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"
101 depends on (DEBUG_FS || PROC_FS)
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 or procfs.
120 Thus, the debugfs or procfs filesystem must first be mounted before
121 making use of this feature.
122 We refer the control file as: <debugfs>/dynamic_debug/control. This
123 file contains a list of the debug statements that can be enabled. The
124 format for each line of the file is:
126 filename:lineno [module]function flags format
128 filename : source file of the debug statement
129 lineno : line number of the debug statement
130 module : module that contains the debug statement
131 function : function that contains the debug statement
132 flags : '=p' means the line is turned 'on' for printing
133 format : the format used for the debug statement
137 nullarbor:~ # cat <debugfs>/dynamic_debug/control
138 # filename:lineno [module]function flags format
139 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
140 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
141 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
145 // enable the message at line 1603 of file svcsock.c
146 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
147 <debugfs>/dynamic_debug/control
149 // enable all the messages in file svcsock.c
150 nullarbor:~ # echo -n 'file svcsock.c +p' >
151 <debugfs>/dynamic_debug/control
153 // enable all the messages in the NFS server module
154 nullarbor:~ # echo -n 'module nfsd +p' >
155 <debugfs>/dynamic_debug/control
157 // enable all 12 messages in the function svc_process()
158 nullarbor:~ # echo -n 'func svc_process +p' >
159 <debugfs>/dynamic_debug/control
161 // disable all 12 messages in the function svc_process()
162 nullarbor:~ # echo -n 'func svc_process -p' >
163 <debugfs>/dynamic_debug/control
165 See Documentation/admin-guide/dynamic-debug-howto.rst for additional
168 config SYMBOLIC_ERRNAME
169 bool "Support symbolic error names in printf"
172 If you say Y here, the kernel's printf implementation will
173 be able to print symbolic error names such as ENOSPC instead
174 of the number 28. It makes the kernel image slightly larger
175 (about 3KB), but can make the kernel logs easier to read.
177 config DEBUG_BUGVERBOSE
178 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
179 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
182 Say Y here to make BUG() panics output the file name and line number
183 of the BUG call as well as the EIP and oops trace. This aids
184 debugging but costs about 70-100K of memory.
186 endmenu # "printk and dmesg options"
188 menu "Compile-time checks and compiler options"
191 bool "Compile the kernel with debug info"
192 depends on DEBUG_KERNEL && !COMPILE_TEST
194 If you say Y here the resulting kernel image will include
195 debugging info resulting in a larger kernel image.
196 This adds debug symbols to the kernel and modules (gcc -g), and
197 is needed if you intend to use kernel crashdump or binary object
198 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
199 Say Y here only if you plan to debug the kernel.
203 config DEBUG_INFO_REDUCED
204 bool "Reduce debugging information"
205 depends on DEBUG_INFO
207 If you say Y here gcc is instructed to generate less debugging
208 information for structure types. This means that tools that
209 need full debugging information (like kgdb or systemtap) won't
210 be happy. But if you merely need debugging information to
211 resolve line numbers there is no loss. Advantage is that
212 build directory object sizes shrink dramatically over a full
213 DEBUG_INFO build and compile times are reduced too.
214 Only works with newer gcc versions.
216 config DEBUG_INFO_SPLIT
217 bool "Produce split debuginfo in .dwo files"
218 depends on DEBUG_INFO
219 depends on $(cc-option,-gsplit-dwarf)
221 Generate debug info into separate .dwo files. This significantly
222 reduces the build directory size for builds with DEBUG_INFO,
223 because it stores the information only once on disk in .dwo
224 files instead of multiple times in object files and executables.
225 In addition the debug information is also compressed.
227 Requires recent gcc (4.7+) and recent gdb/binutils.
228 Any tool that packages or reads debug information would need
229 to know about the .dwo files and include them.
230 Incompatible with older versions of ccache.
232 config DEBUG_INFO_DWARF4
233 bool "Generate dwarf4 debuginfo"
234 depends on DEBUG_INFO
235 depends on $(cc-option,-gdwarf-4)
237 Generate dwarf4 debug info. This requires recent versions
238 of gcc and gdb. It makes the debug information larger.
239 But it significantly improves the success of resolving
240 variables in gdb on optimized code.
242 config DEBUG_INFO_BTF
243 bool "Generate BTF typeinfo"
244 depends on DEBUG_INFO
245 depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED
246 depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST
248 Generate deduplicated BTF type information from DWARF debug info.
249 Turning this on expects presence of pahole tool, which will convert
250 DWARF type info into equivalent deduplicated BTF type info.
253 bool "Provide GDB scripts for kernel debugging"
254 depends on DEBUG_INFO
256 This creates the required links to GDB helper scripts in the
257 build directory. If you load vmlinux into gdb, the helper
258 scripts will be automatically imported by gdb as well, and
259 additional functions are available to analyze a Linux kernel
260 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
263 config ENABLE_MUST_CHECK
264 bool "Enable __must_check logic"
267 Enable the __must_check logic in the kernel build. Disable this to
268 suppress the "warning: ignoring return value of 'foo', declared with
269 attribute warn_unused_result" messages.
272 int "Warn for stack frames larger than"
274 default 2048 if GCC_PLUGIN_LATENT_ENTROPY
275 default 1280 if (!64BIT && PARISC)
276 default 1024 if (!64BIT && !PARISC)
277 default 2048 if 64BIT
279 Tell gcc to warn at build time for stack frames larger than this.
280 Setting this too low will cause a lot of warnings.
281 Setting it to 0 disables the warning.
283 config STRIP_ASM_SYMS
284 bool "Strip assembler-generated symbols during link"
287 Strip internal assembler-generated symbols during a link (symbols
288 that look like '.Lxxx') so they don't pollute the output of
289 get_wchan() and suchlike.
292 bool "Generate readable assembler code"
293 depends on DEBUG_KERNEL
295 Disable some compiler optimizations that tend to generate human unreadable
296 assembler output. This may make the kernel slightly slower, but it helps
297 to keep kernel developers who have to stare a lot at assembler listings
300 config HEADERS_INSTALL
301 bool "Install uapi headers to usr/include"
304 This option will install uapi headers (headers exported to user-space)
305 into the usr/include directory for use during the kernel build.
306 This is unneeded for building the kernel itself, but needed for some
307 user-space program samples. It is also needed by some features such
308 as uapi header sanity checks.
310 config DEBUG_SECTION_MISMATCH
311 bool "Enable full Section mismatch analysis"
313 The section mismatch analysis checks if there are illegal
314 references from one section to another section.
315 During linktime or runtime, some sections are dropped;
316 any use of code/data previously in these sections would
317 most likely result in an oops.
318 In the code, functions and variables are annotated with
319 __init,, etc. (see the full list in include/linux/init.h),
320 which results in the code/data being placed in specific sections.
321 The section mismatch analysis is always performed after a full
322 kernel build, and enabling this option causes the following
323 additional step to occur:
324 - Add the option -fno-inline-functions-called-once to gcc commands.
