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 209endmenu # "printk and dmesg options" 210 211config DEBUG_KERNEL 212 bool "Kernel debugging" 213 help 214 Say Y here if you are developing drivers or trying to debug and 215 identify kernel problems. 216 217config DEBUG_MISC 218 bool "Miscellaneous debug code" 219 default DEBUG_KERNEL 220 depends on DEBUG_KERNEL 221 help 222 Say Y here if you need to enable miscellaneous debug code that should 223 be under a more specific debug option but isn't. 224 225menu "Compile-time checks and compiler options" 226 227config DEBUG_INFO 228 bool 229 help 230 A kernel debug info option other than "None" has been selected 231 in the "Debug information" choice below, indicating that debug 232 information will be generated for build targets. 233 234# Clang generates .uleb128 with label differences for DWARF v5, a feature that 235# older binutils ports do not support when utilizing RISC-V style linker 236# relaxation: https://sourceware.org/bugzilla/show_bug.cgi?id=27215 237config AS_HAS_NON_CONST_ULEB128 238 def_bool $(as-instr,.uleb128 .Lexpr_end4 - .Lexpr_start3\n.Lexpr_start3:\n.Lexpr_end4:) 239 240choice 241 prompt "Debug information" 242 depends on DEBUG_KERNEL 243 help 244 Selecting something other than "None" results in a kernel image 245 that will include debugging info resulting in a larger kernel image. 246 This adds debug symbols to the kernel and modules (gcc -g), and 247 is needed if you intend to use kernel crashdump or binary object 248 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 249 250 Choose which version of DWARF debug info to emit. If unsure, 251 select "Toolchain default". 252 253config DEBUG_INFO_NONE 254 bool "Disable debug information" 255 help 256 Do not build the kernel with debugging information, which will 257 result in a faster and smaller build. 258 259config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT 260 bool "Rely on the toolchain's implicit default DWARF version" 261 select DEBUG_INFO 262 depends on !CC_IS_CLANG || AS_IS_LLVM || CLANG_VERSION < 140000 || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128) 263 help 264 The implicit default version of DWARF debug info produced by a 265 toolchain changes over time. 266 267 This can break consumers of the debug info that haven't upgraded to 268 support newer revisions, and prevent testing newer versions, but 269 those should be less common scenarios. 270 271config DEBUG_INFO_DWARF4 272 bool "Generate DWARF Version 4 debuginfo" 273 select DEBUG_INFO 274 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502) 275 help 276 Generate DWARF v4 debug info. This requires gcc 4.5+, binutils 2.35.2 277 if using clang without clang's integrated assembler, and gdb 7.0+. 278 279 If you have consumers of DWARF debug info that are not ready for 280 newer revisions of DWARF, you may wish to choose this or have your 281 config select this. 282 283config DEBUG_INFO_DWARF5 284 bool "Generate DWARF Version 5 debuginfo" 285 select DEBUG_INFO 286 depends on !ARCH_HAS_BROKEN_DWARF5 287 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128) 288 help 289 Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc 290 5.0+ accepts the -gdwarf-5 flag but only had partial support for some 291 draft features until 7.0), and gdb 8.0+. 292 293 Changes to the structure of debug info in Version 5 allow for around 294 15-18% savings in resulting image and debug info section sizes as 295 compared to DWARF Version 4. DWARF Version 5 standardizes previous 296 extensions such as accelerators for symbol indexing and the format 297 for fission (.dwo/.dwp) files. Users may not want to select this 298 config if they rely on tooling that has not yet been updated to 299 support DWARF Version 5. 300 301endchoice # "Debug information" 302 303if DEBUG_INFO 304 305config DEBUG_INFO_REDUCED 306 bool "Reduce debugging information" 307 help 308 If you say Y here gcc is instructed to generate less debugging 309 information for structure types. This means that tools that 310 need full debugging information (like kgdb or systemtap) won't 311 be happy. But if you merely need debugging information to 312 resolve line numbers there is no loss. Advantage is that 313 build directory object sizes shrink dramatically over a full 314 DEBUG_INFO build and compile times are reduced too. 315 Only works with newer gcc versions. 316 317choice 318 prompt "Compressed Debug information" 319 help 320 Compress the resulting debug info. Results in smaller debug info sections, 321 but requires that consumers are able to decompress the results. 322 323 If unsure, choose DEBUG_INFO_COMPRESSED_NONE. 324 325config DEBUG_INFO_COMPRESSED_NONE 326 bool "Don't compress debug information" 327 help 328 Don't compress debug info sections. 329 330config DEBUG_INFO_COMPRESSED_ZLIB 331 bool "Compress debugging information with zlib" 332 depends on $(cc-option,-gz=zlib) 333 depends on $(ld-option,--compress-debug-sections=zlib) 334 help 335 Compress the debug information using zlib. Requires GCC 5.0+ or Clang 336 5.0+, binutils 2.26+, and zlib. 337 338 Users of dpkg-deb via scripts/package/builddeb may find an increase in 339 size of their debug .deb packages with this config set, due to the 340 debug info being compressed with zlib, then the object files being 341 recompressed with a different compression scheme. But this is still 342 preferable to setting $KDEB_COMPRESS to "none" which would be even 343 larger. 344 345config DEBUG_INFO_COMPRESSED_ZSTD 346 bool "Compress debugging information with zstd" 347 depends on $(cc-option,-gz=zstd) 348 depends on $(ld-option,--compress-debug-sections=zstd) 349 help 350 Compress the debug information using zstd. This may provide better 351 compression than zlib, for about the same time costs, but requires newer 352 toolchain support. Requires GCC 13.0+ or Clang 16.0+, binutils 2.40+, and 353 zstd. 354 355endchoice # "Compressed Debug information" 356 357config DEBUG_INFO_SPLIT 358 bool "Produce split debuginfo in .dwo files" 359 depends on $(cc-option,-gsplit-dwarf) 360 # RISC-V linker relaxation + -gsplit-dwarf has issues with LLVM and GCC 361 # prior to 12.x: 362 # https://github.com/llvm/llvm-project/issues/56642 363 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99090 364 depends on !RISCV || GCC_VERSION >= 120000 365 help 366 Generate debug info into separate .dwo files. This significantly 367 reduces the build directory size for builds with DEBUG_INFO, 368 because it stores the information only once on disk in .dwo 369 files instead of multiple times in object files and executables. 370 In addition the debug information is also compressed. 371 372 Requires recent gcc (4.7+) and recent gdb/binutils. 373 Any tool that packages or reads debug information would need 374 to know about the .dwo files and include them. 375 Incompatible with older versions of ccache. 376 377config DEBUG_INFO_BTF 378 bool "Generate BTF type information" 379 depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED 380 depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST 381 depends on BPF_SYSCALL 382 depends on PAHOLE_VERSION >= 116 383 depends on DEBUG_INFO_DWARF4 || PAHOLE_VERSION >= 121 384 # pahole uses elfutils, which does not have support for Hexagon relocations 385 depends on !HEXAGON 386 help 387 Generate deduplicated BTF type information from DWARF debug info. 388 Turning this on requires pahole v1.16 or later (v1.21 or later to 389 support DWARF 5), which will convert DWARF type info into equivalent 390 deduplicated BTF type info. 391 392config PAHOLE_HAS_SPLIT_BTF 393 def_bool PAHOLE_VERSION >= 119 394 395config PAHOLE_HAS_BTF_TAG 396 def_bool PAHOLE_VERSION >= 123 397 depends on CC_IS_CLANG 398 help 399 Decide whether pahole emits btf_tag attributes (btf_type_tag and 400 btf_decl_tag) or not. Currently only clang compiler implements 401 these attributes, so make the config depend on CC_IS_CLANG. 402 403config PAHOLE_HAS_LANG_EXCLUDE 404 def_bool PAHOLE_VERSION >= 124 405 help 406 Support for the --lang_exclude flag which makes pahole exclude 407 compilation units from the supplied language. Used in Kbuild to 408 omit Rust CUs which are not supported in version 1.24 of pahole, 409 otherwise it would emit malformed kernel and module binaries when 410 using DEBUG_INFO_BTF_MODULES. 411 412config DEBUG_INFO_BTF_MODULES 413 bool "Generate BTF type information for kernel modules" 414 default y 415 depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF 416 help 417 Generate compact split BTF type information for kernel modules. 418 419config MODULE_ALLOW_BTF_MISMATCH 420 bool "Allow loading modules with non-matching BTF type info" 421 depends on DEBUG_INFO_BTF_MODULES 422 help 423 For modules whose split BTF does not match vmlinux, load without 424 BTF rather than refusing to load. The default behavior with 425 module BTF enabled is to reject modules with such mismatches; 426 this option will still load module BTF where possible but ignore 427 it when a mismatch is found. 428 429config GDB_SCRIPTS 430 bool "Provide GDB scripts for kernel debugging" 431 help 432 This creates the required links to GDB helper scripts in the 433 build directory. If you load vmlinux into gdb, the helper 434 scripts will be automatically imported by gdb as well, and 435 additional functions are available to analyze a Linux kernel 436 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst 437 for further details. 438 439endif # DEBUG_INFO 440 441config FRAME_WARN 442 int "Warn for stack frames larger than" 443 range 0 8192 444 default 0 if KMSAN 445 default 2048 if GCC_PLUGIN_LATENT_ENTROPY 446 default 2048 if PARISC 447 default 1536 if (!64BIT && XTENSA) 448 default 1280 if KASAN && !64BIT 449 default 1024 if !64BIT 450 default 2048 if 64BIT 451 help 452 Tell the compiler to warn at build time for stack frames larger than this. 453 Setting this too low will cause a lot of warnings. 454 Setting it to 0 disables the warning. 455 456config STRIP_ASM_SYMS 457 bool "Strip assembler-generated symbols during link" 458 default n 459 help 460 Strip internal assembler-generated symbols during a link (symbols 461 that look like '.Lxxx') so they don't pollute the output of 462 get_wchan() and suchlike. 463 464config READABLE_ASM 465 bool "Generate readable assembler code" 466 depends on DEBUG_KERNEL 467 depends on CC_IS_GCC 468 help 469 Disable some compiler optimizations that tend to generate human unreadable 470 assembler output. This may make the kernel slightly slower, but it helps 471 to keep kernel developers who have to stare a lot at assembler listings 472 sane. 473 474config HEADERS_INSTALL 475 bool "Install uapi headers to usr/include" 476 depends on !UML 477 help 478 This option will install uapi headers (headers exported to user-space) 479 into the usr/include directory for use during the kernel build. 480 This is unneeded for building the kernel itself, but needed for some 481 user-space program samples. It is also needed by some features such 482 as uapi header sanity checks. 483 484config DEBUG_SECTION_MISMATCH 485 bool "Enable full Section mismatch analysis" 486 depends on CC_IS_GCC 487 help 488 The section mismatch analysis checks if there are illegal 489 references from one section to another section. 490 During linktime or runtime, some sections are dropped; 491 any use of code/data previously in these sections would 492 most likely result in an oops. 493 In the code, functions and variables are annotated with 494 __init,, etc. (see the full list in include/linux/init.h), 495 which results in the code/data being placed in specific sections. 496 The section mismatch analysis is always performed after a full 497 kernel build, and enabling this option causes the following 498 additional step to occur: 499 - Add the option -fno-inline-functions-called-once to gcc commands. 500 When inlining a function annotated with __init in a non-init 501 function, we would lose the section information and thus 502 the analysis would not catch the illegal reference. 503 This option tells gcc to inline less (but it does result in 504 a larger kernel). 505 506config SECTION_MISMATCH_WARN_ONLY 507 bool "Make section mismatch errors non-fatal" 508 default y 509 help 510 If you say N here, the build process will fail if there are any 511 section mismatch, instead of just throwing warnings. 512 513 If unsure, say Y. 514 515config DEBUG_FORCE_FUNCTION_ALIGN_64B 516 bool "Force all function address 64B aligned" 517 depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC || RISCV || S390) 518 select FUNCTION_ALIGNMENT_64B 519 help 520 There are cases that a commit from one domain changes the function 521 address alignment of other domains, and cause magic performance 522 bump (regression or improvement). Enable this option will help to 523 verify if the bump is caused by function alignment changes, while 524 it will slightly increase the kernel size and affect icache usage. 