lib/Kconfig.debug

   1 # SPDX-License-Identifier: GPL-2.0-only
   2 menu "Kernel hacking"
   3
   4 menu "printk and dmesg options"
   5
   6 config PRINTK_TIME
   7         bool "Show timing information on printks"
   8         depends on PRINTK
   9         help
  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.
  13
  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.
  17
  18           The behavior is also controlled by the kernel command line
  19           parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst
  20
  21 config PRINTK_CALLER
  22         bool "Show caller information on printks"
  23         depends on PRINTK
  24         help
  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)
  27           to every message.
  28
  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.
  33
  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
  36           sysfs interface.
  37
  38 config CONSOLE_LOGLEVEL_DEFAULT
  39         int "Default console loglevel (1-15)"
  40         range 1 15
  41         default "7"
  42         help
  43           Default loglevel to determine what will be printed on the console.
  44
  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.
  48
  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
  51           option.
  52
  53 config CONSOLE_LOGLEVEL_QUIET
  54         int "quiet console loglevel (1-15)"
  55         range 1 15
  56         default "4"
  57         help
  58           loglevel to use when "quiet" is passed on the kernel commandline.
  59
  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>"
  63
  64 config MESSAGE_LOGLEVEL_DEFAULT
  65         int "Default message log level (1-7)"
  66         range 1 7
  67         default "4"
  68         help
  69           Default log level for printk statements with no specified priority.
  70
  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
  73           priority.
  74
  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.
  78
  79 config BOOT_PRINTK_DELAY
  80         bool "Delay each boot printk message by N milliseconds"
  81         depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
  82         help
  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,
  86           using "boot_delay=N".
  87
  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.
  96
  97 config DYNAMIC_DEBUG
  98         bool "Enable dynamic printk() support"
  99         default n
 100         depends on PRINTK
 101         depends on (DEBUG_FS || PROC_FS)
 102         select DYNAMIC_DEBUG_CORE
 103         help
 104
 105           Compiles debug level messages into the kernel, which would not
 106           otherwise be available at runtime. These messages can then be
 107           enabled/disabled based on various levels of scope - per source file,
 108           function, module, format string, and line number. This mechanism
 109           implicitly compiles in all pr_debug() and dev_dbg() calls, which
 110           enlarges the kernel text size by about 2%.
 111
 112           If a source file is compiled with DEBUG flag set, any
 113           pr_debug() calls in it are enabled by default, but can be
 114           disabled at runtime as below.  Note that DEBUG flag is
 115           turned on by many CONFIG_*DEBUG* options.
 116
 117           Usage:
 118
 119           Dynamic debugging is controlled via the 'dynamic_debug/control' file,
 120           which is contained in the 'debugfs' filesystem or procfs.
 121           Thus, the debugfs or procfs filesystem must first be mounted before
 122           making use of this feature.
 123           We refer the control file as: <debugfs>/dynamic_debug/control. This
 124           file contains a list of the debug statements that can be enabled. The
 125           format for each line of the file is:
 126
 127                 filename:lineno [module]function flags format
 128
 129           filename : source file of the debug statement
 130           lineno : line number of the debug statement
 131           module : module that contains the debug statement
 132           function : function that contains the debug statement
 133           flags : '=p' means the line is turned 'on' for printing
 134           format : the format used for the debug statement
 135
 136           From a live system:
 137
 138                 nullarbor:~ # cat <debugfs>/dynamic_debug/control
 139                 # filename:lineno [module]function flags format
 140                 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
 141                 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
 142                 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
 143
 144           Example usage:
 145
 146                 // enable the message at line 1603 of file svcsock.c
 147                 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
 148                                                 <debugfs>/dynamic_debug/control
 149
 150                 // enable all the messages in file svcsock.c
 151                 nullarbor:~ # echo -n 'file svcsock.c +p' >
 152                                                 <debugfs>/dynamic_debug/control
 153
 154                 // enable all the messages in the NFS server module
 155                 nullarbor:~ # echo -n 'module nfsd +p' >
 156                                                 <debugfs>/dynamic_debug/control
 157
 158                 // enable all 12 messages in the function svc_process()
 159                 nullarbor:~ # echo -n 'func svc_process +p' >
 160                                                 <debugfs>/dynamic_debug/control
 161
 162                 // disable all 12 messages in the function svc_process()
 163                 nullarbor:~ # echo -n 'func svc_process -p' >
 164                                                 <debugfs>/dynamic_debug/control
 165
 166           See Documentation/admin-guide/dynamic-debug-howto.rst for additional
 167           information.
 168
 169 config DYNAMIC_DEBUG_CORE
 170         bool "Enable core function of dynamic debug support"
 171         depends on PRINTK
 172         depends on (DEBUG_FS || PROC_FS)
 173         help
 174           Enable core functional support of dynamic debug. It is useful
 175           when you want to tie dynamic debug to your kernel modules with
 176           DYNAMIC_DEBUG_MODULE defined for each of them, especially for
 177           the case of embedded system where the kernel image size is
 178           sensitive for people.
 179
 180 config SYMBOLIC_ERRNAME
 181         bool "Support symbolic error names in printf"
 182         default y if PRINTK
 183         help
 184           If you say Y here, the kernel's printf implementation will
 185           be able to print symbolic error names such as ENOSPC instead
 186           of the number 28. It makes the kernel image slightly larger
 187           (about 3KB), but can make the kernel logs easier to read.
 188
 189 config DEBUG_BUGVERBOSE
 190         bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
 191         depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
 192         default y
 193         help
 194           Say Y here to make BUG() panics output the file name and line number
 195           of the BUG call as well as the EIP and oops trace.  This aids
 196           debugging but costs about 70-100K of memory.
 197
 198 endmenu # "printk and dmesg options"
 199
 200 menu "Compile-time checks and compiler options"
 201
 202 config DEBUG_INFO
 203         bool "Compile the kernel with debug info"
 204         depends on DEBUG_KERNEL && !COMPILE_TEST
 205         help
 206           If you say Y here the resulting kernel image will include
 207           debugging info resulting in a larger kernel image.
 208           This adds debug symbols to the kernel and modules (gcc -g), and
 209           is needed if you intend to use kernel crashdump or binary object
 210           tools like crash, kgdb, LKCD, gdb, etc on the kernel.
 211           Say Y here only if you plan to debug the kernel.
 212
 213           If unsure, say N.
 214
 215 config DEBUG_INFO_REDUCED
 216         bool "Reduce debugging information"
 217         depends on DEBUG_INFO
 218         help
 219           If you say Y here gcc is instructed to generate less debugging
 220           information for structure types. This means that tools that
 221           need full debugging information (like kgdb or systemtap) won't
 222           be happy. But if you merely need debugging information to
 223           resolve line numbers there is no loss. Advantage is that
 224           build directory object sizes shrink dramatically over a full
 225           DEBUG_INFO build and compile times are reduced too.
 226           Only works with newer gcc versions.
 227
 228 config DEBUG_INFO_COMPRESSED
 229         bool "Compressed debugging information"
 230         depends on DEBUG_INFO
 231         depends on $(cc-option,-gz=zlib)
 232         depends on $(as-option,-Wa$(comma)--compress-debug-sections=zlib)
 233         depends on $(ld-option,--compress-debug-sections=zlib)
 234         help
 235           Compress the debug information using zlib.  Requires GCC 5.0+ or Clang
 236           5.0+, binutils 2.26+, and zlib.
 237
 238           Users of dpkg-deb via scripts/package/builddeb may find an increase in
 239           size of their debug .deb packages with this config set, due to the
 240           debug info being compressed with zlib, then the object files being
 241           recompressed with a different compression scheme. But this is still
 242           preferable to setting $KDEB_COMPRESS to "none" which would be even
 243           larger.
 244
 245 config DEBUG_INFO_SPLIT
 246         bool "Produce split debuginfo in .dwo files"
 247         depends on DEBUG_INFO
 248         depends on $(cc-option,-gsplit-dwarf)
 249         help
 250           Generate debug info into separate .dwo files. This significantly
 251           reduces the build directory size for builds with DEBUG_INFO,
 252           because it stores the information only once on disk in .dwo
 253           files instead of multiple times in object files and executables.
 254           In addition the debug information is also compressed.
 255
 256           Requires recent gcc (4.7+) and recent gdb/binutils.
 257           Any tool that packages or reads debug information would need
 258           to know about the .dwo files and include them.
 259           Incompatible with older versions of ccache.
 260
 261 config DEBUG_INFO_DWARF4
 262         bool "Generate dwarf4 debuginfo"
 263         depends on DEBUG_INFO
 264         depends on $(cc-option,-gdwarf-4)
 265         help
 266           Generate dwarf4 debug info. This requires recent versions
 267           of gcc and gdb. It makes the debug information larger.
 268           But it significantly improves the success of resolving
 269           variables in gdb on optimized code.
 270
 271 config DEBUG_INFO_BTF
 272         bool "Generate BTF typeinfo"
 273         depends on DEBUG_INFO
 274         depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED
 275         depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST
 276         help
 277           Generate deduplicated BTF type information from DWARF debug info.
 278           Turning this on expects presence of pahole tool, which will convert
 279           DWARF type info into equivalent deduplicated BTF type info.
 280
 281 config GDB_SCRIPTS
 282         bool "Provide GDB scripts for kernel debugging"
 283         depends on DEBUG_INFO
 284         help
 285           This creates the required links to GDB helper scripts in the
 286           build directory. If you load vmlinux into gdb, the helper
 287           scripts will be automatically imported by gdb as well, and
 288           additional functions are available to analyze a Linux kernel
 289           instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
 290           for further details.
 291
 292 config ENABLE_MUST_CHECK
 293         bool "Enable __must_check logic"
 294         default y
 295         help
 296           Enable the __must_check logic in the kernel build.  Disable this to
 297           suppress the "warning: ignoring return value of 'foo', declared with
 298           attribute warn_unused_result" messages.
 299
 300 config FRAME_WARN
 301         int "Warn for stack frames larger than"
 302         range 0 8192
 303         default 2048 if GCC_PLUGIN_LATENT_ENTROPY
 304         default 1280 if (!64BIT && PARISC)
 305         default 1024 if (!64BIT && !PARISC)
 306         default 2048 if 64BIT
 307         help
 308           Tell gcc to warn at build time for stack frames larger than this.
 309           Setting this too low will cause a lot of warnings.
 310           Setting it to 0 disables the warning.
 311
 312 config STRIP_ASM_SYMS
 313         bool "Strip assembler-generated symbols during link"
 314         default n
 315         help
 316           Strip internal assembler-generated symbols during a link (symbols
 317           that look like '.Lxxx') so they don't pollute the output of
 318           get_wchan() and suchlike.
