1# SPDX-License-Identifier: GPL-2.0-only 2menu "Kernel hacking" 3 4menu "printk and dmesg options" 5 6config 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 21config 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 38config STACKTRACE_BUILD_ID 39 bool "Show build ID information in stacktraces" 40 depends on PRINTK 41 help 42 Selecting this option adds build ID information for symbols in 43 stacktraces printed with the printk format '%p[SR]b'. 44 45 This option is intended for distros where debuginfo is not easily 46 accessible but can be downloaded given the build ID of the vmlinux or 47 kernel module where the function is located. 48 49config CONSOLE_LOGLEVEL_DEFAULT 50 int "Default console loglevel (1-15)" 51 range 1 15 52 default "7" 53 help 54 Default loglevel to determine what will be printed on the console. 55 56 Setting a default here is equivalent to passing in loglevel=<x> in 57 the kernel bootargs. loglevel=<x> continues to override whatever 58 value is specified here as well. 59 60 Note: This does not affect the log level of un-prefixed printk() 61 usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT 62 option. 63 64config CONSOLE_LOGLEVEL_QUIET 65 int "quiet console loglevel (1-15)" 66 range 1 15 67 default "4" 68 help 69 loglevel to use when "quiet" is passed on the kernel commandline. 70 71 When "quiet" is passed on the kernel commandline this loglevel 72 will be used as the loglevel. IOW passing "quiet" will be the 73 equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>" 74 75config MESSAGE_LOGLEVEL_DEFAULT 76 int "Default message log level (1-7)" 77 range 1 7 78 default "4" 79 help 80 Default log level for printk statements with no specified priority. 81 82 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks 83 that are auditing their logs closely may want to set it to a lower 84 priority. 85 86 Note: This does not affect what message level gets printed on the console 87 by default. To change that, use loglevel=<x> in the kernel bootargs, 88 or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value. 89 90config BOOT_PRINTK_DELAY 91 bool "Delay each boot printk message by N milliseconds" 92 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY 93 help 94 This build option allows you to read kernel boot messages 95 by inserting a short delay after each one. The delay is 96 specified in milliseconds on the kernel command line, 97 using "boot_delay=N". 98 99 It is likely that you would also need to use "lpj=M" to preset 100 the "loops per jiffy" value. 101 See a previous boot log for the "lpj" value to use for your 102 system, and then set "lpj=M" before setting "boot_delay=N". 103 NOTE: Using this option may adversely affect SMP systems. 104 I.e., processors other than the first one may not boot up. 105 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect 106 what it believes to be lockup conditions. 107 108config DYNAMIC_DEBUG 109 bool "Enable dynamic printk() support" 110 default n 111 depends on PRINTK 112 depends on (DEBUG_FS || PROC_FS) 113 select DYNAMIC_DEBUG_CORE 114 help 115 116 Compiles debug level messages into the kernel, which would not 117 otherwise be available at runtime. These messages can then be 118 enabled/disabled based on various levels of scope - per source file, 119 function, module, format string, and line number. This mechanism 120 implicitly compiles in all pr_debug() and dev_dbg() calls, which 121 enlarges the kernel text size by about 2%. 122 123 If a source file is compiled with DEBUG flag set, any 124 pr_debug() calls in it are enabled by default, but can be 125 disabled at runtime as below. Note that DEBUG flag is 126 turned on by many CONFIG_*DEBUG* options. 127 128 Usage: 129 130 Dynamic debugging is controlled via the 'dynamic_debug/control' file, 131 which is contained in the 'debugfs' filesystem or procfs. 132 Thus, the debugfs or procfs filesystem must first be mounted before 133 making use of this feature. 134 We refer the control file as: <debugfs>/dynamic_debug/control. This 135 file contains a list of the debug statements that can be enabled. The 136 format for each line of the file is: 137 138 filename:lineno [module]function flags format 139 140 filename : source file of the debug statement 141 lineno : line number of the debug statement 142 module : module that contains the debug statement 143 function : function that contains the debug statement 144 flags : '=p' means the line is turned 'on' for printing 145 format : the format used for the debug statement 146 147 From a live system: 148 149 nullarbor:~ # cat <debugfs>/dynamic_debug/control 150 # filename:lineno [module]function flags format 151 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012" 152 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012" 153 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012" 154 155 Example usage: 156 157 // enable the message at line 1603 of file svcsock.c 158 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' > 159 <debugfs>/dynamic_debug/control 160 161 // enable all the messages in file svcsock.c 162 nullarbor:~ # echo -n 'file svcsock.c +p' > 163 <debugfs>/dynamic_debug/control 164 165 // enable all the messages in the NFS server module 166 nullarbor:~ # echo -n 'module nfsd +p' > 167 <debugfs>/dynamic_debug/control 168 169 // enable all 12 messages in the function svc_process() 170 nullarbor:~ # echo -n 'func svc_process +p' > 171 <debugfs>/dynamic_debug/control 172 173 // disable all 12 messages in the function svc_process() 174 nullarbor:~ # echo -n 'func svc_process -p' > 175 <debugfs>/dynamic_debug/control 176 177 See Documentation/admin-guide/dynamic-debug-howto.rst for additional 178 information. 179 180config DYNAMIC_DEBUG_CORE 181 bool "Enable core function of dynamic debug support" 182 depends on PRINTK 183 depends on (DEBUG_FS || PROC_FS) 184 help 185 Enable core functional support of dynamic debug. It is useful 186 when you want to tie dynamic debug to your kernel modules with 187 DYNAMIC_DEBUG_MODULE defined for each of them, especially for 188 the case of embedded system where the kernel image size is 189 sensitive for people. 190 191config SYMBOLIC_ERRNAME 192 bool "Support symbolic error names in printf" 193 default y if PRINTK 194 help 195 If you say Y here, the kernel's printf implementation will 196 be able to print symbolic error names such as ENOSPC instead 197 of the number 28. It makes the kernel image slightly larger 198 (about 3KB), but can make the kernel logs easier to read. 199 200config DEBUG_BUGVERBOSE 201 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT 202 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE) 203 default y 204 help 205 Say Y here to make BUG() panics output the file name and line number 206 of the BUG call as well as the EIP and oops trace. This aids 207 debugging but costs about 70-100K of memory. 208 209config DEBUG_BUGVERBOSE_DETAILED 210 bool "Verbose WARN_ON_ONCE() reporting (adds 100K)" if DEBUG_BUGVERBOSE 211 help 212 Say Y here to make WARN_ON_ONCE() output the condition string of the 213 warning, in addition to the file name and line number. 214 This helps debugging, but costs about 100K of memory. 215 216 Say N if unsure. 217 218 219endmenu # "printk and dmesg options" 220 221config DEBUG_KERNEL 222 bool "Kernel debugging" 223 help 224 Say Y here if you are developing drivers or trying to debug and 225 identify kernel problems. 226 227config DEBUG_MISC 228 bool "Miscellaneous debug code" 229 default DEBUG_KERNEL 230 depends on DEBUG_KERNEL 231 help 232 Say Y here if you need to enable miscellaneous debug code that should 233 be under a more specific debug option but isn't. 234 235menu "Compile-time checks and compiler options" 236 237config DEBUG_INFO 238 bool 239 help 240 A kernel debug info option other than "None" has been selected 241 in the "Debug information" choice below, indicating that debug 242 information will be generated for build targets. 243 244# Clang generates .uleb128 with label differences for DWARF v5, a feature that 245# older binutils ports do not support when utilizing RISC-V style linker 246# relaxation: https://sourceware.org/bugzilla/show_bug.cgi?id=27215 247config AS_HAS_NON_CONST_ULEB128 248 def_bool $(as-instr,.uleb128 .Lexpr_end4 - .Lexpr_start3\n.Lexpr_start3:\n.Lexpr_end4:) 249 250choice 251 prompt "Debug information" 252 depends on DEBUG_KERNEL 253 help 254 Selecting something other than "None" results in a kernel image 255 that will include debugging info resulting in a larger kernel image. 256 This adds debug symbols to the kernel and modules (gcc -g), and 257 is needed if you intend to use kernel crashdump or binary object 258 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 259 260 Choose which version of DWARF debug info to emit. If unsure, 261 select "Toolchain default". 262 263config DEBUG_INFO_NONE 264 bool "Disable debug information" 265 help 266 Do not build the kernel with debugging information, which will 267 result in a faster and smaller build. 268 269config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT 270 bool "Rely on the toolchain's implicit default DWARF version" 271 select DEBUG_INFO 272 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128) 273 help 274 The implicit default version of DWARF debug info produced by a 275 toolchain changes over time. 276 277 This can break consumers of the debug info that haven't upgraded to 278 support newer revisions, and prevent testing newer versions, but 279 those should be less common scenarios. 280 281config DEBUG_INFO_DWARF4 282 bool "Generate DWARF Version 4 debuginfo" 283 select DEBUG_INFO 284 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502) 285 help 286 Generate DWARF v4 debug info. This requires gcc 4.5+, binutils 2.35.2 287 if using clang without clang's integrated assembler, and gdb 7.0+. 288 289 If you have consumers of DWARF debug info that are not ready for 290 newer revisions of DWARF, you may wish to choose this or have your 291 config select this. 292 293config DEBUG_INFO_DWARF5 294 bool "Generate DWARF Version 5 debuginfo" 295 select DEBUG_INFO 296 depends on !ARCH_HAS_BROKEN_DWARF5 297 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128) 298 help 299 Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc 300 5.0+ accepts the -gdwarf-5 flag but only had partial support for some 301 draft features until 7.0), and gdb 8.0+. 302 303 Changes to the structure of debug info in Version 5 allow for around 304 15-18% savings in resulting image and debug info section sizes as 305 compared to DWARF Version 4. DWARF Version 5 standardizes previous 306 extensions such as accelerators for symbol indexing and the format 307 for fission (.dwo/.dwp) files. Users may not want to select this 308 config if they rely on tooling that has not yet been updated to 309 support DWARF Version 5. 310 311endchoice # "Debug information" 312 313if DEBUG_INFO 314 315config DEBUG_INFO_REDUCED 316 bool "Reduce debugging information" 317 help 318 If you say Y here gcc is instructed to generate less debugging 319 information for structure types. This means that tools that 320 need full debugging information (like kgdb or systemtap) won't 321 be happy. But if you merely need debugging information to 322 resolve line numbers there is no loss. Advantage is that 323 build directory object sizes shrink dramatically over a full 324 DEBUG_INFO build and compile times are reduced too. 325 Only works with newer gcc versions. 326 327choice 328 prompt "Compressed Debug information" 329 help 330 Compress the resulting debug info. Results in smaller debug info sections, 331 but requires that consumers are able to decompress the results. 332 333 If unsure, choose DEBUG_INFO_COMPRESSED_NONE. 334 335config DEBUG_INFO_COMPRESSED_NONE 336 bool "Don't compress debug information" 337 help 338 Don't compress debug info sections. 339 340config DEBUG_INFO_COMPRESSED_ZLIB 341 bool "Compress debugging information with zlib" 342 depends on $(cc-option,-gz=zlib) 343 depends on $(ld-option,--compress-debug-sections=zlib) 344 help 345 Compress the debug information using zlib. 346 347 Users of dpkg-deb via debian/rules may find an increase in 348 size of their debug .deb packages with this config set, due to the 349 debug info being compressed with zlib, then the object files being 350 recompressed with a different compression scheme. But this is still 351 preferable to setting KDEB_COMPRESS or DPKG_DEB_COMPRESSOR_TYPE to 352 "none" which would be even larger. 353 354config DEBUG_INFO_COMPRESSED_ZSTD 355 bool "Compress debugging information with zstd" 356 depends on $(cc-option,-gz=zstd) 357 depends on $(ld-option,--compress-debug-sections=zstd) 358 help 359 Compress the debug information using zstd. This may provide better 360 compression than zlib, for about the same time costs, but requires newer 361 toolchain support. Requires GCC 13.0+ or Clang 16.0+, binutils 2.40+, and 362 zstd. 363 364endchoice # "Compressed Debug information" 365 366config DEBUG_INFO_SPLIT 367 bool "Produce split debuginfo in .dwo files" 368 depends on $(cc-option,-gsplit-dwarf) 369 # RISC-V linker relaxation + -gsplit-dwarf has issues with LLVM and GCC 370 # prior to 12.x: 371 # https://github.com/llvm/llvm-project/issues/56642 372 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99090 373 depends on !RISCV || GCC_VERSION >= 120000 374 help 375 Generate debug info into separate .dwo files. This significantly 376 reduces the build directory size for builds with DEBUG_INFO, 377 because it stores the information only once on disk in .dwo 378 files instead of multiple times in object files and executables. 379 In addition the debug information is also compressed. 380 381 Requires recent gcc (4.7+) and recent gdb/binutils. 382 Any tool that packages or reads debug information would need 383 to know about the .dwo files and include them. 384 Incompatible with older versions of ccache. 385 386config DEBUG_INFO_BTF 387 bool "Generate BTF type information" 388 depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED 389 depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST 390 depends on BPF_SYSCALL 391 depends on PAHOLE_VERSION >= 122 392 # pahole uses elfutils, which does not have support for Hexagon relocations 393 depends on !HEXAGON 394 help 395 Generate deduplicated BTF type information from DWARF debug info. 396 Turning this on requires pahole v1.22 or later, which will convert 397 DWARF type info into equivalent deduplicated BTF type info. 398 399config PAHOLE_HAS_BTF_TAG 400 def_bool PAHOLE_VERSION >= 123 401 depends on CC_IS_CLANG 402 help 403 Decide whether pahole emits btf_tag attributes (btf_type_tag and 404 btf_decl_tag) or not. Currently only clang compiler implements 405 these attributes, so make the config depend on CC_IS_CLANG. 406 407config PAHOLE_HAS_LANG_EXCLUDE 408 def_bool PAHOLE_VERSION >= 124 409 help 410 Support for the --lang_exclude flag which makes pahole exclude 411 compilation units from the supplied language. Used in Kbuild to 412 omit Rust CUs which are not supported in version 1.24 of pahole, 413 otherwise it would emit malformed kernel and module binaries when 414 using DEBUG_INFO_BTF_MODULES. 415 416config DEBUG_INFO_BTF_MODULES 417 bool "Generate BTF type information for kernel modules" 418 default y 419 depends on DEBUG_INFO_BTF && MODULES 420 help 421 Generate compact split BTF type information for kernel modules. 