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"
403 bool "Magic SysRq key"
406 If you say Y here, you will have some control over the system even
407 if the system crashes for example during kernel debugging (e.g., you
408 will be able to flush the buffer cache to disk, reboot the system
409 immediately or dump some status information). This is accomplished
410 by pressing various keys while holding SysRq (Alt+PrintScreen). It
411 also works on a serial console (on PC hardware at least), if you
412 send a BREAK and then within 5 seconds a command keypress. The
413 keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
414 Don't say Y unless you really know what this hack does.
416 config MAGIC_SYSRQ_DEFAULT_ENABLE
417 hex "Enable magic SysRq key functions by default"
418 depends on MAGIC_SYSRQ
421 Specifies which SysRq key functions are enabled by default.
422 This may be set to 1 or 0 to enable or disable them all, or
423 to a bitmask as described in Documentation/admin-guide/sysrq.rst.
425 config MAGIC_SYSRQ_SERIAL
426 bool "Enable magic SysRq key over serial"
427 depends on MAGIC_SYSRQ
430 Many embedded boards have a disconnected TTL level serial which can
431 generate some garbage that can lead to spurious false sysrq detects.
432 This option allows you to decide whether you want to enable the
436 bool "Kernel debugging"
438 Say Y here if you are developing drivers or trying to debug and
439 identify kernel problems.
442 bool "Miscellaneous debug code"
444 depends on DEBUG_KERNEL
446 Say Y here if you need to enable miscellaneous debug code that should
447 be under a more specific debug option but isn't.
450 menu "Memory Debugging"
452 source "mm/Kconfig.debug"
455 bool "Debug object operations"
456 depends on DEBUG_KERNEL
458 If you say Y here, additional code will be inserted into the
459 kernel to track the life time of various objects and validate
460 the operations on those objects.
462 config DEBUG_OBJECTS_SELFTEST
463 bool "Debug objects selftest"
464 depends on DEBUG_OBJECTS
466 This enables the selftest of the object debug code.
468 config DEBUG_OBJECTS_FREE
469 bool "Debug objects in freed memory"
470 depends on DEBUG_OBJECTS
472 This enables checks whether a k/v free operation frees an area
473 which contains an object which has not been deactivated
474 properly. This can make kmalloc/kfree-intensive workloads
477 config DEBUG_OBJECTS_TIMERS
478 bool "Debug timer objects"
479 depends on DEBUG_OBJECTS
481 If you say Y here, additional code will be inserted into the
482 timer routines to track the life time of timer objects and
483 validate the timer operations.
485 config DEBUG_OBJECTS_WORK
486 bool "Debug work objects"
487 depends on DEBUG_OBJECTS
489 If you say Y here, additional code will be inserted into the
490 work queue routines to track the life time of work objects and
491 validate the work operations.
493 config DEBUG_OBJECTS_RCU_HEAD
494 bool "Debug RCU callbacks objects"
495 depends on DEBUG_OBJECTS
497 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
499 config DEBUG_OBJECTS_PERCPU_COUNTER
500 bool "Debug percpu counter objects"
501 depends on DEBUG_OBJECTS
503 If you say Y here, additional code will be inserted into the
504 percpu counter routines to track the life time of percpu counter
505 objects and validate the percpu counter operations.
507 config DEBUG_OBJECTS_ENABLE_DEFAULT
508 int "debug_objects bootup default value (0-1)"
511 depends on DEBUG_OBJECTS
513 Debug objects boot parameter default value
516 bool "Debug slab memory allocations"
517 depends on DEBUG_KERNEL && SLAB
519 Say Y here to have the kernel do limited verification on memory
520 allocation as well as poisoning memory on free to catch use of freed
521 memory. This can make kmalloc/kfree-intensive workloads much slower.
524 bool "SLUB debugging on by default"
525 depends on SLUB && SLUB_DEBUG
528 Boot with debugging on by default. SLUB boots by default with
529 the runtime debug capabilities switched off. Enabling this is
530 equivalent to specifying the "slub_debug" parameter on boot.
531 There is no support for more fine grained debug control like
532 possible with slub_debug=xxx. SLUB debugging may be switched
533 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
538 bool "Enable SLUB performance statistics"
539 depends on SLUB && SYSFS
541 SLUB statistics are useful to debug SLUBs allocation behavior in
542 order find ways to optimize the allocator. This should never be
543 enabled for production use since keeping statistics slows down
544 the allocator by a few percentage points. The slabinfo command
545 supports the determination of the most active slabs to figure
546 out which slabs are relevant to a particular load.
547 Try running: slabinfo -DA
549 config HAVE_DEBUG_KMEMLEAK
552 config DEBUG_KMEMLEAK
553 bool "Kernel memory leak detector"
554 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
556 select STACKTRACE if STACKTRACE_SUPPORT
560 Say Y here if you want to enable the memory leak
561 detector. The memory allocation/freeing is traced in a way
562 similar to the Boehm's conservative garbage collector, the
563 difference being that the orphan objects are not freed but
564 only shown in /sys/kernel/debug/kmemleak. Enabling this
565 feature will introduce an overhead to memory
566 allocations. See Documentation/dev-tools/kmemleak.rst for more
569 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
570 of finding leaks due to the slab objects poisoning.
572 In order to access the kmemleak file, debugfs needs to be
573 mounted (usually at /sys/kernel/debug).
575 config DEBUG_KMEMLEAK_MEM_POOL_SIZE
576 int "Kmemleak memory pool size"
577 depends on DEBUG_KMEMLEAK
581 Kmemleak must track all the memory allocations to avoid
582 reporting false positives. Since memory may be allocated or
583 freed before kmemleak is fully initialised, use a static pool
584 of metadata objects to track such callbacks. After kmemleak is
585 fully initialised, this memory pool acts as an emergency one
586 if slab allocations fail.
588 config DEBUG_KMEMLEAK_TEST
589 tristate "Simple test for the kernel memory leak detector"
590 depends on DEBUG_KMEMLEAK && m
592 This option enables a module that explicitly leaks memory.
596 config DEBUG_KMEMLEAK_DEFAULT_OFF
597 bool "Default kmemleak to off"
598 depends on DEBUG_KMEMLEAK
600 Say Y here to disable kmemleak by default. It can then be enabled
601 on the command line via kmemleak=on.
603 config DEBUG_KMEMLEAK_AUTO_SCAN
604 bool "Enable kmemleak auto scan thread on boot up"
606 depends on DEBUG_KMEMLEAK
608 Depending on the cpu, kmemleak scan may be cpu intensive and can
609 stall user tasks at times. This option enables/disables automatic
610 kmemleak scan at boot up.
