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.
312 bool "Run sanity checks on uapi headers when building 'all'"
313 depends on HEADERS_INSTALL
315 This option will run basic sanity checks on uapi headers when
316 building the 'all' target, for example, ensure that they do not
317 attempt to include files which were not exported, etc.
319 If you're making modifications to header files which are
320 relevant for userspace, say 'Y'.
322 config OPTIMIZE_INLINING
325 This option determines if the kernel forces gcc to inline the functions
326 developers have marked 'inline'. Doing so takes away freedom from gcc to
327 do what it thinks is best, which is desirable for the gcc 3.x series of
328 compilers. The gcc 4.x series have a rewritten inlining algorithm and
329 enabling this option will generate a smaller kernel there. Hopefully
330 this algorithm is so good that allowing gcc 4.x and above to make the
331 decision will become the default in the future. Until then this option
332 is there to test gcc for this.
334 config DEBUG_SECTION_MISMATCH
335 bool "Enable full Section mismatch analysis"
337 The section mismatch analysis checks if there are illegal
338 references from one section to another section.
339 During linktime or runtime, some sections are dropped;
340 any use of code/data previously in these sections would
341 most likely result in an oops.
342 In the code, functions and variables are annotated with
343 __init,, etc. (see the full list in include/linux/init.h),
344 which results in the code/data being placed in specific sections.
345 The section mismatch analysis is always performed after a full
346 kernel build, and enabling this option causes the following
347 additional step to occur:
348 - Add the option -fno-inline-functions-called-once to gcc commands.
349 When inlining a function annotated with __init in a non-init
350 function, we would lose the section information and thus
351 the analysis would not catch the illegal reference.
352 This option tells gcc to inline less (but it does result in
355 config SECTION_MISMATCH_WARN_ONLY
356 bool "Make section mismatch errors non-fatal"
359 If you say N here, the build process will fail if there are any
360 section mismatch, instead of just throwing warnings.
365 # Select this config option from the architecture Kconfig, if it
366 # is preferred to always offer frame pointers as a config
367 # option on the architecture (regardless of KERNEL_DEBUG):
369 config ARCH_WANT_FRAME_POINTERS
373 bool "Compile the kernel with frame pointers"
374 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
375 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
377 If you say Y here the resulting kernel image will be slightly
378 larger and slower, but it gives very useful debugging information
379 in case of kernel bugs. (precise oopses/stacktraces/warnings)
381 config STACK_VALIDATION
382 bool "Compile-time stack metadata validation"
383 depends on HAVE_STACK_VALIDATION
386 Add compile-time checks to validate stack metadata, including frame
387 pointers (if CONFIG_FRAME_POINTER is enabled). This helps ensure
388 that runtime stack traces are more reliable.
390 This is also a prerequisite for generation of ORC unwind data, which
391 is needed for CONFIG_UNWINDER_ORC.
393 For more information, see
394 tools/objtool/Documentation/stack-validation.txt.
396 config DEBUG_FORCE_WEAK_PER_CPU
397 bool "Force weak per-cpu definitions"
398 depends on DEBUG_KERNEL
400 s390 and alpha require percpu variables in modules to be
401 defined weak to work around addressing range issue which
402 puts the following two restrictions on percpu variable
405 1. percpu symbols must be unique whether static or not
406 2. percpu variables can't be defined inside a function
408 To ensure that generic code follows the above rules, this
409 option forces all percpu variables to be defined as weak.
411 endmenu # "Compiler options"
414 bool "Magic SysRq key"
417 If you say Y here, you will have some control over the system even
418 if the system crashes for example during kernel debugging (e.g., you
419 will be able to flush the buffer cache to disk, reboot the system
420 immediately or dump some status information). This is accomplished
421 by pressing various keys while holding SysRq (Alt+PrintScreen). It
422 also works on a serial console (on PC hardware at least), if you
423 send a BREAK and then within 5 seconds a command keypress. The
424 keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
425 Don't say Y unless you really know what this hack does.
427 config MAGIC_SYSRQ_DEFAULT_ENABLE
428 hex "Enable magic SysRq key functions by default"
429 depends on MAGIC_SYSRQ
432 Specifies which SysRq key functions are enabled by default.
433 This may be set to 1 or 0 to enable or disable them all, or
434 to a bitmask as described in Documentation/admin-guide/sysrq.rst.
436 config MAGIC_SYSRQ_SERIAL
437 bool "Enable magic SysRq key over serial"
438 depends on MAGIC_SYSRQ
441 Many embedded boards have a disconnected TTL level serial which can
442 generate some garbage that can lead to spurious false sysrq detects.
443 This option allows you to decide whether you want to enable the
447 bool "Kernel debugging"
449 Say Y here if you are developing drivers or trying to debug and
450 identify kernel problems.
453 bool "Miscellaneous debug code"
455 depends on DEBUG_KERNEL
457 Say Y here if you need to enable miscellaneous debug code that should
458 be under a more specific debug option but isn't.
461 menu "Memory Debugging"
463 source "mm/Kconfig.debug"
466 bool "Debug object operations"
467 depends on DEBUG_KERNEL
469 If you say Y here, additional code will be inserted into the
470 kernel to track the life time of various objects and validate
471 the operations on those objects.
473 config DEBUG_OBJECTS_SELFTEST
474 bool "Debug objects selftest"
475 depends on DEBUG_OBJECTS
477 This enables the selftest of the object debug code.
479 config DEBUG_OBJECTS_FREE
480 bool "Debug objects in freed memory"
481 depends on DEBUG_OBJECTS
483 This enables checks whether a k/v free operation frees an area
484 which contains an object which has not been deactivated
485 properly. This can make kmalloc/kfree-intensive workloads
488 config DEBUG_OBJECTS_TIMERS
489 bool "Debug timer objects"
490 depends on DEBUG_OBJECTS
492 If you say Y here, additional code will be inserted into the
493 timer routines to track the life time of timer objects and
494 validate the timer operations.
496 config DEBUG_OBJECTS_WORK
497 bool "Debug work objects"
498 depends on DEBUG_OBJECTS
500 If you say Y here, additional code will be inserted into the
501 work queue routines to track the life time of work objects and
502 validate the work operations.
504 config DEBUG_OBJECTS_RCU_HEAD
505 bool "Debug RCU callbacks objects"
506 depends on DEBUG_OBJECTS
508 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
510 config DEBUG_OBJECTS_PERCPU_COUNTER
511 bool "Debug percpu counter objects"
512 depends on DEBUG_OBJECTS
514 If you say Y here, additional code will be inserted into the
515 percpu counter routines to track the life time of percpu counter
516 objects and validate the percpu counter operations.
518 config DEBUG_OBJECTS_ENABLE_DEFAULT
519 int "debug_objects bootup default value (0-1)"
522 depends on DEBUG_OBJECTS
524 Debug objects boot parameter default value
527 bool "Debug slab memory allocations"
528 depends on DEBUG_KERNEL && SLAB
530 Say Y here to have the kernel do limited verification on memory
531 allocation as well as poisoning memory on free to catch use of freed
532 memory. This can make kmalloc/kfree-intensive workloads much slower.