422 423config MODULE_ALLOW_BTF_MISMATCH 424 bool "Allow loading modules with non-matching BTF type info" 425 depends on DEBUG_INFO_BTF_MODULES 426 help 427 For modules whose split BTF does not match vmlinux, load without 428 BTF rather than refusing to load. The default behavior with 429 module BTF enabled is to reject modules with such mismatches; 430 this option will still load module BTF where possible but ignore 431 it when a mismatch is found. 432 433config GDB_SCRIPTS 434 bool "Provide GDB scripts for kernel debugging" 435 help 436 This creates the required links to GDB helper scripts in the 437 build directory. If you load vmlinux into gdb, the helper 438 scripts will be automatically imported by gdb as well, and 439 additional functions are available to analyze a Linux kernel 440 instance. See Documentation/process/debugging/gdb-kernel-debugging.rst 441 for further details. 442 443endif # DEBUG_INFO 444 445config FRAME_WARN 446 int "Warn for stack frames larger than" 447 range 0 8192 448 default 0 if KMSAN 449 default 2048 if GCC_PLUGIN_LATENT_ENTROPY 450 default 2048 if PARISC 451 default 1536 if (!64BIT && XTENSA) 452 default 1280 if !64BIT 453 default 2048 if 64BIT 454 help 455 Tell the compiler to warn at build time for stack frames larger than this. 456 Setting this too low will cause a lot of warnings. 457 Setting it to 0 disables the warning. 458 459config STRIP_ASM_SYMS 460 bool "Strip assembler-generated symbols during link" 461 default n 462 help 463 Strip internal assembler-generated symbols during a link (symbols 464 that look like '.Lxxx') so they don't pollute the output of 465 get_wchan() and suchlike. 466 467config READABLE_ASM 468 bool "Generate readable assembler code" 469 depends on DEBUG_KERNEL 470 depends on CC_IS_GCC 471 help 472 Disable some compiler optimizations that tend to generate human unreadable 473 assembler output. This may make the kernel slightly slower, but it helps 474 to keep kernel developers who have to stare a lot at assembler listings 475 sane. 476 477config HEADERS_INSTALL 478 bool "Install uapi headers to usr/include" 479 help 480 This option will install uapi headers (headers exported to user-space) 481 into the usr/include directory for use during the kernel build. 482 This is unneeded for building the kernel itself, but needed for some 483 user-space program samples. It is also needed by some features such 484 as uapi header sanity checks. 485 486config DEBUG_SECTION_MISMATCH 487 bool "Enable full Section mismatch analysis" 488 depends on CC_IS_GCC 489 help 490 The section mismatch analysis checks if there are illegal references 491 from one section to another. During linktime or runtime, some 492 sections are dropped; any use of code/data previously in these 493 sections would most likely result in an oops. 494 495 In the code, functions and variables are annotated with __init, 496 __initdata, and so on (see the full list in include/linux/init.h). 497 This directs the toolchain to place code/data in specific sections. 498 499 The section mismatch analysis is always performed after a full 500 kernel build, and enabling this option causes the option 501 -fno-inline-functions-called-once to be added to gcc commands. 502 503 However, when inlining a function annotated with __init in 504 a non-init function, we would lose the section information and thus 505 the analysis would not catch the illegal reference. This option 506 tells gcc to inline less (but it does result in a larger kernel). 507 508config SECTION_MISMATCH_WARN_ONLY 509 bool "Make section mismatch errors non-fatal" 510 default y 511 help 512 If you say N here, the build process will fail if there are any 513 section mismatch, instead of just throwing warnings. 514 515 If unsure, say Y. 516 517config DEBUG_FORCE_FUNCTION_ALIGN_64B 518 bool "Force all function address 64B aligned" 519 depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC || RISCV || S390) 520 select FUNCTION_ALIGNMENT_64B 521 help 522 There are cases that a commit from one domain changes the function 523 address alignment of other domains, and cause magic performance 524 bump (regression or improvement). Enable this option will help to 525 verify if the bump is caused by function alignment changes, while 526 it will slightly increase the kernel size and affect icache usage. 527 528 It is mainly for debug and performance tuning use. 529 530# 531# Select this config option from the architecture Kconfig, if it 532# is preferred to always offer frame pointers as a config 533# option on the architecture (regardless of KERNEL_DEBUG): 534# 535config ARCH_WANT_FRAME_POINTERS 536 bool 537 538config FRAME_POINTER 539 bool "Compile the kernel with frame pointers" 540 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS 541 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 542 help 543 If you say Y here the resulting kernel image will be slightly 544 larger and slower, but it gives very useful debugging information 545 in case of kernel bugs. (precise oopses/stacktraces/warnings) 546 547config OBJTOOL 548 bool 549 550config OBJTOOL_WERROR 551 bool "Upgrade objtool warnings to errors" 552 depends on OBJTOOL && !COMPILE_TEST 553 help 554 Fail the build on objtool warnings. 555 556 Objtool warnings can indicate kernel instability, including boot 557 failures. This option is highly recommended. 558 559 If unsure, say Y. 560 561config STACK_VALIDATION 562 bool "Compile-time stack metadata validation" 563 depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER 564 select OBJTOOL 565 default n 566 help 567 Validate frame pointer rules at compile-time. This helps ensure that 568 runtime stack traces are more reliable. 569 570 For more information, see 571 tools/objtool/Documentation/objtool.txt. 572 573config NOINSTR_VALIDATION 574 bool 575 depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY 576 select OBJTOOL 577 default y 578 579config VMLINUX_MAP 580 bool "Generate vmlinux.map file when linking" 581 depends on EXPERT 582 help 583 Selecting this option will pass "-Map=vmlinux.map" to ld 584 when linking vmlinux. That file can be useful for verifying 585 and debugging magic section games, and for seeing which 586 pieces of code get eliminated with 587 CONFIG_LD_DEAD_CODE_DATA_ELIMINATION. 588 589config BUILTIN_MODULE_RANGES 590 bool "Generate address range information for builtin modules" 591 depends on !LTO 592 depends on VMLINUX_MAP 593 help 594 When modules are built into the kernel, there will be no module name 595 associated with its symbols in /proc/kallsyms. Tracers may want to 596 identify symbols by module name and symbol name regardless of whether 597 the module is configured as loadable or not. 598 599 This option generates modules.builtin.ranges in the build tree with 600 offset ranges (per ELF section) for the module(s) they belong to. 601 It also records an anchor symbol to determine the load address of the 602 section. 603 604config DEBUG_FORCE_WEAK_PER_CPU 605 bool "Force weak per-cpu definitions" 606 depends on DEBUG_KERNEL 607 help 608 s390 and alpha require percpu variables in modules to be 609 defined weak to work around addressing range issue which 610 puts the following two restrictions on percpu variable 611 definitions. 612 613 1. percpu symbols must be unique whether static or not 614 2. percpu variables can't be defined inside a function 615 616 To ensure that generic code follows the above rules, this 617 option forces all percpu variables to be defined as weak. 618 619endmenu # "Compiler options" 620 621menu "Generic Kernel Debugging Instruments" 622 623config MAGIC_SYSRQ 624 bool "Magic SysRq key" 625 depends on !UML 626 help 627 If you say Y here, you will have some control over the system even 628 if the system crashes for example during kernel debugging (e.g., you 629 will be able to flush the buffer cache to disk, reboot the system 630 immediately or dump some status information). This is accomplished 631 by pressing various keys while holding SysRq (Alt+PrintScreen). It 632 also works on a serial console (on PC hardware at least), if you 633 send a BREAK and then within 5 seconds a command keypress. The 634 keys are documented in <file:Documentation/admin-guide/sysrq.rst>. 635 Don't say Y unless you really know what this hack does. 636 637config MAGIC_SYSRQ_DEFAULT_ENABLE 638 hex "Enable magic SysRq key functions by default" 639 depends on MAGIC_SYSRQ 640 default 0x1 641 help 642 Specifies which SysRq key functions are enabled by default. 643 This may be set to 1 or 0 to enable or disable them all, or 644 to a bitmask as described in Documentation/admin-guide/sysrq.rst. 645 646config MAGIC_SYSRQ_SERIAL 647 bool "Enable magic SysRq key over serial" 648 depends on MAGIC_SYSRQ 649 default y 650 help 651 Many embedded boards have a disconnected TTL level serial which can 652 generate some garbage that can lead to spurious false sysrq detects. 653 This option allows you to decide whether you want to enable the 654 magic SysRq key. 655 656config MAGIC_SYSRQ_SERIAL_SEQUENCE 657 string "Char sequence that enables magic SysRq over serial" 658 depends on MAGIC_SYSRQ_SERIAL 659 default "" 660 help 661 Specifies a sequence of characters that can follow BREAK to enable 662 SysRq on a serial console. 663 664 If unsure, leave an empty string and the option will not be enabled. 665 666config DEBUG_FS 667 bool "Debug Filesystem" 668 help 669 debugfs is a virtual file system that kernel developers use to put 670 debugging files into. Enable this option to be able to read and 671 write to these files. 672 673 For detailed documentation on the debugfs API, see 674 Documentation/filesystems/. 675 676 If unsure, say N. 677 678choice 679 prompt "Debugfs default access" 680 depends on DEBUG_FS 681 default DEBUG_FS_ALLOW_ALL 682 help 683 This selects the default access restrictions for debugfs. 684 It can be overridden with kernel command line option 685 debugfs=[on,off]. The restrictions apply for API access 686 and filesystem registration. 687 688config DEBUG_FS_ALLOW_ALL 689 bool "Access normal" 690 help 691 No restrictions apply. Both API and filesystem registration 692 is on. This is the normal default operation. 693 694config DEBUG_FS_ALLOW_NONE 695 bool "No access" 696 help 697 Access is off. Clients get -PERM when trying to create nodes in 698 debugfs tree and debugfs is not registered as a filesystem. 699 Client can then back-off or continue without debugfs access. 700 701endchoice 702 703source "lib/Kconfig.kgdb" 704source "lib/Kconfig.ubsan" 705source "lib/Kconfig.kcsan" 706 707endmenu 708 709menu "Networking Debugging" 710 711source "net/Kconfig.debug" 712 713endmenu # "Networking Debugging" 714 715menu "Memory Debugging" 716 717source "mm/Kconfig.debug" 718 719config DEBUG_OBJECTS 720 bool "Debug object operations" 721 depends on DEBUG_KERNEL 722 help 723 If you say Y here, additional code will be inserted into the 724 kernel to track the life time of various objects and validate 725 the operations on those objects. 726 727config DEBUG_OBJECTS_SELFTEST 728 bool "Debug objects selftest" 729 depends on DEBUG_OBJECTS 730 help 731 This enables the selftest of the object debug code. 732 733config DEBUG_OBJECTS_FREE 734 bool "Debug objects in freed memory" 735 depends on DEBUG_OBJECTS 736 help 737 This enables checks whether a k/v free operation frees an area 738 which contains an object which has not been deactivated 739 properly. This can make kmalloc/kfree-intensive workloads 740 much slower. 741 742config DEBUG_OBJECTS_TIMERS 743 bool "Debug timer objects" 744 depends on DEBUG_OBJECTS 745 help 746 If you say Y here, additional code will be inserted into the 747 timer routines to track the life time of timer objects and 748 validate the timer operations. 749 750config DEBUG_OBJECTS_WORK 751 bool "Debug work objects" 752 depends on DEBUG_OBJECTS 753 help 754 If you say Y here, additional code will be inserted into the 755 work queue routines to track the life time of work objects and 756 validate the work operations. 757 758config DEBUG_OBJECTS_RCU_HEAD 759 bool "Debug RCU callbacks objects" 760 depends on DEBUG_OBJECTS 761 help 762 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 763 764config DEBUG_OBJECTS_PERCPU_COUNTER 765 bool "Debug percpu counter objects" 766 depends on DEBUG_OBJECTS 767 help 768 If you say Y here, additional code will be inserted into the 769 percpu counter routines to track the life time of percpu counter 770 objects and validate the percpu counter operations. 771 772config DEBUG_OBJECTS_ENABLE_DEFAULT 773 int "debug_objects bootup default value (0-1)" 774 range 0 1 775 default "1" 776 depends on DEBUG_OBJECTS 777 help 778 Debug objects boot parameter default value 779 780config SHRINKER_DEBUG 781 bool "Enable shrinker debugging support" 782 depends on DEBUG_FS 783 help 784 Say Y to enable the shrinker debugfs interface which provides 785 visibility into the kernel memory shrinkers subsystem. 786 Disable it to avoid an extra memory footprint. 787 788config DEBUG_STACK_USAGE 789 bool "Stack utilization instrumentation" 790 depends on DEBUG_KERNEL 791 help 792 Enables the display of the minimum amount of free stack which each 793 task has ever had available in the sysrq-T and sysrq-P debug output. 794 Also emits a message to dmesg when a process exits if that process 795 used more stack space than previously exiting processes. 796 797 This option will slow down process creation somewhat. 798 799config SCHED_STACK_END_CHECK 800 bool "Detect stack corruption on calls to schedule()" 801 depends on DEBUG_KERNEL 802 default n 803 help 804 This option checks for a stack overrun on calls to schedule(). 805 If the stack end location is found to be over written always panic as 806 the content of the corrupted region can no longer be trusted. 807 This is to ensure no erroneous behaviour occurs which could result in 808 data corruption or a sporadic crash at a later stage once the region 809 is examined. The runtime overhead introduced is minimal. 810 811config ARCH_HAS_DEBUG_VM_PGTABLE 812 bool 813 help 814 An architecture should select this when it can successfully 815 build and run DEBUG_VM_PGTABLE. 816 817config DEBUG_VFS 818 bool "Debug VFS" 819 depends on DEBUG_KERNEL 820 help 821 Enable this to turn on extended checks in the VFS layer that may impact 822 performance. 823 824 If unsure, say N. 825 826config DEBUG_VM_IRQSOFF 827 def_bool DEBUG_VM && !PREEMPT_RT 828 829config DEBUG_VM 830 bool "Debug VM" 831 depends on DEBUG_KERNEL 832 help 833 Enable this to turn on extended checks in the virtual-memory system 834 that may impact performance. 835 836 If unsure, say N. 837 838config DEBUG_VM_SHOOT_LAZIES 839 bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation" 840 depends on DEBUG_VM 841 depends on MMU_LAZY_TLB_SHOOTDOWN 842 help 843 Enable additional IPIs that ensure lazy tlb mm references are removed 844 before the mm is freed. 845 846 If unsure, say N. 847 848config DEBUG_VM_MAPLE_TREE 849 bool "Debug VM maple trees" 850 depends on DEBUG_VM 851 select DEBUG_MAPLE_TREE 852 help 853 Enable VM maple tree debugging information and extra validations. 854 855 If unsure, say N. 856 857config DEBUG_VM_RB 858 bool "Debug VM red-black trees" 859 depends on DEBUG_VM 860 help 861 Enable VM red-black tree debugging information and extra validations. 