612 Say N here to disable kmemleak auto scan thread to stop automatic
613 scanning. Disabling this option disables automatic reporting of
618 config DEBUG_STACK_USAGE
619 bool "Stack utilization instrumentation"
620 depends on DEBUG_KERNEL && !IA64
622 Enables the display of the minimum amount of free stack which each
623 task has ever had available in the sysrq-T and sysrq-P debug output.
625 This option will slow down process creation somewhat.
629 depends on DEBUG_KERNEL
631 Enable this to turn on extended checks in the virtual-memory system
632 that may impact performance.
636 config DEBUG_VM_VMACACHE
637 bool "Debug VMA caching"
640 Enable this to turn on VMA caching debug information. Doing so
641 can cause significant overhead, so only enable it in non-production
647 bool "Debug VM red-black trees"
650 Enable VM red-black tree debugging information and extra validations.
654 config DEBUG_VM_PGFLAGS
655 bool "Debug page-flags operations"
658 Enables extra validation on page flags operations.
662 config ARCH_HAS_DEBUG_VIRTUAL
666 bool "Debug VM translations"
667 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
669 Enable some costly sanity checks in virtual to page code. This can
670 catch mistakes with virt_to_page() and friends.
674 config DEBUG_NOMMU_REGIONS
675 bool "Debug the global anon/private NOMMU mapping region tree"
676 depends on DEBUG_KERNEL && !MMU
678 This option causes the global tree of anonymous and private mapping
679 regions to be regularly checked for invalid topology.
681 config DEBUG_MEMORY_INIT
682 bool "Debug memory initialisation" if EXPERT
685 Enable this for additional checks during memory initialisation.
686 The sanity checks verify aspects of the VM such as the memory model
687 and other information provided by the architecture. Verbose
688 information will be printed at KERN_DEBUG loglevel depending
689 on the mminit_loglevel= command-line option.
693 config MEMORY_NOTIFIER_ERROR_INJECT
694 tristate "Memory hotplug notifier error injection module"
695 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
697 This option provides the ability to inject artificial errors to
698 memory hotplug notifier chain callbacks. It is controlled through
699 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
701 If the notifier call chain should be failed with some events
702 notified, write the error code to "actions/<notifier event>/error".
704 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
706 # cd /sys/kernel/debug/notifier-error-inject/memory
707 # echo -12 > actions/MEM_GOING_OFFLINE/error
708 # echo offline > /sys/devices/system/memory/memoryXXX/state
709 bash: echo: write error: Cannot allocate memory
711 To compile this code as a module, choose M here: the module will
712 be called memory-notifier-error-inject.
716 config DEBUG_PER_CPU_MAPS
717 bool "Debug access to per_cpu maps"
718 depends on DEBUG_KERNEL
721 Say Y to verify that the per_cpu map being accessed has
722 been set up. This adds a fair amount of code to kernel memory
723 and decreases performance.
728 bool "Highmem debugging"
729 depends on DEBUG_KERNEL && HIGHMEM
731 This option enables additional error checking for high memory
732 systems. Disable for production systems.
734 config HAVE_DEBUG_STACKOVERFLOW
737 config DEBUG_STACKOVERFLOW
738 bool "Check for stack overflows"
739 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
741 Say Y here if you want to check for overflows of kernel, IRQ
742 and exception stacks (if your architecture uses them). This
743 option will show detailed messages if free stack space drops
744 below a certain limit.
746 These kinds of bugs usually occur when call-chains in the
747 kernel get too deep, especially when interrupts are
750 Use this in cases where you see apparently random memory
751 corruption, especially if it appears in 'struct thread_info'
753 If in doubt, say "N".
755 source "lib/Kconfig.kasan"
757 endmenu # "Memory Debugging"
762 An architecture should select this when it can successfully
763 build and run with CONFIG_KCOV. This typically requires
764 disabling instrumentation for some early boot code.
766 config CC_HAS_SANCOV_TRACE_PC
767 def_bool $(cc-option,-fsanitize-coverage=trace-pc)
770 bool "Code coverage for fuzzing"
771 depends on ARCH_HAS_KCOV
772 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
774 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
776 KCOV exposes kernel code coverage information in a form suitable
777 for coverage-guided fuzzing (randomized testing).
779 If RANDOMIZE_BASE is enabled, PC values will not be stable across
780 different machines and across reboots. If you need stable PC values,
781 disable RANDOMIZE_BASE.
783 For more details, see Documentation/dev-tools/kcov.rst.
785 config KCOV_ENABLE_COMPARISONS
786 bool "Enable comparison operands collection by KCOV"
788 depends on $(cc-option,-fsanitize-coverage=trace-cmp)
790 KCOV also exposes operands of every comparison in the instrumented
791 code along with operand sizes and PCs of the comparison instructions.
792 These operands can be used by fuzzing engines to improve the quality
795 config KCOV_INSTRUMENT_ALL
796 bool "Instrument all code by default"
800 If you are doing generic system call fuzzing (like e.g. syzkaller),
801 then you will want to instrument the whole kernel and you should
802 say y here. If you are doing more targeted fuzzing (like e.g.
803 filesystem fuzzing with AFL) then you will want to enable coverage
804 for more specific subsets of files, and should say n here.
807 bool "Debug shared IRQ handlers"
808 depends on DEBUG_KERNEL
810 Enable this to generate a spurious interrupt as soon as a shared
811 interrupt handler is registered, and just before one is deregistered.
812 Drivers ought to be able to handle interrupts coming in at those
813 points; some don't and need to be caught.
815 menu "Debug Lockups and Hangs"
817 config LOCKUP_DETECTOR
820 config SOFTLOCKUP_DETECTOR
821 bool "Detect Soft Lockups"
822 depends on DEBUG_KERNEL && !S390
823 select LOCKUP_DETECTOR
825 Say Y here to enable the kernel to act as a watchdog to detect
828 Softlockups are bugs that cause the kernel to loop in kernel
829 mode for more than 20 seconds, without giving other tasks a
830 chance to run. The current stack trace is displayed upon
831 detection and the system will stay locked up.
833 config BOOTPARAM_SOFTLOCKUP_PANIC
834 bool "Panic (Reboot) On Soft Lockups"
835 depends on SOFTLOCKUP_DETECTOR
837 Say Y here to enable the kernel to panic on "soft lockups",
838 which are bugs that cause the kernel to loop in kernel
839 mode for more than 20 seconds (configurable using the watchdog_thresh
840 sysctl), without giving other tasks a chance to run.