325 When inlining a function annotated with __init in a non-init
326 function, we would lose the section information and thus
327 the analysis would not catch the illegal reference.
328 This option tells gcc to inline less (but it does result in
331 config SECTION_MISMATCH_WARN_ONLY
332 bool "Make section mismatch errors non-fatal"
335 If you say N here, the build process will fail if there are any
336 section mismatch, instead of just throwing warnings.
341 # Select this config option from the architecture Kconfig, if it
342 # is preferred to always offer frame pointers as a config
343 # option on the architecture (regardless of KERNEL_DEBUG):
345 config ARCH_WANT_FRAME_POINTERS
349 bool "Compile the kernel with frame pointers"
350 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
351 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
353 If you say Y here the resulting kernel image will be slightly
354 larger and slower, but it gives very useful debugging information
355 in case of kernel bugs. (precise oopses/stacktraces/warnings)
357 config STACK_VALIDATION
358 bool "Compile-time stack metadata validation"
359 depends on HAVE_STACK_VALIDATION
362 Add compile-time checks to validate stack metadata, including frame
363 pointers (if CONFIG_FRAME_POINTER is enabled). This helps ensure
364 that runtime stack traces are more reliable.
366 This is also a prerequisite for generation of ORC unwind data, which
367 is needed for CONFIG_UNWINDER_ORC.
369 For more information, see
370 tools/objtool/Documentation/stack-validation.txt.
372 config DEBUG_FORCE_WEAK_PER_CPU
373 bool "Force weak per-cpu definitions"
374 depends on DEBUG_KERNEL
376 s390 and alpha require percpu variables in modules to be
377 defined weak to work around addressing range issue which
378 puts the following two restrictions on percpu variable
381 1. percpu symbols must be unique whether static or not
382 2. percpu variables can't be defined inside a function
384 To ensure that generic code follows the above rules, this
385 option forces all percpu variables to be defined as weak.
387 endmenu # "Compiler options"
389 menu "Generic Kernel Debugging Instruments"
392 bool "Magic SysRq key"
395 If you say Y here, you will have some control over the system even
396 if the system crashes for example during kernel debugging (e.g., you
397 will be able to flush the buffer cache to disk, reboot the system
398 immediately or dump some status information). This is accomplished
399 by pressing various keys while holding SysRq (Alt+PrintScreen). It
400 also works on a serial console (on PC hardware at least), if you
401 send a BREAK and then within 5 seconds a command keypress. The
402 keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
403 Don't say Y unless you really know what this hack does.
405 config MAGIC_SYSRQ_DEFAULT_ENABLE
406 hex "Enable magic SysRq key functions by default"
407 depends on MAGIC_SYSRQ
410 Specifies which SysRq key functions are enabled by default.
411 This may be set to 1 or 0 to enable or disable them all, or
412 to a bitmask as described in Documentation/admin-guide/sysrq.rst.
414 config MAGIC_SYSRQ_SERIAL
415 bool "Enable magic SysRq key over serial"
416 depends on MAGIC_SYSRQ
419 Many embedded boards have a disconnected TTL level serial which can
420 generate some garbage that can lead to spurious false sysrq detects.
421 This option allows you to decide whether you want to enable the
424 config MAGIC_SYSRQ_SERIAL_SEQUENCE
425 string "Char sequence that enables magic SysRq over serial"
426 depends on MAGIC_SYSRQ_SERIAL
429 Specifies a sequence of characters that can follow BREAK to enable
430 SysRq on a serial console.
432 If unsure, leave an empty string and the option will not be enabled.
435 bool "Debug Filesystem"
437 debugfs is a virtual file system that kernel developers use to put
438 debugging files into. Enable this option to be able to read and
439 write to these files.
441 For detailed documentation on the debugfs API, see
442 Documentation/filesystems/.
446 source "lib/Kconfig.kgdb"
448 source "lib/Kconfig.ubsan"
453 bool "Kernel debugging"
455 Say Y here if you are developing drivers or trying to debug and
456 identify kernel problems.
459 bool "Miscellaneous debug code"
461 depends on DEBUG_KERNEL
463 Say Y here if you need to enable miscellaneous debug code that should
464 be under a more specific debug option but isn't.
467 menu "Memory Debugging"
469 source "mm/Kconfig.debug"
472 bool "Debug object operations"
473 depends on DEBUG_KERNEL
475 If you say Y here, additional code will be inserted into the
476 kernel to track the life time of various objects and validate
477 the operations on those objects.
479 config DEBUG_OBJECTS_SELFTEST
480 bool "Debug objects selftest"
481 depends on DEBUG_OBJECTS
483 This enables the selftest of the object debug code.
485 config DEBUG_OBJECTS_FREE
486 bool "Debug objects in freed memory"
487 depends on DEBUG_OBJECTS
489 This enables checks whether a k/v free operation frees an area
490 which contains an object which has not been deactivated
491 properly. This can make kmalloc/kfree-intensive workloads
494 config DEBUG_OBJECTS_TIMERS
495 bool "Debug timer objects"
496 depends on DEBUG_OBJECTS
498 If you say Y here, additional code will be inserted into the
499 timer routines to track the life time of timer objects and
500 validate the timer operations.
502 config DEBUG_OBJECTS_WORK
503 bool "Debug work objects"
504 depends on DEBUG_OBJECTS
506 If you say Y here, additional code will be inserted into the
507 work queue routines to track the life time of work objects and
508 validate the work operations.
510 config DEBUG_OBJECTS_RCU_HEAD
511 bool "Debug RCU callbacks objects"
512 depends on DEBUG_OBJECTS
514 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
516 config DEBUG_OBJECTS_PERCPU_COUNTER
517 bool "Debug percpu counter objects"
518 depends on DEBUG_OBJECTS
520 If you say Y here, additional code will be inserted into the
521 percpu counter routines to track the life time of percpu counter
522 objects and validate the percpu counter operations.
524 config DEBUG_OBJECTS_ENABLE_DEFAULT
525 int "debug_objects bootup default value (0-1)"
528 depends on DEBUG_OBJECTS
530 Debug objects boot parameter default value
533 bool "Debug slab memory allocations"
534 depends on DEBUG_KERNEL && SLAB
536 Say Y here to have the kernel do limited verification on memory
537 allocation as well as poisoning memory on free to catch use of freed
538 memory. This can make kmalloc/kfree-intensive workloads much slower.
541 bool "SLUB debugging on by default"
542 depends on SLUB && SLUB_DEBUG
545 Boot with debugging on by default. SLUB boots by default with
546 the runtime debug capabilities switched off. Enabling this is
547 equivalent to specifying the "slub_debug" parameter on boot.
548 There is no support for more fine grained debug control like
549 possible with slub_debug=xxx. SLUB debugging may be switched
550 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
555 bool "Enable SLUB performance statistics"
556 depends on SLUB && SYSFS
558 SLUB statistics are useful to debug SLUBs allocation behavior in
559 order find ways to optimize the allocator. This should never be
560 enabled for production use since keeping statistics slows down
561 the allocator by a few percentage points. The slabinfo command
562 supports the determination of the most active slabs to figure
563 out which slabs are relevant to a particular load.
