| blob | 7937265ef8797b68047218a60631dd5db5646333 |
1 # SPDX-License-Identifier: GPL-2.0-only
2 menu "Kernel hacking"
4 menu "printk and dmesg options"
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.
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.
18 The behavior is also controlled by the kernel command line
19 parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst
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.
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.
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.
38 config CONSOLE_LOGLEVEL_DEFAULT
39 int "Default console loglevel (1-15)"
40 range 1 15
41 default "7"
42 help
43 Default loglevel to determine what will be printed on the console.
45 Setting a default here is equivalent to passing in loglevel=<x> in
46 the kernel bootargs. loglevel=<x> continues to override whatever
47 value is specified here as well.
49 Note: This does not affect the log level of un-prefixed printk()
50 usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT
51 option.
53 config CONSOLE_LOGLEVEL_QUIET
54 int "quiet console loglevel (1-15)"
55 range 1 15
56 default "4"
57 help
58 loglevel to use when "quiet" is passed on the kernel commandline.
60 When "quiet" is passed on the kernel commandline this loglevel
61 will be used as the loglevel. IOW passing "quiet" will be the
62 equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>"
64 config MESSAGE_LOGLEVEL_DEFAULT
65 int "Default message log level (1-7)"
66 range 1 7
67 default "4"
68 help
69 Default log level for printk statements with no specified priority.
71 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
72 that are auditing their logs closely may want to set it to a lower
73 priority.
75 Note: This does not affect what message level gets printed on the console
76 by default. To change that, use loglevel=<x> in the kernel bootargs,
77 or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value.
79 config BOOT_PRINTK_DELAY
80 bool "Delay each boot printk message by N milliseconds"
81 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
82 help
83 This build option allows you to read kernel boot messages
84 by inserting a short delay after each one. The delay is
85 specified in milliseconds on the kernel command line,
86 using "boot_delay=N".
88 It is likely that you would also need to use "lpj=M" to preset
89 the "loops per jiffie" value.
90 See a previous boot log for the "lpj" value to use for your
91 system, and then set "lpj=M" before setting "boot_delay=N".
92 NOTE: Using this option may adversely affect SMP systems.
93 I.e., processors other than the first one may not boot up.
94 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
95 what it believes to be lockup conditions.
97 config DYNAMIC_DEBUG
98 bool "Enable dynamic printk() support"
99 default n
100 depends on PRINTK
101 depends on (DEBUG_FS || PROC_FS)
102 select DYNAMIC_DEBUG_CORE
103 help
105 Compiles debug level messages into the kernel, which would not
106 otherwise be available at runtime. These messages can then be
107 enabled/disabled based on various levels of scope - per source file,
108 function, module, format string, and line number. This mechanism
109 implicitly compiles in all pr_debug() and dev_dbg() calls, which
110 enlarges the kernel text size by about 2%.
112 If a source file is compiled with DEBUG flag set, any
113 pr_debug() calls in it are enabled by default, but can be
114 disabled at runtime as below. Note that DEBUG flag is
115 turned on by many CONFIG_*DEBUG* options.
117 Usage:
119 Dynamic debugging is controlled via the 'dynamic_debug/control' file,
120 which is contained in the 'debugfs' filesystem or procfs.
121 Thus, the debugfs or procfs filesystem must first be mounted before
122 making use of this feature.
123 We refer the control file as: <debugfs>/dynamic_debug/control. This
124 file contains a list of the debug statements that can be enabled. The
125 format for each line of the file is:
127 filename:lineno [module]function flags format
129 filename : source file of the debug statement
130 lineno : line number of the debug statement
131 module : module that contains the debug statement
132 function : function that contains the debug statement
133 flags : '=p' means the line is turned 'on' for printing
134 format : the format used for the debug statement
136 From a live system:
138 nullarbor:~ # cat <debugfs>/dynamic_debug/control
139 # filename:lineno [module]function flags format
140 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
141 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
142 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
144 Example usage:
146 // enable the message at line 1603 of file svcsock.c
147 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
148 <debugfs>/dynamic_debug/control
150 // enable all the messages in file svcsock.c
151 nullarbor:~ # echo -n 'file svcsock.c +p' >
152 <debugfs>/dynamic_debug/control
154 // enable all the messages in the NFS server module
155 nullarbor:~ # echo -n 'module nfsd +p' >
156 <debugfs>/dynamic_debug/control
158 // enable all 12 messages in the function svc_process()
159 nullarbor:~ # echo -n 'func svc_process +p' >
160 <debugfs>/dynamic_debug/control
162 // disable all 12 messages in the function svc_process()
163 nullarbor:~ # echo -n 'func svc_process -p' >
164 <debugfs>/dynamic_debug/control
166 See Documentation/admin-guide/dynamic-debug-howto.rst for additional
167 information.
169 config DYNAMIC_DEBUG_CORE
170 bool "Enable core function of dynamic debug support"
171 depends on PRINTK
172 depends on (DEBUG_FS || PROC_FS)
173 help
174 Enable core functional support of dynamic debug. It is useful
175 when you want to tie dynamic debug to your kernel modules with
176 DYNAMIC_DEBUG_MODULE defined for each of them, especially for
177 the case of embedded system where the kernel image size is
178 sensitive for people.
180 config SYMBOLIC_ERRNAME
181 bool "Support symbolic error names in printf"
182 default y if PRINTK
183 help
184 If you say Y here, the kernel's printf implementation will
185 be able to print symbolic error names such as ENOSPC instead
186 of the number 28. It makes the kernel image slightly larger
187 (about 3KB), but can make the kernel logs easier to read.
189 config DEBUG_BUGVERBOSE
190 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
191 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
192 default y
193 help
194 Say Y here to make BUG() panics output the file name and line number
195 of the BUG call as well as the EIP and oops trace. This aids
196 debugging but costs about 70-100K of memory.
198 endmenu # "printk and dmesg options"
200 menu "Compile-time checks and compiler options"
202 config DEBUG_INFO
203 bool "Compile the kernel with debug info"
204 depends on DEBUG_KERNEL && !COMPILE_TEST
205 help
206 If you say Y here the resulting kernel image will include
207 debugging info resulting in a larger kernel image.
208 This adds debug symbols to the kernel and modules (gcc -g), and
209 is needed if you intend to use kernel crashdump or binary object
210 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
211 Say Y here only if you plan to debug the kernel.
213 If unsure, say N.
215 if DEBUG_INFO
217 config DEBUG_INFO_REDUCED
218 bool "Reduce debugging information"
219 help
220 If you say Y here gcc is instructed to generate less debugging
221 information for structure types. This means that tools that
222 need full debugging information (like kgdb or systemtap) won't
223 be happy. But if you merely need debugging information to
224 resolve line numbers there is no loss. Advantage is that
225 build directory object sizes shrink dramatically over a full
226 DEBUG_INFO build and compile times are reduced too.
227 Only works with newer gcc versions.
229 config DEBUG_INFO_COMPRESSED
230 bool "Compressed debugging information"
231 depends on $(cc-option,-gz=zlib)
232 depends on $(ld-option,--compress-debug-sections=zlib)
233 help
234 Compress the debug information using zlib. Requires GCC 5.0+ or Clang
235 5.0+, binutils 2.26+, and zlib.
237 Users of dpkg-deb via scripts/package/builddeb may find an increase in
238 size of their debug .deb packages with this config set, due to the
239 debug info being compressed with zlib, then the object files being
240 recompressed with a different compression scheme. But this is still
241 preferable to setting $KDEB_COMPRESS to "none" which would be even
242 larger.
244 config DEBUG_INFO_SPLIT
245 bool "Produce split debuginfo in .dwo files"
246 depends on $(cc-option,-gsplit-dwarf)
247 help
248 Generate debug info into separate .dwo files. This significantly
249 reduces the build directory size for builds with DEBUG_INFO,
250 because it stores the information only once on disk in .dwo
251 files instead of multiple times in object files and executables.
252 In addition the debug information is also compressed.
254 Requires recent gcc (4.7+) and recent gdb/binutils.
255 Any tool that packages or reads debug information would need
256 to know about the .dwo files and include them.
257 Incompatible with older versions of ccache.
259 config DEBUG_INFO_DWARF4
260 bool "Generate dwarf4 debuginfo"
261 depends on $(cc-option,-gdwarf-4)
262 help
263 Generate dwarf4 debug info. This requires recent versions
264 of gcc and gdb. It makes the debug information larger.
265 But it significantly improves the success of resolving
266 variables in gdb on optimized code.
268 config DEBUG_INFO_BTF
269 bool "Generate BTF typeinfo"
270 depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED
271 depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST
272 help
273 Generate deduplicated BTF type information from DWARF debug info.
274 Turning this on expects presence of pahole tool, which will convert
275 DWARF type info into equivalent deduplicated BTF type info.
277 config PAHOLE_HAS_SPLIT_BTF
278 def_bool $(success, test `$(PAHOLE) --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/'` -ge "119")
280 config DEBUG_INFO_BTF_MODULES
281 def_bool y
282 depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF
283 help
284 Generate compact split BTF type information for kernel modules.
286 config GDB_SCRIPTS
287 bool "Provide GDB scripts for kernel debugging"
288 help
289 This creates the required links to GDB helper scripts in the
290 build directory. If you load vmlinux into gdb, the helper
291 scripts will be automatically imported by gdb as well, and
292 additional functions are available to analyze a Linux kernel
293 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
294 for further details.
296 endif # DEBUG_INFO
298 config FRAME_WARN
299 int "Warn for stack frames larger than"
300 range 0 8192
301 default 2048 if GCC_PLUGIN_LATENT_ENTROPY
302 default 1280 if (!64BIT && PARISC)
303 default 1024 if (!64BIT && !PARISC)
304 default 2048 if 64BIT
305 help
306 Tell gcc to warn at build time for stack frames larger than this.
307 Setting this too low will cause a lot of warnings.
308 Setting it to 0 disables the warning.
310 config STRIP_ASM_SYMS
311 bool "Strip assembler-generated symbols during link"
312 default n
313 help
314 Strip internal assembler-generated symbols during a link (symbols
315 that look like '.Lxxx') so they don't pollute the output of
316 get_wchan() and suchlike.
318 config READABLE_ASM
319 bool "Generate readable assembler code"
320 depends on DEBUG_KERNEL
321 help
322 Disable some compiler optimizations that tend to generate human unreadable
323 assembler output. This may make the kernel slightly slower, but it helps
324 to keep kernel developers who have to stare a lot at assembler listings
325 sane.
327 config HEADERS_INSTALL
328 bool "Install uapi headers to usr/include"
329 depends on !UML
330 help
331 This option will install uapi headers (headers exported to user-space)
332 into the usr/include directory for use during the kernel build.