535 bool "SLUB debugging on by default"
536 depends on SLUB && SLUB_DEBUG
539 Boot with debugging on by default. SLUB boots by default with
540 the runtime debug capabilities switched off. Enabling this is
541 equivalent to specifying the "slub_debug" parameter on boot.
542 There is no support for more fine grained debug control like
543 possible with slub_debug=xxx. SLUB debugging may be switched
544 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
549 bool "Enable SLUB performance statistics"
550 depends on SLUB && SYSFS
552 SLUB statistics are useful to debug SLUBs allocation behavior in
553 order find ways to optimize the allocator. This should never be
554 enabled for production use since keeping statistics slows down
555 the allocator by a few percentage points. The slabinfo command
556 supports the determination of the most active slabs to figure
557 out which slabs are relevant to a particular load.
558 Try running: slabinfo -DA
560 config HAVE_DEBUG_KMEMLEAK
563 config DEBUG_KMEMLEAK
564 bool "Kernel memory leak detector"
565 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
567 select STACKTRACE if STACKTRACE_SUPPORT
571 Say Y here if you want to enable the memory leak
572 detector. The memory allocation/freeing is traced in a way
573 similar to the Boehm's conservative garbage collector, the
574 difference being that the orphan objects are not freed but
575 only shown in /sys/kernel/debug/kmemleak. Enabling this
576 feature will introduce an overhead to memory
577 allocations. See Documentation/dev-tools/kmemleak.rst for more
580 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
581 of finding leaks due to the slab objects poisoning.
583 In order to access the kmemleak file, debugfs needs to be
584 mounted (usually at /sys/kernel/debug).
586 config DEBUG_KMEMLEAK_MEM_POOL_SIZE
587 int "Kmemleak memory pool size"
588 depends on DEBUG_KMEMLEAK
592 Kmemleak must track all the memory allocations to avoid
593 reporting false positives. Since memory may be allocated or
594 freed before kmemleak is fully initialised, use a static pool
595 of metadata objects to track such callbacks. After kmemleak is
596 fully initialised, this memory pool acts as an emergency one
597 if slab allocations fail.
599 config DEBUG_KMEMLEAK_TEST
600 tristate "Simple test for the kernel memory leak detector"
601 depends on DEBUG_KMEMLEAK && m
603 This option enables a module that explicitly leaks memory.
607 config DEBUG_KMEMLEAK_DEFAULT_OFF
608 bool "Default kmemleak to off"
609 depends on DEBUG_KMEMLEAK
611 Say Y here to disable kmemleak by default. It can then be enabled
612 on the command line via kmemleak=on.
614 config DEBUG_KMEMLEAK_AUTO_SCAN
615 bool "Enable kmemleak auto scan thread on boot up"
617 depends on DEBUG_KMEMLEAK
619 Depending on the cpu, kmemleak scan may be cpu intensive and can
620 stall user tasks at times. This option enables/disables automatic
621 kmemleak scan at boot up.
623 Say N here to disable kmemleak auto scan thread to stop automatic
624 scanning. Disabling this option disables automatic reporting of
629 config DEBUG_STACK_USAGE
630 bool "Stack utilization instrumentation"
631 depends on DEBUG_KERNEL && !IA64
633 Enables the display of the minimum amount of free stack which each
634 task has ever had available in the sysrq-T and sysrq-P debug output.
636 This option will slow down process creation somewhat.
640 depends on DEBUG_KERNEL
642 Enable this to turn on extended checks in the virtual-memory system
643 that may impact performance.
647 config DEBUG_VM_VMACACHE
648 bool "Debug VMA caching"
651 Enable this to turn on VMA caching debug information. Doing so
652 can cause significant overhead, so only enable it in non-production
658 bool "Debug VM red-black trees"
661 Enable VM red-black tree debugging information and extra validations.
665 config DEBUG_VM_PGFLAGS
666 bool "Debug page-flags operations"
669 Enables extra validation on page flags operations.
673 config ARCH_HAS_DEBUG_VIRTUAL
677 bool "Debug VM translations"
678 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
680 Enable some costly sanity checks in virtual to page code. This can
681 catch mistakes with virt_to_page() and friends.
685 config DEBUG_NOMMU_REGIONS
686 bool "Debug the global anon/private NOMMU mapping region tree"
687 depends on DEBUG_KERNEL && !MMU
689 This option causes the global tree of anonymous and private mapping
690 regions to be regularly checked for invalid topology.
692 config DEBUG_MEMORY_INIT
693 bool "Debug memory initialisation" if EXPERT
696 Enable this for additional checks during memory initialisation.
697 The sanity checks verify aspects of the VM such as the memory model
698 and other information provided by the architecture. Verbose
699 information will be printed at KERN_DEBUG loglevel depending
700 on the mminit_loglevel= command-line option.
704 config MEMORY_NOTIFIER_ERROR_INJECT
705 tristate "Memory hotplug notifier error injection module"
706 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
708 This option provides the ability to inject artificial errors to
709 memory hotplug notifier chain callbacks. It is controlled through
710 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
712 If the notifier call chain should be failed with some events
713 notified, write the error code to "actions/<notifier event>/error".
715 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
717 # cd /sys/kernel/debug/notifier-error-inject/memory
718 # echo -12 > actions/MEM_GOING_OFFLINE/error
719 # echo offline > /sys/devices/system/memory/memoryXXX/state
720 bash: echo: write error: Cannot allocate memory
722 To compile this code as a module, choose M here: the module will
723 be called memory-notifier-error-inject.
727 config DEBUG_PER_CPU_MAPS
728 bool "Debug access to per_cpu maps"
729 depends on DEBUG_KERNEL
732 Say Y to verify that the per_cpu map being accessed has
733 been set up. This adds a fair amount of code to kernel memory
734 and decreases performance.
739 bool "Highmem debugging"
740 depends on DEBUG_KERNEL && HIGHMEM
742 This option enables additional error checking for high memory
743 systems. Disable for production systems.
745 config HAVE_DEBUG_STACKOVERFLOW
748 config DEBUG_STACKOVERFLOW
749 bool "Check for stack overflows"
750 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
752 Say Y here if you want to check for overflows of kernel, IRQ
753 and exception stacks (if your architecture uses them). This
754 option will show detailed messages if free stack space drops
755 below a certain limit.
757 These kinds of bugs usually occur when call-chains in the
758 kernel get too deep, especially when interrupts are
761 Use this in cases where you see apparently random memory
762 corruption, especially if it appears in 'struct thread_info'
764 If in doubt, say "N".
766 source "lib/Kconfig.kasan"
768 endmenu # "Memory Debugging"
773 An architecture should select this when it can successfully
774 build and run with CONFIG_KCOV. This typically requires
775 disabling instrumentation for some early boot code.
