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 $(ld-option,--compress-debug-sections=zlib)
 233         help
 234           Compress the debug information using zlib.  Requires GCC 5.0+ or Clang
 235           5.0+, binutils 2.26+, and zlib.
 236
 237           Users of dpkg-deb via scripts/package/builddeb may find an increase in
 238           size of their debug .deb packages with this config set, due to the
 239           debug info being compressed with zlib, then the object files being
 240           recompressed with a different compression scheme. But this is still
 241           preferable to setting $KDEB_COMPRESS to "none" which would be even
 242           larger.
 243
 244 config DEBUG_INFO_SPLIT
 245         bool "Produce split debuginfo in .dwo files"
 246         depends on DEBUG_INFO
 247         depends on $(cc-option,-gsplit-dwarf)
 248         help
 249           Generate debug info into separate .dwo files. This significantly
 250           reduces the build directory size for builds with DEBUG_INFO,
 251           because it stores the information only once on disk in .dwo
 252           files instead of multiple times in object files and executables.
 253           In addition the debug information is also compressed.
 254
 255           Requires recent gcc (4.7+) and recent gdb/binutils.
 256           Any tool that packages or reads debug information would need
 257           to know about the .dwo files and include them.
 258           Incompatible with older versions of ccache.
 259
 260 config DEBUG_INFO_DWARF4
 261         bool "Generate dwarf4 debuginfo"
 262         depends on DEBUG_INFO
 263         depends on $(cc-option,-gdwarf-4)
 264         help
 265           Generate dwarf4 debug info. This requires recent versions
 266           of gcc and gdb. It makes the debug information larger.
 267           But it significantly improves the success of resolving
 268           variables in gdb on optimized code.
 269
 270 config DEBUG_INFO_BTF
 271         bool "Generate BTF typeinfo"
 272         depends on DEBUG_INFO
 273         depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED
 274         depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST
 275         help
 276           Generate deduplicated BTF type information from DWARF debug info.
 277           Turning this on expects presence of pahole tool, which will convert
 278           DWARF type info into equivalent deduplicated BTF type info.
 279
 280 config GDB_SCRIPTS
 281         bool "Provide GDB scripts for kernel debugging"
 282         depends on DEBUG_INFO
 283         help
 284           This creates the required links to GDB helper scripts in the
 285           build directory. If you load vmlinux into gdb, the helper
 286           scripts will be automatically imported by gdb as well, and
 287           additional functions are available to analyze a Linux kernel
 288           instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
 289           for further details.
 290
 291 config ENABLE_MUST_CHECK
 292         bool "Enable __must_check logic"
 293         default y
 294         help
 295           Enable the __must_check logic in the kernel build.  Disable this to
 296           suppress the "warning: ignoring return value of 'foo', declared with
 297           attribute warn_unused_result" messages.
 298
 299 config FRAME_WARN
 300         int "Warn for stack frames larger than"
 301         range 0 8192
 302         default 2048 if GCC_PLUGIN_LATENT_ENTROPY
 303         default 1280 if (!64BIT && PARISC)
 304         default 1024 if (!64BIT && !PARISC)
 305         default 2048 if 64BIT
 306         help
 307           Tell gcc to warn at build time for stack frames larger than this.
 308           Setting this too low will cause a lot of warnings.
 309           Setting it to 0 disables the warning.
 310
 311 config STRIP_ASM_SYMS
 312         bool "Strip assembler-generated symbols during link"
 313         default n
 314         help
 315           Strip internal assembler-generated symbols during a link (symbols
 316           that look like '.Lxxx') so they don't pollute the output of
 317           get_wchan() and suchlike.
 318
 319 config READABLE_ASM
 320         bool "Generate readable assembler code"
 321         depends on DEBUG_KERNEL
 322         help
 323           Disable some compiler optimizations that tend to generate human unreadable
 324           assembler output. This may make the kernel slightly slower, but it helps
 325           to keep kernel developers who have to stare a lot at assembler listings
 326           sane.
 327
 328 config HEADERS_INSTALL
 329         bool "Install uapi headers to usr/include"
 330         depends on !UML
 331         help
 332           This option will install uapi headers (headers exported to user-space)
 333           into the usr/include directory for use during the kernel build.
 334           This is unneeded for building the kernel itself, but needed for some
 335           user-space program samples. It is also needed by some features such
 336           as uapi header sanity checks.
 337
 338 config DEBUG_SECTION_MISMATCH
 339         bool "Enable full Section mismatch analysis"
 340         help
 341           The section mismatch analysis checks if there are illegal
 342           references from one section to another section.
 343           During linktime or runtime, some sections are dropped;
 344           any use of code/data previously in these sections would
 345           most likely result in an oops.
 346           In the code, functions and variables are annotated with
 347           __init,, etc. (see the full list in include/linux/init.h),
 348           which results in the code/data being placed in specific sections.
 349           The section mismatch analysis is always performed after a full
 350           kernel build, and enabling this option causes the following
 351           additional step to occur:
 352           - Add the option -fno-inline-functions-called-once to gcc commands.
 353             When inlining a function annotated with __init in a non-init
 354             function, we would lose the section information and thus
 355             the analysis would not catch the illegal reference.
 356             This option tells gcc to inline less (but it does result in
 357             a larger kernel).
 358
 359 config SECTION_MISMATCH_WARN_ONLY
 360         bool "Make section mismatch errors non-fatal"
 361         default y
 362         help
 363           If you say N here, the build process will fail if there are any
 364           section mismatch, instead of just throwing warnings.
 365
 366           If unsure, say Y.
 367
 368 #
 369 # Select this config option from the architecture Kconfig, if it
 370 # is preferred to always offer frame pointers as a config
 371 # option on the architecture (regardless of KERNEL_DEBUG):
 372 #
 373 config ARCH_WANT_FRAME_POINTERS
 374         bool
 375
 376 config FRAME_POINTER
 377         bool "Compile the kernel with frame pointers"
 378         depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
 379         default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
 380         help
 381           If you say Y here the resulting kernel image will be slightly
 382           larger and slower, but it gives very useful debugging information
 383           in case of kernel bugs. (precise oopses/stacktraces/warnings)
 384
 385 config STACK_VALIDATION
 386         bool "Compile-time stack metadata validation"
 387         depends on HAVE_STACK_VALIDATION
 388         default n
 389         help
 390           Add compile-time checks to validate stack metadata, including frame
 391           pointers (if CONFIG_FRAME_POINTER is enabled).  This helps ensure
 392           that runtime stack traces are more reliable.
 393
 394           This is also a prerequisite for generation of ORC unwind data, which
 395           is needed for CONFIG_UNWINDER_ORC.
 396
 397           For more information, see
 398           tools/objtool/Documentation/stack-validation.txt.
 399
 400 config VMLINUX_VALIDATION
 401         bool
 402         depends on STACK_VALIDATION && DEBUG_ENTRY && !PARAVIRT
 403         default y
 404
 405 config DEBUG_FORCE_WEAK_PER_CPU
 406         bool "Force weak per-cpu definitions"
 407         depends on DEBUG_KERNEL
 408         help
 409           s390 and alpha require percpu variables in modules to be
 410           defined weak to work around addressing range issue which
 411           puts the following two restrictions on percpu variable
 412           definitions.
 413
 414           1. percpu symbols must be unique whether static or not
 415           2. percpu variables can't be defined inside a function
 416
 417           To ensure that generic code follows the above rules, this
 418           option forces all percpu variables to be defined as weak.
 419
 420 endmenu # "Compiler options"
 421
 422 menu "Generic Kernel Debugging Instruments"
 423
 424 config MAGIC_SYSRQ
 425         bool "Magic SysRq key"
 426         depends on !UML
 427         help
 428           If you say Y here, you will have some control over the system even
 429           if the system crashes for example during kernel debugging (e.g., you
 430           will be able to flush the buffer cache to disk, reboot the system
 431           immediately or dump some status information). This is accomplished
 432           by pressing various keys while holding SysRq (Alt+PrintScreen). It
 433           also works on a serial console (on PC hardware at least), if you
 434           send a BREAK and then within 5 seconds a command keypress. The
 435           keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
 436           Don't say Y unless you really know what this hack does.
 437
 438 config MAGIC_SYSRQ_DEFAULT_ENABLE
 439         hex "Enable magic SysRq key functions by default"
 440         depends on MAGIC_SYSRQ
 441         default 0x1
 442         help
 443           Specifies which SysRq key functions are enabled by default.
 444           This may be set to 1 or 0 to enable or disable them all, or
 445           to a bitmask as described in Documentation/admin-guide/sysrq.rst.
 446
 447 config MAGIC_SYSRQ_SERIAL
 448         bool "Enable magic SysRq key over serial"
 449         depends on MAGIC_SYSRQ
 450         default y
 451         help
 452           Many embedded boards have a disconnected TTL level serial which can
 453           generate some garbage that can lead to spurious false sysrq detects.
 454           This option allows you to decide whether you want to enable the
 455           magic SysRq key.
 456
 457 config MAGIC_SYSRQ_SERIAL_SEQUENCE
 458         string "Char sequence that enables magic SysRq over serial"
 459         depends on MAGIC_SYSRQ_SERIAL
 460         default ""
 461         help
 462           Specifies a sequence of characters that can follow BREAK to enable
 463           SysRq on a serial console.
 464
 465           If unsure, leave an empty string and the option will not be enabled.
 466
 467 config DEBUG_FS
 468         bool "Debug Filesystem"
 469         help
 470           debugfs is a virtual file system that kernel developers use to put
 471           debugging files into.  Enable this option to be able to read and
 472           write to these files.
 473
 474           For detailed documentation on the debugfs API, see
 475           Documentation/filesystems/.
 476
 477           If unsure, say N.
 478
 479 choice
 480         prompt "Debugfs default access"
 481         depends on DEBUG_FS
 482         default DEBUG_FS_ALLOW_ALL
 483         help
 484           This selects the default access restrictions for debugfs.
 485           It can be overridden with kernel command line option
 486           debugfs=[on,no-mount,off]. The restrictions apply for API access
 487           and filesystem registration.
