1 # SPDX-License-Identifier: GPL-2.0-only
4 menu "printk and dmesg options"
7 bool "Show timing information on printks"
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
22 bool "Show caller information on printks"
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)
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
38 config STACKTRACE_BUILD_ID
39 bool "Show build ID information in stacktraces"
42 Selecting this option adds build ID information for symbols in
43 stacktraces printed with the printk format '%p[SR]b'.
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.
49 config CONSOLE_LOGLEVEL_DEFAULT
50 int "Default console loglevel (1-15)"
54 Default loglevel to determine what will be printed on the console.
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.
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
64 config CONSOLE_LOGLEVEL_QUIET
65 int "quiet console loglevel (1-15)"
69 loglevel to use when "quiet" is passed on the kernel commandline.
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>"
75 config MESSAGE_LOGLEVEL_DEFAULT
76 int "Default message log level (1-7)"
80 Default log level for printk statements with no specified priority.
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
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.
90 config BOOT_PRINTK_DELAY
91 bool "Delay each boot printk message by N milliseconds"
92 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
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,
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.
109 bool "Enable dynamic printk() support"
112 depends on (DEBUG_FS || PROC_FS)
113 select DYNAMIC_DEBUG_CORE
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%.
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.
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:
138 filename:lineno [module]function flags format
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
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"
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
161 // enable all the messages in file svcsock.c
162 nullarbor:~ # echo -n 'file svcsock.c +p' >
163 <debugfs>/dynamic_debug/control
165 // enable all the messages in the NFS server module
166 nullarbor:~ # echo -n 'module nfsd +p' >
167 <debugfs>/dynamic_debug/control
169 // enable all 12 messages in the function svc_process()
170 nullarbor:~ # echo -n 'func svc_process +p' >
171 <debugfs>/dynamic_debug/control
173 // disable all 12 messages in the function svc_process()
174 nullarbor:~ # echo -n 'func svc_process -p' >
175 <debugfs>/dynamic_debug/control
177 See Documentation/admin-guide/dynamic-debug-howto.rst for additional
180 config DYNAMIC_DEBUG_CORE
181 bool "Enable core function of dynamic debug support"
183 depends on (DEBUG_FS || PROC_FS)
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.
191 config SYMBOLIC_ERRNAME
192 bool "Support symbolic error names in printf"
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.
200 config DEBUG_BUGVERBOSE
201 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
202 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
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.
209 endmenu # "printk and dmesg options"
212 bool "Kernel debugging"
214 Say Y here if you are developing drivers or trying to debug and
215 identify kernel problems.
218 bool "Miscellaneous debug code"
220 depends on DEBUG_KERNEL
222 Say Y here if you need to enable miscellaneous debug code that should
223 be under a more specific debug option but isn't.
225 menu "Compile-time checks and compiler options"
230 A kernel debug info option other than "None" has been selected
231 in the "Debug information" choice below, indicating that debug
232 information will be generated for build targets.
234 # Clang is known to generate .{s,u}leb128 with symbol deltas with DWARF5, which
235 # some targets may not support: https://sourceware.org/bugzilla/show_bug.cgi?id=27215
236 config AS_HAS_NON_CONST_LEB128
237 def_bool $(as-instr,.uleb128 .Lexpr_end4 - .Lexpr_start3\n.Lexpr_start3:\n.Lexpr_end4:)
240 prompt "Debug information"
241 depends on DEBUG_KERNEL
243 Selecting something other than "None" results in a kernel image
244 that will include debugging info resulting in a larger kernel image.
245 This adds debug symbols to the kernel and modules (gcc -g), and
246 is needed if you intend to use kernel crashdump or binary object
247 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
249 Choose which version of DWARF debug info to emit. If unsure,
250 select "Toolchain default".
252 config DEBUG_INFO_NONE
253 bool "Disable debug information"
255 Do not build the kernel with debugging information, which will
256 result in a faster and smaller build.
258 config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
259 bool "Rely on the toolchain's implicit default DWARF version"
261 depends on !CC_IS_CLANG || AS_IS_LLVM || CLANG_VERSION < 140000 || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_LEB128)
263 The implicit default version of DWARF debug info produced by a
264 toolchain changes over time.
266 This can break consumers of the debug info that haven't upgraded to
267 support newer revisions, and prevent testing newer versions, but
268 those should be less common scenarios.
270 config DEBUG_INFO_DWARF4
271 bool "Generate DWARF Version 4 debuginfo"
273 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502)
275 Generate DWARF v4 debug info. This requires gcc 4.5+, binutils 2.35.2
276 if using clang without clang's integrated assembler, and gdb 7.0+.
278 If you have consumers of DWARF debug info that are not ready for
279 newer revisions of DWARF, you may wish to choose this or have your
282 config DEBUG_INFO_DWARF5
283 bool "Generate DWARF Version 5 debuginfo"
285 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_LEB128)
287 Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc
288 5.0+ accepts the -gdwarf-5 flag but only had partial support for some
289 draft features until 7.0), and gdb 8.0+.
291 Changes to the structure of debug info in Version 5 allow for around
292 15-18% savings in resulting image and debug info section sizes as
293 compared to DWARF Version 4. DWARF Version 5 standardizes previous
294 extensions such as accelerators for symbol indexing and the format
295 for fission (.dwo/.dwp) files. Users may not want to select this
296 config if they rely on tooling that has not yet been updated to
297 support DWARF Version 5.
299 endchoice # "Debug information"
303 config DEBUG_INFO_REDUCED
304 bool "Reduce debugging information"
306 If you say Y here gcc is instructed to generate less debugging
307 information for structure types. This means that tools that
308 need full debugging information (like kgdb or systemtap) won't
309 be happy. But if you merely need debugging information to
310 resolve line numbers there is no loss. Advantage is that
311 build directory object sizes shrink dramatically over a full
312 DEBUG_INFO build and compile times are reduced too.
313 Only works with newer gcc versions.
316 prompt "Compressed Debug information"
318 Compress the resulting debug info. Results in smaller debug info sections,
319 but requires that consumers are able to decompress the results.
321 If unsure, choose DEBUG_INFO_COMPRESSED_NONE.
323 config DEBUG_INFO_COMPRESSED_NONE
324 bool "Don't compress debug information"
326 Don't compress debug info sections.
328 config DEBUG_INFO_COMPRESSED_ZLIB
329 bool "Compress debugging information with zlib"
330 depends on $(cc-option,-gz=zlib)
331 depends on $(ld-option,--compress-debug-sections=zlib)
333 Compress the debug information using zlib. Requires GCC 5.0+ or Clang
334 5.0+, binutils 2.26+, and zlib.
336 Users of dpkg-deb via scripts/package/builddeb may find an increase in
337 size of their debug .deb packages with this config set, due to the
338 debug info being compressed with zlib, then the object files being
339 recompressed with a different compression scheme. But this is still
340 preferable to setting $KDEB_COMPRESS to "none" which would be even
343 config DEBUG_INFO_COMPRESSED_ZSTD
344 bool "Compress debugging information with zstd"
345 depends on $(cc-option,-gz=zstd)
346 depends on $(ld-option,--compress-debug-sections=zstd)
348 Compress the debug information using zstd. This may provide better
349 compression than zlib, for about the same time costs, but requires newer
350 toolchain support. Requires GCC 13.0+ or Clang 16.0+, binutils 2.40+, and
353 endchoice # "Compressed Debug information"
355 config DEBUG_INFO_SPLIT
356 bool "Produce split debuginfo in .dwo files"
357 depends on $(cc-option,-gsplit-dwarf)
359 Generate debug info into separate .dwo files. This significantly
360 reduces the build directory size for builds with DEBUG_INFO,
361 because it stores the information only once on disk in .dwo
362 files instead of multiple times in object files and executables.
363 In addition the debug information is also compressed.
365 Requires recent gcc (4.7+) and recent gdb/binutils.
366 Any tool that packages or reads debug information would need
367 to know about the .dwo files and include them.
368 Incompatible with older versions of ccache.
370 config DEBUG_INFO_BTF
371 bool "Generate BTF typeinfo"
372 depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED
373 depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST
374 depends on BPF_SYSCALL
375 depends on !DEBUG_INFO_DWARF5 || PAHOLE_VERSION >= 121
377 Generate deduplicated BTF type information from DWARF debug info.
378 Turning this on expects presence of pahole tool, which will convert
379 DWARF type info into equivalent deduplicated BTF type info.
381 config PAHOLE_HAS_SPLIT_BTF
382 def_bool PAHOLE_VERSION >= 119
384 config PAHOLE_HAS_BTF_TAG
385 def_bool PAHOLE_VERSION >= 123
386 depends on CC_IS_CLANG
388 Decide whether pahole emits btf_tag attributes (btf_type_tag and
389 btf_decl_tag) or not. Currently only clang compiler implements
390 these attributes, so make the config depend on CC_IS_CLANG.
392 config PAHOLE_HAS_LANG_EXCLUDE
393 def_bool PAHOLE_VERSION >= 124
395 Support for the --lang_exclude flag which makes pahole exclude
396 compilation units from the supplied language. Used in Kbuild to
397 omit Rust CUs which are not supported in version 1.24 of pahole,
398 otherwise it would emit malformed kernel and module binaries when
399 using DEBUG_INFO_BTF_MODULES.
401 config DEBUG_INFO_BTF_MODULES
403 depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF
405 Generate compact split BTF type information for kernel modules.
407 config MODULE_ALLOW_BTF_MISMATCH
408 bool "Allow loading modules with non-matching BTF type info"
409 depends on DEBUG_INFO_BTF_MODULES
411 For modules whose split BTF does not match vmlinux, load without
412 BTF rather than refusing to load. The default behavior with
413 module BTF enabled is to reject modules with such mismatches;
414 this option will still load module BTF where possible but ignore
415 it when a mismatch is found.
418 bool "Provide GDB scripts for kernel debugging"
420 This creates the required links to GDB helper scripts in the
421 build directory. If you load vmlinux into gdb, the helper
422 scripts will be automatically imported by gdb as well, and
423 additional functions are available to analyze a Linux kernel
424 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
430 int "Warn for stack frames larger than"
433 default 2048 if GCC_PLUGIN_LATENT_ENTROPY
434 default 2048 if PARISC
435 default 1536 if (!64BIT && XTENSA)
436 default 1280 if KASAN && !64BIT
437 default 1024 if !64BIT
438 default 2048 if 64BIT
440 Tell the compiler to warn at build time for stack frames larger than this.
441 Setting this too low will cause a lot of warnings.
442 Setting it to 0 disables the warning.
444 config STRIP_ASM_SYMS
445 bool "Strip assembler-generated symbols during link"
448 Strip internal assembler-generated symbols during a link (symbols
449 that look like '.Lxxx') so they don't pollute the output of
450 get_wchan() and suchlike.
