1 # SPDX-License-Identifier: GPL-2.0-only 2 menu "Kernel hacking" 3 4 menu "printk and dmesg options" 5 6 config PRINTK_TIME 7 bool "Show timing information on printks" 8 depends on PRINTK 9 help 10 Selecting this option causes time stamps of the printk() 11 messages to be added to the output of the syslog() system 12 call and at the console. 13 14 The timestamp is always recorded internally, and exported 15 to /dev/kmsg. This flag just specifies if the timestamp should 16 be included, not that the timestamp is recorded. 17 18 The behavior is also controlled by the kernel command line 19 parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst 20 21 config PRINTK_CALLER 22 bool "Show caller information on printks" 23 depends on PRINTK 24 help 25 Selecting this option causes printk() to add a caller "thread id" (if 26 in task context) or a caller "processor id" (if not in task context) 27 to every message. 28 29 This option is intended for environments where multiple threads 30 concurrently call printk() for many times, for it is difficult to 31 interpret without knowing where these lines (or sometimes individual 32 line which was divided into multiple lines due to race) came from. 33 34 Since toggling after boot makes the code racy, currently there is 35 no option to enable/disable at the kernel command line parameter or 36 sysfs interface. 37 38 config 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 49 config 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 64 config 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 75 config 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 90 config 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. 107 108 config 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. 179 180 config 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. 190 191 config 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. 199 200 config 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. 208 209 endmenu # "printk and dmesg options" 210 211 config 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. 216 217 config 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. 224 225 menu "Compile-time checks and compiler options" 226 227 config 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 237 config AS_HAS_NON_CONST_ULEB128 238 def_bool $(as-instr,.uleb128 .Lexpr_end4 - .Lexpr_start3\n.Lexpr_start3:\n.Lexpr_end4:) 239 240 choice 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". 252 253 config 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. 258 259 config 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. 270 271 config 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. 282 283 config 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. 300 301 endchoice # "Debug information" 302 303 if DEBUG_INFO 304 305 config 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. 316 317 choice 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. 324 325 config DEBUG_INFO_COMPRESSED_NONE 326 bool "Don't compress debug information" 327 help 328 Don't compress debug info sections. 329 330 config 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. 344 345 config 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. 354 355 endchoice # "Compressed Debug information" 356 357 config 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. 376 377 config 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. 391 392 config PAHOLE_HAS_SPLIT_BTF 393 def_bool PAHOLE_VERSION >= 119 394 395 config 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. 402 403 config 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. 411 412 config 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. 418 419 config 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. 428 429 config 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. 438 439 endif # DEBUG_INFO 440 441 config 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. 455 456 config 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. 463 464 config 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. 473 474 config 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. 483 484 config 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). 505 506 config 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. 514 515 config 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 # 533 config ARCH_WANT_FRAME_POINTERS 534 bool 535 536 config 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) 544 545 config OBJTOOL 546 bool 547 548 config 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. 559 560 config NOINSTR_VALIDATION 561 bool 562 depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY 563 select OBJTOOL 564 default y 565 566 config 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. 575 576 config 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. 590 591 config 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. 605 606 endmenu # "Compiler options" 607 608 menu "Generic Kernel Debugging Instruments" 609 610 config 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. 623 624 config 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. 632 633 config 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. 642 643 config 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. 652 653 config 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. 664 665 choice 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. 674 675 config 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. 680 681 config 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. 687 688 config 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. 694 695 endchoice 696 697 source "lib/Kconfig.kgdb" 698 source "lib/Kconfig.ubsan" 699 source "lib/Kconfig.kcsan" 700 701 endmenu 702 703 menu "Networking Debugging" 704 705 source "net/Kconfig.debug" 706 707 endmenu # "Networking Debugging" 708 709 menu "Memory Debugging" 710 711 source "mm/Kconfig.debug" 712 713 config 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. 720 721 config 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. 726 727 config 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. 735 736 config 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. 743 744 config 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. 751 752 config 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). 757 758 config 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. 765 766 config 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 773 774 config 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. 781 782 config 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. 792 793 config 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. 804 805 config 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. 810 811 config DEBUG_VM_IRQSOFF 812 def_bool DEBUG_VM && !PREEMPT_RT 813 814 config 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. 822 823 config 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. 832 833 config 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. 841 842 config 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. 849 850 config 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. 857 858 config 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. 873 874 config ARCH_HAS_DEBUG_VIRTUAL 875 bool 876 877 config 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. 885 886 config 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. 892 893 config 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 904 905 config 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. 927 928 config 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. 938 939 config 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. 945 946 config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 947 bool 948 949 config 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! 958 959 config 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. 967 968 config HAVE_DEBUG_STACKOVERFLOW 969 bool 970 971 config 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". 