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 config SYMBOLIC_ERRNAME
168 bool "Support symbolic error names in printf"
171 If you say Y here, the kernel's printf implementation will
172 be able to print symbolic error names such as ENOSPC instead
173 of the number 28. It makes the kernel image slightly larger
174 (about 3KB), but can make the kernel logs easier to read.
176 endmenu # "printk and dmesg options"
178 menu "Compile-time checks and compiler options"
181 bool "Compile the kernel with debug info"
182 depends on DEBUG_KERNEL && !COMPILE_TEST
184 If you say Y here the resulting kernel image will include
185 debugging info resulting in a larger kernel image.
186 This adds debug symbols to the kernel and modules (gcc -g), and
187 is needed if you intend to use kernel crashdump or binary object
188 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
189 Say Y here only if you plan to debug the kernel.
193 config DEBUG_INFO_REDUCED
194 bool "Reduce debugging information"
195 depends on DEBUG_INFO
197 If you say Y here gcc is instructed to generate less debugging
198 information for structure types. This means that tools that
199 need full debugging information (like kgdb or systemtap) won't
200 be happy. But if you merely need debugging information to
201 resolve line numbers there is no loss. Advantage is that
202 build directory object sizes shrink dramatically over a full
203 DEBUG_INFO build and compile times are reduced too.
204 Only works with newer gcc versions.
206 config DEBUG_INFO_SPLIT
207 bool "Produce split debuginfo in .dwo files"
208 depends on DEBUG_INFO
209 depends on $(cc-option,-gsplit-dwarf)
211 Generate debug info into separate .dwo files. This significantly
212 reduces the build directory size for builds with DEBUG_INFO,
213 because it stores the information only once on disk in .dwo
214 files instead of multiple times in object files and executables.
215 In addition the debug information is also compressed.
217 Requires recent gcc (4.7+) and recent gdb/binutils.
218 Any tool that packages or reads debug information would need
219 to know about the .dwo files and include them.
220 Incompatible with older versions of ccache.
222 config DEBUG_INFO_DWARF4
223 bool "Generate dwarf4 debuginfo"
224 depends on DEBUG_INFO
225 depends on $(cc-option,-gdwarf-4)
227 Generate dwarf4 debug info. This requires recent versions
228 of gcc and gdb. It makes the debug information larger.
229 But it significantly improves the success of resolving
230 variables in gdb on optimized code.
232 config DEBUG_INFO_BTF
233 bool "Generate BTF typeinfo"
234 depends on DEBUG_INFO
236 Generate deduplicated BTF type information from DWARF debug info.
237 Turning this on expects presence of pahole tool, which will convert
238 DWARF type info into equivalent deduplicated BTF type info.
241 bool "Provide GDB scripts for kernel debugging"
242 depends on DEBUG_INFO
244 This creates the required links to GDB helper scripts in the
245 build directory. If you load vmlinux into gdb, the helper
246 scripts will be automatically imported by gdb as well, and
247 additional functions are available to analyze a Linux kernel
248 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
251 config ENABLE_MUST_CHECK
252 bool "Enable __must_check logic"
255 Enable the __must_check logic in the kernel build. Disable this to
256 suppress the "warning: ignoring return value of 'foo', declared with
257 attribute warn_unused_result" messages.
260 int "Warn for stack frames larger than (needs gcc 4.4)"
262 default 2048 if GCC_PLUGIN_LATENT_ENTROPY
263 default 1280 if (!64BIT && PARISC)
264 default 1024 if (!64BIT && !PARISC)
265 default 2048 if 64BIT
267 Tell gcc to warn at build time for stack frames larger than this.
268 Setting this too low will cause a lot of warnings.
269 Setting it to 0 disables the warning.
272 config STRIP_ASM_SYMS
273 bool "Strip assembler-generated symbols during link"
276 Strip internal assembler-generated symbols during a link (symbols
277 that look like '.Lxxx') so they don't pollute the output of
278 get_wchan() and suchlike.
281 bool "Generate readable assembler code"
282 depends on DEBUG_KERNEL
284 Disable some compiler optimizations that tend to generate human unreadable
285 assembler output. This may make the kernel slightly slower, but it helps
286 to keep kernel developers who have to stare a lot at assembler listings
290 bool "Debug Filesystem"
292 debugfs is a virtual file system that kernel developers use to put
293 debugging files into. Enable this option to be able to read and
294 write to these files.
296 For detailed documentation on the debugfs API, see
297 Documentation/filesystems/.
301 config HEADERS_INSTALL
302 bool "Install uapi headers to usr/include"
305 This option will install uapi headers (headers exported to user-space)
306 into the usr/include directory for use during the kernel build.
307 This is unneeded for building the kernel itself, but needed for some
308 user-space program samples. It is also needed by some features such
309 as uapi header sanity checks.
311 config OPTIMIZE_INLINING
314 This option determines if the kernel forces gcc to inline the functions
315 developers have marked 'inline'. Doing so takes away freedom from gcc to
316 do what it thinks is best, which is desirable for the gcc 3.x series of
317 compilers. The gcc 4.x series have a rewritten inlining algorithm and
318 enabling this option will generate a smaller kernel there. Hopefully
319 this algorithm is so good that allowing gcc 4.x and above to make the
320 decision will become the default in the future. Until then this option
321 is there to test gcc for this.
323 config DEBUG_SECTION_MISMATCH
324 bool "Enable full Section mismatch analysis"
326 The section mismatch analysis checks if there are illegal
327 references from one section to another section.
328 During linktime or runtime, some sections are dropped;
329 any use of code/data previously in these sections would
330 most likely result in an oops.
331 In the code, functions and variables are annotated with
332 __init,, etc. (see the full list in include/linux/init.h),
333 which results in the code/data being placed in specific sections.
334 The section mismatch analysis is always performed after a full
335 kernel build, and enabling this option causes the following
336 additional step to occur:
337 - Add the option -fno-inline-functions-called-once to gcc commands.
338 When inlining a function annotated with __init in a non-init
339 function, we would lose the section information and thus
340 the analysis would not catch the illegal reference.
341 This option tells gcc to inline less (but it does result in
344 config SECTION_MISMATCH_WARN_ONLY
345 bool "Make section mismatch errors non-fatal"
348 If you say N here, the build process will fail if there are any
349 section mismatch, instead of just throwing warnings.
354 # Select this config option from the architecture Kconfig, if it
355 # is preferred to always offer frame pointers as a config
356 # option on the architecture (regardless of KERNEL_DEBUG):
358 config ARCH_WANT_FRAME_POINTERS
362 bool "Compile the kernel with frame pointers"
363 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
364 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
366 If you say Y here the resulting kernel image will be slightly
367 larger and slower, but it gives very useful debugging information
368 in case of kernel bugs. (precise oopses/stacktraces/warnings)
370 config STACK_VALIDATION
371 bool "Compile-time stack metadata validation"
372 depends on HAVE_STACK_VALIDATION
375 Add compile-time checks to validate stack metadata, including frame
376 pointers (if CONFIG_FRAME_POINTER is enabled). This helps ensure
377 that runtime stack traces are more reliable.
379 This is also a prerequisite for generation of ORC unwind data, which
380 is needed for CONFIG_UNWINDER_ORC.
382 For more information, see
383 tools/objtool/Documentation/stack-validation.txt.
