1 # SPDX-License-Identifier: GPL-2.0-only
4 menu "printk and dmesg options"
7 bool "Show timing information on printks"
10 Selecting this option causes time stamps of the printk()
11 messages to be added to the output of the syslog() system
12 call and at the console.
14 The timestamp is always recorded internally, and exported
15 to /dev/kmsg. This flag just specifies if the timestamp should
16 be included, not that the timestamp is recorded.
18 The behavior is also controlled by the kernel command line
19 parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst
22 bool "Show caller information on printks"
25 Selecting this option causes printk() to add a caller "thread id" (if
26 in task context) or a caller "processor id" (if not in task context)
29 This option is intended for environments where multiple threads
30 concurrently call printk() for many times, for it is difficult to
31 interpret without knowing where these lines (or sometimes individual
32 line which was divided into multiple lines due to race) came from.
34 Since toggling after boot makes the code racy, currently there is
35 no option to enable/disable at the kernel command line parameter or
38 config CONSOLE_LOGLEVEL_DEFAULT
39 int "Default console loglevel (1-15)"
43 Default loglevel to determine what will be printed on the console.
45 Setting a default here is equivalent to passing in loglevel=<x> in
46 the kernel bootargs. loglevel=<x> continues to override whatever
47 value is specified here as well.
49 Note: This does not affect the log level of un-prefixed printk()
50 usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT
53 config CONSOLE_LOGLEVEL_QUIET
54 int "quiet console loglevel (1-15)"
58 loglevel to use when "quiet" is passed on the kernel commandline.
60 When "quiet" is passed on the kernel commandline this loglevel
61 will be used as the loglevel. IOW passing "quiet" will be the
62 equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>"
64 config MESSAGE_LOGLEVEL_DEFAULT
65 int "Default message log level (1-7)"
69 Default log level for printk statements with no specified priority.
71 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
72 that are auditing their logs closely may want to set it to a lower
75 Note: This does not affect what message level gets printed on the console
76 by default. To change that, use loglevel=<x> in the kernel bootargs,
77 or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value.
79 config BOOT_PRINTK_DELAY
80 bool "Delay each boot printk message by N milliseconds"
81 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
83 This build option allows you to read kernel boot messages
84 by inserting a short delay after each one. The delay is
85 specified in milliseconds on the kernel command line,
88 It is likely that you would also need to use "lpj=M" to preset
89 the "loops per jiffie" value.
90 See a previous boot log for the "lpj" value to use for your
91 system, and then set "lpj=M" before setting "boot_delay=N".
92 NOTE: Using this option may adversely affect SMP systems.
93 I.e., processors other than the first one may not boot up.
94 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
95 what it believes to be lockup conditions.
98 bool "Enable dynamic printk() support"
104 Compiles debug level messages into the kernel, which would not
105 otherwise be available at runtime. These messages can then be
106 enabled/disabled based on various levels of scope - per source file,
107 function, module, format string, and line number. This mechanism
108 implicitly compiles in all pr_debug() and dev_dbg() calls, which
109 enlarges the kernel text size by about 2%.
111 If a source file is compiled with DEBUG flag set, any
112 pr_debug() calls in it are enabled by default, but can be
113 disabled at runtime as below. Note that DEBUG flag is
114 turned on by many CONFIG_*DEBUG* options.
118 Dynamic debugging is controlled via the 'dynamic_debug/control' file,
119 which is contained in the 'debugfs' filesystem. Thus, the debugfs
120 filesystem must first be mounted before making use of this feature.
121 We refer the control file as: <debugfs>/dynamic_debug/control. This
122 file contains a list of the debug statements that can be enabled. The
123 format for each line of the file is:
125 filename:lineno [module]function flags format
127 filename : source file of the debug statement
128 lineno : line number of the debug statement
129 module : module that contains the debug statement
130 function : function that contains the debug statement
131 flags : '=p' means the line is turned 'on' for printing
132 format : the format used for the debug statement
136 nullarbor:~ # cat <debugfs>/dynamic_debug/control
137 # filename:lineno [module]function flags format
138 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
139 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
140 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
144 // enable the message at line 1603 of file svcsock.c
145 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
146 <debugfs>/dynamic_debug/control
148 // enable all the messages in file svcsock.c
149 nullarbor:~ # echo -n 'file svcsock.c +p' >
150 <debugfs>/dynamic_debug/control
152 // enable all the messages in the NFS server module
153 nullarbor:~ # echo -n 'module nfsd +p' >
154 <debugfs>/dynamic_debug/control
156 // enable all 12 messages in the function svc_process()
157 nullarbor:~ # echo -n 'func svc_process +p' >
158 <debugfs>/dynamic_debug/control
160 // disable all 12 messages in the function svc_process()
161 nullarbor:~ # echo -n 'func svc_process -p' >
162 <debugfs>/dynamic_debug/control
164 See Documentation/admin-guide/dynamic-debug-howto.rst for additional
167 endmenu # "printk and dmesg options"
169 menu "Compile-time checks and compiler options"
172 bool "Compile the kernel with debug info"
173 depends on DEBUG_KERNEL && !COMPILE_TEST
175 If you say Y here the resulting kernel image will include
176 debugging info resulting in a larger kernel image.
177 This adds debug symbols to the kernel and modules (gcc -g), and
178 is needed if you intend to use kernel crashdump or binary object
179 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
180 Say Y here only if you plan to debug the kernel.
184 config DEBUG_INFO_REDUCED
185 bool "Reduce debugging information"
186 depends on DEBUG_INFO
188 If you say Y here gcc is instructed to generate less debugging
189 information for structure types. This means that tools that
190 need full debugging information (like kgdb or systemtap) won't
191 be happy. But if you merely need debugging information to
192 resolve line numbers there is no loss. Advantage is that
193 build directory object sizes shrink dramatically over a full
194 DEBUG_INFO build and compile times are reduced too.
195 Only works with newer gcc versions.
197 config DEBUG_INFO_SPLIT
198 bool "Produce split debuginfo in .dwo files"
199 depends on DEBUG_INFO
200 depends on $(cc-option,-gsplit-dwarf)
202 Generate debug info into separate .dwo files. This significantly
203 reduces the build directory size for builds with DEBUG_INFO,
204 because it stores the information only once on disk in .dwo
205 files instead of multiple times in object files and executables.
206 In addition the debug information is also compressed.
208 Requires recent gcc (4.7+) and recent gdb/binutils.
209 Any tool that packages or reads debug information would need
210 to know about the .dwo files and include them.
211 Incompatible with older versions of ccache.
213 config DEBUG_INFO_DWARF4
214 bool "Generate dwarf4 debuginfo"
215 depends on DEBUG_INFO
216 depends on $(cc-option,-gdwarf-4)
218 Generate dwarf4 debug info. This requires recent versions
219 of gcc and gdb. It makes the debug information larger.
220 But it significantly improves the success of resolving
221 variables in gdb on optimized code.
223 config DEBUG_INFO_BTF
224 bool "Generate BTF typeinfo"
225 depends on DEBUG_INFO
227 Generate deduplicated BTF type information from DWARF debug info.
228 Turning this on expects presence of pahole tool, which will convert
229 DWARF type info into equivalent deduplicated BTF type info.
232 bool "Provide GDB scripts for kernel debugging"
233 depends on DEBUG_INFO
235 This creates the required links to GDB helper scripts in the
236 build directory. If you load vmlinux into gdb, the helper
237 scripts will be automatically imported by gdb as well, and
238 additional functions are available to analyze a Linux kernel
239 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
242 config ENABLE_MUST_CHECK
243 bool "Enable __must_check logic"
246 Enable the __must_check logic in the kernel build. Disable this to
247 suppress the "warning: ignoring return value of 'foo', declared with
248 attribute warn_unused_result" messages.