525 526 It is mainly for debug and performance tuning use. 527 528# 529# Select this config option from the architecture Kconfig, if it 530# is preferred to always offer frame pointers as a config 531# option on the architecture (regardless of KERNEL_DEBUG): 532# 533config ARCH_WANT_FRAME_POINTERS 534 bool 535 536config FRAME_POINTER 537 bool "Compile the kernel with frame pointers" 538 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS 539 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 540 help 541 If you say Y here the resulting kernel image will be slightly 542 larger and slower, but it gives very useful debugging information 543 in case of kernel bugs. (precise oopses/stacktraces/warnings) 544 545config OBJTOOL 546 bool 547 548config STACK_VALIDATION 549 bool "Compile-time stack metadata validation" 550 depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER 551 select OBJTOOL 552 default n 553 help 554 Validate frame pointer rules at compile-time. This helps ensure that 555 runtime stack traces are more reliable. 556 557 For more information, see 558 tools/objtool/Documentation/objtool.txt. 559 560config NOINSTR_VALIDATION 561 bool 562 depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY 563 select OBJTOOL 564 default y 565 566config VMLINUX_MAP 567 bool "Generate vmlinux.map file when linking" 568 depends on EXPERT 569 help 570 Selecting this option will pass "-Map=vmlinux.map" to ld 571 when linking vmlinux. That file can be useful for verifying 572 and debugging magic section games, and for seeing which 573 pieces of code get eliminated with 574 CONFIG_LD_DEAD_CODE_DATA_ELIMINATION. 575 576config BUILTIN_MODULE_RANGES 577 bool "Generate address range information for builtin modules" 578 depends on !LTO 579 depends on VMLINUX_MAP 580 help 581 When modules are built into the kernel, there will be no module name 582 associated with its symbols in /proc/kallsyms. Tracers may want to 583 identify symbols by module name and symbol name regardless of whether 584 the module is configured as loadable or not. 585 586 This option generates modules.builtin.ranges in the build tree with 587 offset ranges (per ELF section) for the module(s) they belong to. 588 It also records an anchor symbol to determine the load address of the 589 section. 590 591config DEBUG_FORCE_WEAK_PER_CPU 592 bool "Force weak per-cpu definitions" 593 depends on DEBUG_KERNEL 594 help 595 s390 and alpha require percpu variables in modules to be 596 defined weak to work around addressing range issue which 597 puts the following two restrictions on percpu variable 598 definitions. 599 600 1. percpu symbols must be unique whether static or not 601 2. percpu variables can't be defined inside a function 602 603 To ensure that generic code follows the above rules, this 604 option forces all percpu variables to be defined as weak. 605 606endmenu # "Compiler options" 607 608menu "Generic Kernel Debugging Instruments" 609 610config MAGIC_SYSRQ 611 bool "Magic SysRq key" 612 depends on !UML 613 help 614 If you say Y here, you will have some control over the system even 615 if the system crashes for example during kernel debugging (e.g., you 616 will be able to flush the buffer cache to disk, reboot the system 617 immediately or dump some status information). This is accomplished 618 by pressing various keys while holding SysRq (Alt+PrintScreen). It 619 also works on a serial console (on PC hardware at least), if you 620 send a BREAK and then within 5 seconds a command keypress. The 621 keys are documented in <file:Documentation/admin-guide/sysrq.rst>. 622 Don't say Y unless you really know what this hack does. 623 624config MAGIC_SYSRQ_DEFAULT_ENABLE 625 hex "Enable magic SysRq key functions by default" 626 depends on MAGIC_SYSRQ 627 default 0x1 628 help 629 Specifies which SysRq key functions are enabled by default. 630 This may be set to 1 or 0 to enable or disable them all, or 631 to a bitmask as described in Documentation/admin-guide/sysrq.rst. 632 633config MAGIC_SYSRQ_SERIAL 634 bool "Enable magic SysRq key over serial" 635 depends on MAGIC_SYSRQ 636 default y 637 help 638 Many embedded boards have a disconnected TTL level serial which can 639 generate some garbage that can lead to spurious false sysrq detects. 640 This option allows you to decide whether you want to enable the 641 magic SysRq key. 642 643config MAGIC_SYSRQ_SERIAL_SEQUENCE 644 string "Char sequence that enables magic SysRq over serial" 645 depends on MAGIC_SYSRQ_SERIAL 646 default "" 647 help 648 Specifies a sequence of characters that can follow BREAK to enable 649 SysRq on a serial console. 650 651 If unsure, leave an empty string and the option will not be enabled. 652 653config DEBUG_FS 654 bool "Debug Filesystem" 655 help 656 debugfs is a virtual file system that kernel developers use to put 657 debugging files into. Enable this option to be able to read and 658 write to these files. 659 660 For detailed documentation on the debugfs API, see 661 Documentation/filesystems/. 662 663 If unsure, say N. 664 665choice 666 prompt "Debugfs default access" 667 depends on DEBUG_FS 668 default DEBUG_FS_ALLOW_ALL 669 help 670 This selects the default access restrictions for debugfs. 671 It can be overridden with kernel command line option 672 debugfs=[on,no-mount,off]. The restrictions apply for API access 673 and filesystem registration. 674 675config DEBUG_FS_ALLOW_ALL 676 bool "Access normal" 677 help 678 No restrictions apply. Both API and filesystem registration 679 is on. This is the normal default operation. 680 681config DEBUG_FS_DISALLOW_MOUNT 682 bool "Do not register debugfs as filesystem" 683 help 684 The API is open but filesystem is not loaded. Clients can still do 685 their work and read with debug tools that do not need 686 debugfs filesystem. 687 688config DEBUG_FS_ALLOW_NONE 689 bool "No access" 690 help 691 Access is off. Clients get -PERM when trying to create nodes in 692 debugfs tree and debugfs is not registered as a filesystem. 693 Client can then back-off or continue without debugfs access. 694 695endchoice 696 697source "lib/Kconfig.kgdb" 698source "lib/Kconfig.ubsan" 699source "lib/Kconfig.kcsan" 700 701endmenu 702 703menu "Networking Debugging" 704 705source "net/Kconfig.debug" 706 707endmenu # "Networking Debugging" 708 709menu "Memory Debugging" 710 711source "mm/Kconfig.debug" 712 713config DEBUG_OBJECTS 714 bool "Debug object operations" 715 depends on DEBUG_KERNEL 716 help 717 If you say Y here, additional code will be inserted into the 718 kernel to track the life time of various objects and validate 719 the operations on those objects. 720 721config DEBUG_OBJECTS_SELFTEST 722 bool "Debug objects selftest" 723 depends on DEBUG_OBJECTS 724 help 725 This enables the selftest of the object debug code. 726 727config DEBUG_OBJECTS_FREE 728 bool "Debug objects in freed memory" 729 depends on DEBUG_OBJECTS 730 help 731 This enables checks whether a k/v free operation frees an area 732 which contains an object which has not been deactivated 733 properly. This can make kmalloc/kfree-intensive workloads 734 much slower. 735 736config DEBUG_OBJECTS_TIMERS 737 bool "Debug timer objects" 738 depends on DEBUG_OBJECTS 739 help 740 If you say Y here, additional code will be inserted into the 741 timer routines to track the life time of timer objects and 742 validate the timer operations. 743 744config DEBUG_OBJECTS_WORK 745 bool "Debug work objects" 746 depends on DEBUG_OBJECTS 747 help 748 If you say Y here, additional code will be inserted into the 749 work queue routines to track the life time of work objects and 750 validate the work operations. 751 752config DEBUG_OBJECTS_RCU_HEAD 753 bool "Debug RCU callbacks objects" 754 depends on DEBUG_OBJECTS 755 help 756 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 757 758config DEBUG_OBJECTS_PERCPU_COUNTER 759 bool "Debug percpu counter objects" 760 depends on DEBUG_OBJECTS 761 help 762 If you say Y here, additional code will be inserted into the 763 percpu counter routines to track the life time of percpu counter 764 objects and validate the percpu counter operations. 765 766config DEBUG_OBJECTS_ENABLE_DEFAULT 767 int "debug_objects bootup default value (0-1)" 768 range 0 1 769 default "1" 770 depends on DEBUG_OBJECTS 771 help 772 Debug objects boot parameter default value 773 774config SHRINKER_DEBUG 775 bool "Enable shrinker debugging support" 776 depends on DEBUG_FS 777 help 778 Say Y to enable the shrinker debugfs interface which provides 779 visibility into the kernel memory shrinkers subsystem. 780 Disable it to avoid an extra memory footprint. 781 782config DEBUG_STACK_USAGE 783 bool "Stack utilization instrumentation" 784 depends on DEBUG_KERNEL 785 help 786 Enables the display of the minimum amount of free stack which each 787 task has ever had available in the sysrq-T and sysrq-P debug output. 788 Also emits a message to dmesg when a process exits if that process 789 used more stack space than previously exiting processes. 790 791 This option will slow down process creation somewhat. 792 793config SCHED_STACK_END_CHECK 794 bool "Detect stack corruption on calls to schedule()" 795 depends on DEBUG_KERNEL 796 default n 797 help 798 This option checks for a stack overrun on calls to schedule(). 799 If the stack end location is found to be over written always panic as 800 the content of the corrupted region can no longer be trusted. 801 This is to ensure no erroneous behaviour occurs which could result in 802 data corruption or a sporadic crash at a later stage once the region 803 is examined. The runtime overhead introduced is minimal. 804 805config ARCH_HAS_DEBUG_VM_PGTABLE 806 bool 807 help 808 An architecture should select this when it can successfully 809 build and run DEBUG_VM_PGTABLE. 810 811config DEBUG_VM_IRQSOFF 812 def_bool DEBUG_VM && !PREEMPT_RT 813 814config DEBUG_VM 815 bool "Debug VM" 816 depends on DEBUG_KERNEL 817 help 818 Enable this to turn on extended checks in the virtual-memory system 819 that may impact performance. 820 821 If unsure, say N. 822 823config DEBUG_VM_SHOOT_LAZIES 824 bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation" 825 depends on DEBUG_VM 826 depends on MMU_LAZY_TLB_SHOOTDOWN 827 help 828 Enable additional IPIs that ensure lazy tlb mm references are removed 829 before the mm is freed. 830 831 If unsure, say N. 832 833config DEBUG_VM_MAPLE_TREE 834 bool "Debug VM maple trees" 835 depends on DEBUG_VM 836 select DEBUG_MAPLE_TREE 837 help 838 Enable VM maple tree debugging information and extra validations. 839 840 If unsure, say N. 841 842config DEBUG_VM_RB 843 bool "Debug VM red-black trees" 844 depends on DEBUG_VM 845 help 846 Enable VM red-black tree debugging information and extra validations. 847 848 If unsure, say N. 849 850config DEBUG_VM_PGFLAGS 851 bool "Debug page-flags operations" 852 depends on DEBUG_VM 853 help 854 Enables extra validation on page flags operations. 855 856 If unsure, say N. 857 858config DEBUG_VM_PGTABLE 859 bool "Debug arch page table for semantics compliance" 860 depends on MMU 861 depends on ARCH_HAS_DEBUG_VM_PGTABLE 862 default y if DEBUG_VM 863 help 864 This option provides a debug method which can be used to test 865 architecture page table helper functions on various platforms in 866 verifying if they comply with expected generic MM semantics. This 867 will help architecture code in making sure that any changes or 868 new additions of these helpers still conform to expected 869 semantics of the generic MM. Platforms will have to opt in for 870 this through ARCH_HAS_DEBUG_VM_PGTABLE. 871 872 If unsure, say N. 873 874config ARCH_HAS_DEBUG_VIRTUAL 875 bool 876 877config DEBUG_VIRTUAL 878 bool "Debug VM translations" 879 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL 880 help 881 Enable some costly sanity checks in virtual to page code. This can 882 catch mistakes with virt_to_page() and friends. 883 884 If unsure, say N. 885 886config DEBUG_NOMMU_REGIONS 887 bool "Debug the global anon/private NOMMU mapping region tree" 888 depends on DEBUG_KERNEL && !MMU 889 help 890 This option causes the global tree of anonymous and private mapping 891 regions to be regularly checked for invalid topology. 892 893config DEBUG_MEMORY_INIT 894 bool "Debug memory initialisation" if EXPERT 895 default !EXPERT 896 help 897 Enable this for additional checks during memory initialisation. 898 The sanity checks verify aspects of the VM such as the memory model 899 and other information provided by the architecture. Verbose 900 information will be printed at KERN_DEBUG loglevel depending 901 on the mminit_loglevel= command-line option. 