1 # SPDX-License-Identifier: GPL-2.0-only
4 menu "printk and dmesg options"
7 bool "Show timing information on printks"
10 Selecting this option causes time stamps of the printk()
11 messages to be added to the output of the syslog() system
12 call and at the console.
14 The timestamp is always recorded internally, and exported
15 to /dev/kmsg. This flag just specifies if the timestamp should
16 be included, not that the timestamp is recorded.
18 The behavior is also controlled by the kernel command line
19 parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst
22 bool "Show caller information on printks"
25 Selecting this option causes printk() to add a caller "thread id" (if
26 in task context) or a caller "processor id" (if not in task context)
29 This option is intended for environments where multiple threads
30 concurrently call printk() for many times, for it is difficult to
31 interpret without knowing where these lines (or sometimes individual
32 line which was divided into multiple lines due to race) came from.
34 Since toggling after boot makes the code racy, currently there is
35 no option to enable/disable at the kernel command line parameter or
38 config CONSOLE_LOGLEVEL_DEFAULT
39 int "Default console loglevel (1-15)"
43 Default loglevel to determine what will be printed on the console.
45 Setting a default here is equivalent to passing in loglevel=<x> in
46 the kernel bootargs. loglevel=<x> continues to override whatever
47 value is specified here as well.
49 Note: This does not affect the log level of un-prefixed printk()
50 usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT
53 config CONSOLE_LOGLEVEL_QUIET
54 int "quiet console loglevel (1-15)"
58 loglevel to use when "quiet" is passed on the kernel commandline.
60 When "quiet" is passed on the kernel commandline this loglevel
61 will be used as the loglevel. IOW passing "quiet" will be the
62 equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>"
64 config MESSAGE_LOGLEVEL_DEFAULT
65 int "Default message log level (1-7)"
69 Default log level for printk statements with no specified priority.
71 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
72 that are auditing their logs closely may want to set it to a lower
75 Note: This does not affect what message level gets printed on the console
76 by default. To change that, use loglevel=<x> in the kernel bootargs,
77 or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value.
79 config BOOT_PRINTK_DELAY
80 bool "Delay each boot printk message by N milliseconds"
81 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
83 This build option allows you to read kernel boot messages
84 by inserting a short delay after each one. The delay is
85 specified in milliseconds on the kernel command line,
88 It is likely that you would also need to use "lpj=M" to preset
89 the "loops per jiffie" value.
90 See a previous boot log for the "lpj" value to use for your
91 system, and then set "lpj=M" before setting "boot_delay=N".
92 NOTE: Using this option may adversely affect SMP systems.
93 I.e., processors other than the first one may not boot up.
94 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
95 what it believes to be lockup conditions.
98 bool "Enable dynamic printk() support"
104 Compiles debug level messages into the kernel, which would not
105 otherwise be available at runtime. These messages can then be
106 enabled/disabled based on various levels of scope - per source file,
107 function, module, format string, and line number. This mechanism
108 implicitly compiles in all pr_debug() and dev_dbg() calls, which
109 enlarges the kernel text size by about 2%.
111 If a source file is compiled with DEBUG flag set, any
112 pr_debug() calls in it are enabled by default, but can be
113 disabled at runtime as below. Note that DEBUG flag is
114 turned on by many CONFIG_*DEBUG* options.
118 Dynamic debugging is controlled via the 'dynamic_debug/control' file,
119 which is contained in the 'debugfs' filesystem. Thus, the debugfs
120 filesystem must first be mounted before making use of this feature.
121 We refer the control file as: <debugfs>/dynamic_debug/control. This
122 file contains a list of the debug statements that can be enabled. The
123 format for each line of the file is:
125 filename:lineno [module]function flags format
127 filename : source file of the debug statement
128 lineno : line number of the debug statement
129 module : module that contains the debug statement
130 function : function that contains the debug statement
131 flags : '=p' means the line is turned 'on' for printing
132 format : the format used for the debug statement
136 nullarbor:~ # cat <debugfs>/dynamic_debug/control
137 # filename:lineno [module]function flags format
138 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
139 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
140 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
144 // enable the message at line 1603 of file svcsock.c
145 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
146 <debugfs>/dynamic_debug/control
148 // enable all the messages in file svcsock.c
149 nullarbor:~ # echo -n 'file svcsock.c +p' >
150 <debugfs>/dynamic_debug/control
152 // enable all the messages in the NFS server module
153 nullarbor:~ # echo -n 'module nfsd +p' >
154 <debugfs>/dynamic_debug/control
156 // enable all 12 messages in the function svc_process()
157 nullarbor:~ # echo -n 'func svc_process +p' >
158 <debugfs>/dynamic_debug/control
160 // disable all 12 messages in the function svc_process()
161 nullarbor:~ # echo -n 'func svc_process -p' >
162 <debugfs>/dynamic_debug/control
164 See Documentation/admin-guide/dynamic-debug-howto.rst for additional
167 endmenu # "printk and dmesg options"
169 menu "Compile-time checks and compiler options"
172 bool "Compile the kernel with debug info"
173 depends on DEBUG_KERNEL && !COMPILE_TEST
175 If you say Y here the resulting kernel image will include
176 debugging info resulting in a larger kernel image.
177 This adds debug symbols to the kernel and modules (gcc -g), and
178 is needed if you intend to use kernel crashdump or binary object
179 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
180 Say Y here only if you plan to debug the kernel.
184 config DEBUG_INFO_REDUCED
185 bool "Reduce debugging information"
186 depends on DEBUG_INFO
188 If you say Y here gcc is instructed to generate less debugging
189 information for structure types. This means that tools that
190 need full debugging information (like kgdb or systemtap) won't
191 be happy. But if you merely need debugging information to
192 resolve line numbers there is no loss. Advantage is that
193 build directory object sizes shrink dramatically over a full
194 DEBUG_INFO build and compile times are reduced too.
195 Only works with newer gcc versions.
197 config DEBUG_INFO_SPLIT
198 bool "Produce split debuginfo in .dwo files"
199 depends on DEBUG_INFO
200 depends on $(cc-option,-gsplit-dwarf)
202 Generate debug info into separate .dwo files. This significantly
203 reduces the build directory size for builds with DEBUG_INFO,
204 because it stores the information only once on disk in .dwo
205 files instead of multiple times in object files and executables.
206 In addition the debug information is also compressed.
208 Requires recent gcc (4.7+) and recent gdb/binutils.
209 Any tool that packages or reads debug information would need
210 to know about the .dwo files and include them.
211 Incompatible with older versions of ccache.
213 config DEBUG_INFO_DWARF4
214 bool "Generate dwarf4 debuginfo"
215 depends on DEBUG_INFO
216 depends on $(cc-option,-gdwarf-4)
218 Generate dwarf4 debug info. This requires recent versions
219 of gcc and gdb. It makes the debug information larger.
220 But it significantly improves the success of resolving
221 variables in gdb on optimized code.
223 config DEBUG_INFO_BTF
224 bool "Generate BTF typeinfo"
225 depends on DEBUG_INFO
227 Generate deduplicated BTF type information from DWARF debug info.
228 Turning this on expects presence of pahole tool, which will convert
229 DWARF type info into equivalent deduplicated BTF type info.
232 bool "Provide GDB scripts for kernel debugging"
233 depends on DEBUG_INFO
235 This creates the required links to GDB helper scripts in the
236 build directory. If you load vmlinux into gdb, the helper
237 scripts will be automatically imported by gdb as well, and
238 additional functions are available to analyze a Linux kernel
239 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
242 config ENABLE_MUST_CHECK
243 bool "Enable __must_check logic"
246 Enable the __must_check logic in the kernel build. Disable this to
247 suppress the "warning: ignoring return value of 'foo', declared with
248 attribute warn_unused_result" messages.