385 config DEBUG_FORCE_WEAK_PER_CPU
386 bool "Force weak per-cpu definitions"
387 depends on DEBUG_KERNEL
389 s390 and alpha require percpu variables in modules to be
390 defined weak to work around addressing range issue which
391 puts the following two restrictions on percpu variable
394 1. percpu symbols must be unique whether static or not
395 2. percpu variables can't be defined inside a function
397 To ensure that generic code follows the above rules, this
398 option forces all percpu variables to be defined as weak.
400 endmenu # "Compiler options"
402 menu "Generic Kernel Debugging Instruments"
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
437 source "lib/Kconfig.kgdb"
439 source "lib/Kconfig.ubsan"
444 bool "Kernel debugging"
446 Say Y here if you are developing drivers or trying to debug and
447 identify kernel problems.
450 bool "Miscellaneous debug code"
452 depends on DEBUG_KERNEL
454 Say Y here if you need to enable miscellaneous debug code that should
455 be under a more specific debug option but isn't.
458 menu "Memory Debugging"
460 source "mm/Kconfig.debug"
463 bool "Debug object operations"
464 depends on DEBUG_KERNEL
466 If you say Y here, additional code will be inserted into the
467 kernel to track the life time of various objects and validate
468 the operations on those objects.
470 config DEBUG_OBJECTS_SELFTEST
471 bool "Debug objects selftest"
472 depends on DEBUG_OBJECTS
474 This enables the selftest of the object debug code.
476 config DEBUG_OBJECTS_FREE
477 bool "Debug objects in freed memory"
478 depends on DEBUG_OBJECTS
480 This enables checks whether a k/v free operation frees an area
481 which contains an object which has not been deactivated
482 properly. This can make kmalloc/kfree-intensive workloads
485 config DEBUG_OBJECTS_TIMERS
486 bool "Debug timer objects"
487 depends on DEBUG_OBJECTS
489 If you say Y here, additional code will be inserted into the
490 timer routines to track the life time of timer objects and
491 validate the timer operations.
493 config DEBUG_OBJECTS_WORK
494 bool "Debug work objects"
495 depends on DEBUG_OBJECTS
497 If you say Y here, additional code will be inserted into the
498 work queue routines to track the life time of work objects and
499 validate the work operations.
501 config DEBUG_OBJECTS_RCU_HEAD
502 bool "Debug RCU callbacks objects"
503 depends on DEBUG_OBJECTS
505 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
507 config DEBUG_OBJECTS_PERCPU_COUNTER
508 bool "Debug percpu counter objects"
509 depends on DEBUG_OBJECTS
511 If you say Y here, additional code will be inserted into the
512 percpu counter routines to track the life time of percpu counter
513 objects and validate the percpu counter operations.
515 config DEBUG_OBJECTS_ENABLE_DEFAULT
516 int "debug_objects bootup default value (0-1)"
519 depends on DEBUG_OBJECTS
521 Debug objects boot parameter default value
524 bool "Debug slab memory allocations"
525 depends on DEBUG_KERNEL && SLAB
527 Say Y here to have the kernel do limited verification on memory
528 allocation as well as poisoning memory on free to catch use of freed
529 memory. This can make kmalloc/kfree-intensive workloads much slower.
532 bool "SLUB debugging on by default"
533 depends on SLUB && SLUB_DEBUG
536 Boot with debugging on by default. SLUB boots by default with
537 the runtime debug capabilities switched off. Enabling this is
538 equivalent to specifying the "slub_debug" parameter on boot.
539 There is no support for more fine grained debug control like
540 possible with slub_debug=xxx. SLUB debugging may be switched
541 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
546 bool "Enable SLUB performance statistics"
547 depends on SLUB && SYSFS
549 SLUB statistics are useful to debug SLUBs allocation behavior in
550 order find ways to optimize the allocator. This should never be
551 enabled for production use since keeping statistics slows down
552 the allocator by a few percentage points. The slabinfo command
553 supports the determination of the most active slabs to figure
554 out which slabs are relevant to a particular load.
555 Try running: slabinfo -DA
557 config HAVE_DEBUG_KMEMLEAK
560 config DEBUG_KMEMLEAK
561 bool "Kernel memory leak detector"
562 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
564 select STACKTRACE if STACKTRACE_SUPPORT
568 Say Y here if you want to enable the memory leak
569 detector. The memory allocation/freeing is traced in a way
570 similar to the Boehm's conservative garbage collector, the
571 difference being that the orphan objects are not freed but
572 only shown in /sys/kernel/debug/kmemleak. Enabling this
573 feature will introduce an overhead to memory
574 allocations. See Documentation/dev-tools/kmemleak.rst for more
577 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
578 of finding leaks due to the slab objects poisoning.
580 In order to access the kmemleak file, debugfs needs to be
581 mounted (usually at /sys/kernel/debug).
583 config DEBUG_KMEMLEAK_MEM_POOL_SIZE
584 int "Kmemleak memory pool size"
585 depends on DEBUG_KMEMLEAK
589 Kmemleak must track all the memory allocations to avoid
590 reporting false positives. Since memory may be allocated or
591 freed before kmemleak is fully initialised, use a static pool
592 of metadata objects to track such callbacks. After kmemleak is
593 fully initialised, this memory pool acts as an emergency one
594 if slab allocations fail.
596 config DEBUG_KMEMLEAK_TEST
597 tristate "Simple test for the kernel memory leak detector"
598 depends on DEBUG_KMEMLEAK && m
600 This option enables a module that explicitly leaks memory.
604 config DEBUG_KMEMLEAK_DEFAULT_OFF
605 bool "Default kmemleak to off"
606 depends on DEBUG_KMEMLEAK
608 Say Y here to disable kmemleak by default. It can then be enabled
609 on the command line via kmemleak=on.
611 config DEBUG_KMEMLEAK_AUTO_SCAN
612 bool "Enable kmemleak auto scan thread on boot up"
614 depends on DEBUG_KMEMLEAK
616 Depending on the cpu, kmemleak scan may be cpu intensive and can
617 stall user tasks at times. This option enables/disables automatic
618 kmemleak scan at boot up.
620 Say N here to disable kmemleak auto scan thread to stop automatic
621 scanning. Disabling this option disables automatic reporting of
626 config DEBUG_STACK_USAGE
627 bool "Stack utilization instrumentation"
628 depends on DEBUG_KERNEL && !IA64
630 Enables the display of the minimum amount of free stack which each
631 task has ever had available in the sysrq-T and sysrq-P debug output.
633 This option will slow down process creation somewhat.
637 depends on DEBUG_KERNEL
639 Enable this to turn on extended checks in the virtual-memory system
640 that may impact performance.
644 config DEBUG_VM_VMACACHE
645 bool "Debug VMA caching"
648 Enable this to turn on VMA caching debug information. Doing so
649 can cause significant overhead, so only enable it in non-production
655 bool "Debug VM red-black trees"
658 Enable VM red-black tree debugging information and extra validations.
662 config DEBUG_VM_PGFLAGS
663 bool "Debug page-flags operations"
666 Enables extra validation on page flags operations.
670 config ARCH_HAS_DEBUG_VIRTUAL
674 bool "Debug VM translations"
675 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
677 Enable some costly sanity checks in virtual to page code. This can
678 catch mistakes with virt_to_page() and friends.
682 config DEBUG_NOMMU_REGIONS
683 bool "Debug the global anon/private NOMMU mapping region tree"
684 depends on DEBUG_KERNEL && !MMU
686 This option causes the global tree of anonymous and private mapping
687 regions to be regularly checked for invalid topology.