842 The panic can be used in combination with panic_timeout,
843 to cause the system to reboot automatically after a
844 lockup has been detected. This feature is useful for
845 high-availability systems that have uptime guarantees and
846 where a lockup must be resolved ASAP.
850 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
852 depends on SOFTLOCKUP_DETECTOR
854 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
855 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
857 config HARDLOCKUP_DETECTOR_PERF
859 select SOFTLOCKUP_DETECTOR
862 # Enables a timestamp based low pass filter to compensate for perf based
863 # hard lockup detection which runs too fast due to turbo modes.
865 config HARDLOCKUP_CHECK_TIMESTAMP
869 # arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard
870 # lockup detector rather than the perf based detector.
872 config HARDLOCKUP_DETECTOR
873 bool "Detect Hard Lockups"
874 depends on DEBUG_KERNEL && !S390
875 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH
876 select LOCKUP_DETECTOR
877 select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF
878 select HARDLOCKUP_DETECTOR_ARCH if HAVE_HARDLOCKUP_DETECTOR_ARCH
880 Say Y here to enable the kernel to act as a watchdog to detect
883 Hardlockups are bugs that cause the CPU to loop in kernel mode
884 for more than 10 seconds, without letting other interrupts have a
885 chance to run. The current stack trace is displayed upon detection
886 and the system will stay locked up.
888 config BOOTPARAM_HARDLOCKUP_PANIC
889 bool "Panic (Reboot) On Hard Lockups"
890 depends on HARDLOCKUP_DETECTOR
892 Say Y here to enable the kernel to panic on "hard lockups",
893 which are bugs that cause the kernel to loop in kernel
894 mode with interrupts disabled for more than 10 seconds (configurable
895 using the watchdog_thresh sysctl).
899 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
901 depends on HARDLOCKUP_DETECTOR
903 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
904 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
906 config DETECT_HUNG_TASK
907 bool "Detect Hung Tasks"
908 depends on DEBUG_KERNEL
909 default SOFTLOCKUP_DETECTOR
911 Say Y here to enable the kernel to detect "hung tasks",
912 which are bugs that cause the task to be stuck in
913 uninterruptible "D" state indefinitely.
915 When a hung task is detected, the kernel will print the
916 current stack trace (which you should report), but the
917 task will stay in uninterruptible state. If lockdep is
918 enabled then all held locks will also be reported. This
919 feature has negligible overhead.
921 config DEFAULT_HUNG_TASK_TIMEOUT
922 int "Default timeout for hung task detection (in seconds)"
923 depends on DETECT_HUNG_TASK
926 This option controls the default timeout (in seconds) used
927 to determine when a task has become non-responsive and should
930 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
931 sysctl or by writing a value to
932 /proc/sys/kernel/hung_task_timeout_secs.
934 A timeout of 0 disables the check. The default is two minutes.
935 Keeping the default should be fine in most cases.
937 config BOOTPARAM_HUNG_TASK_PANIC
938 bool "Panic (Reboot) On Hung Tasks"
939 depends on DETECT_HUNG_TASK
941 Say Y here to enable the kernel to panic on "hung tasks",
942 which are bugs that cause the kernel to leave a task stuck
943 in uninterruptible "D" state.
945 The panic can be used in combination with panic_timeout,
946 to cause the system to reboot automatically after a
947 hung task has been detected. This feature is useful for
948 high-availability systems that have uptime guarantees and
949 where a hung tasks must be resolved ASAP.
953 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
955 depends on DETECT_HUNG_TASK
957 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
958 default 1 if BOOTPARAM_HUNG_TASK_PANIC
961 bool "Detect Workqueue Stalls"
962 depends on DEBUG_KERNEL
964 Say Y here to enable stall detection on workqueues. If a
965 worker pool doesn't make forward progress on a pending work
966 item for over a given amount of time, 30s by default, a
967 warning message is printed along with dump of workqueue
968 state. This can be configured through kernel parameter
969 "workqueue.watchdog_thresh" and its sysfs counterpart.
971 endmenu # "Debug lockups and hangs"
976 Say Y here to enable the kernel to panic when it oopses. This
977 has the same effect as setting oops=panic on the kernel command
980 This feature is useful to ensure that the kernel does not do
981 anything erroneous after an oops which could result in data
982 corruption or other issues.
986 config PANIC_ON_OOPS_VALUE
989 default 0 if !PANIC_ON_OOPS
990 default 1 if PANIC_ON_OOPS
996 Set the timeout value (in seconds) until a reboot occurs when the
997 the kernel panics. If n = 0, then we wait forever. A timeout
998 value n > 0 will wait n seconds before rebooting, while a timeout
999 value n < 0 will reboot immediately.
1002 bool "Collect scheduler debugging info"
1003 depends on DEBUG_KERNEL && PROC_FS
1006 If you say Y here, the /proc/sched_debug file will be provided
1007 that can help debug the scheduler. The runtime overhead of this
1015 bool "Collect scheduler statistics"
1016 depends on DEBUG_KERNEL && PROC_FS
1019 If you say Y here, additional code will be inserted into the
1020 scheduler and related routines to collect statistics about
1021 scheduler behavior and provide them in /proc/schedstat. These
1022 stats may be useful for both tuning and debugging the scheduler
1023 If you aren't debugging the scheduler or trying to tune a specific
1024 application, you can say N to avoid the very slight overhead
1027 config SCHED_STACK_END_CHECK
1028 bool "Detect stack corruption on calls to schedule()"
1029 depends on DEBUG_KERNEL
1032 This option checks for a stack overrun on calls to schedule().
1033 If the stack end location is found to be over written always panic as
1034 the content of the corrupted region can no longer be trusted.
1035 This is to ensure no erroneous behaviour occurs which could result in
1036 data corruption or a sporadic crash at a later stage once the region
1037 is examined. The runtime overhead introduced is minimal.
1039 config DEBUG_TIMEKEEPING
1040 bool "Enable extra timekeeping sanity checking"
1042 This option will enable additional timekeeping sanity checks
1043 which may be helpful when diagnosing issues where timekeeping
1044 problems are suspected.
1046 This may include checks in the timekeeping hotpaths, so this
1047 option may have a (very small) performance impact to some
1052 config DEBUG_PREEMPT
1053 bool "Debug preemptible kernel"
1054 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
1057 If you say Y here then the kernel will use a debug variant of the
1058 commonly used smp_processor_id() function and will print warnings
1059 if kernel code uses it in a preemption-unsafe way. Also, the kernel
1060 will detect preemption count underflows.
1062 menu "Lock Debugging (spinlocks, mutexes, etc...)"
