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
 102         help
 103
 104           Compiles debug level messages into the kernel, which would not
 105           otherwise be available at runtime. These messages can then be
 106           enabled/disabled based on various levels of scope - per source file,
 107           function, module, format string, and line number. This mechanism
 108           implicitly compiles in all pr_debug() and dev_dbg() calls, which
 109           enlarges the kernel text size by about 2%.
 110
 111           If a source file is compiled with DEBUG flag set, any
 112           pr_debug() calls in it are enabled by default, but can be
 113           disabled at runtime as below.  Note that DEBUG flag is
 114           turned on by many CONFIG_*DEBUG* options.
 115
 116           Usage:
 117
 118           Dynamic debugging is controlled via the 'dynamic_debug/control' file,
 119           which is contained in the 'debugfs' filesystem. Thus, the debugfs
 120           filesystem must first be mounted before making use of this feature.
 121           We refer the control file as: <debugfs>/dynamic_debug/control. This
 122           file contains a list of the debug statements that can be enabled. The
 123           format for each line of the file is:
 124
 125                 filename:lineno [module]function flags format
 126
 127           filename : source file of the debug statement
 128           lineno : line number of the debug statement
 129           module : module that contains the debug statement
 130           function : function that contains the debug statement
 131           flags : '=p' means the line is turned 'on' for printing
 132           format : the format used for the debug statement
 133
 134           From a live system:
 135
 136                 nullarbor:~ # cat <debugfs>/dynamic_debug/control
 137                 # filename:lineno [module]function flags format
 138                 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
 139                 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
 140                 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
 141
 142           Example usage:
 143
 144                 // enable the message at line 1603 of file svcsock.c
 145                 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
 146                                                 <debugfs>/dynamic_debug/control
 147
 148                 // enable all the messages in file svcsock.c
 149                 nullarbor:~ # echo -n 'file svcsock.c +p' >
 150                                                 <debugfs>/dynamic_debug/control
 151
 152                 // enable all the messages in the NFS server module
 153                 nullarbor:~ # echo -n 'module nfsd +p' >
 154                                                 <debugfs>/dynamic_debug/control
 155
 156                 // enable all 12 messages in the function svc_process()
 157                 nullarbor:~ # echo -n 'func svc_process +p' >
 158                                                 <debugfs>/dynamic_debug/control
 159
 160                 // disable all 12 messages in the function svc_process()
 161                 nullarbor:~ # echo -n 'func svc_process -p' >
 162                                                 <debugfs>/dynamic_debug/control
 163
 164           See Documentation/admin-guide/dynamic-debug-howto.rst for additional
 165           information.
 166
 167 endmenu # "printk and dmesg options"
 168
 169 menu "Compile-time checks and compiler options"
 170
 171 config DEBUG_INFO
 172         bool "Compile the kernel with debug info"
 173         depends on DEBUG_KERNEL && !COMPILE_TEST
 174         help
 175           If you say Y here the resulting kernel image will include
 176           debugging info resulting in a larger kernel image.
 177           This adds debug symbols to the kernel and modules (gcc -g), and
 178           is needed if you intend to use kernel crashdump or binary object
 179           tools like crash, kgdb, LKCD, gdb, etc on the kernel.
 180           Say Y here only if you plan to debug the kernel.
 181
 182           If unsure, say N.
 183
 184 config DEBUG_INFO_REDUCED
 185         bool "Reduce debugging information"
 186         depends on DEBUG_INFO
 187         help
 188           If you say Y here gcc is instructed to generate less debugging
 189           information for structure types. This means that tools that
 190           need full debugging information (like kgdb or systemtap) won't
 191           be happy. But if you merely need debugging information to
 192           resolve line numbers there is no loss. Advantage is that
 193           build directory object sizes shrink dramatically over a full
 194           DEBUG_INFO build and compile times are reduced too.
 195           Only works with newer gcc versions.
 196
 197 config DEBUG_INFO_SPLIT
 198         bool "Produce split debuginfo in .dwo files"
 199         depends on DEBUG_INFO
 200         depends on $(cc-option,-gsplit-dwarf)
 201         help
 202           Generate debug info into separate .dwo files. This significantly
 203           reduces the build directory size for builds with DEBUG_INFO,
 204           because it stores the information only once on disk in .dwo
 205           files instead of multiple times in object files and executables.
 206           In addition the debug information is also compressed.
 207
 208           Requires recent gcc (4.7+) and recent gdb/binutils.
 209           Any tool that packages or reads debug information would need
 210           to know about the .dwo files and include them.
 211           Incompatible with older versions of ccache.
 212
 213 config DEBUG_INFO_DWARF4
 214         bool "Generate dwarf4 debuginfo"
 215         depends on DEBUG_INFO
 216         depends on $(cc-option,-gdwarf-4)
 217         help
 218           Generate dwarf4 debug info. This requires recent versions
 219           of gcc and gdb. It makes the debug information larger.
 220           But it significantly improves the success of resolving
 221           variables in gdb on optimized code.
 222
 223 config DEBUG_INFO_BTF
 224         bool "Generate BTF typeinfo"
 225         depends on DEBUG_INFO
 226         help
 227           Generate deduplicated BTF type information from DWARF debug info.
 228           Turning this on expects presence of pahole tool, which will convert
 229           DWARF type info into equivalent deduplicated BTF type info.
 230
 231 config GDB_SCRIPTS
 232         bool "Provide GDB scripts for kernel debugging"
 233         depends on DEBUG_INFO
 234         help
 235           This creates the required links to GDB helper scripts in the
 236           build directory. If you load vmlinux into gdb, the helper
 237           scripts will be automatically imported by gdb as well, and
 238           additional functions are available to analyze a Linux kernel
 239           instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
 240           for further details.
 241
 242 config ENABLE_MUST_CHECK
 243         bool "Enable __must_check logic"
 244         default y
 245         help
 246           Enable the __must_check logic in the kernel build.  Disable this to
 247           suppress the "warning: ignoring return value of 'foo', declared with
 248           attribute warn_unused_result" messages.
 249
 250 config FRAME_WARN
 251         int "Warn for stack frames larger than (needs gcc 4.4)"
 252         range 0 8192
 253         default 2048 if GCC_PLUGIN_LATENT_ENTROPY
 254         default 1280 if (!64BIT && PARISC)
 255         default 1024 if (!64BIT && !PARISC)
 256         default 2048 if 64BIT
 257         help
 258           Tell gcc to warn at build time for stack frames larger than this.
 259           Setting this too low will cause a lot of warnings.
 260           Setting it to 0 disables the warning.
 261           Requires gcc 4.4
 262
 263 config STRIP_ASM_SYMS
 264         bool "Strip assembler-generated symbols during link"
 265         default n
 266         help
 267           Strip internal assembler-generated symbols during a link (symbols
 268           that look like '.Lxxx') so they don't pollute the output of
 269           get_wchan() and suchlike.
 270
 271 config READABLE_ASM
 272         bool "Generate readable assembler code"
 273         depends on DEBUG_KERNEL
 274         help
 275           Disable some compiler optimizations that tend to generate human unreadable
 276           assembler output. This may make the kernel slightly slower, but it helps
 277           to keep kernel developers who have to stare a lot at assembler listings
 278           sane.
 279
 280 config UNUSED_SYMBOLS
 281         bool "Enable unused/obsolete exported symbols"
 282         default y if X86
 283         help
 284           Unused but exported symbols make the kernel needlessly bigger.  For
 285           that reason most of these unused exports will soon be removed.  This
 286           option is provided temporarily to provide a transition period in case
 287           some external kernel module needs one of these symbols anyway. If you
 288           encounter such a case in your module, consider if you are actually
 289           using the right API.  (rationale: since nobody in the kernel is using
 290           this in a module, there is a pretty good chance it's actually the
 291           wrong interface to use).  If you really need the symbol, please send a
 292           mail to the linux kernel mailing list mentioning the symbol and why
 293           you really need it, and what the merge plan to the mainline kernel for
 294           your module is.
 295
 296 config DEBUG_FS
 297         bool "Debug Filesystem"
 298         help
 299           debugfs is a virtual file system that kernel developers use to put
 300           debugging files into.  Enable this option to be able to read and
 301           write to these files.
 302
 303           For detailed documentation on the debugfs API, see
 304           Documentation/filesystems/.
 305
 306           If unsure, say N.
 307
 308 config HEADERS_CHECK
 309         bool "Run 'make headers_check' when building vmlinux"
 310         depends on !UML
 311         help
 312           This option will extract the user-visible kernel headers whenever
 313           building the kernel, and will run basic sanity checks on them to
 314           ensure that exported files do not attempt to include files which
 315           were not exported, etc.
 316
 317           If you're making modifications to header files which are
 318           relevant for userspace, say 'Y', and check the headers
 319           exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
 320           your build tree), to make sure they're suitable.
 321
 322 config OPTIMIZE_INLINING
 323         bool "Allow compiler to uninline functions marked 'inline'"
 324         help
 325           This option determines if the kernel forces gcc to inline the functions
 326           developers have marked 'inline'. Doing so takes away freedom from gcc to
 327           do what it thinks is best, which is desirable for the gcc 3.x series of
 328           compilers. The gcc 4.x series have a rewritten inlining algorithm and
 329           enabling this option will generate a smaller kernel there. Hopefully
 330           this algorithm is so good that allowing gcc 4.x and above to make the
 331           decision will become the default in the future. Until then this option
 332           is there to test gcc for this.