689 config DEBUG_MEMORY_INIT
690 bool "Debug memory initialisation" if EXPERT
693 Enable this for additional checks during memory initialisation.
694 The sanity checks verify aspects of the VM such as the memory model
695 and other information provided by the architecture. Verbose
696 information will be printed at KERN_DEBUG loglevel depending
697 on the mminit_loglevel= command-line option.
701 config MEMORY_NOTIFIER_ERROR_INJECT
702 tristate "Memory hotplug notifier error injection module"
703 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
705 This option provides the ability to inject artificial errors to
706 memory hotplug notifier chain callbacks. It is controlled through
707 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
709 If the notifier call chain should be failed with some events
710 notified, write the error code to "actions/<notifier event>/error".
712 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
714 # cd /sys/kernel/debug/notifier-error-inject/memory
715 # echo -12 > actions/MEM_GOING_OFFLINE/error
716 # echo offline > /sys/devices/system/memory/memoryXXX/state
717 bash: echo: write error: Cannot allocate memory
719 To compile this code as a module, choose M here: the module will
720 be called memory-notifier-error-inject.
724 config DEBUG_PER_CPU_MAPS
725 bool "Debug access to per_cpu maps"
726 depends on DEBUG_KERNEL
729 Say Y to verify that the per_cpu map being accessed has
730 been set up. This adds a fair amount of code to kernel memory
731 and decreases performance.
736 bool "Highmem debugging"
737 depends on DEBUG_KERNEL && HIGHMEM
739 This option enables additional error checking for high memory
740 systems. Disable for production systems.
742 config HAVE_DEBUG_STACKOVERFLOW
745 config DEBUG_STACKOVERFLOW
746 bool "Check for stack overflows"
747 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
749 Say Y here if you want to check for overflows of kernel, IRQ
750 and exception stacks (if your architecture uses them). This
751 option will show detailed messages if free stack space drops
752 below a certain limit.
754 These kinds of bugs usually occur when call-chains in the
755 kernel get too deep, especially when interrupts are
758 Use this in cases where you see apparently random memory
759 corruption, especially if it appears in 'struct thread_info'
761 If in doubt, say "N".
763 source "lib/Kconfig.kasan"
765 endmenu # "Memory Debugging"
770 An architecture should select this when it can successfully
771 build and run with CONFIG_KCOV. This typically requires
772 disabling instrumentation for some early boot code.
774 config CC_HAS_SANCOV_TRACE_PC
775 def_bool $(cc-option,-fsanitize-coverage=trace-pc)
778 bool "Code coverage for fuzzing"
779 depends on ARCH_HAS_KCOV
780 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
782 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
784 KCOV exposes kernel code coverage information in a form suitable
785 for coverage-guided fuzzing (randomized testing).
787 If RANDOMIZE_BASE is enabled, PC values will not be stable across
788 different machines and across reboots. If you need stable PC values,
789 disable RANDOMIZE_BASE.
791 For more details, see Documentation/dev-tools/kcov.rst.
793 config KCOV_ENABLE_COMPARISONS
794 bool "Enable comparison operands collection by KCOV"
796 depends on $(cc-option,-fsanitize-coverage=trace-cmp)
798 KCOV also exposes operands of every comparison in the instrumented
799 code along with operand sizes and PCs of the comparison instructions.
800 These operands can be used by fuzzing engines to improve the quality
803 config KCOV_INSTRUMENT_ALL
804 bool "Instrument all code by default"
808 If you are doing generic system call fuzzing (like e.g. syzkaller),
809 then you will want to instrument the whole kernel and you should
810 say y here. If you are doing more targeted fuzzing (like e.g.
811 filesystem fuzzing with AFL) then you will want to enable coverage
812 for more specific subsets of files, and should say n here.
815 bool "Debug shared IRQ handlers"
816 depends on DEBUG_KERNEL
818 Enable this to generate a spurious interrupt as soon as a shared
819 interrupt handler is registered, and just before one is deregistered.
820 Drivers ought to be able to handle interrupts coming in at those
821 points; some don't and need to be caught.
823 menu "Debug Lockups and Hangs"
825 config LOCKUP_DETECTOR
828 config SOFTLOCKUP_DETECTOR
829 bool "Detect Soft Lockups"
830 depends on DEBUG_KERNEL && !S390
831 select LOCKUP_DETECTOR
833 Say Y here to enable the kernel to act as a watchdog to detect
836 Softlockups are bugs that cause the kernel to loop in kernel
837 mode for more than 20 seconds, without giving other tasks a
838 chance to run. The current stack trace is displayed upon
839 detection and the system will stay locked up.
841 config BOOTPARAM_SOFTLOCKUP_PANIC
842 bool "Panic (Reboot) On Soft Lockups"
843 depends on SOFTLOCKUP_DETECTOR
845 Say Y here to enable the kernel to panic on "soft lockups",
846 which are bugs that cause the kernel to loop in kernel
847 mode for more than 20 seconds (configurable using the watchdog_thresh
848 sysctl), without giving other tasks a chance to run.
850 The panic can be used in combination with panic_timeout,
851 to cause the system to reboot automatically after a
852 lockup has been detected. This feature is useful for
853 high-availability systems that have uptime guarantees and
854 where a lockup must be resolved ASAP.
858 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
860 depends on SOFTLOCKUP_DETECTOR
862 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
863 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
865 config HARDLOCKUP_DETECTOR_PERF
867 select SOFTLOCKUP_DETECTOR
870 # Enables a timestamp based low pass filter to compensate for perf based
871 # hard lockup detection which runs too fast due to turbo modes.
873 config HARDLOCKUP_CHECK_TIMESTAMP
877 # arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard
878 # lockup detector rather than the perf based detector.
880 config HARDLOCKUP_DETECTOR
881 bool "Detect Hard Lockups"
882 depends on DEBUG_KERNEL && !S390
883 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH
884 select LOCKUP_DETECTOR
885 select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF
886 select HARDLOCKUP_DETECTOR_ARCH if HAVE_HARDLOCKUP_DETECTOR_ARCH
888 Say Y here to enable the kernel to act as a watchdog to detect
891 Hardlockups are bugs that cause the CPU to loop in kernel mode
892 for more than 10 seconds, without letting other interrupts have a
893 chance to run. The current stack trace is displayed upon detection
894 and the system will stay locked up.
896 config BOOTPARAM_HARDLOCKUP_PANIC
897 bool "Panic (Reboot) On Hard Lockups"
898 depends on HARDLOCKUP_DETECTOR
900 Say Y here to enable the kernel to panic on "hard lockups",
901 which are bugs that cause the kernel to loop in kernel
902 mode with interrupts disabled for more than 10 seconds (configurable
903 using the watchdog_thresh sysctl).
907 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
909 depends on HARDLOCKUP_DETECTOR
911 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
912 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
914 config DETECT_HUNG_TASK
915 bool "Detect Hung Tasks"
916 depends on DEBUG_KERNEL
917 default SOFTLOCKUP_DETECTOR
919 Say Y here to enable the kernel to detect "hung tasks",
920 which are bugs that cause the task to be stuck in
921 uninterruptible "D" state indefinitely.
923 When a hung task is detected, the kernel will print the
924 current stack trace (which you should report), but the
925 task will stay in uninterruptible state. If lockdep is
926 enabled then all held locks will also be reported. This
927 feature has negligible overhead.