564 Try running: slabinfo -DA
566 config HAVE_DEBUG_KMEMLEAK
569 config DEBUG_KMEMLEAK
570 bool "Kernel memory leak detector"
571 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
573 select STACKTRACE if STACKTRACE_SUPPORT
577 Say Y here if you want to enable the memory leak
578 detector. The memory allocation/freeing is traced in a way
579 similar to the Boehm's conservative garbage collector, the
580 difference being that the orphan objects are not freed but
581 only shown in /sys/kernel/debug/kmemleak. Enabling this
582 feature will introduce an overhead to memory
583 allocations. See Documentation/dev-tools/kmemleak.rst for more
586 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
587 of finding leaks due to the slab objects poisoning.
589 In order to access the kmemleak file, debugfs needs to be
590 mounted (usually at /sys/kernel/debug).
592 config DEBUG_KMEMLEAK_MEM_POOL_SIZE
593 int "Kmemleak memory pool size"
594 depends on DEBUG_KMEMLEAK
598 Kmemleak must track all the memory allocations to avoid
599 reporting false positives. Since memory may be allocated or
600 freed before kmemleak is fully initialised, use a static pool
601 of metadata objects to track such callbacks. After kmemleak is
602 fully initialised, this memory pool acts as an emergency one
603 if slab allocations fail.
605 config DEBUG_KMEMLEAK_TEST
606 tristate "Simple test for the kernel memory leak detector"
607 depends on DEBUG_KMEMLEAK && m
609 This option enables a module that explicitly leaks memory.
613 config DEBUG_KMEMLEAK_DEFAULT_OFF
614 bool "Default kmemleak to off"
615 depends on DEBUG_KMEMLEAK
617 Say Y here to disable kmemleak by default. It can then be enabled
618 on the command line via kmemleak=on.
620 config DEBUG_KMEMLEAK_AUTO_SCAN
621 bool "Enable kmemleak auto scan thread on boot up"
623 depends on DEBUG_KMEMLEAK
625 Depending on the cpu, kmemleak scan may be cpu intensive and can
626 stall user tasks at times. This option enables/disables automatic
627 kmemleak scan at boot up.
629 Say N here to disable kmemleak auto scan thread to stop automatic
630 scanning. Disabling this option disables automatic reporting of
635 config DEBUG_STACK_USAGE
636 bool "Stack utilization instrumentation"
637 depends on DEBUG_KERNEL && !IA64
639 Enables the display of the minimum amount of free stack which each
640 task has ever had available in the sysrq-T and sysrq-P debug output.
642 This option will slow down process creation somewhat.
644 config SCHED_STACK_END_CHECK
645 bool "Detect stack corruption on calls to schedule()"
646 depends on DEBUG_KERNEL
649 This option checks for a stack overrun on calls to schedule().
650 If the stack end location is found to be over written always panic as
651 the content of the corrupted region can no longer be trusted.
652 This is to ensure no erroneous behaviour occurs which could result in
653 data corruption or a sporadic crash at a later stage once the region
654 is examined. The runtime overhead introduced is minimal.
658 depends on DEBUG_KERNEL
660 Enable this to turn on extended checks in the virtual-memory system
661 that may impact performance.
665 config DEBUG_VM_VMACACHE
666 bool "Debug VMA caching"
669 Enable this to turn on VMA caching debug information. Doing so
670 can cause significant overhead, so only enable it in non-production
676 bool "Debug VM red-black trees"
679 Enable VM red-black tree debugging information and extra validations.
683 config DEBUG_VM_PGFLAGS
684 bool "Debug page-flags operations"
687 Enables extra validation on page flags operations.
691 config ARCH_HAS_DEBUG_VIRTUAL
695 bool "Debug VM translations"
696 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
698 Enable some costly sanity checks in virtual to page code. This can
699 catch mistakes with virt_to_page() and friends.
703 config DEBUG_NOMMU_REGIONS
704 bool "Debug the global anon/private NOMMU mapping region tree"
705 depends on DEBUG_KERNEL && !MMU
707 This option causes the global tree of anonymous and private mapping
708 regions to be regularly checked for invalid topology.
710 config DEBUG_MEMORY_INIT
711 bool "Debug memory initialisation" if EXPERT
714 Enable this for additional checks during memory initialisation.
715 The sanity checks verify aspects of the VM such as the memory model
716 and other information provided by the architecture. Verbose
717 information will be printed at KERN_DEBUG loglevel depending
718 on the mminit_loglevel= command-line option.
722 config MEMORY_NOTIFIER_ERROR_INJECT
723 tristate "Memory hotplug notifier error injection module"
724 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
726 This option provides the ability to inject artificial errors to
727 memory hotplug notifier chain callbacks. It is controlled through
728 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
730 If the notifier call chain should be failed with some events
731 notified, write the error code to "actions/<notifier event>/error".
733 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
735 # cd /sys/kernel/debug/notifier-error-inject/memory
736 # echo -12 > actions/MEM_GOING_OFFLINE/error
737 # echo offline > /sys/devices/system/memory/memoryXXX/state
738 bash: echo: write error: Cannot allocate memory
740 To compile this code as a module, choose M here: the module will
741 be called memory-notifier-error-inject.
745 config DEBUG_PER_CPU_MAPS
746 bool "Debug access to per_cpu maps"
747 depends on DEBUG_KERNEL
750 Say Y to verify that the per_cpu map being accessed has
751 been set up. This adds a fair amount of code to kernel memory
752 and decreases performance.
757 bool "Highmem debugging"
758 depends on DEBUG_KERNEL && HIGHMEM
760 This option enables additional error checking for high memory
761 systems. Disable for production systems.
763 config HAVE_DEBUG_STACKOVERFLOW
766 config DEBUG_STACKOVERFLOW
767 bool "Check for stack overflows"
768 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
770 Say Y here if you want to check for overflows of kernel, IRQ
771 and exception stacks (if your architecture uses them). This
772 option will show detailed messages if free stack space drops
773 below a certain limit.
775 These kinds of bugs usually occur when call-chains in the
776 kernel get too deep, especially when interrupts are
779 Use this in cases where you see apparently random memory
780 corruption, especially if it appears in 'struct thread_info'
782 If in doubt, say "N".
784 source "lib/Kconfig.kasan"
786 endmenu # "Memory Debugging"
789 bool "Debug shared IRQ handlers"
790 depends on DEBUG_KERNEL
792 Enable this to generate a spurious interrupt as soon as a shared
793 interrupt handler is registered, and just before one is deregistered.
794 Drivers ought to be able to handle interrupts coming in at those
795 points; some don't and need to be caught.
797 menu "Debug Oops, Lockups and Hangs"
802 Say Y here to enable the kernel to panic when it oopses. This
803 has the same effect as setting oops=panic on the kernel command
806 This feature is useful to ensure that the kernel does not do
807 anything erroneous after an oops which could result in data
808 corruption or other issues.
