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
226 depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED
227 depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST
229 Generate deduplicated BTF type information from DWARF debug info.
230 Turning this on expects presence of pahole tool, which will convert
231 DWARF type info into equivalent deduplicated BTF type info.
234 bool "Provide GDB scripts for kernel debugging"
235 depends on DEBUG_INFO
237 This creates the required links to GDB helper scripts in the
238 build directory. If you load vmlinux into gdb, the helper
239 scripts will be automatically imported by gdb as well, and
240 additional functions are available to analyze a Linux kernel
241 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
244 config ENABLE_MUST_CHECK
245 bool "Enable __must_check logic"
248 Enable the __must_check logic in the kernel build. Disable this to
249 suppress the "warning: ignoring return value of 'foo', declared with
250 attribute warn_unused_result" messages.
253 int "Warn for stack frames larger than (needs gcc 4.4)"
255 default 2048 if GCC_PLUGIN_LATENT_ENTROPY
256 default 2048 if PARISC
257 default 1536 if (!64BIT && XTENSA)
258 default 1280 if KASAN && !64BIT
259 default 1024 if !64BIT
260 default 2048 if 64BIT
262 Tell gcc to warn at build time for stack frames larger than this.
263 Setting this too low will cause a lot of warnings.
264 Setting it to 0 disables the warning.
267 config STRIP_ASM_SYMS
268 bool "Strip assembler-generated symbols during link"
271 Strip internal assembler-generated symbols during a link (symbols
272 that look like '.Lxxx') so they don't pollute the output of
273 get_wchan() and suchlike.
276 bool "Generate readable assembler code"
277 depends on DEBUG_KERNEL
279 Disable some compiler optimizations that tend to generate human unreadable
280 assembler output. This may make the kernel slightly slower, but it helps
281 to keep kernel developers who have to stare a lot at assembler listings
285 bool "Debug Filesystem"
287 debugfs is a virtual file system that kernel developers use to put
288 debugging files into. Enable this option to be able to read and
289 write to these files.
291 For detailed documentation on the debugfs API, see
292 Documentation/filesystems/.
296 config HEADERS_INSTALL
297 bool "Install uapi headers to usr/include"
300 This option will install uapi headers (headers exported to user-space)
301 into the usr/include directory for use during the kernel build.
302 This is unneeded for building the kernel itself, but needed for some
303 user-space program samples. It is also needed by some features such
304 as uapi header sanity checks.
306 config OPTIMIZE_INLINING
309 This option determines if the kernel forces gcc to inline the functions
310 developers have marked 'inline'. Doing so takes away freedom from gcc to
311 do what it thinks is best, which is desirable for the gcc 3.x series of
312 compilers. The gcc 4.x series have a rewritten inlining algorithm and
313 enabling this option will generate a smaller kernel there. Hopefully
314 this algorithm is so good that allowing gcc 4.x and above to make the
315 decision will become the default in the future. Until then this option
316 is there to test gcc for this.
318 config DEBUG_SECTION_MISMATCH
319 bool "Enable full Section mismatch analysis"
321 The section mismatch analysis checks if there are illegal
322 references from one section to another section.
323 During linktime or runtime, some sections are dropped;
324 any use of code/data previously in these sections would
325 most likely result in an oops.
326 In the code, functions and variables are annotated with
327 __init,, etc. (see the full list in include/linux/init.h),
328 which results in the code/data being placed in specific sections.
329 The section mismatch analysis is always performed after a full
330 kernel build, and enabling this option causes the following
331 additional step to occur:
332 - Add the option -fno-inline-functions-called-once to gcc commands.
333 When inlining a function annotated with __init in a non-init
334 function, we would lose the section information and thus
335 the analysis would not catch the illegal reference.
336 This option tells gcc to inline less (but it does result in
339 config SECTION_MISMATCH_WARN_ONLY
340 bool "Make section mismatch errors non-fatal"
343 If you say N here, the build process will fail if there are any
344 section mismatch, instead of just throwing warnings.
349 # Select this config option from the architecture Kconfig, if it
350 # is preferred to always offer frame pointers as a config
351 # option on the architecture (regardless of KERNEL_DEBUG):
353 config ARCH_WANT_FRAME_POINTERS
357 bool "Compile the kernel with frame pointers"
358 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
359 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
361 If you say Y here the resulting kernel image will be slightly
362 larger and slower, but it gives very useful debugging information
363 in case of kernel bugs. (precise oopses/stacktraces/warnings)
365 config STACK_VALIDATION
366 bool "Compile-time stack metadata validation"
367 depends on HAVE_STACK_VALIDATION
370 Add compile-time checks to validate stack metadata, including frame
371 pointers (if CONFIG_FRAME_POINTER is enabled). This helps ensure
372 that runtime stack traces are more reliable.
374 This is also a prerequisite for generation of ORC unwind data, which
375 is needed for CONFIG_UNWINDER_ORC.
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.
437 bool "Miscellaneous debug code"
439 depends on DEBUG_KERNEL
441 Say Y here if you need to enable miscellaneous debug code that should
442 be under a more specific debug option but isn't.
445 menu "Memory Debugging"
447 source "mm/Kconfig.debug"
450 bool "Debug object operations"
451 depends on DEBUG_KERNEL
453 If you say Y here, additional code will be inserted into the
454 kernel to track the life time of various objects and validate
455 the operations on those objects.
457 config DEBUG_OBJECTS_SELFTEST
458 bool "Debug objects selftest"
459 depends on DEBUG_OBJECTS
461 This enables the selftest of the object debug code.
463 config DEBUG_OBJECTS_FREE
464 bool "Debug objects in freed memory"
465 depends on DEBUG_OBJECTS
467 This enables checks whether a k/v free operation frees an area
468 which contains an object which has not been deactivated
469 properly. This can make kmalloc/kfree-intensive workloads
472 config DEBUG_OBJECTS_TIMERS
473 bool "Debug timer objects"
474 depends on DEBUG_OBJECTS
476 If you say Y here, additional code will be inserted into the
477 timer routines to track the life time of timer objects and
478 validate the timer operations.
480 config DEBUG_OBJECTS_WORK
481 bool "Debug work objects"
482 depends on DEBUG_OBJECTS
484 If you say Y here, additional code will be inserted into the
485 work queue routines to track the life time of work objects and
486 validate the work operations.
488 config DEBUG_OBJECTS_RCU_HEAD
489 bool "Debug RCU callbacks objects"
490 depends on DEBUG_OBJECTS
492 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
494 config DEBUG_OBJECTS_PERCPU_COUNTER
495 bool "Debug percpu counter objects"
496 depends on DEBUG_OBJECTS
498 If you say Y here, additional code will be inserted into the
499 percpu counter routines to track the life time of percpu counter
500 objects and validate the percpu counter operations.