 319
 320 config READABLE_ASM
 321         bool "Generate readable assembler code"
 322         depends on DEBUG_KERNEL
 323         help
 324           Disable some compiler optimizations that tend to generate human unreadable
 325           assembler output. This may make the kernel slightly slower, but it helps
 326           to keep kernel developers who have to stare a lot at assembler listings
 327           sane.
 328
 329 config HEADERS_INSTALL
 330         bool "Install uapi headers to usr/include"
 331         depends on !UML
 332         help
 333           This option will install uapi headers (headers exported to user-space)
 334           into the usr/include directory for use during the kernel build.
 335           This is unneeded for building the kernel itself, but needed for some
 336           user-space program samples. It is also needed by some features such
 337           as uapi header sanity checks.
 338
 339 config DEBUG_SECTION_MISMATCH
 340         bool "Enable full Section mismatch analysis"
 341         help
 342           The section mismatch analysis checks if there are illegal
 343           references from one section to another section.
 344           During linktime or runtime, some sections are dropped;
 345           any use of code/data previously in these sections would
 346           most likely result in an oops.
 347           In the code, functions and variables are annotated with
 348           __init,, etc. (see the full list in include/linux/init.h),
 349           which results in the code/data being placed in specific sections.
 350           The section mismatch analysis is always performed after a full
 351           kernel build, and enabling this option causes the following
 352           additional step to occur:
 353           - Add the option -fno-inline-functions-called-once to gcc commands.
 354             When inlining a function annotated with __init in a non-init
 355             function, we would lose the section information and thus
 356             the analysis would not catch the illegal reference.
 357             This option tells gcc to inline less (but it does result in
 358             a larger kernel).
 359
 360 config SECTION_MISMATCH_WARN_ONLY
 361         bool "Make section mismatch errors non-fatal"
 362         default y
 363         help
 364           If you say N here, the build process will fail if there are any
 365           section mismatch, instead of just throwing warnings.
 366
 367           If unsure, say Y.
 368
 369 #
 370 # Select this config option from the architecture Kconfig, if it
 371 # is preferred to always offer frame pointers as a config
 372 # option on the architecture (regardless of KERNEL_DEBUG):
 373 #
 374 config ARCH_WANT_FRAME_POINTERS
 375         bool
 376
 377 config FRAME_POINTER
 378         bool "Compile the kernel with frame pointers"
 379         depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
 380         default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
 381         help
 382           If you say Y here the resulting kernel image will be slightly
 383           larger and slower, but it gives very useful debugging information
 384           in case of kernel bugs. (precise oopses/stacktraces/warnings)
 385
 386 config STACK_VALIDATION
 387         bool "Compile-time stack metadata validation"
 388         depends on HAVE_STACK_VALIDATION
 389         default n
 390         help
 391           Add compile-time checks to validate stack metadata, including frame
 392           pointers (if CONFIG_FRAME_POINTER is enabled).  This helps ensure
 393           that runtime stack traces are more reliable.
 394
 395           This is also a prerequisite for generation of ORC unwind data, which
 396           is needed for CONFIG_UNWINDER_ORC.
 397
 398           For more information, see
 399           tools/objtool/Documentation/stack-validation.txt.
 400
 401 config VMLINUX_VALIDATION
 402         bool
 403         depends on STACK_VALIDATION && DEBUG_ENTRY && !PARAVIRT
 404         default y
 405
 406 config DEBUG_FORCE_WEAK_PER_CPU
 407         bool "Force weak per-cpu definitions"
 408         depends on DEBUG_KERNEL
 409         help
 410           s390 and alpha require percpu variables in modules to be
 411           defined weak to work around addressing range issue which
 412           puts the following two restrictions on percpu variable
 413           definitions.
 414
 415           1. percpu symbols must be unique whether static or not
 416           2. percpu variables can't be defined inside a function
 417
 418           To ensure that generic code follows the above rules, this
 419           option forces all percpu variables to be defined as weak.
 420
 421 endmenu # "Compiler options"
 422
 423 menu "Generic Kernel Debugging Instruments"
 424
 425 config MAGIC_SYSRQ
 426         bool "Magic SysRq key"
 427         depends on !UML
 428         help
 429           If you say Y here, you will have some control over the system even
 430           if the system crashes for example during kernel debugging (e.g., you
 431           will be able to flush the buffer cache to disk, reboot the system
 432           immediately or dump some status information). This is accomplished
 433           by pressing various keys while holding SysRq (Alt+PrintScreen). It
 434           also works on a serial console (on PC hardware at least), if you
 435           send a BREAK and then within 5 seconds a command keypress. The
 436           keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
 437           Don't say Y unless you really know what this hack does.
 438
 439 config MAGIC_SYSRQ_DEFAULT_ENABLE
 440         hex "Enable magic SysRq key functions by default"
 441         depends on MAGIC_SYSRQ
 442         default 0x1
 443         help
 444           Specifies which SysRq key functions are enabled by default.
 445           This may be set to 1 or 0 to enable or disable them all, or
 446           to a bitmask as described in Documentation/admin-guide/sysrq.rst.
 447
 448 config MAGIC_SYSRQ_SERIAL
 449         bool "Enable magic SysRq key over serial"
 450         depends on MAGIC_SYSRQ
 451         default y
 452         help
 453           Many embedded boards have a disconnected TTL level serial which can
 454           generate some garbage that can lead to spurious false sysrq detects.
 455           This option allows you to decide whether you want to enable the
 456           magic SysRq key.
 457
 458 config MAGIC_SYSRQ_SERIAL_SEQUENCE
 459         string "Char sequence that enables magic SysRq over serial"
 460         depends on MAGIC_SYSRQ_SERIAL
 461         default ""
 462         help
 463           Specifies a sequence of characters that can follow BREAK to enable
 464           SysRq on a serial console.
 465
 466           If unsure, leave an empty string and the option will not be enabled.
 467
 468 config DEBUG_FS
 469         bool "Debug Filesystem"
 470         help
 471           debugfs is a virtual file system that kernel developers use to put
 472           debugging files into.  Enable this option to be able to read and
 473           write to these files.
 474
 475           For detailed documentation on the debugfs API, see
 476           Documentation/filesystems/.
 477
 478           If unsure, say N.
 479
 480 source "lib/Kconfig.kgdb"
 481
 482 source "lib/Kconfig.ubsan"
 483
 484 endmenu
 485
 486 config DEBUG_KERNEL
 487         bool "Kernel debugging"
 488         help
 489           Say Y here if you are developing drivers or trying to debug and
 490           identify kernel problems.
 491
 492 config DEBUG_MISC
 493         bool "Miscellaneous debug code"
 494         default DEBUG_KERNEL
 495         depends on DEBUG_KERNEL
 496         help
 497           Say Y here if you need to enable miscellaneous debug code that should
 498           be under a more specific debug option but isn't.
 499
 500
 501 menu "Memory Debugging"
 502
 503 source "mm/Kconfig.debug"
 504
 505 config DEBUG_OBJECTS
 506         bool "Debug object operations"
 507         depends on DEBUG_KERNEL
 508         help
 509           If you say Y here, additional code will be inserted into the
 510           kernel to track the life time of various objects and validate
 511           the operations on those objects.
 512
 513 config DEBUG_OBJECTS_SELFTEST
 514         bool "Debug objects selftest"
 515         depends on DEBUG_OBJECTS
 516         help
 517           This enables the selftest of the object debug code.
 518
 519 config DEBUG_OBJECTS_FREE
 520         bool "Debug objects in freed memory"
 521         depends on DEBUG_OBJECTS
 522         help
 523           This enables checks whether a k/v free operation frees an area
 524           which contains an object which has not been deactivated
 525           properly. This can make kmalloc/kfree-intensive workloads
 526           much slower.
 527
 528 config DEBUG_OBJECTS_TIMERS
 529         bool "Debug timer objects"
 530         depends on DEBUG_OBJECTS
 531         help
 532           If you say Y here, additional code will be inserted into the
 533           timer routines to track the life time of timer objects and
 534           validate the timer operations.
 535
 536 config DEBUG_OBJECTS_WORK
 537         bool "Debug work objects"
 538         depends on DEBUG_OBJECTS
 539         help
 540           If you say Y here, additional code will be inserted into the
 541           work queue routines to track the life time of work objects and
 542           validate the work operations.
 543
 544 config DEBUG_OBJECTS_RCU_HEAD
 545         bool "Debug RCU callbacks objects"
 546         depends on DEBUG_OBJECTS
 547         help
 548           Enable this to turn on debugging of RCU list heads (call_rcu() usage).
 549
 550 config DEBUG_OBJECTS_PERCPU_COUNTER
 551         bool "Debug percpu counter objects"
 552         depends on DEBUG_OBJECTS
 553         help
 554           If you say Y here, additional code will be inserted into the
 555           percpu counter routines to track the life time of percpu counter
 556           objects and validate the percpu counter operations.
 557
 558 config DEBUG_OBJECTS_ENABLE_DEFAULT
 559         int "debug_objects bootup default value (0-1)"
 560         range 0 1
 561         default "1"
 562         depends on DEBUG_OBJECTS
 563         help
 564           Debug objects boot parameter default value
 565
 566 config DEBUG_SLAB
 567         bool "Debug slab memory allocations"
 568         depends on DEBUG_KERNEL && SLAB
 569         help
 570           Say Y here to have the kernel do limited verification on memory
 571           allocation as well as poisoning memory on free to catch use of freed
 572           memory. This can make kmalloc/kfree-intensive workloads much slower.
 573
 574 config SLUB_DEBUG_ON
 575         bool "SLUB debugging on by default"
 576         depends on SLUB && SLUB_DEBUG
 577         default n
 578         help
 579           Boot with debugging on by default. SLUB boots by default with
 580           the runtime debug capabilities switched off. Enabling this is
 581           equivalent to specifying the "slub_debug" parameter on boot.
 582           There is no support for more fine grained debug control like
 583           possible with slub_debug=xxx. SLUB debugging may be switched
 584           off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
 585           "slub_debug=-".
 586
 587 config SLUB_STATS
 588         default n
 589         bool "Enable SLUB performance statistics"
 590         depends on SLUB && SYSFS
 591         help
 592           SLUB statistics are useful to debug SLUBs allocation behavior in
 593           order find ways to optimize the allocator. This should never be
 594           enabled for production use since keeping statistics slows down
 595           the allocator by a few percentage points. The slabinfo command
 596           supports the determination of the most active slabs to figure
 597           out which slabs are relevant to a particular load.