988 989 config CODE_TAGGING 990 bool 991 select KALLSYMS 992 993 config 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 1006 config MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT 1007 bool "Enable memory allocation profiling by default" 1008 default y 1009 depends on MEM_ALLOC_PROFILING 1010 1011 config 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 1020 source "lib/Kconfig.kasan" 1021 source "lib/Kconfig.kfence" 1022 source "lib/Kconfig.kmsan" 1023 1024 endmenu # "Memory Debugging" 1025 1026 config 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 1035 menu "Debug Oops, Lockups and Hangs" 1036 1037 config 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 1050 config 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 1056 config 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 1067 config LOCKUP_DETECTOR 1068 bool 1069 1070 config 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 1083 config 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 1097 config 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 1114 config 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 # 1129 config 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 # 1150 config 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 1166 config 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 1173 config 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 1181 config 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 # 1193 config 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 # 1201 config HARDLOCKUP_CHECK_TIMESTAMP 1202 bool 1203 1204 config 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 1215 config 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 1230 config 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 1246 config 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 1262 config 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 1273 config 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 1286 config 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 1299 endmenu # "Debug lockups and hangs" 1300 1301 menu "Scheduler Debugging" 1302 1303 config 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 1312 config SCHED_INFO 1313 bool 1314 default n 1315 1316 config 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 1329 endmenu 1330 1331 config DEBUG_TIMEKEEPING 1332 bool "Enable extra timekeeping sanity checking" 1333 help 1334 This option will enable additional timekeeping sanity checks 1335 which may be helpful when diagnosing issues where timekeeping 1336 problems are suspected. 1337 1338 This may include checks in the timekeeping hotpaths, so this 1339 option may have a (very small) performance impact to some 1340 workloads. 1341 1342 If unsure, say N. 1343 1344 config DEBUG_PREEMPT 1345 bool "Debug preemptible kernel" 1346 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1347 help 1348 If you say Y here then the kernel will use a debug variant of the 1349 commonly used smp_processor_id() function and will print warnings 1350 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1351 will detect preemption count underflows. 1352 1353 This option has potential to introduce high runtime overhead, 1354 depending on workload as it triggers debugging routines for each 1355 this_cpu operation. It should only be used for debugging purposes. 1356 1357 menu "Lock Debugging (spinlocks, mutexes, etc...)" 1358 1359 config LOCK_DEBUGGING_SUPPORT 1360 bool 1361 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1362 default y 1363 1364 config PROVE_LOCKING 1365 bool "Lock debugging: prove locking correctness" 1366 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1367 select LOCKDEP 1368 select DEBUG_SPINLOCK 1369 select DEBUG_MUTEXES if !PREEMPT_RT 1370 select DEBUG_RT_MUTEXES if RT_MUTEXES 1371 select DEBUG_RWSEMS if !PREEMPT_RT 1372 select DEBUG_WW_MUTEX_SLOWPATH 1373 select DEBUG_LOCK_ALLOC 1374 select PREEMPT_COUNT if !ARCH_NO_PREEMPT 1375 select TRACE_IRQFLAGS 1376 default n 1377 help 1378 This feature enables the kernel to prove that all locking 1379 that occurs in the kernel runtime is mathematically 1380 correct: that under no circumstance could an arbitrary (and 1381 not yet triggered) combination of observed locking 1382 sequences (on an arbitrary number of CPUs, running an 1383 arbitrary number of tasks and interrupt contexts) cause a 1384 deadlock. 1385 1386 In short, this feature enables the kernel to report locking 1387 related deadlocks before they actually occur. 1388 1389 The proof does not depend on how hard and complex a 1390 deadlock scenario would be to trigger: how many 1391 participant CPUs, tasks and irq-contexts would be needed 1392 for it to trigger. The proof also does not depend on 1393 timing: if a race and a resulting deadlock is possible 1394 theoretically (no matter how unlikely the race scenario 1395 is), it will be proven so and will immediately be 1396 reported by the kernel (once the event is observed that 1397 makes the deadlock theoretically possible). 1398 1399 If a deadlock is impossible (i.e. the locking rules, as 1400 observed by the kernel, are mathematically correct), the 1401 kernel reports nothing. 1402 1403 NOTE: this feature can also be enabled for rwlocks, mutexes 1404 and rwsems - in which case all dependencies between these 1405 different locking variants are observed and mapped too, and 1406 the proof of observed correctness is also maintained for an 1407 arbitrary combination of these separate locking variants. 1408 1409 For more details, see Documentation/locking/lockdep-design.rst. 1410 1411 config PROVE_RAW_LOCK_NESTING 1412 bool "Enable raw_spinlock - spinlock nesting checks" 1413 depends on PROVE_LOCKING 1414 default n 1415 help 1416 Enable the raw_spinlock vs. spinlock nesting checks which ensure 1417 that the lock nesting rules for PREEMPT_RT enabled kernels are 1418 not violated. 1419 1420 NOTE: There are known nesting problems. So if you enable this 1421 option expect lockdep splats until these problems have been fully 1422 addressed which is work in progress. This config switch allows to 1423 identify and analyze these problems. It will be removed and the 1424 check permanently enabled once the main issues have been fixed. 1425 1426 If unsure, select N. 1427 1428 config LOCK_STAT 1429 bool "Lock usage statistics" 1430 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1431 select LOCKDEP 1432 select DEBUG_SPINLOCK 1433 select DEBUG_MUTEXES if !PREEMPT_RT 1434 select DEBUG_RT_MUTEXES if RT_MUTEXES 1435 select DEBUG_LOCK_ALLOC 1436 default n 1437 help 1438 This feature enables tracking lock contention points 1439 1440 For more details, see Documentation/locking/lockstat.rst 1441 1442 This also enables lock events required by "perf lock", 1443 subcommand of perf. 1444 If you want to use "perf lock", you also need to turn on 1445 CONFIG_EVENT_TRACING. 1446 1447 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1448 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1449 1450 config DEBUG_RT_MUTEXES 1451 bool "RT Mutex debugging, deadlock detection" 1452 depends on DEBUG_KERNEL && RT_MUTEXES 1453 help 1454 This allows rt mutex semantics violations and rt mutex related 1455 deadlocks (lockups) to be detected and reported automatically. 1456 1457 config DEBUG_SPINLOCK 1458 bool "Spinlock and rw-lock debugging: basic checks" 1459 depends on DEBUG_KERNEL 1460 select UNINLINE_SPIN_UNLOCK 1461 help 1462 Say Y here and build SMP to catch missing spinlock initialization 1463 and certain other kinds of spinlock errors commonly made. This is 1464 best used in conjunction with the NMI watchdog so that spinlock 1465 deadlocks are also debuggable. 1466 1467 config DEBUG_MUTEXES 1468 bool "Mutex debugging: basic checks" 1469 depends on DEBUG_KERNEL && !PREEMPT_RT 1470 help 1471 This feature allows mutex semantics violations to be detected and 1472 reported. 1473 1474 config DEBUG_WW_MUTEX_SLOWPATH 1475 bool "Wait/wound mutex debugging: Slowpath testing" 1476 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1477 select DEBUG_LOCK_ALLOC 1478 select DEBUG_SPINLOCK 1479 select DEBUG_MUTEXES if !PREEMPT_RT 1480 select DEBUG_RT_MUTEXES if PREEMPT_RT 1481 help 1482 This feature enables slowpath testing for w/w mutex users by 1483 injecting additional -EDEADLK wound/backoff cases. Together with 1484 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1485 will test all possible w/w mutex interface abuse with the 1486 exception of simply not acquiring all the required locks. 1487 Note that this feature can introduce significant overhead, so 1488 it really should not be enabled in a production or distro kernel, 1489 even a debug kernel. If you are a driver writer, enable it. If 1490 you are a distro, do not. 1491 1492 config DEBUG_RWSEMS 1493 bool "RW Semaphore debugging: basic checks" 1494 depends on DEBUG_KERNEL && !PREEMPT_RT 1495 help 1496 This debugging feature allows mismatched rw semaphore locks 1497 and unlocks to be detected and reported. 1498 1499 config DEBUG_LOCK_ALLOC 1500 bool "Lock debugging: detect incorrect freeing of live locks" 1501 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1502 select DEBUG_SPINLOCK 1503 select DEBUG_MUTEXES if !PREEMPT_RT 1504 select DEBUG_RT_MUTEXES if RT_MUTEXES 1505 select LOCKDEP 1506 help 1507 This feature will check whether any held lock (spinlock, rwlock, 1508 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1509 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1510 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1511 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1512 held during task exit. 1513 1514 config LOCKDEP 1515 bool 1516 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1517 select STACKTRACE 1518 select KALLSYMS 1519 select KALLSYMS_ALL 1520 1521 config LOCKDEP_SMALL 1522 bool 1523 1524 config LOCKDEP_BITS 1525 int "Bitsize for MAX_LOCKDEP_ENTRIES" 1526 depends on LOCKDEP && !LOCKDEP_SMALL 1527 range 10 30 1528 default 15 1529 help 1530 Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message. 1531 1532 config LOCKDEP_CHAINS_BITS 1533 int "Bitsize for MAX_LOCKDEP_CHAINS" 1534 depends on LOCKDEP && !LOCKDEP_SMALL 1535 range 10 21 1536 default 16 1537 help 1538 Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message. 