1 menu "printk and dmesg options"
4 bool "Show timing information on printks"
7 Selecting this option causes time stamps of the printk()
8 messages to be added to the output of the syslog() system
9 call and at the console.
11 The timestamp is always recorded internally, and exported
12 to /dev/kmsg. This flag just specifies if the timestamp should
13 be included, not that the timestamp is recorded.
15 The behavior is also controlled by the kernel command line
16 parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst
18 config CONSOLE_LOGLEVEL_DEFAULT
19 int "Default console loglevel (1-15)"
23 Default loglevel to determine what will be printed on the console.
25 Setting a default here is equivalent to passing in loglevel=<x> in
26 the kernel bootargs. loglevel=<x> continues to override whatever
27 value is specified here as well.
29 Note: This does not affect the log level of un-prefixed printk()
30 usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT
34 bool "Show process information on printks"
37 Selecting this option causes process to be
38 included in printk output. Or add printk.process=1 at boot-time.
40 config PRINTK_UTC_TIME
41 bool "Show utc information on printks"
44 Selecting this option causes utc to be
45 included in printk output.
47 config MESSAGE_LOGLEVEL_DEFAULT
48 int "Default message log level (1-7)"
52 Default log level for printk statements with no specified priority.
54 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
55 that are auditing their logs closely may want to set it to a lower
58 Note: This does not affect what message level gets printed on the console
59 by default. To change that, use loglevel=<x> in the kernel bootargs,
60 or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value.
62 config BOOT_PRINTK_DELAY
63 bool "Delay each boot printk message by N milliseconds"
64 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
66 This build option allows you to read kernel boot messages
67 by inserting a short delay after each one. The delay is
68 specified in milliseconds on the kernel command line,
71 It is likely that you would also need to use "lpj=M" to preset
72 the "loops per jiffie" value.
73 See a previous boot log for the "lpj" value to use for your
74 system, and then set "lpj=M" before setting "boot_delay=N".
75 NOTE: Using this option may adversely affect SMP systems.
76 I.e., processors other than the first one may not boot up.
77 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
78 what it believes to be lockup conditions.
81 bool "Enable dynamic printk() support"
87 Compiles debug level messages into the kernel, which would not
88 otherwise be available at runtime. These messages can then be
89 enabled/disabled based on various levels of scope - per source file,
90 function, module, format string, and line number. This mechanism
91 implicitly compiles in all pr_debug() and dev_dbg() calls, which
92 enlarges the kernel text size by about 2%.
94 If a source file is compiled with DEBUG flag set, any
95 pr_debug() calls in it are enabled by default, but can be
96 disabled at runtime as below. Note that DEBUG flag is
97 turned on by many CONFIG_*DEBUG* options.
101 Dynamic debugging is controlled via the 'dynamic_debug/control' file,
102 which is contained in the 'debugfs' filesystem. Thus, the debugfs
103 filesystem must first be mounted before making use of this feature.
104 We refer the control file as: <debugfs>/dynamic_debug/control. This
105 file contains a list of the debug statements that can be enabled. The
106 format for each line of the file is:
108 filename:lineno [module]function flags format
110 filename : source file of the debug statement
111 lineno : line number of the debug statement
112 module : module that contains the debug statement
113 function : function that contains the debug statement
114 flags : '=p' means the line is turned 'on' for printing
115 format : the format used for the debug statement
119 nullarbor:~ # cat <debugfs>/dynamic_debug/control
120 # filename:lineno [module]function flags format
121 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
122 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
123 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
127 // enable the message at line 1603 of file svcsock.c
128 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
129 <debugfs>/dynamic_debug/control
131 // enable all the messages in file svcsock.c
132 nullarbor:~ # echo -n 'file svcsock.c +p' >
133 <debugfs>/dynamic_debug/control
135 // enable all the messages in the NFS server module
136 nullarbor:~ # echo -n 'module nfsd +p' >
137 <debugfs>/dynamic_debug/control
139 // enable all 12 messages in the function svc_process()
140 nullarbor:~ # echo -n 'func svc_process +p' >
141 <debugfs>/dynamic_debug/control
143 // disable all 12 messages in the function svc_process()
144 nullarbor:~ # echo -n 'func svc_process -p' >
145 <debugfs>/dynamic_debug/control
147 See Documentation/admin-guide/dynamic-debug-howto.rst for additional
150 endmenu # "printk and dmesg options"
152 menu "Compile-time checks and compiler options"
155 bool "Compile the kernel with debug info"
156 depends on DEBUG_KERNEL && !COMPILE_TEST
158 If you say Y here the resulting kernel image will include
159 debugging info resulting in a larger kernel image.
160 This adds debug symbols to the kernel and modules (gcc -g), and
161 is needed if you intend to use kernel crashdump or binary object
162 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
163 Say Y here only if you plan to debug the kernel.
167 config DEBUG_INFO_REDUCED
168 bool "Reduce debugging information"
169 depends on DEBUG_INFO
171 If you say Y here gcc is instructed to generate less debugging
172 information for structure types. This means that tools that
173 need full debugging information (like kgdb or systemtap) won't
174 be happy. But if you merely need debugging information to
175 resolve line numbers there is no loss. Advantage is that
176 build directory object sizes shrink dramatically over a full
177 DEBUG_INFO build and compile times are reduced too.
178 Only works with newer gcc versions.
180 config DEBUG_INFO_SPLIT
181 bool "Produce split debuginfo in .dwo files"
182 depends on DEBUG_INFO && !FRV
184 Generate debug info into separate .dwo files. This significantly
185 reduces the build directory size for builds with DEBUG_INFO,
186 because it stores the information only once on disk in .dwo
187 files instead of multiple times in object files and executables.
188 In addition the debug information is also compressed.
190 Requires recent gcc (4.7+) and recent gdb/binutils.
191 Any tool that packages or reads debug information would need
192 to know about the .dwo files and include them.
193 Incompatible with older versions of ccache.
195 config DEBUG_INFO_DWARF4
196 bool "Generate dwarf4 debuginfo"
197 depends on DEBUG_INFO
199 Generate dwarf4 debug info. This requires recent versions
200 of gcc and gdb. It makes the debug information larger.
201 But it significantly improves the success of resolving
202 variables in gdb on optimized code.
205 bool "Provide GDB scripts for kernel debugging"
206 depends on DEBUG_INFO
208 This creates the required links to GDB helper scripts in the
209 build directory. If you load vmlinux into gdb, the helper
210 scripts will be automatically imported by gdb as well, and
211 additional functions are available to analyze a Linux kernel
212 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
215 config ENABLE_WARN_DEPRECATED
216 bool "Enable __deprecated logic"
219 Enable the __deprecated logic in the kernel build.
220 Disable this to suppress the "warning: 'foo' is deprecated
221 (declared at kernel/power/somefile.c:1234)" messages.
223 config ENABLE_MUST_CHECK
224 bool "Enable __must_check logic"
227 Enable the __must_check logic in the kernel build. Disable this to
228 suppress the "warning: ignoring return value of 'foo', declared with
229 attribute warn_unused_result" messages.
232 int "Warn for stack frames larger than (needs gcc 4.4)"
234 default 3072 if KASAN_EXTRA
235 default 2048 if GCC_PLUGIN_LATENT_ENTROPY
236 default 1280 if (!64BIT && PARISC)
237 default 1024 if (!64BIT && !PARISC)
238 default 2048 if 64BIT
240 Tell gcc to warn at build time for stack frames larger than this.
241 Setting this too low will cause a lot of warnings.
242 Setting it to 0 disables the warning.
245 config STRIP_ASM_SYMS
246 bool "Strip assembler-generated symbols during link"
249 Strip internal assembler-generated symbols during a link (symbols
250 that look like '.Lxxx') so they don't pollute the output of
251 get_wchan() and suchlike.