 598           Try running: slabinfo -DA
 599
 600 config HAVE_DEBUG_KMEMLEAK
 601         bool
 602
 603 config DEBUG_KMEMLEAK
 604         bool "Kernel memory leak detector"
 605         depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
 606         select DEBUG_FS
 607         select STACKTRACE if STACKTRACE_SUPPORT
 608         select KALLSYMS
 609         select CRC32
 610         help
 611           Say Y here if you want to enable the memory leak
 612           detector. The memory allocation/freeing is traced in a way
 613           similar to the Boehm's conservative garbage collector, the
 614           difference being that the orphan objects are not freed but
 615           only shown in /sys/kernel/debug/kmemleak. Enabling this
 616           feature will introduce an overhead to memory
 617           allocations. See Documentation/dev-tools/kmemleak.rst for more
 618           details.
 619
 620           Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
 621           of finding leaks due to the slab objects poisoning.
 622
 623           In order to access the kmemleak file, debugfs needs to be
 624           mounted (usually at /sys/kernel/debug).
 625
 626 config DEBUG_KMEMLEAK_MEM_POOL_SIZE
 627         int "Kmemleak memory pool size"
 628         depends on DEBUG_KMEMLEAK
 629         range 200 1000000
 630         default 16000
 631         help
 632           Kmemleak must track all the memory allocations to avoid
 633           reporting false positives. Since memory may be allocated or
 634           freed before kmemleak is fully initialised, use a static pool
 635           of metadata objects to track such callbacks. After kmemleak is
 636           fully initialised, this memory pool acts as an emergency one
 637           if slab allocations fail.
 638
 639 config DEBUG_KMEMLEAK_TEST
 640         tristate "Simple test for the kernel memory leak detector"
 641         depends on DEBUG_KMEMLEAK && m
 642         help
 643           This option enables a module that explicitly leaks memory.
 644
 645           If unsure, say N.
 646
 647 config DEBUG_KMEMLEAK_DEFAULT_OFF
 648         bool "Default kmemleak to off"
 649         depends on DEBUG_KMEMLEAK
 650         help
 651           Say Y here to disable kmemleak by default. It can then be enabled
 652           on the command line via kmemleak=on.
 653
 654 config DEBUG_KMEMLEAK_AUTO_SCAN
 655         bool "Enable kmemleak auto scan thread on boot up"
 656         default y
 657         depends on DEBUG_KMEMLEAK
 658         help
 659           Depending on the cpu, kmemleak scan may be cpu intensive and can
 660           stall user tasks at times. This option enables/disables automatic
 661           kmemleak scan at boot up.
 662
 663           Say N here to disable kmemleak auto scan thread to stop automatic
 664           scanning. Disabling this option disables automatic reporting of
 665           memory leaks.
 666
 667           If unsure, say Y.
 668
 669 config DEBUG_STACK_USAGE
 670         bool "Stack utilization instrumentation"
 671         depends on DEBUG_KERNEL && !IA64
 672         help
 673           Enables the display of the minimum amount of free stack which each
 674           task has ever had available in the sysrq-T and sysrq-P debug output.
 675
 676           This option will slow down process creation somewhat.
 677
 678 config SCHED_STACK_END_CHECK
 679         bool "Detect stack corruption on calls to schedule()"
 680         depends on DEBUG_KERNEL
 681         default n
 682         help
 683           This option checks for a stack overrun on calls to schedule().
 684           If the stack end location is found to be over written always panic as
 685           the content of the corrupted region can no longer be trusted.
 686           This is to ensure no erroneous behaviour occurs which could result in
 687           data corruption or a sporadic crash at a later stage once the region
 688           is examined. The runtime overhead introduced is minimal.
 689
 690 config ARCH_HAS_DEBUG_VM_PGTABLE
 691         bool
 692         help
 693           An architecture should select this when it can successfully
 694           build and run DEBUG_VM_PGTABLE.
 695
 696 config DEBUG_VM
 697         bool "Debug VM"
 698         depends on DEBUG_KERNEL
 699         help
 700           Enable this to turn on extended checks in the virtual-memory system
 701           that may impact performance.
 702
 703           If unsure, say N.
 704
 705 config DEBUG_VM_VMACACHE
 706         bool "Debug VMA caching"
 707         depends on DEBUG_VM
 708         help
 709           Enable this to turn on VMA caching debug information. Doing so
 710           can cause significant overhead, so only enable it in non-production
 711           environments.
 712
 713           If unsure, say N.
 714
 715 config DEBUG_VM_RB
 716         bool "Debug VM red-black trees"
 717         depends on DEBUG_VM
 718         help
 719           Enable VM red-black tree debugging information and extra validations.
 720
 721           If unsure, say N.
 722
 723 config DEBUG_VM_PGFLAGS
 724         bool "Debug page-flags operations"
 725         depends on DEBUG_VM
 726         help
 727           Enables extra validation on page flags operations.
 728
 729           If unsure, say N.
 730
 731 config DEBUG_VM_PGTABLE
 732         bool "Debug arch page table for semantics compliance"
 733         depends on MMU
 734         depends on ARCH_HAS_DEBUG_VM_PGTABLE
 735         default y if DEBUG_VM
 736         help
 737           This option provides a debug method which can be used to test
 738           architecture page table helper functions on various platforms in
 739           verifying if they comply with expected generic MM semantics. This
 740           will help architecture code in making sure that any changes or
 741           new additions of these helpers still conform to expected
 742           semantics of the generic MM. Platforms will have to opt in for
 743           this through ARCH_HAS_DEBUG_VM_PGTABLE.
 744
 745           If unsure, say N.
 746
 747 config ARCH_HAS_DEBUG_VIRTUAL
 748         bool
 749
 750 config DEBUG_VIRTUAL
 751         bool "Debug VM translations"
 752         depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
 753         help
 754           Enable some costly sanity checks in virtual to page code. This can
 755           catch mistakes with virt_to_page() and friends.
 756
 757           If unsure, say N.
 758
 759 config DEBUG_NOMMU_REGIONS
 760         bool "Debug the global anon/private NOMMU mapping region tree"
 761         depends on DEBUG_KERNEL && !MMU
 762         help
 763           This option causes the global tree of anonymous and private mapping
 764           regions to be regularly checked for invalid topology.
 765
 766 config DEBUG_MEMORY_INIT
 767         bool "Debug memory initialisation" if EXPERT
 768         default !EXPERT
 769         help
 770           Enable this for additional checks during memory initialisation.
 771           The sanity checks verify aspects of the VM such as the memory model
 772           and other information provided by the architecture. Verbose
 773           information will be printed at KERN_DEBUG loglevel depending
 774           on the mminit_loglevel= command-line option.
 775
 776           If unsure, say Y
 777
 778 config MEMORY_NOTIFIER_ERROR_INJECT
 779         tristate "Memory hotplug notifier error injection module"
 780         depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
 781         help
 782           This option provides the ability to inject artificial errors to
 783           memory hotplug notifier chain callbacks.  It is controlled through
 784           debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
 785
 786           If the notifier call chain should be failed with some events
 787           notified, write the error code to "actions/<notifier event>/error".
 788
 789           Example: Inject memory hotplug offline error (-12 == -ENOMEM)
 790
 791           # cd /sys/kernel/debug/notifier-error-inject/memory
 792           # echo -12 > actions/MEM_GOING_OFFLINE/error
 793           # echo offline > /sys/devices/system/memory/memoryXXX/state
 794           bash: echo: write error: Cannot allocate memory
 795
 796           To compile this code as a module, choose M here: the module will
 797           be called memory-notifier-error-inject.
 798
 799           If unsure, say N.
 800
 801 config DEBUG_PER_CPU_MAPS
 802         bool "Debug access to per_cpu maps"
 803         depends on DEBUG_KERNEL
 804         depends on SMP
 805         help
 806           Say Y to verify that the per_cpu map being accessed has
 807           been set up. This adds a fair amount of code to kernel memory
 808           and decreases performance.
 809
 810           Say N if unsure.
 811
 812 config DEBUG_HIGHMEM
 813         bool "Highmem debugging"
 814         depends on DEBUG_KERNEL && HIGHMEM
 815         help
 816           This option enables additional error checking for high memory
 817           systems.  Disable for production systems.
 818
 819 config HAVE_DEBUG_STACKOVERFLOW
 820         bool
 821
 822 config DEBUG_STACKOVERFLOW
 823         bool "Check for stack overflows"
 824         depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
 825         help
 826           Say Y here if you want to check for overflows of kernel, IRQ
 827           and exception stacks (if your architecture uses them). This
 828           option will show detailed messages if free stack space drops
 829           below a certain limit.
 830
 831           These kinds of bugs usually occur when call-chains in the
 832           kernel get too deep, especially when interrupts are
 833           involved.
 834
 835           Use this in cases where you see apparently random memory
 836           corruption, especially if it appears in 'struct thread_info'
 837
 838           If in doubt, say "N".
 839
 840 source "lib/Kconfig.kasan"
 841
 842 endmenu # "Memory Debugging"
 843
 844 config DEBUG_SHIRQ
 845         bool "Debug shared IRQ handlers"
 846         depends on DEBUG_KERNEL
 847         help
 848           Enable this to generate a spurious interrupt as soon as a shared
 849           interrupt handler is registered, and just before one is deregistered.
 850           Drivers ought to be able to handle interrupts coming in at those
 851           points; some don't and need to be caught.
 852
 853 menu "Debug Oops, Lockups and Hangs"
 854
 855 config PANIC_ON_OOPS
 856         bool "Panic on Oops"
 857         help
 858           Say Y here to enable the kernel to panic when it oopses. This
 859           has the same effect as setting oops=panic on the kernel command
 860           line.
 861
 862           This feature is useful to ensure that the kernel does not do
 863           anything erroneous after an oops which could result in data
 864           corruption or other issues.
 865
 866           Say N if unsure.
 867
 868 config PANIC_ON_OOPS_VALUE
 869         int
 870         range 0 1
 871         default 0 if !PANIC_ON_OOPS
 872         default 1 if PANIC_ON_OOPS
 873
 874 config PANIC_TIMEOUT
 875         int "panic timeout"
 876         default 0
 877         help
 878           Set the timeout value (in seconds) until a reboot occurs when the
 879           the kernel panics. If n = 0, then we wait forever. A timeout
 880           value n > 0 will wait n seconds before rebooting, while a timeout
 881           value n < 0 will reboot immediately.
 882
 883 config LOCKUP_DETECTOR
 884         bool
 885
 886 config SOFTLOCKUP_DETECTOR
 887         bool "Detect Soft Lockups"
 888         depends on DEBUG_KERNEL && !S390
 889         select LOCKUP_DETECTOR
 890         help
 891           Say Y here to enable the kernel to act as a watchdog to detect
 892           soft lockups.