862 863 If unsure, say N. 864 865config DEBUG_VM_PGFLAGS 866 bool "Debug page-flags operations" 867 depends on DEBUG_VM 868 help 869 Enables extra validation on page flags operations. 870 871 If unsure, say N. 872 873config DEBUG_VM_PGTABLE 874 bool "Debug arch page table for semantics compliance" 875 depends on MMU 876 depends on ARCH_HAS_DEBUG_VM_PGTABLE 877 default y if DEBUG_VM 878 help 879 This option provides a debug method which can be used to test 880 architecture page table helper functions on various platforms in 881 verifying if they comply with expected generic MM semantics. This 882 will help architecture code in making sure that any changes or 883 new additions of these helpers still conform to expected 884 semantics of the generic MM. Platforms will have to opt in for 885 this through ARCH_HAS_DEBUG_VM_PGTABLE. 886 887 If unsure, say N. 888 889config ARCH_HAS_DEBUG_VIRTUAL 890 bool 891 892config DEBUG_VIRTUAL 893 bool "Debug VM translations" 894 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL 895 help 896 Enable some costly sanity checks in virtual to page code. This can 897 catch mistakes with virt_to_page() and friends. 898 899 If unsure, say N. 900 901config DEBUG_NOMMU_REGIONS 902 bool "Debug the global anon/private NOMMU mapping region tree" 903 depends on DEBUG_KERNEL && !MMU 904 help 905 This option causes the global tree of anonymous and private mapping 906 regions to be regularly checked for invalid topology. 907 908config DEBUG_MEMORY_INIT 909 bool "Debug memory initialisation" if EXPERT 910 default !EXPERT 911 help 912 Enable this for additional checks during memory initialisation. 913 The sanity checks verify aspects of the VM such as the memory model 914 and other information provided by the architecture. Verbose 915 information will be printed at KERN_DEBUG loglevel depending 916 on the mminit_loglevel= command-line option. 917 918 If unsure, say Y 919 920config MEMORY_NOTIFIER_ERROR_INJECT 921 tristate "Memory hotplug notifier error injection module" 922 depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION 923 help 924 This option provides the ability to inject artificial errors to 925 memory hotplug notifier chain callbacks. It is controlled through 926 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 927 928 If the notifier call chain should be failed with some events 929 notified, write the error code to "actions/<notifier event>/error". 930 931 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 932 933 # cd /sys/kernel/debug/notifier-error-inject/memory 934 # echo -12 > actions/MEM_GOING_OFFLINE/error 935 # echo offline > /sys/devices/system/memory/memoryXXX/state 936 bash: echo: write error: Cannot allocate memory 937 938 To compile this code as a module, choose M here: the module will 939 be called memory-notifier-error-inject. 940 941 If unsure, say N. 942 943config DEBUG_PER_CPU_MAPS 944 bool "Debug access to per_cpu maps" 945 depends on DEBUG_KERNEL 946 depends on SMP 947 help 948 Say Y to verify that the per_cpu map being accessed has 949 been set up. This adds a fair amount of code to kernel memory 950 and decreases performance. 951 952 Say N if unsure. 953 954config DEBUG_KMAP_LOCAL 955 bool "Debug kmap_local temporary mappings" 956 depends on DEBUG_KERNEL && KMAP_LOCAL 957 help 958 This option enables additional error checking for the kmap_local 959 infrastructure. Disable for production use. 960 961config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 962 bool 963 964config DEBUG_KMAP_LOCAL_FORCE_MAP 965 bool "Enforce kmap_local temporary mappings" 966 depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 967 select KMAP_LOCAL 968 select DEBUG_KMAP_LOCAL 969 help 970 This option enforces temporary mappings through the kmap_local 971 mechanism for non-highmem pages and on non-highmem systems. 972 Disable this for production systems! 973 974config DEBUG_HIGHMEM 975 bool "Highmem debugging" 976 depends on DEBUG_KERNEL && HIGHMEM 977 select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 978 select DEBUG_KMAP_LOCAL 979 help 980 This option enables additional error checking for high memory 981 systems. Disable for production systems. 982 983config HAVE_DEBUG_STACKOVERFLOW 984 bool 985 986config DEBUG_STACKOVERFLOW 987 bool "Check for stack overflows" 988 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 989 help 990 Say Y here if you want to check for overflows of kernel, IRQ 991 and exception stacks (if your architecture uses them). This 992 option will show detailed messages if free stack space drops 993 below a certain limit. 994 995 These kinds of bugs usually occur when call-chains in the 996 kernel get too deep, especially when interrupts are 997 involved. 998 999 Use this in cases where you see apparently random memory 1000 corruption, especially if it appears in 'struct thread_info' 1001 1002 If in doubt, say "N". 1003 1004config CODE_TAGGING 1005 bool 1006 select KALLSYMS 1007 1008config MEM_ALLOC_PROFILING 1009 bool "Enable memory allocation profiling" 1010 default n 1011 depends on MMU 1012 depends on PROC_FS 1013 depends on !DEBUG_FORCE_WEAK_PER_CPU 1014 select CODE_TAGGING 1015 select PAGE_EXTENSION 1016 select SLAB_OBJ_EXT 1017 help 1018 Track allocation source code and record total allocation size 1019 initiated at that code location. The mechanism can be used to track 1020 memory leaks with a low performance and memory impact. 1021 1022config MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT 1023 bool "Enable memory allocation profiling by default" 1024 default y 1025 depends on MEM_ALLOC_PROFILING 1026 1027config MEM_ALLOC_PROFILING_DEBUG 1028 bool "Memory allocation profiler debugging" 1029 default n 1030 depends on MEM_ALLOC_PROFILING 1031 select MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT 1032 help 1033 Adds warnings with helpful error messages for memory allocation 1034 profiling. 1035 1036source "lib/Kconfig.kasan" 1037source "lib/Kconfig.kfence" 1038source "lib/Kconfig.kmsan" 1039 1040endmenu # "Memory Debugging" 1041 1042config DEBUG_SHIRQ 1043 bool "Debug shared IRQ handlers" 1044 depends on DEBUG_KERNEL 1045 help 1046 Enable this to generate a spurious interrupt just before a shared 1047 interrupt handler is deregistered (generating one when registering 1048 is currently disabled). Drivers need to handle this correctly. Some 1049 don't and need to be caught. 1050 1051menu "Debug Oops, Lockups and Hangs" 1052 1053config PANIC_ON_OOPS 1054 bool "Panic on Oops" 1055 help 1056 Say Y here to enable the kernel to panic when it oopses. This 1057 has the same effect as setting oops=panic on the kernel command 1058 line. 1059 1060 This feature is useful to ensure that the kernel does not do 1061 anything erroneous after an oops which could result in data 1062 corruption or other issues. 1063 1064 Say N if unsure. 1065 1066config PANIC_TIMEOUT 1067 int "panic timeout" 1068 default 0 1069 help 1070 Set the timeout value (in seconds) until a reboot occurs when 1071 the kernel panics. If n = 0, then we wait forever. A timeout 1072 value n > 0 will wait n seconds before rebooting, while a timeout 1073 value n < 0 will reboot immediately. This setting can be overridden 1074 with the kernel command line option panic=, and from userspace via 1075 /proc/sys/kernel/panic. 1076 1077config LOCKUP_DETECTOR 1078 bool 1079 1080config SOFTLOCKUP_DETECTOR 1081 bool "Detect Soft Lockups" 1082 depends on DEBUG_KERNEL && !S390 1083 select LOCKUP_DETECTOR 1084 help 1085 Say Y here to enable the kernel to act as a watchdog to detect 1086 soft lockups. 1087 1088 Softlockups are bugs that cause the kernel to loop in kernel 1089 mode for more than 20 seconds, without giving other tasks a 1090 chance to run. The current stack trace is displayed upon 1091 detection and the system will stay locked up. 1092 1093config SOFTLOCKUP_DETECTOR_INTR_STORM 1094 bool "Detect Interrupt Storm in Soft Lockups" 1095 depends on SOFTLOCKUP_DETECTOR && IRQ_TIME_ACCOUNTING 1096 select GENERIC_IRQ_STAT_SNAPSHOT 1097 default y if NR_CPUS <= 128 1098 help 1099 Say Y here to enable the kernel to detect interrupt storm 1100 during "soft lockups". 1101 1102 "soft lockups" can be caused by a variety of reasons. If one is 1103 caused by an interrupt storm, then the storming interrupts will not 1104 be on the callstack. To detect this case, it is necessary to report 1105 the CPU stats and the interrupt counts during the "soft lockups". 1106 1107config BOOTPARAM_SOFTLOCKUP_PANIC 1108 bool "Panic (Reboot) On Soft Lockups" 1109 depends on SOFTLOCKUP_DETECTOR 1110 help 1111 Say Y here to enable the kernel to panic on "soft lockups", 1112 which are bugs that cause the kernel to loop in kernel 1113 mode for more than 20 seconds (configurable using the watchdog_thresh 1114 sysctl), without giving other tasks a chance to run. 1115 1116 The panic can be used in combination with panic_timeout, 1117 to cause the system to reboot automatically after a 1118 lockup has been detected. This feature is useful for 1119 high-availability systems that have uptime guarantees and 1120 where a lockup must be resolved ASAP. 1121 1122 Say N if unsure. 1123 1124config HAVE_HARDLOCKUP_DETECTOR_BUDDY 1125 bool 1126 depends on SMP 1127 default y 1128 1129# 1130# Global switch whether to build a hardlockup detector at all. It is available 1131# only when the architecture supports at least one implementation. There are 1132# two exceptions. The hardlockup detector is never enabled on: 1133# 1134# s390: it reported many false positives there 1135# 1136# sparc64: has a custom implementation which is not using the common 1137# hardlockup command line options and sysctl interface. 1138# 1139config HARDLOCKUP_DETECTOR 1140 bool "Detect Hard Lockups" 1141 depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64 1142 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH 1143 imply HARDLOCKUP_DETECTOR_PERF 1144 imply HARDLOCKUP_DETECTOR_BUDDY 1145 imply HARDLOCKUP_DETECTOR_ARCH 1146 select LOCKUP_DETECTOR 1147 1148 help 1149 Say Y here to enable the kernel to act as a watchdog to detect 1150 hard lockups. 1151 1152 Hardlockups are bugs that cause the CPU to loop in kernel mode 1153 for more than 10 seconds, without letting other interrupts have a 1154 chance to run. The current stack trace is displayed upon detection 1155 and the system will stay locked up. 1156 1157# 1158# Note that arch-specific variants are always preferred. 1159# 1160config HARDLOCKUP_DETECTOR_PREFER_BUDDY 1161 bool "Prefer the buddy CPU hardlockup detector" 1162 depends on HARDLOCKUP_DETECTOR 1163 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY 1164 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1165 help 1166 Say Y here to prefer the buddy hardlockup detector over the perf one. 1167 1168 With the buddy detector, each CPU uses its softlockup hrtimer 1169 to check that the next CPU is processing hrtimer interrupts by 1170 verifying that a counter is increasing. 1171 1172 This hardlockup detector is useful on systems that don't have 1173 an arch-specific hardlockup detector or if resources needed 1174 for the hardlockup detector are better used for other things. 1175 1176config HARDLOCKUP_DETECTOR_PERF 1177 bool 1178 depends on HARDLOCKUP_DETECTOR 1179 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY 1180 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1181 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1182 1183config HARDLOCKUP_DETECTOR_BUDDY 1184 bool 1185 depends on HARDLOCKUP_DETECTOR 1186 depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY 1187 depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY 1188 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1189 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1190 1191config HARDLOCKUP_DETECTOR_ARCH 1192 bool 1193 depends on HARDLOCKUP_DETECTOR 1194 depends on HAVE_HARDLOCKUP_DETECTOR_ARCH 1195 help 1196 The arch-specific implementation of the hardlockup detector will 1197 be used. 1198 1199# 1200# Both the "perf" and "buddy" hardlockup detectors count hrtimer 1201# interrupts. This config enables functions managing this common code. 1202# 1203config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1204 bool 1205 select SOFTLOCKUP_DETECTOR 1206 1207# 1208# Enables a timestamp based low pass filter to compensate for perf based 1209# hard lockup detection which runs too fast due to turbo modes. 1210# 1211config HARDLOCKUP_CHECK_TIMESTAMP 1212 bool 1213 1214config BOOTPARAM_HARDLOCKUP_PANIC 1215 bool "Panic (Reboot) On Hard Lockups" 1216 depends on HARDLOCKUP_DETECTOR 1217 help 1218 Say Y here to enable the kernel to panic on "hard lockups", 1219 which are bugs that cause the kernel to loop in kernel 1220 mode with interrupts disabled for more than 10 seconds (configurable 1221 using the watchdog_thresh sysctl). 1222 1223 Say N if unsure. 1224 1225config DETECT_HUNG_TASK 1226 bool "Detect Hung Tasks" 1227 depends on DEBUG_KERNEL 1228 default SOFTLOCKUP_DETECTOR 1229 help 1230 Say Y here to enable the kernel to detect "hung tasks", 1231 which are bugs that cause the task to be stuck in 1232 uninterruptible "D" state indefinitely. 1233 1234 When a hung task is detected, the kernel will print the 1235 current stack trace (which you should report), but the 1236 task will stay in uninterruptible state. If lockdep is 1237 enabled then all held locks will also be reported. This 1238 feature has negligible overhead. 1239 1240config DEFAULT_HUNG_TASK_TIMEOUT 1241 int "Default timeout for hung task detection (in seconds)" 1242 depends on DETECT_HUNG_TASK 1243 default 120 1244 help 1245 This option controls the default timeout (in seconds) used 1246 to determine when a task has become non-responsive and should 1247 be considered hung. 1248 1249 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 1250 sysctl or by writing a value to 1251 /proc/sys/kernel/hung_task_timeout_secs. 1252 1253 A timeout of 0 disables the check. The default is two minutes. 1254 Keeping the default should be fine in most cases. 1255 1256config BOOTPARAM_HUNG_TASK_PANIC 1257 int "Number of hung tasks to trigger kernel panic" 1258 depends on DETECT_HUNG_TASK 1259 default 0 1260 help 1261 When set to a non-zero value, a kernel panic will be triggered 1262 if the number of hung tasks found during a single scan reaches 1263 this value. 1264 1265 The panic can be used in combination with panic_timeout, 1266 to cause the system to reboot automatically after a 1267 hung task has been detected. This feature is useful for 1268 high-availability systems that have uptime guarantees and 1269 where a hung tasks must be resolved ASAP. 1270 1271 Say N if unsure. 1272 1273config DETECT_HUNG_TASK_BLOCKER 1274 bool "Dump Hung Tasks Blocker" 1275 depends on DETECT_HUNG_TASK 1276 depends on !PREEMPT_RT 1277 default y 1278 help 1279 Say Y here to show the blocker task's stacktrace who acquires 1280 the mutex lock which "hung tasks" are waiting. 1281 This will add overhead a bit but shows suspicious tasks and 1282 call trace if it comes from waiting a mutex. 1283 1284config WQ_WATCHDOG 1285 bool "Detect Workqueue Stalls" 1286 depends on DEBUG_KERNEL 1287 help 1288 Say Y here to enable stall detection on workqueues. If a 1289 worker pool doesn't make forward progress on a pending work 1290 item for over a given amount of time, 30s by default, a 1291 warning message is printed along with dump of workqueue 1292 state. This can be configured through kernel parameter 1293 "workqueue.watchdog_thresh" and its sysfs counterpart. 