502 config DEBUG_OBJECTS_ENABLE_DEFAULT
503 int "debug_objects bootup default value (0-1)"
506 depends on DEBUG_OBJECTS
508 Debug objects boot parameter default value
511 bool "Debug slab memory allocations"
512 depends on DEBUG_KERNEL && SLAB
514 Say Y here to have the kernel do limited verification on memory
515 allocation as well as poisoning memory on free to catch use of freed
516 memory. This can make kmalloc/kfree-intensive workloads much slower.
519 bool "SLUB debugging on by default"
520 depends on SLUB && SLUB_DEBUG
523 Boot with debugging on by default. SLUB boots by default with
524 the runtime debug capabilities switched off. Enabling this is
525 equivalent to specifying the "slub_debug" parameter on boot.
526 There is no support for more fine grained debug control like
527 possible with slub_debug=xxx. SLUB debugging may be switched
528 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
533 bool "Enable SLUB performance statistics"
534 depends on SLUB && SYSFS
536 SLUB statistics are useful to debug SLUBs allocation behavior in
537 order find ways to optimize the allocator. This should never be
538 enabled for production use since keeping statistics slows down
539 the allocator by a few percentage points. The slabinfo command
540 supports the determination of the most active slabs to figure
541 out which slabs are relevant to a particular load.
542 Try running: slabinfo -DA
544 config HAVE_DEBUG_KMEMLEAK
547 config DEBUG_KMEMLEAK
548 bool "Kernel memory leak detector"
549 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
551 select STACKTRACE if STACKTRACE_SUPPORT
555 Say Y here if you want to enable the memory leak
556 detector. The memory allocation/freeing is traced in a way
557 similar to the Boehm's conservative garbage collector, the
558 difference being that the orphan objects are not freed but
559 only shown in /sys/kernel/debug/kmemleak. Enabling this
560 feature will introduce an overhead to memory
561 allocations. See Documentation/dev-tools/kmemleak.rst for more
564 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
565 of finding leaks due to the slab objects poisoning.
567 In order to access the kmemleak file, debugfs needs to be
568 mounted (usually at /sys/kernel/debug).
570 config DEBUG_KMEMLEAK_MEM_POOL_SIZE
571 int "Kmemleak memory pool size"
572 depends on DEBUG_KMEMLEAK
576 Kmemleak must track all the memory allocations to avoid
577 reporting false positives. Since memory may be allocated or
578 freed before kmemleak is fully initialised, use a static pool
579 of metadata objects to track such callbacks. After kmemleak is
580 fully initialised, this memory pool acts as an emergency one
581 if slab allocations fail.
583 config DEBUG_KMEMLEAK_TEST
584 tristate "Simple test for the kernel memory leak detector"
585 depends on DEBUG_KMEMLEAK && m
587 This option enables a module that explicitly leaks memory.
591 config DEBUG_KMEMLEAK_DEFAULT_OFF
592 bool "Default kmemleak to off"
593 depends on DEBUG_KMEMLEAK
595 Say Y here to disable kmemleak by default. It can then be enabled
596 on the command line via kmemleak=on.
598 config DEBUG_KMEMLEAK_AUTO_SCAN
599 bool "Enable kmemleak auto scan thread on boot up"
601 depends on DEBUG_KMEMLEAK
603 Depending on the cpu, kmemleak scan may be cpu intensive and can
604 stall user tasks at times. This option enables/disables automatic
605 kmemleak scan at boot up.
607 Say N here to disable kmemleak auto scan thread to stop automatic
608 scanning. Disabling this option disables automatic reporting of
613 config DEBUG_STACK_USAGE
614 bool "Stack utilization instrumentation"
615 depends on DEBUG_KERNEL && !IA64
617 Enables the display of the minimum amount of free stack which each
618 task has ever had available in the sysrq-T and sysrq-P debug output.
620 This option will slow down process creation somewhat.
624 depends on DEBUG_KERNEL
626 Enable this to turn on extended checks in the virtual-memory system
627 that may impact performance.
631 config DEBUG_VM_VMACACHE
632 bool "Debug VMA caching"
635 Enable this to turn on VMA caching debug information. Doing so
636 can cause significant overhead, so only enable it in non-production
642 bool "Debug VM red-black trees"
645 Enable VM red-black tree debugging information and extra validations.
649 config DEBUG_VM_PGFLAGS
650 bool "Debug page-flags operations"
653 Enables extra validation on page flags operations.
657 config ARCH_HAS_DEBUG_VIRTUAL
661 bool "Debug VM translations"
662 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
664 Enable some costly sanity checks in virtual to page code. This can
665 catch mistakes with virt_to_page() and friends.
669 config DEBUG_NOMMU_REGIONS
670 bool "Debug the global anon/private NOMMU mapping region tree"
671 depends on DEBUG_KERNEL && !MMU
673 This option causes the global tree of anonymous and private mapping
674 regions to be regularly checked for invalid topology.
676 config DEBUG_MEMORY_INIT
677 bool "Debug memory initialisation" if EXPERT
680 Enable this for additional checks during memory initialisation.
681 The sanity checks verify aspects of the VM such as the memory model
682 and other information provided by the architecture. Verbose
683 information will be printed at KERN_DEBUG loglevel depending
684 on the mminit_loglevel= command-line option.
688 config MEMORY_NOTIFIER_ERROR_INJECT
689 tristate "Memory hotplug notifier error injection module"
690 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
692 This option provides the ability to inject artificial errors to
693 memory hotplug notifier chain callbacks. It is controlled through
694 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
696 If the notifier call chain should be failed with some events
697 notified, write the error code to "actions/<notifier event>/error".
699 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
701 # cd /sys/kernel/debug/notifier-error-inject/memory
702 # echo -12 > actions/MEM_GOING_OFFLINE/error
703 # echo offline > /sys/devices/system/memory/memoryXXX/state
704 bash: echo: write error: Cannot allocate memory
706 To compile this code as a module, choose M here: the module will
707 be called memory-notifier-error-inject.
711 config DEBUG_PER_CPU_MAPS
712 bool "Debug access to per_cpu maps"
713 depends on DEBUG_KERNEL
716 Say Y to verify that the per_cpu map being accessed has
717 been set up. This adds a fair amount of code to kernel memory
718 and decreases performance.
723 bool "Highmem debugging"
724 depends on DEBUG_KERNEL && HIGHMEM
726 This option enables additional error checking for high memory
727 systems. Disable for production systems.
729 config HAVE_DEBUG_STACKOVERFLOW
732 config DEBUG_STACKOVERFLOW
733 bool "Check for stack overflows"
734 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
736 Say Y here if you want to check for overflows of kernel, IRQ
737 and exception stacks (if your architecture uses them). This
738 option will show detailed messages if free stack space drops
739 below a certain limit.