254 bool "Generate readable assembler code"
255 depends on DEBUG_KERNEL
257 Disable some compiler optimizations that tend to generate human unreadable
258 assembler output. This may make the kernel slightly slower, but it helps
259 to keep kernel developers who have to stare a lot at assembler listings
262 config UNUSED_SYMBOLS
263 bool "Enable unused/obsolete exported symbols"
266 Unused but exported symbols make the kernel needlessly bigger. For
267 that reason most of these unused exports will soon be removed. This
268 option is provided temporarily to provide a transition period in case
269 some external kernel module needs one of these symbols anyway. If you
270 encounter such a case in your module, consider if you are actually
271 using the right API. (rationale: since nobody in the kernel is using
272 this in a module, there is a pretty good chance it's actually the
273 wrong interface to use). If you really need the symbol, please send a
274 mail to the linux kernel mailing list mentioning the symbol and why
275 you really need it, and what the merge plan to the mainline kernel for
279 bool "Track page owner"
280 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
284 select PAGE_EXTENSION
286 This keeps track of what call chain is the owner of a page, may
287 help to find bare alloc_page(s) leaks. Even if you include this
288 feature on your build, it is disabled in default. You should pass
289 "page_owner=on" to boot parameter in order to enable it. Eats
290 a fair amount of memory if enabled. See tools/vm/page_owner_sort.c
291 for user-space helper.
295 config PAGE_OWNER_ENABLE_DEFAULT
296 bool "Enable Track page owner by default"
297 depends on PAGE_OWNER
299 This keeps track of what call chain is the owner of a page, may
300 help to find bare alloc_page(s) leaks. If you include this
301 feature on your build, it is enabled by default. You should pass
302 "page_owner=off" to boot parameter in order to disable it. Eats
303 a fair amount of memory if enabled. See tools/vm/page_owner_sort.c
304 for user-space helper.
307 bool "Debug Filesystem"
309 debugfs is a virtual file system that kernel developers use to put
310 debugging files into. Enable this option to be able to read and
311 write to these files.
313 For detailed documentation on the debugfs API, see
314 Documentation/filesystems/.
319 bool "Run 'make headers_check' when building vmlinux"
322 This option will extract the user-visible kernel headers whenever
323 building the kernel, and will run basic sanity checks on them to
324 ensure that exported files do not attempt to include files which
325 were not exported, etc.
327 If you're making modifications to header files which are
328 relevant for userspace, say 'Y', and check the headers
329 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
330 your build tree), to make sure they're suitable.
332 config DEBUG_SECTION_MISMATCH
333 bool "Enable full Section mismatch analysis"
335 The section mismatch analysis checks if there are illegal
336 references from one section to another section.
337 During linktime or runtime, some sections are dropped;
338 any use of code/data previously in these sections would
339 most likely result in an oops.
340 In the code, functions and variables are annotated with
341 __init,, etc. (see the full list in include/linux/init.h),
342 which results in the code/data being placed in specific sections.
343 The section mismatch analysis is always performed after a full
344 kernel build, and enabling this option causes the following
345 additional steps to occur:
346 - Add the option -fno-inline-functions-called-once to gcc commands.
347 When inlining a function annotated with __init in a non-init
348 function, we would lose the section information and thus
349 the analysis would not catch the illegal reference.
350 This option tells gcc to inline less (but it does result in
352 - Run the section mismatch analysis for each module/built-in.o file.
353 When we run the section mismatch analysis on vmlinux.o, we
354 lose valuable information about where the mismatch was
356 Running the analysis for each module/built-in.o file
357 tells where the mismatch happens much closer to the
358 source. The drawback is that the same mismatch is
359 reported at least twice.
360 - Enable verbose reporting from modpost in order to help resolve
361 the section mismatches that are reported.
363 config SECTION_MISMATCH_WARN_ONLY
364 bool "Make section mismatch errors non-fatal"
367 If you say N here, the build process will fail if there are any
368 section mismatch, instead of just throwing warnings.
373 # Select this config option from the architecture Kconfig, if it
374 # is preferred to always offer frame pointers as a config
375 # option on the architecture (regardless of KERNEL_DEBUG):
377 config ARCH_WANT_FRAME_POINTERS
382 bool "Compile the kernel with frame pointers"
383 depends on DEBUG_KERNEL && \
384 (CRIS || M68K || FRV || UML || \
385 SUPERH || BLACKFIN || MN10300 || METAG) || \
386 ARCH_WANT_FRAME_POINTERS
387 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
389 If you say Y here the resulting kernel image will be slightly
390 larger and slower, but it gives very useful debugging information
391 in case of kernel bugs. (precise oopses/stacktraces/warnings)
393 config STACK_VALIDATION
394 bool "Compile-time stack metadata validation"
395 depends on HAVE_STACK_VALIDATION
398 Add compile-time checks to validate stack metadata, including frame
399 pointers (if CONFIG_FRAME_POINTER is enabled). This helps ensure
400 that runtime stack traces are more reliable.
402 This is also a prerequisite for generation of ORC unwind data, which
403 is needed for CONFIG_UNWINDER_ORC.
405 For more information, see
406 tools/objtool/Documentation/stack-validation.txt.
408 config DEBUG_FORCE_WEAK_PER_CPU
409 bool "Force weak per-cpu definitions"
410 depends on DEBUG_KERNEL
412 s390 and alpha require percpu variables in modules to be
413 defined weak to work around addressing range issue which
414 puts the following two restrictions on percpu variable
417 1. percpu symbols must be unique whether static or not
418 2. percpu variables can't be defined inside a function
420 To ensure that generic code follows the above rules, this
421 option forces all percpu variables to be defined as weak.
423 endmenu # "Compiler options"
426 bool "Magic SysRq key"
429 If you say Y here, you will have some control over the system even
430 if the system crashes for example during kernel debugging (e.g., you
431 will be able to flush the buffer cache to disk, reboot the system
432 immediately or dump some status information). This is accomplished
433 by pressing various keys while holding SysRq (Alt+PrintScreen). It
434 also works on a serial console (on PC hardware at least), if you
435 send a BREAK and then within 5 seconds a command keypress. The
436 keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
437 Don't say Y unless you really know what this hack does.
439 config MAGIC_SYSRQ_DEFAULT_ENABLE
440 hex "Enable magic SysRq key functions by default"
441 depends on MAGIC_SYSRQ
444 Specifies which SysRq key functions are enabled by default.
445 This may be set to 1 or 0 to enable or disable them all, or
446 to a bitmask as described in Documentation/admin-guide/sysrq.rst.
448 config MAGIC_SYSRQ_SERIAL
449 bool "Enable magic SysRq key over serial"
450 depends on MAGIC_SYSRQ
453 Many embedded boards have a disconnected TTL level serial which can
454 generate some garbage that can lead to spurious false sysrq detects.
455 This option allows you to decide whether you want to enable the
459 bool "Kernel debugging"
461 Say Y here if you are developing drivers or trying to debug and
462 identify kernel problems.
464 menu "Memory Debugging"
466 source mm/Kconfig.debug
469 bool "Debug object operations"
470 depends on DEBUG_KERNEL
472 If you say Y here, additional code will be inserted into the
473 kernel to track the life time of various objects and validate
474 the operations on those objects.
476 config DEBUG_OBJECTS_SELFTEST
477 bool "Debug objects selftest"
478 depends on DEBUG_OBJECTS
480 This enables the selftest of the object debug code.
482 config DEBUG_OBJECTS_FREE
483 bool "Debug objects in freed memory"
484 depends on DEBUG_OBJECTS
486 This enables checks whether a k/v free operation frees an area
487 which contains an object which has not been deactivated
488 properly. This can make kmalloc/kfree-intensive workloads
491 config DEBUG_OBJECTS_TIMERS
492 bool "Debug timer objects"
493 depends on DEBUG_OBJECTS
495 If you say Y here, additional code will be inserted into the
496 timer routines to track the life time of timer objects and
497 validate the timer operations.
499 config DEBUG_OBJECTS_WORK
500 bool "Debug work objects"
501 depends on DEBUG_OBJECTS
503 If you say Y here, additional code will be inserted into the
504 work queue routines to track the life time of work objects and
505 validate the work operations.
507 config DEBUG_OBJECTS_RCU_HEAD
508 bool "Debug RCU callbacks objects"
509 depends on DEBUG_OBJECTS
511 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
513 config DEBUG_OBJECTS_PERCPU_COUNTER
514 bool "Debug percpu counter objects"
515 depends on DEBUG_OBJECTS
517 If you say Y here, additional code will be inserted into the
518 percpu counter routines to track the life time of percpu counter
519 objects and validate the percpu counter operations.
