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 MMU 997 depends on PROC_FS 998 depends on !DEBUG_FORCE_WEAK_PER_CPU 999 select CODE_TAGGING 1000 select PAGE_EXTENSION 1001 select SLAB_OBJ_EXT 1002 help 1003 Track allocation source code and record total allocation size 1004 initiated at that code location. The mechanism can be used to track 1005 memory leaks with a low performance and memory impact. 1006 1007config MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT 1008 bool "Enable memory allocation profiling by default" 1009 default y 1010 depends on MEM_ALLOC_PROFILING 1011 1012config MEM_ALLOC_PROFILING_DEBUG 1013 bool "Memory allocation profiler debugging" 1014 default n 1015 depends on MEM_ALLOC_PROFILING 1016 select MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT 1017 help 1018 Adds warnings with helpful error messages for memory allocation 1019 profiling. 1020 1021source "lib/Kconfig.kasan" 1022source "lib/Kconfig.kfence" 1023source "lib/Kconfig.kmsan" 1024 1025endmenu # "Memory Debugging" 1026 1027config DEBUG_SHIRQ 1028 bool "Debug shared IRQ handlers" 1029 depends on DEBUG_KERNEL 1030 help 1031 Enable this to generate a spurious interrupt just before a shared 1032 interrupt handler is deregistered (generating one when registering 1033 is currently disabled). Drivers need to handle this correctly. Some 1034 don't and need to be caught. 1035 1036menu "Debug Oops, Lockups and Hangs" 1037 1038config PANIC_ON_OOPS 1039 bool "Panic on Oops" 1040 help 1041 Say Y here to enable the kernel to panic when it oopses. This 1042 has the same effect as setting oops=panic on the kernel command 1043 line. 1044 1045 This feature is useful to ensure that the kernel does not do 1046 anything erroneous after an oops which could result in data 1047 corruption or other issues. 1048 1049 Say N if unsure. 1050 1051config PANIC_ON_OOPS_VALUE 1052 int 1053 range 0 1 1054 default 0 if !PANIC_ON_OOPS 1055 default 1 if PANIC_ON_OOPS 1056 1057config PANIC_TIMEOUT 1058 int "panic timeout" 1059 default 0 1060 help 1061 Set the timeout value (in seconds) until a reboot occurs when 1062 the kernel panics. If n = 0, then we wait forever. A timeout 1063 value n > 0 will wait n seconds before rebooting, while a timeout 1064 value n < 0 will reboot immediately. This setting can be overridden 1065 with the kernel command line option panic=, and from userspace via 1066 /proc/sys/kernel/panic. 1067 1068config LOCKUP_DETECTOR 1069 bool 1070 1071config SOFTLOCKUP_DETECTOR 1072 bool "Detect Soft Lockups" 1073 depends on DEBUG_KERNEL && !S390 1074 select LOCKUP_DETECTOR 1075 help 1076 Say Y here to enable the kernel to act as a watchdog to detect 1077 soft lockups. 1078 1079 Softlockups are bugs that cause the kernel to loop in kernel 1080 mode for more than 20 seconds, without giving other tasks a 1081 chance to run. The current stack trace is displayed upon 1082 detection and the system will stay locked up. 1083 1084config SOFTLOCKUP_DETECTOR_INTR_STORM 1085 bool "Detect Interrupt Storm in Soft Lockups" 1086 depends on SOFTLOCKUP_DETECTOR && IRQ_TIME_ACCOUNTING 1087 select GENERIC_IRQ_STAT_SNAPSHOT 1088 default y if NR_CPUS <= 128 1089 help 1090 Say Y here to enable the kernel to detect interrupt storm 1091 during "soft lockups". 1092 1093 "soft lockups" can be caused by a variety of reasons. If one is 1094 caused by an interrupt storm, then the storming interrupts will not 1095 be on the callstack. To detect this case, it is necessary to report 1096 the CPU stats and the interrupt counts during the "soft lockups". 1097 1098config BOOTPARAM_SOFTLOCKUP_PANIC 1099 bool "Panic (Reboot) On Soft Lockups" 1100 depends on SOFTLOCKUP_DETECTOR 1101 help 1102 Say Y here to enable the kernel to panic on "soft lockups", 1103 which are bugs that cause the kernel to loop in kernel 1104 mode for more than 20 seconds (configurable using the watchdog_thresh 1105 sysctl), without giving other tasks a chance to run. 1106 1107 The panic can be used in combination with panic_timeout, 1108 to cause the system to reboot automatically after a 1109 lockup has been detected. This feature is useful for 1110 high-availability systems that have uptime guarantees and 1111 where a lockup must be resolved ASAP. 1112 1113 Say N if unsure. 1114 1115config HAVE_HARDLOCKUP_DETECTOR_BUDDY 1116 bool 1117 depends on SMP 1118 default y 1119 1120# 1121# Global switch whether to build a hardlockup detector at all. It is available 1122# only when the architecture supports at least one implementation. There are 1123# two exceptions. The hardlockup detector is never enabled on: 1124# 1125# s390: it reported many false positives there 1126# 1127# sparc64: has a custom implementation which is not using the common 1128# hardlockup command line options and sysctl interface. 1129# 1130config HARDLOCKUP_DETECTOR 1131 bool "Detect Hard Lockups" 1132 depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64 1133 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH 1134 imply HARDLOCKUP_DETECTOR_PERF 1135 imply HARDLOCKUP_DETECTOR_BUDDY 1136 imply HARDLOCKUP_DETECTOR_ARCH 1137 select LOCKUP_DETECTOR 1138 1139 help 1140 Say Y here to enable the kernel to act as a watchdog to detect 1141 hard lockups. 1142 1143 Hardlockups are bugs that cause the CPU to loop in kernel mode 1144 for more than 10 seconds, without letting other interrupts have a 1145 chance to run. The current stack trace is displayed upon detection 1146 and the system will stay locked up. 1147 1148# 1149# Note that arch-specific variants are always preferred. 1150# 1151config HARDLOCKUP_DETECTOR_PREFER_BUDDY 1152 bool "Prefer the buddy CPU hardlockup detector" 1153 depends on HARDLOCKUP_DETECTOR 1154 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY 1155 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1156 help 1157 Say Y here to prefer the buddy hardlockup detector over the perf one. 1158 1159 With the buddy detector, each CPU uses its softlockup hrtimer 1160 to check that the next CPU is processing hrtimer interrupts by 1161 verifying that a counter is increasing. 1162 1163 This hardlockup detector is useful on systems that don't have 1164 an arch-specific hardlockup detector or if resources needed 1165 for the hardlockup detector are better used for other things. 1166 1167config HARDLOCKUP_DETECTOR_PERF 1168 bool 1169 depends on HARDLOCKUP_DETECTOR 1170 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY 1171 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1172 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1173 1174config HARDLOCKUP_DETECTOR_BUDDY 1175 bool 1176 depends on HARDLOCKUP_DETECTOR 1177 depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY 1178 depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY 1179 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1180 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1181 1182config HARDLOCKUP_DETECTOR_ARCH 1183 bool 1184 depends on HARDLOCKUP_DETECTOR 1185 depends on HAVE_HARDLOCKUP_DETECTOR_ARCH 1186 help 1187 The arch-specific implementation of the hardlockup detector will 1188 be used. 1189 1190# 1191# Both the "perf" and "buddy" hardlockup detectors count hrtimer 1192# interrupts. This config enables functions managing this common code. 1193# 1194config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1195 bool 1196 select SOFTLOCKUP_DETECTOR 1197 1198# 1199# Enables a timestamp based low pass filter to compensate for perf based 1200# hard lockup detection which runs too fast due to turbo modes. 1201# 1202config HARDLOCKUP_CHECK_TIMESTAMP 1203 bool 1204 1205config BOOTPARAM_HARDLOCKUP_PANIC 1206 bool "Panic (Reboot) On Hard Lockups" 1207 depends on HARDLOCKUP_DETECTOR 1208 help 1209 Say Y here to enable the kernel to panic on "hard lockups", 1210 which are bugs that cause the kernel to loop in kernel 1211 mode with interrupts disabled for more than 10 seconds (configurable 1212 using the watchdog_thresh sysctl). 1213 1214 Say N if unsure. 1215 1216config DETECT_HUNG_TASK 1217 bool "Detect Hung Tasks" 1218 depends on DEBUG_KERNEL 1219 default SOFTLOCKUP_DETECTOR 1220 help 1221 Say Y here to enable the kernel to detect "hung tasks", 1222 which are bugs that cause the task to be stuck in 1223 uninterruptible "D" state indefinitely. 1224 1225 When a hung task is detected, the kernel will print the 1226 current stack trace (which you should report), but the 1227 task will stay in uninterruptible state. If lockdep is 1228 enabled then all held locks will also be reported. This 1229 feature has negligible overhead. 1230 1231config DEFAULT_HUNG_TASK_TIMEOUT 1232 int "Default timeout for hung task detection (in seconds)" 1233 depends on DETECT_HUNG_TASK 1234 default 120 1235 help 1236 This option controls the default timeout (in seconds) used 1237 to determine when a task has become non-responsive and should 1238 be considered hung. 1239 1240 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 1241 sysctl or by writing a value to 1242 /proc/sys/kernel/hung_task_timeout_secs. 1243 1244 A timeout of 0 disables the check. The default is two minutes. 1245 Keeping the default should be fine in most cases. 1246 1247config BOOTPARAM_HUNG_TASK_PANIC 1248 bool "Panic (Reboot) On Hung Tasks" 1249 depends on DETECT_HUNG_TASK 1250 help 1251 Say Y here to enable the kernel to panic on "hung tasks", 1252 which are bugs that cause the kernel to leave a task stuck 1253 in uninterruptible "D" state. 