1# SPDX-License-Identifier: GPL-2.0-only 2menu "Kernel hacking" 3 4menu "printk and dmesg options" 5 6config PRINTK_TIME 7 bool "Show timing information on printks" 8 depends on PRINTK 9 help 10 Selecting this option causes time stamps of the printk() 11 messages to be added to the output of the syslog() system 12 call and at the console. 13 14 The timestamp is always recorded internally, and exported 15 to /dev/kmsg. This flag just specifies if the timestamp should 16 be included, not that the timestamp is recorded. 17 18 The behavior is also controlled by the kernel command line 19 parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst 20 21config PRINTK_CALLER 22 bool "Show caller information on printks" 23 depends on PRINTK 24 help 25 Selecting this option causes printk() to add a caller "thread id" (if 26 in task context) or a caller "processor id" (if not in task context) 27 to every message. 28 29 This option is intended for environments where multiple threads 30 concurrently call printk() for many times, for it is difficult to 31 interpret without knowing where these lines (or sometimes individual 32 line which was divided into multiple lines due to race) came from. 33 34 Since toggling after boot makes the code racy, currently there is 35 no option to enable/disable at the kernel command line parameter or 36 sysfs interface. 37 38config STACKTRACE_BUILD_ID 39 bool "Show build ID information in stacktraces" 40 depends on PRINTK 41 help 42 Selecting this option adds build ID information for symbols in 43 stacktraces printed with the printk format '%p[SR]b'. 44 45 This option is intended for distros where debuginfo is not easily 46 accessible but can be downloaded given the build ID of the vmlinux or 47 kernel module where the function is located. 48 49config CONSOLE_LOGLEVEL_DEFAULT 50 int "Default console loglevel (1-15)" 51 range 1 15 52 default "7" 53 help 54 Default loglevel to determine what will be printed on the console. 55 56 Setting a default here is equivalent to passing in loglevel=<x> in 57 the kernel bootargs. loglevel=<x> continues to override whatever 58 value is specified here as well. 59 60 Note: This does not affect the log level of un-prefixed printk() 61 usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT 62 option. 63 64config CONSOLE_LOGLEVEL_QUIET 65 int "quiet console loglevel (1-15)" 66 range 1 15 67 default "4" 68 help 69 loglevel to use when "quiet" is passed on the kernel commandline. 70 71 When "quiet" is passed on the kernel commandline this loglevel 72 will be used as the loglevel. IOW passing "quiet" will be the 73 equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>" 74 75config MESSAGE_LOGLEVEL_DEFAULT 76 int "Default message log level (1-7)" 77 range 1 7 78 default "4" 79 help 80 Default log level for printk statements with no specified priority. 81 82 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks 83 that are auditing their logs closely may want to set it to a lower 84 priority. 85 86 Note: This does not affect what message level gets printed on the console 87 by default. To change that, use loglevel=<x> in the kernel bootargs, 88 or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value. 89 90config BOOT_PRINTK_DELAY 91 bool "Delay each boot printk message by N milliseconds" 92 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY 93 help 94 This build option allows you to read kernel boot messages 95 by inserting a short delay after each one. The delay is 96 specified in milliseconds on the kernel command line, 97 using "boot_delay=N". 98 99 It is likely that you would also need to use "lpj=M" to preset 100 the "loops per jiffy" value. 101 See a previous boot log for the "lpj" value to use for your 102 system, and then set "lpj=M" before setting "boot_delay=N". 103 NOTE: Using this option may adversely affect SMP systems. 104 I.e., processors other than the first one may not boot up. 105 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect 106 what it believes to be lockup conditions. 107 108config DYNAMIC_DEBUG 109 bool "Enable dynamic printk() support" 110 default n 111 depends on PRINTK 112 depends on (DEBUG_FS || PROC_FS) 113 select DYNAMIC_DEBUG_CORE 114 help 115 116 Compiles debug level messages into the kernel, which would not 117 otherwise be available at runtime. These messages can then be 118 enabled/disabled based on various levels of scope - per source file, 119 function, module, format string, and line number. This mechanism 120 implicitly compiles in all pr_debug() and dev_dbg() calls, which 121 enlarges the kernel text size by about 2%. 122 123 If a source file is compiled with DEBUG flag set, any 124 pr_debug() calls in it are enabled by default, but can be 125 disabled at runtime as below. Note that DEBUG flag is 126 turned on by many CONFIG_*DEBUG* options. 127 128 Usage: 129 130 Dynamic debugging is controlled via the 'dynamic_debug/control' file, 131 which is contained in the 'debugfs' filesystem or procfs. 132 Thus, the debugfs or procfs filesystem must first be mounted before 133 making use of this feature. 134 We refer the control file as: <debugfs>/dynamic_debug/control. This 135 file contains a list of the debug statements that can be enabled. The 136 format for each line of the file is: 137 138 filename:lineno [module]function flags format 139 140 filename : source file of the debug statement 141 lineno : line number of the debug statement 142 module : module that contains the debug statement 143 function : function that contains the debug statement 144 flags : '=p' means the line is turned 'on' for printing 145 format : the format used for the debug statement 146 147 From a live system: 148 149 nullarbor:~ # cat <debugfs>/dynamic_debug/control 150 # filename:lineno [module]function flags format 151 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012" 152 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012" 153 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012" 154 155 Example usage: 156 157 // enable the message at line 1603 of file svcsock.c 158 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' > 159 <debugfs>/dynamic_debug/control 160 161 // enable all the messages in file svcsock.c 162 nullarbor:~ # echo -n 'file svcsock.c +p' > 163 <debugfs>/dynamic_debug/control 164 165 // enable all the messages in the NFS server module 166 nullarbor:~ # echo -n 'module nfsd +p' > 167 <debugfs>/dynamic_debug/control 168 169 // enable all 12 messages in the function svc_process() 170 nullarbor:~ # echo -n 'func svc_process +p' > 171 <debugfs>/dynamic_debug/control 172 173 // disable all 12 messages in the function svc_process() 174 nullarbor:~ # echo -n 'func svc_process -p' > 175 <debugfs>/dynamic_debug/control 176 177 See Documentation/admin-guide/dynamic-debug-howto.rst for additional 178 information. 179 180config DYNAMIC_DEBUG_CORE 181 bool "Enable core function of dynamic debug support" 182 depends on PRINTK 183 depends on (DEBUG_FS || PROC_FS) 184 help 185 Enable core functional support of dynamic debug. It is useful 186 when you want to tie dynamic debug to your kernel modules with 187 DYNAMIC_DEBUG_MODULE defined for each of them, especially for 188 the case of embedded system where the kernel image size is 189 sensitive for people. 190 191config SYMBOLIC_ERRNAME 192 bool "Support symbolic error names in printf" 193 default y if PRINTK 194 help 195 If you say Y here, the kernel's printf implementation will 196 be able to print symbolic error names such as ENOSPC instead 197 of the number 28. It makes the kernel image slightly larger 198 (about 3KB), but can make the kernel logs easier to read. 199 200config DEBUG_BUGVERBOSE 201 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT 202 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE) 203 default y 204 help 205 Say Y here to make BUG() panics output the file name and line number 206 of the BUG call as well as the EIP and oops trace. This aids 207 debugging but costs about 70-100K of memory. 208 209endmenu # "printk and dmesg options" 210 211config DEBUG_KERNEL 212 bool "Kernel debugging" 213 help 214 Say Y here if you are developing drivers or trying to debug and 215 identify kernel problems. 216 217config DEBUG_MISC 218 bool "Miscellaneous debug code" 219 default DEBUG_KERNEL 220 depends on DEBUG_KERNEL 221 help 222 Say Y here if you need to enable miscellaneous debug code that should 223 be under a more specific debug option but isn't. 224 225menu "Compile-time checks and compiler options" 226 227config DEBUG_INFO 228 bool 229 help 230 A kernel debug info option other than "None" has been selected 231 in the "Debug information" choice below, indicating that debug 232 information will be generated for build targets. 233 234# Clang generates .uleb128 with label differences for DWARF v5, a feature that 235# older binutils ports do not support when utilizing RISC-V style linker 236# relaxation: https://sourceware.org/bugzilla/show_bug.cgi?id=27215 237config AS_HAS_NON_CONST_ULEB128 238 def_bool $(as-instr,.uleb128 .Lexpr_end4 - .Lexpr_start3\n.Lexpr_start3:\n.Lexpr_end4:) 239 240choice 241 prompt "Debug information" 242 depends on DEBUG_KERNEL 243 help 244 Selecting something other than "None" results in a kernel image 245 that will include debugging info resulting in a larger kernel image. 246 This adds debug symbols to the kernel and modules (gcc -g), and 247 is needed if you intend to use kernel crashdump or binary object 248 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 249 250 Choose which version of DWARF debug info to emit. If unsure, 251 select "Toolchain default". 252 253config DEBUG_INFO_NONE 254 bool "Disable debug information" 255 help 256 Do not build the kernel with debugging information, which will 257 result in a faster and smaller build. 258 259config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT 260 bool "Rely on the toolchain's implicit default DWARF version" 261 select DEBUG_INFO 262 depends on !CC_IS_CLANG || AS_IS_LLVM || CLANG_VERSION < 140000 || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128) 263 help 264 The implicit default version of DWARF debug info produced by a 265 toolchain changes over time. 266 267 This can break consumers of the debug info that haven't upgraded to 268 support newer revisions, and prevent testing newer versions, but 269 those should be less common scenarios. 270 271config DEBUG_INFO_DWARF4 272 bool "Generate DWARF Version 4 debuginfo" 273 select DEBUG_INFO 274 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502) 275 help 276 Generate DWARF v4 debug info. This requires gcc 4.5+, binutils 2.35.2 277 if using clang without clang's integrated assembler, and gdb 7.0+. 278 279 If you have consumers of DWARF debug info that are not ready for 280 newer revisions of DWARF, you may wish to choose this or have your 281 config select this. 282 283config DEBUG_INFO_DWARF5 284 bool "Generate DWARF Version 5 debuginfo" 285 select DEBUG_INFO 286 depends on !ARCH_HAS_BROKEN_DWARF5 287 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128) 288 help 289 Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc 290 5.0+ accepts the -gdwarf-5 flag but only had partial support for some 291 draft features until 7.0), and gdb 8.0+. 292 293 Changes to the structure of debug info in Version 5 allow for around 294 15-18% savings in resulting image and debug info section sizes as 295 compared to DWARF Version 4. DWARF Version 5 standardizes previous 296 extensions such as accelerators for symbol indexing and the format 297 for fission (.dwo/.dwp) files. Users may not want to select this 298 config if they rely on tooling that has not yet been updated to 299 support DWARF Version 5. 300 301endchoice # "Debug information" 302 303if DEBUG_INFO 304 305config DEBUG_INFO_REDUCED 306 bool "Reduce debugging information" 307 help 308 If you say Y here gcc is instructed to generate less debugging 309 information for structure types. This means that tools that 310 need full debugging information (like kgdb or systemtap) won't 311 be happy. But if you merely need debugging information to 312 resolve line numbers there is no loss. Advantage is that 313 build directory object sizes shrink dramatically over a full 314 DEBUG_INFO build and compile times are reduced too. 315 Only works with newer gcc versions. 316 317choice 318 prompt "Compressed Debug information" 319 help 320 Compress the resulting debug info. Results in smaller debug info sections, 321 but requires that consumers are able to decompress the results. 322 323 If unsure, choose DEBUG_INFO_COMPRESSED_NONE. 324 325config DEBUG_INFO_COMPRESSED_NONE 326 bool "Don't compress debug information" 327 help 328 Don't compress debug info sections. 329 330config DEBUG_INFO_COMPRESSED_ZLIB 331 bool "Compress debugging information with zlib" 332 depends on $(cc-option,-gz=zlib) 333 depends on $(ld-option,--compress-debug-sections=zlib) 334 help 335 Compress the debug information using zlib. Requires GCC 5.0+ or Clang 336 5.0+, binutils 2.26+, and zlib. 337 338 Users of dpkg-deb via scripts/package/builddeb may find an increase in 339 size of their debug .deb packages with this config set, due to the 340 debug info being compressed with zlib, then the object files being 341 recompressed with a different compression scheme. But this is still 342 preferable to setting $KDEB_COMPRESS to "none" which would be even 343 larger. 