333 This is unneeded for building the kernel itself, but needed for some
334 user-space program samples. It is also needed by some features such
335 as uapi header sanity checks.
337 config DEBUG_SECTION_MISMATCH
338 bool "Enable full Section mismatch analysis"
339 help
340 The section mismatch analysis checks if there are illegal
341 references from one section to another section.
342 During linktime or runtime, some sections are dropped;
343 any use of code/data previously in these sections would
344 most likely result in an oops.
345 In the code, functions and variables are annotated with
346 __init,, etc. (see the full list in include/linux/init.h),
347 which results in the code/data being placed in specific sections.
348 The section mismatch analysis is always performed after a full
349 kernel build, and enabling this option causes the following
350 additional step to occur:
351 - Add the option -fno-inline-functions-called-once to gcc commands.
352 When inlining a function annotated with __init in a non-init
353 function, we would lose the section information and thus
354 the analysis would not catch the illegal reference.
355 This option tells gcc to inline less (but it does result in
356 a larger kernel).
358 config SECTION_MISMATCH_WARN_ONLY
359 bool "Make section mismatch errors non-fatal"
360 default y
361 help
362 If you say N here, the build process will fail if there are any
363 section mismatch, instead of just throwing warnings.
365 If unsure, say Y.
367 config DEBUG_FORCE_FUNCTION_ALIGN_32B
368 bool "Force all function address 32B aligned" if EXPERT
369 help
370 There are cases that a commit from one domain changes the function
371 address alignment of other domains, and cause magic performance
372 bump (regression or improvement). Enable this option will help to
373 verify if the bump is caused by function alignment changes, while
374 it will slightly increase the kernel size and affect icache usage.
376 It is mainly for debug and performance tuning use.
378 #
379 # Select this config option from the architecture Kconfig, if it
380 # is preferred to always offer frame pointers as a config
381 # option on the architecture (regardless of KERNEL_DEBUG):
382 #
383 config ARCH_WANT_FRAME_POINTERS
384 bool
386 config FRAME_POINTER
387 bool "Compile the kernel with frame pointers"
388 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
389 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
390 help
391 If you say Y here the resulting kernel image will be slightly
392 larger and slower, but it gives very useful debugging information
393 in case of kernel bugs. (precise oopses/stacktraces/warnings)
395 config STACK_VALIDATION
396 bool "Compile-time stack metadata validation"
397 depends on HAVE_STACK_VALIDATION
398 default n
399 help
400 Add compile-time checks to validate stack metadata, including frame
401 pointers (if CONFIG_FRAME_POINTER is enabled). This helps ensure
402 that runtime stack traces are more reliable.
404 This is also a prerequisite for generation of ORC unwind data, which
405 is needed for CONFIG_UNWINDER_ORC.
407 For more information, see
408 tools/objtool/Documentation/stack-validation.txt.
410 config VMLINUX_VALIDATION
411 bool
412 depends on STACK_VALIDATION && DEBUG_ENTRY && !PARAVIRT
413 default y
415 config DEBUG_FORCE_WEAK_PER_CPU
416 bool "Force weak per-cpu definitions"
417 depends on DEBUG_KERNEL
418 help
419 s390 and alpha require percpu variables in modules to be
420 defined weak to work around addressing range issue which
421 puts the following two restrictions on percpu variable
422 definitions.
424 1. percpu symbols must be unique whether static or not
425 2. percpu variables can't be defined inside a function
427 To ensure that generic code follows the above rules, this
428 option forces all percpu variables to be defined as weak.
430 endmenu # "Compiler options"
432 menu "Generic Kernel Debugging Instruments"
434 config MAGIC_SYSRQ
435 bool "Magic SysRq key"
436 depends on !UML
437 help
438 If you say Y here, you will have some control over the system even
439 if the system crashes for example during kernel debugging (e.g., you
440 will be able to flush the buffer cache to disk, reboot the system
441 immediately or dump some status information). This is accomplished
442 by pressing various keys while holding SysRq (Alt+PrintScreen). It
443 also works on a serial console (on PC hardware at least), if you
444 send a BREAK and then within 5 seconds a command keypress. The
445 keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
446 Don't say Y unless you really know what this hack does.
448 config MAGIC_SYSRQ_DEFAULT_ENABLE
449 hex "Enable magic SysRq key functions by default"
450 depends on MAGIC_SYSRQ
451 default 0x1
452 help
453 Specifies which SysRq key functions are enabled by default.
454 This may be set to 1 or 0 to enable or disable them all, or
455 to a bitmask as described in Documentation/admin-guide/sysrq.rst.
457 config MAGIC_SYSRQ_SERIAL
458 bool "Enable magic SysRq key over serial"
459 depends on MAGIC_SYSRQ
460 default y
461 help
462 Many embedded boards have a disconnected TTL level serial which can
463 generate some garbage that can lead to spurious false sysrq detects.
464 This option allows you to decide whether you want to enable the
465 magic SysRq key.
467 config MAGIC_SYSRQ_SERIAL_SEQUENCE
468 string "Char sequence that enables magic SysRq over serial"
469 depends on MAGIC_SYSRQ_SERIAL
470 default ""
471 help
472 Specifies a sequence of characters that can follow BREAK to enable
473 SysRq on a serial console.
475 If unsure, leave an empty string and the option will not be enabled.
477 config DEBUG_FS
478 bool "Debug Filesystem"
479 help
480 debugfs is a virtual file system that kernel developers use to put
481 debugging files into. Enable this option to be able to read and
482 write to these files.
484 For detailed documentation on the debugfs API, see
485 Documentation/filesystems/.
487 If unsure, say N.
489 choice
490 prompt "Debugfs default access"
491 depends on DEBUG_FS
492 default DEBUG_FS_ALLOW_ALL
493 help
494 This selects the default access restrictions for debugfs.
495 It can be overridden with kernel command line option
496 debugfs=[on,no-mount,off]. The restrictions apply for API access
497 and filesystem registration.
499 config DEBUG_FS_ALLOW_ALL
500 bool "Access normal"
501 help
502 No restrictions apply. Both API and filesystem registration
503 is on. This is the normal default operation.
505 config DEBUG_FS_DISALLOW_MOUNT
506 bool "Do not register debugfs as filesystem"
507 help
508 The API is open but filesystem is not loaded. Clients can still do
509 their work and read with debug tools that do not need
510 debugfs filesystem.
512 config DEBUG_FS_ALLOW_NONE
513 bool "No access"
514 help
515 Access is off. Clients get -PERM when trying to create nodes in
516 debugfs tree and debugfs is not registered as a filesystem.
517 Client can then back-off or continue without debugfs access.
519 endchoice
521 source "lib/Kconfig.kgdb"
522 source "lib/Kconfig.ubsan"
523 source "lib/Kconfig.kcsan"
525 endmenu
527 config DEBUG_KERNEL
528 bool "Kernel debugging"
529 help
530 Say Y here if you are developing drivers or trying to debug and
531 identify kernel problems.
533 config DEBUG_MISC
534 bool "Miscellaneous debug code"
535 default DEBUG_KERNEL
536 depends on DEBUG_KERNEL
537 help
538 Say Y here if you need to enable miscellaneous debug code that should
539 be under a more specific debug option but isn't.
542 menu "Memory Debugging"
544 source "mm/Kconfig.debug"
546 config DEBUG_OBJECTS
547 bool "Debug object operations"
548 depends on DEBUG_KERNEL
549 help
550 If you say Y here, additional code will be inserted into the
551 kernel to track the life time of various objects and validate
552 the operations on those objects.
554 config DEBUG_OBJECTS_SELFTEST
555 bool "Debug objects selftest"
556 depends on DEBUG_OBJECTS
557 help
558 This enables the selftest of the object debug code.
560 config DEBUG_OBJECTS_FREE
561 bool "Debug objects in freed memory"
562 depends on DEBUG_OBJECTS
563 help
564 This enables checks whether a k/v free operation frees an area
565 which contains an object which has not been deactivated
566 properly. This can make kmalloc/kfree-intensive workloads
567 much slower.
569 config DEBUG_OBJECTS_TIMERS
570 bool "Debug timer objects"
571 depends on DEBUG_OBJECTS
572 help
573 If you say Y here, additional code will be inserted into the
574 timer routines to track the life time of timer objects and
575 validate the timer operations.
577 config DEBUG_OBJECTS_WORK
578 bool "Debug work objects"
579 depends on DEBUG_OBJECTS
580 help
581 If you say Y here, additional code will be inserted into the
582 work queue routines to track the life time of work objects and
583 validate the work operations.
585 config DEBUG_OBJECTS_RCU_HEAD
586 bool "Debug RCU callbacks objects"
587 depends on DEBUG_OBJECTS
588 help
589 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
591 config DEBUG_OBJECTS_PERCPU_COUNTER
592 bool "Debug percpu counter objects"
593 depends on DEBUG_OBJECTS
594 help
595 If you say Y here, additional code will be inserted into the
596 percpu counter routines to track the life time of percpu counter
597 objects and validate the percpu counter operations.
599 config DEBUG_OBJECTS_ENABLE_DEFAULT
600 int "debug_objects bootup default value (0-1)"
601 range 0 1
602 default "1"
603 depends on DEBUG_OBJECTS
604 help
605 Debug objects boot parameter default value
607 config DEBUG_SLAB
608 bool "Debug slab memory allocations"
609 depends on DEBUG_KERNEL && SLAB
610 help
611 Say Y here to have the kernel do limited verification on memory
612 allocation as well as poisoning memory on free to catch use of freed
613 memory. This can make kmalloc/kfree-intensive workloads much slower.
615 config SLUB_DEBUG_ON
616 bool "SLUB debugging on by default"
617 depends on SLUB && SLUB_DEBUG
618 default n
619 help
620 Boot with debugging on by default. SLUB boots by default with
621 the runtime debug capabilities switched off. Enabling this is
622 equivalent to specifying the "slub_debug" parameter on boot.
623 There is no support for more fine grained debug control like
624 possible with slub_debug=xxx. SLUB debugging may be switched
625 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
626 "slub_debug=-".
628 config SLUB_STATS
629 default n
630 bool "Enable SLUB performance statistics"
631 depends on SLUB && SYSFS
632 help
633 SLUB statistics are useful to debug SLUBs allocation behavior in
634 order find ways to optimize the allocator. This should never be
635 enabled for production use since keeping statistics slows down
636 the allocator by a few percentage points. The slabinfo command
637 supports the determination of the most active slabs to figure
638 out which slabs are relevant to a particular load.
