Version:  2.0.40 2.2.26 2.4.37 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8

Linux/lib/Kconfig.debug

  1 menu "printk and dmesg options"
  2 
  3 config PRINTK_TIME
  4         bool "Show timing information on printks"
  5         depends on PRINTK
  6         help
  7           Selecting this option causes time stamps of the printk()
  8           messages to be added to the output of the syslog() system
  9           call and at the console.
 10 
 11           The timestamp is always recorded internally, and exported
 12           to /dev/kmsg. This flag just specifies if the timestamp should
 13           be included, not that the timestamp is recorded.
 14 
 15           The behavior is also controlled by the kernel command line
 16           parameter printk.time=1. See Documentation/kernel-parameters.txt
 17 
 18 config MESSAGE_LOGLEVEL_DEFAULT
 19         int "Default message log level (1-7)"
 20         range 1 7
 21         default "4"
 22         help
 23           Default log level for printk statements with no specified priority.
 24 
 25           This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
 26           that are auditing their logs closely may want to set it to a lower
 27           priority.
 28 
 29 config BOOT_PRINTK_DELAY
 30         bool "Delay each boot printk message by N milliseconds"
 31         depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
 32         help
 33           This build option allows you to read kernel boot messages
 34           by inserting a short delay after each one.  The delay is
 35           specified in milliseconds on the kernel command line,
 36           using "boot_delay=N".
 37 
 38           It is likely that you would also need to use "lpj=M" to preset
 39           the "loops per jiffie" value.
 40           See a previous boot log for the "lpj" value to use for your
 41           system, and then set "lpj=M" before setting "boot_delay=N".
 42           NOTE:  Using this option may adversely affect SMP systems.
 43           I.e., processors other than the first one may not boot up.
 44           BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
 45           what it believes to be lockup conditions.
 46 
 47 config DYNAMIC_DEBUG
 48         bool "Enable dynamic printk() support"
 49         default n
 50         depends on PRINTK
 51         depends on DEBUG_FS
 52         help
 53 
 54           Compiles debug level messages into the kernel, which would not
 55           otherwise be available at runtime. These messages can then be
 56           enabled/disabled based on various levels of scope - per source file,
 57           function, module, format string, and line number. This mechanism
 58           implicitly compiles in all pr_debug() and dev_dbg() calls, which
 59           enlarges the kernel text size by about 2%.
 60 
 61           If a source file is compiled with DEBUG flag set, any
 62           pr_debug() calls in it are enabled by default, but can be
 63           disabled at runtime as below.  Note that DEBUG flag is
 64           turned on by many CONFIG_*DEBUG* options.
 65 
 66           Usage:
 67 
 68           Dynamic debugging is controlled via the 'dynamic_debug/control' file,
 69           which is contained in the 'debugfs' filesystem. Thus, the debugfs
 70           filesystem must first be mounted before making use of this feature.
 71           We refer the control file as: <debugfs>/dynamic_debug/control. This
 72           file contains a list of the debug statements that can be enabled. The
 73           format for each line of the file is:
 74 
 75                 filename:lineno [module]function flags format
 76 
 77           filename : source file of the debug statement
 78           lineno : line number of the debug statement
 79           module : module that contains the debug statement
 80           function : function that contains the debug statement
 81           flags : '=p' means the line is turned 'on' for printing
 82           format : the format used for the debug statement
 83 
 84           From a live system:
 85 
 86                 nullarbor:~ # cat <debugfs>/dynamic_debug/control
 87                 # filename:lineno [module]function flags format
 88                 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
 89                 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
 90                 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
 91 
 92           Example usage:
 93 
 94                 // enable the message at line 1603 of file svcsock.c
 95                 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
 96                                                 <debugfs>/dynamic_debug/control
 97 
 98                 // enable all the messages in file svcsock.c
 99                 nullarbor:~ # echo -n 'file svcsock.c +p' >
100                                                 <debugfs>/dynamic_debug/control
101 
102                 // enable all the messages in the NFS server module
103                 nullarbor:~ # echo -n 'module nfsd +p' >
104                                                 <debugfs>/dynamic_debug/control
105 
106                 // enable all 12 messages in the function svc_process()
107                 nullarbor:~ # echo -n 'func svc_process +p' >
108                                                 <debugfs>/dynamic_debug/control
109 
110                 // disable all 12 messages in the function svc_process()
111                 nullarbor:~ # echo -n 'func svc_process -p' >
112                                                 <debugfs>/dynamic_debug/control
113 
114           See Documentation/dynamic-debug-howto.txt for additional information.
115 
116 endmenu # "printk and dmesg options"
117 
118 menu "Compile-time checks and compiler options"
119 
120 config DEBUG_INFO
121         bool "Compile the kernel with debug info"
122         depends on DEBUG_KERNEL && !COMPILE_TEST
123         help
124           If you say Y here the resulting kernel image will include
125           debugging info resulting in a larger kernel image.
126           This adds debug symbols to the kernel and modules (gcc -g), and
127           is needed if you intend to use kernel crashdump or binary object
128           tools like crash, kgdb, LKCD, gdb, etc on the kernel.
129           Say Y here only if you plan to debug the kernel.
130 
131           If unsure, say N.
132 
133 config DEBUG_INFO_REDUCED
134         bool "Reduce debugging information"
135         depends on DEBUG_INFO
136         help
137           If you say Y here gcc is instructed to generate less debugging
138           information for structure types. This means that tools that
139           need full debugging information (like kgdb or systemtap) won't
140           be happy. But if you merely need debugging information to
141           resolve line numbers there is no loss. Advantage is that
142           build directory object sizes shrink dramatically over a full
143           DEBUG_INFO build and compile times are reduced too.
144           Only works with newer gcc versions.
145 
146 config DEBUG_INFO_SPLIT
147         bool "Produce split debuginfo in .dwo files"
148         depends on DEBUG_INFO
149         help
150           Generate debug info into separate .dwo files. This significantly
151           reduces the build directory size for builds with DEBUG_INFO,
152           because it stores the information only once on disk in .dwo
153           files instead of multiple times in object files and executables.
154           In addition the debug information is also compressed.
155 
156           Requires recent gcc (4.7+) and recent gdb/binutils.
157           Any tool that packages or reads debug information would need
158           to know about the .dwo files and include them.
159           Incompatible with older versions of ccache.
160 
161 config DEBUG_INFO_DWARF4
162         bool "Generate dwarf4 debuginfo"
163         depends on DEBUG_INFO
164         help
165           Generate dwarf4 debug info. This requires recent versions
166           of gcc and gdb. It makes the debug information larger.
167           But it significantly improves the success of resolving
168           variables in gdb on optimized code.
169 
170 config GDB_SCRIPTS
171         bool "Provide GDB scripts for kernel debugging"
172         depends on DEBUG_INFO
173         help
174           This creates the required links to GDB helper scripts in the
175           build directory. If you load vmlinux into gdb, the helper
176           scripts will be automatically imported by gdb as well, and
177           additional functions are available to analyze a Linux kernel
178           instance. See Documentation/gdb-kernel-debugging.txt for further
179           details.
180 
181 config ENABLE_WARN_DEPRECATED
182         bool "Enable __deprecated logic"
183         default y
184         help
185           Enable the __deprecated logic in the kernel build.
186           Disable this to suppress the "warning: 'foo' is deprecated
187           (declared at kernel/power/somefile.c:1234)" messages.
188 
189 config ENABLE_MUST_CHECK
190         bool "Enable __must_check logic"
191         default y
192         help
193           Enable the __must_check logic in the kernel build.  Disable this to
194           suppress the "warning: ignoring return value of 'foo', declared with
195           attribute warn_unused_result" messages.
196 
197 config FRAME_WARN
198         int "Warn for stack frames larger than (needs gcc 4.4)"
199         range 0 8192
200         default 0 if KASAN
201         default 1024 if !64BIT
202         default 2048 if 64BIT
203         help
204           Tell gcc to warn at build time for stack frames larger than this.
205           Setting this too low will cause a lot of warnings.
206           Setting it to 0 disables the warning.
207           Requires gcc 4.4
208 
209 config STRIP_ASM_SYMS
210         bool "Strip assembler-generated symbols during link"
211         default n
212         help
213           Strip internal assembler-generated symbols during a link (symbols
214           that look like '.Lxxx') so they don't pollute the output of
215           get_wchan() and suchlike.
216 
217 config READABLE_ASM
218         bool "Generate readable assembler code"
219         depends on DEBUG_KERNEL
220         help
221           Disable some compiler optimizations that tend to generate human unreadable
222           assembler output. This may make the kernel slightly slower, but it helps
223           to keep kernel developers who have to stare a lot at assembler listings
224           sane.
225 
226 config UNUSED_SYMBOLS
227         bool "Enable unused/obsolete exported symbols"
228         default y if X86
229         help
230           Unused but exported symbols make the kernel needlessly bigger.  For
231           that reason most of these unused exports will soon be removed.  This
232           option is provided temporarily to provide a transition period in case
233           some external kernel module needs one of these symbols anyway. If you
234           encounter such a case in your module, consider if you are actually
235           using the right API.  (rationale: since nobody in the kernel is using
236           this in a module, there is a pretty good chance it's actually the
237           wrong interface to use).  If you really need the symbol, please send a
238           mail to the linux kernel mailing list mentioning the symbol and why
239           you really need it, and what the merge plan to the mainline kernel for
240           your module is.
