1# SPDX-License-Identifier: GPL-2.0-only 2menu "Kernel hacking" 3 4menu "printk and dmesg options" 5 6config PRINTK_TIME 7 bool "Show timing information on printks" 8 depends on PRINTK 9 help 10 Selecting this option causes time stamps of the printk() 11 messages to be added to the output of the syslog() system 12 call and at the console. 13 14 The timestamp is always recorded internally, and exported 15 to /dev/kmsg. This flag just specifies if the timestamp should 16 be included, not that the timestamp is recorded. 17 18 The behavior is also controlled by the kernel command line 19 parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst 20 21config PRINTK_CALLER 22 bool "Show caller information on printks" 23 depends on PRINTK 24 help 25 Selecting this option causes printk() to add a caller "thread id" (if 26 in task context) or a caller "processor id" (if not in task context) 27 to every message. 28 29 This option is intended for environments where multiple threads 30 concurrently call printk() for many times, for it is difficult to 31 interpret without knowing where these lines (or sometimes individual 32 line which was divided into multiple lines due to race) came from. 33 34 Since toggling after boot makes the code racy, currently there is 35 no option to enable/disable at the kernel command line parameter or 36 sysfs interface. 37 38config STACKTRACE_BUILD_ID 39 bool "Show build ID information in stacktraces" 40 depends on PRINTK 41 help 42 Selecting this option adds build ID information for symbols in 43 stacktraces printed with the printk format '%p[SR]b'. 44 45 This option is intended for distros where debuginfo is not easily 46 accessible but can be downloaded given the build ID of the vmlinux or 47 kernel module where the function is located. 48 49config CONSOLE_LOGLEVEL_DEFAULT 50 int "Default console loglevel (1-15)" 51 range 1 15 52 default "7" 53 help 54 Default loglevel to determine what will be printed on the console. 55 56 Setting a default here is equivalent to passing in loglevel=<x> in 57 the kernel bootargs. loglevel=<x> continues to override whatever 58 value is specified here as well. 59 60 Note: This does not affect the log level of un-prefixed printk() 61 usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT 62 option. 63 64config CONSOLE_LOGLEVEL_QUIET 65 int "quiet console loglevel (1-15)" 66 range 1 15 67 default "4" 68 help 69 loglevel to use when "quiet" is passed on the kernel commandline. 70 71 When "quiet" is passed on the kernel commandline this loglevel 72 will be used as the loglevel. IOW passing "quiet" will be the 73 equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>" 74 75config MESSAGE_LOGLEVEL_DEFAULT 76 int "Default message log level (1-7)" 77 range 1 7 78 default "4" 79 help 80 Default log level for printk statements with no specified priority. 81 82 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks 83 that are auditing their logs closely may want to set it to a lower 84 priority. 85 86 Note: This does not affect what message level gets printed on the console 87 by default. To change that, use loglevel=<x> in the kernel bootargs, 88 or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value. 89 90config BOOT_PRINTK_DELAY 91 bool "Delay each boot printk message by N milliseconds" 92 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY 93 help 94 This build option allows you to read kernel boot messages 95 by inserting a short delay after each one. The delay is 96 specified in milliseconds on the kernel command line, 97 using "boot_delay=N". 98 99 It is likely that you would also need to use "lpj=M" to preset 100 the "loops per jiffy" value. 101 See a previous boot log for the "lpj" value to use for your 102 system, and then set "lpj=M" before setting "boot_delay=N". 103 NOTE: Using this option may adversely affect SMP systems. 104 I.e., processors other than the first one may not boot up. 105 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect 106 what it believes to be lockup conditions. 107 108config DYNAMIC_DEBUG 109 bool "Enable dynamic printk() support" 110 default n 111 depends on PRINTK 112 depends on (DEBUG_FS || PROC_FS) 113 select DYNAMIC_DEBUG_CORE 114 help 115 116 Compiles debug level messages into the kernel, which would not 117 otherwise be available at runtime. These messages can then be 118 enabled/disabled based on various levels of scope - per source file, 119 function, module, format string, and line number. This mechanism 120 implicitly compiles in all pr_debug() and dev_dbg() calls, which 121 enlarges the kernel text size by about 2%. 