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
33 config MESSAGE_LOGLEVEL_DEFAULT
34 int "Default message log level (1-7)"
38 Default log level for printk statements with no specified priority.
40 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
41 that are auditing their logs closely may want to set it to a lower
44 Note: This does not affect what message level gets printed on the console
45 by default. To change that, use loglevel=<x> in the kernel bootargs,
46 or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value.
48 config BOOT_PRINTK_DELAY
49 bool "Delay each boot printk message by N milliseconds"
50 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
52 This build option allows you to read kernel boot messages
53 by inserting a short delay after each one. The delay is
54 specified in milliseconds on the kernel command line,
57 It is likely that you would also need to use "lpj=M" to preset
58 the "loops per jiffie" value.
59 See a previous boot log for the "lpj" value to use for your
60 system, and then set "lpj=M" before setting "boot_delay=N".
61 NOTE: Using this option may adversely affect SMP systems.
62 I.e., processors other than the first one may not boot up.
63 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
64 what it believes to be lockup conditions.
67 bool "Enable dynamic printk() support"
73 Compiles debug level messages into the kernel, which would not
74 otherwise be available at runtime. These messages can then be
75 enabled/disabled based on various levels of scope - per source file,
76 function, module, format string, and line number. This mechanism
77 implicitly compiles in all pr_debug() and dev_dbg() calls, which
78 enlarges the kernel text size by about 2%.
80 If a source file is compiled with DEBUG flag set, any
81 pr_debug() calls in it are enabled by default, but can be
82 disabled at runtime as below. Note that DEBUG flag is
83 turned on by many CONFIG_*DEBUG* options.
87 Dynamic debugging is controlled via the 'dynamic_debug/control' file,
88 which is contained in the 'debugfs' filesystem. Thus, the debugfs
89 filesystem must first be mounted before making use of this feature.
90 We refer the control file as: <debugfs>/dynamic_debug/control. This
91 file contains a list of the debug statements that can be enabled. The
92 format for each line of the file is:
94 filename:lineno [module]function flags format
96 filename : source file of the debug statement
97 lineno : line number of the debug statement
98 module : module that contains the debug statement
99 function : function that contains the debug statement
100 flags : '=p' means the line is turned 'on' for printing
101 format : the format used for the debug statement
105 nullarbor:~ # cat <debugfs>/dynamic_debug/control
106 # filename:lineno [module]function flags format
107 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
108 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
109 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
113 // enable the message at line 1603 of file svcsock.c
114 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
115 <debugfs>/dynamic_debug/control
117 // enable all the messages in file svcsock.c
118 nullarbor:~ # echo -n 'file svcsock.c +p' >
119 <debugfs>/dynamic_debug/control
121 // enable all the messages in the NFS server module
122 nullarbor:~ # echo -n 'module nfsd +p' >
123 <debugfs>/dynamic_debug/control
125 // enable all 12 messages in the function svc_process()
126 nullarbor:~ # echo -n 'func svc_process +p' >
127 <debugfs>/dynamic_debug/control
129 // disable all 12 messages in the function svc_process()
130 nullarbor:~ # echo -n 'func svc_process -p' >
131 <debugfs>/dynamic_debug/control
133 See Documentation/admin-guide/dynamic-debug-howto.rst for additional
136 endmenu # "printk and dmesg options"
138 menu "Compile-time checks and compiler options"
141 bool "Compile the kernel with debug info"
142 depends on DEBUG_KERNEL && !COMPILE_TEST
144 If you say Y here the resulting kernel image will include
145 debugging info resulting in a larger kernel image.
146 This adds debug symbols to the kernel and modules (gcc -g), and
147 is needed if you intend to use kernel crashdump or binary object
148 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
149 Say Y here only if you plan to debug the kernel.
153 config DEBUG_INFO_REDUCED
154 bool "Reduce debugging information"
155 depends on DEBUG_INFO
157 If you say Y here gcc is instructed to generate less debugging
158 information for structure types. This means that tools that
159 need full debugging information (like kgdb or systemtap) won't
160 be happy. But if you merely need debugging information to
161 resolve line numbers there is no loss. Advantage is that
162 build directory object sizes shrink dramatically over a full
163 DEBUG_INFO build and compile times are reduced too.
164 Only works with newer gcc versions.
166 config DEBUG_INFO_SPLIT
167 bool "Produce split debuginfo in .dwo files"
168 depends on DEBUG_INFO && !FRV
170 Generate debug info into separate .dwo files. This significantly
171 reduces the build directory size for builds with DEBUG_INFO,
172 because it stores the information only once on disk in .dwo
173 files instead of multiple times in object files and executables.
174 In addition the debug information is also compressed.
176 Requires recent gcc (4.7+) and recent gdb/binutils.
177 Any tool that packages or reads debug information would need
178 to know about the .dwo files and include them.
179 Incompatible with older versions of ccache.
181 config DEBUG_INFO_DWARF4
182 bool "Generate dwarf4 debuginfo"
183 depends on DEBUG_INFO
185 Generate dwarf4 debug info. This requires recent versions
186 of gcc and gdb. It makes the debug information larger.
187 But it significantly improves the success of resolving
188 variables in gdb on optimized code.
191 bool "Provide GDB scripts for kernel debugging"
192 depends on DEBUG_INFO
194 This creates the required links to GDB helper scripts in the
195 build directory. If you load vmlinux into gdb, the helper
196 scripts will be automatically imported by gdb as well, and
197 additional functions are available to analyze a Linux kernel
198 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
201 config ENABLE_WARN_DEPRECATED
202 bool "Enable __deprecated logic"
205 Enable the __deprecated logic in the kernel build.
206 Disable this to suppress the "warning: 'foo' is deprecated
207 (declared at kernel/power/somefile.c:1234)" messages.
209 config ENABLE_MUST_CHECK
210 bool "Enable __must_check logic"
213 Enable the __must_check logic in the kernel build. Disable this to
214 suppress the "warning: ignoring return value of 'foo', declared with
215 attribute warn_unused_result" messages.
218 int "Warn for stack frames larger than (needs gcc 4.4)"
221 default 2048 if GCC_PLUGIN_LATENT_ENTROPY
222 default 1024 if !64BIT
223 default 2048 if 64BIT
225 Tell gcc to warn at build time for stack frames larger than this.
226 Setting this too low will cause a lot of warnings.
227 Setting it to 0 disables the warning.
230 config STRIP_ASM_SYMS
231 bool "Strip assembler-generated symbols during link"
234 Strip internal assembler-generated symbols during a link (symbols
235 that look like '.Lxxx') so they don't pollute the output of
236 get_wchan() and suchlike.