777 config CC_HAS_SANCOV_TRACE_PC
778 def_bool $(cc-option,-fsanitize-coverage=trace-pc)
781 bool "Code coverage for fuzzing"
782 depends on ARCH_HAS_KCOV
783 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
785 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
787 KCOV exposes kernel code coverage information in a form suitable
788 for coverage-guided fuzzing (randomized testing).
790 If RANDOMIZE_BASE is enabled, PC values will not be stable across
791 different machines and across reboots. If you need stable PC values,
792 disable RANDOMIZE_BASE.
794 For more details, see Documentation/dev-tools/kcov.rst.
796 config KCOV_ENABLE_COMPARISONS
797 bool "Enable comparison operands collection by KCOV"
799 depends on $(cc-option,-fsanitize-coverage=trace-cmp)
801 KCOV also exposes operands of every comparison in the instrumented
802 code along with operand sizes and PCs of the comparison instructions.
803 These operands can be used by fuzzing engines to improve the quality
806 config KCOV_INSTRUMENT_ALL
807 bool "Instrument all code by default"
811 If you are doing generic system call fuzzing (like e.g. syzkaller),
812 then you will want to instrument the whole kernel and you should
813 say y here. If you are doing more targeted fuzzing (like e.g.
814 filesystem fuzzing with AFL) then you will want to enable coverage
815 for more specific subsets of files, and should say n here.
818 bool "Debug shared IRQ handlers"
819 depends on DEBUG_KERNEL
821 Enable this to generate a spurious interrupt as soon as a shared
822 interrupt handler is registered, and just before one is deregistered.
823 Drivers ought to be able to handle interrupts coming in at those
824 points; some don't and need to be caught.
826 menu "Debug Lockups and Hangs"
828 config LOCKUP_DETECTOR
831 config SOFTLOCKUP_DETECTOR
832 bool "Detect Soft Lockups"
833 depends on DEBUG_KERNEL && !S390
834 select LOCKUP_DETECTOR
836 Say Y here to enable the kernel to act as a watchdog to detect
839 Softlockups are bugs that cause the kernel to loop in kernel
840 mode for more than 20 seconds, without giving other tasks a
841 chance to run. The current stack trace is displayed upon
842 detection and the system will stay locked up.
844 config BOOTPARAM_SOFTLOCKUP_PANIC
845 bool "Panic (Reboot) On Soft Lockups"
846 depends on SOFTLOCKUP_DETECTOR
848 Say Y here to enable the kernel to panic on "soft lockups",
849 which are bugs that cause the kernel to loop in kernel
850 mode for more than 20 seconds (configurable using the watchdog_thresh
851 sysctl), without giving other tasks a chance to run.
853 The panic can be used in combination with panic_timeout,
854 to cause the system to reboot automatically after a
855 lockup has been detected. This feature is useful for
856 high-availability systems that have uptime guarantees and
857 where a lockup must be resolved ASAP.
861 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
863 depends on SOFTLOCKUP_DETECTOR
865 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
866 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
868 config HARDLOCKUP_DETECTOR_PERF
870 select SOFTLOCKUP_DETECTOR
873 # Enables a timestamp based low pass filter to compensate for perf based
874 # hard lockup detection which runs too fast due to turbo modes.
876 config HARDLOCKUP_CHECK_TIMESTAMP
880 # arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard
881 # lockup detector rather than the perf based detector.
883 config HARDLOCKUP_DETECTOR
884 bool "Detect Hard Lockups"
885 depends on DEBUG_KERNEL && !S390
886 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH
887 select LOCKUP_DETECTOR
888 select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF
889 select HARDLOCKUP_DETECTOR_ARCH if HAVE_HARDLOCKUP_DETECTOR_ARCH
891 Say Y here to enable the kernel to act as a watchdog to detect
894 Hardlockups are bugs that cause the CPU to loop in kernel mode
895 for more than 10 seconds, without letting other interrupts have a
896 chance to run. The current stack trace is displayed upon detection
897 and the system will stay locked up.
899 config BOOTPARAM_HARDLOCKUP_PANIC
900 bool "Panic (Reboot) On Hard Lockups"
901 depends on HARDLOCKUP_DETECTOR
903 Say Y here to enable the kernel to panic on "hard lockups",
904 which are bugs that cause the kernel to loop in kernel
905 mode with interrupts disabled for more than 10 seconds (configurable
906 using the watchdog_thresh sysctl).
910 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
912 depends on HARDLOCKUP_DETECTOR
914 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
915 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
917 config DETECT_HUNG_TASK
918 bool "Detect Hung Tasks"
919 depends on DEBUG_KERNEL
920 default SOFTLOCKUP_DETECTOR
922 Say Y here to enable the kernel to detect "hung tasks",
923 which are bugs that cause the task to be stuck in
924 uninterruptible "D" state indefinitely.
926 When a hung task is detected, the kernel will print the
927 current stack trace (which you should report), but the
928 task will stay in uninterruptible state. If lockdep is
929 enabled then all held locks will also be reported. This
930 feature has negligible overhead.
932 config DEFAULT_HUNG_TASK_TIMEOUT
933 int "Default timeout for hung task detection (in seconds)"
934 depends on DETECT_HUNG_TASK
937 This option controls the default timeout (in seconds) used
938 to determine when a task has become non-responsive and should
941 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
942 sysctl or by writing a value to
943 /proc/sys/kernel/hung_task_timeout_secs.
945 A timeout of 0 disables the check. The default is two minutes.
946 Keeping the default should be fine in most cases.
948 config BOOTPARAM_HUNG_TASK_PANIC
949 bool "Panic (Reboot) On Hung Tasks"
950 depends on DETECT_HUNG_TASK
952 Say Y here to enable the kernel to panic on "hung tasks",
953 which are bugs that cause the kernel to leave a task stuck
954 in uninterruptible "D" state.
956 The panic can be used in combination with panic_timeout,
957 to cause the system to reboot automatically after a
958 hung task has been detected. This feature is useful for
959 high-availability systems that have uptime guarantees and
960 where a hung tasks must be resolved ASAP.
964 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
966 depends on DETECT_HUNG_TASK
968 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
969 default 1 if BOOTPARAM_HUNG_TASK_PANIC
972 bool "Detect Workqueue Stalls"
973 depends on DEBUG_KERNEL
975 Say Y here to enable stall detection on workqueues. If a
976 worker pool doesn't make forward progress on a pending work
977 item for over a given amount of time, 30s by default, a
978 warning message is printed along with dump of workqueue
979 state. This can be configured through kernel parameter
980 "workqueue.watchdog_thresh" and its sysfs counterpart.
982 endmenu # "Debug lockups and hangs"
987 Say Y here to enable the kernel to panic when it oopses. This
988 has the same effect as setting oops=panic on the kernel command
991 This feature is useful to ensure that the kernel does not do
992 anything erroneous after an oops which could result in data
993 corruption or other issues.
997 config PANIC_ON_OOPS_VALUE
1000 default 0 if !PANIC_ON_OOPS
1001 default 1 if PANIC_ON_OOPS
1003 config PANIC_TIMEOUT
1007 Set the timeout value (in seconds) until a reboot occurs when the
1008 the kernel panics. If n = 0, then we wait forever. A timeout
1009 value n > 0 will wait n seconds before rebooting, while a timeout
1010 value n < 0 will reboot immediately.