812 config PANIC_ON_OOPS_VALUE
815 default 0 if !PANIC_ON_OOPS
816 default 1 if PANIC_ON_OOPS
822 Set the timeout value (in seconds) until a reboot occurs when the
823 the kernel panics. If n = 0, then we wait forever. A timeout
824 value n > 0 will wait n seconds before rebooting, while a timeout
825 value n < 0 will reboot immediately.
827 config LOCKUP_DETECTOR
830 config SOFTLOCKUP_DETECTOR
831 bool "Detect Soft Lockups"
832 depends on DEBUG_KERNEL && !S390
833 select LOCKUP_DETECTOR
835 Say Y here to enable the kernel to act as a watchdog to detect
838 Softlockups are bugs that cause the kernel to loop in kernel
839 mode for more than 20 seconds, without giving other tasks a
840 chance to run. The current stack trace is displayed upon
841 detection and the system will stay locked up.
843 config BOOTPARAM_SOFTLOCKUP_PANIC
844 bool "Panic (Reboot) On Soft Lockups"
845 depends on SOFTLOCKUP_DETECTOR
847 Say Y here to enable the kernel to panic on "soft lockups",
848 which are bugs that cause the kernel to loop in kernel
849 mode for more than 20 seconds (configurable using the watchdog_thresh
850 sysctl), without giving other tasks a chance to run.
852 The panic can be used in combination with panic_timeout,
853 to cause the system to reboot automatically after a
854 lockup has been detected. This feature is useful for
855 high-availability systems that have uptime guarantees and
856 where a lockup must be resolved ASAP.
860 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
862 depends on SOFTLOCKUP_DETECTOR
864 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
865 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
867 config HARDLOCKUP_DETECTOR_PERF
869 select SOFTLOCKUP_DETECTOR
872 # Enables a timestamp based low pass filter to compensate for perf based
873 # hard lockup detection which runs too fast due to turbo modes.
875 config HARDLOCKUP_CHECK_TIMESTAMP
879 # arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard
880 # lockup detector rather than the perf based detector.
882 config HARDLOCKUP_DETECTOR
883 bool "Detect Hard Lockups"
884 depends on DEBUG_KERNEL && !S390
885 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH
886 select LOCKUP_DETECTOR
887 select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF
888 select HARDLOCKUP_DETECTOR_ARCH if HAVE_HARDLOCKUP_DETECTOR_ARCH
890 Say Y here to enable the kernel to act as a watchdog to detect
893 Hardlockups are bugs that cause the CPU to loop in kernel mode
894 for more than 10 seconds, without letting other interrupts have a
895 chance to run. The current stack trace is displayed upon detection
896 and the system will stay locked up.
898 config BOOTPARAM_HARDLOCKUP_PANIC
899 bool "Panic (Reboot) On Hard Lockups"
900 depends on HARDLOCKUP_DETECTOR
902 Say Y here to enable the kernel to panic on "hard lockups",
903 which are bugs that cause the kernel to loop in kernel
904 mode with interrupts disabled for more than 10 seconds (configurable
905 using the watchdog_thresh sysctl).
909 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
911 depends on HARDLOCKUP_DETECTOR
913 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
914 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
916 config DETECT_HUNG_TASK
917 bool "Detect Hung Tasks"
918 depends on DEBUG_KERNEL
919 default SOFTLOCKUP_DETECTOR
921 Say Y here to enable the kernel to detect "hung tasks",
922 which are bugs that cause the task to be stuck in
923 uninterruptible "D" state indefinitely.
925 When a hung task is detected, the kernel will print the
926 current stack trace (which you should report), but the
927 task will stay in uninterruptible state. If lockdep is
928 enabled then all held locks will also be reported. This
929 feature has negligible overhead.
931 config DEFAULT_HUNG_TASK_TIMEOUT
932 int "Default timeout for hung task detection (in seconds)"
933 depends on DETECT_HUNG_TASK
936 This option controls the default timeout (in seconds) used
937 to determine when a task has become non-responsive and should
940 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
941 sysctl or by writing a value to
942 /proc/sys/kernel/hung_task_timeout_secs.
944 A timeout of 0 disables the check. The default is two minutes.
945 Keeping the default should be fine in most cases.
947 config BOOTPARAM_HUNG_TASK_PANIC
948 bool "Panic (Reboot) On Hung Tasks"
949 depends on DETECT_HUNG_TASK
951 Say Y here to enable the kernel to panic on "hung tasks",
952 which are bugs that cause the kernel to leave a task stuck
953 in uninterruptible "D" state.
955 The panic can be used in combination with panic_timeout,
956 to cause the system to reboot automatically after a
957 hung task has been detected. This feature is useful for
958 high-availability systems that have uptime guarantees and
959 where a hung tasks must be resolved ASAP.
963 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
965 depends on DETECT_HUNG_TASK
967 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
968 default 1 if BOOTPARAM_HUNG_TASK_PANIC
971 bool "Detect Workqueue Stalls"
972 depends on DEBUG_KERNEL
974 Say Y here to enable stall detection on workqueues. If a
975 worker pool doesn't make forward progress on a pending work
976 item for over a given amount of time, 30s by default, a
977 warning message is printed along with dump of workqueue
978 state. This can be configured through kernel parameter
979 "workqueue.watchdog_thresh" and its sysfs counterpart.
982 tristate "Test module to generate lockups"
984 This builds the "test_lockup" module that helps to make sure
985 that watchdogs and lockup detectors are working properly.
987 Depending on module parameters it could emulate soft or hard
988 lockup, "hung task", or locking arbitrary lock for a long time.
989 Also it could generate series of lockups with cooling-down periods.
993 endmenu # "Debug lockups and hangs"
995 menu "Scheduler Debugging"
998 bool "Collect scheduler debugging info"
999 depends on DEBUG_KERNEL && PROC_FS
1002 If you say Y here, the /proc/sched_debug file will be provided
1003 that can help debug the scheduler. The runtime overhead of this
1011 bool "Collect scheduler statistics"
1012 depends on DEBUG_KERNEL && PROC_FS
1015 If you say Y here, additional code will be inserted into the
1016 scheduler and related routines to collect statistics about
1017 scheduler behavior and provide them in /proc/schedstat. These
1018 stats may be useful for both tuning and debugging the scheduler
1019 If you aren't debugging the scheduler or trying to tune a specific
1020 application, you can say N to avoid the very slight overhead
1025 config DEBUG_TIMEKEEPING
1026 bool "Enable extra timekeeping sanity checking"
1028 This option will enable additional timekeeping sanity checks
1029 which may be helpful when diagnosing issues where timekeeping
1030 problems are suspected.
1032 This may include checks in the timekeeping hotpaths, so this
1033 option may have a (very small) performance impact to some
1038 config DEBUG_PREEMPT
1039 bool "Debug preemptible kernel"
1040 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT
1043 If you say Y here then the kernel will use a debug variant of the
1044 commonly used smp_processor_id() function and will print warnings
1045 if kernel code uses it in a preemption-unsafe way. Also, the kernel
1046 will detect preemption count underflows.