929 config DEFAULT_HUNG_TASK_TIMEOUT
930 int "Default timeout for hung task detection (in seconds)"
931 depends on DETECT_HUNG_TASK
934 This option controls the default timeout (in seconds) used
935 to determine when a task has become non-responsive and should
938 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
939 sysctl or by writing a value to
940 /proc/sys/kernel/hung_task_timeout_secs.
942 A timeout of 0 disables the check. The default is two minutes.
943 Keeping the default should be fine in most cases.
945 config BOOTPARAM_HUNG_TASK_PANIC
946 bool "Panic (Reboot) On Hung Tasks"
947 depends on DETECT_HUNG_TASK
949 Say Y here to enable the kernel to panic on "hung tasks",
950 which are bugs that cause the kernel to leave a task stuck
951 in uninterruptible "D" state.
953 The panic can be used in combination with panic_timeout,
954 to cause the system to reboot automatically after a
955 hung task has been detected. This feature is useful for
956 high-availability systems that have uptime guarantees and
957 where a hung tasks must be resolved ASAP.
961 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
963 depends on DETECT_HUNG_TASK
965 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
966 default 1 if BOOTPARAM_HUNG_TASK_PANIC
969 bool "Detect Workqueue Stalls"
970 depends on DEBUG_KERNEL
972 Say Y here to enable stall detection on workqueues. If a
973 worker pool doesn't make forward progress on a pending work
974 item for over a given amount of time, 30s by default, a
975 warning message is printed along with dump of workqueue
976 state. This can be configured through kernel parameter
977 "workqueue.watchdog_thresh" and its sysfs counterpart.
979 endmenu # "Debug lockups and hangs"
984 Say Y here to enable the kernel to panic when it oopses. This
985 has the same effect as setting oops=panic on the kernel command
988 This feature is useful to ensure that the kernel does not do
989 anything erroneous after an oops which could result in data
990 corruption or other issues.
994 config PANIC_ON_OOPS_VALUE
997 default 0 if !PANIC_ON_OOPS
998 default 1 if PANIC_ON_OOPS
1000 config PANIC_TIMEOUT
1004 Set the timeout value (in seconds) until a reboot occurs when the
1005 the kernel panics. If n = 0, then we wait forever. A timeout
1006 value n > 0 will wait n seconds before rebooting, while a timeout
1007 value n < 0 will reboot immediately.
1010 bool "Collect scheduler debugging info"
1011 depends on DEBUG_KERNEL && PROC_FS
1014 If you say Y here, the /proc/sched_debug file will be provided
1015 that can help debug the scheduler. The runtime overhead of this
1023 bool "Collect scheduler statistics"
1024 depends on DEBUG_KERNEL && PROC_FS
1027 If you say Y here, additional code will be inserted into the
1028 scheduler and related routines to collect statistics about
1029 scheduler behavior and provide them in /proc/schedstat. These
1030 stats may be useful for both tuning and debugging the scheduler
1031 If you aren't debugging the scheduler or trying to tune a specific
1032 application, you can say N to avoid the very slight overhead
1035 config SCHED_STACK_END_CHECK
1036 bool "Detect stack corruption on calls to schedule()"
1037 depends on DEBUG_KERNEL
1040 This option checks for a stack overrun on calls to schedule().
1041 If the stack end location is found to be over written always panic as
1042 the content of the corrupted region can no longer be trusted.
1043 This is to ensure no erroneous behaviour occurs which could result in
1044 data corruption or a sporadic crash at a later stage once the region
1045 is examined. The runtime overhead introduced is minimal.
1047 config DEBUG_TIMEKEEPING
1048 bool "Enable extra timekeeping sanity checking"
1050 This option will enable additional timekeeping sanity checks
1051 which may be helpful when diagnosing issues where timekeeping
1052 problems are suspected.
1054 This may include checks in the timekeeping hotpaths, so this
1055 option may have a (very small) performance impact to some
1060 config DEBUG_PREEMPT
1061 bool "Debug preemptible kernel"
1062 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
1065 If you say Y here then the kernel will use a debug variant of the
1066 commonly used smp_processor_id() function and will print warnings
1067 if kernel code uses it in a preemption-unsafe way. Also, the kernel
1068 will detect preemption count underflows.
1070 menu "Lock Debugging (spinlocks, mutexes, etc...)"
1072 config LOCK_DEBUGGING_SUPPORT
1074 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1077 config PROVE_LOCKING
1078 bool "Lock debugging: prove locking correctness"
1079 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1081 select DEBUG_SPINLOCK
1082 select DEBUG_MUTEXES
1083 select DEBUG_RT_MUTEXES if RT_MUTEXES
1085 select DEBUG_WW_MUTEX_SLOWPATH
1086 select DEBUG_LOCK_ALLOC
1087 select TRACE_IRQFLAGS
1090 This feature enables the kernel to prove that all locking
1091 that occurs in the kernel runtime is mathematically
1092 correct: that under no circumstance could an arbitrary (and
1093 not yet triggered) combination of observed locking
1094 sequences (on an arbitrary number of CPUs, running an
1095 arbitrary number of tasks and interrupt contexts) cause a
1098 In short, this feature enables the kernel to report locking
1099 related deadlocks before they actually occur.
1101 The proof does not depend on how hard and complex a
1102 deadlock scenario would be to trigger: how many
1103 participant CPUs, tasks and irq-contexts would be needed
1104 for it to trigger. The proof also does not depend on
1105 timing: if a race and a resulting deadlock is possible
1106 theoretically (no matter how unlikely the race scenario
1107 is), it will be proven so and will immediately be
1108 reported by the kernel (once the event is observed that
1109 makes the deadlock theoretically possible).
1111 If a deadlock is impossible (i.e. the locking rules, as
1112 observed by the kernel, are mathematically correct), the
1113 kernel reports nothing.
1115 NOTE: this feature can also be enabled for rwlocks, mutexes
1116 and rwsems - in which case all dependencies between these
1117 different locking variants are observed and mapped too, and
1118 the proof of observed correctness is also maintained for an
1119 arbitrary combination of these separate locking variants.
1121 For more details, see Documentation/locking/lockdep-design.rst.
1124 bool "Lock usage statistics"
1125 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1127 select DEBUG_SPINLOCK
1128 select DEBUG_MUTEXES
1129 select DEBUG_RT_MUTEXES if RT_MUTEXES
1130 select DEBUG_LOCK_ALLOC
1133 This feature enables tracking lock contention points
1135 For more details, see Documentation/locking/lockstat.rst
1137 This also enables lock events required by "perf lock",
1139 If you want to use "perf lock", you also need to turn on
1140 CONFIG_EVENT_TRACING.
1142 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1143 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1145 config DEBUG_RT_MUTEXES
1146 bool "RT Mutex debugging, deadlock detection"
1147 depends on DEBUG_KERNEL && RT_MUTEXES
1149 This allows rt mutex semantics violations and rt mutex related
1150 deadlocks (lockups) to be detected and reported automatically.
1152 config DEBUG_SPINLOCK
1153 bool "Spinlock and rw-lock debugging: basic checks"
1154 depends on DEBUG_KERNEL
1155 select UNINLINE_SPIN_UNLOCK
1157 Say Y here and build SMP to catch missing spinlock initialization
1158 and certain other kinds of spinlock errors commonly made. This is
1159 best used in conjunction with the NMI watchdog so that spinlock
1160 deadlocks are also debuggable.
