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 1413 depends on PROVE_LOCKING 1414 default y 1415 help 1416 Enable the raw_spinlock vs. spinlock nesting checks which ensure 1417 that the lock nesting rules for PREEMPT_RT enabled kernels are 1418 not violated. 1419 1420config LOCK_STAT 1421 bool "Lock usage statistics" 1422 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1423 select LOCKDEP 1424 select DEBUG_SPINLOCK 1425 select DEBUG_MUTEXES if !PREEMPT_RT 1426 select DEBUG_RT_MUTEXES if RT_MUTEXES 1427 select DEBUG_LOCK_ALLOC 1428 default n 1429 help 1430 This feature enables tracking lock contention points 1431 1432 For more details, see Documentation/locking/lockstat.rst 1433 1434 This also enables lock events required by "perf lock", 1435 subcommand of perf. 1436 If you want to use "perf lock", you also need to turn on 1437 CONFIG_EVENT_TRACING. 1438 1439 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1440 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1441 1442config DEBUG_RT_MUTEXES 1443 bool "RT Mutex debugging, deadlock detection" 1444 depends on DEBUG_KERNEL && RT_MUTEXES 1445 help 1446 This allows rt mutex semantics violations and rt mutex related 1447 deadlocks (lockups) to be detected and reported automatically. 1448 1449config DEBUG_SPINLOCK 1450 bool "Spinlock and rw-lock debugging: basic checks" 1451 depends on DEBUG_KERNEL 1452 select UNINLINE_SPIN_UNLOCK 1453 help 1454 Say Y here and build SMP to catch missing spinlock initialization 1455 and certain other kinds of spinlock errors commonly made. This is 1456 best used in conjunction with the NMI watchdog so that spinlock 1457 deadlocks are also debuggable. 1458 1459config DEBUG_MUTEXES 1460 bool "Mutex debugging: basic checks" 1461 depends on DEBUG_KERNEL && !PREEMPT_RT 1462 help 1463 This feature allows mutex semantics violations to be detected and 1464 reported. 1465 1466config DEBUG_WW_MUTEX_SLOWPATH 1467 bool "Wait/wound mutex debugging: Slowpath testing" 1468 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1469 select DEBUG_LOCK_ALLOC 1470 select DEBUG_SPINLOCK 1471 select DEBUG_MUTEXES if !PREEMPT_RT 1472 select DEBUG_RT_MUTEXES if PREEMPT_RT 1473 help 1474 This feature enables slowpath testing for w/w mutex users by 1475 injecting additional -EDEADLK wound/backoff cases. Together with 1476 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1477 will test all possible w/w mutex interface abuse with the 1478 exception of simply not acquiring all the required locks. 1479 Note that this feature can introduce significant overhead, so 1480 it really should not be enabled in a production or distro kernel, 1481 even a debug kernel. If you are a driver writer, enable it. If 1482 you are a distro, do not. 1483 1484config DEBUG_RWSEMS 1485 bool "RW Semaphore debugging: basic checks" 1486 depends on DEBUG_KERNEL && !PREEMPT_RT 1487 help 1488 This debugging feature allows mismatched rw semaphore locks 1489 and unlocks to be detected and reported. 1490 1491config DEBUG_LOCK_ALLOC 1492 bool "Lock debugging: detect incorrect freeing of live locks" 1493 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1494 select DEBUG_SPINLOCK 1495 select DEBUG_MUTEXES if !PREEMPT_RT 1496 select DEBUG_RT_MUTEXES if RT_MUTEXES 1497 select LOCKDEP 1498 help 1499 This feature will check whether any held lock (spinlock, rwlock, 1500 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1501 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1502 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1503 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1504 held during task exit. 1505 1506config LOCKDEP 1507 bool 1508 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1509 select STACKTRACE 1510 select KALLSYMS 1511 select KALLSYMS_ALL 1512 1513config LOCKDEP_SMALL 1514 bool 1515 1516config LOCKDEP_BITS 1517 int "Bitsize for MAX_LOCKDEP_ENTRIES" 1518 depends on LOCKDEP && !LOCKDEP_SMALL 1519 range 10 30 1520 default 15 1521 help 1522 Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message. 1523 1524config LOCKDEP_CHAINS_BITS 1525 int "Bitsize for MAX_LOCKDEP_CHAINS" 1526 depends on LOCKDEP && !LOCKDEP_SMALL 1527 range 10 21 1528 default 16 1529 help 1530 Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message. 1531 1532config LOCKDEP_STACK_TRACE_BITS 1533 int "Bitsize for MAX_STACK_TRACE_ENTRIES" 1534 depends on LOCKDEP && !LOCKDEP_SMALL 1535 range 10 30 1536 default 19 1537 help 1538 Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message. 1539 1540config LOCKDEP_STACK_TRACE_HASH_BITS 1541 int "Bitsize for STACK_TRACE_HASH_SIZE" 1542 depends on LOCKDEP && !LOCKDEP_SMALL 1543 range 10 30 1544 default 14 1545 help 1546 Try increasing this value if you need large STACK_TRACE_HASH_SIZE. 1547 1548config LOCKDEP_CIRCULAR_QUEUE_BITS 1549 int "Bitsize for elements in circular_queue struct" 1550 depends on LOCKDEP 1551 range 10 30 1552 default 12 1553 help 1554 Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure. 1555 1556config DEBUG_LOCKDEP 1557 bool "Lock dependency engine debugging" 1558 depends on DEBUG_KERNEL && LOCKDEP 1559 select DEBUG_IRQFLAGS 1560 help 1561 If you say Y here, the lock dependency engine will do 1562 additional runtime checks to debug itself, at the price 1563 of more runtime overhead. 1564 1565config DEBUG_ATOMIC_SLEEP 1566 bool "Sleep inside atomic section checking" 1567 select PREEMPT_COUNT 1568 depends on DEBUG_KERNEL 1569 depends on !ARCH_NO_PREEMPT 1570 help 1571 If you say Y here, various routines which may sleep will become very 1572 noisy if they are called inside atomic sections: when a spinlock is 1573 held, inside an rcu read side critical section, inside preempt disabled 1574 sections, inside an interrupt, etc... 1575 1576config DEBUG_LOCKING_API_SELFTESTS 1577 bool "Locking API boot-time self-tests" 1578 depends on DEBUG_KERNEL 1579 help 1580 Say Y here if you want the kernel to run a short self-test during 1581 bootup. The self-test checks whether common types of locking bugs 1582 are detected by debugging mechanisms or not. (if you disable 1583 lock debugging then those bugs won't be detected of course.) 1584 The following locking APIs are covered: spinlocks, rwlocks, 1585 mutexes and rwsems. 1586 1587config LOCK_TORTURE_TEST 1588 tristate "torture tests for locking" 1589 depends on DEBUG_KERNEL 1590 select TORTURE_TEST 1591 help 1592 This option provides a kernel module that runs torture tests 1593 on kernel locking primitives. The kernel module may be built 1594 after the fact on the running kernel to be tested, if desired. 1595 1596 Say Y here if you want kernel locking-primitive torture tests 1597 to be built into the kernel. 1598 Say M if you want these torture tests to build as a module. 1599 Say N if you are unsure. 1600 1601config WW_MUTEX_SELFTEST 1602 tristate "Wait/wound mutex selftests" 1603 help 1604 This option provides a kernel module that runs tests on the 1605 on the struct ww_mutex locking API. 1606 1607 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1608 with this test harness. 1609 1610 Say M if you want these self tests to build as a module. 1611 Say N if you are unsure. 1612 1613config SCF_TORTURE_TEST 1614 tristate "torture tests for smp_call_function*()" 1615 depends on DEBUG_KERNEL 1616 select TORTURE_TEST 1617 help 1618 This option provides a kernel module that runs torture tests 1619 on the smp_call_function() family of primitives. The kernel 1620 module may be built after the fact on the running kernel to 1621 be tested, if desired. 