1048 menu "Lock Debugging (spinlocks, mutexes, etc...)"
1050 config LOCK_DEBUGGING_SUPPORT
1052 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1055 config PROVE_LOCKING
1056 bool "Lock debugging: prove locking correctness"
1057 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1059 select DEBUG_SPINLOCK
1060 select DEBUG_MUTEXES
1061 select DEBUG_RT_MUTEXES if RT_MUTEXES
1063 select DEBUG_WW_MUTEX_SLOWPATH
1064 select DEBUG_LOCK_ALLOC
1065 select TRACE_IRQFLAGS
1068 This feature enables the kernel to prove that all locking
1069 that occurs in the kernel runtime is mathematically
1070 correct: that under no circumstance could an arbitrary (and
1071 not yet triggered) combination of observed locking
1072 sequences (on an arbitrary number of CPUs, running an
1073 arbitrary number of tasks and interrupt contexts) cause a
1076 In short, this feature enables the kernel to report locking
1077 related deadlocks before they actually occur.
1079 The proof does not depend on how hard and complex a
1080 deadlock scenario would be to trigger: how many
1081 participant CPUs, tasks and irq-contexts would be needed
1082 for it to trigger. The proof also does not depend on
1083 timing: if a race and a resulting deadlock is possible
1084 theoretically (no matter how unlikely the race scenario
1085 is), it will be proven so and will immediately be
1086 reported by the kernel (once the event is observed that
1087 makes the deadlock theoretically possible).
1089 If a deadlock is impossible (i.e. the locking rules, as
1090 observed by the kernel, are mathematically correct), the
1091 kernel reports nothing.
1093 NOTE: this feature can also be enabled for rwlocks, mutexes
1094 and rwsems - in which case all dependencies between these
1095 different locking variants are observed and mapped too, and
1096 the proof of observed correctness is also maintained for an
1097 arbitrary combination of these separate locking variants.
1099 For more details, see Documentation/locking/lockdep-design.rst.
1101 config PROVE_RAW_LOCK_NESTING
1102 bool "Enable raw_spinlock - spinlock nesting checks"
1103 depends on PROVE_LOCKING
1106 Enable the raw_spinlock vs. spinlock nesting checks which ensure
1107 that the lock nesting rules for PREEMPT_RT enabled kernels are
1110 NOTE: There are known nesting problems. So if you enable this
1111 option expect lockdep splats until these problems have been fully
1112 addressed which is work in progress. This config switch allows to
1113 identify and analyze these problems. It will be removed and the
1114 check permanentely enabled once the main issues have been fixed.
1116 If unsure, select N.
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 menu "Debug kernel data structures"
1347 bool "Debug linked list manipulation"
1348 depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION
1350 Enable this to turn on extended checks in the linked-list
1356 bool "Debug priority linked list manipulation"
1357 depends on DEBUG_KERNEL
1359 Enable this to turn on extended checks in the priority-ordered
1360 linked-list (plist) walking routines. This checks the entire
1361 list multiple times during each manipulation.
1366 bool "Debug SG table operations"
1367 depends on DEBUG_KERNEL
1369 Enable this to turn on checks on scatter-gather tables. This can
1370 help find problems with drivers that do not properly initialize
1375 config DEBUG_NOTIFIERS
1376 bool "Debug notifier call chains"
1377 depends on DEBUG_KERNEL
1379 Enable this to turn on sanity checking for notifier call chains.
1380 This is most useful for kernel developers to make sure that
1381 modules properly unregister themselves from notifier chains.
1382 This is a relatively cheap check but if you care about maximum
1385 config BUG_ON_DATA_CORRUPTION
1386 bool "Trigger a BUG when data corruption is detected"
1389 Select this option if the kernel should BUG when it encounters
1390 data corruption in kernel memory structures when they get checked
1397 config DEBUG_CREDENTIALS
1398 bool "Debug credential management"
1399 depends on DEBUG_KERNEL
1401 Enable this to turn on some debug checking for credential
1402 management. The additional code keeps track of the number of
1403 pointers from task_structs to any given cred struct, and checks to
1404 see that this number never exceeds the usage count of the cred
1407 Furthermore, if SELinux is enabled, this also checks that the
1408 security pointer in the cred struct is never seen to be invalid.
1412 source "kernel/rcu/Kconfig.debug"
1414 config DEBUG_WQ_FORCE_RR_CPU
1415 bool "Force round-robin CPU selection for unbound work items"
1416 depends on DEBUG_KERNEL
1419 Workqueue used to implicitly guarantee that work items queued
1420 without explicit CPU specified are put on the local CPU. This
1421 guarantee is no longer true and while local CPU is still
1422 preferred work items may be put on foreign CPUs. Kernel
1423 parameter "workqueue.debug_force_rr_cpu" is added to force
1424 round-robin CPU selection to flush out usages which depend on the
1425 now broken guarantee. This config option enables the debug
1426 feature by default. When enabled, memory and cache locality will
1429 config DEBUG_BLOCK_EXT_DEVT
1430 bool "Force extended block device numbers and spread them"
1431 depends on DEBUG_KERNEL
1435 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1436 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1437 YOU ARE DOING. Distros, please enable this and fix whatever
1440 Conventionally, block device numbers are allocated from
1441 predetermined contiguous area. However, extended block area
1442 may introduce non-contiguous block device numbers. This
1443 option forces most block device numbers to be allocated from
1444 the extended space and spreads them to discover kernel or
1445 userland code paths which assume predetermined contiguous
1446 device number allocation.
1448 Note that turning on this debug option shuffles all the
1449 device numbers for all IDE and SCSI devices including libata
1450 ones, so root partition specified using device number
1451 directly (via rdev or root=MAJ:MIN) won't work anymore.
1452 Textual device names (root=/dev/sdXn) will continue to work.
1454 Say N if you are unsure.
1456 config CPU_HOTPLUG_STATE_CONTROL
1457 bool "Enable CPU hotplug state control"
1458 depends on DEBUG_KERNEL
1459 depends on HOTPLUG_CPU
1462 Allows to write steps between "offline" and "online" to the CPUs
1463 sysfs target file so states can be stepped granular. This is a debug
1464 option for now as the hotplug machinery cannot be stopped and
1465 restarted at arbitrary points yet.
1467 Say N if your are unsure.
1470 bool "Latency measuring infrastructure"
1471 depends on DEBUG_KERNEL
1472 depends on STACKTRACE_SUPPORT
1474 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86
1481 Enable this option if you want to use the LatencyTOP tool
1482 to find out which userspace is blocking on what kernel operations.
1484 source "kernel/trace/Kconfig"
1486 config PROVIDE_OHCI1394_DMA_INIT
1487 bool "Remote debugging over FireWire early on boot"
1488 depends on PCI && X86
1490 If you want to debug problems which hang or crash the kernel early
1491 on boot and the crashing machine has a FireWire port, you can use
1492 this feature to remotely access the memory of the crashed machine
1493 over FireWire. This employs remote DMA as part of the OHCI1394
1494 specification which is now the standard for FireWire controllers.