1539 1540 config LOCKDEP_STACK_TRACE_BITS 1541 int "Bitsize for MAX_STACK_TRACE_ENTRIES" 1542 depends on LOCKDEP && !LOCKDEP_SMALL 1543 range 10 30 1544 default 19 1545 help 1546 Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message. 1547 1548 config LOCKDEP_STACK_TRACE_HASH_BITS 1549 int "Bitsize for STACK_TRACE_HASH_SIZE" 1550 depends on LOCKDEP && !LOCKDEP_SMALL 1551 range 10 30 1552 default 14 1553 help 1554 Try increasing this value if you need large STACK_TRACE_HASH_SIZE. 1555 1556 config LOCKDEP_CIRCULAR_QUEUE_BITS 1557 int "Bitsize for elements in circular_queue struct" 1558 depends on LOCKDEP 1559 range 10 30 1560 default 12 1561 help 1562 Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure. 1563 1564 config DEBUG_LOCKDEP 1565 bool "Lock dependency engine debugging" 1566 depends on DEBUG_KERNEL && LOCKDEP 1567 select DEBUG_IRQFLAGS 1568 help 1569 If you say Y here, the lock dependency engine will do 1570 additional runtime checks to debug itself, at the price 1571 of more runtime overhead. 1572 1573 config DEBUG_ATOMIC_SLEEP 1574 bool "Sleep inside atomic section checking" 1575 select PREEMPT_COUNT 1576 depends on DEBUG_KERNEL 1577 depends on !ARCH_NO_PREEMPT 1578 help 1579 If you say Y here, various routines which may sleep will become very 1580 noisy if they are called inside atomic sections: when a spinlock is 1581 held, inside an rcu read side critical section, inside preempt disabled 1582 sections, inside an interrupt, etc... 1583 1584 config DEBUG_LOCKING_API_SELFTESTS 1585 bool "Locking API boot-time self-tests" 1586 depends on DEBUG_KERNEL 1587 help 1588 Say Y here if you want the kernel to run a short self-test during 1589 bootup. The self-test checks whether common types of locking bugs 1590 are detected by debugging mechanisms or not. (if you disable 1591 lock debugging then those bugs won't be detected of course.) 1592 The following locking APIs are covered: spinlocks, rwlocks, 1593 mutexes and rwsems. 1594 1595 config LOCK_TORTURE_TEST 1596 tristate "torture tests for locking" 1597 depends on DEBUG_KERNEL 1598 select TORTURE_TEST 1599 help 1600 This option provides a kernel module that runs torture tests 1601 on kernel locking primitives. The kernel module may be built 1602 after the fact on the running kernel to be tested, if desired. 1603 1604 Say Y here if you want kernel locking-primitive torture tests 1605 to be built into the kernel. 1606 Say M if you want these torture tests to build as a module. 1607 Say N if you are unsure. 1608 1609 config WW_MUTEX_SELFTEST 1610 tristate "Wait/wound mutex selftests" 1611 help 1612 This option provides a kernel module that runs tests on the 1613 on the struct ww_mutex locking API. 1614 1615 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1616 with this test harness. 1617 1618 Say M if you want these self tests to build as a module. 1619 Say N if you are unsure. 1620 1621 config SCF_TORTURE_TEST 1622 tristate "torture tests for smp_call_function*()" 1623 depends on DEBUG_KERNEL 1624 select TORTURE_TEST 1625 help 1626 This option provides a kernel module that runs torture tests 1627 on the smp_call_function() family of primitives. The kernel 1628 module may be built after the fact on the running kernel to 1629 be tested, if desired. 1630 1631 config CSD_LOCK_WAIT_DEBUG 1632 bool "Debugging for csd_lock_wait(), called from smp_call_function*()" 1633 depends on DEBUG_KERNEL 1634 depends on SMP 1635 depends on 64BIT 1636 default n 1637 help 1638 This option enables debug prints when CPUs are slow to respond 1639 to the smp_call_function*() IPI wrappers. These debug prints 1640 include the IPI handler function currently executing (if any) 1641 and relevant stack traces. 1642 1643 config CSD_LOCK_WAIT_DEBUG_DEFAULT 1644 bool "Default csd_lock_wait() debugging on at boot time" 1645 depends on CSD_LOCK_WAIT_DEBUG 1646 depends on 64BIT 1647 default n 1648 help 1649 This option causes the csdlock_debug= kernel boot parameter to 1650 default to 1 (basic debugging) instead of 0 (no debugging). 1651 1652 endmenu # lock debugging 1653 1654 config TRACE_IRQFLAGS 1655 depends on TRACE_IRQFLAGS_SUPPORT 1656 bool 1657 help 1658 Enables hooks to interrupt enabling and disabling for 1659 either tracing or lock debugging. 1660 1661 config TRACE_IRQFLAGS_NMI 1662 def_bool y 1663 depends on TRACE_IRQFLAGS 1664 depends on TRACE_IRQFLAGS_NMI_SUPPORT 1665 1666 config NMI_CHECK_CPU 1667 bool "Debugging for CPUs failing to respond to backtrace requests" 1668 depends on DEBUG_KERNEL 1669 depends on X86 1670 default n 1671 help 1672 Enables debug prints when a CPU fails to respond to a given 1673 backtrace NMI. These prints provide some reasons why a CPU 1674 might legitimately be failing to respond, for example, if it 1675 is offline of if ignore_nmis is set. 1676 1677 config DEBUG_IRQFLAGS 1678 bool "Debug IRQ flag manipulation" 1679 help 1680 Enables checks for potentially unsafe enabling or disabling of 1681 interrupts, such as calling raw_local_irq_restore() when interrupts 1682 are enabled. 1683 1684 config STACKTRACE 1685 bool "Stack backtrace support" 1686 depends on STACKTRACE_SUPPORT 1687 help 1688 This option causes the kernel to create a /proc/pid/stack for 1689 every process, showing its current stack trace. 1690 It is also used by various kernel debugging features that require 1691 stack trace generation. 1692 1693 config WARN_ALL_UNSEEDED_RANDOM 1694 bool "Warn for all uses of unseeded randomness" 1695 default n 1696 help 1697 Some parts of the kernel contain bugs relating to their use of 1698 cryptographically secure random numbers before it's actually possible 1699 to generate those numbers securely. This setting ensures that these 1700 flaws don't go unnoticed, by enabling a message, should this ever 1701 occur. This will allow people with obscure setups to know when things 1702 are going wrong, so that they might contact developers about fixing 1703 it. 1704 1705 Unfortunately, on some models of some architectures getting 1706 a fully seeded CRNG is extremely difficult, and so this can 1707 result in dmesg getting spammed for a surprisingly long 1708 time. This is really bad from a security perspective, and 1709 so architecture maintainers really need to do what they can 1710 to get the CRNG seeded sooner after the system is booted. 1711 However, since users cannot do anything actionable to 1712 address this, by default this option is disabled. 1713 1714 Say Y here if you want to receive warnings for all uses of 1715 unseeded randomness. This will be of use primarily for 1716 those developers interested in improving the security of 1717 Linux kernels running on their architecture (or 1718 subarchitecture). 1719 1720 config DEBUG_KOBJECT 1721 bool "kobject debugging" 1722 depends on DEBUG_KERNEL 1723 help 1724 If you say Y here, some extra kobject debugging messages will be sent 1725 to the syslog. 1726 1727 config DEBUG_KOBJECT_RELEASE 1728 bool "kobject release debugging" 1729 depends on DEBUG_OBJECTS_TIMERS 1730 help 1731 kobjects are reference counted objects. This means that their 1732 last reference count put is not predictable, and the kobject can 1733 live on past the point at which a driver decides to drop its 1734 initial reference to the kobject gained on allocation. An 1735 example of this would be a struct device which has just been 1736 unregistered. 1737 1738 However, some buggy drivers assume that after such an operation, 1739 the memory backing the kobject can be immediately freed. This 1740 goes completely against the principles of a refcounted object. 1741 1742 If you say Y here, the kernel will delay the release of kobjects 1743 on the last reference count to improve the visibility of this 1744 kind of kobject release bug. 1745 1746 config HAVE_DEBUG_BUGVERBOSE 1747 bool 1748 1749 menu "Debug kernel data structures" 1750 1751 config DEBUG_LIST 1752 bool "Debug linked list manipulation" 1753 depends on DEBUG_KERNEL 1754 select LIST_HARDENED 1755 help 1756 Enable this to turn on extended checks in the linked-list walking 1757 routines. 1758 1759 This option trades better quality error reports for performance, and 1760 is more suitable for kernel debugging. If you care about performance, 1761 you should only enable CONFIG_LIST_HARDENED instead. 1762 1763 If unsure, say N. 1764 1765 config DEBUG_PLIST 1766 bool "Debug priority linked list manipulation" 1767 depends on DEBUG_KERNEL 1768 help 1769 Enable this to turn on extended checks in the priority-ordered 1770 linked-list (plist) walking routines. This checks the entire 1771 list multiple times during each manipulation. 1772 1773 If unsure, say N. 1774 1775 config DEBUG_SG 1776 bool "Debug SG table operations" 1777 depends on DEBUG_KERNEL 1778 help 1779 Enable this to turn on checks on scatter-gather tables. This can 1780 help find problems with drivers that do not properly initialize 1781 their sg tables. 1782 1783 If unsure, say N. 1784 1785 config DEBUG_NOTIFIERS 1786 bool "Debug notifier call chains" 1787 depends on DEBUG_KERNEL 1788 help 1789 Enable this to turn on sanity checking for notifier call chains. 