1013 bool "Collect scheduler debugging info"
1014 depends on DEBUG_KERNEL && PROC_FS
1017 If you say Y here, the /proc/sched_debug file will be provided
1018 that can help debug the scheduler. The runtime overhead of this
1026 bool "Collect scheduler statistics"
1027 depends on DEBUG_KERNEL && PROC_FS
1030 If you say Y here, additional code will be inserted into the
1031 scheduler and related routines to collect statistics about
1032 scheduler behavior and provide them in /proc/schedstat. These
1033 stats may be useful for both tuning and debugging the scheduler
1034 If you aren't debugging the scheduler or trying to tune a specific
1035 application, you can say N to avoid the very slight overhead
1038 config SCHED_STACK_END_CHECK
1039 bool "Detect stack corruption on calls to schedule()"
1040 depends on DEBUG_KERNEL
1043 This option checks for a stack overrun on calls to schedule().
1044 If the stack end location is found to be over written always panic as
1045 the content of the corrupted region can no longer be trusted.
1046 This is to ensure no erroneous behaviour occurs which could result in
1047 data corruption or a sporadic crash at a later stage once the region
1048 is examined. The runtime overhead introduced is minimal.
1050 config DEBUG_TIMEKEEPING
1051 bool "Enable extra timekeeping sanity checking"
1053 This option will enable additional timekeeping sanity checks
1054 which may be helpful when diagnosing issues where timekeeping
1055 problems are suspected.
1057 This may include checks in the timekeeping hotpaths, so this
1058 option may have a (very small) performance impact to some
1063 config DEBUG_PREEMPT
1064 bool "Debug preemptible kernel"
1065 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
1068 If you say Y here then the kernel will use a debug variant of the
1069 commonly used smp_processor_id() function and will print warnings
1070 if kernel code uses it in a preemption-unsafe way. Also, the kernel
1071 will detect preemption count underflows.
1073 menu "Lock Debugging (spinlocks, mutexes, etc...)"
1075 config LOCK_DEBUGGING_SUPPORT
1077 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1080 config PROVE_LOCKING
1081 bool "Lock debugging: prove locking correctness"
1082 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1084 select DEBUG_SPINLOCK
1085 select DEBUG_MUTEXES
1086 select DEBUG_RT_MUTEXES if RT_MUTEXES
1088 select DEBUG_WW_MUTEX_SLOWPATH
1089 select DEBUG_LOCK_ALLOC
1090 select TRACE_IRQFLAGS
1093 This feature enables the kernel to prove that all locking
1094 that occurs in the kernel runtime is mathematically
1095 correct: that under no circumstance could an arbitrary (and
1096 not yet triggered) combination of observed locking
1097 sequences (on an arbitrary number of CPUs, running an
1098 arbitrary number of tasks and interrupt contexts) cause a
1101 In short, this feature enables the kernel to report locking
1102 related deadlocks before they actually occur.
1104 The proof does not depend on how hard and complex a
1105 deadlock scenario would be to trigger: how many
1106 participant CPUs, tasks and irq-contexts would be needed
1107 for it to trigger. The proof also does not depend on
1108 timing: if a race and a resulting deadlock is possible
1109 theoretically (no matter how unlikely the race scenario
1110 is), it will be proven so and will immediately be
1111 reported by the kernel (once the event is observed that
1112 makes the deadlock theoretically possible).
1114 If a deadlock is impossible (i.e. the locking rules, as
1115 observed by the kernel, are mathematically correct), the
1116 kernel reports nothing.
1118 NOTE: this feature can also be enabled for rwlocks, mutexes
1119 and rwsems - in which case all dependencies between these
1120 different locking variants are observed and mapped too, and
1121 the proof of observed correctness is also maintained for an
1122 arbitrary combination of these separate locking variants.
1124 For more details, see Documentation/locking/lockdep-design.rst.
1127 bool "Lock usage statistics"
1128 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1130 select DEBUG_SPINLOCK
1131 select DEBUG_MUTEXES
1132 select DEBUG_RT_MUTEXES if RT_MUTEXES
1133 select DEBUG_LOCK_ALLOC
1136 This feature enables tracking lock contention points
1138 For more details, see Documentation/locking/lockstat.rst
1140 This also enables lock events required by "perf lock",
1142 If you want to use "perf lock", you also need to turn on
1143 CONFIG_EVENT_TRACING.
1145 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1146 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1148 config DEBUG_RT_MUTEXES
1149 bool "RT Mutex debugging, deadlock detection"
1150 depends on DEBUG_KERNEL && RT_MUTEXES
1152 This allows rt mutex semantics violations and rt mutex related
1153 deadlocks (lockups) to be detected and reported automatically.
1155 config DEBUG_SPINLOCK
1156 bool "Spinlock and rw-lock debugging: basic checks"
1157 depends on DEBUG_KERNEL
1158 select UNINLINE_SPIN_UNLOCK
1160 Say Y here and build SMP to catch missing spinlock initialization
1161 and certain other kinds of spinlock errors commonly made. This is
1162 best used in conjunction with the NMI watchdog so that spinlock
1163 deadlocks are also debuggable.
1165 config DEBUG_MUTEXES
1166 bool "Mutex debugging: basic checks"
1167 depends on DEBUG_KERNEL
1169 This feature allows mutex semantics violations to be detected and
1172 config DEBUG_WW_MUTEX_SLOWPATH
1173 bool "Wait/wound mutex debugging: Slowpath testing"
1174 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1175 select DEBUG_LOCK_ALLOC
1176 select DEBUG_SPINLOCK
1177 select DEBUG_MUTEXES
1179 This feature enables slowpath testing for w/w mutex users by
1180 injecting additional -EDEADLK wound/backoff cases. Together with
1181 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1182 will test all possible w/w mutex interface abuse with the
1183 exception of simply not acquiring all the required locks.
1184 Note that this feature can introduce significant overhead, so
1185 it really should not be enabled in a production or distro kernel,
1186 even a debug kernel. If you are a driver writer, enable it. If
1187 you are a distro, do not.
1190 bool "RW Semaphore debugging: basic checks"
1191 depends on DEBUG_KERNEL
1193 This debugging feature allows mismatched rw semaphore locks
1194 and unlocks to be detected and reported.
1196 config DEBUG_LOCK_ALLOC
1197 bool "Lock debugging: detect incorrect freeing of live locks"
1198 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1199 select DEBUG_SPINLOCK
1200 select DEBUG_MUTEXES
1201 select DEBUG_RT_MUTEXES if RT_MUTEXES
1204 This feature will check whether any held lock (spinlock, rwlock,
1205 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1206 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1207 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1208 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1209 held during task exit.