902 903 If unsure, say Y 904 905config MEMORY_NOTIFIER_ERROR_INJECT 906 tristate "Memory hotplug notifier error injection module" 907 depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION 908 help 909 This option provides the ability to inject artificial errors to 910 memory hotplug notifier chain callbacks. It is controlled through 911 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 912 913 If the notifier call chain should be failed with some events 914 notified, write the error code to "actions/<notifier event>/error". 915 916 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 917 918 # cd /sys/kernel/debug/notifier-error-inject/memory 919 # echo -12 > actions/MEM_GOING_OFFLINE/error 920 # echo offline > /sys/devices/system/memory/memoryXXX/state 921 bash: echo: write error: Cannot allocate memory 922 923 To compile this code as a module, choose M here: the module will 924 be called memory-notifier-error-inject. 925 926 If unsure, say N. 927 928config DEBUG_PER_CPU_MAPS 929 bool "Debug access to per_cpu maps" 930 depends on DEBUG_KERNEL 931 depends on SMP 932 help 933 Say Y to verify that the per_cpu map being accessed has 934 been set up. This adds a fair amount of code to kernel memory 935 and decreases performance. 936 937 Say N if unsure. 938 939config DEBUG_KMAP_LOCAL 940 bool "Debug kmap_local temporary mappings" 941 depends on DEBUG_KERNEL && KMAP_LOCAL 942 help 943 This option enables additional error checking for the kmap_local 944 infrastructure. Disable for production use. 945 946config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 947 bool 948 949config DEBUG_KMAP_LOCAL_FORCE_MAP 950 bool "Enforce kmap_local temporary mappings" 951 depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 952 select KMAP_LOCAL 953 select DEBUG_KMAP_LOCAL 954 help 955 This option enforces temporary mappings through the kmap_local 956 mechanism for non-highmem pages and on non-highmem systems. 957 Disable this for production systems! 958 959config DEBUG_HIGHMEM 960 bool "Highmem debugging" 961 depends on DEBUG_KERNEL && HIGHMEM 962 select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 963 select DEBUG_KMAP_LOCAL 964 help 965 This option enables additional error checking for high memory 966 systems. Disable for production systems. 967 968config HAVE_DEBUG_STACKOVERFLOW 969 bool 970 971config DEBUG_STACKOVERFLOW 972 bool "Check for stack overflows" 973 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 974 help 975 Say Y here if you want to check for overflows of kernel, IRQ 976 and exception stacks (if your architecture uses them). This 977 option will show detailed messages if free stack space drops 978 below a certain limit. 979 980 These kinds of bugs usually occur when call-chains in the 981 kernel get too deep, especially when interrupts are 982 involved. 983 984 Use this in cases where you see apparently random memory 985 corruption, especially if it appears in 'struct thread_info' 986 987 If in doubt, say "N". 988 989config CODE_TAGGING 990 bool 991 select KALLSYMS 992 993config MEM_ALLOC_PROFILING 994 bool "Enable memory allocation profiling" 995 default n 996 depends on PROC_FS 997 depends on !DEBUG_FORCE_WEAK_PER_CPU 998 select CODE_TAGGING 999 select PAGE_EXTENSION 1000 select SLAB_OBJ_EXT 1001 help 1002 Track allocation source code and record total allocation size 1003 initiated at that code location. The mechanism can be used to track 1004 memory leaks with a low performance and memory impact. 1005 1006config MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT 1007 bool "Enable memory allocation profiling by default" 1008 default y 1009 depends on MEM_ALLOC_PROFILING 1010 1011config MEM_ALLOC_PROFILING_DEBUG 1012 bool "Memory allocation profiler debugging" 1013 default n 1014 depends on MEM_ALLOC_PROFILING 1015 select MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT 1016 help 1017 Adds warnings with helpful error messages for memory allocation 1018 profiling. 1019 1020source "lib/Kconfig.kasan" 1021source "lib/Kconfig.kfence" 1022source "lib/Kconfig.kmsan" 1023 1024endmenu # "Memory Debugging" 1025 1026config DEBUG_SHIRQ 1027 bool "Debug shared IRQ handlers" 1028 depends on DEBUG_KERNEL 1029 help 1030 Enable this to generate a spurious interrupt just before a shared 1031 interrupt handler is deregistered (generating one when registering 1032 is currently disabled). Drivers need to handle this correctly. Some 1033 don't and need to be caught. 1034 1035menu "Debug Oops, Lockups and Hangs" 1036 1037config PANIC_ON_OOPS 1038 bool "Panic on Oops" 1039 help 1040 Say Y here to enable the kernel to panic when it oopses. This 1041 has the same effect as setting oops=panic on the kernel command 1042 line. 1043 1044 This feature is useful to ensure that the kernel does not do 1045 anything erroneous after an oops which could result in data 1046 corruption or other issues. 1047 1048 Say N if unsure. 1049 1050config PANIC_ON_OOPS_VALUE 1051 int 1052 range 0 1 1053 default 0 if !PANIC_ON_OOPS 1054 default 1 if PANIC_ON_OOPS 1055 1056config PANIC_TIMEOUT 1057 int "panic timeout" 1058 default 0 1059 help 1060 Set the timeout value (in seconds) until a reboot occurs when 1061 the kernel panics. If n = 0, then we wait forever. A timeout 1062 value n > 0 will wait n seconds before rebooting, while a timeout 1063 value n < 0 will reboot immediately. This setting can be overridden 1064 with the kernel command line option panic=, and from userspace via 1065 /proc/sys/kernel/panic. 1066 1067config LOCKUP_DETECTOR 1068 bool 1069 1070config SOFTLOCKUP_DETECTOR 1071 bool "Detect Soft Lockups" 1072 depends on DEBUG_KERNEL && !S390 1073 select LOCKUP_DETECTOR 1074 help 1075 Say Y here to enable the kernel to act as a watchdog to detect 1076 soft lockups. 1077 1078 Softlockups are bugs that cause the kernel to loop in kernel 1079 mode for more than 20 seconds, without giving other tasks a 1080 chance to run. The current stack trace is displayed upon 1081 detection and the system will stay locked up. 1082 1083config SOFTLOCKUP_DETECTOR_INTR_STORM 1084 bool "Detect Interrupt Storm in Soft Lockups" 1085 depends on SOFTLOCKUP_DETECTOR && IRQ_TIME_ACCOUNTING 1086 select GENERIC_IRQ_STAT_SNAPSHOT 1087 default y if NR_CPUS <= 128 1088 help 1089 Say Y here to enable the kernel to detect interrupt storm 1090 during "soft lockups". 1091 1092 "soft lockups" can be caused by a variety of reasons. If one is 1093 caused by an interrupt storm, then the storming interrupts will not 1094 be on the callstack. To detect this case, it is necessary to report 1095 the CPU stats and the interrupt counts during the "soft lockups". 1096 1097config BOOTPARAM_SOFTLOCKUP_PANIC 1098 bool "Panic (Reboot) On Soft Lockups" 1099 depends on SOFTLOCKUP_DETECTOR 1100 help 1101 Say Y here to enable the kernel to panic on "soft lockups", 1102 which are bugs that cause the kernel to loop in kernel 1103 mode for more than 20 seconds (configurable using the watchdog_thresh 1104 sysctl), without giving other tasks a chance to run. 1105 1106 The panic can be used in combination with panic_timeout, 1107 to cause the system to reboot automatically after a 1108 lockup has been detected. This feature is useful for 1109 high-availability systems that have uptime guarantees and 1110 where a lockup must be resolved ASAP. 1111 1112 Say N if unsure. 1113 1114config HAVE_HARDLOCKUP_DETECTOR_BUDDY 1115 bool 1116 depends on SMP 1117 default y 1118 1119# 1120# Global switch whether to build a hardlockup detector at all. It is available 1121# only when the architecture supports at least one implementation. There are 1122# two exceptions. The hardlockup detector is never enabled on: 1123# 1124# s390: it reported many false positives there 1125# 1126# sparc64: has a custom implementation which is not using the common 1127# hardlockup command line options and sysctl interface. 1128# 1129config HARDLOCKUP_DETECTOR 1130 bool "Detect Hard Lockups" 1131 depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64 1132 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH 1133 imply HARDLOCKUP_DETECTOR_PERF 1134 imply HARDLOCKUP_DETECTOR_BUDDY 1135 imply HARDLOCKUP_DETECTOR_ARCH 1136 select LOCKUP_DETECTOR 1137 1138 help 1139 Say Y here to enable the kernel to act as a watchdog to detect 1140 hard lockups. 1141 1142 Hardlockups are bugs that cause the CPU to loop in kernel mode 1143 for more than 10 seconds, without letting other interrupts have a 1144 chance to run. The current stack trace is displayed upon detection 1145 and the system will stay locked up. 1146 1147# 1148# Note that arch-specific variants are always preferred. 1149# 1150config HARDLOCKUP_DETECTOR_PREFER_BUDDY 1151 bool "Prefer the buddy CPU hardlockup detector" 1152 depends on HARDLOCKUP_DETECTOR 1153 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY 1154 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1155 help 1156 Say Y here to prefer the buddy hardlockup detector over the perf one. 1157 1158 With the buddy detector, each CPU uses its softlockup hrtimer 1159 to check that the next CPU is processing hrtimer interrupts by 1160 verifying that a counter is increasing. 1161 1162 This hardlockup detector is useful on systems that don't have 1163 an arch-specific hardlockup detector or if resources needed 1164 for the hardlockup detector are better used for other things. 1165 1166config HARDLOCKUP_DETECTOR_PERF 1167 bool 1168 depends on HARDLOCKUP_DETECTOR 1169 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY 1170 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1171 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1172 1173config HARDLOCKUP_DETECTOR_BUDDY 1174 bool 1175 depends on HARDLOCKUP_DETECTOR 1176 depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY 1177 depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY 1178 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1179 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1180 1181config HARDLOCKUP_DETECTOR_ARCH 1182 bool 1183 depends on HARDLOCKUP_DETECTOR 1184 depends on HAVE_HARDLOCKUP_DETECTOR_ARCH 1185 help 1186 The arch-specific implementation of the hardlockup detector will 1187 be used. 1188 1189# 1190# Both the "perf" and "buddy" hardlockup detectors count hrtimer 1191# interrupts. This config enables functions managing this common code. 1192# 1193config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1194 bool 1195 select SOFTLOCKUP_DETECTOR 1196 1197# 1198# Enables a timestamp based low pass filter to compensate for perf based 1199# hard lockup detection which runs too fast due to turbo modes. 1200# 1201config HARDLOCKUP_CHECK_TIMESTAMP 1202 bool 1203 1204config BOOTPARAM_HARDLOCKUP_PANIC 1205 bool "Panic (Reboot) On Hard Lockups" 1206 depends on HARDLOCKUP_DETECTOR 1207 help 1208 Say Y here to enable the kernel to panic on "hard lockups", 1209 which are bugs that cause the kernel to loop in kernel 1210 mode with interrupts disabled for more than 10 seconds (configurable 1211 using the watchdog_thresh sysctl). 1212 1213 Say N if unsure. 1214 1215config DETECT_HUNG_TASK 1216 bool "Detect Hung Tasks" 1217 depends on DEBUG_KERNEL 1218 default SOFTLOCKUP_DETECTOR 1219 help 1220 Say Y here to enable the kernel to detect "hung tasks", 1221 which are bugs that cause the task to be stuck in 1222 uninterruptible "D" state indefinitely. 1223 1224 When a hung task is detected, the kernel will print the 1225 current stack trace (which you should report), but the 1226 task will stay in uninterruptible state. If lockdep is 1227 enabled then all held locks will also be reported. This 1228 feature has negligible overhead. 1229 1230config DEFAULT_HUNG_TASK_TIMEOUT 1231 int "Default timeout for hung task detection (in seconds)" 1232 depends on DETECT_HUNG_TASK 1233 default 120 1234 help 1235 This option controls the default timeout (in seconds) used 1236 to determine when a task has become non-responsive and should 1237 be considered hung. 1238 1239 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 1240 sysctl or by writing a value to 1241 /proc/sys/kernel/hung_task_timeout_secs. 1242 1243 A timeout of 0 disables the check. The default is two minutes. 1244 Keeping the default should be fine in most cases. 1245 1246config BOOTPARAM_HUNG_TASK_PANIC 1247 bool "Panic (Reboot) On Hung Tasks" 1248 depends on DETECT_HUNG_TASK 1249 help 1250 Say Y here to enable the kernel to panic on "hung tasks", 1251 which are bugs that cause the kernel to leave a task stuck 1252 in uninterruptible "D" state. 1253 1254 The panic can be used in combination with panic_timeout, 1255 to cause the system to reboot automatically after a 1256 hung task has been detected. This feature is useful for 1257 high-availability systems that have uptime guarantees and 1258 where a hung tasks must be resolved ASAP. 1259 1260 Say N if unsure. 1261 1262config WQ_WATCHDOG 1263 bool "Detect Workqueue Stalls" 1264 depends on DEBUG_KERNEL 1265 help 1266 Say Y here to enable stall detection on workqueues. If a 1267 worker pool doesn't make forward progress on a pending work 1268 item for over a given amount of time, 30s by default, a 1269 warning message is printed along with dump of workqueue 1270 state. This can be configured through kernel parameter 1271 "workqueue.watchdog_thresh" and its sysfs counterpart. 