1790 This is most useful for kernel developers to make sure that 1791 modules properly unregister themselves from notifier chains. 1792 This is a relatively cheap check but if you care about maximum 1793 performance, say N. 1794 1795 config DEBUG_CLOSURES 1796 bool "Debug closures (bcache async widgits)" 1797 depends on CLOSURES 1798 select DEBUG_FS 1799 help 1800 Keeps all active closures in a linked list and provides a debugfs 1801 interface to list them, which makes it possible to see asynchronous 1802 operations that get stuck. 1803 1804 config DEBUG_MAPLE_TREE 1805 bool "Debug maple trees" 1806 depends on DEBUG_KERNEL 1807 help 1808 Enable maple tree debugging information and extra validations. 1809 1810 If unsure, say N. 1811 1812 endmenu 1813 1814 source "kernel/rcu/Kconfig.debug" 1815 1816 config DEBUG_WQ_FORCE_RR_CPU 1817 bool "Force round-robin CPU selection for unbound work items" 1818 depends on DEBUG_KERNEL 1819 default n 1820 help 1821 Workqueue used to implicitly guarantee that work items queued 1822 without explicit CPU specified are put on the local CPU. This 1823 guarantee is no longer true and while local CPU is still 1824 preferred work items may be put on foreign CPUs. Kernel 1825 parameter "workqueue.debug_force_rr_cpu" is added to force 1826 round-robin CPU selection to flush out usages which depend on the 1827 now broken guarantee. This config option enables the debug 1828 feature by default. When enabled, memory and cache locality will 1829 be impacted. 1830 1831 config CPU_HOTPLUG_STATE_CONTROL 1832 bool "Enable CPU hotplug state control" 1833 depends on DEBUG_KERNEL 1834 depends on HOTPLUG_CPU 1835 default n 1836 help 1837 Allows to write steps between "offline" and "online" to the CPUs 1838 sysfs target file so states can be stepped granular. This is a debug 1839 option for now as the hotplug machinery cannot be stopped and 1840 restarted at arbitrary points yet. 1841 1842 Say N if your are unsure. 1843 1844 config LATENCYTOP 1845 bool "Latency measuring infrastructure" 1846 depends on DEBUG_KERNEL 1847 depends on STACKTRACE_SUPPORT 1848 depends on PROC_FS 1849 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 1850 select KALLSYMS 1851 select KALLSYMS_ALL 1852 select STACKTRACE 1853 select SCHEDSTATS 1854 help 1855 Enable this option if you want to use the LatencyTOP tool 1856 to find out which userspace is blocking on what kernel operations. 1857 1858 config DEBUG_CGROUP_REF 1859 bool "Disable inlining of cgroup css reference count functions" 1860 depends on DEBUG_KERNEL 1861 depends on CGROUPS 1862 depends on KPROBES 1863 default n 1864 help 1865 Force cgroup css reference count functions to not be inlined so 1866 that they can be kprobed for debugging. 1867 1868 source "kernel/trace/Kconfig" 1869 1870 config PROVIDE_OHCI1394_DMA_INIT 1871 bool "Remote debugging over FireWire early on boot" 1872 depends on PCI && X86 1873 help 1874 If you want to debug problems which hang or crash the kernel early 1875 on boot and the crashing machine has a FireWire port, you can use 1876 this feature to remotely access the memory of the crashed machine 1877 over FireWire. This employs remote DMA as part of the OHCI1394 1878 specification which is now the standard for FireWire controllers. 1879 1880 With remote DMA, you can monitor the printk buffer remotely using 1881 firescope and access all memory below 4GB using fireproxy from gdb. 1882 Even controlling a kernel debugger is possible using remote DMA. 1883 1884 Usage: 1885 1886 If ohci1394_dma=early is used as boot parameter, it will initialize 1887 all OHCI1394 controllers which are found in the PCI config space. 1888 1889 As all changes to the FireWire bus such as enabling and disabling 1890 devices cause a bus reset and thereby disable remote DMA for all 1891 devices, be sure to have the cable plugged and FireWire enabled on 1892 the debugging host before booting the debug target for debugging. 1893 1894 This code (~1k) is freed after boot. By then, the firewire stack 1895 in charge of the OHCI-1394 controllers should be used instead. 1896 1897 See Documentation/core-api/debugging-via-ohci1394.rst for more information. 1898 1899 source "samples/Kconfig" 1900 1901 config ARCH_HAS_DEVMEM_IS_ALLOWED 1902 bool 1903 1904 config STRICT_DEVMEM 1905 bool "Filter access to /dev/mem" 1906 depends on MMU && DEVMEM 1907 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED 1908 default y if PPC || X86 || ARM64 1909 help 1910 If this option is disabled, you allow userspace (root) access to all 1911 of memory, including kernel and userspace memory. Accidental 1912 access to this is obviously disastrous, but specific access can 1913 be used by people debugging the kernel. Note that with PAT support 1914 enabled, even in this case there are restrictions on /dev/mem 1915 use due to the cache aliasing requirements. 1916 1917 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 1918 file only allows userspace access to PCI space and the BIOS code and 1919 data regions. This is sufficient for dosemu and X and all common 1920 users of /dev/mem. 1921 1922 If in doubt, say Y. 1923 1924 config IO_STRICT_DEVMEM 1925 bool "Filter I/O access to /dev/mem" 1926 depends on STRICT_DEVMEM 1927 help 1928 If this option is disabled, you allow userspace (root) access to all 1929 io-memory regardless of whether a driver is actively using that 1930 range. Accidental access to this is obviously disastrous, but 1931 specific access can be used by people debugging kernel drivers. 1932 1933 If this option is switched on, the /dev/mem file only allows 1934 userspace access to *idle* io-memory ranges (see /proc/iomem) This 1935 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 1936 if the driver using a given range cannot be disabled. 1937 1938 If in doubt, say Y. 1939 1940 menu "$(SRCARCH) Debugging" 1941 1942 source "arch/$(SRCARCH)/Kconfig.debug" 1943 1944 endmenu 1945 1946 menu "Kernel Testing and Coverage" 1947 1948 source "lib/kunit/Kconfig" 1949 1950 config NOTIFIER_ERROR_INJECTION 1951 tristate "Notifier error injection" 1952 depends on DEBUG_KERNEL 1953 select DEBUG_FS 1954 help 1955 This option provides the ability to inject artificial errors to 1956 specified notifier chain callbacks. It is useful to test the error 1957 handling of notifier call chain failures. 1958 1959 Say N if unsure. 1960 1961 config PM_NOTIFIER_ERROR_INJECT 1962 tristate "PM notifier error injection module" 1963 depends on PM && NOTIFIER_ERROR_INJECTION 1964 default m if PM_DEBUG 1965 help 1966 This option provides the ability to inject artificial errors to 1967 PM notifier chain callbacks. It is controlled through debugfs 1968 interface /sys/kernel/debug/notifier-error-inject/pm 1969 1970 If the notifier call chain should be failed with some events 1971 notified, write the error code to "actions/<notifier event>/error". 1972 1973 Example: Inject PM suspend error (-12 = -ENOMEM) 1974 1975 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1976 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1977 # echo mem > /sys/power/state 1978 bash: echo: write error: Cannot allocate memory 1979 1980 To compile this code as a module, choose M here: the module will 1981 be called pm-notifier-error-inject. 1982 1983 If unsure, say N. 1984 1985 config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1986 tristate "OF reconfig notifier error injection module" 1987 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1988 help 1989 This option provides the ability to inject artificial errors to 1990 OF reconfig notifier chain callbacks. It is controlled 1991 through debugfs interface under 1992 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1993 1994 If the notifier call chain should be failed with some events 1995 notified, write the error code to "actions/<notifier event>/error". 1996 1997 To compile this code as a module, choose M here: the module will 1998 be called of-reconfig-notifier-error-inject. 1999 2000 If unsure, say N. 2001 2002 config NETDEV_NOTIFIER_ERROR_INJECT 2003 tristate "Netdev notifier error injection module" 2004 depends on NET && NOTIFIER_ERROR_INJECTION 2005 help 2006 This option provides the ability to inject artificial errors to 2007 netdevice notifier chain callbacks. It is controlled through debugfs 2008 interface /sys/kernel/debug/notifier-error-inject/netdev 2009 2010 If the notifier call chain should be failed with some events 2011 notified, write the error code to "actions/<notifier event>/error". 2012 2013 Example: Inject netdevice mtu change error (-22 = -EINVAL) 2014 2015 # cd /sys/kernel/debug/notifier-error-inject/netdev 2016 # echo -22 > actions/NETDEV_CHANGEMTU/error 2017 # ip link set eth0 mtu 1024 2018 RTNETLINK answers: Invalid argument 2019 2020 To compile this code as a module, choose M here: the module will 2021 be called netdev-notifier-error-inject. 2022 2023 If unsure, say N. 2024 2025 config FUNCTION_ERROR_INJECTION 2026 bool "Fault-injections of functions" 2027 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 2028 help 2029 Add fault injections into various functions that are annotated with 2030 ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return 2031 value of these functions. This is useful to test error paths of code. 2032 2033 If unsure, say N 2034 2035 config FAULT_INJECTION 2036 bool "Fault-injection framework" 2037 depends on DEBUG_KERNEL 2038 help 2039 Provide fault-injection framework. 