251 int "Warn for stack frames larger than (needs gcc 4.4)"
253 default 2048 if GCC_PLUGIN_LATENT_ENTROPY
254 default 1280 if (!64BIT && PARISC)
255 default 1024 if (!64BIT && !PARISC)
256 default 2048 if 64BIT
258 Tell gcc to warn at build time for stack frames larger than this.
259 Setting this too low will cause a lot of warnings.
260 Setting it to 0 disables the warning.
263 config STRIP_ASM_SYMS
264 bool "Strip assembler-generated symbols during link"
267 Strip internal assembler-generated symbols during a link (symbols
268 that look like '.Lxxx') so they don't pollute the output of
269 get_wchan() and suchlike.
272 bool "Generate readable assembler code"
273 depends on DEBUG_KERNEL
275 Disable some compiler optimizations that tend to generate human unreadable
276 assembler output. This may make the kernel slightly slower, but it helps
277 to keep kernel developers who have to stare a lot at assembler listings
281 bool "Debug Filesystem"
283 debugfs is a virtual file system that kernel developers use to put
284 debugging files into. Enable this option to be able to read and
285 write to these files.
287 For detailed documentation on the debugfs API, see
288 Documentation/filesystems/.
292 config HEADERS_INSTALL
293 bool "Install uapi headers to usr/include"
296 This option will install uapi headers (headers exported to user-space)
297 into the usr/include directory for use during the kernel build.
298 This is unneeded for building the kernel itself, but needed for some
299 user-space program samples. It is also needed by some features such
300 as uapi header sanity checks.
303 bool "Run sanity checks on uapi headers when building 'all'"
304 depends on HEADERS_INSTALL
306 This option will run basic sanity checks on uapi headers when
307 building the 'all' target, for example, ensure that they do not
308 attempt to include files which were not exported, etc.
310 If you're making modifications to header files which are
311 relevant for userspace, say 'Y'.
313 config OPTIMIZE_INLINING
314 bool "Allow compiler to uninline functions marked 'inline'"
316 This option determines if the kernel forces gcc to inline the functions
317 developers have marked 'inline'. Doing so takes away freedom from gcc to
318 do what it thinks is best, which is desirable for the gcc 3.x series of
319 compilers. The gcc 4.x series have a rewritten inlining algorithm and
320 enabling this option will generate a smaller kernel there. Hopefully
321 this algorithm is so good that allowing gcc 4.x and above to make the
322 decision will become the default in the future. Until then this option
323 is there to test gcc for this.
327 config DEBUG_SECTION_MISMATCH
328 bool "Enable full Section mismatch analysis"
330 The section mismatch analysis checks if there are illegal
331 references from one section to another section.
332 During linktime or runtime, some sections are dropped;
333 any use of code/data previously in these sections would
334 most likely result in an oops.
335 In the code, functions and variables are annotated with
336 __init,, etc. (see the full list in include/linux/init.h),
337 which results in the code/data being placed in specific sections.
338 The section mismatch analysis is always performed after a full
339 kernel build, and enabling this option causes the following
340 additional step to occur:
341 - Add the option -fno-inline-functions-called-once to gcc commands.
342 When inlining a function annotated with __init in a non-init
343 function, we would lose the section information and thus
344 the analysis would not catch the illegal reference.
345 This option tells gcc to inline less (but it does result in
348 config SECTION_MISMATCH_WARN_ONLY
349 bool "Make section mismatch errors non-fatal"
352 If you say N here, the build process will fail if there are any
353 section mismatch, instead of just throwing warnings.
358 # Select this config option from the architecture Kconfig, if it
359 # is preferred to always offer frame pointers as a config
360 # option on the architecture (regardless of KERNEL_DEBUG):
362 config ARCH_WANT_FRAME_POINTERS
366 bool "Compile the kernel with frame pointers"
367 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
368 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
370 If you say Y here the resulting kernel image will be slightly
371 larger and slower, but it gives very useful debugging information
372 in case of kernel bugs. (precise oopses/stacktraces/warnings)
374 config STACK_VALIDATION
375 bool "Compile-time stack metadata validation"
376 depends on HAVE_STACK_VALIDATION
379 Add compile-time checks to validate stack metadata, including frame
380 pointers (if CONFIG_FRAME_POINTER is enabled). This helps ensure
381 that runtime stack traces are more reliable.
383 This is also a prerequisite for generation of ORC unwind data, which
384 is needed for CONFIG_UNWINDER_ORC.
386 For more information, see
387 tools/objtool/Documentation/stack-validation.txt.
389 config DEBUG_FORCE_WEAK_PER_CPU
390 bool "Force weak per-cpu definitions"
391 depends on DEBUG_KERNEL
393 s390 and alpha require percpu variables in modules to be
394 defined weak to work around addressing range issue which
395 puts the following two restrictions on percpu variable
398 1. percpu symbols must be unique whether static or not
399 2. percpu variables can't be defined inside a function
401 To ensure that generic code follows the above rules, this
402 option forces all percpu variables to be defined as weak.
404 endmenu # "Compiler options"
407 bool "Magic SysRq key"
410 If you say Y here, you will have some control over the system even
411 if the system crashes for example during kernel debugging (e.g., you
412 will be able to flush the buffer cache to disk, reboot the system
413 immediately or dump some status information). This is accomplished
414 by pressing various keys while holding SysRq (Alt+PrintScreen). It
415 also works on a serial console (on PC hardware at least), if you
416 send a BREAK and then within 5 seconds a command keypress. The
417 keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
418 Don't say Y unless you really know what this hack does.
420 config MAGIC_SYSRQ_DEFAULT_ENABLE
421 hex "Enable magic SysRq key functions by default"
422 depends on MAGIC_SYSRQ
425 Specifies which SysRq key functions are enabled by default.
426 This may be set to 1 or 0 to enable or disable them all, or
427 to a bitmask as described in Documentation/admin-guide/sysrq.rst.
429 config MAGIC_SYSRQ_SERIAL
430 bool "Enable magic SysRq key over serial"
431 depends on MAGIC_SYSRQ
434 Many embedded boards have a disconnected TTL level serial which can
435 generate some garbage that can lead to spurious false sysrq detects.
436 This option allows you to decide whether you want to enable the
440 bool "Kernel debugging"
442 Say Y here if you are developing drivers or trying to debug and
443 identify kernel problems.
446 bool "Miscellaneous debug code"
448 depends on DEBUG_KERNEL
450 Say Y here if you need to enable miscellaneous debug code that should
451 be under a more specific debug option but isn't.
454 menu "Memory Debugging"
456 source "mm/Kconfig.debug"
459 bool "Debug object operations"
460 depends on DEBUG_KERNEL
462 If you say Y here, additional code will be inserted into the
463 kernel to track the life time of various objects and validate
464 the operations on those objects.
466 config DEBUG_OBJECTS_SELFTEST
467 bool "Debug objects selftest"
468 depends on DEBUG_OBJECTS
470 This enables the selftest of the object debug code.
472 config DEBUG_OBJECTS_FREE
473 bool "Debug objects in freed memory"
474 depends on DEBUG_OBJECTS
476 This enables checks whether a k/v free operation frees an area
477 which contains an object which has not been deactivated
478 properly. This can make kmalloc/kfree-intensive workloads
481 config DEBUG_OBJECTS_TIMERS
482 bool "Debug timer objects"
483 depends on DEBUG_OBJECTS
485 If you say Y here, additional code will be inserted into the
486 timer routines to track the life time of timer objects and
487 validate the timer operations.
489 config DEBUG_OBJECTS_WORK
490 bool "Debug work objects"
491 depends on DEBUG_OBJECTS
493 If you say Y here, additional code will be inserted into the
494 work queue routines to track the life time of work objects and
495 validate the work operations.
497 config DEBUG_OBJECTS_RCU_HEAD
498 bool "Debug RCU callbacks objects"
499 depends on DEBUG_OBJECTS
501 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
503 config DEBUG_OBJECTS_PERCPU_COUNTER
504 bool "Debug percpu counter objects"
505 depends on DEBUG_OBJECTS
507 If you say Y here, additional code will be inserted into the
508 percpu counter routines to track the life time of percpu counter
509 objects and validate the percpu counter operations.