 893
 894           Softlockups are bugs that cause the kernel to loop in kernel
 895           mode for more than 20 seconds, without giving other tasks a
 896           chance to run.  The current stack trace is displayed upon
 897           detection and the system will stay locked up.
 898
 899 config BOOTPARAM_SOFTLOCKUP_PANIC
 900         bool "Panic (Reboot) On Soft Lockups"
 901         depends on SOFTLOCKUP_DETECTOR
 902         help
 903           Say Y here to enable the kernel to panic on "soft lockups",
 904           which are bugs that cause the kernel to loop in kernel
 905           mode for more than 20 seconds (configurable using the watchdog_thresh
 906           sysctl), without giving other tasks a chance to run.
 907
 908           The panic can be used in combination with panic_timeout,
 909           to cause the system to reboot automatically after a
 910           lockup has been detected. This feature is useful for
 911           high-availability systems that have uptime guarantees and
 912           where a lockup must be resolved ASAP.
 913
 914           Say N if unsure.
 915
 916 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
 917         int
 918         depends on SOFTLOCKUP_DETECTOR
 919         range 0 1
 920         default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
 921         default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
 922
 923 config HARDLOCKUP_DETECTOR_PERF
 924         bool
 925         select SOFTLOCKUP_DETECTOR
 926
 927 #
 928 # Enables a timestamp based low pass filter to compensate for perf based
 929 # hard lockup detection which runs too fast due to turbo modes.
 930 #
 931 config HARDLOCKUP_CHECK_TIMESTAMP
 932         bool
 933
 934 #
 935 # arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard
 936 # lockup detector rather than the perf based detector.
 937 #
 938 config HARDLOCKUP_DETECTOR
 939         bool "Detect Hard Lockups"
 940         depends on DEBUG_KERNEL && !S390
 941         depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH
 942         select LOCKUP_DETECTOR
 943         select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF
 944         select HARDLOCKUP_DETECTOR_ARCH if HAVE_HARDLOCKUP_DETECTOR_ARCH
 945         help
 946           Say Y here to enable the kernel to act as a watchdog to detect
 947           hard lockups.
 948
 949           Hardlockups are bugs that cause the CPU to loop in kernel mode
 950           for more than 10 seconds, without letting other interrupts have a
 951           chance to run.  The current stack trace is displayed upon detection
 952           and the system will stay locked up.
 953
 954 config BOOTPARAM_HARDLOCKUP_PANIC
 955         bool "Panic (Reboot) On Hard Lockups"
 956         depends on HARDLOCKUP_DETECTOR
 957         help
 958           Say Y here to enable the kernel to panic on "hard lockups",
 959           which are bugs that cause the kernel to loop in kernel
 960           mode with interrupts disabled for more than 10 seconds (configurable
 961           using the watchdog_thresh sysctl).
 962
 963           Say N if unsure.
 964
 965 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
 966         int
 967         depends on HARDLOCKUP_DETECTOR
 968         range 0 1
 969         default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
 970         default 1 if BOOTPARAM_HARDLOCKUP_PANIC
 971
 972 config DETECT_HUNG_TASK
 973         bool "Detect Hung Tasks"
 974         depends on DEBUG_KERNEL
 975         default SOFTLOCKUP_DETECTOR
 976         help
 977           Say Y here to enable the kernel to detect "hung tasks",
 978           which are bugs that cause the task to be stuck in
 979           uninterruptible "D" state indefinitely.
 980
 981           When a hung task is detected, the kernel will print the
 982           current stack trace (which you should report), but the
 983           task will stay in uninterruptible state. If lockdep is
 984           enabled then all held locks will also be reported. This
 985           feature has negligible overhead.
 986
 987 config DEFAULT_HUNG_TASK_TIMEOUT
 988         int "Default timeout for hung task detection (in seconds)"
 989         depends on DETECT_HUNG_TASK
 990         default 120
 991         help
 992           This option controls the default timeout (in seconds) used
 993           to determine when a task has become non-responsive and should
 994           be considered hung.
 995
 996           It can be adjusted at runtime via the kernel.hung_task_timeout_secs
 997           sysctl or by writing a value to
 998           /proc/sys/kernel/hung_task_timeout_secs.
 999
1000           A timeout of 0 disables the check.  The default is two minutes.
1001           Keeping the default should be fine in most cases.
1002
1003 config BOOTPARAM_HUNG_TASK_PANIC
1004         bool "Panic (Reboot) On Hung Tasks"
1005         depends on DETECT_HUNG_TASK
1006         help
1007           Say Y here to enable the kernel to panic on "hung tasks",
1008           which are bugs that cause the kernel to leave a task stuck
1009           in uninterruptible "D" state.
1010
1011           The panic can be used in combination with panic_timeout,
1012           to cause the system to reboot automatically after a
1013           hung task has been detected. This feature is useful for
1014           high-availability systems that have uptime guarantees and
1015           where a hung tasks must be resolved ASAP.
1016
1017           Say N if unsure.
1018
1019 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
1020         int
1021         depends on DETECT_HUNG_TASK
1022         range 0 1
1023         default 0 if !BOOTPARAM_HUNG_TASK_PANIC
1024         default 1 if BOOTPARAM_HUNG_TASK_PANIC
1025
1026 config WQ_WATCHDOG
1027         bool "Detect Workqueue Stalls"
1028         depends on DEBUG_KERNEL
1029         help
1030           Say Y here to enable stall detection on workqueues.  If a
1031           worker pool doesn't make forward progress on a pending work
1032           item for over a given amount of time, 30s by default, a
1033           warning message is printed along with dump of workqueue
1034           state.  This can be configured through kernel parameter
1035           "workqueue.watchdog_thresh" and its sysfs counterpart.
1036
1037 config TEST_LOCKUP
1038         tristate "Test module to generate lockups"
1039         help
1040           This builds the "test_lockup" module that helps to make sure
1041           that watchdogs and lockup detectors are working properly.
1042
1043           Depending on module parameters it could emulate soft or hard
1044           lockup, "hung task", or locking arbitrary lock for a long time.
1045           Also it could generate series of lockups with cooling-down periods.
1046
1047           If unsure, say N.
1048
1049 endmenu # "Debug lockups and hangs"
1050
1051 menu "Scheduler Debugging"
1052
1053 config SCHED_DEBUG
1054         bool "Collect scheduler debugging info"
1055         depends on DEBUG_KERNEL && PROC_FS
1056         default y
1057         help
1058           If you say Y here, the /proc/sched_debug file will be provided
1059           that can help debug the scheduler. The runtime overhead of this
1060           option is minimal.
1061
1062 config SCHED_INFO
1063         bool
1064         default n
1065
1066 config SCHEDSTATS
1067         bool "Collect scheduler statistics"
1068         depends on DEBUG_KERNEL && PROC_FS
1069         select SCHED_INFO
1070         help
1071           If you say Y here, additional code will be inserted into the
1072           scheduler and related routines to collect statistics about
1073           scheduler behavior and provide them in /proc/schedstat.  These
1074           stats may be useful for both tuning and debugging the scheduler
1075           If you aren't debugging the scheduler or trying to tune a specific
1076           application, you can say N to avoid the very slight overhead
1077           this adds.
1078
1079 endmenu
1080
1081 config DEBUG_TIMEKEEPING
1082         bool "Enable extra timekeeping sanity checking"
1083         help
1084           This option will enable additional timekeeping sanity checks
1085           which may be helpful when diagnosing issues where timekeeping
1086           problems are suspected.
1087
1088           This may include checks in the timekeeping hotpaths, so this
1089           option may have a (very small) performance impact to some
1090           workloads.
1091
1092           If unsure, say N.
1093
1094 config DEBUG_PREEMPT
1095         bool "Debug preemptible kernel"
1096         depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT
1097         default y
1098         help
1099           If you say Y here then the kernel will use a debug variant of the
1100           commonly used smp_processor_id() function and will print warnings
1101           if kernel code uses it in a preemption-unsafe way. Also, the kernel
1102           will detect preemption count underflows.
1103
1104 menu "Lock Debugging (spinlocks, mutexes, etc...)"
1105
1106 config LOCK_DEBUGGING_SUPPORT
1107         bool
1108         depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1109         default y
1110
1111 config PROVE_LOCKING
1112         bool "Lock debugging: prove locking correctness"
1113         depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1114         select LOCKDEP
1115         select DEBUG_SPINLOCK
1116         select DEBUG_MUTEXES
1117         select DEBUG_RT_MUTEXES if RT_MUTEXES
1118         select DEBUG_RWSEMS
1119         select DEBUG_WW_MUTEX_SLOWPATH
1120         select DEBUG_LOCK_ALLOC
1121         select TRACE_IRQFLAGS
1122         default n
1123         help
1124          This feature enables the kernel to prove that all locking
1125          that occurs in the kernel runtime is mathematically
1126          correct: that under no circumstance could an arbitrary (and
1127          not yet triggered) combination of observed locking
1128          sequences (on an arbitrary number of CPUs, running an
1129          arbitrary number of tasks and interrupt contexts) cause a
1130          deadlock.
1131
1132          In short, this feature enables the kernel to report locking
1133          related deadlocks before they actually occur.
1134
1135          The proof does not depend on how hard and complex a
1136          deadlock scenario would be to trigger: how many
1137          participant CPUs, tasks and irq-contexts would be needed
1138          for it to trigger. The proof also does not depend on
1139          timing: if a race and a resulting deadlock is possible
1140          theoretically (no matter how unlikely the race scenario
1141          is), it will be proven so and will immediately be
1142          reported by the kernel (once the event is observed that
1143          makes the deadlock theoretically possible).
1144
1145          If a deadlock is impossible (i.e. the locking rules, as
1146          observed by the kernel, are mathematically correct), the
1147          kernel reports nothing.
1148
1149          NOTE: this feature can also be enabled for rwlocks, mutexes
1150          and rwsems - in which case all dependencies between these
1151          different locking variants are observed and mapped too, and
1152          the proof of observed correctness is also maintained for an
1153          arbitrary combination of these separate locking variants.
1154
1155          For more details, see Documentation/locking/lockdep-design.rst.
1156
1157 config PROVE_RAW_LOCK_NESTING
1158         bool "Enable raw_spinlock - spinlock nesting checks"
1159         depends on PROVE_LOCKING
1160         default n
1161         help
1162          Enable the raw_spinlock vs. spinlock nesting checks which ensure
1163          that the lock nesting rules for PREEMPT_RT enabled kernels are
1164          not violated.
