1# SPDX-License-Identifier: GPL-2.0-only 2menu "Kernel hacking" 3 4menu "printk and dmesg options" 5 6config PRINTK_TIME 7 bool "Show timing information on printks" 8 depends on PRINTK 9 help 10 Selecting this option causes time stamps of the printk() 11 messages to be added to the output of the syslog() system 12 call and at the console. 13 14 The timestamp is always recorded internally, and exported 15 to /dev/kmsg. This flag just specifies if the timestamp should 16 be included, not that the timestamp is recorded. 17 18 The behavior is also controlled by the kernel command line 19 parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst 20 21config PRINTK_CALLER 22 bool "Show caller information on printks" 23 depends on PRINTK 24 help 25 Selecting this option causes printk() to add a caller "thread id" (if 26 in task context) or a caller "processor id" (if not in task context) 27 to every message. 28 29 This option is intended for environments where multiple threads 30 concurrently call printk() for many times, for it is difficult to 31 interpret without knowing where these lines (or sometimes individual 32 line which was divided into multiple lines due to race) came from. 33 34 Since toggling after boot makes the code racy, currently there is 35 no option to enable/disable at the kernel command line parameter or 36 sysfs interface. 37 38config STACKTRACE_BUILD_ID 39 bool "Show build ID information in stacktraces" 40 depends on PRINTK 41 help 42 Selecting this option adds build ID information for symbols in 43 stacktraces printed with the printk format '%p[SR]b'. 44 45 This option is intended for distros where debuginfo is not easily 46 accessible but can be downloaded given the build ID of the vmlinux or 47 kernel module where the function is located. 48 49config CONSOLE_LOGLEVEL_DEFAULT 50 int "Default console loglevel (1-15)" 51 range 1 15 52 default "7" 53 help 54 Default loglevel to determine what will be printed on the console. 55 56 Setting a default here is equivalent to passing in loglevel=<x> in 57 the kernel bootargs. loglevel=<x> continues to override whatever 58 value is specified here as well. 59 60 Note: This does not affect the log level of un-prefixed printk() 61 usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT 62 option. 63 64config CONSOLE_LOGLEVEL_QUIET 65 int "quiet console loglevel (1-15)" 66 range 1 15 67 default "4" 68 help 69 loglevel to use when "quiet" is passed on the kernel commandline. 70 71 When "quiet" is passed on the kernel commandline this loglevel 72 will be used as the loglevel. IOW passing "quiet" will be the 73 equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>" 74 75config MESSAGE_LOGLEVEL_DEFAULT 76 int "Default message log level (1-7)" 77 range 1 7 78 default "4" 79 help 80 Default log level for printk statements with no specified priority. 81 82 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks 83 that are auditing their logs closely may want to set it to a lower 84 priority. 85 86 Note: This does not affect what message level gets printed on the console 87 by default. To change that, use loglevel=<x> in the kernel bootargs, 88 or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value. 89 90config BOOT_PRINTK_DELAY 91 bool "Delay each boot printk message by N milliseconds" 92 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY 93 help 94 This build option allows you to read kernel boot messages 95 by inserting a short delay after each one. The delay is 96 specified in milliseconds on the kernel command line, 97 using "boot_delay=N". 98 99 It is likely that you would also need to use "lpj=M" to preset 100 the "loops per jiffy" value. 101 See a previous boot log for the "lpj" value to use for your 102 system, and then set "lpj=M" before setting "boot_delay=N". 103 NOTE: Using this option may adversely affect SMP systems. 104 I.e., processors other than the first one may not boot up. 105 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect 106 what it believes to be lockup conditions. 107 108config DYNAMIC_DEBUG 109 bool "Enable dynamic printk() support" 110 default n 111 depends on PRINTK 112 depends on (DEBUG_FS || PROC_FS) 113 select DYNAMIC_DEBUG_CORE 114 help 115 116 Compiles debug level messages into the kernel, which would not 117 otherwise be available at runtime. These messages can then be 118 enabled/disabled based on various levels of scope - per source file, 119 function, module, format string, and line number. This mechanism 120 implicitly compiles in all pr_debug() and dev_dbg() calls, which 121 enlarges the kernel text size by about 2%. 122 123 If a source file is compiled with DEBUG flag set, any 124 pr_debug() calls in it are enabled by default, but can be 125 disabled at runtime as below. Note that DEBUG flag is 126 turned on by many CONFIG_*DEBUG* options. 127 128 Usage: 129 130 Dynamic debugging is controlled via the 'dynamic_debug/control' file, 131 which is contained in the 'debugfs' filesystem or procfs. 132 Thus, the debugfs or procfs filesystem must first be mounted before 133 making use of this feature. 134 We refer the control file as: <debugfs>/dynamic_debug/control. This 135 file contains a list of the debug statements that can be enabled. The 136 format for each line of the file is: 137 138 filename:lineno [module]function flags format 139 140 filename : source file of the debug statement 141 lineno : line number of the debug statement 142 module : module that contains the debug statement 143 function : function that contains the debug statement 144 flags : '=p' means the line is turned 'on' for printing 145 format : the format used for the debug statement 146 147 From a live system: 148 149 nullarbor:~ # cat <debugfs>/dynamic_debug/control 150 # filename:lineno [module]function flags format 151 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012" 152 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012" 153 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012" 154 155 Example usage: 156 157 // enable the message at line 1603 of file svcsock.c 158 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' > 159 <debugfs>/dynamic_debug/control 160 161 // enable all the messages in file svcsock.c 162 nullarbor:~ # echo -n 'file svcsock.c +p' > 163 <debugfs>/dynamic_debug/control 164 165 // enable all the messages in the NFS server module 166 nullarbor:~ # echo -n 'module nfsd +p' > 167 <debugfs>/dynamic_debug/control 168 169 // enable all 12 messages in the function svc_process() 170 nullarbor:~ # echo -n 'func svc_process +p' > 171 <debugfs>/dynamic_debug/control 172 173 // disable all 12 messages in the function svc_process() 174 nullarbor:~ # echo -n 'func svc_process -p' > 175 <debugfs>/dynamic_debug/control 176 177 See Documentation/admin-guide/dynamic-debug-howto.rst for additional 178 information. 179 180config DYNAMIC_DEBUG_CORE 181 bool "Enable core function of dynamic debug support" 182 depends on PRINTK 183 depends on (DEBUG_FS || PROC_FS) 184 help 185 Enable core functional support of dynamic debug. It is useful 186 when you want to tie dynamic debug to your kernel modules with 187 DYNAMIC_DEBUG_MODULE defined for each of them, especially for 188 the case of embedded system where the kernel image size is 189 sensitive for people. 190 191config SYMBOLIC_ERRNAME 192 bool "Support symbolic error names in printf" 193 default y if PRINTK 194 help 195 If you say Y here, the kernel's printf implementation will 196 be able to print symbolic error names such as ENOSPC instead 197 of the number 28. It makes the kernel image slightly larger 198 (about 3KB), but can make the kernel logs easier to read. 199 200config DEBUG_BUGVERBOSE 201 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT 202 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE) 203 default y 204 help 205 Say Y here to make BUG() panics output the file name and line number 206 of the BUG call as well as the EIP and oops trace. This aids 207 debugging but costs about 70-100K of memory. 208 209endmenu # "printk and dmesg options" 210 211config DEBUG_KERNEL 212 bool "Kernel debugging" 213 help 214 Say Y here if you are developing drivers or trying to debug and 215 identify kernel problems. 216 217config DEBUG_MISC 218 bool "Miscellaneous debug code" 219 default DEBUG_KERNEL 220 depends on DEBUG_KERNEL 221 help 222 Say Y here if you need to enable miscellaneous debug code that should 223 be under a more specific debug option but isn't. 224 225menu "Compile-time checks and compiler options" 226 227config DEBUG_INFO 228 bool 229 help 230 A kernel debug info option other than "None" has been selected 231 in the "Debug information" choice below, indicating that debug 232 information will be generated for build targets. 233 234# Clang generates .uleb128 with label differences for DWARF v5, a feature that 235# older binutils ports do not support when utilizing RISC-V style linker 236# relaxation: https://sourceware.org/bugzilla/show_bug.cgi?id=27215 237config AS_HAS_NON_CONST_ULEB128 238 def_bool $(as-instr,.uleb128 .Lexpr_end4 - .Lexpr_start3\n.Lexpr_start3:\n.Lexpr_end4:) 239 240choice 241 prompt "Debug information" 242 depends on DEBUG_KERNEL 243 help 244 Selecting something other than "None" results in a kernel image 245 that will include debugging info resulting in a larger kernel image. 246 This adds debug symbols to the kernel and modules (gcc -g), and 247 is needed if you intend to use kernel crashdump or binary object 248 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 249 250 Choose which version of DWARF debug info to emit. If unsure, 251 select "Toolchain default". 252 253config DEBUG_INFO_NONE 254 bool "Disable debug information" 255 help 256 Do not build the kernel with debugging information, which will 257 result in a faster and smaller build. 258 259config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT 260 bool "Rely on the toolchain's implicit default DWARF version" 261 select DEBUG_INFO 262 depends on !CC_IS_CLANG || AS_IS_LLVM || CLANG_VERSION < 140000 || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128) 263 help 264 The implicit default version of DWARF debug info produced by a 265 toolchain changes over time. 266 267 This can break consumers of the debug info that haven't upgraded to 268 support newer revisions, and prevent testing newer versions, but 269 those should be less common scenarios. 270 271config DEBUG_INFO_DWARF4 272 bool "Generate DWARF Version 4 debuginfo" 273 select DEBUG_INFO 274 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502) 275 help 276 Generate DWARF v4 debug info. This requires gcc 4.5+, binutils 2.35.2 277 if using clang without clang's integrated assembler, and gdb 7.0+. 278 279 If you have consumers of DWARF debug info that are not ready for 280 newer revisions of DWARF, you may wish to choose this or have your 281 config select this. 282 283config DEBUG_INFO_DWARF5 284 bool "Generate DWARF Version 5 debuginfo" 285 select DEBUG_INFO 286 depends on !ARCH_HAS_BROKEN_DWARF5 287 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128) 288 help 289 Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc 290 5.0+ accepts the -gdwarf-5 flag but only had partial support for some 291 draft features until 7.0), and gdb 8.0+. 