344 345config DEBUG_INFO_COMPRESSED_ZSTD 346 bool "Compress debugging information with zstd" 347 depends on $(cc-option,-gz=zstd) 348 depends on $(ld-option,--compress-debug-sections=zstd) 349 help 350 Compress the debug information using zstd. This may provide better 351 compression than zlib, for about the same time costs, but requires newer 352 toolchain support. Requires GCC 13.0+ or Clang 16.0+, binutils 2.40+, and 353 zstd. 354 355endchoice # "Compressed Debug information" 356 357config DEBUG_INFO_SPLIT 358 bool "Produce split debuginfo in .dwo files" 359 depends on $(cc-option,-gsplit-dwarf) 360 # RISC-V linker relaxation + -gsplit-dwarf has issues with LLVM and GCC 361 # prior to 12.x: 362 # https://github.com/llvm/llvm-project/issues/56642 363 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99090 364 depends on !RISCV || GCC_VERSION >= 120000 365 help 366 Generate debug info into separate .dwo files. This significantly 367 reduces the build directory size for builds with DEBUG_INFO, 368 because it stores the information only once on disk in .dwo 369 files instead of multiple times in object files and executables. 370 In addition the debug information is also compressed. 371 372 Requires recent gcc (4.7+) and recent gdb/binutils. 373 Any tool that packages or reads debug information would need 374 to know about the .dwo files and include them. 375 Incompatible with older versions of ccache. 376 377config DEBUG_INFO_BTF 378 bool "Generate BTF type information" 379 depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED 380 depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST 381 depends on BPF_SYSCALL 382 depends on PAHOLE_VERSION >= 116 383 depends on DEBUG_INFO_DWARF4 || PAHOLE_VERSION >= 121 384 # pahole uses elfutils, which does not have support for Hexagon relocations 385 depends on !HEXAGON 386 help 387 Generate deduplicated BTF type information from DWARF debug info. 388 Turning this on requires pahole v1.16 or later (v1.21 or later to 389 support DWARF 5), which will convert DWARF type info into equivalent 390 deduplicated BTF type info. 391 392config PAHOLE_HAS_SPLIT_BTF 393 def_bool PAHOLE_VERSION >= 119 394 395config PAHOLE_HAS_BTF_TAG 396 def_bool PAHOLE_VERSION >= 123 397 depends on CC_IS_CLANG 398 help 399 Decide whether pahole emits btf_tag attributes (btf_type_tag and 400 btf_decl_tag) or not. Currently only clang compiler implements 401 these attributes, so make the config depend on CC_IS_CLANG. 402 403config PAHOLE_HAS_LANG_EXCLUDE 404 def_bool PAHOLE_VERSION >= 124 405 help 406 Support for the --lang_exclude flag which makes pahole exclude 407 compilation units from the supplied language. Used in Kbuild to 408 omit Rust CUs which are not supported in version 1.24 of pahole, 409 otherwise it would emit malformed kernel and module binaries when 410 using DEBUG_INFO_BTF_MODULES. 411 412config DEBUG_INFO_BTF_MODULES 413 bool "Generate BTF type information for kernel modules" 414 default y 415 depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF 416 help 417 Generate compact split BTF type information for kernel modules. 418 419config MODULE_ALLOW_BTF_MISMATCH 420 bool "Allow loading modules with non-matching BTF type info" 421 depends on DEBUG_INFO_BTF_MODULES 422 help 423 For modules whose split BTF does not match vmlinux, load without 424 BTF rather than refusing to load. The default behavior with 425 module BTF enabled is to reject modules with such mismatches; 426 this option will still load module BTF where possible but ignore 427 it when a mismatch is found. 428 429config GDB_SCRIPTS 430 bool "Provide GDB scripts for kernel debugging" 431 help 432 This creates the required links to GDB helper scripts in the 433 build directory. If you load vmlinux into gdb, the helper 434 scripts will be automatically imported by gdb as well, and 435 additional functions are available to analyze a Linux kernel 436 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst 437 for further details. 438 439endif # DEBUG_INFO 440 441config FRAME_WARN 442 int "Warn for stack frames larger than" 443 range 0 8192 444 default 0 if KMSAN 445 default 2048 if GCC_PLUGIN_LATENT_ENTROPY 446 default 2048 if PARISC 447 default 1536 if (!64BIT && XTENSA) 448 default 1280 if KASAN && !64BIT 449 default 1024 if !64BIT 450 default 2048 if 64BIT 451 help 452 Tell the compiler to warn at build time for stack frames larger than this. 453 Setting this too low will cause a lot of warnings. 454 Setting it to 0 disables the warning. 455 456config STRIP_ASM_SYMS 457 bool "Strip assembler-generated symbols during link" 458 default n 459 help 460 Strip internal assembler-generated symbols during a link (symbols 461 that look like '.Lxxx') so they don't pollute the output of 462 get_wchan() and suchlike. 463 464config READABLE_ASM 465 bool "Generate readable assembler code" 466 depends on DEBUG_KERNEL 467 depends on CC_IS_GCC 468 help 469 Disable some compiler optimizations that tend to generate human unreadable 470 assembler output. This may make the kernel slightly slower, but it helps 471 to keep kernel developers who have to stare a lot at assembler listings 472 sane. 473 474config HEADERS_INSTALL 475 bool "Install uapi headers to usr/include" 476 depends on !UML 477 help 478 This option will install uapi headers (headers exported to user-space) 479 into the usr/include directory for use during the kernel build. 480 This is unneeded for building the kernel itself, but needed for some 481 user-space program samples. It is also needed by some features such 482 as uapi header sanity checks. 483 484config DEBUG_SECTION_MISMATCH 485 bool "Enable full Section mismatch analysis" 486 depends on CC_IS_GCC 487 help 488 The section mismatch analysis checks if there are illegal 489 references from one section to another section. 490 During linktime or runtime, some sections are dropped; 491 any use of code/data previously in these sections would 492 most likely result in an oops. 493 In the code, functions and variables are annotated with 494 __init,, etc. (see the full list in include/linux/init.h), 495 which results in the code/data being placed in specific sections. 496 The section mismatch analysis is always performed after a full 497 kernel build, and enabling this option causes the following 498 additional step to occur: 499 - Add the option -fno-inline-functions-called-once to gcc commands. 500 When inlining a function annotated with __init in a non-init 501 function, we would lose the section information and thus 502 the analysis would not catch the illegal reference. 503 This option tells gcc to inline less (but it does result in 504 a larger kernel). 505 506config SECTION_MISMATCH_WARN_ONLY 507 bool "Make section mismatch errors non-fatal" 508 default y 509 help 510 If you say N here, the build process will fail if there are any 511 section mismatch, instead of just throwing warnings. 512 513 If unsure, say Y. 514 515config DEBUG_FORCE_FUNCTION_ALIGN_64B 516 bool "Force all function address 64B aligned" 517 depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC || RISCV || S390) 518 select FUNCTION_ALIGNMENT_64B 519 help 520 There are cases that a commit from one domain changes the function 521 address alignment of other domains, and cause magic performance 522 bump (regression or improvement). Enable this option will help to 523 verify if the bump is caused by function alignment changes, while 524 it will slightly increase the kernel size and affect icache usage. 525 526 It is mainly for debug and performance tuning use. 527 528# 529# Select this config option from the architecture Kconfig, if it 530# is preferred to always offer frame pointers as a config 531# option on the architecture (regardless of KERNEL_DEBUG): 532# 533config ARCH_WANT_FRAME_POINTERS 534 bool 535 536config FRAME_POINTER 537 bool "Compile the kernel with frame pointers" 538 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS 539 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 540 help 541 If you say Y here the resulting kernel image will be slightly 542 larger and slower, but it gives very useful debugging information 543 in case of kernel bugs. (precise oopses/stacktraces/warnings) 544 545config OBJTOOL 546 bool 547 548config STACK_VALIDATION 549 bool "Compile-time stack metadata validation" 550 depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER 551 select OBJTOOL 552 default n 553 help 554 Validate frame pointer rules at compile-time. This helps ensure that 555 runtime stack traces are more reliable. 556 557 For more information, see 558 tools/objtool/Documentation/objtool.txt. 559 560config NOINSTR_VALIDATION 561 bool 562 depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY 563 select OBJTOOL 564 default y 565 566config VMLINUX_MAP 567 bool "Generate vmlinux.map file when linking" 568 depends on EXPERT 569 help 570 Selecting this option will pass "-Map=vmlinux.map" to ld 571 when linking vmlinux. That file can be useful for verifying 572 and debugging magic section games, and for seeing which 573 pieces of code get eliminated with 574 CONFIG_LD_DEAD_CODE_DATA_ELIMINATION. 575 576config BUILTIN_MODULE_RANGES 577 bool "Generate address range information for builtin modules" 578 depends on !LTO 579 depends on VMLINUX_MAP 580 help 581 When modules are built into the kernel, there will be no module name 582 associated with its symbols in /proc/kallsyms. Tracers may want to 583 identify symbols by module name and symbol name regardless of whether 584 the module is configured as loadable or not. 585 586 This option generates modules.builtin.ranges in the build tree with 587 offset ranges (per ELF section) for the module(s) they belong to. 588 It also records an anchor symbol to determine the load address of the 589 section. 590 591config DEBUG_FORCE_WEAK_PER_CPU 592 bool "Force weak per-cpu definitions" 593 depends on DEBUG_KERNEL 594 help 595 s390 and alpha require percpu variables in modules to be 596 defined weak to work around addressing range issue which 597 puts the following two restrictions on percpu variable 598 definitions. 599 600 1. percpu symbols must be unique whether static or not 601 2. percpu variables can't be defined inside a function 602 603 To ensure that generic code follows the above rules, this 604 option forces all percpu variables to be defined as weak. 605 606endmenu # "Compiler options" 607 608menu "Generic Kernel Debugging Instruments" 609 610config MAGIC_SYSRQ 611 bool "Magic SysRq key" 612 depends on !UML 613 help 614 If you say Y here, you will have some control over the system even 615 if the system crashes for example during kernel debugging (e.g., you 616 will be able to flush the buffer cache to disk, reboot the system 617 immediately or dump some status information). This is accomplished 618 by pressing various keys while holding SysRq (Alt+PrintScreen). It 619 also works on a serial console (on PC hardware at least), if you 620 send a BREAK and then within 5 seconds a command keypress. The 621 keys are documented in <file:Documentation/admin-guide/sysrq.rst>. 622 Don't say Y unless you really know what this hack does. 623 624config MAGIC_SYSRQ_DEFAULT_ENABLE 625 hex "Enable magic SysRq key functions by default" 626 depends on MAGIC_SYSRQ 627 default 0x1 628 help 629 Specifies which SysRq key functions are enabled by default. 630 This may be set to 1 or 0 to enable or disable them all, or 631 to a bitmask as described in Documentation/admin-guide/sysrq.rst. 632 633config MAGIC_SYSRQ_SERIAL 634 bool "Enable magic SysRq key over serial" 635 depends on MAGIC_SYSRQ 636 default y 637 help 638 Many embedded boards have a disconnected TTL level serial which can 639 generate some garbage that can lead to spurious false sysrq detects. 640 This option allows you to decide whether you want to enable the 641 magic SysRq key. 642 643config MAGIC_SYSRQ_SERIAL_SEQUENCE 644 string "Char sequence that enables magic SysRq over serial" 645 depends on MAGIC_SYSRQ_SERIAL 646 default "" 647 help 648 Specifies a sequence of characters that can follow BREAK to enable 649 SysRq on a serial console. 650 651 If unsure, leave an empty string and the option will not be enabled. 652 653config DEBUG_FS 654 bool "Debug Filesystem" 655 help 656 debugfs is a virtual file system that kernel developers use to put 657 debugging files into. Enable this option to be able to read and 658 write to these files. 659 660 For detailed documentation on the debugfs API, see 661 Documentation/filesystems/. 662 663 If unsure, say N. 664 665choice 666 prompt "Debugfs default access" 667 depends on DEBUG_FS 668 default DEBUG_FS_ALLOW_ALL 669 help 670 This selects the default access restrictions for debugfs. 671 It can be overridden with kernel command line option 672 debugfs=[on,no-mount,off]. The restrictions apply for API access 673 and filesystem registration. 674 675config DEBUG_FS_ALLOW_ALL 676 bool "Access normal" 677 help 678 No restrictions apply. Both API and filesystem registration 679 is on. This is the normal default operation. 680 681config DEBUG_FS_DISALLOW_MOUNT 682 bool "Do not register debugfs as filesystem" 683 help 684 The API is open but filesystem is not loaded. Clients can still do 685 their work and read with debug tools that do not need 686 debugfs filesystem. 687 688config DEBUG_FS_ALLOW_NONE 689 bool "No access" 690 help 691 Access is off. Clients get -PERM when trying to create nodes in 692 debugfs tree and debugfs is not registered as a filesystem. 693 Client can then back-off or continue without debugfs access. 694 695endchoice 696 697source "lib/Kconfig.kgdb" 698source "lib/Kconfig.ubsan" 699source "lib/Kconfig.kcsan" 700 701endmenu 702 703menu "Networking Debugging" 704 705source "net/Kconfig.debug" 706 707endmenu # "Networking Debugging" 708 709menu "Memory Debugging" 710 711source "mm/Kconfig.debug" 712 713config DEBUG_OBJECTS 714 bool "Debug object operations" 715 depends on DEBUG_KERNEL 716 help 717 If you say Y here, additional code will be inserted into the 718 kernel to track the life time of various objects and validate 719 the operations on those objects. 