639 Try running: slabinfo -DA
641 config HAVE_DEBUG_KMEMLEAK
642 bool
644 config DEBUG_KMEMLEAK
645 bool "Kernel memory leak detector"
646 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
647 select DEBUG_FS
648 select STACKTRACE if STACKTRACE_SUPPORT
649 select KALLSYMS
650 select CRC32
651 help
652 Say Y here if you want to enable the memory leak
653 detector. The memory allocation/freeing is traced in a way
654 similar to the Boehm's conservative garbage collector, the
655 difference being that the orphan objects are not freed but
656 only shown in /sys/kernel/debug/kmemleak. Enabling this
657 feature will introduce an overhead to memory
658 allocations. See Documentation/dev-tools/kmemleak.rst for more
659 details.
661 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
662 of finding leaks due to the slab objects poisoning.
664 In order to access the kmemleak file, debugfs needs to be
665 mounted (usually at /sys/kernel/debug).
667 config DEBUG_KMEMLEAK_MEM_POOL_SIZE
668 int "Kmemleak memory pool size"
669 depends on DEBUG_KMEMLEAK
670 range 200 1000000
671 default 16000
672 help
673 Kmemleak must track all the memory allocations to avoid
674 reporting false positives. Since memory may be allocated or
675 freed before kmemleak is fully initialised, use a static pool
676 of metadata objects to track such callbacks. After kmemleak is
677 fully initialised, this memory pool acts as an emergency one
678 if slab allocations fail.
680 config DEBUG_KMEMLEAK_TEST
681 tristate "Simple test for the kernel memory leak detector"
682 depends on DEBUG_KMEMLEAK && m
683 help
684 This option enables a module that explicitly leaks memory.
686 If unsure, say N.
688 config DEBUG_KMEMLEAK_DEFAULT_OFF
689 bool "Default kmemleak to off"
690 depends on DEBUG_KMEMLEAK
691 help
692 Say Y here to disable kmemleak by default. It can then be enabled
693 on the command line via kmemleak=on.
695 config DEBUG_KMEMLEAK_AUTO_SCAN
696 bool "Enable kmemleak auto scan thread on boot up"
697 default y
698 depends on DEBUG_KMEMLEAK
699 help
700 Depending on the cpu, kmemleak scan may be cpu intensive and can
701 stall user tasks at times. This option enables/disables automatic
702 kmemleak scan at boot up.
704 Say N here to disable kmemleak auto scan thread to stop automatic
705 scanning. Disabling this option disables automatic reporting of
706 memory leaks.
708 If unsure, say Y.
710 config DEBUG_STACK_USAGE
711 bool "Stack utilization instrumentation"
712 depends on DEBUG_KERNEL && !IA64
713 help
714 Enables the display of the minimum amount of free stack which each
715 task has ever had available in the sysrq-T and sysrq-P debug output.
717 This option will slow down process creation somewhat.
719 config SCHED_STACK_END_CHECK
720 bool "Detect stack corruption on calls to schedule()"
721 depends on DEBUG_KERNEL
722 default n
723 help
724 This option checks for a stack overrun on calls to schedule().
725 If the stack end location is found to be over written always panic as
726 the content of the corrupted region can no longer be trusted.
727 This is to ensure no erroneous behaviour occurs which could result in
728 data corruption or a sporadic crash at a later stage once the region
729 is examined. The runtime overhead introduced is minimal.
731 config ARCH_HAS_DEBUG_VM_PGTABLE
732 bool
733 help
734 An architecture should select this when it can successfully
735 build and run DEBUG_VM_PGTABLE.
737 config DEBUG_VM
738 bool "Debug VM"
739 depends on DEBUG_KERNEL
740 help
741 Enable this to turn on extended checks in the virtual-memory system
742 that may impact performance.
744 If unsure, say N.
746 config DEBUG_VM_VMACACHE
747 bool "Debug VMA caching"
748 depends on DEBUG_VM
749 help
750 Enable this to turn on VMA caching debug information. Doing so
751 can cause significant overhead, so only enable it in non-production
752 environments.
754 If unsure, say N.
756 config DEBUG_VM_RB
757 bool "Debug VM red-black trees"
758 depends on DEBUG_VM
759 help
760 Enable VM red-black tree debugging information and extra validations.
762 If unsure, say N.
764 config DEBUG_VM_PGFLAGS
765 bool "Debug page-flags operations"
766 depends on DEBUG_VM
767 help
768 Enables extra validation on page flags operations.
770 If unsure, say N.
772 config DEBUG_VM_PGTABLE
773 bool "Debug arch page table for semantics compliance"
774 depends on MMU
775 depends on ARCH_HAS_DEBUG_VM_PGTABLE
776 default y if DEBUG_VM
777 help
778 This option provides a debug method which can be used to test
779 architecture page table helper functions on various platforms in
780 verifying if they comply with expected generic MM semantics. This
781 will help architecture code in making sure that any changes or
782 new additions of these helpers still conform to expected
783 semantics of the generic MM. Platforms will have to opt in for
784 this through ARCH_HAS_DEBUG_VM_PGTABLE.
786 If unsure, say N.
788 config ARCH_HAS_DEBUG_VIRTUAL
789 bool
791 config DEBUG_VIRTUAL
792 bool "Debug VM translations"
793 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
794 help
795 Enable some costly sanity checks in virtual to page code. This can
796 catch mistakes with virt_to_page() and friends.
798 If unsure, say N.
800 config DEBUG_NOMMU_REGIONS
801 bool "Debug the global anon/private NOMMU mapping region tree"
802 depends on DEBUG_KERNEL && !MMU
803 help
804 This option causes the global tree of anonymous and private mapping
805 regions to be regularly checked for invalid topology.
807 config DEBUG_MEMORY_INIT
808 bool "Debug memory initialisation" if EXPERT
809 default !EXPERT
810 help
811 Enable this for additional checks during memory initialisation.
812 The sanity checks verify aspects of the VM such as the memory model
813 and other information provided by the architecture. Verbose
814 information will be printed at KERN_DEBUG loglevel depending
815 on the mminit_loglevel= command-line option.
817 If unsure, say Y
819 config MEMORY_NOTIFIER_ERROR_INJECT
820 tristate "Memory hotplug notifier error injection module"
821 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
822 help
823 This option provides the ability to inject artificial errors to
824 memory hotplug notifier chain callbacks. It is controlled through
825 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
827 If the notifier call chain should be failed with some events
828 notified, write the error code to "actions/<notifier event>/error".
830 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
832 # cd /sys/kernel/debug/notifier-error-inject/memory
833 # echo -12 > actions/MEM_GOING_OFFLINE/error
834 # echo offline > /sys/devices/system/memory/memoryXXX/state
835 bash: echo: write error: Cannot allocate memory
837 To compile this code as a module, choose M here: the module will
838 be called memory-notifier-error-inject.
840 If unsure, say N.
842 config DEBUG_PER_CPU_MAPS
843 bool "Debug access to per_cpu maps"
844 depends on DEBUG_KERNEL
845 depends on SMP
846 help
847 Say Y to verify that the per_cpu map being accessed has
848 been set up. This adds a fair amount of code to kernel memory
849 and decreases performance.
851 Say N if unsure.
853 config DEBUG_KMAP_LOCAL
854 bool "Debug kmap_local temporary mappings"
855 depends on DEBUG_KERNEL && KMAP_LOCAL
856 help
857 This option enables additional error checking for the kmap_local
858 infrastructure. Disable for production use.
860 config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
861 bool
863 config DEBUG_KMAP_LOCAL_FORCE_MAP
864 bool "Enforce kmap_local temporary mappings"
865 depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
866 select KMAP_LOCAL
867 select DEBUG_KMAP_LOCAL
868 help
869 This option enforces temporary mappings through the kmap_local
870 mechanism for non-highmem pages and on non-highmem systems.
871 Disable this for production systems!
873 config DEBUG_HIGHMEM
874 bool "Highmem debugging"
875 depends on DEBUG_KERNEL && HIGHMEM
876 select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
877 select DEBUG_KMAP_LOCAL
878 help
879 This option enables additional error checking for high memory
880 systems. Disable for production systems.
882 config HAVE_DEBUG_STACKOVERFLOW
883 bool
885 config DEBUG_STACKOVERFLOW
886 bool "Check for stack overflows"
887 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
888 help
889 Say Y here if you want to check for overflows of kernel, IRQ
890 and exception stacks (if your architecture uses them). This
891 option will show detailed messages if free stack space drops
892 below a certain limit.
894 These kinds of bugs usually occur when call-chains in the
895 kernel get too deep, especially when interrupts are
896 involved.
898 Use this in cases where you see apparently random memory
899 corruption, especially if it appears in 'struct thread_info'
901 If in doubt, say "N".
903 source "lib/Kconfig.kasan"
905 endmenu # "Memory Debugging"
907 config DEBUG_SHIRQ
908 bool "Debug shared IRQ handlers"
909 depends on DEBUG_KERNEL
910 help
911 Enable this to generate a spurious interrupt just before a shared
912 interrupt handler is deregistered (generating one when registering
913 is currently disabled). Drivers need to handle this correctly. Some
914 don't and need to be caught.
916 menu "Debug Oops, Lockups and Hangs"
918 config PANIC_ON_OOPS
919 bool "Panic on Oops"
920 help
921 Say Y here to enable the kernel to panic when it oopses. This
922 has the same effect as setting oops=panic on the kernel command
923 line.
925 This feature is useful to ensure that the kernel does not do
926 anything erroneous after an oops which could result in data
927 corruption or other issues.
929 Say N if unsure.
931 config PANIC_ON_OOPS_VALUE
932 int
933 range 0 1
934 default 0 if !PANIC_ON_OOPS
935 default 1 if PANIC_ON_OOPS
937 config PANIC_TIMEOUT
938 int "panic timeout"
939 default 0
940 help
941 Set the timeout value (in seconds) until a reboot occurs when
942 the kernel panics. If n = 0, then we wait forever. A timeout
943 value n > 0 will wait n seconds before rebooting, while a timeout
944 value n < 0 will reboot immediately.
946 config LOCKUP_DETECTOR
947 bool
949 config SOFTLOCKUP_DETECTOR
950 bool "Detect Soft Lockups"
951 depends on DEBUG_KERNEL && !S390
952 select LOCKUP_DETECTOR
953 help
954 Say Y here to enable the kernel to act as a watchdog to detect
955 soft lockups.
957 Softlockups are bugs that cause the kernel to loop in kernel
958 mode for more than 20 seconds, without giving other tasks a
959 chance to run. The current stack trace is displayed upon
960 detection and the system will stay locked up.