1162 config DEBUG_MUTEXES
1163 bool "Mutex debugging: basic checks"
1164 depends on DEBUG_KERNEL
1166 This feature allows mutex semantics violations to be detected and
1169 config DEBUG_WW_MUTEX_SLOWPATH
1170 bool "Wait/wound mutex debugging: Slowpath testing"
1171 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1172 select DEBUG_LOCK_ALLOC
1173 select DEBUG_SPINLOCK
1174 select DEBUG_MUTEXES
1176 This feature enables slowpath testing for w/w mutex users by
1177 injecting additional -EDEADLK wound/backoff cases. Together with
1178 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1179 will test all possible w/w mutex interface abuse with the
1180 exception of simply not acquiring all the required locks.
1181 Note that this feature can introduce significant overhead, so
1182 it really should not be enabled in a production or distro kernel,
1183 even a debug kernel. If you are a driver writer, enable it. If
1184 you are a distro, do not.
1187 bool "RW Semaphore debugging: basic checks"
1188 depends on DEBUG_KERNEL
1190 This debugging feature allows mismatched rw semaphore locks
1191 and unlocks to be detected and reported.
1193 config DEBUG_LOCK_ALLOC
1194 bool "Lock debugging: detect incorrect freeing of live locks"
1195 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1196 select DEBUG_SPINLOCK
1197 select DEBUG_MUTEXES
1198 select DEBUG_RT_MUTEXES if RT_MUTEXES
1201 This feature will check whether any held lock (spinlock, rwlock,
1202 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1203 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1204 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1205 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1206 held during task exit.
1210 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1212 select FRAME_POINTER if !MIPS && !PPC && !ARM && !S390 && !MICROBLAZE && !ARC && !X86
1216 config LOCKDEP_SMALL
1219 config DEBUG_LOCKDEP
1220 bool "Lock dependency engine debugging"
1221 depends on DEBUG_KERNEL && LOCKDEP
1223 If you say Y here, the lock dependency engine will do
1224 additional runtime checks to debug itself, at the price
1225 of more runtime overhead.
1227 config DEBUG_ATOMIC_SLEEP
1228 bool "Sleep inside atomic section checking"
1229 select PREEMPT_COUNT
1230 depends on DEBUG_KERNEL
1231 depends on !ARCH_NO_PREEMPT
1233 If you say Y here, various routines which may sleep will become very
1234 noisy if they are called inside atomic sections: when a spinlock is
1235 held, inside an rcu read side critical section, inside preempt disabled
1236 sections, inside an interrupt, etc...
1238 config DEBUG_LOCKING_API_SELFTESTS
1239 bool "Locking API boot-time self-tests"
1240 depends on DEBUG_KERNEL
1242 Say Y here if you want the kernel to run a short self-test during
1243 bootup. The self-test checks whether common types of locking bugs
1244 are detected by debugging mechanisms or not. (if you disable
1245 lock debugging then those bugs wont be detected of course.)
1246 The following locking APIs are covered: spinlocks, rwlocks,
1249 config LOCK_TORTURE_TEST
1250 tristate "torture tests for locking"
1251 depends on DEBUG_KERNEL
1254 This option provides a kernel module that runs torture tests
1255 on kernel locking primitives. The kernel module may be built
1256 after the fact on the running kernel to be tested, if desired.
1258 Say Y here if you want kernel locking-primitive torture tests
1259 to be built into the kernel.
1260 Say M if you want these torture tests to build as a module.
1261 Say N if you are unsure.
1263 config WW_MUTEX_SELFTEST
1264 tristate "Wait/wound mutex selftests"
1266 This option provides a kernel module that runs tests on the
1267 on the struct ww_mutex locking API.
1269 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1270 with this test harness.
1272 Say M if you want these self tests to build as a module.
1273 Say N if you are unsure.
1275 endmenu # lock debugging
1277 config TRACE_IRQFLAGS
1280 Enables hooks to interrupt enabling and disabling for
1281 either tracing or lock debugging.
1284 bool "Stack backtrace support"
1285 depends on STACKTRACE_SUPPORT
1287 This option causes the kernel to create a /proc/pid/stack for
1288 every process, showing its current stack trace.
1289 It is also used by various kernel debugging features that require
1290 stack trace generation.
1292 config WARN_ALL_UNSEEDED_RANDOM
1293 bool "Warn for all uses of unseeded randomness"
1296 Some parts of the kernel contain bugs relating to their use of
1297 cryptographically secure random numbers before it's actually possible
1298 to generate those numbers securely. This setting ensures that these
1299 flaws don't go unnoticed, by enabling a message, should this ever
1300 occur. This will allow people with obscure setups to know when things
1301 are going wrong, so that they might contact developers about fixing
1304 Unfortunately, on some models of some architectures getting
1305 a fully seeded CRNG is extremely difficult, and so this can
1306 result in dmesg getting spammed for a surprisingly long
1307 time. This is really bad from a security perspective, and
1308 so architecture maintainers really need to do what they can
1309 to get the CRNG seeded sooner after the system is booted.
1310 However, since users cannot do anything actionable to
1311 address this, by default the kernel will issue only a single
1312 warning for the first use of unseeded randomness.
1314 Say Y here if you want to receive warnings for all uses of
1315 unseeded randomness. This will be of use primarily for
1316 those developers interested in improving the security of
1317 Linux kernels running on their architecture (or
1320 config DEBUG_KOBJECT
1321 bool "kobject debugging"
1322 depends on DEBUG_KERNEL
1324 If you say Y here, some extra kobject debugging messages will be sent
1327 config DEBUG_KOBJECT_RELEASE
1328 bool "kobject release debugging"
1329 depends on DEBUG_OBJECTS_TIMERS
1331 kobjects are reference counted objects. This means that their
1332 last reference count put is not predictable, and the kobject can
1333 live on past the point at which a driver decides to drop it's
1334 initial reference to the kobject gained on allocation. An
1335 example of this would be a struct device which has just been
1338 However, some buggy drivers assume that after such an operation,
1339 the memory backing the kobject can be immediately freed. This
1340 goes completely against the principles of a refcounted object.
1342 If you say Y here, the kernel will delay the release of kobjects
1343 on the last reference count to improve the visibility of this
1344 kind of kobject release bug.
1346 config HAVE_DEBUG_BUGVERBOSE
1349 config DEBUG_BUGVERBOSE
1350 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
1351 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
1354 Say Y here to make BUG() panics output the file name and line number
1355 of the BUG call as well as the EIP and oops trace. This aids
1356 debugging but costs about 70-100K of memory.
1358 menu "Debug kernel data structures"
1361 bool "Debug linked list manipulation"
1362 depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION
1364 Enable this to turn on extended checks in the linked-list
1370 bool "Debug priority linked list manipulation"
1371 depends on DEBUG_KERNEL
1373 Enable this to turn on extended checks in the priority-ordered
1374 linked-list (plist) walking routines. This checks the entire
1375 list multiple times during each manipulation.
1380 bool "Debug SG table operations"
1381 depends on DEBUG_KERNEL
1383 Enable this to turn on checks on scatter-gather tables. This can
1384 help find problems with drivers that do not properly initialize
1389 config DEBUG_NOTIFIERS
1390 bool "Debug notifier call chains"
1391 depends on DEBUG_KERNEL
1393 Enable this to turn on sanity checking for notifier call chains.
1394 This is most useful for kernel developers to make sure that
1395 modules properly unregister themselves from notifier chains.