453 bool "Generate readable assembler code"
454 depends on DEBUG_KERNEL
457 Disable some compiler optimizations that tend to generate human unreadable
458 assembler output. This may make the kernel slightly slower, but it helps
459 to keep kernel developers who have to stare a lot at assembler listings
462 config HEADERS_INSTALL
463 bool "Install uapi headers to usr/include"
466 This option will install uapi headers (headers exported to user-space)
467 into the usr/include directory for use during the kernel build.
468 This is unneeded for building the kernel itself, but needed for some
469 user-space program samples. It is also needed by some features such
470 as uapi header sanity checks.
472 config DEBUG_SECTION_MISMATCH
473 bool "Enable full Section mismatch analysis"
476 The section mismatch analysis checks if there are illegal
477 references from one section to another section.
478 During linktime or runtime, some sections are dropped;
479 any use of code/data previously in these sections would
480 most likely result in an oops.
481 In the code, functions and variables are annotated with
482 __init,, etc. (see the full list in include/linux/init.h),
483 which results in the code/data being placed in specific sections.
484 The section mismatch analysis is always performed after a full
485 kernel build, and enabling this option causes the following
486 additional step to occur:
487 - Add the option -fno-inline-functions-called-once to gcc commands.
488 When inlining a function annotated with __init in a non-init
489 function, we would lose the section information and thus
490 the analysis would not catch the illegal reference.
491 This option tells gcc to inline less (but it does result in
494 config SECTION_MISMATCH_WARN_ONLY
495 bool "Make section mismatch errors non-fatal"
498 If you say N here, the build process will fail if there are any
499 section mismatch, instead of just throwing warnings.
503 config DEBUG_FORCE_FUNCTION_ALIGN_64B
504 bool "Force all function address 64B aligned"
505 depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC || S390)
506 select FUNCTION_ALIGNMENT_64B
508 There are cases that a commit from one domain changes the function
509 address alignment of other domains, and cause magic performance
510 bump (regression or improvement). Enable this option will help to
511 verify if the bump is caused by function alignment changes, while
512 it will slightly increase the kernel size and affect icache usage.
514 It is mainly for debug and performance tuning use.
517 # Select this config option from the architecture Kconfig, if it
518 # is preferred to always offer frame pointers as a config
519 # option on the architecture (regardless of KERNEL_DEBUG):
521 config ARCH_WANT_FRAME_POINTERS
525 bool "Compile the kernel with frame pointers"
526 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
527 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
529 If you say Y here the resulting kernel image will be slightly
530 larger and slower, but it gives very useful debugging information
531 in case of kernel bugs. (precise oopses/stacktraces/warnings)
536 config STACK_VALIDATION
537 bool "Compile-time stack metadata validation"
538 depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER
542 Validate frame pointer rules at compile-time. This helps ensure that
543 runtime stack traces are more reliable.
545 For more information, see
546 tools/objtool/Documentation/objtool.txt.
548 config NOINSTR_VALIDATION
550 depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY
555 bool "Generate vmlinux.map file when linking"
558 Selecting this option will pass "-Map=vmlinux.map" to ld
559 when linking vmlinux. That file can be useful for verifying
560 and debugging magic section games, and for seeing which
561 pieces of code get eliminated with
562 CONFIG_LD_DEAD_CODE_DATA_ELIMINATION.
564 config DEBUG_FORCE_WEAK_PER_CPU
565 bool "Force weak per-cpu definitions"
566 depends on DEBUG_KERNEL
568 s390 and alpha require percpu variables in modules to be
569 defined weak to work around addressing range issue which
570 puts the following two restrictions on percpu variable
573 1. percpu symbols must be unique whether static or not
574 2. percpu variables can't be defined inside a function
576 To ensure that generic code follows the above rules, this
577 option forces all percpu variables to be defined as weak.
579 endmenu # "Compiler options"
581 menu "Generic Kernel Debugging Instruments"
584 bool "Magic SysRq key"
587 If you say Y here, you will have some control over the system even
588 if the system crashes for example during kernel debugging (e.g., you
589 will be able to flush the buffer cache to disk, reboot the system
590 immediately or dump some status information). This is accomplished
591 by pressing various keys while holding SysRq (Alt+PrintScreen). It
592 also works on a serial console (on PC hardware at least), if you
593 send a BREAK and then within 5 seconds a command keypress. The
594 keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
595 Don't say Y unless you really know what this hack does.
597 config MAGIC_SYSRQ_DEFAULT_ENABLE
598 hex "Enable magic SysRq key functions by default"
599 depends on MAGIC_SYSRQ
602 Specifies which SysRq key functions are enabled by default.
603 This may be set to 1 or 0 to enable or disable them all, or
604 to a bitmask as described in Documentation/admin-guide/sysrq.rst.
606 config MAGIC_SYSRQ_SERIAL
607 bool "Enable magic SysRq key over serial"
608 depends on MAGIC_SYSRQ
611 Many embedded boards have a disconnected TTL level serial which can
612 generate some garbage that can lead to spurious false sysrq detects.
613 This option allows you to decide whether you want to enable the
616 config MAGIC_SYSRQ_SERIAL_SEQUENCE
617 string "Char sequence that enables magic SysRq over serial"
618 depends on MAGIC_SYSRQ_SERIAL
621 Specifies a sequence of characters that can follow BREAK to enable
622 SysRq on a serial console.
624 If unsure, leave an empty string and the option will not be enabled.
627 bool "Debug Filesystem"
629 debugfs is a virtual file system that kernel developers use to put
630 debugging files into. Enable this option to be able to read and
631 write to these files.
633 For detailed documentation on the debugfs API, see
634 Documentation/filesystems/.
639 prompt "Debugfs default access"
641 default DEBUG_FS_ALLOW_ALL
643 This selects the default access restrictions for debugfs.
644 It can be overridden with kernel command line option
645 debugfs=[on,no-mount,off]. The restrictions apply for API access
646 and filesystem registration.
648 config DEBUG_FS_ALLOW_ALL
651 No restrictions apply. Both API and filesystem registration
652 is on. This is the normal default operation.
654 config DEBUG_FS_DISALLOW_MOUNT
655 bool "Do not register debugfs as filesystem"
657 The API is open but filesystem is not loaded. Clients can still do
658 their work and read with debug tools that do not need
661 config DEBUG_FS_ALLOW_NONE
664 Access is off. Clients get -PERM when trying to create nodes in
665 debugfs tree and debugfs is not registered as a filesystem.
666 Client can then back-off or continue without debugfs access.
670 source "lib/Kconfig.kgdb"
671 source "lib/Kconfig.ubsan"
672 source "lib/Kconfig.kcsan"
676 menu "Networking Debugging"
678 source "net/Kconfig.debug"
680 endmenu # "Networking Debugging"
682 menu "Memory Debugging"
684 source "mm/Kconfig.debug"
687 bool "Debug object operations"
688 depends on DEBUG_KERNEL
690 If you say Y here, additional code will be inserted into the
691 kernel to track the life time of various objects and validate
692 the operations on those objects.
694 config DEBUG_OBJECTS_SELFTEST
695 bool "Debug objects selftest"
696 depends on DEBUG_OBJECTS
698 This enables the selftest of the object debug code.
700 config DEBUG_OBJECTS_FREE
701 bool "Debug objects in freed memory"
702 depends on DEBUG_OBJECTS
704 This enables checks whether a k/v free operation frees an area
705 which contains an object which has not been deactivated
706 properly. This can make kmalloc/kfree-intensive workloads
709 config DEBUG_OBJECTS_TIMERS
710 bool "Debug timer objects"
711 depends on DEBUG_OBJECTS
713 If you say Y here, additional code will be inserted into the
714 timer routines to track the life time of timer objects and
715 validate the timer operations.
717 config DEBUG_OBJECTS_WORK
718 bool "Debug work objects"
719 depends on DEBUG_OBJECTS
721 If you say Y here, additional code will be inserted into the
722 work queue routines to track the life time of work objects and
723 validate the work operations.
725 config DEBUG_OBJECTS_RCU_HEAD
726 bool "Debug RCU callbacks objects"
727 depends on DEBUG_OBJECTS
729 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
731 config DEBUG_OBJECTS_PERCPU_COUNTER
732 bool "Debug percpu counter objects"
733 depends on DEBUG_OBJECTS
735 If you say Y here, additional code will be inserted into the
736 percpu counter routines to track the life time of percpu counter
737 objects and validate the percpu counter operations.
739 config DEBUG_OBJECTS_ENABLE_DEFAULT
740 int "debug_objects bootup default value (0-1)"
743 depends on DEBUG_OBJECTS
745 Debug objects boot parameter default value
747 config SHRINKER_DEBUG
748 bool "Enable shrinker debugging support"
751 Say Y to enable the shrinker debugfs interface which provides
752 visibility into the kernel memory shrinkers subsystem.
753 Disable it to avoid an extra memory footprint.
755 config DEBUG_STACK_USAGE
756 bool "Stack utilization instrumentation"
757 depends on DEBUG_KERNEL && !IA64
759 Enables the display of the minimum amount of free stack which each
760 task has ever had available in the sysrq-T and sysrq-P debug output.
762 This option will slow down process creation somewhat.
764 config SCHED_STACK_END_CHECK
765 bool "Detect stack corruption on calls to schedule()"
766 depends on DEBUG_KERNEL
769 This option checks for a stack overrun on calls to schedule().
770 If the stack end location is found to be over written always panic as
771 the content of the corrupted region can no longer be trusted.
772 This is to ensure no erroneous behaviour occurs which could result in
773 data corruption or a sporadic crash at a later stage once the region
774 is examined. The runtime overhead introduced is minimal.
776 config ARCH_HAS_DEBUG_VM_PGTABLE
779 An architecture should select this when it can successfully
780 build and run DEBUG_VM_PGTABLE.
782 config DEBUG_VM_IRQSOFF
783 def_bool DEBUG_VM && !PREEMPT_RT
787 depends on DEBUG_KERNEL
789 Enable this to turn on extended checks in the virtual-memory system
790 that may impact performance.
794 config DEBUG_VM_SHOOT_LAZIES
795 bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation"
797 depends on MMU_LAZY_TLB_SHOOTDOWN
799 Enable additional IPIs that ensure lazy tlb mm references are removed
800 before the mm is freed.