 488
 489 config DEBUG_FS_ALLOW_ALL
 490         bool "Access normal"
 491         help
 492           No restrictions apply. Both API and filesystem registration
 493           is on. This is the normal default operation.
 494
 495 config DEBUG_FS_DISALLOW_MOUNT
 496         bool "Do not register debugfs as filesystem"
 497         help
 498           The API is open but filesystem is not loaded. Clients can still do
 499           their work and read with debug tools that do not need
 500           debugfs filesystem.
 501
 502 config DEBUG_FS_ALLOW_NONE
 503         bool "No access"
 504         help
 505           Access is off. Clients get -PERM when trying to create nodes in
 506           debugfs tree and debugfs is not registered as a filesystem.
 507           Client can then back-off or continue without debugfs access.
 508
 509 endchoice
 510
 511 source "lib/Kconfig.kgdb"
 512
 513 source "lib/Kconfig.ubsan"
 514
 515 endmenu
 516
 517 config DEBUG_KERNEL
 518         bool "Kernel debugging"
 519         help
 520           Say Y here if you are developing drivers or trying to debug and
 521           identify kernel problems.
 522
 523 config DEBUG_MISC
 524         bool "Miscellaneous debug code"
 525         default DEBUG_KERNEL
 526         depends on DEBUG_KERNEL
 527         help
 528           Say Y here if you need to enable miscellaneous debug code that should
 529           be under a more specific debug option but isn't.
 530
 531
 532 menu "Memory Debugging"
 533
 534 source "mm/Kconfig.debug"
 535
 536 config DEBUG_OBJECTS
 537         bool "Debug object operations"
 538         depends on DEBUG_KERNEL
 539         help
 540           If you say Y here, additional code will be inserted into the
 541           kernel to track the life time of various objects and validate
 542           the operations on those objects.
 543
 544 config DEBUG_OBJECTS_SELFTEST
 545         bool "Debug objects selftest"
 546         depends on DEBUG_OBJECTS
 547         help
 548           This enables the selftest of the object debug code.
 549
 550 config DEBUG_OBJECTS_FREE
 551         bool "Debug objects in freed memory"
 552         depends on DEBUG_OBJECTS
 553         help
 554           This enables checks whether a k/v free operation frees an area
 555           which contains an object which has not been deactivated
 556           properly. This can make kmalloc/kfree-intensive workloads
 557           much slower.
 558
 559 config DEBUG_OBJECTS_TIMERS
 560         bool "Debug timer objects"
 561         depends on DEBUG_OBJECTS
 562         help
 563           If you say Y here, additional code will be inserted into the
 564           timer routines to track the life time of timer objects and
 565           validate the timer operations.
 566
 567 config DEBUG_OBJECTS_WORK
 568         bool "Debug work objects"
 569         depends on DEBUG_OBJECTS
 570         help
 571           If you say Y here, additional code will be inserted into the
 572           work queue routines to track the life time of work objects and
 573           validate the work operations.
 574
 575 config DEBUG_OBJECTS_RCU_HEAD
 576         bool "Debug RCU callbacks objects"
 577         depends on DEBUG_OBJECTS
 578         help
 579           Enable this to turn on debugging of RCU list heads (call_rcu() usage).
 580
 581 config DEBUG_OBJECTS_PERCPU_COUNTER
 582         bool "Debug percpu counter objects"
 583         depends on DEBUG_OBJECTS
 584         help
 585           If you say Y here, additional code will be inserted into the
 586           percpu counter routines to track the life time of percpu counter
 587           objects and validate the percpu counter operations.
 588
 589 config DEBUG_OBJECTS_ENABLE_DEFAULT
 590         int "debug_objects bootup default value (0-1)"
 591         range 0 1
 592         default "1"
 593         depends on DEBUG_OBJECTS
 594         help
 595           Debug objects boot parameter default value
 596
 597 config DEBUG_SLAB
 598         bool "Debug slab memory allocations"
 599         depends on DEBUG_KERNEL && SLAB
 600         help
 601           Say Y here to have the kernel do limited verification on memory
 602           allocation as well as poisoning memory on free to catch use of freed
 603           memory. This can make kmalloc/kfree-intensive workloads much slower.
 604
 605 config SLUB_DEBUG_ON
 606         bool "SLUB debugging on by default"
 607         depends on SLUB && SLUB_DEBUG
 608         default n
 609         help
 610           Boot with debugging on by default. SLUB boots by default with
 611           the runtime debug capabilities switched off. Enabling this is
 612           equivalent to specifying the "slub_debug" parameter on boot.
 613           There is no support for more fine grained debug control like
 614           possible with slub_debug=xxx. SLUB debugging may be switched
 615           off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
 616           "slub_debug=-".
 617
 618 config SLUB_STATS
 619         default n
 620         bool "Enable SLUB performance statistics"
 621         depends on SLUB && SYSFS
 622         help
 623           SLUB statistics are useful to debug SLUBs allocation behavior in
 624           order find ways to optimize the allocator. This should never be
 625           enabled for production use since keeping statistics slows down
 626           the allocator by a few percentage points. The slabinfo command
 627           supports the determination of the most active slabs to figure
 628           out which slabs are relevant to a particular load.
 629           Try running: slabinfo -DA
 630
 631 config HAVE_DEBUG_KMEMLEAK
 632         bool
 633
 634 config DEBUG_KMEMLEAK
 635         bool "Kernel memory leak detector"
 636         depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
 637         select DEBUG_FS
 638         select STACKTRACE if STACKTRACE_SUPPORT
 639         select KALLSYMS
 640         select CRC32
 641         help
 642           Say Y here if you want to enable the memory leak
 643           detector. The memory allocation/freeing is traced in a way
 644           similar to the Boehm's conservative garbage collector, the
 645           difference being that the orphan objects are not freed but
 646           only shown in /sys/kernel/debug/kmemleak. Enabling this
 647           feature will introduce an overhead to memory
 648           allocations. See Documentation/dev-tools/kmemleak.rst for more
 649           details.
 650
 651           Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
 652           of finding leaks due to the slab objects poisoning.
 653
 654           In order to access the kmemleak file, debugfs needs to be
 655           mounted (usually at /sys/kernel/debug).
 656
 657 config DEBUG_KMEMLEAK_MEM_POOL_SIZE
 658         int "Kmemleak memory pool size"
 659         depends on DEBUG_KMEMLEAK
 660         range 200 1000000
 661         default 16000
 662         help
 663           Kmemleak must track all the memory allocations to avoid
 664           reporting false positives. Since memory may be allocated or
 665           freed before kmemleak is fully initialised, use a static pool
 666           of metadata objects to track such callbacks. After kmemleak is
 667           fully initialised, this memory pool acts as an emergency one
 668           if slab allocations fail.
 669
 670 config DEBUG_KMEMLEAK_TEST
 671         tristate "Simple test for the kernel memory leak detector"
 672         depends on DEBUG_KMEMLEAK && m
 673         help
 674           This option enables a module that explicitly leaks memory.
 675
 676           If unsure, say N.
 677
 678 config DEBUG_KMEMLEAK_DEFAULT_OFF
 679         bool "Default kmemleak to off"
 680         depends on DEBUG_KMEMLEAK
 681         help
 682           Say Y here to disable kmemleak by default. It can then be enabled
 683           on the command line via kmemleak=on.
 684
 685 config DEBUG_KMEMLEAK_AUTO_SCAN
 686         bool "Enable kmemleak auto scan thread on boot up"
 687         default y
 688         depends on DEBUG_KMEMLEAK
 689         help
 690           Depending on the cpu, kmemleak scan may be cpu intensive and can
 691           stall user tasks at times. This option enables/disables automatic
 692           kmemleak scan at boot up.
 693
 694           Say N here to disable kmemleak auto scan thread to stop automatic
 695           scanning. Disabling this option disables automatic reporting of
 696           memory leaks.
 697
 698           If unsure, say Y.
 699
 700 config DEBUG_STACK_USAGE
 701         bool "Stack utilization instrumentation"
 702         depends on DEBUG_KERNEL && !IA64
 703         help
 704           Enables the display of the minimum amount of free stack which each
 705           task has ever had available in the sysrq-T and sysrq-P debug output.
 706
 707           This option will slow down process creation somewhat.
 708
 709 config SCHED_STACK_END_CHECK
 710         bool "Detect stack corruption on calls to schedule()"
 711         depends on DEBUG_KERNEL
 712         default n
 713         help
 714           This option checks for a stack overrun on calls to schedule().
 715           If the stack end location is found to be over written always panic as
 716           the content of the corrupted region can no longer be trusted.
 717           This is to ensure no erroneous behaviour occurs which could result in
 718           data corruption or a sporadic crash at a later stage once the region
 719           is examined. The runtime overhead introduced is minimal.
 720
 721 config ARCH_HAS_DEBUG_VM_PGTABLE
 722         bool
 723         help
 724           An architecture should select this when it can successfully
 725           build and run DEBUG_VM_PGTABLE.
 726
 727 config DEBUG_VM
 728         bool "Debug VM"
 729         depends on DEBUG_KERNEL
 730         help
 731           Enable this to turn on extended checks in the virtual-memory system
 732           that may impact performance.
 733
 734           If unsure, say N.
 735
 736 config DEBUG_VM_VMACACHE
 737         bool "Debug VMA caching"
 738         depends on DEBUG_VM
 739         help
 740           Enable this to turn on VMA caching debug information. Doing so
 741           can cause significant overhead, so only enable it in non-production
 742           environments.