251 int "Warn for stack frames larger than (needs gcc 4.4)"
253 default 2048 if GCC_PLUGIN_LATENT_ENTROPY
254 default 1280 if (!64BIT && PARISC)
255 default 1024 if (!64BIT && !PARISC)
256 default 2048 if 64BIT
258 Tell gcc to warn at build time for stack frames larger than this.
259 Setting this too low will cause a lot of warnings.
260 Setting it to 0 disables the warning.
263 config STRIP_ASM_SYMS
264 bool "Strip assembler-generated symbols during link"
267 Strip internal assembler-generated symbols during a link (symbols
268 that look like '.Lxxx') so they don't pollute the output of
269 get_wchan() and suchlike.
272 bool "Generate readable assembler code"
273 depends on DEBUG_KERNEL
275 Disable some compiler optimizations that tend to generate human unreadable
276 assembler output. This may make the kernel slightly slower, but it helps
277 to keep kernel developers who have to stare a lot at assembler listings
281 bool "Debug Filesystem"
283 debugfs is a virtual file system that kernel developers use to put
284 debugging files into. Enable this option to be able to read and
285 write to these files.
287 For detailed documentation on the debugfs API, see
288 Documentation/filesystems/.
292 config HEADERS_INSTALL
293 bool "Install uapi headers to usr/include"
296 This option will install uapi headers (headers exported to user-space)
297 into the usr/include directory for use during the kernel build.
298 This is unneeded for building the kernel itself, but needed for some
299 user-space program samples. It is also needed by some features such
300 as uapi header sanity checks.
303 bool "Run sanity checks on uapi headers when building 'all'"
304 depends on HEADERS_INSTALL
306 This option will run basic sanity checks on uapi headers when
307 building the 'all' target, for example, ensure that they do not
308 attempt to include files which were not exported, etc.
310 If you're making modifications to header files which are
311 relevant for userspace, say 'Y'.
313 config OPTIMIZE_INLINING
316 This option determines if the kernel forces gcc to inline the functions
317 developers have marked 'inline'. Doing so takes away freedom from gcc to
318 do what it thinks is best, which is desirable for the gcc 3.x series of
319 compilers. The gcc 4.x series have a rewritten inlining algorithm and
320 enabling this option will generate a smaller kernel there. Hopefully
321 this algorithm is so good that allowing gcc 4.x and above to make the
322 decision will become the default in the future. Until then this option
323 is there to test gcc for this.
325 config DEBUG_SECTION_MISMATCH
326 bool "Enable full Section mismatch analysis"
328 The section mismatch analysis checks if there are illegal
329 references from one section to another section.
330 During linktime or runtime, some sections are dropped;
331 any use of code/data previously in these sections would
332 most likely result in an oops.
333 In the code, functions and variables are annotated with
334 __init,, etc. (see the full list in include/linux/init.h),
335 which results in the code/data being placed in specific sections.
336 The section mismatch analysis is always performed after a full
337 kernel build, and enabling this option causes the following
338 additional step to occur:
339 - Add the option -fno-inline-functions-called-once to gcc commands.
340 When inlining a function annotated with __init in a non-init
341 function, we would lose the section information and thus
342 the analysis would not catch the illegal reference.
343 This option tells gcc to inline less (but it does result in
346 config SECTION_MISMATCH_WARN_ONLY
347 bool "Make section mismatch errors non-fatal"
350 If you say N here, the build process will fail if there are any
351 section mismatch, instead of just throwing warnings.
356 # Select this config option from the architecture Kconfig, if it
357 # is preferred to always offer frame pointers as a config
358 # option on the architecture (regardless of KERNEL_DEBUG):
360 config ARCH_WANT_FRAME_POINTERS
364 bool "Compile the kernel with frame pointers"
365 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
366 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
368 If you say Y here the resulting kernel image will be slightly
369 larger and slower, but it gives very useful debugging information
370 in case of kernel bugs. (precise oopses/stacktraces/warnings)
372 config STACK_VALIDATION
373 bool "Compile-time stack metadata validation"
374 depends on HAVE_STACK_VALIDATION
377 Add compile-time checks to validate stack metadata, including frame
378 pointers (if CONFIG_FRAME_POINTER is enabled). This helps ensure
379 that runtime stack traces are more reliable.
381 This is also a prerequisite for generation of ORC unwind data, which
382 is needed for CONFIG_UNWINDER_ORC.
384 For more information, see
385 tools/objtool/Documentation/stack-validation.txt.
387 config DEBUG_FORCE_WEAK_PER_CPU
388 bool "Force weak per-cpu definitions"
389 depends on DEBUG_KERNEL
391 s390 and alpha require percpu variables in modules to be
392 defined weak to work around addressing range issue which
393 puts the following two restrictions on percpu variable
396 1. percpu symbols must be unique whether static or not
397 2. percpu variables can't be defined inside a function
399 To ensure that generic code follows the above rules, this
400 option forces all percpu variables to be defined as weak.
402 endmenu # "Compiler options"
405 bool "Magic SysRq key"
408 If you say Y here, you will have some control over the system even
409 if the system crashes for example during kernel debugging (e.g., you
410 will be able to flush the buffer cache to disk, reboot the system
411 immediately or dump some status information). This is accomplished
412 by pressing various keys while holding SysRq (Alt+PrintScreen). It
413 also works on a serial console (on PC hardware at least), if you
414 send a BREAK and then within 5 seconds a command keypress. The
415 keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
416 Don't say Y unless you really know what this hack does.
418 config MAGIC_SYSRQ_DEFAULT_ENABLE
419 hex "Enable magic SysRq key functions by default"
420 depends on MAGIC_SYSRQ
423 Specifies which SysRq key functions are enabled by default.
424 This may be set to 1 or 0 to enable or disable them all, or
425 to a bitmask as described in Documentation/admin-guide/sysrq.rst.
427 config MAGIC_SYSRQ_SERIAL
428 bool "Enable magic SysRq key over serial"
429 depends on MAGIC_SYSRQ
432 Many embedded boards have a disconnected TTL level serial which can
433 generate some garbage that can lead to spurious false sysrq detects.
434 This option allows you to decide whether you want to enable the
438 bool "Kernel debugging"
440 Say Y here if you are developing drivers or trying to debug and
441 identify kernel problems.
444 bool "Miscellaneous debug code"
446 depends on DEBUG_KERNEL
448 Say Y here if you need to enable miscellaneous debug code that should
449 be under a more specific debug option but isn't.
452 menu "Memory Debugging"
454 source "mm/Kconfig.debug"
457 bool "Debug object operations"
458 depends on DEBUG_KERNEL
460 If you say Y here, additional code will be inserted into the
461 kernel to track the life time of various objects and validate
462 the operations on those objects.
464 config DEBUG_OBJECTS_SELFTEST
465 bool "Debug objects selftest"
466 depends on DEBUG_OBJECTS
468 This enables the selftest of the object debug code.
470 config DEBUG_OBJECTS_FREE
471 bool "Debug objects in freed memory"
472 depends on DEBUG_OBJECTS
474 This enables checks whether a k/v free operation frees an area
475 which contains an object which has not been deactivated
476 properly. This can make kmalloc/kfree-intensive workloads
479 config DEBUG_OBJECTS_TIMERS
480 bool "Debug timer objects"
481 depends on DEBUG_OBJECTS
483 If you say Y here, additional code will be inserted into the
484 timer routines to track the life time of timer objects and
485 validate the timer operations.