962 config BOOTPARAM_SOFTLOCKUP_PANIC
963 bool "Panic (Reboot) On Soft Lockups"
964 depends on SOFTLOCKUP_DETECTOR
965 help
966 Say Y here to enable the kernel to panic on "soft lockups",
967 which are bugs that cause the kernel to loop in kernel
968 mode for more than 20 seconds (configurable using the watchdog_thresh
969 sysctl), without giving other tasks a chance to run.
971 The panic can be used in combination with panic_timeout,
972 to cause the system to reboot automatically after a
973 lockup has been detected. This feature is useful for
974 high-availability systems that have uptime guarantees and
975 where a lockup must be resolved ASAP.
977 Say N if unsure.
979 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
980 int
981 depends on SOFTLOCKUP_DETECTOR
982 range 0 1
983 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
984 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
986 config HARDLOCKUP_DETECTOR_PERF
987 bool
988 select SOFTLOCKUP_DETECTOR
990 #
991 # Enables a timestamp based low pass filter to compensate for perf based
992 # hard lockup detection which runs too fast due to turbo modes.
993 #
994 config HARDLOCKUP_CHECK_TIMESTAMP
995 bool
997 #
998 # arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard
999 # lockup detector rather than the perf based detector.
1000 #
1001 config HARDLOCKUP_DETECTOR
1002 bool "Detect Hard Lockups"
1003 depends on DEBUG_KERNEL && !S390
1004 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH
1005 select LOCKUP_DETECTOR
1006 select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF
1007 select HARDLOCKUP_DETECTOR_ARCH if HAVE_HARDLOCKUP_DETECTOR_ARCH
1008 help
1009 Say Y here to enable the kernel to act as a watchdog to detect
1010 hard lockups.
1012 Hardlockups are bugs that cause the CPU to loop in kernel mode
1013 for more than 10 seconds, without letting other interrupts have a
1014 chance to run. The current stack trace is displayed upon detection
1015 and the system will stay locked up.
1017 config BOOTPARAM_HARDLOCKUP_PANIC
1018 bool "Panic (Reboot) On Hard Lockups"
1019 depends on HARDLOCKUP_DETECTOR
1020 help
1021 Say Y here to enable the kernel to panic on "hard lockups",
1022 which are bugs that cause the kernel to loop in kernel
1023 mode with interrupts disabled for more than 10 seconds (configurable
1024 using the watchdog_thresh sysctl).
1026 Say N if unsure.
1028 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
1029 int
1030 depends on HARDLOCKUP_DETECTOR
1031 range 0 1
1032 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
1033 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
1035 config DETECT_HUNG_TASK
1036 bool "Detect Hung Tasks"
1037 depends on DEBUG_KERNEL
1038 default SOFTLOCKUP_DETECTOR
1039 help
1040 Say Y here to enable the kernel to detect "hung tasks",
1041 which are bugs that cause the task to be stuck in
1042 uninterruptible "D" state indefinitely.
1044 When a hung task is detected, the kernel will print the
1045 current stack trace (which you should report), but the
1046 task will stay in uninterruptible state. If lockdep is
1047 enabled then all held locks will also be reported. This
1048 feature has negligible overhead.
1050 config DEFAULT_HUNG_TASK_TIMEOUT
1051 int "Default timeout for hung task detection (in seconds)"
1052 depends on DETECT_HUNG_TASK
1053 default 120
1054 help
1055 This option controls the default timeout (in seconds) used
1056 to determine when a task has become non-responsive and should
1057 be considered hung.
1059 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
1060 sysctl or by writing a value to
1061 /proc/sys/kernel/hung_task_timeout_secs.
1063 A timeout of 0 disables the check. The default is two minutes.
1064 Keeping the default should be fine in most cases.
1066 config BOOTPARAM_HUNG_TASK_PANIC
1067 bool "Panic (Reboot) On Hung Tasks"
1068 depends on DETECT_HUNG_TASK
1069 help
1070 Say Y here to enable the kernel to panic on "hung tasks",
1071 which are bugs that cause the kernel to leave a task stuck
1072 in uninterruptible "D" state.
1074 The panic can be used in combination with panic_timeout,
1075 to cause the system to reboot automatically after a
1076 hung task has been detected. This feature is useful for
1077 high-availability systems that have uptime guarantees and
1078 where a hung tasks must be resolved ASAP.
1080 Say N if unsure.
1082 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
1083 int
1084 depends on DETECT_HUNG_TASK
1085 range 0 1
1086 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
1087 default 1 if BOOTPARAM_HUNG_TASK_PANIC
1089 config WQ_WATCHDOG
1090 bool "Detect Workqueue Stalls"
1091 depends on DEBUG_KERNEL
1092 help
1093 Say Y here to enable stall detection on workqueues. If a
1094 worker pool doesn't make forward progress on a pending work
1095 item for over a given amount of time, 30s by default, a
1096 warning message is printed along with dump of workqueue
1097 state. This can be configured through kernel parameter
1098 "workqueue.watchdog_thresh" and its sysfs counterpart.
1100 config TEST_LOCKUP
1101 tristate "Test module to generate lockups"
1102 depends on m
1103 help
1104 This builds the "test_lockup" module that helps to make sure
1105 that watchdogs and lockup detectors are working properly.
1107 Depending on module parameters it could emulate soft or hard
1108 lockup, "hung task", or locking arbitrary lock for a long time.
1109 Also it could generate series of lockups with cooling-down periods.
1111 If unsure, say N.
1113 endmenu # "Debug lockups and hangs"
1115 menu "Scheduler Debugging"
1117 config SCHED_DEBUG
1118 bool "Collect scheduler debugging info"
1119 depends on DEBUG_KERNEL && PROC_FS
1120 default y
1121 help
1122 If you say Y here, the /proc/sched_debug file will be provided
1123 that can help debug the scheduler. The runtime overhead of this
1124 option is minimal.
1126 config SCHED_INFO
1127 bool
1128 default n
1130 config SCHEDSTATS
1131 bool "Collect scheduler statistics"
1132 depends on DEBUG_KERNEL && PROC_FS
1133 select SCHED_INFO
1134 help
1135 If you say Y here, additional code will be inserted into the
1136 scheduler and related routines to collect statistics about
1137 scheduler behavior and provide them in /proc/schedstat. These
1138 stats may be useful for both tuning and debugging the scheduler
1139 If you aren't debugging the scheduler or trying to tune a specific
1140 application, you can say N to avoid the very slight overhead
1141 this adds.
1143 endmenu
1145 config DEBUG_TIMEKEEPING
1146 bool "Enable extra timekeeping sanity checking"
1147 help
1148 This option will enable additional timekeeping sanity checks
1149 which may be helpful when diagnosing issues where timekeeping
1150 problems are suspected.
1152 This may include checks in the timekeeping hotpaths, so this
1153 option may have a (very small) performance impact to some
1154 workloads.
1156 If unsure, say N.
1158 config DEBUG_PREEMPT
1159 bool "Debug preemptible kernel"
1160 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT
1161 default y
1162 help
1163 If you say Y here then the kernel will use a debug variant of the
1164 commonly used smp_processor_id() function and will print warnings
1165 if kernel code uses it in a preemption-unsafe way. Also, the kernel
1166 will detect preemption count underflows.
1168 menu "Lock Debugging (spinlocks, mutexes, etc...)"
1170 config LOCK_DEBUGGING_SUPPORT
1171 bool
1172 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1173 default y
1175 config PROVE_LOCKING
1176 bool "Lock debugging: prove locking correctness"
1177 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1178 select LOCKDEP
1179 select DEBUG_SPINLOCK
1180 select DEBUG_MUTEXES
1181 select DEBUG_RT_MUTEXES if RT_MUTEXES
1182 select DEBUG_RWSEMS
1183 select DEBUG_WW_MUTEX_SLOWPATH
1184 select DEBUG_LOCK_ALLOC
1185 select PREEMPT_COUNT if !ARCH_NO_PREEMPT
1186 select TRACE_IRQFLAGS
1187 default n
1188 help
1189 This feature enables the kernel to prove that all locking
1190 that occurs in the kernel runtime is mathematically
1191 correct: that under no circumstance could an arbitrary (and
1192 not yet triggered) combination of observed locking
1193 sequences (on an arbitrary number of CPUs, running an
1194 arbitrary number of tasks and interrupt contexts) cause a
1195 deadlock.
1197 In short, this feature enables the kernel to report locking
1198 related deadlocks before they actually occur.
1200 The proof does not depend on how hard and complex a
1201 deadlock scenario would be to trigger: how many
1202 participant CPUs, tasks and irq-contexts would be needed
1203 for it to trigger. The proof also does not depend on
1204 timing: if a race and a resulting deadlock is possible
1205 theoretically (no matter how unlikely the race scenario
1206 is), it will be proven so and will immediately be
1207 reported by the kernel (once the event is observed that
1208 makes the deadlock theoretically possible).
1210 If a deadlock is impossible (i.e. the locking rules, as
1211 observed by the kernel, are mathematically correct), the
1212 kernel reports nothing.
1214 NOTE: this feature can also be enabled for rwlocks, mutexes
1215 and rwsems - in which case all dependencies between these
1216 different locking variants are observed and mapped too, and
1217 the proof of observed correctness is also maintained for an
1218 arbitrary combination of these separate locking variants.
1220 For more details, see Documentation/locking/lockdep-design.rst.
1222 config PROVE_RAW_LOCK_NESTING
1223 bool "Enable raw_spinlock - spinlock nesting checks"
1224 depends on PROVE_LOCKING
1225 default n
1226 help
1227 Enable the raw_spinlock vs. spinlock nesting checks which ensure
1228 that the lock nesting rules for PREEMPT_RT enabled kernels are
1229 not violated.
1231 NOTE: There are known nesting problems. So if you enable this
1232 option expect lockdep splats until these problems have been fully
1233 addressed which is work in progress. This config switch allows to
1234 identify and analyze these problems. It will be removed and the
1235 check permanentely enabled once the main issues have been fixed.
1237 If unsure, select N.
1239 config LOCK_STAT
1240 bool "Lock usage statistics"
1241 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1242 select LOCKDEP
1243 select DEBUG_SPINLOCK
1244 select DEBUG_MUTEXES
1245 select DEBUG_RT_MUTEXES if RT_MUTEXES
1246 select DEBUG_LOCK_ALLOC
1247 default n
1248 help
1249 This feature enables tracking lock contention points
1251 For more details, see Documentation/locking/lockstat.rst
1253 This also enables lock events required by "perf lock",
1254 subcommand of perf.
1255 If you want to use "perf lock", you also need to turn on
1256 CONFIG_EVENT_TRACING.
1258 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1259 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1261 config DEBUG_RT_MUTEXES
1262 bool "RT Mutex debugging, deadlock detection"
1263 depends on DEBUG_KERNEL && RT_MUTEXES
1264 help
1265 This allows rt mutex semantics violations and rt mutex related
1266 deadlocks (lockups) to be detected and reported automatically.