1622 1623config CSD_LOCK_WAIT_DEBUG 1624 bool "Debugging for csd_lock_wait(), called from smp_call_function*()" 1625 depends on DEBUG_KERNEL 1626 depends on SMP 1627 depends on 64BIT 1628 default n 1629 help 1630 This option enables debug prints when CPUs are slow to respond 1631 to the smp_call_function*() IPI wrappers. These debug prints 1632 include the IPI handler function currently executing (if any) 1633 and relevant stack traces. 1634 1635config CSD_LOCK_WAIT_DEBUG_DEFAULT 1636 bool "Default csd_lock_wait() debugging on at boot time" 1637 depends on CSD_LOCK_WAIT_DEBUG 1638 depends on 64BIT 1639 default n 1640 help 1641 This option causes the csdlock_debug= kernel boot parameter to 1642 default to 1 (basic debugging) instead of 0 (no debugging). 1643 1644endmenu # lock debugging 1645 1646config TRACE_IRQFLAGS 1647 depends on TRACE_IRQFLAGS_SUPPORT 1648 bool 1649 help 1650 Enables hooks to interrupt enabling and disabling for 1651 either tracing or lock debugging. 1652 1653config TRACE_IRQFLAGS_NMI 1654 def_bool y 1655 depends on TRACE_IRQFLAGS 1656 depends on TRACE_IRQFLAGS_NMI_SUPPORT 1657 1658config NMI_CHECK_CPU 1659 bool "Debugging for CPUs failing to respond to backtrace requests" 1660 depends on DEBUG_KERNEL 1661 depends on X86 1662 default n 1663 help 1664 Enables debug prints when a CPU fails to respond to a given 1665 backtrace NMI. These prints provide some reasons why a CPU 1666 might legitimately be failing to respond, for example, if it 1667 is offline of if ignore_nmis is set. 1668 1669config DEBUG_IRQFLAGS 1670 bool "Debug IRQ flag manipulation" 1671 help 1672 Enables checks for potentially unsafe enabling or disabling of 1673 interrupts, such as calling raw_local_irq_restore() when interrupts 1674 are enabled. 1675 1676config STACKTRACE 1677 bool "Stack backtrace support" 1678 depends on STACKTRACE_SUPPORT 1679 help 1680 This option causes the kernel to create a /proc/pid/stack for 1681 every process, showing its current stack trace. 1682 It is also used by various kernel debugging features that require 1683 stack trace generation. 1684 1685config WARN_ALL_UNSEEDED_RANDOM 1686 bool "Warn for all uses of unseeded randomness" 1687 default n 1688 help 1689 Some parts of the kernel contain bugs relating to their use of 1690 cryptographically secure random numbers before it's actually possible 1691 to generate those numbers securely. This setting ensures that these 1692 flaws don't go unnoticed, by enabling a message, should this ever 1693 occur. This will allow people with obscure setups to know when things 1694 are going wrong, so that they might contact developers about fixing 1695 it. 1696 1697 Unfortunately, on some models of some architectures getting 1698 a fully seeded CRNG is extremely difficult, and so this can 1699 result in dmesg getting spammed for a surprisingly long 1700 time. This is really bad from a security perspective, and 1701 so architecture maintainers really need to do what they can 1702 to get the CRNG seeded sooner after the system is booted. 1703 However, since users cannot do anything actionable to 1704 address this, by default this option is disabled. 1705 1706 Say Y here if you want to receive warnings for all uses of 1707 unseeded randomness. This will be of use primarily for 1708 those developers interested in improving the security of 1709 Linux kernels running on their architecture (or 1710 subarchitecture). 1711 1712config DEBUG_KOBJECT 1713 bool "kobject debugging" 1714 depends on DEBUG_KERNEL 1715 help 1716 If you say Y here, some extra kobject debugging messages will be sent 1717 to the syslog. 1718 1719config DEBUG_KOBJECT_RELEASE 1720 bool "kobject release debugging" 1721 depends on DEBUG_OBJECTS_TIMERS 1722 help 1723 kobjects are reference counted objects. This means that their 1724 last reference count put is not predictable, and the kobject can 1725 live on past the point at which a driver decides to drop its 1726 initial reference to the kobject gained on allocation. An 1727 example of this would be a struct device which has just been 1728 unregistered. 1729 1730 However, some buggy drivers assume that after such an operation, 1731 the memory backing the kobject can be immediately freed. This 1732 goes completely against the principles of a refcounted object. 1733 1734 If you say Y here, the kernel will delay the release of kobjects 1735 on the last reference count to improve the visibility of this 1736 kind of kobject release bug. 1737 1738config HAVE_DEBUG_BUGVERBOSE 1739 bool 1740 1741menu "Debug kernel data structures" 1742 1743config DEBUG_LIST 1744 bool "Debug linked list manipulation" 1745 depends on DEBUG_KERNEL 1746 select LIST_HARDENED 1747 help 1748 Enable this to turn on extended checks in the linked-list walking 1749 routines. 1750 1751 This option trades better quality error reports for performance, and 1752 is more suitable for kernel debugging. If you care about performance, 1753 you should only enable CONFIG_LIST_HARDENED instead. 1754 1755 If unsure, say N. 1756 1757config DEBUG_PLIST 1758 bool "Debug priority linked list manipulation" 1759 depends on DEBUG_KERNEL 1760 help 1761 Enable this to turn on extended checks in the priority-ordered 1762 linked-list (plist) walking routines. This checks the entire 1763 list multiple times during each manipulation. 1764 1765 If unsure, say N. 1766 1767config DEBUG_SG 1768 bool "Debug SG table operations" 1769 depends on DEBUG_KERNEL 1770 help 1771 Enable this to turn on checks on scatter-gather tables. This can 1772 help find problems with drivers that do not properly initialize 1773 their sg tables. 1774 1775 If unsure, say N. 1776 1777config DEBUG_NOTIFIERS 1778 bool "Debug notifier call chains" 1779 depends on DEBUG_KERNEL 1780 help 1781 Enable this to turn on sanity checking for notifier call chains. 1782 This is most useful for kernel developers to make sure that 1783 modules properly unregister themselves from notifier chains. 1784 This is a relatively cheap check but if you care about maximum 1785 performance, say N. 1786 1787config DEBUG_CLOSURES 1788 bool "Debug closures (bcache async widgits)" 1789 depends on CLOSURES 1790 select DEBUG_FS 1791 help 1792 Keeps all active closures in a linked list and provides a debugfs 1793 interface to list them, which makes it possible to see asynchronous 1794 operations that get stuck. 1795 1796config DEBUG_MAPLE_TREE 1797 bool "Debug maple trees" 1798 depends on DEBUG_KERNEL 1799 help 1800 Enable maple tree debugging information and extra validations. 1801 1802 If unsure, say N. 1803 1804endmenu 1805 1806source "kernel/rcu/Kconfig.debug" 1807 1808config DEBUG_WQ_FORCE_RR_CPU 1809 bool "Force round-robin CPU selection for unbound work items" 1810 depends on DEBUG_KERNEL 1811 default n 1812 help 1813 Workqueue used to implicitly guarantee that work items queued 1814 without explicit CPU specified are put on the local CPU. This 1815 guarantee is no longer true and while local CPU is still 1816 preferred work items may be put on foreign CPUs. Kernel 1817 parameter "workqueue.debug_force_rr_cpu" is added to force 1818 round-robin CPU selection to flush out usages which depend on the 1819 now broken guarantee. This config option enables the debug 1820 feature by default. When enabled, memory and cache locality will 1821 be impacted. 