487 config DEBUG_OBJECTS_WORK
488 bool "Debug work objects"
489 depends on DEBUG_OBJECTS
491 If you say Y here, additional code will be inserted into the
492 work queue routines to track the life time of work objects and
493 validate the work operations.
495 config DEBUG_OBJECTS_RCU_HEAD
496 bool "Debug RCU callbacks objects"
497 depends on DEBUG_OBJECTS
499 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
501 config DEBUG_OBJECTS_PERCPU_COUNTER
502 bool "Debug percpu counter objects"
503 depends on DEBUG_OBJECTS
505 If you say Y here, additional code will be inserted into the
506 percpu counter routines to track the life time of percpu counter
507 objects and validate the percpu counter operations.
509 config DEBUG_OBJECTS_ENABLE_DEFAULT
510 int "debug_objects bootup default value (0-1)"
513 depends on DEBUG_OBJECTS
515 Debug objects boot parameter default value
518 bool "Debug slab memory allocations"
519 depends on DEBUG_KERNEL && SLAB
521 Say Y here to have the kernel do limited verification on memory
522 allocation as well as poisoning memory on free to catch use of freed
523 memory. This can make kmalloc/kfree-intensive workloads much slower.
526 bool "SLUB debugging on by default"
527 depends on SLUB && SLUB_DEBUG
530 Boot with debugging on by default. SLUB boots by default with
531 the runtime debug capabilities switched off. Enabling this is
532 equivalent to specifying the "slub_debug" parameter on boot.
533 There is no support for more fine grained debug control like
534 possible with slub_debug=xxx. SLUB debugging may be switched
535 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
540 bool "Enable SLUB performance statistics"
541 depends on SLUB && SYSFS
543 SLUB statistics are useful to debug SLUBs allocation behavior in
544 order find ways to optimize the allocator. This should never be
545 enabled for production use since keeping statistics slows down
546 the allocator by a few percentage points. The slabinfo command
547 supports the determination of the most active slabs to figure
548 out which slabs are relevant to a particular load.
549 Try running: slabinfo -DA
551 config HAVE_DEBUG_KMEMLEAK
554 config DEBUG_KMEMLEAK
555 bool "Kernel memory leak detector"
556 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
558 select STACKTRACE if STACKTRACE_SUPPORT
562 Say Y here if you want to enable the memory leak
563 detector. The memory allocation/freeing is traced in a way
564 similar to the Boehm's conservative garbage collector, the
565 difference being that the orphan objects are not freed but
566 only shown in /sys/kernel/debug/kmemleak. Enabling this
567 feature will introduce an overhead to memory
568 allocations. See Documentation/dev-tools/kmemleak.rst for more
571 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
572 of finding leaks due to the slab objects poisoning.
574 In order to access the kmemleak file, debugfs needs to be
575 mounted (usually at /sys/kernel/debug).
577 config DEBUG_KMEMLEAK_MEM_POOL_SIZE
578 int "Kmemleak memory pool size"
579 depends on DEBUG_KMEMLEAK
583 Kmemleak must track all the memory allocations to avoid
584 reporting false positives. Since memory may be allocated or
585 freed before kmemleak is fully initialised, use a static pool
586 of metadata objects to track such callbacks. After kmemleak is
587 fully initialised, this memory pool acts as an emergency one
588 if slab allocations fail.
590 config DEBUG_KMEMLEAK_TEST
591 tristate "Simple test for the kernel memory leak detector"
592 depends on DEBUG_KMEMLEAK && m
594 This option enables a module that explicitly leaks memory.
598 config DEBUG_KMEMLEAK_DEFAULT_OFF
599 bool "Default kmemleak to off"
600 depends on DEBUG_KMEMLEAK
602 Say Y here to disable kmemleak by default. It can then be enabled
603 on the command line via kmemleak=on.
605 config DEBUG_KMEMLEAK_AUTO_SCAN
606 bool "Enable kmemleak auto scan thread on boot up"
608 depends on DEBUG_KMEMLEAK
610 Depending on the cpu, kmemleak scan may be cpu intensive and can
611 stall user tasks at times. This option enables/disables automatic
612 kmemleak scan at boot up.
614 Say N here to disable kmemleak auto scan thread to stop automatic
615 scanning. Disabling this option disables automatic reporting of
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 An architecture should select this when it can successfully
765 build and run with CONFIG_KCOV. This typically requires
766 disabling instrumentation for some early boot code.
768 config CC_HAS_SANCOV_TRACE_PC
769 def_bool $(cc-option,-fsanitize-coverage=trace-pc)
772 bool "Code coverage for fuzzing"
773 depends on ARCH_HAS_KCOV
774 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
776 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
778 KCOV exposes kernel code coverage information in a form suitable
779 for coverage-guided fuzzing (randomized testing).
781 If RANDOMIZE_BASE is enabled, PC values will not be stable across
782 different machines and across reboots. If you need stable PC values,
783 disable RANDOMIZE_BASE.
785 For more details, see Documentation/dev-tools/kcov.rst.
787 config KCOV_ENABLE_COMPARISONS
788 bool "Enable comparison operands collection by KCOV"
790 depends on $(cc-option,-fsanitize-coverage=trace-cmp)
792 KCOV also exposes operands of every comparison in the instrumented
793 code along with operand sizes and PCs of the comparison instructions.
794 These operands can be used by fuzzing engines to improve the quality
797 config KCOV_INSTRUMENT_ALL
798 bool "Instrument all code by default"
802 If you are doing generic system call fuzzing (like e.g. syzkaller),
803 then you will want to instrument the whole kernel and you should
804 say y here. If you are doing more targeted fuzzing (like e.g.
805 filesystem fuzzing with AFL) then you will want to enable coverage
806 for more specific subsets of files, and should say n here.
809 bool "Debug shared IRQ handlers"
810 depends on DEBUG_KERNEL
812 Enable this to generate a spurious interrupt as soon as a shared
813 interrupt handler is registered, and just before one is deregistered.
814 Drivers ought to be able to handle interrupts coming in at those
815 points; some don't and need to be caught.
817 menu "Debug Lockups and Hangs"
819 config LOCKUP_DETECTOR
822 config SOFTLOCKUP_DETECTOR
823 bool "Detect Soft Lockups"
824 depends on DEBUG_KERNEL && !S390
825 select LOCKUP_DETECTOR
827 Say Y here to enable the kernel to act as a watchdog to detect
830 Softlockups are bugs that cause the kernel to loop in kernel
831 mode for more than 20 seconds, without giving other tasks a
832 chance to run. The current stack trace is displayed upon
833 detection and the system will stay locked up.
835 config BOOTPARAM_SOFTLOCKUP_PANIC
836 bool "Panic (Reboot) On Soft Lockups"
837 depends on SOFTLOCKUP_DETECTOR
839 Say Y here to enable the kernel to panic on "soft lockups",
840 which are bugs that cause the kernel to loop in kernel
841 mode for more than 20 seconds (configurable using the watchdog_thresh
842 sysctl), without giving other tasks a chance to run.
844 The panic can be used in combination with panic_timeout,
845 to cause the system to reboot automatically after a
846 lockup has been detected. This feature is useful for
847 high-availability systems that have uptime guarantees and
848 where a lockup must be resolved ASAP.