1064 config LOCK_DEBUGGING_SUPPORT
1066 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1069 config PROVE_LOCKING
1070 bool "Lock debugging: prove locking correctness"
1071 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1073 select DEBUG_SPINLOCK
1074 select DEBUG_MUTEXES
1075 select DEBUG_RT_MUTEXES if RT_MUTEXES
1077 select DEBUG_WW_MUTEX_SLOWPATH
1078 select DEBUG_LOCK_ALLOC
1079 select TRACE_IRQFLAGS
1082 This feature enables the kernel to prove that all locking
1083 that occurs in the kernel runtime is mathematically
1084 correct: that under no circumstance could an arbitrary (and
1085 not yet triggered) combination of observed locking
1086 sequences (on an arbitrary number of CPUs, running an
1087 arbitrary number of tasks and interrupt contexts) cause a
1090 In short, this feature enables the kernel to report locking
1091 related deadlocks before they actually occur.
1093 The proof does not depend on how hard and complex a
1094 deadlock scenario would be to trigger: how many
1095 participant CPUs, tasks and irq-contexts would be needed
1096 for it to trigger. The proof also does not depend on
1097 timing: if a race and a resulting deadlock is possible
1098 theoretically (no matter how unlikely the race scenario
1099 is), it will be proven so and will immediately be
1100 reported by the kernel (once the event is observed that
1101 makes the deadlock theoretically possible).
1103 If a deadlock is impossible (i.e. the locking rules, as
1104 observed by the kernel, are mathematically correct), the
1105 kernel reports nothing.
1107 NOTE: this feature can also be enabled for rwlocks, mutexes
1108 and rwsems - in which case all dependencies between these
1109 different locking variants are observed and mapped too, and
1110 the proof of observed correctness is also maintained for an
1111 arbitrary combination of these separate locking variants.
1113 For more details, see Documentation/locking/lockdep-design.rst.
1116 bool "Lock usage statistics"
1117 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1119 select DEBUG_SPINLOCK
1120 select DEBUG_MUTEXES
1121 select DEBUG_RT_MUTEXES if RT_MUTEXES
1122 select DEBUG_LOCK_ALLOC
1125 This feature enables tracking lock contention points
1127 For more details, see Documentation/locking/lockstat.rst
1129 This also enables lock events required by "perf lock",
1131 If you want to use "perf lock", you also need to turn on
1132 CONFIG_EVENT_TRACING.
1134 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1135 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1137 config DEBUG_RT_MUTEXES
1138 bool "RT Mutex debugging, deadlock detection"
1139 depends on DEBUG_KERNEL && RT_MUTEXES
1141 This allows rt mutex semantics violations and rt mutex related
1142 deadlocks (lockups) to be detected and reported automatically.
1144 config DEBUG_SPINLOCK
1145 bool "Spinlock and rw-lock debugging: basic checks"
1146 depends on DEBUG_KERNEL
1147 select UNINLINE_SPIN_UNLOCK
1149 Say Y here and build SMP to catch missing spinlock initialization
1150 and certain other kinds of spinlock errors commonly made. This is
1151 best used in conjunction with the NMI watchdog so that spinlock
1152 deadlocks are also debuggable.
1154 config DEBUG_MUTEXES
1155 bool "Mutex debugging: basic checks"
1156 depends on DEBUG_KERNEL
1158 This feature allows mutex semantics violations to be detected and
1161 config DEBUG_WW_MUTEX_SLOWPATH
1162 bool "Wait/wound mutex debugging: Slowpath testing"
1163 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1164 select DEBUG_LOCK_ALLOC
1165 select DEBUG_SPINLOCK
1166 select DEBUG_MUTEXES
1168 This feature enables slowpath testing for w/w mutex users by
1169 injecting additional -EDEADLK wound/backoff cases. Together with
1170 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1171 will test all possible w/w mutex interface abuse with the
1172 exception of simply not acquiring all the required locks.
1173 Note that this feature can introduce significant overhead, so
1174 it really should not be enabled in a production or distro kernel,
1175 even a debug kernel. If you are a driver writer, enable it. If
1176 you are a distro, do not.
1179 bool "RW Semaphore debugging: basic checks"
1180 depends on DEBUG_KERNEL
1182 This debugging feature allows mismatched rw semaphore locks
1183 and unlocks to be detected and reported.
1185 config DEBUG_LOCK_ALLOC
1186 bool "Lock debugging: detect incorrect freeing of live locks"
1187 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1188 select DEBUG_SPINLOCK
1189 select DEBUG_MUTEXES
1190 select DEBUG_RT_MUTEXES if RT_MUTEXES
1193 This feature will check whether any held lock (spinlock, rwlock,
1194 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1195 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1196 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1197 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1198 held during task exit.
1202 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1204 select FRAME_POINTER if !MIPS && !PPC && !ARM && !S390 && !MICROBLAZE && !ARC && !X86
1208 config LOCKDEP_SMALL
1211 config DEBUG_LOCKDEP
1212 bool "Lock dependency engine debugging"
1213 depends on DEBUG_KERNEL && LOCKDEP
1215 If you say Y here, the lock dependency engine will do
1216 additional runtime checks to debug itself, at the price
1217 of more runtime overhead.
1219 config DEBUG_ATOMIC_SLEEP
1220 bool "Sleep inside atomic section checking"
1221 select PREEMPT_COUNT
1222 depends on DEBUG_KERNEL
1223 depends on !ARCH_NO_PREEMPT
1225 If you say Y here, various routines which may sleep will become very
1226 noisy if they are called inside atomic sections: when a spinlock is
1227 held, inside an rcu read side critical section, inside preempt disabled
1228 sections, inside an interrupt, etc...
1230 config DEBUG_LOCKING_API_SELFTESTS
1231 bool "Locking API boot-time self-tests"
1232 depends on DEBUG_KERNEL
1234 Say Y here if you want the kernel to run a short self-test during
1235 bootup. The self-test checks whether common types of locking bugs
1236 are detected by debugging mechanisms or not. (if you disable
1237 lock debugging then those bugs wont be detected of course.)
1238 The following locking APIs are covered: spinlocks, rwlocks,
1241 config LOCK_TORTURE_TEST
1242 tristate "torture tests for locking"
1243 depends on DEBUG_KERNEL
1246 This option provides a kernel module that runs torture tests
1247 on kernel locking primitives. The kernel module may be built
1248 after the fact on the running kernel to be tested, if desired.
1250 Say Y here if you want kernel locking-primitive torture tests
1251 to be built into the kernel.