 743
 744           If unsure, say N.
 745
 746 config DEBUG_VM_RB
 747         bool "Debug VM red-black trees"
 748         depends on DEBUG_VM
 749         help
 750           Enable VM red-black tree debugging information and extra validations.
 751
 752           If unsure, say N.
 753
 754 config DEBUG_VM_PGFLAGS
 755         bool "Debug page-flags operations"
 756         depends on DEBUG_VM
 757         help
 758           Enables extra validation on page flags operations.
 759
 760           If unsure, say N.
 761
 762 config DEBUG_VM_PGTABLE
 763         bool "Debug arch page table for semantics compliance"
 764         depends on MMU
 765         depends on ARCH_HAS_DEBUG_VM_PGTABLE
 766         default y if DEBUG_VM
 767         help
 768           This option provides a debug method which can be used to test
 769           architecture page table helper functions on various platforms in
 770           verifying if they comply with expected generic MM semantics. This
 771           will help architecture code in making sure that any changes or
 772           new additions of these helpers still conform to expected
 773           semantics of the generic MM. Platforms will have to opt in for
 774           this through ARCH_HAS_DEBUG_VM_PGTABLE.
 775
 776           If unsure, say N.
 777
 778 config ARCH_HAS_DEBUG_VIRTUAL
 779         bool
 780
 781 config DEBUG_VIRTUAL
 782         bool "Debug VM translations"
 783         depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
 784         help
 785           Enable some costly sanity checks in virtual to page code. This can
 786           catch mistakes with virt_to_page() and friends.
 787
 788           If unsure, say N.
 789
 790 config DEBUG_NOMMU_REGIONS
 791         bool "Debug the global anon/private NOMMU mapping region tree"
 792         depends on DEBUG_KERNEL && !MMU
 793         help
 794           This option causes the global tree of anonymous and private mapping
 795           regions to be regularly checked for invalid topology.
 796
 797 config DEBUG_MEMORY_INIT
 798         bool "Debug memory initialisation" if EXPERT
 799         default !EXPERT
 800         help
 801           Enable this for additional checks during memory initialisation.
 802           The sanity checks verify aspects of the VM such as the memory model
 803           and other information provided by the architecture. Verbose
 804           information will be printed at KERN_DEBUG loglevel depending
 805           on the mminit_loglevel= command-line option.
 806
 807           If unsure, say Y
 808
 809 config MEMORY_NOTIFIER_ERROR_INJECT
 810         tristate "Memory hotplug notifier error injection module"
 811         depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
 812         help
 813           This option provides the ability to inject artificial errors to
 814           memory hotplug notifier chain callbacks.  It is controlled through
 815           debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
 816
 817           If the notifier call chain should be failed with some events
 818           notified, write the error code to "actions/<notifier event>/error".
 819
 820           Example: Inject memory hotplug offline error (-12 == -ENOMEM)
 821
 822           # cd /sys/kernel/debug/notifier-error-inject/memory
 823           # echo -12 > actions/MEM_GOING_OFFLINE/error
 824           # echo offline > /sys/devices/system/memory/memoryXXX/state
 825           bash: echo: write error: Cannot allocate memory
 826
 827           To compile this code as a module, choose M here: the module will
 828           be called memory-notifier-error-inject.
 829
 830           If unsure, say N.
 831
 832 config DEBUG_PER_CPU_MAPS
 833         bool "Debug access to per_cpu maps"
 834         depends on DEBUG_KERNEL
 835         depends on SMP
 836         help
 837           Say Y to verify that the per_cpu map being accessed has
 838           been set up. This adds a fair amount of code to kernel memory
 839           and decreases performance.
 840
 841           Say N if unsure.
 842
 843 config DEBUG_HIGHMEM
 844         bool "Highmem debugging"
 845         depends on DEBUG_KERNEL && HIGHMEM
 846         help
 847           This option enables additional error checking for high memory
 848           systems.  Disable for production systems.
 849
 850 config HAVE_DEBUG_STACKOVERFLOW
 851         bool
 852
 853 config DEBUG_STACKOVERFLOW
 854         bool "Check for stack overflows"
 855         depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
 856         help
 857           Say Y here if you want to check for overflows of kernel, IRQ
 858           and exception stacks (if your architecture uses them). This
 859           option will show detailed messages if free stack space drops
 860           below a certain limit.
 861
 862           These kinds of bugs usually occur when call-chains in the
 863           kernel get too deep, especially when interrupts are
 864           involved.
 865
 866           Use this in cases where you see apparently random memory
 867           corruption, especially if it appears in 'struct thread_info'
 868
 869           If in doubt, say "N".
 870
 871 source "lib/Kconfig.kasan"
 872
 873 endmenu # "Memory Debugging"
 874
 875 config DEBUG_SHIRQ
 876         bool "Debug shared IRQ handlers"
 877         depends on DEBUG_KERNEL
 878         help
 879           Enable this to generate a spurious interrupt just before a shared
 880           interrupt handler is deregistered (generating one when registering
 881           is currently disabled). Drivers need to handle this correctly. Some
 882           don't and need to be caught.
 883
 884 menu "Debug Oops, Lockups and Hangs"
 885
 886 config PANIC_ON_OOPS
 887         bool "Panic on Oops"
 888         help
 889           Say Y here to enable the kernel to panic when it oopses. This
 890           has the same effect as setting oops=panic on the kernel command
 891           line.
 892
 893           This feature is useful to ensure that the kernel does not do
 894           anything erroneous after an oops which could result in data
 895           corruption or other issues.
 896
 897           Say N if unsure.
 898
 899 config PANIC_ON_OOPS_VALUE
 900         int
 901         range 0 1
 902         default 0 if !PANIC_ON_OOPS
 903         default 1 if PANIC_ON_OOPS
 904
 905 config PANIC_TIMEOUT
 906         int "panic timeout"
 907         default 0
 908         help
 909           Set the timeout value (in seconds) until a reboot occurs when the
 910           the kernel panics. If n = 0, then we wait forever. A timeout
 911           value n > 0 will wait n seconds before rebooting, while a timeout
 912           value n < 0 will reboot immediately.
 913
 914 config LOCKUP_DETECTOR
 915         bool
 916
 917 config SOFTLOCKUP_DETECTOR
 918         bool "Detect Soft Lockups"
 919         depends on DEBUG_KERNEL && !S390
 920         select LOCKUP_DETECTOR
 921         help
 922           Say Y here to enable the kernel to act as a watchdog to detect
 923           soft lockups.
 924
 925           Softlockups are bugs that cause the kernel to loop in kernel
 926           mode for more than 20 seconds, without giving other tasks a
 927           chance to run.  The current stack trace is displayed upon
 928           detection and the system will stay locked up.
 929
 930 config BOOTPARAM_SOFTLOCKUP_PANIC
 931         bool "Panic (Reboot) On Soft Lockups"
 932         depends on SOFTLOCKUP_DETECTOR
 933         help
 934           Say Y here to enable the kernel to panic on "soft lockups",
 935           which are bugs that cause the kernel to loop in kernel
 936           mode for more than 20 seconds (configurable using the watchdog_thresh
 937           sysctl), without giving other tasks a chance to run.
 938
 939           The panic can be used in combination with panic_timeout,
 940           to cause the system to reboot automatically after a
 941           lockup has been detected. This feature is useful for
 942           high-availability systems that have uptime guarantees and
 943           where a lockup must be resolved ASAP.
 944
 945           Say N if unsure.
 946
 947 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
 948         int
 949         depends on SOFTLOCKUP_DETECTOR
 950         range 0 1
 951         default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
 952         default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
 953
 954 config HARDLOCKUP_DETECTOR_PERF
 955         bool
 956         select SOFTLOCKUP_DETECTOR
 957
 958 #
 959 # Enables a timestamp based low pass filter to compensate for perf based
 960 # hard lockup detection which runs too fast due to turbo modes.
 961 #
 962 config HARDLOCKUP_CHECK_TIMESTAMP
 963         bool
 964
 965 #
 966 # arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard
 967 # lockup detector rather than the perf based detector.
 968 #
 969 config HARDLOCKUP_DETECTOR
 970         bool "Detect Hard Lockups"
 971         depends on DEBUG_KERNEL && !S390
 972         depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH
 973         select LOCKUP_DETECTOR
 974         select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF
 975         select HARDLOCKUP_DETECTOR_ARCH if HAVE_HARDLOCKUP_DETECTOR_ARCH
 976         help
 977           Say Y here to enable the kernel to act as a watchdog to detect
 978           hard lockups.
 979
 980           Hardlockups are bugs that cause the CPU to loop in kernel mode
 981           for more than 10 seconds, without letting other interrupts have a
 982           chance to run.  The current stack trace is displayed upon detection
 983           and the system will stay locked up.
 984
 985 config BOOTPARAM_HARDLOCKUP_PANIC
 986         bool "Panic (Reboot) On Hard Lockups"
 987         depends on HARDLOCKUP_DETECTOR
 988         help
 989           Say Y here to enable the kernel to panic on "hard lockups",
 990           which are bugs that cause the kernel to loop in kernel
 991           mode with interrupts disabled for more than 10 seconds (configurable
 992           using the watchdog_thresh sysctl).
 993
 994           Say N if unsure.
 995
 996 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
 997         int
 998         depends on HARDLOCKUP_DETECTOR
 999         range 0 1
1000         default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
1001         default 1 if BOOTPARAM_HARDLOCKUP_PANIC
1002
1003 config DETECT_HUNG_TASK
1004         bool "Detect Hung Tasks"
1005         depends on DEBUG_KERNEL
1006         default SOFTLOCKUP_DETECTOR
1007         help
1008           Say Y here to enable the kernel to detect "hung tasks",
1009           which are bugs that cause the task to be stuck in
1010           uninterruptible "D" state indefinitely.
1011
1012           When a hung task is detected, the kernel will print the
1013           current stack trace (which you should report), but the
1014           task will stay in uninterruptible state. If lockdep is
1015           enabled then all held locks will also be reported. This
1016           feature has negligible overhead.
1017
1018 config DEFAULT_HUNG_TASK_TIMEOUT
1019         int "Default timeout for hung task detection (in seconds)"
1020         depends on DETECT_HUNG_TASK
1021         default 120
1022         help
1023           This option controls the default timeout (in seconds) used
1024           to determine when a task has become non-responsive and should
1025           be considered hung.