292 293 Changes to the structure of debug info in Version 5 allow for around 294 15-18% savings in resulting image and debug info section sizes as 295 compared to DWARF Version 4. DWARF Version 5 standardizes previous 296 extensions such as accelerators for symbol indexing and the format 297 for fission (.dwo/.dwp) files. Users may not want to select this 298 config if they rely on tooling that has not yet been updated to 299 support DWARF Version 5. 300 301endchoice # "Debug information" 302 303if DEBUG_INFO 304 305config DEBUG_INFO_REDUCED 306 bool "Reduce debugging information" 307 help 308 If you say Y here gcc is instructed to generate less debugging 309 information for structure types. This means that tools that 310 need full debugging information (like kgdb or systemtap) won't 311 be happy. But if you merely need debugging information to 312 resolve line numbers there is no loss. Advantage is that 313 build directory object sizes shrink dramatically over a full 314 DEBUG_INFO build and compile times are reduced too. 315 Only works with newer gcc versions. 316 317choice 318 prompt "Compressed Debug information" 319 help 320 Compress the resulting debug info. Results in smaller debug info sections, 321 but requires that consumers are able to decompress the results. 322 323 If unsure, choose DEBUG_INFO_COMPRESSED_NONE. 324 325config DEBUG_INFO_COMPRESSED_NONE 326 bool "Don't compress debug information" 327 help 328 Don't compress debug info sections. 329 330config DEBUG_INFO_COMPRESSED_ZLIB 331 bool "Compress debugging information with zlib" 332 depends on $(cc-option,-gz=zlib) 333 depends on $(ld-option,--compress-debug-sections=zlib) 334 help 335 Compress the debug information using zlib. Requires GCC 5.0+ or Clang 336 5.0+, binutils 2.26+, and zlib. 337 338 Users of dpkg-deb via scripts/package/builddeb may find an increase in 339 size of their debug .deb packages with this config set, due to the 340 debug info being compressed with zlib, then the object files being 341 recompressed with a different compression scheme. But this is still 342 preferable to setting $KDEB_COMPRESS to "none" which would be even 343 larger. 344 345config DEBUG_INFO_COMPRESSED_ZSTD 346 bool "Compress debugging information with zstd" 347 depends on $(cc-option,-gz=zstd) 348 depends on $(ld-option,--compress-debug-sections=zstd) 349 help 350 Compress the debug information using zstd. This may provide better 351 compression than zlib, for about the same time costs, but requires newer 352 toolchain support. Requires GCC 13.0+ or Clang 16.0+, binutils 2.40+, and 353 zstd. 354 355endchoice # "Compressed Debug information" 356 357config DEBUG_INFO_SPLIT 358 bool "Produce split debuginfo in .dwo files" 359 depends on $(cc-option,-gsplit-dwarf) 360 # RISC-V linker relaxation + -gsplit-dwarf has issues with LLVM and GCC 361 # prior to 12.x: 362 # https://github.com/llvm/llvm-project/issues/56642 363 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99090 364 depends on !RISCV || GCC_VERSION >= 120000 365 help 366 Generate debug info into separate .dwo files. This significantly 367 reduces the build directory size for builds with DEBUG_INFO, 368 because it stores the information only once on disk in .dwo 369 files instead of multiple times in object files and executables. 370 In addition the debug information is also compressed. 371 372 Requires recent gcc (4.7+) and recent gdb/binutils. 373 Any tool that packages or reads debug information would need 374 to know about the .dwo files and include them. 375 Incompatible with older versions of ccache. 376 377config DEBUG_INFO_BTF 378 bool "Generate BTF type information" 379 depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED 380 depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST 381 depends on BPF_SYSCALL 382 depends on PAHOLE_VERSION >= 116 383 depends on DEBUG_INFO_DWARF4 || PAHOLE_VERSION >= 121 384 # pahole uses elfutils, which does not have support for Hexagon relocations 385 depends on !HEXAGON 386 help 387 Generate deduplicated BTF type information from DWARF debug info. 388 Turning this on requires pahole v1.16 or later (v1.21 or later to 389 support DWARF 5), which will convert DWARF type info into equivalent 390 deduplicated BTF type info. 391 392config PAHOLE_HAS_SPLIT_BTF 393 def_bool PAHOLE_VERSION >= 119 394 395config PAHOLE_HAS_BTF_TAG 396 def_bool PAHOLE_VERSION >= 123 397 depends on CC_IS_CLANG 398 help 399 Decide whether pahole emits btf_tag attributes (btf_type_tag and 400 btf_decl_tag) or not. Currently only clang compiler implements 401 these attributes, so make the config depend on CC_IS_CLANG. 402 403config PAHOLE_HAS_LANG_EXCLUDE 404 def_bool PAHOLE_VERSION >= 124 405 help 406 Support for the --lang_exclude flag which makes pahole exclude 407 compilation units from the supplied language. Used in Kbuild to 408 omit Rust CUs which are not supported in version 1.24 of pahole, 409 otherwise it would emit malformed kernel and module binaries when 410 using DEBUG_INFO_BTF_MODULES. 411 412config DEBUG_INFO_BTF_MODULES 413 bool "Generate BTF type information for kernel modules" 414 default y 415 depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF 416 help 417 Generate compact split BTF type information for kernel modules. 418 419config MODULE_ALLOW_BTF_MISMATCH 420 bool "Allow loading modules with non-matching BTF type info" 421 depends on DEBUG_INFO_BTF_MODULES 422 help 423 For modules whose split BTF does not match vmlinux, load without 424 BTF rather than refusing to load. The default behavior with 425 module BTF enabled is to reject modules with such mismatches; 426 this option will still load module BTF where possible but ignore 427 it when a mismatch is found. 428 429config GDB_SCRIPTS 430 bool "Provide GDB scripts for kernel debugging" 431 help 432 This creates the required links to GDB helper scripts in the 433 build directory. If you load vmlinux into gdb, the helper 434 scripts will be automatically imported by gdb as well, and 435 additional functions are available to analyze a Linux kernel 436 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst 437 for further details. 438 439endif # DEBUG_INFO 440 441config FRAME_WARN 442 int "Warn for stack frames larger than" 443 range 0 8192 444 default 0 if KMSAN 445 default 2048 if GCC_PLUGIN_LATENT_ENTROPY 446 default 2048 if PARISC 447 default 1536 if (!64BIT && XTENSA) 448 default 1280 if KASAN && !64BIT 449 default 1024 if !64BIT 450 default 2048 if 64BIT 451 help 452 Tell the compiler to warn at build time for stack frames larger than this. 453 Setting this too low will cause a lot of warnings. 454 Setting it to 0 disables the warning. 455 456config STRIP_ASM_SYMS 457 bool "Strip assembler-generated symbols during link" 458 default n 459 help 460 Strip internal assembler-generated symbols during a link (symbols 461 that look like '.Lxxx') so they don't pollute the output of 462 get_wchan() and suchlike. 463 464config READABLE_ASM 465 bool "Generate readable assembler code" 466 depends on DEBUG_KERNEL 467 depends on CC_IS_GCC 468 help 469 Disable some compiler optimizations that tend to generate human unreadable 470 assembler output. This may make the kernel slightly slower, but it helps 471 to keep kernel developers who have to stare a lot at assembler listings 472 sane. 473 474config HEADERS_INSTALL 475 bool "Install uapi headers to usr/include" 476 depends on !UML 477 help 478 This option will install uapi headers (headers exported to user-space) 479 into the usr/include directory for use during the kernel build. 480 This is unneeded for building the kernel itself, but needed for some 481 user-space program samples. It is also needed by some features such 482 as uapi header sanity checks. 483 484config DEBUG_SECTION_MISMATCH 485 bool "Enable full Section mismatch analysis" 486 depends on CC_IS_GCC 487 help 488 The section mismatch analysis checks if there are illegal 489 references from one section to another section. 490 During linktime or runtime, some sections are dropped; 491 any use of code/data previously in these sections would 492 most likely result in an oops. 493 In the code, functions and variables are annotated with 494 __init,, etc. (see the full list in include/linux/init.h), 495 which results in the code/data being placed in specific sections. 496 The section mismatch analysis is always performed after a full 497 kernel build, and enabling this option causes the following 498 additional step to occur: 499 - Add the option -fno-inline-functions-called-once to gcc commands. 500 When inlining a function annotated with __init in a non-init 501 function, we would lose the section information and thus 502 the analysis would not catch the illegal reference. 503 This option tells gcc to inline less (but it does result in 504 a larger kernel). 505 506config SECTION_MISMATCH_WARN_ONLY 507 bool "Make section mismatch errors non-fatal" 508 default y 509 help 510 If you say N here, the build process will fail if there are any 511 section mismatch, instead of just throwing warnings. 512 513 If unsure, say Y. 514 515config DEBUG_FORCE_FUNCTION_ALIGN_64B 516 bool "Force all function address 64B aligned" 517 depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC || RISCV || S390) 518 select FUNCTION_ALIGNMENT_64B 519 help 520 There are cases that a commit from one domain changes the function 521 address alignment of other domains, and cause magic performance 522 bump (regression or improvement). Enable this option will help to 523 verify if the bump is caused by function alignment changes, while 524 it will slightly increase the kernel size and affect icache usage. 525 526 It is mainly for debug and performance tuning use. 527 528# 529# Select this config option from the architecture Kconfig, if it 530# is preferred to always offer frame pointers as a config 531# option on the architecture (regardless of KERNEL_DEBUG): 532# 533config ARCH_WANT_FRAME_POINTERS 534 bool 535 536config FRAME_POINTER 537 bool "Compile the kernel with frame pointers" 538 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS 539 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 540 help 541 If you say Y here the resulting kernel image will be slightly 542 larger and slower, but it gives very useful debugging information 543 in case of kernel bugs. (precise oopses/stacktraces/warnings) 544 545config OBJTOOL 546 bool 547 548config STACK_VALIDATION 549 bool "Compile-time stack metadata validation" 550 depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER 551 select OBJTOOL 552 default n 553 help 554 Validate frame pointer rules at compile-time. This helps ensure that 555 runtime stack traces are more reliable. 556 557 For more information, see 558 tools/objtool/Documentation/objtool.txt. 559 560config NOINSTR_VALIDATION 561 bool 562 depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY 563 select OBJTOOL 564 default y 565 566config VMLINUX_MAP 567 bool "Generate vmlinux.map file when linking" 568 depends on EXPERT 569 help 570 Selecting this option will pass "-Map=vmlinux.map" to ld 571 when linking vmlinux. That file can be useful for verifying 572 and debugging magic section games, and for seeing which 573 pieces of code get eliminated with 574 CONFIG_LD_DEAD_CODE_DATA_ELIMINATION. 