1268 config DEBUG_SPINLOCK
1269 bool "Spinlock and rw-lock debugging: basic checks"
1270 depends on DEBUG_KERNEL
1271 select UNINLINE_SPIN_UNLOCK
1272 help
1273 Say Y here and build SMP to catch missing spinlock initialization
1274 and certain other kinds of spinlock errors commonly made. This is
1275 best used in conjunction with the NMI watchdog so that spinlock
1276 deadlocks are also debuggable.
1278 config DEBUG_MUTEXES
1279 bool "Mutex debugging: basic checks"
1280 depends on DEBUG_KERNEL
1281 help
1282 This feature allows mutex semantics violations to be detected and
1283 reported.
1285 config DEBUG_WW_MUTEX_SLOWPATH
1286 bool "Wait/wound mutex debugging: Slowpath testing"
1287 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1288 select DEBUG_LOCK_ALLOC
1289 select DEBUG_SPINLOCK
1290 select DEBUG_MUTEXES
1291 help
1292 This feature enables slowpath testing for w/w mutex users by
1293 injecting additional -EDEADLK wound/backoff cases. Together with
1294 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1295 will test all possible w/w mutex interface abuse with the
1296 exception of simply not acquiring all the required locks.
1297 Note that this feature can introduce significant overhead, so
1298 it really should not be enabled in a production or distro kernel,
1299 even a debug kernel. If you are a driver writer, enable it. If
1300 you are a distro, do not.
1302 config DEBUG_RWSEMS
1303 bool "RW Semaphore debugging: basic checks"
1304 depends on DEBUG_KERNEL
1305 help
1306 This debugging feature allows mismatched rw semaphore locks
1307 and unlocks to be detected and reported.
1309 config DEBUG_LOCK_ALLOC
1310 bool "Lock debugging: detect incorrect freeing of live locks"
1311 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1312 select DEBUG_SPINLOCK
1313 select DEBUG_MUTEXES
1314 select DEBUG_RT_MUTEXES if RT_MUTEXES
1315 select LOCKDEP
1316 help
1317 This feature will check whether any held lock (spinlock, rwlock,
1318 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1319 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1320 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1321 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1322 held during task exit.
1324 config LOCKDEP
1325 bool
1326 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1327 select STACKTRACE
1328 select FRAME_POINTER if !MIPS && !PPC && !ARM && !S390 && !MICROBLAZE && !ARC && !X86
1329 select KALLSYMS
1330 select KALLSYMS_ALL
1332 config LOCKDEP_SMALL
1333 bool
1335 config DEBUG_LOCKDEP
1336 bool "Lock dependency engine debugging"
1337 depends on DEBUG_KERNEL && LOCKDEP
1338 help
1339 If you say Y here, the lock dependency engine will do
1340 additional runtime checks to debug itself, at the price
1341 of more runtime overhead.
1343 config DEBUG_ATOMIC_SLEEP
1344 bool "Sleep inside atomic section checking"
1345 select PREEMPT_COUNT
1346 depends on DEBUG_KERNEL
1347 depends on !ARCH_NO_PREEMPT
1348 help
1349 If you say Y here, various routines which may sleep will become very
1350 noisy if they are called inside atomic sections: when a spinlock is
1351 held, inside an rcu read side critical section, inside preempt disabled
1352 sections, inside an interrupt, etc...
1354 config DEBUG_LOCKING_API_SELFTESTS
1355 bool "Locking API boot-time self-tests"
1356 depends on DEBUG_KERNEL
1357 help
1358 Say Y here if you want the kernel to run a short self-test during
1359 bootup. The self-test checks whether common types of locking bugs
1360 are detected by debugging mechanisms or not. (if you disable
1361 lock debugging then those bugs wont be detected of course.)
1362 The following locking APIs are covered: spinlocks, rwlocks,
1363 mutexes and rwsems.
1365 config LOCK_TORTURE_TEST
1366 tristate "torture tests for locking"
1367 depends on DEBUG_KERNEL
1368 select TORTURE_TEST
1369 help
1370 This option provides a kernel module that runs torture tests
1371 on kernel locking primitives. The kernel module may be built
1372 after the fact on the running kernel to be tested, if desired.
1374 Say Y here if you want kernel locking-primitive torture tests
1375 to be built into the kernel.
1376 Say M if you want these torture tests to build as a module.
1377 Say N if you are unsure.
1379 config WW_MUTEX_SELFTEST
1380 tristate "Wait/wound mutex selftests"
1381 help
1382 This option provides a kernel module that runs tests on the
1383 on the struct ww_mutex locking API.
1385 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1386 with this test harness.
1388 Say M if you want these self tests to build as a module.
1389 Say N if you are unsure.
1391 config SCF_TORTURE_TEST
1392 tristate "torture tests for smp_call_function*()"
1393 depends on DEBUG_KERNEL
1394 select TORTURE_TEST
1395 help
1396 This option provides a kernel module that runs torture tests
1397 on the smp_call_function() family of primitives. The kernel
1398 module may be built after the fact on the running kernel to
1399 be tested, if desired.
1401 config CSD_LOCK_WAIT_DEBUG
1402 bool "Debugging for csd_lock_wait(), called from smp_call_function*()"
1403 depends on DEBUG_KERNEL
1404 depends on 64BIT
1405 default n
1406 help
1407 This option enables debug prints when CPUs are slow to respond
1408 to the smp_call_function*() IPI wrappers. These debug prints
1409 include the IPI handler function currently executing (if any)
1410 and relevant stack traces.
1412 endmenu # lock debugging
1414 config TRACE_IRQFLAGS
1415 depends on TRACE_IRQFLAGS_SUPPORT
1416 bool
1417 help
1418 Enables hooks to interrupt enabling and disabling for
1419 either tracing or lock debugging.
1421 config TRACE_IRQFLAGS_NMI
1422 def_bool y
1423 depends on TRACE_IRQFLAGS
1424 depends on TRACE_IRQFLAGS_NMI_SUPPORT
1426 config STACKTRACE
1427 bool "Stack backtrace support"
1428 depends on STACKTRACE_SUPPORT
1429 help
1430 This option causes the kernel to create a /proc/pid/stack for
1431 every process, showing its current stack trace.
1432 It is also used by various kernel debugging features that require
1433 stack trace generation.
1435 config WARN_ALL_UNSEEDED_RANDOM
1436 bool "Warn for all uses of unseeded randomness"
1437 default n
1438 help
1439 Some parts of the kernel contain bugs relating to their use of
1440 cryptographically secure random numbers before it's actually possible
1441 to generate those numbers securely. This setting ensures that these
1442 flaws don't go unnoticed, by enabling a message, should this ever
1443 occur. This will allow people with obscure setups to know when things
1444 are going wrong, so that they might contact developers about fixing
1445 it.
1447 Unfortunately, on some models of some architectures getting
1448 a fully seeded CRNG is extremely difficult, and so this can
1449 result in dmesg getting spammed for a surprisingly long
1450 time. This is really bad from a security perspective, and
1451 so architecture maintainers really need to do what they can
1452 to get the CRNG seeded sooner after the system is booted.
1453 However, since users cannot do anything actionable to
1454 address this, by default the kernel will issue only a single
1455 warning for the first use of unseeded randomness.
1457 Say Y here if you want to receive warnings for all uses of
1458 unseeded randomness. This will be of use primarily for
1459 those developers interested in improving the security of
1460 Linux kernels running on their architecture (or
1461 subarchitecture).
1463 config DEBUG_KOBJECT
1464 bool "kobject debugging"
1465 depends on DEBUG_KERNEL
1466 help
1467 If you say Y here, some extra kobject debugging messages will be sent
1468 to the syslog.
1470 config DEBUG_KOBJECT_RELEASE
1471 bool "kobject release debugging"
1472 depends on DEBUG_OBJECTS_TIMERS
1473 help
1474 kobjects are reference counted objects. This means that their
1475 last reference count put is not predictable, and the kobject can
1476 live on past the point at which a driver decides to drop it's
1477 initial reference to the kobject gained on allocation. An
1478 example of this would be a struct device which has just been
1479 unregistered.
1481 However, some buggy drivers assume that after such an operation,
1482 the memory backing the kobject can be immediately freed. This
1483 goes completely against the principles of a refcounted object.
1485 If you say Y here, the kernel will delay the release of kobjects
1486 on the last reference count to improve the visibility of this
1487 kind of kobject release bug.
1489 config HAVE_DEBUG_BUGVERBOSE
1490 bool
1492 menu "Debug kernel data structures"
1494 config DEBUG_LIST
1495 bool "Debug linked list manipulation"
1496 depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION
1497 help
1498 Enable this to turn on extended checks in the linked-list
1499 walking routines.
1501 If unsure, say N.
1503 config DEBUG_PLIST
1504 bool "Debug priority linked list manipulation"
1505 depends on DEBUG_KERNEL
1506 help
1507 Enable this to turn on extended checks in the priority-ordered
1508 linked-list (plist) walking routines. This checks the entire
1509 list multiple times during each manipulation.
1511 If unsure, say N.
1513 config DEBUG_SG
1514 bool "Debug SG table operations"
1515 depends on DEBUG_KERNEL
1516 help
1517 Enable this to turn on checks on scatter-gather tables. This can
1518 help find problems with drivers that do not properly initialize
1519 their sg tables.
1521 If unsure, say N.
1523 config DEBUG_NOTIFIERS
1524 bool "Debug notifier call chains"
1525 depends on DEBUG_KERNEL
1526 help
1527 Enable this to turn on sanity checking for notifier call chains.
1528 This is most useful for kernel developers to make sure that
1529 modules properly unregister themselves from notifier chains.
1530 This is a relatively cheap check but if you care about maximum
1531 performance, say N.
1533 config BUG_ON_DATA_CORRUPTION
1534 bool "Trigger a BUG when data corruption is detected"
1535 select DEBUG_LIST
1536 help
1537 Select this option if the kernel should BUG when it encounters
1538 data corruption in kernel memory structures when they get checked
1539 for validity.
1541 If unsure, say N.
1543 endmenu
1545 config DEBUG_CREDENTIALS
1546 bool "Debug credential management"
1547 depends on DEBUG_KERNEL
1548 help
1549 Enable this to turn on some debug checking for credential
1550 management. The additional code keeps track of the number of
1551 pointers from task_structs to any given cred struct, and checks to
1552 see that this number never exceeds the usage count of the cred
1553 struct.
1555 Furthermore, if SELinux is enabled, this also checks that the
1556 security pointer in the cred struct is never seen to be invalid.