804 config DEBUG_VM_MAPLE_TREE
805 bool "Debug VM maple trees"
807 select DEBUG_MAPLE_TREE
809 Enable VM maple tree debugging information and extra validations.
814 bool "Debug VM red-black trees"
817 Enable VM red-black tree debugging information and extra validations.
821 config DEBUG_VM_PGFLAGS
822 bool "Debug page-flags operations"
825 Enables extra validation on page flags operations.
829 config DEBUG_VM_PGTABLE
830 bool "Debug arch page table for semantics compliance"
832 depends on ARCH_HAS_DEBUG_VM_PGTABLE
833 default y if DEBUG_VM
835 This option provides a debug method which can be used to test
836 architecture page table helper functions on various platforms in
837 verifying if they comply with expected generic MM semantics. This
838 will help architecture code in making sure that any changes or
839 new additions of these helpers still conform to expected
840 semantics of the generic MM. Platforms will have to opt in for
841 this through ARCH_HAS_DEBUG_VM_PGTABLE.
845 config ARCH_HAS_DEBUG_VIRTUAL
849 bool "Debug VM translations"
850 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
852 Enable some costly sanity checks in virtual to page code. This can
853 catch mistakes with virt_to_page() and friends.
857 config DEBUG_NOMMU_REGIONS
858 bool "Debug the global anon/private NOMMU mapping region tree"
859 depends on DEBUG_KERNEL && !MMU
861 This option causes the global tree of anonymous and private mapping
862 regions to be regularly checked for invalid topology.
864 config DEBUG_MEMORY_INIT
865 bool "Debug memory initialisation" if EXPERT
868 Enable this for additional checks during memory initialisation.
869 The sanity checks verify aspects of the VM such as the memory model
870 and other information provided by the architecture. Verbose
871 information will be printed at KERN_DEBUG loglevel depending
872 on the mminit_loglevel= command-line option.
876 config MEMORY_NOTIFIER_ERROR_INJECT
877 tristate "Memory hotplug notifier error injection module"
878 depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION
880 This option provides the ability to inject artificial errors to
881 memory hotplug notifier chain callbacks. It is controlled through
882 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
884 If the notifier call chain should be failed with some events
885 notified, write the error code to "actions/<notifier event>/error".
887 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
889 # cd /sys/kernel/debug/notifier-error-inject/memory
890 # echo -12 > actions/MEM_GOING_OFFLINE/error
891 # echo offline > /sys/devices/system/memory/memoryXXX/state
892 bash: echo: write error: Cannot allocate memory
894 To compile this code as a module, choose M here: the module will
895 be called memory-notifier-error-inject.
899 config DEBUG_PER_CPU_MAPS
900 bool "Debug access to per_cpu maps"
901 depends on DEBUG_KERNEL
904 Say Y to verify that the per_cpu map being accessed has
905 been set up. This adds a fair amount of code to kernel memory
906 and decreases performance.
910 config DEBUG_KMAP_LOCAL
911 bool "Debug kmap_local temporary mappings"
912 depends on DEBUG_KERNEL && KMAP_LOCAL
914 This option enables additional error checking for the kmap_local
915 infrastructure. Disable for production use.
917 config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
920 config DEBUG_KMAP_LOCAL_FORCE_MAP
921 bool "Enforce kmap_local temporary mappings"
922 depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
924 select DEBUG_KMAP_LOCAL
926 This option enforces temporary mappings through the kmap_local
927 mechanism for non-highmem pages and on non-highmem systems.
928 Disable this for production systems!
931 bool "Highmem debugging"
932 depends on DEBUG_KERNEL && HIGHMEM
933 select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
934 select DEBUG_KMAP_LOCAL
936 This option enables additional error checking for high memory
937 systems. Disable for production systems.
939 config HAVE_DEBUG_STACKOVERFLOW
942 config DEBUG_STACKOVERFLOW
943 bool "Check for stack overflows"
944 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
946 Say Y here if you want to check for overflows of kernel, IRQ
947 and exception stacks (if your architecture uses them). This
948 option will show detailed messages if free stack space drops
949 below a certain limit.
951 These kinds of bugs usually occur when call-chains in the
952 kernel get too deep, especially when interrupts are
955 Use this in cases where you see apparently random memory
956 corruption, especially if it appears in 'struct thread_info'
958 If in doubt, say "N".
960 source "lib/Kconfig.kasan"
961 source "lib/Kconfig.kfence"
962 source "lib/Kconfig.kmsan"
964 endmenu # "Memory Debugging"
967 bool "Debug shared IRQ handlers"
968 depends on DEBUG_KERNEL
970 Enable this to generate a spurious interrupt just before a shared
971 interrupt handler is deregistered (generating one when registering
972 is currently disabled). Drivers need to handle this correctly. Some
973 don't and need to be caught.
975 menu "Debug Oops, Lockups and Hangs"
980 Say Y here to enable the kernel to panic when it oopses. This
981 has the same effect as setting oops=panic on the kernel command
984 This feature is useful to ensure that the kernel does not do
985 anything erroneous after an oops which could result in data
986 corruption or other issues.
990 config PANIC_ON_OOPS_VALUE
993 default 0 if !PANIC_ON_OOPS
994 default 1 if PANIC_ON_OOPS
1000 Set the timeout value (in seconds) until a reboot occurs when
1001 the kernel panics. If n = 0, then we wait forever. A timeout
1002 value n > 0 will wait n seconds before rebooting, while a timeout
1003 value n < 0 will reboot immediately.
1005 config LOCKUP_DETECTOR
1008 config SOFTLOCKUP_DETECTOR
1009 bool "Detect Soft Lockups"
1010 depends on DEBUG_KERNEL && !S390
1011 select LOCKUP_DETECTOR
1013 Say Y here to enable the kernel to act as a watchdog to detect
1016 Softlockups are bugs that cause the kernel to loop in kernel
1017 mode for more than 20 seconds, without giving other tasks a
1018 chance to run. The current stack trace is displayed upon
1019 detection and the system will stay locked up.
1021 config BOOTPARAM_SOFTLOCKUP_PANIC
1022 bool "Panic (Reboot) On Soft Lockups"
1023 depends on SOFTLOCKUP_DETECTOR
1025 Say Y here to enable the kernel to panic on "soft lockups",
1026 which are bugs that cause the kernel to loop in kernel
1027 mode for more than 20 seconds (configurable using the watchdog_thresh
1028 sysctl), without giving other tasks a chance to run.
1030 The panic can be used in combination with panic_timeout,
1031 to cause the system to reboot automatically after a
1032 lockup has been detected. This feature is useful for
1033 high-availability systems that have uptime guarantees and
1034 where a lockup must be resolved ASAP.
1038 config HAVE_HARDLOCKUP_DETECTOR_BUDDY
1044 # Global switch whether to build a hardlockup detector at all. It is available
1045 # only when the architecture supports at least one implementation. There are
1046 # two exceptions. The hardlockup detector is never enabled on:
1048 # s390: it reported many false positives there
1050 # sparc64: has a custom implementation which is not using the common
1051 # hardlockup command line options and sysctl interface.
1053 config HARDLOCKUP_DETECTOR
1054 bool "Detect Hard Lockups"
1055 depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64
1056 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH
1057 imply HARDLOCKUP_DETECTOR_PERF
1058 imply HARDLOCKUP_DETECTOR_BUDDY
1059 imply HARDLOCKUP_DETECTOR_ARCH
1060 select LOCKUP_DETECTOR
1063 Say Y here to enable the kernel to act as a watchdog to detect
1066 Hardlockups are bugs that cause the CPU to loop in kernel mode
1067 for more than 10 seconds, without letting other interrupts have a
1068 chance to run. The current stack trace is displayed upon detection
1069 and the system will stay locked up.
1072 # Note that arch-specific variants are always preferred.
1074 config HARDLOCKUP_DETECTOR_PREFER_BUDDY
1075 bool "Prefer the buddy CPU hardlockup detector"
1076 depends on HARDLOCKUP_DETECTOR
1077 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY
1078 depends on !HAVE_HARLOCKUP_DETECTOR_ARCH
1080 Say Y here to prefer the buddy hardlockup detector over the perf one.
1082 With the buddy detector, each CPU uses its softlockup hrtimer
1083 to check that the next CPU is processing hrtimer interrupts by
1084 verifying that a counter is increasing.
1086 This hardlockup detector is useful on systems that don't have
1087 an arch-specific hardlockup detector or if resources needed
1088 for the hardlockup detector are better used for other things.
1090 config HARDLOCKUP_DETECTOR_PERF
1092 depends on HARDLOCKUP_DETECTOR
1093 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY
1094 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1095 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1097 config HARDLOCKUP_DETECTOR_BUDDY
1099 depends on HARDLOCKUP_DETECTOR
1100 depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY
1101 depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY
1102 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1103 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1105 config HARDLOCKUP_DETECTOR_ARCH
1107 depends on HARDLOCKUP_DETECTOR
1108 depends on HAVE_HARDLOCKUP_DETECTOR_ARCH
1110 The arch-specific implementation of the hardlockup detector will
1114 # Both the "perf" and "buddy" hardlockup detectors count hrtimer
1115 # interrupts. This config enables functions managing this common code.
1117 config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1119 select SOFTLOCKUP_DETECTOR
1122 # Enables a timestamp based low pass filter to compensate for perf based
1123 # hard lockup detection which runs too fast due to turbo modes.
1125 config HARDLOCKUP_CHECK_TIMESTAMP
1128 config BOOTPARAM_HARDLOCKUP_PANIC
1129 bool "Panic (Reboot) On Hard Lockups"
1130 depends on HARDLOCKUP_DETECTOR
1132 Say Y here to enable the kernel to panic on "hard lockups",
1133 which are bugs that cause the kernel to loop in kernel
1134 mode with interrupts disabled for more than 10 seconds (configurable
1135 using the watchdog_thresh sysctl).
1139 config DETECT_HUNG_TASK
1140 bool "Detect Hung Tasks"
1141 depends on DEBUG_KERNEL
1142 default SOFTLOCKUP_DETECTOR
1144 Say Y here to enable the kernel to detect "hung tasks",
1145 which are bugs that cause the task to be stuck in
1146 uninterruptible "D" state indefinitely.
1148 When a hung task is detected, the kernel will print the
1149 current stack trace (which you should report), but the
1150 task will stay in uninterruptible state. If lockdep is
1151 enabled then all held locks will also be reported. This
1152 feature has negligible overhead.
1154 config DEFAULT_HUNG_TASK_TIMEOUT
1155 int "Default timeout for hung task detection (in seconds)"
1156 depends on DETECT_HUNG_TASK
1159 This option controls the default timeout (in seconds) used
1160 to determine when a task has become non-responsive and should
1163 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
1164 sysctl or by writing a value to
1165 /proc/sys/kernel/hung_task_timeout_secs.