575 576config BUILTIN_MODULE_RANGES 577 bool "Generate address range information for builtin modules" 578 depends on !LTO 579 depends on VMLINUX_MAP 580 help 581 When modules are built into the kernel, there will be no module name 582 associated with its symbols in /proc/kallsyms. Tracers may want to 583 identify symbols by module name and symbol name regardless of whether 584 the module is configured as loadable or not. 585 586 This option generates modules.builtin.ranges in the build tree with 587 offset ranges (per ELF section) for the module(s) they belong to. 588 It also records an anchor symbol to determine the load address of the 589 section. 590 591config DEBUG_FORCE_WEAK_PER_CPU 592 bool "Force weak per-cpu definitions" 593 depends on DEBUG_KERNEL 594 help 595 s390 and alpha require percpu variables in modules to be 596 defined weak to work around addressing range issue which 597 puts the following two restrictions on percpu variable 598 definitions. 599 600 1. percpu symbols must be unique whether static or not 601 2. percpu variables can't be defined inside a function 602 603 To ensure that generic code follows the above rules, this 604 option forces all percpu variables to be defined as weak. 605 606endmenu # "Compiler options" 607 608menu "Generic Kernel Debugging Instruments" 609 610config MAGIC_SYSRQ 611 bool "Magic SysRq key" 612 depends on !UML 613 help 614 If you say Y here, you will have some control over the system even 615 if the system crashes for example during kernel debugging (e.g., you 616 will be able to flush the buffer cache to disk, reboot the system 617 immediately or dump some status information). This is accomplished 618 by pressing various keys while holding SysRq (Alt+PrintScreen). It 619 also works on a serial console (on PC hardware at least), if you 620 send a BREAK and then within 5 seconds a command keypress. The 621 keys are documented in <file:Documentation/admin-guide/sysrq.rst>. 622 Don't say Y unless you really know what this hack does. 623 624config MAGIC_SYSRQ_DEFAULT_ENABLE 625 hex "Enable magic SysRq key functions by default" 626 depends on MAGIC_SYSRQ 627 default 0x1 628 help 629 Specifies which SysRq key functions are enabled by default. 630 This may be set to 1 or 0 to enable or disable them all, or 631 to a bitmask as described in Documentation/admin-guide/sysrq.rst. 632 633config MAGIC_SYSRQ_SERIAL 634 bool "Enable magic SysRq key over serial" 635 depends on MAGIC_SYSRQ 636 default y 637 help 638 Many embedded boards have a disconnected TTL level serial which can 639 generate some garbage that can lead to spurious false sysrq detects. 640 This option allows you to decide whether you want to enable the 641 magic SysRq key. 642 643config MAGIC_SYSRQ_SERIAL_SEQUENCE 644 string "Char sequence that enables magic SysRq over serial" 645 depends on MAGIC_SYSRQ_SERIAL 646 default "" 647 help 648 Specifies a sequence of characters that can follow BREAK to enable 649 SysRq on a serial console. 650 651 If unsure, leave an empty string and the option will not be enabled. 652 653config DEBUG_FS 654 bool "Debug Filesystem" 655 help 656 debugfs is a virtual file system that kernel developers use to put 657 debugging files into. Enable this option to be able to read and 658 write to these files. 659 660 For detailed documentation on the debugfs API, see 661 Documentation/filesystems/. 662 663 If unsure, say N. 664 665choice 666 prompt "Debugfs default access" 667 depends on DEBUG_FS 668 default DEBUG_FS_ALLOW_ALL 669 help 670 This selects the default access restrictions for debugfs. 671 It can be overridden with kernel command line option 672 debugfs=[on,no-mount,off]. The restrictions apply for API access 673 and filesystem registration. 674 675config DEBUG_FS_ALLOW_ALL 676 bool "Access normal" 677 help 678 No restrictions apply. Both API and filesystem registration 679 is on. This is the normal default operation. 680 681config DEBUG_FS_DISALLOW_MOUNT 682 bool "Do not register debugfs as filesystem" 683 help 684 The API is open but filesystem is not loaded. Clients can still do 685 their work and read with debug tools that do not need 686 debugfs filesystem. 687 688config DEBUG_FS_ALLOW_NONE 689 bool "No access" 690 help 691 Access is off. Clients get -PERM when trying to create nodes in 692 debugfs tree and debugfs is not registered as a filesystem. 693 Client can then back-off or continue without debugfs access. 694 695endchoice 696 697source "lib/Kconfig.kgdb" 698source "lib/Kconfig.ubsan" 699source "lib/Kconfig.kcsan" 700 701endmenu 702 703menu "Networking Debugging" 704 705source "net/Kconfig.debug" 706 707endmenu # "Networking Debugging" 708 709menu "Memory Debugging" 710 711source "mm/Kconfig.debug" 712 713config DEBUG_OBJECTS 714 bool "Debug object operations" 715 depends on DEBUG_KERNEL 716 help 717 If you say Y here, additional code will be inserted into the 718 kernel to track the life time of various objects and validate 719 the operations on those objects. 720 721config DEBUG_OBJECTS_SELFTEST 722 bool "Debug objects selftest" 723 depends on DEBUG_OBJECTS 724 help 725 This enables the selftest of the object debug code. 726 727config DEBUG_OBJECTS_FREE 728 bool "Debug objects in freed memory" 729 depends on DEBUG_OBJECTS 730 help 731 This enables checks whether a k/v free operation frees an area 732 which contains an object which has not been deactivated 733 properly. This can make kmalloc/kfree-intensive workloads 734 much slower. 735 736config DEBUG_OBJECTS_TIMERS 737 bool "Debug timer objects" 738 depends on DEBUG_OBJECTS 739 help 740 If you say Y here, additional code will be inserted into the 741 timer routines to track the life time of timer objects and 742 validate the timer operations. 743 744config DEBUG_OBJECTS_WORK 745 bool "Debug work objects" 746 depends on DEBUG_OBJECTS 747 help 748 If you say Y here, additional code will be inserted into the 749 work queue routines to track the life time of work objects and 750 validate the work operations. 751 752config DEBUG_OBJECTS_RCU_HEAD 753 bool "Debug RCU callbacks objects" 754 depends on DEBUG_OBJECTS 755 help 756 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 757 758config DEBUG_OBJECTS_PERCPU_COUNTER 759 bool "Debug percpu counter objects" 760 depends on DEBUG_OBJECTS 761 help 762 If you say Y here, additional code will be inserted into the 763 percpu counter routines to track the life time of percpu counter 764 objects and validate the percpu counter operations. 765 766config DEBUG_OBJECTS_ENABLE_DEFAULT 767 int "debug_objects bootup default value (0-1)" 768 range 0 1 769 default "1" 770 depends on DEBUG_OBJECTS 771 help 772 Debug objects boot parameter default value 773 774config SHRINKER_DEBUG 775 bool "Enable shrinker debugging support" 776 depends on DEBUG_FS 777 help 778 Say Y to enable the shrinker debugfs interface which provides 779 visibility into the kernel memory shrinkers subsystem. 780 Disable it to avoid an extra memory footprint. 781 782config DEBUG_STACK_USAGE 783 bool "Stack utilization instrumentation" 784 depends on DEBUG_KERNEL 785 help 786 Enables the display of the minimum amount of free stack which each 787 task has ever had available in the sysrq-T and sysrq-P debug output. 788 Also emits a message to dmesg when a process exits if that process 789 used more stack space than previously exiting processes. 790 791 This option will slow down process creation somewhat. 792 793config SCHED_STACK_END_CHECK 794 bool "Detect stack corruption on calls to schedule()" 795 depends on DEBUG_KERNEL 796 default n 797 help 798 This option checks for a stack overrun on calls to schedule(). 799 If the stack end location is found to be over written always panic as 800 the content of the corrupted region can no longer be trusted. 801 This is to ensure no erroneous behaviour occurs which could result in 802 data corruption or a sporadic crash at a later stage once the region 803 is examined. The runtime overhead introduced is minimal. 804 805config ARCH_HAS_DEBUG_VM_PGTABLE 806 bool 807 help 808 An architecture should select this when it can successfully 809 build and run DEBUG_VM_PGTABLE. 810 811config DEBUG_VM_IRQSOFF 812 def_bool DEBUG_VM && !PREEMPT_RT 813 814config DEBUG_VM 815 bool "Debug VM" 816 depends on DEBUG_KERNEL 817 help 818 Enable this to turn on extended checks in the virtual-memory system 819 that may impact performance. 820 821 If unsure, say N. 822 823config DEBUG_VM_SHOOT_LAZIES 824 bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation" 825 depends on DEBUG_VM 826 depends on MMU_LAZY_TLB_SHOOTDOWN 827 help 828 Enable additional IPIs that ensure lazy tlb mm references are removed 829 before the mm is freed. 830 831 If unsure, say N. 832 833config DEBUG_VM_MAPLE_TREE 834 bool "Debug VM maple trees" 835 depends on DEBUG_VM 836 select DEBUG_MAPLE_TREE 837 help 838 Enable VM maple tree debugging information and extra validations. 839 840 If unsure, say N. 841 842config DEBUG_VM_RB 843 bool "Debug VM red-black trees" 844 depends on DEBUG_VM 845 help 846 Enable VM red-black tree debugging information and extra validations. 847 848 If unsure, say N. 849 850config DEBUG_VM_PGFLAGS 851 bool "Debug page-flags operations" 852 depends on DEBUG_VM 853 help 854 Enables extra validation on page flags operations. 855 856 If unsure, say N. 857 858config DEBUG_VM_PGTABLE 859 bool "Debug arch page table for semantics compliance" 860 depends on MMU 861 depends on ARCH_HAS_DEBUG_VM_PGTABLE 862 default y if DEBUG_VM 863 help 864 This option provides a debug method which can be used to test 865 architecture page table helper functions on various platforms in 866 verifying if they comply with expected generic MM semantics. This 867 will help architecture code in making sure that any changes or 868 new additions of these helpers still conform to expected 869 semantics of the generic MM. Platforms will have to opt in for 870 this through ARCH_HAS_DEBUG_VM_PGTABLE. 871 872 If unsure, say N. 873 874config ARCH_HAS_DEBUG_VIRTUAL 875 bool 876 877config DEBUG_VIRTUAL 878 bool "Debug VM translations" 879 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL 880 help 881 Enable some costly sanity checks in virtual to page code. This can 882 catch mistakes with virt_to_page() and friends. 883 884 If unsure, say N. 885 886config DEBUG_NOMMU_REGIONS 887 bool "Debug the global anon/private NOMMU mapping region tree" 888 depends on DEBUG_KERNEL && !MMU 889 help 890 This option causes the global tree of anonymous and private mapping 891 regions to be regularly checked for invalid topology. 892 893config DEBUG_MEMORY_INIT 894 bool "Debug memory initialisation" if EXPERT 895 default !EXPERT 896 help 897 Enable this for additional checks during memory initialisation. 898 The sanity checks verify aspects of the VM such as the memory model 899 and other information provided by the architecture. Verbose 900 information will be printed at KERN_DEBUG loglevel depending 901 on the mminit_loglevel= command-line option. 902 903 If unsure, say Y 904 905config MEMORY_NOTIFIER_ERROR_INJECT 906 tristate "Memory hotplug notifier error injection module" 907 depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION 908 help 909 This option provides the ability to inject artificial errors to 910 memory hotplug notifier chain callbacks. It is controlled through 911 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 912 913 If the notifier call chain should be failed with some events 914 notified, write the error code to "actions/<notifier event>/error". 