1558 If unsure, say N.
1560 source "kernel/rcu/Kconfig.debug"
1562 config DEBUG_WQ_FORCE_RR_CPU
1563 bool "Force round-robin CPU selection for unbound work items"
1564 depends on DEBUG_KERNEL
1565 default n
1566 help
1567 Workqueue used to implicitly guarantee that work items queued
1568 without explicit CPU specified are put on the local CPU. This
1569 guarantee is no longer true and while local CPU is still
1570 preferred work items may be put on foreign CPUs. Kernel
1571 parameter "workqueue.debug_force_rr_cpu" is added to force
1572 round-robin CPU selection to flush out usages which depend on the
1573 now broken guarantee. This config option enables the debug
1574 feature by default. When enabled, memory and cache locality will
1575 be impacted.
1577 config DEBUG_BLOCK_EXT_DEVT
1578 bool "Force extended block device numbers and spread them"
1579 depends on DEBUG_KERNEL
1580 depends on BLOCK
1581 default n
1582 help
1583 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1584 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1585 YOU ARE DOING. Distros, please enable this and fix whatever
1586 is broken.
1588 Conventionally, block device numbers are allocated from
1589 predetermined contiguous area. However, extended block area
1590 may introduce non-contiguous block device numbers. This
1591 option forces most block device numbers to be allocated from
1592 the extended space and spreads them to discover kernel or
1593 userland code paths which assume predetermined contiguous
1594 device number allocation.
1596 Note that turning on this debug option shuffles all the
1597 device numbers for all IDE and SCSI devices including libata
1598 ones, so root partition specified using device number
1599 directly (via rdev or root=MAJ:MIN) won't work anymore.
1600 Textual device names (root=/dev/sdXn) will continue to work.
1602 Say N if you are unsure.
1604 config CPU_HOTPLUG_STATE_CONTROL
1605 bool "Enable CPU hotplug state control"
1606 depends on DEBUG_KERNEL
1607 depends on HOTPLUG_CPU
1608 default n
1609 help
1610 Allows to write steps between "offline" and "online" to the CPUs
1611 sysfs target file so states can be stepped granular. This is a debug
1612 option for now as the hotplug machinery cannot be stopped and
1613 restarted at arbitrary points yet.
1615 Say N if your are unsure.
1617 config LATENCYTOP
1618 bool "Latency measuring infrastructure"
1619 depends on DEBUG_KERNEL
1620 depends on STACKTRACE_SUPPORT
1621 depends on PROC_FS
1622 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86
1623 select KALLSYMS
1624 select KALLSYMS_ALL
1625 select STACKTRACE
1626 select SCHEDSTATS
1627 select SCHED_DEBUG
1628 help
1629 Enable this option if you want to use the LatencyTOP tool
1630 to find out which userspace is blocking on what kernel operations.
1632 source "kernel/trace/Kconfig"
1634 config PROVIDE_OHCI1394_DMA_INIT
1635 bool "Remote debugging over FireWire early on boot"
1636 depends on PCI && X86
1637 help
1638 If you want to debug problems which hang or crash the kernel early
1639 on boot and the crashing machine has a FireWire port, you can use
1640 this feature to remotely access the memory of the crashed machine
1641 over FireWire. This employs remote DMA as part of the OHCI1394
1642 specification which is now the standard for FireWire controllers.
1644 With remote DMA, you can monitor the printk buffer remotely using
1645 firescope and access all memory below 4GB using fireproxy from gdb.
1646 Even controlling a kernel debugger is possible using remote DMA.
1648 Usage:
1650 If ohci1394_dma=early is used as boot parameter, it will initialize
1651 all OHCI1394 controllers which are found in the PCI config space.
1653 As all changes to the FireWire bus such as enabling and disabling
1654 devices cause a bus reset and thereby disable remote DMA for all
1655 devices, be sure to have the cable plugged and FireWire enabled on
1656 the debugging host before booting the debug target for debugging.
1658 This code (~1k) is freed after boot. By then, the firewire stack
1659 in charge of the OHCI-1394 controllers should be used instead.
1661 See Documentation/core-api/debugging-via-ohci1394.rst for more information.
1663 source "samples/Kconfig"
1665 config ARCH_HAS_DEVMEM_IS_ALLOWED
1666 bool
1668 config STRICT_DEVMEM
1669 bool "Filter access to /dev/mem"
1670 depends on MMU && DEVMEM
1671 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED
1672 default y if PPC || X86 || ARM64
1673 help
1674 If this option is disabled, you allow userspace (root) access to all
1675 of memory, including kernel and userspace memory. Accidental
1676 access to this is obviously disastrous, but specific access can
1677 be used by people debugging the kernel. Note that with PAT support
1678 enabled, even in this case there are restrictions on /dev/mem
1679 use due to the cache aliasing requirements.
1681 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
1682 file only allows userspace access to PCI space and the BIOS code and
1683 data regions. This is sufficient for dosemu and X and all common
1684 users of /dev/mem.
1686 If in doubt, say Y.
1688 config IO_STRICT_DEVMEM
1689 bool "Filter I/O access to /dev/mem"
1690 depends on STRICT_DEVMEM
1691 help
1692 If this option is disabled, you allow userspace (root) access to all
1693 io-memory regardless of whether a driver is actively using that
1694 range. Accidental access to this is obviously disastrous, but
1695 specific access can be used by people debugging kernel drivers.
1697 If this option is switched on, the /dev/mem file only allows
1698 userspace access to *idle* io-memory ranges (see /proc/iomem) This
1699 may break traditional users of /dev/mem (dosemu, legacy X, etc...)
1700 if the driver using a given range cannot be disabled.
1702 If in doubt, say Y.
1704 menu "$(SRCARCH) Debugging"
1706 source "arch/$(SRCARCH)/Kconfig.debug"
1708 endmenu
1710 menu "Kernel Testing and Coverage"
1712 source "lib/kunit/Kconfig"
1714 config NOTIFIER_ERROR_INJECTION
1715 tristate "Notifier error injection"
1716 depends on DEBUG_KERNEL
1717 select DEBUG_FS
1718 help
1719 This option provides the ability to inject artificial errors to
1720 specified notifier chain callbacks. It is useful to test the error
1721 handling of notifier call chain failures.
1723 Say N if unsure.
1725 config PM_NOTIFIER_ERROR_INJECT
1726 tristate "PM notifier error injection module"
1727 depends on PM && NOTIFIER_ERROR_INJECTION
1728 default m if PM_DEBUG
1729 help
1730 This option provides the ability to inject artificial errors to
1731 PM notifier chain callbacks. It is controlled through debugfs
1732 interface /sys/kernel/debug/notifier-error-inject/pm
1734 If the notifier call chain should be failed with some events
1735 notified, write the error code to "actions/<notifier event>/error".
1737 Example: Inject PM suspend error (-12 = -ENOMEM)
1739 # cd /sys/kernel/debug/notifier-error-inject/pm/
1740 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1741 # echo mem > /sys/power/state
1742 bash: echo: write error: Cannot allocate memory
1744 To compile this code as a module, choose M here: the module will
1745 be called pm-notifier-error-inject.
1747 If unsure, say N.
1749 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1750 tristate "OF reconfig notifier error injection module"
1751 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1752 help
1753 This option provides the ability to inject artificial errors to
1754 OF reconfig notifier chain callbacks. It is controlled
1755 through debugfs interface under
1756 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1758 If the notifier call chain should be failed with some events
1759 notified, write the error code to "actions/<notifier event>/error".
1761 To compile this code as a module, choose M here: the module will
1762 be called of-reconfig-notifier-error-inject.
1764 If unsure, say N.
1766 config NETDEV_NOTIFIER_ERROR_INJECT
1767 tristate "Netdev notifier error injection module"
1768 depends on NET && NOTIFIER_ERROR_INJECTION
1769 help
1770 This option provides the ability to inject artificial errors to
1771 netdevice notifier chain callbacks. It is controlled through debugfs
1772 interface /sys/kernel/debug/notifier-error-inject/netdev
1774 If the notifier call chain should be failed with some events
1775 notified, write the error code to "actions/<notifier event>/error".
1777 Example: Inject netdevice mtu change error (-22 = -EINVAL)
1779 # cd /sys/kernel/debug/notifier-error-inject/netdev
1780 # echo -22 > actions/NETDEV_CHANGEMTU/error
1781 # ip link set eth0 mtu 1024
1782 RTNETLINK answers: Invalid argument
1784 To compile this code as a module, choose M here: the module will
1785 be called netdev-notifier-error-inject.
1787 If unsure, say N.
1789 config FUNCTION_ERROR_INJECTION
1790 def_bool y
1791 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
1793 config FAULT_INJECTION
1794 bool "Fault-injection framework"
1795 depends on DEBUG_KERNEL
1796 help
1797 Provide fault-injection framework.
1798 For more details, see Documentation/fault-injection/.
1800 config FAILSLAB
1801 bool "Fault-injection capability for kmalloc"
1802 depends on FAULT_INJECTION
1803 depends on SLAB || SLUB
1804 help
1805 Provide fault-injection capability for kmalloc.
1807 config FAIL_PAGE_ALLOC
1808 bool "Fault-injection capability for alloc_pages()"
1809 depends on FAULT_INJECTION
1810 help
1811 Provide fault-injection capability for alloc_pages().
1813 config FAULT_INJECTION_USERCOPY
1814 bool "Fault injection capability for usercopy functions"
1815 depends on FAULT_INJECTION
1816 help
1817 Provides fault-injection capability to inject failures
1818 in usercopy functions (copy_from_user(), get_user(), ...).
1820 config FAIL_MAKE_REQUEST
1821 bool "Fault-injection capability for disk IO"
1822 depends on FAULT_INJECTION && BLOCK
1823 help
1824 Provide fault-injection capability for disk IO.
1826 config FAIL_IO_TIMEOUT
1827 bool "Fault-injection capability for faking disk interrupts"
1828 depends on FAULT_INJECTION && BLOCK
1829 help
1830 Provide fault-injection capability on end IO handling. This
1831 will make the block layer "forget" an interrupt as configured,
1832 thus exercising the error handling.
1834 Only works with drivers that use the generic timeout handling,
1835 for others it wont do anything.
1837 config FAIL_FUTEX
1838 bool "Fault-injection capability for futexes"
1839 select DEBUG_FS
1840 depends on FAULT_INJECTION && FUTEX
1841 help
1842 Provide fault-injection capability for futexes.
1844 config FAULT_INJECTION_DEBUG_FS
1845 bool "Debugfs entries for fault-injection capabilities"
1846 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1847 help
1848 Enable configuration of fault-injection capabilities via debugfs.
1850 config FAIL_FUNCTION
1851 bool "Fault-injection capability for functions"
1852 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
1853 help
1854 Provide function-based fault-injection capability.
1855 This will allow you to override a specific function with a return
1856 with given return value. As a result, function caller will see
1857 an error value and have to handle it. This is useful to test the
1858 error handling in various subsystems.