1165
1166          NOTE: There are known nesting problems. So if you enable this
1167          option expect lockdep splats until these problems have been fully
1168          addressed which is work in progress. This config switch allows to
1169          identify and analyze these problems. It will be removed and the
1170          check permanentely enabled once the main issues have been fixed.
1171
1172          If unsure, select N.
1173
1174 config LOCK_STAT
1175         bool "Lock usage statistics"
1176         depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1177         select LOCKDEP
1178         select DEBUG_SPINLOCK
1179         select DEBUG_MUTEXES
1180         select DEBUG_RT_MUTEXES if RT_MUTEXES
1181         select DEBUG_LOCK_ALLOC
1182         default n
1183         help
1184          This feature enables tracking lock contention points
1185
1186          For more details, see Documentation/locking/lockstat.rst
1187
1188          This also enables lock events required by "perf lock",
1189          subcommand of perf.
1190          If you want to use "perf lock", you also need to turn on
1191          CONFIG_EVENT_TRACING.
1192
1193          CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1194          (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1195
1196 config DEBUG_RT_MUTEXES
1197         bool "RT Mutex debugging, deadlock detection"
1198         depends on DEBUG_KERNEL && RT_MUTEXES
1199         help
1200          This allows rt mutex semantics violations and rt mutex related
1201          deadlocks (lockups) to be detected and reported automatically.
1202
1203 config DEBUG_SPINLOCK
1204         bool "Spinlock and rw-lock debugging: basic checks"
1205         depends on DEBUG_KERNEL
1206         select UNINLINE_SPIN_UNLOCK
1207         help
1208           Say Y here and build SMP to catch missing spinlock initialization
1209           and certain other kinds of spinlock errors commonly made.  This is
1210           best used in conjunction with the NMI watchdog so that spinlock
1211           deadlocks are also debuggable.
1212
1213 config DEBUG_MUTEXES
1214         bool "Mutex debugging: basic checks"
1215         depends on DEBUG_KERNEL
1216         help
1217          This feature allows mutex semantics violations to be detected and
1218          reported.
1219
1220 config DEBUG_WW_MUTEX_SLOWPATH
1221         bool "Wait/wound mutex debugging: Slowpath testing"
1222         depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1223         select DEBUG_LOCK_ALLOC
1224         select DEBUG_SPINLOCK
1225         select DEBUG_MUTEXES
1226         help
1227          This feature enables slowpath testing for w/w mutex users by
1228          injecting additional -EDEADLK wound/backoff cases. Together with
1229          the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1230          will test all possible w/w mutex interface abuse with the
1231          exception of simply not acquiring all the required locks.
1232          Note that this feature can introduce significant overhead, so
1233          it really should not be enabled in a production or distro kernel,
1234          even a debug kernel.  If you are a driver writer, enable it.  If
1235          you are a distro, do not.
1236
1237 config DEBUG_RWSEMS
1238         bool "RW Semaphore debugging: basic checks"
1239         depends on DEBUG_KERNEL
1240         help
1241           This debugging feature allows mismatched rw semaphore locks
1242           and unlocks to be detected and reported.
1243
1244 config DEBUG_LOCK_ALLOC
1245         bool "Lock debugging: detect incorrect freeing of live locks"
1246         depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1247         select DEBUG_SPINLOCK
1248         select DEBUG_MUTEXES
1249         select DEBUG_RT_MUTEXES if RT_MUTEXES
1250         select LOCKDEP
1251         help
1252          This feature will check whether any held lock (spinlock, rwlock,
1253          mutex or rwsem) is incorrectly freed by the kernel, via any of the
1254          memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1255          vfree(), etc.), whether a live lock is incorrectly reinitialized via
1256          spin_lock_init()/mutex_init()/etc., or whether there is any lock
1257          held during task exit.
1258
1259 config LOCKDEP
1260         bool
1261         depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1262         select STACKTRACE
1263         select FRAME_POINTER if !MIPS && !PPC && !ARM && !S390 && !MICROBLAZE && !ARC && !X86
1264         select KALLSYMS
1265         select KALLSYMS_ALL
1266
1267 config LOCKDEP_SMALL
1268         bool
1269
1270 config DEBUG_LOCKDEP
1271         bool "Lock dependency engine debugging"
1272         depends on DEBUG_KERNEL && LOCKDEP
1273         help
1274           If you say Y here, the lock dependency engine will do
1275           additional runtime checks to debug itself, at the price
1276           of more runtime overhead.
1277
1278 config DEBUG_ATOMIC_SLEEP
1279         bool "Sleep inside atomic section checking"
1280         select PREEMPT_COUNT
1281         depends on DEBUG_KERNEL
1282         depends on !ARCH_NO_PREEMPT
1283         help
1284           If you say Y here, various routines which may sleep will become very
1285           noisy if they are called inside atomic sections: when a spinlock is
1286           held, inside an rcu read side critical section, inside preempt disabled
1287           sections, inside an interrupt, etc...
1288
1289 config DEBUG_LOCKING_API_SELFTESTS
1290         bool "Locking API boot-time self-tests"
1291         depends on DEBUG_KERNEL
1292         help
1293           Say Y here if you want the kernel to run a short self-test during
1294           bootup. The self-test checks whether common types of locking bugs
1295           are detected by debugging mechanisms or not. (if you disable
1296           lock debugging then those bugs wont be detected of course.)
1297           The following locking APIs are covered: spinlocks, rwlocks,
1298           mutexes and rwsems.
1299
1300 config LOCK_TORTURE_TEST
1301         tristate "torture tests for locking"
1302         depends on DEBUG_KERNEL
1303         select TORTURE_TEST
1304         help
1305           This option provides a kernel module that runs torture tests
1306           on kernel locking primitives.  The kernel module may be built
1307           after the fact on the running kernel to be tested, if desired.
1308
1309           Say Y here if you want kernel locking-primitive torture tests
1310           to be built into the kernel.
1311           Say M if you want these torture tests to build as a module.
1312           Say N if you are unsure.
1313
1314 config WW_MUTEX_SELFTEST
1315         tristate "Wait/wound mutex selftests"
1316         help
1317           This option provides a kernel module that runs tests on the
1318           on the struct ww_mutex locking API.
1319
1320           It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1321           with this test harness.
1322
1323           Say M if you want these self tests to build as a module.
1324           Say N if you are unsure.
1325
1326 endmenu # lock debugging
1327
1328 config TRACE_IRQFLAGS
1329         bool
1330         help
1331           Enables hooks to interrupt enabling and disabling for
1332           either tracing or lock debugging.
1333
1334 config STACKTRACE
1335         bool "Stack backtrace support"
1336         depends on STACKTRACE_SUPPORT
1337         help
1338           This option causes the kernel to create a /proc/pid/stack for
1339           every process, showing its current stack trace.
1340           It is also used by various kernel debugging features that require
1341           stack trace generation.
1342
1343 config WARN_ALL_UNSEEDED_RANDOM
1344         bool "Warn for all uses of unseeded randomness"
1345         default n
1346         help
1347           Some parts of the kernel contain bugs relating to their use of
1348           cryptographically secure random numbers before it's actually possible
1349           to generate those numbers securely. This setting ensures that these
1350           flaws don't go unnoticed, by enabling a message, should this ever
1351           occur. This will allow people with obscure setups to know when things
1352           are going wrong, so that they might contact developers about fixing
1353           it.
1354
1355           Unfortunately, on some models of some architectures getting
1356           a fully seeded CRNG is extremely difficult, and so this can
1357           result in dmesg getting spammed for a surprisingly long
1358           time.  This is really bad from a security perspective, and
1359           so architecture maintainers really need to do what they can
1360           to get the CRNG seeded sooner after the system is booted.
1361           However, since users cannot do anything actionable to
1362           address this, by default the kernel will issue only a single
1363           warning for the first use of unseeded randomness.
1364
1365           Say Y here if you want to receive warnings for all uses of
1366           unseeded randomness.  This will be of use primarily for
1367           those developers interested in improving the security of
1368           Linux kernels running on their architecture (or
1369           subarchitecture).
1370
1371 config DEBUG_KOBJECT
1372         bool "kobject debugging"
1373         depends on DEBUG_KERNEL
1374         help
1375           If you say Y here, some extra kobject debugging messages will be sent
1376           to the syslog.
1377
1378 config DEBUG_KOBJECT_RELEASE
1379         bool "kobject release debugging"
1380         depends on DEBUG_OBJECTS_TIMERS
1381         help
1382           kobjects are reference counted objects.  This means that their
1383           last reference count put is not predictable, and the kobject can
1384           live on past the point at which a driver decides to drop it's
1385           initial reference to the kobject gained on allocation.  An
1386           example of this would be a struct device which has just been
1387           unregistered.
1388
1389           However, some buggy drivers assume that after such an operation,
1390           the memory backing the kobject can be immediately freed.  This
1391           goes completely against the principles of a refcounted object.
1392
1393           If you say Y here, the kernel will delay the release of kobjects
1394           on the last reference count to improve the visibility of this
1395           kind of kobject release bug.
1396
1397 config HAVE_DEBUG_BUGVERBOSE
1398         bool
1399
1400 menu "Debug kernel data structures"
1401
1402 config DEBUG_LIST
1403         bool "Debug linked list manipulation"
1404         depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION
1405         help
1406           Enable this to turn on extended checks in the linked-list
1407           walking routines.
1408
1409           If unsure, say N.
1410
1411 config DEBUG_PLIST
1412         bool "Debug priority linked list manipulation"
1413         depends on DEBUG_KERNEL
1414         help
1415           Enable this to turn on extended checks in the priority-ordered
1416           linked-list (plist) walking routines.  This checks the entire
1417           list multiple times during each manipulation.
1418
1419           If unsure, say N.
1420
1421 config DEBUG_SG
1422         bool "Debug SG table operations"
1423         depends on DEBUG_KERNEL
1424         help
1425           Enable this to turn on checks on scatter-gather tables. This can
1426           help find problems with drivers that do not properly initialize
1427           their sg tables.
1428
1429           If unsure, say N.
1430
1431 config DEBUG_NOTIFIERS
1432         bool "Debug notifier call chains"
1433         depends on DEBUG_KERNEL
1434         help
1435           Enable this to turn on sanity checking for notifier call chains.
1436           This is most useful for kernel developers to make sure that
1437           modules properly unregister themselves from notifier chains.
1438           This is a relatively cheap check but if you care about maximum
1439           performance, say N.