1213 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1215 select FRAME_POINTER if !MIPS && !PPC && !ARM && !S390 && !MICROBLAZE && !ARC && !X86
1219 config LOCKDEP_SMALL
1222 config DEBUG_LOCKDEP
1223 bool "Lock dependency engine debugging"
1224 depends on DEBUG_KERNEL && LOCKDEP
1226 If you say Y here, the lock dependency engine will do
1227 additional runtime checks to debug itself, at the price
1228 of more runtime overhead.
1230 config DEBUG_ATOMIC_SLEEP
1231 bool "Sleep inside atomic section checking"
1232 select PREEMPT_COUNT
1233 depends on DEBUG_KERNEL
1234 depends on !ARCH_NO_PREEMPT
1236 If you say Y here, various routines which may sleep will become very
1237 noisy if they are called inside atomic sections: when a spinlock is
1238 held, inside an rcu read side critical section, inside preempt disabled
1239 sections, inside an interrupt, etc...
1241 config DEBUG_LOCKING_API_SELFTESTS
1242 bool "Locking API boot-time self-tests"
1243 depends on DEBUG_KERNEL
1245 Say Y here if you want the kernel to run a short self-test during
1246 bootup. The self-test checks whether common types of locking bugs
1247 are detected by debugging mechanisms or not. (if you disable
1248 lock debugging then those bugs wont be detected of course.)
1249 The following locking APIs are covered: spinlocks, rwlocks,
1252 config LOCK_TORTURE_TEST
1253 tristate "torture tests for locking"
1254 depends on DEBUG_KERNEL
1257 This option provides a kernel module that runs torture tests
1258 on kernel locking primitives. The kernel module may be built
1259 after the fact on the running kernel to be tested, if desired.
1261 Say Y here if you want kernel locking-primitive torture tests
1262 to be built into the kernel.
1263 Say M if you want these torture tests to build as a module.
1264 Say N if you are unsure.
1266 config WW_MUTEX_SELFTEST
1267 tristate "Wait/wound mutex selftests"
1269 This option provides a kernel module that runs tests on the
1270 on the struct ww_mutex locking API.
1272 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1273 with this test harness.
1275 Say M if you want these self tests to build as a module.
1276 Say N if you are unsure.
1278 endmenu # lock debugging
1280 config TRACE_IRQFLAGS
1283 Enables hooks to interrupt enabling and disabling for
1284 either tracing or lock debugging.
1287 bool "Stack backtrace support"
1288 depends on STACKTRACE_SUPPORT
1290 This option causes the kernel to create a /proc/pid/stack for
1291 every process, showing its current stack trace.
1292 It is also used by various kernel debugging features that require
1293 stack trace generation.
1295 config WARN_ALL_UNSEEDED_RANDOM
1296 bool "Warn for all uses of unseeded randomness"
1299 Some parts of the kernel contain bugs relating to their use of
1300 cryptographically secure random numbers before it's actually possible
1301 to generate those numbers securely. This setting ensures that these
1302 flaws don't go unnoticed, by enabling a message, should this ever
1303 occur. This will allow people with obscure setups to know when things
1304 are going wrong, so that they might contact developers about fixing
1307 Unfortunately, on some models of some architectures getting
1308 a fully seeded CRNG is extremely difficult, and so this can
1309 result in dmesg getting spammed for a surprisingly long
1310 time. This is really bad from a security perspective, and
1311 so architecture maintainers really need to do what they can
1312 to get the CRNG seeded sooner after the system is booted.
1313 However, since users cannot do anything actionable to
1314 address this, by default the kernel will issue only a single
1315 warning for the first use of unseeded randomness.
1317 Say Y here if you want to receive warnings for all uses of
1318 unseeded randomness. This will be of use primarily for
1319 those developers interested in improving the security of
1320 Linux kernels running on their architecture (or
1323 config DEBUG_KOBJECT
1324 bool "kobject debugging"
1325 depends on DEBUG_KERNEL
1327 If you say Y here, some extra kobject debugging messages will be sent
1330 config DEBUG_KOBJECT_RELEASE
1331 bool "kobject release debugging"
1332 depends on DEBUG_OBJECTS_TIMERS
1334 kobjects are reference counted objects. This means that their
1335 last reference count put is not predictable, and the kobject can
1336 live on past the point at which a driver decides to drop it's
1337 initial reference to the kobject gained on allocation. An
1338 example of this would be a struct device which has just been
1341 However, some buggy drivers assume that after such an operation,
1342 the memory backing the kobject can be immediately freed. This
1343 goes completely against the principles of a refcounted object.
1345 If you say Y here, the kernel will delay the release of kobjects
1346 on the last reference count to improve the visibility of this
1347 kind of kobject release bug.
1349 config HAVE_DEBUG_BUGVERBOSE
1352 config DEBUG_BUGVERBOSE
1353 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
1354 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
1357 Say Y here to make BUG() panics output the file name and line number
1358 of the BUG call as well as the EIP and oops trace. This aids
1359 debugging but costs about 70-100K of memory.
1362 bool "Debug linked list manipulation"
1363 depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION
1365 Enable this to turn on extended checks in the linked-list
1371 bool "Debug priority linked list manipulation"
1372 depends on DEBUG_KERNEL
1374 Enable this to turn on extended checks in the priority-ordered
1375 linked-list (plist) walking routines. This checks the entire
1376 list multiple times during each manipulation.
1381 bool "Debug SG table operations"
1382 depends on DEBUG_KERNEL
1384 Enable this to turn on checks on scatter-gather tables. This can
1385 help find problems with drivers that do not properly initialize
1390 config DEBUG_NOTIFIERS
1391 bool "Debug notifier call chains"
1392 depends on DEBUG_KERNEL
1394 Enable this to turn on sanity checking for notifier call chains.
1395 This is most useful for kernel developers to make sure that
1396 modules properly unregister themselves from notifier chains.
1397 This is a relatively cheap check but if you care about maximum
1400 config DEBUG_CREDENTIALS
1401 bool "Debug credential management"
1402 depends on DEBUG_KERNEL
1404 Enable this to turn on some debug checking for credential
1405 management. The additional code keeps track of the number of
1406 pointers from task_structs to any given cred struct, and checks to
1407 see that this number never exceeds the usage count of the cred
1410 Furthermore, if SELinux is enabled, this also checks that the
1411 security pointer in the cred struct is never seen to be invalid.
1415 source "kernel/rcu/Kconfig.debug"
1417 config DEBUG_WQ_FORCE_RR_CPU
1418 bool "Force round-robin CPU selection for unbound work items"
1419 depends on DEBUG_KERNEL
1422 Workqueue used to implicitly guarantee that work items queued
1423 without explicit CPU specified are put on the local CPU. This
1424 guarantee is no longer true and while local CPU is still
1425 preferred work items may be put on foreign CPUs. Kernel
1426 parameter "workqueue.debug_force_rr_cpu" is added to force
1427 round-robin CPU selection to flush out usages which depend on the
1428 now broken guarantee. This config option enables the debug
1429 feature by default. When enabled, memory and cache locality will
1432 config DEBUG_BLOCK_EXT_DEVT
1433 bool "Force extended block device numbers and spread them"
1434 depends on DEBUG_KERNEL
1438 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1439 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1440 YOU ARE DOING. Distros, please enable this and fix whatever
1443 Conventionally, block device numbers are allocated from
1444 predetermined contiguous area. However, extended block area
1445 may introduce non-contiguous block device numbers. This
1446 option forces most block device numbers to be allocated from
1447 the extended space and spreads them to discover kernel or
1448 userland code paths which assume predetermined contiguous
1449 device number allocation.