521 config DEBUG_OBJECTS_ENABLE_DEFAULT
522 int "debug_objects bootup default value (0-1)"
525 depends on DEBUG_OBJECTS
527 Debug objects boot parameter default value
530 bool "Debug slab memory allocations"
531 depends on DEBUG_KERNEL && SLAB
533 Say Y here to have the kernel do limited verification on memory
534 allocation as well as poisoning memory on free to catch use of freed
535 memory. This can make kmalloc/kfree-intensive workloads much slower.
537 config DEBUG_SLAB_LEAK
538 bool "Memory leak debugging"
539 depends on DEBUG_SLAB
542 bool "SLUB debugging on by default"
543 depends on SLUB && SLUB_DEBUG
546 Boot with debugging on by default. SLUB boots by default with
547 the runtime debug capabilities switched off. Enabling this is
548 equivalent to specifying the "slub_debug" parameter on boot.
549 There is no support for more fine grained debug control like
550 possible with slub_debug=xxx. SLUB debugging may be switched
551 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
556 bool "Enable SLUB performance statistics"
557 depends on SLUB && SYSFS
559 SLUB statistics are useful to debug SLUBs allocation behavior in
560 order find ways to optimize the allocator. This should never be
561 enabled for production use since keeping statistics slows down
562 the allocator by a few percentage points. The slabinfo command
563 supports the determination of the most active slabs to figure
564 out which slabs are relevant to a particular load.
565 Try running: slabinfo -DA
567 config HAVE_DEBUG_KMEMLEAK
570 config DEBUG_KMEMLEAK
571 bool "Kernel memory leak detector"
572 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
574 select STACKTRACE if STACKTRACE_SUPPORT
578 Say Y here if you want to enable the memory leak
579 detector. The memory allocation/freeing is traced in a way
580 similar to the Boehm's conservative garbage collector, the
581 difference being that the orphan objects are not freed but
582 only shown in /sys/kernel/debug/kmemleak. Enabling this
583 feature will introduce an overhead to memory
584 allocations. See Documentation/dev-tools/kmemleak.rst for more
587 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
588 of finding leaks due to the slab objects poisoning.
590 In order to access the kmemleak file, debugfs needs to be
591 mounted (usually at /sys/kernel/debug).
593 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
594 int "Maximum kmemleak early log entries"
595 depends on DEBUG_KMEMLEAK
599 Kmemleak must track all the memory allocations to avoid
600 reporting false positives. Since memory may be allocated or
601 freed before kmemleak is initialised, an early log buffer is
602 used to store these actions. If kmemleak reports "early log
603 buffer exceeded", please increase this value.
605 config DEBUG_KMEMLEAK_TEST
606 tristate "Simple test for the kernel memory leak detector"
607 depends on DEBUG_KMEMLEAK && m
609 This option enables a module that explicitly leaks memory.
613 config DEBUG_KMEMLEAK_DEFAULT_OFF
614 bool "Default kmemleak to off"
615 depends on DEBUG_KMEMLEAK
617 Say Y here to disable kmemleak by default. It can then be enabled
618 on the command line via kmemleak=on.
620 config DEBUG_STACK_USAGE
621 bool "Stack utilization instrumentation"
622 depends on DEBUG_KERNEL && !IA64
624 Enables the display of the minimum amount of free stack which each
625 task has ever had available in the sysrq-T and sysrq-P debug output.
627 This option will slow down process creation somewhat.
631 depends on DEBUG_KERNEL
633 Enable this to turn on extended checks in the virtual-memory system
634 that may impact performance.
638 config DEBUG_VM_VMACACHE
639 bool "Debug VMA caching"
642 Enable this to turn on VMA caching debug information. Doing so
643 can cause significant overhead, so only enable it in non-production
649 bool "Debug VM red-black trees"
652 Enable VM red-black tree debugging information and extra validations.
656 config DEBUG_VM_PGFLAGS
657 bool "Debug page-flags operations"
660 Enables extra validation on page flags operations.
664 config ARCH_HAS_DEBUG_VIRTUAL
668 bool "Debug VM translations"
669 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
671 Enable some costly sanity checks in virtual to page code. This can
672 catch mistakes with virt_to_page() and friends.
676 config DEBUG_NOMMU_REGIONS
677 bool "Debug the global anon/private NOMMU mapping region tree"
678 depends on DEBUG_KERNEL && !MMU
680 This option causes the global tree of anonymous and private mapping
681 regions to be regularly checked for invalid topology.
683 config DEBUG_MEMORY_INIT
684 bool "Debug memory initialisation" if EXPERT
687 Enable this for additional checks during memory initialisation.
688 The sanity checks verify aspects of the VM such as the memory model
689 and other information provided by the architecture. Verbose
690 information will be printed at KERN_DEBUG loglevel depending
691 on the mminit_loglevel= command-line option.
695 config MEMORY_NOTIFIER_ERROR_INJECT
696 tristate "Memory hotplug notifier error injection module"
697 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
699 This option provides the ability to inject artificial errors to
700 memory hotplug notifier chain callbacks. It is controlled through
701 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
703 If the notifier call chain should be failed with some events
704 notified, write the error code to "actions/<notifier event>/error".
706 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
708 # cd /sys/kernel/debug/notifier-error-inject/memory
709 # echo -12 > actions/MEM_GOING_OFFLINE/error
710 # echo offline > /sys/devices/system/memory/memoryXXX/state
711 bash: echo: write error: Cannot allocate memory
713 To compile this code as a module, choose M here: the module will
714 be called memory-notifier-error-inject.
718 config DEBUG_PER_CPU_MAPS
719 bool "Debug access to per_cpu maps"
720 depends on DEBUG_KERNEL
723 Say Y to verify that the per_cpu map being accessed has
724 been set up. This adds a fair amount of code to kernel memory
725 and decreases performance.
730 bool "Highmem debugging"
731 depends on DEBUG_KERNEL && HIGHMEM
733 This option enables additional error checking for high memory
734 systems. Disable for production systems.
736 config HAVE_DEBUG_STACKOVERFLOW
739 config DEBUG_STACKOVERFLOW
740 bool "Check for stack overflows"
741 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
743 Say Y here if you want to check for overflows of kernel, IRQ
744 and exception stacks (if your architecture uses them). This
745 option will show detailed messages if free stack space drops
746 below a certain limit.
748 These kinds of bugs usually occur when call-chains in the
749 kernel get too deep, especially when interrupts are
752 Use this in cases where you see apparently random memory
753 corruption, especially if it appears in 'struct thread_info'
755 If in doubt, say "N".
757 source "lib/Kconfig.kasan"
759 endmenu # "Memory Debugging"
764 KCOV does not have any arch-specific code, but currently it is enabled
765 only for x86_64. KCOV requires testing on other archs, and most likely
766 disabling of instrumentation for some early boot code.
769 bool "Code coverage for fuzzing"
770 depends on ARCH_HAS_KCOV
772 select GCC_PLUGINS if !COMPILE_TEST
773 select GCC_PLUGIN_SANCOV if !COMPILE_TEST
775 KCOV exposes kernel code coverage information in a form suitable
776 for coverage-guided fuzzing (randomized testing).
778 If RANDOMIZE_BASE is enabled, PC values will not be stable across
779 different machines and across reboots. If you need stable PC values,
780 disable RANDOMIZE_BASE.
782 For more details, see Documentation/dev-tools/kcov.rst.
784 config KCOV_INSTRUMENT_ALL
785 bool "Instrument all code by default"
789 If you are doing generic system call fuzzing (like e.g. syzkaller),
790 then you will want to instrument the whole kernel and you should
791 say y here. If you are doing more targeted fuzzing (like e.g.
792 filesystem fuzzing with AFL) then you will want to enable coverage
793 for more specific subsets of files, and should say n here.
796 bool "Debug shared IRQ handlers"
797 depends on DEBUG_KERNEL
799 Enable this to generate a spurious interrupt as soon as a shared
800 interrupt handler is registered, and just before one is deregistered.
801 Drivers ought to be able to handle interrupts coming in at those
802 points; some don't and need to be caught.
804 menu "Debug Lockups and Hangs"
806 config LOCKUP_DETECTOR
809 config SOFTLOCKUP_DETECTOR
810 bool "Detect Soft Lockups"
811 depends on DEBUG_KERNEL && !S390
812 select LOCKUP_DETECTOR
814 Say Y here to enable the kernel to act as a watchdog to detect
817 Softlockups are bugs that cause the kernel to loop in kernel
818 mode for more than 20 seconds, without giving other tasks a
819 chance to run. The current stack trace is displayed upon
820 detection and the system will stay locked up.