1026
1027           It can be adjusted at runtime via the kernel.hung_task_timeout_secs
1028           sysctl or by writing a value to
1029           /proc/sys/kernel/hung_task_timeout_secs.
1030
1031           A timeout of 0 disables the check.  The default is two minutes.
1032           Keeping the default should be fine in most cases.
1033
1034 config BOOTPARAM_HUNG_TASK_PANIC
1035         bool "Panic (Reboot) On Hung Tasks"
1036         depends on DETECT_HUNG_TASK
1037         help
1038           Say Y here to enable the kernel to panic on "hung tasks",
1039           which are bugs that cause the kernel to leave a task stuck
1040           in uninterruptible "D" state.
1041
1042           The panic can be used in combination with panic_timeout,
1043           to cause the system to reboot automatically after a
1044           hung task has been detected. This feature is useful for
1045           high-availability systems that have uptime guarantees and
1046           where a hung tasks must be resolved ASAP.
1047
1048           Say N if unsure.
1049
1050 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
1051         int
1052         depends on DETECT_HUNG_TASK
1053         range 0 1
1054         default 0 if !BOOTPARAM_HUNG_TASK_PANIC
1055         default 1 if BOOTPARAM_HUNG_TASK_PANIC
1056
1057 config WQ_WATCHDOG
1058         bool "Detect Workqueue Stalls"
1059         depends on DEBUG_KERNEL
1060         help
1061           Say Y here to enable stall detection on workqueues.  If a
1062           worker pool doesn't make forward progress on a pending work
1063           item for over a given amount of time, 30s by default, a
1064           warning message is printed along with dump of workqueue
1065           state.  This can be configured through kernel parameter
1066           "workqueue.watchdog_thresh" and its sysfs counterpart.
1067
1068 config TEST_LOCKUP
1069         tristate "Test module to generate lockups"
1070         help
1071           This builds the "test_lockup" module that helps to make sure
1072           that watchdogs and lockup detectors are working properly.
1073
1074           Depending on module parameters it could emulate soft or hard
1075           lockup, "hung task", or locking arbitrary lock for a long time.
1076           Also it could generate series of lockups with cooling-down periods.
1077
1078           If unsure, say N.
1079
1080 endmenu # "Debug lockups and hangs"
1081
1082 menu "Scheduler Debugging"
1083
1084 config SCHED_DEBUG
1085         bool "Collect scheduler debugging info"
1086         depends on DEBUG_KERNEL && PROC_FS
1087         default y
1088         help
1089           If you say Y here, the /proc/sched_debug file will be provided
1090           that can help debug the scheduler. The runtime overhead of this
1091           option is minimal.
1092
1093 config SCHED_INFO
1094         bool
1095         default n
1096
1097 config SCHEDSTATS
1098         bool "Collect scheduler statistics"
1099         depends on DEBUG_KERNEL && PROC_FS
1100         select SCHED_INFO
1101         help
1102           If you say Y here, additional code will be inserted into the
1103           scheduler and related routines to collect statistics about
1104           scheduler behavior and provide them in /proc/schedstat.  These
1105           stats may be useful for both tuning and debugging the scheduler
1106           If you aren't debugging the scheduler or trying to tune a specific
1107           application, you can say N to avoid the very slight overhead
1108           this adds.
1109
1110 endmenu
1111
1112 config DEBUG_TIMEKEEPING
1113         bool "Enable extra timekeeping sanity checking"
1114         help
1115           This option will enable additional timekeeping sanity checks
1116           which may be helpful when diagnosing issues where timekeeping
1117           problems are suspected.
1118
1119           This may include checks in the timekeeping hotpaths, so this
1120           option may have a (very small) performance impact to some
1121           workloads.
1122
1123           If unsure, say N.
1124
1125 config DEBUG_PREEMPT
1126         bool "Debug preemptible kernel"
1127         depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT
1128         default y
1129         help
1130           If you say Y here then the kernel will use a debug variant of the
1131           commonly used smp_processor_id() function and will print warnings
1132           if kernel code uses it in a preemption-unsafe way. Also, the kernel
1133           will detect preemption count underflows.
1134
1135 menu "Lock Debugging (spinlocks, mutexes, etc...)"
1136
1137 config LOCK_DEBUGGING_SUPPORT
1138         bool
1139         depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1140         default y
1141
1142 config PROVE_LOCKING
1143         bool "Lock debugging: prove locking correctness"
1144         depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1145         select LOCKDEP
1146         select DEBUG_SPINLOCK
1147         select DEBUG_MUTEXES
1148         select DEBUG_RT_MUTEXES if RT_MUTEXES
1149         select DEBUG_RWSEMS
1150         select DEBUG_WW_MUTEX_SLOWPATH
1151         select DEBUG_LOCK_ALLOC
1152         select PREEMPT_COUNT if !ARCH_NO_PREEMPT
1153         select TRACE_IRQFLAGS
1154         default n
1155         help
1156          This feature enables the kernel to prove that all locking
1157          that occurs in the kernel runtime is mathematically
1158          correct: that under no circumstance could an arbitrary (and
1159          not yet triggered) combination of observed locking
1160          sequences (on an arbitrary number of CPUs, running an
1161          arbitrary number of tasks and interrupt contexts) cause a
1162          deadlock.
1163
1164          In short, this feature enables the kernel to report locking
1165          related deadlocks before they actually occur.
1166
1167          The proof does not depend on how hard and complex a
1168          deadlock scenario would be to trigger: how many
1169          participant CPUs, tasks and irq-contexts would be needed
1170          for it to trigger. The proof also does not depend on
1171          timing: if a race and a resulting deadlock is possible
1172          theoretically (no matter how unlikely the race scenario
1173          is), it will be proven so and will immediately be
1174          reported by the kernel (once the event is observed that
1175          makes the deadlock theoretically possible).
1176
1177          If a deadlock is impossible (i.e. the locking rules, as
1178          observed by the kernel, are mathematically correct), the
1179          kernel reports nothing.
1180
1181          NOTE: this feature can also be enabled for rwlocks, mutexes
1182          and rwsems - in which case all dependencies between these
1183          different locking variants are observed and mapped too, and
1184          the proof of observed correctness is also maintained for an
1185          arbitrary combination of these separate locking variants.
1186
1187          For more details, see Documentation/locking/lockdep-design.rst.
1188
1189 config PROVE_RAW_LOCK_NESTING
1190         bool "Enable raw_spinlock - spinlock nesting checks"
1191         depends on PROVE_LOCKING
1192         default n
1193         help
1194          Enable the raw_spinlock vs. spinlock nesting checks which ensure
1195          that the lock nesting rules for PREEMPT_RT enabled kernels are
1196          not violated.
1197
1198          NOTE: There are known nesting problems. So if you enable this
1199          option expect lockdep splats until these problems have been fully
1200          addressed which is work in progress. This config switch allows to
1201          identify and analyze these problems. It will be removed and the
1202          check permanentely enabled once the main issues have been fixed.
1203
1204          If unsure, select N.
1205
1206 config LOCK_STAT
1207         bool "Lock usage statistics"
1208         depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1209         select LOCKDEP
1210         select DEBUG_SPINLOCK
1211         select DEBUG_MUTEXES
1212         select DEBUG_RT_MUTEXES if RT_MUTEXES
1213         select DEBUG_LOCK_ALLOC
1214         default n
1215         help
1216          This feature enables tracking lock contention points
1217
1218          For more details, see Documentation/locking/lockstat.rst
1219
1220          This also enables lock events required by "perf lock",
1221          subcommand of perf.
1222          If you want to use "perf lock", you also need to turn on
1223          CONFIG_EVENT_TRACING.
1224
1225          CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1226          (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1227
1228 config DEBUG_RT_MUTEXES
1229         bool "RT Mutex debugging, deadlock detection"
1230         depends on DEBUG_KERNEL && RT_MUTEXES
1231         help
1232          This allows rt mutex semantics violations and rt mutex related
1233          deadlocks (lockups) to be detected and reported automatically.
1234
1235 config DEBUG_SPINLOCK
1236         bool "Spinlock and rw-lock debugging: basic checks"
1237         depends on DEBUG_KERNEL
1238         select UNINLINE_SPIN_UNLOCK
1239         help
1240           Say Y here and build SMP to catch missing spinlock initialization
1241           and certain other kinds of spinlock errors commonly made.  This is
1242           best used in conjunction with the NMI watchdog so that spinlock
1243           deadlocks are also debuggable.
1244
1245 config DEBUG_MUTEXES
1246         bool "Mutex debugging: basic checks"
1247         depends on DEBUG_KERNEL
1248         help
1249          This feature allows mutex semantics violations to be detected and
1250          reported.
1251
1252 config DEBUG_WW_MUTEX_SLOWPATH
1253         bool "Wait/wound mutex debugging: Slowpath testing"
1254         depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1255         select DEBUG_LOCK_ALLOC
1256         select DEBUG_SPINLOCK
1257         select DEBUG_MUTEXES
1258         help
1259          This feature enables slowpath testing for w/w mutex users by
1260          injecting additional -EDEADLK wound/backoff cases. Together with
1261          the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1262          will test all possible w/w mutex interface abuse with the
1263          exception of simply not acquiring all the required locks.
1264          Note that this feature can introduce significant overhead, so
1265          it really should not be enabled in a production or distro kernel,
1266          even a debug kernel.  If you are a driver writer, enable it.  If
1267          you are a distro, do not.
1268
1269 config DEBUG_RWSEMS
1270         bool "RW Semaphore debugging: basic checks"
1271         depends on DEBUG_KERNEL
1272         help
1273           This debugging feature allows mismatched rw semaphore locks
1274           and unlocks to be detected and reported.