1822 1823config CPU_HOTPLUG_STATE_CONTROL 1824 bool "Enable CPU hotplug state control" 1825 depends on DEBUG_KERNEL 1826 depends on HOTPLUG_CPU 1827 default n 1828 help 1829 Allows to write steps between "offline" and "online" to the CPUs 1830 sysfs target file so states can be stepped granular. This is a debug 1831 option for now as the hotplug machinery cannot be stopped and 1832 restarted at arbitrary points yet. 1833 1834 Say N if your are unsure. 1835 1836config LATENCYTOP 1837 bool "Latency measuring infrastructure" 1838 depends on DEBUG_KERNEL 1839 depends on STACKTRACE_SUPPORT 1840 depends on PROC_FS 1841 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 1842 select KALLSYMS 1843 select KALLSYMS_ALL 1844 select STACKTRACE 1845 select SCHEDSTATS 1846 help 1847 Enable this option if you want to use the LatencyTOP tool 1848 to find out which userspace is blocking on what kernel operations. 1849 1850config DEBUG_CGROUP_REF 1851 bool "Disable inlining of cgroup css reference count functions" 1852 depends on DEBUG_KERNEL 1853 depends on CGROUPS 1854 depends on KPROBES 1855 default n 1856 help 1857 Force cgroup css reference count functions to not be inlined so 1858 that they can be kprobed for debugging. 1859 1860source "kernel/trace/Kconfig" 1861 1862config PROVIDE_OHCI1394_DMA_INIT 1863 bool "Remote debugging over FireWire early on boot" 1864 depends on PCI && X86 1865 help 1866 If you want to debug problems which hang or crash the kernel early 1867 on boot and the crashing machine has a FireWire port, you can use 1868 this feature to remotely access the memory of the crashed machine 1869 over FireWire. This employs remote DMA as part of the OHCI1394 1870 specification which is now the standard for FireWire controllers. 1871 1872 With remote DMA, you can monitor the printk buffer remotely using 1873 firescope and access all memory below 4GB using fireproxy from gdb. 1874 Even controlling a kernel debugger is possible using remote DMA. 1875 1876 Usage: 1877 1878 If ohci1394_dma=early is used as boot parameter, it will initialize 1879 all OHCI1394 controllers which are found in the PCI config space. 1880 1881 As all changes to the FireWire bus such as enabling and disabling 1882 devices cause a bus reset and thereby disable remote DMA for all 1883 devices, be sure to have the cable plugged and FireWire enabled on 1884 the debugging host before booting the debug target for debugging. 1885 1886 This code (~1k) is freed after boot. By then, the firewire stack 1887 in charge of the OHCI-1394 controllers should be used instead. 1888 1889 See Documentation/core-api/debugging-via-ohci1394.rst for more information. 1890 1891source "samples/Kconfig" 1892 1893config ARCH_HAS_DEVMEM_IS_ALLOWED 1894 bool 1895 1896config STRICT_DEVMEM 1897 bool "Filter access to /dev/mem" 1898 depends on MMU && DEVMEM 1899 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED 1900 default y if PPC || X86 || ARM64 1901 help 1902 If this option is disabled, you allow userspace (root) access to all 1903 of memory, including kernel and userspace memory. Accidental 1904 access to this is obviously disastrous, but specific access can 1905 be used by people debugging the kernel. Note that with PAT support 1906 enabled, even in this case there are restrictions on /dev/mem 1907 use due to the cache aliasing requirements. 1908 1909 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 1910 file only allows userspace access to PCI space and the BIOS code and 1911 data regions. This is sufficient for dosemu and X and all common 1912 users of /dev/mem. 1913 1914 If in doubt, say Y. 1915 1916config IO_STRICT_DEVMEM 1917 bool "Filter I/O access to /dev/mem" 1918 depends on STRICT_DEVMEM 1919 help 1920 If this option is disabled, you allow userspace (root) access to all 1921 io-memory regardless of whether a driver is actively using that 1922 range. Accidental access to this is obviously disastrous, but 1923 specific access can be used by people debugging kernel drivers. 1924 1925 If this option is switched on, the /dev/mem file only allows 1926 userspace access to *idle* io-memory ranges (see /proc/iomem) This 1927 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 1928 if the driver using a given range cannot be disabled. 1929 1930 If in doubt, say Y. 1931 1932menu "$(SRCARCH) Debugging" 1933 1934source "arch/$(SRCARCH)/Kconfig.debug" 1935 1936endmenu 1937 1938menu "Kernel Testing and Coverage" 1939 1940source "lib/kunit/Kconfig" 1941 1942config NOTIFIER_ERROR_INJECTION 1943 tristate "Notifier error injection" 1944 depends on DEBUG_KERNEL 1945 select DEBUG_FS 1946 help 1947 This option provides the ability to inject artificial errors to 1948 specified notifier chain callbacks. It is useful to test the error 1949 handling of notifier call chain failures. 1950 1951 Say N if unsure. 1952 1953config PM_NOTIFIER_ERROR_INJECT 1954 tristate "PM notifier error injection module" 1955 depends on PM && NOTIFIER_ERROR_INJECTION 1956 default m if PM_DEBUG 1957 help 1958 This option provides the ability to inject artificial errors to 1959 PM notifier chain callbacks. It is controlled through debugfs 1960 interface /sys/kernel/debug/notifier-error-inject/pm 1961 1962 If the notifier call chain should be failed with some events 1963 notified, write the error code to "actions/<notifier event>/error". 1964 1965 Example: Inject PM suspend error (-12 = -ENOMEM) 1966 1967 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1968 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1969 # echo mem > /sys/power/state 1970 bash: echo: write error: Cannot allocate memory 1971 1972 To compile this code as a module, choose M here: the module will 1973 be called pm-notifier-error-inject. 1974 1975 If unsure, say N. 1976 1977config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1978 tristate "OF reconfig notifier error injection module" 1979 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1980 help 1981 This option provides the ability to inject artificial errors to 1982 OF reconfig notifier chain callbacks. It is controlled 1983 through debugfs interface under 1984 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1985 1986 If the notifier call chain should be failed with some events 1987 notified, write the error code to "actions/<notifier event>/error". 1988 1989 To compile this code as a module, choose M here: the module will 1990 be called of-reconfig-notifier-error-inject. 1991 1992 If unsure, say N. 1993 1994config NETDEV_NOTIFIER_ERROR_INJECT 1995 tristate "Netdev notifier error injection module" 1996 depends on NET && NOTIFIER_ERROR_INJECTION 1997 help 1998 This option provides the ability to inject artificial errors to 1999 netdevice notifier chain callbacks. It is controlled through debugfs 2000 interface /sys/kernel/debug/notifier-error-inject/netdev 2001 2002 If the notifier call chain should be failed with some events 2003 notified, write the error code to "actions/<notifier event>/error". 2004 2005 Example: Inject netdevice mtu change error (-22 = -EINVAL) 2006 2007 # cd /sys/kernel/debug/notifier-error-inject/netdev 2008 # echo -22 > actions/NETDEV_CHANGEMTU/error 2009 # ip link set eth0 mtu 1024 2010 RTNETLINK answers: Invalid argument 2011 2012 To compile this code as a module, choose M here: the module will 2013 be called netdev-notifier-error-inject. 