822 config HARDLOCKUP_DETECTOR_PERF
824 select SOFTLOCKUP_DETECTOR
827 # Enables a timestamp based low pass filter to compensate for perf based
828 # hard lockup detection which runs too fast due to turbo modes.
830 config HARDLOCKUP_CHECK_TIMESTAMP
834 # arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard
835 # lockup detector rather than the perf based detector.
837 config HARDLOCKUP_DETECTOR
838 bool "Detect Hard Lockups"
839 depends on DEBUG_KERNEL && !S390
840 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH
841 select LOCKUP_DETECTOR
842 select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF
843 select HARDLOCKUP_DETECTOR_ARCH if HAVE_HARDLOCKUP_DETECTOR_ARCH
845 Say Y here to enable the kernel to act as a watchdog to detect
848 Hardlockups are bugs that cause the CPU to loop in kernel mode
849 for more than 10 seconds, without letting other interrupts have a
850 chance to run. The current stack trace is displayed upon detection
851 and the system will stay locked up.
853 config HARDLOCKUP_DETECTOR_OTHER_CPU
855 depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
856 depends on !HARDLOCKUP_DETECTOR
858 config BOOTPARAM_HARDLOCKUP_PANIC
859 bool "Panic (Reboot) On Hard Lockups"
860 depends on HARDLOCKUP_DETECTOR || HARDLOCKUP_DETECTOR_OTHER_CPU
862 Say Y here to enable the kernel to panic on "hard lockups",
863 which are bugs that cause the kernel to loop in kernel
864 mode with interrupts disabled for more than 10 seconds (configurable
865 using the watchdog_thresh sysctl).
869 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
871 depends on HARDLOCKUP_DETECTOR || HARDLOCKUP_DETECTOR_OTHER_CPU
873 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
874 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
876 config BOOTPARAM_SOFTLOCKUP_PANIC
877 bool "Panic (Reboot) On Soft Lockups"
878 depends on SOFTLOCKUP_DETECTOR
880 Say Y here to enable the kernel to panic on "soft lockups",
881 which are bugs that cause the kernel to loop in kernel
882 mode for more than 20 seconds (configurable using the watchdog_thresh
883 sysctl), without giving other tasks a chance to run.
885 The panic can be used in combination with panic_timeout,
886 to cause the system to reboot automatically after a
887 lockup has been detected. This feature is useful for
888 high-availability systems that have uptime guarantees and
889 where a lockup must be resolved ASAP.
893 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
895 depends on SOFTLOCKUP_DETECTOR
897 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
898 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
900 config DETECT_HUNG_TASK
901 bool "Detect Hung Tasks"
902 depends on DEBUG_KERNEL
903 default SOFTLOCKUP_DETECTOR
905 Say Y here to enable the kernel to detect "hung tasks",
906 which are bugs that cause the task to be stuck in
907 uninterruptible "D" state indefinitely.
909 When a hung task is detected, the kernel will print the
910 current stack trace (which you should report), but the
911 task will stay in uninterruptible state. If lockdep is
912 enabled then all held locks will also be reported. This
913 feature has negligible overhead.
915 config DEFAULT_HUNG_TASK_TIMEOUT
916 int "Default timeout for hung task detection (in seconds)"
917 depends on DETECT_HUNG_TASK
920 This option controls the default timeout (in seconds) used
921 to determine when a task has become non-responsive and should
924 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
925 sysctl or by writing a value to
926 /proc/sys/kernel/hung_task_timeout_secs.
928 A timeout of 0 disables the check. The default is two minutes.
929 Keeping the default should be fine in most cases.
931 config BOOTPARAM_HUNG_TASK_PANIC
932 bool "Panic (Reboot) On Hung Tasks"
933 depends on DETECT_HUNG_TASK
935 Say Y here to enable the kernel to panic on "hung tasks",
936 which are bugs that cause the kernel to leave a task stuck
937 in uninterruptible "D" state.
939 The panic can be used in combination with panic_timeout,
940 to cause the system to reboot automatically after a
941 hung task has been detected. This feature is useful for
942 high-availability systems that have uptime guarantees and
943 where a hung tasks must be resolved ASAP.
947 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
949 depends on DETECT_HUNG_TASK
951 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
952 default 1 if BOOTPARAM_HUNG_TASK_PANIC
955 bool "Detect Workqueue Stalls"
956 depends on DEBUG_KERNEL
958 Say Y here to enable stall detection on workqueues. If a
959 worker pool doesn't make forward progress on a pending work
960 item for over a given amount of time, 30s by default, a
961 warning message is printed along with dump of workqueue
962 state. This can be configured through kernel parameter
963 "workqueue.watchdog_thresh" and its sysfs counterpart.
965 endmenu # "Debug lockups and hangs"
970 Say Y here to enable the kernel to panic when it oopses. This
971 has the same effect as setting oops=panic on the kernel command
974 This feature is useful to ensure that the kernel does not do
975 anything erroneous after an oops which could result in data
976 corruption or other issues.
980 config PANIC_ON_OOPS_VALUE
983 default 0 if !PANIC_ON_OOPS
984 default 1 if PANIC_ON_OOPS
990 Set the timeout value (in seconds) until a reboot occurs when the
991 the kernel panics. If n = 0, then we wait forever. A timeout
992 value n > 0 will wait n seconds before rebooting, while a timeout
993 value n < 0 will reboot immediately.
996 bool "Collect scheduler debugging info"
997 depends on DEBUG_KERNEL && PROC_FS
1000 If you say Y here, the /proc/sched_debug file will be provided
1001 that can help debug the scheduler. The runtime overhead of this
1009 bool "Collect scheduler statistics"
1010 depends on DEBUG_KERNEL && PROC_FS
1013 If you say Y here, additional code will be inserted into the
1014 scheduler and related routines to collect statistics about
1015 scheduler behavior and provide them in /proc/schedstat. These
1016 stats may be useful for both tuning and debugging the scheduler
1017 If you aren't debugging the scheduler or trying to tune a specific
1018 application, you can say N to avoid the very slight overhead
1021 config SCHED_STACK_END_CHECK
1022 bool "Detect stack corruption on calls to schedule()"
1023 depends on DEBUG_KERNEL
1026 This option checks for a stack overrun on calls to schedule().
1027 If the stack end location is found to be over written always panic as
1028 the content of the corrupted region can no longer be trusted.
1029 This is to ensure no erroneous behaviour occurs which could result in
1030 data corruption or a sporadic crash at a later stage once the region
1031 is examined. The runtime overhead introduced is minimal.
1033 config DEBUG_TIMEKEEPING
1034 bool "Enable extra timekeeping sanity checking"
1036 This option will enable additional timekeeping sanity checks
1037 which may be helpful when diagnosing issues where timekeeping
1038 problems are suspected.
1040 This may include checks in the timekeeping hotpaths, so this
1041 option may have a (very small) performance impact to some
1046 config DEBUG_PREEMPT
1047 bool "Debug preemptible kernel"
1048 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
1051 If you say Y here then the kernel will use a debug variant of the
1052 commonly used smp_processor_id() function and will print warnings
1053 if kernel code uses it in a preemption-unsafe way. Also, the kernel
1054 will detect preemption count underflows.
1056 menu "Lock Debugging (spinlocks, mutexes, etc...)"
1058 config DEBUG_RT_MUTEXES
1059 bool "RT Mutex debugging, deadlock detection"
1060 depends on DEBUG_KERNEL && RT_MUTEXES
1062 This allows rt mutex semantics violations and rt mutex related
1063 deadlocks (lockups) to be detected and reported automatically.
1065 config DEBUG_SPINLOCK
1066 bool "Spinlock and rw-lock debugging: basic checks"
1067 depends on DEBUG_KERNEL
1068 select UNINLINE_SPIN_UNLOCK
1070 Say Y here and build SMP to catch missing spinlock initialization
1071 and certain other kinds of spinlock errors commonly made. This is
1072 best used in conjunction with the NMI watchdog so that spinlock
1073 deadlocks are also debuggable.