1275
1276 config DEBUG_LOCK_ALLOC
1277         bool "Lock debugging: detect incorrect freeing of live locks"
1278         depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1279         select DEBUG_SPINLOCK
1280         select DEBUG_MUTEXES
1281         select DEBUG_RT_MUTEXES if RT_MUTEXES
1282         select LOCKDEP
1283         help
1284          This feature will check whether any held lock (spinlock, rwlock,
1285          mutex or rwsem) is incorrectly freed by the kernel, via any of the
1286          memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1287          vfree(), etc.), whether a live lock is incorrectly reinitialized via
1288          spin_lock_init()/mutex_init()/etc., or whether there is any lock
1289          held during task exit.
1290
1291 config LOCKDEP
1292         bool
1293         depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1294         select STACKTRACE
1295         select FRAME_POINTER if !MIPS && !PPC && !ARM && !S390 && !MICROBLAZE && !ARC && !X86
1296         select KALLSYMS
1297         select KALLSYMS_ALL
1298
1299 config LOCKDEP_SMALL
1300         bool
1301
1302 config DEBUG_LOCKDEP
1303         bool "Lock dependency engine debugging"
1304         depends on DEBUG_KERNEL && LOCKDEP
1305         help
1306           If you say Y here, the lock dependency engine will do
1307           additional runtime checks to debug itself, at the price
1308           of more runtime overhead.
1309
1310 config DEBUG_ATOMIC_SLEEP
1311         bool "Sleep inside atomic section checking"
1312         select PREEMPT_COUNT
1313         depends on DEBUG_KERNEL
1314         depends on !ARCH_NO_PREEMPT
1315         help
1316           If you say Y here, various routines which may sleep will become very
1317           noisy if they are called inside atomic sections: when a spinlock is
1318           held, inside an rcu read side critical section, inside preempt disabled
1319           sections, inside an interrupt, etc...
1320
1321 config DEBUG_LOCKING_API_SELFTESTS
1322         bool "Locking API boot-time self-tests"
1323         depends on DEBUG_KERNEL
1324         help
1325           Say Y here if you want the kernel to run a short self-test during
1326           bootup. The self-test checks whether common types of locking bugs
1327           are detected by debugging mechanisms or not. (if you disable
1328           lock debugging then those bugs wont be detected of course.)
1329           The following locking APIs are covered: spinlocks, rwlocks,
1330           mutexes and rwsems.
1331
1332 config LOCK_TORTURE_TEST
1333         tristate "torture tests for locking"
1334         depends on DEBUG_KERNEL
1335         select TORTURE_TEST
1336         help
1337           This option provides a kernel module that runs torture tests
1338           on kernel locking primitives.  The kernel module may be built
1339           after the fact on the running kernel to be tested, if desired.
1340
1341           Say Y here if you want kernel locking-primitive torture tests
1342           to be built into the kernel.
1343           Say M if you want these torture tests to build as a module.
1344           Say N if you are unsure.
1345
1346 config WW_MUTEX_SELFTEST
1347         tristate "Wait/wound mutex selftests"
1348         help
1349           This option provides a kernel module that runs tests on the
1350           on the struct ww_mutex locking API.
1351
1352           It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1353           with this test harness.
1354
1355           Say M if you want these self tests to build as a module.
1356           Say N if you are unsure.
1357
1358 endmenu # lock debugging
1359
1360 config TRACE_IRQFLAGS
1361         depends on TRACE_IRQFLAGS_SUPPORT
1362         bool
1363         help
1364           Enables hooks to interrupt enabling and disabling for
1365           either tracing or lock debugging.
1366
1367 config TRACE_IRQFLAGS_NMI
1368         def_bool y
1369         depends on TRACE_IRQFLAGS
1370         depends on TRACE_IRQFLAGS_NMI_SUPPORT
1371
1372 config STACKTRACE
1373         bool "Stack backtrace support"
1374         depends on STACKTRACE_SUPPORT
1375         help
1376           This option causes the kernel to create a /proc/pid/stack for
1377           every process, showing its current stack trace.
1378           It is also used by various kernel debugging features that require
1379           stack trace generation.
1380
1381 config WARN_ALL_UNSEEDED_RANDOM
1382         bool "Warn for all uses of unseeded randomness"
1383         default n
1384         help
1385           Some parts of the kernel contain bugs relating to their use of
1386           cryptographically secure random numbers before it's actually possible
1387           to generate those numbers securely. This setting ensures that these
1388           flaws don't go unnoticed, by enabling a message, should this ever
1389           occur. This will allow people with obscure setups to know when things
1390           are going wrong, so that they might contact developers about fixing
1391           it.
1392
1393           Unfortunately, on some models of some architectures getting
1394           a fully seeded CRNG is extremely difficult, and so this can
1395           result in dmesg getting spammed for a surprisingly long
1396           time.  This is really bad from a security perspective, and
1397           so architecture maintainers really need to do what they can
1398           to get the CRNG seeded sooner after the system is booted.
1399           However, since users cannot do anything actionable to
1400           address this, by default the kernel will issue only a single
1401           warning for the first use of unseeded randomness.
1402
1403           Say Y here if you want to receive warnings for all uses of
1404           unseeded randomness.  This will be of use primarily for
1405           those developers interested in improving the security of
1406           Linux kernels running on their architecture (or
1407           subarchitecture).
1408
1409 config DEBUG_KOBJECT
1410         bool "kobject debugging"
1411         depends on DEBUG_KERNEL
1412         help
1413           If you say Y here, some extra kobject debugging messages will be sent
1414           to the syslog.
1415
1416 config DEBUG_KOBJECT_RELEASE
1417         bool "kobject release debugging"
1418         depends on DEBUG_OBJECTS_TIMERS
1419         help
1420           kobjects are reference counted objects.  This means that their
1421           last reference count put is not predictable, and the kobject can
1422           live on past the point at which a driver decides to drop it's
1423           initial reference to the kobject gained on allocation.  An
1424           example of this would be a struct device which has just been
1425           unregistered.
1426
1427           However, some buggy drivers assume that after such an operation,
1428           the memory backing the kobject can be immediately freed.  This
1429           goes completely against the principles of a refcounted object.
1430
1431           If you say Y here, the kernel will delay the release of kobjects
1432           on the last reference count to improve the visibility of this
1433           kind of kobject release bug.
1434
1435 config HAVE_DEBUG_BUGVERBOSE
1436         bool
1437
1438 menu "Debug kernel data structures"
1439
1440 config DEBUG_LIST
1441         bool "Debug linked list manipulation"
1442         depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION
1443         help
1444           Enable this to turn on extended checks in the linked-list
1445           walking routines.
1446
1447           If unsure, say N.
1448
1449 config DEBUG_PLIST
1450         bool "Debug priority linked list manipulation"
1451         depends on DEBUG_KERNEL
1452         help
1453           Enable this to turn on extended checks in the priority-ordered
1454           linked-list (plist) walking routines.  This checks the entire
1455           list multiple times during each manipulation.
1456
1457           If unsure, say N.
1458
1459 config DEBUG_SG
1460         bool "Debug SG table operations"
1461         depends on DEBUG_KERNEL
1462         help
1463           Enable this to turn on checks on scatter-gather tables. This can
1464           help find problems with drivers that do not properly initialize
1465           their sg tables.
1466
1467           If unsure, say N.
1468
1469 config DEBUG_NOTIFIERS
1470         bool "Debug notifier call chains"
1471         depends on DEBUG_KERNEL
1472         help
1473           Enable this to turn on sanity checking for notifier call chains.
1474           This is most useful for kernel developers to make sure that
1475           modules properly unregister themselves from notifier chains.
1476           This is a relatively cheap check but if you care about maximum
1477           performance, say N.
1478
1479 config BUG_ON_DATA_CORRUPTION
1480         bool "Trigger a BUG when data corruption is detected"
1481         select DEBUG_LIST
1482         help
1483           Select this option if the kernel should BUG when it encounters
1484           data corruption in kernel memory structures when they get checked
1485           for validity.
1486
1487           If unsure, say N.
1488
1489 endmenu
1490
1491 config DEBUG_CREDENTIALS
1492         bool "Debug credential management"
1493         depends on DEBUG_KERNEL
1494         help
1495           Enable this to turn on some debug checking for credential
1496           management.  The additional code keeps track of the number of
1497           pointers from task_structs to any given cred struct, and checks to
1498           see that this number never exceeds the usage count of the cred
1499           struct.
1500
1501           Furthermore, if SELinux is enabled, this also checks that the
1502           security pointer in the cred struct is never seen to be invalid.
1503
1504           If unsure, say N.
1505
1506 source "kernel/rcu/Kconfig.debug"
1507
1508 config DEBUG_WQ_FORCE_RR_CPU
1509         bool "Force round-robin CPU selection for unbound work items"
1510         depends on DEBUG_KERNEL
1511         default n
1512         help
1513           Workqueue used to implicitly guarantee that work items queued
1514           without explicit CPU specified are put on the local CPU.  This
1515           guarantee is no longer true and while local CPU is still
1516           preferred work items may be put on foreign CPUs.  Kernel
1517           parameter "workqueue.debug_force_rr_cpu" is added to force
1518           round-robin CPU selection to flush out usages which depend on the
1519           now broken guarantee.  This config option enables the debug
1520           feature by default.  When enabled, memory and cache locality will
1521           be impacted.
1522
1523 config DEBUG_BLOCK_EXT_DEVT
1524         bool "Force extended block device numbers and spread them"
1525         depends on DEBUG_KERNEL
1526         depends on BLOCK
1527         default n
1528         help
1529           BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1530           SOME DISTRIBUTIONS.  DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1531           YOU ARE DOING.  Distros, please enable this and fix whatever
1532           is broken.
1533
1534           Conventionally, block device numbers are allocated from
1535           predetermined contiguous area.  However, extended block area
1536           may introduce non-contiguous block device numbers.  This
1537           option forces most block device numbers to be allocated from
1538           the extended space and spreads them to discover kernel or
1539           userland code paths which assume predetermined contiguous
1540           device number allocation.