1396 This is a relatively cheap check but if you care about maximum
1399 config BUG_ON_DATA_CORRUPTION
1400 bool "Trigger a BUG when data corruption is detected"
1403 Select this option if the kernel should BUG when it encounters
1404 data corruption in kernel memory structures when they get checked
1411 config DEBUG_CREDENTIALS
1412 bool "Debug credential management"
1413 depends on DEBUG_KERNEL
1415 Enable this to turn on some debug checking for credential
1416 management. The additional code keeps track of the number of
1417 pointers from task_structs to any given cred struct, and checks to
1418 see that this number never exceeds the usage count of the cred
1421 Furthermore, if SELinux is enabled, this also checks that the
1422 security pointer in the cred struct is never seen to be invalid.
1426 source "kernel/rcu/Kconfig.debug"
1428 config DEBUG_WQ_FORCE_RR_CPU
1429 bool "Force round-robin CPU selection for unbound work items"
1430 depends on DEBUG_KERNEL
1433 Workqueue used to implicitly guarantee that work items queued
1434 without explicit CPU specified are put on the local CPU. This
1435 guarantee is no longer true and while local CPU is still
1436 preferred work items may be put on foreign CPUs. Kernel
1437 parameter "workqueue.debug_force_rr_cpu" is added to force
1438 round-robin CPU selection to flush out usages which depend on the
1439 now broken guarantee. This config option enables the debug
1440 feature by default. When enabled, memory and cache locality will
1443 config DEBUG_BLOCK_EXT_DEVT
1444 bool "Force extended block device numbers and spread them"
1445 depends on DEBUG_KERNEL
1449 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1450 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1451 YOU ARE DOING. Distros, please enable this and fix whatever
1454 Conventionally, block device numbers are allocated from
1455 predetermined contiguous area. However, extended block area
1456 may introduce non-contiguous block device numbers. This
1457 option forces most block device numbers to be allocated from
1458 the extended space and spreads them to discover kernel or
1459 userland code paths which assume predetermined contiguous
1460 device number allocation.
1462 Note that turning on this debug option shuffles all the
1463 device numbers for all IDE and SCSI devices including libata
1464 ones, so root partition specified using device number
1465 directly (via rdev or root=MAJ:MIN) won't work anymore.
1466 Textual device names (root=/dev/sdXn) will continue to work.
1468 Say N if you are unsure.
1470 config CPU_HOTPLUG_STATE_CONTROL
1471 bool "Enable CPU hotplug state control"
1472 depends on DEBUG_KERNEL
1473 depends on HOTPLUG_CPU
1476 Allows to write steps between "offline" and "online" to the CPUs
1477 sysfs target file so states can be stepped granular. This is a debug
1478 option for now as the hotplug machinery cannot be stopped and
1479 restarted at arbitrary points yet.
1481 Say N if your are unsure.
1483 config NOTIFIER_ERROR_INJECTION
1484 tristate "Notifier error injection"
1485 depends on DEBUG_KERNEL
1488 This option provides the ability to inject artificial errors to
1489 specified notifier chain callbacks. It is useful to test the error
1490 handling of notifier call chain failures.
1494 config PM_NOTIFIER_ERROR_INJECT
1495 tristate "PM notifier error injection module"
1496 depends on PM && NOTIFIER_ERROR_INJECTION
1497 default m if PM_DEBUG
1499 This option provides the ability to inject artificial errors to
1500 PM notifier chain callbacks. It is controlled through debugfs
1501 interface /sys/kernel/debug/notifier-error-inject/pm
1503 If the notifier call chain should be failed with some events
1504 notified, write the error code to "actions/<notifier event>/error".
1506 Example: Inject PM suspend error (-12 = -ENOMEM)
1508 # cd /sys/kernel/debug/notifier-error-inject/pm/
1509 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1510 # echo mem > /sys/power/state
1511 bash: echo: write error: Cannot allocate memory
1513 To compile this code as a module, choose M here: the module will
1514 be called pm-notifier-error-inject.
1518 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1519 tristate "OF reconfig notifier error injection module"
1520 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1522 This option provides the ability to inject artificial errors to
1523 OF reconfig notifier chain callbacks. It is controlled
1524 through debugfs interface under
1525 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1527 If the notifier call chain should be failed with some events
1528 notified, write the error code to "actions/<notifier event>/error".
1530 To compile this code as a module, choose M here: the module will
1531 be called of-reconfig-notifier-error-inject.
1535 config NETDEV_NOTIFIER_ERROR_INJECT
1536 tristate "Netdev notifier error injection module"
1537 depends on NET && NOTIFIER_ERROR_INJECTION
1539 This option provides the ability to inject artificial errors to
1540 netdevice notifier chain callbacks. It is controlled through debugfs
1541 interface /sys/kernel/debug/notifier-error-inject/netdev
1543 If the notifier call chain should be failed with some events
1544 notified, write the error code to "actions/<notifier event>/error".
1546 Example: Inject netdevice mtu change error (-22 = -EINVAL)
1548 # cd /sys/kernel/debug/notifier-error-inject/netdev
1549 # echo -22 > actions/NETDEV_CHANGEMTU/error
1550 # ip link set eth0 mtu 1024
1551 RTNETLINK answers: Invalid argument
1553 To compile this code as a module, choose M here: the module will
1554 be called netdev-notifier-error-inject.
1558 config FUNCTION_ERROR_INJECTION
1560 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
1562 config FAULT_INJECTION
1563 bool "Fault-injection framework"
1564 depends on DEBUG_KERNEL
1566 Provide fault-injection framework.
1567 For more details, see Documentation/fault-injection/.
1570 bool "Fault-injection capability for kmalloc"
1571 depends on FAULT_INJECTION
1572 depends on SLAB || SLUB
1574 Provide fault-injection capability for kmalloc.
1576 config FAIL_PAGE_ALLOC
1577 bool "Fault-injection capabilitiy for alloc_pages()"
1578 depends on FAULT_INJECTION
1580 Provide fault-injection capability for alloc_pages().
1582 config FAIL_MAKE_REQUEST
1583 bool "Fault-injection capability for disk IO"
1584 depends on FAULT_INJECTION && BLOCK
1586 Provide fault-injection capability for disk IO.
1588 config FAIL_IO_TIMEOUT
1589 bool "Fault-injection capability for faking disk interrupts"
1590 depends on FAULT_INJECTION && BLOCK
1592 Provide fault-injection capability on end IO handling. This
1593 will make the block layer "forget" an interrupt as configured,
1594 thus exercising the error handling.
1596 Only works with drivers that use the generic timeout handling,
1597 for others it wont do anything.
1600 bool "Fault-injection capability for futexes"
1602 depends on FAULT_INJECTION && FUTEX
1604 Provide fault-injection capability for futexes.
1606 config FAULT_INJECTION_DEBUG_FS
1607 bool "Debugfs entries for fault-injection capabilities"
1608 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1610 Enable configuration of fault-injection capabilities via debugfs.
1612 config FAIL_FUNCTION
1613 bool "Fault-injection capability for functions"
1614 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
1616 Provide function-based fault-injection capability.
1617 This will allow you to override a specific function with a return
1618 with given return value. As a result, function caller will see
1619 an error value and have to handle it. This is useful to test the
1620 error handling in various subsystems.