741 These kinds of bugs usually occur when call-chains in the
742 kernel get too deep, especially when interrupts are
745 Use this in cases where you see apparently random memory
746 corruption, especially if it appears in 'struct thread_info'
748 If in doubt, say "N".
750 source "lib/Kconfig.kasan"
752 endmenu # "Memory Debugging"
757 An architecture should select this when it can successfully
758 build and run with CONFIG_KCOV. This typically requires
759 disabling instrumentation for some early boot code.
761 config CC_HAS_SANCOV_TRACE_PC
762 def_bool $(cc-option,-fsanitize-coverage=trace-pc)
765 bool "Code coverage for fuzzing"
766 depends on ARCH_HAS_KCOV
767 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
769 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
771 KCOV exposes kernel code coverage information in a form suitable
772 for coverage-guided fuzzing (randomized testing).
774 If RANDOMIZE_BASE is enabled, PC values will not be stable across
775 different machines and across reboots. If you need stable PC values,
776 disable RANDOMIZE_BASE.
778 For more details, see Documentation/dev-tools/kcov.rst.
780 config KCOV_ENABLE_COMPARISONS
781 bool "Enable comparison operands collection by KCOV"
783 depends on $(cc-option,-fsanitize-coverage=trace-cmp)
785 KCOV also exposes operands of every comparison in the instrumented
786 code along with operand sizes and PCs of the comparison instructions.
787 These operands can be used by fuzzing engines to improve the quality
790 config KCOV_INSTRUMENT_ALL
791 bool "Instrument all code by default"
795 If you are doing generic system call fuzzing (like e.g. syzkaller),
796 then you will want to instrument the whole kernel and you should
797 say y here. If you are doing more targeted fuzzing (like e.g.
798 filesystem fuzzing with AFL) then you will want to enable coverage
799 for more specific subsets of files, and should say n here.
802 bool "Debug shared IRQ handlers"
803 depends on DEBUG_KERNEL
805 Enable this to generate a spurious interrupt as soon as a shared
806 interrupt handler is registered, and just before one is deregistered.
807 Drivers ought to be able to handle interrupts coming in at those
808 points; some don't and need to be caught.
810 menu "Debug Lockups and Hangs"
812 config LOCKUP_DETECTOR
815 config SOFTLOCKUP_DETECTOR
816 bool "Detect Soft Lockups"
817 depends on DEBUG_KERNEL && !S390
818 select LOCKUP_DETECTOR
820 Say Y here to enable the kernel to act as a watchdog to detect
823 Softlockups are bugs that cause the kernel to loop in kernel
824 mode for more than 20 seconds, without giving other tasks a
825 chance to run. The current stack trace is displayed upon
826 detection and the system will stay locked up.
828 config BOOTPARAM_SOFTLOCKUP_PANIC
829 bool "Panic (Reboot) On Soft Lockups"
830 depends on SOFTLOCKUP_DETECTOR
832 Say Y here to enable the kernel to panic on "soft lockups",
833 which are bugs that cause the kernel to loop in kernel
834 mode for more than 20 seconds (configurable using the watchdog_thresh
835 sysctl), without giving other tasks a chance to run.
837 The panic can be used in combination with panic_timeout,
838 to cause the system to reboot automatically after a
839 lockup has been detected. This feature is useful for
840 high-availability systems that have uptime guarantees and
841 where a lockup must be resolved ASAP.
845 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
847 depends on SOFTLOCKUP_DETECTOR
849 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
850 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
852 config HARDLOCKUP_DETECTOR_PERF
854 select SOFTLOCKUP_DETECTOR
857 # Enables a timestamp based low pass filter to compensate for perf based
858 # hard lockup detection which runs too fast due to turbo modes.
860 config HARDLOCKUP_CHECK_TIMESTAMP
864 # arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard
865 # lockup detector rather than the perf based detector.
867 config HARDLOCKUP_DETECTOR
868 bool "Detect Hard Lockups"
869 depends on DEBUG_KERNEL && !S390
870 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH
871 select LOCKUP_DETECTOR
872 select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF
874 Say Y here to enable the kernel to act as a watchdog to detect
877 Hardlockups are bugs that cause the CPU to loop in kernel mode
878 for more than 10 seconds, without letting other interrupts have a
879 chance to run. The current stack trace is displayed upon detection
880 and the system will stay locked up.
882 config BOOTPARAM_HARDLOCKUP_PANIC
883 bool "Panic (Reboot) On Hard Lockups"
884 depends on HARDLOCKUP_DETECTOR
886 Say Y here to enable the kernel to panic on "hard lockups",
887 which are bugs that cause the kernel to loop in kernel
888 mode with interrupts disabled for more than 10 seconds (configurable
889 using the watchdog_thresh sysctl).
893 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
895 depends on HARDLOCKUP_DETECTOR
897 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
898 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
900 config DETECT_HUNG_TASK
901 bool "Detect Hung Tasks"
902 depends on DEBUG_KERNEL
903 default SOFTLOCKUP_DETECTOR
905 Say Y here to enable the kernel to detect "hung tasks",
906 which are bugs that cause the task to be stuck in
907 uninterruptible "D" state indefinitely.
909 When a hung task is detected, the kernel will print the
910 current stack trace (which you should report), but the
911 task will stay in uninterruptible state. If lockdep is
912 enabled then all held locks will also be reported. This
913 feature has negligible overhead.
915 config DEFAULT_HUNG_TASK_TIMEOUT
916 int "Default timeout for hung task detection (in seconds)"
917 depends on DETECT_HUNG_TASK
920 This option controls the default timeout (in seconds) used
921 to determine when a task has become non-responsive and should
924 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
925 sysctl or by writing a value to
926 /proc/sys/kernel/hung_task_timeout_secs.
928 A timeout of 0 disables the check. The default is two minutes.
929 Keeping the default should be fine in most cases.
931 config BOOTPARAM_HUNG_TASK_PANIC
932 bool "Panic (Reboot) On Hung Tasks"
933 depends on DETECT_HUNG_TASK
935 Say Y here to enable the kernel to panic on "hung tasks",
936 which are bugs that cause the kernel to leave a task stuck
937 in uninterruptible "D" state.
939 The panic can be used in combination with panic_timeout,
940 to cause the system to reboot automatically after a
941 hung task has been detected. This feature is useful for
942 high-availability systems that have uptime guarantees and
943 where a hung tasks must be resolved ASAP.