1496 With remote DMA, you can monitor the printk buffer remotely using
1497 firescope and access all memory below 4GB using fireproxy from gdb.
1498 Even controlling a kernel debugger is possible using remote DMA.
1502 If ohci1394_dma=early is used as boot parameter, it will initialize
1503 all OHCI1394 controllers which are found in the PCI config space.
1505 As all changes to the FireWire bus such as enabling and disabling
1506 devices cause a bus reset and thereby disable remote DMA for all
1507 devices, be sure to have the cable plugged and FireWire enabled on
1508 the debugging host before booting the debug target for debugging.
1510 This code (~1k) is freed after boot. By then, the firewire stack
1511 in charge of the OHCI-1394 controllers should be used instead.
1513 See Documentation/debugging-via-ohci1394.txt for more information.
1515 source "samples/Kconfig"
1517 config ARCH_HAS_DEVMEM_IS_ALLOWED
1520 config STRICT_DEVMEM
1521 bool "Filter access to /dev/mem"
1522 depends on MMU && DEVMEM
1523 depends on ARCH_HAS_DEVMEM_IS_ALLOWED
1524 default y if PPC || X86 || ARM64
1526 If this option is disabled, you allow userspace (root) access to all
1527 of memory, including kernel and userspace memory. Accidental
1528 access to this is obviously disastrous, but specific access can
1529 be used by people debugging the kernel. Note that with PAT support
1530 enabled, even in this case there are restrictions on /dev/mem
1531 use due to the cache aliasing requirements.
1533 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
1534 file only allows userspace access to PCI space and the BIOS code and
1535 data regions. This is sufficient for dosemu and X and all common
1540 config IO_STRICT_DEVMEM
1541 bool "Filter I/O access to /dev/mem"
1542 depends on STRICT_DEVMEM
1544 If this option is disabled, you allow userspace (root) access to all
1545 io-memory regardless of whether a driver is actively using that
1546 range. Accidental access to this is obviously disastrous, but
1547 specific access can be used by people debugging kernel drivers.
1549 If this option is switched on, the /dev/mem file only allows
1550 userspace access to *idle* io-memory ranges (see /proc/iomem) This
1551 may break traditional users of /dev/mem (dosemu, legacy X, etc...)
1552 if the driver using a given range cannot be disabled.
1556 menu "$(SRCARCH) Debugging"
1558 source "arch/$(SRCARCH)/Kconfig.debug"
1562 menu "Kernel Testing and Coverage"
1564 source "lib/kunit/Kconfig"
1566 config NOTIFIER_ERROR_INJECTION
1567 tristate "Notifier error injection"
1568 depends on DEBUG_KERNEL
1571 This option provides the ability to inject artificial errors to
1572 specified notifier chain callbacks. It is useful to test the error
1573 handling of notifier call chain failures.
1577 config PM_NOTIFIER_ERROR_INJECT
1578 tristate "PM notifier error injection module"
1579 depends on PM && NOTIFIER_ERROR_INJECTION
1580 default m if PM_DEBUG
1582 This option provides the ability to inject artificial errors to
1583 PM notifier chain callbacks. It is controlled through debugfs
1584 interface /sys/kernel/debug/notifier-error-inject/pm
1586 If the notifier call chain should be failed with some events
1587 notified, write the error code to "actions/<notifier event>/error".
1589 Example: Inject PM suspend error (-12 = -ENOMEM)
1591 # cd /sys/kernel/debug/notifier-error-inject/pm/
1592 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1593 # echo mem > /sys/power/state
1594 bash: echo: write error: Cannot allocate memory
1596 To compile this code as a module, choose M here: the module will
1597 be called pm-notifier-error-inject.
1601 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1602 tristate "OF reconfig notifier error injection module"
1603 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1605 This option provides the ability to inject artificial errors to
1606 OF reconfig notifier chain callbacks. It is controlled
1607 through debugfs interface under
1608 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1610 If the notifier call chain should be failed with some events
1611 notified, write the error code to "actions/<notifier event>/error".
1613 To compile this code as a module, choose M here: the module will
1614 be called of-reconfig-notifier-error-inject.
1618 config NETDEV_NOTIFIER_ERROR_INJECT
1619 tristate "Netdev notifier error injection module"
1620 depends on NET && NOTIFIER_ERROR_INJECTION
1622 This option provides the ability to inject artificial errors to
1623 netdevice notifier chain callbacks. It is controlled through debugfs
1624 interface /sys/kernel/debug/notifier-error-inject/netdev
1626 If the notifier call chain should be failed with some events
1627 notified, write the error code to "actions/<notifier event>/error".
1629 Example: Inject netdevice mtu change error (-22 = -EINVAL)
1631 # cd /sys/kernel/debug/notifier-error-inject/netdev
1632 # echo -22 > actions/NETDEV_CHANGEMTU/error
1633 # ip link set eth0 mtu 1024
1634 RTNETLINK answers: Invalid argument
1636 To compile this code as a module, choose M here: the module will
1637 be called netdev-notifier-error-inject.
1641 config FUNCTION_ERROR_INJECTION
1643 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
1645 config FAULT_INJECTION
1646 bool "Fault-injection framework"
1647 depends on DEBUG_KERNEL
1649 Provide fault-injection framework.
1650 For more details, see Documentation/fault-injection/.
1653 bool "Fault-injection capability for kmalloc"
1654 depends on FAULT_INJECTION
1655 depends on SLAB || SLUB
1657 Provide fault-injection capability for kmalloc.
1659 config FAIL_PAGE_ALLOC
1660 bool "Fault-injection capability for alloc_pages()"
1661 depends on FAULT_INJECTION
1663 Provide fault-injection capability for alloc_pages().
1665 config FAIL_MAKE_REQUEST
1666 bool "Fault-injection capability for disk IO"
1667 depends on FAULT_INJECTION && BLOCK
1669 Provide fault-injection capability for disk IO.
1671 config FAIL_IO_TIMEOUT
1672 bool "Fault-injection capability for faking disk interrupts"
1673 depends on FAULT_INJECTION && BLOCK
1675 Provide fault-injection capability on end IO handling. This
1676 will make the block layer "forget" an interrupt as configured,
1677 thus exercising the error handling.
1679 Only works with drivers that use the generic timeout handling,
1680 for others it wont do anything.
1683 bool "Fault-injection capability for futexes"
1685 depends on FAULT_INJECTION && FUTEX
1687 Provide fault-injection capability for futexes.
1689 config FAULT_INJECTION_DEBUG_FS
1690 bool "Debugfs entries for fault-injection capabilities"
1691 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1693 Enable configuration of fault-injection capabilities via debugfs.
1695 config FAIL_FUNCTION
1696 bool "Fault-injection capability for functions"
1697 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
1699 Provide function-based fault-injection capability.
1700 This will allow you to override a specific function with a return
1701 with given return value. As a result, function caller will see
1702 an error value and have to handle it. This is useful to test the
1703 error handling in various subsystems.