852 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
854 depends on SOFTLOCKUP_DETECTOR
856 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
857 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
859 config HARDLOCKUP_DETECTOR_PERF
861 select SOFTLOCKUP_DETECTOR
864 # Enables a timestamp based low pass filter to compensate for perf based
865 # hard lockup detection which runs too fast due to turbo modes.
867 config HARDLOCKUP_CHECK_TIMESTAMP
871 # arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard
872 # lockup detector rather than the perf based detector.
874 config HARDLOCKUP_DETECTOR
875 bool "Detect Hard Lockups"
876 depends on DEBUG_KERNEL && !S390
877 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH
878 select LOCKUP_DETECTOR
879 select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF
880 select HARDLOCKUP_DETECTOR_ARCH if HAVE_HARDLOCKUP_DETECTOR_ARCH
882 Say Y here to enable the kernel to act as a watchdog to detect
885 Hardlockups are bugs that cause the CPU to loop in kernel mode
886 for more than 10 seconds, without letting other interrupts have a
887 chance to run. The current stack trace is displayed upon detection
888 and the system will stay locked up.
890 config BOOTPARAM_HARDLOCKUP_PANIC
891 bool "Panic (Reboot) On Hard Lockups"
892 depends on HARDLOCKUP_DETECTOR
894 Say Y here to enable the kernel to panic on "hard lockups",
895 which are bugs that cause the kernel to loop in kernel
896 mode with interrupts disabled for more than 10 seconds (configurable
897 using the watchdog_thresh sysctl).
901 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
903 depends on HARDLOCKUP_DETECTOR
905 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
906 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
908 config DETECT_HUNG_TASK
909 bool "Detect Hung Tasks"
910 depends on DEBUG_KERNEL
911 default SOFTLOCKUP_DETECTOR
913 Say Y here to enable the kernel to detect "hung tasks",
914 which are bugs that cause the task to be stuck in
915 uninterruptible "D" state indefinitely.
917 When a hung task is detected, the kernel will print the
918 current stack trace (which you should report), but the
919 task will stay in uninterruptible state. If lockdep is
920 enabled then all held locks will also be reported. This
921 feature has negligible overhead.
923 config DEFAULT_HUNG_TASK_TIMEOUT
924 int "Default timeout for hung task detection (in seconds)"
925 depends on DETECT_HUNG_TASK
928 This option controls the default timeout (in seconds) used
929 to determine when a task has become non-responsive and should
932 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
933 sysctl or by writing a value to
934 /proc/sys/kernel/hung_task_timeout_secs.
936 A timeout of 0 disables the check. The default is two minutes.
937 Keeping the default should be fine in most cases.
939 config BOOTPARAM_HUNG_TASK_PANIC
940 bool "Panic (Reboot) On Hung Tasks"
941 depends on DETECT_HUNG_TASK
943 Say Y here to enable the kernel to panic on "hung tasks",
944 which are bugs that cause the kernel to leave a task stuck
945 in uninterruptible "D" state.
947 The panic can be used in combination with panic_timeout,
948 to cause the system to reboot automatically after a
949 hung task has been detected. This feature is useful for
950 high-availability systems that have uptime guarantees and
951 where a hung tasks must be resolved ASAP.
955 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
957 depends on DETECT_HUNG_TASK
959 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
960 default 1 if BOOTPARAM_HUNG_TASK_PANIC
963 bool "Detect Workqueue Stalls"
964 depends on DEBUG_KERNEL
966 Say Y here to enable stall detection on workqueues. If a
967 worker pool doesn't make forward progress on a pending work
968 item for over a given amount of time, 30s by default, a
969 warning message is printed along with dump of workqueue
970 state. This can be configured through kernel parameter
971 "workqueue.watchdog_thresh" and its sysfs counterpart.
973 endmenu # "Debug lockups and hangs"
978 Say Y here to enable the kernel to panic when it oopses. This
979 has the same effect as setting oops=panic on the kernel command
982 This feature is useful to ensure that the kernel does not do
983 anything erroneous after an oops which could result in data
984 corruption or other issues.
988 config PANIC_ON_OOPS_VALUE
991 default 0 if !PANIC_ON_OOPS
992 default 1 if PANIC_ON_OOPS
998 Set the timeout value (in seconds) until a reboot occurs when the
999 the kernel panics. If n = 0, then we wait forever. A timeout
1000 value n > 0 will wait n seconds before rebooting, while a timeout
1001 value n < 0 will reboot immediately.
1004 bool "Collect scheduler debugging info"
1005 depends on DEBUG_KERNEL && PROC_FS
1008 If you say Y here, the /proc/sched_debug file will be provided
1009 that can help debug the scheduler. The runtime overhead of this
1017 bool "Collect scheduler statistics"
1018 depends on DEBUG_KERNEL && PROC_FS
1021 If you say Y here, additional code will be inserted into the
1022 scheduler and related routines to collect statistics about
1023 scheduler behavior and provide them in /proc/schedstat. These
1024 stats may be useful for both tuning and debugging the scheduler
1025 If you aren't debugging the scheduler or trying to tune a specific
1026 application, you can say N to avoid the very slight overhead
1029 config SCHED_STACK_END_CHECK
1030 bool "Detect stack corruption on calls to schedule()"
1031 depends on DEBUG_KERNEL
1034 This option checks for a stack overrun on calls to schedule().
1035 If the stack end location is found to be over written always panic as
1036 the content of the corrupted region can no longer be trusted.
1037 This is to ensure no erroneous behaviour occurs which could result in
1038 data corruption or a sporadic crash at a later stage once the region
1039 is examined. The runtime overhead introduced is minimal.
1041 config DEBUG_TIMEKEEPING
1042 bool "Enable extra timekeeping sanity checking"
1044 This option will enable additional timekeeping sanity checks
1045 which may be helpful when diagnosing issues where timekeeping
1046 problems are suspected.
1048 This may include checks in the timekeeping hotpaths, so this
1049 option may have a (very small) performance impact to some
1054 config DEBUG_PREEMPT
1055 bool "Debug preemptible kernel"
1056 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
1059 If you say Y here then the kernel will use a debug variant of the
1060 commonly used smp_processor_id() function and will print warnings
1061 if kernel code uses it in a preemption-unsafe way. Also, the kernel
1062 will detect preemption count underflows.
1064 menu "Lock Debugging (spinlocks, mutexes, etc...)"
1066 config LOCK_DEBUGGING_SUPPORT
1068 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1071 config PROVE_LOCKING
1072 bool "Lock debugging: prove locking correctness"
1073 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1075 select DEBUG_SPINLOCK
1076 select DEBUG_MUTEXES
1077 select DEBUG_RT_MUTEXES if RT_MUTEXES
1079 select DEBUG_WW_MUTEX_SLOWPATH
1080 select DEBUG_LOCK_ALLOC
1081 select TRACE_IRQFLAGS
1084 This feature enables the kernel to prove that all locking
1085 that occurs in the kernel runtime is mathematically
1086 correct: that under no circumstance could an arbitrary (and
1087 not yet triggered) combination of observed locking
1088 sequences (on an arbitrary number of CPUs, running an
1089 arbitrary number of tasks and interrupt contexts) cause a
1092 In short, this feature enables the kernel to report locking
1093 related deadlocks before they actually occur.
1095 The proof does not depend on how hard and complex a
1096 deadlock scenario would be to trigger: how many
1097 participant CPUs, tasks and irq-contexts would be needed
1098 for it to trigger. The proof also does not depend on
1099 timing: if a race and a resulting deadlock is possible
1100 theoretically (no matter how unlikely the race scenario
1101 is), it will be proven so and will immediately be
1102 reported by the kernel (once the event is observed that
1103 makes the deadlock theoretically possible).