239 bool "Generate readable assembler code"
240 depends on DEBUG_KERNEL
242 Disable some compiler optimizations that tend to generate human unreadable
243 assembler output. This may make the kernel slightly slower, but it helps
244 to keep kernel developers who have to stare a lot at assembler listings
247 config UNUSED_SYMBOLS
248 bool "Enable unused/obsolete exported symbols"
251 Unused but exported symbols make the kernel needlessly bigger. For
252 that reason most of these unused exports will soon be removed. This
253 option is provided temporarily to provide a transition period in case
254 some external kernel module needs one of these symbols anyway. If you
255 encounter such a case in your module, consider if you are actually
256 using the right API. (rationale: since nobody in the kernel is using
257 this in a module, there is a pretty good chance it's actually the
258 wrong interface to use). If you really need the symbol, please send a
259 mail to the linux kernel mailing list mentioning the symbol and why
260 you really need it, and what the merge plan to the mainline kernel for
264 bool "Track page owner"
265 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
269 select PAGE_EXTENSION
271 This keeps track of what call chain is the owner of a page, may
272 help to find bare alloc_page(s) leaks. Even if you include this
273 feature on your build, it is disabled in default. You should pass
274 "page_owner=on" to boot parameter in order to enable it. Eats
275 a fair amount of memory if enabled. See tools/vm/page_owner_sort.c
276 for user-space helper.
281 bool "Debug Filesystem"
284 debugfs is a virtual file system that kernel developers use to put
285 debugging files into. Enable this option to be able to read and
286 write to these files.
288 For detailed documentation on the debugfs API, see
289 Documentation/filesystems/.
294 bool "Run 'make headers_check' when building vmlinux"
297 This option will extract the user-visible kernel headers whenever
298 building the kernel, and will run basic sanity checks on them to
299 ensure that exported files do not attempt to include files which
300 were not exported, etc.
302 If you're making modifications to header files which are
303 relevant for userspace, say 'Y', and check the headers
304 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
305 your build tree), to make sure they're suitable.
307 config DEBUG_SECTION_MISMATCH
308 bool "Enable full Section mismatch analysis"
310 The section mismatch analysis checks if there are illegal
311 references from one section to another section.
312 During linktime or runtime, some sections are dropped;
313 any use of code/data previously in these sections would
314 most likely result in an oops.
315 In the code, functions and variables are annotated with
316 __init,, etc. (see the full list in include/linux/init.h),
317 which results in the code/data being placed in specific sections.
318 The section mismatch analysis is always performed after a full
319 kernel build, and enabling this option causes the following
320 additional steps to occur:
321 - Add the option -fno-inline-functions-called-once to gcc commands.
322 When inlining a function annotated with __init in a non-init
323 function, we would lose the section information and thus
324 the analysis would not catch the illegal reference.
325 This option tells gcc to inline less (but it does result in
327 - Run the section mismatch analysis for each module/built-in.o file.
328 When we run the section mismatch analysis on vmlinux.o, we
329 lose valuable information about where the mismatch was
331 Running the analysis for each module/built-in.o file
332 tells where the mismatch happens much closer to the
333 source. The drawback is that the same mismatch is
334 reported at least twice.
335 - Enable verbose reporting from modpost in order to help resolve
336 the section mismatches that are reported.
338 config SECTION_MISMATCH_WARN_ONLY
339 bool "Make section mismatch errors non-fatal"
342 If you say N here, the build process will fail if there are any
343 section mismatch, instead of just throwing warnings.
348 # Select this config option from the architecture Kconfig, if it
349 # is preferred to always offer frame pointers as a config
350 # option on the architecture (regardless of KERNEL_DEBUG):
352 config ARCH_WANT_FRAME_POINTERS
357 bool "Compile the kernel with frame pointers"
358 depends on DEBUG_KERNEL && \
359 (CRIS || M68K || FRV || UML || \
360 SUPERH || BLACKFIN || MN10300 || METAG) || \
361 ARCH_WANT_FRAME_POINTERS
362 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
364 If you say Y here the resulting kernel image will be slightly
365 larger and slower, but it gives very useful debugging information
366 in case of kernel bugs. (precise oopses/stacktraces/warnings)
368 config STACK_VALIDATION
369 bool "Compile-time stack metadata validation"
370 depends on HAVE_STACK_VALIDATION
373 Add compile-time checks to validate stack metadata, including frame
374 pointers (if CONFIG_FRAME_POINTER is enabled). This helps ensure
375 that runtime stack traces are more reliable.
377 For more information, see
378 tools/objtool/Documentation/stack-validation.txt.
380 config DEBUG_FORCE_WEAK_PER_CPU
381 bool "Force weak per-cpu definitions"
382 depends on DEBUG_KERNEL
384 s390 and alpha require percpu variables in modules to be
385 defined weak to work around addressing range issue which
386 puts the following two restrictions on percpu variable
389 1. percpu symbols must be unique whether static or not
390 2. percpu variables can't be defined inside a function
392 To ensure that generic code follows the above rules, this
393 option forces all percpu variables to be defined as weak.
395 endmenu # "Compiler options"
398 bool "Magic SysRq key"
401 If you say Y here, you will have some control over the system even
402 if the system crashes for example during kernel debugging (e.g., you
403 will be able to flush the buffer cache to disk, reboot the system
404 immediately or dump some status information). This is accomplished
405 by pressing various keys while holding SysRq (Alt+PrintScreen). It
406 also works on a serial console (on PC hardware at least), if you
407 send a BREAK and then within 5 seconds a command keypress. The
408 keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
409 Don't say Y unless you really know what this hack does.
411 config MAGIC_SYSRQ_DEFAULT_ENABLE
412 hex "Enable magic SysRq key functions by default"
413 depends on MAGIC_SYSRQ
416 Specifies which SysRq key functions are enabled by default.
417 This may be set to 1 or 0 to enable or disable them all, or
418 to a bitmask as described in Documentation/admin-guide/sysrq.rst.
420 config MAGIC_SYSRQ_SERIAL
421 bool "Enable magic SysRq key over serial"
422 depends on MAGIC_SYSRQ
425 Many embedded boards have a disconnected TTL level serial which can
426 generate some garbage that can lead to spurious false sysrq detects.
427 This option allows you to decide whether you want to enable the
431 bool "Kernel debugging"
433 Say Y here if you are developing drivers or trying to debug and
434 identify kernel problems.
436 menu "Memory Debugging"
438 source mm/Kconfig.debug
441 bool "Debug object operations"
442 depends on DEBUG_KERNEL
444 If you say Y here, additional code will be inserted into the
445 kernel to track the life time of various objects and validate
446 the operations on those objects.
448 config DEBUG_OBJECTS_SELFTEST
449 bool "Debug objects selftest"
450 depends on DEBUG_OBJECTS
452 This enables the selftest of the object debug code.
454 config DEBUG_OBJECTS_FREE
455 bool "Debug objects in freed memory"
456 depends on DEBUG_OBJECTS
458 This enables checks whether a k/v free operation frees an area
459 which contains an object which has not been deactivated
460 properly. This can make kmalloc/kfree-intensive workloads
463 config DEBUG_OBJECTS_TIMERS
464 bool "Debug timer objects"
465 depends on DEBUG_OBJECTS
467 If you say Y here, additional code will be inserted into the
468 timer routines to track the life time of timer objects and
469 validate the timer operations.