1075 config DEBUG_MUTEXES
1076 bool "Mutex debugging: basic checks"
1077 depends on DEBUG_KERNEL
1079 This feature allows mutex semantics violations to be detected and
1082 config DEBUG_WW_MUTEX_SLOWPATH
1083 bool "Wait/wound mutex debugging: Slowpath testing"
1084 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1085 select DEBUG_LOCK_ALLOC
1086 select DEBUG_SPINLOCK
1087 select DEBUG_MUTEXES
1089 This feature enables slowpath testing for w/w mutex users by
1090 injecting additional -EDEADLK wound/backoff cases. Together with
1091 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1092 will test all possible w/w mutex interface abuse with the
1093 exception of simply not acquiring all the required locks.
1094 Note that this feature can introduce significant overhead, so
1095 it really should not be enabled in a production or distro kernel,
1096 even a debug kernel. If you are a driver writer, enable it. If
1097 you are a distro, do not.
1099 config DEBUG_LOCK_ALLOC
1100 bool "Lock debugging: detect incorrect freeing of live locks"
1101 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1102 select DEBUG_SPINLOCK
1103 select DEBUG_MUTEXES
1104 select DEBUG_RT_MUTEXES if RT_MUTEXES
1107 This feature will check whether any held lock (spinlock, rwlock,
1108 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1109 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1110 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1111 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1112 held during task exit.
1114 config PROVE_LOCKING
1115 bool "Lock debugging: prove locking correctness"
1116 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1118 select DEBUG_SPINLOCK
1119 select DEBUG_MUTEXES
1120 select DEBUG_RT_MUTEXES if RT_MUTEXES
1121 select DEBUG_LOCK_ALLOC
1122 select LOCKDEP_CROSSRELEASE if BROKEN
1123 select LOCKDEP_COMPLETIONS if BROKEN
1124 select TRACE_IRQFLAGS
1127 This feature enables the kernel to prove that all locking
1128 that occurs in the kernel runtime is mathematically
1129 correct: that under no circumstance could an arbitrary (and
1130 not yet triggered) combination of observed locking
1131 sequences (on an arbitrary number of CPUs, running an
1132 arbitrary number of tasks and interrupt contexts) cause a
1135 In short, this feature enables the kernel to report locking
1136 related deadlocks before they actually occur.
1138 The proof does not depend on how hard and complex a
1139 deadlock scenario would be to trigger: how many
1140 participant CPUs, tasks and irq-contexts would be needed
1141 for it to trigger. The proof also does not depend on
1142 timing: if a race and a resulting deadlock is possible
1143 theoretically (no matter how unlikely the race scenario
1144 is), it will be proven so and will immediately be
1145 reported by the kernel (once the event is observed that
1146 makes the deadlock theoretically possible).
1148 If a deadlock is impossible (i.e. the locking rules, as
1149 observed by the kernel, are mathematically correct), the
1150 kernel reports nothing.
1152 NOTE: this feature can also be enabled for rwlocks, mutexes
1153 and rwsems - in which case all dependencies between these
1154 different locking variants are observed and mapped too, and
1155 the proof of observed correctness is also maintained for an
1156 arbitrary combination of these separate locking variants.
1158 For more details, see Documentation/locking/lockdep-design.txt.
1162 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1164 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC && !SCORE && !X86
1168 config LOCKDEP_SMALL
1172 bool "Lock usage statistics"
1173 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1175 select DEBUG_SPINLOCK
1176 select DEBUG_MUTEXES
1177 select DEBUG_RT_MUTEXES if RT_MUTEXES
1178 select DEBUG_LOCK_ALLOC
1181 This feature enables tracking lock contention points
1183 For more details, see Documentation/locking/lockstat.txt
1185 This also enables lock events required by "perf lock",
1187 If you want to use "perf lock", you also need to turn on
1188 CONFIG_EVENT_TRACING.
1190 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1191 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1193 config LOCKDEP_CROSSRELEASE
1196 This makes lockdep work for crosslock which is a lock allowed to
1197 be released in a different context from the acquisition context.
1198 Normally a lock must be released in the context acquiring the lock.
1199 However, relexing this constraint helps synchronization primitives
1200 such as page locks or completions can use the lock correctness
1203 config LOCKDEP_COMPLETIONS
1206 A deadlock caused by wait_for_completion() and complete() can be
1207 detected by lockdep using crossrelease feature.
1209 config DEBUG_LOCKDEP
1210 bool "Lock dependency engine debugging"
1211 depends on DEBUG_KERNEL && LOCKDEP
1213 If you say Y here, the lock dependency engine will do
1214 additional runtime checks to debug itself, at the price
1215 of more runtime overhead.
1217 config DEBUG_ATOMIC_SLEEP
1218 bool "Sleep inside atomic section checking"
1219 select PREEMPT_COUNT
1220 depends on DEBUG_KERNEL
1222 If you say Y here, various routines which may sleep will become very
1223 noisy if they are called inside atomic sections: when a spinlock is
1224 held, inside an rcu read side critical section, inside preempt disabled
1225 sections, inside an interrupt, etc...
1227 config DEBUG_LOCKING_API_SELFTESTS
1228 bool "Locking API boot-time self-tests"
1229 depends on DEBUG_KERNEL
1231 Say Y here if you want the kernel to run a short self-test during
1232 bootup. The self-test checks whether common types of locking bugs
1233 are detected by debugging mechanisms or not. (if you disable
1234 lock debugging then those bugs wont be detected of course.)
1235 The following locking APIs are covered: spinlocks, rwlocks,
1238 config LOCK_TORTURE_TEST
1239 tristate "torture tests for locking"
1240 depends on DEBUG_KERNEL
1244 This option provides a kernel module that runs torture tests
1245 on kernel locking primitives. The kernel module may be built
1246 after the fact on the running kernel to be tested, if desired.
1248 Say Y here if you want kernel locking-primitive torture tests
1249 to be built into the kernel.
1250 Say M if you want these torture tests to build as a module.
1251 Say N if you are unsure.
1253 config WW_MUTEX_SELFTEST
1254 tristate "Wait/wound mutex selftests"
1256 This option provides a kernel module that runs tests on the
1257 on the struct ww_mutex locking API.
1259 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1260 with this test harness.
1262 Say M if you want these self tests to build as a module.
1263 Say N if you are unsure.
1265 endmenu # lock debugging
1267 config TRACE_IRQFLAGS
1270 Enables hooks to interrupt enabling and disabling for
1271 either tracing or lock debugging.
1274 bool "Stack backtrace support"
1275 depends on STACKTRACE_SUPPORT
1277 This option causes the kernel to create a /proc/pid/stack for
1278 every process, showing its current stack trace.
1279 It is also used by various kernel debugging features that require
1280 stack trace generation.
1282 config WARN_ALL_UNSEEDED_RANDOM
1283 bool "Warn for all uses of unseeded randomness"
1286 Some parts of the kernel contain bugs relating to their use of
1287 cryptographically secure random numbers before it's actually possible
1288 to generate those numbers securely. This setting ensures that these
1289 flaws don't go unnoticed, by enabling a message, should this ever
1290 occur. This will allow people with obscure setups to know when things
1291 are going wrong, so that they might contact developers about fixing
1294 Unfortunately, on some models of some architectures getting
1295 a fully seeded CRNG is extremely difficult, and so this can
1296 result in dmesg getting spammed for a surprisingly long
1297 time. This is really bad from a security perspective, and
1298 so architecture maintainers really need to do what they can
1299 to get the CRNG seeded sooner after the system is booted.
1300 However, since users can not do anything actionble to
1301 address this, by default the kernel will issue only a single
1302 warning for the first use of unseeded randomness.
1304 Say Y here if you want to receive warnings for all uses of
1305 unseeded randomness. This will be of use primarily for
1306 those developers interersted in improving the security of
1307 Linux kernels running on their architecture (or
1310 config DEBUG_KOBJECT
1311 bool "kobject debugging"
1312 depends on DEBUG_KERNEL
1314 If you say Y here, some extra kobject debugging messages will be sent
1317 config DEBUG_KOBJECT_RELEASE
1318 bool "kobject release debugging"
1319 depends on DEBUG_OBJECTS_TIMERS
1321 kobjects are reference counted objects. This means that their
1322 last reference count put is not predictable, and the kobject can
1323 live on past the point at which a driver decides to drop it's
1324 initial reference to the kobject gained on allocation. An
1325 example of this would be a struct device which has just been
1328 However, some buggy drivers assume that after such an operation,
1329 the memory backing the kobject can be immediately freed. This
1330 goes completely against the principles of a refcounted object.