1622 config FAIL_MMC_REQUEST
1623 bool "Fault-injection capability for MMC IO"
1624 depends on FAULT_INJECTION_DEBUG_FS && MMC
1626 Provide fault-injection capability for MMC IO.
1627 This will make the mmc core return data errors. This is
1628 useful to test the error handling in the mmc block device
1629 and to test how the mmc host driver handles retries from
1632 config FAULT_INJECTION_STACKTRACE_FILTER
1633 bool "stacktrace filter for fault-injection capabilities"
1634 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1637 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86
1639 Provide stacktrace filter for fault-injection capabilities
1642 bool "Latency measuring infrastructure"
1643 depends on DEBUG_KERNEL
1644 depends on STACKTRACE_SUPPORT
1646 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86
1653 Enable this option if you want to use the LatencyTOP tool
1654 to find out which userspace is blocking on what kernel operations.
1656 source "kernel/trace/Kconfig"
1658 config PROVIDE_OHCI1394_DMA_INIT
1659 bool "Remote debugging over FireWire early on boot"
1660 depends on PCI && X86
1662 If you want to debug problems which hang or crash the kernel early
1663 on boot and the crashing machine has a FireWire port, you can use
1664 this feature to remotely access the memory of the crashed machine
1665 over FireWire. This employs remote DMA as part of the OHCI1394
1666 specification which is now the standard for FireWire controllers.
1668 With remote DMA, you can monitor the printk buffer remotely using
1669 firescope and access all memory below 4GB using fireproxy from gdb.
1670 Even controlling a kernel debugger is possible using remote DMA.
1674 If ohci1394_dma=early is used as boot parameter, it will initialize
1675 all OHCI1394 controllers which are found in the PCI config space.
1677 As all changes to the FireWire bus such as enabling and disabling
1678 devices cause a bus reset and thereby disable remote DMA for all
1679 devices, be sure to have the cable plugged and FireWire enabled on
1680 the debugging host before booting the debug target for debugging.
1682 This code (~1k) is freed after boot. By then, the firewire stack
1683 in charge of the OHCI-1394 controllers should be used instead.
1685 See Documentation/debugging-via-ohci1394.txt for more information.
1687 source "lib/kunit/Kconfig"
1689 menuconfig RUNTIME_TESTING_MENU
1690 bool "Runtime Testing"
1693 if RUNTIME_TESTING_MENU
1696 tristate "Linux Kernel Dump Test Tool Module"
1699 This module enables testing of the different dumping mechanisms by
1700 inducing system failures at predefined crash points.
1701 If you don't need it: say N
1702 Choose M here to compile this code as a module. The module will be
1705 Documentation on how to use the module can be found in
1706 Documentation/fault-injection/provoke-crashes.rst
1708 config TEST_LIST_SORT
1709 tristate "Linked list sorting test"
1710 depends on DEBUG_KERNEL || m
1712 Enable this to turn on 'list_sort()' function test. This test is
1713 executed only once during system boot (so affects only boot time),
1714 or at module load time.
1719 tristate "Array-based sort test"
1720 depends on DEBUG_KERNEL || m
1722 This option enables the self-test function of 'sort()' at boot,
1723 or at module load time.
1727 config KPROBES_SANITY_TEST
1728 bool "Kprobes sanity tests"
1729 depends on DEBUG_KERNEL
1732 This option provides for testing basic kprobes functionality on
1733 boot. Samples of kprobe and kretprobe are inserted and
1734 verified for functionality.
1736 Say N if you are unsure.
1738 config BACKTRACE_SELF_TEST
1739 tristate "Self test for the backtrace code"
1740 depends on DEBUG_KERNEL
1742 This option provides a kernel module that can be used to test
1743 the kernel stack backtrace code. This option is not useful
1744 for distributions or general kernels, but only for kernel
1745 developers working on architecture code.
1747 Note that if you want to also test saved backtraces, you will
1748 have to enable STACKTRACE as well.
1750 Say N if you are unsure.
1753 tristate "Red-Black tree test"
1754 depends on DEBUG_KERNEL
1756 A benchmark measuring the performance of the rbtree library.
1757 Also includes rbtree invariant checks.
1759 config REED_SOLOMON_TEST
1760 tristate "Reed-Solomon library test"
1761 depends on DEBUG_KERNEL || m
1763 select REED_SOLOMON_ENC16
1764 select REED_SOLOMON_DEC16
1766 This option enables the self-test function of rslib at boot,
1767 or at module load time.
1771 config INTERVAL_TREE_TEST
1772 tristate "Interval tree test"
1773 depends on DEBUG_KERNEL
1774 select INTERVAL_TREE
1776 A benchmark measuring the performance of the interval tree library
1779 tristate "Per cpu operations test"
1780 depends on m && DEBUG_KERNEL
1782 Enable this option to build test module which validates per-cpu
1787 config ATOMIC64_SELFTEST
1788 tristate "Perform an atomic64_t self-test"
1790 Enable this option to test the atomic64_t functions at boot or
1791 at module load time.
1795 config ASYNC_RAID6_TEST
1796 tristate "Self test for hardware accelerated raid6 recovery"
1797 depends on ASYNC_RAID6_RECOV
1800 This is a one-shot self test that permutes through the
1801 recovery of all the possible two disk failure scenarios for a
1802 N-disk array. Recovery is performed with the asynchronous
1803 raid6 recovery routines, and will optionally use an offload
1804 engine if one is available.
1809 tristate "Test functions located in the hexdump module at runtime"
1811 config TEST_STRING_HELPERS
1812 tristate "Test functions located in the string_helpers module at runtime"
1815 tristate "Test strscpy*() family of functions at runtime"
1818 tristate "Test kstrto*() family of functions at runtime"
1821 tristate "Test printf() family of functions at runtime"
1824 tristate "Test bitmap_*() family of functions at runtime"
1826 Enable this option to test the bitmap functions at boot.
1830 config TEST_BITFIELD
1831 tristate "Test bitfield functions at runtime"
1833 Enable this option to test the bitfield functions at boot.
1838 tristate "Test functions located in the uuid module at runtime"
1841 tristate "Test the XArray code at runtime"
1843 config TEST_OVERFLOW
1844 tristate "Test check_*_overflow() functions at runtime"
1846 config TEST_RHASHTABLE
1847 tristate "Perform selftest on resizable hash table"
1849 Enable this option to test the rhashtable functions at boot.
1854 tristate "Perform selftest on hash functions"
1856 Enable this option to test the kernel's integer (<linux/hash.h>),
1857 string (<linux/stringhash.h>), and siphash (<linux/siphash.h>)
1858 hash functions on boot (or module load).
1860 This is intended to help people writing architecture-specific
1861 optimized versions. If unsure, say N.
1864 tristate "Perform selftest on IDA functions"
1867 tristate "Perform selftest on priority array manager"
1870 Enable this option to test priority array manager on boot
1875 config TEST_IRQ_TIMINGS
1876 bool "IRQ timings selftest"
1877 depends on IRQ_TIMINGS
1879 Enable this option to test the irq timings code on boot.
1884 tristate "Test module loading with 'hello world' module"
1887 This builds the "test_module" module that emits "Hello, world"
1888 on printk when loaded. It is designed to be used for basic
1889 evaluation of the module loading subsystem (for example when
1890 validating module verification). It lacks any extra dependencies,
1891 and will not normally be loaded by the system unless explicitly
1897 tristate "Test module for stress/performance analysis of vmalloc allocator"
1902 This builds the "test_vmalloc" module that should be used for
1903 stress and performance analysis. So, any new change for vmalloc
1904 subsystem can be evaluated from performance and stability point
1909 config TEST_USER_COPY
1910 tristate "Test user/kernel boundary protections"
1913 This builds the "test_user_copy" module that runs sanity checks
1914 on the copy_to/from_user infrastructure, making sure basic
1915 user/kernel boundary testing is working. If it fails to load,
1916 a regression has been detected in the user/kernel memory boundary
1922 tristate "Test BPF filter functionality"
1925 This builds the "test_bpf" module that runs various test vectors
1926 against the BPF interpreter or BPF JIT compiler depending on the
1927 current setting. This is in particular useful for BPF JIT compiler
1928 development, but also to run regression tests against changes in
1929 the interpreter code. It also enables test stubs for eBPF maps and
1930 verifier used by user space verifier testsuite.