1254 1255 The panic can be used in combination with panic_timeout, 1256 to cause the system to reboot automatically after a 1257 hung task has been detected. This feature is useful for 1258 high-availability systems that have uptime guarantees and 1259 where a hung tasks must be resolved ASAP. 1260 1261 Say N if unsure. 1262 1263config WQ_WATCHDOG 1264 bool "Detect Workqueue Stalls" 1265 depends on DEBUG_KERNEL 1266 help 1267 Say Y here to enable stall detection on workqueues. If a 1268 worker pool doesn't make forward progress on a pending work 1269 item for over a given amount of time, 30s by default, a 1270 warning message is printed along with dump of workqueue 1271 state. This can be configured through kernel parameter 1272 "workqueue.watchdog_thresh" and its sysfs counterpart. 1273 1274config WQ_CPU_INTENSIVE_REPORT 1275 bool "Report per-cpu work items which hog CPU for too long" 1276 depends on DEBUG_KERNEL 1277 help 1278 Say Y here to enable reporting of concurrency-managed per-cpu work 1279 items that hog CPUs for longer than 1280 workqueue.cpu_intensive_thresh_us. Workqueue automatically 1281 detects and excludes them from concurrency management to prevent 1282 them from stalling other per-cpu work items. Occassional 1283 triggering may not necessarily indicate a problem. Repeated 1284 triggering likely indicates that the work item should be switched 1285 to use an unbound workqueue. 1286 1287config TEST_LOCKUP 1288 tristate "Test module to generate lockups" 1289 depends on m 1290 help 1291 This builds the "test_lockup" module that helps to make sure 1292 that watchdogs and lockup detectors are working properly. 1293 1294 Depending on module parameters it could emulate soft or hard 1295 lockup, "hung task", or locking arbitrary lock for a long time. 1296 Also it could generate series of lockups with cooling-down periods. 1297 1298 If unsure, say N. 1299 1300endmenu # "Debug lockups and hangs" 1301 1302menu "Scheduler Debugging" 1303 1304config SCHED_DEBUG 1305 bool "Collect scheduler debugging info" 1306 depends on DEBUG_KERNEL && DEBUG_FS 1307 default y 1308 help 1309 If you say Y here, the /sys/kernel/debug/sched file will be provided 1310 that can help debug the scheduler. The runtime overhead of this 1311 option is minimal. 1312 1313config SCHED_INFO 1314 bool 1315 default n 1316 1317config SCHEDSTATS 1318 bool "Collect scheduler statistics" 1319 depends on PROC_FS 1320 select SCHED_INFO 1321 help 1322 If you say Y here, additional code will be inserted into the 1323 scheduler and related routines to collect statistics about 1324 scheduler behavior and provide them in /proc/schedstat. These 1325 stats may be useful for both tuning and debugging the scheduler 1326 If you aren't debugging the scheduler or trying to tune a specific 1327 application, you can say N to avoid the very slight overhead 1328 this adds. 1329 1330endmenu 1331 1332config DEBUG_TIMEKEEPING 1333 bool "Enable extra timekeeping sanity checking" 1334 help 1335 This option will enable additional timekeeping sanity checks 1336 which may be helpful when diagnosing issues where timekeeping 1337 problems are suspected. 1338 1339 This may include checks in the timekeeping hotpaths, so this 1340 option may have a (very small) performance impact to some 1341 workloads. 1342 1343 If unsure, say N. 1344 1345config DEBUG_PREEMPT 1346 bool "Debug preemptible kernel" 1347 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1348 help 1349 If you say Y here then the kernel will use a debug variant of the 1350 commonly used smp_processor_id() function and will print warnings 1351 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1352 will detect preemption count underflows. 1353 1354 This option has potential to introduce high runtime overhead, 1355 depending on workload as it triggers debugging routines for each 1356 this_cpu operation. It should only be used for debugging purposes. 1357 1358menu "Lock Debugging (spinlocks, mutexes, etc...)" 1359 1360config LOCK_DEBUGGING_SUPPORT 1361 bool 1362 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1363 default y 1364 1365config PROVE_LOCKING 1366 bool "Lock debugging: prove locking correctness" 1367 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1368 select LOCKDEP 1369 select DEBUG_SPINLOCK 1370 select DEBUG_MUTEXES if !PREEMPT_RT 1371 select DEBUG_RT_MUTEXES if RT_MUTEXES 1372 select DEBUG_RWSEMS if !PREEMPT_RT 1373 select DEBUG_WW_MUTEX_SLOWPATH 1374 select DEBUG_LOCK_ALLOC 1375 select PREEMPT_COUNT if !ARCH_NO_PREEMPT 1376 select TRACE_IRQFLAGS 1377 default n 1378 help 1379 This feature enables the kernel to prove that all locking 1380 that occurs in the kernel runtime is mathematically 1381 correct: that under no circumstance could an arbitrary (and 1382 not yet triggered) combination of observed locking 1383 sequences (on an arbitrary number of CPUs, running an 1384 arbitrary number of tasks and interrupt contexts) cause a 1385 deadlock. 1386 1387 In short, this feature enables the kernel to report locking 1388 related deadlocks before they actually occur. 1389 1390 The proof does not depend on how hard and complex a 1391 deadlock scenario would be to trigger: how many 1392 participant CPUs, tasks and irq-contexts would be needed 1393 for it to trigger. The proof also does not depend on 1394 timing: if a race and a resulting deadlock is possible 1395 theoretically (no matter how unlikely the race scenario 1396 is), it will be proven so and will immediately be 1397 reported by the kernel (once the event is observed that 1398 makes the deadlock theoretically possible). 1399 1400 If a deadlock is impossible (i.e. the locking rules, as 1401 observed by the kernel, are mathematically correct), the 1402 kernel reports nothing. 1403 1404 NOTE: this feature can also be enabled for rwlocks, mutexes 1405 and rwsems - in which case all dependencies between these 1406 different locking variants are observed and mapped too, and 1407 the proof of observed correctness is also maintained for an 1408 arbitrary combination of these separate locking variants. 1409 1410 For more details, see Documentation/locking/lockdep-design.rst. 1411 1412config PROVE_RAW_LOCK_NESTING 1413 bool "Enable raw_spinlock - spinlock nesting checks" 1414 depends on PROVE_LOCKING 1415 default n 1416 help 1417 Enable the raw_spinlock vs. spinlock nesting checks which ensure 1418 that the lock nesting rules for PREEMPT_RT enabled kernels are 1419 not violated. 1420 1421 NOTE: There are known nesting problems. So if you enable this 1422 option expect lockdep splats until these problems have been fully 1423 addressed which is work in progress. This config switch allows to 1424 identify and analyze these problems. It will be removed and the 1425 check permanently enabled once the main issues have been fixed. 1426 1427 If unsure, select N. 1428 1429config LOCK_STAT 1430 bool "Lock usage statistics" 1431 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1432 select LOCKDEP 1433 select DEBUG_SPINLOCK 1434 select DEBUG_MUTEXES if !PREEMPT_RT 1435 select DEBUG_RT_MUTEXES if RT_MUTEXES 1436 select DEBUG_LOCK_ALLOC 1437 default n 1438 help 1439 This feature enables tracking lock contention points 1440 1441 For more details, see Documentation/locking/lockstat.rst 1442 1443 This also enables lock events required by "perf lock", 1444 subcommand of perf. 1445 If you want to use "perf lock", you also need to turn on 1446 CONFIG_EVENT_TRACING. 1447 1448 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1449 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1450 1451config DEBUG_RT_MUTEXES 1452 bool "RT Mutex debugging, deadlock detection" 1453 depends on DEBUG_KERNEL && RT_MUTEXES 1454 help 1455 This allows rt mutex semantics violations and rt mutex related 1456 deadlocks (lockups) to be detected and reported automatically. 1457 1458config DEBUG_SPINLOCK 1459 bool "Spinlock and rw-lock debugging: basic checks" 1460 depends on DEBUG_KERNEL 1461 select UNINLINE_SPIN_UNLOCK 1462 help 1463 Say Y here and build SMP to catch missing spinlock initialization 1464 and certain other kinds of spinlock errors commonly made. This is 1465 best used in conjunction with the NMI watchdog so that spinlock 1466 deadlocks are also debuggable. 1467 1468config DEBUG_MUTEXES 1469 bool "Mutex debugging: basic checks" 1470 depends on DEBUG_KERNEL && !PREEMPT_RT 1471 help 1472 This feature allows mutex semantics violations to be detected and 1473 reported. 1474 1475config DEBUG_WW_MUTEX_SLOWPATH 1476 bool "Wait/wound mutex debugging: Slowpath testing" 1477 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1478 select DEBUG_LOCK_ALLOC 1479 select DEBUG_SPINLOCK 1480 select DEBUG_MUTEXES if !PREEMPT_RT 1481 select DEBUG_RT_MUTEXES if PREEMPT_RT 1482 help 1483 This feature enables slowpath testing for w/w mutex users by 1484 injecting additional -EDEADLK wound/backoff cases. Together with 1485 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1486 will test all possible w/w mutex interface abuse with the 1487 exception of simply not acquiring all the required locks. 1488 Note that this feature can introduce significant overhead, so 1489 it really should not be enabled in a production or distro kernel, 1490 even a debug kernel. If you are a driver writer, enable it. If 1491 you are a distro, do not. 1492 1493config DEBUG_RWSEMS 1494 bool "RW Semaphore debugging: basic checks" 1495 depends on DEBUG_KERNEL && !PREEMPT_RT 1496 help 1497 This debugging feature allows mismatched rw semaphore locks 1498 and unlocks to be detected and reported. 