1705 config FAIL_MMC_REQUEST
1706 bool "Fault-injection capability for MMC IO"
1707 depends on FAULT_INJECTION_DEBUG_FS && MMC
1709 Provide fault-injection capability for MMC IO.
1710 This will make the mmc core return data errors. This is
1711 useful to test the error handling in the mmc block device
1712 and to test how the mmc host driver handles retries from
1715 config FAULT_INJECTION_STACKTRACE_FILTER
1716 bool "stacktrace filter for fault-injection capabilities"
1717 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1720 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86
1722 Provide stacktrace filter for fault-injection capabilities
1724 config ARCH_HAS_KCOV
1727 An architecture should select this when it can successfully
1728 build and run with CONFIG_KCOV. This typically requires
1729 disabling instrumentation for some early boot code.
1731 config CC_HAS_SANCOV_TRACE_PC
1732 def_bool $(cc-option,-fsanitize-coverage=trace-pc)
1736 bool "Code coverage for fuzzing"
1737 depends on ARCH_HAS_KCOV
1738 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
1740 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
1742 KCOV exposes kernel code coverage information in a form suitable
1743 for coverage-guided fuzzing (randomized testing).
1745 If RANDOMIZE_BASE is enabled, PC values will not be stable across
1746 different machines and across reboots. If you need stable PC values,
1747 disable RANDOMIZE_BASE.
1749 For more details, see Documentation/dev-tools/kcov.rst.
1751 config KCOV_ENABLE_COMPARISONS
1752 bool "Enable comparison operands collection by KCOV"
1754 depends on $(cc-option,-fsanitize-coverage=trace-cmp)
1756 KCOV also exposes operands of every comparison in the instrumented
1757 code along with operand sizes and PCs of the comparison instructions.
1758 These operands can be used by fuzzing engines to improve the quality
1759 of fuzzing coverage.
1761 config KCOV_INSTRUMENT_ALL
1762 bool "Instrument all code by default"
1766 If you are doing generic system call fuzzing (like e.g. syzkaller),
1767 then you will want to instrument the whole kernel and you should
1768 say y here. If you are doing more targeted fuzzing (like e.g.
1769 filesystem fuzzing with AFL) then you will want to enable coverage
1770 for more specific subsets of files, and should say n here.
1772 menuconfig RUNTIME_TESTING_MENU
1773 bool "Runtime Testing"
1776 if RUNTIME_TESTING_MENU
1779 tristate "Linux Kernel Dump Test Tool Module"
1782 This module enables testing of the different dumping mechanisms by
1783 inducing system failures at predefined crash points.
1784 If you don't need it: say N
1785 Choose M here to compile this code as a module. The module will be
1788 Documentation on how to use the module can be found in
1789 Documentation/fault-injection/provoke-crashes.rst
1791 config TEST_LIST_SORT
1792 tristate "Linked list sorting test"
1793 depends on DEBUG_KERNEL || m
1795 Enable this to turn on 'list_sort()' function test. This test is
1796 executed only once during system boot (so affects only boot time),
1797 or at module load time.
1801 config TEST_MIN_HEAP
1802 tristate "Min heap test"
1803 depends on DEBUG_KERNEL || m
1805 Enable this to turn on min heap function tests. This test is
1806 executed only once during system boot (so affects only boot time),
1807 or at module load time.
1812 tristate "Array-based sort test"
1813 depends on DEBUG_KERNEL || m
1815 This option enables the self-test function of 'sort()' at boot,
1816 or at module load time.
1820 config KPROBES_SANITY_TEST
1821 bool "Kprobes sanity tests"
1822 depends on DEBUG_KERNEL
1825 This option provides for testing basic kprobes functionality on
1826 boot. Samples of kprobe and kretprobe are inserted and
1827 verified for functionality.
1829 Say N if you are unsure.
1831 config BACKTRACE_SELF_TEST
1832 tristate "Self test for the backtrace code"
1833 depends on DEBUG_KERNEL
1835 This option provides a kernel module that can be used to test
1836 the kernel stack backtrace code. This option is not useful
1837 for distributions or general kernels, but only for kernel
1838 developers working on architecture code.
1840 Note that if you want to also test saved backtraces, you will
1841 have to enable STACKTRACE as well.
1843 Say N if you are unsure.
1846 tristate "Red-Black tree test"
1847 depends on DEBUG_KERNEL
1849 A benchmark measuring the performance of the rbtree library.
1850 Also includes rbtree invariant checks.
1852 config REED_SOLOMON_TEST
1853 tristate "Reed-Solomon library test"
1854 depends on DEBUG_KERNEL || m
1856 select REED_SOLOMON_ENC16
1857 select REED_SOLOMON_DEC16
1859 This option enables the self-test function of rslib at boot,
1860 or at module load time.
1864 config INTERVAL_TREE_TEST
1865 tristate "Interval tree test"
1866 depends on DEBUG_KERNEL
1867 select INTERVAL_TREE
1869 A benchmark measuring the performance of the interval tree library
1872 tristate "Per cpu operations test"
1873 depends on m && DEBUG_KERNEL
1875 Enable this option to build test module which validates per-cpu
1880 config ATOMIC64_SELFTEST
1881 tristate "Perform an atomic64_t self-test"
1883 Enable this option to test the atomic64_t functions at boot or
1884 at module load time.
1888 config ASYNC_RAID6_TEST
1889 tristate "Self test for hardware accelerated raid6 recovery"
1890 depends on ASYNC_RAID6_RECOV
1893 This is a one-shot self test that permutes through the
1894 recovery of all the possible two disk failure scenarios for a
1895 N-disk array. Recovery is performed with the asynchronous
1896 raid6 recovery routines, and will optionally use an offload
1897 engine if one is available.
1902 tristate "Test functions located in the hexdump module at runtime"
1904 config TEST_STRING_HELPERS
1905 tristate "Test functions located in the string_helpers module at runtime"
1908 tristate "Test strscpy*() family of functions at runtime"
1911 tristate "Test kstrto*() family of functions at runtime"
1914 tristate "Test printf() family of functions at runtime"
1917 tristate "Test bitmap_*() family of functions at runtime"
1919 Enable this option to test the bitmap functions at boot.
1923 config TEST_BITFIELD
1924 tristate "Test bitfield functions at runtime"
1926 Enable this option to test the bitfield functions at boot.
1931 tristate "Test functions located in the uuid module at runtime"
1934 tristate "Test the XArray code at runtime"
1936 config TEST_OVERFLOW
1937 tristate "Test check_*_overflow() functions at runtime"
1939 config TEST_RHASHTABLE
1940 tristate "Perform selftest on resizable hash table"
1942 Enable this option to test the rhashtable functions at boot.
1947 tristate "Perform selftest on hash functions"
1949 Enable this option to test the kernel's integer (<linux/hash.h>),
1950 string (<linux/stringhash.h>), and siphash (<linux/siphash.h>)
1951 hash functions on boot (or module load).
1953 This is intended to help people writing architecture-specific
1954 optimized versions. If unsure, say N.