2014 2015 If unsure, say N. 2016 2017config FUNCTION_ERROR_INJECTION 2018 bool "Fault-injections of functions" 2019 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 2020 help 2021 Add fault injections into various functions that are annotated with 2022 ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return 2023 value of these functions. This is useful to test error paths of code. 2024 2025 If unsure, say N 2026 2027config FAULT_INJECTION 2028 bool "Fault-injection framework" 2029 depends on DEBUG_KERNEL 2030 help 2031 Provide fault-injection framework. 2032 For more details, see Documentation/fault-injection/. 2033 2034config FAILSLAB 2035 bool "Fault-injection capability for kmalloc" 2036 depends on FAULT_INJECTION 2037 help 2038 Provide fault-injection capability for kmalloc. 2039 2040config FAIL_PAGE_ALLOC 2041 bool "Fault-injection capability for alloc_pages()" 2042 depends on FAULT_INJECTION 2043 help 2044 Provide fault-injection capability for alloc_pages(). 2045 2046config FAULT_INJECTION_USERCOPY 2047 bool "Fault injection capability for usercopy functions" 2048 depends on FAULT_INJECTION 2049 help 2050 Provides fault-injection capability to inject failures 2051 in usercopy functions (copy_from_user(), get_user(), ...). 2052 2053config FAIL_MAKE_REQUEST 2054 bool "Fault-injection capability for disk IO" 2055 depends on FAULT_INJECTION && BLOCK 2056 help 2057 Provide fault-injection capability for disk IO. 2058 2059config FAIL_IO_TIMEOUT 2060 bool "Fault-injection capability for faking disk interrupts" 2061 depends on FAULT_INJECTION && BLOCK 2062 help 2063 Provide fault-injection capability on end IO handling. This 2064 will make the block layer "forget" an interrupt as configured, 2065 thus exercising the error handling. 2066 2067 Only works with drivers that use the generic timeout handling, 2068 for others it won't do anything. 2069 2070config FAIL_FUTEX 2071 bool "Fault-injection capability for futexes" 2072 select DEBUG_FS 2073 depends on FAULT_INJECTION && FUTEX 2074 help 2075 Provide fault-injection capability for futexes. 2076 2077config FAULT_INJECTION_DEBUG_FS 2078 bool "Debugfs entries for fault-injection capabilities" 2079 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 2080 help 2081 Enable configuration of fault-injection capabilities via debugfs. 2082 2083config FAIL_FUNCTION 2084 bool "Fault-injection capability for functions" 2085 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 2086 help 2087 Provide function-based fault-injection capability. 2088 This will allow you to override a specific function with a return 2089 with given return value. As a result, function caller will see 2090 an error value and have to handle it. This is useful to test the 2091 error handling in various subsystems. 2092 2093config FAIL_MMC_REQUEST 2094 bool "Fault-injection capability for MMC IO" 2095 depends on FAULT_INJECTION_DEBUG_FS && MMC 2096 help 2097 Provide fault-injection capability for MMC IO. 2098 This will make the mmc core return data errors. This is 2099 useful to test the error handling in the mmc block device 2100 and to test how the mmc host driver handles retries from 2101 the block device. 2102 2103config FAIL_SUNRPC 2104 bool "Fault-injection capability for SunRPC" 2105 depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG 2106 help 2107 Provide fault-injection capability for SunRPC and 2108 its consumers. 2109 2110config FAULT_INJECTION_CONFIGFS 2111 bool "Configfs interface for fault-injection capabilities" 2112 depends on FAULT_INJECTION 2113 select CONFIGFS_FS 2114 help 2115 This option allows configfs-based drivers to dynamically configure 2116 fault-injection via configfs. Each parameter for driver-specific 2117 fault-injection can be made visible as a configfs attribute in a 2118 configfs group. 2119 2120 2121config FAULT_INJECTION_STACKTRACE_FILTER 2122 bool "stacktrace filter for fault-injection capabilities" 2123 depends on FAULT_INJECTION 2124 depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT 2125 select STACKTRACE 2126 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 2127 help 2128 Provide stacktrace filter for fault-injection capabilities 2129 2130config ARCH_HAS_KCOV 2131 bool 2132 help 2133 An architecture should select this when it can successfully 2134 build and run with CONFIG_KCOV. This typically requires 2135 disabling instrumentation for some early boot code. 2136 2137config CC_HAS_SANCOV_TRACE_PC 2138 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 2139 2140 2141config KCOV 2142 bool "Code coverage for fuzzing" 2143 depends on ARCH_HAS_KCOV 2144 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 2145 depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \ 2146 GCC_VERSION >= 120000 || CC_IS_CLANG 2147 select DEBUG_FS 2148 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 2149 select OBJTOOL if HAVE_NOINSTR_HACK 2150 help 2151 KCOV exposes kernel code coverage information in a form suitable 2152 for coverage-guided fuzzing (randomized testing). 2153 2154 For more details, see Documentation/dev-tools/kcov.rst. 2155 2156config KCOV_ENABLE_COMPARISONS 2157 bool "Enable comparison operands collection by KCOV" 2158 depends on KCOV 2159 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 2160 help 2161 KCOV also exposes operands of every comparison in the instrumented 2162 code along with operand sizes and PCs of the comparison instructions. 2163 These operands can be used by fuzzing engines to improve the quality 2164 of fuzzing coverage. 2165 2166config KCOV_INSTRUMENT_ALL 2167 bool "Instrument all code by default" 2168 depends on KCOV 2169 default y 2170 help 2171 If you are doing generic system call fuzzing (like e.g. syzkaller), 2172 then you will want to instrument the whole kernel and you should 2173 say y here. If you are doing more targeted fuzzing (like e.g. 2174 filesystem fuzzing with AFL) then you will want to enable coverage 2175 for more specific subsets of files, and should say n here. 2176 2177config KCOV_IRQ_AREA_SIZE 2178 hex "Size of interrupt coverage collection area in words" 2179 depends on KCOV 2180 default 0x40000 2181 help 2182 KCOV uses preallocated per-cpu areas to collect coverage from 2183 soft interrupts. This specifies the size of those areas in the 2184 number of unsigned long words. 2185 2186config KCOV_SELFTEST 2187 bool "Perform short selftests on boot" 2188 depends on KCOV 2189 help 2190 Run short KCOV coverage collection selftests on boot. 2191 On test failure, causes the kernel to panic. Recommended to be 2192 enabled, ensuring critical functionality works as intended. 2193 2194menuconfig RUNTIME_TESTING_MENU 2195 bool "Runtime Testing" 2196 default y 2197 2198if RUNTIME_TESTING_MENU 2199 2200config TEST_DHRY 2201 tristate "Dhrystone benchmark test" 2202 help 2203 Enable this to include the Dhrystone 2.1 benchmark. This test 2204 calculates the number of Dhrystones per second, and the number of 2205 DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided 2206 by 1757 (the number of Dhrystones per second obtained on the VAX 2207 11/780, nominally a 1 MIPS machine). 2208 2209 To run the benchmark, it needs to be enabled explicitly, either from 2210 the kernel command line (when built-in), or from userspace (when 2211 built-in or modular). 