122 123 If a source file is compiled with DEBUG flag set, any 124 pr_debug() calls in it are enabled by default, but can be 125 disabled at runtime as below. Note that DEBUG flag is 126 turned on by many CONFIG_*DEBUG* options. 127 128 Usage: 129 130 Dynamic debugging is controlled via the 'dynamic_debug/control' file, 131 which is contained in the 'debugfs' filesystem or procfs. 132 Thus, the debugfs or procfs filesystem must first be mounted before 133 making use of this feature. 134 We refer the control file as: <debugfs>/dynamic_debug/control. This 135 file contains a list of the debug statements that can be enabled. The 136 format for each line of the file is: 137 138 filename:lineno [module]function flags format 139 140 filename : source file of the debug statement 141 lineno : line number of the debug statement 142 module : module that contains the debug statement 143 function : function that contains the debug statement 144 flags : '=p' means the line is turned 'on' for printing 145 format : the format used for the debug statement 146 147 From a live system: 148 149 nullarbor:~ # cat <debugfs>/dynamic_debug/control 150 # filename:lineno [module]function flags format 151 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012" 152 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012" 153 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012" 154 155 Example usage: 156 157 // enable the message at line 1603 of file svcsock.c 158 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' > 159 <debugfs>/dynamic_debug/control 160 161 // enable all the messages in file svcsock.c 162 nullarbor:~ # echo -n 'file svcsock.c +p' > 163 <debugfs>/dynamic_debug/control 164 165 // enable all the messages in the NFS server module 166 nullarbor:~ # echo -n 'module nfsd +p' > 167 <debugfs>/dynamic_debug/control 168 169 // enable all 12 messages in the function svc_process() 170 nullarbor:~ # echo -n 'func svc_process +p' > 171 <debugfs>/dynamic_debug/control 172 173 // disable all 12 messages in the function svc_process() 174 nullarbor:~ # echo -n 'func svc_process -p' > 175 <debugfs>/dynamic_debug/control 176 177 See Documentation/admin-guide/dynamic-debug-howto.rst for additional 178 information. 179 180config DYNAMIC_DEBUG_CORE 181 bool "Enable core function of dynamic debug support" 182 depends on PRINTK 183 depends on (DEBUG_FS || PROC_FS) 184 help 185 Enable core functional support of dynamic debug. It is useful 186 when you want to tie dynamic debug to your kernel modules with 187 DYNAMIC_DEBUG_MODULE defined for each of them, especially for 188 the case of embedded system where the kernel image size is 189 sensitive for people. 190 191config SYMBOLIC_ERRNAME 192 bool "Support symbolic error names in printf" 193 default y if PRINTK 194 help 195 If you say Y here, the kernel's printf implementation will 196 be able to print symbolic error names such as ENOSPC instead 197 of the number 28. It makes the kernel image slightly larger 198 (about 3KB), but can make the kernel logs easier to read. 199 200config DEBUG_BUGVERBOSE 201 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT 202 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE) 203 default y 204 help 205 Say Y here to make BUG() panics output the file name and line number 206 of the BUG call as well as the EIP and oops trace. This aids 207 debugging but costs about 70-100K of memory. 208 209endmenu # "printk and dmesg options" 210 211config DEBUG_KERNEL 212 bool "Kernel debugging" 213 help 214 Say Y here if you are developing drivers or trying to debug and 215 identify kernel problems. 216 217config DEBUG_MISC 218 bool "Miscellaneous debug code" 219 default DEBUG_KERNEL 220 depends on DEBUG_KERNEL 221 help 222 Say Y here if you need to enable miscellaneous debug code that should 223 be under a more specific debug option but isn't. 224 225menu "Compile-time checks and compiler options" 226 227config DEBUG_INFO 228 bool 229 help 230 A kernel debug info option other than "None" has been selected 231 in the "Debug information" choice below, indicating that debug 232 information will be generated for build targets. 