1499 1500config DEBUG_LOCK_ALLOC 1501 bool "Lock debugging: detect incorrect freeing of live locks" 1502 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1503 select DEBUG_SPINLOCK 1504 select DEBUG_MUTEXES if !PREEMPT_RT 1505 select DEBUG_RT_MUTEXES if RT_MUTEXES 1506 select LOCKDEP 1507 help 1508 This feature will check whether any held lock (spinlock, rwlock, 1509 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1510 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1511 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1512 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1513 held during task exit. 1514 1515config LOCKDEP 1516 bool 1517 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1518 select STACKTRACE 1519 select KALLSYMS 1520 select KALLSYMS_ALL 1521 1522config LOCKDEP_SMALL 1523 bool 1524 1525config LOCKDEP_BITS 1526 int "Bitsize for MAX_LOCKDEP_ENTRIES" 1527 depends on LOCKDEP && !LOCKDEP_SMALL 1528 range 10 30 1529 default 15 1530 help 1531 Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message. 1532 1533config LOCKDEP_CHAINS_BITS 1534 int "Bitsize for MAX_LOCKDEP_CHAINS" 1535 depends on LOCKDEP && !LOCKDEP_SMALL 1536 range 10 21 1537 default 16 1538 help 1539 Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message. 1540 1541config LOCKDEP_STACK_TRACE_BITS 1542 int "Bitsize for MAX_STACK_TRACE_ENTRIES" 1543 depends on LOCKDEP && !LOCKDEP_SMALL 1544 range 10 30 1545 default 19 1546 help 1547 Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message. 1548 1549config LOCKDEP_STACK_TRACE_HASH_BITS 1550 int "Bitsize for STACK_TRACE_HASH_SIZE" 1551 depends on LOCKDEP && !LOCKDEP_SMALL 1552 range 10 30 1553 default 14 1554 help 1555 Try increasing this value if you need large STACK_TRACE_HASH_SIZE. 1556 1557config LOCKDEP_CIRCULAR_QUEUE_BITS 1558 int "Bitsize for elements in circular_queue struct" 1559 depends on LOCKDEP 1560 range 10 30 1561 default 12 1562 help 1563 Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure. 1564 1565config DEBUG_LOCKDEP 1566 bool "Lock dependency engine debugging" 1567 depends on DEBUG_KERNEL && LOCKDEP 1568 select DEBUG_IRQFLAGS 1569 help 1570 If you say Y here, the lock dependency engine will do 1571 additional runtime checks to debug itself, at the price 1572 of more runtime overhead. 1573 1574config DEBUG_ATOMIC_SLEEP 1575 bool "Sleep inside atomic section checking" 1576 select PREEMPT_COUNT 1577 depends on DEBUG_KERNEL 1578 depends on !ARCH_NO_PREEMPT 1579 help 1580 If you say Y here, various routines which may sleep will become very 1581 noisy if they are called inside atomic sections: when a spinlock is 1582 held, inside an rcu read side critical section, inside preempt disabled 1583 sections, inside an interrupt, etc... 1584 1585config DEBUG_LOCKING_API_SELFTESTS 1586 bool "Locking API boot-time self-tests" 1587 depends on DEBUG_KERNEL 1588 help 1589 Say Y here if you want the kernel to run a short self-test during 1590 bootup. The self-test checks whether common types of locking bugs 1591 are detected by debugging mechanisms or not. (if you disable 1592 lock debugging then those bugs won't be detected of course.) 1593 The following locking APIs are covered: spinlocks, rwlocks, 1594 mutexes and rwsems. 1595 1596config LOCK_TORTURE_TEST 1597 tristate "torture tests for locking" 1598 depends on DEBUG_KERNEL 1599 select TORTURE_TEST 1600 help 1601 This option provides a kernel module that runs torture tests 1602 on kernel locking primitives. The kernel module may be built 1603 after the fact on the running kernel to be tested, if desired. 1604 1605 Say Y here if you want kernel locking-primitive torture tests 1606 to be built into the kernel. 1607 Say M if you want these torture tests to build as a module. 1608 Say N if you are unsure. 1609 1610config WW_MUTEX_SELFTEST 1611 tristate "Wait/wound mutex selftests" 1612 help 1613 This option provides a kernel module that runs tests on the 1614 on the struct ww_mutex locking API. 1615 1616 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1617 with this test harness. 1618 1619 Say M if you want these self tests to build as a module. 1620 Say N if you are unsure. 1621 1622config SCF_TORTURE_TEST 1623 tristate "torture tests for smp_call_function*()" 1624 depends on DEBUG_KERNEL 1625 select TORTURE_TEST 1626 help 1627 This option provides a kernel module that runs torture tests 1628 on the smp_call_function() family of primitives. The kernel 1629 module may be built after the fact on the running kernel to 1630 be tested, if desired. 1631 1632config CSD_LOCK_WAIT_DEBUG 1633 bool "Debugging for csd_lock_wait(), called from smp_call_function*()" 1634 depends on DEBUG_KERNEL 1635 depends on SMP 1636 depends on 64BIT 1637 default n 1638 help 1639 This option enables debug prints when CPUs are slow to respond 1640 to the smp_call_function*() IPI wrappers. These debug prints 1641 include the IPI handler function currently executing (if any) 1642 and relevant stack traces. 1643 1644config CSD_LOCK_WAIT_DEBUG_DEFAULT 1645 bool "Default csd_lock_wait() debugging on at boot time" 1646 depends on CSD_LOCK_WAIT_DEBUG 1647 depends on 64BIT 1648 default n 1649 help 1650 This option causes the csdlock_debug= kernel boot parameter to 1651 default to 1 (basic debugging) instead of 0 (no debugging). 1652 1653endmenu # lock debugging 1654 1655config TRACE_IRQFLAGS 1656 depends on TRACE_IRQFLAGS_SUPPORT 1657 bool 1658 help 1659 Enables hooks to interrupt enabling and disabling for 1660 either tracing or lock debugging. 1661 1662config TRACE_IRQFLAGS_NMI 1663 def_bool y 1664 depends on TRACE_IRQFLAGS 1665 depends on TRACE_IRQFLAGS_NMI_SUPPORT 1666 1667config NMI_CHECK_CPU 1668 bool "Debugging for CPUs failing to respond to backtrace requests" 1669 depends on DEBUG_KERNEL 1670 depends on X86 1671 default n 1672 help 1673 Enables debug prints when a CPU fails to respond to a given 1674 backtrace NMI. These prints provide some reasons why a CPU 1675 might legitimately be failing to respond, for example, if it 1676 is offline of if ignore_nmis is set. 1677 1678config DEBUG_IRQFLAGS 1679 bool "Debug IRQ flag manipulation" 1680 help 1681 Enables checks for potentially unsafe enabling or disabling of 1682 interrupts, such as calling raw_local_irq_restore() when interrupts 1683 are enabled. 1684 1685config STACKTRACE 1686 bool "Stack backtrace support" 1687 depends on STACKTRACE_SUPPORT 1688 help 1689 This option causes the kernel to create a /proc/pid/stack for 1690 every process, showing its current stack trace. 1691 It is also used by various kernel debugging features that require 1692 stack trace generation. 1693 1694config WARN_ALL_UNSEEDED_RANDOM 1695 bool "Warn for all uses of unseeded randomness" 1696 default n 1697 help 1698 Some parts of the kernel contain bugs relating to their use of 1699 cryptographically secure random numbers before it's actually possible 1700 to generate those numbers securely. This setting ensures that these 1701 flaws don't go unnoticed, by enabling a message, should this ever 1702 occur. This will allow people with obscure setups to know when things 1703 are going wrong, so that they might contact developers about fixing 1704 it. 1705 1706 Unfortunately, on some models of some architectures getting 1707 a fully seeded CRNG is extremely difficult, and so this can 1708 result in dmesg getting spammed for a surprisingly long 1709 time. This is really bad from a security perspective, and 1710 so architecture maintainers really need to do what they can 1711 to get the CRNG seeded sooner after the system is booted. 1712 However, since users cannot do anything actionable to 1713 address this, by default this option is disabled. 1714 1715 Say Y here if you want to receive warnings for all uses of 1716 unseeded randomness. This will be of use primarily for 1717 those developers interested in improving the security of 1718 Linux kernels running on their architecture (or 1719 subarchitecture). 1720 1721config DEBUG_KOBJECT 1722 bool "kobject debugging" 1723 depends on DEBUG_KERNEL 1724 help 1725 If you say Y here, some extra kobject debugging messages will be sent 1726 to the syslog. 1727 1728config DEBUG_KOBJECT_RELEASE 1729 bool "kobject release debugging" 1730 depends on DEBUG_OBJECTS_TIMERS 1731 help 1732 kobjects are reference counted objects. This means that their 1733 last reference count put is not predictable, and the kobject can 1734 live on past the point at which a driver decides to drop its 1735 initial reference to the kobject gained on allocation. An 1736 example of this would be a struct device which has just been 1737 unregistered. 1738 1739 However, some buggy drivers assume that after such an operation, 1740 the memory backing the kobject can be immediately freed. This 1741 goes completely against the principles of a refcounted object. 1742 1743 If you say Y here, the kernel will delay the release of kobjects 1744 on the last reference count to improve the visibility of this 1745 kind of kobject release bug. 1746 1747config HAVE_DEBUG_BUGVERBOSE 1748 bool 1749 1750menu "Debug kernel data structures" 1751 1752config DEBUG_LIST 1753 bool "Debug linked list manipulation" 1754 depends on DEBUG_KERNEL 1755 select LIST_HARDENED 1756 help 1757 Enable this to turn on extended checks in the linked-list walking 1758 routines. 