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 CONSOLE_LOGLEVEL_DEFAULT
39 int "Default console loglevel (1-15)"
43 Default loglevel to determine what will be printed on the console.
45 Setting a default here is equivalent to passing in loglevel=<x> in
46 the kernel bootargs. loglevel=<x> continues to override whatever
47 value is specified here as well.
49 Note: This does not affect the log level of un-prefixed printk()
50 usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT
53 config CONSOLE_LOGLEVEL_QUIET
54 int "quiet console loglevel (1-15)"
58 loglevel to use when "quiet" is passed on the kernel commandline.
60 When "quiet" is passed on the kernel commandline this loglevel
61 will be used as the loglevel. IOW passing "quiet" will be the
62 equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>"
64 config MESSAGE_LOGLEVEL_DEFAULT
65 int "Default message log level (1-7)"
69 Default log level for printk statements with no specified priority.
71 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
72 that are auditing their logs closely may want to set it to a lower
75 Note: This does not affect what message level gets printed on the console
76 by default. To change that, use loglevel=<x> in the kernel bootargs,
77 or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value.
79 config BOOT_PRINTK_DELAY
80 bool "Delay each boot printk message by N milliseconds"
81 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
83 This build option allows you to read kernel boot messages
84 by inserting a short delay after each one. The delay is
85 specified in milliseconds on the kernel command line,
88 It is likely that you would also need to use "lpj=M" to preset
89 the "loops per jiffie" value.
90 See a previous boot log for the "lpj" value to use for your
91 system, and then set "lpj=M" before setting "boot_delay=N".
92 NOTE: Using this option may adversely affect SMP systems.
93 I.e., processors other than the first one may not boot up.
94 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
95 what it believes to be lockup conditions.
98 bool "Enable dynamic printk() support"
104 Compiles debug level messages into the kernel, which would not
105 otherwise be available at runtime. These messages can then be
106 enabled/disabled based on various levels of scope - per source file,
107 function, module, format string, and line number. This mechanism
108 implicitly compiles in all pr_debug() and dev_dbg() calls, which
109 enlarges the kernel text size by about 2%.
111 If a source file is compiled with DEBUG flag set, any
112 pr_debug() calls in it are enabled by default, but can be
113 disabled at runtime as below. Note that DEBUG flag is
114 turned on by many CONFIG_*DEBUG* options.
118 Dynamic debugging is controlled via the 'dynamic_debug/control' file,
119 which is contained in the 'debugfs' filesystem. Thus, the debugfs
120 filesystem must first be mounted before making use of this feature.
121 We refer the control file as: <debugfs>/dynamic_debug/control. This
122 file contains a list of the debug statements that can be enabled. The
123 format for each line of the file is:
125 filename:lineno [module]function flags format
127 filename : source file of the debug statement
128 lineno : line number of the debug statement
129 module : module that contains the debug statement
130 function : function that contains the debug statement
131 flags : '=p' means the line is turned 'on' for printing
132 format : the format used for the debug statement
136 nullarbor:~ # cat <debugfs>/dynamic_debug/control
137 # filename:lineno [module]function flags format
138 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
139 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
140 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
144 // enable the message at line 1603 of file svcsock.c
145 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
146 <debugfs>/dynamic_debug/control
148 // enable all the messages in file svcsock.c
149 nullarbor:~ # echo -n 'file svcsock.c +p' >
150 <debugfs>/dynamic_debug/control
152 // enable all the messages in the NFS server module
153 nullarbor:~ # echo -n 'module nfsd +p' >
154 <debugfs>/dynamic_debug/control
156 // enable all 12 messages in the function svc_process()
157 nullarbor:~ # echo -n 'func svc_process +p' >
158 <debugfs>/dynamic_debug/control
160 // disable all 12 messages in the function svc_process()
161 nullarbor:~ # echo -n 'func svc_process -p' >
162 <debugfs>/dynamic_debug/control
164 See Documentation/admin-guide/dynamic-debug-howto.rst for additional
167 endmenu # "printk and dmesg options"
169 menu "Compile-time checks and compiler options"
172 bool "Compile the kernel with debug info"
173 depends on DEBUG_KERNEL && !COMPILE_TEST
175 If you say Y here the resulting kernel image will include
176 debugging info resulting in a larger kernel image.
177 This adds debug symbols to the kernel and modules (gcc -g), and
178 is needed if you intend to use kernel crashdump or binary object
179 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
180 Say Y here only if you plan to debug the kernel.
184 config DEBUG_INFO_REDUCED
185 bool "Reduce debugging information"
186 depends on DEBUG_INFO
188 If you say Y here gcc is instructed to generate less debugging
189 information for structure types. This means that tools that
190 need full debugging information (like kgdb or systemtap) won't
191 be happy. But if you merely need debugging information to
192 resolve line numbers there is no loss. Advantage is that
193 build directory object sizes shrink dramatically over a full
194 DEBUG_INFO build and compile times are reduced too.
195 Only works with newer gcc versions.
197 config DEBUG_INFO_SPLIT
198 bool "Produce split debuginfo in .dwo files"
199 depends on DEBUG_INFO
200 depends on $(cc-option,-gsplit-dwarf)
202 Generate debug info into separate .dwo files. This significantly
203 reduces the build directory size for builds with DEBUG_INFO,
204 because it stores the information only once on disk in .dwo
205 files instead of multiple times in object files and executables.
206 In addition the debug information is also compressed.
208 Requires recent gcc (4.7+) and recent gdb/binutils.
209 Any tool that packages or reads debug information would need
210 to know about the .dwo files and include them.
211 Incompatible with older versions of ccache.
213 config DEBUG_INFO_DWARF4
214 bool "Generate dwarf4 debuginfo"
215 depends on DEBUG_INFO
216 depends on $(cc-option,-gdwarf-4)
218 Generate dwarf4 debug info. This requires recent versions
219 of gcc and gdb. It makes the debug information larger.
220 But it significantly improves the success of resolving
221 variables in gdb on optimized code.
223 config DEBUG_INFO_BTF
224 bool "Generate BTF typeinfo"
225 depends on DEBUG_INFO
227 Generate deduplicated BTF type information from DWARF debug info.
228 Turning this on expects presence of pahole tool, which will convert
229 DWARF type info into equivalent deduplicated BTF type info.
232 bool "Provide GDB scripts for kernel debugging"
233 depends on DEBUG_INFO
235 This creates the required links to GDB helper scripts in the
236 build directory. If you load vmlinux into gdb, the helper
237 scripts will be automatically imported by gdb as well, and
238 additional functions are available to analyze a Linux kernel
239 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
242 config ENABLE_MUST_CHECK
243 bool "Enable __must_check logic"
246 Enable the __must_check logic in the kernel build. Disable this to
247 suppress the "warning: ignoring return value of 'foo', declared with
248 attribute warn_unused_result" messages.
251 int "Warn for stack frames larger than (needs gcc 4.4)"
253 default 2048 if GCC_PLUGIN_LATENT_ENTROPY
254 default 1280 if (!64BIT && PARISC)
255 default 1024 if (!64BIT && !PARISC)
256 default 2048 if 64BIT
258 Tell gcc to warn at build time for stack frames larger than this.
259 Setting this too low will cause a lot of warnings.
260 Setting it to 0 disables the warning.
263 config STRIP_ASM_SYMS
264 bool "Strip assembler-generated symbols during link"
267 Strip internal assembler-generated symbols during a link (symbols
268 that look like '.Lxxx') so they don't pollute the output of
269 get_wchan() and suchlike.
272 bool "Generate readable assembler code"
273 depends on DEBUG_KERNEL
275 Disable some compiler optimizations that tend to generate human unreadable
276 assembler output. This may make the kernel slightly slower, but it helps
277 to keep kernel developers who have to stare a lot at assembler listings
281 bool "Debug Filesystem"
283 debugfs is a virtual file system that kernel developers use to put
284 debugging files into. Enable this option to be able to read and
285 write to these files.