1860 config FAIL_MMC_REQUEST
1861 bool "Fault-injection capability for MMC IO"
1862 depends on FAULT_INJECTION_DEBUG_FS && MMC
1863 help
1864 Provide fault-injection capability for MMC IO.
1865 This will make the mmc core return data errors. This is
1866 useful to test the error handling in the mmc block device
1867 and to test how the mmc host driver handles retries from
1868 the block device.
1870 config FAULT_INJECTION_STACKTRACE_FILTER
1871 bool "stacktrace filter for fault-injection capabilities"
1872 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1873 depends on !X86_64
1874 select STACKTRACE
1875 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86
1876 help
1877 Provide stacktrace filter for fault-injection capabilities
1879 config ARCH_HAS_KCOV
1880 bool
1881 help
1882 An architecture should select this when it can successfully
1883 build and run with CONFIG_KCOV. This typically requires
1884 disabling instrumentation for some early boot code.
1886 config CC_HAS_SANCOV_TRACE_PC
1887 def_bool $(cc-option,-fsanitize-coverage=trace-pc)
1890 config KCOV
1891 bool "Code coverage for fuzzing"
1892 depends on ARCH_HAS_KCOV
1893 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
1894 select DEBUG_FS
1895 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
1896 help
1897 KCOV exposes kernel code coverage information in a form suitable
1898 for coverage-guided fuzzing (randomized testing).
1900 If RANDOMIZE_BASE is enabled, PC values will not be stable across
1901 different machines and across reboots. If you need stable PC values,
1902 disable RANDOMIZE_BASE.
1904 For more details, see Documentation/dev-tools/kcov.rst.
1906 config KCOV_ENABLE_COMPARISONS
1907 bool "Enable comparison operands collection by KCOV"
1908 depends on KCOV
1909 depends on $(cc-option,-fsanitize-coverage=trace-cmp)
1910 help
1911 KCOV also exposes operands of every comparison in the instrumented
1912 code along with operand sizes and PCs of the comparison instructions.
1913 These operands can be used by fuzzing engines to improve the quality
1914 of fuzzing coverage.
1916 config KCOV_INSTRUMENT_ALL
1917 bool "Instrument all code by default"
1918 depends on KCOV
1919 default y
1920 help
1921 If you are doing generic system call fuzzing (like e.g. syzkaller),
1922 then you will want to instrument the whole kernel and you should
1923 say y here. If you are doing more targeted fuzzing (like e.g.
1924 filesystem fuzzing with AFL) then you will want to enable coverage
1925 for more specific subsets of files, and should say n here.
1927 config KCOV_IRQ_AREA_SIZE
1928 hex "Size of interrupt coverage collection area in words"
1929 depends on KCOV
1930 default 0x40000
1931 help
1932 KCOV uses preallocated per-cpu areas to collect coverage from
1933 soft interrupts. This specifies the size of those areas in the
1934 number of unsigned long words.
1936 menuconfig RUNTIME_TESTING_MENU
1937 bool "Runtime Testing"
1938 def_bool y
1940 if RUNTIME_TESTING_MENU
1942 config LKDTM
1943 tristate "Linux Kernel Dump Test Tool Module"
1944 depends on DEBUG_FS
1945 help
1946 This module enables testing of the different dumping mechanisms by
1947 inducing system failures at predefined crash points.
1948 If you don't need it: say N
1949 Choose M here to compile this code as a module. The module will be
1950 called lkdtm.
1952 Documentation on how to use the module can be found in
1953 Documentation/fault-injection/provoke-crashes.rst
1955 config TEST_LIST_SORT
1956 tristate "Linked list sorting test"
1957 depends on DEBUG_KERNEL || m
1958 help
1959 Enable this to turn on 'list_sort()' function test. This test is
1960 executed only once during system boot (so affects only boot time),
1961 or at module load time.
1963 If unsure, say N.
1965 config TEST_MIN_HEAP
1966 tristate "Min heap test"
1967 depends on DEBUG_KERNEL || m
1968 help
1969 Enable this to turn on min heap function tests. This test is
1970 executed only once during system boot (so affects only boot time),
1971 or at module load time.
1973 If unsure, say N.
1975 config TEST_SORT
1976 tristate "Array-based sort test"
1977 depends on DEBUG_KERNEL || m
1978 help
1979 This option enables the self-test function of 'sort()' at boot,
1980 or at module load time.
1982 If unsure, say N.
1984 config KPROBES_SANITY_TEST
1985 bool "Kprobes sanity tests"
1986 depends on DEBUG_KERNEL
1987 depends on KPROBES
1988 help
1989 This option provides for testing basic kprobes functionality on
1990 boot. Samples of kprobe and kretprobe are inserted and
1991 verified for functionality.
1993 Say N if you are unsure.
1995 config BACKTRACE_SELF_TEST
1996 tristate "Self test for the backtrace code"
1997 depends on DEBUG_KERNEL
1998 help
1999 This option provides a kernel module that can be used to test
2000 the kernel stack backtrace code. This option is not useful
2001 for distributions or general kernels, but only for kernel
2002 developers working on architecture code.
2004 Note that if you want to also test saved backtraces, you will
2005 have to enable STACKTRACE as well.
2007 Say N if you are unsure.
2009 config RBTREE_TEST
2010 tristate "Red-Black tree test"
2011 depends on DEBUG_KERNEL
2012 help
2013 A benchmark measuring the performance of the rbtree library.
2014 Also includes rbtree invariant checks.
2016 config REED_SOLOMON_TEST
2017 tristate "Reed-Solomon library test"
2018 depends on DEBUG_KERNEL || m
2019 select REED_SOLOMON
2020 select REED_SOLOMON_ENC16
2021 select REED_SOLOMON_DEC16
2022 help
2023 This option enables the self-test function of rslib at boot,
2024 or at module load time.
2026 If unsure, say N.
2028 config INTERVAL_TREE_TEST
2029 tristate "Interval tree test"
2030 depends on DEBUG_KERNEL
2031 select INTERVAL_TREE
2032 help
2033 A benchmark measuring the performance of the interval tree library
2035 config PERCPU_TEST
2036 tristate "Per cpu operations test"
2037 depends on m && DEBUG_KERNEL
2038 help
2039 Enable this option to build test module which validates per-cpu
2040 operations.
2042 If unsure, say N.
2044 config ATOMIC64_SELFTEST
2045 tristate "Perform an atomic64_t self-test"
2046 help
2047 Enable this option to test the atomic64_t functions at boot or
2048 at module load time.
2050 If unsure, say N.
2052 config ASYNC_RAID6_TEST
2053 tristate "Self test for hardware accelerated raid6 recovery"
2054 depends on ASYNC_RAID6_RECOV
2055 select ASYNC_MEMCPY
2056 help
2057 This is a one-shot self test that permutes through the
2058 recovery of all the possible two disk failure scenarios for a
2059 N-disk array. Recovery is performed with the asynchronous
2060 raid6 recovery routines, and will optionally use an offload
2061 engine if one is available.
2063 If unsure, say N.
2065 config TEST_HEXDUMP
2066 tristate "Test functions located in the hexdump module at runtime"
2068 config TEST_STRING_HELPERS
2069 tristate "Test functions located in the string_helpers module at runtime"
2071 config TEST_STRSCPY
2072 tristate "Test strscpy*() family of functions at runtime"
2074 config TEST_KSTRTOX
2075 tristate "Test kstrto*() family of functions at runtime"
2077 config TEST_PRINTF
2078 tristate "Test printf() family of functions at runtime"
2080 config TEST_BITMAP
2081 tristate "Test bitmap_*() family of functions at runtime"
2082 help
2083 Enable this option to test the bitmap functions at boot.
2085 If unsure, say N.
2087 config TEST_UUID
2088 tristate "Test functions located in the uuid module at runtime"
2090 config TEST_XARRAY
2091 tristate "Test the XArray code at runtime"
2093 config TEST_OVERFLOW
2094 tristate "Test check_*_overflow() functions at runtime"
2096 config TEST_RHASHTABLE
2097 tristate "Perform selftest on resizable hash table"
2098 help
2099 Enable this option to test the rhashtable functions at boot.
2101 If unsure, say N.
2103 config TEST_HASH
2104 tristate "Perform selftest on hash functions"
2105 help
2106 Enable this option to test the kernel's integer (<linux/hash.h>),
2107 string (<linux/stringhash.h>), and siphash (<linux/siphash.h>)
2108 hash functions on boot (or module load).
2110 This is intended to help people writing architecture-specific
2111 optimized versions. If unsure, say N.
2113 config TEST_IDA
2114 tristate "Perform selftest on IDA functions"
2116 config TEST_PARMAN
2117 tristate "Perform selftest on priority array manager"
2118 depends on PARMAN
2119 help
2120 Enable this option to test priority array manager on boot
2121 (or module load).
2123 If unsure, say N.
2125 config TEST_IRQ_TIMINGS
2126 bool "IRQ timings selftest"
2127 depends on IRQ_TIMINGS
2128 help
2129 Enable this option to test the irq timings code on boot.
2131 If unsure, say N.
2133 config TEST_LKM
2134 tristate "Test module loading with 'hello world' module"
2135 depends on m
2136 help
2137 This builds the "test_module" module that emits "Hello, world"
2138 on printk when loaded. It is designed to be used for basic
2139 evaluation of the module loading subsystem (for example when
2140 validating module verification). It lacks any extra dependencies,
2141 and will not normally be loaded by the system unless explicitly
2142 requested by name.
2144 If unsure, say N.
2146 config TEST_BITOPS
2147 tristate "Test module for compilation of bitops operations"
2148 depends on m
2149 help
2150 This builds the "test_bitops" module that is much like the
2151 TEST_LKM module except that it does a basic exercise of the
2152 set/clear_bit macros and get_count_order/long to make sure there are
2153 no compiler warnings from C=1 sparse checker or -Wextra
2154 compilations. It has no dependencies and doesn't run or load unless
2155 explicitly requested by name. for example: modprobe test_bitops.
2157 If unsure, say N.
2159 config TEST_VMALLOC
2160 tristate "Test module for stress/performance analysis of vmalloc allocator"
2161 default n
2162 depends on MMU
2163 depends on m
2164 help
2165 This builds the "test_vmalloc" module that should be used for
2166 stress and performance analysis. So, any new change for vmalloc
2167 subsystem can be evaluated from performance and stability point
2168 of view.