1451 Note that turning on this debug option shuffles all the
1452 device numbers for all IDE and SCSI devices including libata
1453 ones, so root partition specified using device number
1454 directly (via rdev or root=MAJ:MIN) won't work anymore.
1455 Textual device names (root=/dev/sdXn) will continue to work.
1457 Say N if you are unsure.
1459 config CPU_HOTPLUG_STATE_CONTROL
1460 bool "Enable CPU hotplug state control"
1461 depends on DEBUG_KERNEL
1462 depends on HOTPLUG_CPU
1465 Allows to write steps between "offline" and "online" to the CPUs
1466 sysfs target file so states can be stepped granular. This is a debug
1467 option for now as the hotplug machinery cannot be stopped and
1468 restarted at arbitrary points yet.
1470 Say N if your are unsure.
1472 config NOTIFIER_ERROR_INJECTION
1473 tristate "Notifier error injection"
1474 depends on DEBUG_KERNEL
1477 This option provides the ability to inject artificial errors to
1478 specified notifier chain callbacks. It is useful to test the error
1479 handling of notifier call chain failures.
1483 config PM_NOTIFIER_ERROR_INJECT
1484 tristate "PM notifier error injection module"
1485 depends on PM && NOTIFIER_ERROR_INJECTION
1486 default m if PM_DEBUG
1488 This option provides the ability to inject artificial errors to
1489 PM notifier chain callbacks. It is controlled through debugfs
1490 interface /sys/kernel/debug/notifier-error-inject/pm
1492 If the notifier call chain should be failed with some events
1493 notified, write the error code to "actions/<notifier event>/error".
1495 Example: Inject PM suspend error (-12 = -ENOMEM)
1497 # cd /sys/kernel/debug/notifier-error-inject/pm/
1498 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1499 # echo mem > /sys/power/state
1500 bash: echo: write error: Cannot allocate memory
1502 To compile this code as a module, choose M here: the module will
1503 be called pm-notifier-error-inject.
1507 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1508 tristate "OF reconfig notifier error injection module"
1509 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1511 This option provides the ability to inject artificial errors to
1512 OF reconfig notifier chain callbacks. It is controlled
1513 through debugfs interface under
1514 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1516 If the notifier call chain should be failed with some events
1517 notified, write the error code to "actions/<notifier event>/error".
1519 To compile this code as a module, choose M here: the module will
1520 be called of-reconfig-notifier-error-inject.
1524 config NETDEV_NOTIFIER_ERROR_INJECT
1525 tristate "Netdev notifier error injection module"
1526 depends on NET && NOTIFIER_ERROR_INJECTION
1528 This option provides the ability to inject artificial errors to
1529 netdevice notifier chain callbacks. It is controlled through debugfs
1530 interface /sys/kernel/debug/notifier-error-inject/netdev
1532 If the notifier call chain should be failed with some events
1533 notified, write the error code to "actions/<notifier event>/error".
1535 Example: Inject netdevice mtu change error (-22 = -EINVAL)
1537 # cd /sys/kernel/debug/notifier-error-inject/netdev
1538 # echo -22 > actions/NETDEV_CHANGEMTU/error
1539 # ip link set eth0 mtu 1024
1540 RTNETLINK answers: Invalid argument
1542 To compile this code as a module, choose M here: the module will
1543 be called netdev-notifier-error-inject.
1547 config FUNCTION_ERROR_INJECTION
1549 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
1551 config FAULT_INJECTION
1552 bool "Fault-injection framework"
1553 depends on DEBUG_KERNEL
1555 Provide fault-injection framework.
1556 For more details, see Documentation/fault-injection/.
1559 bool "Fault-injection capability for kmalloc"
1560 depends on FAULT_INJECTION
1561 depends on SLAB || SLUB
1563 Provide fault-injection capability for kmalloc.
1565 config FAIL_PAGE_ALLOC
1566 bool "Fault-injection capabilitiy for alloc_pages()"
1567 depends on FAULT_INJECTION
1569 Provide fault-injection capability for alloc_pages().
1571 config FAIL_MAKE_REQUEST
1572 bool "Fault-injection capability for disk IO"
1573 depends on FAULT_INJECTION && BLOCK
1575 Provide fault-injection capability for disk IO.
1577 config FAIL_IO_TIMEOUT
1578 bool "Fault-injection capability for faking disk interrupts"
1579 depends on FAULT_INJECTION && BLOCK
1581 Provide fault-injection capability on end IO handling. This
1582 will make the block layer "forget" an interrupt as configured,
1583 thus exercising the error handling.
1585 Only works with drivers that use the generic timeout handling,
1586 for others it wont do anything.
1589 bool "Fault-injection capability for futexes"
1591 depends on FAULT_INJECTION && FUTEX
1593 Provide fault-injection capability for futexes.
1595 config FAULT_INJECTION_DEBUG_FS
1596 bool "Debugfs entries for fault-injection capabilities"
1597 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1599 Enable configuration of fault-injection capabilities via debugfs.
1601 config FAIL_FUNCTION
1602 bool "Fault-injection capability for functions"
1603 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
1605 Provide function-based fault-injection capability.
1606 This will allow you to override a specific function with a return
1607 with given return value. As a result, function caller will see
1608 an error value and have to handle it. This is useful to test the
1609 error handling in various subsystems.
1611 config FAIL_MMC_REQUEST
1612 bool "Fault-injection capability for MMC IO"
1613 depends on FAULT_INJECTION_DEBUG_FS && MMC
1615 Provide fault-injection capability for MMC IO.
1616 This will make the mmc core return data errors. This is
1617 useful to test the error handling in the mmc block device
1618 and to test how the mmc host driver handles retries from
1621 config FAULT_INJECTION_STACKTRACE_FILTER
1622 bool "stacktrace filter for fault-injection capabilities"
1623 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1626 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86
1628 Provide stacktrace filter for fault-injection capabilities
1631 bool "Latency measuring infrastructure"
1632 depends on DEBUG_KERNEL
1633 depends on STACKTRACE_SUPPORT
1635 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86
1642 Enable this option if you want to use the LatencyTOP tool
1643 to find out which userspace is blocking on what kernel operations.
1645 source "kernel/trace/Kconfig"
1647 config PROVIDE_OHCI1394_DMA_INIT
1648 bool "Remote debugging over FireWire early on boot"
1649 depends on PCI && X86
1651 If you want to debug problems which hang or crash the kernel early
1652 on boot and the crashing machine has a FireWire port, you can use
1653 this feature to remotely access the memory of the crashed machine
1654 over FireWire. This employs remote DMA as part of the OHCI1394
1655 specification which is now the standard for FireWire controllers.