1541
1542           Note that turning on this debug option shuffles all the
1543           device numbers for all IDE and SCSI devices including libata
1544           ones, so root partition specified using device number
1545           directly (via rdev or root=MAJ:MIN) won't work anymore.
1546           Textual device names (root=/dev/sdXn) will continue to work.
1547
1548           Say N if you are unsure.
1549
1550 config CPU_HOTPLUG_STATE_CONTROL
1551         bool "Enable CPU hotplug state control"
1552         depends on DEBUG_KERNEL
1553         depends on HOTPLUG_CPU
1554         default n
1555         help
1556           Allows to write steps between "offline" and "online" to the CPUs
1557           sysfs target file so states can be stepped granular. This is a debug
1558           option for now as the hotplug machinery cannot be stopped and
1559           restarted at arbitrary points yet.
1560
1561           Say N if your are unsure.
1562
1563 config LATENCYTOP
1564         bool "Latency measuring infrastructure"
1565         depends on DEBUG_KERNEL
1566         depends on STACKTRACE_SUPPORT
1567         depends on PROC_FS
1568         select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86
1569         select KALLSYMS
1570         select KALLSYMS_ALL
1571         select STACKTRACE
1572         select SCHEDSTATS
1573         select SCHED_DEBUG
1574         help
1575           Enable this option if you want to use the LatencyTOP tool
1576           to find out which userspace is blocking on what kernel operations.
1577
1578 source "kernel/trace/Kconfig"
1579
1580 config PROVIDE_OHCI1394_DMA_INIT
1581         bool "Remote debugging over FireWire early on boot"
1582         depends on PCI && X86
1583         help
1584           If you want to debug problems which hang or crash the kernel early
1585           on boot and the crashing machine has a FireWire port, you can use
1586           this feature to remotely access the memory of the crashed machine
1587           over FireWire. This employs remote DMA as part of the OHCI1394
1588           specification which is now the standard for FireWire controllers.
1589
1590           With remote DMA, you can monitor the printk buffer remotely using
1591           firescope and access all memory below 4GB using fireproxy from gdb.
1592           Even controlling a kernel debugger is possible using remote DMA.
1593
1594           Usage:
1595
1596           If ohci1394_dma=early is used as boot parameter, it will initialize
1597           all OHCI1394 controllers which are found in the PCI config space.
1598
1599           As all changes to the FireWire bus such as enabling and disabling
1600           devices cause a bus reset and thereby disable remote DMA for all
1601           devices, be sure to have the cable plugged and FireWire enabled on
1602           the debugging host before booting the debug target for debugging.
1603
1604           This code (~1k) is freed after boot. By then, the firewire stack
1605           in charge of the OHCI-1394 controllers should be used instead.
1606
1607           See Documentation/core-api/debugging-via-ohci1394.rst for more information.
1608
1609 source "samples/Kconfig"
1610
1611 source "lib/Kconfig.kcsan"
1612
1613 config ARCH_HAS_DEVMEM_IS_ALLOWED
1614         bool
1615
1616 config STRICT_DEVMEM
1617         bool "Filter access to /dev/mem"
1618         depends on MMU && DEVMEM
1619         depends on ARCH_HAS_DEVMEM_IS_ALLOWED
1620         default y if PPC || X86 || ARM64
1621         help
1622           If this option is disabled, you allow userspace (root) access to all
1623           of memory, including kernel and userspace memory. Accidental
1624           access to this is obviously disastrous, but specific access can
1625           be used by people debugging the kernel. Note that with PAT support
1626           enabled, even in this case there are restrictions on /dev/mem
1627           use due to the cache aliasing requirements.
1628
1629           If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
1630           file only allows userspace access to PCI space and the BIOS code and
1631           data regions.  This is sufficient for dosemu and X and all common
1632           users of /dev/mem.
1633
1634           If in doubt, say Y.
1635
1636 config IO_STRICT_DEVMEM
1637         bool "Filter I/O access to /dev/mem"
1638         depends on STRICT_DEVMEM
1639         help
1640           If this option is disabled, you allow userspace (root) access to all
1641           io-memory regardless of whether a driver is actively using that
1642           range.  Accidental access to this is obviously disastrous, but
1643           specific access can be used by people debugging kernel drivers.
1644
1645           If this option is switched on, the /dev/mem file only allows
1646           userspace access to *idle* io-memory ranges (see /proc/iomem) This
1647           may break traditional users of /dev/mem (dosemu, legacy X, etc...)
1648           if the driver using a given range cannot be disabled.
1649
1650           If in doubt, say Y.
1651
1652 menu "$(SRCARCH) Debugging"
1653
1654 source "arch/$(SRCARCH)/Kconfig.debug"
1655
1656 endmenu
1657
1658 menu "Kernel Testing and Coverage"
1659
1660 source "lib/kunit/Kconfig"
1661
1662 config NOTIFIER_ERROR_INJECTION
1663         tristate "Notifier error injection"
1664         depends on DEBUG_KERNEL
1665         select DEBUG_FS
1666         help
1667           This option provides the ability to inject artificial errors to
1668           specified notifier chain callbacks. It is useful to test the error
1669           handling of notifier call chain failures.
1670
1671           Say N if unsure.
1672
1673 config PM_NOTIFIER_ERROR_INJECT
1674         tristate "PM notifier error injection module"
1675         depends on PM && NOTIFIER_ERROR_INJECTION
1676         default m if PM_DEBUG
1677         help
1678           This option provides the ability to inject artificial errors to
1679           PM notifier chain callbacks.  It is controlled through debugfs
1680           interface /sys/kernel/debug/notifier-error-inject/pm
1681
1682           If the notifier call chain should be failed with some events
1683           notified, write the error code to "actions/<notifier event>/error".
1684
1685           Example: Inject PM suspend error (-12 = -ENOMEM)
1686
1687           # cd /sys/kernel/debug/notifier-error-inject/pm/
1688           # echo -12 > actions/PM_SUSPEND_PREPARE/error
1689           # echo mem > /sys/power/state
1690           bash: echo: write error: Cannot allocate memory
1691
1692           To compile this code as a module, choose M here: the module will
1693           be called pm-notifier-error-inject.
1694
1695           If unsure, say N.
1696
1697 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1698         tristate "OF reconfig notifier error injection module"
1699         depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1700         help
1701           This option provides the ability to inject artificial errors to
1702           OF reconfig notifier chain callbacks.  It is controlled
1703           through debugfs interface under
1704           /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1705
1706           If the notifier call chain should be failed with some events
1707           notified, write the error code to "actions/<notifier event>/error".
1708
1709           To compile this code as a module, choose M here: the module will
1710           be called of-reconfig-notifier-error-inject.
1711
1712           If unsure, say N.
1713
1714 config NETDEV_NOTIFIER_ERROR_INJECT
1715         tristate "Netdev notifier error injection module"
1716         depends on NET && NOTIFIER_ERROR_INJECTION
1717         help
1718           This option provides the ability to inject artificial errors to
1719           netdevice notifier chain callbacks.  It is controlled through debugfs
1720           interface /sys/kernel/debug/notifier-error-inject/netdev
1721
1722           If the notifier call chain should be failed with some events
1723           notified, write the error code to "actions/<notifier event>/error".
1724
1725           Example: Inject netdevice mtu change error (-22 = -EINVAL)
1726
1727           # cd /sys/kernel/debug/notifier-error-inject/netdev
1728           # echo -22 > actions/NETDEV_CHANGEMTU/error
1729           # ip link set eth0 mtu 1024
1730           RTNETLINK answers: Invalid argument
1731
1732           To compile this code as a module, choose M here: the module will
1733           be called netdev-notifier-error-inject.
1734
1735           If unsure, say N.
1736
1737 config FUNCTION_ERROR_INJECTION
1738         def_bool y
1739         depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
1740
1741 config FAULT_INJECTION
1742         bool "Fault-injection framework"
1743         depends on DEBUG_KERNEL
1744         help
1745           Provide fault-injection framework.
1746           For more details, see Documentation/fault-injection/.
1747
1748 config FAILSLAB
1749         bool "Fault-injection capability for kmalloc"
1750         depends on FAULT_INJECTION
1751         depends on SLAB || SLUB
1752         help
1753           Provide fault-injection capability for kmalloc.
1754
1755 config FAIL_PAGE_ALLOC
1756         bool "Fault-injection capability for alloc_pages()"
1757         depends on FAULT_INJECTION
1758         help
1759           Provide fault-injection capability for alloc_pages().
1760
1761 config FAIL_MAKE_REQUEST
1762         bool "Fault-injection capability for disk IO"
1763         depends on FAULT_INJECTION && BLOCK
1764         help
1765           Provide fault-injection capability for disk IO.
1766
1767 config FAIL_IO_TIMEOUT
1768         bool "Fault-injection capability for faking disk interrupts"
1769         depends on FAULT_INJECTION && BLOCK
1770         help
1771           Provide fault-injection capability on end IO handling. This
1772           will make the block layer "forget" an interrupt as configured,
1773           thus exercising the error handling.
1774
1775           Only works with drivers that use the generic timeout handling,
1776           for others it wont do anything.
1777
1778 config FAIL_FUTEX
1779         bool "Fault-injection capability for futexes"
1780         select DEBUG_FS
1781         depends on FAULT_INJECTION && FUTEX
1782         help
1783           Provide fault-injection capability for futexes.
1784
1785 config FAULT_INJECTION_DEBUG_FS
1786         bool "Debugfs entries for fault-injection capabilities"
1787         depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1788         help
1789           Enable configuration of fault-injection capabilities via debugfs.
1790
1791 config FAIL_FUNCTION
1792         bool "Fault-injection capability for functions"
1793         depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
1794         help
1795           Provide function-based fault-injection capability.
1796           This will allow you to override a specific function with a return
1797           with given return value. As a result, function caller will see
1798           an error value and have to handle it. This is useful to test the
1799           error handling in various subsystems.