1167 A timeout of 0 disables the check. The default is two minutes.
1168 Keeping the default should be fine in most cases.
1170 config BOOTPARAM_HUNG_TASK_PANIC
1171 bool "Panic (Reboot) On Hung Tasks"
1172 depends on DETECT_HUNG_TASK
1174 Say Y here to enable the kernel to panic on "hung tasks",
1175 which are bugs that cause the kernel to leave a task stuck
1176 in uninterruptible "D" state.
1178 The panic can be used in combination with panic_timeout,
1179 to cause the system to reboot automatically after a
1180 hung task has been detected. This feature is useful for
1181 high-availability systems that have uptime guarantees and
1182 where a hung tasks must be resolved ASAP.
1187 bool "Detect Workqueue Stalls"
1188 depends on DEBUG_KERNEL
1190 Say Y here to enable stall detection on workqueues. If a
1191 worker pool doesn't make forward progress on a pending work
1192 item for over a given amount of time, 30s by default, a
1193 warning message is printed along with dump of workqueue
1194 state. This can be configured through kernel parameter
1195 "workqueue.watchdog_thresh" and its sysfs counterpart.
1198 tristate "Test module to generate lockups"
1201 This builds the "test_lockup" module that helps to make sure
1202 that watchdogs and lockup detectors are working properly.
1204 Depending on module parameters it could emulate soft or hard
1205 lockup, "hung task", or locking arbitrary lock for a long time.
1206 Also it could generate series of lockups with cooling-down periods.
1210 endmenu # "Debug lockups and hangs"
1212 menu "Scheduler Debugging"
1215 bool "Collect scheduler debugging info"
1216 depends on DEBUG_KERNEL && DEBUG_FS
1219 If you say Y here, the /sys/kernel/debug/sched file will be provided
1220 that can help debug the scheduler. The runtime overhead of this
1228 bool "Collect scheduler statistics"
1229 depends on DEBUG_KERNEL && PROC_FS
1232 If you say Y here, additional code will be inserted into the
1233 scheduler and related routines to collect statistics about
1234 scheduler behavior and provide them in /proc/schedstat. These
1235 stats may be useful for both tuning and debugging the scheduler
1236 If you aren't debugging the scheduler or trying to tune a specific
1237 application, you can say N to avoid the very slight overhead
1242 config DEBUG_TIMEKEEPING
1243 bool "Enable extra timekeeping sanity checking"
1245 This option will enable additional timekeeping sanity checks
1246 which may be helpful when diagnosing issues where timekeeping
1247 problems are suspected.
1249 This may include checks in the timekeeping hotpaths, so this
1250 option may have a (very small) performance impact to some
1255 config DEBUG_PREEMPT
1256 bool "Debug preemptible kernel"
1257 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT
1259 If you say Y here then the kernel will use a debug variant of the
1260 commonly used smp_processor_id() function and will print warnings
1261 if kernel code uses it in a preemption-unsafe way. Also, the kernel
1262 will detect preemption count underflows.
1264 This option has potential to introduce high runtime overhead,
1265 depending on workload as it triggers debugging routines for each
1266 this_cpu operation. It should only be used for debugging purposes.
1268 menu "Lock Debugging (spinlocks, mutexes, etc...)"
1270 config LOCK_DEBUGGING_SUPPORT
1272 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1275 config PROVE_LOCKING
1276 bool "Lock debugging: prove locking correctness"
1277 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1279 select DEBUG_SPINLOCK
1280 select DEBUG_MUTEXES if !PREEMPT_RT
1281 select DEBUG_RT_MUTEXES if RT_MUTEXES
1283 select DEBUG_WW_MUTEX_SLOWPATH
1284 select DEBUG_LOCK_ALLOC
1285 select PREEMPT_COUNT if !ARCH_NO_PREEMPT
1286 select TRACE_IRQFLAGS
1289 This feature enables the kernel to prove that all locking
1290 that occurs in the kernel runtime is mathematically
1291 correct: that under no circumstance could an arbitrary (and
1292 not yet triggered) combination of observed locking
1293 sequences (on an arbitrary number of CPUs, running an
1294 arbitrary number of tasks and interrupt contexts) cause a
1297 In short, this feature enables the kernel to report locking
1298 related deadlocks before they actually occur.
1300 The proof does not depend on how hard and complex a
1301 deadlock scenario would be to trigger: how many
1302 participant CPUs, tasks and irq-contexts would be needed
1303 for it to trigger. The proof also does not depend on
1304 timing: if a race and a resulting deadlock is possible
1305 theoretically (no matter how unlikely the race scenario
1306 is), it will be proven so and will immediately be
1307 reported by the kernel (once the event is observed that
1308 makes the deadlock theoretically possible).
1310 If a deadlock is impossible (i.e. the locking rules, as
1311 observed by the kernel, are mathematically correct), the
1312 kernel reports nothing.
1314 NOTE: this feature can also be enabled for rwlocks, mutexes
1315 and rwsems - in which case all dependencies between these
1316 different locking variants are observed and mapped too, and
1317 the proof of observed correctness is also maintained for an
1318 arbitrary combination of these separate locking variants.
1320 For more details, see Documentation/locking/lockdep-design.rst.
1322 config PROVE_RAW_LOCK_NESTING
1323 bool "Enable raw_spinlock - spinlock nesting checks"
1324 depends on PROVE_LOCKING
1327 Enable the raw_spinlock vs. spinlock nesting checks which ensure
1328 that the lock nesting rules for PREEMPT_RT enabled kernels are
1331 NOTE: There are known nesting problems. So if you enable this
1332 option expect lockdep splats until these problems have been fully
1333 addressed which is work in progress. This config switch allows to
1334 identify and analyze these problems. It will be removed and the
1335 check permanently enabled once the main issues have been fixed.
1337 If unsure, select N.
1340 bool "Lock usage statistics"
1341 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1343 select DEBUG_SPINLOCK
1344 select DEBUG_MUTEXES if !PREEMPT_RT
1345 select DEBUG_RT_MUTEXES if RT_MUTEXES
1346 select DEBUG_LOCK_ALLOC
1349 This feature enables tracking lock contention points
1351 For more details, see Documentation/locking/lockstat.rst
1353 This also enables lock events required by "perf lock",
1355 If you want to use "perf lock", you also need to turn on
1356 CONFIG_EVENT_TRACING.
1358 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1359 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1361 config DEBUG_RT_MUTEXES
1362 bool "RT Mutex debugging, deadlock detection"
1363 depends on DEBUG_KERNEL && RT_MUTEXES
1365 This allows rt mutex semantics violations and rt mutex related
1366 deadlocks (lockups) to be detected and reported automatically.
1368 config DEBUG_SPINLOCK
1369 bool "Spinlock and rw-lock debugging: basic checks"
1370 depends on DEBUG_KERNEL
1371 select UNINLINE_SPIN_UNLOCK
1373 Say Y here and build SMP to catch missing spinlock initialization
1374 and certain other kinds of spinlock errors commonly made. This is
1375 best used in conjunction with the NMI watchdog so that spinlock
1376 deadlocks are also debuggable.
1378 config DEBUG_MUTEXES
1379 bool "Mutex debugging: basic checks"
1380 depends on DEBUG_KERNEL && !PREEMPT_RT
1382 This feature allows mutex semantics violations to be detected and
1385 config DEBUG_WW_MUTEX_SLOWPATH
1386 bool "Wait/wound mutex debugging: Slowpath testing"
1387 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1388 select DEBUG_LOCK_ALLOC
1389 select DEBUG_SPINLOCK
1390 select DEBUG_MUTEXES if !PREEMPT_RT
1391 select DEBUG_RT_MUTEXES if PREEMPT_RT
1393 This feature enables slowpath testing for w/w mutex users by
1394 injecting additional -EDEADLK wound/backoff cases. Together with
1395 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1396 will test all possible w/w mutex interface abuse with the
1397 exception of simply not acquiring all the required locks.
1398 Note that this feature can introduce significant overhead, so
1399 it really should not be enabled in a production or distro kernel,
1400 even a debug kernel. If you are a driver writer, enable it. If
1401 you are a distro, do not.
1404 bool "RW Semaphore debugging: basic checks"
1405 depends on DEBUG_KERNEL
1407 This debugging feature allows mismatched rw semaphore locks
1408 and unlocks to be detected and reported.
1410 config DEBUG_LOCK_ALLOC
1411 bool "Lock debugging: detect incorrect freeing of live locks"
1412 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1413 select DEBUG_SPINLOCK
1414 select DEBUG_MUTEXES if !PREEMPT_RT
1415 select DEBUG_RT_MUTEXES if RT_MUTEXES
1418 This feature will check whether any held lock (spinlock, rwlock,
1419 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1420 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1421 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1422 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1423 held during task exit.
1427 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1432 config LOCKDEP_SMALL
1436 int "Bitsize for MAX_LOCKDEP_ENTRIES"
1437 depends on LOCKDEP && !LOCKDEP_SMALL
1441 Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message.
1443 config LOCKDEP_CHAINS_BITS
1444 int "Bitsize for MAX_LOCKDEP_CHAINS"
1445 depends on LOCKDEP && !LOCKDEP_SMALL
1449 Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message.
1451 config LOCKDEP_STACK_TRACE_BITS
1452 int "Bitsize for MAX_STACK_TRACE_ENTRIES"
1453 depends on LOCKDEP && !LOCKDEP_SMALL
1457 Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message.
1459 config LOCKDEP_STACK_TRACE_HASH_BITS
1460 int "Bitsize for STACK_TRACE_HASH_SIZE"
1461 depends on LOCKDEP && !LOCKDEP_SMALL
1465 Try increasing this value if you need large STACK_TRACE_HASH_SIZE.
1467 config LOCKDEP_CIRCULAR_QUEUE_BITS
1468 int "Bitsize for elements in circular_queue struct"
1473 Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure.
1475 config DEBUG_LOCKDEP
1476 bool "Lock dependency engine debugging"
1477 depends on DEBUG_KERNEL && LOCKDEP
1478 select DEBUG_IRQFLAGS
1480 If you say Y here, the lock dependency engine will do
1481 additional runtime checks to debug itself, at the price
1482 of more runtime overhead.
1484 config DEBUG_ATOMIC_SLEEP
1485 bool "Sleep inside atomic section checking"
1486 select PREEMPT_COUNT
1487 depends on DEBUG_KERNEL
1488 depends on !ARCH_NO_PREEMPT
1490 If you say Y here, various routines which may sleep will become very
1491 noisy if they are called inside atomic sections: when a spinlock is
1492 held, inside an rcu read side critical section, inside preempt disabled
1493 sections, inside an interrupt, etc...