915 916 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 917 918 # cd /sys/kernel/debug/notifier-error-inject/memory 919 # echo -12 > actions/MEM_GOING_OFFLINE/error 920 # echo offline > /sys/devices/system/memory/memoryXXX/state 921 bash: echo: write error: Cannot allocate memory 922 923 To compile this code as a module, choose M here: the module will 924 be called memory-notifier-error-inject. 925 926 If unsure, say N. 927 928config DEBUG_PER_CPU_MAPS 929 bool "Debug access to per_cpu maps" 930 depends on DEBUG_KERNEL 931 depends on SMP 932 help 933 Say Y to verify that the per_cpu map being accessed has 934 been set up. This adds a fair amount of code to kernel memory 935 and decreases performance. 936 937 Say N if unsure. 938 939config DEBUG_KMAP_LOCAL 940 bool "Debug kmap_local temporary mappings" 941 depends on DEBUG_KERNEL && KMAP_LOCAL 942 help 943 This option enables additional error checking for the kmap_local 944 infrastructure. Disable for production use. 945 946config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 947 bool 948 949config DEBUG_KMAP_LOCAL_FORCE_MAP 950 bool "Enforce kmap_local temporary mappings" 951 depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 952 select KMAP_LOCAL 953 select DEBUG_KMAP_LOCAL 954 help 955 This option enforces temporary mappings through the kmap_local 956 mechanism for non-highmem pages and on non-highmem systems. 957 Disable this for production systems! 958 959config DEBUG_HIGHMEM 960 bool "Highmem debugging" 961 depends on DEBUG_KERNEL && HIGHMEM 962 select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 963 select DEBUG_KMAP_LOCAL 964 help 965 This option enables additional error checking for high memory 966 systems. Disable for production systems. 967 968config HAVE_DEBUG_STACKOVERFLOW 969 bool 970 971config DEBUG_STACKOVERFLOW 972 bool "Check for stack overflows" 973 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 974 help 975 Say Y here if you want to check for overflows of kernel, IRQ 976 and exception stacks (if your architecture uses them). This 977 option will show detailed messages if free stack space drops 978 below a certain limit. 979 980 These kinds of bugs usually occur when call-chains in the 981 kernel get too deep, especially when interrupts are 982 involved. 983 984 Use this in cases where you see apparently random memory 985 corruption, especially if it appears in 'struct thread_info' 986 987 If in doubt, say "N". 988 989config CODE_TAGGING 990 bool 991 select KALLSYMS 992 993config MEM_ALLOC_PROFILING 994 bool "Enable memory allocation profiling" 995 default n 996 depends on PROC_FS 997 depends on !DEBUG_FORCE_WEAK_PER_CPU 998 select CODE_TAGGING 999 select PAGE_EXTENSION 1000 select SLAB_OBJ_EXT 1001 help 1002 Track allocation source code and record total allocation size 1003 initiated at that code location. The mechanism can be used to track 1004 memory leaks with a low performance and memory impact. 1005 1006config MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT 1007 bool "Enable memory allocation profiling by default" 1008 default y 1009 depends on MEM_ALLOC_PROFILING 1010 1011config MEM_ALLOC_PROFILING_DEBUG 1012 bool "Memory allocation profiler debugging" 1013 default n 1014 depends on MEM_ALLOC_PROFILING 1015 select MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT 1016 help 1017 Adds warnings with helpful error messages for memory allocation 1018 profiling. 1019 1020source "lib/Kconfig.kasan" 1021source "lib/Kconfig.kfence" 1022source "lib/Kconfig.kmsan" 1023 1024endmenu # "Memory Debugging" 1025 1026config DEBUG_SHIRQ 1027 bool "Debug shared IRQ handlers" 1028 depends on DEBUG_KERNEL 1029 help 1030 Enable this to generate a spurious interrupt just before a shared 1031 interrupt handler is deregistered (generating one when registering 1032 is currently disabled). Drivers need to handle this correctly. Some 1033 don't and need to be caught. 1034 1035menu "Debug Oops, Lockups and Hangs" 1036 1037config PANIC_ON_OOPS 1038 bool "Panic on Oops" 1039 help 1040 Say Y here to enable the kernel to panic when it oopses. This 1041 has the same effect as setting oops=panic on the kernel command 1042 line. 1043 1044 This feature is useful to ensure that the kernel does not do 1045 anything erroneous after an oops which could result in data 1046 corruption or other issues. 1047 1048 Say N if unsure. 1049 1050config PANIC_ON_OOPS_VALUE 1051 int 1052 range 0 1 1053 default 0 if !PANIC_ON_OOPS 1054 default 1 if PANIC_ON_OOPS 1055 1056config PANIC_TIMEOUT 1057 int "panic timeout" 1058 default 0 1059 help 1060 Set the timeout value (in seconds) until a reboot occurs when 1061 the kernel panics. If n = 0, then we wait forever. A timeout 1062 value n > 0 will wait n seconds before rebooting, while a timeout 1063 value n < 0 will reboot immediately. This setting can be overridden 1064 with the kernel command line option panic=, and from userspace via 1065 /proc/sys/kernel/panic. 1066 1067config LOCKUP_DETECTOR 1068 bool 1069 1070config SOFTLOCKUP_DETECTOR 1071 bool "Detect Soft Lockups" 1072 depends on DEBUG_KERNEL && !S390 1073 select LOCKUP_DETECTOR 1074 help 1075 Say Y here to enable the kernel to act as a watchdog to detect 1076 soft lockups. 1077 1078 Softlockups are bugs that cause the kernel to loop in kernel 1079 mode for more than 20 seconds, without giving other tasks a 1080 chance to run. The current stack trace is displayed upon 1081 detection and the system will stay locked up. 1082 1083config SOFTLOCKUP_DETECTOR_INTR_STORM 1084 bool "Detect Interrupt Storm in Soft Lockups" 1085 depends on SOFTLOCKUP_DETECTOR && IRQ_TIME_ACCOUNTING 1086 select GENERIC_IRQ_STAT_SNAPSHOT 1087 default y if NR_CPUS <= 128 1088 help 1089 Say Y here to enable the kernel to detect interrupt storm 1090 during "soft lockups". 1091 1092 "soft lockups" can be caused by a variety of reasons. If one is 1093 caused by an interrupt storm, then the storming interrupts will not 1094 be on the callstack. To detect this case, it is necessary to report 1095 the CPU stats and the interrupt counts during the "soft lockups". 1096 1097config BOOTPARAM_SOFTLOCKUP_PANIC 1098 bool "Panic (Reboot) On Soft Lockups" 1099 depends on SOFTLOCKUP_DETECTOR 1100 help 1101 Say Y here to enable the kernel to panic on "soft lockups", 1102 which are bugs that cause the kernel to loop in kernel 1103 mode for more than 20 seconds (configurable using the watchdog_thresh 1104 sysctl), without giving other tasks a chance to run. 1105 1106 The panic can be used in combination with panic_timeout, 1107 to cause the system to reboot automatically after a 1108 lockup has been detected. This feature is useful for 1109 high-availability systems that have uptime guarantees and 1110 where a lockup must be resolved ASAP. 1111 1112 Say N if unsure. 1113 1114config HAVE_HARDLOCKUP_DETECTOR_BUDDY 1115 bool 1116 depends on SMP 1117 default y 1118 1119# 1120# Global switch whether to build a hardlockup detector at all. It is available 1121# only when the architecture supports at least one implementation. There are 1122# two exceptions. The hardlockup detector is never enabled on: 1123# 1124# s390: it reported many false positives there 1125# 1126# sparc64: has a custom implementation which is not using the common 1127# hardlockup command line options and sysctl interface. 1128# 1129config HARDLOCKUP_DETECTOR 1130 bool "Detect Hard Lockups" 1131 depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64 1132 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH 1133 imply HARDLOCKUP_DETECTOR_PERF 1134 imply HARDLOCKUP_DETECTOR_BUDDY 1135 imply HARDLOCKUP_DETECTOR_ARCH 1136 select LOCKUP_DETECTOR 1137 1138 help 1139 Say Y here to enable the kernel to act as a watchdog to detect 1140 hard lockups. 1141 1142 Hardlockups are bugs that cause the CPU to loop in kernel mode 1143 for more than 10 seconds, without letting other interrupts have a 1144 chance to run. The current stack trace is displayed upon detection 1145 and the system will stay locked up. 1146 1147# 1148# Note that arch-specific variants are always preferred. 1149# 1150config HARDLOCKUP_DETECTOR_PREFER_BUDDY 1151 bool "Prefer the buddy CPU hardlockup detector" 1152 depends on HARDLOCKUP_DETECTOR 1153 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY 1154 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1155 help 1156 Say Y here to prefer the buddy hardlockup detector over the perf one. 1157 1158 With the buddy detector, each CPU uses its softlockup hrtimer 1159 to check that the next CPU is processing hrtimer interrupts by 1160 verifying that a counter is increasing. 1161 1162 This hardlockup detector is useful on systems that don't have 1163 an arch-specific hardlockup detector or if resources needed 1164 for the hardlockup detector are better used for other things. 1165 1166config HARDLOCKUP_DETECTOR_PERF 1167 bool 1168 depends on HARDLOCKUP_DETECTOR 1169 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY 1170 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1171 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1172 1173config HARDLOCKUP_DETECTOR_BUDDY 1174 bool 1175 depends on HARDLOCKUP_DETECTOR 1176 depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY 1177 depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY 1178 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1179 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1180 1181config HARDLOCKUP_DETECTOR_ARCH 1182 bool 1183 depends on HARDLOCKUP_DETECTOR 1184 depends on HAVE_HARDLOCKUP_DETECTOR_ARCH 1185 help 1186 The arch-specific implementation of the hardlockup detector will 1187 be used. 1188 1189# 1190# Both the "perf" and "buddy" hardlockup detectors count hrtimer 1191# interrupts. This config enables functions managing this common code. 1192# 1193config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1194 bool 1195 select SOFTLOCKUP_DETECTOR 1196 1197# 1198# Enables a timestamp based low pass filter to compensate for perf based 1199# hard lockup detection which runs too fast due to turbo modes. 1200# 1201config HARDLOCKUP_CHECK_TIMESTAMP 1202 bool 1203 1204config BOOTPARAM_HARDLOCKUP_PANIC 1205 bool "Panic (Reboot) On Hard Lockups" 1206 depends on HARDLOCKUP_DETECTOR 1207 help 1208 Say Y here to enable the kernel to panic on "hard lockups", 1209 which are bugs that cause the kernel to loop in kernel 1210 mode with interrupts disabled for more than 10 seconds (configurable 1211 using the watchdog_thresh sysctl). 1212 1213 Say N if unsure. 1214 1215config DETECT_HUNG_TASK 1216 bool "Detect Hung Tasks" 1217 depends on DEBUG_KERNEL 1218 default SOFTLOCKUP_DETECTOR 1219 help 1220 Say Y here to enable the kernel to detect "hung tasks", 1221 which are bugs that cause the task to be stuck in 1222 uninterruptible "D" state indefinitely. 1223 1224 When a hung task is detected, the kernel will print the 1225 current stack trace (which you should report), but the 1226 task will stay in uninterruptible state. If lockdep is 1227 enabled then all held locks will also be reported. This 1228 feature has negligible overhead. 