 333
 334           If unsure, say N.
 335
 336 config DEBUG_SECTION_MISMATCH
 337         bool "Enable full Section mismatch analysis"
 338         help
 339           The section mismatch analysis checks if there are illegal
 340           references from one section to another section.
 341           During linktime or runtime, some sections are dropped;
 342           any use of code/data previously in these sections would
 343           most likely result in an oops.
 344           In the code, functions and variables are annotated with
 345           __init,, etc. (see the full list in include/linux/init.h),
 346           which results in the code/data being placed in specific sections.
 347           The section mismatch analysis is always performed after a full
 348           kernel build, and enabling this option causes the following
 349           additional steps to occur:
 350           - Add the option -fno-inline-functions-called-once to gcc commands.
 351             When inlining a function annotated with __init in a non-init
 352             function, we would lose the section information and thus
 353             the analysis would not catch the illegal reference.
 354             This option tells gcc to inline less (but it does result in
 355             a larger kernel).
 356           - Run the section mismatch analysis for each module/built-in.a file.
 357             When we run the section mismatch analysis on vmlinux.o, we
 358             lose valuable information about where the mismatch was
 359             introduced.
 360             Running the analysis for each module/built-in.a file
 361             tells where the mismatch happens much closer to the
 362             source. The drawback is that the same mismatch is
 363             reported at least twice.
 364           - Enable verbose reporting from modpost in order to help resolve
 365             the section mismatches that are reported.
 366
 367 config SECTION_MISMATCH_WARN_ONLY
 368         bool "Make section mismatch errors non-fatal"
 369         default y
 370         help
 371           If you say N here, the build process will fail if there are any
 372           section mismatch, instead of just throwing warnings.
 373
 374           If unsure, say Y.
 375
 376 #
 377 # Select this config option from the architecture Kconfig, if it
 378 # is preferred to always offer frame pointers as a config
 379 # option on the architecture (regardless of KERNEL_DEBUG):
 380 #
 381 config ARCH_WANT_FRAME_POINTERS
 382         bool
 383
 384 config FRAME_POINTER
 385         bool "Compile the kernel with frame pointers"
 386         depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
 387         default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
 388         help
 389           If you say Y here the resulting kernel image will be slightly
 390           larger and slower, but it gives very useful debugging information
 391           in case of kernel bugs. (precise oopses/stacktraces/warnings)
 392
 393 config STACK_VALIDATION
 394         bool "Compile-time stack metadata validation"
 395         depends on HAVE_STACK_VALIDATION
 396         default n
 397         help
 398           Add compile-time checks to validate stack metadata, including frame
 399           pointers (if CONFIG_FRAME_POINTER is enabled).  This helps ensure
 400           that runtime stack traces are more reliable.
 401
 402           This is also a prerequisite for generation of ORC unwind data, which
 403           is needed for CONFIG_UNWINDER_ORC.
 404
 405           For more information, see
 406           tools/objtool/Documentation/stack-validation.txt.
 407
 408 config DEBUG_FORCE_WEAK_PER_CPU
 409         bool "Force weak per-cpu definitions"
 410         depends on DEBUG_KERNEL
 411         help
 412           s390 and alpha require percpu variables in modules to be
 413           defined weak to work around addressing range issue which
 414           puts the following two restrictions on percpu variable
 415           definitions.
 416
 417           1. percpu symbols must be unique whether static or not
 418           2. percpu variables can't be defined inside a function
 419
 420           To ensure that generic code follows the above rules, this
 421           option forces all percpu variables to be defined as weak.
 422
 423 endmenu # "Compiler options"
 424
 425 config MAGIC_SYSRQ
 426         bool "Magic SysRq key"
 427         depends on !UML
 428         help
 429           If you say Y here, you will have some control over the system even
 430           if the system crashes for example during kernel debugging (e.g., you
 431           will be able to flush the buffer cache to disk, reboot the system
 432           immediately or dump some status information). This is accomplished
 433           by pressing various keys while holding SysRq (Alt+PrintScreen). It
 434           also works on a serial console (on PC hardware at least), if you
 435           send a BREAK and then within 5 seconds a command keypress. The
 436           keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
 437           Don't say Y unless you really know what this hack does.
 438
 439 config MAGIC_SYSRQ_DEFAULT_ENABLE
 440         hex "Enable magic SysRq key functions by default"
 441         depends on MAGIC_SYSRQ
 442         default 0x1
 443         help
 444           Specifies which SysRq key functions are enabled by default.
 445           This may be set to 1 or 0 to enable or disable them all, or
 446           to a bitmask as described in Documentation/admin-guide/sysrq.rst.
 447
 448 config MAGIC_SYSRQ_SERIAL
 449         bool "Enable magic SysRq key over serial"
 450         depends on MAGIC_SYSRQ
 451         default y
 452         help
 453           Many embedded boards have a disconnected TTL level serial which can
 454           generate some garbage that can lead to spurious false sysrq detects.
 455           This option allows you to decide whether you want to enable the
 456           magic SysRq key.
 457
 458 config DEBUG_KERNEL
 459         bool "Kernel debugging"
 460         help
 461           Say Y here if you are developing drivers or trying to debug and
 462           identify kernel problems.
 463
 464 config DEBUG_MISC
 465         bool "Miscellaneous debug code"
 466         default DEBUG_KERNEL
 467         depends on DEBUG_KERNEL
 468         help
 469           Say Y here if you need to enable miscellaneous debug code that should
 470           be under a more specific debug option but isn't.
 471
 472
 473 menu "Memory Debugging"
 474
 475 source "mm/Kconfig.debug"
 476
 477 config DEBUG_OBJECTS
 478         bool "Debug object operations"
 479         depends on DEBUG_KERNEL
 480         help
 481           If you say Y here, additional code will be inserted into the
 482           kernel to track the life time of various objects and validate
 483           the operations on those objects.
 484
 485 config DEBUG_OBJECTS_SELFTEST
 486         bool "Debug objects selftest"
 487         depends on DEBUG_OBJECTS
 488         help
 489           This enables the selftest of the object debug code.
 490
 491 config DEBUG_OBJECTS_FREE
 492         bool "Debug objects in freed memory"
 493         depends on DEBUG_OBJECTS
 494         help
 495           This enables checks whether a k/v free operation frees an area
 496           which contains an object which has not been deactivated
 497           properly. This can make kmalloc/kfree-intensive workloads
 498           much slower.
 499
 500 config DEBUG_OBJECTS_TIMERS
 501         bool "Debug timer objects"
 502         depends on DEBUG_OBJECTS
 503         help
 504           If you say Y here, additional code will be inserted into the
 505           timer routines to track the life time of timer objects and
 506           validate the timer operations.
 507
 508 config DEBUG_OBJECTS_WORK
 509         bool "Debug work objects"
 510         depends on DEBUG_OBJECTS
 511         help
 512           If you say Y here, additional code will be inserted into the
 513           work queue routines to track the life time of work objects and
 514           validate the work operations.
 515
 516 config DEBUG_OBJECTS_RCU_HEAD
 517         bool "Debug RCU callbacks objects"
 518         depends on DEBUG_OBJECTS
 519         help
 520           Enable this to turn on debugging of RCU list heads (call_rcu() usage).
 521
 522 config DEBUG_OBJECTS_PERCPU_COUNTER
 523         bool "Debug percpu counter objects"
 524         depends on DEBUG_OBJECTS
 525         help
 526           If you say Y here, additional code will be inserted into the
 527           percpu counter routines to track the life time of percpu counter
 528           objects and validate the percpu counter operations.
 529
 530 config DEBUG_OBJECTS_ENABLE_DEFAULT
 531         int "debug_objects bootup default value (0-1)"
 532         range 0 1
 533         default "1"
 534         depends on DEBUG_OBJECTS
 535         help
 536           Debug objects boot parameter default value
 537
 538 config DEBUG_SLAB
 539         bool "Debug slab memory allocations"
 540         depends on DEBUG_KERNEL && SLAB
 541         help
 542           Say Y here to have the kernel do limited verification on memory
 543           allocation as well as poisoning memory on free to catch use of freed
 544           memory. This can make kmalloc/kfree-intensive workloads much slower.
 545
 546 config SLUB_DEBUG_ON
 547         bool "SLUB debugging on by default"
 548         depends on SLUB && SLUB_DEBUG
 549         default n
 550         help
 551           Boot with debugging on by default. SLUB boots by default with
 552           the runtime debug capabilities switched off. Enabling this is
 553           equivalent to specifying the "slub_debug" parameter on boot.
 554           There is no support for more fine grained debug control like
 555           possible with slub_debug=xxx. SLUB debugging may be switched
 556           off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
 557           "slub_debug=-".
 558
 559 config SLUB_STATS
 560         default n
 561         bool "Enable SLUB performance statistics"
 562         depends on SLUB && SYSFS
 563         help
 564           SLUB statistics are useful to debug SLUBs allocation behavior in
 565           order find ways to optimize the allocator. This should never be
 566           enabled for production use since keeping statistics slows down
 567           the allocator by a few percentage points. The slabinfo command
 568           supports the determination of the most active slabs to figure
 569           out which slabs are relevant to a particular load.