1657 With remote DMA, you can monitor the printk buffer remotely using
1658 firescope and access all memory below 4GB using fireproxy from gdb.
1659 Even controlling a kernel debugger is possible using remote DMA.
1663 If ohci1394_dma=early is used as boot parameter, it will initialize
1664 all OHCI1394 controllers which are found in the PCI config space.
1666 As all changes to the FireWire bus such as enabling and disabling
1667 devices cause a bus reset and thereby disable remote DMA for all
1668 devices, be sure to have the cable plugged and FireWire enabled on
1669 the debugging host before booting the debug target for debugging.
1671 This code (~1k) is freed after boot. By then, the firewire stack
1672 in charge of the OHCI-1394 controllers should be used instead.
1674 See Documentation/debugging-via-ohci1394.txt for more information.
1676 source "lib/kunit/Kconfig"
1678 menuconfig RUNTIME_TESTING_MENU
1679 bool "Runtime Testing"
1682 if RUNTIME_TESTING_MENU
1685 tristate "Linux Kernel Dump Test Tool Module"
1688 This module enables testing of the different dumping mechanisms by
1689 inducing system failures at predefined crash points.
1690 If you don't need it: say N
1691 Choose M here to compile this code as a module. The module will be
1694 Documentation on how to use the module can be found in
1695 Documentation/fault-injection/provoke-crashes.rst
1697 config TEST_LIST_SORT
1698 tristate "Linked list sorting test"
1699 depends on DEBUG_KERNEL || m
1701 Enable this to turn on 'list_sort()' function test. This test is
1702 executed only once during system boot (so affects only boot time),
1703 or at module load time.
1708 tristate "Array-based sort test"
1709 depends on DEBUG_KERNEL || m
1711 This option enables the self-test function of 'sort()' at boot,
1712 or at module load time.
1716 config KPROBES_SANITY_TEST
1717 bool "Kprobes sanity tests"
1718 depends on DEBUG_KERNEL
1721 This option provides for testing basic kprobes functionality on
1722 boot. Samples of kprobe and kretprobe are inserted and
1723 verified for functionality.
1725 Say N if you are unsure.
1727 config BACKTRACE_SELF_TEST
1728 tristate "Self test for the backtrace code"
1729 depends on DEBUG_KERNEL
1731 This option provides a kernel module that can be used to test
1732 the kernel stack backtrace code. This option is not useful
1733 for distributions or general kernels, but only for kernel
1734 developers working on architecture code.
1736 Note that if you want to also test saved backtraces, you will
1737 have to enable STACKTRACE as well.
1739 Say N if you are unsure.
1742 tristate "Red-Black tree test"
1743 depends on DEBUG_KERNEL
1745 A benchmark measuring the performance of the rbtree library.
1746 Also includes rbtree invariant checks.
1748 config REED_SOLOMON_TEST
1749 tristate "Reed-Solomon library test"
1750 depends on DEBUG_KERNEL || m
1752 select REED_SOLOMON_ENC16
1753 select REED_SOLOMON_DEC16
1755 This option enables the self-test function of rslib at boot,
1756 or at module load time.
1760 config INTERVAL_TREE_TEST
1761 tristate "Interval tree test"
1762 depends on DEBUG_KERNEL
1763 select INTERVAL_TREE
1765 A benchmark measuring the performance of the interval tree library
1768 tristate "Per cpu operations test"
1769 depends on m && DEBUG_KERNEL
1771 Enable this option to build test module which validates per-cpu
1776 config ATOMIC64_SELFTEST
1777 tristate "Perform an atomic64_t self-test"
1779 Enable this option to test the atomic64_t functions at boot or
1780 at module load time.
1784 config ASYNC_RAID6_TEST
1785 tristate "Self test for hardware accelerated raid6 recovery"
1786 depends on ASYNC_RAID6_RECOV
1789 This is a one-shot self test that permutes through the
1790 recovery of all the possible two disk failure scenarios for a
1791 N-disk array. Recovery is performed with the asynchronous
1792 raid6 recovery routines, and will optionally use an offload
1793 engine if one is available.
1798 tristate "Test functions located in the hexdump module at runtime"
1800 config TEST_STRING_HELPERS
1801 tristate "Test functions located in the string_helpers module at runtime"
1804 tristate "Test strscpy*() family of functions at runtime"
1807 tristate "Test kstrto*() family of functions at runtime"
1810 tristate "Test printf() family of functions at runtime"
1813 tristate "Test bitmap_*() family of functions at runtime"
1815 Enable this option to test the bitmap functions at boot.
1819 config TEST_BITFIELD
1820 tristate "Test bitfield functions at runtime"
1822 Enable this option to test the bitfield functions at boot.
1827 tristate "Test functions located in the uuid module at runtime"
1830 tristate "Test the XArray code at runtime"
1832 config TEST_OVERFLOW
1833 tristate "Test check_*_overflow() functions at runtime"
1835 config TEST_RHASHTABLE
1836 tristate "Perform selftest on resizable hash table"
1838 Enable this option to test the rhashtable functions at boot.
1843 tristate "Perform selftest on hash functions"
1845 Enable this option to test the kernel's integer (<linux/hash.h>),
1846 string (<linux/stringhash.h>), and siphash (<linux/siphash.h>)
1847 hash functions on boot (or module load).
1849 This is intended to help people writing architecture-specific
1850 optimized versions. If unsure, say N.
1853 tristate "Perform selftest on IDA functions"
1856 tristate "Perform selftest on priority array manager"
1859 Enable this option to test priority array manager on boot
1864 config TEST_IRQ_TIMINGS
1865 bool "IRQ timings selftest"
1866 depends on IRQ_TIMINGS
1868 Enable this option to test the irq timings code on boot.
1873 tristate "Test module loading with 'hello world' module"
1876 This builds the "test_module" module that emits "Hello, world"
1877 on printk when loaded. It is designed to be used for basic
1878 evaluation of the module loading subsystem (for example when
1879 validating module verification). It lacks any extra dependencies,
1880 and will not normally be loaded by the system unless explicitly
1886 tristate "Test module for stress/performance analysis of vmalloc allocator"
1891 This builds the "test_vmalloc" module that should be used for
1892 stress and performance analysis. So, any new change for vmalloc
1893 subsystem can be evaluated from performance and stability point
1898 config TEST_USER_COPY
1899 tristate "Test user/kernel boundary protections"
1902 This builds the "test_user_copy" module that runs sanity checks
1903 on the copy_to/from_user infrastructure, making sure basic
1904 user/kernel boundary testing is working. If it fails to load,
1905 a regression has been detected in the user/kernel memory boundary
1911 tristate "Test BPF filter functionality"
1914 This builds the "test_bpf" module that runs various test vectors
1915 against the BPF interpreter or BPF JIT compiler depending on the
1916 current setting. This is in particular useful for BPF JIT compiler
1917 development, but also to run regression tests against changes in
1918 the interpreter code. It also enables test stubs for eBPF maps and
1919 verifier used by user space verifier testsuite.