1294 1295config WQ_CPU_INTENSIVE_REPORT 1296 bool "Report per-cpu work items which hog CPU for too long" 1297 depends on DEBUG_KERNEL 1298 help 1299 Say Y here to enable reporting of concurrency-managed per-cpu work 1300 items that hog CPUs for longer than 1301 workqueue.cpu_intensive_thresh_us. Workqueue automatically 1302 detects and excludes them from concurrency management to prevent 1303 them from stalling other per-cpu work items. Occassional 1304 triggering may not necessarily indicate a problem. Repeated 1305 triggering likely indicates that the work item should be switched 1306 to use an unbound workqueue. 1307 1308config TEST_LOCKUP 1309 tristate "Test module to generate lockups" 1310 depends on m 1311 help 1312 This builds the "test_lockup" module that helps to make sure 1313 that watchdogs and lockup detectors are working properly. 1314 1315 Depending on module parameters it could emulate soft or hard 1316 lockup, "hung task", or locking arbitrary lock for a long time. 1317 Also it could generate series of lockups with cooling-down periods. 1318 1319 If unsure, say N. 1320 1321endmenu # "Debug lockups and hangs" 1322 1323menu "Scheduler Debugging" 1324 1325config SCHED_INFO 1326 bool 1327 default n 1328 1329config SCHEDSTATS 1330 bool "Collect scheduler statistics" 1331 depends on PROC_FS 1332 select SCHED_INFO 1333 help 1334 If you say Y here, additional code will be inserted into the 1335 scheduler and related routines to collect statistics about 1336 scheduler behavior and provide them in /proc/schedstat. These 1337 stats may be useful for both tuning and debugging the scheduler 1338 If you aren't debugging the scheduler or trying to tune a specific 1339 application, you can say N to avoid the very slight overhead 1340 this adds. 1341 1342endmenu 1343 1344config DEBUG_PREEMPT 1345 bool "Debug preemptible kernel" 1346 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1347 help 1348 If you say Y here then the kernel will use a debug variant of the 1349 commonly used smp_processor_id() function and will print warnings 1350 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1351 will detect preemption count underflows. 1352 1353 This option has potential to introduce high runtime overhead, 1354 depending on workload as it triggers debugging routines for each 1355 this_cpu operation. It should only be used for debugging purposes. 1356 1357menu "Lock Debugging (spinlocks, mutexes, etc...)" 1358 1359config LOCK_DEBUGGING_SUPPORT 1360 bool 1361 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1362 default y 1363 1364config PROVE_LOCKING 1365 bool "Lock debugging: prove locking correctness" 1366 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1367 select LOCKDEP 1368 select DEBUG_SPINLOCK 1369 select DEBUG_MUTEXES if !PREEMPT_RT 1370 select DEBUG_RT_MUTEXES if RT_MUTEXES 1371 select DEBUG_RWSEMS if !PREEMPT_RT 1372 select DEBUG_WW_MUTEX_SLOWPATH 1373 select DEBUG_LOCK_ALLOC 1374 select PREEMPT_COUNT if !ARCH_NO_PREEMPT 1375 select TRACE_IRQFLAGS 1376 default n 1377 help 1378 This feature enables the kernel to prove that all locking 1379 that occurs in the kernel runtime is mathematically 1380 correct: that under no circumstance could an arbitrary (and 1381 not yet triggered) combination of observed locking 1382 sequences (on an arbitrary number of CPUs, running an 1383 arbitrary number of tasks and interrupt contexts) cause a 1384 deadlock. 1385 1386 In short, this feature enables the kernel to report locking 1387 related deadlocks before they actually occur. 1388 1389 The proof does not depend on how hard and complex a 1390 deadlock scenario would be to trigger: how many 1391 participant CPUs, tasks and irq-contexts would be needed 1392 for it to trigger. The proof also does not depend on 1393 timing: if a race and a resulting deadlock is possible 1394 theoretically (no matter how unlikely the race scenario 1395 is), it will be proven so and will immediately be 1396 reported by the kernel (once the event is observed that 1397 makes the deadlock theoretically possible). 1398 1399 If a deadlock is impossible (i.e. the locking rules, as 1400 observed by the kernel, are mathematically correct), the 1401 kernel reports nothing. 1402 1403 NOTE: this feature can also be enabled for rwlocks, mutexes 1404 and rwsems - in which case all dependencies between these 1405 different locking variants are observed and mapped too, and 1406 the proof of observed correctness is also maintained for an 1407 arbitrary combination of these separate locking variants. 1408 1409 For more details, see Documentation/locking/lockdep-design.rst. 1410 1411config PROVE_RAW_LOCK_NESTING 1412 bool "Enable raw_spinlock - spinlock nesting checks" if !ARCH_SUPPORTS_RT 1413 depends on PROVE_LOCKING 1414 default y if ARCH_SUPPORTS_RT 1415 help 1416 Enable the raw_spinlock vs. spinlock nesting checks which ensure 1417 that the lock nesting rules for PREEMPT_RT enabled kernels are 1418 not violated. 1419 1420config LOCK_STAT 1421 bool "Lock usage statistics" 1422 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1423 select LOCKDEP 1424 select DEBUG_SPINLOCK 1425 select DEBUG_MUTEXES if !PREEMPT_RT 1426 select DEBUG_RT_MUTEXES if RT_MUTEXES 1427 select DEBUG_LOCK_ALLOC 1428 default n 1429 help 1430 This feature enables tracking lock contention points 1431 1432 For more details, see Documentation/locking/lockstat.rst 1433 1434 This also enables lock events required by "perf lock", 1435 subcommand of perf. 1436 If you want to use "perf lock", you also need to turn on 1437 CONFIG_EVENT_TRACING. 1438 1439 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1440 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1441 1442config DEBUG_RT_MUTEXES 1443 bool "RT Mutex debugging, deadlock detection" 1444 depends on DEBUG_KERNEL && RT_MUTEXES 1445 help 1446 This allows rt mutex semantics violations and rt mutex related 1447 deadlocks (lockups) to be detected and reported automatically. 1448 1449config DEBUG_SPINLOCK 1450 bool "Spinlock and rw-lock debugging: basic checks" 1451 depends on DEBUG_KERNEL 1452 select UNINLINE_SPIN_UNLOCK 1453 help 1454 Say Y here and build SMP to catch missing spinlock initialization 1455 and certain other kinds of spinlock errors commonly made. This is 1456 best used in conjunction with the NMI watchdog so that spinlock 1457 deadlocks are also debuggable. 1458 1459config DEBUG_MUTEXES 1460 bool "Mutex debugging: basic checks" 1461 depends on DEBUG_KERNEL && !PREEMPT_RT 1462 help 1463 This feature allows mutex semantics violations to be detected and 1464 reported. 1465 1466config DEBUG_WW_MUTEX_SLOWPATH 1467 bool "Wait/wound mutex debugging: Slowpath testing" 1468 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1469 select DEBUG_LOCK_ALLOC 1470 select DEBUG_SPINLOCK 1471 select DEBUG_MUTEXES if !PREEMPT_RT 1472 select DEBUG_RT_MUTEXES if PREEMPT_RT 1473 help 1474 This feature enables slowpath testing for w/w mutex users by 1475 injecting additional -EDEADLK wound/backoff cases. Together with 1476 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1477 will test all possible w/w mutex interface abuse with the 1478 exception of simply not acquiring all the required locks. 1479 Note that this feature can introduce significant overhead, so 1480 it really should not be enabled in a production or distro kernel, 1481 even a debug kernel. If you are a driver writer, enable it. If 1482 you are a distro, do not. 1483 1484config DEBUG_RWSEMS 1485 bool "RW Semaphore debugging: basic checks" 1486 depends on DEBUG_KERNEL && !PREEMPT_RT 1487 help 1488 This debugging feature allows mismatched rw semaphore locks 1489 and unlocks to be detected and reported. 1490 1491config DEBUG_LOCK_ALLOC 1492 bool "Lock debugging: detect incorrect freeing of live locks" 1493 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1494 select DEBUG_SPINLOCK 1495 select DEBUG_MUTEXES if !PREEMPT_RT 1496 select DEBUG_RT_MUTEXES if RT_MUTEXES 1497 select LOCKDEP 1498 help 1499 This feature will check whether any held lock (spinlock, rwlock, 1500 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1501 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1502 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1503 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1504 held during task exit. 1505 1506config LOCKDEP 1507 bool 1508 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1509 select STACKTRACE 1510 select KALLSYMS 1511 select KALLSYMS_ALL 1512 1513config LOCKDEP_SMALL 1514 bool 1515 1516config LOCKDEP_BITS 1517 int "Size for MAX_LOCKDEP_ENTRIES (as Nth power of 2)" 1518 depends on LOCKDEP && !LOCKDEP_SMALL 1519 range 10 24 1520 default 15 1521 help 1522 Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message. 1523 1524config LOCKDEP_CHAINS_BITS 1525 int "Size for MAX_LOCKDEP_CHAINS (as Nth power of 2)" 1526 depends on LOCKDEP && !LOCKDEP_SMALL 1527 range 10 21 1528 default 16 1529 help 1530 Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message. 1531 1532config LOCKDEP_STACK_TRACE_BITS 1533 int "Size for MAX_STACK_TRACE_ENTRIES (as Nth power of 2)" 1534 depends on LOCKDEP && !LOCKDEP_SMALL 1535 range 10 26 1536 default 19 1537 help 1538 Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message. 1539 1540config LOCKDEP_STACK_TRACE_HASH_BITS 1541 int "Size for STACK_TRACE_HASH_SIZE (as Nth power of 2)" 1542 depends on LOCKDEP && !LOCKDEP_SMALL 1543 range 10 26 1544 default 14 1545 help 1546 Try increasing this value if you need large STACK_TRACE_HASH_SIZE. 1547 1548config LOCKDEP_CIRCULAR_QUEUE_BITS 1549 int "Size for elements in circular_queue struct (as Nth power of 2)" 1550 depends on LOCKDEP 1551 range 10 26 1552 default 12 1553 help 1554 Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure. 1555 1556config DEBUG_LOCKDEP 1557 bool "Lock dependency engine debugging" 1558 depends on DEBUG_KERNEL && LOCKDEP 1559 select DEBUG_IRQFLAGS 1560 help 1561 If you say Y here, the lock dependency engine will do 1562 additional runtime checks to debug itself, at the price 1563 of more runtime overhead. 1564 1565config DEBUG_ATOMIC_SLEEP 1566 bool "Sleep inside atomic section checking" 1567 select PREEMPT_COUNT 1568 depends on DEBUG_KERNEL 1569 depends on !ARCH_NO_PREEMPT 1570 help 1571 If you say Y here, various routines which may sleep will become very 1572 noisy if they are called inside atomic sections: when a spinlock is 1573 held, inside an rcu read side critical section, inside preempt disabled 1574 sections, inside an interrupt, etc... 1575 1576config DEBUG_LOCKING_API_SELFTESTS 1577 bool "Locking API boot-time self-tests" 1578 depends on DEBUG_KERNEL 1579 help 1580 Say Y here if you want the kernel to run a short self-test during 1581 bootup. The self-test checks whether common types of locking bugs 1582 are detected by debugging mechanisms or not. (if you disable 1583 lock debugging then those bugs won't be detected of course.) 1584 The following locking APIs are covered: spinlocks, rwlocks, 1585 mutexes and rwsems. 1586 1587config LOCK_TORTURE_TEST 1588 tristate "torture tests for locking" 1589 depends on DEBUG_KERNEL 1590 select TORTURE_TEST 1591 help 1592 This option provides a kernel module that runs torture tests 1593 on kernel locking primitives. The kernel module may be built 1594 after the fact on the running kernel to be tested, if desired. 1595 1596 Say Y here if you want kernel locking-primitive torture tests 1597 to be built into the kernel. 1598 Say M if you want these torture tests to build as a module. 1599 Say N if you are unsure. 1600 1601config WW_MUTEX_SELFTEST 1602 tristate "Wait/wound mutex selftests" 1603 help 1604 This option provides a kernel module that runs tests on the 1605 on the struct ww_mutex locking API. 1606 1607 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1608 with this test harness. 1609 1610 Say M if you want these self tests to build as a module. 1611 Say N if you are unsure. 1612 1613config SCF_TORTURE_TEST 1614 tristate "torture tests for smp_call_function*()" 1615 depends on DEBUG_KERNEL 1616 select TORTURE_TEST 1617 help 1618 This option provides a kernel module that runs torture tests 1619 on the smp_call_function() family of primitives. The kernel 1620 module may be built after the fact on the running kernel to 1621 be tested, if desired. 1622 1623config CSD_LOCK_WAIT_DEBUG 1624 bool "Debugging for csd_lock_wait(), called from smp_call_function*()" 1625 depends on DEBUG_KERNEL 1626 depends on SMP 1627 depends on 64BIT 1628 default n 1629 help 1630 This option enables debug prints when CPUs are slow to respond 1631 to the smp_call_function*() IPI wrappers. These debug prints 1632 include the IPI handler function currently executing (if any) 1633 and relevant stack traces. 1634 1635config CSD_LOCK_WAIT_DEBUG_DEFAULT 1636 bool "Default csd_lock_wait() debugging on at boot time" 1637 depends on CSD_LOCK_WAIT_DEBUG 1638 depends on 64BIT 1639 default n 1640 help 1641 This option causes the csdlock_debug= kernel boot parameter to 1642 default to 1 (basic debugging) instead of 0 (no debugging). 1643 1644endmenu # lock debugging 1645 1646config TRACE_IRQFLAGS 1647 depends on TRACE_IRQFLAGS_SUPPORT 1648 bool 1649 help 1650 Enables hooks to interrupt enabling and disabling for 1651 either tracing or lock debugging. 1652 1653config TRACE_IRQFLAGS_NMI 1654 def_bool y 1655 depends on TRACE_IRQFLAGS 1656 depends on TRACE_IRQFLAGS_NMI_SUPPORT 1657 1658config NMI_CHECK_CPU 1659 bool "Debugging for CPUs failing to respond to backtrace requests" 1660 depends on DEBUG_KERNEL 1661 depends on X86 1662 default n 1663 help 1664 Enables debug prints when a CPU fails to respond to a given 1665 backtrace NMI. These prints provide some reasons why a CPU 1666 might legitimately be failing to respond, for example, if it 1667 is offline of if ignore_nmis is set. 1668 1669config DEBUG_IRQFLAGS 1670 bool "Debug IRQ flag manipulation" 1671 help 1672 Enables checks for potentially unsafe enabling or disabling of 1673 interrupts, such as calling raw_local_irq_restore() when interrupts 1674 are enabled. 1675 1676config STACKTRACE 1677 bool "Stack backtrace support" 1678 depends on STACKTRACE_SUPPORT 1679 help 1680 This option causes the kernel to create a /proc/pid/stack for 1681 every process, showing its current stack trace. 1682 It is also used by various kernel debugging features that require 1683 stack trace generation. 1684 1685config WARN_ALL_UNSEEDED_RANDOM 1686 bool "Warn for all uses of unseeded randomness" 1687 default n 1688 help 1689 Some parts of the kernel contain bugs relating to their use of 1690 cryptographically secure random numbers before it's actually possible 1691 to generate those numbers securely. This setting ensures that these 1692 flaws don't go unnoticed, by enabling a message, should this ever 1693 occur. This will allow people with obscure setups to know when things 1694 are going wrong, so that they might contact developers about fixing 1695 it. 1696 1697 Unfortunately, on some models of some architectures getting 1698 a fully seeded CRNG is extremely difficult, and so this can 1699 result in dmesg getting spammed for a surprisingly long 1700 time. This is really bad from a security perspective, and 1701 so architecture maintainers really need to do what they can 1702 to get the CRNG seeded sooner after the system is booted. 