1440
1441 config BUG_ON_DATA_CORRUPTION
1442         bool "Trigger a BUG when data corruption is detected"
1443         select DEBUG_LIST
1444         help
1445           Select this option if the kernel should BUG when it encounters
1446           data corruption in kernel memory structures when they get checked
1447           for validity.
1448
1449           If unsure, say N.
1450
1451 endmenu
1452
1453 config DEBUG_CREDENTIALS
1454         bool "Debug credential management"
1455         depends on DEBUG_KERNEL
1456         help
1457           Enable this to turn on some debug checking for credential
1458           management.  The additional code keeps track of the number of
1459           pointers from task_structs to any given cred struct, and checks to
1460           see that this number never exceeds the usage count of the cred
1461           struct.
1462
1463           Furthermore, if SELinux is enabled, this also checks that the
1464           security pointer in the cred struct is never seen to be invalid.
1465
1466           If unsure, say N.
1467
1468 source "kernel/rcu/Kconfig.debug"
1469
1470 config DEBUG_WQ_FORCE_RR_CPU
1471         bool "Force round-robin CPU selection for unbound work items"
1472         depends on DEBUG_KERNEL
1473         default n
1474         help
1475           Workqueue used to implicitly guarantee that work items queued
1476           without explicit CPU specified are put on the local CPU.  This
1477           guarantee is no longer true and while local CPU is still
1478           preferred work items may be put on foreign CPUs.  Kernel
1479           parameter "workqueue.debug_force_rr_cpu" is added to force
1480           round-robin CPU selection to flush out usages which depend on the
1481           now broken guarantee.  This config option enables the debug
1482           feature by default.  When enabled, memory and cache locality will
1483           be impacted.
1484
1485 config DEBUG_BLOCK_EXT_DEVT
1486         bool "Force extended block device numbers and spread them"
1487         depends on DEBUG_KERNEL
1488         depends on BLOCK
1489         default n
1490         help
1491           BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1492           SOME DISTRIBUTIONS.  DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1493           YOU ARE DOING.  Distros, please enable this and fix whatever
1494           is broken.
1495
1496           Conventionally, block device numbers are allocated from
1497           predetermined contiguous area.  However, extended block area
1498           may introduce non-contiguous block device numbers.  This
1499           option forces most block device numbers to be allocated from
1500           the extended space and spreads them to discover kernel or
1501           userland code paths which assume predetermined contiguous
1502           device number allocation.
1503
1504           Note that turning on this debug option shuffles all the
1505           device numbers for all IDE and SCSI devices including libata
1506           ones, so root partition specified using device number
1507           directly (via rdev or root=MAJ:MIN) won't work anymore.
1508           Textual device names (root=/dev/sdXn) will continue to work.
1509
1510           Say N if you are unsure.
1511
1512 config CPU_HOTPLUG_STATE_CONTROL
1513         bool "Enable CPU hotplug state control"
1514         depends on DEBUG_KERNEL
1515         depends on HOTPLUG_CPU
1516         default n
1517         help
1518           Allows to write steps between "offline" and "online" to the CPUs
1519           sysfs target file so states can be stepped granular. This is a debug
1520           option for now as the hotplug machinery cannot be stopped and
1521           restarted at arbitrary points yet.
1522
1523           Say N if your are unsure.
1524
1525 config LATENCYTOP
1526         bool "Latency measuring infrastructure"
1527         depends on DEBUG_KERNEL
1528         depends on STACKTRACE_SUPPORT
1529         depends on PROC_FS
1530         select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86
1531         select KALLSYMS
1532         select KALLSYMS_ALL
1533         select STACKTRACE
1534         select SCHEDSTATS
1535         select SCHED_DEBUG
1536         help
1537           Enable this option if you want to use the LatencyTOP tool
1538           to find out which userspace is blocking on what kernel operations.
1539
1540 source "kernel/trace/Kconfig"
1541
1542 config PROVIDE_OHCI1394_DMA_INIT
1543         bool "Remote debugging over FireWire early on boot"
1544         depends on PCI && X86
1545         help
1546           If you want to debug problems which hang or crash the kernel early
1547           on boot and the crashing machine has a FireWire port, you can use
1548           this feature to remotely access the memory of the crashed machine
1549           over FireWire. This employs remote DMA as part of the OHCI1394
1550           specification which is now the standard for FireWire controllers.
1551
1552           With remote DMA, you can monitor the printk buffer remotely using
1553           firescope and access all memory below 4GB using fireproxy from gdb.
1554           Even controlling a kernel debugger is possible using remote DMA.
1555
1556           Usage:
1557
1558           If ohci1394_dma=early is used as boot parameter, it will initialize
1559           all OHCI1394 controllers which are found in the PCI config space.
1560
1561           As all changes to the FireWire bus such as enabling and disabling
1562           devices cause a bus reset and thereby disable remote DMA for all
1563           devices, be sure to have the cable plugged and FireWire enabled on
1564           the debugging host before booting the debug target for debugging.
1565
1566           This code (~1k) is freed after boot. By then, the firewire stack
1567           in charge of the OHCI-1394 controllers should be used instead.
1568
1569           See Documentation/core-api/debugging-via-ohci1394.rst for more information.
1570
1571 source "samples/Kconfig"
1572
1573 source "lib/Kconfig.kcsan"
1574
1575 config ARCH_HAS_DEVMEM_IS_ALLOWED
1576         bool
1577
1578 config STRICT_DEVMEM
1579         bool "Filter access to /dev/mem"
1580         depends on MMU && DEVMEM
1581         depends on ARCH_HAS_DEVMEM_IS_ALLOWED
1582         default y if PPC || X86 || ARM64
1583         help
1584           If this option is disabled, you allow userspace (root) access to all
1585           of memory, including kernel and userspace memory. Accidental
1586           access to this is obviously disastrous, but specific access can
1587           be used by people debugging the kernel. Note that with PAT support
1588           enabled, even in this case there are restrictions on /dev/mem
1589           use due to the cache aliasing requirements.
1590
1591           If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
1592           file only allows userspace access to PCI space and the BIOS code and
1593           data regions.  This is sufficient for dosemu and X and all common
1594           users of /dev/mem.
1595
1596           If in doubt, say Y.
1597
1598 config IO_STRICT_DEVMEM
1599         bool "Filter I/O access to /dev/mem"
1600         depends on STRICT_DEVMEM
1601         help
1602           If this option is disabled, you allow userspace (root) access to all
1603           io-memory regardless of whether a driver is actively using that
1604           range.  Accidental access to this is obviously disastrous, but
1605           specific access can be used by people debugging kernel drivers.
1606
1607           If this option is switched on, the /dev/mem file only allows
1608           userspace access to *idle* io-memory ranges (see /proc/iomem) This
1609           may break traditional users of /dev/mem (dosemu, legacy X, etc...)
1610           if the driver using a given range cannot be disabled.
1611
1612           If in doubt, say Y.
1613
1614 menu "$(SRCARCH) Debugging"
1615
1616 source "arch/$(SRCARCH)/Kconfig.debug"
1617
1618 endmenu
1619
1620 menu "Kernel Testing and Coverage"
1621
1622 source "lib/kunit/Kconfig"
1623
1624 config NOTIFIER_ERROR_INJECTION
1625         tristate "Notifier error injection"
1626         depends on DEBUG_KERNEL
1627         select DEBUG_FS
1628         help
1629           This option provides the ability to inject artificial errors to
1630           specified notifier chain callbacks. It is useful to test the error
1631           handling of notifier call chain failures.
1632
1633           Say N if unsure.
1634
1635 config PM_NOTIFIER_ERROR_INJECT
1636         tristate "PM notifier error injection module"
1637         depends on PM && NOTIFIER_ERROR_INJECTION
1638         default m if PM_DEBUG
1639         help
1640           This option provides the ability to inject artificial errors to
1641           PM notifier chain callbacks.  It is controlled through debugfs
1642           interface /sys/kernel/debug/notifier-error-inject/pm
1643
1644           If the notifier call chain should be failed with some events
1645           notified, write the error code to "actions/<notifier event>/error".
1646
1647           Example: Inject PM suspend error (-12 = -ENOMEM)
1648
1649           # cd /sys/kernel/debug/notifier-error-inject/pm/
1650           # echo -12 > actions/PM_SUSPEND_PREPARE/error
1651           # echo mem > /sys/power/state
1652           bash: echo: write error: Cannot allocate memory
1653
1654           To compile this code as a module, choose M here: the module will
1655           be called pm-notifier-error-inject.
1656
1657           If unsure, say N.
1658
1659 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1660         tristate "OF reconfig notifier error injection module"
1661         depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1662         help
1663           This option provides the ability to inject artificial errors to
1664           OF reconfig notifier chain callbacks.  It is controlled
1665           through debugfs interface under
1666           /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1667
1668           If the notifier call chain should be failed with some events
1669           notified, write the error code to "actions/<notifier event>/error".
1670
1671           To compile this code as a module, choose M here: the module will
1672           be called of-reconfig-notifier-error-inject.
1673
1674           If unsure, say N.
1675
1676 config NETDEV_NOTIFIER_ERROR_INJECT
1677         tristate "Netdev notifier error injection module"
1678         depends on NET && NOTIFIER_ERROR_INJECTION
1679         help
1680           This option provides the ability to inject artificial errors to
1681           netdevice notifier chain callbacks.  It is controlled through debugfs
1682           interface /sys/kernel/debug/notifier-error-inject/netdev
1683
1684           If the notifier call chain should be failed with some events
1685           notified, write the error code to "actions/<notifier event>/error".
1686
1687           Example: Inject netdevice mtu change error (-22 = -EINVAL)
1688
1689           # cd /sys/kernel/debug/notifier-error-inject/netdev
1690           # echo -22 > actions/NETDEV_CHANGEMTU/error
1691           # ip link set eth0 mtu 1024
1692           RTNETLINK answers: Invalid argument
1693
1694           To compile this code as a module, choose M here: the module will
1695           be called netdev-notifier-error-inject.
1696
1697           If unsure, say N.
1698
1699 config FUNCTION_ERROR_INJECTION
1700         def_bool y
1701         depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
1702
1703 config FAULT_INJECTION
1704         bool "Fault-injection framework"
1705         depends on DEBUG_KERNEL
1706         help
1707           Provide fault-injection framework.
1708           For more details, see Documentation/fault-injection/.
1709
1710 config FAILSLAB
1711         bool "Fault-injection capability for kmalloc"
1712         depends on FAULT_INJECTION
1713         depends on SLAB || SLUB
1714         help
1715           Provide fault-injection capability for kmalloc.
1716
1717 config FAIL_PAGE_ALLOC
1718         bool "Fault-injection capability for alloc_pages()"
1719         depends on FAULT_INJECTION
1720         help
1721           Provide fault-injection capability for alloc_pages().
1722
1723 config FAIL_MAKE_REQUEST
1724         bool "Fault-injection capability for disk IO"
1725         depends on FAULT_INJECTION && BLOCK
1726         help
1727           Provide fault-injection capability for disk IO.
1728
1729 config FAIL_IO_TIMEOUT
1730         bool "Fault-injection capability for faking disk interrupts"
1731         depends on FAULT_INJECTION && BLOCK
1732         help
1733           Provide fault-injection capability on end IO handling. This
1734           will make the block layer "forget" an interrupt as configured,
1735           thus exercising the error handling.