1229 1230config DEFAULT_HUNG_TASK_TIMEOUT 1231 int "Default timeout for hung task detection (in seconds)" 1232 depends on DETECT_HUNG_TASK 1233 default 120 1234 help 1235 This option controls the default timeout (in seconds) used 1236 to determine when a task has become non-responsive and should 1237 be considered hung. 1238 1239 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 1240 sysctl or by writing a value to 1241 /proc/sys/kernel/hung_task_timeout_secs. 1242 1243 A timeout of 0 disables the check. The default is two minutes. 1244 Keeping the default should be fine in most cases. 1245 1246config BOOTPARAM_HUNG_TASK_PANIC 1247 bool "Panic (Reboot) On Hung Tasks" 1248 depends on DETECT_HUNG_TASK 1249 help 1250 Say Y here to enable the kernel to panic on "hung tasks", 1251 which are bugs that cause the kernel to leave a task stuck 1252 in uninterruptible "D" state. 1253 1254 The panic can be used in combination with panic_timeout, 1255 to cause the system to reboot automatically after a 1256 hung task has been detected. This feature is useful for 1257 high-availability systems that have uptime guarantees and 1258 where a hung tasks must be resolved ASAP. 1259 1260 Say N if unsure. 1261 1262config WQ_WATCHDOG 1263 bool "Detect Workqueue Stalls" 1264 depends on DEBUG_KERNEL 1265 help 1266 Say Y here to enable stall detection on workqueues. If a 1267 worker pool doesn't make forward progress on a pending work 1268 item for over a given amount of time, 30s by default, a 1269 warning message is printed along with dump of workqueue 1270 state. This can be configured through kernel parameter 1271 "workqueue.watchdog_thresh" and its sysfs counterpart. 1272 1273config WQ_CPU_INTENSIVE_REPORT 1274 bool "Report per-cpu work items which hog CPU for too long" 1275 depends on DEBUG_KERNEL 1276 help 1277 Say Y here to enable reporting of concurrency-managed per-cpu work 1278 items that hog CPUs for longer than 1279 workqueue.cpu_intensive_thresh_us. Workqueue automatically 1280 detects and excludes them from concurrency management to prevent 1281 them from stalling other per-cpu work items. Occassional 1282 triggering may not necessarily indicate a problem. Repeated 1283 triggering likely indicates that the work item should be switched 1284 to use an unbound workqueue. 1285 1286config TEST_LOCKUP 1287 tristate "Test module to generate lockups" 1288 depends on m 1289 help 1290 This builds the "test_lockup" module that helps to make sure 1291 that watchdogs and lockup detectors are working properly. 1292 1293 Depending on module parameters it could emulate soft or hard 1294 lockup, "hung task", or locking arbitrary lock for a long time. 1295 Also it could generate series of lockups with cooling-down periods. 1296 1297 If unsure, say N. 1298 1299endmenu # "Debug lockups and hangs" 1300 1301menu "Scheduler Debugging" 1302 1303config SCHED_DEBUG 1304 bool "Collect scheduler debugging info" 1305 depends on DEBUG_KERNEL && DEBUG_FS 1306 default y 1307 help 1308 If you say Y here, the /sys/kernel/debug/sched file will be provided 1309 that can help debug the scheduler. The runtime overhead of this 1310 option is minimal. 1311 1312config SCHED_INFO 1313 bool 1314 default n 1315 1316config SCHEDSTATS 1317 bool "Collect scheduler statistics" 1318 depends on PROC_FS 1319 select SCHED_INFO 1320 help 1321 If you say Y here, additional code will be inserted into the 1322 scheduler and related routines to collect statistics about 1323 scheduler behavior and provide them in /proc/schedstat. These 1324 stats may be useful for both tuning and debugging the scheduler 1325 If you aren't debugging the scheduler or trying to tune a specific 1326 application, you can say N to avoid the very slight overhead 1327 this adds. 1328 1329endmenu 1330 1331config DEBUG_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 1344config DEBUG_PREEMPT 1345 bool "Debug preemptible kernel" 1346 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1347 help 1348 If you say Y here then the kernel will use a debug variant of the 1349 commonly used smp_processor_id() function and will print warnings 1350 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1351 will detect preemption count underflows. 1352 1353 This option has potential to introduce high runtime overhead, 1354 depending on workload as it triggers debugging routines for each 1355 this_cpu operation. It should only be used for debugging purposes. 1356 1357menu "Lock Debugging (spinlocks, mutexes, etc...)" 1358 1359config LOCK_DEBUGGING_SUPPORT 1360 bool 1361 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1362 default y 1363 1364config PROVE_LOCKING 1365 bool "Lock debugging: prove locking correctness" 1366 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1367 select LOCKDEP 1368 select DEBUG_SPINLOCK 1369 select DEBUG_MUTEXES if !PREEMPT_RT 1370 select DEBUG_RT_MUTEXES if RT_MUTEXES 1371 select DEBUG_RWSEMS if !PREEMPT_RT 1372 select DEBUG_WW_MUTEX_SLOWPATH 1373 select DEBUG_LOCK_ALLOC 1374 select PREEMPT_COUNT if !ARCH_NO_PREEMPT 1375 select TRACE_IRQFLAGS 1376 default n 1377 help 1378 This feature enables the kernel to prove that all locking 1379 that occurs in the kernel runtime is mathematically 1380 correct: that under no circumstance could an arbitrary (and 1381 not yet triggered) combination of observed locking 1382 sequences (on an arbitrary number of CPUs, running an 1383 arbitrary number of tasks and interrupt contexts) cause a 1384 deadlock. 1385 1386 In short, this feature enables the kernel to report locking 1387 related deadlocks before they actually occur. 1388 1389 The proof does not depend on how hard and complex a 1390 deadlock scenario would be to trigger: how many 1391 participant CPUs, tasks and irq-contexts would be needed 1392 for it to trigger. The proof also does not depend on 1393 timing: if a race and a resulting deadlock is possible 1394 theoretically (no matter how unlikely the race scenario 1395 is), it will be proven so and will immediately be 1396 reported by the kernel (once the event is observed that 1397 makes the deadlock theoretically possible). 1398 1399 If a deadlock is impossible (i.e. the locking rules, as 1400 observed by the kernel, are mathematically correct), the 1401 kernel reports nothing. 1402 1403 NOTE: this feature can also be enabled for rwlocks, mutexes 1404 and rwsems - in which case all dependencies between these 1405 different locking variants are observed and mapped too, and 1406 the proof of observed correctness is also maintained for an 1407 arbitrary combination of these separate locking variants. 1408 1409 For more details, see Documentation/locking/lockdep-design.rst. 1410 1411config PROVE_RAW_LOCK_NESTING 1412 bool "Enable raw_spinlock - spinlock nesting checks" 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 1428config 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 1450config 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 1457config 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 1467config 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 1474config 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 1492config 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 1499config 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 1514config LOCKDEP 1515 bool 1516 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1517 select STACKTRACE 1518 select KALLSYMS 1519 select KALLSYMS_ALL 1520 1521config LOCKDEP_SMALL 1522 bool 1523 1524config 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 1532config 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 1540config 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 1548config 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 1556config 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 1564config 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 1573config 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 1584config 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 1595config 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 1609config 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 1621config 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 1631config 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 1643config 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 1652endmenu # lock debugging 1653 1654config 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 1661config TRACE_IRQFLAGS_NMI 1662 def_bool y 1663 depends on TRACE_IRQFLAGS 1664 depends on TRACE_IRQFLAGS_NMI_SUPPORT 1665 1666config 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 1677config 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 1684config 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 1693config 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 1720config 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 1727config 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 1746config HAVE_DEBUG_BUGVERBOSE 1747 bool 1748 1749menu "Debug kernel data structures" 1750 1751config 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 1765config 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 1775config 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 1785config 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 1795config 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 1804config 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 1812endmenu 1813 1814source "kernel/rcu/Kconfig.debug" 1815 1816config 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 1831config 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 1844config 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 1858config 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 1868source "kernel/trace/Kconfig" 1869 1870config 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 1899source "samples/Kconfig" 1900 1901config ARCH_HAS_DEVMEM_IS_ALLOWED 1902 bool 1903 1904config 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 1924config 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 1940menu "$(SRCARCH) Debugging" 1941 1942source "arch/$(SRCARCH)/Kconfig.debug" 1943 1944endmenu 1945 1946menu "Kernel Testing and Coverage" 1947 1948source "lib/kunit/Kconfig" 1949 1950config 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 1961config 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 1985config 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 2002config 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 2025config 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 2035config 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 2042config FAILSLAB 2043 bool "Fault-injection capability for kmalloc" 2044 depends on FAULT_INJECTION 2045 help 2046 Provide fault-injection capability for kmalloc. 