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