1703 However, since users cannot do anything actionable to 1704 address this, by default this option is disabled. 1705 1706 Say Y here if you want to receive warnings for all uses of 1707 unseeded randomness. This will be of use primarily for 1708 those developers interested in improving the security of 1709 Linux kernels running on their architecture (or 1710 subarchitecture). 1711 1712config DEBUG_KOBJECT 1713 bool "kobject debugging" 1714 depends on DEBUG_KERNEL 1715 help 1716 If you say Y here, some extra kobject debugging messages will be sent 1717 to the syslog. 1718 1719config DEBUG_KOBJECT_RELEASE 1720 bool "kobject release debugging" 1721 depends on DEBUG_OBJECTS_TIMERS 1722 help 1723 kobjects are reference counted objects. This means that their 1724 last reference count put is not predictable, and the kobject can 1725 live on past the point at which a driver decides to drop its 1726 initial reference to the kobject gained on allocation. An 1727 example of this would be a struct device which has just been 1728 unregistered. 1729 1730 However, some buggy drivers assume that after such an operation, 1731 the memory backing the kobject can be immediately freed. This 1732 goes completely against the principles of a refcounted object. 1733 1734 If you say Y here, the kernel will delay the release of kobjects 1735 on the last reference count to improve the visibility of this 1736 kind of kobject release bug. 1737 1738config HAVE_DEBUG_BUGVERBOSE 1739 bool 1740 1741menu "Debug kernel data structures" 1742 1743config DEBUG_LIST 1744 bool "Debug linked list manipulation" 1745 depends on DEBUG_KERNEL 1746 select LIST_HARDENED 1747 help 1748 Enable this to turn on extended checks in the linked-list walking 1749 routines. 1750 1751 This option trades better quality error reports for performance, and 1752 is more suitable for kernel debugging. If you care about performance, 1753 you should only enable CONFIG_LIST_HARDENED instead. 1754 1755 If unsure, say N. 1756 1757config DEBUG_PLIST 1758 bool "Debug priority linked list manipulation" 1759 depends on DEBUG_KERNEL 1760 help 1761 Enable this to turn on extended checks in the priority-ordered 1762 linked-list (plist) walking routines. This checks the entire 1763 list multiple times during each manipulation. 1764 1765 If unsure, say N. 1766 1767config DEBUG_SG 1768 bool "Debug SG table operations" 1769 depends on DEBUG_KERNEL 1770 help 1771 Enable this to turn on checks on scatter-gather tables. This can 1772 help find problems with drivers that do not properly initialize 1773 their sg tables. 1774 1775 If unsure, say N. 1776 1777config DEBUG_NOTIFIERS 1778 bool "Debug notifier call chains" 1779 depends on DEBUG_KERNEL 1780 help 1781 Enable this to turn on sanity checking for notifier call chains. 1782 This is most useful for kernel developers to make sure that 1783 modules properly unregister themselves from notifier chains. 1784 This is a relatively cheap check but if you care about maximum 1785 performance, say N. 1786 1787config DEBUG_CLOSURES 1788 bool "Debug closures (bcache async widgits)" 1789 depends on CLOSURES 1790 select DEBUG_FS 1791 help 1792 Keeps all active closures in a linked list and provides a debugfs 1793 interface to list them, which makes it possible to see asynchronous 1794 operations that get stuck. 1795 1796config DEBUG_MAPLE_TREE 1797 bool "Debug maple trees" 1798 depends on DEBUG_KERNEL 1799 help 1800 Enable maple tree debugging information and extra validations. 1801 1802 If unsure, say N. 1803 1804endmenu 1805 1806source "kernel/rcu/Kconfig.debug" 1807 1808config DEBUG_WQ_FORCE_RR_CPU 1809 bool "Force round-robin CPU selection for unbound work items" 1810 depends on DEBUG_KERNEL 1811 default n 1812 help 1813 Workqueue used to implicitly guarantee that work items queued 1814 without explicit CPU specified are put on the local CPU. This 1815 guarantee is no longer true and while local CPU is still 1816 preferred work items may be put on foreign CPUs. Kernel 1817 parameter "workqueue.debug_force_rr_cpu" is added to force 1818 round-robin CPU selection to flush out usages which depend on the 1819 now broken guarantee. This config option enables the debug 1820 feature by default. When enabled, memory and cache locality will 1821 be impacted. 1822 1823config CPU_HOTPLUG_STATE_CONTROL 1824 bool "Enable CPU hotplug state control" 1825 depends on DEBUG_KERNEL 1826 depends on HOTPLUG_CPU 1827 default n 1828 help 1829 Allows to write steps between "offline" and "online" to the CPUs 1830 sysfs target file so states can be stepped granular. This is a debug 1831 option for now as the hotplug machinery cannot be stopped and 1832 restarted at arbitrary points yet. 1833 1834 Say N if your are unsure. 1835 1836config LATENCYTOP 1837 bool "Latency measuring infrastructure" 1838 depends on DEBUG_KERNEL 1839 depends on STACKTRACE_SUPPORT 1840 depends on PROC_FS 1841 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 1842 select KALLSYMS 1843 select KALLSYMS_ALL 1844 select STACKTRACE 1845 select SCHEDSTATS 1846 help 1847 Enable this option if you want to use the LatencyTOP tool 1848 to find out which userspace is blocking on what kernel operations. 1849 1850config DEBUG_CGROUP_REF 1851 bool "Disable inlining of cgroup css reference count functions" 1852 depends on DEBUG_KERNEL 1853 depends on CGROUPS 1854 depends on KPROBES 1855 default n 1856 help 1857 Force cgroup css reference count functions to not be inlined so 1858 that they can be kprobed for debugging. 1859 1860source "kernel/trace/Kconfig" 1861 1862config PROVIDE_OHCI1394_DMA_INIT 1863 bool "Remote debugging over FireWire early on boot" 1864 depends on PCI && X86 1865 help 1866 If you want to debug problems which hang or crash the kernel early 1867 on boot and the crashing machine has a FireWire port, you can use 1868 this feature to remotely access the memory of the crashed machine 1869 over FireWire. This employs remote DMA as part of the OHCI1394 1870 specification which is now the standard for FireWire controllers. 1871 1872 With remote DMA, you can monitor the printk buffer remotely using 1873 firescope and access all memory below 4GB using fireproxy from gdb. 1874 Even controlling a kernel debugger is possible using remote DMA. 1875 1876 Usage: 1877 1878 If ohci1394_dma=early is used as boot parameter, it will initialize 1879 all OHCI1394 controllers which are found in the PCI config space. 1880 1881 As all changes to the FireWire bus such as enabling and disabling 1882 devices cause a bus reset and thereby disable remote DMA for all 1883 devices, be sure to have the cable plugged and FireWire enabled on 1884 the debugging host before booting the debug target for debugging. 1885 1886 This code (~1k) is freed after boot. By then, the firewire stack 1887 in charge of the OHCI-1394 controllers should be used instead. 1888 1889 See Documentation/core-api/debugging-via-ohci1394.rst for more information. 1890 1891source "samples/Kconfig" 1892 1893config ARCH_HAS_DEVMEM_IS_ALLOWED 1894 bool 1895 1896config STRICT_DEVMEM 1897 bool "Filter access to /dev/mem" 1898 depends on MMU && DEVMEM 1899 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED 1900 default y if PPC || X86 || ARM64 || S390 1901 help 1902 If this option is disabled, you allow userspace (root) access to all 1903 of memory, including kernel and userspace memory. Accidental 1904 access to this is obviously disastrous, but specific access can 1905 be used by people debugging the kernel. Note that with PAT support 1906 enabled, even in this case there are restrictions on /dev/mem 1907 use due to the cache aliasing requirements. 1908 1909 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 1910 file only allows userspace access to PCI space and the BIOS code and 1911 data regions. This is sufficient for dosemu and X and all common 1912 users of /dev/mem. 1913 1914 If in doubt, say Y. 1915 1916config IO_STRICT_DEVMEM 1917 bool "Filter I/O access to /dev/mem" 1918 depends on STRICT_DEVMEM 1919 help 1920 If this option is disabled, you allow userspace (root) access to all 1921 io-memory regardless of whether a driver is actively using that 1922 range. Accidental access to this is obviously disastrous, but 1923 specific access can be used by people debugging kernel drivers. 1924 1925 If this option is switched on, the /dev/mem file only allows 1926 userspace access to *idle* io-memory ranges (see /proc/iomem) This 1927 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 1928 if the driver using a given range cannot be disabled. 1929 1930 If in doubt, say Y. 1931 1932menu "$(SRCARCH) Debugging" 1933 1934source "arch/$(SRCARCH)/Kconfig.debug" 1935 1936endmenu 1937 1938menu "Kernel Testing and Coverage" 1939 1940source "lib/kunit/Kconfig" 1941 1942config NOTIFIER_ERROR_INJECTION 1943 tristate "Notifier error injection" 1944 depends on DEBUG_KERNEL 1945 select DEBUG_FS 1946 help 1947 This option provides the ability to inject artificial errors to 1948 specified notifier chain callbacks. It is useful to test the error 1949 handling of notifier call chain failures. 1950 1951 Say N if unsure. 1952 1953config PM_NOTIFIER_ERROR_INJECT 1954 tristate "PM notifier error injection module" 1955 depends on PM && NOTIFIER_ERROR_INJECTION 1956 default m if PM_DEBUG 1957 help 1958 This option provides the ability to inject artificial errors to 1959 PM notifier chain callbacks. It is controlled through debugfs 1960 interface /sys/kernel/debug/notifier-error-inject/pm 1961 1962 If the notifier call chain should be failed with some events 1963 notified, write the error code to "actions/<notifier event>/error". 1964 1965 Example: Inject PM suspend error (-12 = -ENOMEM) 1966 1967 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1968 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1969 # echo mem > /sys/power/state 1970 bash: echo: write error: Cannot allocate memory 1971 1972 To compile this code as a module, choose M here: the module will 1973 be called pm-notifier-error-inject. 1974 1975 If unsure, say N. 1976 1977config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1978 tristate "OF reconfig notifier error injection module" 1979 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1980 help 1981 This option provides the ability to inject artificial errors to 1982 OF reconfig notifier chain callbacks. It is controlled 1983 through debugfs interface under 1984 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1985 1986 If the notifier call chain should be failed with some events 1987 notified, write the error code to "actions/<notifier event>/error". 1988 1989 To compile this code as a module, choose M here: the module will 1990 be called of-reconfig-notifier-error-inject. 1991 1992 If unsure, say N. 1993 1994config NETDEV_NOTIFIER_ERROR_INJECT 1995 tristate "Netdev notifier error injection module" 1996 depends on NET && NOTIFIER_ERROR_INJECTION 1997 help 1998 This option provides the ability to inject artificial errors to 1999 netdevice notifier chain callbacks. It is controlled through debugfs 2000 interface /sys/kernel/debug/notifier-error-inject/netdev 2001 2002 If the notifier call chain should be failed with some events 2003 notified, write the error code to "actions/<notifier event>/error". 2004 2005 Example: Inject netdevice mtu change error (-22 = -EINVAL) 2006 2007 # cd /sys/kernel/debug/notifier-error-inject/netdev 2008 # echo -22 > actions/NETDEV_CHANGEMTU/error 2009 # ip link set eth0 mtu 1024 2010 RTNETLINK answers: Invalid argument 2011 2012 To compile this code as a module, choose M here: the module will 2013 be called netdev-notifier-error-inject. 2014 2015 If unsure, say N. 2016 2017config FUNCTION_ERROR_INJECTION 2018 bool "Fault-injections of functions" 2019 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 2020 help 2021 Add fault injections into various functions that are annotated with 2022 ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return 2023 value of these functions. This is useful to test error paths of code. 2024 2025 If unsure, say N 2026 2027config FAULT_INJECTION 2028 bool "Fault-injection framework" 2029 depends on DEBUG_KERNEL 2030 help 2031 Provide fault-injection framework. 2032 For more details, see Documentation/fault-injection/. 2033 2034config FAILSLAB 2035 bool "Fault-injection capability for kmalloc" 2036 depends on FAULT_INJECTION 2037 help 2038 Provide fault-injection capability for kmalloc. 2039 2040config FAIL_PAGE_ALLOC 2041 bool "Fault-injection capability for alloc_pages()" 2042 depends on FAULT_INJECTION 2043 help 2044 Provide fault-injection capability for alloc_pages(). 2045 2046config FAULT_INJECTION_USERCOPY 2047 bool "Fault injection capability for usercopy functions" 2048 depends on FAULT_INJECTION 2049 help 2050 Provides fault-injection capability to inject failures 2051 in usercopy functions (copy_from_user(), get_user(), ...). 2052 2053config FAIL_MAKE_REQUEST 2054 bool "Fault-injection capability for disk IO" 2055 depends on FAULT_INJECTION && BLOCK 2056 help 2057 Provide fault-injection capability for disk IO. 2058 2059config FAIL_IO_TIMEOUT 2060 bool "Fault-injection capability for faking disk interrupts" 2061 depends on FAULT_INJECTION && BLOCK 2062 help 2063 Provide fault-injection capability on end IO handling. This 2064 will make the block layer "forget" an interrupt as configured, 2065 thus exercising the error handling. 2066 2067 Only works with drivers that use the generic timeout handling, 2068 for others it won't do anything. 2069 2070config FAIL_FUTEX 2071 bool "Fault-injection capability for futexes" 2072 select DEBUG_FS 2073 depends on FAULT_INJECTION && FUTEX 2074 help 2075 Provide fault-injection capability for futexes. 2076 2077config FAULT_INJECTION_DEBUG_FS 2078 bool "Debugfs entries for fault-injection capabilities" 2079 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 2080 help 2081 Enable configuration of fault-injection capabilities via debugfs. 2082 2083config FAIL_FUNCTION 2084 bool "Fault-injection capability for functions" 2085 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 2086 help 2087 Provide function-based fault-injection capability. 2088 This will allow you to override a specific function with a return 2089 with given return value. As a result, function caller will see 2090 an error value and have to handle it. This is useful to test the 2091 error handling in various subsystems. 2092 2093config FAIL_MMC_REQUEST 2094 bool "Fault-injection capability for MMC IO" 2095 depends on FAULT_INJECTION_DEBUG_FS && MMC 2096 help 2097 Provide fault-injection capability for MMC IO. 2098 This will make the mmc core return data errors. This is 2099 useful to test the error handling in the mmc block device 2100 and to test how the mmc host driver handles retries from 2101 the block device. 2102 2103config FAIL_SUNRPC 2104 bool "Fault-injection capability for SunRPC" 2105 depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG 2106 help 2107 Provide fault-injection capability for SunRPC and 2108 its consumers. 