287 For detailed documentation on the debugfs API, see
288 Documentation/filesystems/.
292 config HEADERS_INSTALL
293 bool "Install uapi headers to usr/include"
296 This option will install uapi headers (headers exported to user-space)
297 into the usr/include directory for use during the kernel build.
298 This is unneeded for building the kernel itself, but needed for some
299 user-space program samples. It is also needed by some features such
300 as uapi header sanity checks.
303 bool "Run sanity checks on uapi headers when building 'all'"
304 depends on HEADERS_INSTALL
306 This option will run basic sanity checks on uapi headers when
307 building the 'all' target, for example, ensure that they do not
308 attempt to include files which were not exported, etc.
310 If you're making modifications to header files which are
311 relevant for userspace, say 'Y'.
313 config OPTIMIZE_INLINING
314 bool "Allow compiler to uninline functions marked 'inline'"
316 This option determines if the kernel forces gcc to inline the functions
317 developers have marked 'inline'. Doing so takes away freedom from gcc to
318 do what it thinks is best, which is desirable for the gcc 3.x series of
319 compilers. The gcc 4.x series have a rewritten inlining algorithm and
320 enabling this option will generate a smaller kernel there. Hopefully
321 this algorithm is so good that allowing gcc 4.x and above to make the
322 decision will become the default in the future. Until then this option
323 is there to test gcc for this.
327 config DEBUG_SECTION_MISMATCH
328 bool "Enable full Section mismatch analysis"
330 The section mismatch analysis checks if there are illegal
331 references from one section to another section.
332 During linktime or runtime, some sections are dropped;
333 any use of code/data previously in these sections would
334 most likely result in an oops.
335 In the code, functions and variables are annotated with
336 __init,, etc. (see the full list in include/linux/init.h),
337 which results in the code/data being placed in specific sections.
338 The section mismatch analysis is always performed after a full
339 kernel build, and enabling this option causes the following
340 additional step to occur:
341 - Add the option -fno-inline-functions-called-once to gcc commands.
342 When inlining a function annotated with __init in a non-init
343 function, we would lose the section information and thus
344 the analysis would not catch the illegal reference.
345 This option tells gcc to inline less (but it does result in
348 config SECTION_MISMATCH_WARN_ONLY
349 bool "Make section mismatch errors non-fatal"
352 If you say N here, the build process will fail if there are any
353 section mismatch, instead of just throwing warnings.
358 # Select this config option from the architecture Kconfig, if it
359 # is preferred to always offer frame pointers as a config
360 # option on the architecture (regardless of KERNEL_DEBUG):
362 config ARCH_WANT_FRAME_POINTERS
366 bool "Compile the kernel with frame pointers"
367 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
368 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
370 If you say Y here the resulting kernel image will be slightly
371 larger and slower, but it gives very useful debugging information
372 in case of kernel bugs. (precise oopses/stacktraces/warnings)
374 config STACK_VALIDATION
375 bool "Compile-time stack metadata validation"
376 depends on HAVE_STACK_VALIDATION
379 Add compile-time checks to validate stack metadata, including frame
380 pointers (if CONFIG_FRAME_POINTER is enabled). This helps ensure
381 that runtime stack traces are more reliable.
383 This is also a prerequisite for generation of ORC unwind data, which
384 is needed for CONFIG_UNWINDER_ORC.
386 For more information, see
387 tools/objtool/Documentation/stack-validation.txt.
389 config DEBUG_FORCE_WEAK_PER_CPU
390 bool "Force weak per-cpu definitions"
391 depends on DEBUG_KERNEL
393 s390 and alpha require percpu variables in modules to be
394 defined weak to work around addressing range issue which
395 puts the following two restrictions on percpu variable
398 1. percpu symbols must be unique whether static or not
399 2. percpu variables can't be defined inside a function
401 To ensure that generic code follows the above rules, this
402 option forces all percpu variables to be defined as weak.
404 endmenu # "Compiler options"
407 bool "Magic SysRq key"
410 If you say Y here, you will have some control over the system even
411 if the system crashes for example during kernel debugging (e.g., you
412 will be able to flush the buffer cache to disk, reboot the system
413 immediately or dump some status information). This is accomplished
414 by pressing various keys while holding SysRq (Alt+PrintScreen). It
415 also works on a serial console (on PC hardware at least), if you
416 send a BREAK and then within 5 seconds a command keypress. The
417 keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
418 Don't say Y unless you really know what this hack does.
420 config MAGIC_SYSRQ_DEFAULT_ENABLE
421 hex "Enable magic SysRq key functions by default"
422 depends on MAGIC_SYSRQ
425 Specifies which SysRq key functions are enabled by default.
426 This may be set to 1 or 0 to enable or disable them all, or
427 to a bitmask as described in Documentation/admin-guide/sysrq.rst.
429 config MAGIC_SYSRQ_SERIAL
430 bool "Enable magic SysRq key over serial"
431 depends on MAGIC_SYSRQ
434 Many embedded boards have a disconnected TTL level serial which can
435 generate some garbage that can lead to spurious false sysrq detects.
436 This option allows you to decide whether you want to enable the
440 bool "Kernel debugging"
442 Say Y here if you are developing drivers or trying to debug and
443 identify kernel problems.
446 bool "Miscellaneous debug code"
448 depends on DEBUG_KERNEL
450 Say Y here if you need to enable miscellaneous debug code that should
451 be under a more specific debug option but isn't.
454 menu "Memory Debugging"
456 source "mm/Kconfig.debug"
459 bool "Debug object operations"
460 depends on DEBUG_KERNEL
462 If you say Y here, additional code will be inserted into the
463 kernel to track the life time of various objects and validate
464 the operations on those objects.
466 config DEBUG_OBJECTS_SELFTEST
467 bool "Debug objects selftest"
468 depends on DEBUG_OBJECTS
470 This enables the selftest of the object debug code.
472 config DEBUG_OBJECTS_FREE
473 bool "Debug objects in freed memory"
474 depends on DEBUG_OBJECTS
476 This enables checks whether a k/v free operation frees an area
477 which contains an object which has not been deactivated
478 properly. This can make kmalloc/kfree-intensive workloads
481 config DEBUG_OBJECTS_TIMERS
482 bool "Debug timer objects"
483 depends on DEBUG_OBJECTS
485 If you say Y here, additional code will be inserted into the
486 timer routines to track the life time of timer objects and
487 validate the timer operations.
489 config DEBUG_OBJECTS_WORK
490 bool "Debug work objects"
491 depends on DEBUG_OBJECTS
493 If you say Y here, additional code will be inserted into the
494 work queue routines to track the life time of work objects and
495 validate the work operations.
497 config DEBUG_OBJECTS_RCU_HEAD
498 bool "Debug RCU callbacks objects"
499 depends on DEBUG_OBJECTS
501 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
503 config DEBUG_OBJECTS_PERCPU_COUNTER
504 bool "Debug percpu counter objects"
505 depends on DEBUG_OBJECTS
507 If you say Y here, additional code will be inserted into the
508 percpu counter routines to track the life time of percpu counter
509 objects and validate the percpu counter operations.
511 config DEBUG_OBJECTS_ENABLE_DEFAULT
512 int "debug_objects bootup default value (0-1)"
515 depends on DEBUG_OBJECTS
517 Debug objects boot parameter default value
520 bool "Debug slab memory allocations"
521 depends on DEBUG_KERNEL && SLAB
523 Say Y here to have the kernel do limited verification on memory
524 allocation as well as poisoning memory on free to catch use of freed
525 memory. This can make kmalloc/kfree-intensive workloads much slower.