1759 1760 This option trades better quality error reports for performance, and 1761 is more suitable for kernel debugging. If you care about performance, 1762 you should only enable CONFIG_LIST_HARDENED instead. 1763 1764 If unsure, say N. 1765 1766config DEBUG_PLIST 1767 bool "Debug priority linked list manipulation" 1768 depends on DEBUG_KERNEL 1769 help 1770 Enable this to turn on extended checks in the priority-ordered 1771 linked-list (plist) walking routines. This checks the entire 1772 list multiple times during each manipulation. 1773 1774 If unsure, say N. 1775 1776config DEBUG_SG 1777 bool "Debug SG table operations" 1778 depends on DEBUG_KERNEL 1779 help 1780 Enable this to turn on checks on scatter-gather tables. This can 1781 help find problems with drivers that do not properly initialize 1782 their sg tables. 1783 1784 If unsure, say N. 1785 1786config DEBUG_NOTIFIERS 1787 bool "Debug notifier call chains" 1788 depends on DEBUG_KERNEL 1789 help 1790 Enable this to turn on sanity checking for notifier call chains. 1791 This is most useful for kernel developers to make sure that 1792 modules properly unregister themselves from notifier chains. 1793 This is a relatively cheap check but if you care about maximum 1794 performance, say N. 1795 1796config DEBUG_CLOSURES 1797 bool "Debug closures (bcache async widgits)" 1798 depends on CLOSURES 1799 select DEBUG_FS 1800 help 1801 Keeps all active closures in a linked list and provides a debugfs 1802 interface to list them, which makes it possible to see asynchronous 1803 operations that get stuck. 1804 1805config DEBUG_MAPLE_TREE 1806 bool "Debug maple trees" 1807 depends on DEBUG_KERNEL 1808 help 1809 Enable maple tree debugging information and extra validations. 1810 1811 If unsure, say N. 1812 1813endmenu 1814 1815source "kernel/rcu/Kconfig.debug" 1816 1817config DEBUG_WQ_FORCE_RR_CPU 1818 bool "Force round-robin CPU selection for unbound work items" 1819 depends on DEBUG_KERNEL 1820 default n 1821 help 1822 Workqueue used to implicitly guarantee that work items queued 1823 without explicit CPU specified are put on the local CPU. This 1824 guarantee is no longer true and while local CPU is still 1825 preferred work items may be put on foreign CPUs. Kernel 1826 parameter "workqueue.debug_force_rr_cpu" is added to force 1827 round-robin CPU selection to flush out usages which depend on the 1828 now broken guarantee. This config option enables the debug 1829 feature by default. When enabled, memory and cache locality will 1830 be impacted. 1831 1832config CPU_HOTPLUG_STATE_CONTROL 1833 bool "Enable CPU hotplug state control" 1834 depends on DEBUG_KERNEL 1835 depends on HOTPLUG_CPU 1836 default n 1837 help 1838 Allows to write steps between "offline" and "online" to the CPUs 1839 sysfs target file so states can be stepped granular. This is a debug 1840 option for now as the hotplug machinery cannot be stopped and 1841 restarted at arbitrary points yet. 1842 1843 Say N if your are unsure. 1844 1845config LATENCYTOP 1846 bool "Latency measuring infrastructure" 1847 depends on DEBUG_KERNEL 1848 depends on STACKTRACE_SUPPORT 1849 depends on PROC_FS 1850 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 1851 select KALLSYMS 1852 select KALLSYMS_ALL 1853 select STACKTRACE 1854 select SCHEDSTATS 1855 help 1856 Enable this option if you want to use the LatencyTOP tool 1857 to find out which userspace is blocking on what kernel operations. 1858 1859config DEBUG_CGROUP_REF 1860 bool "Disable inlining of cgroup css reference count functions" 1861 depends on DEBUG_KERNEL 1862 depends on CGROUPS 1863 depends on KPROBES 1864 default n 1865 help 1866 Force cgroup css reference count functions to not be inlined so 1867 that they can be kprobed for debugging. 1868 1869source "kernel/trace/Kconfig" 1870 1871config PROVIDE_OHCI1394_DMA_INIT 1872 bool "Remote debugging over FireWire early on boot" 1873 depends on PCI && X86 1874 help 1875 If you want to debug problems which hang or crash the kernel early 1876 on boot and the crashing machine has a FireWire port, you can use 1877 this feature to remotely access the memory of the crashed machine 1878 over FireWire. This employs remote DMA as part of the OHCI1394 1879 specification which is now the standard for FireWire controllers. 1880 1881 With remote DMA, you can monitor the printk buffer remotely using 1882 firescope and access all memory below 4GB using fireproxy from gdb. 1883 Even controlling a kernel debugger is possible using remote DMA. 1884 1885 Usage: 1886 1887 If ohci1394_dma=early is used as boot parameter, it will initialize 1888 all OHCI1394 controllers which are found in the PCI config space. 1889 1890 As all changes to the FireWire bus such as enabling and disabling 1891 devices cause a bus reset and thereby disable remote DMA for all 1892 devices, be sure to have the cable plugged and FireWire enabled on 1893 the debugging host before booting the debug target for debugging. 1894 1895 This code (~1k) is freed after boot. By then, the firewire stack 1896 in charge of the OHCI-1394 controllers should be used instead. 1897 1898 See Documentation/core-api/debugging-via-ohci1394.rst for more information. 1899 1900source "samples/Kconfig" 1901 1902config ARCH_HAS_DEVMEM_IS_ALLOWED 1903 bool 1904 1905config STRICT_DEVMEM 1906 bool "Filter access to /dev/mem" 1907 depends on MMU && DEVMEM 1908 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED 1909 default y if PPC || X86 || ARM64 1910 help 1911 If this option is disabled, you allow userspace (root) access to all 1912 of memory, including kernel and userspace memory. Accidental 1913 access to this is obviously disastrous, but specific access can 1914 be used by people debugging the kernel. Note that with PAT support 1915 enabled, even in this case there are restrictions on /dev/mem 1916 use due to the cache aliasing requirements. 1917 1918 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 1919 file only allows userspace access to PCI space and the BIOS code and 1920 data regions. This is sufficient for dosemu and X and all common 1921 users of /dev/mem. 1922 1923 If in doubt, say Y. 1924 1925config IO_STRICT_DEVMEM 1926 bool "Filter I/O access to /dev/mem" 1927 depends on STRICT_DEVMEM 1928 help 1929 If this option is disabled, you allow userspace (root) access to all 1930 io-memory regardless of whether a driver is actively using that 1931 range. Accidental access to this is obviously disastrous, but 1932 specific access can be used by people debugging kernel drivers. 1933 1934 If this option is switched on, the /dev/mem file only allows 1935 userspace access to *idle* io-memory ranges (see /proc/iomem) This 1936 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 1937 if the driver using a given range cannot be disabled. 1938 1939 If in doubt, say Y. 1940 1941menu "$(SRCARCH) Debugging" 1942 1943source "arch/$(SRCARCH)/Kconfig.debug" 1944 1945endmenu 1946 1947menu "Kernel Testing and Coverage" 1948 1949source "lib/kunit/Kconfig" 1950 1951config NOTIFIER_ERROR_INJECTION 1952 tristate "Notifier error injection" 1953 depends on DEBUG_KERNEL 1954 select DEBUG_FS 1955 help 1956 This option provides the ability to inject artificial errors to 1957 specified notifier chain callbacks. It is useful to test the error 1958 handling of notifier call chain failures. 1959 1960 Say N if unsure. 1961 1962config PM_NOTIFIER_ERROR_INJECT 1963 tristate "PM notifier error injection module" 1964 depends on PM && NOTIFIER_ERROR_INJECTION 1965 default m if PM_DEBUG 1966 help 1967 This option provides the ability to inject artificial errors to 1968 PM notifier chain callbacks. It is controlled through debugfs 1969 interface /sys/kernel/debug/notifier-error-inject/pm 1970 1971 If the notifier call chain should be failed with some events 1972 notified, write the error code to "actions/<notifier event>/error". 1973 1974 Example: Inject PM suspend error (-12 = -ENOMEM) 1975 1976 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1977 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1978 # echo mem > /sys/power/state 1979 bash: echo: write error: Cannot allocate memory 1980 1981 To compile this code as a module, choose M here: the module will 1982 be called pm-notifier-error-inject. 1983 1984 If unsure, say N. 1985 1986config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1987 tristate "OF reconfig notifier error injection module" 1988 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1989 help 1990 This option provides the ability to inject artificial errors to 1991 OF reconfig notifier chain callbacks. It is controlled 1992 through debugfs interface under 1993 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1994 1995 If the notifier call chain should be failed with some events 1996 notified, write the error code to "actions/<notifier event>/error". 1997 1998 To compile this code as a module, choose M here: the module will 1999 be called of-reconfig-notifier-error-inject. 2000 2001 If unsure, say N. 2002 2003config NETDEV_NOTIFIER_ERROR_INJECT 2004 tristate "Netdev notifier error injection module" 2005 depends on NET && NOTIFIER_ERROR_INJECTION 2006 help 2007 This option provides the ability to inject artificial errors to 2008 netdevice notifier chain callbacks. It is controlled through debugfs 2009 interface /sys/kernel/debug/notifier-error-inject/netdev 2010 2011 If the notifier call chain should be failed with some events 2012 notified, write the error code to "actions/<notifier event>/error". 