720 721config DEBUG_OBJECTS_SELFTEST 722 bool "Debug objects selftest" 723 depends on DEBUG_OBJECTS 724 help 725 This enables the selftest of the object debug code. 726 727config DEBUG_OBJECTS_FREE 728 bool "Debug objects in freed memory" 729 depends on DEBUG_OBJECTS 730 help 731 This enables checks whether a k/v free operation frees an area 732 which contains an object which has not been deactivated 733 properly. This can make kmalloc/kfree-intensive workloads 734 much slower. 735 736config DEBUG_OBJECTS_TIMERS 737 bool "Debug timer objects" 738 depends on DEBUG_OBJECTS 739 help 740 If you say Y here, additional code will be inserted into the 741 timer routines to track the life time of timer objects and 742 validate the timer operations. 743 744config DEBUG_OBJECTS_WORK 745 bool "Debug work objects" 746 depends on DEBUG_OBJECTS 747 help 748 If you say Y here, additional code will be inserted into the 749 work queue routines to track the life time of work objects and 750 validate the work operations. 751 752config DEBUG_OBJECTS_RCU_HEAD 753 bool "Debug RCU callbacks objects" 754 depends on DEBUG_OBJECTS 755 help 756 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 757 758config DEBUG_OBJECTS_PERCPU_COUNTER 759 bool "Debug percpu counter objects" 760 depends on DEBUG_OBJECTS 761 help 762 If you say Y here, additional code will be inserted into the 763 percpu counter routines to track the life time of percpu counter 764 objects and validate the percpu counter operations. 765 766config DEBUG_OBJECTS_ENABLE_DEFAULT 767 int "debug_objects bootup default value (0-1)" 768 range 0 1 769 default "1" 770 depends on DEBUG_OBJECTS 771 help 772 Debug objects boot parameter default value 773 774config SHRINKER_DEBUG 775 bool "Enable shrinker debugging support" 776 depends on DEBUG_FS 777 help 778 Say Y to enable the shrinker debugfs interface which provides 779 visibility into the kernel memory shrinkers subsystem. 780 Disable it to avoid an extra memory footprint. 781 782config DEBUG_STACK_USAGE 783 bool "Stack utilization instrumentation" 784 depends on DEBUG_KERNEL 785 help 786 Enables the display of the minimum amount of free stack which each 787 task has ever had available in the sysrq-T and sysrq-P debug output. 788 Also emits a message to dmesg when a process exits if that process 789 used more stack space than previously exiting processes. 790 791 This option will slow down process creation somewhat. 792 793config SCHED_STACK_END_CHECK 794 bool "Detect stack corruption on calls to schedule()" 795 depends on DEBUG_KERNEL 796 default n 797 help 798 This option checks for a stack overrun on calls to schedule(). 799 If the stack end location is found to be over written always panic as 800 the content of the corrupted region can no longer be trusted. 801 This is to ensure no erroneous behaviour occurs which could result in 802 data corruption or a sporadic crash at a later stage once the region 803 is examined. The runtime overhead introduced is minimal. 804 805config ARCH_HAS_DEBUG_VM_PGTABLE 806 bool 807 help 808 An architecture should select this when it can successfully 809 build and run DEBUG_VM_PGTABLE. 810 811config DEBUG_VM_IRQSOFF 812 def_bool DEBUG_VM && !PREEMPT_RT 813 814config DEBUG_VM 815 bool "Debug VM" 816 depends on DEBUG_KERNEL 817 help 818 Enable this to turn on extended checks in the virtual-memory system 819 that may impact performance. 820 821 If unsure, say N. 822 823config DEBUG_VM_SHOOT_LAZIES 824 bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation" 825 depends on DEBUG_VM 826 depends on MMU_LAZY_TLB_SHOOTDOWN 827 help 828 Enable additional IPIs that ensure lazy tlb mm references are removed 829 before the mm is freed. 830 831 If unsure, say N. 832 833config DEBUG_VM_MAPLE_TREE 834 bool "Debug VM maple trees" 835 depends on DEBUG_VM 836 select DEBUG_MAPLE_TREE 837 help 838 Enable VM maple tree debugging information and extra validations. 839 840 If unsure, say N. 841 842config DEBUG_VM_RB 843 bool "Debug VM red-black trees" 844 depends on DEBUG_VM 845 help 846 Enable VM red-black tree debugging information and extra validations. 847 848 If unsure, say N. 849 850config DEBUG_VM_PGFLAGS 851 bool "Debug page-flags operations" 852 depends on DEBUG_VM 853 help 854 Enables extra validation on page flags operations. 855 856 If unsure, say N. 857 858config DEBUG_VM_PGTABLE 859 bool "Debug arch page table for semantics compliance" 860 depends on MMU 861 depends on ARCH_HAS_DEBUG_VM_PGTABLE 862 default y if DEBUG_VM 863 help 864 This option provides a debug method which can be used to test 865 architecture page table helper functions on various platforms in 866 verifying if they comply with expected generic MM semantics. This 867 will help architecture code in making sure that any changes or 868 new additions of these helpers still conform to expected 869 semantics of the generic MM. Platforms will have to opt in for 870 this through ARCH_HAS_DEBUG_VM_PGTABLE. 871 872 If unsure, say N. 873 874config ARCH_HAS_DEBUG_VIRTUAL 875 bool 876 877config DEBUG_VIRTUAL 878 bool "Debug VM translations" 879 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL 880 help 881 Enable some costly sanity checks in virtual to page code. This can 882 catch mistakes with virt_to_page() and friends. 883 884 If unsure, say N. 885 886config DEBUG_NOMMU_REGIONS 887 bool "Debug the global anon/private NOMMU mapping region tree" 888 depends on DEBUG_KERNEL && !MMU 889 help 890 This option causes the global tree of anonymous and private mapping 891 regions to be regularly checked for invalid topology. 892 893config DEBUG_MEMORY_INIT 894 bool "Debug memory initialisation" if EXPERT 895 default !EXPERT 896 help 897 Enable this for additional checks during memory initialisation. 898 The sanity checks verify aspects of the VM such as the memory model 899 and other information provided by the architecture. Verbose 900 information will be printed at KERN_DEBUG loglevel depending 901 on the mminit_loglevel= command-line option. 902 903 If unsure, say Y 904 905config MEMORY_NOTIFIER_ERROR_INJECT 906 tristate "Memory hotplug notifier error injection module" 907 depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION 908 help 909 This option provides the ability to inject artificial errors to 910 memory hotplug notifier chain callbacks. It is controlled through 911 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 912 913 If the notifier call chain should be failed with some events 914 notified, write the error code to "actions/<notifier event>/error". 915 916 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 917 918 # cd /sys/kernel/debug/notifier-error-inject/memory 919 # echo -12 > actions/MEM_GOING_OFFLINE/error 920 # echo offline > /sys/devices/system/memory/memoryXXX/state 921 bash: echo: write error: Cannot allocate memory 922 923 To compile this code as a module, choose M here: the module will 924 be called memory-notifier-error-inject. 925 926 If unsure, say N. 927 928config DEBUG_PER_CPU_MAPS 929 bool "Debug access to per_cpu maps" 930 depends on DEBUG_KERNEL 931 depends on SMP 932 help 933 Say Y to verify that the per_cpu map being accessed has 934 been set up. This adds a fair amount of code to kernel memory 935 and decreases performance. 936 937 Say N if unsure. 938 939config DEBUG_KMAP_LOCAL 940 bool "Debug kmap_local temporary mappings" 941 depends on DEBUG_KERNEL && KMAP_LOCAL 942 help 943 This option enables additional error checking for the kmap_local 944 infrastructure. Disable for production use. 945 946config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 947 bool 948 949config DEBUG_KMAP_LOCAL_FORCE_MAP 950 bool "Enforce kmap_local temporary mappings" 951 depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 952 select KMAP_LOCAL 953 select DEBUG_KMAP_LOCAL 954 help 955 This option enforces temporary mappings through the kmap_local 956 mechanism for non-highmem pages and on non-highmem systems. 957 Disable this for production systems! 958 959config DEBUG_HIGHMEM 960 bool "Highmem debugging" 961 depends on DEBUG_KERNEL && HIGHMEM 962 select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 963 select DEBUG_KMAP_LOCAL 964 help 965 This option enables additional error checking for high memory 966 systems. Disable for production systems. 967 968config HAVE_DEBUG_STACKOVERFLOW 969 bool 970 971config DEBUG_STACKOVERFLOW 972 bool "Check for stack overflows" 973 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 974 help 975 Say Y here if you want to check for overflows of kernel, IRQ 976 and exception stacks (if your architecture uses them). This 977 option will show detailed messages if free stack space drops 978 below a certain limit. 979 980 These kinds of bugs usually occur when call-chains in the 981 kernel get too deep, especially when interrupts are 982 involved. 983 984 Use this in cases where you see apparently random memory 985 corruption, especially if it appears in 'struct thread_info' 986 987 If in doubt, say "N". 988 989config CODE_TAGGING 990 bool 991 select KALLSYMS 992 993config MEM_ALLOC_PROFILING 994 bool "Enable memory allocation profiling" 995 default n 996 depends on PROC_FS 997 depends on !DEBUG_FORCE_WEAK_PER_CPU 998 select CODE_TAGGING 999 select PAGE_EXTENSION 1000 select SLAB_OBJ_EXT 1001 help 1002 Track allocation source code and record total allocation size 1003 initiated at that code location. The mechanism can be used to track 1004 memory leaks with a low performance and memory impact. 1005 1006config MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT 1007 bool "Enable memory allocation profiling by default" 1008 default y 1009 depends on MEM_ALLOC_PROFILING 1010 1011config MEM_ALLOC_PROFILING_DEBUG 1012 bool "Memory allocation profiler debugging" 1013 default n 1014 depends on MEM_ALLOC_PROFILING 1015 select MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT 1016 help 1017 Adds warnings with helpful error messages for memory allocation 1018 profiling. 1019 1020source "lib/Kconfig.kasan" 1021source "lib/Kconfig.kfence" 1022source "lib/Kconfig.kmsan" 1023 1024endmenu # "Memory Debugging" 1025 1026config DEBUG_SHIRQ 1027 bool "Debug shared IRQ handlers" 1028 depends on DEBUG_KERNEL 1029 help 1030 Enable this to generate a spurious interrupt just before a shared 1031 interrupt handler is deregistered (generating one when registering 1032 is currently disabled). Drivers need to handle this correctly. Some 1033 don't and need to be caught. 1034 1035menu "Debug Oops, Lockups and Hangs" 1036 1037config PANIC_ON_OOPS 1038 bool "Panic on Oops" 1039 help 1040 Say Y here to enable the kernel to panic when it oopses. This 1041 has the same effect as setting oops=panic on the kernel command 1042 line. 1043 1044 This feature is useful to ensure that the kernel does not do 1045 anything erroneous after an oops which could result in data 1046 corruption or other issues. 1047 1048 Say N if unsure. 1049 1050config PANIC_ON_OOPS_VALUE 1051 int 1052 range 0 1 1053 default 0 if !PANIC_ON_OOPS 1054 default 1 if PANIC_ON_OOPS 1055 1056config PANIC_TIMEOUT 1057 int "panic timeout" 1058 default 0 1059 help 1060 Set the timeout value (in seconds) until a reboot occurs when 1061 the kernel panics. If n = 0, then we wait forever. A timeout 1062 value n > 0 will wait n seconds before rebooting, while a timeout 1063 value n < 0 will reboot immediately. This setting can be overridden 1064 with the kernel command line option panic=, and from userspace via 1065 /proc/sys/kernel/panic. 1066 1067config LOCKUP_DETECTOR 1068 bool 1069 1070config SOFTLOCKUP_DETECTOR 1071 bool "Detect Soft Lockups" 1072 depends on DEBUG_KERNEL && !S390 1073 select LOCKUP_DETECTOR 1074 help 1075 Say Y here to enable the kernel to act as a watchdog to detect 1076 soft lockups. 1077 1078 Softlockups are bugs that cause the kernel to loop in kernel 1079 mode for more than 20 seconds, without giving other tasks a 1080 chance to run. The current stack trace is displayed upon 1081 detection and the system will stay locked up. 1082 1083config SOFTLOCKUP_DETECTOR_INTR_STORM 1084 bool "Detect Interrupt Storm in Soft Lockups" 1085 depends on SOFTLOCKUP_DETECTOR && IRQ_TIME_ACCOUNTING 1086 select GENERIC_IRQ_STAT_SNAPSHOT 1087 default y if NR_CPUS <= 128 1088 help 1089 Say Y here to enable the kernel to detect interrupt storm 1090 during "soft lockups". 1091 1092 "soft lockups" can be caused by a variety of reasons. If one is 1093 caused by an interrupt storm, then the storming interrupts will not 1094 be on the callstack. To detect this case, it is necessary to report 1095 the CPU stats and the interrupt counts during the "soft lockups". 1096 1097config BOOTPARAM_SOFTLOCKUP_PANIC 1098 bool "Panic (Reboot) On Soft Lockups" 1099 depends on SOFTLOCKUP_DETECTOR 1100 help 1101 Say Y here to enable the kernel to panic on "soft lockups", 1102 which are bugs that cause the kernel to loop in kernel 1103 mode for more than 20 seconds (configurable using the watchdog_thresh 1104 sysctl), without giving other tasks a chance to run. 1105 1106 The panic can be used in combination with panic_timeout, 1107 to cause the system to reboot automatically after a 1108 lockup has been detected. This feature is useful for 1109 high-availability systems that have uptime guarantees and 1110 where a lockup must be resolved ASAP. 1111 1112 Say N if unsure. 1113 1114config HAVE_HARDLOCKUP_DETECTOR_BUDDY 1115 bool 1116 depends on SMP 1117 default y 1118 1119# 1120# Global switch whether to build a hardlockup detector at all. It is available 1121# only when the architecture supports at least one implementation. There are 1122# two exceptions. The hardlockup detector is never enabled on: 1123# 1124# s390: it reported many false positives there 1125# 1126# sparc64: has a custom implementation which is not using the common 1127# hardlockup command line options and sysctl interface. 