1736
1737           Only works with drivers that use the generic timeout handling,
1738           for others it wont do anything.
1739
1740 config FAIL_FUTEX
1741         bool "Fault-injection capability for futexes"
1742         select DEBUG_FS
1743         depends on FAULT_INJECTION && FUTEX
1744         help
1745           Provide fault-injection capability for futexes.
1746
1747 config FAULT_INJECTION_DEBUG_FS
1748         bool "Debugfs entries for fault-injection capabilities"
1749         depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1750         help
1751           Enable configuration of fault-injection capabilities via debugfs.
1752
1753 config FAIL_FUNCTION
1754         bool "Fault-injection capability for functions"
1755         depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
1756         help
1757           Provide function-based fault-injection capability.
1758           This will allow you to override a specific function with a return
1759           with given return value. As a result, function caller will see
1760           an error value and have to handle it. This is useful to test the
1761           error handling in various subsystems.
1762
1763 config FAIL_MMC_REQUEST
1764         bool "Fault-injection capability for MMC IO"
1765         depends on FAULT_INJECTION_DEBUG_FS && MMC
1766         help
1767           Provide fault-injection capability for MMC IO.
1768           This will make the mmc core return data errors. This is
1769           useful to test the error handling in the mmc block device
1770           and to test how the mmc host driver handles retries from
1771           the block device.
1772
1773 config FAULT_INJECTION_STACKTRACE_FILTER
1774         bool "stacktrace filter for fault-injection capabilities"
1775         depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1776         depends on !X86_64
1777         select STACKTRACE
1778         select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86
1779         help
1780           Provide stacktrace filter for fault-injection capabilities
1781
1782 config ARCH_HAS_KCOV
1783         bool
1784         help
1785           An architecture should select this when it can successfully
1786           build and run with CONFIG_KCOV. This typically requires
1787           disabling instrumentation for some early boot code.
1788
1789 config CC_HAS_SANCOV_TRACE_PC
1790         def_bool $(cc-option,-fsanitize-coverage=trace-pc)
1791
1792
1793 config KCOV
1794         bool "Code coverage for fuzzing"
1795         depends on ARCH_HAS_KCOV
1796         depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
1797         select DEBUG_FS
1798         select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
1799         help
1800           KCOV exposes kernel code coverage information in a form suitable
1801           for coverage-guided fuzzing (randomized testing).
1802
1803           If RANDOMIZE_BASE is enabled, PC values will not be stable across
1804           different machines and across reboots. If you need stable PC values,
1805           disable RANDOMIZE_BASE.
1806
1807           For more details, see Documentation/dev-tools/kcov.rst.
1808
1809 config KCOV_ENABLE_COMPARISONS
1810         bool "Enable comparison operands collection by KCOV"
1811         depends on KCOV
1812         depends on $(cc-option,-fsanitize-coverage=trace-cmp)
1813         help
1814           KCOV also exposes operands of every comparison in the instrumented
1815           code along with operand sizes and PCs of the comparison instructions.
1816           These operands can be used by fuzzing engines to improve the quality
1817           of fuzzing coverage.
1818
1819 config KCOV_INSTRUMENT_ALL
1820         bool "Instrument all code by default"
1821         depends on KCOV
1822         default y
1823         help
1824           If you are doing generic system call fuzzing (like e.g. syzkaller),
1825           then you will want to instrument the whole kernel and you should
1826           say y here. If you are doing more targeted fuzzing (like e.g.
1827           filesystem fuzzing with AFL) then you will want to enable coverage
1828           for more specific subsets of files, and should say n here.
1829
1830 config KCOV_IRQ_AREA_SIZE
1831         hex "Size of interrupt coverage collection area in words"
1832         depends on KCOV
1833         default 0x40000
1834         help
1835           KCOV uses preallocated per-cpu areas to collect coverage from
1836           soft interrupts. This specifies the size of those areas in the
1837           number of unsigned long words.
1838
1839 menuconfig RUNTIME_TESTING_MENU
1840         bool "Runtime Testing"
1841         def_bool y
1842
1843 if RUNTIME_TESTING_MENU
1844
1845 config LKDTM
1846         tristate "Linux Kernel Dump Test Tool Module"
1847         depends on DEBUG_FS
1848         help
1849         This module enables testing of the different dumping mechanisms by
1850         inducing system failures at predefined crash points.
1851         If you don't need it: say N
1852         Choose M here to compile this code as a module. The module will be
1853         called lkdtm.
1854
1855         Documentation on how to use the module can be found in
1856         Documentation/fault-injection/provoke-crashes.rst
1857
1858 config TEST_LIST_SORT
1859         tristate "Linked list sorting test"
1860         depends on DEBUG_KERNEL || m
1861         help
1862           Enable this to turn on 'list_sort()' function test. This test is
1863           executed only once during system boot (so affects only boot time),
1864           or at module load time.
1865
1866           If unsure, say N.
1867
1868 config TEST_MIN_HEAP
1869         tristate "Min heap test"
1870         depends on DEBUG_KERNEL || m
1871         help
1872           Enable this to turn on min heap function tests. This test is
1873           executed only once during system boot (so affects only boot time),
1874           or at module load time.
1875
1876           If unsure, say N.
1877
1878 config TEST_SORT
1879         tristate "Array-based sort test"
1880         depends on DEBUG_KERNEL || m
1881         help
1882           This option enables the self-test function of 'sort()' at boot,
1883           or at module load time.
1884
1885           If unsure, say N.
1886
1887 config KPROBES_SANITY_TEST
1888         bool "Kprobes sanity tests"
1889         depends on DEBUG_KERNEL
1890         depends on KPROBES
1891         help
1892           This option provides for testing basic kprobes functionality on
1893           boot. Samples of kprobe and kretprobe are inserted and
1894           verified for functionality.
1895
1896           Say N if you are unsure.
1897
1898 config BACKTRACE_SELF_TEST
1899         tristate "Self test for the backtrace code"
1900         depends on DEBUG_KERNEL
1901         help
1902           This option provides a kernel module that can be used to test
1903           the kernel stack backtrace code. This option is not useful
1904           for distributions or general kernels, but only for kernel
1905           developers working on architecture code.
1906
1907           Note that if you want to also test saved backtraces, you will
1908           have to enable STACKTRACE as well.
1909
1910           Say N if you are unsure.
1911
1912 config RBTREE_TEST
1913         tristate "Red-Black tree test"
1914         depends on DEBUG_KERNEL
1915         help
1916           A benchmark measuring the performance of the rbtree library.
1917           Also includes rbtree invariant checks.
1918
1919 config REED_SOLOMON_TEST
1920         tristate "Reed-Solomon library test"
1921         depends on DEBUG_KERNEL || m
1922         select REED_SOLOMON
1923         select REED_SOLOMON_ENC16
1924         select REED_SOLOMON_DEC16
1925         help
1926           This option enables the self-test function of rslib at boot,
1927           or at module load time.
1928
1929           If unsure, say N.
1930
1931 config INTERVAL_TREE_TEST
1932         tristate "Interval tree test"
1933         depends on DEBUG_KERNEL
1934         select INTERVAL_TREE
1935         help
1936           A benchmark measuring the performance of the interval tree library
1937
1938 config PERCPU_TEST
1939         tristate "Per cpu operations test"
1940         depends on m && DEBUG_KERNEL
1941         help
1942           Enable this option to build test module which validates per-cpu
1943           operations.
1944
1945           If unsure, say N.
1946
1947 config ATOMIC64_SELFTEST
1948         tristate "Perform an atomic64_t self-test"
1949         help
1950           Enable this option to test the atomic64_t functions at boot or
1951           at module load time.
1952
1953           If unsure, say N.
1954
1955 config ASYNC_RAID6_TEST
1956         tristate "Self test for hardware accelerated raid6 recovery"
1957         depends on ASYNC_RAID6_RECOV
1958         select ASYNC_MEMCPY
1959         help
1960           This is a one-shot self test that permutes through the
1961           recovery of all the possible two disk failure scenarios for a
1962           N-disk array.  Recovery is performed with the asynchronous
1963           raid6 recovery routines, and will optionally use an offload
1964           engine if one is available.
1965
1966           If unsure, say N.
1967
1968 config TEST_HEXDUMP
1969         tristate "Test functions located in the hexdump module at runtime"
1970
1971 config TEST_STRING_HELPERS
1972         tristate "Test functions located in the string_helpers module at runtime"
1973
1974 config TEST_STRSCPY
1975         tristate "Test strscpy*() family of functions at runtime"
1976
1977 config TEST_KSTRTOX
1978         tristate "Test kstrto*() family of functions at runtime"
1979
1980 config TEST_PRINTF
1981         tristate "Test printf() family of functions at runtime"
1982
1983 config TEST_BITMAP
1984         tristate "Test bitmap_*() family of functions at runtime"
1985         help
1986           Enable this option to test the bitmap functions at boot.
1987
1988           If unsure, say N.
1989
1990 config TEST_BITFIELD
1991         tristate "Test bitfield functions at runtime"
1992         help
1993           Enable this option to test the bitfield functions at boot.
1994
1995           If unsure, say N.
1996
1997 config TEST_UUID
1998         tristate "Test functions located in the uuid module at runtime"
1999
2000 config TEST_XARRAY
2001         tristate "Test the XArray code at runtime"
2002
2003 config TEST_OVERFLOW
2004         tristate "Test check_*_overflow() functions at runtime"
2005
2006 config TEST_RHASHTABLE
2007         tristate "Perform selftest on resizable hash table"
2008         help
2009           Enable this option to test the rhashtable functions at boot.
2010
2011           If unsure, say N.
2012
2013 config TEST_HASH
2014         tristate "Perform selftest on hash functions"
2015         help
2016           Enable this option to test the kernel's integer (<linux/hash.h>),
2017           string (<linux/stringhash.h>), and siphash (<linux/siphash.h>)
2018           hash functions on boot (or module load).
2019
2020           This is intended to help people writing architecture-specific
2021           optimized versions.  If unsure, say N.