2047 2048config 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 2054config 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 2061config 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 2067config 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 2078config 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 2085config 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 2091config 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 2101config 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 2111config 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 2118config FAIL_SKB_REALLOC 2119 bool "Fault-injection capability forcing skb to reallocate" 2120 depends on FAULT_INJECTION_DEBUG_FS 2121 help 2122 Provide fault-injection capability that forces the skb to be 2123 reallocated, catching possible invalid pointers to the skb. 2124 2125 For more information, check 2126 Documentation/dev-tools/fault-injection/fault-injection.rst 2127 2128config FAULT_INJECTION_CONFIGFS 2129 bool "Configfs interface for fault-injection capabilities" 2130 depends on FAULT_INJECTION 2131 select CONFIGFS_FS 2132 help 2133 This option allows configfs-based drivers to dynamically configure 2134 fault-injection via configfs. Each parameter for driver-specific 2135 fault-injection can be made visible as a configfs attribute in a 2136 configfs group. 2137 2138 2139config FAULT_INJECTION_STACKTRACE_FILTER 2140 bool "stacktrace filter for fault-injection capabilities" 2141 depends on FAULT_INJECTION 2142 depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT 2143 select STACKTRACE 2144 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 2145 help 2146 Provide stacktrace filter for fault-injection capabilities 2147 2148config ARCH_HAS_KCOV 2149 bool 2150 help 2151 An architecture should select this when it can successfully 2152 build and run with CONFIG_KCOV. This typically requires 2153 disabling instrumentation for some early boot code. 2154 2155config CC_HAS_SANCOV_TRACE_PC 2156 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 2157 2158 2159config KCOV 2160 bool "Code coverage for fuzzing" 2161 depends on ARCH_HAS_KCOV 2162 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 2163 depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \ 2164 GCC_VERSION >= 120000 || CC_IS_CLANG 2165 select DEBUG_FS 2166 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 2167 select OBJTOOL if HAVE_NOINSTR_HACK 2168 help 2169 KCOV exposes kernel code coverage information in a form suitable 2170 for coverage-guided fuzzing (randomized testing). 2171 2172 For more details, see Documentation/dev-tools/kcov.rst. 2173 2174config KCOV_ENABLE_COMPARISONS 2175 bool "Enable comparison operands collection by KCOV" 2176 depends on KCOV 2177 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 2178 help 2179 KCOV also exposes operands of every comparison in the instrumented 2180 code along with operand sizes and PCs of the comparison instructions. 2181 These operands can be used by fuzzing engines to improve the quality 2182 of fuzzing coverage. 2183 2184config KCOV_INSTRUMENT_ALL 2185 bool "Instrument all code by default" 2186 depends on KCOV 2187 default y 2188 help 2189 If you are doing generic system call fuzzing (like e.g. syzkaller), 2190 then you will want to instrument the whole kernel and you should 2191 say y here. If you are doing more targeted fuzzing (like e.g. 2192 filesystem fuzzing with AFL) then you will want to enable coverage 2193 for more specific subsets of files, and should say n here. 2194 2195config KCOV_IRQ_AREA_SIZE 2196 hex "Size of interrupt coverage collection area in words" 2197 depends on KCOV 2198 default 0x40000 2199 help 2200 KCOV uses preallocated per-cpu areas to collect coverage from 2201 soft interrupts. This specifies the size of those areas in the 2202 number of unsigned long words. 2203 2204config KCOV_SELFTEST 2205 bool "Perform short selftests on boot" 2206 depends on KCOV 2207 help 2208 Run short KCOV coverage collection selftests on boot. 2209 On test failure, causes the kernel to panic. Recommended to be 2210 enabled, ensuring critical functionality works as intended. 2211 2212menuconfig RUNTIME_TESTING_MENU 2213 bool "Runtime Testing" 2214 default y 2215 2216if RUNTIME_TESTING_MENU 2217 2218config TEST_DHRY 2219 tristate "Dhrystone benchmark test" 2220 help 2221 Enable this to include the Dhrystone 2.1 benchmark. This test 2222 calculates the number of Dhrystones per second, and the number of 2223 DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided 2224 by 1757 (the number of Dhrystones per second obtained on the VAX 2225 11/780, nominally a 1 MIPS machine). 2226 2227 To run the benchmark, it needs to be enabled explicitly, either from 2228 the kernel command line (when built-in), or from userspace (when 2229 built-in or modular). 2230 2231 Run once during kernel boot: 2232 2233 test_dhry.run 2234 2235 Set number of iterations from kernel command line: 2236 2237 test_dhry.iterations=<n> 2238 2239 Set number of iterations from userspace: 2240 2241 echo <n> > /sys/module/test_dhry/parameters/iterations 2242 2243 Trigger manual run from userspace: 2244 2245 echo y > /sys/module/test_dhry/parameters/run 2246 2247 If the number of iterations is <= 0, the test will devise a suitable 2248 number of iterations (test runs for at least 2s) automatically. 2249 This process takes ca. 4s. 2250 2251 If unsure, say N. 2252 2253config LKDTM 2254 tristate "Linux Kernel Dump Test Tool Module" 2255 depends on DEBUG_FS 2256 help 2257 This module enables testing of the different dumping mechanisms by 2258 inducing system failures at predefined crash points. 2259 If you don't need it: say N 2260 Choose M here to compile this code as a module. The module will be 2261 called lkdtm. 2262 2263 Documentation on how to use the module can be found in 2264 Documentation/fault-injection/provoke-crashes.rst 2265 2266config CPUMASK_KUNIT_TEST 2267 tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS 2268 depends on KUNIT 2269 default KUNIT_ALL_TESTS 2270 help 2271 Enable to turn on cpumask tests, running at boot or module load time. 2272 2273 For more information on KUnit and unit tests in general, please refer 2274 to the KUnit documentation in Documentation/dev-tools/kunit/. 2275 2276 If unsure, say N. 2277 2278config TEST_LIST_SORT 2279 tristate "Linked list sorting test" if !KUNIT_ALL_TESTS 2280 depends on KUNIT 2281 default KUNIT_ALL_TESTS 2282 help 2283 Enable this to turn on 'list_sort()' function test. 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 2289config TEST_MIN_HEAP 2290 tristate "Min heap test" 2291 depends on DEBUG_KERNEL || m 2292 help 2293 Enable this to turn on min heap function tests. This test is 2294 executed only once during system boot (so affects only boot time), 2295 or at module load time. 2296 2297 If unsure, say N. 2298 2299config TEST_SORT 2300 tristate "Array-based sort test" if !KUNIT_ALL_TESTS 2301 depends on KUNIT 2302 default KUNIT_ALL_TESTS 2303 help 2304 This option enables the self-test function of 'sort()' at boot, 2305 or at module load time. 2306 2307 If unsure, say N. 2308 2309config TEST_DIV64 2310 tristate "64bit/32bit division and modulo test" 2311 depends on DEBUG_KERNEL || m 2312 help 2313 Enable this to turn on 'do_div()' function test. This test is 2314 executed only once during system boot (so affects only boot time), 2315 or at module load time. 2316 2317 If unsure, say N. 2318 2319config TEST_MULDIV64 2320 tristate "mul_u64_u64_div_u64() test" 2321 depends on DEBUG_KERNEL || m 2322 help 2323 Enable this to turn on 'mul_u64_u64_div_u64()' function test. 2324 This test is executed only once during system boot (so affects 2325 only boot time), or at module load time. 2326 2327 If unsure, say N. 2328 2329config TEST_IOV_ITER 2330 tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS 2331 depends on KUNIT 2332 depends on MMU 2333 default KUNIT_ALL_TESTS 2334 help 2335 Enable this to turn on testing of the operation of the I/O iterator 2336 (iov_iter). This test is executed only once during system boot (so 2337 affects only boot time), or at module load time. 2338 2339 If unsure, say N. 2340 2341config KPROBES_SANITY_TEST 2342 tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS 2343 depends on DEBUG_KERNEL 2344 depends on KPROBES 2345 depends on KUNIT 2346 select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 2347 default KUNIT_ALL_TESTS 2348 help 2349 This option provides for testing basic kprobes functionality on 2350 boot. Samples of kprobe and kretprobe are inserted and 2351 verified for functionality. 2352 2353 Say N if you are unsure. 2354 2355config FPROBE_SANITY_TEST 2356 bool "Self test for fprobe" 2357 depends on DEBUG_KERNEL 2358 depends on FPROBE 2359 depends on KUNIT=y 2360 help 2361 This option will enable testing the fprobe when the system boot. 2362 A series of tests are made to verify that the fprobe is functioning 2363 properly. 2364 2365 Say N if you are unsure. 2366 2367config BACKTRACE_SELF_TEST 2368 tristate "Self test for the backtrace code" 2369 depends on DEBUG_KERNEL 2370 help 2371 This option provides a kernel module that can be used to test 2372 the kernel stack backtrace code. This option is not useful 2373 for distributions or general kernels, but only for kernel 2374 developers working on architecture code. 2375 2376 Note that if you want to also test saved backtraces, you will 2377 have to enable STACKTRACE as well. 2378 2379 Say N if you are unsure. 2380 2381config TEST_REF_TRACKER 2382 tristate "Self test for reference tracker" 2383 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT 2384 select REF_TRACKER 2385 help 2386 This option provides a kernel module performing tests 2387 using reference tracker infrastructure. 2388 2389 Say N if you are unsure. 2390 2391config RBTREE_TEST 2392 tristate "Red-Black tree test" 2393 depends on DEBUG_KERNEL 2394 help 2395 A benchmark measuring the performance of the rbtree library. 2396 Also includes rbtree invariant checks. 2397 2398config REED_SOLOMON_TEST 2399 tristate "Reed-Solomon library test" 2400 depends on DEBUG_KERNEL || m 2401 select REED_SOLOMON 2402 select REED_SOLOMON_ENC16 2403 select REED_SOLOMON_DEC16 2404 help 2405 This option enables the self-test function of rslib at boot, 2406 or at module load time. 2407 2408 If unsure, say N. 2409 2410config INTERVAL_TREE_TEST 2411 tristate "Interval tree test" 2412 depends on DEBUG_KERNEL 2413 select INTERVAL_TREE 2414 help 2415 A benchmark measuring the performance of the interval tree library 2416 2417config PERCPU_TEST 2418 tristate "Per cpu operations test" 2419 depends on m && DEBUG_KERNEL 2420 help 2421 Enable this option to build test module which validates per-cpu 2422 operations. 2423 2424 If unsure, say N. 2425 2426config ATOMIC64_SELFTEST 2427 tristate "Perform an atomic64_t self-test" 2428 help 2429 Enable this option to test the atomic64_t functions at boot or 2430 at module load time. 2431 2432 If unsure, say N. 2433 2434config ASYNC_RAID6_TEST 2435 tristate "Self test for hardware accelerated raid6 recovery" 2436 depends on ASYNC_RAID6_RECOV 2437 select ASYNC_MEMCPY 2438 help 2439 This is a one-shot self test that permutes through the 2440 recovery of all the possible two disk failure scenarios for a 2441 N-disk array. Recovery is performed with the asynchronous 2442 raid6 recovery routines, and will optionally use an offload 2443 engine if one is available. 