1495 config DEBUG_LOCKING_API_SELFTESTS
1496 bool "Locking API boot-time self-tests"
1497 depends on DEBUG_KERNEL
1499 Say Y here if you want the kernel to run a short self-test during
1500 bootup. The self-test checks whether common types of locking bugs
1501 are detected by debugging mechanisms or not. (if you disable
1502 lock debugging then those bugs won't be detected of course.)
1503 The following locking APIs are covered: spinlocks, rwlocks,
1506 config LOCK_TORTURE_TEST
1507 tristate "torture tests for locking"
1508 depends on DEBUG_KERNEL
1511 This option provides a kernel module that runs torture tests
1512 on kernel locking primitives. The kernel module may be built
1513 after the fact on the running kernel to be tested, if desired.
1515 Say Y here if you want kernel locking-primitive torture tests
1516 to be built into the kernel.
1517 Say M if you want these torture tests to build as a module.
1518 Say N if you are unsure.
1520 config WW_MUTEX_SELFTEST
1521 tristate "Wait/wound mutex selftests"
1523 This option provides a kernel module that runs tests on the
1524 on the struct ww_mutex locking API.
1526 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1527 with this test harness.
1529 Say M if you want these self tests to build as a module.
1530 Say N if you are unsure.
1532 config SCF_TORTURE_TEST
1533 tristate "torture tests for smp_call_function*()"
1534 depends on DEBUG_KERNEL
1537 This option provides a kernel module that runs torture tests
1538 on the smp_call_function() family of primitives. The kernel
1539 module may be built after the fact on the running kernel to
1540 be tested, if desired.
1542 config CSD_LOCK_WAIT_DEBUG
1543 bool "Debugging for csd_lock_wait(), called from smp_call_function*()"
1544 depends on DEBUG_KERNEL
1548 This option enables debug prints when CPUs are slow to respond
1549 to the smp_call_function*() IPI wrappers. These debug prints
1550 include the IPI handler function currently executing (if any)
1551 and relevant stack traces.
1553 config CSD_LOCK_WAIT_DEBUG_DEFAULT
1554 bool "Default csd_lock_wait() debugging on at boot time"
1555 depends on CSD_LOCK_WAIT_DEBUG
1559 This option causes the csdlock_debug= kernel boot parameter to
1560 default to 1 (basic debugging) instead of 0 (no debugging).
1562 endmenu # lock debugging
1564 config TRACE_IRQFLAGS
1565 depends on TRACE_IRQFLAGS_SUPPORT
1568 Enables hooks to interrupt enabling and disabling for
1569 either tracing or lock debugging.
1571 config TRACE_IRQFLAGS_NMI
1573 depends on TRACE_IRQFLAGS
1574 depends on TRACE_IRQFLAGS_NMI_SUPPORT
1576 config NMI_CHECK_CPU
1577 bool "Debugging for CPUs failing to respond to backtrace requests"
1578 depends on DEBUG_KERNEL
1582 Enables debug prints when a CPU fails to respond to a given
1583 backtrace NMI. These prints provide some reasons why a CPU
1584 might legitimately be failing to respond, for example, if it
1585 is offline of if ignore_nmis is set.
1587 config DEBUG_IRQFLAGS
1588 bool "Debug IRQ flag manipulation"
1590 Enables checks for potentially unsafe enabling or disabling of
1591 interrupts, such as calling raw_local_irq_restore() when interrupts
1595 bool "Stack backtrace support"
1596 depends on STACKTRACE_SUPPORT
1598 This option causes the kernel to create a /proc/pid/stack for
1599 every process, showing its current stack trace.
1600 It is also used by various kernel debugging features that require
1601 stack trace generation.
1603 config WARN_ALL_UNSEEDED_RANDOM
1604 bool "Warn for all uses of unseeded randomness"
1607 Some parts of the kernel contain bugs relating to their use of
1608 cryptographically secure random numbers before it's actually possible
1609 to generate those numbers securely. This setting ensures that these
1610 flaws don't go unnoticed, by enabling a message, should this ever
1611 occur. This will allow people with obscure setups to know when things
1612 are going wrong, so that they might contact developers about fixing
1615 Unfortunately, on some models of some architectures getting
1616 a fully seeded CRNG is extremely difficult, and so this can
1617 result in dmesg getting spammed for a surprisingly long
1618 time. This is really bad from a security perspective, and
1619 so architecture maintainers really need to do what they can
1620 to get the CRNG seeded sooner after the system is booted.
1621 However, since users cannot do anything actionable to
1622 address this, by default this option is disabled.
1624 Say Y here if you want to receive warnings for all uses of
1625 unseeded randomness. This will be of use primarily for
1626 those developers interested in improving the security of
1627 Linux kernels running on their architecture (or
1630 config DEBUG_KOBJECT
1631 bool "kobject debugging"
1632 depends on DEBUG_KERNEL
1634 If you say Y here, some extra kobject debugging messages will be sent
1637 config DEBUG_KOBJECT_RELEASE
1638 bool "kobject release debugging"
1639 depends on DEBUG_OBJECTS_TIMERS
1641 kobjects are reference counted objects. This means that their
1642 last reference count put is not predictable, and the kobject can
1643 live on past the point at which a driver decides to drop its
1644 initial reference to the kobject gained on allocation. An
1645 example of this would be a struct device which has just been
1648 However, some buggy drivers assume that after such an operation,
1649 the memory backing the kobject can be immediately freed. This
1650 goes completely against the principles of a refcounted object.
1652 If you say Y here, the kernel will delay the release of kobjects
1653 on the last reference count to improve the visibility of this
1654 kind of kobject release bug.
1656 config HAVE_DEBUG_BUGVERBOSE
1659 menu "Debug kernel data structures"
1662 bool "Debug linked list manipulation"
1663 depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION
1665 Enable this to turn on extended checks in the linked-list
1671 bool "Debug priority linked list manipulation"
1672 depends on DEBUG_KERNEL
1674 Enable this to turn on extended checks in the priority-ordered
1675 linked-list (plist) walking routines. This checks the entire
1676 list multiple times during each manipulation.
1681 bool "Debug SG table operations"
1682 depends on DEBUG_KERNEL
1684 Enable this to turn on checks on scatter-gather tables. This can
1685 help find problems with drivers that do not properly initialize
1690 config DEBUG_NOTIFIERS
1691 bool "Debug notifier call chains"
1692 depends on DEBUG_KERNEL
1694 Enable this to turn on sanity checking for notifier call chains.
1695 This is most useful for kernel developers to make sure that
1696 modules properly unregister themselves from notifier chains.
1697 This is a relatively cheap check but if you care about maximum
1700 config BUG_ON_DATA_CORRUPTION
1701 bool "Trigger a BUG when data corruption is detected"
1704 Select this option if the kernel should BUG when it encounters
1705 data corruption in kernel memory structures when they get checked
1710 config DEBUG_MAPLE_TREE
1711 bool "Debug maple trees"
1712 depends on DEBUG_KERNEL
1714 Enable maple tree debugging information and extra validations.
1720 config DEBUG_CREDENTIALS
1721 bool "Debug credential management"
1722 depends on DEBUG_KERNEL
1724 Enable this to turn on some debug checking for credential
1725 management. The additional code keeps track of the number of
1726 pointers from task_structs to any given cred struct, and checks to
1727 see that this number never exceeds the usage count of the cred
1730 Furthermore, if SELinux is enabled, this also checks that the
1731 security pointer in the cred struct is never seen to be invalid.
1735 source "kernel/rcu/Kconfig.debug"
1737 config DEBUG_WQ_FORCE_RR_CPU
1738 bool "Force round-robin CPU selection for unbound work items"
1739 depends on DEBUG_KERNEL
1742 Workqueue used to implicitly guarantee that work items queued
1743 without explicit CPU specified are put on the local CPU. This
1744 guarantee is no longer true and while local CPU is still
1745 preferred work items may be put on foreign CPUs. Kernel
1746 parameter "workqueue.debug_force_rr_cpu" is added to force
1747 round-robin CPU selection to flush out usages which depend on the
1748 now broken guarantee. This config option enables the debug
1749 feature by default. When enabled, memory and cache locality will
1752 config CPU_HOTPLUG_STATE_CONTROL
1753 bool "Enable CPU hotplug state control"
1754 depends on DEBUG_KERNEL
1755 depends on HOTPLUG_CPU
1758 Allows to write steps between "offline" and "online" to the CPUs
1759 sysfs target file so states can be stepped granular. This is a debug
1760 option for now as the hotplug machinery cannot be stopped and
1761 restarted at arbitrary points yet.
1763 Say N if your are unsure.
1766 bool "Latency measuring infrastructure"
1767 depends on DEBUG_KERNEL
1768 depends on STACKTRACE_SUPPORT
1770 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
1776 Enable this option if you want to use the LatencyTOP tool
1777 to find out which userspace is blocking on what kernel operations.
1779 config DEBUG_CGROUP_REF
1780 bool "Disable inlining of cgroup css reference count functions"
1781 depends on DEBUG_KERNEL
1786 Force cgroup css reference count functions to not be inlined so
1787 that they can be kprobed for debugging.
1789 source "kernel/trace/Kconfig"
1791 config PROVIDE_OHCI1394_DMA_INIT
1792 bool "Remote debugging over FireWire early on boot"
1793 depends on PCI && X86
1795 If you want to debug problems which hang or crash the kernel early
1796 on boot and the crashing machine has a FireWire port, you can use
1797 this feature to remotely access the memory of the crashed machine
1798 over FireWire. This employs remote DMA as part of the OHCI1394
1799 specification which is now the standard for FireWire controllers.
1801 With remote DMA, you can monitor the printk buffer remotely using
1802 firescope and access all memory below 4GB using fireproxy from gdb.
1803 Even controlling a kernel debugger is possible using remote DMA.
1807 If ohci1394_dma=early is used as boot parameter, it will initialize
1808 all OHCI1394 controllers which are found in the PCI config space.
1810 As all changes to the FireWire bus such as enabling and disabling
1811 devices cause a bus reset and thereby disable remote DMA for all
1812 devices, be sure to have the cable plugged and FireWire enabled on
1813 the debugging host before booting the debug target for debugging.
1815 This code (~1k) is freed after boot. By then, the firewire stack
1816 in charge of the OHCI-1394 controllers should be used instead.
1818 See Documentation/core-api/debugging-via-ohci1394.rst for more information.
1820 source "samples/Kconfig"
1822 config ARCH_HAS_DEVMEM_IS_ALLOWED
1825 config STRICT_DEVMEM
1826 bool "Filter access to /dev/mem"
1827 depends on MMU && DEVMEM
1828 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED
1829 default y if PPC || X86 || ARM64
1831 If this option is disabled, you allow userspace (root) access to all
1832 of memory, including kernel and userspace memory. Accidental
1833 access to this is obviously disastrous, but specific access can
1834 be used by people debugging the kernel. Note that with PAT support
1835 enabled, even in this case there are restrictions on /dev/mem
1836 use due to the cache aliasing requirements.