1800
1801 config FAIL_MMC_REQUEST
1802         bool "Fault-injection capability for MMC IO"
1803         depends on FAULT_INJECTION_DEBUG_FS && MMC
1804         help
1805           Provide fault-injection capability for MMC IO.
1806           This will make the mmc core return data errors. This is
1807           useful to test the error handling in the mmc block device
1808           and to test how the mmc host driver handles retries from
1809           the block device.
1810
1811 config FAULT_INJECTION_STACKTRACE_FILTER
1812         bool "stacktrace filter for fault-injection capabilities"
1813         depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1814         depends on !X86_64
1815         select STACKTRACE
1816         select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86
1817         help
1818           Provide stacktrace filter for fault-injection capabilities
1819
1820 config ARCH_HAS_KCOV
1821         bool
1822         help
1823           An architecture should select this when it can successfully
1824           build and run with CONFIG_KCOV. This typically requires
1825           disabling instrumentation for some early boot code.
1826
1827 config CC_HAS_SANCOV_TRACE_PC
1828         def_bool $(cc-option,-fsanitize-coverage=trace-pc)
1829
1830
1831 config KCOV
1832         bool "Code coverage for fuzzing"
1833         depends on ARCH_HAS_KCOV
1834         depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
1835         select DEBUG_FS
1836         select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
1837         help
1838           KCOV exposes kernel code coverage information in a form suitable
1839           for coverage-guided fuzzing (randomized testing).
1840
1841           If RANDOMIZE_BASE is enabled, PC values will not be stable across
1842           different machines and across reboots. If you need stable PC values,
1843           disable RANDOMIZE_BASE.
1844
1845           For more details, see Documentation/dev-tools/kcov.rst.
1846
1847 config KCOV_ENABLE_COMPARISONS
1848         bool "Enable comparison operands collection by KCOV"
1849         depends on KCOV
1850         depends on $(cc-option,-fsanitize-coverage=trace-cmp)
1851         help
1852           KCOV also exposes operands of every comparison in the instrumented
1853           code along with operand sizes and PCs of the comparison instructions.
1854           These operands can be used by fuzzing engines to improve the quality
1855           of fuzzing coverage.
1856
1857 config KCOV_INSTRUMENT_ALL
1858         bool "Instrument all code by default"
1859         depends on KCOV
1860         default y
1861         help
1862           If you are doing generic system call fuzzing (like e.g. syzkaller),
1863           then you will want to instrument the whole kernel and you should
1864           say y here. If you are doing more targeted fuzzing (like e.g.
1865           filesystem fuzzing with AFL) then you will want to enable coverage
1866           for more specific subsets of files, and should say n here.
1867
1868 config KCOV_IRQ_AREA_SIZE
1869         hex "Size of interrupt coverage collection area in words"
1870         depends on KCOV
1871         default 0x40000
1872         help
1873           KCOV uses preallocated per-cpu areas to collect coverage from
1874           soft interrupts. This specifies the size of those areas in the
1875           number of unsigned long words.
1876
1877 menuconfig RUNTIME_TESTING_MENU
1878         bool "Runtime Testing"
1879         def_bool y
1880
1881 if RUNTIME_TESTING_MENU
1882
1883 config LKDTM
1884         tristate "Linux Kernel Dump Test Tool Module"
1885         depends on DEBUG_FS
1886         help
1887         This module enables testing of the different dumping mechanisms by
1888         inducing system failures at predefined crash points.
1889         If you don't need it: say N
1890         Choose M here to compile this code as a module. The module will be
1891         called lkdtm.
1892
1893         Documentation on how to use the module can be found in
1894         Documentation/fault-injection/provoke-crashes.rst
1895
1896 config TEST_LIST_SORT
1897         tristate "Linked list sorting test"
1898         depends on DEBUG_KERNEL || m
1899         help
1900           Enable this to turn on 'list_sort()' function test. This test is
1901           executed only once during system boot (so affects only boot time),
1902           or at module load time.
1903
1904           If unsure, say N.
1905
1906 config TEST_MIN_HEAP
1907         tristate "Min heap test"
1908         depends on DEBUG_KERNEL || m
1909         help
1910           Enable this to turn on min heap function tests. This test is
1911           executed only once during system boot (so affects only boot time),
1912           or at module load time.
1913
1914           If unsure, say N.
1915
1916 config TEST_SORT
1917         tristate "Array-based sort test"
1918         depends on DEBUG_KERNEL || m
1919         help
1920           This option enables the self-test function of 'sort()' at boot,
1921           or at module load time.
1922
1923           If unsure, say N.
1924
1925 config KPROBES_SANITY_TEST
1926         bool "Kprobes sanity tests"
1927         depends on DEBUG_KERNEL
1928         depends on KPROBES
1929         help
1930           This option provides for testing basic kprobes functionality on
1931           boot. Samples of kprobe and kretprobe are inserted and
1932           verified for functionality.
1933
1934           Say N if you are unsure.
1935
1936 config BACKTRACE_SELF_TEST
1937         tristate "Self test for the backtrace code"
1938         depends on DEBUG_KERNEL
1939         help
1940           This option provides a kernel module that can be used to test
1941           the kernel stack backtrace code. This option is not useful
1942           for distributions or general kernels, but only for kernel
1943           developers working on architecture code.
1944
1945           Note that if you want to also test saved backtraces, you will
1946           have to enable STACKTRACE as well.
1947
1948           Say N if you are unsure.
1949
1950 config RBTREE_TEST
1951         tristate "Red-Black tree test"
1952         depends on DEBUG_KERNEL
1953         help
1954           A benchmark measuring the performance of the rbtree library.
1955           Also includes rbtree invariant checks.
1956
1957 config REED_SOLOMON_TEST
1958         tristate "Reed-Solomon library test"
1959         depends on DEBUG_KERNEL || m
1960         select REED_SOLOMON
1961         select REED_SOLOMON_ENC16
1962         select REED_SOLOMON_DEC16
1963         help
1964           This option enables the self-test function of rslib at boot,
1965           or at module load time.
1966
1967           If unsure, say N.
1968
1969 config INTERVAL_TREE_TEST
1970         tristate "Interval tree test"
1971         depends on DEBUG_KERNEL
1972         select INTERVAL_TREE
1973         help
1974           A benchmark measuring the performance of the interval tree library
1975
1976 config PERCPU_TEST
1977         tristate "Per cpu operations test"
1978         depends on m && DEBUG_KERNEL
1979         help
1980           Enable this option to build test module which validates per-cpu
1981           operations.
1982
1983           If unsure, say N.
1984
1985 config ATOMIC64_SELFTEST
1986         tristate "Perform an atomic64_t self-test"
1987         help
1988           Enable this option to test the atomic64_t functions at boot or
1989           at module load time.
1990
1991           If unsure, say N.
1992
1993 config ASYNC_RAID6_TEST
1994         tristate "Self test for hardware accelerated raid6 recovery"
1995         depends on ASYNC_RAID6_RECOV
1996         select ASYNC_MEMCPY
1997         help
1998           This is a one-shot self test that permutes through the
1999           recovery of all the possible two disk failure scenarios for a
2000           N-disk array.  Recovery is performed with the asynchronous
2001           raid6 recovery routines, and will optionally use an offload
2002           engine if one is available.
2003
2004           If unsure, say N.
2005
2006 config TEST_HEXDUMP
2007         tristate "Test functions located in the hexdump module at runtime"
2008
2009 config TEST_STRING_HELPERS
2010         tristate "Test functions located in the string_helpers module at runtime"
2011
2012 config TEST_STRSCPY
2013         tristate "Test strscpy*() family of functions at runtime"
2014
2015 config TEST_KSTRTOX
2016         tristate "Test kstrto*() family of functions at runtime"
2017
2018 config TEST_PRINTF
2019         tristate "Test printf() family of functions at runtime"
2020
2021 config TEST_BITMAP
2022         tristate "Test bitmap_*() family of functions at runtime"
2023         help
2024           Enable this option to test the bitmap functions at boot.
2025
2026           If unsure, say N.
2027
2028 config TEST_BITFIELD
2029         tristate "Test bitfield functions at runtime"
2030         help
2031           Enable this option to test the bitfield functions at boot.
2032
2033           If unsure, say N.
2034
2035 config TEST_UUID
2036         tristate "Test functions located in the uuid module at runtime"
2037
2038 config TEST_XARRAY
2039         tristate "Test the XArray code at runtime"
2040
2041 config TEST_OVERFLOW
2042         tristate "Test check_*_overflow() functions at runtime"
2043
2044 config TEST_RHASHTABLE
2045         tristate "Perform selftest on resizable hash table"
2046         help
2047           Enable this option to test the rhashtable functions at boot.
2048
2049           If unsure, say N.
2050
2051 config TEST_HASH
2052         tristate "Perform selftest on hash functions"
2053         help
2054           Enable this option to test the kernel's integer (<linux/hash.h>),
2055           string (<linux/stringhash.h>), and siphash (<linux/siphash.h>)
2056           hash functions on boot (or module load).
2057
2058           This is intended to help people writing architecture-specific
2059           optimized versions.  If unsure, say N.
2060
2061 config TEST_IDA
2062         tristate "Perform selftest on IDA functions"
2063
2064 config TEST_PARMAN
2065         tristate "Perform selftest on priority array manager"
2066         depends on PARMAN
2067         help
2068           Enable this option to test priority array manager on boot
2069           (or module load).
2070
2071           If unsure, say N.
2072
2073 config TEST_IRQ_TIMINGS
2074         bool "IRQ timings selftest"
2075         depends on IRQ_TIMINGS
2076         help
2077           Enable this option to test the irq timings code on boot.
2078
2079           If unsure, say N.
2080
2081 config TEST_LKM
2082         tristate "Test module loading with 'hello world' module"
2083         depends on m
2084         help
2085           This builds the "test_module" module that emits "Hello, world"
2086           on printk when loaded. It is designed to be used for basic
2087           evaluation of the module loading subsystem (for example when
2088           validating module verification). It lacks any extra dependencies,
2089           and will not normally be loaded by the system unless explicitly
2090           requested by name.