241 
242 config PAGE_OWNER
243         bool "Track page owner"
244         depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
245         select DEBUG_FS
246         select STACKTRACE
247         select STACKDEPOT
248         select PAGE_EXTENSION
249         help
250           This keeps track of what call chain is the owner of a page, may
251           help to find bare alloc_page(s) leaks. Even if you include this
252           feature on your build, it is disabled in default. You should pass
253           "page_owner=on" to boot parameter in order to enable it. Eats
254           a fair amount of memory if enabled. See tools/vm/page_owner_sort.c
255           for user-space helper.
256 
257           If unsure, say N.
258 
259 config DEBUG_FS
260         bool "Debug Filesystem"
261         select SRCU
262         help
263           debugfs is a virtual file system that kernel developers use to put
264           debugging files into.  Enable this option to be able to read and
265           write to these files.
266 
267           For detailed documentation on the debugfs API, see
268           Documentation/DocBook/filesystems.
269 
270           If unsure, say N.
271 
272 config HEADERS_CHECK
273         bool "Run 'make headers_check' when building vmlinux"
274         depends on !UML
275         help
276           This option will extract the user-visible kernel headers whenever
277           building the kernel, and will run basic sanity checks on them to
278           ensure that exported files do not attempt to include files which
279           were not exported, etc.
280 
281           If you're making modifications to header files which are
282           relevant for userspace, say 'Y', and check the headers
283           exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
284           your build tree), to make sure they're suitable.
285 
286 config DEBUG_SECTION_MISMATCH
287         bool "Enable full Section mismatch analysis"
288         help
289           The section mismatch analysis checks if there are illegal
290           references from one section to another section.
291           During linktime or runtime, some sections are dropped;
292           any use of code/data previously in these sections would
293           most likely result in an oops.
294           In the code, functions and variables are annotated with
295           __init,, etc. (see the full list in include/linux/init.h),
296           which results in the code/data being placed in specific sections.
297           The section mismatch analysis is always performed after a full
298           kernel build, and enabling this option causes the following
299           additional steps to occur:
300           - Add the option -fno-inline-functions-called-once to gcc commands.
301             When inlining a function annotated with __init in a non-init
302             function, we would lose the section information and thus
303             the analysis would not catch the illegal reference.
304             This option tells gcc to inline less (but it does result in
305             a larger kernel).
306           - Run the section mismatch analysis for each module/built-in.o file.
307             When we run the section mismatch analysis on vmlinux.o, we
308             lose valueble information about where the mismatch was
309             introduced.
310             Running the analysis for each module/built-in.o file
311             tells where the mismatch happens much closer to the
312             source. The drawback is that the same mismatch is
313             reported at least twice.
314           - Enable verbose reporting from modpost in order to help resolve
315             the section mismatches that are reported.
316 
317 config SECTION_MISMATCH_WARN_ONLY
318         bool "Make section mismatch errors non-fatal"
319         default y
320         help
321           If you say N here, the build process will fail if there are any
322           section mismatch, instead of just throwing warnings.
323 
324           If unsure, say Y.
325 
326 #
327 # Select this config option from the architecture Kconfig, if it
328 # is preferred to always offer frame pointers as a config
329 # option on the architecture (regardless of KERNEL_DEBUG):
330 #
331 config ARCH_WANT_FRAME_POINTERS
332         bool
333         help
334 
335 config FRAME_POINTER
336         bool "Compile the kernel with frame pointers"
337         depends on DEBUG_KERNEL && \
338                 (CRIS || M68K || FRV || UML || \
339                  AVR32 || SUPERH || BLACKFIN || MN10300 || METAG) || \
340                 ARCH_WANT_FRAME_POINTERS
341         default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
342         help
343           If you say Y here the resulting kernel image will be slightly
344           larger and slower, but it gives very useful debugging information
345           in case of kernel bugs. (precise oopses/stacktraces/warnings)
346 
347 config STACK_VALIDATION
348         bool "Compile-time stack metadata validation"
349         depends on HAVE_STACK_VALIDATION
350         default n
351         help
352           Add compile-time checks to validate stack metadata, including frame
353           pointers (if CONFIG_FRAME_POINTER is enabled).  This helps ensure
354           that runtime stack traces are more reliable.
355 
356           For more information, see
357           tools/objtool/Documentation/stack-validation.txt.
358 
359 config DEBUG_FORCE_WEAK_PER_CPU
360         bool "Force weak per-cpu definitions"
361         depends on DEBUG_KERNEL
362         help
363           s390 and alpha require percpu variables in modules to be
364           defined weak to work around addressing range issue which
365           puts the following two restrictions on percpu variable
366           definitions.
367 
368           1. percpu symbols must be unique whether static or not
369           2. percpu variables can't be defined inside a function
370 
371           To ensure that generic code follows the above rules, this
372           option forces all percpu variables to be defined as weak.
373 
374 endmenu # "Compiler options"
375 
376 config MAGIC_SYSRQ
377         bool "Magic SysRq key"
378         depends on !UML
379         help
380           If you say Y here, you will have some control over the system even
381           if the system crashes for example during kernel debugging (e.g., you
382           will be able to flush the buffer cache to disk, reboot the system
383           immediately or dump some status information). This is accomplished
384           by pressing various keys while holding SysRq (Alt+PrintScreen). It
385           also works on a serial console (on PC hardware at least), if you
386           send a BREAK and then within 5 seconds a command keypress. The
387           keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
388           unless you really know what this hack does.
389 
390 config MAGIC_SYSRQ_DEFAULT_ENABLE
391         hex "Enable magic SysRq key functions by default"
392         depends on MAGIC_SYSRQ
393         default 0x1
394         help
395           Specifies which SysRq key functions are enabled by default.
396           This may be set to 1 or 0 to enable or disable them all, or
397           to a bitmask as described in Documentation/sysrq.txt.
398 
399 config DEBUG_KERNEL
400         bool "Kernel debugging"
401         help
402           Say Y here if you are developing drivers or trying to debug and
403           identify kernel problems.
404 
405 menu "Memory Debugging"
406 
407 source mm/Kconfig.debug
408 
409 config DEBUG_OBJECTS
410         bool "Debug object operations"
411         depends on DEBUG_KERNEL
412         help
413           If you say Y here, additional code will be inserted into the
414           kernel to track the life time of various objects and validate
415           the operations on those objects.
416 
417 config DEBUG_OBJECTS_SELFTEST
418         bool "Debug objects selftest"
419         depends on DEBUG_OBJECTS
420         help
421           This enables the selftest of the object debug code.
422 
423 config DEBUG_OBJECTS_FREE
424         bool "Debug objects in freed memory"
425         depends on DEBUG_OBJECTS
426         help
427           This enables checks whether a k/v free operation frees an area
428           which contains an object which has not been deactivated
429           properly. This can make kmalloc/kfree-intensive workloads
430           much slower.
431 
432 config DEBUG_OBJECTS_TIMERS
433         bool "Debug timer objects"
434         depends on DEBUG_OBJECTS
435         help
436           If you say Y here, additional code will be inserted into the
437           timer routines to track the life time of timer objects and
438           validate the timer operations.
439 
440 config DEBUG_OBJECTS_WORK
441         bool "Debug work objects"
442         depends on DEBUG_OBJECTS
443         help
444           If you say Y here, additional code will be inserted into the
445           work queue routines to track the life time of work objects and
446           validate the work operations.
447 
448 config DEBUG_OBJECTS_RCU_HEAD
449         bool "Debug RCU callbacks objects"
450         depends on DEBUG_OBJECTS
451         help
452           Enable this to turn on debugging of RCU list heads (call_rcu() usage).
453 
454 config DEBUG_OBJECTS_PERCPU_COUNTER
455         bool "Debug percpu counter objects"
456         depends on DEBUG_OBJECTS
457         help
458           If you say Y here, additional code will be inserted into the
459           percpu counter routines to track the life time of percpu counter
460           objects and validate the percpu counter operations.
461 
462 config DEBUG_OBJECTS_ENABLE_DEFAULT
463         int "debug_objects bootup default value (0-1)"
464         range 0 1
465         default "1"
466         depends on DEBUG_OBJECTS
467         help
468           Debug objects boot parameter default value
469 
470 config DEBUG_SLAB
471         bool "Debug slab memory allocations"
472         depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
473         help
474           Say Y here to have the kernel do limited verification on memory
475           allocation as well as poisoning memory on free to catch use of freed
476           memory. This can make kmalloc/kfree-intensive workloads much slower.
477 
478 config DEBUG_SLAB_LEAK
479         bool "Memory leak debugging"
480         depends on DEBUG_SLAB
481 
482 config SLUB_DEBUG_ON
483         bool "SLUB debugging on by default"
484         depends on SLUB && SLUB_DEBUG && !KMEMCHECK
485         default n
486         help
487           Boot with debugging on by default. SLUB boots by default with
488           the runtime debug capabilities switched off. Enabling this is
489           equivalent to specifying the "slub_debug" parameter on boot.
490           There is no support for more fine grained debug control like
491           possible with slub_debug=xxx. SLUB debugging may be switched
492           off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
493           "slub_debug=-".