1332 If you say Y here, the kernel will delay the release of kobjects
1333 on the last reference count to improve the visibility of this
1334 kind of kobject release bug.
1336 config HAVE_DEBUG_BUGVERBOSE
1339 config DEBUG_BUGVERBOSE
1340 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
1341 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
1344 Say Y here to make BUG() panics output the file name and line number
1345 of the BUG call as well as the EIP and oops trace. This aids
1346 debugging but costs about 70-100K of memory.
1349 bool "Debug linked list manipulation"
1350 depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION
1352 Enable this to turn on extended checks in the linked-list
1357 config DEBUG_PI_LIST
1358 bool "Debug priority linked list manipulation"
1359 depends on DEBUG_KERNEL
1361 Enable this to turn on extended checks in the priority-ordered
1362 linked-list (plist) walking routines. This checks the entire
1363 list multiple times during each manipulation.
1368 bool "Debug SG table operations"
1369 depends on DEBUG_KERNEL
1371 Enable this to turn on checks on scatter-gather tables. This can
1372 help find problems with drivers that do not properly initialize
1377 config DEBUG_NOTIFIERS
1378 bool "Debug notifier call chains"
1379 depends on DEBUG_KERNEL
1381 Enable this to turn on sanity checking for notifier call chains.
1382 This is most useful for kernel developers to make sure that
1383 modules properly unregister themselves from notifier chains.
1384 This is a relatively cheap check but if you care about maximum
1387 config DEBUG_CREDENTIALS
1388 bool "Debug credential management"
1389 depends on DEBUG_KERNEL
1391 Enable this to turn on some debug checking for credential
1392 management. The additional code keeps track of the number of
1393 pointers from task_structs to any given cred struct, and checks to
1394 see that this number never exceeds the usage count of the cred
1397 Furthermore, if SELinux is enabled, this also checks that the
1398 security pointer in the cred struct is never seen to be invalid.
1402 source "kernel/rcu/Kconfig.debug"
1404 config DEBUG_WQ_FORCE_RR_CPU
1405 bool "Force round-robin CPU selection for unbound work items"
1406 depends on DEBUG_KERNEL
1409 Workqueue used to implicitly guarantee that work items queued
1410 without explicit CPU specified are put on the local CPU. This
1411 guarantee is no longer true and while local CPU is still
1412 preferred work items may be put on foreign CPUs. Kernel
1413 parameter "workqueue.debug_force_rr_cpu" is added to force
1414 round-robin CPU selection to flush out usages which depend on the
1415 now broken guarantee. This config option enables the debug
1416 feature by default. When enabled, memory and cache locality will
1419 config DEBUG_BLOCK_EXT_DEVT
1420 bool "Force extended block device numbers and spread them"
1421 depends on DEBUG_KERNEL
1425 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1426 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1427 YOU ARE DOING. Distros, please enable this and fix whatever
1430 Conventionally, block device numbers are allocated from
1431 predetermined contiguous area. However, extended block area
1432 may introduce non-contiguous block device numbers. This
1433 option forces most block device numbers to be allocated from
1434 the extended space and spreads them to discover kernel or
1435 userland code paths which assume predetermined contiguous
1436 device number allocation.
1438 Note that turning on this debug option shuffles all the
1439 device numbers for all IDE and SCSI devices including libata
1440 ones, so root partition specified using device number
1441 directly (via rdev or root=MAJ:MIN) won't work anymore.
1442 Textual device names (root=/dev/sdXn) will continue to work.
1444 Say N if you are unsure.
1446 config CPU_HOTPLUG_STATE_CONTROL
1447 bool "Enable CPU hotplug state control"
1448 depends on DEBUG_KERNEL
1449 depends on HOTPLUG_CPU
1452 Allows to write steps between "offline" and "online" to the CPUs
1453 sysfs target file so states can be stepped granular. This is a debug
1454 option for now as the hotplug machinery cannot be stopped and
1455 restarted at arbitrary points yet.
1457 Say N if your are unsure.
1459 config NOTIFIER_ERROR_INJECTION
1460 tristate "Notifier error injection"
1461 depends on DEBUG_KERNEL
1464 This option provides the ability to inject artificial errors to
1465 specified notifier chain callbacks. It is useful to test the error
1466 handling of notifier call chain failures.
1470 config PM_NOTIFIER_ERROR_INJECT
1471 tristate "PM notifier error injection module"
1472 depends on PM && NOTIFIER_ERROR_INJECTION
1473 default m if PM_DEBUG
1475 This option provides the ability to inject artificial errors to
1476 PM notifier chain callbacks. It is controlled through debugfs
1477 interface /sys/kernel/debug/notifier-error-inject/pm
1479 If the notifier call chain should be failed with some events
1480 notified, write the error code to "actions/<notifier event>/error".
1482 Example: Inject PM suspend error (-12 = -ENOMEM)
1484 # cd /sys/kernel/debug/notifier-error-inject/pm/
1485 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1486 # echo mem > /sys/power/state
1487 bash: echo: write error: Cannot allocate memory
1489 To compile this code as a module, choose M here: the module will
1490 be called pm-notifier-error-inject.
1494 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1495 tristate "OF reconfig notifier error injection module"
1496 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1498 This option provides the ability to inject artificial errors to
1499 OF reconfig notifier chain callbacks. It is controlled
1500 through debugfs interface under
1501 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1503 If the notifier call chain should be failed with some events
1504 notified, write the error code to "actions/<notifier event>/error".
1506 To compile this code as a module, choose M here: the module will
1507 be called of-reconfig-notifier-error-inject.
1511 config NETDEV_NOTIFIER_ERROR_INJECT
1512 tristate "Netdev notifier error injection module"
1513 depends on NET && NOTIFIER_ERROR_INJECTION
1515 This option provides the ability to inject artificial errors to
1516 netdevice notifier chain callbacks. It is controlled through debugfs
1517 interface /sys/kernel/debug/notifier-error-inject/netdev
1519 If the notifier call chain should be failed with some events
1520 notified, write the error code to "actions/<notifier event>/error".
1522 Example: Inject netdevice mtu change error (-22 = -EINVAL)
1524 # cd /sys/kernel/debug/notifier-error-inject/netdev
1525 # echo -22 > actions/NETDEV_CHANGEMTU/error
1526 # ip link set eth0 mtu 1024
1527 RTNETLINK answers: Invalid argument
1529 To compile this code as a module, choose M here: the module will
1530 be called netdev-notifier-error-inject.
1534 config FAULT_INJECTION
1535 bool "Fault-injection framework"
1536 depends on DEBUG_KERNEL
1538 Provide fault-injection framework.
1539 For more details, see Documentation/fault-injection/.
1542 bool "Fault-injection capability for kmalloc"
1543 depends on FAULT_INJECTION
1544 depends on SLAB || SLUB
1546 Provide fault-injection capability for kmalloc.
1548 config FAIL_PAGE_ALLOC
1549 bool "Fault-injection capabilitiy for alloc_pages()"
1550 depends on FAULT_INJECTION
1552 Provide fault-injection capability for alloc_pages().
1554 config FAIL_MAKE_REQUEST
1555 bool "Fault-injection capability for disk IO"
1556 depends on FAULT_INJECTION && BLOCK
1558 Provide fault-injection capability for disk IO.
1560 config FAIL_IO_TIMEOUT
1561 bool "Fault-injection capability for faking disk interrupts"
1562 depends on FAULT_INJECTION && BLOCK
1564 Provide fault-injection capability on end IO handling. This
1565 will make the block layer "forget" an interrupt as configured,
1566 thus exercising the error handling.
1568 Only works with drivers that use the generic timeout handling,
1569 for others it wont do anything.
1571 config FAIL_MMC_REQUEST
1572 bool "Fault-injection capability for MMC IO"
1573 depends on FAULT_INJECTION_DEBUG_FS && MMC
1575 Provide fault-injection capability for MMC IO.
1576 This will make the mmc core return data errors. This is
1577 useful to test the error handling in the mmc block device
1578 and to test how the mmc host driver handles retries from
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 FAULT_INJECTION_STACKTRACE_FILTER
1595 bool "stacktrace filter for fault-injection capabilities"
1596 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1599 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC && !SCORE && !X86
1601 Provide stacktrace filter for fault-injection capabilities
1604 bool "Latency measuring infrastructure"
1605 depends on DEBUG_KERNEL
1606 depends on STACKTRACE_SUPPORT
1608 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC && !X86
1615 Enable this option if you want to use the LatencyTOP tool
1616 to find out which userspace is blocking on what kernel operations.