471 config DEBUG_OBJECTS_WORK
472 bool "Debug work objects"
473 depends on DEBUG_OBJECTS
475 If you say Y here, additional code will be inserted into the
476 work queue routines to track the life time of work objects and
477 validate the work operations.
479 config DEBUG_OBJECTS_RCU_HEAD
480 bool "Debug RCU callbacks objects"
481 depends on DEBUG_OBJECTS
483 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
485 config DEBUG_OBJECTS_PERCPU_COUNTER
486 bool "Debug percpu counter objects"
487 depends on DEBUG_OBJECTS
489 If you say Y here, additional code will be inserted into the
490 percpu counter routines to track the life time of percpu counter
491 objects and validate the percpu counter operations.
493 config DEBUG_OBJECTS_ENABLE_DEFAULT
494 int "debug_objects bootup default value (0-1)"
497 depends on DEBUG_OBJECTS
499 Debug objects boot parameter default value
502 bool "Debug slab memory allocations"
503 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
505 Say Y here to have the kernel do limited verification on memory
506 allocation as well as poisoning memory on free to catch use of freed
507 memory. This can make kmalloc/kfree-intensive workloads much slower.
509 config DEBUG_SLAB_LEAK
510 bool "Memory leak debugging"
511 depends on DEBUG_SLAB
514 bool "SLUB debugging on by default"
515 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
518 Boot with debugging on by default. SLUB boots by default with
519 the runtime debug capabilities switched off. Enabling this is
520 equivalent to specifying the "slub_debug" parameter on boot.
521 There is no support for more fine grained debug control like
522 possible with slub_debug=xxx. SLUB debugging may be switched
523 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
528 bool "Enable SLUB performance statistics"
529 depends on SLUB && SYSFS
531 SLUB statistics are useful to debug SLUBs allocation behavior in
532 order find ways to optimize the allocator. This should never be
533 enabled for production use since keeping statistics slows down
534 the allocator by a few percentage points. The slabinfo command
535 supports the determination of the most active slabs to figure
536 out which slabs are relevant to a particular load.
537 Try running: slabinfo -DA
539 config HAVE_DEBUG_KMEMLEAK
542 config DEBUG_KMEMLEAK
543 bool "Kernel memory leak detector"
544 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
546 select STACKTRACE if STACKTRACE_SUPPORT
550 Say Y here if you want to enable the memory leak
551 detector. The memory allocation/freeing is traced in a way
552 similar to the Boehm's conservative garbage collector, the
553 difference being that the orphan objects are not freed but
554 only shown in /sys/kernel/debug/kmemleak. Enabling this
555 feature will introduce an overhead to memory
556 allocations. See Documentation/dev-tools/kmemleak.rst for more
559 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
560 of finding leaks due to the slab objects poisoning.
562 In order to access the kmemleak file, debugfs needs to be
563 mounted (usually at /sys/kernel/debug).
565 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
566 int "Maximum kmemleak early log entries"
567 depends on DEBUG_KMEMLEAK
571 Kmemleak must track all the memory allocations to avoid
572 reporting false positives. Since memory may be allocated or
573 freed before kmemleak is initialised, an early log buffer is
574 used to store these actions. If kmemleak reports "early log
575 buffer exceeded", please increase this value.
577 config DEBUG_KMEMLEAK_TEST
578 tristate "Simple test for the kernel memory leak detector"
579 depends on DEBUG_KMEMLEAK && m
581 This option enables a module that explicitly leaks memory.
585 config DEBUG_KMEMLEAK_DEFAULT_OFF
586 bool "Default kmemleak to off"
587 depends on DEBUG_KMEMLEAK
589 Say Y here to disable kmemleak by default. It can then be enabled
590 on the command line via kmemleak=on.
592 config DEBUG_STACK_USAGE
593 bool "Stack utilization instrumentation"
594 depends on DEBUG_KERNEL && !IA64
596 Enables the display of the minimum amount of free stack which each
597 task has ever had available in the sysrq-T and sysrq-P debug output.
599 This option will slow down process creation somewhat.
603 depends on DEBUG_KERNEL
605 Enable this to turn on extended checks in the virtual-memory system
606 that may impact performance.
610 config DEBUG_VM_VMACACHE
611 bool "Debug VMA caching"
614 Enable this to turn on VMA caching debug information. Doing so
615 can cause significant overhead, so only enable it in non-production
621 bool "Debug VM red-black trees"
624 Enable VM red-black tree debugging information and extra validations.
628 config DEBUG_VM_PGFLAGS
629 bool "Debug page-flags operations"
632 Enables extra validation on page flags operations.
636 config ARCH_HAS_DEBUG_VIRTUAL
640 bool "Debug VM translations"
641 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
643 Enable some costly sanity checks in virtual to page code. This can
644 catch mistakes with virt_to_page() and friends.
648 config DEBUG_NOMMU_REGIONS
649 bool "Debug the global anon/private NOMMU mapping region tree"
650 depends on DEBUG_KERNEL && !MMU
652 This option causes the global tree of anonymous and private mapping
653 regions to be regularly checked for invalid topology.
655 config DEBUG_MEMORY_INIT
656 bool "Debug memory initialisation" if EXPERT
659 Enable this for additional checks during memory initialisation.
660 The sanity checks verify aspects of the VM such as the memory model
661 and other information provided by the architecture. Verbose
662 information will be printed at KERN_DEBUG loglevel depending
663 on the mminit_loglevel= command-line option.
667 config MEMORY_NOTIFIER_ERROR_INJECT
668 tristate "Memory hotplug notifier error injection module"
669 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
671 This option provides the ability to inject artificial errors to
672 memory hotplug notifier chain callbacks. It is controlled through
673 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
675 If the notifier call chain should be failed with some events
676 notified, write the error code to "actions/<notifier event>/error".
678 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
680 # cd /sys/kernel/debug/notifier-error-inject/memory
681 # echo -12 > actions/MEM_GOING_OFFLINE/error
682 # echo offline > /sys/devices/system/memory/memoryXXX/state
683 bash: echo: write error: Cannot allocate memory
685 To compile this code as a module, choose M here: the module will
686 be called memory-notifier-error-inject.
690 config DEBUG_PER_CPU_MAPS
691 bool "Debug access to per_cpu maps"
692 depends on DEBUG_KERNEL
695 Say Y to verify that the per_cpu map being accessed has
696 been set up. This adds a fair amount of code to kernel memory
697 and decreases performance.
702 bool "Highmem debugging"
703 depends on DEBUG_KERNEL && HIGHMEM
705 This option enables additional error checking for high memory
706 systems. Disable for production systems.
708 config HAVE_DEBUG_STACKOVERFLOW
711 config DEBUG_STACKOVERFLOW
712 bool "Check for stack overflows"
713 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
715 Say Y here if you want to check for overflows of kernel, IRQ
716 and exception stacks (if your architecture uses them). This
717 option will show detailed messages if free stack space drops
718 below a certain limit.