 570           Try running: slabinfo -DA
 571
 572 config HAVE_DEBUG_KMEMLEAK
 573         bool
 574
 575 config DEBUG_KMEMLEAK
 576         bool "Kernel memory leak detector"
 577         depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
 578         select DEBUG_FS
 579         select STACKTRACE if STACKTRACE_SUPPORT
 580         select KALLSYMS
 581         select CRC32
 582         help
 583           Say Y here if you want to enable the memory leak
 584           detector. The memory allocation/freeing is traced in a way
 585           similar to the Boehm's conservative garbage collector, the
 586           difference being that the orphan objects are not freed but
 587           only shown in /sys/kernel/debug/kmemleak. Enabling this
 588           feature will introduce an overhead to memory
 589           allocations. See Documentation/dev-tools/kmemleak.rst for more
 590           details.
 591
 592           Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
 593           of finding leaks due to the slab objects poisoning.
 594
 595           In order to access the kmemleak file, debugfs needs to be
 596           mounted (usually at /sys/kernel/debug).
 597
 598 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
 599         int "Maximum kmemleak early log entries"
 600         depends on DEBUG_KMEMLEAK
 601         range 200 40000
 602         default 400
 603         help
 604           Kmemleak must track all the memory allocations to avoid
 605           reporting false positives. Since memory may be allocated or
 606           freed before kmemleak is initialised, an early log buffer is
 607           used to store these actions. If kmemleak reports "early log
 608           buffer exceeded", please increase this value.
 609
 610 config DEBUG_KMEMLEAK_TEST
 611         tristate "Simple test for the kernel memory leak detector"
 612         depends on DEBUG_KMEMLEAK && m
 613         help
 614           This option enables a module that explicitly leaks memory.
 615
 616           If unsure, say N.
 617
 618 config DEBUG_KMEMLEAK_DEFAULT_OFF
 619         bool "Default kmemleak to off"
 620         depends on DEBUG_KMEMLEAK
 621         help
 622           Say Y here to disable kmemleak by default. It can then be enabled
 623           on the command line via kmemleak=on.
 624
 625 config DEBUG_KMEMLEAK_AUTO_SCAN
 626         bool "Enable kmemleak auto scan thread on boot up"
 627         default y
 628         depends on DEBUG_KMEMLEAK
 629         help
 630           Depending on the cpu, kmemleak scan may be cpu intensive and can
 631           stall user tasks at times. This option enables/disables automatic
 632           kmemleak scan at boot up.
 633
 634           Say N here to disable kmemleak auto scan thread to stop automatic
 635           scanning. Disabling this option disables automatic reporting of
 636           memory leaks.
 637
 638           If unsure, say Y.
 639
 640 config DEBUG_STACK_USAGE
 641         bool "Stack utilization instrumentation"
 642         depends on DEBUG_KERNEL && !IA64
 643         help
 644           Enables the display of the minimum amount of free stack which each
 645           task has ever had available in the sysrq-T and sysrq-P debug output.
 646
 647           This option will slow down process creation somewhat.
 648
 649 config DEBUG_VM
 650         bool "Debug VM"
 651         depends on DEBUG_KERNEL
 652         help
 653           Enable this to turn on extended checks in the virtual-memory system
 654           that may impact performance.
 655
 656           If unsure, say N.
 657
 658 config DEBUG_VM_VMACACHE
 659         bool "Debug VMA caching"
 660         depends on DEBUG_VM
 661         help
 662           Enable this to turn on VMA caching debug information. Doing so
 663           can cause significant overhead, so only enable it in non-production
 664           environments.
 665
 666           If unsure, say N.
 667
 668 config DEBUG_VM_RB
 669         bool "Debug VM red-black trees"
 670         depends on DEBUG_VM
 671         help
 672           Enable VM red-black tree debugging information and extra validations.
 673
 674           If unsure, say N.
 675
 676 config DEBUG_VM_PGFLAGS
 677         bool "Debug page-flags operations"
 678         depends on DEBUG_VM
 679         help
 680           Enables extra validation on page flags operations.
 681
 682           If unsure, say N.
 683
 684 config ARCH_HAS_DEBUG_VIRTUAL
 685         bool
 686
 687 config DEBUG_VIRTUAL
 688         bool "Debug VM translations"
 689         depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
 690         help
 691           Enable some costly sanity checks in virtual to page code. This can
 692           catch mistakes with virt_to_page() and friends.
 693
 694           If unsure, say N.
 695
 696 config DEBUG_NOMMU_REGIONS
 697         bool "Debug the global anon/private NOMMU mapping region tree"
 698         depends on DEBUG_KERNEL && !MMU
 699         help
 700           This option causes the global tree of anonymous and private mapping
 701           regions to be regularly checked for invalid topology.
 702
 703 config DEBUG_MEMORY_INIT
 704         bool "Debug memory initialisation" if EXPERT
 705         default !EXPERT
 706         help
 707           Enable this for additional checks during memory initialisation.
 708           The sanity checks verify aspects of the VM such as the memory model
 709           and other information provided by the architecture. Verbose
 710           information will be printed at KERN_DEBUG loglevel depending
 711           on the mminit_loglevel= command-line option.
 712
 713           If unsure, say Y
 714
 715 config MEMORY_NOTIFIER_ERROR_INJECT
 716         tristate "Memory hotplug notifier error injection module"
 717         depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
 718         help
 719           This option provides the ability to inject artificial errors to
 720           memory hotplug notifier chain callbacks.  It is controlled through
 721           debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
 722
 723           If the notifier call chain should be failed with some events
 724           notified, write the error code to "actions/<notifier event>/error".
 725
 726           Example: Inject memory hotplug offline error (-12 == -ENOMEM)
 727
 728           # cd /sys/kernel/debug/notifier-error-inject/memory
 729           # echo -12 > actions/MEM_GOING_OFFLINE/error
 730           # echo offline > /sys/devices/system/memory/memoryXXX/state
 731           bash: echo: write error: Cannot allocate memory
 732
 733           To compile this code as a module, choose M here: the module will
 734           be called memory-notifier-error-inject.
 735
 736           If unsure, say N.
 737
 738 config DEBUG_PER_CPU_MAPS
 739         bool "Debug access to per_cpu maps"
 740         depends on DEBUG_KERNEL
 741         depends on SMP
 742         help
 743           Say Y to verify that the per_cpu map being accessed has
 744           been set up. This adds a fair amount of code to kernel memory
 745           and decreases performance.
 746
 747           Say N if unsure.
 748
 749 config DEBUG_HIGHMEM
 750         bool "Highmem debugging"
 751         depends on DEBUG_KERNEL && HIGHMEM
 752         help
 753           This option enables additional error checking for high memory
 754           systems.  Disable for production systems.
 755
 756 config HAVE_DEBUG_STACKOVERFLOW
 757         bool
 758
 759 config DEBUG_STACKOVERFLOW
 760         bool "Check for stack overflows"
 761         depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
 762         ---help---
 763           Say Y here if you want to check for overflows of kernel, IRQ
 764           and exception stacks (if your architecture uses them). This
 765           option will show detailed messages if free stack space drops
 766           below a certain limit.
 767
 768           These kinds of bugs usually occur when call-chains in the
 769           kernel get too deep, especially when interrupts are
 770           involved.
 771
 772           Use this in cases where you see apparently random memory
 773           corruption, especially if it appears in 'struct thread_info'
 774
 775           If in doubt, say "N".
 776
 777 source "lib/Kconfig.kasan"
 778
 779 endmenu # "Memory Debugging"
 780
 781 config ARCH_HAS_KCOV
 782         bool
 783         help
 784           An architecture should select this when it can successfully
 785           build and run with CONFIG_KCOV. This typically requires
 786           disabling instrumentation for some early boot code.
 787
 788 config CC_HAS_SANCOV_TRACE_PC
 789         def_bool $(cc-option,-fsanitize-coverage=trace-pc)
 790
 791 config KCOV
 792         bool "Code coverage for fuzzing"
 793         depends on ARCH_HAS_KCOV
 794         depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
 795         select DEBUG_FS
 796         select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
 797         help
 798           KCOV exposes kernel code coverage information in a form suitable
 799           for coverage-guided fuzzing (randomized testing).
 800
 801           If RANDOMIZE_BASE is enabled, PC values will not be stable across
 802           different machines and across reboots. If you need stable PC values,
 803           disable RANDOMIZE_BASE.
 804
 805           For more details, see Documentation/dev-tools/kcov.rst.
 806
 807 config KCOV_ENABLE_COMPARISONS
 808         bool "Enable comparison operands collection by KCOV"
 809         depends on KCOV
 810         depends on $(cc-option,-fsanitize-coverage=trace-cmp)
 811         help
 812           KCOV also exposes operands of every comparison in the instrumented
 813           code along with operand sizes and PCs of the comparison instructions.
 814           These operands can be used by fuzzing engines to improve the quality
 815           of fuzzing coverage.
 816
 817 config KCOV_INSTRUMENT_ALL
 818         bool "Instrument all code by default"
 819         depends on KCOV
 820         default y
 821         help
 822           If you are doing generic system call fuzzing (like e.g. syzkaller),
 823           then you will want to instrument the whole kernel and you should
 824           say y here. If you are doing more targeted fuzzing (like e.g.
 825           filesystem fuzzing with AFL) then you will want to enable coverage
 826           for more specific subsets of files, and should say n here.
 827
 828 config DEBUG_SHIRQ
 829         bool "Debug shared IRQ handlers"
 830         depends on DEBUG_KERNEL
 831         help
 832           Enable this to generate a spurious interrupt as soon as a shared
 833           interrupt handler is registered, and just before one is deregistered.
 834           Drivers ought to be able to handle interrupts coming in at those
 835           points; some don't and need to be caught.