494 
495 config SLUB_STATS
496         default n
497         bool "Enable SLUB performance statistics"
498         depends on SLUB && SYSFS
499         help
500           SLUB statistics are useful to debug SLUBs allocation behavior in
501           order find ways to optimize the allocator. This should never be
502           enabled for production use since keeping statistics slows down
503           the allocator by a few percentage points. The slabinfo command
504           supports the determination of the most active slabs to figure
505           out which slabs are relevant to a particular load.
506           Try running: slabinfo -DA
507 
508 config HAVE_DEBUG_KMEMLEAK
509         bool
510 
511 config DEBUG_KMEMLEAK
512         bool "Kernel memory leak detector"
513         depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
514         select DEBUG_FS
515         select STACKTRACE if STACKTRACE_SUPPORT
516         select KALLSYMS
517         select CRC32
518         help
519           Say Y here if you want to enable the memory leak
520           detector. The memory allocation/freeing is traced in a way
521           similar to the Boehm's conservative garbage collector, the
522           difference being that the orphan objects are not freed but
523           only shown in /sys/kernel/debug/kmemleak. Enabling this
524           feature will introduce an overhead to memory
525           allocations. See Documentation/kmemleak.txt for more
526           details.
527 
528           Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
529           of finding leaks due to the slab objects poisoning.
530 
531           In order to access the kmemleak file, debugfs needs to be
532           mounted (usually at /sys/kernel/debug).
533 
534 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
535         int "Maximum kmemleak early log entries"
536         depends on DEBUG_KMEMLEAK
537         range 200 40000
538         default 400
539         help
540           Kmemleak must track all the memory allocations to avoid
541           reporting false positives. Since memory may be allocated or
542           freed before kmemleak is initialised, an early log buffer is
543           used to store these actions. If kmemleak reports "early log
544           buffer exceeded", please increase this value.
545 
546 config DEBUG_KMEMLEAK_TEST
547         tristate "Simple test for the kernel memory leak detector"
548         depends on DEBUG_KMEMLEAK && m
549         help
550           This option enables a module that explicitly leaks memory.
551 
552           If unsure, say N.
553 
554 config DEBUG_KMEMLEAK_DEFAULT_OFF
555         bool "Default kmemleak to off"
556         depends on DEBUG_KMEMLEAK
557         help
558           Say Y here to disable kmemleak by default. It can then be enabled
559           on the command line via kmemleak=on.
560 
561 config DEBUG_STACK_USAGE
562         bool "Stack utilization instrumentation"
563         depends on DEBUG_KERNEL && !IA64
564         help
565           Enables the display of the minimum amount of free stack which each
566           task has ever had available in the sysrq-T and sysrq-P debug output.
567 
568           This option will slow down process creation somewhat.
569 
570 config DEBUG_VM
571         bool "Debug VM"
572         depends on DEBUG_KERNEL
573         help
574           Enable this to turn on extended checks in the virtual-memory system
575           that may impact performance.
576 
577           If unsure, say N.
578 
579 config DEBUG_VM_VMACACHE
580         bool "Debug VMA caching"
581         depends on DEBUG_VM
582         help
583           Enable this to turn on VMA caching debug information. Doing so
584           can cause significant overhead, so only enable it in non-production
585           environments.
586 
587           If unsure, say N.
588 
589 config DEBUG_VM_RB
590         bool "Debug VM red-black trees"
591         depends on DEBUG_VM
592         help
593           Enable VM red-black tree debugging information and extra validations.
594 
595           If unsure, say N.
596 
597 config DEBUG_VM_PGFLAGS
598         bool "Debug page-flags operations"
599         depends on DEBUG_VM
600         help
601           Enables extra validation on page flags operations.
602 
603           If unsure, say N.
604 
605 config DEBUG_VIRTUAL
606         bool "Debug VM translations"
607         depends on DEBUG_KERNEL && X86
608         help
609           Enable some costly sanity checks in virtual to page code. This can
610           catch mistakes with virt_to_page() and friends.
611 
612           If unsure, say N.
613 
614 config DEBUG_NOMMU_REGIONS
615         bool "Debug the global anon/private NOMMU mapping region tree"
616         depends on DEBUG_KERNEL && !MMU
617         help
618           This option causes the global tree of anonymous and private mapping
619           regions to be regularly checked for invalid topology.
620 
621 config DEBUG_MEMORY_INIT
622         bool "Debug memory initialisation" if EXPERT
623         default !EXPERT
624         help
625           Enable this for additional checks during memory initialisation.
626           The sanity checks verify aspects of the VM such as the memory model
627           and other information provided by the architecture. Verbose
628           information will be printed at KERN_DEBUG loglevel depending
629           on the mminit_loglevel= command-line option.
630 
631           If unsure, say Y
632 
633 config MEMORY_NOTIFIER_ERROR_INJECT
634         tristate "Memory hotplug notifier error injection module"
635         depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
636         help
637           This option provides the ability to inject artificial errors to
638           memory hotplug notifier chain callbacks.  It is controlled through
639           debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
640 
641           If the notifier call chain should be failed with some events
642           notified, write the error code to "actions/<notifier event>/error".
643 
644           Example: Inject memory hotplug offline error (-12 == -ENOMEM)
645 
646           # cd /sys/kernel/debug/notifier-error-inject/memory
647           # echo -12 > actions/MEM_GOING_OFFLINE/error
648           # echo offline > /sys/devices/system/memory/memoryXXX/state
649           bash: echo: write error: Cannot allocate memory
650 
651           To compile this code as a module, choose M here: the module will
652           be called memory-notifier-error-inject.
653 
654           If unsure, say N.
655 
656 config DEBUG_PER_CPU_MAPS
657         bool "Debug access to per_cpu maps"
658         depends on DEBUG_KERNEL
659         depends on SMP
660         help
661           Say Y to verify that the per_cpu map being accessed has
662           been set up. This adds a fair amount of code to kernel memory
663           and decreases performance.
664 
665           Say N if unsure.
666 
667 config DEBUG_HIGHMEM
668         bool "Highmem debugging"
669         depends on DEBUG_KERNEL && HIGHMEM
670         help
671           This option enables additional error checking for high memory
672           systems.  Disable for production systems.
673 
674 config HAVE_DEBUG_STACKOVERFLOW
675         bool
676 
677 config DEBUG_STACKOVERFLOW
678         bool "Check for stack overflows"
679         depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
680         ---help---
681           Say Y here if you want to check for overflows of kernel, IRQ
682           and exception stacks (if your architecture uses them). This
683           option will show detailed messages if free stack space drops
684           below a certain limit.
685 
686           These kinds of bugs usually occur when call-chains in the
687           kernel get too deep, especially when interrupts are
688           involved.
689 
690           Use this in cases where you see apparently random memory
691           corruption, especially if it appears in 'struct thread_info'
692 
693           If in doubt, say "N".
694 
695 source "lib/Kconfig.kmemcheck"
696 
697 source "lib/Kconfig.kasan"
698 
699 endmenu # "Memory Debugging"
700 
701 config ARCH_HAS_KCOV
702         bool
703         help
704           KCOV does not have any arch-specific code, but currently it is enabled
705           only for x86_64. KCOV requires testing on other archs, and most likely
706           disabling of instrumentation for some early boot code.
707 
708 config KCOV
709         bool "Code coverage for fuzzing"
710         depends on ARCH_HAS_KCOV
711         select DEBUG_FS
712         select GCC_PLUGINS if !COMPILE_TEST
713         select GCC_PLUGIN_SANCOV if !COMPILE_TEST
714         help
715           KCOV exposes kernel code coverage information in a form suitable
716           for coverage-guided fuzzing (randomized testing).
717 
718           If RANDOMIZE_BASE is enabled, PC values will not be stable across
719           different machines and across reboots. If you need stable PC values,
720           disable RANDOMIZE_BASE.
721 
722           For more details, see Documentation/kcov.txt.
723 
724 config KCOV_INSTRUMENT_ALL
725         bool "Instrument all code by default"
726         depends on KCOV
727         default y if KCOV
728         help
729           If you are doing generic system call fuzzing (like e.g. syzkaller),
730           then you will want to instrument the whole kernel and you should
731           say y here. If you are doing more targeted fuzzing (like e.g.
732           filesystem fuzzing with AFL) then you will want to enable coverage
733           for more specific subsets of files, and should say n here.
734 
735 config DEBUG_SHIRQ
736         bool "Debug shared IRQ handlers"
737         depends on DEBUG_KERNEL
738         help
739           Enable this to generate a spurious interrupt as soon as a shared
740           interrupt handler is registered, and just before one is deregistered.
741           Drivers ought to be able to handle interrupts coming in at those
742           points; some don't and need to be caught.
743 
744 menu "Debug Lockups and Hangs"
745 
746 config LOCKUP_DETECTOR
747         bool "Detect Hard and Soft Lockups"
748         depends on DEBUG_KERNEL && !S390
749         help
750           Say Y here to enable the kernel to act as a watchdog to detect
751           hard and soft lockups.
752 
753           Softlockups are bugs that cause the kernel to loop in kernel
754           mode for more than 20 seconds, without giving other tasks a
755           chance to run.  The current stack trace is displayed upon
756           detection and the system will stay locked up.
757 
758           Hardlockups are bugs that cause the CPU to loop in kernel mode
759           for more than 10 seconds, without letting other interrupts have a
760           chance to run.  The current stack trace is displayed upon detection
761           and the system will stay locked up.
762 
763           The overhead should be minimal.  A periodic hrtimer runs to
764           generate interrupts and kick the watchdog task every 4 seconds.