1128# 1129config HARDLOCKUP_DETECTOR 1130 bool "Detect Hard Lockups" 1131 depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64 1132 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH 1133 imply HARDLOCKUP_DETECTOR_PERF 1134 imply HARDLOCKUP_DETECTOR_BUDDY 1135 imply HARDLOCKUP_DETECTOR_ARCH 1136 select LOCKUP_DETECTOR 1137 1138 help 1139 Say Y here to enable the kernel to act as a watchdog to detect 1140 hard lockups. 1141 1142 Hardlockups are bugs that cause the CPU to loop in kernel mode 1143 for more than 10 seconds, without letting other interrupts have a 1144 chance to run. The current stack trace is displayed upon detection 1145 and the system will stay locked up. 1146 1147# 1148# Note that arch-specific variants are always preferred. 1149# 1150config HARDLOCKUP_DETECTOR_PREFER_BUDDY 1151 bool "Prefer the buddy CPU hardlockup detector" 1152 depends on HARDLOCKUP_DETECTOR 1153 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY 1154 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1155 help 1156 Say Y here to prefer the buddy hardlockup detector over the perf one. 1157 1158 With the buddy detector, each CPU uses its softlockup hrtimer 1159 to check that the next CPU is processing hrtimer interrupts by 1160 verifying that a counter is increasing. 1161 1162 This hardlockup detector is useful on systems that don't have 1163 an arch-specific hardlockup detector or if resources needed 1164 for the hardlockup detector are better used for other things. 1165 1166config HARDLOCKUP_DETECTOR_PERF 1167 bool 1168 depends on HARDLOCKUP_DETECTOR 1169 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY 1170 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1171 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1172 1173config HARDLOCKUP_DETECTOR_BUDDY 1174 bool 1175 depends on HARDLOCKUP_DETECTOR 1176 depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY 1177 depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY 1178 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1179 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1180 1181config HARDLOCKUP_DETECTOR_ARCH 1182 bool 1183 depends on HARDLOCKUP_DETECTOR 1184 depends on HAVE_HARDLOCKUP_DETECTOR_ARCH 1185 help 1186 The arch-specific implementation of the hardlockup detector will 1187 be used. 1188 1189# 1190# Both the "perf" and "buddy" hardlockup detectors count hrtimer 1191# interrupts. This config enables functions managing this common code. 1192# 1193config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1194 bool 1195 select SOFTLOCKUP_DETECTOR 1196 1197# 1198# Enables a timestamp based low pass filter to compensate for perf based 1199# hard lockup detection which runs too fast due to turbo modes. 1200# 1201config HARDLOCKUP_CHECK_TIMESTAMP 1202 bool 1203 1204config BOOTPARAM_HARDLOCKUP_PANIC 1205 bool "Panic (Reboot) On Hard Lockups" 1206 depends on HARDLOCKUP_DETECTOR 1207 help 1208 Say Y here to enable the kernel to panic on "hard lockups", 1209 which are bugs that cause the kernel to loop in kernel 1210 mode with interrupts disabled for more than 10 seconds (configurable 1211 using the watchdog_thresh sysctl). 1212 1213 Say N if unsure. 1214 1215config DETECT_HUNG_TASK 1216 bool "Detect Hung Tasks" 1217 depends on DEBUG_KERNEL 1218 default SOFTLOCKUP_DETECTOR 1219 help 1220 Say Y here to enable the kernel to detect "hung tasks", 1221 which are bugs that cause the task to be stuck in 1222 uninterruptible "D" state indefinitely. 1223 1224 When a hung task is detected, the kernel will print the 1225 current stack trace (which you should report), but the 1226 task will stay in uninterruptible state. If lockdep is 1227 enabled then all held locks will also be reported. This 1228 feature has negligible overhead. 1229 1230config DEFAULT_HUNG_TASK_TIMEOUT 1231 int "Default timeout for hung task detection (in seconds)" 1232 depends on DETECT_HUNG_TASK 1233 default 120 1234 help 1235 This option controls the default timeout (in seconds) used 1236 to determine when a task has become non-responsive and should 1237 be considered hung. 1238 1239 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 1240 sysctl or by writing a value to 1241 /proc/sys/kernel/hung_task_timeout_secs. 1242 1243 A timeout of 0 disables the check. The default is two minutes. 1244 Keeping the default should be fine in most cases. 1245 1246config BOOTPARAM_HUNG_TASK_PANIC 1247 bool "Panic (Reboot) On Hung Tasks" 1248 depends on DETECT_HUNG_TASK 1249 help 1250 Say Y here to enable the kernel to panic on "hung tasks", 1251 which are bugs that cause the kernel to leave a task stuck 1252 in uninterruptible "D" state. 1253 1254 The panic can be used in combination with panic_timeout, 1255 to cause the system to reboot automatically after a 1256 hung task has been detected. This feature is useful for 1257 high-availability systems that have uptime guarantees and 1258 where a hung tasks must be resolved ASAP. 1259 1260 Say N if unsure. 1261 1262config WQ_WATCHDOG 1263 bool "Detect Workqueue Stalls" 1264 depends on DEBUG_KERNEL 1265 help 1266 Say Y here to enable stall detection on workqueues. If a 1267 worker pool doesn't make forward progress on a pending work 1268 item for over a given amount of time, 30s by default, a 1269 warning message is printed along with dump of workqueue 1270 state. This can be configured through kernel parameter 1271 "workqueue.watchdog_thresh" and its sysfs counterpart. 1272 1273config WQ_CPU_INTENSIVE_REPORT 1274 bool "Report per-cpu work items which hog CPU for too long" 1275 depends on DEBUG_KERNEL 1276 help 1277 Say Y here to enable reporting of concurrency-managed per-cpu work 1278 items that hog CPUs for longer than 1279 workqueue.cpu_intensive_thresh_us. Workqueue automatically 1280 detects and excludes them from concurrency management to prevent 1281 them from stalling other per-cpu work items. Occassional 1282 triggering may not necessarily indicate a problem. Repeated 1283 triggering likely indicates that the work item should be switched 1284 to use an unbound workqueue. 1285 1286config TEST_LOCKUP 1287 tristate "Test module to generate lockups" 1288 depends on m 1289 help 1290 This builds the "test_lockup" module that helps to make sure 1291 that watchdogs and lockup detectors are working properly. 1292 1293 Depending on module parameters it could emulate soft or hard 1294 lockup, "hung task", or locking arbitrary lock for a long time. 1295 Also it could generate series of lockups with cooling-down periods. 1296 1297 If unsure, say N. 1298 1299endmenu # "Debug lockups and hangs" 1300 1301menu "Scheduler Debugging" 1302 1303config SCHED_DEBUG 1304 bool "Collect scheduler debugging info" 1305 depends on DEBUG_KERNEL && DEBUG_FS 1306 default y 1307 help 1308 If you say Y here, the /sys/kernel/debug/sched file will be provided 1309 that can help debug the scheduler. The runtime overhead of this 1310 option is minimal. 1311 1312config SCHED_INFO 1313 bool 1314 default n 1315 1316config SCHEDSTATS 1317 bool "Collect scheduler statistics" 1318 depends on PROC_FS 1319 select SCHED_INFO 1320 help 1321 If you say Y here, additional code will be inserted into the 1322 scheduler and related routines to collect statistics about 1323 scheduler behavior and provide them in /proc/schedstat. These 1324 stats may be useful for both tuning and debugging the scheduler 1325 If you aren't debugging the scheduler or trying to tune a specific 1326 application, you can say N to avoid the very slight overhead 1327 this adds. 1328 1329endmenu 1330 1331config DEBUG_PREEMPT 1332 bool "Debug preemptible kernel" 1333 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1334 help 1335 If you say Y here then the kernel will use a debug variant of the 1336 commonly used smp_processor_id() function and will print warnings 1337 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1338 will detect preemption count underflows. 1339 1340 This option has potential to introduce high runtime overhead, 1341 depending on workload as it triggers debugging routines for each 1342 this_cpu operation. It should only be used for debugging purposes. 1343 1344menu "Lock Debugging (spinlocks, mutexes, etc...)" 1345 1346config LOCK_DEBUGGING_SUPPORT 1347 bool 1348 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1349 default y 1350 1351config PROVE_LOCKING 1352 bool "Lock debugging: prove locking correctness" 1353 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1354 select LOCKDEP 1355 select DEBUG_SPINLOCK 1356 select DEBUG_MUTEXES if !PREEMPT_RT 1357 select DEBUG_RT_MUTEXES if RT_MUTEXES 1358 select DEBUG_RWSEMS if !PREEMPT_RT 1359 select DEBUG_WW_MUTEX_SLOWPATH 1360 select DEBUG_LOCK_ALLOC 1361 select PREEMPT_COUNT if !ARCH_NO_PREEMPT 1362 select TRACE_IRQFLAGS 1363 default n 1364 help 1365 This feature enables the kernel to prove that all locking 1366 that occurs in the kernel runtime is mathematically 1367 correct: that under no circumstance could an arbitrary (and 1368 not yet triggered) combination of observed locking 1369 sequences (on an arbitrary number of CPUs, running an 1370 arbitrary number of tasks and interrupt contexts) cause a 1371 deadlock. 1372 1373 In short, this feature enables the kernel to report locking 1374 related deadlocks before they actually occur. 1375 1376 The proof does not depend on how hard and complex a 1377 deadlock scenario would be to trigger: how many 1378 participant CPUs, tasks and irq-contexts would be needed 1379 for it to trigger. The proof also does not depend on 1380 timing: if a race and a resulting deadlock is possible 1381 theoretically (no matter how unlikely the race scenario 1382 is), it will be proven so and will immediately be 1383 reported by the kernel (once the event is observed that 1384 makes the deadlock theoretically possible). 1385 1386 If a deadlock is impossible (i.e. the locking rules, as 1387 observed by the kernel, are mathematically correct), the 1388 kernel reports nothing. 1389 1390 NOTE: this feature can also be enabled for rwlocks, mutexes 1391 and rwsems - in which case all dependencies between these 1392 different locking variants are observed and mapped too, and 1393 the proof of observed correctness is also maintained for an 1394 arbitrary combination of these separate locking variants. 1395 1396 For more details, see Documentation/locking/lockdep-design.rst. 1397 1398config PROVE_RAW_LOCK_NESTING 1399 bool 1400 depends on PROVE_LOCKING 1401 default y 1402 help 1403 Enable the raw_spinlock vs. spinlock nesting checks which ensure 1404 that the lock nesting rules for PREEMPT_RT enabled kernels are 1405 not violated. 1406 1407config LOCK_STAT 1408 bool "Lock usage statistics" 1409 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1410 select LOCKDEP 1411 select DEBUG_SPINLOCK 1412 select DEBUG_MUTEXES if !PREEMPT_RT 1413 select DEBUG_RT_MUTEXES if RT_MUTEXES 1414 select DEBUG_LOCK_ALLOC 1415 default n 1416 help 1417 This feature enables tracking lock contention points 1418 1419 For more details, see Documentation/locking/lockstat.rst 1420 1421 This also enables lock events required by "perf lock", 1422 subcommand of perf. 1423 If you want to use "perf lock", you also need to turn on 1424 CONFIG_EVENT_TRACING. 1425 1426 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1427 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1428 1429config DEBUG_RT_MUTEXES 1430 bool "RT Mutex debugging, deadlock detection" 1431 depends on DEBUG_KERNEL && RT_MUTEXES 1432 help 1433 This allows rt mutex semantics violations and rt mutex related 1434 deadlocks (lockups) to be detected and reported automatically. 1435 1436config DEBUG_SPINLOCK 1437 bool "Spinlock and rw-lock debugging: basic checks" 1438 depends on DEBUG_KERNEL 1439 select UNINLINE_SPIN_UNLOCK 1440 help 1441 Say Y here and build SMP to catch missing spinlock initialization 1442 and certain other kinds of spinlock errors commonly made. This is 1443 best used in conjunction with the NMI watchdog so that spinlock 1444 deadlocks are also debuggable. 1445 1446config DEBUG_MUTEXES 1447 bool "Mutex debugging: basic checks" 1448 depends on DEBUG_KERNEL && !PREEMPT_RT 1449 help 1450 This feature allows mutex semantics violations to be detected and 1451 reported. 1452 1453config DEBUG_WW_MUTEX_SLOWPATH 1454 bool "Wait/wound mutex debugging: Slowpath testing" 1455 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1456 select DEBUG_LOCK_ALLOC 1457 select DEBUG_SPINLOCK 1458 select DEBUG_MUTEXES if !PREEMPT_RT 1459 select DEBUG_RT_MUTEXES if PREEMPT_RT 1460 help 1461 This feature enables slowpath testing for w/w mutex users by 1462 injecting additional -EDEADLK wound/backoff cases. Together with 1463 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1464 will test all possible w/w mutex interface abuse with the 1465 exception of simply not acquiring all the required locks. 1466 Note that this feature can introduce significant overhead, so 1467 it really should not be enabled in a production or distro kernel, 1468 even a debug kernel. If you are a driver writer, enable it. If 1469 you are a distro, do not. 1470 1471config DEBUG_RWSEMS 1472 bool "RW Semaphore debugging: basic checks" 1473 depends on DEBUG_KERNEL && !PREEMPT_RT 1474 help 1475 This debugging feature allows mismatched rw semaphore locks 1476 and unlocks to be detected and reported. 1477 1478config DEBUG_LOCK_ALLOC 1479 bool "Lock debugging: detect incorrect freeing of live locks" 1480 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1481 select DEBUG_SPINLOCK 1482 select DEBUG_MUTEXES if !PREEMPT_RT 1483 select DEBUG_RT_MUTEXES if RT_MUTEXES 1484 select LOCKDEP 1485 help 1486 This feature will check whether any held lock (spinlock, rwlock, 1487 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1488 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1489 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1490 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1491 held during task exit. 1492 1493config LOCKDEP 1494 bool 1495 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1496 select STACKTRACE 1497 select KALLSYMS 1498 select KALLSYMS_ALL 1499 1500config LOCKDEP_SMALL 1501 bool 1502 1503config LOCKDEP_BITS 1504 int "Bitsize for MAX_LOCKDEP_ENTRIES" 1505 depends on LOCKDEP && !LOCKDEP_SMALL 1506 range 10 30 1507 default 15 1508 help 1509 Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message. 