947 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
949 depends on DETECT_HUNG_TASK
951 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
952 default 1 if BOOTPARAM_HUNG_TASK_PANIC
955 bool "Detect Workqueue Stalls"
956 depends on DEBUG_KERNEL
958 Say Y here to enable stall detection on workqueues. If a
959 worker pool doesn't make forward progress on a pending work
960 item for over a given amount of time, 30s by default, a
961 warning message is printed along with dump of workqueue
962 state. This can be configured through kernel parameter
963 "workqueue.watchdog_thresh" and its sysfs counterpart.
965 endmenu # "Debug lockups and hangs"
970 Say Y here to enable the kernel to panic when it oopses. This
971 has the same effect as setting oops=panic on the kernel command
974 This feature is useful to ensure that the kernel does not do
975 anything erroneous after an oops which could result in data
976 corruption or other issues.
980 config PANIC_ON_OOPS_VALUE
983 default 0 if !PANIC_ON_OOPS
984 default 1 if PANIC_ON_OOPS
990 Set the timeout value (in seconds) until a reboot occurs when the
991 the kernel panics. If n = 0, then we wait forever. A timeout
992 value n > 0 will wait n seconds before rebooting, while a timeout
993 value n < 0 will reboot immediately.
996 bool "Collect scheduler debugging info"
997 depends on DEBUG_KERNEL && PROC_FS
1000 If you say Y here, the /proc/sched_debug file will be provided
1001 that can help debug the scheduler. The runtime overhead of this
1009 bool "Collect scheduler statistics"
1010 depends on DEBUG_KERNEL && PROC_FS
1013 If you say Y here, additional code will be inserted into the
1014 scheduler and related routines to collect statistics about
1015 scheduler behavior and provide them in /proc/schedstat. These
1016 stats may be useful for both tuning and debugging the scheduler
1017 If you aren't debugging the scheduler or trying to tune a specific
1018 application, you can say N to avoid the very slight overhead
1021 config SCHED_STACK_END_CHECK
1022 bool "Detect stack corruption on calls to schedule()"
1023 depends on DEBUG_KERNEL
1026 This option checks for a stack overrun on calls to schedule().
1027 If the stack end location is found to be over written always panic as
1028 the content of the corrupted region can no longer be trusted.
1029 This is to ensure no erroneous behaviour occurs which could result in
1030 data corruption or a sporadic crash at a later stage once the region
1031 is examined. The runtime overhead introduced is minimal.
1033 config DEBUG_TIMEKEEPING
1034 bool "Enable extra timekeeping sanity checking"
1036 This option will enable additional timekeeping sanity checks
1037 which may be helpful when diagnosing issues where timekeeping
1038 problems are suspected.
1040 This may include checks in the timekeeping hotpaths, so this
1041 option may have a (very small) performance impact to some
1046 config DEBUG_PREEMPT
1047 bool "Debug preemptible kernel"
1048 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
1051 If you say Y here then the kernel will use a debug variant of the
1052 commonly used smp_processor_id() function and will print warnings
1053 if kernel code uses it in a preemption-unsafe way. Also, the kernel
1054 will detect preemption count underflows.
1056 menu "Lock Debugging (spinlocks, mutexes, etc...)"
1058 config LOCK_DEBUGGING_SUPPORT
1060 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1063 config PROVE_LOCKING
1064 bool "Lock debugging: prove locking correctness"
1065 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1067 select DEBUG_SPINLOCK
1068 select DEBUG_MUTEXES
1069 select DEBUG_RT_MUTEXES if RT_MUTEXES
1071 select DEBUG_WW_MUTEX_SLOWPATH
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.rst.
1110 bool "Lock usage statistics"
1111 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1113 select DEBUG_SPINLOCK
1114 select DEBUG_MUTEXES
1115 select DEBUG_RT_MUTEXES if RT_MUTEXES
1116 select DEBUG_LOCK_ALLOC
1119 This feature enables tracking lock contention points
1121 For more details, see Documentation/locking/lockstat.rst
1123 This also enables lock events required by "perf lock",
1125 If you want to use "perf lock", you also need to turn on
1126 CONFIG_EVENT_TRACING.
1128 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1129 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1131 config DEBUG_RT_MUTEXES
1132 bool "RT Mutex debugging, deadlock detection"
1133 depends on DEBUG_KERNEL && RT_MUTEXES
1135 This allows rt mutex semantics violations and rt mutex related
1136 deadlocks (lockups) to be detected and reported automatically.
1138 config DEBUG_SPINLOCK
1139 bool "Spinlock and rw-lock debugging: basic checks"
1140 depends on DEBUG_KERNEL
1141 select UNINLINE_SPIN_UNLOCK
1143 Say Y here and build SMP to catch missing spinlock initialization
1144 and certain other kinds of spinlock errors commonly made. This is
1145 best used in conjunction with the NMI watchdog so that spinlock
1146 deadlocks are also debuggable.
1148 config DEBUG_MUTEXES
1149 bool "Mutex debugging: basic checks"
1150 depends on DEBUG_KERNEL
1152 This feature allows mutex semantics violations to be detected and
1155 config DEBUG_WW_MUTEX_SLOWPATH
1156 bool "Wait/wound mutex debugging: Slowpath testing"
1157 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1158 select DEBUG_LOCK_ALLOC
1159 select DEBUG_SPINLOCK
1160 select DEBUG_MUTEXES
1162 This feature enables slowpath testing for w/w mutex users by
1163 injecting additional -EDEADLK wound/backoff cases. Together with
1164 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1165 will test all possible w/w mutex interface abuse with the
1166 exception of simply not acquiring all the required locks.
1167 Note that this feature can introduce significant overhead, so
1168 it really should not be enabled in a production or distro kernel,
1169 even a debug kernel. If you are a driver writer, enable it. If
1170 you are a distro, do not.
1173 bool "RW Semaphore debugging: basic checks"
1174 depends on DEBUG_KERNEL
1176 This debugging feature allows mismatched rw semaphore locks
1177 and unlocks to be detected and reported.
1179 config DEBUG_LOCK_ALLOC
1180 bool "Lock debugging: detect incorrect freeing of live locks"
1181 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1182 select DEBUG_SPINLOCK
1183 select DEBUG_MUTEXES
1184 select DEBUG_RT_MUTEXES if RT_MUTEXES
1187 This feature will check whether any held lock (spinlock, rwlock,
1188 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1189 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1190 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1191 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1192 held during task exit.
1196 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1198 select FRAME_POINTER if !MIPS && !PPC && !ARM && !S390 && !MICROBLAZE && !ARC && !X86
1202 config LOCKDEP_SMALL
1205 config DEBUG_LOCKDEP
1206 bool "Lock dependency engine debugging"
1207 depends on DEBUG_KERNEL && LOCKDEP
1209 If you say Y here, the lock dependency engine will do
1210 additional runtime checks to debug itself, at the price
1211 of more runtime overhead.