765           An NMI is generated every 10 seconds or so to check for hardlockups.
766 
767           The frequency of hrtimer and NMI events and the soft and hard lockup
768           thresholds can be controlled through the sysctl watchdog_thresh.
769 
770 config HARDLOCKUP_DETECTOR
771         def_bool y
772         depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
773         depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
774 
775 config BOOTPARAM_HARDLOCKUP_PANIC
776         bool "Panic (Reboot) On Hard Lockups"
777         depends on HARDLOCKUP_DETECTOR
778         help
779           Say Y here to enable the kernel to panic on "hard lockups",
780           which are bugs that cause the kernel to loop in kernel
781           mode with interrupts disabled for more than 10 seconds (configurable
782           using the watchdog_thresh sysctl).
783 
784           Say N if unsure.
785 
786 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
787         int
788         depends on HARDLOCKUP_DETECTOR
789         range 0 1
790         default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
791         default 1 if BOOTPARAM_HARDLOCKUP_PANIC
792 
793 config BOOTPARAM_SOFTLOCKUP_PANIC
794         bool "Panic (Reboot) On Soft Lockups"
795         depends on LOCKUP_DETECTOR
796         help
797           Say Y here to enable the kernel to panic on "soft lockups",
798           which are bugs that cause the kernel to loop in kernel
799           mode for more than 20 seconds (configurable using the watchdog_thresh
800           sysctl), without giving other tasks a chance to run.
801 
802           The panic can be used in combination with panic_timeout,
803           to cause the system to reboot automatically after a
804           lockup has been detected. This feature is useful for
805           high-availability systems that have uptime guarantees and
806           where a lockup must be resolved ASAP.
807 
808           Say N if unsure.
809 
810 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
811         int
812         depends on LOCKUP_DETECTOR
813         range 0 1
814         default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
815         default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
816 
817 config DETECT_HUNG_TASK
818         bool "Detect Hung Tasks"
819         depends on DEBUG_KERNEL
820         default LOCKUP_DETECTOR
821         help
822           Say Y here to enable the kernel to detect "hung tasks",
823           which are bugs that cause the task to be stuck in
824           uninterruptible "D" state indefinitely.
825 
826           When a hung task is detected, the kernel will print the
827           current stack trace (which you should report), but the
828           task will stay in uninterruptible state. If lockdep is
829           enabled then all held locks will also be reported. This
830           feature has negligible overhead.
831 
832 config DEFAULT_HUNG_TASK_TIMEOUT
833         int "Default timeout for hung task detection (in seconds)"
834         depends on DETECT_HUNG_TASK
835         default 120
836         help
837           This option controls the default timeout (in seconds) used
838           to determine when a task has become non-responsive and should
839           be considered hung.
840 
841           It can be adjusted at runtime via the kernel.hung_task_timeout_secs
842           sysctl or by writing a value to
843           /proc/sys/kernel/hung_task_timeout_secs.
844 
845           A timeout of 0 disables the check.  The default is two minutes.
846           Keeping the default should be fine in most cases.
847 
848 config BOOTPARAM_HUNG_TASK_PANIC
849         bool "Panic (Reboot) On Hung Tasks"
850         depends on DETECT_HUNG_TASK
851         help
852           Say Y here to enable the kernel to panic on "hung tasks",
853           which are bugs that cause the kernel to leave a task stuck
854           in uninterruptible "D" state.
855 
856           The panic can be used in combination with panic_timeout,
857           to cause the system to reboot automatically after a
858           hung task has been detected. This feature is useful for
859           high-availability systems that have uptime guarantees and
860           where a hung tasks must be resolved ASAP.
861 
862           Say N if unsure.
863 
864 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
865         int
866         depends on DETECT_HUNG_TASK
867         range 0 1
868         default 0 if !BOOTPARAM_HUNG_TASK_PANIC
869         default 1 if BOOTPARAM_HUNG_TASK_PANIC
870 
871 config WQ_WATCHDOG
872         bool "Detect Workqueue Stalls"
873         depends on DEBUG_KERNEL
874         help
875           Say Y here to enable stall detection on workqueues.  If a
876           worker pool doesn't make forward progress on a pending work
877           item for over a given amount of time, 30s by default, a
878           warning message is printed along with dump of workqueue
879           state.  This can be configured through kernel parameter
880           "workqueue.watchdog_thresh" and its sysfs counterpart.
881 
882 endmenu # "Debug lockups and hangs"
883 
884 config PANIC_ON_OOPS
885         bool "Panic on Oops"
886         help
887           Say Y here to enable the kernel to panic when it oopses. This
888           has the same effect as setting oops=panic on the kernel command
889           line.
890 
891           This feature is useful to ensure that the kernel does not do
892           anything erroneous after an oops which could result in data
893           corruption or other issues.
894 
895           Say N if unsure.
896 
897 config PANIC_ON_OOPS_VALUE
898         int
899         range 0 1
900         default 0 if !PANIC_ON_OOPS
901         default 1 if PANIC_ON_OOPS
902 
903 config PANIC_TIMEOUT
904         int "panic timeout"
905         default 0
906         help
907           Set the timeout value (in seconds) until a reboot occurs when the
908           the kernel panics. If n = 0, then we wait forever. A timeout
909           value n > 0 will wait n seconds before rebooting, while a timeout
910           value n < 0 will reboot immediately.
911 
912 config SCHED_DEBUG
913         bool "Collect scheduler debugging info"
914         depends on DEBUG_KERNEL && PROC_FS
915         default y
916         help
917           If you say Y here, the /proc/sched_debug file will be provided
918           that can help debug the scheduler. The runtime overhead of this
919           option is minimal.
920 
921 config SCHED_INFO
922         bool
923         default n
924 
925 config SCHEDSTATS
926         bool "Collect scheduler statistics"
927         depends on DEBUG_KERNEL && PROC_FS
928         select SCHED_INFO
929         help
930           If you say Y here, additional code will be inserted into the
931           scheduler and related routines to collect statistics about
932           scheduler behavior and provide them in /proc/schedstat.  These
933           stats may be useful for both tuning and debugging the scheduler
934           If you aren't debugging the scheduler or trying to tune a specific
935           application, you can say N to avoid the very slight overhead
936           this adds.
937 
938 config SCHED_STACK_END_CHECK
939         bool "Detect stack corruption on calls to schedule()"
940         depends on DEBUG_KERNEL
941         default n
942         help
943           This option checks for a stack overrun on calls to schedule().
944           If the stack end location is found to be over written always panic as
945           the content of the corrupted region can no longer be trusted.
946           This is to ensure no erroneous behaviour occurs which could result in
947           data corruption or a sporadic crash at a later stage once the region
948           is examined. The runtime overhead introduced is minimal.
949 
950 config DEBUG_TIMEKEEPING
951         bool "Enable extra timekeeping sanity checking"
952         help
953           This option will enable additional timekeeping sanity checks
954           which may be helpful when diagnosing issues where timekeeping
955           problems are suspected.
956 
957           This may include checks in the timekeeping hotpaths, so this
958           option may have a (very small) performance impact to some
959           workloads.
960 
961           If unsure, say N.
962 
963 config TIMER_STATS
964         bool "Collect kernel timers statistics"
965         depends on DEBUG_KERNEL && PROC_FS
966         help
967           If you say Y here, additional code will be inserted into the
968           timer routines to collect statistics about kernel timers being
969           reprogrammed. The statistics can be read from /proc/timer_stats.
970           The statistics collection is started by writing 1 to /proc/timer_stats,
971           writing 0 stops it. This feature is useful to collect information
972           about timer usage patterns in kernel and userspace. This feature
973           is lightweight if enabled in the kernel config but not activated
974           (it defaults to deactivated on bootup and will only be activated
975           if some application like powertop activates it explicitly).
976 
977 config DEBUG_PREEMPT
978         bool "Debug preemptible kernel"
979         depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
980         default y
981         help
982           If you say Y here then the kernel will use a debug variant of the
983           commonly used smp_processor_id() function and will print warnings
984           if kernel code uses it in a preemption-unsafe way. Also, the kernel
985           will detect preemption count underflows.
986 
987 menu "Lock Debugging (spinlocks, mutexes, etc...)"
988 
989 config DEBUG_RT_MUTEXES
990         bool "RT Mutex debugging, deadlock detection"
991         depends on DEBUG_KERNEL && RT_MUTEXES
992         help
993          This allows rt mutex semantics violations and rt mutex related
994          deadlocks (lockups) to be detected and reported automatically.
995 
996 config DEBUG_SPINLOCK
997         bool "Spinlock and rw-lock debugging: basic checks"
998         depends on DEBUG_KERNEL
999         select UNINLINE_SPIN_UNLOCK
1000         help
1001           Say Y here and build SMP to catch missing spinlock initialization
1002           and certain other kinds of spinlock errors commonly made.  This is
1003           best used in conjunction with the NMI watchdog so that spinlock
1004           deadlocks are also debuggable.
1005 
1006 config DEBUG_MUTEXES
1007         bool "Mutex debugging: basic checks"
1008         depends on DEBUG_KERNEL
1009         help
1010          This feature allows mutex semantics violations to be detected and
1011          reported.