1272 1273config WQ_CPU_INTENSIVE_REPORT 1274 bool "Report per-cpu work items which hog CPU for too long" 1275 depends on DEBUG_KERNEL 1276 help 1277 Say Y here to enable reporting of concurrency-managed per-cpu work 1278 items that hog CPUs for longer than 1279 workqueue.cpu_intensive_thresh_us. Workqueue automatically 1280 detects and excludes them from concurrency management to prevent 1281 them from stalling other per-cpu work items. Occassional 1282 triggering may not necessarily indicate a problem. Repeated 1283 triggering likely indicates that the work item should be switched 1284 to use an unbound workqueue. 1285 1286config TEST_LOCKUP 1287 tristate "Test module to generate lockups" 1288 depends on m 1289 help 1290 This builds the "test_lockup" module that helps to make sure 1291 that watchdogs and lockup detectors are working properly. 1292 1293 Depending on module parameters it could emulate soft or hard 1294 lockup, "hung task", or locking arbitrary lock for a long time. 1295 Also it could generate series of lockups with cooling-down periods. 1296 1297 If unsure, say N. 1298 1299endmenu # "Debug lockups and hangs" 1300 1301menu "Scheduler Debugging" 1302 1303config SCHED_DEBUG 1304 bool "Collect scheduler debugging info" 1305 depends on DEBUG_KERNEL && DEBUG_FS 1306 default y 1307 help 1308 If you say Y here, the /sys/kernel/debug/sched file will be provided 1309 that can help debug the scheduler. The runtime overhead of this 1310 option is minimal. 1311 1312config SCHED_INFO 1313 bool 1314 default n 1315 1316config SCHEDSTATS 1317 bool "Collect scheduler statistics" 1318 depends on PROC_FS 1319 select SCHED_INFO 1320 help 1321 If you say Y here, additional code will be inserted into the 1322 scheduler and related routines to collect statistics about 1323 scheduler behavior and provide them in /proc/schedstat. These 1324 stats may be useful for both tuning and debugging the scheduler 1325 If you aren't debugging the scheduler or trying to tune a specific 1326 application, you can say N to avoid the very slight overhead 1327 this adds. 1328 1329endmenu 1330 1331config DEBUG_PREEMPT 1332 bool "Debug preemptible kernel" 1333 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1334 help 1335 If you say Y here then the kernel will use a debug variant of the 1336 commonly used smp_processor_id() function and will print warnings 1337 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1338 will detect preemption count underflows. 1339 1340 This option has potential to introduce high runtime overhead, 1341 depending on workload as it triggers debugging routines for each 1342 this_cpu operation. It should only be used for debugging purposes. 1343 1344menu "Lock Debugging (spinlocks, mutexes, etc...)" 1345 1346config LOCK_DEBUGGING_SUPPORT 1347 bool 1348 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1349 default y 1350 1351config PROVE_LOCKING 1352 bool "Lock debugging: prove locking correctness" 1353 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1354 select LOCKDEP 1355 select DEBUG_SPINLOCK 1356 select DEBUG_MUTEXES if !PREEMPT_RT 1357 select DEBUG_RT_MUTEXES if RT_MUTEXES 1358 select DEBUG_RWSEMS if !PREEMPT_RT 1359 select DEBUG_WW_MUTEX_SLOWPATH 1360 select DEBUG_LOCK_ALLOC 1361 select PREEMPT_COUNT if !ARCH_NO_PREEMPT 1362 select TRACE_IRQFLAGS 1363 default n 1364 help 1365 This feature enables the kernel to prove that all locking 1366 that occurs in the kernel runtime is mathematically 1367 correct: that under no circumstance could an arbitrary (and 1368 not yet triggered) combination of observed locking 1369 sequences (on an arbitrary number of CPUs, running an 1370 arbitrary number of tasks and interrupt contexts) cause a 1371 deadlock. 1372 1373 In short, this feature enables the kernel to report locking 1374 related deadlocks before they actually occur. 1375 1376 The proof does not depend on how hard and complex a 1377 deadlock scenario would be to trigger: how many 1378 participant CPUs, tasks and irq-contexts would be needed 1379 for it to trigger. The proof also does not depend on 1380 timing: if a race and a resulting deadlock is possible 1381 theoretically (no matter how unlikely the race scenario 1382 is), it will be proven so and will immediately be 1383 reported by the kernel (once the event is observed that 1384 makes the deadlock theoretically possible). 1385 1386 If a deadlock is impossible (i.e. the locking rules, as 1387 observed by the kernel, are mathematically correct), the 1388 kernel reports nothing. 1389 1390 NOTE: this feature can also be enabled for rwlocks, mutexes 1391 and rwsems - in which case all dependencies between these 1392 different locking variants are observed and mapped too, and 1393 the proof of observed correctness is also maintained for an 1394 arbitrary combination of these separate locking variants. 1395 1396 For more details, see Documentation/locking/lockdep-design.rst. 1397 1398config PROVE_RAW_LOCK_NESTING 1399 bool "Enable raw_spinlock - spinlock nesting checks" 1400 depends on PROVE_LOCKING 1401 default n 1402 help 1403 Enable the raw_spinlock vs. spinlock nesting checks which ensure 1404 that the lock nesting rules for PREEMPT_RT enabled kernels are 1405 not violated. 1406 1407 NOTE: There are known nesting problems. So if you enable this 1408 option expect lockdep splats until these problems have been fully 1409 addressed which is work in progress. This config switch allows to 1410 identify and analyze these problems. It will be removed and the 1411 check permanently enabled once the main issues have been fixed. 1412 1413 If unsure, select N. 1414 1415config LOCK_STAT 1416 bool "Lock usage statistics" 1417 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1418 select LOCKDEP 1419 select DEBUG_SPINLOCK 1420 select DEBUG_MUTEXES if !PREEMPT_RT 1421 select DEBUG_RT_MUTEXES if RT_MUTEXES 1422 select DEBUG_LOCK_ALLOC 1423 default n 1424 help 1425 This feature enables tracking lock contention points 1426 1427 For more details, see Documentation/locking/lockstat.rst 1428 1429 This also enables lock events required by "perf lock", 1430 subcommand of perf. 1431 If you want to use "perf lock", you also need to turn on 1432 CONFIG_EVENT_TRACING. 1433 1434 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1435 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1436 1437config DEBUG_RT_MUTEXES 1438 bool "RT Mutex debugging, deadlock detection" 1439 depends on DEBUG_KERNEL && RT_MUTEXES 1440 help 1441 This allows rt mutex semantics violations and rt mutex related 1442 deadlocks (lockups) to be detected and reported automatically. 1443 1444config DEBUG_SPINLOCK 1445 bool "Spinlock and rw-lock debugging: basic checks" 1446 depends on DEBUG_KERNEL 1447 select UNINLINE_SPIN_UNLOCK 1448 help 1449 Say Y here and build SMP to catch missing spinlock initialization 1450 and certain other kinds of spinlock errors commonly made. This is 1451 best used in conjunction with the NMI watchdog so that spinlock 1452 deadlocks are also debuggable. 1453 1454config DEBUG_MUTEXES 1455 bool "Mutex debugging: basic checks" 1456 depends on DEBUG_KERNEL && !PREEMPT_RT 1457 help 1458 This feature allows mutex semantics violations to be detected and 1459 reported. 1460 1461config DEBUG_WW_MUTEX_SLOWPATH 1462 bool "Wait/wound mutex debugging: Slowpath testing" 1463 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1464 select DEBUG_LOCK_ALLOC 1465 select DEBUG_SPINLOCK 1466 select DEBUG_MUTEXES if !PREEMPT_RT 1467 select DEBUG_RT_MUTEXES if PREEMPT_RT 1468 help 1469 This feature enables slowpath testing for w/w mutex users by 1470 injecting additional -EDEADLK wound/backoff cases. Together with 1471 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1472 will test all possible w/w mutex interface abuse with the 1473 exception of simply not acquiring all the required locks. 1474 Note that this feature can introduce significant overhead, so 1475 it really should not be enabled in a production or distro kernel, 1476 even a debug kernel. If you are a driver writer, enable it. If 1477 you are a distro, do not. 1478 1479config DEBUG_RWSEMS 1480 bool "RW Semaphore debugging: basic checks" 1481 depends on DEBUG_KERNEL && !PREEMPT_RT 1482 help 1483 This debugging feature allows mismatched rw semaphore locks 1484 and unlocks to be detected and reported. 1485 1486config DEBUG_LOCK_ALLOC 1487 bool "Lock debugging: detect incorrect freeing of live locks" 1488 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1489 select DEBUG_SPINLOCK 1490 select DEBUG_MUTEXES if !PREEMPT_RT 1491 select DEBUG_RT_MUTEXES if RT_MUTEXES 1492 select LOCKDEP 1493 help 1494 This feature will check whether any held lock (spinlock, rwlock, 1495 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1496 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1497 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1498 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1499 held during task exit. 1500 1501config LOCKDEP 1502 bool 1503 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1504 select STACKTRACE 1505 select KALLSYMS 1506 select KALLSYMS_ALL 1507 1508config LOCKDEP_SMALL 1509 bool 1510 1511config LOCKDEP_BITS 1512 int "Bitsize for MAX_LOCKDEP_ENTRIES" 1513 depends on LOCKDEP && !LOCKDEP_SMALL 1514 range 10 30 1515 default 15 1516 help 1517 Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message. 1518 1519config LOCKDEP_CHAINS_BITS 1520 int "Bitsize for MAX_LOCKDEP_CHAINS" 1521 depends on LOCKDEP && !LOCKDEP_SMALL 1522 range 10 21 1523 default 16 1524 help 1525 Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message. 1526 1527config LOCKDEP_STACK_TRACE_BITS 1528 int "Bitsize for MAX_STACK_TRACE_ENTRIES" 1529 depends on LOCKDEP && !LOCKDEP_SMALL 1530 range 10 30 1531 default 19 1532 help 1533 Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message. 1534 1535config LOCKDEP_STACK_TRACE_HASH_BITS 1536 int "Bitsize for STACK_TRACE_HASH_SIZE" 1537 depends on LOCKDEP && !LOCKDEP_SMALL 1538 range 10 30 1539 default 14 1540 help 1541 Try increasing this value if you need large STACK_TRACE_HASH_SIZE. 1542 1543config LOCKDEP_CIRCULAR_QUEUE_BITS 1544 int "Bitsize for elements in circular_queue struct" 1545 depends on LOCKDEP 1546 range 10 30 1547 default 12 1548 help 1549 Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure. 1550 1551config DEBUG_LOCKDEP 1552 bool "Lock dependency engine debugging" 1553 depends on DEBUG_KERNEL && LOCKDEP 1554 select DEBUG_IRQFLAGS 1555 help 1556 If you say Y here, the lock dependency engine will do 1557 additional runtime checks to debug itself, at the price 1558 of more runtime overhead. 1559 1560config DEBUG_ATOMIC_SLEEP 1561 bool "Sleep inside atomic section checking" 1562 select PREEMPT_COUNT 1563 depends on DEBUG_KERNEL 1564 depends on !ARCH_NO_PREEMPT 1565 help 1566 If you say Y here, various routines which may sleep will become very 1567 noisy if they are called inside atomic sections: when a spinlock is 1568 held, inside an rcu read side critical section, inside preempt disabled 1569 sections, inside an interrupt, etc... 1570 1571config DEBUG_LOCKING_API_SELFTESTS 1572 bool "Locking API boot-time self-tests" 1573 depends on DEBUG_KERNEL 1574 help 1575 Say Y here if you want the kernel to run a short self-test during 1576 bootup. The self-test checks whether common types of locking bugs 1577 are detected by debugging mechanisms or not. (if you disable 1578 lock debugging then those bugs won't be detected of course.) 1579 The following locking APIs are covered: spinlocks, rwlocks, 1580 mutexes and rwsems. 1581 1582config LOCK_TORTURE_TEST 1583 tristate "torture tests for locking" 1584 depends on DEBUG_KERNEL 1585 select TORTURE_TEST 1586 help 1587 This option provides a kernel module that runs torture tests 1588 on kernel locking primitives. The kernel module may be built 1589 after the fact on the running kernel to be tested, if desired. 1590 1591 Say Y here if you want kernel locking-primitive torture tests 1592 to be built into the kernel. 1593 Say M if you want these torture tests to build as a module. 1594 Say N if you are unsure. 1595 1596config WW_MUTEX_SELFTEST 1597 tristate "Wait/wound mutex selftests" 1598 help 1599 This option provides a kernel module that runs tests on the 1600 on the struct ww_mutex locking API. 1601 1602 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1603 with this test harness. 1604 1605 Say M if you want these self tests to build as a module. 1606 Say N if you are unsure. 1607 1608config SCF_TORTURE_TEST 1609 tristate "torture tests for smp_call_function*()" 1610 depends on DEBUG_KERNEL 1611 select TORTURE_TEST 1612 help 1613 This option provides a kernel module that runs torture tests 1614 on the smp_call_function() family of primitives. The kernel 1615 module may be built after the fact on the running kernel to 1616 be tested, if desired. 