528 bool "SLUB debugging on by default"
529 depends on SLUB && SLUB_DEBUG
532 Boot with debugging on by default. SLUB boots by default with
533 the runtime debug capabilities switched off. Enabling this is
534 equivalent to specifying the "slub_debug" parameter on boot.
535 There is no support for more fine grained debug control like
536 possible with slub_debug=xxx. SLUB debugging may be switched
537 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
542 bool "Enable SLUB performance statistics"
543 depends on SLUB && SYSFS
545 SLUB statistics are useful to debug SLUBs allocation behavior in
546 order find ways to optimize the allocator. This should never be
547 enabled for production use since keeping statistics slows down
548 the allocator by a few percentage points. The slabinfo command
549 supports the determination of the most active slabs to figure
550 out which slabs are relevant to a particular load.
551 Try running: slabinfo -DA
553 config HAVE_DEBUG_KMEMLEAK
556 config DEBUG_KMEMLEAK
557 bool "Kernel memory leak detector"
558 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
560 select STACKTRACE if STACKTRACE_SUPPORT
564 Say Y here if you want to enable the memory leak
565 detector. The memory allocation/freeing is traced in a way
566 similar to the Boehm's conservative garbage collector, the
567 difference being that the orphan objects are not freed but
568 only shown in /sys/kernel/debug/kmemleak. Enabling this
569 feature will introduce an overhead to memory
570 allocations. See Documentation/dev-tools/kmemleak.rst for more
573 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
574 of finding leaks due to the slab objects poisoning.
576 In order to access the kmemleak file, debugfs needs to be
577 mounted (usually at /sys/kernel/debug).
579 config DEBUG_KMEMLEAK_MEM_POOL_SIZE
580 int "Kmemleak memory pool size"
581 depends on DEBUG_KMEMLEAK
585 Kmemleak must track all the memory allocations to avoid
586 reporting false positives. Since memory may be allocated or
587 freed before kmemleak is fully initialised, use a static pool
588 of metadata objects to track such callbacks. After kmemleak is
589 fully initialised, this memory pool acts as an emergency one
590 if slab allocations fail.
592 config DEBUG_KMEMLEAK_TEST
593 tristate "Simple test for the kernel memory leak detector"
594 depends on DEBUG_KMEMLEAK && m
596 This option enables a module that explicitly leaks memory.
600 config DEBUG_KMEMLEAK_DEFAULT_OFF
601 bool "Default kmemleak to off"
602 depends on DEBUG_KMEMLEAK
604 Say Y here to disable kmemleak by default. It can then be enabled
605 on the command line via kmemleak=on.
607 config DEBUG_KMEMLEAK_AUTO_SCAN
608 bool "Enable kmemleak auto scan thread on boot up"
610 depends on DEBUG_KMEMLEAK
612 Depending on the cpu, kmemleak scan may be cpu intensive and can
613 stall user tasks at times. This option enables/disables automatic
614 kmemleak scan at boot up.
616 Say N here to disable kmemleak auto scan thread to stop automatic
617 scanning. Disabling this option disables automatic reporting of
622 config DEBUG_STACK_USAGE
623 bool "Stack utilization instrumentation"
624 depends on DEBUG_KERNEL && !IA64
626 Enables the display of the minimum amount of free stack which each
627 task has ever had available in the sysrq-T and sysrq-P debug output.
629 This option will slow down process creation somewhat.
633 depends on DEBUG_KERNEL
635 Enable this to turn on extended checks in the virtual-memory system
636 that may impact performance.
640 config DEBUG_VM_VMACACHE
641 bool "Debug VMA caching"
644 Enable this to turn on VMA caching debug information. Doing so
645 can cause significant overhead, so only enable it in non-production
651 bool "Debug VM red-black trees"
654 Enable VM red-black tree debugging information and extra validations.
658 config DEBUG_VM_PGFLAGS
659 bool "Debug page-flags operations"
662 Enables extra validation on page flags operations.
666 config ARCH_HAS_DEBUG_VIRTUAL
670 bool "Debug VM translations"
671 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
673 Enable some costly sanity checks in virtual to page code. This can
674 catch mistakes with virt_to_page() and friends.
678 config DEBUG_NOMMU_REGIONS
679 bool "Debug the global anon/private NOMMU mapping region tree"
680 depends on DEBUG_KERNEL && !MMU
682 This option causes the global tree of anonymous and private mapping
683 regions to be regularly checked for invalid topology.
685 config DEBUG_MEMORY_INIT
686 bool "Debug memory initialisation" if EXPERT
689 Enable this for additional checks during memory initialisation.
690 The sanity checks verify aspects of the VM such as the memory model
691 and other information provided by the architecture. Verbose
692 information will be printed at KERN_DEBUG loglevel depending
693 on the mminit_loglevel= command-line option.
697 config MEMORY_NOTIFIER_ERROR_INJECT
698 tristate "Memory hotplug notifier error injection module"
699 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
701 This option provides the ability to inject artificial errors to
702 memory hotplug notifier chain callbacks. It is controlled through
703 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
705 If the notifier call chain should be failed with some events
706 notified, write the error code to "actions/<notifier event>/error".
708 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
710 # cd /sys/kernel/debug/notifier-error-inject/memory
711 # echo -12 > actions/MEM_GOING_OFFLINE/error
712 # echo offline > /sys/devices/system/memory/memoryXXX/state
713 bash: echo: write error: Cannot allocate memory
715 To compile this code as a module, choose M here: the module will
716 be called memory-notifier-error-inject.
720 config DEBUG_PER_CPU_MAPS
721 bool "Debug access to per_cpu maps"
722 depends on DEBUG_KERNEL
725 Say Y to verify that the per_cpu map being accessed has
726 been set up. This adds a fair amount of code to kernel memory
727 and decreases performance.
732 bool "Highmem debugging"
733 depends on DEBUG_KERNEL && HIGHMEM
735 This option enables additional error checking for high memory
736 systems. Disable for production systems.
738 config HAVE_DEBUG_STACKOVERFLOW
741 config DEBUG_STACKOVERFLOW
742 bool "Check for stack overflows"
743 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
745 Say Y here if you want to check for overflows of kernel, IRQ
746 and exception stacks (if your architecture uses them). This
747 option will show detailed messages if free stack space drops
748 below a certain limit.
750 These kinds of bugs usually occur when call-chains in the
751 kernel get too deep, especially when interrupts are
754 Use this in cases where you see apparently random memory
755 corruption, especially if it appears in 'struct thread_info'
757 If in doubt, say "N".
759 source "lib/Kconfig.kasan"
761 endmenu # "Memory Debugging"
766 An architecture should select this when it can successfully
767 build and run with CONFIG_KCOV. This typically requires
768 disabling instrumentation for some early boot code.
770 config CC_HAS_SANCOV_TRACE_PC
771 def_bool $(cc-option,-fsanitize-coverage=trace-pc)
774 bool "Code coverage for fuzzing"
775 depends on ARCH_HAS_KCOV
776 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
778 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
780 KCOV exposes kernel code coverage information in a form suitable
781 for coverage-guided fuzzing (randomized testing).
783 If RANDOMIZE_BASE is enabled, PC values will not be stable across
784 different machines and across reboots. If you need stable PC values,
785 disable RANDOMIZE_BASE.
787 For more details, see Documentation/dev-tools/kcov.rst.
789 config KCOV_ENABLE_COMPARISONS
790 bool "Enable comparison operands collection by KCOV"
792 depends on $(cc-option,-fsanitize-coverage=trace-cmp)
794 KCOV also exposes operands of every comparison in the instrumented
795 code along with operand sizes and PCs of the comparison instructions.
796 These operands can be used by fuzzing engines to improve the quality
799 config KCOV_INSTRUMENT_ALL
800 bool "Instrument all code by default"
804 If you are doing generic system call fuzzing (like e.g. syzkaller),
805 then you will want to instrument the whole kernel and you should
806 say y here. If you are doing more targeted fuzzing (like e.g.