1252 Say M if you want these torture tests to build as a module.
1253 Say N if you are unsure.
1255 config WW_MUTEX_SELFTEST
1256 tristate "Wait/wound mutex selftests"
1258 This option provides a kernel module that runs tests on the
1259 on the struct ww_mutex locking API.
1261 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1262 with this test harness.
1264 Say M if you want these self tests to build as a module.
1265 Say N if you are unsure.
1267 endmenu # lock debugging
1269 config TRACE_IRQFLAGS
1272 Enables hooks to interrupt enabling and disabling for
1273 either tracing or lock debugging.
1276 bool "Stack backtrace support"
1277 depends on STACKTRACE_SUPPORT
1279 This option causes the kernel to create a /proc/pid/stack for
1280 every process, showing its current stack trace.
1281 It is also used by various kernel debugging features that require
1282 stack trace generation.
1284 config WARN_ALL_UNSEEDED_RANDOM
1285 bool "Warn for all uses of unseeded randomness"
1288 Some parts of the kernel contain bugs relating to their use of
1289 cryptographically secure random numbers before it's actually possible
1290 to generate those numbers securely. This setting ensures that these
1291 flaws don't go unnoticed, by enabling a message, should this ever
1292 occur. This will allow people with obscure setups to know when things
1293 are going wrong, so that they might contact developers about fixing
1296 Unfortunately, on some models of some architectures getting
1297 a fully seeded CRNG is extremely difficult, and so this can
1298 result in dmesg getting spammed for a surprisingly long
1299 time. This is really bad from a security perspective, and
1300 so architecture maintainers really need to do what they can
1301 to get the CRNG seeded sooner after the system is booted.
1302 However, since users cannot do anything actionable to
1303 address this, by default the kernel will issue only a single
1304 warning for the first use of unseeded randomness.
1306 Say Y here if you want to receive warnings for all uses of
1307 unseeded randomness. This will be of use primarily for
1308 those developers interested in improving the security of
1309 Linux kernels running on their architecture (or
1312 config DEBUG_KOBJECT
1313 bool "kobject debugging"
1314 depends on DEBUG_KERNEL
1316 If you say Y here, some extra kobject debugging messages will be sent
1319 config DEBUG_KOBJECT_RELEASE
1320 bool "kobject release debugging"
1321 depends on DEBUG_OBJECTS_TIMERS
1323 kobjects are reference counted objects. This means that their
1324 last reference count put is not predictable, and the kobject can
1325 live on past the point at which a driver decides to drop it's
1326 initial reference to the kobject gained on allocation. An
1327 example of this would be a struct device which has just been
1330 However, some buggy drivers assume that after such an operation,
1331 the memory backing the kobject can be immediately freed. This
1332 goes completely against the principles of a refcounted object.
1334 If you say Y here, the kernel will delay the release of kobjects
1335 on the last reference count to improve the visibility of this
1336 kind of kobject release bug.
1338 config HAVE_DEBUG_BUGVERBOSE
1341 config DEBUG_BUGVERBOSE
1342 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
1343 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
1346 Say Y here to make BUG() panics output the file name and line number
1347 of the BUG call as well as the EIP and oops trace. This aids
1348 debugging but costs about 70-100K of memory.
1351 bool "Debug linked list manipulation"
1352 depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION
1354 Enable this to turn on extended checks in the linked-list
1360 bool "Debug priority linked list manipulation"
1361 depends on DEBUG_KERNEL
1363 Enable this to turn on extended checks in the priority-ordered
1364 linked-list (plist) walking routines. This checks the entire
1365 list multiple times during each manipulation.
1370 bool "Debug SG table operations"
1371 depends on DEBUG_KERNEL
1373 Enable this to turn on checks on scatter-gather tables. This can
1374 help find problems with drivers that do not properly initialize
1379 config DEBUG_NOTIFIERS
1380 bool "Debug notifier call chains"
1381 depends on DEBUG_KERNEL
1383 Enable this to turn on sanity checking for notifier call chains.
1384 This is most useful for kernel developers to make sure that
1385 modules properly unregister themselves from notifier chains.
1386 This is a relatively cheap check but if you care about maximum
1389 config DEBUG_CREDENTIALS
1390 bool "Debug credential management"
1391 depends on DEBUG_KERNEL
1393 Enable this to turn on some debug checking for credential
1394 management. The additional code keeps track of the number of
1395 pointers from task_structs to any given cred struct, and checks to
1396 see that this number never exceeds the usage count of the cred
1399 Furthermore, if SELinux is enabled, this also checks that the
1400 security pointer in the cred struct is never seen to be invalid.
1404 source "kernel/rcu/Kconfig.debug"
1406 config DEBUG_WQ_FORCE_RR_CPU
1407 bool "Force round-robin CPU selection for unbound work items"
1408 depends on DEBUG_KERNEL
1411 Workqueue used to implicitly guarantee that work items queued
1412 without explicit CPU specified are put on the local CPU. This
1413 guarantee is no longer true and while local CPU is still
1414 preferred work items may be put on foreign CPUs. Kernel
1415 parameter "workqueue.debug_force_rr_cpu" is added to force
1416 round-robin CPU selection to flush out usages which depend on the
1417 now broken guarantee. This config option enables the debug
1418 feature by default. When enabled, memory and cache locality will
1421 config DEBUG_BLOCK_EXT_DEVT
1422 bool "Force extended block device numbers and spread them"
1423 depends on DEBUG_KERNEL
1427 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1428 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1429 YOU ARE DOING. Distros, please enable this and fix whatever
1432 Conventionally, block device numbers are allocated from
1433 predetermined contiguous area. However, extended block area
1434 may introduce non-contiguous block device numbers. This
1435 option forces most block device numbers to be allocated from
1436 the extended space and spreads them to discover kernel or
1437 userland code paths which assume predetermined contiguous
1438 device number allocation.
1440 Note that turning on this debug option shuffles all the
1441 device numbers for all IDE and SCSI devices including libata
1442 ones, so root partition specified using device number
1443 directly (via rdev or root=MAJ:MIN) won't work anymore.
1444 Textual device names (root=/dev/sdXn) will continue to work.
1446 Say N if you are unsure.
1448 config CPU_HOTPLUG_STATE_CONTROL
1449 bool "Enable CPU hotplug state control"
1450 depends on DEBUG_KERNEL
1451 depends on HOTPLUG_CPU
1454 Allows to write steps between "offline" and "online" to the CPUs
1455 sysfs target file so states can be stepped granular. This is a debug
1456 option for now as the hotplug machinery cannot be stopped and
1457 restarted at arbitrary points yet.