1617 1618config CSD_LOCK_WAIT_DEBUG 1619 bool "Debugging for csd_lock_wait(), called from smp_call_function*()" 1620 depends on DEBUG_KERNEL 1621 depends on SMP 1622 depends on 64BIT 1623 default n 1624 help 1625 This option enables debug prints when CPUs are slow to respond 1626 to the smp_call_function*() IPI wrappers. These debug prints 1627 include the IPI handler function currently executing (if any) 1628 and relevant stack traces. 1629 1630config CSD_LOCK_WAIT_DEBUG_DEFAULT 1631 bool "Default csd_lock_wait() debugging on at boot time" 1632 depends on CSD_LOCK_WAIT_DEBUG 1633 depends on 64BIT 1634 default n 1635 help 1636 This option causes the csdlock_debug= kernel boot parameter to 1637 default to 1 (basic debugging) instead of 0 (no debugging). 1638 1639endmenu # lock debugging 1640 1641config TRACE_IRQFLAGS 1642 depends on TRACE_IRQFLAGS_SUPPORT 1643 bool 1644 help 1645 Enables hooks to interrupt enabling and disabling for 1646 either tracing or lock debugging. 1647 1648config TRACE_IRQFLAGS_NMI 1649 def_bool y 1650 depends on TRACE_IRQFLAGS 1651 depends on TRACE_IRQFLAGS_NMI_SUPPORT 1652 1653config NMI_CHECK_CPU 1654 bool "Debugging for CPUs failing to respond to backtrace requests" 1655 depends on DEBUG_KERNEL 1656 depends on X86 1657 default n 1658 help 1659 Enables debug prints when a CPU fails to respond to a given 1660 backtrace NMI. These prints provide some reasons why a CPU 1661 might legitimately be failing to respond, for example, if it 1662 is offline of if ignore_nmis is set. 1663 1664config DEBUG_IRQFLAGS 1665 bool "Debug IRQ flag manipulation" 1666 help 1667 Enables checks for potentially unsafe enabling or disabling of 1668 interrupts, such as calling raw_local_irq_restore() when interrupts 1669 are enabled. 1670 1671config STACKTRACE 1672 bool "Stack backtrace support" 1673 depends on STACKTRACE_SUPPORT 1674 help 1675 This option causes the kernel to create a /proc/pid/stack for 1676 every process, showing its current stack trace. 1677 It is also used by various kernel debugging features that require 1678 stack trace generation. 1679 1680config WARN_ALL_UNSEEDED_RANDOM 1681 bool "Warn for all uses of unseeded randomness" 1682 default n 1683 help 1684 Some parts of the kernel contain bugs relating to their use of 1685 cryptographically secure random numbers before it's actually possible 1686 to generate those numbers securely. This setting ensures that these 1687 flaws don't go unnoticed, by enabling a message, should this ever 1688 occur. This will allow people with obscure setups to know when things 1689 are going wrong, so that they might contact developers about fixing 1690 it. 1691 1692 Unfortunately, on some models of some architectures getting 1693 a fully seeded CRNG is extremely difficult, and so this can 1694 result in dmesg getting spammed for a surprisingly long 1695 time. This is really bad from a security perspective, and 1696 so architecture maintainers really need to do what they can 1697 to get the CRNG seeded sooner after the system is booted. 1698 However, since users cannot do anything actionable to 1699 address this, by default this option is disabled. 1700 1701 Say Y here if you want to receive warnings for all uses of 1702 unseeded randomness. This will be of use primarily for 1703 those developers interested in improving the security of 1704 Linux kernels running on their architecture (or 1705 subarchitecture). 1706 1707config DEBUG_KOBJECT 1708 bool "kobject debugging" 1709 depends on DEBUG_KERNEL 1710 help 1711 If you say Y here, some extra kobject debugging messages will be sent 1712 to the syslog. 1713 1714config DEBUG_KOBJECT_RELEASE 1715 bool "kobject release debugging" 1716 depends on DEBUG_OBJECTS_TIMERS 1717 help 1718 kobjects are reference counted objects. This means that their 1719 last reference count put is not predictable, and the kobject can 1720 live on past the point at which a driver decides to drop its 1721 initial reference to the kobject gained on allocation. An 1722 example of this would be a struct device which has just been 1723 unregistered. 1724 1725 However, some buggy drivers assume that after such an operation, 1726 the memory backing the kobject can be immediately freed. This 1727 goes completely against the principles of a refcounted object. 1728 1729 If you say Y here, the kernel will delay the release of kobjects 1730 on the last reference count to improve the visibility of this 1731 kind of kobject release bug. 1732 1733config HAVE_DEBUG_BUGVERBOSE 1734 bool 1735 1736menu "Debug kernel data structures" 1737 1738config DEBUG_LIST 1739 bool "Debug linked list manipulation" 1740 depends on DEBUG_KERNEL 1741 select LIST_HARDENED 1742 help 1743 Enable this to turn on extended checks in the linked-list walking 1744 routines. 1745 1746 This option trades better quality error reports for performance, and 1747 is more suitable for kernel debugging. If you care about performance, 1748 you should only enable CONFIG_LIST_HARDENED instead. 1749 1750 If unsure, say N. 1751 1752config DEBUG_PLIST 1753 bool "Debug priority linked list manipulation" 1754 depends on DEBUG_KERNEL 1755 help 1756 Enable this to turn on extended checks in the priority-ordered 1757 linked-list (plist) walking routines. This checks the entire 1758 list multiple times during each manipulation. 1759 1760 If unsure, say N. 1761 1762config DEBUG_SG 1763 bool "Debug SG table operations" 1764 depends on DEBUG_KERNEL 1765 help 1766 Enable this to turn on checks on scatter-gather tables. This can 1767 help find problems with drivers that do not properly initialize 1768 their sg tables. 1769 1770 If unsure, say N. 1771 1772config DEBUG_NOTIFIERS 1773 bool "Debug notifier call chains" 1774 depends on DEBUG_KERNEL 1775 help 1776 Enable this to turn on sanity checking for notifier call chains. 1777 This is most useful for kernel developers to make sure that 1778 modules properly unregister themselves from notifier chains. 1779 This is a relatively cheap check but if you care about maximum 1780 performance, say N. 1781 1782config DEBUG_CLOSURES 1783 bool "Debug closures (bcache async widgits)" 1784 depends on CLOSURES 1785 select DEBUG_FS 1786 help 1787 Keeps all active closures in a linked list and provides a debugfs 1788 interface to list them, which makes it possible to see asynchronous 1789 operations that get stuck. 1790 1791config DEBUG_MAPLE_TREE 1792 bool "Debug maple trees" 1793 depends on DEBUG_KERNEL 1794 help 1795 Enable maple tree debugging information and extra validations. 1796 1797 If unsure, say N. 1798 1799endmenu 1800 1801source "kernel/rcu/Kconfig.debug" 1802 1803config DEBUG_WQ_FORCE_RR_CPU 1804 bool "Force round-robin CPU selection for unbound work items" 1805 depends on DEBUG_KERNEL 1806 default n 1807 help 1808 Workqueue used to implicitly guarantee that work items queued 1809 without explicit CPU specified are put on the local CPU. This 1810 guarantee is no longer true and while local CPU is still 1811 preferred work items may be put on foreign CPUs. Kernel 1812 parameter "workqueue.debug_force_rr_cpu" is added to force 1813 round-robin CPU selection to flush out usages which depend on the 1814 now broken guarantee. This config option enables the debug 1815 feature by default. When enabled, memory and cache locality will 1816 be impacted. 1817 1818config CPU_HOTPLUG_STATE_CONTROL 1819 bool "Enable CPU hotplug state control" 1820 depends on DEBUG_KERNEL 1821 depends on HOTPLUG_CPU 1822 default n 1823 help 1824 Allows to write steps between "offline" and "online" to the CPUs 1825 sysfs target file so states can be stepped granular. This is a debug 1826 option for now as the hotplug machinery cannot be stopped and 1827 restarted at arbitrary points yet. 1828 1829 Say N if your are unsure. 1830 1831config LATENCYTOP 1832 bool "Latency measuring infrastructure" 1833 depends on DEBUG_KERNEL 1834 depends on STACKTRACE_SUPPORT 1835 depends on PROC_FS 1836 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 1837 select KALLSYMS 1838 select KALLSYMS_ALL 1839 select STACKTRACE 1840 select SCHEDSTATS 1841 help 1842 Enable this option if you want to use the LatencyTOP tool 1843 to find out which userspace is blocking on what kernel operations. 1844 1845config DEBUG_CGROUP_REF 1846 bool "Disable inlining of cgroup css reference count functions" 1847 depends on DEBUG_KERNEL 1848 depends on CGROUPS 1849 depends on KPROBES 1850 default n 1851 help 1852 Force cgroup css reference count functions to not be inlined so 1853 that they can be kprobed for debugging. 1854 1855source "kernel/trace/Kconfig" 1856 1857config PROVIDE_OHCI1394_DMA_INIT 1858 bool "Remote debugging over FireWire early on boot" 1859 depends on PCI && X86 1860 help 1861 If you want to debug problems which hang or crash the kernel early 1862 on boot and the crashing machine has a FireWire port, you can use 1863 this feature to remotely access the memory of the crashed machine 1864 over FireWire. This employs remote DMA as part of the OHCI1394 1865 specification which is now the standard for FireWire controllers. 1866 1867 With remote DMA, you can monitor the printk buffer remotely using 1868 firescope and access all memory below 4GB using fireproxy from gdb. 1869 Even controlling a kernel debugger is possible using remote DMA. 1870 1871 Usage: 1872 1873 If ohci1394_dma=early is used as boot parameter, it will initialize 1874 all OHCI1394 controllers which are found in the PCI config space. 1875 1876 As all changes to the FireWire bus such as enabling and disabling 1877 devices cause a bus reset and thereby disable remote DMA for all 1878 devices, be sure to have the cable plugged and FireWire enabled on 1879 the debugging host before booting the debug target for debugging. 1880 1881 This code (~1k) is freed after boot. By then, the firewire stack 1882 in charge of the OHCI-1394 controllers should be used instead. 1883 1884 See Documentation/core-api/debugging-via-ohci1394.rst for more information. 1885 1886source "samples/Kconfig" 1887 1888config ARCH_HAS_DEVMEM_IS_ALLOWED 1889 bool 1890 1891config STRICT_DEVMEM 1892 bool "Filter access to /dev/mem" 1893 depends on MMU && DEVMEM 1894 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED 1895 default y if PPC || X86 || ARM64 1896 help 1897 If this option is disabled, you allow userspace (root) access to all 1898 of memory, including kernel and userspace memory. Accidental 1899 access to this is obviously disastrous, but specific access can 1900 be used by people debugging the kernel. Note that with PAT support 1901 enabled, even in this case there are restrictions on /dev/mem 1902 use due to the cache aliasing requirements. 1903 1904 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 1905 file only allows userspace access to PCI space and the BIOS code and 1906 data regions. This is sufficient for dosemu and X and all common 1907 users of /dev/mem. 1908 1909 If in doubt, say Y. 1910 1911config IO_STRICT_DEVMEM 1912 bool "Filter I/O access to /dev/mem" 1913 depends on STRICT_DEVMEM 1914 help 1915 If this option is disabled, you allow userspace (root) access to all 1916 io-memory regardless of whether a driver is actively using that 1917 range. Accidental access to this is obviously disastrous, but 1918 specific access can be used by people debugging kernel drivers. 1919 1920 If this option is switched on, the /dev/mem file only allows 1921 userspace access to *idle* io-memory ranges (see /proc/iomem) This 1922 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 1923 if the driver using a given range cannot be disabled. 1924 1925 If in doubt, say Y. 1926 1927menu "$(SRCARCH) Debugging" 1928 1929source "arch/$(SRCARCH)/Kconfig.debug" 1930 1931endmenu 1932 1933menu "Kernel Testing and Coverage" 1934 1935source "lib/kunit/Kconfig" 1936 1937config NOTIFIER_ERROR_INJECTION 1938 tristate "Notifier error injection" 1939 depends on DEBUG_KERNEL 1940 select DEBUG_FS 1941 help 1942 This option provides the ability to inject artificial errors to 1943 specified notifier chain callbacks. It is useful to test the error 1944 handling of notifier call chain failures. 1945 1946 Say N if unsure. 1947 1948config PM_NOTIFIER_ERROR_INJECT 1949 tristate "PM notifier error injection module" 1950 depends on PM && NOTIFIER_ERROR_INJECTION 1951 default m if PM_DEBUG 1952 help 1953 This option provides the ability to inject artificial errors to 1954 PM notifier chain callbacks. It is controlled through debugfs 1955 interface /sys/kernel/debug/notifier-error-inject/pm 1956 1957 If the notifier call chain should be failed with some events 1958 notified, write the error code to "actions/<notifier event>/error". 