2013 2014 Example: Inject netdevice mtu change error (-22 = -EINVAL) 2015 2016 # cd /sys/kernel/debug/notifier-error-inject/netdev 2017 # echo -22 > actions/NETDEV_CHANGEMTU/error 2018 # ip link set eth0 mtu 1024 2019 RTNETLINK answers: Invalid argument 2020 2021 To compile this code as a module, choose M here: the module will 2022 be called netdev-notifier-error-inject. 2023 2024 If unsure, say N. 2025 2026config FUNCTION_ERROR_INJECTION 2027 bool "Fault-injections of functions" 2028 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 2029 help 2030 Add fault injections into various functions that are annotated with 2031 ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return 2032 value of these functions. This is useful to test error paths of code. 2033 2034 If unsure, say N 2035 2036config FAULT_INJECTION 2037 bool "Fault-injection framework" 2038 depends on DEBUG_KERNEL 2039 help 2040 Provide fault-injection framework. 2041 For more details, see Documentation/fault-injection/. 2042 2043config FAILSLAB 2044 bool "Fault-injection capability for kmalloc" 2045 depends on FAULT_INJECTION 2046 help 2047 Provide fault-injection capability for kmalloc. 2048 2049config FAIL_PAGE_ALLOC 2050 bool "Fault-injection capability for alloc_pages()" 2051 depends on FAULT_INJECTION 2052 help 2053 Provide fault-injection capability for alloc_pages(). 2054 2055config FAULT_INJECTION_USERCOPY 2056 bool "Fault injection capability for usercopy functions" 2057 depends on FAULT_INJECTION 2058 help 2059 Provides fault-injection capability to inject failures 2060 in usercopy functions (copy_from_user(), get_user(), ...). 2061 2062config FAIL_MAKE_REQUEST 2063 bool "Fault-injection capability for disk IO" 2064 depends on FAULT_INJECTION && BLOCK 2065 help 2066 Provide fault-injection capability for disk IO. 2067 2068config FAIL_IO_TIMEOUT 2069 bool "Fault-injection capability for faking disk interrupts" 2070 depends on FAULT_INJECTION && BLOCK 2071 help 2072 Provide fault-injection capability on end IO handling. This 2073 will make the block layer "forget" an interrupt as configured, 2074 thus exercising the error handling. 2075 2076 Only works with drivers that use the generic timeout handling, 2077 for others it won't do anything. 2078 2079config FAIL_FUTEX 2080 bool "Fault-injection capability for futexes" 2081 select DEBUG_FS 2082 depends on FAULT_INJECTION && FUTEX 2083 help 2084 Provide fault-injection capability for futexes. 2085 2086config FAULT_INJECTION_DEBUG_FS 2087 bool "Debugfs entries for fault-injection capabilities" 2088 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 2089 help 2090 Enable configuration of fault-injection capabilities via debugfs. 2091 2092config FAIL_FUNCTION 2093 bool "Fault-injection capability for functions" 2094 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 2095 help 2096 Provide function-based fault-injection capability. 2097 This will allow you to override a specific function with a return 2098 with given return value. As a result, function caller will see 2099 an error value and have to handle it. This is useful to test the 2100 error handling in various subsystems. 2101 2102config FAIL_MMC_REQUEST 2103 bool "Fault-injection capability for MMC IO" 2104 depends on FAULT_INJECTION_DEBUG_FS && MMC 2105 help 2106 Provide fault-injection capability for MMC IO. 2107 This will make the mmc core return data errors. This is 2108 useful to test the error handling in the mmc block device 2109 and to test how the mmc host driver handles retries from 2110 the block device. 2111 2112config FAIL_SUNRPC 2113 bool "Fault-injection capability for SunRPC" 2114 depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG 2115 help 2116 Provide fault-injection capability for SunRPC and 2117 its consumers. 2118 2119config FAULT_INJECTION_CONFIGFS 2120 bool "Configfs interface for fault-injection capabilities" 2121 depends on FAULT_INJECTION 2122 select CONFIGFS_FS 2123 help 2124 This option allows configfs-based drivers to dynamically configure 2125 fault-injection via configfs. Each parameter for driver-specific 2126 fault-injection can be made visible as a configfs attribute in a 2127 configfs group. 2128 2129 2130config FAULT_INJECTION_STACKTRACE_FILTER 2131 bool "stacktrace filter for fault-injection capabilities" 2132 depends on FAULT_INJECTION 2133 depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT 2134 select STACKTRACE 2135 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 2136 help 2137 Provide stacktrace filter for fault-injection capabilities 2138 2139config ARCH_HAS_KCOV 2140 bool 2141 help 2142 An architecture should select this when it can successfully 2143 build and run with CONFIG_KCOV. This typically requires 2144 disabling instrumentation for some early boot code. 2145 2146config CC_HAS_SANCOV_TRACE_PC 2147 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 2148 2149 2150config KCOV 2151 bool "Code coverage for fuzzing" 2152 depends on ARCH_HAS_KCOV 2153 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 2154 depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \ 2155 GCC_VERSION >= 120000 || CC_IS_CLANG 2156 select DEBUG_FS 2157 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 2158 select OBJTOOL if HAVE_NOINSTR_HACK 2159 help 2160 KCOV exposes kernel code coverage information in a form suitable 2161 for coverage-guided fuzzing (randomized testing). 2162 2163 For more details, see Documentation/dev-tools/kcov.rst. 2164 2165config KCOV_ENABLE_COMPARISONS 2166 bool "Enable comparison operands collection by KCOV" 2167 depends on KCOV 2168 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 2169 help 2170 KCOV also exposes operands of every comparison in the instrumented 2171 code along with operand sizes and PCs of the comparison instructions. 2172 These operands can be used by fuzzing engines to improve the quality 2173 of fuzzing coverage. 2174 2175config KCOV_INSTRUMENT_ALL 2176 bool "Instrument all code by default" 2177 depends on KCOV 2178 default y 2179 help 2180 If you are doing generic system call fuzzing (like e.g. syzkaller), 2181 then you will want to instrument the whole kernel and you should 2182 say y here. If you are doing more targeted fuzzing (like e.g. 2183 filesystem fuzzing with AFL) then you will want to enable coverage 2184 for more specific subsets of files, and should say n here. 2185 2186config KCOV_IRQ_AREA_SIZE 2187 hex "Size of interrupt coverage collection area in words" 2188 depends on KCOV 2189 default 0x40000 2190 help 2191 KCOV uses preallocated per-cpu areas to collect coverage from 2192 soft interrupts. This specifies the size of those areas in the 2193 number of unsigned long words. 2194 2195config KCOV_SELFTEST 2196 bool "Perform short selftests on boot" 2197 depends on KCOV 2198 help 2199 Run short KCOV coverage collection selftests on boot. 2200 On test failure, causes the kernel to panic. Recommended to be 2201 enabled, ensuring critical functionality works as intended. 2202 2203menuconfig RUNTIME_TESTING_MENU 2204 bool "Runtime Testing" 2205 default y 2206 2207if RUNTIME_TESTING_MENU 2208 2209config TEST_DHRY 2210 tristate "Dhrystone benchmark test" 2211 help 2212 Enable this to include the Dhrystone 2.1 benchmark. This test 2213 calculates the number of Dhrystones per second, and the number of 2214 DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided 2215 by 1757 (the number of Dhrystones per second obtained on the VAX 2216 11/780, nominally a 1 MIPS machine). 2217 2218 To run the benchmark, it needs to be enabled explicitly, either from 2219 the kernel command line (when built-in), or from userspace (when 2220 built-in or modular). 2221 2222 Run once during kernel boot: 2223 2224 test_dhry.run 2225 2226 Set number of iterations from kernel command line: 2227 2228 test_dhry.iterations=<n> 2229 2230 Set number of iterations from userspace: 2231 2232 echo <n> > /sys/module/test_dhry/parameters/iterations 2233 2234 Trigger manual run from userspace: 2235 2236 echo y > /sys/module/test_dhry/parameters/run 2237 2238 If the number of iterations is <= 0, the test will devise a suitable 2239 number of iterations (test runs for at least 2s) automatically. 2240 This process takes ca. 4s. 2241 2242 If unsure, say N. 2243 2244config LKDTM 2245 tristate "Linux Kernel Dump Test Tool Module" 2246 depends on DEBUG_FS 2247 help 2248 This module enables testing of the different dumping mechanisms by 2249 inducing system failures at predefined crash points. 2250 If you don't need it: say N 2251 Choose M here to compile this code as a module. The module will be 2252 called lkdtm. 2253 2254 Documentation on how to use the module can be found in 2255 Documentation/fault-injection/provoke-crashes.rst 2256 2257config CPUMASK_KUNIT_TEST 2258 tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS 2259 depends on KUNIT 2260 default KUNIT_ALL_TESTS 2261 help 2262 Enable to turn on cpumask tests, running at boot or module load time. 2263 2264 For more information on KUnit and unit tests in general, please refer 2265 to the KUnit documentation in Documentation/dev-tools/kunit/. 