1957 tristate "Perform selftest on IDA functions"
1960 tristate "Perform selftest on priority array manager"
1963 Enable this option to test priority array manager on boot
1968 config TEST_IRQ_TIMINGS
1969 bool "IRQ timings selftest"
1970 depends on IRQ_TIMINGS
1972 Enable this option to test the irq timings code on boot.
1977 tristate "Test module loading with 'hello world' module"
1980 This builds the "test_module" module that emits "Hello, world"
1981 on printk when loaded. It is designed to be used for basic
1982 evaluation of the module loading subsystem (for example when
1983 validating module verification). It lacks any extra dependencies,
1984 and will not normally be loaded by the system unless explicitly
1990 tristate "Test module for stress/performance analysis of vmalloc allocator"
1995 This builds the "test_vmalloc" module that should be used for
1996 stress and performance analysis. So, any new change for vmalloc
1997 subsystem can be evaluated from performance and stability point
2002 config TEST_USER_COPY
2003 tristate "Test user/kernel boundary protections"
2006 This builds the "test_user_copy" module that runs sanity checks
2007 on the copy_to/from_user infrastructure, making sure basic
2008 user/kernel boundary testing is working. If it fails to load,
2009 a regression has been detected in the user/kernel memory boundary
2015 tristate "Test BPF filter functionality"
2018 This builds the "test_bpf" module that runs various test vectors
2019 against the BPF interpreter or BPF JIT compiler depending on the
2020 current setting. This is in particular useful for BPF JIT compiler
2021 development, but also to run regression tests against changes in
2022 the interpreter code. It also enables test stubs for eBPF maps and
2023 verifier used by user space verifier testsuite.
2027 config TEST_BLACKHOLE_DEV
2028 tristate "Test blackhole netdev functionality"
2031 This builds the "test_blackhole_dev" module that validates the
2032 data path through this blackhole netdev.
2036 config FIND_BIT_BENCHMARK
2037 tristate "Test find_bit functions"
2039 This builds the "test_find_bit" module that measure find_*_bit()
2040 functions performance.
2044 config TEST_FIRMWARE
2045 tristate "Test firmware loading via userspace interface"
2046 depends on FW_LOADER
2048 This builds the "test_firmware" module that creates a userspace
2049 interface for testing firmware loading. This can be used to
2050 control the triggering of firmware loading without needing an
2051 actual firmware-using device. The contents can be rechecked by
2057 tristate "sysctl test driver"
2058 depends on PROC_SYSCTL
2060 This builds the "test_sysctl" module. This driver enables to test the
2061 proc sysctl interfaces available to drivers safely without affecting
2062 production knobs which might alter system functionality.
2066 config SYSCTL_KUNIT_TEST
2067 tristate "KUnit test for sysctl"
2070 This builds the proc sysctl unit test, which runs on boot.
2071 Tests the API contract and implementation correctness of sysctl.
2072 For more information on KUnit and unit tests in general please refer
2073 to the KUnit documentation in Documentation/dev-tools/kunit/.
2077 config LIST_KUNIT_TEST
2078 tristate "KUnit Test for Kernel Linked-list structures"
2081 This builds the linked list KUnit test suite.
2082 It tests that the API and basic functionality of the list_head type
2083 and associated macros.
2085 KUnit tests run during boot and output the results to the debug log
2086 in TAP format (http://testanything.org/). Only useful for kernel devs
2087 running the KUnit test harness, and not intended for inclusion into a
2090 For more information on KUnit and unit tests in general please refer
2091 to the KUnit documentation in Documentation/dev-tools/kunit/.
2095 config LINEAR_RANGES_TEST
2096 tristate "KUnit test for linear_ranges"
2098 select LINEAR_RANGES
2100 This builds the linear_ranges unit test, which runs on boot.
2101 Tests the linear_ranges logic correctness.
2102 For more information on KUnit and unit tests in general please refer
2103 to the KUnit documentation in Documentation/dev-tools/kunit/.
2108 tristate "udelay test driver"
2110 This builds the "udelay_test" module that helps to make sure
2111 that udelay() is working properly.
2115 config TEST_STATIC_KEYS
2116 tristate "Test static keys"
2119 Test the static key interfaces.
2124 tristate "kmod stress tester"
2126 depends on NETDEVICES && NET_CORE && INET # for TUN
2133 Test the kernel's module loading mechanism: kmod. kmod implements
2134 support to load modules using the Linux kernel's usermode helper.
2135 This test provides a series of tests against kmod.
2137 Although technically you can either build test_kmod as a module or
2138 into the kernel we disallow building it into the kernel since
2139 it stress tests request_module() and this will very likely cause
2140 some issues by taking over precious threads available from other
2141 module load requests, ultimately this could be fatal.
2145 tools/testing/selftests/kmod/kmod.sh --help
2149 config TEST_DEBUG_VIRTUAL
2150 tristate "Test CONFIG_DEBUG_VIRTUAL feature"
2151 depends on DEBUG_VIRTUAL
2153 Test the kernel's ability to detect incorrect calls to
2154 virt_to_phys() done against the non-linear part of the
2155 kernel's virtual address map.
2159 config TEST_MEMCAT_P
2160 tristate "Test memcat_p() helper function"
2162 Test the memcat_p() helper for correctly merging two
2163 pointer arrays together.
2167 config TEST_LIVEPATCH
2168 tristate "Test livepatching"
2170 depends on DYNAMIC_DEBUG
2171 depends on LIVEPATCH
2174 Test kernel livepatching features for correctness. The tests will
2175 load test modules that will be livepatched in various scenarios.
2177 To run all the livepatching tests:
2179 make -C tools/testing/selftests TARGETS=livepatch run_tests
2181 Alternatively, individual tests may be invoked:
2183 tools/testing/selftests/livepatch/test-callbacks.sh
2184 tools/testing/selftests/livepatch/test-livepatch.sh
2185 tools/testing/selftests/livepatch/test-shadow-vars.sh
2190 tristate "Perform selftest on object aggreration manager"
2194 Enable this option to test object aggregation manager on boot
2198 config TEST_STACKINIT
2199 tristate "Test level of stack variable initialization"
2201 Test if the kernel is zero-initializing stack variables and
2202 padding. Coverage is controlled by compiler flags,
2203 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2204 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2209 tristate "Test heap/page initialization"
2211 Test if the kernel is zero-initializing heap and page allocations.
2212 This can be useful to test init_on_alloc and init_on_free features.
2216 endif # RUNTIME_TESTING_MENU
2221 This option adds a kernel parameter 'memtest', which allows memtest
2223 memtest=0, mean disabled; -- default
2224 memtest=1, mean do 1 test pattern;
2226 memtest=17, mean do 17 test patterns.
2227 If you are unsure how to answer this question, answer N.
2231 config HYPERV_TESTING
2232 bool "Microsoft Hyper-V driver testing"
2234 depends on HYPERV && DEBUG_FS
2236 Select this option to enable Hyper-V vmbus testing.
2238 endmenu # "Kernel Testing and Coverage"
2240 endmenu # Kernel hacking
projects / linux-2.6-microblaze.git / blob