1012 
1013 config DEBUG_WW_MUTEX_SLOWPATH
1014         bool "Wait/wound mutex debugging: Slowpath testing"
1015         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1016         select DEBUG_LOCK_ALLOC
1017         select DEBUG_SPINLOCK
1018         select DEBUG_MUTEXES
1019         help
1020          This feature enables slowpath testing for w/w mutex users by
1021          injecting additional -EDEADLK wound/backoff cases. Together with
1022          the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1023          will test all possible w/w mutex interface abuse with the
1024          exception of simply not acquiring all the required locks.
1025          Note that this feature can introduce significant overhead, so
1026          it really should not be enabled in a production or distro kernel,
1027          even a debug kernel.  If you are a driver writer, enable it.  If
1028          you are a distro, do not.
1029 
1030 config DEBUG_LOCK_ALLOC
1031         bool "Lock debugging: detect incorrect freeing of live locks"
1032         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1033         select DEBUG_SPINLOCK
1034         select DEBUG_MUTEXES
1035         select LOCKDEP
1036         help
1037          This feature will check whether any held lock (spinlock, rwlock,
1038          mutex or rwsem) is incorrectly freed by the kernel, via any of the
1039          memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1040          vfree(), etc.), whether a live lock is incorrectly reinitialized via
1041          spin_lock_init()/mutex_init()/etc., or whether there is any lock
1042          held during task exit.
1043 
1044 config PROVE_LOCKING
1045         bool "Lock debugging: prove locking correctness"
1046         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1047         select LOCKDEP
1048         select DEBUG_SPINLOCK
1049         select DEBUG_MUTEXES
1050         select DEBUG_LOCK_ALLOC
1051         select TRACE_IRQFLAGS
1052         default n
1053         help
1054          This feature enables the kernel to prove that all locking
1055          that occurs in the kernel runtime is mathematically
1056          correct: that under no circumstance could an arbitrary (and
1057          not yet triggered) combination of observed locking
1058          sequences (on an arbitrary number of CPUs, running an
1059          arbitrary number of tasks and interrupt contexts) cause a
1060          deadlock.
1061 
1062          In short, this feature enables the kernel to report locking
1063          related deadlocks before they actually occur.
1064 
1065          The proof does not depend on how hard and complex a
1066          deadlock scenario would be to trigger: how many
1067          participant CPUs, tasks and irq-contexts would be needed
1068          for it to trigger. The proof also does not depend on
1069          timing: if a race and a resulting deadlock is possible
1070          theoretically (no matter how unlikely the race scenario
1071          is), it will be proven so and will immediately be
1072          reported by the kernel (once the event is observed that
1073          makes the deadlock theoretically possible).
1074 
1075          If a deadlock is impossible (i.e. the locking rules, as
1076          observed by the kernel, are mathematically correct), the
1077          kernel reports nothing.
1078 
1079          NOTE: this feature can also be enabled for rwlocks, mutexes
1080          and rwsems - in which case all dependencies between these
1081          different locking variants are observed and mapped too, and
1082          the proof of observed correctness is also maintained for an
1083          arbitrary combination of these separate locking variants.
1084 
1085          For more details, see Documentation/locking/lockdep-design.txt.
1086 
1087 config LOCKDEP
1088         bool
1089         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1090         select STACKTRACE
1091         select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC && !SCORE
1092         select KALLSYMS
1093         select KALLSYMS_ALL
1094 
1095 config LOCK_STAT
1096         bool "Lock usage statistics"
1097         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1098         select LOCKDEP
1099         select DEBUG_SPINLOCK
1100         select DEBUG_MUTEXES
1101         select DEBUG_LOCK_ALLOC
1102         default n
1103         help
1104          This feature enables tracking lock contention points
1105 
1106          For more details, see Documentation/locking/lockstat.txt
1107 
1108          This also enables lock events required by "perf lock",
1109          subcommand of perf.
1110          If you want to use "perf lock", you also need to turn on
1111          CONFIG_EVENT_TRACING.
1112 
1113          CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1114          (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1115 
1116 config DEBUG_LOCKDEP
1117         bool "Lock dependency engine debugging"
1118         depends on DEBUG_KERNEL && LOCKDEP
1119         help
1120           If you say Y here, the lock dependency engine will do
1121           additional runtime checks to debug itself, at the price
1122           of more runtime overhead.
1123 
1124 config DEBUG_ATOMIC_SLEEP
1125         bool "Sleep inside atomic section checking"
1126         select PREEMPT_COUNT
1127         depends on DEBUG_KERNEL
1128         help
1129           If you say Y here, various routines which may sleep will become very
1130           noisy if they are called inside atomic sections: when a spinlock is
1131           held, inside an rcu read side critical section, inside preempt disabled
1132           sections, inside an interrupt, etc...
1133 
1134 config DEBUG_LOCKING_API_SELFTESTS
1135         bool "Locking API boot-time self-tests"
1136         depends on DEBUG_KERNEL
1137         help
1138           Say Y here if you want the kernel to run a short self-test during
1139           bootup. The self-test checks whether common types of locking bugs
1140           are detected by debugging mechanisms or not. (if you disable
1141           lock debugging then those bugs wont be detected of course.)
1142           The following locking APIs are covered: spinlocks, rwlocks,
1143           mutexes and rwsems.
1144 
1145 config LOCK_TORTURE_TEST
1146         tristate "torture tests for locking"
1147         depends on DEBUG_KERNEL
1148         select TORTURE_TEST
1149         default n
1150         help
1151           This option provides a kernel module that runs torture tests
1152           on kernel locking primitives.  The kernel module may be built
1153           after the fact on the running kernel to be tested, if desired.
1154 
1155           Say Y here if you want kernel locking-primitive torture tests
1156           to be built into the kernel.
1157           Say M if you want these torture tests to build as a module.
1158           Say N if you are unsure.
1159 
1160 endmenu # lock debugging
1161 
1162 config TRACE_IRQFLAGS
1163         bool
1164         help
1165           Enables hooks to interrupt enabling and disabling for
1166           either tracing or lock debugging.
1167 
1168 config STACKTRACE
1169         bool "Stack backtrace support"
1170         depends on STACKTRACE_SUPPORT
1171         help
1172           This option causes the kernel to create a /proc/pid/stack for
1173           every process, showing its current stack trace.
1174           It is also used by various kernel debugging features that require
1175           stack trace generation.
1176 
1177 config DEBUG_KOBJECT
1178         bool "kobject debugging"
1179         depends on DEBUG_KERNEL
1180         help
1181           If you say Y here, some extra kobject debugging messages will be sent
1182           to the syslog. 
1183 
1184 config DEBUG_KOBJECT_RELEASE
1185         bool "kobject release debugging"
1186         depends on DEBUG_OBJECTS_TIMERS
1187         help
1188           kobjects are reference counted objects.  This means that their
1189           last reference count put is not predictable, and the kobject can
1190           live on past the point at which a driver decides to drop it's
1191           initial reference to the kobject gained on allocation.  An
1192           example of this would be a struct device which has just been
1193           unregistered.
1194 
1195           However, some buggy drivers assume that after such an operation,
1196           the memory backing the kobject can be immediately freed.  This
1197           goes completely against the principles of a refcounted object.
1198 
1199           If you say Y here, the kernel will delay the release of kobjects
1200           on the last reference count to improve the visibility of this
1201           kind of kobject release bug.
1202 
1203 config HAVE_DEBUG_BUGVERBOSE
1204         bool
1205 
1206 config DEBUG_BUGVERBOSE
1207         bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
1208         depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
1209         default y
1210         help
1211           Say Y here to make BUG() panics output the file name and line number
1212           of the BUG call as well as the EIP and oops trace.  This aids
1213           debugging but costs about 70-100K of memory.
1214 
1215 config DEBUG_LIST
1216         bool "Debug linked list manipulation"
1217         depends on DEBUG_KERNEL
1218         help
1219           Enable this to turn on extended checks in the linked-list
1220           walking routines.
1221 
1222           If unsure, say N.
1223 
1224 config DEBUG_PI_LIST
1225         bool "Debug priority linked list manipulation"
1226         depends on DEBUG_KERNEL
1227         help
1228           Enable this to turn on extended checks in the priority-ordered
1229           linked-list (plist) walking routines.  This checks the entire
1230           list multiple times during each manipulation.
1231 
1232           If unsure, say N.
1233 
1234 config DEBUG_SG
1235         bool "Debug SG table operations"
1236         depends on DEBUG_KERNEL
1237         help
1238           Enable this to turn on checks on scatter-gather tables. This can
1239           help find problems with drivers that do not properly initialize
1240           their sg tables.
1241 
1242           If unsure, say N.
1243 
1244 config DEBUG_NOTIFIERS
1245         bool "Debug notifier call chains"
1246         depends on DEBUG_KERNEL
1247         help
1248           Enable this to turn on sanity checking for notifier call chains.
1249           This is most useful for kernel developers to make sure that
1250           modules properly unregister themselves from notifier chains.
1251           This is a relatively cheap check but if you care about maximum
1252           performance, say N.
1253 
1254 config DEBUG_CREDENTIALS
1255         bool "Debug credential management"
1256         depends on DEBUG_KERNEL
1257         help
1258           Enable this to turn on some debug checking for credential
1259           management.  The additional code keeps track of the number of
1260           pointers from task_structs to any given cred struct, and checks to
1261           see that this number never exceeds the usage count of the cred
1262           struct.
1263 
1264           Furthermore, if SELinux is enabled, this also checks that the
1265           security pointer in the cred struct is never seen to be invalid.