1105 If a deadlock is impossible (i.e. the locking rules, as
1106 observed by the kernel, are mathematically correct), the
1107 kernel reports nothing.
1109 NOTE: this feature can also be enabled for rwlocks, mutexes
1110 and rwsems - in which case all dependencies between these
1111 different locking variants are observed and mapped too, and
1112 the proof of observed correctness is also maintained for an
1113 arbitrary combination of these separate locking variants.
1115 For more details, see Documentation/locking/lockdep-design.rst.
1118 bool "Lock usage statistics"
1119 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1121 select DEBUG_SPINLOCK
1122 select DEBUG_MUTEXES
1123 select DEBUG_RT_MUTEXES if RT_MUTEXES
1124 select DEBUG_LOCK_ALLOC
1127 This feature enables tracking lock contention points
1129 For more details, see Documentation/locking/lockstat.rst
1131 This also enables lock events required by "perf lock",
1133 If you want to use "perf lock", you also need to turn on
1134 CONFIG_EVENT_TRACING.
1136 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1137 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1139 config DEBUG_RT_MUTEXES
1140 bool "RT Mutex debugging, deadlock detection"
1141 depends on DEBUG_KERNEL && RT_MUTEXES
1143 This allows rt mutex semantics violations and rt mutex related
1144 deadlocks (lockups) to be detected and reported automatically.
1146 config DEBUG_SPINLOCK
1147 bool "Spinlock and rw-lock debugging: basic checks"
1148 depends on DEBUG_KERNEL
1149 select UNINLINE_SPIN_UNLOCK
1151 Say Y here and build SMP to catch missing spinlock initialization
1152 and certain other kinds of spinlock errors commonly made. This is
1153 best used in conjunction with the NMI watchdog so that spinlock
1154 deadlocks are also debuggable.
1156 config DEBUG_MUTEXES
1157 bool "Mutex debugging: basic checks"
1158 depends on DEBUG_KERNEL
1160 This feature allows mutex semantics violations to be detected and
1163 config DEBUG_WW_MUTEX_SLOWPATH
1164 bool "Wait/wound mutex debugging: Slowpath testing"
1165 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1166 select DEBUG_LOCK_ALLOC
1167 select DEBUG_SPINLOCK
1168 select DEBUG_MUTEXES
1170 This feature enables slowpath testing for w/w mutex users by
1171 injecting additional -EDEADLK wound/backoff cases. Together with
1172 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1173 will test all possible w/w mutex interface abuse with the
1174 exception of simply not acquiring all the required locks.
1175 Note that this feature can introduce significant overhead, so
1176 it really should not be enabled in a production or distro kernel,
1177 even a debug kernel. If you are a driver writer, enable it. If
1178 you are a distro, do not.
1181 bool "RW Semaphore debugging: basic checks"
1182 depends on DEBUG_KERNEL
1184 This debugging feature allows mismatched rw semaphore locks
1185 and unlocks to be detected and reported.
1187 config DEBUG_LOCK_ALLOC
1188 bool "Lock debugging: detect incorrect freeing of live locks"
1189 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1190 select DEBUG_SPINLOCK
1191 select DEBUG_MUTEXES
1192 select DEBUG_RT_MUTEXES if RT_MUTEXES
1195 This feature will check whether any held lock (spinlock, rwlock,
1196 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1197 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1198 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1199 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1200 held during task exit.
1204 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1206 select FRAME_POINTER if !MIPS && !PPC && !ARM && !S390 && !MICROBLAZE && !ARC && !X86
1210 config LOCKDEP_SMALL
1213 config DEBUG_LOCKDEP
1214 bool "Lock dependency engine debugging"
1215 depends on DEBUG_KERNEL && LOCKDEP
1217 If you say Y here, the lock dependency engine will do
1218 additional runtime checks to debug itself, at the price
1219 of more runtime overhead.
1221 config DEBUG_ATOMIC_SLEEP
1222 bool "Sleep inside atomic section checking"
1223 select PREEMPT_COUNT
1224 depends on DEBUG_KERNEL
1225 depends on !ARCH_NO_PREEMPT
1227 If you say Y here, various routines which may sleep will become very
1228 noisy if they are called inside atomic sections: when a spinlock is
1229 held, inside an rcu read side critical section, inside preempt disabled
1230 sections, inside an interrupt, etc...
1232 config DEBUG_LOCKING_API_SELFTESTS
1233 bool "Locking API boot-time self-tests"
1234 depends on DEBUG_KERNEL
1236 Say Y here if you want the kernel to run a short self-test during
1237 bootup. The self-test checks whether common types of locking bugs
1238 are detected by debugging mechanisms or not. (if you disable
1239 lock debugging then those bugs wont be detected of course.)
1240 The following locking APIs are covered: spinlocks, rwlocks,
1243 config LOCK_TORTURE_TEST
1244 tristate "torture tests for locking"
1245 depends on DEBUG_KERNEL
1248 This option provides a kernel module that runs torture tests
1249 on kernel locking primitives. The kernel module may be built
1250 after the fact on the running kernel to be tested, if desired.
1252 Say Y here if you want kernel locking-primitive torture tests
1253 to be built into the kernel.
1254 Say M if you want these torture tests to build as a module.
1255 Say N if you are unsure.
1257 config WW_MUTEX_SELFTEST
1258 tristate "Wait/wound mutex selftests"
1260 This option provides a kernel module that runs tests on the
1261 on the struct ww_mutex locking API.
1263 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1264 with this test harness.
1266 Say M if you want these self tests to build as a module.
1267 Say N if you are unsure.
1269 endmenu # lock debugging
1271 config TRACE_IRQFLAGS
1274 Enables hooks to interrupt enabling and disabling for
1275 either tracing or lock debugging.
1278 bool "Stack backtrace support"
1279 depends on STACKTRACE_SUPPORT
1281 This option causes the kernel to create a /proc/pid/stack for
1282 every process, showing its current stack trace.
1283 It is also used by various kernel debugging features that require
1284 stack trace generation.
1286 config WARN_ALL_UNSEEDED_RANDOM
1287 bool "Warn for all uses of unseeded randomness"
1290 Some parts of the kernel contain bugs relating to their use of
1291 cryptographically secure random numbers before it's actually possible
1292 to generate those numbers securely. This setting ensures that these
1293 flaws don't go unnoticed, by enabling a message, should this ever
1294 occur. This will allow people with obscure setups to know when things
1295 are going wrong, so that they might contact developers about fixing
1298 Unfortunately, on some models of some architectures getting
1299 a fully seeded CRNG is extremely difficult, and so this can
1300 result in dmesg getting spammed for a surprisingly long
1301 time. This is really bad from a security perspective, and
1302 so architecture maintainers really need to do what they can
1303 to get the CRNG seeded sooner after the system is booted.
1304 However, since users cannot do anything actionable to
1305 address this, by default the kernel will issue only a single
1306 warning for the first use of unseeded randomness.
1308 Say Y here if you want to receive warnings for all uses of
1309 unseeded randomness. This will be of use primarily for
1310 those developers interested in improving the security of
1311 Linux kernels running on their architecture (or
1314 config DEBUG_KOBJECT
1315 bool "kobject debugging"
1316 depends on DEBUG_KERNEL
1318 If you say Y here, some extra kobject debugging messages will be sent
1321 config DEBUG_KOBJECT_RELEASE
1322 bool "kobject release debugging"
1323 depends on DEBUG_OBJECTS_TIMERS
1325 kobjects are reference counted objects. This means that their
1326 last reference count put is not predictable, and the kobject can
1327 live on past the point at which a driver decides to drop it's
1328 initial reference to the kobject gained on allocation. An
1329 example of this would be a struct device which has just been
1332 However, some buggy drivers assume that after such an operation,
1333 the memory backing the kobject can be immediately freed. This
1334 goes completely against the principles of a refcounted object.