1510 1511config LOCKDEP_CHAINS_BITS 1512 int "Bitsize for MAX_LOCKDEP_CHAINS" 1513 depends on LOCKDEP && !LOCKDEP_SMALL 1514 range 10 21 1515 default 16 1516 help 1517 Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message. 1518 1519config LOCKDEP_STACK_TRACE_BITS 1520 int "Bitsize for MAX_STACK_TRACE_ENTRIES" 1521 depends on LOCKDEP && !LOCKDEP_SMALL 1522 range 10 30 1523 default 19 1524 help 1525 Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message. 1526 1527config LOCKDEP_STACK_TRACE_HASH_BITS 1528 int "Bitsize for STACK_TRACE_HASH_SIZE" 1529 depends on LOCKDEP && !LOCKDEP_SMALL 1530 range 10 30 1531 default 14 1532 help 1533 Try increasing this value if you need large STACK_TRACE_HASH_SIZE. 1534 1535config LOCKDEP_CIRCULAR_QUEUE_BITS 1536 int "Bitsize for elements in circular_queue struct" 1537 depends on LOCKDEP 1538 range 10 30 1539 default 12 1540 help 1541 Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure. 1542 1543config DEBUG_LOCKDEP 1544 bool "Lock dependency engine debugging" 1545 depends on DEBUG_KERNEL && LOCKDEP 1546 select DEBUG_IRQFLAGS 1547 help 1548 If you say Y here, the lock dependency engine will do 1549 additional runtime checks to debug itself, at the price 1550 of more runtime overhead. 1551 1552config DEBUG_ATOMIC_SLEEP 1553 bool "Sleep inside atomic section checking" 1554 select PREEMPT_COUNT 1555 depends on DEBUG_KERNEL 1556 depends on !ARCH_NO_PREEMPT 1557 help 1558 If you say Y here, various routines which may sleep will become very 1559 noisy if they are called inside atomic sections: when a spinlock is 1560 held, inside an rcu read side critical section, inside preempt disabled 1561 sections, inside an interrupt, etc... 1562 1563config DEBUG_LOCKING_API_SELFTESTS 1564 bool "Locking API boot-time self-tests" 1565 depends on DEBUG_KERNEL 1566 help 1567 Say Y here if you want the kernel to run a short self-test during 1568 bootup. The self-test checks whether common types of locking bugs 1569 are detected by debugging mechanisms or not. (if you disable 1570 lock debugging then those bugs won't be detected of course.) 1571 The following locking APIs are covered: spinlocks, rwlocks, 1572 mutexes and rwsems. 1573 1574config LOCK_TORTURE_TEST 1575 tristate "torture tests for locking" 1576 depends on DEBUG_KERNEL 1577 select TORTURE_TEST 1578 help 1579 This option provides a kernel module that runs torture tests 1580 on kernel locking primitives. The kernel module may be built 1581 after the fact on the running kernel to be tested, if desired. 1582 1583 Say Y here if you want kernel locking-primitive torture tests 1584 to be built into the kernel. 1585 Say M if you want these torture tests to build as a module. 1586 Say N if you are unsure. 1587 1588config WW_MUTEX_SELFTEST 1589 tristate "Wait/wound mutex selftests" 1590 help 1591 This option provides a kernel module that runs tests on the 1592 on the struct ww_mutex locking API. 1593 1594 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1595 with this test harness. 1596 1597 Say M if you want these self tests to build as a module. 1598 Say N if you are unsure. 1599 1600config SCF_TORTURE_TEST 1601 tristate "torture tests for smp_call_function*()" 1602 depends on DEBUG_KERNEL 1603 select TORTURE_TEST 1604 help 1605 This option provides a kernel module that runs torture tests 1606 on the smp_call_function() family of primitives. The kernel 1607 module may be built after the fact on the running kernel to 1608 be tested, if desired. 1609 1610config CSD_LOCK_WAIT_DEBUG 1611 bool "Debugging for csd_lock_wait(), called from smp_call_function*()" 1612 depends on DEBUG_KERNEL 1613 depends on SMP 1614 depends on 64BIT 1615 default n 1616 help 1617 This option enables debug prints when CPUs are slow to respond 1618 to the smp_call_function*() IPI wrappers. These debug prints 1619 include the IPI handler function currently executing (if any) 1620 and relevant stack traces. 1621 1622config CSD_LOCK_WAIT_DEBUG_DEFAULT 1623 bool "Default csd_lock_wait() debugging on at boot time" 1624 depends on CSD_LOCK_WAIT_DEBUG 1625 depends on 64BIT 1626 default n 1627 help 1628 This option causes the csdlock_debug= kernel boot parameter to 1629 default to 1 (basic debugging) instead of 0 (no debugging). 1630 1631endmenu # lock debugging 1632 1633config TRACE_IRQFLAGS 1634 depends on TRACE_IRQFLAGS_SUPPORT 1635 bool 1636 help 1637 Enables hooks to interrupt enabling and disabling for 1638 either tracing or lock debugging. 1639 1640config TRACE_IRQFLAGS_NMI 1641 def_bool y 1642 depends on TRACE_IRQFLAGS 1643 depends on TRACE_IRQFLAGS_NMI_SUPPORT 1644 1645config NMI_CHECK_CPU 1646 bool "Debugging for CPUs failing to respond to backtrace requests" 1647 depends on DEBUG_KERNEL 1648 depends on X86 1649 default n 1650 help 1651 Enables debug prints when a CPU fails to respond to a given 1652 backtrace NMI. These prints provide some reasons why a CPU 1653 might legitimately be failing to respond, for example, if it 1654 is offline of if ignore_nmis is set. 1655 1656config DEBUG_IRQFLAGS 1657 bool "Debug IRQ flag manipulation" 1658 help 1659 Enables checks for potentially unsafe enabling or disabling of 1660 interrupts, such as calling raw_local_irq_restore() when interrupts 1661 are enabled. 1662 1663config STACKTRACE 1664 bool "Stack backtrace support" 1665 depends on STACKTRACE_SUPPORT 1666 help 1667 This option causes the kernel to create a /proc/pid/stack for 1668 every process, showing its current stack trace. 1669 It is also used by various kernel debugging features that require 1670 stack trace generation. 1671 1672config WARN_ALL_UNSEEDED_RANDOM 1673 bool "Warn for all uses of unseeded randomness" 1674 default n 1675 help 1676 Some parts of the kernel contain bugs relating to their use of 1677 cryptographically secure random numbers before it's actually possible 1678 to generate those numbers securely. This setting ensures that these 1679 flaws don't go unnoticed, by enabling a message, should this ever 1680 occur. This will allow people with obscure setups to know when things 1681 are going wrong, so that they might contact developers about fixing 1682 it. 1683 1684 Unfortunately, on some models of some architectures getting 1685 a fully seeded CRNG is extremely difficult, and so this can 1686 result in dmesg getting spammed for a surprisingly long 1687 time. This is really bad from a security perspective, and 1688 so architecture maintainers really need to do what they can 1689 to get the CRNG seeded sooner after the system is booted. 1690 However, since users cannot do anything actionable to 1691 address this, by default this option is disabled. 1692 1693 Say Y here if you want to receive warnings for all uses of 1694 unseeded randomness. This will be of use primarily for 1695 those developers interested in improving the security of 1696 Linux kernels running on their architecture (or 1697 subarchitecture). 1698 1699config DEBUG_KOBJECT 1700 bool "kobject debugging" 1701 depends on DEBUG_KERNEL 1702 help 1703 If you say Y here, some extra kobject debugging messages will be sent 1704 to the syslog. 1705 1706config DEBUG_KOBJECT_RELEASE 1707 bool "kobject release debugging" 1708 depends on DEBUG_OBJECTS_TIMERS 1709 help 1710 kobjects are reference counted objects. This means that their 1711 last reference count put is not predictable, and the kobject can 1712 live on past the point at which a driver decides to drop its 1713 initial reference to the kobject gained on allocation. An 1714 example of this would be a struct device which has just been 1715 unregistered. 1716 1717 However, some buggy drivers assume that after such an operation, 1718 the memory backing the kobject can be immediately freed. This 1719 goes completely against the principles of a refcounted object. 1720 1721 If you say Y here, the kernel will delay the release of kobjects 1722 on the last reference count to improve the visibility of this 1723 kind of kobject release bug. 1724 1725config HAVE_DEBUG_BUGVERBOSE 1726 bool 1727 1728menu "Debug kernel data structures" 1729 1730config DEBUG_LIST 1731 bool "Debug linked list manipulation" 1732 depends on DEBUG_KERNEL 1733 select LIST_HARDENED 1734 help 1735 Enable this to turn on extended checks in the linked-list walking 1736 routines. 1737 1738 This option trades better quality error reports for performance, and 1739 is more suitable for kernel debugging. If you care about performance, 1740 you should only enable CONFIG_LIST_HARDENED instead. 1741 1742 If unsure, say N. 1743 1744config DEBUG_PLIST 1745 bool "Debug priority linked list manipulation" 1746 depends on DEBUG_KERNEL 1747 help 1748 Enable this to turn on extended checks in the priority-ordered 1749 linked-list (plist) walking routines. This checks the entire 1750 list multiple times during each manipulation. 1751 1752 If unsure, say N. 1753 1754config DEBUG_SG 1755 bool "Debug SG table operations" 1756 depends on DEBUG_KERNEL 1757 help 1758 Enable this to turn on checks on scatter-gather tables. This can 1759 help find problems with drivers that do not properly initialize 1760 their sg tables. 1761 1762 If unsure, say N. 1763 1764config DEBUG_NOTIFIERS 1765 bool "Debug notifier call chains" 1766 depends on DEBUG_KERNEL 1767 help 1768 Enable this to turn on sanity checking for notifier call chains. 1769 This is most useful for kernel developers to make sure that 1770 modules properly unregister themselves from notifier chains. 1771 This is a relatively cheap check but if you care about maximum 1772 performance, say N. 1773 1774config DEBUG_CLOSURES 1775 bool "Debug closures (bcache async widgits)" 1776 depends on CLOSURES 1777 select DEBUG_FS 1778 help 1779 Keeps all active closures in a linked list and provides a debugfs 1780 interface to list them, which makes it possible to see asynchronous 1781 operations that get stuck. 1782 1783config DEBUG_MAPLE_TREE 1784 bool "Debug maple trees" 1785 depends on DEBUG_KERNEL 1786 help 1787 Enable maple tree debugging information and extra validations. 1788 1789 If unsure, say N. 1790 1791endmenu 1792 1793source "kernel/rcu/Kconfig.debug" 1794 1795config DEBUG_WQ_FORCE_RR_CPU 1796 bool "Force round-robin CPU selection for unbound work items" 1797 depends on DEBUG_KERNEL 1798 default n 1799 help 1800 Workqueue used to implicitly guarantee that work items queued 1801 without explicit CPU specified are put on the local CPU. This 1802 guarantee is no longer true and while local CPU is still 1803 preferred work items may be put on foreign CPUs. Kernel 1804 parameter "workqueue.debug_force_rr_cpu" is added to force 1805 round-robin CPU selection to flush out usages which depend on the 1806 now broken guarantee. This config option enables the debug 1807 feature by default. When enabled, memory and cache locality will 1808 be impacted. 1809 1810config CPU_HOTPLUG_STATE_CONTROL 1811 bool "Enable CPU hotplug state control" 1812 depends on DEBUG_KERNEL 1813 depends on HOTPLUG_CPU 1814 default n 1815 help 1816 Allows to write steps between "offline" and "online" to the CPUs 1817 sysfs target file so states can be stepped granular. This is a debug 1818 option for now as the hotplug machinery cannot be stopped and 1819 restarted at arbitrary points yet. 1820 1821 Say N if your are unsure. 1822 1823config LATENCYTOP 1824 bool "Latency measuring infrastructure" 1825 depends on DEBUG_KERNEL 1826 depends on STACKTRACE_SUPPORT 1827 depends on PROC_FS 1828 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 1829 select KALLSYMS 1830 select KALLSYMS_ALL 1831 select STACKTRACE 1832 select SCHEDSTATS 1833 help 1834 Enable this option if you want to use the LatencyTOP tool 1835 to find out which userspace is blocking on what kernel operations. 1836 1837config DEBUG_CGROUP_REF 1838 bool "Disable inlining of cgroup css reference count functions" 1839 depends on DEBUG_KERNEL 1840 depends on CGROUPS 1841 depends on KPROBES 1842 default n 1843 help 1844 Force cgroup css reference count functions to not be inlined so 1845 that they can be kprobed for debugging. 1846 1847source "kernel/trace/Kconfig" 1848 1849config PROVIDE_OHCI1394_DMA_INIT 1850 bool "Remote debugging over FireWire early on boot" 1851 depends on PCI && X86 1852 help 1853 If you want to debug problems which hang or crash the kernel early 1854 on boot and the crashing machine has a FireWire port, you can use 1855 this feature to remotely access the memory of the crashed machine 1856 over FireWire. This employs remote DMA as part of the OHCI1394 1857 specification which is now the standard for FireWire controllers. 1858 1859 With remote DMA, you can monitor the printk buffer remotely using 1860 firescope and access all memory below 4GB using fireproxy from gdb. 1861 Even controlling a kernel debugger is possible using remote DMA. 1862 1863 Usage: 1864 1865 If ohci1394_dma=early is used as boot parameter, it will initialize 1866 all OHCI1394 controllers which are found in the PCI config space. 1867 1868 As all changes to the FireWire bus such as enabling and disabling 1869 devices cause a bus reset and thereby disable remote DMA for all 1870 devices, be sure to have the cable plugged and FireWire enabled on 1871 the debugging host before booting the debug target for debugging. 1872 1873 This code (~1k) is freed after boot. By then, the firewire stack 1874 in charge of the OHCI-1394 controllers should be used instead. 