2040 For more details, see Documentation/fault-injection/. 2041 2042 config FAILSLAB 2043 bool "Fault-injection capability for kmalloc" 2044 depends on FAULT_INJECTION 2045 help 2046 Provide fault-injection capability for kmalloc. 2047 2048 config FAIL_PAGE_ALLOC 2049 bool "Fault-injection capability for alloc_pages()" 2050 depends on FAULT_INJECTION 2051 help 2052 Provide fault-injection capability for alloc_pages(). 2053 2054 config FAULT_INJECTION_USERCOPY 2055 bool "Fault injection capability for usercopy functions" 2056 depends on FAULT_INJECTION 2057 help 2058 Provides fault-injection capability to inject failures 2059 in usercopy functions (copy_from_user(), get_user(), ...). 2060 2061 config FAIL_MAKE_REQUEST 2062 bool "Fault-injection capability for disk IO" 2063 depends on FAULT_INJECTION && BLOCK 2064 help 2065 Provide fault-injection capability for disk IO. 2066 2067 config FAIL_IO_TIMEOUT 2068 bool "Fault-injection capability for faking disk interrupts" 2069 depends on FAULT_INJECTION && BLOCK 2070 help 2071 Provide fault-injection capability on end IO handling. This 2072 will make the block layer "forget" an interrupt as configured, 2073 thus exercising the error handling. 2074 2075 Only works with drivers that use the generic timeout handling, 2076 for others it won't do anything. 2077 2078 config FAIL_FUTEX 2079 bool "Fault-injection capability for futexes" 2080 select DEBUG_FS 2081 depends on FAULT_INJECTION && FUTEX 2082 help 2083 Provide fault-injection capability for futexes. 2084 2085 config FAULT_INJECTION_DEBUG_FS 2086 bool "Debugfs entries for fault-injection capabilities" 2087 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 2088 help 2089 Enable configuration of fault-injection capabilities via debugfs. 2090 2091 config FAIL_FUNCTION 2092 bool "Fault-injection capability for functions" 2093 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 2094 help 2095 Provide function-based fault-injection capability. 2096 This will allow you to override a specific function with a return 2097 with given return value. As a result, function caller will see 2098 an error value and have to handle it. This is useful to test the 2099 error handling in various subsystems. 2100 2101 config FAIL_MMC_REQUEST 2102 bool "Fault-injection capability for MMC IO" 2103 depends on FAULT_INJECTION_DEBUG_FS && MMC 2104 help 2105 Provide fault-injection capability for MMC IO. 2106 This will make the mmc core return data errors. This is 2107 useful to test the error handling in the mmc block device 2108 and to test how the mmc host driver handles retries from 2109 the block device. 2110 2111 config FAIL_SUNRPC 2112 bool "Fault-injection capability for SunRPC" 2113 depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG 2114 help 2115 Provide fault-injection capability for SunRPC and 2116 its consumers. 2117 2118 config FAULT_INJECTION_CONFIGFS 2119 bool "Configfs interface for fault-injection capabilities" 2120 depends on FAULT_INJECTION 2121 select CONFIGFS_FS 2122 help 2123 This option allows configfs-based drivers to dynamically configure 2124 fault-injection via configfs. Each parameter for driver-specific 2125 fault-injection can be made visible as a configfs attribute in a 2126 configfs group. 2127 2128 2129 config FAULT_INJECTION_STACKTRACE_FILTER 2130 bool "stacktrace filter for fault-injection capabilities" 2131 depends on FAULT_INJECTION 2132 depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT 2133 select STACKTRACE 2134 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 2135 help 2136 Provide stacktrace filter for fault-injection capabilities 2137 2138 config ARCH_HAS_KCOV 2139 bool 2140 help 2141 An architecture should select this when it can successfully 2142 build and run with CONFIG_KCOV. This typically requires 2143 disabling instrumentation for some early boot code. 2144 2145 config CC_HAS_SANCOV_TRACE_PC 2146 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 2147 2148 2149 config KCOV 2150 bool "Code coverage for fuzzing" 2151 depends on ARCH_HAS_KCOV 2152 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 2153 depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \ 2154 GCC_VERSION >= 120000 || CC_IS_CLANG 2155 select DEBUG_FS 2156 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 2157 select OBJTOOL if HAVE_NOINSTR_HACK 2158 help 2159 KCOV exposes kernel code coverage information in a form suitable 2160 for coverage-guided fuzzing (randomized testing). 2161 2162 For more details, see Documentation/dev-tools/kcov.rst. 2163 2164 config KCOV_ENABLE_COMPARISONS 2165 bool "Enable comparison operands collection by KCOV" 2166 depends on KCOV 2167 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 2168 help 2169 KCOV also exposes operands of every comparison in the instrumented 2170 code along with operand sizes and PCs of the comparison instructions. 2171 These operands can be used by fuzzing engines to improve the quality 2172 of fuzzing coverage. 2173 2174 config KCOV_INSTRUMENT_ALL 2175 bool "Instrument all code by default" 2176 depends on KCOV 2177 default y 2178 help 2179 If you are doing generic system call fuzzing (like e.g. syzkaller), 2180 then you will want to instrument the whole kernel and you should 2181 say y here. If you are doing more targeted fuzzing (like e.g. 2182 filesystem fuzzing with AFL) then you will want to enable coverage 2183 for more specific subsets of files, and should say n here. 2184 2185 config KCOV_IRQ_AREA_SIZE 2186 hex "Size of interrupt coverage collection area in words" 2187 depends on KCOV 2188 default 0x40000 2189 help 2190 KCOV uses preallocated per-cpu areas to collect coverage from 2191 soft interrupts. This specifies the size of those areas in the 2192 number of unsigned long words. 2193 2194 config KCOV_SELFTEST 2195 bool "Perform short selftests on boot" 2196 depends on KCOV 2197 help 2198 Run short KCOV coverage collection selftests on boot. 2199 On test failure, causes the kernel to panic. Recommended to be 2200 enabled, ensuring critical functionality works as intended. 2201 2202 menuconfig RUNTIME_TESTING_MENU 2203 bool "Runtime Testing" 2204 default y 2205 2206 if RUNTIME_TESTING_MENU 2207 2208 config TEST_DHRY 2209 tristate "Dhrystone benchmark test" 2210 help 2211 Enable this to include the Dhrystone 2.1 benchmark. This test 2212 calculates the number of Dhrystones per second, and the number of 2213 DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided 2214 by 1757 (the number of Dhrystones per second obtained on the VAX 2215 11/780, nominally a 1 MIPS machine). 2216 2217 To run the benchmark, it needs to be enabled explicitly, either from 2218 the kernel command line (when built-in), or from userspace (when 2219 built-in or modular). 2220 2221 Run once during kernel boot: 2222 2223 test_dhry.run 2224 2225 Set number of iterations from kernel command line: 2226 2227 test_dhry.iterations=<n> 2228 2229 Set number of iterations from userspace: 2230 2231 echo <n> > /sys/module/test_dhry/parameters/iterations 2232 2233 Trigger manual run from userspace: 2234 2235 echo y > /sys/module/test_dhry/parameters/run 2236 2237 If the number of iterations is <= 0, the test will devise a suitable 2238 number of iterations (test runs for at least 2s) automatically. 2239 This process takes ca. 4s. 2240 2241 If unsure, say N. 2242 2243 config LKDTM 2244 tristate "Linux Kernel Dump Test Tool Module" 2245 depends on DEBUG_FS 2246 help 2247 This module enables testing of the different dumping mechanisms by 2248 inducing system failures at predefined crash points. 2249 If you don't need it: say N 2250 Choose M here to compile this code as a module. The module will be 2251 called lkdtm. 2252 2253 Documentation on how to use the module can be found in 2254 Documentation/fault-injection/provoke-crashes.rst 2255 2256 config CPUMASK_KUNIT_TEST 2257 tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS 2258 depends on KUNIT 2259 default KUNIT_ALL_TESTS 2260 help 2261 Enable to turn on cpumask tests, running at boot or module load time. 2262 2263 For more information on KUnit and unit tests in general, please refer 2264 to the KUnit documentation in Documentation/dev-tools/kunit/. 