1923 config TEST_BLACKHOLE_DEV
1924 tristate "Test blackhole netdev functionality"
1927 This builds the "test_blackhole_dev" module that validates the
1928 data path through this blackhole netdev.
1932 config FIND_BIT_BENCHMARK
1933 tristate "Test find_bit functions"
1935 This builds the "test_find_bit" module that measure find_*_bit()
1936 functions performance.
1940 config TEST_FIRMWARE
1941 tristate "Test firmware loading via userspace interface"
1942 depends on FW_LOADER
1944 This builds the "test_firmware" module that creates a userspace
1945 interface for testing firmware loading. This can be used to
1946 control the triggering of firmware loading without needing an
1947 actual firmware-using device. The contents can be rechecked by
1953 tristate "sysctl test driver"
1954 depends on PROC_SYSCTL
1956 This builds the "test_sysctl" module. This driver enables to test the
1957 proc sysctl interfaces available to drivers safely without affecting
1958 production knobs which might alter system functionality.
1962 config SYSCTL_KUNIT_TEST
1963 bool "KUnit test for sysctl"
1966 This builds the proc sysctl unit test, which runs on boot.
1967 Tests the API contract and implementation correctness of sysctl.
1968 For more information on KUnit and unit tests in general please refer
1969 to the KUnit documentation in Documentation/dev-tools/kunit/.
1973 config LIST_KUNIT_TEST
1974 bool "KUnit Test for Kernel Linked-list structures"
1977 This builds the linked list KUnit test suite.
1978 It tests that the API and basic functionality of the list_head type
1979 and associated macros.
1981 KUnit tests run during boot and output the results to the debug log
1982 in TAP format (http://testanything.org/). Only useful for kernel devs
1983 running the KUnit test harness, and not intended for inclusion into a
1986 For more information on KUnit and unit tests in general please refer
1987 to the KUnit documentation in Documentation/dev-tools/kunit/.
1992 tristate "udelay test driver"
1994 This builds the "udelay_test" module that helps to make sure
1995 that udelay() is working properly.
1999 config TEST_STATIC_KEYS
2000 tristate "Test static keys"
2003 Test the static key interfaces.
2008 tristate "kmod stress tester"
2010 depends on NETDEVICES && NET_CORE && INET # for TUN
2017 Test the kernel's module loading mechanism: kmod. kmod implements
2018 support to load modules using the Linux kernel's usermode helper.
2019 This test provides a series of tests against kmod.
2021 Although technically you can either build test_kmod as a module or
2022 into the kernel we disallow building it into the kernel since
2023 it stress tests request_module() and this will very likely cause
2024 some issues by taking over precious threads available from other
2025 module load requests, ultimately this could be fatal.
2029 tools/testing/selftests/kmod/kmod.sh --help
2033 config TEST_DEBUG_VIRTUAL
2034 tristate "Test CONFIG_DEBUG_VIRTUAL feature"
2035 depends on DEBUG_VIRTUAL
2037 Test the kernel's ability to detect incorrect calls to
2038 virt_to_phys() done against the non-linear part of the
2039 kernel's virtual address map.
2043 config TEST_MEMCAT_P
2044 tristate "Test memcat_p() helper function"
2046 Test the memcat_p() helper for correctly merging two
2047 pointer arrays together.
2051 config TEST_LIVEPATCH
2052 tristate "Test livepatching"
2054 depends on DYNAMIC_DEBUG
2055 depends on LIVEPATCH
2058 Test kernel livepatching features for correctness. The tests will
2059 load test modules that will be livepatched in various scenarios.
2061 To run all the livepatching tests:
2063 make -C tools/testing/selftests TARGETS=livepatch run_tests
2065 Alternatively, individual tests may be invoked:
2067 tools/testing/selftests/livepatch/test-callbacks.sh
2068 tools/testing/selftests/livepatch/test-livepatch.sh
2069 tools/testing/selftests/livepatch/test-shadow-vars.sh
2074 tristate "Perform selftest on object aggreration manager"
2078 Enable this option to test object aggregation manager on boot
2082 config TEST_STACKINIT
2083 tristate "Test level of stack variable initialization"
2085 Test if the kernel is zero-initializing stack variables and
2086 padding. Coverage is controlled by compiler flags,
2087 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2088 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2093 tristate "Test heap/page initialization"
2095 Test if the kernel is zero-initializing heap and page allocations.
2096 This can be useful to test init_on_alloc and init_on_free features.
2100 endif # RUNTIME_TESTING_MENU
2105 This option adds a kernel parameter 'memtest', which allows memtest
2107 memtest=0, mean disabled; -- default
2108 memtest=1, mean do 1 test pattern;
2110 memtest=17, mean do 17 test patterns.
2111 If you are unsure how to answer this question, answer N.
2113 config BUG_ON_DATA_CORRUPTION
2114 bool "Trigger a BUG when data corruption is detected"
2117 Select this option if the kernel should BUG when it encounters
2118 data corruption in kernel memory structures when they get checked
2123 source "samples/Kconfig"
2125 source "lib/Kconfig.kgdb"
2127 source "lib/Kconfig.ubsan"
2129 config ARCH_HAS_DEVMEM_IS_ALLOWED
2132 config STRICT_DEVMEM
2133 bool "Filter access to /dev/mem"
2134 depends on MMU && DEVMEM
2135 depends on ARCH_HAS_DEVMEM_IS_ALLOWED
2136 default y if PPC || X86 || ARM64
2138 If this option is disabled, you allow userspace (root) access to all
2139 of memory, including kernel and userspace memory. Accidental
2140 access to this is obviously disastrous, but specific access can
2141 be used by people debugging the kernel. Note that with PAT support
2142 enabled, even in this case there are restrictions on /dev/mem
2143 use due to the cache aliasing requirements.
2145 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
2146 file only allows userspace access to PCI space and the BIOS code and
2147 data regions. This is sufficient for dosemu and X and all common
2152 config IO_STRICT_DEVMEM
2153 bool "Filter I/O access to /dev/mem"
2154 depends on STRICT_DEVMEM
2156 If this option is disabled, you allow userspace (root) access to all
2157 io-memory regardless of whether a driver is actively using that
2158 range. Accidental access to this is obviously disastrous, but
2159 specific access can be used by people debugging kernel drivers.
2161 If this option is switched on, the /dev/mem file only allows
2162 userspace access to *idle* io-memory ranges (see /proc/iomem) This
2163 may break traditional users of /dev/mem (dosemu, legacy X, etc...)
2164 if the driver using a given range cannot be disabled.
2168 source "arch/$(SRCARCH)/Kconfig.debug"
2170 config HYPERV_TESTING
2171 bool "Microsoft Hyper-V driver testing"
2173 depends on HYPERV && DEBUG_FS
2175 Select this option to enable Hyper-V vmbus testing.
2177 endmenu # Kernel hacking
projects / linux-2.6-microblaze.git / blob