1838 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
1839 file only allows userspace access to PCI space and the BIOS code and
1840 data regions. This is sufficient for dosemu and X and all common
1845 config IO_STRICT_DEVMEM
1846 bool "Filter I/O access to /dev/mem"
1847 depends on STRICT_DEVMEM
1849 If this option is disabled, you allow userspace (root) access to all
1850 io-memory regardless of whether a driver is actively using that
1851 range. Accidental access to this is obviously disastrous, but
1852 specific access can be used by people debugging kernel drivers.
1854 If this option is switched on, the /dev/mem file only allows
1855 userspace access to *idle* io-memory ranges (see /proc/iomem) This
1856 may break traditional users of /dev/mem (dosemu, legacy X, etc...)
1857 if the driver using a given range cannot be disabled.
1861 menu "$(SRCARCH) Debugging"
1863 source "arch/$(SRCARCH)/Kconfig.debug"
1867 menu "Kernel Testing and Coverage"
1869 source "lib/kunit/Kconfig"
1871 config NOTIFIER_ERROR_INJECTION
1872 tristate "Notifier error injection"
1873 depends on DEBUG_KERNEL
1876 This option provides the ability to inject artificial errors to
1877 specified notifier chain callbacks. It is useful to test the error
1878 handling of notifier call chain failures.
1882 config PM_NOTIFIER_ERROR_INJECT
1883 tristate "PM notifier error injection module"
1884 depends on PM && NOTIFIER_ERROR_INJECTION
1885 default m if PM_DEBUG
1887 This option provides the ability to inject artificial errors to
1888 PM notifier chain callbacks. It is controlled through debugfs
1889 interface /sys/kernel/debug/notifier-error-inject/pm
1891 If the notifier call chain should be failed with some events
1892 notified, write the error code to "actions/<notifier event>/error".
1894 Example: Inject PM suspend error (-12 = -ENOMEM)
1896 # cd /sys/kernel/debug/notifier-error-inject/pm/
1897 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1898 # echo mem > /sys/power/state
1899 bash: echo: write error: Cannot allocate memory
1901 To compile this code as a module, choose M here: the module will
1902 be called pm-notifier-error-inject.
1906 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1907 tristate "OF reconfig notifier error injection module"
1908 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1910 This option provides the ability to inject artificial errors to
1911 OF reconfig notifier chain callbacks. It is controlled
1912 through debugfs interface under
1913 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1915 If the notifier call chain should be failed with some events
1916 notified, write the error code to "actions/<notifier event>/error".
1918 To compile this code as a module, choose M here: the module will
1919 be called of-reconfig-notifier-error-inject.
1923 config NETDEV_NOTIFIER_ERROR_INJECT
1924 tristate "Netdev notifier error injection module"
1925 depends on NET && NOTIFIER_ERROR_INJECTION
1927 This option provides the ability to inject artificial errors to
1928 netdevice notifier chain callbacks. It is controlled through debugfs
1929 interface /sys/kernel/debug/notifier-error-inject/netdev
1931 If the notifier call chain should be failed with some events
1932 notified, write the error code to "actions/<notifier event>/error".
1934 Example: Inject netdevice mtu change error (-22 = -EINVAL)
1936 # cd /sys/kernel/debug/notifier-error-inject/netdev
1937 # echo -22 > actions/NETDEV_CHANGEMTU/error
1938 # ip link set eth0 mtu 1024
1939 RTNETLINK answers: Invalid argument
1941 To compile this code as a module, choose M here: the module will
1942 be called netdev-notifier-error-inject.
1946 config FUNCTION_ERROR_INJECTION
1947 bool "Fault-injections of functions"
1948 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
1950 Add fault injections into various functions that are annotated with
1951 ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return
1952 value of these functions. This is useful to test error paths of code.
1956 config FAULT_INJECTION
1957 bool "Fault-injection framework"
1958 depends on DEBUG_KERNEL
1960 Provide fault-injection framework.
1961 For more details, see Documentation/fault-injection/.
1964 bool "Fault-injection capability for kmalloc"
1965 depends on FAULT_INJECTION
1966 depends on SLAB || SLUB
1968 Provide fault-injection capability for kmalloc.
1970 config FAIL_PAGE_ALLOC
1971 bool "Fault-injection capability for alloc_pages()"
1972 depends on FAULT_INJECTION
1974 Provide fault-injection capability for alloc_pages().
1976 config FAULT_INJECTION_USERCOPY
1977 bool "Fault injection capability for usercopy functions"
1978 depends on FAULT_INJECTION
1980 Provides fault-injection capability to inject failures
1981 in usercopy functions (copy_from_user(), get_user(), ...).
1983 config FAIL_MAKE_REQUEST
1984 bool "Fault-injection capability for disk IO"
1985 depends on FAULT_INJECTION && BLOCK
1987 Provide fault-injection capability for disk IO.
1989 config FAIL_IO_TIMEOUT
1990 bool "Fault-injection capability for faking disk interrupts"
1991 depends on FAULT_INJECTION && BLOCK
1993 Provide fault-injection capability on end IO handling. This
1994 will make the block layer "forget" an interrupt as configured,
1995 thus exercising the error handling.
1997 Only works with drivers that use the generic timeout handling,
1998 for others it won't do anything.
2001 bool "Fault-injection capability for futexes"
2003 depends on FAULT_INJECTION && FUTEX
2005 Provide fault-injection capability for futexes.
2007 config FAULT_INJECTION_DEBUG_FS
2008 bool "Debugfs entries for fault-injection capabilities"
2009 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
2011 Enable configuration of fault-injection capabilities via debugfs.
2013 config FAIL_FUNCTION
2014 bool "Fault-injection capability for functions"
2015 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
2017 Provide function-based fault-injection capability.
2018 This will allow you to override a specific function with a return
2019 with given return value. As a result, function caller will see
2020 an error value and have to handle it. This is useful to test the
2021 error handling in various subsystems.
2023 config FAIL_MMC_REQUEST
2024 bool "Fault-injection capability for MMC IO"
2025 depends on FAULT_INJECTION_DEBUG_FS && MMC
2027 Provide fault-injection capability for MMC IO.
2028 This will make the mmc core return data errors. This is
2029 useful to test the error handling in the mmc block device
2030 and to test how the mmc host driver handles retries from
2034 bool "Fault-injection capability for SunRPC"
2035 depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG
2037 Provide fault-injection capability for SunRPC and
2040 config FAULT_INJECTION_CONFIGFS
2041 bool "Configfs interface for fault-injection capabilities"
2042 depends on FAULT_INJECTION
2045 This option allows configfs-based drivers to dynamically configure
2046 fault-injection via configfs. Each parameter for driver-specific
2047 fault-injection can be made visible as a configfs attribute in a
2051 config FAULT_INJECTION_STACKTRACE_FILTER
2052 bool "stacktrace filter for fault-injection capabilities"
2053 depends on FAULT_INJECTION
2054 depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT
2056 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
2058 Provide stacktrace filter for fault-injection capabilities
2060 config ARCH_HAS_KCOV
2063 An architecture should select this when it can successfully
2064 build and run with CONFIG_KCOV. This typically requires
2065 disabling instrumentation for some early boot code.
2067 config CC_HAS_SANCOV_TRACE_PC
2068 def_bool $(cc-option,-fsanitize-coverage=trace-pc)
2072 bool "Code coverage for fuzzing"
2073 depends on ARCH_HAS_KCOV
2074 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
2075 depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \
2076 GCC_VERSION >= 120000 || CLANG_VERSION >= 130000
2078 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
2079 select OBJTOOL if HAVE_NOINSTR_HACK
2081 KCOV exposes kernel code coverage information in a form suitable
2082 for coverage-guided fuzzing (randomized testing).
2084 If RANDOMIZE_BASE is enabled, PC values will not be stable across
2085 different machines and across reboots. If you need stable PC values,
2086 disable RANDOMIZE_BASE.
2088 For more details, see Documentation/dev-tools/kcov.rst.
2090 config KCOV_ENABLE_COMPARISONS
2091 bool "Enable comparison operands collection by KCOV"
2093 depends on $(cc-option,-fsanitize-coverage=trace-cmp)
2095 KCOV also exposes operands of every comparison in the instrumented
2096 code along with operand sizes and PCs of the comparison instructions.
2097 These operands can be used by fuzzing engines to improve the quality
2098 of fuzzing coverage.
2100 config KCOV_INSTRUMENT_ALL
2101 bool "Instrument all code by default"
2105 If you are doing generic system call fuzzing (like e.g. syzkaller),
2106 then you will want to instrument the whole kernel and you should
2107 say y here. If you are doing more targeted fuzzing (like e.g.
2108 filesystem fuzzing with AFL) then you will want to enable coverage
2109 for more specific subsets of files, and should say n here.
2111 config KCOV_IRQ_AREA_SIZE
2112 hex "Size of interrupt coverage collection area in words"
2116 KCOV uses preallocated per-cpu areas to collect coverage from
2117 soft interrupts. This specifies the size of those areas in the
2118 number of unsigned long words.
2120 menuconfig RUNTIME_TESTING_MENU
2121 bool "Runtime Testing"
2124 if RUNTIME_TESTING_MENU
2127 tristate "Dhrystone benchmark test"
2129 Enable this to include the Dhrystone 2.1 benchmark. This test
2130 calculates the number of Dhrystones per second, and the number of
2131 DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided
2132 by 1757 (the number of Dhrystones per second obtained on the VAX
2133 11/780, nominally a 1 MIPS machine).
2135 To run the benchmark, it needs to be enabled explicitly, either from
2136 the kernel command line (when built-in), or from userspace (when
2137 built-in or modular.
2139 Run once during kernel boot:
2143 Set number of iterations from kernel command line:
2145 test_dhry.iterations=<n>
2147 Set number of iterations from userspace:
2149 echo <n> > /sys/module/test_dhry/parameters/iterations
2151 Trigger manual run from userspace:
2153 echo y > /sys/module/test_dhry/parameters/run
2155 If the number of iterations is <= 0, the test will devise a suitable
2156 number of iterations (test runs for at least 2s) automatically.
2157 This process takes ca. 4s.
2162 tristate "Linux Kernel Dump Test Tool Module"
2165 This module enables testing of the different dumping mechanisms by
2166 inducing system failures at predefined crash points.