2265 2266 If unsure, say N. 2267 2268 config TEST_LIST_SORT 2269 tristate "Linked list sorting test" if !KUNIT_ALL_TESTS 2270 depends on KUNIT 2271 default KUNIT_ALL_TESTS 2272 help 2273 Enable this to turn on 'list_sort()' function test. This test is 2274 executed only once during system boot (so affects only boot time), 2275 or at module load time. 2276 2277 If unsure, say N. 2278 2279 config TEST_MIN_HEAP 2280 tristate "Min heap test" 2281 depends on DEBUG_KERNEL || m 2282 help 2283 Enable this to turn on min heap function tests. This test is 2284 executed only once during system boot (so affects only boot time), 2285 or at module load time. 2286 2287 If unsure, say N. 2288 2289 config TEST_SORT 2290 tristate "Array-based sort test" if !KUNIT_ALL_TESTS 2291 depends on KUNIT 2292 default KUNIT_ALL_TESTS 2293 help 2294 This option enables the self-test function of 'sort()' at boot, 2295 or at module load time. 2296 2297 If unsure, say N. 2298 2299 config TEST_DIV64 2300 tristate "64bit/32bit division and modulo test" 2301 depends on DEBUG_KERNEL || m 2302 help 2303 Enable this to turn on 'do_div()' function test. This test is 2304 executed only once during system boot (so affects only boot time), 2305 or at module load time. 2306 2307 If unsure, say N. 2308 2309 config TEST_MULDIV64 2310 tristate "mul_u64_u64_div_u64() test" 2311 depends on DEBUG_KERNEL || m 2312 help 2313 Enable this to turn on 'mul_u64_u64_div_u64()' function test. 2314 This test is executed only once during system boot (so affects 2315 only boot time), or at module load time. 2316 2317 If unsure, say N. 2318 2319 config TEST_IOV_ITER 2320 tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS 2321 depends on KUNIT 2322 depends on MMU 2323 default KUNIT_ALL_TESTS 2324 help 2325 Enable this to turn on testing of the operation of the I/O iterator 2326 (iov_iter). This test is executed only once during system boot (so 2327 affects only boot time), or at module load time. 2328 2329 If unsure, say N. 2330 2331 config KPROBES_SANITY_TEST 2332 tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS 2333 depends on DEBUG_KERNEL 2334 depends on KPROBES 2335 depends on KUNIT 2336 select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 2337 default KUNIT_ALL_TESTS 2338 help 2339 This option provides for testing basic kprobes functionality on 2340 boot. Samples of kprobe and kretprobe are inserted and 2341 verified for functionality. 2342 2343 Say N if you are unsure. 2344 2345 config FPROBE_SANITY_TEST 2346 bool "Self test for fprobe" 2347 depends on DEBUG_KERNEL 2348 depends on FPROBE 2349 depends on KUNIT=y 2350 help 2351 This option will enable testing the fprobe when the system boot. 2352 A series of tests are made to verify that the fprobe is functioning 2353 properly. 2354 2355 Say N if you are unsure. 2356 2357 config BACKTRACE_SELF_TEST 2358 tristate "Self test for the backtrace code" 2359 depends on DEBUG_KERNEL 2360 help 2361 This option provides a kernel module that can be used to test 2362 the kernel stack backtrace code. This option is not useful 2363 for distributions or general kernels, but only for kernel 2364 developers working on architecture code. 2365 2366 Note that if you want to also test saved backtraces, you will 2367 have to enable STACKTRACE as well. 2368 2369 Say N if you are unsure. 2370 2371 config TEST_REF_TRACKER 2372 tristate "Self test for reference tracker" 2373 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT 2374 select REF_TRACKER 2375 help 2376 This option provides a kernel module performing tests 2377 using reference tracker infrastructure. 2378 2379 Say N if you are unsure. 2380 2381 config RBTREE_TEST 2382 tristate "Red-Black tree test" 2383 depends on DEBUG_KERNEL 2384 help 2385 A benchmark measuring the performance of the rbtree library. 2386 Also includes rbtree invariant checks. 2387 2388 config REED_SOLOMON_TEST 2389 tristate "Reed-Solomon library test" 2390 depends on DEBUG_KERNEL || m 2391 select REED_SOLOMON 2392 select REED_SOLOMON_ENC16 2393 select REED_SOLOMON_DEC16 2394 help 2395 This option enables the self-test function of rslib at boot, 2396 or at module load time. 2397 2398 If unsure, say N. 2399 2400 config INTERVAL_TREE_TEST 2401 tristate "Interval tree test" 2402 depends on DEBUG_KERNEL 2403 select INTERVAL_TREE 2404 help 2405 A benchmark measuring the performance of the interval tree library 2406 2407 config PERCPU_TEST 2408 tristate "Per cpu operations test" 2409 depends on m && DEBUG_KERNEL 2410 help 2411 Enable this option to build test module which validates per-cpu 2412 operations. 2413 2414 If unsure, say N. 2415 2416 config ATOMIC64_SELFTEST 2417 tristate "Perform an atomic64_t self-test" 2418 help 2419 Enable this option to test the atomic64_t functions at boot or 2420 at module load time. 2421 2422 If unsure, say N. 2423 2424 config ASYNC_RAID6_TEST 2425 tristate "Self test for hardware accelerated raid6 recovery" 2426 depends on ASYNC_RAID6_RECOV 2427 select ASYNC_MEMCPY 2428 help 2429 This is a one-shot self test that permutes through the 2430 recovery of all the possible two disk failure scenarios for a 2431 N-disk array. Recovery is performed with the asynchronous 2432 raid6 recovery routines, and will optionally use an offload 2433 engine if one is available. 2434 2435 If unsure, say N. 2436 2437 config TEST_HEXDUMP 2438 tristate "Test functions located in the hexdump module at runtime" 2439 2440 config STRING_KUNIT_TEST 2441 tristate "KUnit test string functions at runtime" if !KUNIT_ALL_TESTS 2442 depends on KUNIT 2443 default KUNIT_ALL_TESTS 2444 2445 config STRING_HELPERS_KUNIT_TEST 2446 tristate "KUnit test string helpers at runtime" if !KUNIT_ALL_TESTS 2447 depends on KUNIT 2448 default KUNIT_ALL_TESTS 2449 2450 config TEST_KSTRTOX 2451 tristate "Test kstrto*() family of functions at runtime" 2452 2453 config TEST_PRINTF 2454 tristate "Test printf() family of functions at runtime" 2455 2456 config TEST_SCANF 2457 tristate "Test scanf() family of functions at runtime" 2458 2459 config TEST_BITMAP 2460 tristate "Test bitmap_*() family of functions at runtime" 2461 help 2462 Enable this option to test the bitmap functions at boot. 2463 2464 If unsure, say N. 2465 2466 config TEST_UUID 2467 tristate "Test functions located in the uuid module at runtime" 2468 2469 config TEST_XARRAY 2470 tristate "Test the XArray code at runtime" 2471 2472 config TEST_MAPLE_TREE 2473 tristate "Test the Maple Tree code at runtime or module load" 2474 help 2475 Enable this option to test the maple tree code functions at boot, or 2476 when the module is loaded. Enable "Debug Maple Trees" will enable 2477 more verbose output on failures. 2478 2479 If unsure, say N. 2480 2481 config TEST_RHASHTABLE 2482 tristate "Perform selftest on resizable hash table" 2483 help 2484 Enable this option to test the rhashtable functions at boot. 2485 2486 If unsure, say N. 2487 2488 config TEST_IDA 2489 tristate "Perform selftest on IDA functions" 2490 2491 config TEST_PARMAN 2492 tristate "Perform selftest on priority array manager" 2493 depends on PARMAN 2494 help 2495 Enable this option to test priority array manager on boot 2496 (or module load). 2497 2498 If unsure, say N. 2499 2500 config TEST_IRQ_TIMINGS 2501 bool "IRQ timings selftest" 2502 depends on IRQ_TIMINGS 2503 help 2504 Enable this option to test the irq timings code on boot. 2505 2506 If unsure, say N. 2507 2508 config TEST_LKM 2509 tristate "Test module loading with 'hello world' module" 2510 depends on m 2511 help 2512 This builds the "test_module" module that emits "Hello, world" 2513 on printk when loaded. It is designed to be used for basic 2514 evaluation of the module loading subsystem (for example when 2515 validating module verification). It lacks any extra dependencies, 2516 and will not normally be loaded by the system unless explicitly 2517 requested by name. 2518 2519 If unsure, say N. 2520 2521 config TEST_BITOPS 2522 tristate "Test module for compilation of bitops operations" 2523 help 2524 This builds the "test_bitops" module that is much like the 2525 TEST_LKM module except that it does a basic exercise of the 2526 set/clear_bit macros and get_count_order/long to make sure there are 2527 no compiler warnings from C=1 sparse checker or -Wextra 2528 compilations. It has no dependencies and doesn't run or load unless 2529 explicitly requested by name. for example: modprobe test_bitops. 2530 2531 If unsure, say N. 2532 2533 config TEST_VMALLOC 2534 tristate "Test module for stress/performance analysis of vmalloc allocator" 2535 default n 2536 depends on MMU 2537 depends on m 2538 help 2539 This builds the "test_vmalloc" module that should be used for 2540 stress and performance analysis. So, any new change for vmalloc 2541 subsystem can be evaluated from performance and stability point 2542 of view. 2543 2544 If unsure, say N. 2545 2546 config TEST_BPF 2547 tristate "Test BPF filter functionality" 2548 depends on m && NET 2549 help 2550 This builds the "test_bpf" module that runs various test vectors 2551 against the BPF interpreter or BPF JIT compiler depending on the 2552 current setting. This is in particular useful for BPF JIT compiler 2553 development, but also to run regression tests against changes in 2554 the interpreter code. It also enables test stubs for eBPF maps and 2555 verifier used by user space verifier testsuite. 2556 2557 If unsure, say N. 2558 2559 config TEST_BLACKHOLE_DEV 2560 tristate "Test blackhole netdev functionality" 2561 depends on m && NET 2562 help 2563 This builds the "test_blackhole_dev" module that validates the 2564 data path through this blackhole netdev. 2565 2566 If unsure, say N. 2567 2568 config FIND_BIT_BENCHMARK 2569 tristate "Test find_bit functions" 2570 help 2571 This builds the "test_find_bit" module that measure find_*_bit() 2572 functions performance. 