1959 1960 Example: Inject PM suspend error (-12 = -ENOMEM) 1961 1962 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1963 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1964 # echo mem > /sys/power/state 1965 bash: echo: write error: Cannot allocate memory 1966 1967 To compile this code as a module, choose M here: the module will 1968 be called pm-notifier-error-inject. 1969 1970 If unsure, say N. 1971 1972config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1973 tristate "OF reconfig notifier error injection module" 1974 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1975 help 1976 This option provides the ability to inject artificial errors to 1977 OF reconfig notifier chain callbacks. It is controlled 1978 through debugfs interface under 1979 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1980 1981 If the notifier call chain should be failed with some events 1982 notified, write the error code to "actions/<notifier event>/error". 1983 1984 To compile this code as a module, choose M here: the module will 1985 be called of-reconfig-notifier-error-inject. 1986 1987 If unsure, say N. 1988 1989config NETDEV_NOTIFIER_ERROR_INJECT 1990 tristate "Netdev notifier error injection module" 1991 depends on NET && NOTIFIER_ERROR_INJECTION 1992 help 1993 This option provides the ability to inject artificial errors to 1994 netdevice notifier chain callbacks. It is controlled through debugfs 1995 interface /sys/kernel/debug/notifier-error-inject/netdev 1996 1997 If the notifier call chain should be failed with some events 1998 notified, write the error code to "actions/<notifier event>/error". 1999 2000 Example: Inject netdevice mtu change error (-22 = -EINVAL) 2001 2002 # cd /sys/kernel/debug/notifier-error-inject/netdev 2003 # echo -22 > actions/NETDEV_CHANGEMTU/error 2004 # ip link set eth0 mtu 1024 2005 RTNETLINK answers: Invalid argument 2006 2007 To compile this code as a module, choose M here: the module will 2008 be called netdev-notifier-error-inject. 2009 2010 If unsure, say N. 2011 2012config FUNCTION_ERROR_INJECTION 2013 bool "Fault-injections of functions" 2014 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 2015 help 2016 Add fault injections into various functions that are annotated with 2017 ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return 2018 value of these functions. This is useful to test error paths of code. 2019 2020 If unsure, say N 2021 2022config FAULT_INJECTION 2023 bool "Fault-injection framework" 2024 depends on DEBUG_KERNEL 2025 help 2026 Provide fault-injection framework. 2027 For more details, see Documentation/fault-injection/. 2028 2029config FAILSLAB 2030 bool "Fault-injection capability for kmalloc" 2031 depends on FAULT_INJECTION 2032 help 2033 Provide fault-injection capability for kmalloc. 2034 2035config FAIL_PAGE_ALLOC 2036 bool "Fault-injection capability for alloc_pages()" 2037 depends on FAULT_INJECTION 2038 help 2039 Provide fault-injection capability for alloc_pages(). 2040 2041config FAULT_INJECTION_USERCOPY 2042 bool "Fault injection capability for usercopy functions" 2043 depends on FAULT_INJECTION 2044 help 2045 Provides fault-injection capability to inject failures 2046 in usercopy functions (copy_from_user(), get_user(), ...). 2047 2048config FAIL_MAKE_REQUEST 2049 bool "Fault-injection capability for disk IO" 2050 depends on FAULT_INJECTION && BLOCK 2051 help 2052 Provide fault-injection capability for disk IO. 2053 2054config FAIL_IO_TIMEOUT 2055 bool "Fault-injection capability for faking disk interrupts" 2056 depends on FAULT_INJECTION && BLOCK 2057 help 2058 Provide fault-injection capability on end IO handling. This 2059 will make the block layer "forget" an interrupt as configured, 2060 thus exercising the error handling. 2061 2062 Only works with drivers that use the generic timeout handling, 2063 for others it won't do anything. 2064 2065config FAIL_FUTEX 2066 bool "Fault-injection capability for futexes" 2067 select DEBUG_FS 2068 depends on FAULT_INJECTION && FUTEX 2069 help 2070 Provide fault-injection capability for futexes. 2071 2072config FAULT_INJECTION_DEBUG_FS 2073 bool "Debugfs entries for fault-injection capabilities" 2074 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 2075 help 2076 Enable configuration of fault-injection capabilities via debugfs. 2077 2078config FAIL_FUNCTION 2079 bool "Fault-injection capability for functions" 2080 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 2081 help 2082 Provide function-based fault-injection capability. 2083 This will allow you to override a specific function with a return 2084 with given return value. As a result, function caller will see 2085 an error value and have to handle it. This is useful to test the 2086 error handling in various subsystems. 2087 2088config FAIL_MMC_REQUEST 2089 bool "Fault-injection capability for MMC IO" 2090 depends on FAULT_INJECTION_DEBUG_FS && MMC 2091 help 2092 Provide fault-injection capability for MMC IO. 2093 This will make the mmc core return data errors. This is 2094 useful to test the error handling in the mmc block device 2095 and to test how the mmc host driver handles retries from 2096 the block device. 2097 2098config FAIL_SUNRPC 2099 bool "Fault-injection capability for SunRPC" 2100 depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG 2101 help 2102 Provide fault-injection capability for SunRPC and 2103 its consumers. 2104 2105config FAULT_INJECTION_CONFIGFS 2106 bool "Configfs interface for fault-injection capabilities" 2107 depends on FAULT_INJECTION 2108 select CONFIGFS_FS 2109 help 2110 This option allows configfs-based drivers to dynamically configure 2111 fault-injection via configfs. Each parameter for driver-specific 2112 fault-injection can be made visible as a configfs attribute in a 2113 configfs group. 2114 2115 2116config FAULT_INJECTION_STACKTRACE_FILTER 2117 bool "stacktrace filter for fault-injection capabilities" 2118 depends on FAULT_INJECTION 2119 depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT 2120 select STACKTRACE 2121 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 2122 help 2123 Provide stacktrace filter for fault-injection capabilities 2124 2125config ARCH_HAS_KCOV 2126 bool 2127 help 2128 An architecture should select this when it can successfully 2129 build and run with CONFIG_KCOV. This typically requires 2130 disabling instrumentation for some early boot code. 2131 2132config CC_HAS_SANCOV_TRACE_PC 2133 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 2134 2135 2136config KCOV 2137 bool "Code coverage for fuzzing" 2138 depends on ARCH_HAS_KCOV 2139 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 2140 depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \ 2141 GCC_VERSION >= 120000 || CC_IS_CLANG 2142 select DEBUG_FS 2143 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 2144 select OBJTOOL if HAVE_NOINSTR_HACK 2145 help 2146 KCOV exposes kernel code coverage information in a form suitable 2147 for coverage-guided fuzzing (randomized testing). 2148 2149 For more details, see Documentation/dev-tools/kcov.rst. 2150 2151config KCOV_ENABLE_COMPARISONS 2152 bool "Enable comparison operands collection by KCOV" 2153 depends on KCOV 2154 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 2155 help 2156 KCOV also exposes operands of every comparison in the instrumented 2157 code along with operand sizes and PCs of the comparison instructions. 2158 These operands can be used by fuzzing engines to improve the quality 2159 of fuzzing coverage. 2160 2161config KCOV_INSTRUMENT_ALL 2162 bool "Instrument all code by default" 2163 depends on KCOV 2164 default y 2165 help 2166 If you are doing generic system call fuzzing (like e.g. syzkaller), 2167 then you will want to instrument the whole kernel and you should 2168 say y here. If you are doing more targeted fuzzing (like e.g. 2169 filesystem fuzzing with AFL) then you will want to enable coverage 2170 for more specific subsets of files, and should say n here. 2171 2172config KCOV_IRQ_AREA_SIZE 2173 hex "Size of interrupt coverage collection area in words" 2174 depends on KCOV 2175 default 0x40000 2176 help 2177 KCOV uses preallocated per-cpu areas to collect coverage from 2178 soft interrupts. This specifies the size of those areas in the 2179 number of unsigned long words. 2180 2181config KCOV_SELFTEST 2182 bool "Perform short selftests on boot" 2183 depends on KCOV 2184 help 2185 Run short KCOV coverage collection selftests on boot. 2186 On test failure, causes the kernel to panic. Recommended to be 2187 enabled, ensuring critical functionality works as intended. 2188 2189menuconfig RUNTIME_TESTING_MENU 2190 bool "Runtime Testing" 2191 default y 2192 2193if RUNTIME_TESTING_MENU 2194 2195config TEST_DHRY 2196 tristate "Dhrystone benchmark test" 2197 help 2198 Enable this to include the Dhrystone 2.1 benchmark. This test 2199 calculates the number of Dhrystones per second, and the number of 2200 DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided 2201 by 1757 (the number of Dhrystones per second obtained on the VAX 2202 11/780, nominally a 1 MIPS machine). 2203 2204 To run the benchmark, it needs to be enabled explicitly, either from 2205 the kernel command line (when built-in), or from userspace (when 2206 built-in or modular). 2207 2208 Run once during kernel boot: 2209 2210 test_dhry.run 2211 2212 Set number of iterations from kernel command line: 2213 2214 test_dhry.iterations=<n> 2215 2216 Set number of iterations from userspace: 2217 2218 echo <n> > /sys/module/test_dhry/parameters/iterations 2219 2220 Trigger manual run from userspace: 2221 2222 echo y > /sys/module/test_dhry/parameters/run 2223 2224 If the number of iterations is <= 0, the test will devise a suitable 2225 number of iterations (test runs for at least 2s) automatically. 2226 This process takes ca. 4s. 2227 2228 If unsure, say N. 2229 2230config LKDTM 2231 tristate "Linux Kernel Dump Test Tool Module" 2232 depends on DEBUG_FS 2233 help 2234 This module enables testing of the different dumping mechanisms by 2235 inducing system failures at predefined crash points. 2236 If you don't need it: say N 2237 Choose M here to compile this code as a module. The module will be 2238 called lkdtm. 2239 2240 Documentation on how to use the module can be found in 2241 Documentation/fault-injection/provoke-crashes.rst 2242 2243config CPUMASK_KUNIT_TEST 2244 tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS 2245 depends on KUNIT 2246 default KUNIT_ALL_TESTS 2247 help 2248 Enable to turn on cpumask tests, running at boot or module load time. 2249 2250 For more information on KUnit and unit tests in general, please refer 2251 to the KUnit documentation in Documentation/dev-tools/kunit/. 2252 2253 If unsure, say N. 2254 2255config TEST_LIST_SORT 2256 tristate "Linked list sorting test" if !KUNIT_ALL_TESTS 2257 depends on KUNIT 2258 default KUNIT_ALL_TESTS 2259 help 2260 Enable this to turn on 'list_sort()' function test. This test is 2261 executed only once during system boot (so affects only boot time), 2262 or at module load time. 2263 2264 If unsure, say N. 2265 2266config TEST_MIN_HEAP 2267 tristate "Min heap test" 2268 depends on DEBUG_KERNEL || m 2269 help 2270 Enable this to turn on min heap function tests. This test is 2271 executed only once during system boot (so affects only boot time), 2272 or at module load time. 2273 2274 If unsure, say N. 2275 2276config TEST_SORT 2277 tristate "Array-based sort test" if !KUNIT_ALL_TESTS 2278 depends on KUNIT 2279 default KUNIT_ALL_TESTS 2280 help 2281 This option enables the self-test function of 'sort()' at boot, 2282 or at module load time. 2283 2284 If unsure, say N. 2285 2286config TEST_DIV64 2287 tristate "64bit/32bit division and modulo test" 2288 depends on DEBUG_KERNEL || m 2289 help 2290 Enable this to turn on 'do_div()' function test. This test is 2291 executed only once during system boot (so affects only boot time), 2292 or at module load time. 2293 2294 If unsure, say N. 2295 2296config TEST_MULDIV64 2297 tristate "mul_u64_u64_div_u64() test" 2298 depends on DEBUG_KERNEL || m 2299 help 2300 Enable this to turn on 'mul_u64_u64_div_u64()' function test. 2301 This test is executed only once during system boot (so affects 2302 only boot time), or at module load time. 2303 2304 If unsure, say N. 2305 2306config TEST_IOV_ITER 2307 tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS 2308 depends on KUNIT 2309 depends on MMU 2310 default KUNIT_ALL_TESTS 2311 help 2312 Enable this to turn on testing of the operation of the I/O iterator 2313 (iov_iter). This test is executed only once during system boot (so 2314 affects only boot time), or at module load time. 2315 2316 If unsure, say N. 2317 2318config KPROBES_SANITY_TEST 2319 tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS 2320 depends on DEBUG_KERNEL 2321 depends on KPROBES 2322 depends on KUNIT 2323 select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 2324 default KUNIT_ALL_TESTS 2325 help 2326 This option provides for testing basic kprobes functionality on 2327 boot. Samples of kprobe and kretprobe are inserted and 2328 verified for functionality. 