720 These kinds of bugs usually occur when call-chains in the
721 kernel get too deep, especially when interrupts are
724 Use this in cases where you see apparently random memory
725 corruption, especially if it appears in 'struct thread_info'
727 If in doubt, say "N".
729 source "lib/Kconfig.kmemcheck"
731 source "lib/Kconfig.kasan"
733 endmenu # "Memory Debugging"
738 KCOV does not have any arch-specific code, but currently it is enabled
739 only for x86_64. KCOV requires testing on other archs, and most likely
740 disabling of instrumentation for some early boot code.
743 bool "Code coverage for fuzzing"
744 depends on ARCH_HAS_KCOV
746 select GCC_PLUGINS if !COMPILE_TEST
747 select GCC_PLUGIN_SANCOV if !COMPILE_TEST
749 KCOV exposes kernel code coverage information in a form suitable
750 for coverage-guided fuzzing (randomized testing).
752 If RANDOMIZE_BASE is enabled, PC values will not be stable across
753 different machines and across reboots. If you need stable PC values,
754 disable RANDOMIZE_BASE.
756 For more details, see Documentation/dev-tools/kcov.rst.
758 config KCOV_INSTRUMENT_ALL
759 bool "Instrument all code by default"
763 If you are doing generic system call fuzzing (like e.g. syzkaller),
764 then you will want to instrument the whole kernel and you should
765 say y here. If you are doing more targeted fuzzing (like e.g.
766 filesystem fuzzing with AFL) then you will want to enable coverage
767 for more specific subsets of files, and should say n here.
770 bool "Debug shared IRQ handlers"
771 depends on DEBUG_KERNEL
773 Enable this to generate a spurious interrupt as soon as a shared
774 interrupt handler is registered, and just before one is deregistered.
775 Drivers ought to be able to handle interrupts coming in at those
776 points; some don't and need to be caught.
778 menu "Debug Lockups and Hangs"
780 config LOCKUP_DETECTOR
781 bool "Detect Hard and Soft Lockups"
782 depends on DEBUG_KERNEL && !S390
784 Say Y here to enable the kernel to act as a watchdog to detect
785 hard and soft lockups.
787 Softlockups are bugs that cause the kernel to loop in kernel
788 mode for more than 20 seconds, without giving other tasks a
789 chance to run. The current stack trace is displayed upon
790 detection and the system will stay locked up.
792 Hardlockups are bugs that cause the CPU to loop in kernel mode
793 for more than 10 seconds, without letting other interrupts have a
794 chance to run. The current stack trace is displayed upon detection
795 and the system will stay locked up.
797 The overhead should be minimal. A periodic hrtimer runs to
798 generate interrupts and kick the watchdog task every 4 seconds.
799 An NMI is generated every 10 seconds or so to check for hardlockups.
801 The frequency of hrtimer and NMI events and the soft and hard lockup
802 thresholds can be controlled through the sysctl watchdog_thresh.
804 config HARDLOCKUP_DETECTOR
806 depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
807 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
809 config BOOTPARAM_HARDLOCKUP_PANIC
810 bool "Panic (Reboot) On Hard Lockups"
811 depends on HARDLOCKUP_DETECTOR
813 Say Y here to enable the kernel to panic on "hard lockups",
814 which are bugs that cause the kernel to loop in kernel
815 mode with interrupts disabled for more than 10 seconds (configurable
816 using the watchdog_thresh sysctl).
820 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
822 depends on HARDLOCKUP_DETECTOR
824 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
825 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
827 config BOOTPARAM_SOFTLOCKUP_PANIC
828 bool "Panic (Reboot) On Soft Lockups"
829 depends on LOCKUP_DETECTOR
831 Say Y here to enable the kernel to panic on "soft lockups",
832 which are bugs that cause the kernel to loop in kernel
833 mode for more than 20 seconds (configurable using the watchdog_thresh
834 sysctl), without giving other tasks a chance to run.
836 The panic can be used in combination with panic_timeout,
837 to cause the system to reboot automatically after a
838 lockup has been detected. This feature is useful for
839 high-availability systems that have uptime guarantees and
840 where a lockup must be resolved ASAP.
844 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
846 depends on LOCKUP_DETECTOR
848 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
849 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
851 config DETECT_HUNG_TASK
852 bool "Detect Hung Tasks"
853 depends on DEBUG_KERNEL
854 default LOCKUP_DETECTOR
856 Say Y here to enable the kernel to detect "hung tasks",
857 which are bugs that cause the task to be stuck in
858 uninterruptible "D" state indefinitely.
860 When a hung task is detected, the kernel will print the
861 current stack trace (which you should report), but the
862 task will stay in uninterruptible state. If lockdep is
863 enabled then all held locks will also be reported. This
864 feature has negligible overhead.
866 config DEFAULT_HUNG_TASK_TIMEOUT
867 int "Default timeout for hung task detection (in seconds)"
868 depends on DETECT_HUNG_TASK
871 This option controls the default timeout (in seconds) used
872 to determine when a task has become non-responsive and should
875 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
876 sysctl or by writing a value to
877 /proc/sys/kernel/hung_task_timeout_secs.
879 A timeout of 0 disables the check. The default is two minutes.
880 Keeping the default should be fine in most cases.
882 config BOOTPARAM_HUNG_TASK_PANIC
883 bool "Panic (Reboot) On Hung Tasks"
884 depends on DETECT_HUNG_TASK
886 Say Y here to enable the kernel to panic on "hung tasks",
887 which are bugs that cause the kernel to leave a task stuck
888 in uninterruptible "D" state.
890 The panic can be used in combination with panic_timeout,
891 to cause the system to reboot automatically after a
892 hung task has been detected. This feature is useful for
893 high-availability systems that have uptime guarantees and
894 where a hung tasks must be resolved ASAP.
898 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
900 depends on DETECT_HUNG_TASK
902 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
903 default 1 if BOOTPARAM_HUNG_TASK_PANIC
906 bool "Detect Workqueue Stalls"
907 depends on DEBUG_KERNEL
909 Say Y here to enable stall detection on workqueues. If a
910 worker pool doesn't make forward progress on a pending work
911 item for over a given amount of time, 30s by default, a
912 warning message is printed along with dump of workqueue
913 state. This can be configured through kernel parameter
914 "workqueue.watchdog_thresh" and its sysfs counterpart.
916 endmenu # "Debug lockups and hangs"
921 Say Y here to enable the kernel to panic when it oopses. This
922 has the same effect as setting oops=panic on the kernel command
925 This feature is useful to ensure that the kernel does not do
926 anything erroneous after an oops which could result in data
927 corruption or other issues.
931 config PANIC_ON_OOPS_VALUE
934 default 0 if !PANIC_ON_OOPS
935 default 1 if PANIC_ON_OOPS
941 Set the timeout value (in seconds) until a reboot occurs when the
942 the kernel panics. If n = 0, then we wait forever. A timeout
943 value n > 0 will wait n seconds before rebooting, while a timeout
944 value n < 0 will reboot immediately.