2109 2110config FAIL_SKB_REALLOC 2111 bool "Fault-injection capability forcing skb to reallocate" 2112 depends on FAULT_INJECTION_DEBUG_FS 2113 help 2114 Provide fault-injection capability that forces the skb to be 2115 reallocated, catching possible invalid pointers to the skb. 2116 2117 For more information, check 2118 Documentation/fault-injection/fault-injection.rst 2119 2120config FAULT_INJECTION_CONFIGFS 2121 bool "Configfs interface for fault-injection capabilities" 2122 depends on FAULT_INJECTION 2123 select CONFIGFS_FS 2124 help 2125 This option allows configfs-based drivers to dynamically configure 2126 fault-injection via configfs. Each parameter for driver-specific 2127 fault-injection can be made visible as a configfs attribute in a 2128 configfs group. 2129 2130 2131config FAULT_INJECTION_STACKTRACE_FILTER 2132 bool "stacktrace filter for fault-injection capabilities" 2133 depends on FAULT_INJECTION 2134 depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT 2135 select STACKTRACE 2136 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 2137 help 2138 Provide stacktrace filter for fault-injection capabilities 2139 2140config ARCH_HAS_KCOV 2141 bool 2142 help 2143 An architecture should select this when it can successfully 2144 build and run with CONFIG_KCOV. This typically requires 2145 disabling instrumentation for some early boot code. 2146 2147config KCOV 2148 bool "Code coverage for fuzzing" 2149 depends on ARCH_HAS_KCOV 2150 depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \ 2151 GCC_VERSION >= 120000 || CC_IS_CLANG 2152 select DEBUG_FS 2153 select OBJTOOL if HAVE_NOINSTR_HACK 2154 help 2155 KCOV exposes kernel code coverage information in a form suitable 2156 for coverage-guided fuzzing (randomized testing). 2157 2158 For more details, see Documentation/dev-tools/kcov.rst. 2159 2160config KCOV_ENABLE_COMPARISONS 2161 bool "Enable comparison operands collection by KCOV" 2162 depends on KCOV 2163 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 2164 help 2165 KCOV also exposes operands of every comparison in the instrumented 2166 code along with operand sizes and PCs of the comparison instructions. 2167 These operands can be used by fuzzing engines to improve the quality 2168 of fuzzing coverage. 2169 2170config KCOV_INSTRUMENT_ALL 2171 bool "Instrument all code by default" 2172 depends on KCOV 2173 default y 2174 help 2175 If you are doing generic system call fuzzing (like e.g. syzkaller), 2176 then you will want to instrument the whole kernel and you should 2177 say y here. If you are doing more targeted fuzzing (like e.g. 2178 filesystem fuzzing with AFL) then you will want to enable coverage 2179 for more specific subsets of files, and should say n here. 2180 2181config KCOV_IRQ_AREA_SIZE 2182 hex "Size of interrupt coverage collection area in words" 2183 depends on KCOV 2184 default 0x40000 2185 help 2186 KCOV uses preallocated per-cpu areas to collect coverage from 2187 soft interrupts. This specifies the size of those areas in the 2188 number of unsigned long words. 2189 2190config KCOV_SELFTEST 2191 bool "Perform short selftests on boot" 2192 depends on KCOV 2193 help 2194 Run short KCOV coverage collection selftests on boot. 2195 On test failure, causes the kernel to panic. Recommended to be 2196 enabled, ensuring critical functionality works as intended. 2197 2198menuconfig RUNTIME_TESTING_MENU 2199 bool "Runtime Testing" 2200 default y 2201 2202if RUNTIME_TESTING_MENU 2203 2204config TEST_DHRY 2205 tristate "Dhrystone benchmark test" 2206 help 2207 Enable this to include the Dhrystone 2.1 benchmark. This test 2208 calculates the number of Dhrystones per second, and the number of 2209 DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided 2210 by 1757 (the number of Dhrystones per second obtained on the VAX 2211 11/780, nominally a 1 MIPS machine). 2212 2213 To run the benchmark, it needs to be enabled explicitly, either from 2214 the kernel command line (when built-in), or from userspace (when 2215 built-in or modular). 2216 2217 Run once during kernel boot: 2218 2219 test_dhry.run 2220 2221 Set number of iterations from kernel command line: 2222 2223 test_dhry.iterations=<n> 2224 2225 Set number of iterations from userspace: 2226 2227 echo <n> > /sys/module/test_dhry/parameters/iterations 2228 2229 Trigger manual run from userspace: 2230 2231 echo y > /sys/module/test_dhry/parameters/run 2232 2233 If the number of iterations is <= 0, the test will devise a suitable 2234 number of iterations (test runs for at least 2s) automatically. 2235 This process takes ca. 4s. 2236 2237 If unsure, say N. 2238 2239config LKDTM 2240 tristate "Linux Kernel Dump Test Tool Module" 2241 depends on DEBUG_FS 2242 help 2243 This module enables testing of the different dumping mechanisms by 2244 inducing system failures at predefined crash points. 2245 If you don't need it: say N 2246 Choose M here to compile this code as a module. The module will be 2247 called lkdtm. 2248 2249 Documentation on how to use the module can be found in 2250 Documentation/fault-injection/provoke-crashes.rst 2251 2252config CPUMASK_KUNIT_TEST 2253 tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS 2254 depends on KUNIT 2255 default KUNIT_ALL_TESTS 2256 help 2257 Enable to turn on cpumask tests, running at boot or module load time. 2258 2259 For more information on KUnit and unit tests in general, please refer 2260 to the KUnit documentation in Documentation/dev-tools/kunit/. 2261 2262 If unsure, say N. 2263 2264config TEST_LIST_SORT 2265 tristate "Linked list sorting test" if !KUNIT_ALL_TESTS 2266 depends on KUNIT 2267 default KUNIT_ALL_TESTS 2268 help 2269 Enable this to turn on 'list_sort()' function test. This test is 2270 executed only once during system boot (so affects only boot time), 2271 or at module load time. 2272 2273 If unsure, say N. 2274 2275config TEST_MIN_HEAP 2276 tristate "Min heap test" 2277 depends on DEBUG_KERNEL || m 2278 help 2279 Enable this to turn on min heap function tests. This test is 2280 executed only once during system boot (so affects only boot time), 2281 or at module load time. 2282 2283 If unsure, say N. 2284 2285config TEST_SORT 2286 tristate "Array-based sort test" if !KUNIT_ALL_TESTS 2287 depends on KUNIT 2288 default KUNIT_ALL_TESTS 2289 help 2290 This option enables the self-test function of 'sort()' at boot, 2291 or at module load time. 2292 2293 If unsure, say N. 2294 2295config TEST_DIV64 2296 tristate "64bit/32bit division and modulo test" 2297 depends on DEBUG_KERNEL || m 2298 help 2299 Enable this to turn on 'do_div()' function test. This test is 2300 executed only once during system boot (so affects only boot time), 2301 or at module load time. 2302 2303 If unsure, say N. 2304 2305config TEST_MULDIV64 2306 tristate "mul_u64_u64_div_u64() test" 2307 depends on DEBUG_KERNEL || m 2308 help 2309 Enable this to turn on 'mul_u64_u64_div_u64()' function test. 2310 This test is executed only once during system boot (so affects 2311 only boot time), or at module load time. 2312 2313 If unsure, say N. 2314 2315config TEST_IOV_ITER 2316 tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS 2317 depends on KUNIT 2318 depends on MMU 2319 default KUNIT_ALL_TESTS 2320 help 2321 Enable this to turn on testing of the operation of the I/O iterator 2322 (iov_iter). This test is executed only once during system boot (so 2323 affects only boot time), or at module load time. 2324 2325 If unsure, say N. 2326 2327config KPROBES_SANITY_TEST 2328 tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS 2329 depends on DEBUG_KERNEL 2330 depends on KPROBES 2331 depends on KUNIT 2332 select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 2333 default KUNIT_ALL_TESTS 2334 help 2335 This option provides for testing basic kprobes functionality on 2336 boot. Samples of kprobe and kretprobe are inserted and 2337 verified for functionality. 2338 2339 Say N if you are unsure. 2340 2341config FPROBE_SANITY_TEST 2342 bool "Self test for fprobe" 2343 depends on DEBUG_KERNEL 2344 depends on FPROBE 2345 depends on KUNIT=y 2346 help 2347 This option will enable testing the fprobe when the system boot. 2348 A series of tests are made to verify that the fprobe is functioning 2349 properly. 2350 2351 Say N if you are unsure. 2352 2353config BACKTRACE_SELF_TEST 2354 tristate "Self test for the backtrace code" 2355 depends on DEBUG_KERNEL 2356 help 2357 This option provides a kernel module that can be used to test 2358 the kernel stack backtrace code. This option is not useful 2359 for distributions or general kernels, but only for kernel 2360 developers working on architecture code. 2361 2362 Note that if you want to also test saved backtraces, you will 2363 have to enable STACKTRACE as well. 2364 2365 Say N if you are unsure. 2366 2367config TEST_REF_TRACKER 2368 tristate "Self test for reference tracker" 2369 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT 2370 select REF_TRACKER 2371 help 2372 This option provides a kernel module performing tests 2373 using reference tracker infrastructure. 2374 2375 Say N if you are unsure. 2376 2377config RBTREE_TEST 2378 tristate "Red-Black tree test" 2379 depends on DEBUG_KERNEL 2380 help 2381 A benchmark measuring the performance of the rbtree library. 2382 Also includes rbtree invariant checks. 2383 2384config REED_SOLOMON_TEST 2385 tristate "Reed-Solomon library test" 2386 depends on DEBUG_KERNEL || m 2387 select REED_SOLOMON 2388 select REED_SOLOMON_ENC16 2389 select REED_SOLOMON_DEC16 2390 help 2391 This option enables the self-test function of rslib at boot, 2392 or at module load time. 2393 2394 If unsure, say N. 2395 2396config INTERVAL_TREE_TEST 2397 tristate "Interval tree test" 2398 depends on DEBUG_KERNEL 2399 select INTERVAL_TREE 2400 help 2401 A benchmark measuring the performance of the interval tree library 2402 2403config PERCPU_TEST 2404 tristate "Per cpu operations test" 2405 depends on m && DEBUG_KERNEL 2406 help 2407 Enable this option to build test module which validates per-cpu 2408 operations. 2409 2410 If unsure, say N. 2411 2412config ATOMIC64_SELFTEST 2413 tristate "Perform an atomic64_t self-test" 2414 help 2415 Enable this option to test the atomic64_t functions at boot or 2416 at module load time. 2417 2418 If unsure, say N. 2419 2420config ASYNC_RAID6_TEST 2421 tristate "Self test for hardware accelerated raid6 recovery" 2422 depends on ASYNC_RAID6_RECOV 2423 select ASYNC_MEMCPY 2424 help 2425 This is a one-shot self test that permutes through the 2426 recovery of all the possible two disk failure scenarios for a 2427 N-disk array. Recovery is performed with the asynchronous 2428 raid6 recovery routines, and will optionally use an offload 2429 engine if one is available. 2430 2431 If unsure, say N. 2432 2433config TEST_HEXDUMP 2434 tristate "Test functions located in the hexdump module at runtime" 2435 2436config PRINTF_KUNIT_TEST 2437 tristate "KUnit test printf() family of functions at runtime" if !KUNIT_ALL_TESTS 2438 depends on KUNIT 2439 default KUNIT_ALL_TESTS 2440 help 2441 Enable this option to test the printf functions at runtime. 2442 2443 If unsure, say N. 2444 2445config SCANF_KUNIT_TEST 2446 tristate "KUnit test scanf() family of functions at runtime" if !KUNIT_ALL_TESTS 2447 depends on KUNIT 2448 default KUNIT_ALL_TESTS 2449 help 2450 Enable this option to test the scanf functions at runtime. 2451 2452 If unsure, say N. 2453 2454config SEQ_BUF_KUNIT_TEST 2455 tristate "KUnit test for seq_buf" if !KUNIT_ALL_TESTS 2456 depends on KUNIT 2457 default KUNIT_ALL_TESTS 2458 help 2459 This builds unit tests for the seq_buf library. 2460 2461 If unsure, say N. 2462 2463config STRING_KUNIT_TEST 2464 tristate "KUnit test string functions at runtime" if !KUNIT_ALL_TESTS 2465 depends on KUNIT 2466 default KUNIT_ALL_TESTS 2467 2468config STRING_HELPERS_KUNIT_TEST 2469 tristate "KUnit test string helpers at runtime" if !KUNIT_ALL_TESTS 2470 depends on KUNIT 2471 default KUNIT_ALL_TESTS 2472 2473config FFS_KUNIT_TEST 2474 tristate "KUnit test ffs-family functions at runtime" if !KUNIT_ALL_TESTS 2475 depends on KUNIT 2476 default KUNIT_ALL_TESTS 2477 help 2478 This builds KUnit tests for ffs-family bit manipulation functions 2479 including ffs(), __ffs(), fls(), __fls(), fls64(), and __ffs64(). 2480 2481 These tests validate mathematical correctness, edge case handling, 2482 and cross-architecture consistency of bit scanning functions. 2483 2484 For more information on KUnit and unit tests in general, 2485 please refer to Documentation/dev-tools/kunit/. 2486 2487config TEST_KSTRTOX 2488 tristate "Test kstrto*() family of functions at runtime" 2489 2490config TEST_BITMAP 2491 tristate "Test bitmap_*() family of functions at runtime" 2492 help 2493 Enable this option to test the bitmap functions at boot. 2494 2495 If unsure, say N. 2496 2497config TEST_UUID 2498 tristate "Test functions located in the uuid module at runtime" 2499 2500config TEST_XARRAY 2501 tristate "Test the XArray code at runtime" 2502 2503config TEST_MAPLE_TREE 2504 tristate "Test the Maple Tree code at runtime or module load" 2505 help 2506 Enable this option to test the maple tree code functions at boot, or 2507 when the module is loaded. Enable "Debug Maple Trees" will enable 2508 more verbose output on failures. 2509 2510 If unsure, say N. 2511 2512config TEST_RHASHTABLE 2513 tristate "Perform selftest on resizable hash table" 2514 help 2515 Enable this option to test the rhashtable functions at boot. 2516 2517 If unsure, say N. 2518 2519config TEST_IDA 2520 tristate "Perform selftest on IDA functions" 2521 2522config TEST_MISC_MINOR 2523 bool "miscdevice KUnit test" if !KUNIT_ALL_TESTS 2524 depends on KUNIT=y 2525 default KUNIT_ALL_TESTS 2526 help 2527 Kunit test for miscdevice API, specially its behavior in respect to 2528 static and dynamic minor numbers. 2529 2530 KUnit tests run during boot and output the results to the debug log 2531 in TAP format (https://testanything.org/). Only useful for kernel devs 2532 running the KUnit test harness, and not intended for inclusion into a 2533 production build. 2534 2535 For more information on KUnit and unit tests in general please refer 2536 to the KUnit documentation in Documentation/dev-tools/kunit/. 2537 2538 If unsure, say N. 2539 2540config TEST_PARMAN 2541 tristate "Perform selftest on priority array manager" 2542 depends on PARMAN 2543 help 2544 Enable this option to test priority array manager on boot 2545 (or module load). 2546 2547 If unsure, say N. 2548 2549config TEST_IRQ_TIMINGS 2550 bool "IRQ timings selftest" 2551 depends on IRQ_TIMINGS 2552 help 2553 Enable this option to test the irq timings code on boot. 2554 2555 If unsure, say N. 2556 2557config TEST_LKM 2558 tristate "Test module loading with 'hello world' module" 2559 depends on m 2560 help 2561 This builds the "test_module" module that emits "Hello, world" 2562 on printk when loaded. It is designed to be used for basic 2563 evaluation of the module loading subsystem (for example when 2564 validating module verification). It lacks any extra dependencies, 2565 and will not normally be loaded by the system unless explicitly 2566 requested by name. 2567 2568 If unsure, say N. 2569 2570config TEST_BITOPS 2571 tristate "Test module for compilation of bitops operations" 2572 help 2573 This builds the "test_bitops" module that is much like the 2574 TEST_LKM module except that it does a basic exercise of the 2575 set/clear_bit macros and get_count_order/long to make sure there are 2576 no compiler warnings from C=1 sparse checker or -Wextra 2577 compilations. It has no dependencies and doesn't run or load unless 2578 explicitly requested by name. for example: modprobe test_bitops. 