1875 1876 See Documentation/core-api/debugging-via-ohci1394.rst for more information. 1877 1878source "samples/Kconfig" 1879 1880config ARCH_HAS_DEVMEM_IS_ALLOWED 1881 bool 1882 1883config STRICT_DEVMEM 1884 bool "Filter access to /dev/mem" 1885 depends on MMU && DEVMEM 1886 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED 1887 default y if PPC || X86 || ARM64 || S390 1888 help 1889 If this option is disabled, you allow userspace (root) access to all 1890 of memory, including kernel and userspace memory. Accidental 1891 access to this is obviously disastrous, but specific access can 1892 be used by people debugging the kernel. Note that with PAT support 1893 enabled, even in this case there are restrictions on /dev/mem 1894 use due to the cache aliasing requirements. 1895 1896 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 1897 file only allows userspace access to PCI space and the BIOS code and 1898 data regions. This is sufficient for dosemu and X and all common 1899 users of /dev/mem. 1900 1901 If in doubt, say Y. 1902 1903config IO_STRICT_DEVMEM 1904 bool "Filter I/O access to /dev/mem" 1905 depends on STRICT_DEVMEM 1906 help 1907 If this option is disabled, you allow userspace (root) access to all 1908 io-memory regardless of whether a driver is actively using that 1909 range. Accidental access to this is obviously disastrous, but 1910 specific access can be used by people debugging kernel drivers. 1911 1912 If this option is switched on, the /dev/mem file only allows 1913 userspace access to *idle* io-memory ranges (see /proc/iomem) This 1914 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 1915 if the driver using a given range cannot be disabled. 1916 1917 If in doubt, say Y. 1918 1919menu "$(SRCARCH) Debugging" 1920 1921source "arch/$(SRCARCH)/Kconfig.debug" 1922 1923endmenu 1924 1925menu "Kernel Testing and Coverage" 1926 1927source "lib/kunit/Kconfig" 1928 1929config NOTIFIER_ERROR_INJECTION 1930 tristate "Notifier error injection" 1931 depends on DEBUG_KERNEL 1932 select DEBUG_FS 1933 help 1934 This option provides the ability to inject artificial errors to 1935 specified notifier chain callbacks. It is useful to test the error 1936 handling of notifier call chain failures. 1937 1938 Say N if unsure. 1939 1940config PM_NOTIFIER_ERROR_INJECT 1941 tristate "PM notifier error injection module" 1942 depends on PM && NOTIFIER_ERROR_INJECTION 1943 default m if PM_DEBUG 1944 help 1945 This option provides the ability to inject artificial errors to 1946 PM notifier chain callbacks. It is controlled through debugfs 1947 interface /sys/kernel/debug/notifier-error-inject/pm 1948 1949 If the notifier call chain should be failed with some events 1950 notified, write the error code to "actions/<notifier event>/error". 1951 1952 Example: Inject PM suspend error (-12 = -ENOMEM) 1953 1954 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1955 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1956 # echo mem > /sys/power/state 1957 bash: echo: write error: Cannot allocate memory 1958 1959 To compile this code as a module, choose M here: the module will 1960 be called pm-notifier-error-inject. 1961 1962 If unsure, say N. 1963 1964config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1965 tristate "OF reconfig notifier error injection module" 1966 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1967 help 1968 This option provides the ability to inject artificial errors to 1969 OF reconfig notifier chain callbacks. It is controlled 1970 through debugfs interface under 1971 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1972 1973 If the notifier call chain should be failed with some events 1974 notified, write the error code to "actions/<notifier event>/error". 1975 1976 To compile this code as a module, choose M here: the module will 1977 be called of-reconfig-notifier-error-inject. 1978 1979 If unsure, say N. 1980 1981config NETDEV_NOTIFIER_ERROR_INJECT 1982 tristate "Netdev notifier error injection module" 1983 depends on NET && NOTIFIER_ERROR_INJECTION 1984 help 1985 This option provides the ability to inject artificial errors to 1986 netdevice notifier chain callbacks. It is controlled through debugfs 1987 interface /sys/kernel/debug/notifier-error-inject/netdev 1988 1989 If the notifier call chain should be failed with some events 1990 notified, write the error code to "actions/<notifier event>/error". 1991 1992 Example: Inject netdevice mtu change error (-22 = -EINVAL) 1993 1994 # cd /sys/kernel/debug/notifier-error-inject/netdev 1995 # echo -22 > actions/NETDEV_CHANGEMTU/error 1996 # ip link set eth0 mtu 1024 1997 RTNETLINK answers: Invalid argument 1998 1999 To compile this code as a module, choose M here: the module will 2000 be called netdev-notifier-error-inject. 2001 2002 If unsure, say N. 2003 2004config FUNCTION_ERROR_INJECTION 2005 bool "Fault-injections of functions" 2006 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 2007 help 2008 Add fault injections into various functions that are annotated with 2009 ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return 2010 value of these functions. This is useful to test error paths of code. 2011 2012 If unsure, say N 2013 2014config FAULT_INJECTION 2015 bool "Fault-injection framework" 2016 depends on DEBUG_KERNEL 2017 help 2018 Provide fault-injection framework. 2019 For more details, see Documentation/fault-injection/. 2020 2021config FAILSLAB 2022 bool "Fault-injection capability for kmalloc" 2023 depends on FAULT_INJECTION 2024 help 2025 Provide fault-injection capability for kmalloc. 2026 2027config FAIL_PAGE_ALLOC 2028 bool "Fault-injection capability for alloc_pages()" 2029 depends on FAULT_INJECTION 2030 help 2031 Provide fault-injection capability for alloc_pages(). 2032 2033config FAULT_INJECTION_USERCOPY 2034 bool "Fault injection capability for usercopy functions" 2035 depends on FAULT_INJECTION 2036 help 2037 Provides fault-injection capability to inject failures 2038 in usercopy functions (copy_from_user(), get_user(), ...). 2039 2040config FAIL_MAKE_REQUEST 2041 bool "Fault-injection capability for disk IO" 2042 depends on FAULT_INJECTION && BLOCK 2043 help 2044 Provide fault-injection capability for disk IO. 2045 2046config FAIL_IO_TIMEOUT 2047 bool "Fault-injection capability for faking disk interrupts" 2048 depends on FAULT_INJECTION && BLOCK 2049 help 2050 Provide fault-injection capability on end IO handling. This 2051 will make the block layer "forget" an interrupt as configured, 2052 thus exercising the error handling. 2053 2054 Only works with drivers that use the generic timeout handling, 2055 for others it won't do anything. 2056 2057config FAIL_FUTEX 2058 bool "Fault-injection capability for futexes" 2059 select DEBUG_FS 2060 depends on FAULT_INJECTION && FUTEX 2061 help 2062 Provide fault-injection capability for futexes. 2063 2064config FAULT_INJECTION_DEBUG_FS 2065 bool "Debugfs entries for fault-injection capabilities" 2066 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 2067 help 2068 Enable configuration of fault-injection capabilities via debugfs. 2069 2070config FAIL_FUNCTION 2071 bool "Fault-injection capability for functions" 2072 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 2073 help 2074 Provide function-based fault-injection capability. 2075 This will allow you to override a specific function with a return 2076 with given return value. As a result, function caller will see 2077 an error value and have to handle it. This is useful to test the 2078 error handling in various subsystems. 2079 2080config FAIL_MMC_REQUEST 2081 bool "Fault-injection capability for MMC IO" 2082 depends on FAULT_INJECTION_DEBUG_FS && MMC 2083 help 2084 Provide fault-injection capability for MMC IO. 2085 This will make the mmc core return data errors. This is 2086 useful to test the error handling in the mmc block device 2087 and to test how the mmc host driver handles retries from 2088 the block device. 2089 2090config FAIL_SUNRPC 2091 bool "Fault-injection capability for SunRPC" 2092 depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG 2093 help 2094 Provide fault-injection capability for SunRPC and 2095 its consumers. 2096 2097config FAIL_SKB_REALLOC 2098 bool "Fault-injection capability forcing skb to reallocate" 2099 depends on FAULT_INJECTION_DEBUG_FS 2100 help 2101 Provide fault-injection capability that forces the skb to be 2102 reallocated, catching possible invalid pointers to the skb. 2103 2104 For more information, check 2105 Documentation/dev-tools/fault-injection/fault-injection.rst 2106 2107config FAULT_INJECTION_CONFIGFS 2108 bool "Configfs interface for fault-injection capabilities" 2109 depends on FAULT_INJECTION 2110 select CONFIGFS_FS 2111 help 2112 This option allows configfs-based drivers to dynamically configure 2113 fault-injection via configfs. Each parameter for driver-specific 2114 fault-injection can be made visible as a configfs attribute in a 2115 configfs group. 2116 2117 2118config FAULT_INJECTION_STACKTRACE_FILTER 2119 bool "stacktrace filter for fault-injection capabilities" 2120 depends on FAULT_INJECTION 2121 depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT 2122 select STACKTRACE 2123 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 2124 help 2125 Provide stacktrace filter for fault-injection capabilities 2126 2127config ARCH_HAS_KCOV 2128 bool 2129 help 2130 An architecture should select this when it can successfully 2131 build and run with CONFIG_KCOV. This typically requires 2132 disabling instrumentation for some early boot code. 2133 2134config CC_HAS_SANCOV_TRACE_PC 2135 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 2136 2137 2138config KCOV 2139 bool "Code coverage for fuzzing" 2140 depends on ARCH_HAS_KCOV 2141 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 2142 depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \ 2143 GCC_VERSION >= 120000 || CC_IS_CLANG 2144 select DEBUG_FS 2145 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 2146 select OBJTOOL if HAVE_NOINSTR_HACK 2147 help 2148 KCOV exposes kernel code coverage information in a form suitable 2149 for coverage-guided fuzzing (randomized testing). 2150 2151 For more details, see Documentation/dev-tools/kcov.rst. 2152 2153config KCOV_ENABLE_COMPARISONS 2154 bool "Enable comparison operands collection by KCOV" 2155 depends on KCOV 2156 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 2157 help 2158 KCOV also exposes operands of every comparison in the instrumented 2159 code along with operand sizes and PCs of the comparison instructions. 2160 These operands can be used by fuzzing engines to improve the quality 2161 of fuzzing coverage. 2162 2163config KCOV_INSTRUMENT_ALL 2164 bool "Instrument all code by default" 2165 depends on KCOV 2166 default y 2167 help 2168 If you are doing generic system call fuzzing (like e.g. syzkaller), 2169 then you will want to instrument the whole kernel and you should 2170 say y here. If you are doing more targeted fuzzing (like e.g. 2171 filesystem fuzzing with AFL) then you will want to enable coverage 2172 for more specific subsets of files, and should say n here. 2173 2174config KCOV_IRQ_AREA_SIZE 2175 hex "Size of interrupt coverage collection area in words" 2176 depends on KCOV 2177 default 0x40000 2178 help 2179 KCOV uses preallocated per-cpu areas to collect coverage from 2180 soft interrupts. This specifies the size of those areas in the 2181 number of unsigned long words. 2182 2183config KCOV_SELFTEST 2184 bool "Perform short selftests on boot" 2185 depends on KCOV 2186 help 2187 Run short KCOV coverage collection selftests on boot. 2188 On test failure, causes the kernel to panic. Recommended to be 2189 enabled, ensuring critical functionality works as intended. 2190 2191menuconfig RUNTIME_TESTING_MENU 2192 bool "Runtime Testing" 2193 default y 2194 2195if RUNTIME_TESTING_MENU 2196 2197config TEST_DHRY 2198 tristate "Dhrystone benchmark test" 2199 help 2200 Enable this to include the Dhrystone 2.1 benchmark. This test 2201 calculates the number of Dhrystones per second, and the number of 2202 DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided 2203 by 1757 (the number of Dhrystones per second obtained on the VAX 2204 11/780, nominally a 1 MIPS machine). 2205 2206 To run the benchmark, it needs to be enabled explicitly, either from 2207 the kernel command line (when built-in), or from userspace (when 2208 built-in or modular). 2209 2210 Run once during kernel boot: 2211 2212 test_dhry.run 2213 2214 Set number of iterations from kernel command line: 2215 2216 test_dhry.iterations=<n> 2217 2218 Set number of iterations from userspace: 2219 2220 echo <n> > /sys/module/test_dhry/parameters/iterations 2221 2222 Trigger manual run from userspace: 2223 2224 echo y > /sys/module/test_dhry/parameters/run 2225 2226 If the number of iterations is <= 0, the test will devise a suitable 2227 number of iterations (test runs for at least 2s) automatically. 2228 This process takes ca. 4s. 2229 2230 If unsure, say N. 2231 2232config LKDTM 2233 tristate "Linux Kernel Dump Test Tool Module" 2234 depends on DEBUG_FS 2235 help 2236 This module enables testing of the different dumping mechanisms by 2237 inducing system failures at predefined crash points. 2238 If you don't need it: say N 2239 Choose M here to compile this code as a module. The module will be 2240 called lkdtm. 2241 2242 Documentation on how to use the module can be found in 2243 Documentation/fault-injection/provoke-crashes.rst 2244 2245config CPUMASK_KUNIT_TEST 2246 tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS 2247 depends on KUNIT 2248 default KUNIT_ALL_TESTS 2249 help 2250 Enable to turn on cpumask tests, running at boot or module load time. 2251 2252 For more information on KUnit and unit tests in general, please refer 2253 to the KUnit documentation in Documentation/dev-tools/kunit/. 