1213 config DEBUG_ATOMIC_SLEEP
1214 bool "Sleep inside atomic section checking"
1215 select PREEMPT_COUNT
1216 depends on DEBUG_KERNEL
1217 depends on !ARCH_NO_PREEMPT
1219 If you say Y here, various routines which may sleep will become very
1220 noisy if they are called inside atomic sections: when a spinlock is
1221 held, inside an rcu read side critical section, inside preempt disabled
1222 sections, inside an interrupt, etc...
1224 config DEBUG_LOCKING_API_SELFTESTS
1225 bool "Locking API boot-time self-tests"
1226 depends on DEBUG_KERNEL
1228 Say Y here if you want the kernel to run a short self-test during
1229 bootup. The self-test checks whether common types of locking bugs
1230 are detected by debugging mechanisms or not. (if you disable
1231 lock debugging then those bugs wont be detected of course.)
1232 The following locking APIs are covered: spinlocks, rwlocks,
1235 config LOCK_TORTURE_TEST
1236 tristate "torture tests for locking"
1237 depends on DEBUG_KERNEL
1240 This option provides a kernel module that runs torture tests
1241 on kernel locking primitives. The kernel module may be built
1242 after the fact on the running kernel to be tested, if desired.
1244 Say Y here if you want kernel locking-primitive torture tests
1245 to be built into the kernel.
1246 Say M if you want these torture tests to build as a module.
1247 Say N if you are unsure.
1249 config WW_MUTEX_SELFTEST
1250 tristate "Wait/wound mutex selftests"
1252 This option provides a kernel module that runs tests on the
1253 on the struct ww_mutex locking API.
1255 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1256 with this test harness.
1258 Say M if you want these self tests to build as a module.
1259 Say N if you are unsure.
1261 endmenu # lock debugging
1263 config TRACE_IRQFLAGS
1266 Enables hooks to interrupt enabling and disabling for
1267 either tracing or lock debugging.
1270 bool "Stack backtrace support"
1271 depends on STACKTRACE_SUPPORT
1273 This option causes the kernel to create a /proc/pid/stack for
1274 every process, showing its current stack trace.
1275 It is also used by various kernel debugging features that require
1276 stack trace generation.
1278 config WARN_ALL_UNSEEDED_RANDOM
1279 bool "Warn for all uses of unseeded randomness"
1282 Some parts of the kernel contain bugs relating to their use of
1283 cryptographically secure random numbers before it's actually possible
1284 to generate those numbers securely. This setting ensures that these
1285 flaws don't go unnoticed, by enabling a message, should this ever
1286 occur. This will allow people with obscure setups to know when things
1287 are going wrong, so that they might contact developers about fixing
1290 Unfortunately, on some models of some architectures getting
1291 a fully seeded CRNG is extremely difficult, and so this can
1292 result in dmesg getting spammed for a surprisingly long
1293 time. This is really bad from a security perspective, and
1294 so architecture maintainers really need to do what they can
1295 to get the CRNG seeded sooner after the system is booted.
1296 However, since users cannot do anything actionable to
1297 address this, by default this option is disabled.
1299 Say Y here if you want to receive warnings for all uses of
1300 unseeded randomness. This will be of use primarily for
1301 those developers interested in improving the security of
1302 Linux kernels running on their architecture (or
1305 config DEBUG_KOBJECT
1306 bool "kobject debugging"
1307 depends on DEBUG_KERNEL
1309 If you say Y here, some extra kobject debugging messages will be sent
1312 config DEBUG_KOBJECT_RELEASE
1313 bool "kobject release debugging"
1314 depends on DEBUG_OBJECTS_TIMERS
1316 kobjects are reference counted objects. This means that their
1317 last reference count put is not predictable, and the kobject can
1318 live on past the point at which a driver decides to drop it's
1319 initial reference to the kobject gained on allocation. An
1320 example of this would be a struct device which has just been
1323 However, some buggy drivers assume that after such an operation,
1324 the memory backing the kobject can be immediately freed. This
1325 goes completely against the principles of a refcounted object.
1327 If you say Y here, the kernel will delay the release of kobjects
1328 on the last reference count to improve the visibility of this
1329 kind of kobject release bug.
1331 config HAVE_DEBUG_BUGVERBOSE
1334 config DEBUG_BUGVERBOSE
1335 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
1336 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
1339 Say Y here to make BUG() panics output the file name and line number
1340 of the BUG call as well as the EIP and oops trace. This aids
1341 debugging but costs about 70-100K of memory.
1344 bool "Debug linked list manipulation"
1345 depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION
1347 Enable this to turn on extended checks in the linked-list
1353 bool "Debug priority linked list manipulation"
1354 depends on DEBUG_KERNEL
1356 Enable this to turn on extended checks in the priority-ordered
1357 linked-list (plist) walking routines. This checks the entire
1358 list multiple times during each manipulation.
1363 bool "Debug SG table operations"
1364 depends on DEBUG_KERNEL
1366 Enable this to turn on checks on scatter-gather tables. This can
1367 help find problems with drivers that do not properly initialize
1372 config DEBUG_NOTIFIERS
1373 bool "Debug notifier call chains"
1374 depends on DEBUG_KERNEL
1376 Enable this to turn on sanity checking for notifier call chains.
1377 This is most useful for kernel developers to make sure that
1378 modules properly unregister themselves from notifier chains.
1379 This is a relatively cheap check but if you care about maximum
1382 config DEBUG_CREDENTIALS
1383 bool "Debug credential management"
1384 depends on DEBUG_KERNEL
1386 Enable this to turn on some debug checking for credential
1387 management. The additional code keeps track of the number of
1388 pointers from task_structs to any given cred struct, and checks to
1389 see that this number never exceeds the usage count of the cred
1392 Furthermore, if SELinux is enabled, this also checks that the
1393 security pointer in the cred struct is never seen to be invalid.
1397 source "kernel/rcu/Kconfig.debug"
1399 config DEBUG_WQ_FORCE_RR_CPU
1400 bool "Force round-robin CPU selection for unbound work items"
1401 depends on DEBUG_KERNEL
1404 Workqueue used to implicitly guarantee that work items queued
1405 without explicit CPU specified are put on the local CPU. This
1406 guarantee is no longer true and while local CPU is still
1407 preferred work items may be put on foreign CPUs. Kernel
1408 parameter "workqueue.debug_force_rr_cpu" is added to force
1409 round-robin CPU selection to flush out usages which depend on the
1410 now broken guarantee. This config option enables the debug
1411 feature by default. When enabled, memory and cache locality will
1414 config DEBUG_BLOCK_EXT_DEVT
1415 bool "Force extended block device numbers and spread them"
1416 depends on DEBUG_KERNEL
1420 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1421 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1422 YOU ARE DOING. Distros, please enable this and fix whatever
1425 Conventionally, block device numbers are allocated from
1426 predetermined contiguous area. However, extended block area
1427 may introduce non-contiguous block device numbers. This
1428 option forces most block device numbers to be allocated from
1429 the extended space and spreads them to discover kernel or
1430 userland code paths which assume predetermined contiguous
1431 device number allocation.