1934 config TEST_BLACKHOLE_DEV
1935 tristate "Test blackhole netdev functionality"
1938 This builds the "test_blackhole_dev" module that validates the
1939 data path through this blackhole netdev.
1943 config FIND_BIT_BENCHMARK
1944 tristate "Test find_bit functions"
1946 This builds the "test_find_bit" module that measure find_*_bit()
1947 functions performance.
1951 config TEST_FIRMWARE
1952 tristate "Test firmware loading via userspace interface"
1953 depends on FW_LOADER
1955 This builds the "test_firmware" module that creates a userspace
1956 interface for testing firmware loading. This can be used to
1957 control the triggering of firmware loading without needing an
1958 actual firmware-using device. The contents can be rechecked by
1964 tristate "sysctl test driver"
1965 depends on PROC_SYSCTL
1967 This builds the "test_sysctl" module. This driver enables to test the
1968 proc sysctl interfaces available to drivers safely without affecting
1969 production knobs which might alter system functionality.
1973 config SYSCTL_KUNIT_TEST
1974 bool "KUnit test for sysctl"
1977 This builds the proc sysctl unit test, which runs on boot.
1978 Tests the API contract and implementation correctness of sysctl.
1979 For more information on KUnit and unit tests in general please refer
1980 to the KUnit documentation in Documentation/dev-tools/kunit/.
1984 config LIST_KUNIT_TEST
1985 bool "KUnit Test for Kernel Linked-list structures"
1988 This builds the linked list KUnit test suite.
1989 It tests that the API and basic functionality of the list_head type
1990 and associated macros.
1992 KUnit tests run during boot and output the results to the debug log
1993 in TAP format (http://testanything.org/). Only useful for kernel devs
1994 running the KUnit test harness, and not intended for inclusion into a
1997 For more information on KUnit and unit tests in general please refer
1998 to the KUnit documentation in Documentation/dev-tools/kunit/.
2003 tristate "udelay test driver"
2005 This builds the "udelay_test" module that helps to make sure
2006 that udelay() is working properly.
2010 config TEST_STATIC_KEYS
2011 tristate "Test static keys"
2014 Test the static key interfaces.
2019 tristate "kmod stress tester"
2021 depends on NETDEVICES && NET_CORE && INET # for TUN
2028 Test the kernel's module loading mechanism: kmod. kmod implements
2029 support to load modules using the Linux kernel's usermode helper.
2030 This test provides a series of tests against kmod.
2032 Although technically you can either build test_kmod as a module or
2033 into the kernel we disallow building it into the kernel since
2034 it stress tests request_module() and this will very likely cause
2035 some issues by taking over precious threads available from other
2036 module load requests, ultimately this could be fatal.
2040 tools/testing/selftests/kmod/kmod.sh --help
2044 config TEST_DEBUG_VIRTUAL
2045 tristate "Test CONFIG_DEBUG_VIRTUAL feature"
2046 depends on DEBUG_VIRTUAL
2048 Test the kernel's ability to detect incorrect calls to
2049 virt_to_phys() done against the non-linear part of the
2050 kernel's virtual address map.
2054 config TEST_MEMCAT_P
2055 tristate "Test memcat_p() helper function"
2057 Test the memcat_p() helper for correctly merging two
2058 pointer arrays together.
2062 config TEST_LIVEPATCH
2063 tristate "Test livepatching"
2065 depends on DYNAMIC_DEBUG
2066 depends on LIVEPATCH
2069 Test kernel livepatching features for correctness. The tests will
2070 load test modules that will be livepatched in various scenarios.
2072 To run all the livepatching tests:
2074 make -C tools/testing/selftests TARGETS=livepatch run_tests
2076 Alternatively, individual tests may be invoked:
2078 tools/testing/selftests/livepatch/test-callbacks.sh
2079 tools/testing/selftests/livepatch/test-livepatch.sh
2080 tools/testing/selftests/livepatch/test-shadow-vars.sh
2085 tristate "Perform selftest on object aggreration manager"
2089 Enable this option to test object aggregation manager on boot
2093 config TEST_STACKINIT
2094 tristate "Test level of stack variable initialization"
2096 Test if the kernel is zero-initializing stack variables and
2097 padding. Coverage is controlled by compiler flags,
2098 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2099 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2104 tristate "Test heap/page initialization"
2106 Test if the kernel is zero-initializing heap and page allocations.
2107 This can be useful to test init_on_alloc and init_on_free features.
2111 endif # RUNTIME_TESTING_MENU
2116 This option adds a kernel parameter 'memtest', which allows memtest
2118 memtest=0, mean disabled; -- default
2119 memtest=1, mean do 1 test pattern;
2121 memtest=17, mean do 17 test patterns.
2122 If you are unsure how to answer this question, answer N.
2124 source "samples/Kconfig"
2126 config ARCH_HAS_DEVMEM_IS_ALLOWED
2129 config STRICT_DEVMEM
2130 bool "Filter access to /dev/mem"
2131 depends on MMU && DEVMEM
2132 depends on ARCH_HAS_DEVMEM_IS_ALLOWED
2133 default y if PPC || X86 || ARM64
2135 If this option is disabled, you allow userspace (root) access to all
2136 of memory, including kernel and userspace memory. Accidental
2137 access to this is obviously disastrous, but specific access can
2138 be used by people debugging the kernel. Note that with PAT support
2139 enabled, even in this case there are restrictions on /dev/mem
2140 use due to the cache aliasing requirements.
2142 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
2143 file only allows userspace access to PCI space and the BIOS code and
2144 data regions. This is sufficient for dosemu and X and all common
2149 config IO_STRICT_DEVMEM
2150 bool "Filter I/O access to /dev/mem"
2151 depends on STRICT_DEVMEM
2153 If this option is disabled, you allow userspace (root) access to all
2154 io-memory regardless of whether a driver is actively using that
2155 range. Accidental access to this is obviously disastrous, but
2156 specific access can be used by people debugging kernel drivers.
2158 If this option is switched on, the /dev/mem file only allows
2159 userspace access to *idle* io-memory ranges (see /proc/iomem) This
2160 may break traditional users of /dev/mem (dosemu, legacy X, etc...)
2161 if the driver using a given range cannot be disabled.
2165 menu "$(SRCARCH) Debugging"
2167 source "arch/$(SRCARCH)/Kconfig.debug"
2171 config HYPERV_TESTING
2172 bool "Microsoft Hyper-V driver testing"
2174 depends on HYPERV && DEBUG_FS
2176 Select this option to enable Hyper-V vmbus testing.
2178 endmenu # Kernel hacking
projects / platform / kernel / linux-rpi.git / blob