807 filesystem fuzzing with AFL) then you will want to enable coverage
808 for more specific subsets of files, and should say n here.
811 bool "Debug shared IRQ handlers"
812 depends on DEBUG_KERNEL
814 Enable this to generate a spurious interrupt as soon as a shared
815 interrupt handler is registered, and just before one is deregistered.
816 Drivers ought to be able to handle interrupts coming in at those
817 points; some don't and need to be caught.
819 menu "Debug Lockups and Hangs"
821 config LOCKUP_DETECTOR
824 config SOFTLOCKUP_DETECTOR
825 bool "Detect Soft Lockups"
826 depends on DEBUG_KERNEL && !S390
827 select LOCKUP_DETECTOR
829 Say Y here to enable the kernel to act as a watchdog to detect
832 Softlockups are bugs that cause the kernel to loop in kernel
833 mode for more than 20 seconds, without giving other tasks a
834 chance to run. The current stack trace is displayed upon
835 detection and the system will stay locked up.
837 config BOOTPARAM_SOFTLOCKUP_PANIC
838 bool "Panic (Reboot) On Soft Lockups"
839 depends on SOFTLOCKUP_DETECTOR
841 Say Y here to enable the kernel to panic on "soft lockups",
842 which are bugs that cause the kernel to loop in kernel
843 mode for more than 20 seconds (configurable using the watchdog_thresh
844 sysctl), without giving other tasks a chance to run.
846 The panic can be used in combination with panic_timeout,
847 to cause the system to reboot automatically after a
848 lockup has been detected. This feature is useful for
849 high-availability systems that have uptime guarantees and
850 where a lockup must be resolved ASAP.
854 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
856 depends on SOFTLOCKUP_DETECTOR
858 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
859 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
861 config HARDLOCKUP_DETECTOR_PERF
863 select SOFTLOCKUP_DETECTOR
866 # Enables a timestamp based low pass filter to compensate for perf based
867 # hard lockup detection which runs too fast due to turbo modes.
869 config HARDLOCKUP_CHECK_TIMESTAMP
873 # arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard
874 # lockup detector rather than the perf based detector.
876 config HARDLOCKUP_DETECTOR
877 bool "Detect Hard Lockups"
878 depends on DEBUG_KERNEL && !S390
879 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH
880 select LOCKUP_DETECTOR
881 select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF
882 select HARDLOCKUP_DETECTOR_ARCH if HAVE_HARDLOCKUP_DETECTOR_ARCH
884 Say Y here to enable the kernel to act as a watchdog to detect
887 Hardlockups are bugs that cause the CPU to loop in kernel mode
888 for more than 10 seconds, without letting other interrupts have a
889 chance to run. The current stack trace is displayed upon detection
890 and the system will stay locked up.
892 config BOOTPARAM_HARDLOCKUP_PANIC
893 bool "Panic (Reboot) On Hard Lockups"
894 depends on HARDLOCKUP_DETECTOR
896 Say Y here to enable the kernel to panic on "hard lockups",
897 which are bugs that cause the kernel to loop in kernel
898 mode with interrupts disabled for more than 10 seconds (configurable
899 using the watchdog_thresh sysctl).
903 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
905 depends on HARDLOCKUP_DETECTOR
907 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
908 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
910 config DETECT_HUNG_TASK
911 bool "Detect Hung Tasks"
912 depends on DEBUG_KERNEL
913 default SOFTLOCKUP_DETECTOR
915 Say Y here to enable the kernel to detect "hung tasks",
916 which are bugs that cause the task to be stuck in
917 uninterruptible "D" state indefinitely.
919 When a hung task is detected, the kernel will print the
920 current stack trace (which you should report), but the
921 task will stay in uninterruptible state. If lockdep is
922 enabled then all held locks will also be reported. This
923 feature has negligible overhead.
925 config DEFAULT_HUNG_TASK_TIMEOUT
926 int "Default timeout for hung task detection (in seconds)"
927 depends on DETECT_HUNG_TASK
930 This option controls the default timeout (in seconds) used
931 to determine when a task has become non-responsive and should
934 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
935 sysctl or by writing a value to
936 /proc/sys/kernel/hung_task_timeout_secs.
938 A timeout of 0 disables the check. The default is two minutes.
939 Keeping the default should be fine in most cases.
941 config BOOTPARAM_HUNG_TASK_PANIC
942 bool "Panic (Reboot) On Hung Tasks"
943 depends on DETECT_HUNG_TASK
945 Say Y here to enable the kernel to panic on "hung tasks",
946 which are bugs that cause the kernel to leave a task stuck
947 in uninterruptible "D" state.
949 The panic can be used in combination with panic_timeout,
950 to cause the system to reboot automatically after a
951 hung task has been detected. This feature is useful for
952 high-availability systems that have uptime guarantees and
953 where a hung tasks must be resolved ASAP.
957 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
959 depends on DETECT_HUNG_TASK
961 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
962 default 1 if BOOTPARAM_HUNG_TASK_PANIC
965 bool "Detect Workqueue Stalls"
966 depends on DEBUG_KERNEL
968 Say Y here to enable stall detection on workqueues. If a
969 worker pool doesn't make forward progress on a pending work
970 item for over a given amount of time, 30s by default, a
971 warning message is printed along with dump of workqueue
972 state. This can be configured through kernel parameter
973 "workqueue.watchdog_thresh" and its sysfs counterpart.
975 endmenu # "Debug 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 the
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.
1006 bool "Collect scheduler debugging info"
1007 depends on DEBUG_KERNEL && PROC_FS
1010 If you say Y here, the /proc/sched_debug file will be provided
1011 that can help debug the scheduler. The runtime overhead of this
1019 bool "Collect scheduler statistics"
1020 depends on DEBUG_KERNEL && PROC_FS
1023 If you say Y here, additional code will be inserted into the
1024 scheduler and related routines to collect statistics about
1025 scheduler behavior and provide them in /proc/schedstat. These
1026 stats may be useful for both tuning and debugging the scheduler
1027 If you aren't debugging the scheduler or trying to tune a specific
1028 application, you can say N to avoid the very slight overhead
1031 config SCHED_STACK_END_CHECK
1032 bool "Detect stack corruption on calls to schedule()"
1033 depends on DEBUG_KERNEL
1036 This option checks for a stack overrun on calls to schedule().
1037 If the stack end location is found to be over written always panic as
1038 the content of the corrupted region can no longer be trusted.
1039 This is to ensure no erroneous behaviour occurs which could result in
1040 data corruption or a sporadic crash at a later stage once the region
1041 is examined. The runtime overhead introduced is minimal.
1043 config DEBUG_TIMEKEEPING
1044 bool "Enable extra timekeeping sanity checking"
1046 This option will enable additional timekeeping sanity checks
1047 which may be helpful when diagnosing issues where timekeeping
1048 problems are suspected.
1050 This may include checks in the timekeeping hotpaths, so this
1051 option may have a (very small) performance impact to some
1056 config DEBUG_PREEMPT
1057 bool "Debug preemptible kernel"
1058 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
1061 If you say Y here then the kernel will use a debug variant of the
1062 commonly used smp_processor_id() function and will print warnings
1063 if kernel code uses it in a preemption-unsafe way. Also, the kernel
1064 will detect preemption count underflows.
1066 menu "Lock Debugging (spinlocks, mutexes, etc...)"