1459 Say N if your are unsure.
1461 config NOTIFIER_ERROR_INJECTION
1462 tristate "Notifier error injection"
1463 depends on DEBUG_KERNEL
1466 This option provides the ability to inject artificial errors to
1467 specified notifier chain callbacks. It is useful to test the error
1468 handling of notifier call chain failures.
1472 config PM_NOTIFIER_ERROR_INJECT
1473 tristate "PM notifier error injection module"
1474 depends on PM && NOTIFIER_ERROR_INJECTION
1475 default m if PM_DEBUG
1477 This option provides the ability to inject artificial errors to
1478 PM notifier chain callbacks. It is controlled through debugfs
1479 interface /sys/kernel/debug/notifier-error-inject/pm
1481 If the notifier call chain should be failed with some events
1482 notified, write the error code to "actions/<notifier event>/error".
1484 Example: Inject PM suspend error (-12 = -ENOMEM)
1486 # cd /sys/kernel/debug/notifier-error-inject/pm/
1487 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1488 # echo mem > /sys/power/state
1489 bash: echo: write error: Cannot allocate memory
1491 To compile this code as a module, choose M here: the module will
1492 be called pm-notifier-error-inject.
1496 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1497 tristate "OF reconfig notifier error injection module"
1498 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1500 This option provides the ability to inject artificial errors to
1501 OF reconfig notifier chain callbacks. It is controlled
1502 through debugfs interface under
1503 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1505 If the notifier call chain should be failed with some events
1506 notified, write the error code to "actions/<notifier event>/error".
1508 To compile this code as a module, choose M here: the module will
1509 be called of-reconfig-notifier-error-inject.
1513 config NETDEV_NOTIFIER_ERROR_INJECT
1514 tristate "Netdev notifier error injection module"
1515 depends on NET && NOTIFIER_ERROR_INJECTION
1517 This option provides the ability to inject artificial errors to
1518 netdevice notifier chain callbacks. It is controlled through debugfs
1519 interface /sys/kernel/debug/notifier-error-inject/netdev
1521 If the notifier call chain should be failed with some events
1522 notified, write the error code to "actions/<notifier event>/error".
1524 Example: Inject netdevice mtu change error (-22 = -EINVAL)
1526 # cd /sys/kernel/debug/notifier-error-inject/netdev
1527 # echo -22 > actions/NETDEV_CHANGEMTU/error
1528 # ip link set eth0 mtu 1024
1529 RTNETLINK answers: Invalid argument
1531 To compile this code as a module, choose M here: the module will
1532 be called netdev-notifier-error-inject.
1536 config FUNCTION_ERROR_INJECTION
1538 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
1540 config FAULT_INJECTION
1541 bool "Fault-injection framework"
1542 depends on DEBUG_KERNEL
1544 Provide fault-injection framework.
1545 For more details, see Documentation/fault-injection/.
1548 bool "Fault-injection capability for kmalloc"
1549 depends on FAULT_INJECTION
1550 depends on SLAB || SLUB
1552 Provide fault-injection capability for kmalloc.
1554 config FAIL_PAGE_ALLOC
1555 bool "Fault-injection capabilitiy for alloc_pages()"
1556 depends on FAULT_INJECTION
1558 Provide fault-injection capability for alloc_pages().
1560 config FAIL_MAKE_REQUEST
1561 bool "Fault-injection capability for disk IO"
1562 depends on FAULT_INJECTION && BLOCK
1564 Provide fault-injection capability for disk IO.
1566 config FAIL_IO_TIMEOUT
1567 bool "Fault-injection capability for faking disk interrupts"
1568 depends on FAULT_INJECTION && BLOCK
1570 Provide fault-injection capability on end IO handling. This
1571 will make the block layer "forget" an interrupt as configured,
1572 thus exercising the error handling.
1574 Only works with drivers that use the generic timeout handling,
1575 for others it wont do anything.
1578 bool "Fault-injection capability for futexes"
1580 depends on FAULT_INJECTION && FUTEX
1582 Provide fault-injection capability for futexes.
1584 config FAULT_INJECTION_DEBUG_FS
1585 bool "Debugfs entries for fault-injection capabilities"
1586 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1588 Enable configuration of fault-injection capabilities via debugfs.
1590 config FAIL_FUNCTION
1591 bool "Fault-injection capability for functions"
1592 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
1594 Provide function-based fault-injection capability.
1595 This will allow you to override a specific function with a return
1596 with given return value. As a result, function caller will see
1597 an error value and have to handle it. This is useful to test the
1598 error handling in various subsystems.
1600 config FAIL_MMC_REQUEST
1601 bool "Fault-injection capability for MMC IO"
1602 depends on FAULT_INJECTION_DEBUG_FS && MMC
1604 Provide fault-injection capability for MMC IO.
1605 This will make the mmc core return data errors. This is
1606 useful to test the error handling in the mmc block device
1607 and to test how the mmc host driver handles retries from
1610 config FAULT_INJECTION_STACKTRACE_FILTER
1611 bool "stacktrace filter for fault-injection capabilities"
1612 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1615 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86
1617 Provide stacktrace filter for fault-injection capabilities
1620 bool "Latency measuring infrastructure"
1621 depends on DEBUG_KERNEL
1622 depends on STACKTRACE_SUPPORT
1624 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86
1631 Enable this option if you want to use the LatencyTOP tool
1632 to find out which userspace is blocking on what kernel operations.
1634 source "kernel/trace/Kconfig"
1636 config PROVIDE_OHCI1394_DMA_INIT
1637 bool "Remote debugging over FireWire early on boot"
1638 depends on PCI && X86
1640 If you want to debug problems which hang or crash the kernel early
1641 on boot and the crashing machine has a FireWire port, you can use
1642 this feature to remotely access the memory of the crashed machine
1643 over FireWire. This employs remote DMA as part of the OHCI1394
1644 specification which is now the standard for FireWire controllers.
1646 With remote DMA, you can monitor the printk buffer remotely using
1647 firescope and access all memory below 4GB using fireproxy from gdb.
1648 Even controlling a kernel debugger is possible using remote DMA.
1652 If ohci1394_dma=early is used as boot parameter, it will initialize
1653 all OHCI1394 controllers which are found in the PCI config space.
1655 As all changes to the FireWire bus such as enabling and disabling
1656 devices cause a bus reset and thereby disable remote DMA for all
1657 devices, be sure to have the cable plugged and FireWire enabled on
1658 the debugging host before booting the debug target for debugging.
1660 This code (~1k) is freed after boot. By then, the firewire stack
1661 in charge of the OHCI-1394 controllers should be used instead.