2167 If you don't need it: say N
2168 Choose M here to compile this code as a module. The module will be
2171 Documentation on how to use the module can be found in
2172 Documentation/fault-injection/provoke-crashes.rst
2174 config CPUMASK_KUNIT_TEST
2175 tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS
2177 default KUNIT_ALL_TESTS
2179 Enable to turn on cpumask tests, running at boot or module load time.
2181 For more information on KUnit and unit tests in general, please refer
2182 to the KUnit documentation in Documentation/dev-tools/kunit/.
2186 config TEST_LIST_SORT
2187 tristate "Linked list sorting test" if !KUNIT_ALL_TESTS
2189 default KUNIT_ALL_TESTS
2191 Enable this to turn on 'list_sort()' function test. This test is
2192 executed only once during system boot (so affects only boot time),
2193 or at module load time.
2197 config TEST_MIN_HEAP
2198 tristate "Min heap test"
2199 depends on DEBUG_KERNEL || m
2201 Enable this to turn on min heap function tests. This test is
2202 executed only once during system boot (so affects only boot time),
2203 or at module load time.
2208 tristate "Array-based sort test" if !KUNIT_ALL_TESTS
2210 default KUNIT_ALL_TESTS
2212 This option enables the self-test function of 'sort()' at boot,
2213 or at module load time.
2218 tristate "64bit/32bit division and modulo test"
2219 depends on DEBUG_KERNEL || m
2221 Enable this to turn on 'do_div()' function test. This test is
2222 executed only once during system boot (so affects only boot time),
2223 or at module load time.
2227 config KPROBES_SANITY_TEST
2228 tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS
2229 depends on DEBUG_KERNEL
2232 select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
2233 default KUNIT_ALL_TESTS
2235 This option provides for testing basic kprobes functionality on
2236 boot. Samples of kprobe and kretprobe are inserted and
2237 verified for functionality.
2239 Say N if you are unsure.
2241 config FPROBE_SANITY_TEST
2242 bool "Self test for fprobe"
2243 depends on DEBUG_KERNEL
2247 This option will enable testing the fprobe when the system boot.
2248 A series of tests are made to verify that the fprobe is functioning
2251 Say N if you are unsure.
2253 config BACKTRACE_SELF_TEST
2254 tristate "Self test for the backtrace code"
2255 depends on DEBUG_KERNEL
2257 This option provides a kernel module that can be used to test
2258 the kernel stack backtrace code. This option is not useful
2259 for distributions or general kernels, but only for kernel
2260 developers working on architecture code.
2262 Note that if you want to also test saved backtraces, you will
2263 have to enable STACKTRACE as well.
2265 Say N if you are unsure.
2267 config TEST_REF_TRACKER
2268 tristate "Self test for reference tracker"
2269 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
2272 This option provides a kernel module performing tests
2273 using reference tracker infrastructure.
2275 Say N if you are unsure.
2278 tristate "Red-Black tree test"
2279 depends on DEBUG_KERNEL
2281 A benchmark measuring the performance of the rbtree library.
2282 Also includes rbtree invariant checks.
2284 config REED_SOLOMON_TEST
2285 tristate "Reed-Solomon library test"
2286 depends on DEBUG_KERNEL || m
2288 select REED_SOLOMON_ENC16
2289 select REED_SOLOMON_DEC16
2291 This option enables the self-test function of rslib at boot,
2292 or at module load time.
2296 config INTERVAL_TREE_TEST
2297 tristate "Interval tree test"
2298 depends on DEBUG_KERNEL
2299 select INTERVAL_TREE
2301 A benchmark measuring the performance of the interval tree library
2304 tristate "Per cpu operations test"
2305 depends on m && DEBUG_KERNEL
2307 Enable this option to build test module which validates per-cpu
2312 config ATOMIC64_SELFTEST
2313 tristate "Perform an atomic64_t self-test"
2315 Enable this option to test the atomic64_t functions at boot or
2316 at module load time.
2320 config ASYNC_RAID6_TEST
2321 tristate "Self test for hardware accelerated raid6 recovery"
2322 depends on ASYNC_RAID6_RECOV
2325 This is a one-shot self test that permutes through the
2326 recovery of all the possible two disk failure scenarios for a
2327 N-disk array. Recovery is performed with the asynchronous
2328 raid6 recovery routines, and will optionally use an offload
2329 engine if one is available.
2334 tristate "Test functions located in the hexdump module at runtime"
2336 config STRING_SELFTEST
2337 tristate "Test string functions at runtime"
2339 config TEST_STRING_HELPERS
2340 tristate "Test functions located in the string_helpers module at runtime"
2343 tristate "Test kstrto*() family of functions at runtime"
2346 tristate "Test printf() family of functions at runtime"
2349 tristate "Test scanf() family of functions at runtime"
2352 tristate "Test bitmap_*() family of functions at runtime"
2354 Enable this option to test the bitmap functions at boot.
2359 tristate "Test functions located in the uuid module at runtime"
2362 tristate "Test the XArray code at runtime"
2364 config TEST_MAPLE_TREE
2365 depends on DEBUG_KERNEL
2366 select DEBUG_MAPLE_TREE
2367 tristate "Test the Maple Tree code at runtime"
2369 config TEST_RHASHTABLE
2370 tristate "Perform selftest on resizable hash table"
2372 Enable this option to test the rhashtable functions at boot.
2377 tristate "Perform selftest on IDA functions"
2380 tristate "Perform selftest on priority array manager"
2383 Enable this option to test priority array manager on boot
2388 config TEST_IRQ_TIMINGS
2389 bool "IRQ timings selftest"
2390 depends on IRQ_TIMINGS
2392 Enable this option to test the irq timings code on boot.
2397 tristate "Test module loading with 'hello world' module"
2400 This builds the "test_module" module that emits "Hello, world"
2401 on printk when loaded. It is designed to be used for basic
2402 evaluation of the module loading subsystem (for example when
2403 validating module verification). It lacks any extra dependencies,
2404 and will not normally be loaded by the system unless explicitly
2410 tristate "Test module for compilation of bitops operations"
2413 This builds the "test_bitops" module that is much like the
2414 TEST_LKM module except that it does a basic exercise of the
2415 set/clear_bit macros and get_count_order/long to make sure there are
2416 no compiler warnings from C=1 sparse checker or -Wextra
2417 compilations. It has no dependencies and doesn't run or load unless
2418 explicitly requested by name. for example: modprobe test_bitops.
2423 tristate "Test module for stress/performance analysis of vmalloc allocator"
2428 This builds the "test_vmalloc" module that should be used for
2429 stress and performance analysis. So, any new change for vmalloc
2430 subsystem can be evaluated from performance and stability point
2435 config TEST_USER_COPY
2436 tristate "Test user/kernel boundary protections"
2439 This builds the "test_user_copy" module that runs sanity checks
2440 on the copy_to/from_user infrastructure, making sure basic
2441 user/kernel boundary testing is working. If it fails to load,
2442 a regression has been detected in the user/kernel memory boundary
2448 tristate "Test BPF filter functionality"
2451 This builds the "test_bpf" module that runs various test vectors
2452 against the BPF interpreter or BPF JIT compiler depending on the
2453 current setting. This is in particular useful for BPF JIT compiler
2454 development, but also to run regression tests against changes in
2455 the interpreter code. It also enables test stubs for eBPF maps and
2456 verifier used by user space verifier testsuite.
2460 config TEST_BLACKHOLE_DEV
2461 tristate "Test blackhole netdev functionality"
2464 This builds the "test_blackhole_dev" module that validates the
2465 data path through this blackhole netdev.
2469 config FIND_BIT_BENCHMARK
2470 tristate "Test find_bit functions"
2472 This builds the "test_find_bit" module that measure find_*_bit()
2473 functions performance.
2477 config TEST_FIRMWARE
2478 tristate "Test firmware loading via userspace interface"
2479 depends on FW_LOADER
2481 This builds the "test_firmware" module that creates a userspace
2482 interface for testing firmware loading. This can be used to
2483 control the triggering of firmware loading without needing an
2484 actual firmware-using device. The contents can be rechecked by
2490 tristate "sysctl test driver"
2491 depends on PROC_SYSCTL
2493 This builds the "test_sysctl" module. This driver enables to test the
2494 proc sysctl interfaces available to drivers safely without affecting
2495 production knobs which might alter system functionality.
2499 config BITFIELD_KUNIT
2500 tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS
2502 default KUNIT_ALL_TESTS
2504 Enable this option to test the bitfield functions at boot.
2506 KUnit tests run during boot and output the results to the debug log
2507 in TAP format (http://testanything.org/). Only useful for kernel devs
2508 running the KUnit test harness, and not intended for inclusion into a
2511 For more information on KUnit and unit tests in general please refer
2512 to the KUnit documentation in Documentation/dev-tools/kunit/.
2516 config HASH_KUNIT_TEST
2517 tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS
2519 default KUNIT_ALL_TESTS
2521 Enable this option to test the kernel's string (<linux/stringhash.h>), and
2522 integer (<linux/hash.h>) hash functions on boot.
2524 KUnit tests run during boot and output the results to the debug log
2525 in TAP format (https://testanything.org/). Only useful for kernel devs
2526 running the KUnit test harness, and not intended for inclusion into a
2529 For more information on KUnit and unit tests in general please refer
2530 to the KUnit documentation in Documentation/dev-tools/kunit/.
2532 This is intended to help people writing architecture-specific
2533 optimized versions. If unsure, say N.
2535 config RESOURCE_KUNIT_TEST
2536 tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS
2538 default KUNIT_ALL_TESTS
2540 This builds the resource API unit test.
2541 Tests the logic of API provided by resource.c and ioport.h.
2542 For more information on KUnit and unit tests in general please refer
2543 to the KUnit documentation in Documentation/dev-tools/kunit/.
2547 config SYSCTL_KUNIT_TEST
2548 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS
2550 default KUNIT_ALL_TESTS
2552 This builds the proc sysctl unit test, which runs on boot.
2553 Tests the API contract and implementation correctness of sysctl.
2554 For more information on KUnit and unit tests in general please refer
2555 to the KUnit documentation in Documentation/dev-tools/kunit/.
2559 config LIST_KUNIT_TEST
2560 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS
2562 default KUNIT_ALL_TESTS
2564 This builds the linked list KUnit test suite.
2565 It tests that the API and basic functionality of the list_head type
2566 and associated macros.
2568 KUnit tests run during boot and output the results to the debug log
2569 in TAP format (https://testanything.org/). Only useful for kernel devs
2570 running the KUnit test harness, and not intended for inclusion into a
2573 For more information on KUnit and unit tests in general please refer
2574 to the KUnit documentation in Documentation/dev-tools/kunit/.