2091
2092           If unsure, say N.
2093
2094 config TEST_BITOPS
2095         tristate "Test module for compilation of bitops operations"
2096         depends on m
2097         help
2098           This builds the "test_bitops" module that is much like the
2099           TEST_LKM module except that it does a basic exercise of the
2100           set/clear_bit macros and get_count_order/long to make sure there are
2101           no compiler warnings from C=1 sparse checker or -Wextra
2102           compilations. It has no dependencies and doesn't run or load unless
2103           explicitly requested by name.  for example: modprobe test_bitops.
2104
2105           If unsure, say N.
2106
2107 config TEST_VMALLOC
2108         tristate "Test module for stress/performance analysis of vmalloc allocator"
2109         default n
2110        depends on MMU
2111         depends on m
2112         help
2113           This builds the "test_vmalloc" module that should be used for
2114           stress and performance analysis. So, any new change for vmalloc
2115           subsystem can be evaluated from performance and stability point
2116           of view.
2117
2118           If unsure, say N.
2119
2120 config TEST_USER_COPY
2121         tristate "Test user/kernel boundary protections"
2122         depends on m
2123         help
2124           This builds the "test_user_copy" module that runs sanity checks
2125           on the copy_to/from_user infrastructure, making sure basic
2126           user/kernel boundary testing is working. If it fails to load,
2127           a regression has been detected in the user/kernel memory boundary
2128           protections.
2129
2130           If unsure, say N.
2131
2132 config TEST_BPF
2133         tristate "Test BPF filter functionality"
2134         depends on m && NET
2135         help
2136           This builds the "test_bpf" module that runs various test vectors
2137           against the BPF interpreter or BPF JIT compiler depending on the
2138           current setting. This is in particular useful for BPF JIT compiler
2139           development, but also to run regression tests against changes in
2140           the interpreter code. It also enables test stubs for eBPF maps and
2141           verifier used by user space verifier testsuite.
2142
2143           If unsure, say N.
2144
2145 config TEST_BLACKHOLE_DEV
2146         tristate "Test blackhole netdev functionality"
2147         depends on m && NET
2148         help
2149           This builds the "test_blackhole_dev" module that validates the
2150           data path through this blackhole netdev.
2151
2152           If unsure, say N.
2153
2154 config FIND_BIT_BENCHMARK
2155         tristate "Test find_bit functions"
2156         help
2157           This builds the "test_find_bit" module that measure find_*_bit()
2158           functions performance.
2159
2160           If unsure, say N.
2161
2162 config TEST_FIRMWARE
2163         tristate "Test firmware loading via userspace interface"
2164         depends on FW_LOADER
2165         help
2166           This builds the "test_firmware" module that creates a userspace
2167           interface for testing firmware loading. This can be used to
2168           control the triggering of firmware loading without needing an
2169           actual firmware-using device. The contents can be rechecked by
2170           userspace.
2171
2172           If unsure, say N.
2173
2174 config TEST_SYSCTL
2175         tristate "sysctl test driver"
2176         depends on PROC_SYSCTL
2177         help
2178           This builds the "test_sysctl" module. This driver enables to test the
2179           proc sysctl interfaces available to drivers safely without affecting
2180           production knobs which might alter system functionality.
2181
2182           If unsure, say N.
2183
2184 config SYSCTL_KUNIT_TEST
2185         tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS
2186         depends on KUNIT
2187         default KUNIT_ALL_TESTS
2188         help
2189           This builds the proc sysctl unit test, which runs on boot.
2190           Tests the API contract and implementation correctness of sysctl.
2191           For more information on KUnit and unit tests in general please refer
2192           to the KUnit documentation in Documentation/dev-tools/kunit/.
2193
2194           If unsure, say N.
2195
2196 config LIST_KUNIT_TEST
2197         tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS
2198         depends on KUNIT
2199         default KUNIT_ALL_TESTS
2200         help
2201           This builds the linked list KUnit test suite.
2202           It tests that the API and basic functionality of the list_head type
2203           and associated macros.
2204
2205           KUnit tests run during boot and output the results to the debug log
2206           in TAP format (http://testanything.org/). Only useful for kernel devs
2207           running the KUnit test harness, and not intended for inclusion into a
2208           production build.
2209
2210           For more information on KUnit and unit tests in general please refer
2211           to the KUnit documentation in Documentation/dev-tools/kunit/.
2212
2213           If unsure, say N.
2214
2215 config LINEAR_RANGES_TEST
2216         tristate "KUnit test for linear_ranges"
2217         depends on KUNIT
2218         select LINEAR_RANGES
2219         help
2220           This builds the linear_ranges unit test, which runs on boot.
2221           Tests the linear_ranges logic correctness.
2222           For more information on KUnit and unit tests in general please refer
2223           to the KUnit documentation in Documentation/dev-tools/kunit/.
2224
2225           If unsure, say N.
2226
2227 config TEST_UDELAY
2228         tristate "udelay test driver"
2229         help
2230           This builds the "udelay_test" module that helps to make sure
2231           that udelay() is working properly.
2232
2233           If unsure, say N.
2234
2235 config TEST_STATIC_KEYS
2236         tristate "Test static keys"
2237         depends on m
2238         help
2239           Test the static key interfaces.
2240
2241           If unsure, say N.
2242
2243 config TEST_KMOD
2244         tristate "kmod stress tester"
2245         depends on m
2246         depends on NETDEVICES && NET_CORE && INET # for TUN
2247         depends on BLOCK
2248         select TEST_LKM
2249         select XFS_FS
2250         select TUN
2251         select BTRFS_FS
2252         help
2253           Test the kernel's module loading mechanism: kmod. kmod implements
2254           support to load modules using the Linux kernel's usermode helper.
2255           This test provides a series of tests against kmod.
2256
2257           Although technically you can either build test_kmod as a module or
2258           into the kernel we disallow building it into the kernel since
2259           it stress tests request_module() and this will very likely cause
2260           some issues by taking over precious threads available from other
2261           module load requests, ultimately this could be fatal.
2262
2263           To run tests run:
2264
2265           tools/testing/selftests/kmod/kmod.sh --help
2266
2267           If unsure, say N.
2268
2269 config TEST_DEBUG_VIRTUAL
2270         tristate "Test CONFIG_DEBUG_VIRTUAL feature"
2271         depends on DEBUG_VIRTUAL
2272         help
2273           Test the kernel's ability to detect incorrect calls to
2274           virt_to_phys() done against the non-linear part of the
2275           kernel's virtual address map.
2276
2277           If unsure, say N.
2278
2279 config TEST_MEMCAT_P
2280         tristate "Test memcat_p() helper function"
2281         help
2282           Test the memcat_p() helper for correctly merging two
2283           pointer arrays together.
2284
2285           If unsure, say N.
2286
2287 config TEST_LIVEPATCH
2288         tristate "Test livepatching"
2289         default n
2290         depends on DYNAMIC_DEBUG
2291         depends on LIVEPATCH
2292         depends on m
2293         help
2294           Test kernel livepatching features for correctness.  The tests will
2295           load test modules that will be livepatched in various scenarios.
2296
2297           To run all the livepatching tests:
2298
2299           make -C tools/testing/selftests TARGETS=livepatch run_tests
2300
2301           Alternatively, individual tests may be invoked:
2302
2303           tools/testing/selftests/livepatch/test-callbacks.sh
2304           tools/testing/selftests/livepatch/test-livepatch.sh
2305           tools/testing/selftests/livepatch/test-shadow-vars.sh
2306
2307           If unsure, say N.
2308
2309 config TEST_OBJAGG
2310         tristate "Perform selftest on object aggreration manager"
2311         default n
2312         depends on OBJAGG
2313         help
2314           Enable this option to test object aggregation manager on boot
2315           (or module load).
2316
2317
2318 config TEST_STACKINIT
2319         tristate "Test level of stack variable initialization"
2320         help
2321           Test if the kernel is zero-initializing stack variables and
2322           padding. Coverage is controlled by compiler flags,
2323           CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2324           or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2325
2326           If unsure, say N.
2327
2328 config TEST_MEMINIT
2329         tristate "Test heap/page initialization"
2330         help
2331           Test if the kernel is zero-initializing heap and page allocations.
2332           This can be useful to test init_on_alloc and init_on_free features.
2333
2334           If unsure, say N.
2335
2336 config TEST_HMM
2337         tristate "Test HMM (Heterogeneous Memory Management)"
2338         depends on TRANSPARENT_HUGEPAGE
2339         depends on DEVICE_PRIVATE
2340         select HMM_MIRROR
2341         select MMU_NOTIFIER
2342         help
2343           This is a pseudo device driver solely for testing HMM.
2344           Say M here if you want to build the HMM test module.
2345           Doing so will allow you to run tools/testing/selftest/vm/hmm-tests.
2346
2347           If unsure, say N.
2348
2349 config TEST_FPU
2350         tristate "Test floating point operations in kernel space"
2351         depends on X86 && !KCOV_INSTRUMENT_ALL
2352         help
2353           Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu
2354           which will trigger a sequence of floating point operations. This is used
2355           for self-testing floating point control register setting in
2356           kernel_fpu_begin().
2357
2358           If unsure, say N.
2359
2360 endif # RUNTIME_TESTING_MENU
2361
2362 config MEMTEST
2363         bool "Memtest"
2364         help
2365           This option adds a kernel parameter 'memtest', which allows memtest
2366           to be set.
2367                 memtest=0, mean disabled; -- default
2368                 memtest=1, mean do 1 test pattern;
2369                 ...
2370                 memtest=17, mean do 17 test patterns.
2371           If you are unsure how to answer this question, answer N.
2372
2373
2374
2375 config HYPERV_TESTING
2376         bool "Microsoft Hyper-V driver testing"
2377         default n
2378         depends on HYPERV && DEBUG_FS
2379         help
2380           Select this option to enable Hyper-V vmbus testing.
2381
2382 endmenu # "Kernel Testing and Coverage"
2383
2384 endmenu # Kernel hacking