 836
 837 menu "Debug Lockups and Hangs"
 838
 839 config LOCKUP_DETECTOR
 840         bool
 841
 842 config SOFTLOCKUP_DETECTOR
 843         bool "Detect Soft Lockups"
 844         depends on DEBUG_KERNEL && !S390
 845         select LOCKUP_DETECTOR
 846         help
 847           Say Y here to enable the kernel to act as a watchdog to detect
 848           soft lockups.
 849
 850           Softlockups are bugs that cause the kernel to loop in kernel
 851           mode for more than 20 seconds, without giving other tasks a
 852           chance to run.  The current stack trace is displayed upon
 853           detection and the system will stay locked up.
 854
 855 config BOOTPARAM_SOFTLOCKUP_PANIC
 856         bool "Panic (Reboot) On Soft Lockups"
 857         depends on SOFTLOCKUP_DETECTOR
 858         help
 859           Say Y here to enable the kernel to panic on "soft lockups",
 860           which are bugs that cause the kernel to loop in kernel
 861           mode for more than 20 seconds (configurable using the watchdog_thresh
 862           sysctl), without giving other tasks a chance to run.
 863
 864           The panic can be used in combination with panic_timeout,
 865           to cause the system to reboot automatically after a
 866           lockup has been detected. This feature is useful for
 867           high-availability systems that have uptime guarantees and
 868           where a lockup must be resolved ASAP.
 869
 870           Say N if unsure.
 871
 872 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
 873         int
 874         depends on SOFTLOCKUP_DETECTOR
 875         range 0 1
 876         default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
 877         default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
 878
 879 config HARDLOCKUP_DETECTOR_PERF
 880         bool
 881         select SOFTLOCKUP_DETECTOR
 882
 883 #
 884 # Enables a timestamp based low pass filter to compensate for perf based
 885 # hard lockup detection which runs too fast due to turbo modes.
 886 #
 887 config HARDLOCKUP_CHECK_TIMESTAMP
 888         bool
 889
 890 #
 891 # arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard
 892 # lockup detector rather than the perf based detector.
 893 #
 894 config HARDLOCKUP_DETECTOR
 895         bool "Detect Hard Lockups"
 896         depends on DEBUG_KERNEL && !S390
 897         depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH
 898         select LOCKUP_DETECTOR
 899         select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF
 900         select HARDLOCKUP_DETECTOR_ARCH if HAVE_HARDLOCKUP_DETECTOR_ARCH
 901         help
 902           Say Y here to enable the kernel to act as a watchdog to detect
 903           hard lockups.
 904
 905           Hardlockups are bugs that cause the CPU to loop in kernel mode
 906           for more than 10 seconds, without letting other interrupts have a
 907           chance to run.  The current stack trace is displayed upon detection
 908           and the system will stay locked up.
 909
 910 config BOOTPARAM_HARDLOCKUP_PANIC
 911         bool "Panic (Reboot) On Hard Lockups"
 912         depends on HARDLOCKUP_DETECTOR
 913         help
 914           Say Y here to enable the kernel to panic on "hard lockups",
 915           which are bugs that cause the kernel to loop in kernel
 916           mode with interrupts disabled for more than 10 seconds (configurable
 917           using the watchdog_thresh sysctl).
 918
 919           Say N if unsure.
 920
 921 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
 922         int
 923         depends on HARDLOCKUP_DETECTOR
 924         range 0 1
 925         default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
 926         default 1 if BOOTPARAM_HARDLOCKUP_PANIC
 927
 928 config DETECT_HUNG_TASK
 929         bool "Detect Hung Tasks"
 930         depends on DEBUG_KERNEL
 931         default SOFTLOCKUP_DETECTOR
 932         help
 933           Say Y here to enable the kernel to detect "hung tasks",
 934           which are bugs that cause the task to be stuck in
 935           uninterruptible "D" state indefinitely.
 936
 937           When a hung task is detected, the kernel will print the
 938           current stack trace (which you should report), but the
 939           task will stay in uninterruptible state. If lockdep is
 940           enabled then all held locks will also be reported. This
 941           feature has negligible overhead.
 942
 943 config DEFAULT_HUNG_TASK_TIMEOUT
 944         int "Default timeout for hung task detection (in seconds)"
 945         depends on DETECT_HUNG_TASK
 946         default 120
 947         help
 948           This option controls the default timeout (in seconds) used
 949           to determine when a task has become non-responsive and should
 950           be considered hung.
 951
 952           It can be adjusted at runtime via the kernel.hung_task_timeout_secs
 953           sysctl or by writing a value to
 954           /proc/sys/kernel/hung_task_timeout_secs.
 955
 956           A timeout of 0 disables the check.  The default is two minutes.
 957           Keeping the default should be fine in most cases.
 958
 959 config BOOTPARAM_HUNG_TASK_PANIC
 960         bool "Panic (Reboot) On Hung Tasks"
 961         depends on DETECT_HUNG_TASK
 962         help
 963           Say Y here to enable the kernel to panic on "hung tasks",
 964           which are bugs that cause the kernel to leave a task stuck
 965           in uninterruptible "D" state.
 966
 967           The panic can be used in combination with panic_timeout,
 968           to cause the system to reboot automatically after a
 969           hung task has been detected. This feature is useful for
 970           high-availability systems that have uptime guarantees and
 971           where a hung tasks must be resolved ASAP.
 972
 973           Say N if unsure.
 974
 975 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
 976         int
 977         depends on DETECT_HUNG_TASK
 978         range 0 1
 979         default 0 if !BOOTPARAM_HUNG_TASK_PANIC
 980         default 1 if BOOTPARAM_HUNG_TASK_PANIC
 981
 982 config WQ_WATCHDOG
 983         bool "Detect Workqueue Stalls"
 984         depends on DEBUG_KERNEL
 985         help
 986           Say Y here to enable stall detection on workqueues.  If a
 987           worker pool doesn't make forward progress on a pending work
 988           item for over a given amount of time, 30s by default, a
 989           warning message is printed along with dump of workqueue
 990           state.  This can be configured through kernel parameter
 991           "workqueue.watchdog_thresh" and its sysfs counterpart.
 992
 993 endmenu # "Debug lockups and hangs"
 994
 995 config PANIC_ON_OOPS
 996         bool "Panic on Oops"
 997         help
 998           Say Y here to enable the kernel to panic when it oopses. This
 999           has the same effect as setting oops=panic on the kernel command
1000           line.
1001
1002           This feature is useful to ensure that the kernel does not do
1003           anything erroneous after an oops which could result in data
1004           corruption or other issues.
1005
1006           Say N if unsure.
1007
1008 config PANIC_ON_OOPS_VALUE
1009         int
1010         range 0 1
1011         default 0 if !PANIC_ON_OOPS
1012         default 1 if PANIC_ON_OOPS
1013
1014 config PANIC_TIMEOUT
1015         int "panic timeout"
1016         default 0
1017         help
1018           Set the timeout value (in seconds) until a reboot occurs when the
1019           the kernel panics. If n = 0, then we wait forever. A timeout
1020           value n > 0 will wait n seconds before rebooting, while a timeout
1021           value n < 0 will reboot immediately.
1022
1023 config SCHED_DEBUG
1024         bool "Collect scheduler debugging info"
1025         depends on DEBUG_KERNEL && PROC_FS
1026         default y
1027         help
1028           If you say Y here, the /proc/sched_debug file will be provided
1029           that can help debug the scheduler. The runtime overhead of this
1030           option is minimal.
1031
1032 config SCHED_INFO
1033         bool
1034         default n
1035
1036 config SCHEDSTATS
1037         bool "Collect scheduler statistics"
1038         depends on DEBUG_KERNEL && PROC_FS
1039         select SCHED_INFO
1040         help
1041           If you say Y here, additional code will be inserted into the
1042           scheduler and related routines to collect statistics about
1043           scheduler behavior and provide them in /proc/schedstat.  These
1044           stats may be useful for both tuning and debugging the scheduler
1045           If you aren't debugging the scheduler or trying to tune a specific
1046           application, you can say N to avoid the very slight overhead
1047           this adds.
1048
1049 config SCHED_STACK_END_CHECK
1050         bool "Detect stack corruption on calls to schedule()"
1051         depends on DEBUG_KERNEL
1052         default n
1053         help
1054           This option checks for a stack overrun on calls to schedule().
1055           If the stack end location is found to be over written always panic as
1056           the content of the corrupted region can no longer be trusted.
1057           This is to ensure no erroneous behaviour occurs which could result in
1058           data corruption or a sporadic crash at a later stage once the region
1059           is examined. The runtime overhead introduced is minimal.
1060
1061 config DEBUG_TIMEKEEPING
1062         bool "Enable extra timekeeping sanity checking"
1063         help
1064           This option will enable additional timekeeping sanity checks
1065           which may be helpful when diagnosing issues where timekeeping
1066           problems are suspected.
1067
1068           This may include checks in the timekeeping hotpaths, so this
1069           option may have a (very small) performance impact to some
1070           workloads.
1071
1072           If unsure, say N.
1073
1074 config DEBUG_PREEMPT
1075         bool "Debug preemptible kernel"
1076         depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
1077         default y
1078         help
1079           If you say Y here then the kernel will use a debug variant of the
1080           commonly used smp_processor_id() function and will print warnings
1081           if kernel code uses it in a preemption-unsafe way. Also, the kernel
1082           will detect preemption count underflows.