1663 See Documentation/debugging-via-ohci1394.txt for more information.
1665 source "lib/kunit/Kconfig"
1667 menuconfig RUNTIME_TESTING_MENU
1668 bool "Runtime Testing"
1671 if RUNTIME_TESTING_MENU
1674 tristate "Linux Kernel Dump Test Tool Module"
1677 This module enables testing of the different dumping mechanisms by
1678 inducing system failures at predefined crash points.
1679 If you don't need it: say N
1680 Choose M here to compile this code as a module. The module will be
1683 Documentation on how to use the module can be found in
1684 Documentation/fault-injection/provoke-crashes.rst
1686 config TEST_LIST_SORT
1687 tristate "Linked list sorting test"
1688 depends on DEBUG_KERNEL || m
1690 Enable this to turn on 'list_sort()' function test. This test is
1691 executed only once during system boot (so affects only boot time),
1692 or at module load time.
1697 tristate "Array-based sort test"
1698 depends on DEBUG_KERNEL || m
1700 This option enables the self-test function of 'sort()' at boot,
1701 or at module load time.
1705 config KPROBES_SANITY_TEST
1706 bool "Kprobes sanity tests"
1707 depends on DEBUG_KERNEL
1710 This option provides for testing basic kprobes functionality on
1711 boot. Samples of kprobe and kretprobe are inserted and
1712 verified for functionality.
1714 Say N if you are unsure.
1716 config BACKTRACE_SELF_TEST
1717 tristate "Self test for the backtrace code"
1718 depends on DEBUG_KERNEL
1720 This option provides a kernel module that can be used to test
1721 the kernel stack backtrace code. This option is not useful
1722 for distributions or general kernels, but only for kernel
1723 developers working on architecture code.
1725 Note that if you want to also test saved backtraces, you will
1726 have to enable STACKTRACE as well.
1728 Say N if you are unsure.
1731 tristate "Red-Black tree test"
1732 depends on DEBUG_KERNEL
1734 A benchmark measuring the performance of the rbtree library.
1735 Also includes rbtree invariant checks.
1737 config REED_SOLOMON_TEST
1738 tristate "Reed-Solomon library test"
1739 depends on DEBUG_KERNEL || m
1741 select REED_SOLOMON_ENC16
1742 select REED_SOLOMON_DEC16
1744 This option enables the self-test function of rslib at boot,
1745 or at module load time.
1749 config INTERVAL_TREE_TEST
1750 tristate "Interval tree test"
1751 depends on DEBUG_KERNEL
1752 select INTERVAL_TREE
1754 A benchmark measuring the performance of the interval tree library
1757 tristate "Per cpu operations test"
1758 depends on m && DEBUG_KERNEL
1760 Enable this option to build test module which validates per-cpu
1765 config ATOMIC64_SELFTEST
1766 tristate "Perform an atomic64_t self-test"
1768 Enable this option to test the atomic64_t functions at boot or
1769 at module load time.
1773 config ASYNC_RAID6_TEST
1774 tristate "Self test for hardware accelerated raid6 recovery"
1775 depends on ASYNC_RAID6_RECOV
1778 This is a one-shot self test that permutes through the
1779 recovery of all the possible two disk failure scenarios for a
1780 N-disk array. Recovery is performed with the asynchronous
1781 raid6 recovery routines, and will optionally use an offload
1782 engine if one is available.
1787 tristate "Test functions located in the hexdump module at runtime"
1789 config TEST_STRING_HELPERS
1790 tristate "Test functions located in the string_helpers module at runtime"
1793 tristate "Test strscpy*() family of functions at runtime"
1796 tristate "Test kstrto*() family of functions at runtime"
1799 tristate "Test printf() family of functions at runtime"
1802 tristate "Test bitmap_*() family of functions at runtime"
1804 Enable this option to test the bitmap functions at boot.
1808 config TEST_BITFIELD
1809 tristate "Test bitfield functions at runtime"
1811 Enable this option to test the bitfield functions at boot.
1816 tristate "Test functions located in the uuid module at runtime"
1819 tristate "Test the XArray code at runtime"
1821 config TEST_OVERFLOW
1822 tristate "Test check_*_overflow() functions at runtime"
1824 config TEST_RHASHTABLE
1825 tristate "Perform selftest on resizable hash table"
1827 Enable this option to test the rhashtable functions at boot.
1832 tristate "Perform selftest on hash functions"
1834 Enable this option to test the kernel's integer (<linux/hash.h>),
1835 string (<linux/stringhash.h>), and siphash (<linux/siphash.h>)
1836 hash functions on boot (or module load).
1838 This is intended to help people writing architecture-specific
1839 optimized versions. If unsure, say N.
1842 tristate "Perform selftest on IDA functions"
1845 tristate "Perform selftest on priority array manager"
1848 Enable this option to test priority array manager on boot
1853 config TEST_IRQ_TIMINGS
1854 bool "IRQ timings selftest"
1855 depends on IRQ_TIMINGS
1857 Enable this option to test the irq timings code on boot.
1862 tristate "Test module loading with 'hello world' module"
1865 This builds the "test_module" module that emits "Hello, world"
1866 on printk when loaded. It is designed to be used for basic
1867 evaluation of the module loading subsystem (for example when
1868 validating module verification). It lacks any extra dependencies,
1869 and will not normally be loaded by the system unless explicitly
1875 tristate "Test module for stress/performance analysis of vmalloc allocator"
1880 This builds the "test_vmalloc" module that should be used for
1881 stress and performance analysis. So, any new change for vmalloc
1882 subsystem can be evaluated from performance and stability point
1887 config TEST_USER_COPY
1888 tristate "Test user/kernel boundary protections"
1891 This builds the "test_user_copy" module that runs sanity checks
1892 on the copy_to/from_user infrastructure, making sure basic
1893 user/kernel boundary testing is working. If it fails to load,
1894 a regression has been detected in the user/kernel memory boundary
1900 tristate "Test BPF filter functionality"
1903 This builds the "test_bpf" module that runs various test vectors
1904 against the BPF interpreter or BPF JIT compiler depending on the
1905 current setting. This is in particular useful for BPF JIT compiler
1906 development, but also to run regression tests against changes in
1907 the interpreter code. It also enables test stubs for eBPF maps and
1908 verifier used by user space verifier testsuite.
1912 config TEST_BLACKHOLE_DEV
1913 tristate "Test blackhole netdev functionality"
1916 This builds the "test_blackhole_dev" module that validates the
1917 data path through this blackhole netdev.
1921 config FIND_BIT_BENCHMARK
1922 tristate "Test find_bit functions"
1924 This builds the "test_find_bit" module that measure find_*_bit()
1925 functions performance.