2329 2330 Say N if you are unsure. 2331 2332config FPROBE_SANITY_TEST 2333 bool "Self test for fprobe" 2334 depends on DEBUG_KERNEL 2335 depends on FPROBE 2336 depends on KUNIT=y 2337 help 2338 This option will enable testing the fprobe when the system boot. 2339 A series of tests are made to verify that the fprobe is functioning 2340 properly. 2341 2342 Say N if you are unsure. 2343 2344config BACKTRACE_SELF_TEST 2345 tristate "Self test for the backtrace code" 2346 depends on DEBUG_KERNEL 2347 help 2348 This option provides a kernel module that can be used to test 2349 the kernel stack backtrace code. This option is not useful 2350 for distributions or general kernels, but only for kernel 2351 developers working on architecture code. 2352 2353 Note that if you want to also test saved backtraces, you will 2354 have to enable STACKTRACE as well. 2355 2356 Say N if you are unsure. 2357 2358config TEST_REF_TRACKER 2359 tristate "Self test for reference tracker" 2360 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT 2361 select REF_TRACKER 2362 help 2363 This option provides a kernel module performing tests 2364 using reference tracker infrastructure. 2365 2366 Say N if you are unsure. 2367 2368config RBTREE_TEST 2369 tristate "Red-Black tree test" 2370 depends on DEBUG_KERNEL 2371 help 2372 A benchmark measuring the performance of the rbtree library. 2373 Also includes rbtree invariant checks. 2374 2375config REED_SOLOMON_TEST 2376 tristate "Reed-Solomon library test" 2377 depends on DEBUG_KERNEL || m 2378 select REED_SOLOMON 2379 select REED_SOLOMON_ENC16 2380 select REED_SOLOMON_DEC16 2381 help 2382 This option enables the self-test function of rslib at boot, 2383 or at module load time. 2384 2385 If unsure, say N. 2386 2387config INTERVAL_TREE_TEST 2388 tristate "Interval tree test" 2389 depends on DEBUG_KERNEL 2390 select INTERVAL_TREE 2391 help 2392 A benchmark measuring the performance of the interval tree library 2393 2394config PERCPU_TEST 2395 tristate "Per cpu operations test" 2396 depends on m && DEBUG_KERNEL 2397 help 2398 Enable this option to build test module which validates per-cpu 2399 operations. 2400 2401 If unsure, say N. 2402 2403config ATOMIC64_SELFTEST 2404 tristate "Perform an atomic64_t self-test" 2405 help 2406 Enable this option to test the atomic64_t functions at boot or 2407 at module load time. 2408 2409 If unsure, say N. 2410 2411config ASYNC_RAID6_TEST 2412 tristate "Self test for hardware accelerated raid6 recovery" 2413 depends on ASYNC_RAID6_RECOV 2414 select ASYNC_MEMCPY 2415 help 2416 This is a one-shot self test that permutes through the 2417 recovery of all the possible two disk failure scenarios for a 2418 N-disk array. Recovery is performed with the asynchronous 2419 raid6 recovery routines, and will optionally use an offload 2420 engine if one is available. 2421 2422 If unsure, say N. 2423 2424config TEST_HEXDUMP 2425 tristate "Test functions located in the hexdump module at runtime" 2426 2427config STRING_KUNIT_TEST 2428 tristate "KUnit test string functions at runtime" if !KUNIT_ALL_TESTS 2429 depends on KUNIT 2430 default KUNIT_ALL_TESTS 2431 2432config STRING_HELPERS_KUNIT_TEST 2433 tristate "KUnit test string helpers at runtime" if !KUNIT_ALL_TESTS 2434 depends on KUNIT 2435 default KUNIT_ALL_TESTS 2436 2437config TEST_KSTRTOX 2438 tristate "Test kstrto*() family of functions at runtime" 2439 2440config TEST_PRINTF 2441 tristate "Test printf() family of functions at runtime" 2442 2443config TEST_SCANF 2444 tristate "Test scanf() family of functions at runtime" 2445 2446config TEST_BITMAP 2447 tristate "Test bitmap_*() family of functions at runtime" 2448 help 2449 Enable this option to test the bitmap functions at boot. 2450 2451 If unsure, say N. 2452 2453config TEST_UUID 2454 tristate "Test functions located in the uuid module at runtime" 2455 2456config TEST_XARRAY 2457 tristate "Test the XArray code at runtime" 2458 2459config TEST_MAPLE_TREE 2460 tristate "Test the Maple Tree code at runtime or module load" 2461 help 2462 Enable this option to test the maple tree code functions at boot, or 2463 when the module is loaded. Enable "Debug Maple Trees" will enable 2464 more verbose output on failures. 2465 2466 If unsure, say N. 2467 2468config TEST_RHASHTABLE 2469 tristate "Perform selftest on resizable hash table" 2470 help 2471 Enable this option to test the rhashtable functions at boot. 2472 2473 If unsure, say N. 2474 2475config TEST_IDA 2476 tristate "Perform selftest on IDA functions" 2477 2478config TEST_PARMAN 2479 tristate "Perform selftest on priority array manager" 2480 depends on PARMAN 2481 help 2482 Enable this option to test priority array manager on boot 2483 (or module load). 2484 2485 If unsure, say N. 2486 2487config TEST_IRQ_TIMINGS 2488 bool "IRQ timings selftest" 2489 depends on IRQ_TIMINGS 2490 help 2491 Enable this option to test the irq timings code on boot. 2492 2493 If unsure, say N. 2494 2495config TEST_LKM 2496 tristate "Test module loading with 'hello world' module" 2497 depends on m 2498 help 2499 This builds the "test_module" module that emits "Hello, world" 2500 on printk when loaded. It is designed to be used for basic 2501 evaluation of the module loading subsystem (for example when 2502 validating module verification). It lacks any extra dependencies, 2503 and will not normally be loaded by the system unless explicitly 2504 requested by name. 2505 2506 If unsure, say N. 2507 2508config TEST_BITOPS 2509 tristate "Test module for compilation of bitops operations" 2510 help 2511 This builds the "test_bitops" module that is much like the 2512 TEST_LKM module except that it does a basic exercise of the 2513 set/clear_bit macros and get_count_order/long to make sure there are 2514 no compiler warnings from C=1 sparse checker or -Wextra 2515 compilations. It has no dependencies and doesn't run or load unless 2516 explicitly requested by name. for example: modprobe test_bitops. 2517 2518 If unsure, say N. 2519 2520config TEST_VMALLOC 2521 tristate "Test module for stress/performance analysis of vmalloc allocator" 2522 default n 2523 depends on MMU 2524 depends on m 2525 help 2526 This builds the "test_vmalloc" module that should be used for 2527 stress and performance analysis. So, any new change for vmalloc 2528 subsystem can be evaluated from performance and stability point 2529 of view. 2530 2531 If unsure, say N. 2532 2533config TEST_BPF 2534 tristate "Test BPF filter functionality" 2535 depends on m && NET 2536 help 2537 This builds the "test_bpf" module that runs various test vectors 2538 against the BPF interpreter or BPF JIT compiler depending on the 2539 current setting. This is in particular useful for BPF JIT compiler 2540 development, but also to run regression tests against changes in 2541 the interpreter code. It also enables test stubs for eBPF maps and 2542 verifier used by user space verifier testsuite. 2543 2544 If unsure, say N. 2545 2546config TEST_BLACKHOLE_DEV 2547 tristate "Test blackhole netdev functionality" 2548 depends on m && NET 2549 help 2550 This builds the "test_blackhole_dev" module that validates the 2551 data path through this blackhole netdev. 2552 2553 If unsure, say N. 2554 2555config FIND_BIT_BENCHMARK 2556 tristate "Test find_bit functions" 2557 help 2558 This builds the "test_find_bit" module that measure find_*_bit() 2559 functions performance. 2560 2561 If unsure, say N. 2562 2563config TEST_FIRMWARE 2564 tristate "Test firmware loading via userspace interface" 2565 depends on FW_LOADER 2566 help 2567 This builds the "test_firmware" module that creates a userspace 2568 interface for testing firmware loading. This can be used to 2569 control the triggering of firmware loading without needing an 2570 actual firmware-using device. The contents can be rechecked by 2571 userspace. 2572 2573 If unsure, say N. 2574 2575config TEST_SYSCTL 2576 tristate "sysctl test driver" 2577 depends on PROC_SYSCTL 2578 help 2579 This builds the "test_sysctl" module. This driver enables to test the 2580 proc sysctl interfaces available to drivers safely without affecting 2581 production knobs which might alter system functionality. 2582 2583 If unsure, say N. 2584 2585config BITFIELD_KUNIT 2586 tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS 2587 depends on KUNIT 2588 default KUNIT_ALL_TESTS 2589 help 2590 Enable this option to test the bitfield functions at boot. 2591 2592 KUnit tests run during boot and output the results to the debug log 2593 in TAP format (http://testanything.org/). Only useful for kernel devs 2594 running the KUnit test harness, and not intended for inclusion into a 2595 production build. 2596 2597 For more information on KUnit and unit tests in general please refer 2598 to the KUnit documentation in Documentation/dev-tools/kunit/. 2599 2600 If unsure, say N. 2601 2602config CHECKSUM_KUNIT 2603 tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS 2604 depends on KUNIT 2605 default KUNIT_ALL_TESTS 2606 help 2607 Enable this option to test the checksum functions at boot. 2608 2609 KUnit tests run during boot and output the results to the debug log 2610 in TAP format (http://testanything.org/). Only useful for kernel devs 2611 running the KUnit test harness, and not intended for inclusion into a 2612 production build. 2613 2614 For more information on KUnit and unit tests in general please refer 2615 to the KUnit documentation in Documentation/dev-tools/kunit/. 2616 2617 If unsure, say N. 2618 2619config HASH_KUNIT_TEST 2620 tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS 2621 depends on KUNIT 2622 default KUNIT_ALL_TESTS 2623 help 2624 Enable this option to test the kernel's string (<linux/stringhash.h>), and 2625 integer (<linux/hash.h>) hash functions on boot. 2626 2627 KUnit tests run during boot and output the results to the debug log 2628 in TAP format (https://testanything.org/). Only useful for kernel devs 2629 running the KUnit test harness, and not intended for inclusion into a 2630 production build. 2631 2632 For more information on KUnit and unit tests in general please refer 2633 to the KUnit documentation in Documentation/dev-tools/kunit/. 2634 2635 This is intended to help people writing architecture-specific 2636 optimized versions. If unsure, say N. 2637 2638config RESOURCE_KUNIT_TEST 2639 tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS 2640 depends on KUNIT 2641 default KUNIT_ALL_TESTS 2642 select GET_FREE_REGION 2643 help 2644 This builds the resource API unit test. 2645 Tests the logic of API provided by resource.c and ioport.h. 2646 For more information on KUnit and unit tests in general please refer 2647 to the KUnit documentation in Documentation/dev-tools/kunit/. 2648 2649 If unsure, say N. 2650 2651config SYSCTL_KUNIT_TEST 2652 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS 2653 depends on KUNIT 2654 default KUNIT_ALL_TESTS 2655 help 2656 This builds the proc sysctl unit test, which runs on boot. 2657 Tests the API contract and implementation correctness of sysctl. 2658 For more information on KUnit and unit tests in general please refer 2659 to the KUnit documentation in Documentation/dev-tools/kunit/. 2660 2661 If unsure, say N. 2662 2663config LIST_KUNIT_TEST 2664 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS 2665 depends on KUNIT 2666 default KUNIT_ALL_TESTS 2667 help 2668 This builds the linked list KUnit test suite. 2669 It tests that the API and basic functionality of the list_head type 2670 and associated macros. 2671 2672 KUnit tests run during boot and output the results to the debug log 2673 in TAP format (https://testanything.org/). Only useful for kernel devs 2674 running the KUnit test harness, and not intended for inclusion into a 2675 production build. 2676 2677 For more information on KUnit and unit tests in general please refer 2678 to the KUnit documentation in Documentation/dev-tools/kunit/. 2679 2680 If unsure, say N. 2681 2682config HASHTABLE_KUNIT_TEST 2683 tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS 2684 depends on KUNIT 2685 default KUNIT_ALL_TESTS 2686 help 2687 This builds the hashtable KUnit test suite. 2688 It tests the basic functionality of the API defined in 2689 include/linux/hashtable.h. For more information on KUnit and 2690 unit tests in general please refer to the KUnit documentation 2691 in Documentation/dev-tools/kunit/. 2692 2693 If unsure, say N. 2694 2695config LINEAR_RANGES_TEST 2696 tristate "KUnit test for linear_ranges" 2697 depends on KUNIT 2698 select LINEAR_RANGES 2699 help 2700 This builds the linear_ranges unit test, which runs on boot. 2701 Tests the linear_ranges logic correctness. 2702 For more information on KUnit and unit tests in general please refer 2703 to the KUnit documentation in Documentation/dev-tools/kunit/. 