2579 2580 If unsure, say N. 2581 2582config TEST_VMALLOC 2583 tristate "Test module for stress/performance analysis of vmalloc allocator" 2584 default n 2585 depends on MMU 2586 help 2587 This builds the "test_vmalloc" module that should be used for 2588 stress and performance analysis. So, any new change for vmalloc 2589 subsystem can be evaluated from performance and stability point 2590 of view. 2591 2592 If unsure, say N. 2593 2594config TEST_BPF 2595 tristate "Test BPF filter functionality" 2596 depends on m && NET 2597 help 2598 This builds the "test_bpf" module that runs various test vectors 2599 against the BPF interpreter or BPF JIT compiler depending on the 2600 current setting. This is in particular useful for BPF JIT compiler 2601 development, but also to run regression tests against changes in 2602 the interpreter code. It also enables test stubs for eBPF maps and 2603 verifier used by user space verifier testsuite. 2604 2605 If unsure, say N. 2606 2607config FIND_BIT_BENCHMARK 2608 tristate "Test find_bit functions" 2609 help 2610 This builds the "test_find_bit" module that measure find_*_bit() 2611 functions performance. 2612 2613 If unsure, say N. 2614 2615config FIND_BIT_BENCHMARK_RUST 2616 tristate "Test find_bit functions in Rust" 2617 depends on RUST 2618 help 2619 This builds the "find_bit_benchmark_rust" module. It is a micro 2620 benchmark that measures the performance of Rust functions that 2621 correspond to the find_*_bit() operations in C. It follows the 2622 FIND_BIT_BENCHMARK closely but will in general not yield same 2623 numbers due to extra bounds checks and overhead of foreign 2624 function calls. 2625 2626 If unsure, say N. 2627 2628config TEST_FIRMWARE 2629 tristate "Test firmware loading via userspace interface" 2630 depends on FW_LOADER 2631 help 2632 This builds the "test_firmware" module that creates a userspace 2633 interface for testing firmware loading. This can be used to 2634 control the triggering of firmware loading without needing an 2635 actual firmware-using device. The contents can be rechecked by 2636 userspace. 2637 2638 If unsure, say N. 2639 2640config TEST_SYSCTL 2641 tristate "sysctl test driver" 2642 depends on PROC_SYSCTL 2643 help 2644 This builds the "test_sysctl" module. This driver enables to test the 2645 proc sysctl interfaces available to drivers safely without affecting 2646 production knobs which might alter system functionality. 2647 2648 If unsure, say N. 2649 2650config BITOPS_KUNIT 2651 tristate "KUnit test for bitops" if !KUNIT_ALL_TESTS 2652 depends on KUNIT 2653 default KUNIT_ALL_TESTS 2654 help 2655 This option enables the KUnit test for the bitops library 2656 which provides functions for bit operations. 2657 2658 Note that this is derived from the original test_bitops module. 2659 For micro-benchmarks and compiler warning checks, enable TEST_BITOPS. 2660 2661 If unsure, say N. 2662 2663config BITFIELD_KUNIT 2664 tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS 2665 depends on KUNIT 2666 default KUNIT_ALL_TESTS 2667 help 2668 Enable this option to test the bitfield functions at boot. 2669 2670 KUnit tests run during boot and output the results to the debug log 2671 in TAP format (http://testanything.org/). Only useful for kernel devs 2672 running the KUnit test harness, and not intended for inclusion into a 2673 production build. 2674 2675 For more information on KUnit and unit tests in general please refer 2676 to the KUnit documentation in Documentation/dev-tools/kunit/. 2677 2678 If unsure, say N. 2679 2680config CHECKSUM_KUNIT 2681 tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS 2682 depends on KUNIT 2683 default KUNIT_ALL_TESTS 2684 help 2685 Enable this option to test the checksum functions at boot. 2686 2687 KUnit tests run during boot and output the results to the debug log 2688 in TAP format (http://testanything.org/). Only useful for kernel devs 2689 running the KUnit test harness, and not intended for inclusion into a 2690 production build. 2691 2692 For more information on KUnit and unit tests in general please refer 2693 to the KUnit documentation in Documentation/dev-tools/kunit/. 2694 2695 If unsure, say N. 2696 2697config UTIL_MACROS_KUNIT 2698 tristate "KUnit test util_macros.h functions at runtime" if !KUNIT_ALL_TESTS 2699 depends on KUNIT 2700 default KUNIT_ALL_TESTS 2701 help 2702 Enable this option to test the util_macros.h function at boot. 2703 2704 KUnit tests run during boot and output the results to the debug log 2705 in TAP format (http://testanything.org/). Only useful for kernel devs 2706 running the KUnit test harness, and not intended for inclusion into a 2707 production build. 2708 2709 For more information on KUnit and unit tests in general please refer 2710 to the KUnit documentation in Documentation/dev-tools/kunit/. 2711 2712 If unsure, say N. 2713 2714config HASH_KUNIT_TEST 2715 tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS 2716 depends on KUNIT 2717 default KUNIT_ALL_TESTS 2718 help 2719 Enable this option to test the kernel's string (<linux/stringhash.h>), and 2720 integer (<linux/hash.h>) hash functions on boot. 2721 2722 KUnit tests run during boot and output the results to the debug log 2723 in TAP format (https://testanything.org/). Only useful for kernel devs 2724 running the KUnit test harness, and not intended for inclusion into a 2725 production build. 2726 2727 For more information on KUnit and unit tests in general please refer 2728 to the KUnit documentation in Documentation/dev-tools/kunit/. 2729 2730 This is intended to help people writing architecture-specific 2731 optimized versions. If unsure, say N. 2732 2733config RESOURCE_KUNIT_TEST 2734 tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS 2735 depends on KUNIT 2736 default KUNIT_ALL_TESTS 2737 select GET_FREE_REGION 2738 help 2739 This builds the resource API unit test. 2740 Tests the logic of API provided by resource.c and ioport.h. 2741 For more information on KUnit and unit tests in general please refer 2742 to the KUnit documentation in Documentation/dev-tools/kunit/. 2743 2744 If unsure, say N. 2745 2746config SYSCTL_KUNIT_TEST 2747 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS 2748 depends on KUNIT 2749 default KUNIT_ALL_TESTS 2750 help 2751 This builds the proc sysctl unit test, which runs on boot. 2752 Tests the API contract and implementation correctness of sysctl. 2753 For more information on KUnit and unit tests in general please refer 2754 to the KUnit documentation in Documentation/dev-tools/kunit/. 2755 2756 If unsure, say N. 2757 2758config KFIFO_KUNIT_TEST 2759 tristate "KUnit Test for the generic kernel FIFO implementation" if !KUNIT_ALL_TESTS 2760 depends on KUNIT 2761 default KUNIT_ALL_TESTS 2762 help 2763 This builds the generic FIFO implementation KUnit test suite. 2764 It tests that the API and basic functionality of the kfifo type 2765 and associated macros. 2766 2767 For more information on KUnit and unit tests in general please refer 2768 to the KUnit documentation in Documentation/dev-tools/kunit/. 2769 2770 If unsure, say N. 2771 2772config LIST_KUNIT_TEST 2773 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS 2774 depends on KUNIT 2775 default KUNIT_ALL_TESTS 2776 help 2777 This builds the linked list KUnit test suite. 2778 It tests that the API and basic functionality of the list_head type 2779 and associated macros. 2780 2781 KUnit tests run during boot and output the results to the debug log 2782 in TAP format (https://testanything.org/). Only useful for kernel devs 2783 running the KUnit test harness, and not intended for inclusion into a 2784 production build. 2785 2786 For more information on KUnit and unit tests in general please refer 2787 to the KUnit documentation in Documentation/dev-tools/kunit/. 2788 2789 If unsure, say N. 2790 2791config HASHTABLE_KUNIT_TEST 2792 tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS 2793 depends on KUNIT 2794 default KUNIT_ALL_TESTS 2795 help 2796 This builds the hashtable KUnit test suite. 2797 It tests the basic functionality of the API defined in 2798 include/linux/hashtable.h. For more information on KUnit and 2799 unit tests in general please refer to the KUnit documentation 2800 in Documentation/dev-tools/kunit/. 2801 2802 If unsure, say N. 2803 2804config LINEAR_RANGES_TEST 2805 tristate "KUnit test for linear_ranges" 2806 depends on KUNIT 2807 select LINEAR_RANGES 2808 help 2809 This builds the linear_ranges unit test, which runs on boot. 2810 Tests the linear_ranges logic correctness. 2811 For more information on KUnit and unit tests in general please refer 2812 to the KUnit documentation in Documentation/dev-tools/kunit/. 2813 2814 If unsure, say N. 2815 2816config CMDLINE_KUNIT_TEST 2817 tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS 2818 depends on KUNIT 2819 default KUNIT_ALL_TESTS 2820 help 2821 This builds the cmdline API unit test. 2822 Tests the logic of API provided by cmdline.c. 2823 For more information on KUnit and unit tests in general please refer 2824 to the KUnit documentation in Documentation/dev-tools/kunit/. 2825 2826 If unsure, say N. 2827 2828config BASE64_KUNIT 2829 tristate "KUnit test for base64 decoding and encoding" if !KUNIT_ALL_TESTS 2830 depends on KUNIT 2831 default KUNIT_ALL_TESTS 2832 help 2833 This builds the base64 unit tests. 2834 2835 The tests cover the encoding and decoding logic of Base64 functions 2836 in the kernel. 2837 In addition to correctness checks, simple performance benchmarks 2838 for both encoding and decoding are also included. 2839 2840 For more information on KUnit and unit tests in general please refer 2841 to the KUnit documentation in Documentation/dev-tools/kunit/. 2842 2843 If unsure, say N. 2844 2845config BITS_TEST 2846 tristate "KUnit test for bit functions and macros" if !KUNIT_ALL_TESTS 2847 depends on KUNIT 2848 default KUNIT_ALL_TESTS 2849 help 2850 This builds the bits unit test. 2851 Tests the logic of macros defined in bits.h. 2852 For more information on KUnit and unit tests in general please refer 2853 to the KUnit documentation in Documentation/dev-tools/kunit/. 2854 2855 If unsure, say N. 2856 2857config SLUB_KUNIT_TEST 2858 tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS 2859 depends on SLUB_DEBUG && KUNIT 2860 default KUNIT_ALL_TESTS 2861 help 2862 This builds SLUB allocator unit test. 2863 Tests SLUB cache debugging functionality. 2864 For more information on KUnit and unit tests in general please refer 2865 to the KUnit documentation in Documentation/dev-tools/kunit/. 2866 2867 If unsure, say N. 2868 2869config RATIONAL_KUNIT_TEST 2870 tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS 2871 depends on KUNIT && RATIONAL 2872 default KUNIT_ALL_TESTS 2873 help 2874 This builds the rational math unit test. 2875 For more information on KUnit and unit tests in general please refer 2876 to the KUnit documentation in Documentation/dev-tools/kunit/. 2877 2878 If unsure, say N. 2879 2880config MEMCPY_KUNIT_TEST 2881 tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS 2882 depends on KUNIT 2883 default KUNIT_ALL_TESTS 2884 help 2885 Builds unit tests for memcpy(), memmove(), and memset() functions. 2886 For more information on KUnit and unit tests in general please refer 2887 to the KUnit documentation in Documentation/dev-tools/kunit/. 2888 2889 If unsure, say N. 2890 2891config IS_SIGNED_TYPE_KUNIT_TEST 2892 tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS 2893 depends on KUNIT 2894 default KUNIT_ALL_TESTS 2895 help 2896 Builds unit tests for the is_signed_type() macro. 2897 2898 For more information on KUnit and unit tests in general please refer 2899 to the KUnit documentation in Documentation/dev-tools/kunit/. 2900 2901 If unsure, say N. 2902 2903config OVERFLOW_KUNIT_TEST 2904 tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS 2905 depends on KUNIT 2906 default KUNIT_ALL_TESTS 2907 help 2908 Builds unit tests for the check_*_overflow(), size_*(), allocation, and 2909 related functions. 2910 2911 For more information on KUnit and unit tests in general please refer 2912 to the KUnit documentation in Documentation/dev-tools/kunit/. 2913 2914 If unsure, say N. 2915 2916config RANDSTRUCT_KUNIT_TEST 2917 tristate "Test randstruct structure layout randomization at runtime" if !KUNIT_ALL_TESTS 2918 depends on KUNIT 2919 default KUNIT_ALL_TESTS 2920 help 2921 Builds unit tests for the checking CONFIG_RANDSTRUCT=y, which 2922 randomizes structure layouts. 2923 2924config STACKINIT_KUNIT_TEST 2925 tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS 2926 depends on KUNIT 2927 default KUNIT_ALL_TESTS 2928 help 2929 Test if the kernel is zero-initializing stack variables and 2930 padding. Coverage is controlled by compiler flags, 2931 CONFIG_INIT_STACK_ALL_PATTERN or CONFIG_INIT_STACK_ALL_ZERO. 2932 2933config FORTIFY_KUNIT_TEST 2934 tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS 2935 depends on KUNIT 2936 default KUNIT_ALL_TESTS 2937 help 2938 Builds unit tests for checking internals of FORTIFY_SOURCE as used 2939 by the str*() and mem*() family of functions. For testing runtime 2940 traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests. 2941 2942config LONGEST_SYM_KUNIT_TEST 2943 tristate "Test the longest symbol possible" if !KUNIT_ALL_TESTS 2944 depends on KUNIT && KPROBES 2945 depends on !PREFIX_SYMBOLS && !CFI && !GCOV_KERNEL 2946 default KUNIT_ALL_TESTS 2947 help 2948 Tests the longest symbol possible 2949 2950 If unsure, say N. 2951 2952config HW_BREAKPOINT_KUNIT_TEST 2953 bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS 2954 depends on HAVE_HW_BREAKPOINT 2955 depends on KUNIT=y 2956 default KUNIT_ALL_TESTS 2957 help 2958 Tests for hw_breakpoint constraints accounting. 2959 2960 If unsure, say N. 2961 2962config SIPHASH_KUNIT_TEST 2963 tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS 2964 depends on KUNIT 2965 default KUNIT_ALL_TESTS 2966 help 2967 Enable this option to test the kernel's siphash (<linux/siphash.h>) hash 2968 functions on boot (or module load). 2969 2970 This is intended to help people writing architecture-specific 2971 optimized versions. If unsure, say N. 2972 2973config USERCOPY_KUNIT_TEST 2974 tristate "KUnit Test for user/kernel boundary protections" 2975 depends on KUNIT 2976 default KUNIT_ALL_TESTS 2977 help 2978 This builds the "usercopy_kunit" module that runs sanity checks 2979 on the copy_to/from_user infrastructure, making sure basic 2980 user/kernel boundary testing is working. 2981 2982config BLACKHOLE_DEV_KUNIT_TEST 2983 tristate "Test blackhole netdev functionality" if !KUNIT_ALL_TESTS 2984 depends on NET 2985 depends on KUNIT 2986 default KUNIT_ALL_TESTS 2987 help 2988 This builds the "blackhole_dev_kunit" module that validates the 2989 data path through this blackhole netdev. 2990 2991 If unsure, say N. 2992 2993config TEST_UDELAY 2994 tristate "udelay test driver" 2995 help 2996 This builds the "udelay_test" module that helps to make sure 2997 that udelay() is working properly. 2998 2999 If unsure, say N. 3000 3001config TEST_STATIC_KEYS 3002 tristate "Test static keys" 3003 depends on m 3004 help 3005 Test the static key interfaces. 3006 3007 If unsure, say N. 3008 3009config TEST_DYNAMIC_DEBUG 3010 tristate "Test DYNAMIC_DEBUG" 3011 depends on DYNAMIC_DEBUG 3012 help 3013 This module registers a tracer callback to count enabled 3014 pr_debugs in a 'do_debugging' function, then alters their 3015 enablements, calls the function, and compares counts. 