1618 source kernel/trace/Kconfig
1620 config PROVIDE_OHCI1394_DMA_INIT
1621 bool "Remote debugging over FireWire early on boot"
1622 depends on PCI && X86
1624 If you want to debug problems which hang or crash the kernel early
1625 on boot and the crashing machine has a FireWire port, you can use
1626 this feature to remotely access the memory of the crashed machine
1627 over FireWire. This employs remote DMA as part of the OHCI1394
1628 specification which is now the standard for FireWire controllers.
1630 With remote DMA, you can monitor the printk buffer remotely using
1631 firescope and access all memory below 4GB using fireproxy from gdb.
1632 Even controlling a kernel debugger is possible using remote DMA.
1636 If ohci1394_dma=early is used as boot parameter, it will initialize
1637 all OHCI1394 controllers which are found in the PCI config space.
1639 As all changes to the FireWire bus such as enabling and disabling
1640 devices cause a bus reset and thereby disable remote DMA for all
1641 devices, be sure to have the cable plugged and FireWire enabled on
1642 the debugging host before booting the debug target for debugging.
1644 This code (~1k) is freed after boot. By then, the firewire stack
1645 in charge of the OHCI-1394 controllers should be used instead.
1647 See Documentation/debugging-via-ohci1394.txt for more information.
1649 config DMA_API_DEBUG
1650 bool "Enable debugging of DMA-API usage"
1651 depends on HAVE_DMA_API_DEBUG
1653 Enable this option to debug the use of the DMA API by device drivers.
1654 With this option you will be able to detect common bugs in device
1655 drivers like double-freeing of DMA mappings or freeing mappings that
1656 were never allocated.
1658 This also attempts to catch cases where a page owned by DMA is
1659 accessed by the cpu in a way that could cause data corruption. For
1660 example, this enables cow_user_page() to check that the source page is
1663 This option causes a performance degradation. Use only if you want to
1664 debug device drivers and dma interactions.
1668 menu "Runtime Testing"
1671 tristate "Linux Kernel Dump Test Tool Module"
1676 This module enables testing of the different dumping mechanisms by
1677 inducing system failures at predefined crash points.
1678 If you don't need it: say N
1679 Choose M here to compile this code as a module. The module will be
1682 Documentation on how to use the module can be found in
1683 Documentation/fault-injection/provoke-crashes.txt
1685 config TEST_LIST_SORT
1686 tristate "Linked list sorting test"
1687 depends on DEBUG_KERNEL || m
1689 Enable this to turn on 'list_sort()' function test. This test is
1690 executed only once during system boot (so affects only boot time),
1691 or at module load time.
1696 tristate "Array-based sort test"
1697 depends on DEBUG_KERNEL || m
1699 This option enables the self-test function of 'sort()' at boot,
1700 or at module load time.
1704 config KPROBES_SANITY_TEST
1705 bool "Kprobes sanity tests"
1706 depends on DEBUG_KERNEL
1710 This option provides for testing basic kprobes functionality on
1711 boot. A sample kprobe, jprobe and kretprobe are inserted and
1712 verified for functionality.
1714 Say N if you are unsure.
1716 config BACKTRACE_SELF_TEST
1717 tristate "Self test for the backtrace code"
1718 depends on DEBUG_KERNEL
1721 This option provides a kernel module that can be used to test
1722 the kernel stack backtrace code. This option is not useful
1723 for distributions or general kernels, but only for kernel
1724 developers working on architecture code.
1726 Note that if you want to also test saved backtraces, you will
1727 have to enable STACKTRACE as well.
1729 Say N if you are unsure.
1732 tristate "Red-Black tree test"
1733 depends on DEBUG_KERNEL
1735 A benchmark measuring the performance of the rbtree library.
1736 Also includes rbtree invariant checks.
1738 config INTERVAL_TREE_TEST
1739 tristate "Interval tree test"
1740 depends on DEBUG_KERNEL
1741 select INTERVAL_TREE
1743 A benchmark measuring the performance of the interval tree library
1746 tristate "Per cpu operations test"
1747 depends on m && DEBUG_KERNEL
1749 Enable this option to build test module which validates per-cpu
1754 config ATOMIC64_SELFTEST
1755 tristate "Perform an atomic64_t self-test"
1757 Enable this option to test the atomic64_t functions at boot or
1758 at module load time.
1762 config ASYNC_RAID6_TEST
1763 tristate "Self test for hardware accelerated raid6 recovery"
1764 depends on ASYNC_RAID6_RECOV
1767 This is a one-shot self test that permutes through the
1768 recovery of all the possible two disk failure scenarios for a
1769 N-disk array. Recovery is performed with the asynchronous
1770 raid6 recovery routines, and will optionally use an offload
1771 engine if one is available.
1776 tristate "Test functions located in the hexdump module at runtime"
1778 config TEST_STRING_HELPERS
1779 tristate "Test functions located in the string_helpers module at runtime"
1782 tristate "Test kstrto*() family of functions at runtime"
1785 tristate "Test printf() family of functions at runtime"
1788 tristate "Test bitmap_*() family of functions at runtime"
1791 Enable this option to test the bitmap functions at boot.
1796 tristate "Test functions located in the uuid module at runtime"
1798 config TEST_RHASHTABLE
1799 tristate "Perform selftest on resizable hash table"
1802 Enable this option to test the rhashtable functions at boot.
1807 tristate "Perform selftest on hash functions"
1810 Enable this option to test the kernel's integer (<linux/hash.h>),
1811 string (<linux/stringhash.h>), and siphash (<linux/siphash.h>)
1812 hash functions on boot (or module load).
1814 This is intended to help people writing architecture-specific
1815 optimized versions. If unsure, say N.
1818 tristate "Perform selftest on priority array manager"
1822 Enable this option to test priority array manager on boot
1828 tristate "Test module loading with 'hello world' module"
1832 This builds the "test_module" module that emits "Hello, world"
1833 on printk when loaded. It is designed to be used for basic
1834 evaluation of the module loading subsystem (for example when
1835 validating module verification). It lacks any extra dependencies,
1836 and will not normally be loaded by the system unless explicitly
1841 config TEST_USER_COPY
1842 tristate "Test user/kernel boundary protections"
1846 This builds the "test_user_copy" module that runs sanity checks
1847 on the copy_to/from_user infrastructure, making sure basic
1848 user/kernel boundary testing is working. If it fails to load,
1849 a regression has been detected in the user/kernel memory boundary
1855 tristate "Test BPF filter functionality"
1859 This builds the "test_bpf" module that runs various test vectors
1860 against the BPF interpreter or BPF JIT compiler depending on the
1861 current setting. This is in particular useful for BPF JIT compiler
1862 development, but also to run regression tests against changes in
1863 the interpreter code. It also enables test stubs for eBPF maps and
1864 verifier used by user space verifier testsuite.
1868 config TEST_FIRMWARE
1869 tristate "Test firmware loading via userspace interface"
1871 depends on FW_LOADER
1873 This builds the "test_firmware" module that creates a userspace
1874 interface for testing firmware loading. This can be used to
1875 control the triggering of firmware loading without needing an
1876 actual firmware-using device. The contents can be rechecked by
1882 tristate "sysctl test driver"
1884 depends on PROC_SYSCTL
1886 This builds the "test_sysctl" module. This driver enables to test the
1887 proc sysctl interfaces available to drivers safely without affecting
1888 production knobs which might alter system functionality.
1893 tristate "udelay test driver"
1896 This builds the "udelay_test" module that helps to make sure
1897 that udelay() is working properly.
1901 config TEST_STATIC_KEYS
1902 tristate "Test static keys"
1906 Test the static key interfaces.
1911 tristate "kmod stress tester"
1914 depends on BLOCK && (64BIT || LBDAF) # for XFS, BTRFS
1915 depends on NETDEVICES && NET_CORE && INET # for TUN
1921 Test the kernel's module loading mechanism: kmod. kmod implements
1922 support to load modules using the Linux kernel's usermode helper.