1068 config LOCK_DEBUGGING_SUPPORT
1070 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1073 config PROVE_LOCKING
1074 bool "Lock debugging: prove locking correctness"
1075 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1077 select DEBUG_SPINLOCK
1078 select DEBUG_MUTEXES
1079 select DEBUG_RT_MUTEXES if RT_MUTEXES
1081 select DEBUG_WW_MUTEX_SLOWPATH
1082 select DEBUG_LOCK_ALLOC
1083 select TRACE_IRQFLAGS
1086 This feature enables the kernel to prove that all locking
1087 that occurs in the kernel runtime is mathematically
1088 correct: that under no circumstance could an arbitrary (and
1089 not yet triggered) combination of observed locking
1090 sequences (on an arbitrary number of CPUs, running an
1091 arbitrary number of tasks and interrupt contexts) cause a
1094 In short, this feature enables the kernel to report locking
1095 related deadlocks before they actually occur.
1097 The proof does not depend on how hard and complex a
1098 deadlock scenario would be to trigger: how many
1099 participant CPUs, tasks and irq-contexts would be needed
1100 for it to trigger. The proof also does not depend on
1101 timing: if a race and a resulting deadlock is possible
1102 theoretically (no matter how unlikely the race scenario
1103 is), it will be proven so and will immediately be
1104 reported by the kernel (once the event is observed that
1105 makes the deadlock theoretically possible).
1107 If a deadlock is impossible (i.e. the locking rules, as
1108 observed by the kernel, are mathematically correct), the
1109 kernel reports nothing.
1111 NOTE: this feature can also be enabled for rwlocks, mutexes
1112 and rwsems - in which case all dependencies between these
1113 different locking variants are observed and mapped too, and
1114 the proof of observed correctness is also maintained for an
1115 arbitrary combination of these separate locking variants.
1117 For more details, see Documentation/locking/lockdep-design.rst.
1120 bool "Lock usage statistics"
1121 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1123 select DEBUG_SPINLOCK
1124 select DEBUG_MUTEXES
1125 select DEBUG_RT_MUTEXES if RT_MUTEXES
1126 select DEBUG_LOCK_ALLOC
1129 This feature enables tracking lock contention points
1131 For more details, see Documentation/locking/lockstat.rst
1133 This also enables lock events required by "perf lock",
1135 If you want to use "perf lock", you also need to turn on
1136 CONFIG_EVENT_TRACING.
1138 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1139 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1141 config DEBUG_RT_MUTEXES
1142 bool "RT Mutex debugging, deadlock detection"
1143 depends on DEBUG_KERNEL && RT_MUTEXES
1145 This allows rt mutex semantics violations and rt mutex related
1146 deadlocks (lockups) to be detected and reported automatically.
1148 config DEBUG_SPINLOCK
1149 bool "Spinlock and rw-lock debugging: basic checks"
1150 depends on DEBUG_KERNEL
1151 select UNINLINE_SPIN_UNLOCK
1153 Say Y here and build SMP to catch missing spinlock initialization
1154 and certain other kinds of spinlock errors commonly made. This is
1155 best used in conjunction with the NMI watchdog so that spinlock
1156 deadlocks are also debuggable.
1158 config DEBUG_MUTEXES
1159 bool "Mutex debugging: basic checks"
1160 depends on DEBUG_KERNEL
1162 This feature allows mutex semantics violations to be detected and
1165 config DEBUG_WW_MUTEX_SLOWPATH
1166 bool "Wait/wound mutex debugging: Slowpath testing"
1167 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1168 select DEBUG_LOCK_ALLOC
1169 select DEBUG_SPINLOCK
1170 select DEBUG_MUTEXES
1172 This feature enables slowpath testing for w/w mutex users by
1173 injecting additional -EDEADLK wound/backoff cases. Together with
1174 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1175 will test all possible w/w mutex interface abuse with the
1176 exception of simply not acquiring all the required locks.
1177 Note that this feature can introduce significant overhead, so
1178 it really should not be enabled in a production or distro kernel,
1179 even a debug kernel. If you are a driver writer, enable it. If
1180 you are a distro, do not.
1183 bool "RW Semaphore debugging: basic checks"
1184 depends on DEBUG_KERNEL
1186 This debugging feature allows mismatched rw semaphore locks
1187 and unlocks to be detected and reported.
1189 config DEBUG_LOCK_ALLOC
1190 bool "Lock debugging: detect incorrect freeing of live locks"
1191 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1192 select DEBUG_SPINLOCK
1193 select DEBUG_MUTEXES
1194 select DEBUG_RT_MUTEXES if RT_MUTEXES
1197 This feature will check whether any held lock (spinlock, rwlock,
1198 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1199 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1200 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1201 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1202 held during task exit.
1206 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1208 select FRAME_POINTER if !MIPS && !PPC && !ARM && !S390 && !MICROBLAZE && !ARC && !X86
1212 config LOCKDEP_SMALL
1215 config DEBUG_LOCKDEP
1216 bool "Lock dependency engine debugging"
1217 depends on DEBUG_KERNEL && LOCKDEP
1219 If you say Y here, the lock dependency engine will do
1220 additional runtime checks to debug itself, at the price
1221 of more runtime overhead.
1223 config DEBUG_ATOMIC_SLEEP
1224 bool "Sleep inside atomic section checking"
1225 select PREEMPT_COUNT
1226 depends on DEBUG_KERNEL
1227 depends on !ARCH_NO_PREEMPT
1229 If you say Y here, various routines which may sleep will become very
1230 noisy if they are called inside atomic sections: when a spinlock is
1231 held, inside an rcu read side critical section, inside preempt disabled
1232 sections, inside an interrupt, etc...
1234 config DEBUG_LOCKING_API_SELFTESTS
1235 bool "Locking API boot-time self-tests"
1236 depends on DEBUG_KERNEL
1238 Say Y here if you want the kernel to run a short self-test during
1239 bootup. The self-test checks whether common types of locking bugs
1240 are detected by debugging mechanisms or not. (if you disable
1241 lock debugging then those bugs wont be detected of course.)
1242 The following locking APIs are covered: spinlocks, rwlocks,
1245 config LOCK_TORTURE_TEST
1246 tristate "torture tests for locking"
1247 depends on DEBUG_KERNEL
1250 This option provides a kernel module that runs torture tests
1251 on kernel locking primitives. The kernel module may be built
1252 after the fact on the running kernel to be tested, if desired.
1254 Say Y here if you want kernel locking-primitive torture tests
1255 to be built into the kernel.
1256 Say M if you want these torture tests to build as a module.
1257 Say N if you are unsure.
1259 config WW_MUTEX_SELFTEST
1260 tristate "Wait/wound mutex selftests"
1262 This option provides a kernel module that runs tests on the
1263 on the struct ww_mutex locking API.
1265 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1266 with this test harness.
1268 Say M if you want these self tests to build as a module.
1269 Say N if you are unsure.
1271 endmenu # lock debugging
1273 config TRACE_IRQFLAGS
1276 Enables hooks to interrupt enabling and disabling for
1277 either tracing or lock debugging.
1280 bool "Stack backtrace support"
1281 depends on STACKTRACE_SUPPORT
1283 This option causes the kernel to create a /proc/pid/stack for
1284 every process, showing its current stack trace.
1285 It is also used by various kernel debugging features that require
1286 stack trace generation.
1288 config WARN_ALL_UNSEEDED_RANDOM
1289 bool "Warn for all uses of unseeded randomness"
1292 Some parts of the kernel contain bugs relating to their use of
1293 cryptographically secure random numbers before it's actually possible
1294 to generate those numbers securely. This setting ensures that these
1295 flaws don't go unnoticed, by enabling a message, should this ever
1296 occur. This will allow people with obscure setups to know when things
1297 are going wrong, so that they might contact developers about fixing
1300 Unfortunately, on some models of some architectures getting
1301 a fully seeded CRNG is extremely difficult, and so this can
1302 result in dmesg getting spammed for a surprisingly long
1303 time. This is really bad from a security perspective, and
1304 so architecture maintainers really need to do what they can
1305 to get the CRNG seeded sooner after the system is booted.