511 config DEBUG_OBJECTS_ENABLE_DEFAULT
512 int "debug_objects bootup default value (0-1)"
515 depends on DEBUG_OBJECTS
517 Debug objects boot parameter default value
520 bool "Debug slab memory allocations"
521 depends on DEBUG_KERNEL && SLAB
523 Say Y here to have the kernel do limited verification on memory
524 allocation as well as poisoning memory on free to catch use of freed
525 memory. This can make kmalloc/kfree-intensive workloads much slower.
528 bool "SLUB debugging on by default"
529 depends on SLUB && SLUB_DEBUG
532 Boot with debugging on by default. SLUB boots by default with
533 the runtime debug capabilities switched off. Enabling this is
534 equivalent to specifying the "slub_debug" parameter on boot.
535 There is no support for more fine grained debug control like
536 possible with slub_debug=xxx. SLUB debugging may be switched
537 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
542 bool "Enable SLUB performance statistics"
543 depends on SLUB && SYSFS
545 SLUB statistics are useful to debug SLUBs allocation behavior in
546 order find ways to optimize the allocator. This should never be
547 enabled for production use since keeping statistics slows down
548 the allocator by a few percentage points. The slabinfo command
549 supports the determination of the most active slabs to figure
550 out which slabs are relevant to a particular load.
551 Try running: slabinfo -DA
553 config HAVE_DEBUG_KMEMLEAK
556 config DEBUG_KMEMLEAK
557 bool "Kernel memory leak detector"
558 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
560 select STACKTRACE if STACKTRACE_SUPPORT
564 Say Y here if you want to enable the memory leak
565 detector. The memory allocation/freeing is traced in a way
566 similar to the Boehm's conservative garbage collector, the
567 difference being that the orphan objects are not freed but
568 only shown in /sys/kernel/debug/kmemleak. Enabling this
569 feature will introduce an overhead to memory
570 allocations. See Documentation/dev-tools/kmemleak.rst for more
573 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
574 of finding leaks due to the slab objects poisoning.
576 In order to access the kmemleak file, debugfs needs to be
577 mounted (usually at /sys/kernel/debug).
579 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
580 int "Maximum kmemleak early log entries"
581 depends on DEBUG_KMEMLEAK
585 Kmemleak must track all the memory allocations to avoid
586 reporting false positives. Since memory may be allocated or
587 freed before kmemleak is initialised, an early log buffer is
588 used to store these actions. If kmemleak reports "early log
589 buffer exceeded", please increase this value.
591 config DEBUG_KMEMLEAK_TEST
592 tristate "Simple test for the kernel memory leak detector"
593 depends on DEBUG_KMEMLEAK && m
595 This option enables a module that explicitly leaks memory.
599 config DEBUG_KMEMLEAK_DEFAULT_OFF
600 bool "Default kmemleak to off"
601 depends on DEBUG_KMEMLEAK
603 Say Y here to disable kmemleak by default. It can then be enabled
604 on the command line via kmemleak=on.
606 config DEBUG_KMEMLEAK_AUTO_SCAN
607 bool "Enable kmemleak auto scan thread on boot up"
609 depends on DEBUG_KMEMLEAK
611 Depending on the cpu, kmemleak scan may be cpu intensive and can
612 stall user tasks at times. This option enables/disables automatic
613 kmemleak scan at boot up.
615 Say N here to disable kmemleak auto scan thread to stop automatic
616 scanning. Disabling this option disables automatic reporting of
621 config DEBUG_STACK_USAGE
622 bool "Stack utilization instrumentation"
623 depends on DEBUG_KERNEL && !IA64
625 Enables the display of the minimum amount of free stack which each
626 task has ever had available in the sysrq-T and sysrq-P debug output.
628 This option will slow down process creation somewhat.
632 depends on DEBUG_KERNEL
634 Enable this to turn on extended checks in the virtual-memory system
635 that may impact performance.
639 config DEBUG_VM_VMACACHE
640 bool "Debug VMA caching"
643 Enable this to turn on VMA caching debug information. Doing so
644 can cause significant overhead, so only enable it in non-production
650 bool "Debug VM red-black trees"
653 Enable VM red-black tree debugging information and extra validations.
657 config DEBUG_VM_PGFLAGS
658 bool "Debug page-flags operations"
661 Enables extra validation on page flags operations.
665 config ARCH_HAS_DEBUG_VIRTUAL
669 bool "Debug VM translations"
670 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
672 Enable some costly sanity checks in virtual to page code. This can
673 catch mistakes with virt_to_page() and friends.
677 config DEBUG_NOMMU_REGIONS
678 bool "Debug the global anon/private NOMMU mapping region tree"
679 depends on DEBUG_KERNEL && !MMU
681 This option causes the global tree of anonymous and private mapping
682 regions to be regularly checked for invalid topology.
684 config DEBUG_MEMORY_INIT
685 bool "Debug memory initialisation" if EXPERT
688 Enable this for additional checks during memory initialisation.
689 The sanity checks verify aspects of the VM such as the memory model
690 and other information provided by the architecture. Verbose
691 information will be printed at KERN_DEBUG loglevel depending
692 on the mminit_loglevel= command-line option.
696 config MEMORY_NOTIFIER_ERROR_INJECT
697 tristate "Memory hotplug notifier error injection module"
698 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
700 This option provides the ability to inject artificial errors to
701 memory hotplug notifier chain callbacks. It is controlled through
702 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
704 If the notifier call chain should be failed with some events
705 notified, write the error code to "actions/<notifier event>/error".
707 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
709 # cd /sys/kernel/debug/notifier-error-inject/memory
710 # echo -12 > actions/MEM_GOING_OFFLINE/error
711 # echo offline > /sys/devices/system/memory/memoryXXX/state
712 bash: echo: write error: Cannot allocate memory
714 To compile this code as a module, choose M here: the module will
715 be called memory-notifier-error-inject.
719 config DEBUG_PER_CPU_MAPS
720 bool "Debug access to per_cpu maps"
721 depends on DEBUG_KERNEL
724 Say Y to verify that the per_cpu map being accessed has
725 been set up. This adds a fair amount of code to kernel memory
726 and decreases performance.
731 bool "Highmem debugging"
732 depends on DEBUG_KERNEL && HIGHMEM
734 This option enables additional error checking for high memory
735 systems. Disable for production systems.
737 config HAVE_DEBUG_STACKOVERFLOW
740 config DEBUG_STACKOVERFLOW
741 bool "Check for stack overflows"
742 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
744 Say Y here if you want to check for overflows of kernel, IRQ
745 and exception stacks (if your architecture uses them). This
746 option will show detailed messages if free stack space drops
747 below a certain limit.
749 These kinds of bugs usually occur when call-chains in the
750 kernel get too deep, especially when interrupts are
753 Use this in cases where you see apparently random memory
754 corruption, especially if it appears in 'struct thread_info'
756 If in doubt, say "N".
758 source "lib/Kconfig.kasan"
760 endmenu # "Memory Debugging"
765 An architecture should select this when it can successfully
766 build and run with CONFIG_KCOV. This typically requires
767 disabling instrumentation for some early boot code.
769 config CC_HAS_SANCOV_TRACE_PC
770 def_bool $(cc-option,-fsanitize-coverage=trace-pc)
773 bool "Code coverage for fuzzing"
774 depends on ARCH_HAS_KCOV
775 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
777 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
779 KCOV exposes kernel code coverage information in a form suitable
780 for coverage-guided fuzzing (randomized testing).
782 If RANDOMIZE_BASE is enabled, PC values will not be stable across
783 different machines and across reboots. If you need stable PC values,
784 disable RANDOMIZE_BASE.
786 For more details, see Documentation/dev-tools/kcov.rst.
788 config KCOV_ENABLE_COMPARISONS
789 bool "Enable comparison operands collection by KCOV"
791 depends on $(cc-option,-fsanitize-coverage=trace-cmp)
793 KCOV also exposes operands of every comparison in the instrumented
794 code along with operand sizes and PCs of the comparison instructions.