2254 2255 If unsure, say N. 2256 2257config TEST_LIST_SORT 2258 tristate "Linked list sorting test" if !KUNIT_ALL_TESTS 2259 depends on KUNIT 2260 default KUNIT_ALL_TESTS 2261 help 2262 Enable this to turn on 'list_sort()' function test. This test is 2263 executed only once during system boot (so affects only boot time), 2264 or at module load time. 2265 2266 If unsure, say N. 2267 2268config TEST_MIN_HEAP 2269 tristate "Min heap test" 2270 depends on DEBUG_KERNEL || m 2271 help 2272 Enable this to turn on min heap function tests. This test is 2273 executed only once during system boot (so affects only boot time), 2274 or at module load time. 2275 2276 If unsure, say N. 2277 2278config TEST_SORT 2279 tristate "Array-based sort test" if !KUNIT_ALL_TESTS 2280 depends on KUNIT 2281 default KUNIT_ALL_TESTS 2282 help 2283 This option enables the self-test function of 'sort()' at boot, 2284 or at module load time. 2285 2286 If unsure, say N. 2287 2288config TEST_DIV64 2289 tristate "64bit/32bit division and modulo test" 2290 depends on DEBUG_KERNEL || m 2291 help 2292 Enable this to turn on 'do_div()' function test. This test is 2293 executed only once during system boot (so affects only boot time), 2294 or at module load time. 2295 2296 If unsure, say N. 2297 2298config TEST_MULDIV64 2299 tristate "mul_u64_u64_div_u64() test" 2300 depends on DEBUG_KERNEL || m 2301 help 2302 Enable this to turn on 'mul_u64_u64_div_u64()' function test. 2303 This test is executed only once during system boot (so affects 2304 only boot time), or at module load time. 2305 2306 If unsure, say N. 2307 2308config TEST_IOV_ITER 2309 tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS 2310 depends on KUNIT 2311 depends on MMU 2312 default KUNIT_ALL_TESTS 2313 help 2314 Enable this to turn on testing of the operation of the I/O iterator 2315 (iov_iter). This test is executed only once during system boot (so 2316 affects only boot time), or at module load time. 2317 2318 If unsure, say N. 2319 2320config KPROBES_SANITY_TEST 2321 tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS 2322 depends on DEBUG_KERNEL 2323 depends on KPROBES 2324 depends on KUNIT 2325 select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 2326 default KUNIT_ALL_TESTS 2327 help 2328 This option provides for testing basic kprobes functionality on 2329 boot. Samples of kprobe and kretprobe are inserted and 2330 verified for functionality. 2331 2332 Say N if you are unsure. 2333 2334config FPROBE_SANITY_TEST 2335 bool "Self test for fprobe" 2336 depends on DEBUG_KERNEL 2337 depends on FPROBE 2338 depends on KUNIT=y 2339 help 2340 This option will enable testing the fprobe when the system boot. 2341 A series of tests are made to verify that the fprobe is functioning 2342 properly. 2343 2344 Say N if you are unsure. 2345 2346config BACKTRACE_SELF_TEST 2347 tristate "Self test for the backtrace code" 2348 depends on DEBUG_KERNEL 2349 help 2350 This option provides a kernel module that can be used to test 2351 the kernel stack backtrace code. This option is not useful 2352 for distributions or general kernels, but only for kernel 2353 developers working on architecture code. 2354 2355 Note that if you want to also test saved backtraces, you will 2356 have to enable STACKTRACE as well. 2357 2358 Say N if you are unsure. 2359 2360config TEST_REF_TRACKER 2361 tristate "Self test for reference tracker" 2362 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT 2363 select REF_TRACKER 2364 help 2365 This option provides a kernel module performing tests 2366 using reference tracker infrastructure. 2367 2368 Say N if you are unsure. 2369 2370config RBTREE_TEST 2371 tristate "Red-Black tree test" 2372 depends on DEBUG_KERNEL 2373 help 2374 A benchmark measuring the performance of the rbtree library. 2375 Also includes rbtree invariant checks. 2376 2377config REED_SOLOMON_TEST 2378 tristate "Reed-Solomon library test" 2379 depends on DEBUG_KERNEL || m 2380 select REED_SOLOMON 2381 select REED_SOLOMON_ENC16 2382 select REED_SOLOMON_DEC16 2383 help 2384 This option enables the self-test function of rslib at boot, 2385 or at module load time. 2386 2387 If unsure, say N. 2388 2389config INTERVAL_TREE_TEST 2390 tristate "Interval tree test" 2391 depends on DEBUG_KERNEL 2392 select INTERVAL_TREE 2393 help 2394 A benchmark measuring the performance of the interval tree library 2395 2396config PERCPU_TEST 2397 tristate "Per cpu operations test" 2398 depends on m && DEBUG_KERNEL 2399 help 2400 Enable this option to build test module which validates per-cpu 2401 operations. 2402 2403 If unsure, say N. 2404 2405config ATOMIC64_SELFTEST 2406 tristate "Perform an atomic64_t self-test" 2407 help 2408 Enable this option to test the atomic64_t functions at boot or 2409 at module load time. 2410 2411 If unsure, say N. 2412 2413config ASYNC_RAID6_TEST 2414 tristate "Self test for hardware accelerated raid6 recovery" 2415 depends on ASYNC_RAID6_RECOV 2416 select ASYNC_MEMCPY 2417 help 2418 This is a one-shot self test that permutes through the 2419 recovery of all the possible two disk failure scenarios for a 2420 N-disk array. Recovery is performed with the asynchronous 2421 raid6 recovery routines, and will optionally use an offload 2422 engine if one is available. 2423 2424 If unsure, say N. 2425 2426config TEST_HEXDUMP 2427 tristate "Test functions located in the hexdump module at runtime" 2428 2429config STRING_KUNIT_TEST 2430 tristate "KUnit test string functions at runtime" if !KUNIT_ALL_TESTS 2431 depends on KUNIT 2432 default KUNIT_ALL_TESTS 2433 2434config STRING_HELPERS_KUNIT_TEST 2435 tristate "KUnit test string helpers at runtime" if !KUNIT_ALL_TESTS 2436 depends on KUNIT 2437 default KUNIT_ALL_TESTS 2438 2439config TEST_KSTRTOX 2440 tristate "Test kstrto*() family of functions at runtime" 2441 2442config TEST_PRINTF 2443 tristate "Test printf() family of functions at runtime" 2444 2445config TEST_SCANF 2446 tristate "Test scanf() family of functions at runtime" 2447 2448config TEST_BITMAP 2449 tristate "Test bitmap_*() family of functions at runtime" 2450 help 2451 Enable this option to test the bitmap functions at boot. 2452 2453 If unsure, say N. 2454 2455config TEST_UUID 2456 tristate "Test functions located in the uuid module at runtime" 2457 2458config TEST_XARRAY 2459 tristate "Test the XArray code at runtime" 2460 2461config TEST_MAPLE_TREE 2462 tristate "Test the Maple Tree code at runtime or module load" 2463 help 2464 Enable this option to test the maple tree code functions at boot, or 2465 when the module is loaded. Enable "Debug Maple Trees" will enable 2466 more verbose output on failures. 2467 2468 If unsure, say N. 2469 2470config TEST_RHASHTABLE 2471 tristate "Perform selftest on resizable hash table" 2472 help 2473 Enable this option to test the rhashtable functions at boot. 2474 2475 If unsure, say N. 2476 2477config TEST_IDA 2478 tristate "Perform selftest on IDA functions" 2479 2480config TEST_PARMAN 2481 tristate "Perform selftest on priority array manager" 2482 depends on PARMAN 2483 help 2484 Enable this option to test priority array manager on boot 2485 (or module load). 2486 2487 If unsure, say N. 2488 2489config TEST_IRQ_TIMINGS 2490 bool "IRQ timings selftest" 2491 depends on IRQ_TIMINGS 2492 help 2493 Enable this option to test the irq timings code on boot. 2494 2495 If unsure, say N. 2496 2497config TEST_LKM 2498 tristate "Test module loading with 'hello world' module" 2499 depends on m 2500 help 2501 This builds the "test_module" module that emits "Hello, world" 2502 on printk when loaded. It is designed to be used for basic 2503 evaluation of the module loading subsystem (for example when 2504 validating module verification). It lacks any extra dependencies, 2505 and will not normally be loaded by the system unless explicitly 2506 requested by name. 2507 2508 If unsure, say N. 2509 2510config TEST_BITOPS 2511 tristate "Test module for compilation of bitops operations" 2512 help 2513 This builds the "test_bitops" module that is much like the 2514 TEST_LKM module except that it does a basic exercise of the 2515 set/clear_bit macros and get_count_order/long to make sure there are 2516 no compiler warnings from C=1 sparse checker or -Wextra 2517 compilations. It has no dependencies and doesn't run or load unless 2518 explicitly requested by name. for example: modprobe test_bitops. 2519 2520 If unsure, say N. 2521 2522config TEST_VMALLOC 2523 tristate "Test module for stress/performance analysis of vmalloc allocator" 2524 default n 2525 depends on MMU 2526 depends on m 2527 help 2528 This builds the "test_vmalloc" module that should be used for 2529 stress and performance analysis. So, any new change for vmalloc 2530 subsystem can be evaluated from performance and stability point 2531 of view. 2532 2533 If unsure, say N. 2534 2535config TEST_BPF 2536 tristate "Test BPF filter functionality" 2537 depends on m && NET 2538 help 2539 This builds the "test_bpf" module that runs various test vectors 2540 against the BPF interpreter or BPF JIT compiler depending on the 2541 current setting. This is in particular useful for BPF JIT compiler 2542 development, but also to run regression tests against changes in 2543 the interpreter code. It also enables test stubs for eBPF maps and 2544 verifier used by user space verifier testsuite. 2545 2546 If unsure, say N. 2547 2548config TEST_BLACKHOLE_DEV 2549 tristate "Test blackhole netdev functionality" 2550 depends on m && NET 2551 help 2552 This builds the "test_blackhole_dev" module that validates the 2553 data path through this blackhole netdev. 2554 2555 If unsure, say N. 2556 2557config FIND_BIT_BENCHMARK 2558 tristate "Test find_bit functions" 2559 help 2560 This builds the "test_find_bit" module that measure find_*_bit() 2561 functions performance. 2562 2563 If unsure, say N. 2564 2565config TEST_FIRMWARE 2566 tristate "Test firmware loading via userspace interface" 2567 depends on FW_LOADER 2568 help 2569 This builds the "test_firmware" module that creates a userspace 2570 interface for testing firmware loading. This can be used to 2571 control the triggering of firmware loading without needing an 2572 actual firmware-using device. The contents can be rechecked by 2573 userspace. 2574 2575 If unsure, say N. 2576 2577config TEST_SYSCTL 2578 tristate "sysctl test driver" 2579 depends on PROC_SYSCTL 2580 help 2581 This builds the "test_sysctl" module. This driver enables to test the 2582 proc sysctl interfaces available to drivers safely without affecting 2583 production knobs which might alter system functionality. 2584 2585 If unsure, say N. 2586 2587config BITFIELD_KUNIT 2588 tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS 2589 depends on KUNIT 2590 default KUNIT_ALL_TESTS 2591 help 2592 Enable this option to test the bitfield functions at boot. 2593 2594 KUnit tests run during boot and output the results to the debug log 2595 in TAP format (http://testanything.org/). Only useful for kernel devs 2596 running the KUnit test harness, and not intended for inclusion into a 2597 production build. 2598 2599 For more information on KUnit and unit tests in general please refer 2600 to the KUnit documentation in Documentation/dev-tools/kunit/. 2601 2602 If unsure, say N. 2603 2604config CHECKSUM_KUNIT 2605 tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS 2606 depends on KUNIT 2607 default KUNIT_ALL_TESTS 2608 help 2609 Enable this option to test the checksum functions at boot. 2610 2611 KUnit tests run during boot and output the results to the debug log 2612 in TAP format (http://testanything.org/). Only useful for kernel devs 2613 running the KUnit test harness, and not intended for inclusion into a 2614 production build. 2615 2616 For more information on KUnit and unit tests in general please refer 2617 to the KUnit documentation in Documentation/dev-tools/kunit/. 2618 2619 If unsure, say N. 2620 2621config HASH_KUNIT_TEST 2622 tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS 2623 depends on KUNIT 2624 default KUNIT_ALL_TESTS 2625 help 2626 Enable this option to test the kernel's string (<linux/stringhash.h>), and 2627 integer (<linux/hash.h>) hash functions on boot. 2628 2629 KUnit tests run during boot and output the results to the debug log 2630 in TAP format (https://testanything.org/). Only useful for kernel devs 2631 running the KUnit test harness, and not intended for inclusion into a 2632 production build. 2633 2634 For more information on KUnit and unit tests in general please refer 2635 to the KUnit documentation in Documentation/dev-tools/kunit/. 2636 2637 This is intended to help people writing architecture-specific 2638 optimized versions. If unsure, say N. 2639 2640config RESOURCE_KUNIT_TEST 2641 tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS 2642 depends on KUNIT 2643 default KUNIT_ALL_TESTS 2644 select GET_FREE_REGION 2645 help 2646 This builds the resource API unit test. 2647 Tests the logic of API provided by resource.c and ioport.h. 2648 For more information on KUnit and unit tests in general please refer 2649 to the KUnit documentation in Documentation/dev-tools/kunit/. 2650 2651 If unsure, say N. 2652 2653config SYSCTL_KUNIT_TEST 2654 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS 2655 depends on KUNIT 2656 default KUNIT_ALL_TESTS 2657 help 2658 This builds the proc sysctl unit test, which runs on boot. 2659 Tests the API contract and implementation correctness of sysctl. 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 LIST_KUNIT_TEST 2666 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS 2667 depends on KUNIT 2668 default KUNIT_ALL_TESTS 2669 help 2670 This builds the linked list KUnit test suite. 