947 bool "Collect scheduler debugging info"
948 depends on DEBUG_KERNEL && PROC_FS
951 If you say Y here, the /proc/sched_debug file will be provided
952 that can help debug the scheduler. The runtime overhead of this
960 bool "Collect scheduler statistics"
961 depends on DEBUG_KERNEL && PROC_FS
964 If you say Y here, additional code will be inserted into the
965 scheduler and related routines to collect statistics about
966 scheduler behavior and provide them in /proc/schedstat. These
967 stats may be useful for both tuning and debugging the scheduler
968 If you aren't debugging the scheduler or trying to tune a specific
969 application, you can say N to avoid the very slight overhead
972 config SCHED_STACK_END_CHECK
973 bool "Detect stack corruption on calls to schedule()"
974 depends on DEBUG_KERNEL
977 This option checks for a stack overrun on calls to schedule().
978 If the stack end location is found to be over written always panic as
979 the content of the corrupted region can no longer be trusted.
980 This is to ensure no erroneous behaviour occurs which could result in
981 data corruption or a sporadic crash at a later stage once the region
982 is examined. The runtime overhead introduced is minimal.
984 config DEBUG_TIMEKEEPING
985 bool "Enable extra timekeeping sanity checking"
987 This option will enable additional timekeeping sanity checks
988 which may be helpful when diagnosing issues where timekeeping
989 problems are suspected.
991 This may include checks in the timekeeping hotpaths, so this
992 option may have a (very small) performance impact to some
998 bool "Debug preemptible kernel"
999 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
1002 If you say Y here then the kernel will use a debug variant of the
1003 commonly used smp_processor_id() function and will print warnings
1004 if kernel code uses it in a preemption-unsafe way. Also, the kernel
1005 will detect preemption count underflows.
1007 menu "Lock Debugging (spinlocks, mutexes, etc...)"
1009 config DEBUG_RT_MUTEXES
1010 bool "RT Mutex debugging, deadlock detection"
1011 depends on DEBUG_KERNEL && RT_MUTEXES
1013 This allows rt mutex semantics violations and rt mutex related
1014 deadlocks (lockups) to be detected and reported automatically.
1016 config DEBUG_SPINLOCK
1017 bool "Spinlock and rw-lock debugging: basic checks"
1018 depends on DEBUG_KERNEL
1019 select UNINLINE_SPIN_UNLOCK
1021 Say Y here and build SMP to catch missing spinlock initialization
1022 and certain other kinds of spinlock errors commonly made. This is
1023 best used in conjunction with the NMI watchdog so that spinlock
1024 deadlocks are also debuggable.
1026 config DEBUG_MUTEXES
1027 bool "Mutex debugging: basic checks"
1028 depends on DEBUG_KERNEL
1030 This feature allows mutex semantics violations to be detected and
1033 config DEBUG_WW_MUTEX_SLOWPATH
1034 bool "Wait/wound mutex debugging: Slowpath testing"
1035 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1036 select DEBUG_LOCK_ALLOC
1037 select DEBUG_SPINLOCK
1038 select DEBUG_MUTEXES
1040 This feature enables slowpath testing for w/w mutex users by
1041 injecting additional -EDEADLK wound/backoff cases. Together with
1042 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1043 will test all possible w/w mutex interface abuse with the
1044 exception of simply not acquiring all the required locks.
1045 Note that this feature can introduce significant overhead, so
1046 it really should not be enabled in a production or distro kernel,
1047 even a debug kernel. If you are a driver writer, enable it. If
1048 you are a distro, do not.
1050 config DEBUG_LOCK_ALLOC
1051 bool "Lock debugging: detect incorrect freeing of live locks"
1052 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1053 select DEBUG_SPINLOCK
1054 select DEBUG_MUTEXES
1055 select DEBUG_RT_MUTEXES if RT_MUTEXES
1058 This feature will check whether any held lock (spinlock, rwlock,
1059 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1060 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1061 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1062 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1063 held during task exit.
1065 config PROVE_LOCKING
1066 bool "Lock debugging: prove locking correctness"
1067 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1069 select DEBUG_SPINLOCK
1070 select DEBUG_MUTEXES
1071 select DEBUG_RT_MUTEXES if RT_MUTEXES
1072 select DEBUG_LOCK_ALLOC
1073 select TRACE_IRQFLAGS
1076 This feature enables the kernel to prove that all locking
1077 that occurs in the kernel runtime is mathematically
1078 correct: that under no circumstance could an arbitrary (and
1079 not yet triggered) combination of observed locking
1080 sequences (on an arbitrary number of CPUs, running an
1081 arbitrary number of tasks and interrupt contexts) cause a
1084 In short, this feature enables the kernel to report locking
1085 related deadlocks before they actually occur.
1087 The proof does not depend on how hard and complex a
1088 deadlock scenario would be to trigger: how many
1089 participant CPUs, tasks and irq-contexts would be needed
1090 for it to trigger. The proof also does not depend on
1091 timing: if a race and a resulting deadlock is possible
1092 theoretically (no matter how unlikely the race scenario
1093 is), it will be proven so and will immediately be
1094 reported by the kernel (once the event is observed that
1095 makes the deadlock theoretically possible).
1097 If a deadlock is impossible (i.e. the locking rules, as
1098 observed by the kernel, are mathematically correct), the
1099 kernel reports nothing.
1101 NOTE: this feature can also be enabled for rwlocks, mutexes
1102 and rwsems - in which case all dependencies between these
1103 different locking variants are observed and mapped too, and
1104 the proof of observed correctness is also maintained for an
1105 arbitrary combination of these separate locking variants.
1107 For more details, see Documentation/locking/lockdep-design.txt.
1111 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1113 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC && !SCORE
1117 config LOCKDEP_SMALL
1121 bool "Lock usage statistics"
1122 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1124 select DEBUG_SPINLOCK
1125 select DEBUG_MUTEXES
1126 select DEBUG_RT_MUTEXES if RT_MUTEXES
1127 select DEBUG_LOCK_ALLOC
1130 This feature enables tracking lock contention points
1132 For more details, see Documentation/locking/lockstat.txt
1134 This also enables lock events required by "perf lock",
1136 If you want to use "perf lock", you also need to turn on
1137 CONFIG_EVENT_TRACING.
1139 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1140 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1142 config DEBUG_LOCKDEP
1143 bool "Lock dependency engine debugging"
1144 depends on DEBUG_KERNEL && LOCKDEP
1146 If you say Y here, the lock dependency engine will do
1147 additional runtime checks to debug itself, at the price
1148 of more runtime overhead.
1150 config DEBUG_ATOMIC_SLEEP
1151 bool "Sleep inside atomic section checking"
1152 select PREEMPT_COUNT
1153 depends on DEBUG_KERNEL
1155 If you say Y here, various routines which may sleep will become very
1156 noisy if they are called inside atomic sections: when a spinlock is
1157 held, inside an rcu read side critical section, inside preempt disabled
1158 sections, inside an interrupt, etc...