1266 
1267           If unsure, say N.
1268 
1269 menu "RCU Debugging"
1270 
1271 config PROVE_RCU
1272         def_bool PROVE_LOCKING
1273 
1274 config PROVE_RCU_REPEATEDLY
1275         bool "RCU debugging: don't disable PROVE_RCU on first splat"
1276         depends on PROVE_RCU
1277         default n
1278         help
1279          By itself, PROVE_RCU will disable checking upon issuing the
1280          first warning (or "splat").  This feature prevents such
1281          disabling, allowing multiple RCU-lockdep warnings to be printed
1282          on a single reboot.
1283 
1284          Say Y to allow multiple RCU-lockdep warnings per boot.
1285 
1286          Say N if you are unsure.
1287 
1288 config SPARSE_RCU_POINTER
1289         bool "RCU debugging: sparse-based checks for pointer usage"
1290         default n
1291         help
1292          This feature enables the __rcu sparse annotation for
1293          RCU-protected pointers.  This annotation will cause sparse
1294          to flag any non-RCU used of annotated pointers.  This can be
1295          helpful when debugging RCU usage.  Please note that this feature
1296          is not intended to enforce code cleanliness; it is instead merely
1297          a debugging aid.
1298 
1299          Say Y to make sparse flag questionable use of RCU-protected pointers
1300 
1301          Say N if you are unsure.
1302 
1303 config TORTURE_TEST
1304         tristate
1305         default n
1306 
1307 config RCU_PERF_TEST
1308         tristate "performance tests for RCU"
1309         depends on DEBUG_KERNEL
1310         select TORTURE_TEST
1311         select SRCU
1312         select TASKS_RCU
1313         default n
1314         help
1315           This option provides a kernel module that runs performance
1316           tests on the RCU infrastructure.  The kernel module may be built
1317           after the fact on the running kernel to be tested, if desired.
1318 
1319           Say Y here if you want RCU performance tests to be built into
1320           the kernel.
1321           Say M if you want the RCU performance tests to build as a module.
1322           Say N if you are unsure.
1323 
1324 config RCU_TORTURE_TEST
1325         tristate "torture tests for RCU"
1326         depends on DEBUG_KERNEL
1327         select TORTURE_TEST
1328         select SRCU
1329         select TASKS_RCU
1330         default n
1331         help
1332           This option provides a kernel module that runs torture tests
1333           on the RCU infrastructure.  The kernel module may be built
1334           after the fact on the running kernel to be tested, if desired.
1335 
1336           Say Y here if you want RCU torture tests to be built into
1337           the kernel.
1338           Say M if you want the RCU torture tests to build as a module.
1339           Say N if you are unsure.
1340 
1341 config RCU_TORTURE_TEST_SLOW_PREINIT
1342         bool "Slow down RCU grace-period pre-initialization to expose races"
1343         depends on RCU_TORTURE_TEST
1344         help
1345           This option delays grace-period pre-initialization (the
1346           propagation of CPU-hotplug changes up the rcu_node combining
1347           tree) for a few jiffies between initializing each pair of
1348           consecutive rcu_node structures.  This helps to expose races
1349           involving grace-period pre-initialization, in other words, it
1350           makes your kernel less stable.  It can also greatly increase
1351           grace-period latency, especially on systems with large numbers
1352           of CPUs.  This is useful when torture-testing RCU, but in
1353           almost no other circumstance.
1354 
1355           Say Y here if you want your system to crash and hang more often.
1356           Say N if you want a sane system.
1357 
1358 config RCU_TORTURE_TEST_SLOW_PREINIT_DELAY
1359         int "How much to slow down RCU grace-period pre-initialization"
1360         range 0 5
1361         default 3
1362         depends on RCU_TORTURE_TEST_SLOW_PREINIT
1363         help
1364           This option specifies the number of jiffies to wait between
1365           each rcu_node structure pre-initialization step.
1366 
1367 config RCU_TORTURE_TEST_SLOW_INIT
1368         bool "Slow down RCU grace-period initialization to expose races"
1369         depends on RCU_TORTURE_TEST
1370         help
1371           This option delays grace-period initialization for a few
1372           jiffies between initializing each pair of consecutive
1373           rcu_node structures.  This helps to expose races involving
1374           grace-period initialization, in other words, it makes your
1375           kernel less stable.  It can also greatly increase grace-period
1376           latency, especially on systems with large numbers of CPUs.
1377           This is useful when torture-testing RCU, but in almost no
1378           other circumstance.
1379 
1380           Say Y here if you want your system to crash and hang more often.
1381           Say N if you want a sane system.
1382 
1383 config RCU_TORTURE_TEST_SLOW_INIT_DELAY
1384         int "How much to slow down RCU grace-period initialization"
1385         range 0 5
1386         default 3
1387         depends on RCU_TORTURE_TEST_SLOW_INIT
1388         help
1389           This option specifies the number of jiffies to wait between
1390           each rcu_node structure initialization.
1391 
1392 config RCU_TORTURE_TEST_SLOW_CLEANUP
1393         bool "Slow down RCU grace-period cleanup to expose races"
1394         depends on RCU_TORTURE_TEST
1395         help
1396           This option delays grace-period cleanup for a few jiffies
1397           between cleaning up each pair of consecutive rcu_node
1398           structures.  This helps to expose races involving grace-period
1399           cleanup, in other words, it makes your kernel less stable.
1400           It can also greatly increase grace-period latency, especially
1401           on systems with large numbers of CPUs.  This is useful when
1402           torture-testing RCU, but in almost no other circumstance.
1403 
1404           Say Y here if you want your system to crash and hang more often.
1405           Say N if you want a sane system.
1406 
1407 config RCU_TORTURE_TEST_SLOW_CLEANUP_DELAY
1408         int "How much to slow down RCU grace-period cleanup"
1409         range 0 5
1410         default 3
1411         depends on RCU_TORTURE_TEST_SLOW_CLEANUP
1412         help
1413           This option specifies the number of jiffies to wait between
1414           each rcu_node structure cleanup operation.
1415 
1416 config RCU_CPU_STALL_TIMEOUT
1417         int "RCU CPU stall timeout in seconds"
1418         depends on RCU_STALL_COMMON
1419         range 3 300
1420         default 21
1421         help
1422           If a given RCU grace period extends more than the specified
1423           number of seconds, a CPU stall warning is printed.  If the
1424           RCU grace period persists, additional CPU stall warnings are
1425           printed at more widely spaced intervals.
1426 
1427 config RCU_TRACE
1428         bool "Enable tracing for RCU"
1429         depends on DEBUG_KERNEL
1430         select TRACE_CLOCK
1431         help
1432           This option provides tracing in RCU which presents stats
1433           in debugfs for debugging RCU implementation.
1434 
1435           Say Y here if you want to enable RCU tracing
1436           Say N if you are unsure.
1437 
1438 config RCU_EQS_DEBUG
1439         bool "Provide debugging asserts for adding NO_HZ support to an arch"
1440         depends on DEBUG_KERNEL
1441         help
1442           This option provides consistency checks in RCU's handling of
1443           NO_HZ.  These checks have proven quite helpful in detecting
1444           bugs in arch-specific NO_HZ code.
1445 
1446           Say N here if you need ultimate kernel/user switch latencies
1447           Say Y if you are unsure
1448 
1449 endmenu # "RCU Debugging"
1450 
1451 config DEBUG_WQ_FORCE_RR_CPU
1452         bool "Force round-robin CPU selection for unbound work items"
1453         depends on DEBUG_KERNEL
1454         default n
1455         help
1456           Workqueue used to implicitly guarantee that work items queued
1457           without explicit CPU specified are put on the local CPU.  This
1458           guarantee is no longer true and while local CPU is still
1459           preferred work items may be put on foreign CPUs.  Kernel
1460           parameter "workqueue.debug_force_rr_cpu" is added to force
1461           round-robin CPU selection to flush out usages which depend on the
1462           now broken guarantee.  This config option enables the debug
1463           feature by default.  When enabled, memory and cache locality will
1464           be impacted.
1465 
1466 config DEBUG_BLOCK_EXT_DEVT
1467         bool "Force extended block device numbers and spread them"
1468         depends on DEBUG_KERNEL
1469         depends on BLOCK
1470         default n
1471         help
1472           BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1473           SOME DISTRIBUTIONS.  DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1474           YOU ARE DOING.  Distros, please enable this and fix whatever
1475           is broken.
1476 
1477           Conventionally, block device numbers are allocated from
1478           predetermined contiguous area.  However, extended block area
1479           may introduce non-contiguous block device numbers.  This
1480           option forces most block device numbers to be allocated from
1481           the extended space and spreads them to discover kernel or
1482           userland code paths which assume predetermined contiguous
1483           device number allocation.
1484 
1485           Note that turning on this debug option shuffles all the
1486           device numbers for all IDE and SCSI devices including libata
1487           ones, so root partition specified using device number
1488           directly (via rdev or root=MAJ:MIN) won't work anymore.
1489           Textual device names (root=/dev/sdXn) will continue to work.
1490 
1491           Say N if you are unsure.
1492 
1493 config CPU_HOTPLUG_STATE_CONTROL
1494         bool "Enable CPU hotplug state control"
1495         depends on DEBUG_KERNEL
1496         depends on HOTPLUG_CPU
1497         default n
1498         help
1499           Allows to write steps between "offline" and "online" to the CPUs
1500           sysfs target file so states can be stepped granular. This is a debug
1501           option for now as the hotplug machinery cannot be stopped and
1502           restarted at arbitrary points yet.