2573 2574 If unsure, say N. 2575 2576 config TEST_FIRMWARE 2577 tristate "Test firmware loading via userspace interface" 2578 depends on FW_LOADER 2579 help 2580 This builds the "test_firmware" module that creates a userspace 2581 interface for testing firmware loading. This can be used to 2582 control the triggering of firmware loading without needing an 2583 actual firmware-using device. The contents can be rechecked by 2584 userspace. 2585 2586 If unsure, say N. 2587 2588 config TEST_SYSCTL 2589 tristate "sysctl test driver" 2590 depends on PROC_SYSCTL 2591 help 2592 This builds the "test_sysctl" module. This driver enables to test the 2593 proc sysctl interfaces available to drivers safely without affecting 2594 production knobs which might alter system functionality. 2595 2596 If unsure, say N. 2597 2598 config BITFIELD_KUNIT 2599 tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS 2600 depends on KUNIT 2601 default KUNIT_ALL_TESTS 2602 help 2603 Enable this option to test the bitfield functions at boot. 2604 2605 KUnit tests run during boot and output the results to the debug log 2606 in TAP format (http://testanything.org/). Only useful for kernel devs 2607 running the KUnit test harness, and not intended for inclusion into a 2608 production build. 2609 2610 For more information on KUnit and unit tests in general please refer 2611 to the KUnit documentation in Documentation/dev-tools/kunit/. 2612 2613 If unsure, say N. 2614 2615 config CHECKSUM_KUNIT 2616 tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS 2617 depends on KUNIT 2618 default KUNIT_ALL_TESTS 2619 help 2620 Enable this option to test the checksum functions at boot. 2621 2622 KUnit tests run during boot and output the results to the debug log 2623 in TAP format (http://testanything.org/). Only useful for kernel devs 2624 running the KUnit test harness, and not intended for inclusion into a 2625 production build. 2626 2627 For more information on KUnit and unit tests in general please refer 2628 to the KUnit documentation in Documentation/dev-tools/kunit/. 2629 2630 If unsure, say N. 2631 2632 config HASH_KUNIT_TEST 2633 tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS 2634 depends on KUNIT 2635 default KUNIT_ALL_TESTS 2636 help 2637 Enable this option to test the kernel's string (<linux/stringhash.h>), and 2638 integer (<linux/hash.h>) hash functions on boot. 2639 2640 KUnit tests run during boot and output the results to the debug log 2641 in TAP format (https://testanything.org/). Only useful for kernel devs 2642 running the KUnit test harness, and not intended for inclusion into a 2643 production build. 2644 2645 For more information on KUnit and unit tests in general please refer 2646 to the KUnit documentation in Documentation/dev-tools/kunit/. 2647 2648 This is intended to help people writing architecture-specific 2649 optimized versions. If unsure, say N. 2650 2651 config RESOURCE_KUNIT_TEST 2652 tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS 2653 depends on KUNIT 2654 default KUNIT_ALL_TESTS 2655 select GET_FREE_REGION 2656 help 2657 This builds the resource API unit test. 2658 Tests the logic of API provided by resource.c and ioport.h. 2659 For more information on KUnit and unit tests in general please refer 2660 to the KUnit documentation in Documentation/dev-tools/kunit/. 2661 2662 If unsure, say N. 2663 2664 config SYSCTL_KUNIT_TEST 2665 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS 2666 depends on KUNIT 2667 default KUNIT_ALL_TESTS 2668 help 2669 This builds the proc sysctl unit test, which runs on boot. 2670 Tests the API contract and implementation correctness of sysctl. 2671 For more information on KUnit and unit tests in general please refer 2672 to the KUnit documentation in Documentation/dev-tools/kunit/. 2673 2674 If unsure, say N. 2675 2676 config LIST_KUNIT_TEST 2677 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS 2678 depends on KUNIT 2679 default KUNIT_ALL_TESTS 2680 help 2681 This builds the linked list KUnit test suite. 2682 It tests that the API and basic functionality of the list_head type 2683 and associated macros. 2684 2685 KUnit tests run during boot and output the results to the debug log 2686 in TAP format (https://testanything.org/). Only useful for kernel devs 2687 running the KUnit test harness, and not intended for inclusion into a 2688 production build. 2689 2690 For more information on KUnit and unit tests in general please refer 2691 to the KUnit documentation in Documentation/dev-tools/kunit/. 2692 2693 If unsure, say N. 2694 2695 config HASHTABLE_KUNIT_TEST 2696 tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS 2697 depends on KUNIT 2698 default KUNIT_ALL_TESTS 2699 help 2700 This builds the hashtable KUnit test suite. 2701 It tests the basic functionality of the API defined in 2702 include/linux/hashtable.h. For more information on KUnit and 2703 unit tests in general please refer to the KUnit documentation 2704 in Documentation/dev-tools/kunit/. 2705 2706 If unsure, say N. 2707 2708 config LINEAR_RANGES_TEST 2709 tristate "KUnit test for linear_ranges" 2710 depends on KUNIT 2711 select LINEAR_RANGES 2712 help 2713 This builds the linear_ranges unit test, which runs on boot. 2714 Tests the linear_ranges logic correctness. 2715 For more information on KUnit and unit tests in general please refer 2716 to the KUnit documentation in Documentation/dev-tools/kunit/. 2717 2718 If unsure, say N. 2719 2720 config CMDLINE_KUNIT_TEST 2721 tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS 2722 depends on KUNIT 2723 default KUNIT_ALL_TESTS 2724 help 2725 This builds the cmdline API unit test. 2726 Tests the logic of API provided by cmdline.c. 2727 For more information on KUnit and unit tests in general please refer 2728 to the KUnit documentation in Documentation/dev-tools/kunit/. 2729 2730 If unsure, say N. 2731 2732 config BITS_TEST 2733 tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS 2734 depends on KUNIT 2735 default KUNIT_ALL_TESTS 2736 help 2737 This builds the bits unit test. 2738 Tests the logic of macros defined in bits.h. 2739 For more information on KUnit and unit tests in general please refer 2740 to the KUnit documentation in Documentation/dev-tools/kunit/. 2741 2742 If unsure, say N. 2743 2744 config SLUB_KUNIT_TEST 2745 tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS 2746 depends on SLUB_DEBUG && KUNIT 2747 default KUNIT_ALL_TESTS 2748 help 2749 This builds SLUB allocator unit test. 2750 Tests SLUB cache debugging functionality. 2751 For more information on KUnit and unit tests in general please refer 2752 to the KUnit documentation in Documentation/dev-tools/kunit/. 2753 2754 If unsure, say N. 2755 2756 config RATIONAL_KUNIT_TEST 2757 tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS 2758 depends on KUNIT && RATIONAL 2759 default KUNIT_ALL_TESTS 2760 help 2761 This builds the rational math unit test. 2762 For more information on KUnit and unit tests in general please refer 2763 to the KUnit documentation in Documentation/dev-tools/kunit/. 2764 2765 If unsure, say N. 2766 2767 config MEMCPY_KUNIT_TEST 2768 tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS 2769 depends on KUNIT 2770 default KUNIT_ALL_TESTS 2771 help 2772 Builds unit tests for memcpy(), memmove(), and memset() functions. 2773 For more information on KUnit and unit tests in general please refer 2774 to the KUnit documentation in Documentation/dev-tools/kunit/. 2775 2776 If unsure, say N. 2777 2778 config IS_SIGNED_TYPE_KUNIT_TEST 2779 tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS 2780 depends on KUNIT 2781 default KUNIT_ALL_TESTS 2782 help 2783 Builds unit tests for the is_signed_type() macro. 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 2790 config OVERFLOW_KUNIT_TEST 2791 tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS 2792 depends on KUNIT 2793 default KUNIT_ALL_TESTS 2794 help 2795 Builds unit tests for the check_*_overflow(), size_*(), allocation, and 2796 related functions. 2797 2798 For more information on KUnit and unit tests in general please refer 2799 to the KUnit documentation in Documentation/dev-tools/kunit/. 2800 2801 If unsure, say N. 2802 2803 config STACKINIT_KUNIT_TEST 2804 tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS 2805 depends on KUNIT 2806 default KUNIT_ALL_TESTS 2807 help 2808 Test if the kernel is zero-initializing stack variables and 2809 padding. Coverage is controlled by compiler flags, 2810 CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO, 2811 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2812 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2813 2814 config FORTIFY_KUNIT_TEST 2815 tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS 2816 depends on KUNIT 2817 default KUNIT_ALL_TESTS 2818 help 2819 Builds unit tests for checking internals of FORTIFY_SOURCE as used 2820 by the str*() and mem*() family of functions. For testing runtime 2821 traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests. 2822 2823 config HW_BREAKPOINT_KUNIT_TEST 2824 bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS 2825 depends on HAVE_HW_BREAKPOINT 2826 depends on KUNIT=y 2827 default KUNIT_ALL_TESTS 2828 help 2829 Tests for hw_breakpoint constraints accounting. 