1336 If you say Y here, the kernel will delay the release of kobjects
1337 on the last reference count to improve the visibility of this
1338 kind of kobject release bug.
1340 config HAVE_DEBUG_BUGVERBOSE
1343 config DEBUG_BUGVERBOSE
1344 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
1345 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
1348 Say Y here to make BUG() panics output the file name and line number
1349 of the BUG call as well as the EIP and oops trace. This aids
1350 debugging but costs about 70-100K of memory.
1353 bool "Debug linked list manipulation"
1354 depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION
1356 Enable this to turn on extended checks in the linked-list
1362 bool "Debug priority linked list manipulation"
1363 depends on DEBUG_KERNEL
1365 Enable this to turn on extended checks in the priority-ordered
1366 linked-list (plist) walking routines. This checks the entire
1367 list multiple times during each manipulation.
1372 bool "Debug SG table operations"
1373 depends on DEBUG_KERNEL
1375 Enable this to turn on checks on scatter-gather tables. This can
1376 help find problems with drivers that do not properly initialize
1381 config DEBUG_NOTIFIERS
1382 bool "Debug notifier call chains"
1383 depends on DEBUG_KERNEL
1385 Enable this to turn on sanity checking for notifier call chains.
1386 This is most useful for kernel developers to make sure that
1387 modules properly unregister themselves from notifier chains.
1388 This is a relatively cheap check but if you care about maximum
1391 config DEBUG_CREDENTIALS
1392 bool "Debug credential management"
1393 depends on DEBUG_KERNEL
1395 Enable this to turn on some debug checking for credential
1396 management. The additional code keeps track of the number of
1397 pointers from task_structs to any given cred struct, and checks to
1398 see that this number never exceeds the usage count of the cred
1401 Furthermore, if SELinux is enabled, this also checks that the
1402 security pointer in the cred struct is never seen to be invalid.
1406 source "kernel/rcu/Kconfig.debug"
1408 config DEBUG_WQ_FORCE_RR_CPU
1409 bool "Force round-robin CPU selection for unbound work items"
1410 depends on DEBUG_KERNEL
1413 Workqueue used to implicitly guarantee that work items queued
1414 without explicit CPU specified are put on the local CPU. This
1415 guarantee is no longer true and while local CPU is still
1416 preferred work items may be put on foreign CPUs. Kernel
1417 parameter "workqueue.debug_force_rr_cpu" is added to force
1418 round-robin CPU selection to flush out usages which depend on the
1419 now broken guarantee. This config option enables the debug
1420 feature by default. When enabled, memory and cache locality will
1423 config DEBUG_BLOCK_EXT_DEVT
1424 bool "Force extended block device numbers and spread them"
1425 depends on DEBUG_KERNEL
1429 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1430 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1431 YOU ARE DOING. Distros, please enable this and fix whatever
1434 Conventionally, block device numbers are allocated from
1435 predetermined contiguous area. However, extended block area
1436 may introduce non-contiguous block device numbers. This
1437 option forces most block device numbers to be allocated from
1438 the extended space and spreads them to discover kernel or
1439 userland code paths which assume predetermined contiguous
1440 device number allocation.
1442 Note that turning on this debug option shuffles all the
1443 device numbers for all IDE and SCSI devices including libata
1444 ones, so root partition specified using device number
1445 directly (via rdev or root=MAJ:MIN) won't work anymore.
1446 Textual device names (root=/dev/sdXn) will continue to work.
1448 Say N if you are unsure.
1450 config CPU_HOTPLUG_STATE_CONTROL
1451 bool "Enable CPU hotplug state control"
1452 depends on DEBUG_KERNEL
1453 depends on HOTPLUG_CPU
1456 Allows to write steps between "offline" and "online" to the CPUs
1457 sysfs target file so states can be stepped granular. This is a debug
1458 option for now as the hotplug machinery cannot be stopped and
1459 restarted at arbitrary points yet.
1461 Say N if your are unsure.
1463 config NOTIFIER_ERROR_INJECTION
1464 tristate "Notifier error injection"
1465 depends on DEBUG_KERNEL
1468 This option provides the ability to inject artificial errors to
1469 specified notifier chain callbacks. It is useful to test the error
1470 handling of notifier call chain failures.
1474 config PM_NOTIFIER_ERROR_INJECT
1475 tristate "PM notifier error injection module"
1476 depends on PM && NOTIFIER_ERROR_INJECTION
1477 default m if PM_DEBUG
1479 This option provides the ability to inject artificial errors to
1480 PM notifier chain callbacks. It is controlled through debugfs
1481 interface /sys/kernel/debug/notifier-error-inject/pm
1483 If the notifier call chain should be failed with some events
1484 notified, write the error code to "actions/<notifier event>/error".
1486 Example: Inject PM suspend error (-12 = -ENOMEM)
1488 # cd /sys/kernel/debug/notifier-error-inject/pm/
1489 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1490 # echo mem > /sys/power/state
1491 bash: echo: write error: Cannot allocate memory
1493 To compile this code as a module, choose M here: the module will
1494 be called pm-notifier-error-inject.
1498 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1499 tristate "OF reconfig notifier error injection module"
1500 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1502 This option provides the ability to inject artificial errors to
1503 OF reconfig notifier chain callbacks. It is controlled
1504 through debugfs interface under
1505 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1507 If the notifier call chain should be failed with some events
1508 notified, write the error code to "actions/<notifier event>/error".
1510 To compile this code as a module, choose M here: the module will
1511 be called of-reconfig-notifier-error-inject.
1515 config NETDEV_NOTIFIER_ERROR_INJECT
1516 tristate "Netdev notifier error injection module"
1517 depends on NET && NOTIFIER_ERROR_INJECTION
1519 This option provides the ability to inject artificial errors to
1520 netdevice notifier chain callbacks. It is controlled through debugfs
1521 interface /sys/kernel/debug/notifier-error-inject/netdev
1523 If the notifier call chain should be failed with some events
1524 notified, write the error code to "actions/<notifier event>/error".
1526 Example: Inject netdevice mtu change error (-22 = -EINVAL)
1528 # cd /sys/kernel/debug/notifier-error-inject/netdev
1529 # echo -22 > actions/NETDEV_CHANGEMTU/error
1530 # ip link set eth0 mtu 1024
1531 RTNETLINK answers: Invalid argument
1533 To compile this code as a module, choose M here: the module will
1534 be called netdev-notifier-error-inject.
1538 config FUNCTION_ERROR_INJECTION
1540 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
1542 config FAULT_INJECTION
1543 bool "Fault-injection framework"
1544 depends on DEBUG_KERNEL
1546 Provide fault-injection framework.
1547 For more details, see Documentation/fault-injection/.
1550 bool "Fault-injection capability for kmalloc"
1551 depends on FAULT_INJECTION
1552 depends on SLAB || SLUB
1554 Provide fault-injection capability for kmalloc.
1556 config FAIL_PAGE_ALLOC
1557 bool "Fault-injection capabilitiy for alloc_pages()"
1558 depends on FAULT_INJECTION
1560 Provide fault-injection capability for alloc_pages().
1562 config FAIL_MAKE_REQUEST
1563 bool "Fault-injection capability for disk IO"
1564 depends on FAULT_INJECTION && BLOCK
1566 Provide fault-injection capability for disk IO.
1568 config FAIL_IO_TIMEOUT
1569 bool "Fault-injection capability for faking disk interrupts"
1570 depends on FAULT_INJECTION && BLOCK
1572 Provide fault-injection capability on end IO handling. This
1573 will make the block layer "forget" an interrupt as configured,
1574 thus exercising the error handling.