1503 
1504           Say N if your are unsure.
1505 
1506 config NOTIFIER_ERROR_INJECTION
1507         tristate "Notifier error injection"
1508         depends on DEBUG_KERNEL
1509         select DEBUG_FS
1510         help
1511           This option provides the ability to inject artificial errors to
1512           specified notifier chain callbacks. It is useful to test the error
1513           handling of notifier call chain failures.
1514 
1515           Say N if unsure.
1516 
1517 config CPU_NOTIFIER_ERROR_INJECT
1518         tristate "CPU notifier error injection module"
1519         depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
1520         help
1521           This option provides a kernel module that can be used to test
1522           the error handling of the cpu notifiers by injecting artificial
1523           errors to CPU notifier chain callbacks.  It is controlled through
1524           debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
1525 
1526           If the notifier call chain should be failed with some events
1527           notified, write the error code to "actions/<notifier event>/error".
1528 
1529           Example: Inject CPU offline error (-1 == -EPERM)
1530 
1531           # cd /sys/kernel/debug/notifier-error-inject/cpu
1532           # echo -1 > actions/CPU_DOWN_PREPARE/error
1533           # echo 0 > /sys/devices/system/cpu/cpu1/online
1534           bash: echo: write error: Operation not permitted
1535 
1536           To compile this code as a module, choose M here: the module will
1537           be called cpu-notifier-error-inject.
1538 
1539           If unsure, say N.
1540 
1541 config PM_NOTIFIER_ERROR_INJECT
1542         tristate "PM notifier error injection module"
1543         depends on PM && NOTIFIER_ERROR_INJECTION
1544         default m if PM_DEBUG
1545         help
1546           This option provides the ability to inject artificial errors to
1547           PM notifier chain callbacks.  It is controlled through debugfs
1548           interface /sys/kernel/debug/notifier-error-inject/pm
1549 
1550           If the notifier call chain should be failed with some events
1551           notified, write the error code to "actions/<notifier event>/error".
1552 
1553           Example: Inject PM suspend error (-12 = -ENOMEM)
1554 
1555           # cd /sys/kernel/debug/notifier-error-inject/pm/
1556           # echo -12 > actions/PM_SUSPEND_PREPARE/error
1557           # echo mem > /sys/power/state
1558           bash: echo: write error: Cannot allocate memory
1559 
1560           To compile this code as a module, choose M here: the module will
1561           be called pm-notifier-error-inject.
1562 
1563           If unsure, say N.
1564 
1565 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1566         tristate "OF reconfig notifier error injection module"
1567         depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1568         help
1569           This option provides the ability to inject artificial errors to
1570           OF reconfig notifier chain callbacks.  It is controlled
1571           through debugfs interface under
1572           /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1573 
1574           If the notifier call chain should be failed with some events
1575           notified, write the error code to "actions/<notifier event>/error".
1576 
1577           To compile this code as a module, choose M here: the module will
1578           be called of-reconfig-notifier-error-inject.
1579 
1580           If unsure, say N.
1581 
1582 config NETDEV_NOTIFIER_ERROR_INJECT
1583         tristate "Netdev notifier error injection module"
1584         depends on NET && NOTIFIER_ERROR_INJECTION
1585         help
1586           This option provides the ability to inject artificial errors to
1587           netdevice notifier chain callbacks.  It is controlled through debugfs
1588           interface /sys/kernel/debug/notifier-error-inject/netdev
1589 
1590           If the notifier call chain should be failed with some events
1591           notified, write the error code to "actions/<notifier event>/error".
1592 
1593           Example: Inject netdevice mtu change error (-22 = -EINVAL)
1594 
1595           # cd /sys/kernel/debug/notifier-error-inject/netdev
1596           # echo -22 > actions/NETDEV_CHANGEMTU/error
1597           # ip link set eth0 mtu 1024
1598           RTNETLINK answers: Invalid argument
1599 
1600           To compile this code as a module, choose M here: the module will
1601           be called netdev-notifier-error-inject.
1602 
1603           If unsure, say N.
1604 
1605 config FAULT_INJECTION
1606         bool "Fault-injection framework"
1607         depends on DEBUG_KERNEL
1608         help
1609           Provide fault-injection framework.
1610           For more details, see Documentation/fault-injection/.
1611 
1612 config FAILSLAB
1613         bool "Fault-injection capability for kmalloc"
1614         depends on FAULT_INJECTION
1615         depends on SLAB || SLUB
1616         help
1617           Provide fault-injection capability for kmalloc.
1618 
1619 config FAIL_PAGE_ALLOC
1620         bool "Fault-injection capabilitiy for alloc_pages()"
1621         depends on FAULT_INJECTION
1622         help
1623           Provide fault-injection capability for alloc_pages().
1624 
1625 config FAIL_MAKE_REQUEST
1626         bool "Fault-injection capability for disk IO"
1627         depends on FAULT_INJECTION && BLOCK
1628         help
1629           Provide fault-injection capability for disk IO.
1630 
1631 config FAIL_IO_TIMEOUT
1632         bool "Fault-injection capability for faking disk interrupts"
1633         depends on FAULT_INJECTION && BLOCK
1634         help
1635           Provide fault-injection capability on end IO handling. This
1636           will make the block layer "forget" an interrupt as configured,
1637           thus exercising the error handling.
1638 
1639           Only works with drivers that use the generic timeout handling,
1640           for others it wont do anything.
1641 
1642 config FAIL_MMC_REQUEST
1643         bool "Fault-injection capability for MMC IO"
1644         depends on FAULT_INJECTION_DEBUG_FS && MMC
1645         help
1646           Provide fault-injection capability for MMC IO.
1647           This will make the mmc core return data errors. This is
1648           useful to test the error handling in the mmc block device
1649           and to test how the mmc host driver handles retries from
1650           the block device.
1651 
1652 config FAIL_FUTEX
1653         bool "Fault-injection capability for futexes"
1654         select DEBUG_FS
1655         depends on FAULT_INJECTION && FUTEX
1656         help
1657           Provide fault-injection capability for futexes.
1658 
1659 config FAULT_INJECTION_DEBUG_FS
1660         bool "Debugfs entries for fault-injection capabilities"
1661         depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1662         help
1663           Enable configuration of fault-injection capabilities via debugfs.
1664 
1665 config FAULT_INJECTION_STACKTRACE_FILTER
1666         bool "stacktrace filter for fault-injection capabilities"
1667         depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1668         depends on !X86_64
1669         select STACKTRACE
1670         select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC && !SCORE
1671         help
1672           Provide stacktrace filter for fault-injection capabilities
1673 
1674 config LATENCYTOP
1675         bool "Latency measuring infrastructure"
1676         depends on DEBUG_KERNEL
1677         depends on STACKTRACE_SUPPORT
1678         depends on PROC_FS
1679         select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC
1680         select KALLSYMS
1681         select KALLSYMS_ALL
1682         select STACKTRACE
1683         select SCHEDSTATS
1684         select SCHED_DEBUG
1685         help
1686           Enable this option if you want to use the LatencyTOP tool
1687           to find out which userspace is blocking on what kernel operations.
1688 
1689 source kernel/trace/Kconfig
1690 
1691 menu "Runtime Testing"
1692 
1693 config LKDTM
1694         tristate "Linux Kernel Dump Test Tool Module"
1695         depends on DEBUG_FS
1696         depends on BLOCK
1697         default n
1698         help
1699         This module enables testing of the different dumping mechanisms by
1700         inducing system failures at predefined crash points.
1701         If you don't need it: say N
1702         Choose M here to compile this code as a module. The module will be
1703         called lkdtm.
1704 
1705         Documentation on how to use the module can be found in
1706         Documentation/fault-injection/provoke-crashes.txt
1707 
1708 config TEST_LIST_SORT
1709         bool "Linked list sorting test"
1710         depends on DEBUG_KERNEL
1711         help
1712           Enable this to turn on 'list_sort()' function test. This test is
1713           executed only once during system boot, so affects only boot time.
1714 
1715           If unsure, say N.
1716 
1717 config KPROBES_SANITY_TEST
1718         bool "Kprobes sanity tests"
1719         depends on DEBUG_KERNEL
1720         depends on KPROBES
1721         default n
1722         help
1723           This option provides for testing basic kprobes functionality on
1724           boot. A sample kprobe, jprobe and kretprobe are inserted and
1725           verified for functionality.
1726 
1727           Say N if you are unsure.
1728 
1729 config BACKTRACE_SELF_TEST
1730         tristate "Self test for the backtrace code"
1731         depends on DEBUG_KERNEL
1732         default n
1733         help
1734           This option provides a kernel module that can be used to test
1735           the kernel stack backtrace code. This option is not useful
1736           for distributions or general kernels, but only for kernel
1737           developers working on architecture code.
1738 
1739           Note that if you want to also test saved backtraces, you will
1740           have to enable STACKTRACE as well.