2266 2267 If unsure, say N. 2268 2269config TEST_LIST_SORT 2270 tristate "Linked list sorting test" if !KUNIT_ALL_TESTS 2271 depends on KUNIT 2272 default KUNIT_ALL_TESTS 2273 help 2274 Enable this to turn on 'list_sort()' function test. This test is 2275 executed only once during system boot (so affects only boot time), 2276 or at module load time. 2277 2278 If unsure, say N. 2279 2280config TEST_MIN_HEAP 2281 tristate "Min heap test" 2282 depends on DEBUG_KERNEL || m 2283 help 2284 Enable this to turn on min heap function tests. This test is 2285 executed only once during system boot (so affects only boot time), 2286 or at module load time. 2287 2288 If unsure, say N. 2289 2290config TEST_SORT 2291 tristate "Array-based sort test" if !KUNIT_ALL_TESTS 2292 depends on KUNIT 2293 default KUNIT_ALL_TESTS 2294 help 2295 This option enables the self-test function of 'sort()' at boot, 2296 or at module load time. 2297 2298 If unsure, say N. 2299 2300config TEST_DIV64 2301 tristate "64bit/32bit division and modulo test" 2302 depends on DEBUG_KERNEL || m 2303 help 2304 Enable this to turn on 'do_div()' function test. This test is 2305 executed only once during system boot (so affects only boot time), 2306 or at module load time. 2307 2308 If unsure, say N. 2309 2310config TEST_MULDIV64 2311 tristate "mul_u64_u64_div_u64() test" 2312 depends on DEBUG_KERNEL || m 2313 help 2314 Enable this to turn on 'mul_u64_u64_div_u64()' function test. 2315 This test is executed only once during system boot (so affects 2316 only boot time), or at module load time. 2317 2318 If unsure, say N. 2319 2320config TEST_IOV_ITER 2321 tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS 2322 depends on KUNIT 2323 depends on MMU 2324 default KUNIT_ALL_TESTS 2325 help 2326 Enable this to turn on testing of the operation of the I/O iterator 2327 (iov_iter). This test is executed only once during system boot (so 2328 affects only boot time), or at module load time. 2329 2330 If unsure, say N. 2331 2332config KPROBES_SANITY_TEST 2333 tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS 2334 depends on DEBUG_KERNEL 2335 depends on KPROBES 2336 depends on KUNIT 2337 select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 2338 default KUNIT_ALL_TESTS 2339 help 2340 This option provides for testing basic kprobes functionality on 2341 boot. Samples of kprobe and kretprobe are inserted and 2342 verified for functionality. 2343 2344 Say N if you are unsure. 2345 2346config FPROBE_SANITY_TEST 2347 bool "Self test for fprobe" 2348 depends on DEBUG_KERNEL 2349 depends on FPROBE 2350 depends on KUNIT=y 2351 help 2352 This option will enable testing the fprobe when the system boot. 2353 A series of tests are made to verify that the fprobe is functioning 2354 properly. 2355 2356 Say N if you are unsure. 2357 2358config BACKTRACE_SELF_TEST 2359 tristate "Self test for the backtrace code" 2360 depends on DEBUG_KERNEL 2361 help 2362 This option provides a kernel module that can be used to test 2363 the kernel stack backtrace code. This option is not useful 2364 for distributions or general kernels, but only for kernel 2365 developers working on architecture code. 2366 2367 Note that if you want to also test saved backtraces, you will 2368 have to enable STACKTRACE as well. 2369 2370 Say N if you are unsure. 2371 2372config TEST_REF_TRACKER 2373 tristate "Self test for reference tracker" 2374 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT 2375 select REF_TRACKER 2376 help 2377 This option provides a kernel module performing tests 2378 using reference tracker infrastructure. 2379 2380 Say N if you are unsure. 2381 2382config RBTREE_TEST 2383 tristate "Red-Black tree test" 2384 depends on DEBUG_KERNEL 2385 help 2386 A benchmark measuring the performance of the rbtree library. 2387 Also includes rbtree invariant checks. 2388 2389config REED_SOLOMON_TEST 2390 tristate "Reed-Solomon library test" 2391 depends on DEBUG_KERNEL || m 2392 select REED_SOLOMON 2393 select REED_SOLOMON_ENC16 2394 select REED_SOLOMON_DEC16 2395 help 2396 This option enables the self-test function of rslib at boot, 2397 or at module load time. 2398 2399 If unsure, say N. 2400 2401config INTERVAL_TREE_TEST 2402 tristate "Interval tree test" 2403 depends on DEBUG_KERNEL 2404 select INTERVAL_TREE 2405 help 2406 A benchmark measuring the performance of the interval tree library 2407 2408config PERCPU_TEST 2409 tristate "Per cpu operations test" 2410 depends on m && DEBUG_KERNEL 2411 help 2412 Enable this option to build test module which validates per-cpu 2413 operations. 2414 2415 If unsure, say N. 2416 2417config ATOMIC64_SELFTEST 2418 tristate "Perform an atomic64_t self-test" 2419 help 2420 Enable this option to test the atomic64_t functions at boot or 2421 at module load time. 2422 2423 If unsure, say N. 2424 2425config ASYNC_RAID6_TEST 2426 tristate "Self test for hardware accelerated raid6 recovery" 2427 depends on ASYNC_RAID6_RECOV 2428 select ASYNC_MEMCPY 2429 help 2430 This is a one-shot self test that permutes through the 2431 recovery of all the possible two disk failure scenarios for a 2432 N-disk array. Recovery is performed with the asynchronous 2433 raid6 recovery routines, and will optionally use an offload 2434 engine if one is available. 2435 2436 If unsure, say N. 2437 2438config TEST_HEXDUMP 2439 tristate "Test functions located in the hexdump module at runtime" 2440 2441config STRING_KUNIT_TEST 2442 tristate "KUnit test string functions at runtime" if !KUNIT_ALL_TESTS 2443 depends on KUNIT 2444 default KUNIT_ALL_TESTS 2445 2446config STRING_HELPERS_KUNIT_TEST 2447 tristate "KUnit test string helpers at runtime" if !KUNIT_ALL_TESTS 2448 depends on KUNIT 2449 default KUNIT_ALL_TESTS 2450 2451config TEST_KSTRTOX 2452 tristate "Test kstrto*() family of functions at runtime" 2453 2454config TEST_PRINTF 2455 tristate "Test printf() family of functions at runtime" 2456 2457config TEST_SCANF 2458 tristate "Test scanf() family of functions at runtime" 2459 2460config TEST_BITMAP 2461 tristate "Test bitmap_*() family of functions at runtime" 2462 help 2463 Enable this option to test the bitmap functions at boot. 2464 2465 If unsure, say N. 2466 2467config TEST_UUID 2468 tristate "Test functions located in the uuid module at runtime" 2469 2470config TEST_XARRAY 2471 tristate "Test the XArray code at runtime" 2472 2473config TEST_MAPLE_TREE 2474 tristate "Test the Maple Tree code at runtime or module load" 2475 help 2476 Enable this option to test the maple tree code functions at boot, or 2477 when the module is loaded. Enable "Debug Maple Trees" will enable 2478 more verbose output on failures. 2479 2480 If unsure, say N. 2481 2482config TEST_RHASHTABLE 2483 tristate "Perform selftest on resizable hash table" 2484 help 2485 Enable this option to test the rhashtable functions at boot. 2486 2487 If unsure, say N. 2488 2489config TEST_IDA 2490 tristate "Perform selftest on IDA functions" 2491 2492config TEST_PARMAN 2493 tristate "Perform selftest on priority array manager" 2494 depends on PARMAN 2495 help 2496 Enable this option to test priority array manager on boot 2497 (or module load). 2498 2499 If unsure, say N. 2500 2501config TEST_IRQ_TIMINGS 2502 bool "IRQ timings selftest" 2503 depends on IRQ_TIMINGS 2504 help 2505 Enable this option to test the irq timings code on boot. 2506 2507 If unsure, say N. 2508 2509config TEST_LKM 2510 tristate "Test module loading with 'hello world' module" 2511 depends on m 2512 help 2513 This builds the "test_module" module that emits "Hello, world" 2514 on printk when loaded. It is designed to be used for basic 2515 evaluation of the module loading subsystem (for example when 2516 validating module verification). It lacks any extra dependencies, 2517 and will not normally be loaded by the system unless explicitly 2518 requested by name. 2519 2520 If unsure, say N. 2521 2522config TEST_BITOPS 2523 tristate "Test module for compilation of bitops operations" 2524 help 2525 This builds the "test_bitops" module that is much like the 2526 TEST_LKM module except that it does a basic exercise of the 2527 set/clear_bit macros and get_count_order/long to make sure there are 2528 no compiler warnings from C=1 sparse checker or -Wextra 2529 compilations. It has no dependencies and doesn't run or load unless 2530 explicitly requested by name. for example: modprobe test_bitops. 2531 2532 If unsure, say N. 2533 2534config TEST_VMALLOC 2535 tristate "Test module for stress/performance analysis of vmalloc allocator" 2536 default n 2537 depends on MMU 2538 depends on m 2539 help 2540 This builds the "test_vmalloc" module that should be used for 2541 stress and performance analysis. So, any new change for vmalloc 2542 subsystem can be evaluated from performance and stability point 2543 of view. 2544 2545 If unsure, say N. 2546 2547config TEST_BPF 2548 tristate "Test BPF filter functionality" 2549 depends on m && NET 2550 help 2551 This builds the "test_bpf" module that runs various test vectors 2552 against the BPF interpreter or BPF JIT compiler depending on the 2553 current setting. This is in particular useful for BPF JIT compiler 2554 development, but also to run regression tests against changes in 2555 the interpreter code. It also enables test stubs for eBPF maps and 2556 verifier used by user space verifier testsuite. 