1306 However, since users cannot do anything actionable to
1307 address this, by default the kernel will issue only a single
1308 warning for the first use of unseeded randomness.
1310 Say Y here if you want to receive warnings for all uses of
1311 unseeded randomness. This will be of use primarily for
1312 those developers interested in improving the security of
1313 Linux kernels running on their architecture (or
1316 config DEBUG_KOBJECT
1317 bool "kobject debugging"
1318 depends on DEBUG_KERNEL
1320 If you say Y here, some extra kobject debugging messages will be sent
1323 config DEBUG_KOBJECT_RELEASE
1324 bool "kobject release debugging"
1325 depends on DEBUG_OBJECTS_TIMERS
1327 kobjects are reference counted objects. This means that their
1328 last reference count put is not predictable, and the kobject can
1329 live on past the point at which a driver decides to drop it's
1330 initial reference to the kobject gained on allocation. An
1331 example of this would be a struct device which has just been
1334 However, some buggy drivers assume that after such an operation,
1335 the memory backing the kobject can be immediately freed. This
1336 goes completely against the principles of a refcounted object.
1338 If you say Y here, the kernel will delay the release of kobjects
1339 on the last reference count to improve the visibility of this
1340 kind of kobject release bug.
1342 config HAVE_DEBUG_BUGVERBOSE
1345 config DEBUG_BUGVERBOSE
1346 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
1347 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
1350 Say Y here to make BUG() panics output the file name and line number
1351 of the BUG call as well as the EIP and oops trace. This aids
1352 debugging but costs about 70-100K of memory.
1355 bool "Debug linked list manipulation"
1356 depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION
1358 Enable this to turn on extended checks in the linked-list
1364 bool "Debug priority linked list manipulation"
1365 depends on DEBUG_KERNEL
1367 Enable this to turn on extended checks in the priority-ordered
1368 linked-list (plist) walking routines. This checks the entire
1369 list multiple times during each manipulation.
1374 bool "Debug SG table operations"
1375 depends on DEBUG_KERNEL
1377 Enable this to turn on checks on scatter-gather tables. This can
1378 help find problems with drivers that do not properly initialize
1383 config DEBUG_NOTIFIERS
1384 bool "Debug notifier call chains"
1385 depends on DEBUG_KERNEL
1387 Enable this to turn on sanity checking for notifier call chains.
1388 This is most useful for kernel developers to make sure that
1389 modules properly unregister themselves from notifier chains.
1390 This is a relatively cheap check but if you care about maximum
1393 config DEBUG_CREDENTIALS
1394 bool "Debug credential management"
1395 depends on DEBUG_KERNEL
1397 Enable this to turn on some debug checking for credential
1398 management. The additional code keeps track of the number of
1399 pointers from task_structs to any given cred struct, and checks to
1400 see that this number never exceeds the usage count of the cred
1403 Furthermore, if SELinux is enabled, this also checks that the
1404 security pointer in the cred struct is never seen to be invalid.
1408 source "kernel/rcu/Kconfig.debug"
1410 config DEBUG_WQ_FORCE_RR_CPU
1411 bool "Force round-robin CPU selection for unbound work items"
1412 depends on DEBUG_KERNEL
1415 Workqueue used to implicitly guarantee that work items queued
1416 without explicit CPU specified are put on the local CPU. This
1417 guarantee is no longer true and while local CPU is still
1418 preferred work items may be put on foreign CPUs. Kernel
1419 parameter "workqueue.debug_force_rr_cpu" is added to force
1420 round-robin CPU selection to flush out usages which depend on the
1421 now broken guarantee. This config option enables the debug
1422 feature by default. When enabled, memory and cache locality will
1425 config DEBUG_BLOCK_EXT_DEVT
1426 bool "Force extended block device numbers and spread them"
1427 depends on DEBUG_KERNEL
1431 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1432 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1433 YOU ARE DOING. Distros, please enable this and fix whatever
1436 Conventionally, block device numbers are allocated from
1437 predetermined contiguous area. However, extended block area
1438 may introduce non-contiguous block device numbers. This
1439 option forces most block device numbers to be allocated from
1440 the extended space and spreads them to discover kernel or
1441 userland code paths which assume predetermined contiguous
1442 device number allocation.
1444 Note that turning on this debug option shuffles all the
1445 device numbers for all IDE and SCSI devices including libata
1446 ones, so root partition specified using device number
1447 directly (via rdev or root=MAJ:MIN) won't work anymore.
1448 Textual device names (root=/dev/sdXn) will continue to work.
1450 Say N if you are unsure.
1452 config CPU_HOTPLUG_STATE_CONTROL
1453 bool "Enable CPU hotplug state control"
1454 depends on DEBUG_KERNEL
1455 depends on HOTPLUG_CPU
1458 Allows to write steps between "offline" and "online" to the CPUs
1459 sysfs target file so states can be stepped granular. This is a debug
1460 option for now as the hotplug machinery cannot be stopped and
1461 restarted at arbitrary points yet.
1463 Say N if your are unsure.
1465 config NOTIFIER_ERROR_INJECTION
1466 tristate "Notifier error injection"
1467 depends on DEBUG_KERNEL
1470 This option provides the ability to inject artificial errors to
1471 specified notifier chain callbacks. It is useful to test the error
1472 handling of notifier call chain failures.
1476 config PM_NOTIFIER_ERROR_INJECT
1477 tristate "PM notifier error injection module"
1478 depends on PM && NOTIFIER_ERROR_INJECTION
1479 default m if PM_DEBUG
1481 This option provides the ability to inject artificial errors to
1482 PM notifier chain callbacks. It is controlled through debugfs
1483 interface /sys/kernel/debug/notifier-error-inject/pm
1485 If the notifier call chain should be failed with some events
1486 notified, write the error code to "actions/<notifier event>/error".
1488 Example: Inject PM suspend error (-12 = -ENOMEM)
1490 # cd /sys/kernel/debug/notifier-error-inject/pm/
1491 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1492 # echo mem > /sys/power/state
1493 bash: echo: write error: Cannot allocate memory
1495 To compile this code as a module, choose M here: the module will
1496 be called pm-notifier-error-inject.
1500 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1501 tristate "OF reconfig notifier error injection module"
1502 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1504 This option provides the ability to inject artificial errors to
1505 OF reconfig notifier chain callbacks. It is controlled
1506 through debugfs interface under
1507 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1509 If the notifier call chain should be failed with some events
1510 notified, write the error code to "actions/<notifier event>/error".
1512 To compile this code as a module, choose M here: the module will
1513 be called of-reconfig-notifier-error-inject.
1517 config NETDEV_NOTIFIER_ERROR_INJECT
1518 tristate "Netdev notifier error injection module"
1519 depends on NET && NOTIFIER_ERROR_INJECTION
1521 This option provides the ability to inject artificial errors to
1522 netdevice notifier chain callbacks. It is controlled through debugfs
1523 interface /sys/kernel/debug/notifier-error-inject/netdev
1525 If the notifier call chain should be failed with some events
1526 notified, write the error code to "actions/<notifier event>/error".
1528 Example: Inject netdevice mtu change error (-22 = -EINVAL)
1530 # cd /sys/kernel/debug/notifier-error-inject/netdev
1531 # echo -22 > actions/NETDEV_CHANGEMTU/error
1532 # ip link set eth0 mtu 1024
1533 RTNETLINK answers: Invalid argument
1535 To compile this code as a module, choose M here: the module will
1536 be called netdev-notifier-error-inject.