3016 3017 If unsure, say N. 3018 3019config TEST_KMOD 3020 tristate "kmod stress tester" 3021 depends on m 3022 select TEST_LKM 3023 help 3024 Test the kernel's module loading mechanism: kmod. kmod implements 3025 support to load modules using the Linux kernel's usermode helper. 3026 This test provides a series of tests against kmod. 3027 3028 Although technically you can either build test_kmod as a module or 3029 into the kernel we disallow building it into the kernel since 3030 it stress tests request_module() and this will very likely cause 3031 some issues by taking over precious threads available from other 3032 module load requests, ultimately this could be fatal. 3033 3034 To run tests run: 3035 3036 tools/testing/selftests/kmod/kmod.sh --help 3037 3038 If unsure, say N. 3039 3040config TEST_RUNTIME 3041 bool 3042 3043config TEST_RUNTIME_MODULE 3044 bool 3045 3046config TEST_KALLSYMS 3047 tristate "module kallsyms find_symbol() test" 3048 depends on m 3049 select TEST_RUNTIME 3050 select TEST_RUNTIME_MODULE 3051 select TEST_KALLSYMS_A 3052 select TEST_KALLSYMS_B 3053 select TEST_KALLSYMS_C 3054 select TEST_KALLSYMS_D 3055 help 3056 This allows us to stress test find_symbol() through the kallsyms 3057 used to place symbols on the kernel ELF kallsyms and modules kallsyms 3058 where we place kernel symbols such as exported symbols. 3059 3060 We have four test modules: 3061 3062 A: has KALLSYSMS_NUMSYMS exported symbols 3063 B: uses one of A's symbols 3064 C: adds KALLSYMS_SCALE_FACTOR * KALLSYSMS_NUMSYMS exported 3065 D: adds 2 * the symbols than C 3066 3067 We stress test find_symbol() through two means: 3068 3069 1) Upon load of B it will trigger simplify_symbols() to look for the 3070 one symbol it uses from the module A with tons of symbols. This is an 3071 indirect way for us to have B call resolve_symbol_wait() upon module 3072 load. This will eventually call find_symbol() which will eventually 3073 try to find the symbols used with find_exported_symbol_in_section(). 3074 find_exported_symbol_in_section() uses bsearch() so a binary search 3075 for each symbol. Binary search will at worst be O(log(n)) so the 3076 larger TEST_MODULE_KALLSYSMS the worse the search. 3077 3078 2) The selftests should load C first, before B. Upon B's load towards 3079 the end right before we call module B's init routine we get 3080 complete_formation() called on the module. That will first check 3081 for duplicate symbols with the call to verify_exported_symbols(). 3082 That is when we'll force iteration on module C's insane symbol list. 3083 Since it has 10 * KALLSYMS_NUMSYMS it means we can first test 3084 just loading B without C. The amount of time it takes to load C Vs 3085 B can give us an idea of the impact growth of the symbol space and 3086 give us projection. Module A only uses one symbol from B so to allow 3087 this scaling in module C to be proportional, if it used more symbols 3088 then the first test would be doing more and increasing just the 3089 search space would be slightly different. The last module, module D 3090 will just increase the search space by twice the number of symbols in 3091 C so to allow for full projects. 3092 3093 tools/testing/selftests/module/find_symbol.sh 3094 3095 The current defaults will incur a build delay of about 7 minutes 3096 on an x86_64 with only 8 cores. Enable this only if you want to 3097 stress test find_symbol() with thousands of symbols. At the same 3098 time this is also useful to test building modules with thousands of 3099 symbols, and if BTF is enabled this also stress tests adding BTF 3100 information for each module. Currently enabling many more symbols 3101 will segfault the build system. 3102 3103 If unsure, say N. 3104 3105if TEST_KALLSYMS 3106 3107config TEST_KALLSYMS_A 3108 tristate 3109 depends on m 3110 3111config TEST_KALLSYMS_B 3112 tristate 3113 depends on m 3114 3115config TEST_KALLSYMS_C 3116 tristate 3117 depends on m 3118 3119config TEST_KALLSYMS_D 3120 tristate 3121 depends on m 3122 3123choice 3124 prompt "Kallsym test range" 3125 default TEST_KALLSYMS_LARGE 3126 help 3127 Selecting something other than "Fast" will enable tests which slow 3128 down the build and may crash your build. 3129 3130config TEST_KALLSYMS_FAST 3131 bool "Fast builds" 3132 help 3133 You won't really be testing kallsysms, so this just helps fast builds 3134 when allmodconfig is used.. 3135 3136config TEST_KALLSYMS_LARGE 3137 bool "Enable testing kallsyms with large exports" 3138 help 3139 This will enable larger number of symbols. This will slow down 3140 your build considerably. 3141 3142config TEST_KALLSYMS_MAX 3143 bool "Known kallsysms limits" 3144 help 3145 This will enable exports to the point we know we'll start crashing 3146 builds. 3147 3148endchoice 3149 3150config TEST_KALLSYMS_NUMSYMS 3151 int "test kallsyms number of symbols" 3152 range 2 10000 3153 default 2 if TEST_KALLSYMS_FAST 3154 default 100 if TEST_KALLSYMS_LARGE 3155 default 10000 if TEST_KALLSYMS_MAX 3156 help 3157 The number of symbols to create on TEST_KALLSYMS_A, only one of which 3158 module TEST_KALLSYMS_B will use. This also will be used 3159 for how many symbols TEST_KALLSYMS_C will have, scaled up by 3160 TEST_KALLSYMS_SCALE_FACTOR. Note that setting this to 10,000 will 3161 trigger a segfault today, don't use anything close to it unless 3162 you are aware that this should not be used for automated build tests. 3163 3164config TEST_KALLSYMS_SCALE_FACTOR 3165 int "test kallsyms scale factor" 3166 default 8 3167 help 3168 How many more unusued symbols will TEST_KALLSYSMS_C have than 3169 TEST_KALLSYMS_A. If 8, then module C will have 8 * syms 3170 than module A. Then TEST_KALLSYMS_D will have double the amount 3171 of symbols than C so to allow projections. 3172 3173endif # TEST_KALLSYMS 3174 3175config TEST_DEBUG_VIRTUAL 3176 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 3177 depends on DEBUG_VIRTUAL 3178 help 3179 Test the kernel's ability to detect incorrect calls to 3180 virt_to_phys() done against the non-linear part of the 3181 kernel's virtual address map. 3182 3183 If unsure, say N. 3184 3185config TEST_MEMCAT_P 3186 tristate "Test memcat_p() helper function" 3187 help 3188 Test the memcat_p() helper for correctly merging two 3189 pointer arrays together. 3190 3191 If unsure, say N. 3192 3193config TEST_OBJAGG 3194 tristate "Perform selftest on object aggreration manager" 3195 default n 3196 depends on OBJAGG 3197 help 3198 Enable this option to test object aggregation manager on boot 3199 (or module load). 3200 3201config TEST_MEMINIT 3202 tristate "Test heap/page initialization" 3203 help 3204 Test if the kernel is zero-initializing heap and page allocations. 3205 This can be useful to test init_on_alloc and init_on_free features. 3206 3207 If unsure, say N. 3208 3209config TEST_HMM 3210 tristate "Test HMM (Heterogeneous Memory Management)" 3211 depends on TRANSPARENT_HUGEPAGE 3212 depends on DEVICE_PRIVATE 3213 select HMM_MIRROR 3214 select MMU_NOTIFIER 3215 help 3216 This is a pseudo device driver solely for testing HMM. 3217 Say M here if you want to build the HMM test module. 3218 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests. 3219 3220 If unsure, say N. 3221 3222config TEST_FREE_PAGES 3223 tristate "Test freeing pages" 3224 help 3225 Test that a memory leak does not occur due to a race between 3226 freeing a block of pages and a speculative page reference. 3227 Loading this module is safe if your kernel has the bug fixed. 3228 If the bug is not fixed, it will leak gigabytes of memory and 3229 probably OOM your system. 3230 3231config TEST_FPU 3232 tristate "Test floating point operations in kernel space" 3233 depends on ARCH_HAS_KERNEL_FPU_SUPPORT && !KCOV_INSTRUMENT_ALL 3234 help 3235 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu 3236 which will trigger a sequence of floating point operations. This is used 3237 for self-testing floating point control register setting in 3238 kernel_fpu_begin(). 3239 3240 If unsure, say N. 3241 3242config TEST_CLOCKSOURCE_WATCHDOG 3243 tristate "Test clocksource watchdog in kernel space" 3244 depends on CLOCKSOURCE_WATCHDOG 3245 help 3246 Enable this option to create a kernel module that will trigger 3247 a test of the clocksource watchdog. This module may be loaded 3248 via modprobe or insmod in which case it will run upon being 3249 loaded, or it may be built in, in which case it will run 3250 shortly after boot. 3251 3252 If unsure, say N. 3253 3254config TEST_OBJPOOL 3255 tristate "Test module for correctness and stress of objpool" 3256 default n 3257 depends on m && DEBUG_KERNEL 3258 help 3259 This builds the "test_objpool" module that should be used for 3260 correctness verification and concurrent testings of objects 3261 allocation and reclamation. 3262 3263 If unsure, say N. 3264 3265config TEST_KEXEC_HANDOVER 3266 bool "Test for Kexec HandOver" 3267 default n 3268 depends on KEXEC_HANDOVER 3269 help 3270 This option enables test for Kexec HandOver (KHO). 3271 The test consists of two parts: saving kernel data before kexec and 3272 restoring the data after kexec and verifying that it was properly 3273 handed over. This test module creates and saves data on the boot of 3274 the first kernel and restores and verifies the data on the boot of 3275 kexec'ed kernel. 3276 3277 For detailed documentation about KHO, see Documentation/core-api/kho. 3278 3279 To run the test run: 3280 3281 tools/testing/selftests/kho/vmtest.sh -h 3282 3283 If unsure, say N. 3284 3285config RATELIMIT_KUNIT_TEST 3286 tristate "KUnit Test for correctness and stress of ratelimit" if !KUNIT_ALL_TESTS 3287 depends on KUNIT 3288 default KUNIT_ALL_TESTS 3289 help 3290 This builds the "test_ratelimit" module that should be used 3291 for correctness verification and concurrent testings of rate 3292 limiting. 3293 3294 If unsure, say N. 3295 3296config INT_POW_KUNIT_TEST 3297 tristate "Integer exponentiation (int_pow) test" if !KUNIT_ALL_TESTS 3298 depends on KUNIT 3299 default KUNIT_ALL_TESTS 3300 help 3301 This option enables the KUnit test suite for the int_pow function, 3302 which performs integer exponentiation. The test suite is designed to 3303 verify that the implementation of int_pow correctly computes the power 3304 of a given base raised to a given exponent. 3305 3306 Enabling this option will include tests that check various scenarios 3307 and edge cases to ensure the accuracy and reliability of the exponentiation 3308 function. 3309 3310 If unsure, say N 3311 3312config INT_SQRT_KUNIT_TEST 3313 tristate "Integer square root test" if !KUNIT_ALL_TESTS 3314 depends on KUNIT 3315 default KUNIT_ALL_TESTS 3316 help 3317 This option enables the KUnit test suite for the int_sqrt() function, 3318 which performs square root calculation. The test suite checks 3319 various scenarios, including edge cases, to ensure correctness. 3320 3321 Enabling this option will include tests that check various scenarios 3322 and edge cases to ensure the accuracy and reliability of the square root 3323 function. 3324 3325 If unsure, say N 3326 3327config INT_LOG_KUNIT_TEST 3328 tristate "Integer log (int_log) test" if !KUNIT_ALL_TESTS 3329 depends on KUNIT 3330 default KUNIT_ALL_TESTS 3331 help 3332 This option enables the KUnit test suite for the int_log library, which 3333 provides two functions to compute the integer logarithm in base 2 and 3334 base 10, called respectively as intlog2 and intlog10. 3335 3336 If unsure, say N 3337 3338config GCD_KUNIT_TEST 3339 tristate "Greatest common divisor test" if !KUNIT_ALL_TESTS 3340 depends on KUNIT 3341 default KUNIT_ALL_TESTS 3342 help 3343 This option enables the KUnit test suite for the gcd() function, 3344 which computes the greatest common divisor of two numbers. 3345 3346 This test suite verifies the correctness of gcd() across various 3347 scenarios, including edge cases. 3348 3349 If unsure, say N 3350 3351config PRIME_NUMBERS_KUNIT_TEST 3352 tristate "Prime number generator test" if !KUNIT_ALL_TESTS 3353 depends on KUNIT 3354 depends on PRIME_NUMBERS 3355 default KUNIT_ALL_TESTS 3356 help 3357 This option enables the KUnit test suite for the {is,next}_prime_number 3358 functions. 3359 3360 Enabling this option will include tests that compare the prime number 3361 generator functions against a brute force implementation. 3362 3363 If unsure, say N 3364 3365endif # RUNTIME_TESTING_MENU 3366 3367config ARCH_USE_MEMTEST 3368 bool 3369 help 3370 An architecture should select this when it uses early_memtest() 3371 during boot process. 3372 3373config MEMTEST 3374 bool "Memtest" 3375 depends on ARCH_USE_MEMTEST 3376 help 3377 This option adds a kernel parameter 'memtest', which allows memtest 3378 to be set and executed. 3379 memtest=0, mean disabled; -- default 3380 memtest=1, mean do 1 test pattern; 3381 ... 3382 memtest=17, mean do 17 test patterns. 3383 If you are unsure how to answer this question, answer N. 3384 3385 3386 3387config HYPERV_TESTING 3388 bool "Microsoft Hyper-V driver testing" 3389 default n 3390 depends on HYPERV && DEBUG_FS 3391 help 3392 Select this option to enable Hyper-V vmbus testing. 3393 3394endmenu # "Kernel Testing and Coverage" 3395 3396menu "Rust hacking" 3397 3398config RUST_DEBUG_ASSERTIONS 3399 bool "Debug assertions" 3400 depends on RUST 3401 help 3402 Enables rustc's `-Cdebug-assertions` codegen option. 3403 3404 This flag lets you turn `cfg(debug_assertions)` conditional 3405 compilation on or off. This can be used to enable extra debugging 3406 code in development but not in production. For example, it controls 3407 the behavior of the standard library's `debug_assert!` macro. 3408 3409 Note that this will apply to all Rust code, including `core`. 3410 3411 If unsure, say N. 3412 3413config RUST_OVERFLOW_CHECKS 3414 bool "Overflow checks" 3415 default y 3416 depends on RUST 3417 help 3418 Enables rustc's `-Coverflow-checks` codegen option. 3419 3420 This flag allows you to control the behavior of runtime integer 3421 overflow. When overflow-checks are enabled, a Rust panic will occur 3422 on overflow. 3423 3424 Note that this will apply to all Rust code, including `core`. 3425 3426 If unsure, say Y. 3427 3428config RUST_BUILD_ASSERT_ALLOW 3429 bool "Allow unoptimized build-time assertions" 3430 depends on RUST 3431 help 3432 Controls how `build_error!` and `build_assert!` are handled during the build. 3433 3434 If calls to them exist in the binary, it may indicate a violated invariant 3435 or that the optimizer failed to verify the invariant during compilation. 3436 3437 This should not happen, thus by default the build is aborted. However, 3438 as an escape hatch, you can choose Y here to ignore them during build 3439 and let the check be carried at runtime (with `panic!` being called if 3440 the check fails). 3441 3442 If unsure, say N. 3443 3444config RUST_KERNEL_DOCTESTS 3445 bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS 3446 depends on RUST && KUNIT=y 3447 default KUNIT_ALL_TESTS 3448 help 3449 This builds the documentation tests of the `kernel` crate 3450 as KUnit tests. 3451 3452 For more information on KUnit and unit tests in general, 3453 please refer to the KUnit documentation in Documentation/dev-tools/kunit/. 3454 3455 If unsure, say N. 3456 3457endmenu # "Rust" 3458 3459endmenu # Kernel hacking 3460