1083
1084 menu "Lock Debugging (spinlocks, mutexes, etc...)"
1085
1086 config LOCK_DEBUGGING_SUPPORT
1087         bool
1088         depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1089         default y
1090
1091 config PROVE_LOCKING
1092         bool "Lock debugging: prove locking correctness"
1093         depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1094         select LOCKDEP
1095         select DEBUG_SPINLOCK
1096         select DEBUG_MUTEXES
1097         select DEBUG_RT_MUTEXES if RT_MUTEXES
1098         select DEBUG_RWSEMS if RWSEM_SPIN_ON_OWNER
1099         select DEBUG_WW_MUTEX_SLOWPATH
1100         select DEBUG_LOCK_ALLOC
1101         select TRACE_IRQFLAGS
1102         default n
1103         help
1104          This feature enables the kernel to prove that all locking
1105          that occurs in the kernel runtime is mathematically
1106          correct: that under no circumstance could an arbitrary (and
1107          not yet triggered) combination of observed locking
1108          sequences (on an arbitrary number of CPUs, running an
1109          arbitrary number of tasks and interrupt contexts) cause a
1110          deadlock.
1111
1112          In short, this feature enables the kernel to report locking
1113          related deadlocks before they actually occur.
1114
1115          The proof does not depend on how hard and complex a
1116          deadlock scenario would be to trigger: how many
1117          participant CPUs, tasks and irq-contexts would be needed
1118          for it to trigger. The proof also does not depend on
1119          timing: if a race and a resulting deadlock is possible
1120          theoretically (no matter how unlikely the race scenario
1121          is), it will be proven so and will immediately be
1122          reported by the kernel (once the event is observed that
1123          makes the deadlock theoretically possible).
1124
1125          If a deadlock is impossible (i.e. the locking rules, as
1126          observed by the kernel, are mathematically correct), the
1127          kernel reports nothing.
1128
1129          NOTE: this feature can also be enabled for rwlocks, mutexes
1130          and rwsems - in which case all dependencies between these
1131          different locking variants are observed and mapped too, and
1132          the proof of observed correctness is also maintained for an
1133          arbitrary combination of these separate locking variants.
1134
1135          For more details, see Documentation/locking/lockdep-design.txt.
1136
1137 config LOCK_STAT
1138         bool "Lock usage statistics"
1139         depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1140         select LOCKDEP
1141         select DEBUG_SPINLOCK
1142         select DEBUG_MUTEXES
1143         select DEBUG_RT_MUTEXES if RT_MUTEXES
1144         select DEBUG_LOCK_ALLOC
1145         default n
1146         help
1147          This feature enables tracking lock contention points
1148
1149          For more details, see Documentation/locking/lockstat.txt
1150
1151          This also enables lock events required by "perf lock",
1152          subcommand of perf.
1153          If you want to use "perf lock", you also need to turn on
1154          CONFIG_EVENT_TRACING.
1155
1156          CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1157          (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1158
1159 config DEBUG_RT_MUTEXES
1160         bool "RT Mutex debugging, deadlock detection"
1161         depends on DEBUG_KERNEL && RT_MUTEXES
1162         help
1163          This allows rt mutex semantics violations and rt mutex related
1164          deadlocks (lockups) to be detected and reported automatically.
1165
1166 config DEBUG_SPINLOCK
1167         bool "Spinlock and rw-lock debugging: basic checks"
1168         depends on DEBUG_KERNEL
1169         select UNINLINE_SPIN_UNLOCK
1170         help
1171           Say Y here and build SMP to catch missing spinlock initialization
1172           and certain other kinds of spinlock errors commonly made.  This is
1173           best used in conjunction with the NMI watchdog so that spinlock
1174           deadlocks are also debuggable.
1175
1176 config DEBUG_MUTEXES
1177         bool "Mutex debugging: basic checks"
1178         depends on DEBUG_KERNEL
1179         help
1180          This feature allows mutex semantics violations to be detected and
1181          reported.
1182
1183 config DEBUG_WW_MUTEX_SLOWPATH
1184         bool "Wait/wound mutex debugging: Slowpath testing"
1185         depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1186         select DEBUG_LOCK_ALLOC
1187         select DEBUG_SPINLOCK
1188         select DEBUG_MUTEXES
1189         help
1190          This feature enables slowpath testing for w/w mutex users by
1191          injecting additional -EDEADLK wound/backoff cases. Together with
1192          the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1193          will test all possible w/w mutex interface abuse with the
1194          exception of simply not acquiring all the required locks.
1195          Note that this feature can introduce significant overhead, so
1196          it really should not be enabled in a production or distro kernel,
1197          even a debug kernel.  If you are a driver writer, enable it.  If
1198          you are a distro, do not.
1199
1200 config DEBUG_RWSEMS
1201         bool "RW Semaphore debugging: basic checks"
1202         depends on DEBUG_KERNEL && RWSEM_SPIN_ON_OWNER
1203         help
1204           This debugging feature allows mismatched rw semaphore locks and unlocks
1205           to be detected and reported.
1206
1207 config DEBUG_LOCK_ALLOC
1208         bool "Lock debugging: detect incorrect freeing of live locks"
1209         depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1210         select DEBUG_SPINLOCK
1211         select DEBUG_MUTEXES
1212         select DEBUG_RT_MUTEXES if RT_MUTEXES
1213         select LOCKDEP
1214         help
1215          This feature will check whether any held lock (spinlock, rwlock,
1216          mutex or rwsem) is incorrectly freed by the kernel, via any of the
1217          memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1218          vfree(), etc.), whether a live lock is incorrectly reinitialized via
1219          spin_lock_init()/mutex_init()/etc., or whether there is any lock
1220          held during task exit.
1221
1222 config LOCKDEP
1223         bool
1224         depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1225         select STACKTRACE
1226         select FRAME_POINTER if !MIPS && !PPC && !ARM && !S390 && !MICROBLAZE && !ARC && !X86
1227         select KALLSYMS
1228         select KALLSYMS_ALL
1229
1230 config LOCKDEP_SMALL
1231         bool
1232
1233 config DEBUG_LOCKDEP
1234         bool "Lock dependency engine debugging"
1235         depends on DEBUG_KERNEL && LOCKDEP
1236         help
1237           If you say Y here, the lock dependency engine will do
1238           additional runtime checks to debug itself, at the price
1239           of more runtime overhead.
1240
1241 config DEBUG_ATOMIC_SLEEP
1242         bool "Sleep inside atomic section checking"
1243         select PREEMPT_COUNT
1244         depends on DEBUG_KERNEL
1245         depends on !ARCH_NO_PREEMPT
1246         help
1247           If you say Y here, various routines which may sleep will become very
1248           noisy if they are called inside atomic sections: when a spinlock is
1249           held, inside an rcu read side critical section, inside preempt disabled
1250           sections, inside an interrupt, etc...
1251
1252 config DEBUG_LOCKING_API_SELFTESTS
1253         bool "Locking API boot-time self-tests"
1254         depends on DEBUG_KERNEL
1255         help
1256           Say Y here if you want the kernel to run a short self-test during
1257           bootup. The self-test checks whether common types of locking bugs
1258           are detected by debugging mechanisms or not. (if you disable
1259           lock debugging then those bugs wont be detected of course.)
1260           The following locking APIs are covered: spinlocks, rwlocks,
1261           mutexes and rwsems.
1262
1263 config LOCK_TORTURE_TEST
1264         tristate "torture tests for locking"
1265         depends on DEBUG_KERNEL
1266         select TORTURE_TEST
1267         help
1268           This option provides a kernel module that runs torture tests
1269           on kernel locking primitives.  The kernel module may be built
1270           after the fact on the running kernel to be tested, if desired.
1271
1272           Say Y here if you want kernel locking-primitive torture tests
1273           to be built into the kernel.
1274           Say M if you want these torture tests to build as a module.
1275           Say N if you are unsure.
1276
1277 config WW_MUTEX_SELFTEST
1278         tristate "Wait/wound mutex selftests"
1279         help
1280           This option provides a kernel module that runs tests on the
1281           on the struct ww_mutex locking API.
1282
1283           It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1284           with this test harness.
1285
1286           Say M if you want these self tests to build as a module.
1287           Say N if you are unsure.
1288
1289 endmenu # lock debugging
1290
1291 config TRACE_IRQFLAGS
1292         bool
1293         help
1294           Enables hooks to interrupt enabling and disabling for
1295           either tracing or lock debugging.
1296
1297 config STACKTRACE
1298         bool "Stack backtrace support"
1299         depends on STACKTRACE_SUPPORT
1300         help
1301           This option causes the kernel to create a /proc/pid/stack for
1302           every process, showing its current stack trace.
1303           It is also used by various kernel debugging features that require
1304           stack trace generation.
1305
1306 config WARN_ALL_UNSEEDED_RANDOM
1307         bool "Warn for all uses of unseeded randomness"
1308         default n
1309         help
1310           Some parts of the kernel contain bugs relating to their use of
1311           cryptographically secure random numbers before it's actually possible
1312           to generate those numbers securely. This setting ensures that these
1313           flaws don't go unnoticed, by enabling a message, should this ever
1314           occur. This will allow people with obscure setups to know when things
1315           are going wrong, so that they might contact developers about fixing
1316           it.
1317
1318           Unfortunately, on some models of some architectures getting
1319           a fully seeded CRNG is extremely difficult, and so this can
1320           result in dmesg getting spammed for a surprisingly long
1321           time.  This is really bad from a security perspective, and
1322           so architecture maintainers really need to do what they can
1323           to get the CRNG seeded sooner after the system is booted.