795 These operands can be used by fuzzing engines to improve the quality
798 config KCOV_INSTRUMENT_ALL
799 bool "Instrument all code by default"
803 If you are doing generic system call fuzzing (like e.g. syzkaller),
804 then you will want to instrument the whole kernel and you should
805 say y here. If you are doing more targeted fuzzing (like e.g.
806 filesystem fuzzing with AFL) then you will want to enable coverage
807 for more specific subsets of files, and should say n here.
810 bool "Debug shared IRQ handlers"
811 depends on DEBUG_KERNEL
813 Enable this to generate a spurious interrupt as soon as a shared
814 interrupt handler is registered, and just before one is deregistered.
815 Drivers ought to be able to handle interrupts coming in at those
816 points; some don't and need to be caught.
818 menu "Debug Lockups and Hangs"
820 config LOCKUP_DETECTOR
823 config SOFTLOCKUP_DETECTOR
824 bool "Detect Soft Lockups"
825 depends on DEBUG_KERNEL && !S390
826 select LOCKUP_DETECTOR
828 Say Y here to enable the kernel to act as a watchdog to detect
831 Softlockups are bugs that cause the kernel to loop in kernel
832 mode for more than 20 seconds, without giving other tasks a
833 chance to run. The current stack trace is displayed upon
834 detection and the system will stay locked up.
836 config BOOTPARAM_SOFTLOCKUP_PANIC
837 bool "Panic (Reboot) On Soft Lockups"
838 depends on SOFTLOCKUP_DETECTOR
840 Say Y here to enable the kernel to panic on "soft lockups",
841 which are bugs that cause the kernel to loop in kernel
842 mode for more than 20 seconds (configurable using the watchdog_thresh
843 sysctl), without giving other tasks a chance to run.
845 The panic can be used in combination with panic_timeout,
846 to cause the system to reboot automatically after a
847 lockup has been detected. This feature is useful for
848 high-availability systems that have uptime guarantees and
849 where a lockup must be resolved ASAP.
853 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
855 depends on SOFTLOCKUP_DETECTOR
857 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
858 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
860 config HARDLOCKUP_DETECTOR_PERF
862 select SOFTLOCKUP_DETECTOR
865 # Enables a timestamp based low pass filter to compensate for perf based
866 # hard lockup detection which runs too fast due to turbo modes.
868 config HARDLOCKUP_CHECK_TIMESTAMP
872 # arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard
873 # lockup detector rather than the perf based detector.
875 config HARDLOCKUP_DETECTOR
876 bool "Detect Hard Lockups"
877 depends on DEBUG_KERNEL && !S390
878 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH
879 select LOCKUP_DETECTOR
880 select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF
881 select HARDLOCKUP_DETECTOR_ARCH if HAVE_HARDLOCKUP_DETECTOR_ARCH
883 Say Y here to enable the kernel to act as a watchdog to detect
886 Hardlockups are bugs that cause the CPU to loop in kernel mode
887 for more than 10 seconds, without letting other interrupts have a
888 chance to run. The current stack trace is displayed upon detection
889 and the system will stay locked up.
891 config BOOTPARAM_HARDLOCKUP_PANIC
892 bool "Panic (Reboot) On Hard Lockups"
893 depends on HARDLOCKUP_DETECTOR
895 Say Y here to enable the kernel to panic on "hard lockups",
896 which are bugs that cause the kernel to loop in kernel
897 mode with interrupts disabled for more than 10 seconds (configurable
898 using the watchdog_thresh sysctl).
902 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
904 depends on HARDLOCKUP_DETECTOR
906 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
907 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
909 config DETECT_HUNG_TASK
910 bool "Detect Hung Tasks"
911 depends on DEBUG_KERNEL
912 default SOFTLOCKUP_DETECTOR
914 Say Y here to enable the kernel to detect "hung tasks",
915 which are bugs that cause the task to be stuck in
916 uninterruptible "D" state indefinitely.
918 When a hung task is detected, the kernel will print the
919 current stack trace (which you should report), but the
920 task will stay in uninterruptible state. If lockdep is
921 enabled then all held locks will also be reported. This
922 feature has negligible overhead.
924 config DEFAULT_HUNG_TASK_TIMEOUT
925 int "Default timeout for hung task detection (in seconds)"
926 depends on DETECT_HUNG_TASK
929 This option controls the default timeout (in seconds) used
930 to determine when a task has become non-responsive and should
933 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
934 sysctl or by writing a value to
935 /proc/sys/kernel/hung_task_timeout_secs.
937 A timeout of 0 disables the check. The default is two minutes.
938 Keeping the default should be fine in most cases.
940 config BOOTPARAM_HUNG_TASK_PANIC
941 bool "Panic (Reboot) On Hung Tasks"
942 depends on DETECT_HUNG_TASK
944 Say Y here to enable the kernel to panic on "hung tasks",
945 which are bugs that cause the kernel to leave a task stuck
946 in uninterruptible "D" state.
948 The panic can be used in combination with panic_timeout,
949 to cause the system to reboot automatically after a
950 hung task has been detected. This feature is useful for
951 high-availability systems that have uptime guarantees and
952 where a hung tasks must be resolved ASAP.
956 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
958 depends on DETECT_HUNG_TASK
960 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
961 default 1 if BOOTPARAM_HUNG_TASK_PANIC
964 bool "Detect Workqueue Stalls"
965 depends on DEBUG_KERNEL
967 Say Y here to enable stall detection on workqueues. If a
968 worker pool doesn't make forward progress on a pending work
969 item for over a given amount of time, 30s by default, a
970 warning message is printed along with dump of workqueue
971 state. This can be configured through kernel parameter
972 "workqueue.watchdog_thresh" and its sysfs counterpart.
974 endmenu # "Debug lockups and hangs"
979 Say Y here to enable the kernel to panic when it oopses. This
980 has the same effect as setting oops=panic on the kernel command
983 This feature is useful to ensure that the kernel does not do
984 anything erroneous after an oops which could result in data
985 corruption or other issues.
989 config PANIC_ON_OOPS_VALUE
992 default 0 if !PANIC_ON_OOPS
993 default 1 if PANIC_ON_OOPS
999 Set the timeout value (in seconds) until a reboot occurs when the
1000 the kernel panics. If n = 0, then we wait forever. A timeout
1001 value n > 0 will wait n seconds before rebooting, while a timeout
1002 value n < 0 will reboot immediately.
1005 bool "Collect scheduler debugging info"
1006 depends on DEBUG_KERNEL && PROC_FS
1009 If you say Y here, the /proc/sched_debug file will be provided
1010 that can help debug the scheduler. The runtime overhead of this
1018 bool "Collect scheduler statistics"
1019 depends on DEBUG_KERNEL && PROC_FS
1022 If you say Y here, additional code will be inserted into the
1023 scheduler and related routines to collect statistics about
1024 scheduler behavior and provide them in /proc/schedstat. These
1025 stats may be useful for both tuning and debugging the scheduler
1026 If you aren't debugging the scheduler or trying to tune a specific
1027 application, you can say N to avoid the very slight overhead
1030 config SCHED_STACK_END_CHECK
1031 bool "Detect stack corruption on calls to schedule()"
1032 depends on DEBUG_KERNEL
1035 This option checks for a stack overrun on calls to schedule().
1036 If the stack end location is found to be over written always panic as
1037 the content of the corrupted region can no longer be trusted.
1038 This is to ensure no erroneous behaviour occurs which could result in
1039 data corruption or a sporadic crash at a later stage once the region
1040 is examined. The runtime overhead introduced is minimal.
1042 config DEBUG_TIMEKEEPING
1043 bool "Enable extra timekeeping sanity checking"
1045 This option will enable additional timekeeping sanity checks
1046 which may be helpful when diagnosing issues where timekeeping
1047 problems are suspected.