2578 config HASHTABLE_KUNIT_TEST
2579 tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS
2581 default KUNIT_ALL_TESTS
2583 This builds the hashtable KUnit test suite.
2584 It tests the basic functionality of the API defined in
2585 include/linux/hashtable.h. For more information on KUnit and
2586 unit tests in general please refer to the KUnit documentation
2587 in Documentation/dev-tools/kunit/.
2591 config LINEAR_RANGES_TEST
2592 tristate "KUnit test for linear_ranges"
2594 select LINEAR_RANGES
2596 This builds the linear_ranges unit test, which runs on boot.
2597 Tests the linear_ranges logic correctness.
2598 For more information on KUnit and unit tests in general please refer
2599 to the KUnit documentation in Documentation/dev-tools/kunit/.
2603 config CMDLINE_KUNIT_TEST
2604 tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS
2606 default KUNIT_ALL_TESTS
2608 This builds the cmdline API unit test.
2609 Tests the logic of API provided by cmdline.c.
2610 For more information on KUnit and unit tests in general please refer
2611 to the KUnit documentation in Documentation/dev-tools/kunit/.
2616 tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS
2618 default KUNIT_ALL_TESTS
2620 This builds the bits unit test.
2621 Tests the logic of macros defined in bits.h.
2622 For more information on KUnit and unit tests in general please refer
2623 to the KUnit documentation in Documentation/dev-tools/kunit/.
2627 config SLUB_KUNIT_TEST
2628 tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS
2629 depends on SLUB_DEBUG && KUNIT
2630 default KUNIT_ALL_TESTS
2632 This builds SLUB allocator unit test.
2633 Tests SLUB cache debugging functionality.
2634 For more information on KUnit and unit tests in general please refer
2635 to the KUnit documentation in Documentation/dev-tools/kunit/.
2639 config RATIONAL_KUNIT_TEST
2640 tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS
2641 depends on KUNIT && RATIONAL
2642 default KUNIT_ALL_TESTS
2644 This builds the rational math unit test.
2645 For more information on KUnit and unit tests in general please refer
2646 to the KUnit documentation in Documentation/dev-tools/kunit/.
2650 config MEMCPY_KUNIT_TEST
2651 tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS
2653 default KUNIT_ALL_TESTS
2655 Builds unit tests for memcpy(), memmove(), and memset() functions.
2656 For more information on KUnit and unit tests in general please refer
2657 to the KUnit documentation in Documentation/dev-tools/kunit/.
2661 config MEMCPY_SLOW_KUNIT_TEST
2662 bool "Include exhaustive memcpy tests"
2663 depends on MEMCPY_KUNIT_TEST
2666 Some memcpy tests are quite exhaustive in checking for overlaps
2667 and bit ranges. These can be very slow, so they are split out
2668 as a separate config, in case they need to be disabled.
2670 config IS_SIGNED_TYPE_KUNIT_TEST
2671 tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS
2673 default KUNIT_ALL_TESTS
2675 Builds unit tests for the is_signed_type() macro.
2677 For more information on KUnit and unit tests in general please refer
2678 to the KUnit documentation in Documentation/dev-tools/kunit/.
2682 config OVERFLOW_KUNIT_TEST
2683 tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS
2685 default KUNIT_ALL_TESTS
2687 Builds unit tests for the check_*_overflow(), size_*(), allocation, and
2690 For more information on KUnit and unit tests in general please refer
2691 to the KUnit documentation in Documentation/dev-tools/kunit/.
2695 config STACKINIT_KUNIT_TEST
2696 tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS
2698 default KUNIT_ALL_TESTS
2700 Test if the kernel is zero-initializing stack variables and
2701 padding. Coverage is controlled by compiler flags,
2702 CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO,
2703 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2704 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2706 config FORTIFY_KUNIT_TEST
2707 tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS
2708 depends on KUNIT && FORTIFY_SOURCE
2709 default KUNIT_ALL_TESTS
2711 Builds unit tests for checking internals of FORTIFY_SOURCE as used
2712 by the str*() and mem*() family of functions. For testing runtime
2713 traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests.
2715 config HW_BREAKPOINT_KUNIT_TEST
2716 bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS
2717 depends on HAVE_HW_BREAKPOINT
2719 default KUNIT_ALL_TESTS
2721 Tests for hw_breakpoint constraints accounting.
2725 config STRSCPY_KUNIT_TEST
2726 tristate "Test strscpy*() family of functions at runtime" if !KUNIT_ALL_TESTS
2728 default KUNIT_ALL_TESTS
2730 config SIPHASH_KUNIT_TEST
2731 tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS
2733 default KUNIT_ALL_TESTS
2735 Enable this option to test the kernel's siphash (<linux/siphash.h>) hash
2736 functions on boot (or module load).
2738 This is intended to help people writing architecture-specific
2739 optimized versions. If unsure, say N.
2742 tristate "udelay test driver"
2744 This builds the "udelay_test" module that helps to make sure
2745 that udelay() is working properly.
2749 config TEST_STATIC_KEYS
2750 tristate "Test static keys"
2753 Test the static key interfaces.
2757 config TEST_DYNAMIC_DEBUG
2758 tristate "Test DYNAMIC_DEBUG"
2759 depends on DYNAMIC_DEBUG
2761 This module registers a tracer callback to count enabled
2762 pr_debugs in a 'do_debugging' function, then alters their
2763 enablements, calls the function, and compares counts.
2768 tristate "kmod stress tester"
2770 depends on NETDEVICES && NET_CORE && INET # for TUN
2772 depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS
2778 Test the kernel's module loading mechanism: kmod. kmod implements
2779 support to load modules using the Linux kernel's usermode helper.
2780 This test provides a series of tests against kmod.
2782 Although technically you can either build test_kmod as a module or
2783 into the kernel we disallow building it into the kernel since
2784 it stress tests request_module() and this will very likely cause
2785 some issues by taking over precious threads available from other
2786 module load requests, ultimately this could be fatal.
2790 tools/testing/selftests/kmod/kmod.sh --help
2794 config TEST_DEBUG_VIRTUAL
2795 tristate "Test CONFIG_DEBUG_VIRTUAL feature"
2796 depends on DEBUG_VIRTUAL
2798 Test the kernel's ability to detect incorrect calls to
2799 virt_to_phys() done against the non-linear part of the
2800 kernel's virtual address map.
2804 config TEST_MEMCAT_P
2805 tristate "Test memcat_p() helper function"
2807 Test the memcat_p() helper for correctly merging two
2808 pointer arrays together.
2812 config TEST_LIVEPATCH
2813 tristate "Test livepatching"
2815 depends on DYNAMIC_DEBUG
2816 depends on LIVEPATCH
2819 Test kernel livepatching features for correctness. The tests will
2820 load test modules that will be livepatched in various scenarios.
2822 To run all the livepatching tests:
2824 make -C tools/testing/selftests TARGETS=livepatch run_tests
2826 Alternatively, individual tests may be invoked:
2828 tools/testing/selftests/livepatch/test-callbacks.sh
2829 tools/testing/selftests/livepatch/test-livepatch.sh
2830 tools/testing/selftests/livepatch/test-shadow-vars.sh
2835 tristate "Perform selftest on object aggreration manager"
2839 Enable this option to test object aggregation manager on boot
2843 tristate "Test heap/page initialization"
2845 Test if the kernel is zero-initializing heap and page allocations.
2846 This can be useful to test init_on_alloc and init_on_free features.
2851 tristate "Test HMM (Heterogeneous Memory Management)"
2852 depends on TRANSPARENT_HUGEPAGE
2853 depends on DEVICE_PRIVATE
2857 This is a pseudo device driver solely for testing HMM.
2858 Say M here if you want to build the HMM test module.
2859 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests.
2863 config TEST_FREE_PAGES
2864 tristate "Test freeing pages"
2866 Test that a memory leak does not occur due to a race between
2867 freeing a block of pages and a speculative page reference.
2868 Loading this module is safe if your kernel has the bug fixed.
2869 If the bug is not fixed, it will leak gigabytes of memory and
2870 probably OOM your system.
2873 tristate "Test floating point operations in kernel space"
2874 depends on X86 && !KCOV_INSTRUMENT_ALL
2876 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu
2877 which will trigger a sequence of floating point operations. This is used
2878 for self-testing floating point control register setting in
2883 config TEST_CLOCKSOURCE_WATCHDOG
2884 tristate "Test clocksource watchdog in kernel space"
2885 depends on CLOCKSOURCE_WATCHDOG
2887 Enable this option to create a kernel module that will trigger
2888 a test of the clocksource watchdog. This module may be loaded
2889 via modprobe or insmod in which case it will run upon being
2890 loaded, or it may be built in, in which case it will run
2895 endif # RUNTIME_TESTING_MENU
2897 config ARCH_USE_MEMTEST
2900 An architecture should select this when it uses early_memtest()
2901 during boot process.
2905 depends on ARCH_USE_MEMTEST
2907 This option adds a kernel parameter 'memtest', which allows memtest
2908 to be set and executed.
2909 memtest=0, mean disabled; -- default
2910 memtest=1, mean do 1 test pattern;
2912 memtest=17, mean do 17 test patterns.
2913 If you are unsure how to answer this question, answer N.
2917 config HYPERV_TESTING
2918 bool "Microsoft Hyper-V driver testing"
2920 depends on HYPERV && DEBUG_FS
2922 Select this option to enable Hyper-V vmbus testing.
2924 endmenu # "Kernel Testing and Coverage"
2928 config RUST_DEBUG_ASSERTIONS
2929 bool "Debug assertions"
2932 Enables rustc's `-Cdebug-assertions` codegen option.
2934 This flag lets you turn `cfg(debug_assertions)` conditional
2935 compilation on or off. This can be used to enable extra debugging
2936 code in development but not in production. For example, it controls
2937 the behavior of the standard library's `debug_assert!` macro.
2939 Note that this will apply to all Rust code, including `core`.
2943 config RUST_OVERFLOW_CHECKS
2944 bool "Overflow checks"
2948 Enables rustc's `-Coverflow-checks` codegen option.
2950 This flag allows you to control the behavior of runtime integer
2951 overflow. When overflow-checks are enabled, a Rust panic will occur
2954 Note that this will apply to all Rust code, including `core`.
2958 config RUST_BUILD_ASSERT_ALLOW
2959 bool "Allow unoptimized build-time assertions"
2962 Controls how are `build_error!` and `build_assert!` handled during build.
2964 If calls to them exist in the binary, it may indicate a violated invariant
2965 or that the optimizer failed to verify the invariant during compilation.
2967 This should not happen, thus by default the build is aborted. However,
2968 as an escape hatch, you can choose Y here to ignore them during build
2969 and let the check be carried at runtime (with `panic!` being called if
2976 endmenu # Kernel hacking
projects / platform / kernel / linux-starfive.git / blob