1324           However, since users cannot do anything actionable to
1325           address this, by default the kernel will issue only a single
1326           warning for the first use of unseeded randomness.
1327
1328           Say Y here if you want to receive warnings for all uses of
1329           unseeded randomness.  This will be of use primarily for
1330           those developers interested in improving the security of
1331           Linux kernels running on their architecture (or
1332           subarchitecture).
1333
1334 config DEBUG_KOBJECT
1335         bool "kobject debugging"
1336         depends on DEBUG_KERNEL
1337         help
1338           If you say Y here, some extra kobject debugging messages will be sent
1339           to the syslog.
1340
1341 config DEBUG_KOBJECT_RELEASE
1342         bool "kobject release debugging"
1343         depends on DEBUG_OBJECTS_TIMERS
1344         help
1345           kobjects are reference counted objects.  This means that their
1346           last reference count put is not predictable, and the kobject can
1347           live on past the point at which a driver decides to drop it's
1348           initial reference to the kobject gained on allocation.  An
1349           example of this would be a struct device which has just been
1350           unregistered.
1351
1352           However, some buggy drivers assume that after such an operation,
1353           the memory backing the kobject can be immediately freed.  This
1354           goes completely against the principles of a refcounted object.
1355
1356           If you say Y here, the kernel will delay the release of kobjects
1357           on the last reference count to improve the visibility of this
1358           kind of kobject release bug.
1359
1360 config HAVE_DEBUG_BUGVERBOSE
1361         bool
1362
1363 config DEBUG_BUGVERBOSE
1364         bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
1365         depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
1366         default y
1367         help
1368           Say Y here to make BUG() panics output the file name and line number
1369           of the BUG call as well as the EIP and oops trace.  This aids
1370           debugging but costs about 70-100K of memory.
1371
1372 config DEBUG_LIST
1373         bool "Debug linked list manipulation"
1374         depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION
1375         help
1376           Enable this to turn on extended checks in the linked-list
1377           walking routines.
1378
1379           If unsure, say N.
1380
1381 config DEBUG_PLIST
1382         bool "Debug priority linked list manipulation"
1383         depends on DEBUG_KERNEL
1384         help
1385           Enable this to turn on extended checks in the priority-ordered
1386           linked-list (plist) walking routines.  This checks the entire
1387           list multiple times during each manipulation.
1388
1389           If unsure, say N.
1390
1391 config DEBUG_SG
1392         bool "Debug SG table operations"
1393         depends on DEBUG_KERNEL
1394         help
1395           Enable this to turn on checks on scatter-gather tables. This can
1396           help find problems with drivers that do not properly initialize
1397           their sg tables.
1398
1399           If unsure, say N.
1400
1401 config DEBUG_NOTIFIERS
1402         bool "Debug notifier call chains"
1403         depends on DEBUG_KERNEL
1404         help
1405           Enable this to turn on sanity checking for notifier call chains.
1406           This is most useful for kernel developers to make sure that
1407           modules properly unregister themselves from notifier chains.
1408           This is a relatively cheap check but if you care about maximum
1409           performance, say N.
1410
1411 config DEBUG_CREDENTIALS
1412         bool "Debug credential management"
1413         depends on DEBUG_KERNEL
1414         help
1415           Enable this to turn on some debug checking for credential
1416           management.  The additional code keeps track of the number of
1417           pointers from task_structs to any given cred struct, and checks to
1418           see that this number never exceeds the usage count of the cred
1419           struct.
1420
1421           Furthermore, if SELinux is enabled, this also checks that the
1422           security pointer in the cred struct is never seen to be invalid.
1423
1424           If unsure, say N.
1425
1426 source "kernel/rcu/Kconfig.debug"
1427
1428 config DEBUG_WQ_FORCE_RR_CPU
1429         bool "Force round-robin CPU selection for unbound work items"
1430         depends on DEBUG_KERNEL
1431         default n
1432         help
1433           Workqueue used to implicitly guarantee that work items queued
1434           without explicit CPU specified are put on the local CPU.  This
1435           guarantee is no longer true and while local CPU is still
1436           preferred work items may be put on foreign CPUs.  Kernel
1437           parameter "workqueue.debug_force_rr_cpu" is added to force
1438           round-robin CPU selection to flush out usages which depend on the
1439           now broken guarantee.  This config option enables the debug
1440           feature by default.  When enabled, memory and cache locality will
1441           be impacted.
1442
1443 config DEBUG_BLOCK_EXT_DEVT
1444         bool "Force extended block device numbers and spread them"
1445         depends on DEBUG_KERNEL
1446         depends on BLOCK
1447         default n
1448         help
1449           BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1450           SOME DISTRIBUTIONS.  DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1451           YOU ARE DOING.  Distros, please enable this and fix whatever
1452           is broken.
1453
1454           Conventionally, block device numbers are allocated from
1455           predetermined contiguous area.  However, extended block area
1456           may introduce non-contiguous block device numbers.  This
1457           option forces most block device numbers to be allocated from
1458           the extended space and spreads them to discover kernel or
1459           userland code paths which assume predetermined contiguous
1460           device number allocation.
1461
1462           Note that turning on this debug option shuffles all the
1463           device numbers for all IDE and SCSI devices including libata
1464           ones, so root partition specified using device number
1465           directly (via rdev or root=MAJ:MIN) won't work anymore.
1466           Textual device names (root=/dev/sdXn) will continue to work.
1467
1468           Say N if you are unsure.
1469
1470 config CPU_HOTPLUG_STATE_CONTROL
1471         bool "Enable CPU hotplug state control"
1472         depends on DEBUG_KERNEL
1473         depends on HOTPLUG_CPU
1474         default n
1475         help
1476           Allows to write steps between "offline" and "online" to the CPUs
1477           sysfs target file so states can be stepped granular. This is a debug
1478           option for now as the hotplug machinery cannot be stopped and
1479           restarted at arbitrary points yet.
1480
1481           Say N if your are unsure.
1482
1483 config NOTIFIER_ERROR_INJECTION
1484         tristate "Notifier error injection"
1485         depends on DEBUG_KERNEL
1486         select DEBUG_FS
1487         help
1488           This option provides the ability to inject artificial errors to
1489           specified notifier chain callbacks. It is useful to test the error
1490           handling of notifier call chain failures.
1491
1492           Say N if unsure.
1493
1494 config PM_NOTIFIER_ERROR_INJECT
1495         tristate "PM notifier error injection module"
1496         depends on PM && NOTIFIER_ERROR_INJECTION
1497         default m if PM_DEBUG
1498         help
1499           This option provides the ability to inject artificial errors to
1500           PM notifier chain callbacks.  It is controlled through debugfs
1501           interface /sys/kernel/debug/notifier-error-inject/pm
1502
1503           If the notifier call chain should be failed with some events
1504           notified, write the error code to "actions/<notifier event>/error".
1505
1506           Example: Inject PM suspend error (-12 = -ENOMEM)
1507
1508           # cd /sys/kernel/debug/notifier-error-inject/pm/
1509           # echo -12 > actions/PM_SUSPEND_PREPARE/error
1510           # echo mem > /sys/power/state
1511           bash: echo: write error: Cannot allocate memory
1512
1513           To compile this code as a module, choose M here: the module will
1514           be called pm-notifier-error-inject.
1515
1516           If unsure, say N.
1517
1518 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1519         tristate "OF reconfig notifier error injection module"
1520         depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1521         help
1522           This option provides the ability to inject artificial errors to
1523           OF reconfig notifier chain callbacks.  It is controlled
1524           through debugfs interface under
1525           /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1526
1527           If the notifier call chain should be failed with some events
1528           notified, write the error code to "actions/<notifier event>/error".
1529
1530           To compile this code as a module, choose M here: the module will
1531           be called of-reconfig-notifier-error-inject.
1532
1533           If unsure, say N.
1534
1535 config NETDEV_NOTIFIER_ERROR_INJECT
1536         tristate "Netdev notifier error injection module"
1537         depends on NET && NOTIFIER_ERROR_INJECTION
1538         help
1539           This option provides the ability to inject artificial errors to
1540           netdevice notifier chain callbacks.  It is controlled through debugfs
1541           interface /sys/kernel/debug/notifier-error-inject/netdev
1542
1543           If the notifier call chain should be failed with some events
1544           notified, write the error code to "actions/<notifier event>/error".
1545
1546           Example: Inject netdevice mtu change error (-22 = -EINVAL)
1547
1548           # cd /sys/kernel/debug/notifier-error-inject/netdev
1549           # echo -22 > actions/NETDEV_CHANGEMTU/error
1550           # ip link set eth0 mtu 1024
1551           RTNETLINK answers: Invalid argument
1552
1553           To compile this code as a module, choose M here: the module will
1554           be called netdev-notifier-error-inject.