1576 Only works with drivers that use the generic timeout handling,
1577 for others it wont do anything.
1580 bool "Fault-injection capability for futexes"
1582 depends on FAULT_INJECTION && FUTEX
1584 Provide fault-injection capability for futexes.
1586 config FAULT_INJECTION_DEBUG_FS
1587 bool "Debugfs entries for fault-injection capabilities"
1588 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1590 Enable configuration of fault-injection capabilities via debugfs.
1592 config FAIL_FUNCTION
1593 bool "Fault-injection capability for functions"
1594 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
1596 Provide function-based fault-injection capability.
1597 This will allow you to override a specific function with a return
1598 with given return value. As a result, function caller will see
1599 an error value and have to handle it. This is useful to test the
1600 error handling in various subsystems.
1602 config FAIL_MMC_REQUEST
1603 bool "Fault-injection capability for MMC IO"
1604 depends on FAULT_INJECTION_DEBUG_FS && MMC
1606 Provide fault-injection capability for MMC IO.
1607 This will make the mmc core return data errors. This is
1608 useful to test the error handling in the mmc block device
1609 and to test how the mmc host driver handles retries from
1612 config FAULT_INJECTION_STACKTRACE_FILTER
1613 bool "stacktrace filter for fault-injection capabilities"
1614 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1617 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86
1619 Provide stacktrace filter for fault-injection capabilities
1622 bool "Latency measuring infrastructure"
1623 depends on DEBUG_KERNEL
1624 depends on STACKTRACE_SUPPORT
1626 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86
1633 Enable this option if you want to use the LatencyTOP tool
1634 to find out which userspace is blocking on what kernel operations.
1636 source "kernel/trace/Kconfig"
1638 config PROVIDE_OHCI1394_DMA_INIT
1639 bool "Remote debugging over FireWire early on boot"
1640 depends on PCI && X86
1642 If you want to debug problems which hang or crash the kernel early
1643 on boot and the crashing machine has a FireWire port, you can use
1644 this feature to remotely access the memory of the crashed machine
1645 over FireWire. This employs remote DMA as part of the OHCI1394
1646 specification which is now the standard for FireWire controllers.
1648 With remote DMA, you can monitor the printk buffer remotely using
1649 firescope and access all memory below 4GB using fireproxy from gdb.
1650 Even controlling a kernel debugger is possible using remote DMA.
1654 If ohci1394_dma=early is used as boot parameter, it will initialize
1655 all OHCI1394 controllers which are found in the PCI config space.
1657 As all changes to the FireWire bus such as enabling and disabling
1658 devices cause a bus reset and thereby disable remote DMA for all
1659 devices, be sure to have the cable plugged and FireWire enabled on
1660 the debugging host before booting the debug target for debugging.
1662 This code (~1k) is freed after boot. By then, the firewire stack
1663 in charge of the OHCI-1394 controllers should be used instead.
1665 See Documentation/debugging-via-ohci1394.txt for more information.
1667 menuconfig RUNTIME_TESTING_MENU
1668 bool "Runtime Testing"
1671 if RUNTIME_TESTING_MENU
1674 tristate "Linux Kernel Dump Test Tool Module"
1677 This module enables testing of the different dumping mechanisms by
1678 inducing system failures at predefined crash points.
1679 If you don't need it: say N
1680 Choose M here to compile this code as a module. The module will be
1683 Documentation on how to use the module can be found in
1684 Documentation/fault-injection/provoke-crashes.rst
1686 config TEST_LIST_SORT
1687 tristate "Linked list sorting test"
1688 depends on DEBUG_KERNEL || m
1690 Enable this to turn on 'list_sort()' function test. This test is
1691 executed only once during system boot (so affects only boot time),
1692 or at module load time.
1697 tristate "Array-based sort test"
1698 depends on DEBUG_KERNEL || m
1700 This option enables the self-test function of 'sort()' at boot,
1701 or at module load time.
1705 config KPROBES_SANITY_TEST
1706 bool "Kprobes sanity tests"
1707 depends on DEBUG_KERNEL
1710 This option provides for testing basic kprobes functionality on
1711 boot. Samples of kprobe 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
1720 This option provides a kernel module that can be used to test
1721 the kernel stack backtrace code. This option is not useful
1722 for distributions or general kernels, but only for kernel
1723 developers working on architecture code.
1725 Note that if you want to also test saved backtraces, you will
1726 have to enable STACKTRACE as well.
1728 Say N if you are unsure.
1731 tristate "Red-Black tree test"
1732 depends on DEBUG_KERNEL
1734 A benchmark measuring the performance of the rbtree library.
1735 Also includes rbtree invariant checks.
1737 config REED_SOLOMON_TEST
1738 tristate "Reed-Solomon library test"
1739 depends on DEBUG_KERNEL || m
1741 select REED_SOLOMON_ENC16
1742 select REED_SOLOMON_DEC16
1744 This option enables the self-test function of rslib at boot,
1745 or at module load time.
1749 config INTERVAL_TREE_TEST
1750 tristate "Interval tree test"
1751 depends on DEBUG_KERNEL
1752 select INTERVAL_TREE
1754 A benchmark measuring the performance of the interval tree library
1757 tristate "Per cpu operations test"
1758 depends on m && DEBUG_KERNEL
1760 Enable this option to build test module which validates per-cpu
1765 config ATOMIC64_SELFTEST
1766 tristate "Perform an atomic64_t self-test"
1768 Enable this option to test the atomic64_t functions at boot or
1769 at module load time.
1773 config ASYNC_RAID6_TEST
1774 tristate "Self test for hardware accelerated raid6 recovery"
1775 depends on ASYNC_RAID6_RECOV
1778 This is a one-shot self test that permutes through the
1779 recovery of all the possible two disk failure scenarios for a
1780 N-disk array. Recovery is performed with the asynchronous
1781 raid6 recovery routines, and will optionally use an offload
1782 engine if one is available.
1787 tristate "Test functions located in the hexdump module at runtime"
1789 config TEST_STRING_HELPERS
1790 tristate "Test functions located in the string_helpers module at runtime"
1793 tristate "Test strscpy*() family of functions at runtime"
1796 tristate "Test kstrto*() family of functions at runtime"
1799 tristate "Test printf() family of functions at runtime"
1802 tristate "Test bitmap_*() family of functions at runtime"
1804 Enable this option to test the bitmap functions at boot.
1808 config TEST_BITFIELD
1809 tristate "Test bitfield functions at runtime"
1811 Enable this option to test the bitfield functions at boot.
1816 tristate "Test functions located in the uuid module at runtime"
1819 tristate "Test the XArray code at runtime"
1821 config TEST_OVERFLOW
1822 tristate "Test check_*_overflow() functions at runtime"
1824 config TEST_RHASHTABLE
1825 tristate "Perform selftest on resizable hash table"
1827 Enable this option to test the rhashtable functions at boot.
1832 tristate "Perform selftest on hash functions"
1834 Enable this option to test the kernel's integer (<linux/hash.h>),
1835 string (<linux/stringhash.h>), and siphash (<linux/siphash.h>)
1836 hash functions on boot (or module load).