2830 2831 If unsure, say N. 2832 2833 config SIPHASH_KUNIT_TEST 2834 tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS 2835 depends on KUNIT 2836 default KUNIT_ALL_TESTS 2837 help 2838 Enable this option to test the kernel's siphash (<linux/siphash.h>) hash 2839 functions on boot (or module load). 2840 2841 This is intended to help people writing architecture-specific 2842 optimized versions. If unsure, say N. 2843 2844 config USERCOPY_KUNIT_TEST 2845 tristate "KUnit Test for user/kernel boundary protections" 2846 depends on KUNIT 2847 default KUNIT_ALL_TESTS 2848 help 2849 This builds the "usercopy_kunit" module that runs sanity checks 2850 on the copy_to/from_user infrastructure, making sure basic 2851 user/kernel boundary testing is working. 2852 2853 config TEST_UDELAY 2854 tristate "udelay test driver" 2855 help 2856 This builds the "udelay_test" module that helps to make sure 2857 that udelay() is working properly. 2858 2859 If unsure, say N. 2860 2861 config TEST_STATIC_KEYS 2862 tristate "Test static keys" 2863 depends on m 2864 help 2865 Test the static key interfaces. 2866 2867 If unsure, say N. 2868 2869 config TEST_DYNAMIC_DEBUG 2870 tristate "Test DYNAMIC_DEBUG" 2871 depends on DYNAMIC_DEBUG 2872 help 2873 This module registers a tracer callback to count enabled 2874 pr_debugs in a 'do_debugging' function, then alters their 2875 enablements, calls the function, and compares counts. 2876 2877 If unsure, say N. 2878 2879 config TEST_KMOD 2880 tristate "kmod stress tester" 2881 depends on m 2882 depends on NETDEVICES && NET_CORE && INET # for TUN 2883 depends on BLOCK 2884 depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS 2885 select TEST_LKM 2886 select XFS_FS 2887 select TUN 2888 select BTRFS_FS 2889 help 2890 Test the kernel's module loading mechanism: kmod. kmod implements 2891 support to load modules using the Linux kernel's usermode helper. 2892 This test provides a series of tests against kmod. 2893 2894 Although technically you can either build test_kmod as a module or 2895 into the kernel we disallow building it into the kernel since 2896 it stress tests request_module() and this will very likely cause 2897 some issues by taking over precious threads available from other 2898 module load requests, ultimately this could be fatal. 2899 2900 To run tests run: 2901 2902 tools/testing/selftests/kmod/kmod.sh --help 2903 2904 If unsure, say N. 2905 2906 config TEST_DEBUG_VIRTUAL 2907 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 2908 depends on DEBUG_VIRTUAL 2909 help 2910 Test the kernel's ability to detect incorrect calls to 2911 virt_to_phys() done against the non-linear part of the 2912 kernel's virtual address map. 2913 2914 If unsure, say N. 2915 2916 config TEST_MEMCAT_P 2917 tristate "Test memcat_p() helper function" 2918 help 2919 Test the memcat_p() helper for correctly merging two 2920 pointer arrays together. 2921 2922 If unsure, say N. 2923 2924 config TEST_OBJAGG 2925 tristate "Perform selftest on object aggreration manager" 2926 default n 2927 depends on OBJAGG 2928 help 2929 Enable this option to test object aggregation manager on boot 2930 (or module load). 2931 2932 config TEST_MEMINIT 2933 tristate "Test heap/page initialization" 2934 help 2935 Test if the kernel is zero-initializing heap and page allocations. 2936 This can be useful to test init_on_alloc and init_on_free features. 2937 2938 If unsure, say N. 2939 2940 config TEST_HMM 2941 tristate "Test HMM (Heterogeneous Memory Management)" 2942 depends on TRANSPARENT_HUGEPAGE 2943 depends on DEVICE_PRIVATE 2944 select HMM_MIRROR 2945 select MMU_NOTIFIER 2946 help 2947 This is a pseudo device driver solely for testing HMM. 2948 Say M here if you want to build the HMM test module. 2949 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests. 2950 2951 If unsure, say N. 2952 2953 config TEST_FREE_PAGES 2954 tristate "Test freeing pages" 2955 help 2956 Test that a memory leak does not occur due to a race between 2957 freeing a block of pages and a speculative page reference. 2958 Loading this module is safe if your kernel has the bug fixed. 2959 If the bug is not fixed, it will leak gigabytes of memory and 2960 probably OOM your system. 2961 2962 config TEST_FPU 2963 tristate "Test floating point operations in kernel space" 2964 depends on ARCH_HAS_KERNEL_FPU_SUPPORT && !KCOV_INSTRUMENT_ALL 2965 help 2966 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu 2967 which will trigger a sequence of floating point operations. This is used 2968 for self-testing floating point control register setting in 2969 kernel_fpu_begin(). 2970 2971 If unsure, say N. 2972 2973 config TEST_CLOCKSOURCE_WATCHDOG 2974 tristate "Test clocksource watchdog in kernel space" 2975 depends on CLOCKSOURCE_WATCHDOG 2976 help 2977 Enable this option to create a kernel module that will trigger 2978 a test of the clocksource watchdog. This module may be loaded 2979 via modprobe or insmod in which case it will run upon being 2980 loaded, or it may be built in, in which case it will run 2981 shortly after boot. 2982 2983 If unsure, say N. 2984 2985 config TEST_OBJPOOL 2986 tristate "Test module for correctness and stress of objpool" 2987 default n 2988 depends on m && DEBUG_KERNEL 2989 help 2990 This builds the "test_objpool" module that should be used for 2991 correctness verification and concurrent testings of objects 2992 allocation and reclamation. 2993 2994 If unsure, say N. 2995 2996 endif # RUNTIME_TESTING_MENU 2997 2998 config ARCH_USE_MEMTEST 2999 bool 3000 help 3001 An architecture should select this when it uses early_memtest() 3002 during boot process. 3003 3004 config MEMTEST 3005 bool "Memtest" 3006 depends on ARCH_USE_MEMTEST 3007 help 3008 This option adds a kernel parameter 'memtest', which allows memtest 3009 to be set and executed. 3010 memtest=0, mean disabled; -- default 3011 memtest=1, mean do 1 test pattern; 3012 ... 3013 memtest=17, mean do 17 test patterns. 3014 If you are unsure how to answer this question, answer N. 3015 3016 3017 3018 config HYPERV_TESTING 3019 bool "Microsoft Hyper-V driver testing" 3020 default n 3021 depends on HYPERV && DEBUG_FS 3022 help 3023 Select this option to enable Hyper-V vmbus testing. 3024 3025 endmenu # "Kernel Testing and Coverage" 3026 3027 menu "Rust hacking" 3028 3029 config RUST_DEBUG_ASSERTIONS 3030 bool "Debug assertions" 3031 depends on RUST 3032 help 3033 Enables rustc's `-Cdebug-assertions` codegen option. 3034 3035 This flag lets you turn `cfg(debug_assertions)` conditional 3036 compilation on or off. This can be used to enable extra debugging 3037 code in development but not in production. For example, it controls 3038 the behavior of the standard library's `debug_assert!` macro. 3039 3040 Note that this will apply to all Rust code, including `core`. 3041 3042 If unsure, say N. 3043 3044 config RUST_OVERFLOW_CHECKS 3045 bool "Overflow checks" 3046 default y 3047 depends on RUST 3048 help 3049 Enables rustc's `-Coverflow-checks` codegen option. 3050 3051 This flag allows you to control the behavior of runtime integer 3052 overflow. When overflow-checks are enabled, a Rust panic will occur 3053 on overflow. 3054 3055 Note that this will apply to all Rust code, including `core`. 3056 3057 If unsure, say Y. 3058 3059 config RUST_BUILD_ASSERT_ALLOW 3060 bool "Allow unoptimized build-time assertions" 3061 depends on RUST 3062 help 3063 Controls how `build_error!` and `build_assert!` are handled during the build. 3064 3065 If calls to them exist in the binary, it may indicate a violated invariant 3066 or that the optimizer failed to verify the invariant during compilation. 3067 3068 This should not happen, thus by default the build is aborted. However, 3069 as an escape hatch, you can choose Y here to ignore them during build 3070 and let the check be carried at runtime (with `panic!` being called if 3071 the check fails). 3072 3073 If unsure, say N. 3074 3075 config RUST_KERNEL_DOCTESTS 3076 bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS 3077 depends on RUST && KUNIT=y 3078 default KUNIT_ALL_TESTS 3079 help 3080 This builds the documentation tests of the `kernel` crate 3081 as KUnit tests. 3082 3083 For more information on KUnit and unit tests in general, 3084 please refer to the KUnit documentation in Documentation/dev-tools/kunit/. 3085 3086 If unsure, say N. 3087 3088 endmenu # "Rust" 3089 3090 endmenu # Kernel hacking 3091 3092 config INT_POW_TEST 3093 tristate "Integer exponentiation (int_pow) test" if !KUNIT_ALL_TESTS 3094 depends on KUNIT 3095 default KUNIT_ALL_TESTS 3096 help 3097 This option enables the KUnit test suite for the int_pow function, 3098 which performs integer exponentiation. The test suite is designed to 3099 verify that the implementation of int_pow correctly computes the power 3100 of a given base raised to a given exponent. 3101 3102 Enabling this option will include tests that check various scenarios 3103 and edge cases to ensure the accuracy and reliability of the exponentiation 3104 function. 3105 3106 If unsure, say N 3107