1540 config FUNCTION_ERROR_INJECTION
1542 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
1544 config FAULT_INJECTION
1545 bool "Fault-injection framework"
1546 depends on DEBUG_KERNEL
1548 Provide fault-injection framework.
1549 For more details, see Documentation/fault-injection/.
1552 bool "Fault-injection capability for kmalloc"
1553 depends on FAULT_INJECTION
1554 depends on SLAB || SLUB
1556 Provide fault-injection capability for kmalloc.
1558 config FAIL_PAGE_ALLOC
1559 bool "Fault-injection capabilitiy for alloc_pages()"
1560 depends on FAULT_INJECTION
1562 Provide fault-injection capability for alloc_pages().
1564 config FAIL_MAKE_REQUEST
1565 bool "Fault-injection capability for disk IO"
1566 depends on FAULT_INJECTION && BLOCK
1568 Provide fault-injection capability for disk IO.
1570 config FAIL_IO_TIMEOUT
1571 bool "Fault-injection capability for faking disk interrupts"
1572 depends on FAULT_INJECTION && BLOCK
1574 Provide fault-injection capability on end IO handling. This
1575 will make the block layer "forget" an interrupt as configured,
1576 thus exercising the error handling.
1578 Only works with drivers that use the generic timeout handling,
1579 for others it wont do anything.
1582 bool "Fault-injection capability for futexes"
1584 depends on FAULT_INJECTION && FUTEX
1586 Provide fault-injection capability for futexes.
1588 config FAULT_INJECTION_DEBUG_FS
1589 bool "Debugfs entries for fault-injection capabilities"
1590 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1592 Enable configuration of fault-injection capabilities via debugfs.
1594 config FAIL_FUNCTION
1595 bool "Fault-injection capability for functions"
1596 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
1598 Provide function-based fault-injection capability.
1599 This will allow you to override a specific function with a return
1600 with given return value. As a result, function caller will see
1601 an error value and have to handle it. This is useful to test the
1602 error handling in various subsystems.
1604 config FAIL_MMC_REQUEST
1605 bool "Fault-injection capability for MMC IO"
1606 depends on FAULT_INJECTION_DEBUG_FS && MMC
1608 Provide fault-injection capability for MMC IO.
1609 This will make the mmc core return data errors. This is
1610 useful to test the error handling in the mmc block device
1611 and to test how the mmc host driver handles retries from
1614 config FAULT_INJECTION_STACKTRACE_FILTER
1615 bool "stacktrace filter for fault-injection capabilities"
1616 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1619 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86
1621 Provide stacktrace filter for fault-injection capabilities
1624 bool "Latency measuring infrastructure"
1625 depends on DEBUG_KERNEL
1626 depends on STACKTRACE_SUPPORT
1628 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86
1635 Enable this option if you want to use the LatencyTOP tool
1636 to find out which userspace is blocking on what kernel operations.
1638 source "kernel/trace/Kconfig"
1640 config PROVIDE_OHCI1394_DMA_INIT
1641 bool "Remote debugging over FireWire early on boot"
1642 depends on PCI && X86
1644 If you want to debug problems which hang or crash the kernel early
1645 on boot and the crashing machine has a FireWire port, you can use
1646 this feature to remotely access the memory of the crashed machine
1647 over FireWire. This employs remote DMA as part of the OHCI1394
1648 specification which is now the standard for FireWire controllers.
1650 With remote DMA, you can monitor the printk buffer remotely using
1651 firescope and access all memory below 4GB using fireproxy from gdb.
1652 Even controlling a kernel debugger is possible using remote DMA.
1656 If ohci1394_dma=early is used as boot parameter, it will initialize
1657 all OHCI1394 controllers which are found in the PCI config space.
1659 As all changes to the FireWire bus such as enabling and disabling
1660 devices cause a bus reset and thereby disable remote DMA for all
1661 devices, be sure to have the cable plugged and FireWire enabled on
1662 the debugging host before booting the debug target for debugging.
1664 This code (~1k) is freed after boot. By then, the firewire stack
1665 in charge of the OHCI-1394 controllers should be used instead.
1667 See Documentation/debugging-via-ohci1394.txt for more information.
1669 menuconfig RUNTIME_TESTING_MENU
1670 bool "Runtime Testing"
1673 if RUNTIME_TESTING_MENU
1676 tristate "Linux Kernel Dump Test Tool Module"
1679 This module enables testing of the different dumping mechanisms by
1680 inducing system failures at predefined crash points.
1681 If you don't need it: say N
1682 Choose M here to compile this code as a module. The module will be
1685 Documentation on how to use the module can be found in
1686 Documentation/fault-injection/provoke-crashes.rst
1688 config TEST_LIST_SORT
1689 tristate "Linked list sorting test"
1690 depends on DEBUG_KERNEL || m
1692 Enable this to turn on 'list_sort()' function test. This test is
1693 executed only once during system boot (so affects only boot time),
1694 or at module load time.
1699 tristate "Array-based sort test"
1700 depends on DEBUG_KERNEL || m
1702 This option enables the self-test function of 'sort()' at boot,
1703 or at module load time.
1707 config KPROBES_SANITY_TEST
1708 bool "Kprobes sanity tests"
1709 depends on DEBUG_KERNEL
1712 This option provides for testing basic kprobes functionality on
1713 boot. Samples of kprobe and kretprobe are inserted and
1714 verified for functionality.
1716 Say N if you are unsure.
1718 config BACKTRACE_SELF_TEST
1719 tristate "Self test for the backtrace code"
1720 depends on DEBUG_KERNEL
1722 This option provides a kernel module that can be used to test
1723 the kernel stack backtrace code. This option is not useful
1724 for distributions or general kernels, but only for kernel
1725 developers working on architecture code.
1727 Note that if you want to also test saved backtraces, you will
1728 have to enable STACKTRACE as well.
1730 Say N if you are unsure.
1733 tristate "Red-Black tree test"
1734 depends on DEBUG_KERNEL
1736 A benchmark measuring the performance of the rbtree library.
1737 Also includes rbtree invariant checks.
1739 config REED_SOLOMON_TEST
1740 tristate "Reed-Solomon library test"
1741 depends on DEBUG_KERNEL || m
1743 select REED_SOLOMON_ENC16
1744 select REED_SOLOMON_DEC16
1746 This option enables the self-test function of rslib at boot,
1747 or at module load time.
1751 config INTERVAL_TREE_TEST
1752 tristate "Interval tree test"
1753 depends on DEBUG_KERNEL
1754 select INTERVAL_TREE
1756 A benchmark measuring the performance of the interval tree library
1759 tristate "Per cpu operations test"
1760 depends on m && DEBUG_KERNEL
1762 Enable this option to build test module which validates per-cpu
1767 config ATOMIC64_SELFTEST
1768 tristate "Perform an atomic64_t self-test"
1770 Enable this option to test the atomic64_t functions at boot or
1771 at module load time.
1775 config ASYNC_RAID6_TEST
1776 tristate "Self test for hardware accelerated raid6 recovery"
1777 depends on ASYNC_RAID6_RECOV
1780 This is a one-shot self test that permutes through the
1781 recovery of all the possible two disk failure scenarios for a
1782 N-disk array. Recovery is performed with the asynchronous
1783 raid6 recovery routines, and will optionally use an offload
1784 engine if one is available.
1789 tristate "Test functions located in the hexdump module at runtime"
1791 config TEST_STRING_HELPERS
1792 tristate "Test functions located in the string_helpers module at runtime"
1795 tristate "Test strscpy*() family of functions at runtime"
1798 tristate "Test kstrto*() family of functions at runtime"
1801 tristate "Test printf() family of functions at runtime"
1804 tristate "Test bitmap_*() family of functions at runtime"
1806 Enable this option to test the bitmap functions at boot.
1810 config TEST_BITFIELD
1811 tristate "Test bitfield functions at runtime"
1813 Enable this option to test the bitfield functions at boot.
1818 tristate "Test functions located in the uuid module at runtime"
1821 tristate "Test the XArray code at runtime"
1823 config TEST_OVERFLOW
1824 tristate "Test check_*_overflow() functions at runtime"
1826 config TEST_RHASHTABLE
1827 tristate "Perform selftest on resizable hash table"
1829 Enable this option to test the rhashtable functions at boot.
1834 tristate "Perform selftest on hash functions"
1836 Enable this option to test the kernel's integer (<linux/hash.h>),
1837 string (<linux/stringhash.h>), and siphash (<linux/siphash.h>)
1838 hash functions on boot (or module load).