2444 2445 If unsure, say N. 2446 2447config TEST_HEXDUMP 2448 tristate "Test functions located in the hexdump module at runtime" 2449 2450config STRING_KUNIT_TEST 2451 tristate "KUnit test string functions at runtime" if !KUNIT_ALL_TESTS 2452 depends on KUNIT 2453 default KUNIT_ALL_TESTS 2454 2455config STRING_HELPERS_KUNIT_TEST 2456 tristate "KUnit test string helpers at runtime" if !KUNIT_ALL_TESTS 2457 depends on KUNIT 2458 default KUNIT_ALL_TESTS 2459 2460config TEST_KSTRTOX 2461 tristate "Test kstrto*() family of functions at runtime" 2462 2463config TEST_PRINTF 2464 tristate "Test printf() family of functions at runtime" 2465 2466config TEST_SCANF 2467 tristate "Test scanf() family of functions at runtime" 2468 2469config TEST_BITMAP 2470 tristate "Test bitmap_*() family of functions at runtime" 2471 help 2472 Enable this option to test the bitmap functions at boot. 2473 2474 If unsure, say N. 2475 2476config TEST_UUID 2477 tristate "Test functions located in the uuid module at runtime" 2478 2479config TEST_XARRAY 2480 tristate "Test the XArray code at runtime" 2481 2482config TEST_MAPLE_TREE 2483 tristate "Test the Maple Tree code at runtime or module load" 2484 help 2485 Enable this option to test the maple tree code functions at boot, or 2486 when the module is loaded. Enable "Debug Maple Trees" will enable 2487 more verbose output on failures. 2488 2489 If unsure, say N. 2490 2491config TEST_RHASHTABLE 2492 tristate "Perform selftest on resizable hash table" 2493 help 2494 Enable this option to test the rhashtable functions at boot. 2495 2496 If unsure, say N. 2497 2498config TEST_IDA 2499 tristate "Perform selftest on IDA functions" 2500 2501config TEST_PARMAN 2502 tristate "Perform selftest on priority array manager" 2503 depends on PARMAN 2504 help 2505 Enable this option to test priority array manager on boot 2506 (or module load). 2507 2508 If unsure, say N. 2509 2510config TEST_IRQ_TIMINGS 2511 bool "IRQ timings selftest" 2512 depends on IRQ_TIMINGS 2513 help 2514 Enable this option to test the irq timings code on boot. 2515 2516 If unsure, say N. 2517 2518config TEST_LKM 2519 tristate "Test module loading with 'hello world' module" 2520 depends on m 2521 help 2522 This builds the "test_module" module that emits "Hello, world" 2523 on printk when loaded. It is designed to be used for basic 2524 evaluation of the module loading subsystem (for example when 2525 validating module verification). It lacks any extra dependencies, 2526 and will not normally be loaded by the system unless explicitly 2527 requested by name. 2528 2529 If unsure, say N. 2530 2531config TEST_BITOPS 2532 tristate "Test module for compilation of bitops operations" 2533 help 2534 This builds the "test_bitops" module that is much like the 2535 TEST_LKM module except that it does a basic exercise of the 2536 set/clear_bit macros and get_count_order/long to make sure there are 2537 no compiler warnings from C=1 sparse checker or -Wextra 2538 compilations. It has no dependencies and doesn't run or load unless 2539 explicitly requested by name. for example: modprobe test_bitops. 2540 2541 If unsure, say N. 2542 2543config TEST_VMALLOC 2544 tristate "Test module for stress/performance analysis of vmalloc allocator" 2545 default n 2546 depends on MMU 2547 depends on m 2548 help 2549 This builds the "test_vmalloc" module that should be used for 2550 stress and performance analysis. So, any new change for vmalloc 2551 subsystem can be evaluated from performance and stability point 2552 of view. 2553 2554 If unsure, say N. 2555 2556config TEST_BPF 2557 tristate "Test BPF filter functionality" 2558 depends on m && NET 2559 help 2560 This builds the "test_bpf" module that runs various test vectors 2561 against the BPF interpreter or BPF JIT compiler depending on the 2562 current setting. This is in particular useful for BPF JIT compiler 2563 development, but also to run regression tests against changes in 2564 the interpreter code. It also enables test stubs for eBPF maps and 2565 verifier used by user space verifier testsuite. 2566 2567 If unsure, say N. 2568 2569config TEST_BLACKHOLE_DEV 2570 tristate "Test blackhole netdev functionality" 2571 depends on m && NET 2572 help 2573 This builds the "test_blackhole_dev" module that validates the 2574 data path through this blackhole netdev. 2575 2576 If unsure, say N. 2577 2578config FIND_BIT_BENCHMARK 2579 tristate "Test find_bit functions" 2580 help 2581 This builds the "test_find_bit" module that measure find_*_bit() 2582 functions performance. 2583 2584 If unsure, say N. 2585 2586config TEST_FIRMWARE 2587 tristate "Test firmware loading via userspace interface" 2588 depends on FW_LOADER 2589 help 2590 This builds the "test_firmware" module that creates a userspace 2591 interface for testing firmware loading. This can be used to 2592 control the triggering of firmware loading without needing an 2593 actual firmware-using device. The contents can be rechecked by 2594 userspace. 2595 2596 If unsure, say N. 2597 2598config TEST_SYSCTL 2599 tristate "sysctl test driver" 2600 depends on PROC_SYSCTL 2601 help 2602 This builds the "test_sysctl" module. This driver enables to test the 2603 proc sysctl interfaces available to drivers safely without affecting 2604 production knobs which might alter system functionality. 2605 2606 If unsure, say N. 2607 2608config BITFIELD_KUNIT 2609 tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS 2610 depends on KUNIT 2611 default KUNIT_ALL_TESTS 2612 help 2613 Enable this option to test the bitfield functions at boot. 2614 2615 KUnit tests run during boot and output the results to the debug log 2616 in TAP format (http://testanything.org/). Only useful for kernel devs 2617 running the KUnit test harness, and not intended for inclusion into a 2618 production build. 2619 2620 For more information on KUnit and unit tests in general please refer 2621 to the KUnit documentation in Documentation/dev-tools/kunit/. 2622 2623 If unsure, say N. 2624 2625config CHECKSUM_KUNIT 2626 tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS 2627 depends on KUNIT 2628 default KUNIT_ALL_TESTS 2629 help 2630 Enable this option to test the checksum functions at boot. 2631 2632 KUnit tests run during boot and output the results to the debug log 2633 in TAP format (http://testanything.org/). Only useful for kernel devs 2634 running the KUnit test harness, and not intended for inclusion into a 2635 production build. 2636 2637 For more information on KUnit and unit tests in general please refer 2638 to the KUnit documentation in Documentation/dev-tools/kunit/. 2639 2640 If unsure, say N. 2641 2642config HASH_KUNIT_TEST 2643 tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS 2644 depends on KUNIT 2645 default KUNIT_ALL_TESTS 2646 help 2647 Enable this option to test the kernel's string (<linux/stringhash.h>), and 2648 integer (<linux/hash.h>) hash functions on boot. 2649 2650 KUnit tests run during boot and output the results to the debug log 2651 in TAP format (https://testanything.org/). Only useful for kernel devs 2652 running the KUnit test harness, and not intended for inclusion into a 2653 production build. 2654 2655 For more information on KUnit and unit tests in general please refer 2656 to the KUnit documentation in Documentation/dev-tools/kunit/. 2657 2658 This is intended to help people writing architecture-specific 2659 optimized versions. If unsure, say N. 2660 2661config RESOURCE_KUNIT_TEST 2662 tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS 2663 depends on KUNIT 2664 default KUNIT_ALL_TESTS 2665 select GET_FREE_REGION 2666 help 2667 This builds the resource API unit test. 2668 Tests the logic of API provided by resource.c and ioport.h. 2669 For more information on KUnit and unit tests in general please refer 2670 to the KUnit documentation in Documentation/dev-tools/kunit/. 2671 2672 If unsure, say N. 2673 2674config SYSCTL_KUNIT_TEST 2675 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS 2676 depends on KUNIT 2677 default KUNIT_ALL_TESTS 2678 help 2679 This builds the proc sysctl unit test, which runs on boot. 2680 Tests the API contract and implementation correctness of sysctl. 2681 For more information on KUnit and unit tests in general please refer 2682 to the KUnit documentation in Documentation/dev-tools/kunit/. 2683 2684 If unsure, say N. 2685 2686config LIST_KUNIT_TEST 2687 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS 2688 depends on KUNIT 2689 default KUNIT_ALL_TESTS 2690 help 2691 This builds the linked list KUnit test suite. 2692 It tests that the API and basic functionality of the list_head type 2693 and associated macros. 2694 2695 KUnit tests run during boot and output the results to the debug log 2696 in TAP format (https://testanything.org/). Only useful for kernel devs 2697 running the KUnit test harness, and not intended for inclusion into a 2698 production build. 2699 2700 For more information on KUnit and unit tests in general please refer 2701 to the KUnit documentation in Documentation/dev-tools/kunit/. 2702 2703 If unsure, say N. 2704 2705config HASHTABLE_KUNIT_TEST 2706 tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS 2707 depends on KUNIT 2708 default KUNIT_ALL_TESTS 2709 help 2710 This builds the hashtable KUnit test suite. 2711 It tests the basic functionality of the API defined in 2712 include/linux/hashtable.h. For more information on KUnit and 2713 unit tests in general please refer to the KUnit documentation 2714 in Documentation/dev-tools/kunit/. 2715 2716 If unsure, say N. 2717 2718config LINEAR_RANGES_TEST 2719 tristate "KUnit test for linear_ranges" 2720 depends on KUNIT 2721 select LINEAR_RANGES 2722 help 2723 This builds the linear_ranges unit test, which runs on boot. 2724 Tests the linear_ranges logic correctness. 2725 For more information on KUnit and unit tests in general please refer 2726 to the KUnit documentation in Documentation/dev-tools/kunit/. 2727 2728 If unsure, say N. 2729 2730config CMDLINE_KUNIT_TEST 2731 tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS 2732 depends on KUNIT 2733 default KUNIT_ALL_TESTS 2734 help 2735 This builds the cmdline API unit test. 2736 Tests the logic of API provided by cmdline.c. 2737 For more information on KUnit and unit tests in general please refer 2738 to the KUnit documentation in Documentation/dev-tools/kunit/. 2739 2740 If unsure, say N. 2741 2742config BITS_TEST 2743 tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS 2744 depends on KUNIT 2745 default KUNIT_ALL_TESTS 2746 help 2747 This builds the bits unit test. 2748 Tests the logic of macros defined in bits.h. 2749 For more information on KUnit and unit tests in general please refer 2750 to the KUnit documentation in Documentation/dev-tools/kunit/. 2751 2752 If unsure, say N. 2753 2754config SLUB_KUNIT_TEST 2755 tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS 2756 depends on SLUB_DEBUG && KUNIT 2757 default KUNIT_ALL_TESTS 2758 help 2759 This builds SLUB allocator unit test. 2760 Tests SLUB cache debugging functionality. 2761 For more information on KUnit and unit tests in general please refer 2762 to the KUnit documentation in Documentation/dev-tools/kunit/. 2763 2764 If unsure, say N. 2765 2766config RATIONAL_KUNIT_TEST 2767 tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS 2768 depends on KUNIT && RATIONAL 2769 default KUNIT_ALL_TESTS 2770 help 2771 This builds the rational math unit test. 2772 For more information on KUnit and unit tests in general please refer 2773 to the KUnit documentation in Documentation/dev-tools/kunit/. 