1555
1556           If unsure, say N.
1557
1558 config FUNCTION_ERROR_INJECTION
1559         def_bool y
1560         depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
1561
1562 config FAULT_INJECTION
1563         bool "Fault-injection framework"
1564         depends on DEBUG_KERNEL
1565         help
1566           Provide fault-injection framework.
1567           For more details, see Documentation/fault-injection/.
1568
1569 config FAILSLAB
1570         bool "Fault-injection capability for kmalloc"
1571         depends on FAULT_INJECTION
1572         depends on SLAB || SLUB
1573         help
1574           Provide fault-injection capability for kmalloc.
1575
1576 config FAIL_PAGE_ALLOC
1577         bool "Fault-injection capabilitiy for alloc_pages()"
1578         depends on FAULT_INJECTION
1579         help
1580           Provide fault-injection capability for alloc_pages().
1581
1582 config FAIL_MAKE_REQUEST
1583         bool "Fault-injection capability for disk IO"
1584         depends on FAULT_INJECTION && BLOCK
1585         help
1586           Provide fault-injection capability for disk IO.
1587
1588 config FAIL_IO_TIMEOUT
1589         bool "Fault-injection capability for faking disk interrupts"
1590         depends on FAULT_INJECTION && BLOCK
1591         help
1592           Provide fault-injection capability on end IO handling. This
1593           will make the block layer "forget" an interrupt as configured,
1594           thus exercising the error handling.
1595
1596           Only works with drivers that use the generic timeout handling,
1597           for others it wont do anything.
1598
1599 config FAIL_FUTEX
1600         bool "Fault-injection capability for futexes"
1601         select DEBUG_FS
1602         depends on FAULT_INJECTION && FUTEX
1603         help
1604           Provide fault-injection capability for futexes.
1605
1606 config FAULT_INJECTION_DEBUG_FS
1607         bool "Debugfs entries for fault-injection capabilities"
1608         depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1609         help
1610           Enable configuration of fault-injection capabilities via debugfs.
1611
1612 config FAIL_FUNCTION
1613         bool "Fault-injection capability for functions"
1614         depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
1615         help
1616           Provide function-based fault-injection capability.
1617           This will allow you to override a specific function with a return
1618           with given return value. As a result, function caller will see
1619           an error value and have to handle it. This is useful to test the
1620           error handling in various subsystems.
1621
1622 config FAIL_MMC_REQUEST
1623         bool "Fault-injection capability for MMC IO"
1624         depends on FAULT_INJECTION_DEBUG_FS && MMC
1625         help
1626           Provide fault-injection capability for MMC IO.
1627           This will make the mmc core return data errors. This is
1628           useful to test the error handling in the mmc block device
1629           and to test how the mmc host driver handles retries from
1630           the block device.
1631
1632 config FAULT_INJECTION_STACKTRACE_FILTER
1633         bool "stacktrace filter for fault-injection capabilities"
1634         depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1635         depends on !X86_64
1636         select STACKTRACE
1637         select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86
1638         help
1639           Provide stacktrace filter for fault-injection capabilities
1640
1641 config LATENCYTOP
1642         bool "Latency measuring infrastructure"
1643         depends on DEBUG_KERNEL
1644         depends on STACKTRACE_SUPPORT
1645         depends on PROC_FS
1646         select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86
1647         select KALLSYMS
1648         select KALLSYMS_ALL
1649         select STACKTRACE
1650         select SCHEDSTATS
1651         select SCHED_DEBUG
1652         help
1653           Enable this option if you want to use the LatencyTOP tool
1654           to find out which userspace is blocking on what kernel operations.
1655
1656 source "kernel/trace/Kconfig"
1657
1658 config PROVIDE_OHCI1394_DMA_INIT
1659         bool "Remote debugging over FireWire early on boot"
1660         depends on PCI && X86
1661         help
1662           If you want to debug problems which hang or crash the kernel early
1663           on boot and the crashing machine has a FireWire port, you can use
1664           this feature to remotely access the memory of the crashed machine
1665           over FireWire. This employs remote DMA as part of the OHCI1394
1666           specification which is now the standard for FireWire controllers.
1667
1668           With remote DMA, you can monitor the printk buffer remotely using
1669           firescope and access all memory below 4GB using fireproxy from gdb.
1670           Even controlling a kernel debugger is possible using remote DMA.
1671
1672           Usage:
1673
1674           If ohci1394_dma=early is used as boot parameter, it will initialize
1675           all OHCI1394 controllers which are found in the PCI config space.
1676
1677           As all changes to the FireWire bus such as enabling and disabling
1678           devices cause a bus reset and thereby disable remote DMA for all
1679           devices, be sure to have the cable plugged and FireWire enabled on
1680           the debugging host before booting the debug target for debugging.
1681
1682           This code (~1k) is freed after boot. By then, the firewire stack
1683           in charge of the OHCI-1394 controllers should be used instead.
1684
1685           See Documentation/debugging-via-ohci1394.txt for more information.
1686
1687 menuconfig RUNTIME_TESTING_MENU
1688         bool "Runtime Testing"
1689         def_bool y
1690
1691 if RUNTIME_TESTING_MENU
1692
1693 config LKDTM
1694         tristate "Linux Kernel Dump Test Tool Module"
1695         depends on DEBUG_FS
1696         help
1697         This module enables testing of the different dumping mechanisms by
1698         inducing system failures at predefined crash points.
1699         If you don't need it: say N
1700         Choose M here to compile this code as a module. The module will be
1701         called lkdtm.
1702
1703         Documentation on how to use the module can be found in
1704         Documentation/fault-injection/provoke-crashes.txt
1705
1706 config TEST_LIST_SORT
1707         tristate "Linked list sorting test"
1708         depends on DEBUG_KERNEL || m
1709         help
1710           Enable this to turn on 'list_sort()' function test. This test is
1711           executed only once during system boot (so affects only boot time),
1712           or at module load time.
1713
1714           If unsure, say N.
1715
1716 config TEST_SORT
1717         tristate "Array-based sort test"
1718         depends on DEBUG_KERNEL || m
1719         help
1720           This option enables the self-test function of 'sort()' at boot,
1721           or at module load time.
1722
1723           If unsure, say N.
1724
1725 config KPROBES_SANITY_TEST
1726         bool "Kprobes sanity tests"
1727         depends on DEBUG_KERNEL
1728         depends on KPROBES
1729         help
1730           This option provides for testing basic kprobes functionality on
1731           boot. Samples of kprobe and kretprobe are inserted and
1732           verified for functionality.
1733
1734           Say N if you are unsure.
1735
1736 config BACKTRACE_SELF_TEST
1737         tristate "Self test for the backtrace code"
1738         depends on DEBUG_KERNEL
1739         help
1740           This option provides a kernel module that can be used to test
1741           the kernel stack backtrace code. This option is not useful
1742           for distributions or general kernels, but only for kernel
1743           developers working on architecture code.
1744
1745           Note that if you want to also test saved backtraces, you will
1746           have to enable STACKTRACE as well.
1747
1748           Say N if you are unsure.
1749
1750 config RBTREE_TEST
1751         tristate "Red-Black tree test"
1752         depends on DEBUG_KERNEL
1753         help
1754           A benchmark measuring the performance of the rbtree library.
1755           Also includes rbtree invariant checks.
1756
1757 config INTERVAL_TREE_TEST
1758         tristate "Interval tree test"
1759         depends on DEBUG_KERNEL
1760         select INTERVAL_TREE
1761         help
1762           A benchmark measuring the performance of the interval tree library
1763
1764 config PERCPU_TEST
1765         tristate "Per cpu operations test"
1766         depends on m && DEBUG_KERNEL
1767         help
1768           Enable this option to build test module which validates per-cpu
1769           operations.
1770
1771           If unsure, say N.
1772
1773 config ATOMIC64_SELFTEST
1774         tristate "Perform an atomic64_t self-test"
1775         help
1776           Enable this option to test the atomic64_t functions at boot or
1777           at module load time.
1778
1779           If unsure, say N.
1780
1781 config ASYNC_RAID6_TEST
1782         tristate "Self test for hardware accelerated raid6 recovery"
1783         depends on ASYNC_RAID6_RECOV
1784         select ASYNC_MEMCPY
1785         ---help---
1786           This is a one-shot self test that permutes through the
1787           recovery of all the possible two disk failure scenarios for a
1788           N-disk array.  Recovery is performed with the asynchronous
1789           raid6 recovery routines, and will optionally use an offload
1790           engine if one is available.
1791
1792           If unsure, say N.
1793
1794 config TEST_HEXDUMP
1795         tristate "Test functions located in the hexdump module at runtime"
1796
1797 config TEST_STRING_HELPERS
1798         tristate "Test functions located in the string_helpers module at runtime"
1799
1800 config TEST_STRSCPY
1801         tristate "Test strscpy*() family of functions at runtime"
1802
1803 config TEST_KSTRTOX
1804         tristate "Test kstrto*() family of functions at runtime"
1805
1806 config TEST_PRINTF
1807         tristate "Test printf() family of functions at runtime"
1808
1809 config TEST_BITMAP
1810         tristate "Test bitmap_*() family of functions at runtime"
1811         help
1812           Enable this option to test the bitmap functions at boot.
1813
1814           If unsure, say N.
1815
1816 config TEST_BITFIELD
1817         tristate "Test bitfield functions at runtime"
1818         help
1819           Enable this option to test the bitfield functions at boot.
1820
1821           If unsure, say N.
1822
1823 config TEST_UUID
1824         tristate "Test functions located in the uuid module at runtime"
1825
1826 config TEST_XARRAY
1827         tristate "Test the XArray code at runtime"
1828
1829 config TEST_OVERFLOW
1830         tristate "Test check_*_overflow() functions at runtime"
1831
1832 config TEST_RHASHTABLE
1833         tristate "Perform selftest on resizable hash table"
1834         help
1835           Enable this option to test the rhashtable functions at boot.
1836
1837           If unsure, say N.
1838
1839 config TEST_HASH
1840         tristate "Perform selftest on hash functions"
1841         help
1842           Enable this option to test the kernel's integer (<linux/hash.h>),
1843           string (<linux/stringhash.h>), and siphash (<linux/siphash.h>)
1844           hash functions on boot (or module load).