1049 This may include checks in the timekeeping hotpaths, so this
1050 option may have a (very small) performance impact to some
1055 config DEBUG_PREEMPT
1056 bool "Debug preemptible kernel"
1057 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
1060 If you say Y here then the kernel will use a debug variant of the
1061 commonly used smp_processor_id() function and will print warnings
1062 if kernel code uses it in a preemption-unsafe way. Also, the kernel
1063 will detect preemption count underflows.
1065 menu "Lock Debugging (spinlocks, mutexes, etc...)"
1067 config LOCK_DEBUGGING_SUPPORT
1069 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1072 config PROVE_LOCKING
1073 bool "Lock debugging: prove locking correctness"
1074 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1076 select DEBUG_SPINLOCK
1077 select DEBUG_MUTEXES
1078 select DEBUG_RT_MUTEXES if RT_MUTEXES
1080 select DEBUG_WW_MUTEX_SLOWPATH
1081 select DEBUG_LOCK_ALLOC
1082 select TRACE_IRQFLAGS
1085 This feature enables the kernel to prove that all locking
1086 that occurs in the kernel runtime is mathematically
1087 correct: that under no circumstance could an arbitrary (and
1088 not yet triggered) combination of observed locking
1089 sequences (on an arbitrary number of CPUs, running an
1090 arbitrary number of tasks and interrupt contexts) cause a
1093 In short, this feature enables the kernel to report locking
1094 related deadlocks before they actually occur.
1096 The proof does not depend on how hard and complex a
1097 deadlock scenario would be to trigger: how many
1098 participant CPUs, tasks and irq-contexts would be needed
1099 for it to trigger. The proof also does not depend on
1100 timing: if a race and a resulting deadlock is possible
1101 theoretically (no matter how unlikely the race scenario
1102 is), it will be proven so and will immediately be
1103 reported by the kernel (once the event is observed that
1104 makes the deadlock theoretically possible).
1106 If a deadlock is impossible (i.e. the locking rules, as
1107 observed by the kernel, are mathematically correct), the
1108 kernel reports nothing.
1110 NOTE: this feature can also be enabled for rwlocks, mutexes
1111 and rwsems - in which case all dependencies between these
1112 different locking variants are observed and mapped too, and
1113 the proof of observed correctness is also maintained for an
1114 arbitrary combination of these separate locking variants.
1116 For more details, see Documentation/locking/lockdep-design.rst.
1119 bool "Lock usage statistics"
1120 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1122 select DEBUG_SPINLOCK
1123 select DEBUG_MUTEXES
1124 select DEBUG_RT_MUTEXES if RT_MUTEXES
1125 select DEBUG_LOCK_ALLOC
1128 This feature enables tracking lock contention points
1130 For more details, see Documentation/locking/lockstat.rst
1132 This also enables lock events required by "perf lock",
1134 If you want to use "perf lock", you also need to turn on
1135 CONFIG_EVENT_TRACING.
1137 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1138 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1140 config DEBUG_RT_MUTEXES
1141 bool "RT Mutex debugging, deadlock detection"
1142 depends on DEBUG_KERNEL && RT_MUTEXES
1144 This allows rt mutex semantics violations and rt mutex related
1145 deadlocks (lockups) to be detected and reported automatically.
1147 config DEBUG_SPINLOCK
1148 bool "Spinlock and rw-lock debugging: basic checks"
1149 depends on DEBUG_KERNEL
1150 select UNINLINE_SPIN_UNLOCK
1152 Say Y here and build SMP to catch missing spinlock initialization
1153 and certain other kinds of spinlock errors commonly made. This is
1154 best used in conjunction with the NMI watchdog so that spinlock
1155 deadlocks are also debuggable.
1157 config DEBUG_MUTEXES
1158 bool "Mutex debugging: basic checks"
1159 depends on DEBUG_KERNEL
1161 This feature allows mutex semantics violations to be detected and
1164 config DEBUG_WW_MUTEX_SLOWPATH
1165 bool "Wait/wound mutex debugging: Slowpath testing"
1166 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1167 select DEBUG_LOCK_ALLOC
1168 select DEBUG_SPINLOCK
1169 select DEBUG_MUTEXES
1171 This feature enables slowpath testing for w/w mutex users by
1172 injecting additional -EDEADLK wound/backoff cases. Together with
1173 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1174 will test all possible w/w mutex interface abuse with the
1175 exception of simply not acquiring all the required locks.
1176 Note that this feature can introduce significant overhead, so
1177 it really should not be enabled in a production or distro kernel,
1178 even a debug kernel. If you are a driver writer, enable it. If
1179 you are a distro, do not.
1182 bool "RW Semaphore debugging: basic checks"
1183 depends on DEBUG_KERNEL
1185 This debugging feature allows mismatched rw semaphore locks
1186 and unlocks to be detected and reported.
1188 config DEBUG_LOCK_ALLOC
1189 bool "Lock debugging: detect incorrect freeing of live locks"
1190 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1191 select DEBUG_SPINLOCK
1192 select DEBUG_MUTEXES
1193 select DEBUG_RT_MUTEXES if RT_MUTEXES
1196 This feature will check whether any held lock (spinlock, rwlock,
1197 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1198 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1199 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1200 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1201 held during task exit.
1205 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1207 select FRAME_POINTER if !MIPS && !PPC && !ARM && !S390 && !MICROBLAZE && !ARC && !X86
1211 config LOCKDEP_SMALL
1214 config DEBUG_LOCKDEP
1215 bool "Lock dependency engine debugging"
1216 depends on DEBUG_KERNEL && LOCKDEP
1218 If you say Y here, the lock dependency engine will do
1219 additional runtime checks to debug itself, at the price
1220 of more runtime overhead.
1222 config DEBUG_ATOMIC_SLEEP
1223 bool "Sleep inside atomic section checking"
1224 select PREEMPT_COUNT
1225 depends on DEBUG_KERNEL
1226 depends on !ARCH_NO_PREEMPT
1228 If you say Y here, various routines which may sleep will become very
1229 noisy if they are called inside atomic sections: when a spinlock is
1230 held, inside an rcu read side critical section, inside preempt disabled
1231 sections, inside an interrupt, etc...
1233 config DEBUG_LOCKING_API_SELFTESTS
1234 bool "Locking API boot-time self-tests"
1235 depends on DEBUG_KERNEL
1237 Say Y here if you want the kernel to run a short self-test during
1238 bootup. The self-test checks whether common types of locking bugs
1239 are detected by debugging mechanisms or not. (if you disable
1240 lock debugging then those bugs wont be detected of course.)
1241 The following locking APIs are covered: spinlocks, rwlocks,
1244 config LOCK_TORTURE_TEST
1245 tristate "torture tests for locking"
1246 depends on DEBUG_KERNEL
1249 This option provides a kernel module that runs torture tests
1250 on kernel locking primitives. The kernel module may be built
1251 after the fact on the running kernel to be tested, if desired.
1253 Say Y here if you want kernel locking-primitive torture tests
1254 to be built into the kernel.
1255 Say M if you want these torture tests to build as a module.
1256 Say N if you are unsure.
1258 config WW_MUTEX_SELFTEST
1259 tristate "Wait/wound mutex selftests"
1261 This option provides a kernel module that runs tests on the
1262 on the struct ww_mutex locking API.
1264 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1265 with this test harness.
1267 Say M if you want these self tests to build as a module.
1268 Say N if you are unsure.
1270 endmenu # lock debugging
1272 config TRACE_IRQFLAGS
1275 Enables hooks to interrupt enabling and disabling for
1276 either tracing or lock debugging.
1279 bool "Stack backtrace support"
1280 depends on STACKTRACE_SUPPORT
1282 This option causes the kernel to create a /proc/pid/stack for
1283 every process, showing its current stack trace.
1284 It is also used by various kernel debugging features that require
1285 stack trace generation.