2774 2775 If unsure, say N. 2776 2777config MEMCPY_KUNIT_TEST 2778 tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS 2779 depends on KUNIT 2780 default KUNIT_ALL_TESTS 2781 help 2782 Builds unit tests for memcpy(), memmove(), and memset() functions. 2783 For more information on KUnit and unit tests in general please refer 2784 to the KUnit documentation in Documentation/dev-tools/kunit/. 2785 2786 If unsure, say N. 2787 2788config IS_SIGNED_TYPE_KUNIT_TEST 2789 tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS 2790 depends on KUNIT 2791 default KUNIT_ALL_TESTS 2792 help 2793 Builds unit tests for the is_signed_type() macro. 2794 2795 For more information on KUnit and unit tests in general please refer 2796 to the KUnit documentation in Documentation/dev-tools/kunit/. 2797 2798 If unsure, say N. 2799 2800config OVERFLOW_KUNIT_TEST 2801 tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS 2802 depends on KUNIT 2803 default KUNIT_ALL_TESTS 2804 help 2805 Builds unit tests for the check_*_overflow(), size_*(), allocation, and 2806 related functions. 2807 2808 For more information on KUnit and unit tests in general please refer 2809 to the KUnit documentation in Documentation/dev-tools/kunit/. 2810 2811 If unsure, say N. 2812 2813config STACKINIT_KUNIT_TEST 2814 tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS 2815 depends on KUNIT 2816 default KUNIT_ALL_TESTS 2817 help 2818 Test if the kernel is zero-initializing stack variables and 2819 padding. Coverage is controlled by compiler flags, 2820 CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO, 2821 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2822 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2823 2824config FORTIFY_KUNIT_TEST 2825 tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS 2826 depends on KUNIT 2827 default KUNIT_ALL_TESTS 2828 help 2829 Builds unit tests for checking internals of FORTIFY_SOURCE as used 2830 by the str*() and mem*() family of functions. For testing runtime 2831 traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests. 2832 2833config HW_BREAKPOINT_KUNIT_TEST 2834 bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS 2835 depends on HAVE_HW_BREAKPOINT 2836 depends on KUNIT=y 2837 default KUNIT_ALL_TESTS 2838 help 2839 Tests for hw_breakpoint constraints accounting. 2840 2841 If unsure, say N. 2842 2843config SIPHASH_KUNIT_TEST 2844 tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS 2845 depends on KUNIT 2846 default KUNIT_ALL_TESTS 2847 help 2848 Enable this option to test the kernel's siphash (<linux/siphash.h>) hash 2849 functions on boot (or module load). 2850 2851 This is intended to help people writing architecture-specific 2852 optimized versions. If unsure, say N. 2853 2854config USERCOPY_KUNIT_TEST 2855 tristate "KUnit Test for user/kernel boundary protections" 2856 depends on KUNIT 2857 default KUNIT_ALL_TESTS 2858 help 2859 This builds the "usercopy_kunit" module that runs sanity checks 2860 on the copy_to/from_user infrastructure, making sure basic 2861 user/kernel boundary testing is working. 2862 2863config TEST_UDELAY 2864 tristate "udelay test driver" 2865 help 2866 This builds the "udelay_test" module that helps to make sure 2867 that udelay() is working properly. 2868 2869 If unsure, say N. 2870 2871config TEST_STATIC_KEYS 2872 tristate "Test static keys" 2873 depends on m 2874 help 2875 Test the static key interfaces. 2876 2877 If unsure, say N. 2878 2879config TEST_DYNAMIC_DEBUG 2880 tristate "Test DYNAMIC_DEBUG" 2881 depends on DYNAMIC_DEBUG 2882 help 2883 This module registers a tracer callback to count enabled 2884 pr_debugs in a 'do_debugging' function, then alters their 2885 enablements, calls the function, and compares counts. 2886 2887 If unsure, say N. 2888 2889config TEST_KMOD 2890 tristate "kmod stress tester" 2891 depends on m 2892 depends on NETDEVICES && NET_CORE && INET # for TUN 2893 depends on BLOCK 2894 depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS 2895 select TEST_LKM 2896 select XFS_FS 2897 select TUN 2898 select BTRFS_FS 2899 help 2900 Test the kernel's module loading mechanism: kmod. kmod implements 2901 support to load modules using the Linux kernel's usermode helper. 2902 This test provides a series of tests against kmod. 2903 2904 Although technically you can either build test_kmod as a module or 2905 into the kernel we disallow building it into the kernel since 2906 it stress tests request_module() and this will very likely cause 2907 some issues by taking over precious threads available from other 2908 module load requests, ultimately this could be fatal. 2909 2910 To run tests run: 2911 2912 tools/testing/selftests/kmod/kmod.sh --help 2913 2914 If unsure, say N. 2915 2916config TEST_DEBUG_VIRTUAL 2917 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 2918 depends on DEBUG_VIRTUAL 2919 help 2920 Test the kernel's ability to detect incorrect calls to 2921 virt_to_phys() done against the non-linear part of the 2922 kernel's virtual address map. 2923 2924 If unsure, say N. 2925 2926config TEST_MEMCAT_P 2927 tristate "Test memcat_p() helper function" 2928 help 2929 Test the memcat_p() helper for correctly merging two 2930 pointer arrays together. 2931 2932 If unsure, say N. 2933 2934config TEST_OBJAGG 2935 tristate "Perform selftest on object aggreration manager" 2936 default n 2937 depends on OBJAGG 2938 help 2939 Enable this option to test object aggregation manager on boot 2940 (or module load). 2941 2942config TEST_MEMINIT 2943 tristate "Test heap/page initialization" 2944 help 2945 Test if the kernel is zero-initializing heap and page allocations. 2946 This can be useful to test init_on_alloc and init_on_free features. 2947 2948 If unsure, say N. 2949 2950config TEST_HMM 2951 tristate "Test HMM (Heterogeneous Memory Management)" 2952 depends on TRANSPARENT_HUGEPAGE 2953 depends on DEVICE_PRIVATE 2954 select HMM_MIRROR 2955 select MMU_NOTIFIER 2956 help 2957 This is a pseudo device driver solely for testing HMM. 2958 Say M here if you want to build the HMM test module. 2959 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests. 2960 2961 If unsure, say N. 2962 2963config TEST_FREE_PAGES 2964 tristate "Test freeing pages" 2965 help 2966 Test that a memory leak does not occur due to a race between 2967 freeing a block of pages and a speculative page reference. 2968 Loading this module is safe if your kernel has the bug fixed. 2969 If the bug is not fixed, it will leak gigabytes of memory and 2970 probably OOM your system. 2971 2972config TEST_FPU 2973 tristate "Test floating point operations in kernel space" 2974 depends on ARCH_HAS_KERNEL_FPU_SUPPORT && !KCOV_INSTRUMENT_ALL 2975 help 2976 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu 2977 which will trigger a sequence of floating point operations. This is used 2978 for self-testing floating point control register setting in 2979 kernel_fpu_begin(). 2980 2981 If unsure, say N. 2982 2983config TEST_CLOCKSOURCE_WATCHDOG 2984 tristate "Test clocksource watchdog in kernel space" 2985 depends on CLOCKSOURCE_WATCHDOG 2986 help 2987 Enable this option to create a kernel module that will trigger 2988 a test of the clocksource watchdog. This module may be loaded 2989 via modprobe or insmod in which case it will run upon being 2990 loaded, or it may be built in, in which case it will run 2991 shortly after boot. 2992 2993 If unsure, say N. 2994 2995config TEST_OBJPOOL 2996 tristate "Test module for correctness and stress of objpool" 2997 default n 2998 depends on m && DEBUG_KERNEL 2999 help 3000 This builds the "test_objpool" module that should be used for 3001 correctness verification and concurrent testings of objects 3002 allocation and reclamation. 3003 3004 If unsure, say N. 3005 3006endif # RUNTIME_TESTING_MENU 3007 3008config ARCH_USE_MEMTEST 3009 bool 3010 help 3011 An architecture should select this when it uses early_memtest() 3012 during boot process. 3013 3014config MEMTEST 3015 bool "Memtest" 3016 depends on ARCH_USE_MEMTEST 3017 help 3018 This option adds a kernel parameter 'memtest', which allows memtest 3019 to be set and executed. 3020 memtest=0, mean disabled; -- default 3021 memtest=1, mean do 1 test pattern; 3022 ... 3023 memtest=17, mean do 17 test patterns. 3024 If you are unsure how to answer this question, answer N. 3025 3026 3027 3028config HYPERV_TESTING 3029 bool "Microsoft Hyper-V driver testing" 3030 default n 3031 depends on HYPERV && DEBUG_FS 3032 help 3033 Select this option to enable Hyper-V vmbus testing. 3034 3035endmenu # "Kernel Testing and Coverage" 3036 3037menu "Rust hacking" 3038 3039config RUST_DEBUG_ASSERTIONS 3040 bool "Debug assertions" 3041 depends on RUST 3042 help 3043 Enables rustc's `-Cdebug-assertions` codegen option. 3044 3045 This flag lets you turn `cfg(debug_assertions)` conditional 3046 compilation on or off. This can be used to enable extra debugging 3047 code in development but not in production. For example, it controls 3048 the behavior of the standard library's `debug_assert!` macro. 3049 3050 Note that this will apply to all Rust code, including `core`. 3051 3052 If unsure, say N. 3053 3054config RUST_OVERFLOW_CHECKS 3055 bool "Overflow checks" 3056 default y 3057 depends on RUST 3058 help 3059 Enables rustc's `-Coverflow-checks` codegen option. 3060 3061 This flag allows you to control the behavior of runtime integer 3062 overflow. When overflow-checks are enabled, a Rust panic will occur 3063 on overflow. 3064 3065 Note that this will apply to all Rust code, including `core`. 3066 3067 If unsure, say Y. 3068 3069config RUST_BUILD_ASSERT_ALLOW 3070 bool "Allow unoptimized build-time assertions" 3071 depends on RUST 3072 help 3073 Controls how `build_error!` and `build_assert!` are handled during the build. 3074 3075 If calls to them exist in the binary, it may indicate a violated invariant 3076 or that the optimizer failed to verify the invariant during compilation. 3077 3078 This should not happen, thus by default the build is aborted. However, 3079 as an escape hatch, you can choose Y here to ignore them during build 3080 and let the check be carried at runtime (with `panic!` being called if 3081 the check fails). 3082 3083 If unsure, say N. 3084 3085config RUST_KERNEL_DOCTESTS 3086 bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS 3087 depends on RUST && KUNIT=y 3088 default KUNIT_ALL_TESTS 3089 help 3090 This builds the documentation tests of the `kernel` crate 3091 as KUnit tests. 3092 3093 For more information on KUnit and unit tests in general, 3094 please refer to the KUnit documentation in Documentation/dev-tools/kunit/. 3095 3096 If unsure, say N. 3097 3098endmenu # "Rust" 3099 3100endmenu # Kernel hacking 3101 3102config INT_POW_TEST 3103 tristate "Integer exponentiation (int_pow) test" if !KUNIT_ALL_TESTS 3104 depends on KUNIT 3105 default KUNIT_ALL_TESTS 3106 help 3107 This option enables the KUnit test suite for the int_pow function, 3108 which performs integer exponentiation. The test suite is designed to 3109 verify that the implementation of int_pow correctly computes the power 3110 of a given base raised to a given exponent. 3111 3112 Enabling this option will include tests that check various scenarios 3113 and edge cases to ensure the accuracy and reliability of the exponentiation 3114 function. 3115 3116 If unsure, say N 3117