1160 config DEBUG_LOCKING_API_SELFTESTS
1161 bool "Locking API boot-time self-tests"
1162 depends on DEBUG_KERNEL
1164 Say Y here if you want the kernel to run a short self-test during
1165 bootup. The self-test checks whether common types of locking bugs
1166 are detected by debugging mechanisms or not. (if you disable
1167 lock debugging then those bugs wont be detected of course.)
1168 The following locking APIs are covered: spinlocks, rwlocks,
1171 config LOCK_TORTURE_TEST
1172 tristate "torture tests for locking"
1173 depends on DEBUG_KERNEL
1177 This option provides a kernel module that runs torture tests
1178 on kernel locking primitives. The kernel module may be built
1179 after the fact on the running kernel to be tested, if desired.
1181 Say Y here if you want kernel locking-primitive torture tests
1182 to be built into the kernel.
1183 Say M if you want these torture tests to build as a module.
1184 Say N if you are unsure.
1186 config WW_MUTEX_SELFTEST
1187 tristate "Wait/wound mutex selftests"
1189 This option provides a kernel module that runs tests on the
1190 on the struct ww_mutex locking API.
1192 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1193 with this test harness.
1195 Say M if you want these self tests to build as a module.
1196 Say N if you are unsure.
1198 endmenu # lock debugging
1200 config TRACE_IRQFLAGS
1203 Enables hooks to interrupt enabling and disabling for
1204 either tracing or lock debugging.
1207 bool "Stack backtrace support"
1208 depends on STACKTRACE_SUPPORT
1210 This option causes the kernel to create a /proc/pid/stack for
1211 every process, showing its current stack trace.
1212 It is also used by various kernel debugging features that require
1213 stack trace generation.
1215 config DEBUG_KOBJECT
1216 bool "kobject debugging"
1217 depends on DEBUG_KERNEL
1219 If you say Y here, some extra kobject debugging messages will be sent
1222 config DEBUG_KOBJECT_RELEASE
1223 bool "kobject release debugging"
1224 depends on DEBUG_OBJECTS_TIMERS
1226 kobjects are reference counted objects. This means that their
1227 last reference count put is not predictable, and the kobject can
1228 live on past the point at which a driver decides to drop it's
1229 initial reference to the kobject gained on allocation. An
1230 example of this would be a struct device which has just been
1233 However, some buggy drivers assume that after such an operation,
1234 the memory backing the kobject can be immediately freed. This
1235 goes completely against the principles of a refcounted object.
1237 If you say Y here, the kernel will delay the release of kobjects
1238 on the last reference count to improve the visibility of this
1239 kind of kobject release bug.
1241 config HAVE_DEBUG_BUGVERBOSE
1244 config DEBUG_BUGVERBOSE
1245 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
1246 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
1249 Say Y here to make BUG() panics output the file name and line number
1250 of the BUG call as well as the EIP and oops trace. This aids
1251 debugging but costs about 70-100K of memory.
1254 bool "Debug linked list manipulation"
1255 depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION
1257 Enable this to turn on extended checks in the linked-list
1262 config DEBUG_PI_LIST
1263 bool "Debug priority linked list manipulation"
1264 depends on DEBUG_KERNEL
1266 Enable this to turn on extended checks in the priority-ordered
1267 linked-list (plist) walking routines. This checks the entire
1268 list multiple times during each manipulation.
1273 bool "Debug SG table operations"
1274 depends on DEBUG_KERNEL
1276 Enable this to turn on checks on scatter-gather tables. This can
1277 help find problems with drivers that do not properly initialize
1282 config DEBUG_NOTIFIERS
1283 bool "Debug notifier call chains"
1284 depends on DEBUG_KERNEL
1286 Enable this to turn on sanity checking for notifier call chains.
1287 This is most useful for kernel developers to make sure that
1288 modules properly unregister themselves from notifier chains.
1289 This is a relatively cheap check but if you care about maximum
1292 config DEBUG_CREDENTIALS
1293 bool "Debug credential management"
1294 depends on DEBUG_KERNEL
1296 Enable this to turn on some debug checking for credential
1297 management. The additional code keeps track of the number of
1298 pointers from task_structs to any given cred struct, and checks to
1299 see that this number never exceeds the usage count of the cred
1302 Furthermore, if SELinux is enabled, this also checks that the
1303 security pointer in the cred struct is never seen to be invalid.
1307 source "kernel/rcu/Kconfig.debug"
1309 config DEBUG_WQ_FORCE_RR_CPU
1310 bool "Force round-robin CPU selection for unbound work items"
1311 depends on DEBUG_KERNEL
1314 Workqueue used to implicitly guarantee that work items queued
1315 without explicit CPU specified are put on the local CPU. This
1316 guarantee is no longer true and while local CPU is still
1317 preferred work items may be put on foreign CPUs. Kernel
1318 parameter "workqueue.debug_force_rr_cpu" is added to force
1319 round-robin CPU selection to flush out usages which depend on the
1320 now broken guarantee. This config option enables the debug
1321 feature by default. When enabled, memory and cache locality will
1324 config DEBUG_BLOCK_EXT_DEVT
1325 bool "Force extended block device numbers and spread them"
1326 depends on DEBUG_KERNEL
1330 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1331 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1332 YOU ARE DOING. Distros, please enable this and fix whatever
1335 Conventionally, block device numbers are allocated from
1336 predetermined contiguous area. However, extended block area
1337 may introduce non-contiguous block device numbers. This
1338 option forces most block device numbers to be allocated from
1339 the extended space and spreads them to discover kernel or
1340 userland code paths which assume predetermined contiguous
1341 device number allocation.
1343 Note that turning on this debug option shuffles all the
1344 device numbers for all IDE and SCSI devices including libata
1345 ones, so root partition specified using device number
1346 directly (via rdev or root=MAJ:MIN) won't work anymore.
1347 Textual device names (root=/dev/sdXn) will continue to work.
1349 Say N if you are unsure.
1351 config CPU_HOTPLUG_STATE_CONTROL
1352 bool "Enable CPU hotplug state control"
1353 depends on DEBUG_KERNEL
1354 depends on HOTPLUG_CPU
1357 Allows to write steps between "offline" and "online" to the CPUs
1358 sysfs target file so states can be stepped granular. This is a debug
1359 option for now as the hotplug machinery cannot be stopped and
1360 restarted at arbitrary points yet.
1362 Say N if your are unsure.
1364 config NOTIFIER_ERROR_INJECTION
1365 tristate "Notifier error injection"
1366 depends on DEBUG_KERNEL
1369 This option provides the ability to inject artificial errors to
1370 specified notifier chain callbacks. It is useful to test the error
1371 handling of notifier call chain failures.
1375 config PM_NOTIFIER_ERROR_INJECT
1376 tristate "PM notifier error injection module"
1377 depends on PM && NOTIFIER_ERROR_INJECTION
1378 default m if PM_DEBUG
1380 This option provides the ability to inject artificial errors to
1381 PM notifier chain callbacks. It is controlled through debugfs
1382 interface /sys/kernel/debug/notifier-error-inject/pm
1384 If the notifier call chain should be failed with some events
1385 notified, write the error code to "actions/<notifier event>/error".