2022
2023 config TEST_IDA
2024         tristate "Perform selftest on IDA functions"
2025
2026 config TEST_PARMAN
2027         tristate "Perform selftest on priority array manager"
2028         depends on PARMAN
2029         help
2030           Enable this option to test priority array manager on boot
2031           (or module load).
2032
2033           If unsure, say N.
2034
2035 config TEST_IRQ_TIMINGS
2036         bool "IRQ timings selftest"
2037         depends on IRQ_TIMINGS
2038         help
2039           Enable this option to test the irq timings code on boot.
2040
2041           If unsure, say N.
2042
2043 config TEST_LKM
2044         tristate "Test module loading with 'hello world' module"
2045         depends on m
2046         help
2047           This builds the "test_module" module that emits "Hello, world"
2048           on printk when loaded. It is designed to be used for basic
2049           evaluation of the module loading subsystem (for example when
2050           validating module verification). It lacks any extra dependencies,
2051           and will not normally be loaded by the system unless explicitly
2052           requested by name.
2053
2054           If unsure, say N.
2055
2056 config TEST_BITOPS
2057         tristate "Test module for compilation of bitops operations"
2058         depends on m
2059         help
2060           This builds the "test_bitops" module that is much like the
2061           TEST_LKM module except that it does a basic exercise of the
2062           set/clear_bit macros and get_count_order/long to make sure there are
2063           no compiler warnings from C=1 sparse checker or -Wextra
2064           compilations. It has no dependencies and doesn't run or load unless
2065           explicitly requested by name.  for example: modprobe test_bitops.
2066
2067           If unsure, say N.
2068
2069 config TEST_VMALLOC
2070         tristate "Test module for stress/performance analysis of vmalloc allocator"
2071         default n
2072        depends on MMU
2073         depends on m
2074         help
2075           This builds the "test_vmalloc" module that should be used for
2076           stress and performance analysis. So, any new change for vmalloc
2077           subsystem can be evaluated from performance and stability point
2078           of view.
2079
2080           If unsure, say N.
2081
2082 config TEST_USER_COPY
2083         tristate "Test user/kernel boundary protections"
2084         depends on m
2085         help
2086           This builds the "test_user_copy" module that runs sanity checks
2087           on the copy_to/from_user infrastructure, making sure basic
2088           user/kernel boundary testing is working. If it fails to load,
2089           a regression has been detected in the user/kernel memory boundary
2090           protections.
2091
2092           If unsure, say N.
2093
2094 config TEST_BPF
2095         tristate "Test BPF filter functionality"
2096         depends on m && NET
2097         help
2098           This builds the "test_bpf" module that runs various test vectors
2099           against the BPF interpreter or BPF JIT compiler depending on the
2100           current setting. This is in particular useful for BPF JIT compiler
2101           development, but also to run regression tests against changes in
2102           the interpreter code. It also enables test stubs for eBPF maps and
2103           verifier used by user space verifier testsuite.
2104
2105           If unsure, say N.
2106
2107 config TEST_BLACKHOLE_DEV
2108         tristate "Test blackhole netdev functionality"
2109         depends on m && NET
2110         help
2111           This builds the "test_blackhole_dev" module that validates the
2112           data path through this blackhole netdev.
2113
2114           If unsure, say N.
2115
2116 config FIND_BIT_BENCHMARK
2117         tristate "Test find_bit functions"
2118         help
2119           This builds the "test_find_bit" module that measure find_*_bit()
2120           functions performance.
2121
2122           If unsure, say N.
2123
2124 config TEST_FIRMWARE
2125         tristate "Test firmware loading via userspace interface"
2126         depends on FW_LOADER
2127         help
2128           This builds the "test_firmware" module that creates a userspace
2129           interface for testing firmware loading. This can be used to
2130           control the triggering of firmware loading without needing an
2131           actual firmware-using device. The contents can be rechecked by
2132           userspace.
2133
2134           If unsure, say N.
2135
2136 config TEST_SYSCTL
2137         tristate "sysctl test driver"
2138         depends on PROC_SYSCTL
2139         help
2140           This builds the "test_sysctl" module. This driver enables to test the
2141           proc sysctl interfaces available to drivers safely without affecting
2142           production knobs which might alter system functionality.
2143
2144           If unsure, say N.
2145
2146 config SYSCTL_KUNIT_TEST
2147         tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS
2148         depends on KUNIT
2149         default KUNIT_ALL_TESTS
2150         help
2151           This builds the proc sysctl unit test, which runs on boot.
2152           Tests the API contract and implementation correctness of sysctl.
2153           For more information on KUnit and unit tests in general please refer
2154           to the KUnit documentation in Documentation/dev-tools/kunit/.
2155
2156           If unsure, say N.
2157
2158 config LIST_KUNIT_TEST
2159         tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS
2160         depends on KUNIT
2161         default KUNIT_ALL_TESTS
2162         help
2163           This builds the linked list KUnit test suite.
2164           It tests that the API and basic functionality of the list_head type
2165           and associated macros.
2166
2167           KUnit tests run during boot and output the results to the debug log
2168           in TAP format (http://testanything.org/). Only useful for kernel devs
2169           running the KUnit test harness, and not intended for inclusion into a
2170           production build.
2171
2172           For more information on KUnit and unit tests in general please refer
2173           to the KUnit documentation in Documentation/dev-tools/kunit/.
2174
2175           If unsure, say N.
2176
2177 config LINEAR_RANGES_TEST
2178         tristate "KUnit test for linear_ranges"
2179         depends on KUNIT
2180         select LINEAR_RANGES
2181         help
2182           This builds the linear_ranges unit test, which runs on boot.
2183           Tests the linear_ranges logic correctness.
2184           For more information on KUnit and unit tests in general please refer
2185           to the KUnit documentation in Documentation/dev-tools/kunit/.
2186
2187           If unsure, say N.
2188
2189 config TEST_UDELAY
2190         tristate "udelay test driver"
2191         help
2192           This builds the "udelay_test" module that helps to make sure
2193           that udelay() is working properly.
2194
2195           If unsure, say N.
2196
2197 config TEST_STATIC_KEYS
2198         tristate "Test static keys"
2199         depends on m
2200         help
2201           Test the static key interfaces.
2202
2203           If unsure, say N.
2204
2205 config TEST_KMOD
2206         tristate "kmod stress tester"
2207         depends on m
2208         depends on NETDEVICES && NET_CORE && INET # for TUN
2209         depends on BLOCK
2210         select TEST_LKM
2211         select XFS_FS
2212         select TUN
2213         select BTRFS_FS
2214         help
2215           Test the kernel's module loading mechanism: kmod. kmod implements
2216           support to load modules using the Linux kernel's usermode helper.
2217           This test provides a series of tests against kmod.
2218
2219           Although technically you can either build test_kmod as a module or
2220           into the kernel we disallow building it into the kernel since
2221           it stress tests request_module() and this will very likely cause
2222           some issues by taking over precious threads available from other
2223           module load requests, ultimately this could be fatal.
2224
2225           To run tests run:
2226
2227           tools/testing/selftests/kmod/kmod.sh --help
2228
2229           If unsure, say N.
2230
2231 config TEST_DEBUG_VIRTUAL
2232         tristate "Test CONFIG_DEBUG_VIRTUAL feature"
2233         depends on DEBUG_VIRTUAL
2234         help
2235           Test the kernel's ability to detect incorrect calls to
2236           virt_to_phys() done against the non-linear part of the
2237           kernel's virtual address map.
2238
2239           If unsure, say N.
2240
2241 config TEST_MEMCAT_P
2242         tristate "Test memcat_p() helper function"
2243         help
2244           Test the memcat_p() helper for correctly merging two
2245           pointer arrays together.
2246
2247           If unsure, say N.
2248
2249 config TEST_LIVEPATCH
2250         tristate "Test livepatching"
2251         default n
2252         depends on DYNAMIC_DEBUG
2253         depends on LIVEPATCH
2254         depends on m
2255         help
2256           Test kernel livepatching features for correctness.  The tests will
2257           load test modules that will be livepatched in various scenarios.
2258
2259           To run all the livepatching tests:
2260
2261           make -C tools/testing/selftests TARGETS=livepatch run_tests
2262
2263           Alternatively, individual tests may be invoked:
2264
2265           tools/testing/selftests/livepatch/test-callbacks.sh
2266           tools/testing/selftests/livepatch/test-livepatch.sh
2267           tools/testing/selftests/livepatch/test-shadow-vars.sh
2268
2269           If unsure, say N.
2270
2271 config TEST_OBJAGG
2272         tristate "Perform selftest on object aggreration manager"
2273         default n
2274         depends on OBJAGG
2275         help
2276           Enable this option to test object aggregation manager on boot
2277           (or module load).
2278
2279
2280 config TEST_STACKINIT
2281         tristate "Test level of stack variable initialization"
2282         help
2283           Test if the kernel is zero-initializing stack variables and
2284           padding. Coverage is controlled by compiler flags,
2285           CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2286           or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2287
2288           If unsure, say N.
2289
2290 config TEST_MEMINIT
2291         tristate "Test heap/page initialization"
2292         help
2293           Test if the kernel is zero-initializing heap and page allocations.
2294           This can be useful to test init_on_alloc and init_on_free features.
2295
2296           If unsure, say N.
2297
2298 config TEST_HMM
2299         tristate "Test HMM (Heterogeneous Memory Management)"
2300         depends on TRANSPARENT_HUGEPAGE
2301         depends on DEVICE_PRIVATE
2302         select HMM_MIRROR
2303         select MMU_NOTIFIER
2304         help
2305           This is a pseudo device driver solely for testing HMM.
2306           Say M here if you want to build the HMM test module.
2307           Doing so will allow you to run tools/testing/selftest/vm/hmm-tests.
2308
2309           If unsure, say N.
2310
2311 endif # RUNTIME_TESTING_MENU
2312
2313 config MEMTEST
2314         bool "Memtest"
2315         help
2316           This option adds a kernel parameter 'memtest', which allows memtest
2317           to be set.
2318                 memtest=0, mean disabled; -- default
2319                 memtest=1, mean do 1 test pattern;
2320                 ...
2321                 memtest=17, mean do 17 test patterns.
2322           If you are unsure how to answer this question, answer N.
2323
2324
2325
2326 config HYPERV_TESTING
2327         bool "Microsoft Hyper-V driver testing"
2328         default n
2329         depends on HYPERV && DEBUG_FS
2330         help
2331           Select this option to enable Hyper-V vmbus testing.
2332
2333 endmenu # "Kernel Testing and Coverage"
2334
2335 endmenu # Kernel hacking