1433 Note that turning on this debug option shuffles all the
1434 device numbers for all IDE and SCSI devices including libata
1435 ones, so root partition specified using device number
1436 directly (via rdev or root=MAJ:MIN) won't work anymore.
1437 Textual device names (root=/dev/sdXn) will continue to work.
1439 Say N if you are unsure.
1441 config CPU_HOTPLUG_STATE_CONTROL
1442 bool "Enable CPU hotplug state control"
1443 depends on DEBUG_KERNEL
1444 depends on HOTPLUG_CPU
1447 Allows to write steps between "offline" and "online" to the CPUs
1448 sysfs target file so states can be stepped granular. This is a debug
1449 option for now as the hotplug machinery cannot be stopped and
1450 restarted at arbitrary points yet.
1452 Say N if your are unsure.
1454 config NOTIFIER_ERROR_INJECTION
1455 tristate "Notifier error injection"
1456 depends on DEBUG_KERNEL
1459 This option provides the ability to inject artificial errors to
1460 specified notifier chain callbacks. It is useful to test the error
1461 handling of notifier call chain failures.
1465 config PM_NOTIFIER_ERROR_INJECT
1466 tristate "PM notifier error injection module"
1467 depends on PM && NOTIFIER_ERROR_INJECTION
1468 default m if PM_DEBUG
1470 This option provides the ability to inject artificial errors to
1471 PM notifier chain callbacks. It is controlled through debugfs
1472 interface /sys/kernel/debug/notifier-error-inject/pm
1474 If the notifier call chain should be failed with some events
1475 notified, write the error code to "actions/<notifier event>/error".
1477 Example: Inject PM suspend error (-12 = -ENOMEM)
1479 # cd /sys/kernel/debug/notifier-error-inject/pm/
1480 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1481 # echo mem > /sys/power/state
1482 bash: echo: write error: Cannot allocate memory
1484 To compile this code as a module, choose M here: the module will
1485 be called pm-notifier-error-inject.
1489 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1490 tristate "OF reconfig notifier error injection module"
1491 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1493 This option provides the ability to inject artificial errors to
1494 OF reconfig notifier chain callbacks. It is controlled
1495 through debugfs interface under
1496 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1498 If the notifier call chain should be failed with some events
1499 notified, write the error code to "actions/<notifier event>/error".
1501 To compile this code as a module, choose M here: the module will
1502 be called of-reconfig-notifier-error-inject.
1506 config NETDEV_NOTIFIER_ERROR_INJECT
1507 tristate "Netdev notifier error injection module"
1508 depends on NET && NOTIFIER_ERROR_INJECTION
1510 This option provides the ability to inject artificial errors to
1511 netdevice notifier chain callbacks. It is controlled through debugfs
1512 interface /sys/kernel/debug/notifier-error-inject/netdev
1514 If the notifier call chain should be failed with some events
1515 notified, write the error code to "actions/<notifier event>/error".
1517 Example: Inject netdevice mtu change error (-22 = -EINVAL)
1519 # cd /sys/kernel/debug/notifier-error-inject/netdev
1520 # echo -22 > actions/NETDEV_CHANGEMTU/error
1521 # ip link set eth0 mtu 1024
1522 RTNETLINK answers: Invalid argument
1524 To compile this code as a module, choose M here: the module will
1525 be called netdev-notifier-error-inject.
1529 config FUNCTION_ERROR_INJECTION
1530 bool "Fault-injections of functions"
1531 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
1533 Add fault injections into various functions that are annotated with
1534 ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return
1535 value of theses functions. This is useful to test error paths of code.
1539 config FAULT_INJECTION
1540 bool "Fault-injection framework"
1541 depends on DEBUG_KERNEL
1543 Provide fault-injection framework.
1544 For more details, see Documentation/fault-injection/.
1547 bool "Fault-injection capability for kmalloc"
1548 depends on FAULT_INJECTION
1549 depends on SLAB || SLUB
1551 Provide fault-injection capability for kmalloc.
1553 config FAIL_PAGE_ALLOC
1554 bool "Fault-injection capabilitiy for alloc_pages()"
1555 depends on FAULT_INJECTION
1557 Provide fault-injection capability for alloc_pages().
1559 config FAIL_MAKE_REQUEST
1560 bool "Fault-injection capability for disk IO"
1561 depends on FAULT_INJECTION && BLOCK
1563 Provide fault-injection capability for disk IO.
1565 config FAIL_IO_TIMEOUT
1566 bool "Fault-injection capability for faking disk interrupts"
1567 depends on FAULT_INJECTION && BLOCK
1569 Provide fault-injection capability on end IO handling. This
1570 will make the block layer "forget" an interrupt as configured,
1571 thus exercising the error handling.
1573 Only works with drivers that use the generic timeout handling,
1574 for others it wont do anything.
1577 bool "Fault-injection capability for futexes"
1579 depends on FAULT_INJECTION && FUTEX
1581 Provide fault-injection capability for futexes.
1583 config FAULT_INJECTION_DEBUG_FS
1584 bool "Debugfs entries for fault-injection capabilities"
1585 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1587 Enable configuration of fault-injection capabilities via debugfs.
1589 config FAIL_FUNCTION
1590 bool "Fault-injection capability for functions"
1591 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
1593 Provide function-based fault-injection capability.
1594 This will allow you to override a specific function with a return
1595 with given return value. As a result, function caller will see
1596 an error value and have to handle it. This is useful to test the
1597 error handling in various subsystems.
1599 config FAIL_MMC_REQUEST
1600 bool "Fault-injection capability for MMC IO"
1601 depends on FAULT_INJECTION_DEBUG_FS && MMC
1603 Provide fault-injection capability for MMC IO.
1604 This will make the mmc core return data errors. This is
1605 useful to test the error handling in the mmc block device
1606 and to test how the mmc host driver handles retries from
1609 config FAULT_INJECTION_STACKTRACE_FILTER
1610 bool "stacktrace filter for fault-injection capabilities"
1611 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1614 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86
1616 Provide stacktrace filter for fault-injection capabilities
1619 bool "Latency measuring infrastructure"
1620 depends on DEBUG_KERNEL
1621 depends on STACKTRACE_SUPPORT
1623 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86
1630 Enable this option if you want to use the LatencyTOP tool
1631 to find out which userspace is blocking on what kernel operations.