1387 Example: Inject PM suspend error (-12 = -ENOMEM)
1389 # cd /sys/kernel/debug/notifier-error-inject/pm/
1390 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1391 # echo mem > /sys/power/state
1392 bash: echo: write error: Cannot allocate memory
1394 To compile this code as a module, choose M here: the module will
1395 be called pm-notifier-error-inject.
1399 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1400 tristate "OF reconfig notifier error injection module"
1401 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1403 This option provides the ability to inject artificial errors to
1404 OF reconfig notifier chain callbacks. It is controlled
1405 through debugfs interface under
1406 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1408 If the notifier call chain should be failed with some events
1409 notified, write the error code to "actions/<notifier event>/error".
1411 To compile this code as a module, choose M here: the module will
1412 be called of-reconfig-notifier-error-inject.
1416 config NETDEV_NOTIFIER_ERROR_INJECT
1417 tristate "Netdev notifier error injection module"
1418 depends on NET && NOTIFIER_ERROR_INJECTION
1420 This option provides the ability to inject artificial errors to
1421 netdevice notifier chain callbacks. It is controlled through debugfs
1422 interface /sys/kernel/debug/notifier-error-inject/netdev
1424 If the notifier call chain should be failed with some events
1425 notified, write the error code to "actions/<notifier event>/error".
1427 Example: Inject netdevice mtu change error (-22 = -EINVAL)
1429 # cd /sys/kernel/debug/notifier-error-inject/netdev
1430 # echo -22 > actions/NETDEV_CHANGEMTU/error
1431 # ip link set eth0 mtu 1024
1432 RTNETLINK answers: Invalid argument
1434 To compile this code as a module, choose M here: the module will
1435 be called netdev-notifier-error-inject.
1439 config FAULT_INJECTION
1440 bool "Fault-injection framework"
1441 depends on DEBUG_KERNEL
1443 Provide fault-injection framework.
1444 For more details, see Documentation/fault-injection/.
1447 bool "Fault-injection capability for kmalloc"
1448 depends on FAULT_INJECTION
1449 depends on SLAB || SLUB
1451 Provide fault-injection capability for kmalloc.
1453 config FAIL_PAGE_ALLOC
1454 bool "Fault-injection capabilitiy for alloc_pages()"
1455 depends on FAULT_INJECTION
1457 Provide fault-injection capability for alloc_pages().
1459 config FAIL_MAKE_REQUEST
1460 bool "Fault-injection capability for disk IO"
1461 depends on FAULT_INJECTION && BLOCK
1463 Provide fault-injection capability for disk IO.
1465 config FAIL_IO_TIMEOUT
1466 bool "Fault-injection capability for faking disk interrupts"
1467 depends on FAULT_INJECTION && BLOCK
1469 Provide fault-injection capability on end IO handling. This
1470 will make the block layer "forget" an interrupt as configured,
1471 thus exercising the error handling.
1473 Only works with drivers that use the generic timeout handling,
1474 for others it wont do anything.
1476 config FAIL_MMC_REQUEST
1477 bool "Fault-injection capability for MMC IO"
1478 depends on FAULT_INJECTION_DEBUG_FS && MMC
1480 Provide fault-injection capability for MMC IO.
1481 This will make the mmc core return data errors. This is
1482 useful to test the error handling in the mmc block device
1483 and to test how the mmc host driver handles retries from
1487 bool "Fault-injection capability for futexes"
1489 depends on FAULT_INJECTION && FUTEX
1491 Provide fault-injection capability for futexes.
1493 config FAULT_INJECTION_DEBUG_FS
1494 bool "Debugfs entries for fault-injection capabilities"
1495 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1497 Enable configuration of fault-injection capabilities via debugfs.
1499 config FAULT_INJECTION_STACKTRACE_FILTER
1500 bool "stacktrace filter for fault-injection capabilities"
1501 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1504 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC && !SCORE
1506 Provide stacktrace filter for fault-injection capabilities
1509 bool "Latency measuring infrastructure"
1510 depends on DEBUG_KERNEL
1511 depends on STACKTRACE_SUPPORT
1513 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC
1520 Enable this option if you want to use the LatencyTOP tool
1521 to find out which userspace is blocking on what kernel operations.
1523 source kernel/trace/Kconfig
1525 menu "Runtime Testing"
1528 tristate "Linux Kernel Dump Test Tool Module"
1533 This module enables testing of the different dumping mechanisms by
1534 inducing system failures at predefined crash points.
1535 If you don't need it: say N
1536 Choose M here to compile this code as a module. The module will be
1539 Documentation on how to use the module can be found in
1540 Documentation/fault-injection/provoke-crashes.txt
1542 config TEST_LIST_SORT
1543 tristate "Linked list sorting test"
1544 depends on DEBUG_KERNEL || m
1546 Enable this to turn on 'list_sort()' function test. This test is
1547 executed only once during system boot (so affects only boot time),
1548 or at module load time.
1553 tristate "Array-based sort test"
1554 depends on DEBUG_KERNEL || m
1556 This option enables the self-test function of 'sort()' at boot,
1557 or at module load time.
1561 config KPROBES_SANITY_TEST
1562 bool "Kprobes sanity tests"
1563 depends on DEBUG_KERNEL
1567 This option provides for testing basic kprobes functionality on
1568 boot. A sample kprobe, jprobe and kretprobe are inserted and
1569 verified for functionality.
1571 Say N if you are unsure.
1573 config BACKTRACE_SELF_TEST
1574 tristate "Self test for the backtrace code"
1575 depends on DEBUG_KERNEL
1578 This option provides a kernel module that can be used to test
1579 the kernel stack backtrace code. This option is not useful
1580 for distributions or general kernels, but only for kernel
1581 developers working on architecture code.
1583 Note that if you want to also test saved backtraces, you will
1584 have to enable STACKTRACE as well.
1586 Say N if you are unsure.
1589 tristate "Red-Black tree test"
1590 depends on DEBUG_KERNEL
1592 A benchmark measuring the performance of the rbtree library.
1593 Also includes rbtree invariant checks.
1595 config INTERVAL_TREE_TEST
1596 tristate "Interval tree test"
1597 depends on m && DEBUG_KERNEL
1598 select INTERVAL_TREE
1600 A benchmark measuring the performance of the interval tree library
1603 tristate "Per cpu operations test"
1604 depends on m && DEBUG_KERNEL
1606 Enable this option to build test module which validates per-cpu
1611 config ATOMIC64_SELFTEST
1612 tristate "Perform an atomic64_t self-test"
1614 Enable this option to test the atomic64_t functions at boot or
1615 at module load time.