1840 This is intended to help people writing architecture-specific
1841 optimized versions. If unsure, say N.
1844 tristate "Perform selftest on IDA functions"
1847 tristate "Perform selftest on priority array manager"
1850 Enable this option to test priority array manager on boot
1855 config TEST_IRQ_TIMINGS
1856 bool "IRQ timings selftest"
1857 depends on IRQ_TIMINGS
1859 Enable this option to test the irq timings code on boot.
1864 tristate "Test module loading with 'hello world' module"
1867 This builds the "test_module" module that emits "Hello, world"
1868 on printk when loaded. It is designed to be used for basic
1869 evaluation of the module loading subsystem (for example when
1870 validating module verification). It lacks any extra dependencies,
1871 and will not normally be loaded by the system unless explicitly
1877 tristate "Test module for stress/performance analysis of vmalloc allocator"
1882 This builds the "test_vmalloc" module that should be used for
1883 stress and performance analysis. So, any new change for vmalloc
1884 subsystem can be evaluated from performance and stability point
1889 config TEST_USER_COPY
1890 tristate "Test user/kernel boundary protections"
1893 This builds the "test_user_copy" module that runs sanity checks
1894 on the copy_to/from_user infrastructure, making sure basic
1895 user/kernel boundary testing is working. If it fails to load,
1896 a regression has been detected in the user/kernel memory boundary
1902 tristate "Test BPF filter functionality"
1905 This builds the "test_bpf" module that runs various test vectors
1906 against the BPF interpreter or BPF JIT compiler depending on the
1907 current setting. This is in particular useful for BPF JIT compiler
1908 development, but also to run regression tests against changes in
1909 the interpreter code. It also enables test stubs for eBPF maps and
1910 verifier used by user space verifier testsuite.
1914 config TEST_BLACKHOLE_DEV
1915 tristate "Test blackhole netdev functionality"
1918 This builds the "test_blackhole_dev" module that validates the
1919 data path through this blackhole netdev.
1923 config FIND_BIT_BENCHMARK
1924 tristate "Test find_bit functions"
1926 This builds the "test_find_bit" module that measure find_*_bit()
1927 functions performance.
1931 config TEST_FIRMWARE
1932 tristate "Test firmware loading via userspace interface"
1933 depends on FW_LOADER
1935 This builds the "test_firmware" module that creates a userspace
1936 interface for testing firmware loading. This can be used to
1937 control the triggering of firmware loading without needing an
1938 actual firmware-using device. The contents can be rechecked by
1944 tristate "sysctl test driver"
1945 depends on PROC_SYSCTL
1947 This builds the "test_sysctl" module. This driver enables to test the
1948 proc sysctl interfaces available to drivers safely without affecting
1949 production knobs which might alter system functionality.
1954 tristate "udelay test driver"
1956 This builds the "udelay_test" module that helps to make sure
1957 that udelay() is working properly.
1961 config TEST_STATIC_KEYS
1962 tristate "Test static keys"
1965 Test the static key interfaces.
1970 tristate "kmod stress tester"
1972 depends on NETDEVICES && NET_CORE && INET # for TUN
1979 Test the kernel's module loading mechanism: kmod. kmod implements
1980 support to load modules using the Linux kernel's usermode helper.
1981 This test provides a series of tests against kmod.
1983 Although technically you can either build test_kmod as a module or
1984 into the kernel we disallow building it into the kernel since
1985 it stress tests request_module() and this will very likely cause
1986 some issues by taking over precious threads available from other
1987 module load requests, ultimately this could be fatal.
1991 tools/testing/selftests/kmod/kmod.sh --help
1995 config TEST_DEBUG_VIRTUAL
1996 tristate "Test CONFIG_DEBUG_VIRTUAL feature"
1997 depends on DEBUG_VIRTUAL
1999 Test the kernel's ability to detect incorrect calls to
2000 virt_to_phys() done against the non-linear part of the
2001 kernel's virtual address map.
2005 config TEST_MEMCAT_P
2006 tristate "Test memcat_p() helper function"
2008 Test the memcat_p() helper for correctly merging two
2009 pointer arrays together.
2013 config TEST_LIVEPATCH
2014 tristate "Test livepatching"
2016 depends on DYNAMIC_DEBUG
2017 depends on LIVEPATCH
2020 Test kernel livepatching features for correctness. The tests will
2021 load test modules that will be livepatched in various scenarios.
2023 To run all the livepatching tests:
2025 make -C tools/testing/selftests TARGETS=livepatch run_tests
2027 Alternatively, individual tests may be invoked:
2029 tools/testing/selftests/livepatch/test-callbacks.sh
2030 tools/testing/selftests/livepatch/test-livepatch.sh
2031 tools/testing/selftests/livepatch/test-shadow-vars.sh
2036 tristate "Perform selftest on object aggreration manager"
2040 Enable this option to test object aggregation manager on boot
2044 config TEST_STACKINIT
2045 tristate "Test level of stack variable initialization"
2047 Test if the kernel is zero-initializing stack variables and
2048 padding. Coverage is controlled by compiler flags,
2049 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2050 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2055 tristate "Test heap/page initialization"
2057 Test if the kernel is zero-initializing heap and page allocations.
2058 This can be useful to test init_on_alloc and init_on_free features.
2062 endif # RUNTIME_TESTING_MENU
2067 This option adds a kernel parameter 'memtest', which allows memtest
2069 memtest=0, mean disabled; -- default
2070 memtest=1, mean do 1 test pattern;
2072 memtest=17, mean do 17 test patterns.
2073 If you are unsure how to answer this question, answer N.
2075 config BUG_ON_DATA_CORRUPTION
2076 bool "Trigger a BUG when data corruption is detected"
2079 Select this option if the kernel should BUG when it encounters
2080 data corruption in kernel memory structures when they get checked
2085 source "samples/Kconfig"
2087 source "lib/Kconfig.kgdb"
2089 source "lib/Kconfig.ubsan"
2091 config ARCH_HAS_DEVMEM_IS_ALLOWED
2094 config STRICT_DEVMEM
2095 bool "Filter access to /dev/mem"
2096 depends on MMU && DEVMEM
2097 depends on ARCH_HAS_DEVMEM_IS_ALLOWED
2098 default y if PPC || X86 || ARM64
2100 If this option is disabled, you allow userspace (root) access to all
2101 of memory, including kernel and userspace memory. Accidental
2102 access to this is obviously disastrous, but specific access can
2103 be used by people debugging the kernel. Note that with PAT support
2104 enabled, even in this case there are restrictions on /dev/mem
2105 use due to the cache aliasing requirements.
2107 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
2108 file only allows userspace access to PCI space and the BIOS code and
2109 data regions. This is sufficient for dosemu and X and all common
2114 config IO_STRICT_DEVMEM
2115 bool "Filter I/O access to /dev/mem"
2116 depends on STRICT_DEVMEM
2118 If this option is disabled, you allow userspace (root) access to all
2119 io-memory regardless of whether a driver is actively using that
2120 range. Accidental access to this is obviously disastrous, but
2121 specific access can be used by people debugging kernel drivers.
2123 If this option is switched on, the /dev/mem file only allows
2124 userspace access to *idle* io-memory ranges (see /proc/iomem) This
2125 may break traditional users of /dev/mem (dosemu, legacy X, etc...)
2126 if the driver using a given range cannot be disabled.
2130 source "arch/$(SRCARCH)/Kconfig.debug"
2132 endmenu # Kernel hacking
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