1287 config WARN_ALL_UNSEEDED_RANDOM
1288 bool "Warn for all uses of unseeded randomness"
1291 Some parts of the kernel contain bugs relating to their use of
1292 cryptographically secure random numbers before it's actually possible
1293 to generate those numbers securely. This setting ensures that these
1294 flaws don't go unnoticed, by enabling a message, should this ever
1295 occur. This will allow people with obscure setups to know when things
1296 are going wrong, so that they might contact developers about fixing
1299 Unfortunately, on some models of some architectures getting
1300 a fully seeded CRNG is extremely difficult, and so this can
1301 result in dmesg getting spammed for a surprisingly long
1302 time. This is really bad from a security perspective, and
1303 so architecture maintainers really need to do what they can
1304 to get the CRNG seeded sooner after the system is booted.
1305 However, since users cannot do anything actionable to
1306 address this, by default the kernel will issue only a single
1307 warning for the first use of unseeded randomness.
1309 Say Y here if you want to receive warnings for all uses of
1310 unseeded randomness. This will be of use primarily for
1311 those developers interested in improving the security of
1312 Linux kernels running on their architecture (or
1315 config DEBUG_KOBJECT
1316 bool "kobject debugging"
1317 depends on DEBUG_KERNEL
1319 If you say Y here, some extra kobject debugging messages will be sent
1322 config DEBUG_KOBJECT_RELEASE
1323 bool "kobject release debugging"
1324 depends on DEBUG_OBJECTS_TIMERS
1326 kobjects are reference counted objects. This means that their
1327 last reference count put is not predictable, and the kobject can
1328 live on past the point at which a driver decides to drop it's
1329 initial reference to the kobject gained on allocation. An
1330 example of this would be a struct device which has just been
1333 However, some buggy drivers assume that after such an operation,
1334 the memory backing the kobject can be immediately freed. This
1335 goes completely against the principles of a refcounted object.
1337 If you say Y here, the kernel will delay the release of kobjects
1338 on the last reference count to improve the visibility of this
1339 kind of kobject release bug.
1341 config HAVE_DEBUG_BUGVERBOSE
1344 config DEBUG_BUGVERBOSE
1345 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
1346 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
1349 Say Y here to make BUG() panics output the file name and line number
1350 of the BUG call as well as the EIP and oops trace. This aids
1351 debugging but costs about 70-100K of memory.
1354 bool "Debug linked list manipulation"
1355 depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION
1357 Enable this to turn on extended checks in the linked-list
1363 bool "Debug priority linked list manipulation"
1364 depends on DEBUG_KERNEL
1366 Enable this to turn on extended checks in the priority-ordered
1367 linked-list (plist) walking routines. This checks the entire
1368 list multiple times during each manipulation.
1373 bool "Debug SG table operations"
1374 depends on DEBUG_KERNEL
1376 Enable this to turn on checks on scatter-gather tables. This can
1377 help find problems with drivers that do not properly initialize
1382 config DEBUG_NOTIFIERS
1383 bool "Debug notifier call chains"
1384 depends on DEBUG_KERNEL
1386 Enable this to turn on sanity checking for notifier call chains.
1387 This is most useful for kernel developers to make sure that
1388 modules properly unregister themselves from notifier chains.
1389 This is a relatively cheap check but if you care about maximum
1392 config DEBUG_CREDENTIALS
1393 bool "Debug credential management"
1394 depends on DEBUG_KERNEL
1396 Enable this to turn on some debug checking for credential
1397 management. The additional code keeps track of the number of
1398 pointers from task_structs to any given cred struct, and checks to
1399 see that this number never exceeds the usage count of the cred
1402 Furthermore, if SELinux is enabled, this also checks that the
1403 security pointer in the cred struct is never seen to be invalid.
1407 source "kernel/rcu/Kconfig.debug"
1409 config DEBUG_WQ_FORCE_RR_CPU
1410 bool "Force round-robin CPU selection for unbound work items"
1411 depends on DEBUG_KERNEL
1414 Workqueue used to implicitly guarantee that work items queued
1415 without explicit CPU specified are put on the local CPU. This
1416 guarantee is no longer true and while local CPU is still
1417 preferred work items may be put on foreign CPUs. Kernel
1418 parameter "workqueue.debug_force_rr_cpu" is added to force
1419 round-robin CPU selection to flush out usages which depend on the
1420 now broken guarantee. This config option enables the debug
1421 feature by default. When enabled, memory and cache locality will
1424 config DEBUG_BLOCK_EXT_DEVT
1425 bool "Force extended block device numbers and spread them"
1426 depends on DEBUG_KERNEL
1430 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1431 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1432 YOU ARE DOING. Distros, please enable this and fix whatever
1435 Conventionally, block device numbers are allocated from
1436 predetermined contiguous area. However, extended block area
1437 may introduce non-contiguous block device numbers. This
1438 option forces most block device numbers to be allocated from
1439 the extended space and spreads them to discover kernel or
1440 userland code paths which assume predetermined contiguous
1441 device number allocation.
1443 Note that turning on this debug option shuffles all the
1444 device numbers for all IDE and SCSI devices including libata
1445 ones, so root partition specified using device number
1446 directly (via rdev or root=MAJ:MIN) won't work anymore.
1447 Textual device names (root=/dev/sdXn) will continue to work.
1449 Say N if you are unsure.
1451 config CPU_HOTPLUG_STATE_CONTROL
1452 bool "Enable CPU hotplug state control"
1453 depends on DEBUG_KERNEL
1454 depends on HOTPLUG_CPU
1457 Allows to write steps between "offline" and "online" to the CPUs
1458 sysfs target file so states can be stepped granular. This is a debug
1459 option for now as the hotplug machinery cannot be stopped and
1460 restarted at arbitrary points yet.
1462 Say N if your are unsure.
1464 config NOTIFIER_ERROR_INJECTION
1465 tristate "Notifier error injection"
1466 depends on DEBUG_KERNEL
1469 This option provides the ability to inject artificial errors to
1470 specified notifier chain callbacks. It is useful to test the error
1471 handling of notifier call chain failures.
1475 config PM_NOTIFIER_ERROR_INJECT
1476 tristate "PM notifier error injection module"
1477 depends on PM && NOTIFIER_ERROR_INJECTION
1478 default m if PM_DEBUG
1480 This option provides the ability to inject artificial errors to
1481 PM notifier chain callbacks. It is controlled through debugfs
1482 interface /sys/kernel/debug/notifier-error-inject/pm
1484 If the notifier call chain should be failed with some events
1485 notified, write the error code to "actions/<notifier event>/error".
1487 Example: Inject PM suspend error (-12 = -ENOMEM)
1489 # cd /sys/kernel/debug/notifier-error-inject/pm/
1490 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1491 # echo mem > /sys/power/state
1492 bash: echo: write error: Cannot allocate memory
1494 To compile this code as a module, choose M here: the module will
1495 be called pm-notifier-error-inject.
1499 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1500 tristate "OF reconfig notifier error injection module"
1501 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1503 This option provides the ability to inject artificial errors to
1504 OF reconfig notifier chain callbacks. It is controlled
1505 through debugfs interface under
1506 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1508 If the notifier call chain should be failed with some events
1509 notified, write the error code to "actions/<notifier event>/error".
1511 To compile this code as a module, choose M here: the module will
1512 be called of-reconfig-notifier-error-inject.
1516 config NETDEV_NOTIFIER_ERROR_INJECT
1517 tristate "Netdev notifier error injection module"
1518 depends on NET && NOTIFIER_ERROR_INJECTION
1520 This option provides the ability to inject artificial errors to
1521 netdevice notifier chain callbacks. It is controlled through debugfs
1522 interface /sys/kernel/debug/notifier-error-inject/netdev
1524 If the notifier call chain should be failed with some events
1525 notified, write the error code to "actions/<notifier event>/error".
1527 Example: Inject netdevice mtu change error (-22 = -EINVAL)
1529 # cd /sys/kernel/debug/notifier-error-inject/netdev
1530 # echo -22 > actions/NETDEV_CHANGEMTU/error
1531 # ip link set eth0 mtu 1024
1532 RTNETLINK answers: Invalid argument
1534 To compile this code as a module, choose M here: the module will
1535 be called netdev-notifier-error-inject.