2212 2213 Run once during kernel boot: 2214 2215 test_dhry.run 2216 2217 Set number of iterations from kernel command line: 2218 2219 test_dhry.iterations=<n> 2220 2221 Set number of iterations from userspace: 2222 2223 echo <n> > /sys/module/test_dhry/parameters/iterations 2224 2225 Trigger manual run from userspace: 2226 2227 echo y > /sys/module/test_dhry/parameters/run 2228 2229 If the number of iterations is <= 0, the test will devise a suitable 2230 number of iterations (test runs for at least 2s) automatically. 2231 This process takes ca. 4s. 2232 2233 If unsure, say N. 2234 2235config LKDTM 2236 tristate "Linux Kernel Dump Test Tool Module" 2237 depends on DEBUG_FS 2238 help 2239 This module enables testing of the different dumping mechanisms by 2240 inducing system failures at predefined crash points. 2241 If you don't need it: say N 2242 Choose M here to compile this code as a module. The module will be 2243 called lkdtm. 2244 2245 Documentation on how to use the module can be found in 2246 Documentation/fault-injection/provoke-crashes.rst 2247 2248config CPUMASK_KUNIT_TEST 2249 tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS 2250 depends on KUNIT 2251 default KUNIT_ALL_TESTS 2252 help 2253 Enable to turn on cpumask tests, running at boot or module load time. 2254 2255 For more information on KUnit and unit tests in general, please refer 2256 to the KUnit documentation in Documentation/dev-tools/kunit/. 2257 2258 If unsure, say N. 2259 2260config TEST_LIST_SORT 2261 tristate "Linked list sorting test" if !KUNIT_ALL_TESTS 2262 depends on KUNIT 2263 default KUNIT_ALL_TESTS 2264 help 2265 Enable this to turn on 'list_sort()' function test. This test is 2266 executed only once during system boot (so affects only boot time), 2267 or at module load time. 2268 2269 If unsure, say N. 2270 2271config TEST_MIN_HEAP 2272 tristate "Min heap test" 2273 depends on DEBUG_KERNEL || m 2274 help 2275 Enable this to turn on min heap function tests. This test is 2276 executed only once during system boot (so affects only boot time), 2277 or at module load time. 2278 2279 If unsure, say N. 2280 2281config TEST_SORT 2282 tristate "Array-based sort test" if !KUNIT_ALL_TESTS 2283 depends on KUNIT 2284 default KUNIT_ALL_TESTS 2285 help 2286 This option enables the self-test function of 'sort()' at boot, 2287 or at module load time. 2288 2289 If unsure, say N. 2290 2291config TEST_DIV64 2292 tristate "64bit/32bit division and modulo test" 2293 depends on DEBUG_KERNEL || m 2294 help 2295 Enable this to turn on 'do_div()' function test. This test is 2296 executed only once during system boot (so affects only boot time), 2297 or at module load time. 2298 2299 If unsure, say N. 2300 2301config TEST_MULDIV64 2302 tristate "mul_u64_u64_div_u64() test" 2303 depends on DEBUG_KERNEL || m 2304 help 2305 Enable this to turn on 'mul_u64_u64_div_u64()' function test. 2306 This test is executed only once during system boot (so affects 2307 only boot time), or at module load time. 2308 2309 If unsure, say N. 2310 2311config TEST_IOV_ITER 2312 tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS 2313 depends on KUNIT 2314 depends on MMU 2315 default KUNIT_ALL_TESTS 2316 help 2317 Enable this to turn on testing of the operation of the I/O iterator 2318 (iov_iter). This test is executed only once during system boot (so 2319 affects only boot time), or at module load time. 2320 2321 If unsure, say N. 2322 2323config KPROBES_SANITY_TEST 2324 tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS 2325 depends on DEBUG_KERNEL 2326 depends on KPROBES 2327 depends on KUNIT 2328 select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 2329 default KUNIT_ALL_TESTS 2330 help 2331 This option provides for testing basic kprobes functionality on 2332 boot. Samples of kprobe and kretprobe are inserted and 2333 verified for functionality. 2334 2335 Say N if you are unsure. 2336 2337config FPROBE_SANITY_TEST 2338 bool "Self test for fprobe" 2339 depends on DEBUG_KERNEL 2340 depends on FPROBE 2341 depends on KUNIT=y 2342 help 2343 This option will enable testing the fprobe when the system boot. 2344 A series of tests are made to verify that the fprobe is functioning 2345 properly. 2346 2347 Say N if you are unsure. 2348 2349config BACKTRACE_SELF_TEST 2350 tristate "Self test for the backtrace code" 2351 depends on DEBUG_KERNEL 2352 help 2353 This option provides a kernel module that can be used to test 2354 the kernel stack backtrace code. This option is not useful 2355 for distributions or general kernels, but only for kernel 2356 developers working on architecture code. 2357 2358 Note that if you want to also test saved backtraces, you will 2359 have to enable STACKTRACE as well. 2360 2361 Say N if you are unsure. 2362 2363config TEST_REF_TRACKER 2364 tristate "Self test for reference tracker" 2365 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT 2366 select REF_TRACKER 2367 help 2368 This option provides a kernel module performing tests 2369 using reference tracker infrastructure. 2370 2371 Say N if you are unsure. 2372 2373config RBTREE_TEST 2374 tristate "Red-Black tree test" 2375 depends on DEBUG_KERNEL 2376 help 2377 A benchmark measuring the performance of the rbtree library. 2378 Also includes rbtree invariant checks. 2379 2380config REED_SOLOMON_TEST 2381 tristate "Reed-Solomon library test" 2382 depends on DEBUG_KERNEL || m 2383 select REED_SOLOMON 2384 select REED_SOLOMON_ENC16 2385 select REED_SOLOMON_DEC16 2386 help 2387 This option enables the self-test function of rslib at boot, 2388 or at module load time. 2389 2390 If unsure, say N. 2391 2392config INTERVAL_TREE_TEST 2393 tristate "Interval tree test" 2394 depends on DEBUG_KERNEL 2395 select INTERVAL_TREE 2396 help 2397 A benchmark measuring the performance of the interval tree library 2398 2399config PERCPU_TEST 2400 tristate "Per cpu operations test" 2401 depends on m && DEBUG_KERNEL 2402 help 2403 Enable this option to build test module which validates per-cpu 2404 operations. 2405 2406 If unsure, say N. 2407 2408config ATOMIC64_SELFTEST 2409 tristate "Perform an atomic64_t self-test" 2410 help 2411 Enable this option to test the atomic64_t functions at boot or 2412 at module load time. 2413 2414 If unsure, say N. 2415 2416config ASYNC_RAID6_TEST 2417 tristate "Self test for hardware accelerated raid6 recovery" 2418 depends on ASYNC_RAID6_RECOV 2419 select ASYNC_MEMCPY 2420 help 2421 This is a one-shot self test that permutes through the 2422 recovery of all the possible two disk failure scenarios for a 2423 N-disk array. Recovery is performed with the asynchronous 2424 raid6 recovery routines, and will optionally use an offload 2425 engine if one is available. 