2557 2558 If unsure, say N. 2559 2560config TEST_BLACKHOLE_DEV 2561 tristate "Test blackhole netdev functionality" 2562 depends on m && NET 2563 help 2564 This builds the "test_blackhole_dev" module that validates the 2565 data path through this blackhole netdev. 2566 2567 If unsure, say N. 2568 2569config FIND_BIT_BENCHMARK 2570 tristate "Test find_bit functions" 2571 help 2572 This builds the "test_find_bit" module that measure find_*_bit() 2573 functions performance. 2574 2575 If unsure, say N. 2576 2577config TEST_FIRMWARE 2578 tristate "Test firmware loading via userspace interface" 2579 depends on FW_LOADER 2580 help 2581 This builds the "test_firmware" module that creates a userspace 2582 interface for testing firmware loading. This can be used to 2583 control the triggering of firmware loading without needing an 2584 actual firmware-using device. The contents can be rechecked by 2585 userspace. 2586 2587 If unsure, say N. 2588 2589config TEST_SYSCTL 2590 tristate "sysctl test driver" 2591 depends on PROC_SYSCTL 2592 help 2593 This builds the "test_sysctl" module. This driver enables to test the 2594 proc sysctl interfaces available to drivers safely without affecting 2595 production knobs which might alter system functionality. 2596 2597 If unsure, say N. 2598 2599config BITFIELD_KUNIT 2600 tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS 2601 depends on KUNIT 2602 default KUNIT_ALL_TESTS 2603 help 2604 Enable this option to test the bitfield functions at boot. 2605 2606 KUnit tests run during boot and output the results to the debug log 2607 in TAP format (http://testanything.org/). Only useful for kernel devs 2608 running the KUnit test harness, and not intended for inclusion into a 2609 production build. 2610 2611 For more information on KUnit and unit tests in general please refer 2612 to the KUnit documentation in Documentation/dev-tools/kunit/. 2613 2614 If unsure, say N. 2615 2616config CHECKSUM_KUNIT 2617 tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS 2618 depends on KUNIT 2619 default KUNIT_ALL_TESTS 2620 help 2621 Enable this option to test the checksum functions at boot. 2622 2623 KUnit tests run during boot and output the results to the debug log 2624 in TAP format (http://testanything.org/). Only useful for kernel devs 2625 running the KUnit test harness, and not intended for inclusion into a 2626 production build. 2627 2628 For more information on KUnit and unit tests in general please refer 2629 to the KUnit documentation in Documentation/dev-tools/kunit/. 2630 2631 If unsure, say N. 2632 2633config HASH_KUNIT_TEST 2634 tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS 2635 depends on KUNIT 2636 default KUNIT_ALL_TESTS 2637 help 2638 Enable this option to test the kernel's string (<linux/stringhash.h>), and 2639 integer (<linux/hash.h>) hash functions on boot. 2640 2641 KUnit tests run during boot and output the results to the debug log 2642 in TAP format (https://testanything.org/). Only useful for kernel devs 2643 running the KUnit test harness, and not intended for inclusion into a 2644 production build. 2645 2646 For more information on KUnit and unit tests in general please refer 2647 to the KUnit documentation in Documentation/dev-tools/kunit/. 2648 2649 This is intended to help people writing architecture-specific 2650 optimized versions. If unsure, say N. 2651 2652config RESOURCE_KUNIT_TEST 2653 tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS 2654 depends on KUNIT 2655 default KUNIT_ALL_TESTS 2656 select GET_FREE_REGION 2657 help 2658 This builds the resource API unit test. 2659 Tests the logic of API provided by resource.c and ioport.h. 2660 For more information on KUnit and unit tests in general please refer 2661 to the KUnit documentation in Documentation/dev-tools/kunit/. 2662 2663 If unsure, say N. 2664 2665config SYSCTL_KUNIT_TEST 2666 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS 2667 depends on KUNIT 2668 default KUNIT_ALL_TESTS 2669 help 2670 This builds the proc sysctl unit test, which runs on boot. 2671 Tests the API contract and implementation correctness of sysctl. 2672 For more information on KUnit and unit tests in general please refer 2673 to the KUnit documentation in Documentation/dev-tools/kunit/. 2674 2675 If unsure, say N. 2676 2677config LIST_KUNIT_TEST 2678 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS 2679 depends on KUNIT 2680 default KUNIT_ALL_TESTS 2681 help 2682 This builds the linked list KUnit test suite. 2683 It tests that the API and basic functionality of the list_head type 2684 and associated macros. 2685 2686 KUnit tests run during boot and output the results to the debug log 2687 in TAP format (https://testanything.org/). Only useful for kernel devs 2688 running the KUnit test harness, and not intended for inclusion into a 2689 production build. 2690 2691 For more information on KUnit and unit tests in general please refer 2692 to the KUnit documentation in Documentation/dev-tools/kunit/. 2693 2694 If unsure, say N. 2695 2696config HASHTABLE_KUNIT_TEST 2697 tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS 2698 depends on KUNIT 2699 default KUNIT_ALL_TESTS 2700 help 2701 This builds the hashtable KUnit test suite. 2702 It tests the basic functionality of the API defined in 2703 include/linux/hashtable.h. For more information on KUnit and 2704 unit tests in general please refer to the KUnit documentation 2705 in Documentation/dev-tools/kunit/. 2706 2707 If unsure, say N. 2708 2709config LINEAR_RANGES_TEST 2710 tristate "KUnit test for linear_ranges" 2711 depends on KUNIT 2712 select LINEAR_RANGES 2713 help 2714 This builds the linear_ranges unit test, which runs on boot. 2715 Tests the linear_ranges logic correctness. 2716 For more information on KUnit and unit tests in general please refer 2717 to the KUnit documentation in Documentation/dev-tools/kunit/. 2718 2719 If unsure, say N. 2720 2721config CMDLINE_KUNIT_TEST 2722 tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS 2723 depends on KUNIT 2724 default KUNIT_ALL_TESTS 2725 help 2726 This builds the cmdline API unit test. 2727 Tests the logic of API provided by cmdline.c. 2728 For more information on KUnit and unit tests in general please refer 2729 to the KUnit documentation in Documentation/dev-tools/kunit/. 2730 2731 If unsure, say N. 2732 2733config BITS_TEST 2734 tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS 2735 depends on KUNIT 2736 default KUNIT_ALL_TESTS 2737 help 2738 This builds the bits unit test. 2739 Tests the logic of macros defined in bits.h. 2740 For more information on KUnit and unit tests in general please refer 2741 to the KUnit documentation in Documentation/dev-tools/kunit/. 2742 2743 If unsure, say N. 2744 2745config SLUB_KUNIT_TEST 2746 tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS 2747 depends on SLUB_DEBUG && KUNIT 2748 default KUNIT_ALL_TESTS 2749 help 2750 This builds SLUB allocator unit test. 2751 Tests SLUB cache debugging functionality. 2752 For more information on KUnit and unit tests in general please refer 2753 to the KUnit documentation in Documentation/dev-tools/kunit/. 2754 2755 If unsure, say N. 2756 2757config RATIONAL_KUNIT_TEST 2758 tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS 2759 depends on KUNIT && RATIONAL 2760 default KUNIT_ALL_TESTS 2761 help 2762 This builds the rational math unit test. 2763 For more information on KUnit and unit tests in general please refer 2764 to the KUnit documentation in Documentation/dev-tools/kunit/. 2765 2766 If unsure, say N. 2767 2768config MEMCPY_KUNIT_TEST 2769 tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS 2770 depends on KUNIT 2771 default KUNIT_ALL_TESTS 2772 help 2773 Builds unit tests for memcpy(), memmove(), and memset() functions. 2774 For more information on KUnit and unit tests in general please refer 2775 to the KUnit documentation in Documentation/dev-tools/kunit/. 2776 2777 If unsure, say N. 2778 2779config IS_SIGNED_TYPE_KUNIT_TEST 2780 tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS 2781 depends on KUNIT 2782 default KUNIT_ALL_TESTS 2783 help 2784 Builds unit tests for the is_signed_type() macro. 2785 2786 For more information on KUnit and unit tests in general please refer 2787 to the KUnit documentation in Documentation/dev-tools/kunit/. 2788 2789 If unsure, say N. 2790 2791config OVERFLOW_KUNIT_TEST 2792 tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS 2793 depends on KUNIT 2794 default KUNIT_ALL_TESTS 2795 help 2796 Builds unit tests for the check_*_overflow(), size_*(), allocation, and 2797 related functions. 2798 2799 For more information on KUnit and unit tests in general please refer 2800 to the KUnit documentation in Documentation/dev-tools/kunit/. 2801 2802 If unsure, say N. 2803 2804config STACKINIT_KUNIT_TEST 2805 tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS 2806 depends on KUNIT 2807 default KUNIT_ALL_TESTS 2808 help 2809 Test if the kernel is zero-initializing stack variables and 2810 padding. Coverage is controlled by compiler flags, 2811 CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO, 2812 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2813 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2814 2815config FORTIFY_KUNIT_TEST 2816 tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS 2817 depends on KUNIT 2818 default KUNIT_ALL_TESTS 2819 help 2820 Builds unit tests for checking internals of FORTIFY_SOURCE as used 2821 by the str*() and mem*() family of functions. For testing runtime 2822 traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests. 2823 2824config HW_BREAKPOINT_KUNIT_TEST 2825 bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS 2826 depends on HAVE_HW_BREAKPOINT 2827 depends on KUNIT=y 2828 default KUNIT_ALL_TESTS 2829 help 2830 Tests for hw_breakpoint constraints accounting. 