1619 config ASYNC_RAID6_TEST
1620 tristate "Self test for hardware accelerated raid6 recovery"
1621 depends on ASYNC_RAID6_RECOV
1624 This is a one-shot self test that permutes through the
1625 recovery of all the possible two disk failure scenarios for a
1626 N-disk array. Recovery is performed with the asynchronous
1627 raid6 recovery routines, and will optionally use an offload
1628 engine if one is available.
1633 tristate "Test functions located in the hexdump module at runtime"
1635 config TEST_STRING_HELPERS
1636 tristate "Test functions located in the string_helpers module at runtime"
1639 tristate "Test kstrto*() family of functions at runtime"
1642 tristate "Test printf() family of functions at runtime"
1645 tristate "Test bitmap_*() family of functions at runtime"
1648 Enable this option to test the bitmap functions at boot.
1653 tristate "Test functions located in the uuid module at runtime"
1655 config TEST_RHASHTABLE
1656 tristate "Perform selftest on resizable hash table"
1659 Enable this option to test the rhashtable functions at boot.
1664 tristate "Perform selftest on hash functions"
1667 Enable this option to test the kernel's integer (<linux/hash.h>),
1668 string (<linux/stringhash.h>), and siphash (<linux/siphash.h>)
1669 hash functions on boot (or module load).
1671 This is intended to help people writing architecture-specific
1672 optimized versions. If unsure, say N.
1675 tristate "Perform selftest on priority array manager"
1679 Enable this option to test priority array manager on boot
1684 endmenu # runtime tests
1686 config PROVIDE_OHCI1394_DMA_INIT
1687 bool "Remote debugging over FireWire early on boot"
1688 depends on PCI && X86
1690 If you want to debug problems which hang or crash the kernel early
1691 on boot and the crashing machine has a FireWire port, you can use
1692 this feature to remotely access the memory of the crashed machine
1693 over FireWire. This employs remote DMA as part of the OHCI1394
1694 specification which is now the standard for FireWire controllers.
1696 With remote DMA, you can monitor the printk buffer remotely using
1697 firescope and access all memory below 4GB using fireproxy from gdb.
1698 Even controlling a kernel debugger is possible using remote DMA.
1702 If ohci1394_dma=early is used as boot parameter, it will initialize
1703 all OHCI1394 controllers which are found in the PCI config space.
1705 As all changes to the FireWire bus such as enabling and disabling
1706 devices cause a bus reset and thereby disable remote DMA for all
1707 devices, be sure to have the cable plugged and FireWire enabled on
1708 the debugging host before booting the debug target for debugging.
1710 This code (~1k) is freed after boot. By then, the firewire stack
1711 in charge of the OHCI-1394 controllers should be used instead.
1713 See Documentation/debugging-via-ohci1394.txt for more information.
1715 config DMA_API_DEBUG
1716 bool "Enable debugging of DMA-API usage"
1717 depends on HAVE_DMA_API_DEBUG
1719 Enable this option to debug the use of the DMA API by device drivers.
1720 With this option you will be able to detect common bugs in device
1721 drivers like double-freeing of DMA mappings or freeing mappings that
1722 were never allocated.
1724 This also attempts to catch cases where a page owned by DMA is
1725 accessed by the cpu in a way that could cause data corruption. For
1726 example, this enables cow_user_page() to check that the source page is
1729 This option causes a performance degradation. Use only if you want to
1730 debug device drivers and dma interactions.
1735 tristate "Test module loading with 'hello world' module"
1739 This builds the "test_module" module that emits "Hello, world"
1740 on printk when loaded. It is designed to be used for basic
1741 evaluation of the module loading subsystem (for example when
1742 validating module verification). It lacks any extra dependencies,
1743 and will not normally be loaded by the system unless explicitly
1748 config TEST_USER_COPY
1749 tristate "Test user/kernel boundary protections"
1753 This builds the "test_user_copy" module that runs sanity checks
1754 on the copy_to/from_user infrastructure, making sure basic
1755 user/kernel boundary testing is working. If it fails to load,
1756 a regression has been detected in the user/kernel memory boundary
1762 tristate "Test BPF filter functionality"
1766 This builds the "test_bpf" module that runs various test vectors
1767 against the BPF interpreter or BPF JIT compiler depending on the
1768 current setting. This is in particular useful for BPF JIT compiler
1769 development, but also to run regression tests against changes in
1770 the interpreter code. It also enables test stubs for eBPF maps and
1771 verifier used by user space verifier testsuite.
1775 config TEST_FIRMWARE
1776 tristate "Test firmware loading via userspace interface"
1778 depends on FW_LOADER
1780 This builds the "test_firmware" module that creates a userspace
1781 interface for testing firmware loading. This can be used to
1782 control the triggering of firmware loading without needing an
1783 actual firmware-using device. The contents can be rechecked by
1789 tristate "udelay test driver"
1792 This builds the "udelay_test" module that helps to make sure
1793 that udelay() is working properly.
1799 depends on HAVE_MEMBLOCK
1801 This option adds a kernel parameter 'memtest', which allows memtest
1803 memtest=0, mean disabled; -- default
1804 memtest=1, mean do 1 test pattern;
1806 memtest=17, mean do 17 test patterns.
1807 If you are unsure how to answer this question, answer N.
1809 config TEST_STATIC_KEYS
1810 tristate "Test static keys"
1814 Test the static key interfaces.
1818 config BUG_ON_DATA_CORRUPTION
1819 bool "Trigger a BUG when data corruption is detected"
1822 Select this option if the kernel should BUG when it encounters
1823 data corruption in kernel memory structures when they get checked
1828 source "samples/Kconfig"
1830 source "lib/Kconfig.kgdb"
1832 source "lib/Kconfig.ubsan"
1834 config ARCH_HAS_DEVMEM_IS_ALLOWED
1837 config STRICT_DEVMEM
1838 bool "Filter access to /dev/mem"
1839 depends on MMU && DEVMEM
1840 depends on ARCH_HAS_DEVMEM_IS_ALLOWED
1841 default y if TILE || PPC
1843 If this option is disabled, you allow userspace (root) access to all
1844 of memory, including kernel and userspace memory. Accidental
1845 access to this is obviously disastrous, but specific access can
1846 be used by people debugging the kernel. Note that with PAT support
1847 enabled, even in this case there are restrictions on /dev/mem
1848 use due to the cache aliasing requirements.
1850 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
1851 file only allows userspace access to PCI space and the BIOS code and
1852 data regions. This is sufficient for dosemu and X and all common
1857 config IO_STRICT_DEVMEM
1858 bool "Filter I/O access to /dev/mem"
1859 depends on STRICT_DEVMEM
1861 If this option is disabled, you allow userspace (root) access to all
1862 io-memory regardless of whether a driver is actively using that
1863 range. Accidental access to this is obviously disastrous, but
1864 specific access can be used by people debugging kernel drivers.
1866 If this option is switched on, the /dev/mem file only allows
1867 userspace access to *idle* io-memory ranges (see /proc/iomem) This
1868 may break traditional users of /dev/mem (dosemu, legacy X, etc...)
1869 if the driver using a given range cannot be disabled.
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