2426 2427 If unsure, say N. 2428 2429config TEST_HEXDUMP 2430 tristate "Test functions located in the hexdump module at runtime" 2431 2432config STRING_KUNIT_TEST 2433 tristate "KUnit test string functions at runtime" if !KUNIT_ALL_TESTS 2434 depends on KUNIT 2435 default KUNIT_ALL_TESTS 2436 2437config STRING_HELPERS_KUNIT_TEST 2438 tristate "KUnit test string helpers at runtime" if !KUNIT_ALL_TESTS 2439 depends on KUNIT 2440 default KUNIT_ALL_TESTS 2441 2442config TEST_KSTRTOX 2443 tristate "Test kstrto*() family of functions at runtime" 2444 2445config TEST_PRINTF 2446 tristate "Test printf() family of functions at runtime" 2447 2448config TEST_SCANF 2449 tristate "Test scanf() family of functions at runtime" 2450 2451config TEST_BITMAP 2452 tristate "Test bitmap_*() family of functions at runtime" 2453 help 2454 Enable this option to test the bitmap functions at boot. 2455 2456 If unsure, say N. 2457 2458config TEST_UUID 2459 tristate "Test functions located in the uuid module at runtime" 2460 2461config TEST_XARRAY 2462 tristate "Test the XArray code at runtime" 2463 2464config TEST_MAPLE_TREE 2465 tristate "Test the Maple Tree code at runtime or module load" 2466 help 2467 Enable this option to test the maple tree code functions at boot, or 2468 when the module is loaded. Enable "Debug Maple Trees" will enable 2469 more verbose output on failures. 2470 2471 If unsure, say N. 2472 2473config TEST_RHASHTABLE 2474 tristate "Perform selftest on resizable hash table" 2475 help 2476 Enable this option to test the rhashtable functions at boot. 2477 2478 If unsure, say N. 2479 2480config TEST_IDA 2481 tristate "Perform selftest on IDA functions" 2482 2483config TEST_PARMAN 2484 tristate "Perform selftest on priority array manager" 2485 depends on PARMAN 2486 help 2487 Enable this option to test priority array manager on boot 2488 (or module load). 2489 2490 If unsure, say N. 2491 2492config TEST_IRQ_TIMINGS 2493 bool "IRQ timings selftest" 2494 depends on IRQ_TIMINGS 2495 help 2496 Enable this option to test the irq timings code on boot. 2497 2498 If unsure, say N. 2499 2500config TEST_LKM 2501 tristate "Test module loading with 'hello world' module" 2502 depends on m 2503 help 2504 This builds the "test_module" module that emits "Hello, world" 2505 on printk when loaded. It is designed to be used for basic 2506 evaluation of the module loading subsystem (for example when 2507 validating module verification). It lacks any extra dependencies, 2508 and will not normally be loaded by the system unless explicitly 2509 requested by name. 2510 2511 If unsure, say N. 2512 2513config TEST_BITOPS 2514 tristate "Test module for compilation of bitops operations" 2515 help 2516 This builds the "test_bitops" module that is much like the 2517 TEST_LKM module except that it does a basic exercise of the 2518 set/clear_bit macros and get_count_order/long to make sure there are 2519 no compiler warnings from C=1 sparse checker or -Wextra 2520 compilations. It has no dependencies and doesn't run or load unless 2521 explicitly requested by name. for example: modprobe test_bitops. 2522 2523 If unsure, say N. 2524 2525config TEST_VMALLOC 2526 tristate "Test module for stress/performance analysis of vmalloc allocator" 2527 default n 2528 depends on MMU 2529 depends on m 2530 help 2531 This builds the "test_vmalloc" module that should be used for 2532 stress and performance analysis. So, any new change for vmalloc 2533 subsystem can be evaluated from performance and stability point 2534 of view. 2535 2536 If unsure, say N. 2537 2538config TEST_BPF 2539 tristate "Test BPF filter functionality" 2540 depends on m && NET 2541 help 2542 This builds the "test_bpf" module that runs various test vectors 2543 against the BPF interpreter or BPF JIT compiler depending on the 2544 current setting. This is in particular useful for BPF JIT compiler 2545 development, but also to run regression tests against changes in 2546 the interpreter code. It also enables test stubs for eBPF maps and 2547 verifier used by user space verifier testsuite. 2548 2549 If unsure, say N. 2550 2551config TEST_BLACKHOLE_DEV 2552 tristate "Test blackhole netdev functionality" 2553 depends on m && NET 2554 help 2555 This builds the "test_blackhole_dev" module that validates the 2556 data path through this blackhole netdev. 2557 2558 If unsure, say N. 2559 2560config FIND_BIT_BENCHMARK 2561 tristate "Test find_bit functions" 2562 help 2563 This builds the "test_find_bit" module that measure find_*_bit() 2564 functions performance. 2565 2566 If unsure, say N. 2567 2568config TEST_FIRMWARE 2569 tristate "Test firmware loading via userspace interface" 2570 depends on FW_LOADER 2571 help 2572 This builds the "test_firmware" module that creates a userspace 2573 interface for testing firmware loading. This can be used to 2574 control the triggering of firmware loading without needing an 2575 actual firmware-using device. The contents can be rechecked by 2576 userspace. 2577 2578 If unsure, say N. 2579 2580config TEST_SYSCTL 2581 tristate "sysctl test driver" 2582 depends on PROC_SYSCTL 2583 help 2584 This builds the "test_sysctl" module. This driver enables to test the 2585 proc sysctl interfaces available to drivers safely without affecting 2586 production knobs which might alter system functionality. 2587 2588 If unsure, say N. 2589 2590config BITFIELD_KUNIT 2591 tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS 2592 depends on KUNIT 2593 default KUNIT_ALL_TESTS 2594 help 2595 Enable this option to test the bitfield functions at boot. 2596 2597 KUnit tests run during boot and output the results to the debug log 2598 in TAP format (http://testanything.org/). Only useful for kernel devs 2599 running the KUnit test harness, and not intended for inclusion into a 2600 production build. 2601 2602 For more information on KUnit and unit tests in general please refer 2603 to the KUnit documentation in Documentation/dev-tools/kunit/. 2604 2605 If unsure, say N. 2606 2607config CHECKSUM_KUNIT 2608 tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS 2609 depends on KUNIT 2610 default KUNIT_ALL_TESTS 2611 help 2612 Enable this option to test the checksum functions at boot. 2613 2614 KUnit tests run during boot and output the results to the debug log 2615 in TAP format (http://testanything.org/). Only useful for kernel devs 2616 running the KUnit test harness, and not intended for inclusion into a 2617 production build. 2618 2619 For more information on KUnit and unit tests in general please refer 2620 to the KUnit documentation in Documentation/dev-tools/kunit/. 2621 2622 If unsure, say N. 2623 2624config HASH_KUNIT_TEST 2625 tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS 2626 depends on KUNIT 2627 default KUNIT_ALL_TESTS 2628 help 2629 Enable this option to test the kernel's string (<linux/stringhash.h>), and 2630 integer (<linux/hash.h>) hash functions on boot. 2631 2632 KUnit tests run during boot and output the results to the debug log 2633 in TAP format (https://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 This is intended to help people writing architecture-specific 2641 optimized versions. If unsure, say N. 2642 2643config RESOURCE_KUNIT_TEST 2644 tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS 2645 depends on KUNIT 2646 default KUNIT_ALL_TESTS 2647 select GET_FREE_REGION 2648 help 2649 This builds the resource API unit test. 2650 Tests the logic of API provided by resource.c and ioport.h. 2651 For more information on KUnit and unit tests in general please refer 2652 to the KUnit documentation in Documentation/dev-tools/kunit/. 2653 2654 If unsure, say N. 2655 2656config SYSCTL_KUNIT_TEST 2657 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS 2658 depends on KUNIT 2659 default KUNIT_ALL_TESTS 2660 help 2661 This builds the proc sysctl unit test, which runs on boot. 2662 Tests the API contract and implementation correctness of sysctl. 