1633 source "kernel/trace/Kconfig"
1635 config PROVIDE_OHCI1394_DMA_INIT
1636 bool "Remote debugging over FireWire early on boot"
1637 depends on PCI && X86
1639 If you want to debug problems which hang or crash the kernel early
1640 on boot and the crashing machine has a FireWire port, you can use
1641 this feature to remotely access the memory of the crashed machine
1642 over FireWire. This employs remote DMA as part of the OHCI1394
1643 specification which is now the standard for FireWire controllers.
1645 With remote DMA, you can monitor the printk buffer remotely using
1646 firescope and access all memory below 4GB using fireproxy from gdb.
1647 Even controlling a kernel debugger is possible using remote DMA.
1651 If ohci1394_dma=early is used as boot parameter, it will initialize
1652 all OHCI1394 controllers which are found in the PCI config space.
1654 As all changes to the FireWire bus such as enabling and disabling
1655 devices cause a bus reset and thereby disable remote DMA for all
1656 devices, be sure to have the cable plugged and FireWire enabled on
1657 the debugging host before booting the debug target for debugging.
1659 This code (~1k) is freed after boot. By then, the firewire stack
1660 in charge of the OHCI-1394 controllers should be used instead.
1662 See Documentation/debugging-via-ohci1394.txt for more information.
1664 menuconfig RUNTIME_TESTING_MENU
1665 bool "Runtime Testing"
1668 if RUNTIME_TESTING_MENU
1671 tristate "Linux Kernel Dump Test Tool Module"
1674 This module enables testing of the different dumping mechanisms by
1675 inducing system failures at predefined crash points.
1676 If you don't need it: say N
1677 Choose M here to compile this code as a module. The module will be
1680 Documentation on how to use the module can be found in
1681 Documentation/fault-injection/provoke-crashes.rst
1683 config TEST_LIST_SORT
1684 tristate "Linked list sorting test"
1685 depends on DEBUG_KERNEL || m
1687 Enable this to turn on 'list_sort()' function test. This test is
1688 executed only once during system boot (so affects only boot time),
1689 or at module load time.
1694 tristate "Array-based sort test"
1695 depends on DEBUG_KERNEL || m
1697 This option enables the self-test function of 'sort()' at boot,
1698 or at module load time.
1702 config KPROBES_SANITY_TEST
1703 bool "Kprobes sanity tests"
1704 depends on DEBUG_KERNEL
1707 This option provides for testing basic kprobes functionality on
1708 boot. Samples of kprobe and kretprobe are inserted and
1709 verified for functionality.
1711 Say N if you are unsure.
1713 config BACKTRACE_SELF_TEST
1714 tristate "Self test for the backtrace code"
1715 depends on DEBUG_KERNEL
1717 This option provides a kernel module that can be used to test
1718 the kernel stack backtrace code. This option is not useful
1719 for distributions or general kernels, but only for kernel
1720 developers working on architecture code.
1722 Note that if you want to also test saved backtraces, you will
1723 have to enable STACKTRACE as well.
1725 Say N if you are unsure.
1728 tristate "Red-Black tree test"
1729 depends on DEBUG_KERNEL
1731 A benchmark measuring the performance of the rbtree library.
1732 Also includes rbtree invariant checks.
1734 config REED_SOLOMON_TEST
1735 tristate "Reed-Solomon library test"
1736 depends on DEBUG_KERNEL || m
1738 select REED_SOLOMON_ENC16
1739 select REED_SOLOMON_DEC16
1741 This option enables the self-test function of rslib at boot,
1742 or at module load time.
1746 config INTERVAL_TREE_TEST
1747 tristate "Interval tree test"
1748 depends on DEBUG_KERNEL
1749 select INTERVAL_TREE
1751 A benchmark measuring the performance of the interval tree library
1754 tristate "Per cpu operations test"
1755 depends on m && DEBUG_KERNEL
1757 Enable this option to build test module which validates per-cpu
1762 config ATOMIC64_SELFTEST
1763 tristate "Perform an atomic64_t self-test"
1765 Enable this option to test the atomic64_t functions at boot or
1766 at module load time.
1770 config ASYNC_RAID6_TEST
1771 tristate "Self test for hardware accelerated raid6 recovery"
1772 depends on ASYNC_RAID6_RECOV
1775 This is a one-shot self test that permutes through the
1776 recovery of all the possible two disk failure scenarios for a
1777 N-disk array. Recovery is performed with the asynchronous
1778 raid6 recovery routines, and will optionally use an offload
1779 engine if one is available.
1784 tristate "Test functions located in the hexdump module at runtime"
1786 config TEST_STRING_HELPERS
1787 tristate "Test functions located in the string_helpers module at runtime"
1790 tristate "Test strscpy*() family of functions at runtime"
1793 tristate "Test kstrto*() family of functions at runtime"
1796 tristate "Test printf() family of functions at runtime"
1799 tristate "Test bitmap_*() family of functions at runtime"
1801 Enable this option to test the bitmap functions at boot.
1805 config TEST_BITFIELD
1806 tristate "Test bitfield functions at runtime"
1808 Enable this option to test the bitfield functions at boot.
1813 tristate "Test functions located in the uuid module at runtime"
1816 tristate "Test the XArray code at runtime"
1818 config TEST_OVERFLOW
1819 tristate "Test check_*_overflow() functions at runtime"
1821 config TEST_RHASHTABLE
1822 tristate "Perform selftest on resizable hash table"
1824 Enable this option to test the rhashtable functions at boot.
1829 tristate "Perform selftest on hash functions"
1831 Enable this option to test the kernel's integer (<linux/hash.h>),
1832 string (<linux/stringhash.h>), and siphash (<linux/siphash.h>)
1833 hash functions on boot (or module load).
1835 This is intended to help people writing architecture-specific
1836 optimized versions. If unsure, say N.
1839 tristate "Perform selftest on IDA functions"
1842 tristate "Perform selftest on priority array manager"
1845 Enable this option to test priority array manager on boot
1850 config TEST_IRQ_TIMINGS
1851 bool "IRQ timings selftest"
1852 depends on IRQ_TIMINGS
1854 Enable this option to test the irq timings code on boot.
1859 tristate "Test module loading with 'hello world' module"
1862 This builds the "test_module" module that emits "Hello, world"
1863 on printk when loaded. It is designed to be used for basic
1864 evaluation of the module loading subsystem (for example when
1865 validating module verification). It lacks any extra dependencies,
1866 and will not normally be loaded by the system unless explicitly
1872 tristate "Test module for stress/performance analysis of vmalloc allocator"
1877 This builds the "test_vmalloc" module that should be used for
1878 stress and performance analysis. So, any new change for vmalloc
1879 subsystem can be evaluated from performance and stability point
1884 config TEST_USER_COPY
1885 tristate "Test user/kernel boundary protections"
1888 This builds the "test_user_copy" module that runs sanity checks
1889 on the copy_to/from_user infrastructure, making sure basic
1890 user/kernel boundary testing is working. If it fails to load,
1891 a regression has been detected in the user/kernel memory boundary
1897 tristate "Test BPF filter functionality"
1900 This builds the "test_bpf" module that runs various test vectors
1901 against the BPF interpreter or BPF JIT compiler depending on the
1902 current setting. This is in particular useful for BPF JIT compiler
1903 development, but also to run regression tests against changes in
1904 the interpreter code. It also enables test stubs for eBPF maps and
1905 verifier used by user space verifier testsuite.