1741 
1742           Say N if you are unsure.
1743 
1744 config RBTREE_TEST
1745         tristate "Red-Black tree test"
1746         depends on DEBUG_KERNEL
1747         help
1748           A benchmark measuring the performance of the rbtree library.
1749           Also includes rbtree invariant checks.
1750 
1751 config INTERVAL_TREE_TEST
1752         tristate "Interval tree test"
1753         depends on m && DEBUG_KERNEL
1754         select INTERVAL_TREE
1755         help
1756           A benchmark measuring the performance of the interval tree library
1757 
1758 config PERCPU_TEST
1759         tristate "Per cpu operations test"
1760         depends on m && DEBUG_KERNEL
1761         help
1762           Enable this option to build test module which validates per-cpu
1763           operations.
1764 
1765           If unsure, say N.
1766 
1767 config ATOMIC64_SELFTEST
1768         bool "Perform an atomic64_t self-test at boot"
1769         help
1770           Enable this option to test the atomic64_t functions at boot.
1771 
1772           If unsure, say N.
1773 
1774 config ASYNC_RAID6_TEST
1775         tristate "Self test for hardware accelerated raid6 recovery"
1776         depends on ASYNC_RAID6_RECOV
1777         select ASYNC_MEMCPY
1778         ---help---
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.
1784 
1785           If unsure, say N.
1786 
1787 config TEST_HEXDUMP
1788         tristate "Test functions located in the hexdump module at runtime"
1789 
1790 config TEST_STRING_HELPERS
1791         tristate "Test functions located in the string_helpers module at runtime"
1792 
1793 config TEST_KSTRTOX
1794         tristate "Test kstrto*() family of functions at runtime"
1795 
1796 config TEST_PRINTF
1797         tristate "Test printf() family of functions at runtime"
1798 
1799 config TEST_BITMAP
1800         tristate "Test bitmap_*() family of functions at runtime"
1801         default n
1802         help
1803           Enable this option to test the bitmap functions at boot.
1804 
1805           If unsure, say N.
1806 
1807 config TEST_UUID
1808         tristate "Test functions located in the uuid module at runtime"
1809 
1810 config TEST_RHASHTABLE
1811         tristate "Perform selftest on resizable hash table"
1812         default n
1813         help
1814           Enable this option to test the rhashtable functions at boot.
1815 
1816           If unsure, say N.
1817 
1818 config TEST_HASH
1819         tristate "Perform selftest on hash functions"
1820         default n
1821         help
1822           Enable this option to test the kernel's integer (<linux/hash,h>)
1823           and string (<linux/stringhash.h>) hash functions on boot
1824           (or module load).
1825 
1826           This is intended to help people writing architecture-specific
1827           optimized versions.  If unsure, say N.
1828 
1829 endmenu # runtime tests
1830 
1831 config PROVIDE_OHCI1394_DMA_INIT
1832         bool "Remote debugging over FireWire early on boot"
1833         depends on PCI && X86
1834         help
1835           If you want to debug problems which hang or crash the kernel early
1836           on boot and the crashing machine has a FireWire port, you can use
1837           this feature to remotely access the memory of the crashed machine
1838           over FireWire. This employs remote DMA as part of the OHCI1394
1839           specification which is now the standard for FireWire controllers.
1840 
1841           With remote DMA, you can monitor the printk buffer remotely using
1842           firescope and access all memory below 4GB using fireproxy from gdb.
1843           Even controlling a kernel debugger is possible using remote DMA.
1844 
1845           Usage:
1846 
1847           If ohci1394_dma=early is used as boot parameter, it will initialize
1848           all OHCI1394 controllers which are found in the PCI config space.
1849 
1850           As all changes to the FireWire bus such as enabling and disabling
1851           devices cause a bus reset and thereby disable remote DMA for all
1852           devices, be sure to have the cable plugged and FireWire enabled on
1853           the debugging host before booting the debug target for debugging.
1854 
1855           This code (~1k) is freed after boot. By then, the firewire stack
1856           in charge of the OHCI-1394 controllers should be used instead.
1857 
1858           See Documentation/debugging-via-ohci1394.txt for more information.
1859 
1860 config BUILD_DOCSRC
1861         bool "Build targets in Documentation/ tree"
1862         depends on HEADERS_CHECK
1863         help
1864           This option attempts to build objects from the source files in the
1865           kernel Documentation/ tree.
1866 
1867           Say N if you are unsure.
1868 
1869 config DMA_API_DEBUG
1870         bool "Enable debugging of DMA-API usage"
1871         depends on HAVE_DMA_API_DEBUG
1872         help
1873           Enable this option to debug the use of the DMA API by device drivers.
1874           With this option you will be able to detect common bugs in device
1875           drivers like double-freeing of DMA mappings or freeing mappings that
1876           were never allocated.
1877 
1878           This also attempts to catch cases where a page owned by DMA is
1879           accessed by the cpu in a way that could cause data corruption.  For
1880           example, this enables cow_user_page() to check that the source page is
1881           not undergoing DMA.
1882 
1883           This option causes a performance degradation.  Use only if you want to
1884           debug device drivers and dma interactions.
1885 
1886           If unsure, say N.
1887 
1888 config TEST_LKM
1889         tristate "Test module loading with 'hello world' module"
1890         default n
1891         depends on m
1892         help
1893           This builds the "test_module" module that emits "Hello, world"
1894           on printk when loaded. It is designed to be used for basic
1895           evaluation of the module loading subsystem (for example when
1896           validating module verification). It lacks any extra dependencies,
1897           and will not normally be loaded by the system unless explicitly
1898           requested by name.
1899 
1900           If unsure, say N.
1901 
1902 config TEST_USER_COPY
1903         tristate "Test user/kernel boundary protections"
1904         default n
1905         depends on m
1906         help
1907           This builds the "test_user_copy" module that runs sanity checks
1908           on the copy_to/from_user infrastructure, making sure basic
1909           user/kernel boundary testing is working. If it fails to load,
1910           a regression has been detected in the user/kernel memory boundary
1911           protections.
1912 
1913           If unsure, say N.
1914 
1915 config TEST_BPF
1916         tristate "Test BPF filter functionality"
1917         default n
1918         depends on m && NET
1919         help
1920           This builds the "test_bpf" module that runs various test vectors
1921           against the BPF interpreter or BPF JIT compiler depending on the
1922           current setting. This is in particular useful for BPF JIT compiler
1923           development, but also to run regression tests against changes in
1924           the interpreter code. It also enables test stubs for eBPF maps and
1925           verifier used by user space verifier testsuite.
1926 
1927           If unsure, say N.
1928 
1929 config TEST_FIRMWARE
1930         tristate "Test firmware loading via userspace interface"
1931         default n
1932         depends on FW_LOADER
1933         help
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
1938           userspace.
1939 
1940           If unsure, say N.
1941 
1942 config TEST_UDELAY
1943         tristate "udelay test driver"
1944         default n
1945         help
1946           This builds the "udelay_test" module that helps to make sure
1947           that udelay() is working properly.
1948 
1949           If unsure, say N.
1950 
1951 config MEMTEST
1952         bool "Memtest"
1953         depends on HAVE_MEMBLOCK
1954         ---help---
1955           This option adds a kernel parameter 'memtest', which allows memtest
1956           to be set.
1957                 memtest=0, mean disabled; -- default
1958                 memtest=1, mean do 1 test pattern;
1959                 ...
1960                 memtest=17, mean do 17 test patterns.
1961           If you are unsure how to answer this question, answer N.
1962 
1963 config TEST_STATIC_KEYS
1964         tristate "Test static keys"
1965         default n
1966         depends on m
1967         help
1968           Test the static key interfaces.
1969 
1970           If unsure, say N.
1971 
1972 source "samples/Kconfig"
1973 
1974 source "lib/Kconfig.kgdb"
1975 
1976 source "lib/Kconfig.ubsan"
1977 
1978 config ARCH_HAS_DEVMEM_IS_ALLOWED
1979         bool
1980 
1981 config STRICT_DEVMEM
1982         bool "Filter access to /dev/mem"
1983         depends on MMU
1984         depends on ARCH_HAS_DEVMEM_IS_ALLOWED
1985         default y if TILE || PPC
1986         ---help---
1987           If this option is disabled, you allow userspace (root) access to all
1988           of memory, including kernel and userspace memory. Accidental
1989           access to this is obviously disastrous, but specific access can
1990           be used by people debugging the kernel. Note that with PAT support
1991           enabled, even in this case there are restrictions on /dev/mem
1992           use due to the cache aliasing requirements.
1993 
1994           If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
1995           file only allows userspace access to PCI space and the BIOS code and
1996           data regions.  This is sufficient for dosemu and X and all common
1997           users of /dev/mem.
1998 
1999           If in doubt, say Y.
2000 
2001 config IO_STRICT_DEVMEM
2002         bool "Filter I/O access to /dev/mem"
2003         depends on STRICT_DEVMEM
2004         ---help---
2005           If this option is disabled, you allow userspace (root) access to all
2006           io-memory regardless of whether a driver is actively using that
2007           range.  Accidental access to this is obviously disastrous, but
2008           specific access can be used by people debugging kernel drivers.
2009 
2010           If this option is switched on, the /dev/mem file only allows
2011           userspace access to *idle* io-memory ranges (see /proc/iomem) This
2012           may break traditional users of /dev/mem (dosemu, legacy X, etc...)
2013           if the driver using a given range cannot be disabled.
2014 
2015           If in doubt, say Y.

This page was automatically generated by LXR 0.3.1 (source).  •  Linux is a registered trademark of Linus Torvalds  •  Contact us