1845
1846           This is intended to help people writing architecture-specific
1847           optimized versions.  If unsure, say N.
1848
1849 config TEST_IDA
1850         tristate "Perform selftest on IDA functions"
1851
1852 config TEST_PARMAN
1853         tristate "Perform selftest on priority array manager"
1854         depends on PARMAN
1855         help
1856           Enable this option to test priority array manager on boot
1857           (or module load).
1858
1859           If unsure, say N.
1860
1861 config TEST_LKM
1862         tristate "Test module loading with 'hello world' module"
1863         depends on m
1864         help
1865           This builds the "test_module" module that emits "Hello, world"
1866           on printk when loaded. It is designed to be used for basic
1867           evaluation of the module loading subsystem (for example when
1868           validating module verification). It lacks any extra dependencies,
1869           and will not normally be loaded by the system unless explicitly
1870           requested by name.
1871
1872           If unsure, say N.
1873
1874 config TEST_VMALLOC
1875         tristate "Test module for stress/performance analysis of vmalloc allocator"
1876         default n
1877        depends on MMU
1878         depends on m
1879         help
1880           This builds the "test_vmalloc" module that should be used for
1881           stress and performance analysis. So, any new change for vmalloc
1882           subsystem can be evaluated from performance and stability point
1883           of view.
1884
1885           If unsure, say N.
1886
1887 config TEST_USER_COPY
1888         tristate "Test user/kernel boundary protections"
1889         depends on m
1890         help
1891           This builds the "test_user_copy" module that runs sanity checks
1892           on the copy_to/from_user infrastructure, making sure basic
1893           user/kernel boundary testing is working. If it fails to load,
1894           a regression has been detected in the user/kernel memory boundary
1895           protections.
1896
1897           If unsure, say N.
1898
1899 config TEST_BPF
1900         tristate "Test BPF filter functionality"
1901         depends on m && NET
1902         help
1903           This builds the "test_bpf" module that runs various test vectors
1904           against the BPF interpreter or BPF JIT compiler depending on the
1905           current setting. This is in particular useful for BPF JIT compiler
1906           development, but also to run regression tests against changes in
1907           the interpreter code. It also enables test stubs for eBPF maps and
1908           verifier used by user space verifier testsuite.
1909
1910           If unsure, say N.
1911
1912 config FIND_BIT_BENCHMARK
1913         tristate "Test find_bit functions"
1914         help
1915           This builds the "test_find_bit" module that measure find_*_bit()
1916           functions performance.
1917
1918           If unsure, say N.
1919
1920 config TEST_FIRMWARE
1921         tristate "Test firmware loading via userspace interface"
1922         depends on FW_LOADER
1923         help
1924           This builds the "test_firmware" module that creates a userspace
1925           interface for testing firmware loading. This can be used to
1926           control the triggering of firmware loading without needing an
1927           actual firmware-using device. The contents can be rechecked by
1928           userspace.
1929
1930           If unsure, say N.
1931
1932 config TEST_SYSCTL
1933         tristate "sysctl test driver"
1934         depends on PROC_SYSCTL
1935         help
1936           This builds the "test_sysctl" module. This driver enables to test the
1937           proc sysctl interfaces available to drivers safely without affecting
1938           production knobs which might alter system functionality.
1939
1940           If unsure, say N.
1941
1942 config TEST_UDELAY
1943         tristate "udelay test driver"
1944         help
1945           This builds the "udelay_test" module that helps to make sure
1946           that udelay() is working properly.
1947
1948           If unsure, say N.
1949
1950 config TEST_STATIC_KEYS
1951         tristate "Test static keys"
1952         depends on m
1953         help
1954           Test the static key interfaces.
1955
1956           If unsure, say N.
1957
1958 config TEST_KMOD
1959         tristate "kmod stress tester"
1960         depends on m
1961         depends on NETDEVICES && NET_CORE && INET # for TUN
1962         depends on BLOCK
1963         select TEST_LKM
1964         select XFS_FS
1965         select TUN
1966         select BTRFS_FS
1967         help
1968           Test the kernel's module loading mechanism: kmod. kmod implements
1969           support to load modules using the Linux kernel's usermode helper.
1970           This test provides a series of tests against kmod.
1971
1972           Although technically you can either build test_kmod as a module or
1973           into the kernel we disallow building it into the kernel since
1974           it stress tests request_module() and this will very likely cause
1975           some issues by taking over precious threads available from other
1976           module load requests, ultimately this could be fatal.
1977
1978           To run tests run:
1979
1980           tools/testing/selftests/kmod/kmod.sh --help
1981
1982           If unsure, say N.
1983
1984 config TEST_DEBUG_VIRTUAL
1985         tristate "Test CONFIG_DEBUG_VIRTUAL feature"
1986         depends on DEBUG_VIRTUAL
1987         help
1988           Test the kernel's ability to detect incorrect calls to
1989           virt_to_phys() done against the non-linear part of the
1990           kernel's virtual address map.
1991
1992           If unsure, say N.
1993
1994 config TEST_MEMCAT_P
1995         tristate "Test memcat_p() helper function"
1996         help
1997           Test the memcat_p() helper for correctly merging two
1998           pointer arrays together.
1999
2000           If unsure, say N.
2001
2002 config TEST_LIVEPATCH
2003         tristate "Test livepatching"
2004         default n
2005         depends on DYNAMIC_DEBUG
2006         depends on LIVEPATCH
2007         depends on m
2008         help
2009           Test kernel livepatching features for correctness.  The tests will
2010           load test modules that will be livepatched in various scenarios.
2011
2012           To run all the livepatching tests:
2013
2014           make -C tools/testing/selftests TARGETS=livepatch run_tests
2015
2016           Alternatively, individual tests may be invoked:
2017
2018           tools/testing/selftests/livepatch/test-callbacks.sh
2019           tools/testing/selftests/livepatch/test-livepatch.sh
2020           tools/testing/selftests/livepatch/test-shadow-vars.sh
2021
2022           If unsure, say N.
2023
2024 config TEST_OBJAGG
2025         tristate "Perform selftest on object aggreration manager"
2026         default n
2027         depends on OBJAGG
2028         help
2029           Enable this option to test object aggregation manager on boot
2030           (or module load).
2031
2032
2033 config TEST_STACKINIT
2034         tristate "Test level of stack variable initialization"
2035         help
2036           Test if the kernel is zero-initializing stack variables and
2037           padding. Coverage is controlled by compiler flags,
2038           CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2039           or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2040
2041           If unsure, say N.
2042
2043 endif # RUNTIME_TESTING_MENU
2044
2045 config MEMTEST
2046         bool "Memtest"
2047         ---help---
2048           This option adds a kernel parameter 'memtest', which allows memtest
2049           to be set.
2050                 memtest=0, mean disabled; -- default
2051                 memtest=1, mean do 1 test pattern;
2052                 ...
2053                 memtest=17, mean do 17 test patterns.
2054           If you are unsure how to answer this question, answer N.
2055
2056 config BUG_ON_DATA_CORRUPTION
2057         bool "Trigger a BUG when data corruption is detected"
2058         select DEBUG_LIST
2059         help
2060           Select this option if the kernel should BUG when it encounters
2061           data corruption in kernel memory structures when they get checked
2062           for validity.
2063
2064           If unsure, say N.
2065
2066 source "samples/Kconfig"
2067
2068 source "lib/Kconfig.kgdb"
2069
2070 source "lib/Kconfig.ubsan"
2071
2072 config ARCH_HAS_DEVMEM_IS_ALLOWED
2073         bool
2074
2075 config STRICT_DEVMEM
2076         bool "Filter access to /dev/mem"
2077         depends on MMU && DEVMEM
2078         depends on ARCH_HAS_DEVMEM_IS_ALLOWED
2079         default y if PPC || X86 || ARM64
2080         ---help---
2081           If this option is disabled, you allow userspace (root) access to all
2082           of memory, including kernel and userspace memory. Accidental
2083           access to this is obviously disastrous, but specific access can
2084           be used by people debugging the kernel. Note that with PAT support
2085           enabled, even in this case there are restrictions on /dev/mem
2086           use due to the cache aliasing requirements.
2087
2088           If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
2089           file only allows userspace access to PCI space and the BIOS code and
2090           data regions.  This is sufficient for dosemu and X and all common
2091           users of /dev/mem.
2092
2093           If in doubt, say Y.
2094
2095 config IO_STRICT_DEVMEM
2096         bool "Filter I/O access to /dev/mem"
2097         depends on STRICT_DEVMEM
2098         ---help---
2099           If this option is disabled, you allow userspace (root) access to all
2100           io-memory regardless of whether a driver is actively using that
2101           range.  Accidental access to this is obviously disastrous, but
2102           specific access can be used by people debugging kernel drivers.
2103
2104           If this option is switched on, the /dev/mem file only allows
2105           userspace access to *idle* io-memory ranges (see /proc/iomem) This
2106           may break traditional users of /dev/mem (dosemu, legacy X, etc...)
2107           if the driver using a given range cannot be disabled.
2108
2109           If in doubt, say Y.
2110
2111 source "arch/$(SRCARCH)/Kconfig.debug"
2112
2113 endmenu # Kernel hacking