test-callbacks.sh
2532 tools/testing/selftests/livepatch/test-livepatch.sh
2533 tools/testing/selftests/livepatch/test-shadow-vars.sh
2534
2535 If unsure, say N.
2536
2537 config TEST_OBJAGG
2538 tristate "Perform selftest on object aggreration manager"
2539 default n
2540 depends on OBJAGG
2541 help
2542 Enable this option to test object aggregation manager on boot
2543 (or module load).
2544
2545
2546 config TEST_STACKINIT
2547 tristate "Test level of stack variable initialization"
2548 help
2549 Test if the kernel is zero-initializing stack variables and
2550 padding. Coverage is controlled by compiler flags,
2551 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2552 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2553
2554 If unsure, say N.
2555
2556 config TEST_MEMINIT
2557 tristate "Test heap/page initialization"
2558 help
2559 Test if the kernel is zero-initializing heap and page allocations.
2560 This can be useful to test init_on_alloc and init_on_free features.
2561
2562 If unsure, say N.
2563
2564 config TEST_HMM
2565 tristate "Test HMM (Heterogeneous Memory Management)"
2566 depends on TRANSPARENT_HUGEPAGE
2567 depends on DEVICE_PRIVATE
2568 select HMM_MIRROR
2569 select MMU_NOTIFIER
2570 help
2571 This is a pseudo device driver solely for testing HMM.
2572 Say M here if you want to build the HMM test module.
2573 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests.
2574
2575 If unsure, say N.
2576
2577 config TEST_FREE_PAGES
2578 tristate "Test freeing pages"
2579 help
2580 Test that a memory leak does not occur due to a race between
2581 freeing a block of pages and a speculative page reference.
2582 Loading this module is safe if your kernel has the bug fixed.
2583 If the bug is not fixed, it will leak gigabytes of memory and
2584 probably OOM your system.
2585
2586 config TEST_FPU
2587 tristate "Test floating point operations in kernel space"
2588 depends on X86 && !KCOV_INSTRUMENT_ALL
2589 help
2590 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu
2591 which will trigger a sequence of floating point operations. This is used
2592 for self-testing floating point control register setting in
2593 kernel_fpu_begin().
2594
2595 If unsure, say N.
2596
2597 config TEST_CLOCKSOURCE_WATCHDOG
2598 tristate "Test clocksource watchdog in kernel space"
2599 depends on CLOCKSOURCE_WATCHDOG
2600 help
2601 Enable this option to create a kernel module that will trigger
2602 a test of the clocksource watchdog. This module may be loaded
2603 via modprobe or insmod in which case it will run upon being
2604 loaded, or it may be built in, in which case it will run
2605 shortly after boot.
2606
2607 If unsure, say N.
2608
2609 endif # RUNTIME_TESTING_MENU
2610
2611 config ARCH_USE_MEMTEST
2612 bool
2613 help
2614 An architecture should select this when it uses early_memtest()
2615 during boot process.
2616
2617 config MEMTEST
2618 bool "Memtest"
2619 depends on ARCH_USE_MEMTEST
2620 help
2621 This option adds a kernel parameter 'memtest', which allows memtest
2622 to be set and executed.
2623 memtest=0, mean disabled; -- default
2624 memtest=1, mean do 1 test pattern;
2625 ...
2626 memtest=17, mean do 17 test patterns.
2627 If you are unsure how to answer this question, answer N.
2628
2629
2630
2631 config HYPERV_TESTING
2632 bool "Microsoft Hyper-V driver testing"
2633 default n
2634 depends on HYPERV && DEBUG_FS
2635 help
2636 Select this option to enable Hyper-V vmbus testing.
2637
2638 endmenu # "Kernel Testing and Coverage"
2639
2640 source "Documentation/Kconfig"
2641
2642 endmenu # Kernel hacking