2704 2705 If unsure, say N. 2706 2707config CMDLINE_KUNIT_TEST 2708 tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS 2709 depends on KUNIT 2710 default KUNIT_ALL_TESTS 2711 help 2712 This builds the cmdline API unit test. 2713 Tests the logic of API provided by cmdline.c. 2714 For more information on KUnit and unit tests in general please refer 2715 to the KUnit documentation in Documentation/dev-tools/kunit/. 2716 2717 If unsure, say N. 2718 2719config BITS_TEST 2720 tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS 2721 depends on KUNIT 2722 default KUNIT_ALL_TESTS 2723 help 2724 This builds the bits unit test. 2725 Tests the logic of macros defined in bits.h. 2726 For more information on KUnit and unit tests in general please refer 2727 to the KUnit documentation in Documentation/dev-tools/kunit/. 2728 2729 If unsure, say N. 2730 2731config SLUB_KUNIT_TEST 2732 tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS 2733 depends on SLUB_DEBUG && KUNIT 2734 default KUNIT_ALL_TESTS 2735 help 2736 This builds SLUB allocator unit test. 2737 Tests SLUB cache debugging functionality. 2738 For more information on KUnit and unit tests in general please refer 2739 to the KUnit documentation in Documentation/dev-tools/kunit/. 2740 2741 If unsure, say N. 2742 2743config RATIONAL_KUNIT_TEST 2744 tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS 2745 depends on KUNIT && RATIONAL 2746 default KUNIT_ALL_TESTS 2747 help 2748 This builds the rational math unit test. 2749 For more information on KUnit and unit tests in general please refer 2750 to the KUnit documentation in Documentation/dev-tools/kunit/. 2751 2752 If unsure, say N. 2753 2754config MEMCPY_KUNIT_TEST 2755 tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS 2756 depends on KUNIT 2757 default KUNIT_ALL_TESTS 2758 help 2759 Builds unit tests for memcpy(), memmove(), and memset() functions. 2760 For more information on KUnit and unit tests in general please refer 2761 to the KUnit documentation in Documentation/dev-tools/kunit/. 2762 2763 If unsure, say N. 2764 2765config IS_SIGNED_TYPE_KUNIT_TEST 2766 tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS 2767 depends on KUNIT 2768 default KUNIT_ALL_TESTS 2769 help 2770 Builds unit tests for the is_signed_type() macro. 2771 2772 For more information on KUnit and unit tests in general please refer 2773 to the KUnit documentation in Documentation/dev-tools/kunit/. 2774 2775 If unsure, say N. 2776 2777config OVERFLOW_KUNIT_TEST 2778 tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS 2779 depends on KUNIT 2780 default KUNIT_ALL_TESTS 2781 help 2782 Builds unit tests for the check_*_overflow(), size_*(), allocation, and 2783 related functions. 2784 2785 For more information on KUnit and unit tests in general please refer 2786 to the KUnit documentation in Documentation/dev-tools/kunit/. 2787 2788 If unsure, say N. 2789 2790config STACKINIT_KUNIT_TEST 2791 tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS 2792 depends on KUNIT 2793 default KUNIT_ALL_TESTS 2794 help 2795 Test if the kernel is zero-initializing stack variables and 2796 padding. Coverage is controlled by compiler flags, 2797 CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO, 2798 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2799 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2800 2801config FORTIFY_KUNIT_TEST 2802 tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS 2803 depends on KUNIT 2804 default KUNIT_ALL_TESTS 2805 help 2806 Builds unit tests for checking internals of FORTIFY_SOURCE as used 2807 by the str*() and mem*() family of functions. For testing runtime 2808 traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests. 2809 2810config HW_BREAKPOINT_KUNIT_TEST 2811 bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS 2812 depends on HAVE_HW_BREAKPOINT 2813 depends on KUNIT=y 2814 default KUNIT_ALL_TESTS 2815 help 2816 Tests for hw_breakpoint constraints accounting. 2817 2818 If unsure, say N. 2819 2820config SIPHASH_KUNIT_TEST 2821 tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS 2822 depends on KUNIT 2823 default KUNIT_ALL_TESTS 2824 help 2825 Enable this option to test the kernel's siphash (<linux/siphash.h>) hash 2826 functions on boot (or module load). 2827 2828 This is intended to help people writing architecture-specific 2829 optimized versions. If unsure, say N. 2830 2831config USERCOPY_KUNIT_TEST 2832 tristate "KUnit Test for user/kernel boundary protections" 2833 depends on KUNIT 2834 default KUNIT_ALL_TESTS 2835 help 2836 This builds the "usercopy_kunit" module that runs sanity checks 2837 on the copy_to/from_user infrastructure, making sure basic 2838 user/kernel boundary testing is working. 2839 2840config TEST_UDELAY 2841 tristate "udelay test driver" 2842 help 2843 This builds the "udelay_test" module that helps to make sure 2844 that udelay() is working properly. 2845 2846 If unsure, say N. 2847 2848config TEST_STATIC_KEYS 2849 tristate "Test static keys" 2850 depends on m 2851 help 2852 Test the static key interfaces. 2853 2854 If unsure, say N. 2855 2856config TEST_DYNAMIC_DEBUG 2857 tristate "Test DYNAMIC_DEBUG" 2858 depends on DYNAMIC_DEBUG 2859 help 2860 This module registers a tracer callback to count enabled 2861 pr_debugs in a 'do_debugging' function, then alters their 2862 enablements, calls the function, and compares counts. 2863 2864 If unsure, say N. 2865 2866config TEST_KMOD 2867 tristate "kmod stress tester" 2868 depends on m 2869 depends on NETDEVICES && NET_CORE && INET # for TUN 2870 depends on BLOCK 2871 depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS 2872 select TEST_LKM 2873 select XFS_FS 2874 select TUN 2875 select BTRFS_FS 2876 help 2877 Test the kernel's module loading mechanism: kmod. kmod implements 2878 support to load modules using the Linux kernel's usermode helper. 2879 This test provides a series of tests against kmod. 2880 2881 Although technically you can either build test_kmod as a module or 2882 into the kernel we disallow building it into the kernel since 2883 it stress tests request_module() and this will very likely cause 2884 some issues by taking over precious threads available from other 2885 module load requests, ultimately this could be fatal. 2886 2887 To run tests run: 2888 2889 tools/testing/selftests/kmod/kmod.sh --help 2890 2891 If unsure, say N. 2892 2893config TEST_DEBUG_VIRTUAL 2894 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 2895 depends on DEBUG_VIRTUAL 2896 help 2897 Test the kernel's ability to detect incorrect calls to 2898 virt_to_phys() done against the non-linear part of the 2899 kernel's virtual address map. 2900 2901 If unsure, say N. 2902 2903config TEST_MEMCAT_P 2904 tristate "Test memcat_p() helper function" 2905 help 2906 Test the memcat_p() helper for correctly merging two 2907 pointer arrays together. 2908 2909 If unsure, say N. 2910 2911config TEST_OBJAGG 2912 tristate "Perform selftest on object aggreration manager" 2913 default n 2914 depends on OBJAGG 2915 help 2916 Enable this option to test object aggregation manager on boot 2917 (or module load). 2918 2919config TEST_MEMINIT 2920 tristate "Test heap/page initialization" 2921 help 2922 Test if the kernel is zero-initializing heap and page allocations. 2923 This can be useful to test init_on_alloc and init_on_free features. 2924 2925 If unsure, say N. 2926 2927config TEST_HMM 2928 tristate "Test HMM (Heterogeneous Memory Management)" 2929 depends on TRANSPARENT_HUGEPAGE 2930 depends on DEVICE_PRIVATE 2931 select HMM_MIRROR 2932 select MMU_NOTIFIER 2933 help 2934 This is a pseudo device driver solely for testing HMM. 2935 Say M here if you want to build the HMM test module. 2936 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests. 2937 2938 If unsure, say N. 2939 2940config TEST_FREE_PAGES 2941 tristate "Test freeing pages" 2942 help 2943 Test that a memory leak does not occur due to a race between 2944 freeing a block of pages and a speculative page reference. 2945 Loading this module is safe if your kernel has the bug fixed. 2946 If the bug is not fixed, it will leak gigabytes of memory and 2947 probably OOM your system. 2948 2949config TEST_FPU 2950 tristate "Test floating point operations in kernel space" 2951 depends on ARCH_HAS_KERNEL_FPU_SUPPORT && !KCOV_INSTRUMENT_ALL 2952 help 2953 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu 2954 which will trigger a sequence of floating point operations. This is used 2955 for self-testing floating point control register setting in 2956 kernel_fpu_begin(). 2957 2958 If unsure, say N. 2959 2960config TEST_CLOCKSOURCE_WATCHDOG 2961 tristate "Test clocksource watchdog in kernel space" 2962 depends on CLOCKSOURCE_WATCHDOG 2963 help 2964 Enable this option to create a kernel module that will trigger 2965 a test of the clocksource watchdog. This module may be loaded 2966 via modprobe or insmod in which case it will run upon being 2967 loaded, or it may be built in, in which case it will run 2968 shortly after boot. 2969 2970 If unsure, say N. 2971 2972config TEST_OBJPOOL 2973 tristate "Test module for correctness and stress of objpool" 2974 default n 2975 depends on m && DEBUG_KERNEL 2976 help 2977 This builds the "test_objpool" module that should be used for 2978 correctness verification and concurrent testings of objects 2979 allocation and reclamation. 2980 2981 If unsure, say N. 2982 2983endif # RUNTIME_TESTING_MENU 2984 2985config ARCH_USE_MEMTEST 2986 bool 2987 help 2988 An architecture should select this when it uses early_memtest() 2989 during boot process. 2990 2991config MEMTEST 2992 bool "Memtest" 2993 depends on ARCH_USE_MEMTEST 2994 help 2995 This option adds a kernel parameter 'memtest', which allows memtest 2996 to be set and executed. 2997 memtest=0, mean disabled; -- default 2998 memtest=1, mean do 1 test pattern; 2999 ... 3000 memtest=17, mean do 17 test patterns. 3001 If you are unsure how to answer this question, answer N. 3002 3003 3004 3005config HYPERV_TESTING 3006 bool "Microsoft Hyper-V driver testing" 3007 default n 3008 depends on HYPERV && DEBUG_FS 3009 help 3010 Select this option to enable Hyper-V vmbus testing. 3011 3012endmenu # "Kernel Testing and Coverage" 3013 3014menu "Rust hacking" 3015 3016config RUST_DEBUG_ASSERTIONS 3017 bool "Debug assertions" 3018 depends on RUST 3019 help 3020 Enables rustc's `-Cdebug-assertions` codegen option. 3021 3022 This flag lets you turn `cfg(debug_assertions)` conditional 3023 compilation on or off. This can be used to enable extra debugging 3024 code in development but not in production. For example, it controls 3025 the behavior of the standard library's `debug_assert!` macro. 3026 3027 Note that this will apply to all Rust code, including `core`. 3028 3029 If unsure, say N. 3030 3031config RUST_OVERFLOW_CHECKS 3032 bool "Overflow checks" 3033 default y 3034 depends on RUST 3035 help 3036 Enables rustc's `-Coverflow-checks` codegen option. 3037 3038 This flag allows you to control the behavior of runtime integer 3039 overflow. When overflow-checks are enabled, a Rust panic will occur 3040 on overflow. 3041 3042 Note that this will apply to all Rust code, including `core`. 3043 3044 If unsure, say Y. 3045 3046config RUST_BUILD_ASSERT_ALLOW 3047 bool "Allow unoptimized build-time assertions" 3048 depends on RUST 3049 help 3050 Controls how are `build_error!` and `build_assert!` handled during build. 3051 3052 If calls to them exist in the binary, it may indicate a violated invariant 3053 or that the optimizer failed to verify the invariant during compilation. 3054 3055 This should not happen, thus by default the build is aborted. However, 3056 as an escape hatch, you can choose Y here to ignore them during build 3057 and let the check be carried at runtime (with `panic!` being called if 3058 the check fails). 3059 3060 If unsure, say N. 3061 3062config RUST_KERNEL_DOCTESTS 3063 bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS 3064 depends on RUST && KUNIT=y 3065 default KUNIT_ALL_TESTS 3066 help 3067 This builds the documentation tests of the `kernel` crate 3068 as KUnit tests. 3069 3070 For more information on KUnit and unit tests in general, 3071 please refer to the KUnit documentation in Documentation/dev-tools/kunit/. 3072 3073 If unsure, say N. 3074 3075endmenu # "Rust" 3076 3077endmenu # Kernel hacking 3078 3079config INT_POW_TEST 3080 tristate "Integer exponentiation (int_pow) test" if !KUNIT_ALL_TESTS 3081 depends on KUNIT 3082 default KUNIT_ALL_TESTS 3083 help 3084 This option enables the KUnit test suite for the int_pow function, 3085 which performs integer exponentiation. The test suite is designed to 3086 verify that the implementation of int_pow correctly computes the power 3087 of a given base raised to a given exponent. 3088 3089 Enabling this option will include tests that check various scenarios 3090 and edge cases to ensure the accuracy and reliability of the exponentiation 3091 function. 3092 3093 If unsure, say N 3094