1923 This test provides a series of tests against kmod.
1925 Although technically you can either build test_kmod as a module or
1926 into the kernel we disallow building it into the kernel since
1927 it stress tests request_module() and this will very likely cause
1928 some issues by taking over precious threads available from other
1929 module load requests, ultimately this could be fatal.
1933 tools/testing/selftests/kmod/kmod.sh --help
1937 config TEST_DEBUG_VIRTUAL
1938 tristate "Test CONFIG_DEBUG_VIRTUAL feature"
1939 depends on DEBUG_VIRTUAL
1941 Test the kernel's ability to detect incorrect calls to
1942 virt_to_phys() done against the non-linear part of the
1943 kernel's virtual address map.
1947 endmenu # runtime tests
1951 depends on HAVE_MEMBLOCK
1953 This option adds a kernel parameter 'memtest', which allows memtest
1955 memtest=0, mean disabled; -- default
1956 memtest=1, mean do 1 test pattern;
1958 memtest=17, mean do 17 test patterns.
1959 If you are unsure how to answer this question, answer N.
1961 config BUG_ON_DATA_CORRUPTION
1962 bool "Trigger a BUG when data corruption is detected"
1965 Select this option if the kernel should BUG when it encounters
1966 data corruption in kernel memory structures when they get checked
1971 config SOFTLOCKUP_WATCHDOG_TEST
1972 bool "To test softlockup watchdog"
1973 depends on LOCKUP_DETECTOR && DEBUG_FS
1976 This option provides a kernel debugfs item that can be used
1977 to test softlockup watchdog reset. This option is not useful
1978 for distributions or general kernels, but only for kernel
1979 developers working on architecture code for test purpose.
1981 Say N if you are unsure.
1983 source "samples/Kconfig"
1985 source "lib/Kconfig.kgdb"
1987 source "lib/Kconfig.ubsan"
1989 config ARCH_HAS_DEVMEM_IS_ALLOWED
1992 config STRICT_DEVMEM
1993 bool "Filter access to /dev/mem"
1994 depends on MMU && DEVMEM
1995 depends on ARCH_HAS_DEVMEM_IS_ALLOWED
1996 default y if TILE || PPC
1998 If this option is disabled, you allow userspace (root) access to all
1999 of memory, including kernel and userspace memory. Accidental
2000 access to this is obviously disastrous, but specific access can
2001 be used by people debugging the kernel. Note that with PAT support
2002 enabled, even in this case there are restrictions on /dev/mem
2003 use due to the cache aliasing requirements.
2005 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
2006 file only allows userspace access to PCI space and the BIOS code and
2007 data regions. This is sufficient for dosemu and X and all common
2012 config IO_STRICT_DEVMEM
2013 bool "Filter I/O access to /dev/mem"
2014 depends on STRICT_DEVMEM
2016 If this option is disabled, you allow userspace (root) access to all
2017 io-memory regardless of whether a driver is actively using that
2018 range. Accidental access to this is obviously disastrous, but
2019 specific access can be used by people debugging kernel drivers.
2021 If this option is switched on, the /dev/mem file only allows
2022 userspace access to *idle* io-memory ranges (see /proc/iomem) This
2023 may break traditional users of /dev/mem (dosemu, legacy X, etc...)
2024 if the driver using a given range cannot be disabled.
2028 menuconfig DEBUG_SNAPSHOT
2029 bool "Debug SnapShot Support"
2032 config DEBUG_SNAPSHOT_LINUX_BUILD
2033 bool "May be built in LINUX environment"
2034 depends on DEBUG_SNAPSHOT
2037 config DEBUG_SNAPSHOT_USER_MODE
2038 bool "Enable User Mode, Most of debug feature are disabled"
2039 depends on DEBUG_SNAPSHOT
2042 config DEBUG_SNAPSHOT_CALLSTACK
2043 int "shown callstack level"
2044 depends on DEBUG_SNAPSHOT
2048 config DEBUG_SNAPSHOT_IRQ_DISABLED
2049 bool "Enable debugging of interrupt disable event by kevent(EXPERIMENTAL)"
2050 depends on DEBUG_SNAPSHOT && !DEBUG_SNAPSHOT_MINIMIZED_MODE
2053 config DEBUG_SNAPSHOT_SPINLOCK
2054 bool "Enable debugging of spinlock event by kevent(EXPERIMENTAL)"
2055 depends on DEBUG_SNAPSHOT && DEBUG_SPINLOCK && !DEBUG_SNAPSHOT_MINIMIZED_MODE
2058 config DEBUG_SNAPSHOT_CLK
2059 bool "Enable debugging of clock event by kevent(EXPERIMENTAL)"
2060 depends on DEBUG_SNAPSHOT && !DEBUG_SNAPSHOT_MINIMIZED_MODE
2063 config DEBUG_SNAPSHOT_PMU
2064 bool "Enable debugging of pmu event by kevent(EXPERIMENTAL)"
2065 depends on DEBUG_SNAPSHOT && !DEBUG_SNAPSHOT_MINIMIZED_MODE
2068 config DEBUG_SNAPSHOT_FREQ
2069 bool "Enable debugging of frequence event by kevent(EXPERIMENTAL)"
2070 depends on DEBUG_SNAPSHOT && PM_DEVFREQ
2073 config DEBUG_SNAPSHOT_DM
2074 bool "Enable debugging of dvfs manager event by kevent(EXPERIMENTAL)"
2075 depends on DEBUG_SNAPSHOT && EXYNOS_DVFS_MANAGER && !DEBUG_SNAPSHOT_MINIMIZED_MODE
2078 config DEBUG_SNAPSHOT_HRTIMER
2079 bool "Enable debugging of hrtimer by kevent"
2080 depends on DEBUG_SNAPSHOT && !DEBUG_SNAPSHOT_MINIMIZED_MODE
2083 config DEBUG_SNAPSHOT_REG
2084 bool "Enable debugging of accessing register by kevent"
2085 depends on DEBUG_SNAPSHOT && !DEBUG_SNAPSHOT_MINIMIZED_MODE
2088 config DEBUG_SNAPSHOT_REGULATOR
2089 bool "Enable debugging of regulator and pmic driver"
2090 depends on DEBUG_SNAPSHOT && !DEBUG_SNAPSHOT_MINIMIZED_MODE
2093 config DEBUG_SNAPSHOT_ACPM
2094 bool "Enable debugging of acpm framework"
2095 depends on DEBUG_SNAPSHOT && !DEBUG_SNAPSHOT_MINIMIZED_MODE
2098 config DEBUG_SNAPSHOT_THERMAL
2099 bool "Enable debugging of thermal driver"
2100 depends on DEBUG_SNAPSHOT && !DEBUG_SNAPSHOT_MINIMIZED_MODE && EXYNOS_THERMAL
2103 config DEBUG_SNAPSHOT_I2C
2104 bool "Enable debugging of i2c driver"
2105 depends on DEBUG_SNAPSHOT && !DEBUG_SNAPSHOT_MINIMIZED_MODE
2108 config DEBUG_SNAPSHOT_SPI
2109 bool "Enable debugging of spi driver"
2110 depends on DEBUG_SNAPSHOT && !DEBUG_SNAPSHOT_MINIMIZED_MODE
2113 config DEBUG_SNAPSHOT_BINDER
2114 bool "Enable debugging of binder driver"
2115 depends on DEBUG_SNAPSHOT && !DEBUG_SNAPSHOT_MINIMIZED_MODE
2118 config DEBUG_SNAPSHOT_PANIC_REBOOT
2119 bool "Enable forced reboot after panic for ramdump"
2120 depends on DEBUG_SNAPSHOT
2123 config DEBUG_SNAPSHOT_WATCHDOG_RESET
2124 bool "Support watchdog reset when hardlockup detect"
2125 depends on DEBUG_SNAPSHOT && DEBUG_SNAPSHOT_PANIC_REBOOT
2128 config DEBUG_SNAPSHOT_CRASH_KEY
2129 bool "Support Crash Key to artificial panic for debugging"
2130 depends on DEBUG_SNAPSHOT && KEYBOARD_GPIO
2133 config DEBUG_SNAPSHOT_MINIMIZED_MODE
2134 bool "Support minimized feature configuration"
2135 depends on DEBUG_SNAPSHOT_USER_MODE
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