1539 config FUNCTION_ERROR_INJECTION
1541 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
1543 config FAULT_INJECTION
1544 bool "Fault-injection framework"
1545 depends on DEBUG_KERNEL
1547 Provide fault-injection framework.
1548 For more details, see Documentation/fault-injection/.
1551 bool "Fault-injection capability for kmalloc"
1552 depends on FAULT_INJECTION
1553 depends on SLAB || SLUB
1555 Provide fault-injection capability for kmalloc.
1557 config FAIL_PAGE_ALLOC
1558 bool "Fault-injection capabilitiy for alloc_pages()"
1559 depends on FAULT_INJECTION
1561 Provide fault-injection capability for alloc_pages().
1563 config FAIL_MAKE_REQUEST
1564 bool "Fault-injection capability for disk IO"
1565 depends on FAULT_INJECTION && BLOCK
1567 Provide fault-injection capability for disk IO.
1569 config FAIL_IO_TIMEOUT
1570 bool "Fault-injection capability for faking disk interrupts"
1571 depends on FAULT_INJECTION && BLOCK
1573 Provide fault-injection capability on end IO handling. This
1574 will make the block layer "forget" an interrupt as configured,
1575 thus exercising the error handling.
1577 Only works with drivers that use the generic timeout handling,
1578 for others it wont do anything.
1581 bool "Fault-injection capability for futexes"
1583 depends on FAULT_INJECTION && FUTEX
1585 Provide fault-injection capability for futexes.
1587 config FAULT_INJECTION_DEBUG_FS
1588 bool "Debugfs entries for fault-injection capabilities"
1589 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1591 Enable configuration of fault-injection capabilities via debugfs.
1593 config FAIL_FUNCTION
1594 bool "Fault-injection capability for functions"
1595 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
1597 Provide function-based fault-injection capability.
1598 This will allow you to override a specific function with a return
1599 with given return value. As a result, function caller will see
1600 an error value and have to handle it. This is useful to test the
1601 error handling in various subsystems.
1603 config FAIL_MMC_REQUEST
1604 bool "Fault-injection capability for MMC IO"
1605 depends on FAULT_INJECTION_DEBUG_FS && MMC
1607 Provide fault-injection capability for MMC IO.
1608 This will make the mmc core return data errors. This is
1609 useful to test the error handling in the mmc block device
1610 and to test how the mmc host driver handles retries from
1613 config FAULT_INJECTION_STACKTRACE_FILTER
1614 bool "stacktrace filter for fault-injection capabilities"
1615 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1618 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86
1620 Provide stacktrace filter for fault-injection capabilities
1623 bool "Latency measuring infrastructure"
1624 depends on DEBUG_KERNEL
1625 depends on STACKTRACE_SUPPORT
1627 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86
1634 Enable this option if you want to use the LatencyTOP tool
1635 to find out which userspace is blocking on what kernel operations.
1637 source "kernel/trace/Kconfig"
1639 config PROVIDE_OHCI1394_DMA_INIT
1640 bool "Remote debugging over FireWire early on boot"
1641 depends on PCI && X86
1643 If you want to debug problems which hang or crash the kernel early
1644 on boot and the crashing machine has a FireWire port, you can use
1645 this feature to remotely access the memory of the crashed machine
1646 over FireWire. This employs remote DMA as part of the OHCI1394
1647 specification which is now the standard for FireWire controllers.
1649 With remote DMA, you can monitor the printk buffer remotely using
1650 firescope and access all memory below 4GB using fireproxy from gdb.
1651 Even controlling a kernel debugger is possible using remote DMA.
1655 If ohci1394_dma=early is used as boot parameter, it will initialize
1656 all OHCI1394 controllers which are found in the PCI config space.
1658 As all changes to the FireWire bus such as enabling and disabling
1659 devices cause a bus reset and thereby disable remote DMA for all
1660 devices, be sure to have the cable plugged and FireWire enabled on
1661 the debugging host before booting the debug target for debugging.
1663 This code (~1k) is freed after boot. By then, the firewire stack
1664 in charge of the OHCI-1394 controllers should be used instead.
1666 See Documentation/debugging-via-ohci1394.txt for more information.
1668 menuconfig RUNTIME_TESTING_MENU
1669 bool "Runtime Testing"
1672 if RUNTIME_TESTING_MENU
1675 tristate "Linux Kernel Dump Test Tool Module"
1678 This module enables testing of the different dumping mechanisms by
1679 inducing system failures at predefined crash points.
1680 If you don't need it: say N
1681 Choose M here to compile this code as a module. The module will be
1684 Documentation on how to use the module can be found in
1685 Documentation/fault-injection/provoke-crashes.rst
1687 config TEST_LIST_SORT
1688 tristate "Linked list sorting test"
1689 depends on DEBUG_KERNEL || m
1691 Enable this to turn on 'list_sort()' function test. This test is
1692 executed only once during system boot (so affects only boot time),
1693 or at module load time.
1698 tristate "Array-based sort test"
1699 depends on DEBUG_KERNEL || m
1701 This option enables the self-test function of 'sort()' at boot,
1702 or at module load time.
1706 config KPROBES_SANITY_TEST
1707 bool "Kprobes sanity tests"
1708 depends on DEBUG_KERNEL
1711 This option provides for testing basic kprobes functionality on
1712 boot. Samples of kprobe and kretprobe are inserted and
1713 verified for functionality.
1715 Say N if you are unsure.
1717 config BACKTRACE_SELF_TEST
1718 tristate "Self test for the backtrace code"
1719 depends on DEBUG_KERNEL
1721 This option provides a kernel module that can be used to test
1722 the kernel stack backtrace code. This option is not useful
1723 for distributions or general kernels, but only for kernel
1724 developers working on architecture code.
1726 Note that if you want to also test saved backtraces, you will
1727 have to enable STACKTRACE as well.
1729 Say N if you are unsure.
1732 tristate "Red-Black tree test"
1733 depends on DEBUG_KERNEL
1735 A benchmark measuring the performance of the rbtree library.
1736 Also includes rbtree invariant checks.
1738 config REED_SOLOMON_TEST
1739 tristate "Reed-Solomon library test"
1740 depends on DEBUG_KERNEL || m
1742 select REED_SOLOMON_ENC16
1743 select REED_SOLOMON_DEC16
1745 This option enables the self-test function of rslib at boot,
1746 or at module load time.
1750 config INTERVAL_TREE_TEST
1751 tristate "Interval tree test"
1752 depends on DEBUG_KERNEL
1753 select INTERVAL_TREE
1755 A benchmark measuring the performance of the interval tree library
1758 tristate "Per cpu operations test"
1759 depends on m && DEBUG_KERNEL
1761 Enable this option to build test module which validates per-cpu
1766 config ATOMIC64_SELFTEST
1767 tristate "Perform an atomic64_t self-test"
1769 Enable this option to test the atomic64_t functions at boot or
1770 at module load time.
1774 config ASYNC_RAID6_TEST
1775 tristate "Self test for hardware accelerated raid6 recovery"
1776 depends on ASYNC_RAID6_RECOV
1779 This is a one-shot self test that permutes through the
1780 recovery of all the possible two disk failure scenarios for a
1781 N-disk array. Recovery is performed with the asynchronous
1782 raid6 recovery routines, and will optionally use an offload
1783 engine if one is available.
1788 tristate "Test functions located in the hexdump module at runtime"
1790 config TEST_STRING_HELPERS
1791 tristate "Test functions located in the string_helpers module at runtime"
1794 tristate "Test strscpy*() family of functions at runtime"
1797 tristate "Test kstrto*() family of functions at runtime"
1800 tristate "Test printf() family of functions at runtime"
1803 tristate "Test bitmap_*() family of functions at runtime"
1805 Enable this option to test the bitmap functions at boot.
1809 config TEST_BITFIELD
1810 tristate "Test bitfield functions at runtime"
1812 Enable this option to test the bitfield functions at boot.
1817 tristate "Test functions located in the uuid module at runtime"
1820 tristate "Test the XArray code at runtime"
1822 config TEST_OVERFLOW
1823 tristate "Test check_*_overflow() functions at runtime"
1825 config TEST_RHASHTABLE
1826 tristate "Perform selftest on resizable hash table"
1828 Enable this option to test the rhashtable functions at boot.
1833 tristate "Perform selftest on hash functions"
1835 Enable this option to test the kernel's integer (<linux/hash.h>),
1836 string (<linux/stringhash.h>), and siphash (<linux/siphash.h>)
1837 hash functions on boot (or module load).