2170 If unsure, say N.
2172 config TEST_USER_COPY
2173 tristate "Test user/kernel boundary protections"
2174 depends on m
2175 help
2176 This builds the "test_user_copy" module that runs sanity checks
2177 on the copy_to/from_user infrastructure, making sure basic
2178 user/kernel boundary testing is working. If it fails to load,
2179 a regression has been detected in the user/kernel memory boundary
2180 protections.
2182 If unsure, say N.
2184 config TEST_BPF
2185 tristate "Test BPF filter functionality"
2186 depends on m && NET
2187 help
2188 This builds the "test_bpf" module that runs various test vectors
2189 against the BPF interpreter or BPF JIT compiler depending on the
2190 current setting. This is in particular useful for BPF JIT compiler
2191 development, but also to run regression tests against changes in
2192 the interpreter code. It also enables test stubs for eBPF maps and
2193 verifier used by user space verifier testsuite.
2195 If unsure, say N.
2197 config TEST_BLACKHOLE_DEV
2198 tristate "Test blackhole netdev functionality"
2199 depends on m && NET
2200 help
2201 This builds the "test_blackhole_dev" module that validates the
2202 data path through this blackhole netdev.
2204 If unsure, say N.
2206 config FIND_BIT_BENCHMARK
2207 tristate "Test find_bit functions"
2208 help
2209 This builds the "test_find_bit" module that measure find_*_bit()
2210 functions performance.
2212 If unsure, say N.
2214 config TEST_FIRMWARE
2215 tristate "Test firmware loading via userspace interface"
2216 depends on FW_LOADER
2217 help
2218 This builds the "test_firmware" module that creates a userspace
2219 interface for testing firmware loading. This can be used to
2220 control the triggering of firmware loading without needing an
2221 actual firmware-using device. The contents can be rechecked by
2222 userspace.
2224 If unsure, say N.
2226 config TEST_SYSCTL
2227 tristate "sysctl test driver"
2228 depends on PROC_SYSCTL
2229 help
2230 This builds the "test_sysctl" module. This driver enables to test the
2231 proc sysctl interfaces available to drivers safely without affecting
2232 production knobs which might alter system functionality.
2234 If unsure, say N.
2236 config BITFIELD_KUNIT
2237 tristate "KUnit test bitfield functions at runtime"
2238 depends on KUNIT
2239 help
2240 Enable this option to test the bitfield functions at boot.
2242 KUnit tests run during boot and output the results to the debug log
2243 in TAP format (http://testanything.org/). Only useful for kernel devs
2244 running the KUnit test harness, and not intended for inclusion into a
2245 production build.
2247 For more information on KUnit and unit tests in general please refer
2248 to the KUnit documentation in Documentation/dev-tools/kunit/.
2250 If unsure, say N.
2252 config RESOURCE_KUNIT_TEST
2253 tristate "KUnit test for resource API"
2254 depends on KUNIT
2255 help
2256 This builds the resource API unit test.
2257 Tests the logic of API provided by resource.c and ioport.h.
2258 For more information on KUnit and unit tests in general please refer
2259 to the KUnit documentation in Documentation/dev-tools/kunit/.
2261 If unsure, say N.
2263 config SYSCTL_KUNIT_TEST
2264 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS
2265 depends on KUNIT
2266 default KUNIT_ALL_TESTS
2267 help
2268 This builds the proc sysctl unit test, which runs on boot.
2269 Tests the API contract and implementation correctness of sysctl.
2270 For more information on KUnit and unit tests in general please refer
2271 to the KUnit documentation in Documentation/dev-tools/kunit/.
2273 If unsure, say N.
2275 config LIST_KUNIT_TEST
2276 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS
2277 depends on KUNIT
2278 default KUNIT_ALL_TESTS
2279 help
2280 This builds the linked list KUnit test suite.
2281 It tests that the API and basic functionality of the list_head type
2282 and associated macros.
2284 KUnit tests run during boot and output the results to the debug log
2285 in TAP format (https://testanything.org/). Only useful for kernel devs
2286 running the KUnit test harness, and not intended for inclusion into a
2287 production build.
2289 For more information on KUnit and unit tests in general please refer
2290 to the KUnit documentation in Documentation/dev-tools/kunit/.
2292 If unsure, say N.
2294 config LINEAR_RANGES_TEST
2295 tristate "KUnit test for linear_ranges"
2296 depends on KUNIT
2297 select LINEAR_RANGES
2298 help
2299 This builds the linear_ranges unit test, which runs on boot.
2300 Tests the linear_ranges logic correctness.
2301 For more information on KUnit and unit tests in general please refer
2302 to the KUnit documentation in Documentation/dev-tools/kunit/.
2304 If unsure, say N.
2306 config CMDLINE_KUNIT_TEST
2307 tristate "KUnit test for cmdline API"
2308 depends on KUNIT
2309 help
2310 This builds the cmdline API unit test.
2311 Tests the logic of API provided by cmdline.c.
2312 For more information on KUnit and unit tests in general please refer
2313 to the KUnit documentation in Documentation/dev-tools/kunit/.
2315 If unsure, say N.
2317 config BITS_TEST
2318 tristate "KUnit test for bits.h"
2319 depends on KUNIT
2320 help
2321 This builds the bits unit test.
2322 Tests the logic of macros defined in bits.h.
2323 For more information on KUnit and unit tests in general please refer
2324 to the KUnit documentation in Documentation/dev-tools/kunit/.
2326 If unsure, say N.
2328 config TEST_UDELAY
2329 tristate "udelay test driver"
2330 help
2331 This builds the "udelay_test" module that helps to make sure
2332 that udelay() is working properly.
2334 If unsure, say N.
2336 config TEST_STATIC_KEYS
2337 tristate "Test static keys"
2338 depends on m
2339 help
2340 Test the static key interfaces.
2342 If unsure, say N.
2344 config TEST_KMOD
2345 tristate "kmod stress tester"
2346 depends on m
2347 depends on NETDEVICES && NET_CORE && INET # for TUN
2348 depends on BLOCK
2349 select TEST_LKM
2350 select XFS_FS
2351 select TUN
2352 select BTRFS_FS
2353 help
2354 Test the kernel's module loading mechanism: kmod. kmod implements
2355 support to load modules using the Linux kernel's usermode helper.
2356 This test provides a series of tests against kmod.
2358 Although technically you can either build test_kmod as a module or
2359 into the kernel we disallow building it into the kernel since
2360 it stress tests request_module() and this will very likely cause
2361 some issues by taking over precious threads available from other
2362 module load requests, ultimately this could be fatal.
2364 To run tests run:
2366 tools/testing/selftests/kmod/kmod.sh --help
2368 If unsure, say N.
2370 config TEST_DEBUG_VIRTUAL
2371 tristate "Test CONFIG_DEBUG_VIRTUAL feature"
2372 depends on DEBUG_VIRTUAL
2373 help
2374 Test the kernel's ability to detect incorrect calls to
2375 virt_to_phys() done against the non-linear part of the
2376 kernel's virtual address map.
2378 If unsure, say N.
2380 config TEST_MEMCAT_P
2381 tristate "Test memcat_p() helper function"
2382 help
2383 Test the memcat_p() helper for correctly merging two
2384 pointer arrays together.
2386 If unsure, say N.
2388 config TEST_LIVEPATCH
2389 tristate "Test livepatching"
2390 default n
2391 depends on DYNAMIC_DEBUG
2392 depends on LIVEPATCH
2393 depends on m
2394 help
2395 Test kernel livepatching features for correctness. The tests will
2396 load test modules that will be livepatched in various scenarios.
2398 To run all the livepatching tests:
2400 make -C tools/testing/selftests TARGETS=livepatch run_tests
2402 Alternatively, individual tests may be invoked:
2404 tools/testing/selftests/livepatch/test-callbacks.sh
2405 tools/testing/selftests/livepatch/test-livepatch.sh
2406 tools/testing/selftests/livepatch/test-shadow-vars.sh
2408 If unsure, say N.
2410 config TEST_OBJAGG
2411 tristate "Perform selftest on object aggreration manager"
2412 default n
2413 depends on OBJAGG
2414 help
2415 Enable this option to test object aggregation manager on boot
2416 (or module load).
2419 config TEST_STACKINIT
2420 tristate "Test level of stack variable initialization"
2421 help
2422 Test if the kernel is zero-initializing stack variables and
2423 padding. Coverage is controlled by compiler flags,
2424 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2425 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2427 If unsure, say N.
2429 config TEST_MEMINIT
2430 tristate "Test heap/page initialization"
2431 help
2432 Test if the kernel is zero-initializing heap and page allocations.
2433 This can be useful to test init_on_alloc and init_on_free features.
2435 If unsure, say N.
2437 config TEST_HMM
2438 tristate "Test HMM (Heterogeneous Memory Management)"
2439 depends on TRANSPARENT_HUGEPAGE
2440 depends on DEVICE_PRIVATE
2441 select HMM_MIRROR
2442 select MMU_NOTIFIER
2443 help
2444 This is a pseudo device driver solely for testing HMM.
2445 Say M here if you want to build the HMM test module.
2446 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests.
2448 If unsure, say N.
2450 config TEST_FREE_PAGES
2451 tristate "Test freeing pages"
2452 help
2453 Test that a memory leak does not occur due to a race between
2454 freeing a block of pages and a speculative page reference.
2455 Loading this module is safe if your kernel has the bug fixed.
2456 If the bug is not fixed, it will leak gigabytes of memory and
2457 probably OOM your system.
2459 config TEST_FPU
2460 tristate "Test floating point operations in kernel space"
2461 depends on X86 && !KCOV_INSTRUMENT_ALL
2462 help
2463 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu
2464 which will trigger a sequence of floating point operations. This is used
2465 for self-testing floating point control register setting in
2466 kernel_fpu_begin().
2468 If unsure, say N.
2470 endif # RUNTIME_TESTING_MENU
2472 config MEMTEST
2473 bool "Memtest"
2474 help
2475 This option adds a kernel parameter 'memtest', which allows memtest
2476 to be set.
2477 memtest=0, mean disabled; -- default
2478 memtest=1, mean do 1 test pattern;
2479 ...
2480 memtest=17, mean do 17 test patterns.
2481 If you are unsure how to answer this question, answer N.
2485 config HYPERV_TESTING
2486 bool "Microsoft Hyper-V driver testing"
2487 default n
2488 depends on HYPERV && DEBUG_FS
2489 help
2490 Select this option to enable Hyper-V vmbus testing.
2492 endmenu # "Kernel Testing and Coverage"
2494 source "Documentation/Kconfig"
2496 endmenu # Kernel hacking