2831 2832 If unsure, say N. 2833 2834config SIPHASH_KUNIT_TEST 2835 tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS 2836 depends on KUNIT 2837 default KUNIT_ALL_TESTS 2838 help 2839 Enable this option to test the kernel's siphash (<linux/siphash.h>) hash 2840 functions on boot (or module load). 2841 2842 This is intended to help people writing architecture-specific 2843 optimized versions. If unsure, say N. 2844 2845config USERCOPY_KUNIT_TEST 2846 tristate "KUnit Test for user/kernel boundary protections" 2847 depends on KUNIT 2848 default KUNIT_ALL_TESTS 2849 help 2850 This builds the "usercopy_kunit" module that runs sanity checks 2851 on the copy_to/from_user infrastructure, making sure basic 2852 user/kernel boundary testing is working. 2853 2854config TEST_UDELAY 2855 tristate "udelay test driver" 2856 help 2857 This builds the "udelay_test" module that helps to make sure 2858 that udelay() is working properly. 2859 2860 If unsure, say N. 2861 2862config TEST_STATIC_KEYS 2863 tristate "Test static keys" 2864 depends on m 2865 help 2866 Test the static key interfaces. 2867 2868 If unsure, say N. 2869 2870config TEST_DYNAMIC_DEBUG 2871 tristate "Test DYNAMIC_DEBUG" 2872 depends on DYNAMIC_DEBUG 2873 help 2874 This module registers a tracer callback to count enabled 2875 pr_debugs in a 'do_debugging' function, then alters their 2876 enablements, calls the function, and compares counts. 2877 2878 If unsure, say N. 2879 2880config TEST_KMOD 2881 tristate "kmod stress tester" 2882 depends on m 2883 depends on NETDEVICES && NET_CORE && INET # for TUN 2884 depends on BLOCK 2885 depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS 2886 select TEST_LKM 2887 select XFS_FS 2888 select TUN 2889 select BTRFS_FS 2890 help 2891 Test the kernel's module loading mechanism: kmod. kmod implements 2892 support to load modules using the Linux kernel's usermode helper. 2893 This test provides a series of tests against kmod. 2894 2895 Although technically you can either build test_kmod as a module or 2896 into the kernel we disallow building it into the kernel since 2897 it stress tests request_module() and this will very likely cause 2898 some issues by taking over precious threads available from other 2899 module load requests, ultimately this could be fatal. 2900 2901 To run tests run: 2902 2903 tools/testing/selftests/kmod/kmod.sh --help 2904 2905 If unsure, say N. 2906 2907config TEST_DEBUG_VIRTUAL 2908 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 2909 depends on DEBUG_VIRTUAL 2910 help 2911 Test the kernel's ability to detect incorrect calls to 2912 virt_to_phys() done against the non-linear part of the 2913 kernel's virtual address map. 2914 2915 If unsure, say N. 2916 2917config TEST_MEMCAT_P 2918 tristate "Test memcat_p() helper function" 2919 help 2920 Test the memcat_p() helper for correctly merging two 2921 pointer arrays together. 2922 2923 If unsure, say N. 2924 2925config TEST_OBJAGG 2926 tristate "Perform selftest on object aggreration manager" 2927 default n 2928 depends on OBJAGG 2929 help 2930 Enable this option to test object aggregation manager on boot 2931 (or module load). 2932 2933config TEST_MEMINIT 2934 tristate "Test heap/page initialization" 2935 help 2936 Test if the kernel is zero-initializing heap and page allocations. 2937 This can be useful to test init_on_alloc and init_on_free features. 2938 2939 If unsure, say N. 2940 2941config TEST_HMM 2942 tristate "Test HMM (Heterogeneous Memory Management)" 2943 depends on TRANSPARENT_HUGEPAGE 2944 depends on DEVICE_PRIVATE 2945 select HMM_MIRROR 2946 select MMU_NOTIFIER 2947 help 2948 This is a pseudo device driver solely for testing HMM. 2949 Say M here if you want to build the HMM test module. 2950 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests. 2951 2952 If unsure, say N. 2953 2954config TEST_FREE_PAGES 2955 tristate "Test freeing pages" 2956 help 2957 Test that a memory leak does not occur due to a race between 2958 freeing a block of pages and a speculative page reference. 2959 Loading this module is safe if your kernel has the bug fixed. 2960 If the bug is not fixed, it will leak gigabytes of memory and 2961 probably OOM your system. 2962 2963config TEST_FPU 2964 tristate "Test floating point operations in kernel space" 2965 depends on ARCH_HAS_KERNEL_FPU_SUPPORT && !KCOV_INSTRUMENT_ALL 2966 help 2967 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu 2968 which will trigger a sequence of floating point operations. This is used 2969 for self-testing floating point control register setting in 2970 kernel_fpu_begin(). 2971 2972 If unsure, say N. 2973 2974config TEST_CLOCKSOURCE_WATCHDOG 2975 tristate "Test clocksource watchdog in kernel space" 2976 depends on CLOCKSOURCE_WATCHDOG 2977 help 2978 Enable this option to create a kernel module that will trigger 2979 a test of the clocksource watchdog. This module may be loaded 2980 via modprobe or insmod in which case it will run upon being 2981 loaded, or it may be built in, in which case it will run 2982 shortly after boot. 2983 2984 If unsure, say N. 2985 2986config TEST_OBJPOOL 2987 tristate "Test module for correctness and stress of objpool" 2988 default n 2989 depends on m && DEBUG_KERNEL 2990 help 2991 This builds the "test_objpool" module that should be used for 2992 correctness verification and concurrent testings of objects 2993 allocation and reclamation. 2994 2995 If unsure, say N. 2996 2997endif # RUNTIME_TESTING_MENU 2998 2999config ARCH_USE_MEMTEST 3000 bool 3001 help 3002 An architecture should select this when it uses early_memtest() 3003 during boot process. 3004 3005config MEMTEST 3006 bool "Memtest" 3007 depends on ARCH_USE_MEMTEST 3008 help 3009 This option adds a kernel parameter 'memtest', which allows memtest 3010 to be set and executed. 3011 memtest=0, mean disabled; -- default 3012 memtest=1, mean do 1 test pattern; 3013 ... 3014 memtest=17, mean do 17 test patterns. 3015 If you are unsure how to answer this question, answer N. 3016 3017 3018 3019config HYPERV_TESTING 3020 bool "Microsoft Hyper-V driver testing" 3021 default n 3022 depends on HYPERV && DEBUG_FS 3023 help 3024 Select this option to enable Hyper-V vmbus testing. 3025 3026endmenu # "Kernel Testing and Coverage" 3027 3028menu "Rust hacking" 3029 3030config RUST_DEBUG_ASSERTIONS 3031 bool "Debug assertions" 3032 depends on RUST 3033 help 3034 Enables rustc's `-Cdebug-assertions` codegen option. 3035 3036 This flag lets you turn `cfg(debug_assertions)` conditional 3037 compilation on or off. This can be used to enable extra debugging 3038 code in development but not in production. For example, it controls 3039 the behavior of the standard library's `debug_assert!` macro. 3040 3041 Note that this will apply to all Rust code, including `core`. 3042 3043 If unsure, say N. 3044 3045config RUST_OVERFLOW_CHECKS 3046 bool "Overflow checks" 3047 default y 3048 depends on RUST 3049 help 3050 Enables rustc's `-Coverflow-checks` codegen option. 3051 3052 This flag allows you to control the behavior of runtime integer 3053 overflow. When overflow-checks are enabled, a Rust panic will occur 3054 on overflow. 3055 3056 Note that this will apply to all Rust code, including `core`. 3057 3058 If unsure, say Y. 3059 3060config RUST_BUILD_ASSERT_ALLOW 3061 bool "Allow unoptimized build-time assertions" 3062 depends on RUST 3063 help 3064 Controls how `build_error!` and `build_assert!` are handled during the build. 3065 3066 If calls to them exist in the binary, it may indicate a violated invariant 3067 or that the optimizer failed to verify the invariant during compilation. 3068 3069 This should not happen, thus by default the build is aborted. However, 3070 as an escape hatch, you can choose Y here to ignore them during build 3071 and let the check be carried at runtime (with `panic!` being called if 3072 the check fails). 3073 3074 If unsure, say N. 3075 3076config RUST_KERNEL_DOCTESTS 3077 bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS 3078 depends on RUST && KUNIT=y 3079 default KUNIT_ALL_TESTS 3080 help 3081 This builds the documentation tests of the `kernel` crate 3082 as KUnit tests. 3083 3084 For more information on KUnit and unit tests in general, 3085 please refer to the KUnit documentation in Documentation/dev-tools/kunit/. 3086 3087 If unsure, say N. 3088 3089endmenu # "Rust" 3090 3091endmenu # Kernel hacking 3092 3093config INT_POW_TEST 3094 tristate "Integer exponentiation (int_pow) test" if !KUNIT_ALL_TESTS 3095 depends on KUNIT 3096 default KUNIT_ALL_TESTS 3097 help 3098 This option enables the KUnit test suite for the int_pow function, 3099 which performs integer exponentiation. The test suite is designed to 3100 verify that the implementation of int_pow correctly computes the power 3101 of a given base raised to a given exponent. 3102 3103 Enabling this option will include tests that check various scenarios 3104 and edge cases to ensure the accuracy and reliability of the exponentiation 3105 function. 3106 3107 If unsure, say N 3108