2663 For more information on KUnit and unit tests in general please refer 2664 to the KUnit documentation in Documentation/dev-tools/kunit/. 2665 2666 If unsure, say N. 2667 2668config LIST_KUNIT_TEST 2669 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS 2670 depends on KUNIT 2671 default KUNIT_ALL_TESTS 2672 help 2673 This builds the linked list KUnit test suite. 2674 It tests that the API and basic functionality of the list_head type 2675 and associated macros. 2676 2677 KUnit tests run during boot and output the results to the debug log 2678 in TAP format (https://testanything.org/). Only useful for kernel devs 2679 running the KUnit test harness, and not intended for inclusion into a 2680 production build. 2681 2682 For more information on KUnit and unit tests in general please refer 2683 to the KUnit documentation in Documentation/dev-tools/kunit/. 2684 2685 If unsure, say N. 2686 2687config HASHTABLE_KUNIT_TEST 2688 tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS 2689 depends on KUNIT 2690 default KUNIT_ALL_TESTS 2691 help 2692 This builds the hashtable KUnit test suite. 2693 It tests the basic functionality of the API defined in 2694 include/linux/hashtable.h. For more information on KUnit and 2695 unit tests in general please refer to the KUnit documentation 2696 in Documentation/dev-tools/kunit/. 2697 2698 If unsure, say N. 2699 2700config LINEAR_RANGES_TEST 2701 tristate "KUnit test for linear_ranges" 2702 depends on KUNIT 2703 select LINEAR_RANGES 2704 help 2705 This builds the linear_ranges unit test, which runs on boot. 2706 Tests the linear_ranges logic correctness. 2707 For more information on KUnit and unit tests in general please refer 2708 to the KUnit documentation in Documentation/dev-tools/kunit/. 2709 2710 If unsure, say N. 2711 2712config CMDLINE_KUNIT_TEST 2713 tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS 2714 depends on KUNIT 2715 default KUNIT_ALL_TESTS 2716 help 2717 This builds the cmdline API unit test. 2718 Tests the logic of API provided by cmdline.c. 2719 For more information on KUnit and unit tests in general please refer 2720 to the KUnit documentation in Documentation/dev-tools/kunit/. 2721 2722 If unsure, say N. 2723 2724config BITS_TEST 2725 tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS 2726 depends on KUNIT 2727 default KUNIT_ALL_TESTS 2728 help 2729 This builds the bits unit test. 2730 Tests the logic of macros defined in bits.h. 2731 For more information on KUnit and unit tests in general please refer 2732 to the KUnit documentation in Documentation/dev-tools/kunit/. 2733 2734 If unsure, say N. 2735 2736config SLUB_KUNIT_TEST 2737 tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS 2738 depends on SLUB_DEBUG && KUNIT 2739 default KUNIT_ALL_TESTS 2740 help 2741 This builds SLUB allocator unit test. 2742 Tests SLUB cache debugging functionality. 2743 For more information on KUnit and unit tests in general please refer 2744 to the KUnit documentation in Documentation/dev-tools/kunit/. 2745 2746 If unsure, say N. 2747 2748config RATIONAL_KUNIT_TEST 2749 tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS 2750 depends on KUNIT && RATIONAL 2751 default KUNIT_ALL_TESTS 2752 help 2753 This builds the rational math unit test. 2754 For more information on KUnit and unit tests in general please refer 2755 to the KUnit documentation in Documentation/dev-tools/kunit/. 2756 2757 If unsure, say N. 2758 2759config MEMCPY_KUNIT_TEST 2760 tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS 2761 depends on KUNIT 2762 default KUNIT_ALL_TESTS 2763 help 2764 Builds unit tests for memcpy(), memmove(), and memset() functions. 2765 For more information on KUnit and unit tests in general please refer 2766 to the KUnit documentation in Documentation/dev-tools/kunit/. 2767 2768 If unsure, say N. 2769 2770config IS_SIGNED_TYPE_KUNIT_TEST 2771 tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS 2772 depends on KUNIT 2773 default KUNIT_ALL_TESTS 2774 help 2775 Builds unit tests for the is_signed_type() macro. 2776 2777 For more information on KUnit and unit tests in general please refer 2778 to the KUnit documentation in Documentation/dev-tools/kunit/. 2779 2780 If unsure, say N. 2781 2782config OVERFLOW_KUNIT_TEST 2783 tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS 2784 depends on KUNIT 2785 default KUNIT_ALL_TESTS 2786 help 2787 Builds unit tests for the check_*_overflow(), size_*(), allocation, and 2788 related functions. 2789 2790 For more information on KUnit and unit tests in general please refer 2791 to the KUnit documentation in Documentation/dev-tools/kunit/. 2792 2793 If unsure, say N. 2794 2795config STACKINIT_KUNIT_TEST 2796 tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS 2797 depends on KUNIT 2798 default KUNIT_ALL_TESTS 2799 help 2800 Test if the kernel is zero-initializing stack variables and 2801 padding. Coverage is controlled by compiler flags, 2802 CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO, 2803 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2804 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2805 2806config FORTIFY_KUNIT_TEST 2807 tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS 2808 depends on KUNIT 2809 default KUNIT_ALL_TESTS 2810 help 2811 Builds unit tests for checking internals of FORTIFY_SOURCE as used 2812 by the str*() and mem*() family of functions. For testing runtime 2813 traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests. 2814 2815config HW_BREAKPOINT_KUNIT_TEST 2816 bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS 2817 depends on HAVE_HW_BREAKPOINT 2818 depends on KUNIT=y 2819 default KUNIT_ALL_TESTS 2820 help 2821 Tests for hw_breakpoint constraints accounting. 2822 2823 If unsure, say N. 2824 2825config SIPHASH_KUNIT_TEST 2826 tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS 2827 depends on KUNIT 2828 default KUNIT_ALL_TESTS 2829 help 2830 Enable this option to test the kernel's siphash (<linux/siphash.h>) hash 2831 functions on boot (or module load). 2832 2833 This is intended to help people writing architecture-specific 2834 optimized versions. If unsure, say N. 2835 2836config USERCOPY_KUNIT_TEST 2837 tristate "KUnit Test for user/kernel boundary protections" 2838 depends on KUNIT 2839 default KUNIT_ALL_TESTS 2840 help 2841 This builds the "usercopy_kunit" module that runs sanity checks 2842 on the copy_to/from_user infrastructure, making sure basic 2843 user/kernel boundary testing is working. 2844 2845config TEST_UDELAY 2846 tristate "udelay test driver" 2847 help 2848 This builds the "udelay_test" module that helps to make sure 2849 that udelay() is working properly. 2850 2851 If unsure, say N. 2852 2853config TEST_STATIC_KEYS 2854 tristate "Test static keys" 2855 depends on m 2856 help 2857 Test the static key interfaces. 2858 2859 If unsure, say N. 2860 2861config TEST_DYNAMIC_DEBUG 2862 tristate "Test DYNAMIC_DEBUG" 2863 depends on DYNAMIC_DEBUG 2864 help 2865 This module registers a tracer callback to count enabled 2866 pr_debugs in a 'do_debugging' function, then alters their 2867 enablements, calls the function, and compares counts. 2868 2869 If unsure, say N. 2870 2871config TEST_KMOD 2872 tristate "kmod stress tester" 2873 depends on m 2874 depends on NETDEVICES && NET_CORE && INET # for TUN 2875 depends on BLOCK 2876 depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS 2877 select TEST_LKM 2878 select XFS_FS 2879 select TUN 2880 select BTRFS_FS 2881 help 2882 Test the kernel's module loading mechanism: kmod. kmod implements 2883 support to load modules using the Linux kernel's usermode helper. 