1929 config TEST_FIRMWARE
1930 tristate "Test firmware loading via userspace interface"
1931 depends on FW_LOADER
1933 This builds the "test_firmware" module that creates a userspace
1934 interface for testing firmware loading. This can be used to
1935 control the triggering of firmware loading without needing an
1936 actual firmware-using device. The contents can be rechecked by
1942 tristate "sysctl test driver"
1943 depends on PROC_SYSCTL
1945 This builds the "test_sysctl" module. This driver enables to test the
1946 proc sysctl interfaces available to drivers safely without affecting
1947 production knobs which might alter system functionality.
1951 config SYSCTL_KUNIT_TEST
1952 bool "KUnit test for sysctl"
1955 This builds the proc sysctl unit test, which runs on boot.
1956 Tests the API contract and implementation correctness of sysctl.
1957 For more information on KUnit and unit tests in general please refer
1958 to the KUnit documentation in Documentation/dev-tools/kunit/.
1962 config LIST_KUNIT_TEST
1963 bool "KUnit Test for Kernel Linked-list structures"
1966 This builds the linked list KUnit test suite.
1967 It tests that the API and basic functionality of the list_head type
1968 and associated macros.
1970 KUnit tests run during boot and output the results to the debug log
1971 in TAP format (http://testanything.org/). Only useful for kernel devs
1972 running the KUnit test harness, and not intended for inclusion into a
1975 For more information on KUnit and unit tests in general please refer
1976 to the KUnit documentation in Documentation/dev-tools/kunit/.
1981 tristate "udelay test driver"
1983 This builds the "udelay_test" module that helps to make sure
1984 that udelay() is working properly.
1988 config TEST_STATIC_KEYS
1989 tristate "Test static keys"
1992 Test the static key interfaces.
1997 tristate "kmod stress tester"
1999 depends on NETDEVICES && NET_CORE && INET # for TUN
2006 Test the kernel's module loading mechanism: kmod. kmod implements
2007 support to load modules using the Linux kernel's usermode helper.
2008 This test provides a series of tests against kmod.
2010 Although technically you can either build test_kmod as a module or
2011 into the kernel we disallow building it into the kernel since
2012 it stress tests request_module() and this will very likely cause
2013 some issues by taking over precious threads available from other
2014 module load requests, ultimately this could be fatal.
2018 tools/testing/selftests/kmod/kmod.sh --help
2022 config TEST_DEBUG_VIRTUAL
2023 tristate "Test CONFIG_DEBUG_VIRTUAL feature"
2024 depends on DEBUG_VIRTUAL
2026 Test the kernel's ability to detect incorrect calls to
2027 virt_to_phys() done against the non-linear part of the
2028 kernel's virtual address map.
2032 config TEST_MEMCAT_P
2033 tristate "Test memcat_p() helper function"
2035 Test the memcat_p() helper for correctly merging two
2036 pointer arrays together.
2040 config TEST_LIVEPATCH
2041 tristate "Test livepatching"
2043 depends on DYNAMIC_DEBUG
2044 depends on LIVEPATCH
2047 Test kernel livepatching features for correctness. The tests will
2048 load test modules that will be livepatched in various scenarios.
2050 To run all the livepatching tests:
2052 make -C tools/testing/selftests TARGETS=livepatch run_tests
2054 Alternatively, individual tests may be invoked:
2056 tools/testing/selftests/livepatch/test-callbacks.sh
2057 tools/testing/selftests/livepatch/test-livepatch.sh
2058 tools/testing/selftests/livepatch/test-shadow-vars.sh
2063 tristate "Perform selftest on object aggreration manager"
2067 Enable this option to test object aggregation manager on boot
2071 config TEST_STACKINIT
2072 tristate "Test level of stack variable initialization"
2074 Test if the kernel is zero-initializing stack variables and
2075 padding. Coverage is controlled by compiler flags,
2076 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2077 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2082 tristate "Test heap/page initialization"
2084 Test if the kernel is zero-initializing heap and page allocations.
2085 This can be useful to test init_on_alloc and init_on_free features.
2089 endif # RUNTIME_TESTING_MENU
2094 This option adds a kernel parameter 'memtest', which allows memtest
2096 memtest=0, mean disabled; -- default
2097 memtest=1, mean do 1 test pattern;
2099 memtest=17, mean do 17 test patterns.
2100 If you are unsure how to answer this question, answer N.
2102 config BUG_ON_DATA_CORRUPTION
2103 bool "Trigger a BUG when data corruption is detected"
2106 Select this option if the kernel should BUG when it encounters
2107 data corruption in kernel memory structures when they get checked
2112 source "samples/Kconfig"
2114 source "lib/Kconfig.kgdb"
2116 source "lib/Kconfig.ubsan"
2118 config ARCH_HAS_DEVMEM_IS_ALLOWED
2121 config STRICT_DEVMEM
2122 bool "Filter access to /dev/mem"
2123 depends on MMU && DEVMEM
2124 depends on ARCH_HAS_DEVMEM_IS_ALLOWED
2125 default y if PPC || X86 || ARM64
2127 If this option is disabled, you allow userspace (root) access to all
2128 of memory, including kernel and userspace memory. Accidental
2129 access to this is obviously disastrous, but specific access can
2130 be used by people debugging the kernel. Note that with PAT support
2131 enabled, even in this case there are restrictions on /dev/mem
2132 use due to the cache aliasing requirements.
2134 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
2135 file only allows userspace access to PCI space and the BIOS code and
2136 data regions. This is sufficient for dosemu and X and all common
2141 config IO_STRICT_DEVMEM
2142 bool "Filter I/O access to /dev/mem"
2143 depends on STRICT_DEVMEM
2145 If this option is disabled, you allow userspace (root) access to all
2146 io-memory regardless of whether a driver is actively using that
2147 range. Accidental access to this is obviously disastrous, but
2148 specific access can be used by people debugging kernel drivers.
2150 If this option is switched on, the /dev/mem file only allows
2151 userspace access to *idle* io-memory ranges (see /proc/iomem) This
2152 may break traditional users of /dev/mem (dosemu, legacy X, etc...)
2153 if the driver using a given range cannot be disabled.
2157 source "arch/$(SRCARCH)/Kconfig.debug"
2159 config HYPERV_TESTING
2160 bool "Microsoft Hyper-V driver testing"
2162 depends on HYPERV && DEBUG_FS
2164 Select this option to enable Hyper-V vmbus testing.
2166 endmenu # Kernel hacking
projects / linux-2.6-microblaze.git / blob