1909 config TEST_BLACKHOLE_DEV
1910 tristate "Test blackhole netdev functionality"
1913 This builds the "test_blackhole_dev" module that validates the
1914 data path through this blackhole netdev.
1918 config FIND_BIT_BENCHMARK
1919 tristate "Test find_bit functions"
1921 This builds the "test_find_bit" module that measure find_*_bit()
1922 functions performance.
1926 config TEST_FIRMWARE
1927 tristate "Test firmware loading via userspace interface"
1928 depends on FW_LOADER
1930 This builds the "test_firmware" module that creates a userspace
1931 interface for testing firmware loading. This can be used to
1932 control the triggering of firmware loading without needing an
1933 actual firmware-using device. The contents can be rechecked by
1939 tristate "sysctl test driver"
1940 depends on PROC_SYSCTL
1942 This builds the "test_sysctl" module. This driver enables to test the
1943 proc sysctl interfaces available to drivers safely without affecting
1944 production knobs which might alter system functionality.
1948 config SYSCTL_KUNIT_TEST
1949 bool "KUnit test for sysctl"
1952 This builds the proc sysctl unit test, which runs on boot.
1953 Tests the API contract and implementation correctness of sysctl.
1954 For more information on KUnit and unit tests in general please refer
1955 to the KUnit documentation in Documentation/dev-tools/kunit/.
1960 tristate "udelay test driver"
1962 This builds the "udelay_test" module that helps to make sure
1963 that udelay() is working properly.
1967 config TEST_STATIC_KEYS
1968 tristate "Test static keys"
1971 Test the static key interfaces.
1976 tristate "kmod stress tester"
1978 depends on NETDEVICES && NET_CORE && INET # for TUN
1985 Test the kernel's module loading mechanism: kmod. kmod implements
1986 support to load modules using the Linux kernel's usermode helper.
1987 This test provides a series of tests against kmod.
1989 Although technically you can either build test_kmod as a module or
1990 into the kernel we disallow building it into the kernel since
1991 it stress tests request_module() and this will very likely cause
1992 some issues by taking over precious threads available from other
1993 module load requests, ultimately this could be fatal.
1997 tools/testing/selftests/kmod/kmod.sh --help
2001 config TEST_DEBUG_VIRTUAL
2002 tristate "Test CONFIG_DEBUG_VIRTUAL feature"
2003 depends on DEBUG_VIRTUAL
2005 Test the kernel's ability to detect incorrect calls to
2006 virt_to_phys() done against the non-linear part of the
2007 kernel's virtual address map.
2011 config TEST_MEMCAT_P
2012 tristate "Test memcat_p() helper function"
2014 Test the memcat_p() helper for correctly merging two
2015 pointer arrays together.
2019 config TEST_LIVEPATCH
2020 tristate "Test livepatching"
2022 depends on DYNAMIC_DEBUG
2023 depends on LIVEPATCH
2026 Test kernel livepatching features for correctness. The tests will
2027 load test modules that will be livepatched in various scenarios.
2029 To run all the livepatching tests:
2031 make -C tools/testing/selftests TARGETS=livepatch run_tests
2033 Alternatively, individual tests may be invoked:
2035 tools/testing/selftests/livepatch/test-callbacks.sh
2036 tools/testing/selftests/livepatch/test-livepatch.sh
2037 tools/testing/selftests/livepatch/test-shadow-vars.sh
2042 tristate "Perform selftest on object aggreration manager"
2046 Enable this option to test object aggregation manager on boot
2050 config TEST_STACKINIT
2051 tristate "Test level of stack variable initialization"
2053 Test if the kernel is zero-initializing stack variables and
2054 padding. Coverage is controlled by compiler flags,
2055 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2056 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2061 tristate "Test heap/page initialization"
2063 Test if the kernel is zero-initializing heap and page allocations.
2064 This can be useful to test init_on_alloc and init_on_free features.
2068 endif # RUNTIME_TESTING_MENU
2073 This option adds a kernel parameter 'memtest', which allows memtest
2075 memtest=0, mean disabled; -- default
2076 memtest=1, mean do 1 test pattern;
2078 memtest=17, mean do 17 test patterns.
2079 If you are unsure how to answer this question, answer N.
2081 config BUG_ON_DATA_CORRUPTION
2082 bool "Trigger a BUG when data corruption is detected"
2085 Select this option if the kernel should BUG when it encounters
2086 data corruption in kernel memory structures when they get checked
2091 source "samples/Kconfig"
2093 source "lib/Kconfig.kgdb"
2095 source "lib/Kconfig.ubsan"
2097 config ARCH_HAS_DEVMEM_IS_ALLOWED
2100 config STRICT_DEVMEM
2101 bool "Filter access to /dev/mem"
2102 depends on MMU && DEVMEM
2103 depends on ARCH_HAS_DEVMEM_IS_ALLOWED
2104 default y if PPC || X86 || ARM64
2106 If this option is disabled, you allow userspace (root) access to all
2107 of memory, including kernel and userspace memory. Accidental
2108 access to this is obviously disastrous, but specific access can
2109 be used by people debugging the kernel. Note that with PAT support
2110 enabled, even in this case there are restrictions on /dev/mem
2111 use due to the cache aliasing requirements.
2113 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
2114 file only allows userspace access to PCI space and the BIOS code and
2115 data regions. This is sufficient for dosemu and X and all common
2120 config IO_STRICT_DEVMEM
2121 bool "Filter I/O access to /dev/mem"
2122 depends on STRICT_DEVMEM
2124 If this option is disabled, you allow userspace (root) access to all
2125 io-memory regardless of whether a driver is actively using that
2126 range. Accidental access to this is obviously disastrous, but
2127 specific access can be used by people debugging kernel drivers.
2129 If this option is switched on, the /dev/mem file only allows
2130 userspace access to *idle* io-memory ranges (see /proc/iomem) This
2131 may break traditional users of /dev/mem (dosemu, legacy X, etc...)
2132 if the driver using a given range cannot be disabled.
2136 source "arch/$(SRCARCH)/Kconfig.debug"
2138 endmenu # Kernel hacking
projects / releases.git / blob