2884 This test provides a series of tests against kmod. 2885 2886 Although technically you can either build test_kmod as a module or 2887 into the kernel we disallow building it into the kernel since 2888 it stress tests request_module() and this will very likely cause 2889 some issues by taking over precious threads available from other 2890 module load requests, ultimately this could be fatal. 2891 2892 To run tests run: 2893 2894 tools/testing/selftests/kmod/kmod.sh --help 2895 2896 If unsure, say N. 2897 2898config TEST_DEBUG_VIRTUAL 2899 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 2900 depends on DEBUG_VIRTUAL 2901 help 2902 Test the kernel's ability to detect incorrect calls to 2903 virt_to_phys() done against the non-linear part of the 2904 kernel's virtual address map. 2905 2906 If unsure, say N. 2907 2908config TEST_MEMCAT_P 2909 tristate "Test memcat_p() helper function" 2910 help 2911 Test the memcat_p() helper for correctly merging two 2912 pointer arrays together. 2913 2914 If unsure, say N. 2915 2916config TEST_OBJAGG 2917 tristate "Perform selftest on object aggreration manager" 2918 default n 2919 depends on OBJAGG 2920 help 2921 Enable this option to test object aggregation manager on boot 2922 (or module load). 2923 2924config TEST_MEMINIT 2925 tristate "Test heap/page initialization" 2926 help 2927 Test if the kernel is zero-initializing heap and page allocations. 2928 This can be useful to test init_on_alloc and init_on_free features. 2929 2930 If unsure, say N. 2931 2932config TEST_HMM 2933 tristate "Test HMM (Heterogeneous Memory Management)" 2934 depends on TRANSPARENT_HUGEPAGE 2935 depends on DEVICE_PRIVATE 2936 select HMM_MIRROR 2937 select MMU_NOTIFIER 2938 help 2939 This is a pseudo device driver solely for testing HMM. 2940 Say M here if you want to build the HMM test module. 2941 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests. 2942 2943 If unsure, say N. 2944 2945config TEST_FREE_PAGES 2946 tristate "Test freeing pages" 2947 help 2948 Test that a memory leak does not occur due to a race between 2949 freeing a block of pages and a speculative page reference. 2950 Loading this module is safe if your kernel has the bug fixed. 2951 If the bug is not fixed, it will leak gigabytes of memory and 2952 probably OOM your system. 2953 2954config TEST_FPU 2955 tristate "Test floating point operations in kernel space" 2956 depends on ARCH_HAS_KERNEL_FPU_SUPPORT && !KCOV_INSTRUMENT_ALL 2957 help 2958 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu 2959 which will trigger a sequence of floating point operations. This is used 2960 for self-testing floating point control register setting in 2961 kernel_fpu_begin(). 2962 2963 If unsure, say N. 2964 2965config TEST_CLOCKSOURCE_WATCHDOG 2966 tristate "Test clocksource watchdog in kernel space" 2967 depends on CLOCKSOURCE_WATCHDOG 2968 help 2969 Enable this option to create a kernel module that will trigger 2970 a test of the clocksource watchdog. This module may be loaded 2971 via modprobe or insmod in which case it will run upon being 2972 loaded, or it may be built in, in which case it will run 2973 shortly after boot. 2974 2975 If unsure, say N. 2976 2977config TEST_OBJPOOL 2978 tristate "Test module for correctness and stress of objpool" 2979 default n 2980 depends on m && DEBUG_KERNEL 2981 help 2982 This builds the "test_objpool" module that should be used for 2983 correctness verification and concurrent testings of objects 2984 allocation and reclamation. 2985 2986 If unsure, say N. 2987 2988endif # RUNTIME_TESTING_MENU 2989 2990config ARCH_USE_MEMTEST 2991 bool 2992 help 2993 An architecture should select this when it uses early_memtest() 2994 during boot process. 2995 2996config MEMTEST 2997 bool "Memtest" 2998 depends on ARCH_USE_MEMTEST 2999 help 3000 This option adds a kernel parameter 'memtest', which allows memtest 3001 to be set and executed. 3002 memtest=0, mean disabled; -- default 3003 memtest=1, mean do 1 test pattern; 3004 ... 3005 memtest=17, mean do 17 test patterns. 3006 If you are unsure how to answer this question, answer N. 3007 3008 3009 3010config HYPERV_TESTING 3011 bool "Microsoft Hyper-V driver testing" 3012 default n 3013 depends on HYPERV && DEBUG_FS 3014 help 3015 Select this option to enable Hyper-V vmbus testing. 3016 3017endmenu # "Kernel Testing and Coverage" 3018 3019menu "Rust hacking" 3020 3021config RUST_DEBUG_ASSERTIONS 3022 bool "Debug assertions" 3023 depends on RUST 3024 help 3025 Enables rustc's `-Cdebug-assertions` codegen option. 3026 3027 This flag lets you turn `cfg(debug_assertions)` conditional 3028 compilation on or off. This can be used to enable extra debugging 3029 code in development but not in production. For example, it controls 3030 the behavior of the standard library's `debug_assert!` macro. 3031 3032 Note that this will apply to all Rust code, including `core`. 3033 3034 If unsure, say N. 3035 3036config RUST_OVERFLOW_CHECKS 3037 bool "Overflow checks" 3038 default y 3039 depends on RUST 3040 help 3041 Enables rustc's `-Coverflow-checks` codegen option. 3042 3043 This flag allows you to control the behavior of runtime integer 3044 overflow. When overflow-checks are enabled, a Rust panic will occur 3045 on overflow. 3046 3047 Note that this will apply to all Rust code, including `core`. 3048 3049 If unsure, say Y. 3050 3051config RUST_BUILD_ASSERT_ALLOW 3052 bool "Allow unoptimized build-time assertions" 3053 depends on RUST 3054 help 3055 Controls how are `build_error!` and `build_assert!` handled during build. 3056 3057 If calls to them exist in the binary, it may indicate a violated invariant 3058 or that the optimizer failed to verify the invariant during compilation. 3059 3060 This should not happen, thus by default the build is aborted. However, 3061 as an escape hatch, you can choose Y here to ignore them during build 3062 and let the check be carried at runtime (with `panic!` being called if 3063 the check fails). 3064 3065 If unsure, say N. 3066 3067config RUST_KERNEL_DOCTESTS 3068 bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS 3069 depends on RUST && KUNIT=y 3070 default KUNIT_ALL_TESTS 3071 help 3072 This builds the documentation tests of the `kernel` crate 3073 as KUnit tests. 3074 3075 For more information on KUnit and unit tests in general, 3076 please refer to the KUnit documentation in Documentation/dev-tools/kunit/. 3077 3078 If unsure, say N. 3079 3080endmenu # "Rust" 3081 3082endmenu # Kernel hacking 3083 3084config INT_POW_TEST 3085 tristate "Integer exponentiation (int_pow) test" if !KUNIT_ALL_TESTS 3086 depends on KUNIT 3087 default KUNIT_ALL_TESTS 3088 help 3089 This option enables the KUnit test suite for the int_pow function, 3090 which performs integer exponentiation. The test suite is designed to 3091 verify that the implementation of int_pow correctly computes the power 3092 of a given base raised to a given exponent. 3093 3094 Enabling this option will include tests that check various scenarios 3095 and edge cases to ensure the accuracy and reliability of the exponentiation 3096 function. 3097 3098 If unsure, say N 3099