2671 It tests that the API and basic functionality of the list_head type 2672 and associated macros. 2673 2674 KUnit tests run during boot and output the results to the debug log 2675 in TAP format (https://testanything.org/). Only useful for kernel devs 2676 running the KUnit test harness, and not intended for inclusion into a 2677 production build. 2678 2679 For more information on KUnit and unit tests in general please refer 2680 to the KUnit documentation in Documentation/dev-tools/kunit/. 2681 2682 If unsure, say N. 2683 2684config HASHTABLE_KUNIT_TEST 2685 tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS 2686 depends on KUNIT 2687 default KUNIT_ALL_TESTS 2688 help 2689 This builds the hashtable KUnit test suite. 2690 It tests the basic functionality of the API defined in 2691 include/linux/hashtable.h. For more information on KUnit and 2692 unit tests in general please refer to the KUnit documentation 2693 in Documentation/dev-tools/kunit/. 2694 2695 If unsure, say N. 2696 2697config LINEAR_RANGES_TEST 2698 tristate "KUnit test for linear_ranges" 2699 depends on KUNIT 2700 select LINEAR_RANGES 2701 help 2702 This builds the linear_ranges unit test, which runs on boot. 2703 Tests the linear_ranges logic correctness. 2704 For more information on KUnit and unit tests in general please refer 2705 to the KUnit documentation in Documentation/dev-tools/kunit/. 2706 2707 If unsure, say N. 2708 2709config CMDLINE_KUNIT_TEST 2710 tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS 2711 depends on KUNIT 2712 default KUNIT_ALL_TESTS 2713 help 2714 This builds the cmdline API unit test. 2715 Tests the logic of API provided by cmdline.c. 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 BITS_TEST 2722 tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS 2723 depends on KUNIT 2724 default KUNIT_ALL_TESTS 2725 help 2726 This builds the bits unit test. 2727 Tests the logic of macros defined in bits.h. 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 SLUB_KUNIT_TEST 2734 tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS 2735 depends on SLUB_DEBUG && KUNIT 2736 default KUNIT_ALL_TESTS 2737 help 2738 This builds SLUB allocator unit test. 2739 Tests SLUB cache debugging functionality. 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 RATIONAL_KUNIT_TEST 2746 tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS 2747 depends on KUNIT && RATIONAL 2748 default KUNIT_ALL_TESTS 2749 help 2750 This builds the rational math unit test. 2751 For more information on KUnit and unit tests in general please refer 2752 to the KUnit documentation in Documentation/dev-tools/kunit/. 2753 2754 If unsure, say N. 2755 2756config MEMCPY_KUNIT_TEST 2757 tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS 2758 depends on KUNIT 2759 default KUNIT_ALL_TESTS 2760 help 2761 Builds unit tests for memcpy(), memmove(), and memset() functions. 2762 For more information on KUnit and unit tests in general please refer 2763 to the KUnit documentation in Documentation/dev-tools/kunit/. 2764 2765 If unsure, say N. 2766 2767config IS_SIGNED_TYPE_KUNIT_TEST 2768 tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS 2769 depends on KUNIT 2770 default KUNIT_ALL_TESTS 2771 help 2772 Builds unit tests for the is_signed_type() macro. 2773 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 OVERFLOW_KUNIT_TEST 2780 tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS 2781 depends on KUNIT 2782 default KUNIT_ALL_TESTS 2783 help 2784 Builds unit tests for the check_*_overflow(), size_*(), allocation, and 2785 related functions. 2786 2787 For more information on KUnit and unit tests in general please refer 2788 to the KUnit documentation in Documentation/dev-tools/kunit/. 2789 2790 If unsure, say N. 2791 2792config STACKINIT_KUNIT_TEST 2793 tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS 2794 depends on KUNIT 2795 default KUNIT_ALL_TESTS 2796 help 2797 Test if the kernel is zero-initializing stack variables and 2798 padding. Coverage is controlled by compiler flags, 2799 CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO, 2800 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2801 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2802 2803config FORTIFY_KUNIT_TEST 2804 tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS 2805 depends on KUNIT 2806 default KUNIT_ALL_TESTS 2807 help 2808 Builds unit tests for checking internals of FORTIFY_SOURCE as used 2809 by the str*() and mem*() family of functions. For testing runtime 2810 traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests. 2811 2812config HW_BREAKPOINT_KUNIT_TEST 2813 bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS 2814 depends on HAVE_HW_BREAKPOINT 2815 depends on KUNIT=y 2816 default KUNIT_ALL_TESTS 2817 help 2818 Tests for hw_breakpoint constraints accounting. 2819 2820 If unsure, say N. 2821 2822config SIPHASH_KUNIT_TEST 2823 tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS 2824 depends on KUNIT 2825 default KUNIT_ALL_TESTS 2826 help 2827 Enable this option to test the kernel's siphash (<linux/siphash.h>) hash 2828 functions on boot (or module load). 2829 2830 This is intended to help people writing architecture-specific 2831 optimized versions. If unsure, say N. 2832 2833config USERCOPY_KUNIT_TEST 2834 tristate "KUnit Test for user/kernel boundary protections" 2835 depends on KUNIT 2836 default KUNIT_ALL_TESTS 2837 help 2838 This builds the "usercopy_kunit" module that runs sanity checks 2839 on the copy_to/from_user infrastructure, making sure basic 2840 user/kernel boundary testing is working. 2841 2842config TEST_UDELAY 2843 tristate "udelay test driver" 2844 help 2845 This builds the "udelay_test" module that helps to make sure 2846 that udelay() is working properly. 2847 2848 If unsure, say N. 2849 2850config TEST_STATIC_KEYS 2851 tristate "Test static keys" 2852 depends on m 2853 help 2854 Test the static key interfaces. 2855 2856 If unsure, say N. 2857 2858config TEST_DYNAMIC_DEBUG 2859 tristate "Test DYNAMIC_DEBUG" 2860 depends on DYNAMIC_DEBUG 2861 help 2862 This module registers a tracer callback to count enabled 2863 pr_debugs in a 'do_debugging' function, then alters their 2864 enablements, calls the function, and compares counts. 2865 2866 If unsure, say N. 2867 2868config TEST_KMOD 2869 tristate "kmod stress tester" 2870 depends on m 2871 depends on NETDEVICES && NET_CORE && INET # for TUN 2872 depends on BLOCK 2873 depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS 2874 select TEST_LKM 2875 select XFS_FS 2876 select TUN 2877 select BTRFS_FS 2878 help 2879 Test the kernel's module loading mechanism: kmod. kmod implements 2880 support to load modules using the Linux kernel's usermode helper. 2881 This test provides a series of tests against kmod. 2882 2883 Although technically you can either build test_kmod as a module or 2884 into the kernel we disallow building it into the kernel since 2885 it stress tests request_module() and this will very likely cause 2886 some issues by taking over precious threads available from other 2887 module load requests, ultimately this could be fatal. 2888 2889 To run tests run: 2890 2891 tools/testing/selftests/kmod/kmod.sh --help 2892 2893 If unsure, say N. 2894 2895config TEST_DEBUG_VIRTUAL 2896 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 2897 depends on DEBUG_VIRTUAL 2898 help 2899 Test the kernel's ability to detect incorrect calls to 2900 virt_to_phys() done against the non-linear part of the 2901 kernel's virtual address map. 2902 2903 If unsure, say N. 2904 2905config TEST_MEMCAT_P 2906 tristate "Test memcat_p() helper function" 2907 help 2908 Test the memcat_p() helper for correctly merging two 2909 pointer arrays together. 2910 2911 If unsure, say N. 2912 2913config TEST_OBJAGG 2914 tristate "Perform selftest on object aggreration manager" 2915 default n 2916 depends on OBJAGG 2917 help 2918 Enable this option to test object aggregation manager on boot 2919 (or module load). 2920 2921config TEST_MEMINIT 2922 tristate "Test heap/page initialization" 2923 help 2924 Test if the kernel is zero-initializing heap and page allocations. 2925 This can be useful to test init_on_alloc and init_on_free features. 2926 2927 If unsure, say N. 2928 2929config TEST_HMM 2930 tristate "Test HMM (Heterogeneous Memory Management)" 2931 depends on TRANSPARENT_HUGEPAGE 2932 depends on DEVICE_PRIVATE 2933 select HMM_MIRROR 2934 select MMU_NOTIFIER 2935 help 2936 This is a pseudo device driver solely for testing HMM. 2937 Say M here if you want to build the HMM test module. 2938 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests. 2939 2940 If unsure, say N. 2941 2942config TEST_FREE_PAGES 2943 tristate "Test freeing pages" 2944 help 2945 Test that a memory leak does not occur due to a race between 2946 freeing a block of pages and a speculative page reference. 2947 Loading this module is safe if your kernel has the bug fixed. 2948 If the bug is not fixed, it will leak gigabytes of memory and 2949 probably OOM your system. 2950 2951config TEST_FPU 2952 tristate "Test floating point operations in kernel space" 2953 depends on ARCH_HAS_KERNEL_FPU_SUPPORT && !KCOV_INSTRUMENT_ALL 2954 help 2955 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu 2956 which will trigger a sequence of floating point operations. This is used 2957 for self-testing floating point control register setting in 2958 kernel_fpu_begin(). 2959 2960 If unsure, say N. 2961 2962config TEST_CLOCKSOURCE_WATCHDOG 2963 tristate "Test clocksource watchdog in kernel space" 2964 depends on CLOCKSOURCE_WATCHDOG 2965 help 2966 Enable this option to create a kernel module that will trigger 2967 a test of the clocksource watchdog. This module may be loaded 2968 via modprobe or insmod in which case it will run upon being 2969 loaded, or it may be built in, in which case it will run 2970 shortly after boot. 2971 2972 If unsure, say N. 2973 2974config TEST_OBJPOOL 2975 tristate "Test module for correctness and stress of objpool" 2976 default n 2977 depends on m && DEBUG_KERNEL 2978 help 2979 This builds the "test_objpool" module that should be used for 2980 correctness verification and concurrent testings of objects 2981 allocation and reclamation. 2982 2983 If unsure, say N. 2984 2985endif # RUNTIME_TESTING_MENU 2986 2987config ARCH_USE_MEMTEST 2988 bool 2989 help 2990 An architecture should select this when it uses early_memtest() 2991 during boot process. 2992 2993config MEMTEST 2994 bool "Memtest" 2995 depends on ARCH_USE_MEMTEST 2996 help 2997 This option adds a kernel parameter 'memtest', which allows memtest 2998 to be set and executed. 2999 memtest=0, mean disabled; -- default 3000 memtest=1, mean do 1 test pattern; 3001 ... 3002 memtest=17, mean do 17 test patterns. 3003 If you are unsure how to answer this question, answer N. 3004 3005 3006 3007config HYPERV_TESTING 3008 bool "Microsoft Hyper-V driver testing" 3009 default n 3010 depends on HYPERV && DEBUG_FS 3011 help 3012 Select this option to enable Hyper-V vmbus testing. 3013 3014endmenu # "Kernel Testing and Coverage" 3015 3016menu "Rust hacking" 3017 3018config RUST_DEBUG_ASSERTIONS 3019 bool "Debug assertions" 3020 depends on RUST 3021 help 3022 Enables rustc's `-Cdebug-assertions` codegen option. 3023 3024 This flag lets you turn `cfg(debug_assertions)` conditional 3025 compilation on or off. This can be used to enable extra debugging 3026 code in development but not in production. For example, it controls 3027 the behavior of the standard library's `debug_assert!` macro. 3028 3029 Note that this will apply to all Rust code, including `core`. 3030 3031 If unsure, say N. 3032 3033config RUST_OVERFLOW_CHECKS 3034 bool "Overflow checks" 3035 default y 3036 depends on RUST 3037 help 3038 Enables rustc's `-Coverflow-checks` codegen option. 3039 3040 This flag allows you to control the behavior of runtime integer 3041 overflow. When overflow-checks are enabled, a Rust panic will occur 3042 on overflow. 3043 3044 Note that this will apply to all Rust code, including `core`. 3045 3046 If unsure, say Y. 3047 3048config RUST_BUILD_ASSERT_ALLOW 3049 bool "Allow unoptimized build-time assertions" 3050 depends on RUST 3051 help 3052 Controls how `build_error!` and `build_assert!` are handled during the build. 3053 3054 If calls to them exist in the binary, it may indicate a violated invariant 3055 or that the optimizer failed to verify the invariant during compilation. 3056 3057 This should not happen, thus by default the build is aborted. However, 3058 as an escape hatch, you can choose Y here to ignore them during build 3059 and let the check be carried at runtime (with `panic!` being called if 3060 the check fails). 3061 3062 If unsure, say N. 3063 3064config RUST_KERNEL_DOCTESTS 3065 bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS 3066 depends on RUST && KUNIT=y 3067 default KUNIT_ALL_TESTS 3068 help 3069 This builds the documentation tests of the `kernel` crate 3070 as KUnit tests. 3071 3072 For more information on KUnit and unit tests in general, 3073 please refer to the KUnit documentation in Documentation/dev-tools/kunit/. 3074 3075 If unsure, say N. 3076 3077endmenu # "Rust" 3078 3079endmenu # Kernel hacking 3080 3081config INT_POW_TEST 3082 tristate "Integer exponentiation (int_pow) test" if !KUNIT_ALL_TESTS 3083 depends on KUNIT 3084 default KUNIT_ALL_TESTS 3085 help 3086 This option enables the KUnit test suite for the int_pow function, 3087 which performs integer exponentiation. The test suite is designed to 3088 verify that the implementation of int_pow correctly computes the power 3089 of a given base raised to a given exponent. 3090 3091 Enabling this option will include tests that check various scenarios 3092 and edge cases to ensure the accuracy and reliability of the exponentiation 3093 function. 3094 3095 If unsure, say N 3096