1838 This is intended to help people writing architecture-specific
1839 optimized versions. If unsure, say N.
1842 tristate "Perform selftest on IDA functions"
1845 tristate "Perform selftest on priority array manager"
1848 Enable this option to test priority array manager on boot
1853 config TEST_IRQ_TIMINGS
1854 bool "IRQ timings selftest"
1855 depends on IRQ_TIMINGS
1857 Enable this option to test the irq timings code on boot.
1862 tristate "Test module loading with 'hello world' module"
1865 This builds the "test_module" module that emits "Hello, world"
1866 on printk when loaded. It is designed to be used for basic
1867 evaluation of the module loading subsystem (for example when
1868 validating module verification). It lacks any extra dependencies,
1869 and will not normally be loaded by the system unless explicitly
1875 tristate "Test module for stress/performance analysis of vmalloc allocator"
1880 This builds the "test_vmalloc" module that should be used for
1881 stress and performance analysis. So, any new change for vmalloc
1882 subsystem can be evaluated from performance and stability point
1887 config TEST_USER_COPY
1888 tristate "Test user/kernel boundary protections"
1891 This builds the "test_user_copy" module that runs sanity checks
1892 on the copy_to/from_user infrastructure, making sure basic
1893 user/kernel boundary testing is working. If it fails to load,
1894 a regression has been detected in the user/kernel memory boundary
1900 tristate "Test BPF filter functionality"
1903 This builds the "test_bpf" module that runs various test vectors
1904 against the BPF interpreter or BPF JIT compiler depending on the
1905 current setting. This is in particular useful for BPF JIT compiler
1906 development, but also to run regression tests against changes in
1907 the interpreter code. It also enables test stubs for eBPF maps and
1908 verifier used by user space verifier testsuite.
1912 config TEST_BLACKHOLE_DEV
1913 tristate "Test blackhole netdev functionality"
1916 This builds the "test_blackhole_dev" module that validates the
1917 data path through this blackhole netdev.
1921 config FIND_BIT_BENCHMARK
1922 tristate "Test find_bit functions"
1924 This builds the "test_find_bit" module that measure find_*_bit()
1925 functions performance.
1929 config TEST_FIRMWARE
1930 tristate "Test firmware loading via userspace interface"
1931 depends on FW_LOADER
1933 This builds the "test_firmware" module that creates a userspace
1934 interface for testing firmware loading. This can be used to
1935 control the triggering of firmware loading without needing an
1936 actual firmware-using device. The contents can be rechecked by
1942 tristate "sysctl test driver"
1943 depends on PROC_SYSCTL
1945 This builds the "test_sysctl" module. This driver enables to test the
1946 proc sysctl interfaces available to drivers safely without affecting
1947 production knobs which might alter system functionality.
1952 tristate "udelay test driver"
1954 This builds the "udelay_test" module that helps to make sure
1955 that udelay() is working properly.
1959 config TEST_STATIC_KEYS
1960 tristate "Test static keys"
1963 Test the static key interfaces.
1968 tristate "kmod stress tester"
1970 depends on NETDEVICES && NET_CORE && INET # for TUN
1977 Test the kernel's module loading mechanism: kmod. kmod implements
1978 support to load modules using the Linux kernel's usermode helper.
1979 This test provides a series of tests against kmod.
1981 Although technically you can either build test_kmod as a module or
1982 into the kernel we disallow building it into the kernel since
1983 it stress tests request_module() and this will very likely cause
1984 some issues by taking over precious threads available from other
1985 module load requests, ultimately this could be fatal.
1989 tools/testing/selftests/kmod/kmod.sh --help
1993 config TEST_DEBUG_VIRTUAL
1994 tristate "Test CONFIG_DEBUG_VIRTUAL feature"
1995 depends on DEBUG_VIRTUAL
1997 Test the kernel's ability to detect incorrect calls to
1998 virt_to_phys() done against the non-linear part of the
1999 kernel's virtual address map.
2003 config TEST_MEMCAT_P
2004 tristate "Test memcat_p() helper function"
2006 Test the memcat_p() helper for correctly merging two
2007 pointer arrays together.
2011 config TEST_LIVEPATCH
2012 tristate "Test livepatching"
2014 depends on DYNAMIC_DEBUG
2015 depends on LIVEPATCH
2018 Test kernel livepatching features for correctness. The tests will
2019 load test modules that will be livepatched in various scenarios.
2021 To run all the livepatching tests:
2023 make -C tools/testing/selftests TARGETS=livepatch run_tests
2025 Alternatively, individual tests may be invoked:
2027 tools/testing/selftests/livepatch/test-callbacks.sh
2028 tools/testing/selftests/livepatch/test-livepatch.sh
2029 tools/testing/selftests/livepatch/test-shadow-vars.sh
2034 tristate "Perform selftest on object aggreration manager"
2038 Enable this option to test object aggregation manager on boot
2042 config TEST_STACKINIT
2043 tristate "Test level of stack variable initialization"
2045 Test if the kernel is zero-initializing stack variables and
2046 padding. Coverage is controlled by compiler flags,
2047 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2048 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2053 tristate "Test heap/page initialization"
2055 Test if the kernel is zero-initializing heap and page allocations.
2056 This can be useful to test init_on_alloc and init_on_free features.
2060 endif # RUNTIME_TESTING_MENU
2065 This option adds a kernel parameter 'memtest', which allows memtest
2067 memtest=0, mean disabled; -- default
2068 memtest=1, mean do 1 test pattern;
2070 memtest=17, mean do 17 test patterns.
2071 If you are unsure how to answer this question, answer N.
2073 config BUG_ON_DATA_CORRUPTION
2074 bool "Trigger a BUG when data corruption is detected"
2077 Select this option if the kernel should BUG when it encounters
2078 data corruption in kernel memory structures when they get checked
2083 source "samples/Kconfig"
2085 source "lib/Kconfig.kgdb"
2087 source "lib/Kconfig.ubsan"
2089 config ARCH_HAS_DEVMEM_IS_ALLOWED
2092 config STRICT_DEVMEM
2093 bool "Filter access to /dev/mem"
2094 depends on MMU && DEVMEM
2095 depends on ARCH_HAS_DEVMEM_IS_ALLOWED
2096 default y if PPC || X86 || ARM64
2098 If this option is disabled, you allow userspace (root) access to all
2099 of memory, including kernel and userspace memory. Accidental
2100 access to this is obviously disastrous, but specific access can
2101 be used by people debugging the kernel. Note that with PAT support
2102 enabled, even in this case there are restrictions on /dev/mem
2103 use due to the cache aliasing requirements.
2105 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
2106 file only allows userspace access to PCI space and the BIOS code and
2107 data regions. This is sufficient for dosemu and X and all common
2112 config IO_STRICT_DEVMEM
2113 bool "Filter I/O access to /dev/mem"
2114 depends on STRICT_DEVMEM
2116 If this option is disabled, you allow userspace (root) access to all
2117 io-memory regardless of whether a driver is actively using that
2118 range. Accidental access to this is obviously disastrous, but
2119 specific access can be used by people debugging kernel drivers.
2121 If this option is switched on, the /dev/mem file only allows
2122 userspace access to *idle* io-memory ranges (see /proc/iomem) This
2123 may break traditional users of /dev/mem (dosemu, legacy X, etc...)
2124 if the driver using a given range cannot be disabled.
2128 source "arch/$(SRCARCH)/Kconfig.debug"
2130 endmenu # Kernel hacking
projects / linux-2.6-block.git / blob