1839 This is intended to help people writing architecture-specific
1840 optimized versions. If unsure, say N.
1843 tristate "Perform selftest on IDA functions"
1846 tristate "Perform selftest on priority array manager"
1849 Enable this option to test priority array manager on boot
1854 config TEST_IRQ_TIMINGS
1855 bool "IRQ timings selftest"
1856 depends on IRQ_TIMINGS
1858 Enable this option to test the irq timings code on boot.
1863 tristate "Test module loading with 'hello world' module"
1866 This builds the "test_module" module that emits "Hello, world"
1867 on printk when loaded. It is designed to be used for basic
1868 evaluation of the module loading subsystem (for example when
1869 validating module verification). It lacks any extra dependencies,
1870 and will not normally be loaded by the system unless explicitly
1876 tristate "Test module for stress/performance analysis of vmalloc allocator"
1881 This builds the "test_vmalloc" module that should be used for
1882 stress and performance analysis. So, any new change for vmalloc
1883 subsystem can be evaluated from performance and stability point
1888 config TEST_USER_COPY
1889 tristate "Test user/kernel boundary protections"
1892 This builds the "test_user_copy" module that runs sanity checks
1893 on the copy_to/from_user infrastructure, making sure basic
1894 user/kernel boundary testing is working. If it fails to load,
1895 a regression has been detected in the user/kernel memory boundary
1901 tristate "Test BPF filter functionality"
1904 This builds the "test_bpf" module that runs various test vectors
1905 against the BPF interpreter or BPF JIT compiler depending on the
1906 current setting. This is in particular useful for BPF JIT compiler
1907 development, but also to run regression tests against changes in
1908 the interpreter code. It also enables test stubs for eBPF maps and
1909 verifier used by user space verifier testsuite.
1913 config TEST_BLACKHOLE_DEV
1914 tristate "Test blackhole netdev functionality"
1917 This builds the "test_blackhole_dev" module that validates the
1918 data path through this blackhole netdev.
1922 config FIND_BIT_BENCHMARK
1923 tristate "Test find_bit functions"
1925 This builds the "test_find_bit" module that measure find_*_bit()
1926 functions performance.
1930 config TEST_FIRMWARE
1931 tristate "Test firmware loading via userspace interface"
1932 depends on FW_LOADER
1934 This builds the "test_firmware" module that creates a userspace
1935 interface for testing firmware loading. This can be used to
1936 control the triggering of firmware loading without needing an
1937 actual firmware-using device. The contents can be rechecked by
1943 tristate "sysctl test driver"
1944 depends on PROC_SYSCTL
1946 This builds the "test_sysctl" module. This driver enables to test the
1947 proc sysctl interfaces available to drivers safely without affecting
1948 production knobs which might alter system functionality.
1953 tristate "udelay test driver"
1955 This builds the "udelay_test" module that helps to make sure
1956 that udelay() is working properly.
1960 config TEST_STATIC_KEYS
1961 tristate "Test static keys"
1964 Test the static key interfaces.
1969 tristate "kmod stress tester"
1971 depends on NETDEVICES && NET_CORE && INET # for TUN
1978 Test the kernel's module loading mechanism: kmod. kmod implements
1979 support to load modules using the Linux kernel's usermode helper.
1980 This test provides a series of tests against kmod.
1982 Although technically you can either build test_kmod as a module or
1983 into the kernel we disallow building it into the kernel since
1984 it stress tests request_module() and this will very likely cause
1985 some issues by taking over precious threads available from other
1986 module load requests, ultimately this could be fatal.
1990 tools/testing/selftests/kmod/kmod.sh --help
1994 config TEST_DEBUG_VIRTUAL
1995 tristate "Test CONFIG_DEBUG_VIRTUAL feature"
1996 depends on DEBUG_VIRTUAL
1998 Test the kernel's ability to detect incorrect calls to
1999 virt_to_phys() done against the non-linear part of the
2000 kernel's virtual address map.
2004 config TEST_MEMCAT_P
2005 tristate "Test memcat_p() helper function"
2007 Test the memcat_p() helper for correctly merging two
2008 pointer arrays together.
2012 config TEST_LIVEPATCH
2013 tristate "Test livepatching"
2015 depends on DYNAMIC_DEBUG
2016 depends on LIVEPATCH
2019 Test kernel livepatching features for correctness. The tests will
2020 load test modules that will be livepatched in various scenarios.
2022 To run all the livepatching tests:
2024 make -C tools/testing/selftests TARGETS=livepatch run_tests
2026 Alternatively, individual tests may be invoked:
2028 tools/testing/selftests/livepatch/test-callbacks.sh
2029 tools/testing/selftests/livepatch/test-livepatch.sh
2030 tools/testing/selftests/livepatch/test-shadow-vars.sh
2035 tristate "Perform selftest on object aggreration manager"
2039 Enable this option to test object aggregation manager on boot
2043 config TEST_STACKINIT
2044 tristate "Test level of stack variable initialization"
2046 Test if the kernel is zero-initializing stack variables and
2047 padding. Coverage is controlled by compiler flags,
2048 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2049 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2054 tristate "Test heap/page initialization"
2056 Test if the kernel is zero-initializing heap and page allocations.
2057 This can be useful to test init_on_alloc and init_on_free features.
2061 endif # RUNTIME_TESTING_MENU
2066 This option adds a kernel parameter 'memtest', which allows memtest
2068 memtest=0, mean disabled; -- default
2069 memtest=1, mean do 1 test pattern;
2071 memtest=17, mean do 17 test patterns.
2072 If you are unsure how to answer this question, answer N.
2074 config BUG_ON_DATA_CORRUPTION
2075 bool "Trigger a BUG when data corruption is detected"
2078 Select this option if the kernel should BUG when it encounters
2079 data corruption in kernel memory structures when they get checked
2084 source "samples/Kconfig"
2086 source "lib/Kconfig.kgdb"
2088 source "lib/Kconfig.ubsan"
2090 config ARCH_HAS_DEVMEM_IS_ALLOWED
2093 config STRICT_DEVMEM
2094 bool "Filter access to /dev/mem"
2095 depends on MMU && DEVMEM
2096 depends on ARCH_HAS_DEVMEM_IS_ALLOWED
2097 default y if PPC || X86 || ARM64
2099 If this option is disabled, you allow userspace (root) access to all
2100 of memory, including kernel and userspace memory. Accidental
2101 access to this is obviously disastrous, but specific access can
2102 be used by people debugging the kernel. Note that with PAT support
2103 enabled, even in this case there are restrictions on /dev/mem
2104 use due to the cache aliasing requirements.
2106 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
2107 file only allows userspace access to PCI space and the BIOS code and
2108 data regions. This is sufficient for dosemu and X and all common
2113 config IO_STRICT_DEVMEM
2114 bool "Filter I/O access to /dev/mem"
2115 depends on STRICT_DEVMEM
2117 If this option is disabled, you allow userspace (root) access to all
2118 io-memory regardless of whether a driver is actively using that
2119 range. Accidental access to this is obviously disastrous, but
2120 specific access can be used by people debugging kernel drivers.
2122 If this option is switched on, the /dev/mem file only allows
2123 userspace access to *idle* io-memory ranges (see /proc/iomem) This
2124 may break traditional users of /dev/mem (dosemu, legacy X, etc...)
2125 if the driver using a given range cannot be disabled.
2129 source "arch/$(SRCARCH)/Kconfig.debug"
2131 endmenu # Kernel hacking
projects / linux-2.6-microblaze.git / blob