233 234# Clang generates .uleb128 with label differences for DWARF v5, a feature that 235# older binutils ports do not support when utilizing RISC-V style linker 236# relaxation: https://sourceware.org/bugzilla/show_bug.cgi?id=27215 237config AS_HAS_NON_CONST_ULEB128 238 def_bool $(as-instr,.uleb128 .Lexpr_end4 - .Lexpr_start3\n.Lexpr_start3:\n.Lexpr_end4:) 239 240choice 241 prompt "Debug information" 242 depends on DEBUG_KERNEL 243 help 244 Selecting something other than "None" results in a kernel image 245 that will include debugging info resulting in a larger kernel image. 246 This adds debug symbols to the kernel and modules (gcc -g), and 247 is needed if you intend to use kernel crashdump or binary object 248 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 249 250 Choose which version of DWARF debug info to emit. If unsure, 251 select "Toolchain default". 252 253config DEBUG_INFO_NONE 254 bool "Disable debug information" 255 help 256 Do not build the kernel with debugging information, which will 257 result in a faster and smaller build. 258 259config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT 260 bool "Rely on the toolchain's implicit default DWARF version" 261 select DEBUG_INFO 262 depends on !CC_IS_CLANG || AS_IS_LLVM || CLANG_VERSION < 140000 || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128) 263 help 264 The implicit default version of DWARF debug info produced by a 265 toolchain changes over time. 266 267 This can break consumers of the debug info that haven't upgraded to 268 support newer revisions, and prevent testing newer versions, but 269 those should be less common scenarios. 270 271config DEBUG_INFO_DWARF4 272 bool "Generate DWARF Version 4 debuginfo" 273 select DEBUG_INFO 274 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502) 275 help 276 Generate DWARF v4 debug info. This requires gcc 4.5+, binutils 2.35.2 277 if using clang without clang's integrated assembler, and gdb 7.0+. 278 279 If you have consumers of DWARF debug info that are not ready for 280 newer revisions of DWARF, you may wish to choose this or have your 281 config select this. 282 283config DEBUG_INFO_DWARF5 284 bool "Generate DWARF Version 5 debuginfo" 285 select DEBUG_INFO 286 depends on !ARCH_HAS_BROKEN_DWARF5 287 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128) 288 help 289 Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc 290 5.0+ accepts the -gdwarf-5 flag but only had partial support for some 291 draft features until 7.0), and gdb 8.0+. 292 293 Changes to the structure of debug info in Version 5 allow for around 294 15-18% savings in resulting image and debug info section sizes as 295 compared to DWARF Version 4. DWARF Version 5 standardizes previous 296 extensions such as accelerators for symbol indexing and the format 297 for fission (.dwo/.dwp) files. Users may not want to select this 298 config if they rely on tooling that has not yet been updated to 299 support DWARF Version 5. 300 301endchoice # "Debug information" 302 303if DEBUG_INFO 304 305config DEBUG_INFO_REDUCED 306 bool "Reduce debugging information" 307 help 308 If you say Y here gcc is instructed to generate less debugging 309 information for structure types. This means that tools that 310 need full debugging information (like kgdb or systemtap) won't 311 be happy. But if you merely need debugging information to 312 resolve line numbers there is no loss. Advantage is that 313 build directory object sizes shrink dramatically over a full 314 DEBUG_INFO build and compile times are reduced too. 315 Only works with newer gcc versions. 316 317choice 318 prompt "Compressed Debug information" 319 help 320 Compress the resulting debug info. Results in smaller debug info sections, 321 but requires that consumers are able to decompress the results. 322 323 If unsure, choose DEBUG_INFO_COMPRESSED_NONE. 324 325config DEBUG_INFO_COMPRESSED_NONE 326 bool "Don't compress debug information" 327 help 328 Don't compress debug info sections. 329 330config DEBUG_INFO_COMPRESSED_ZLIB 331 bool "Compress debugging information with zlib" 332 depends on $(cc-option,-gz=zlib) 333 depends on $(ld-option,--compress-debug-sections=zlib) 334 help 335 Compress the debug information using zlib. Requires GCC 5.0+ or Clang 336 5.0+, binutils 2.26+, and zlib. 337 338 Users of dpkg-deb via scripts/package/builddeb may find an increase in 339 size of their debug .deb packages with this config set, due to the 340 debug info being compressed with zlib, then the object files being 341 recompressed with a different compression scheme. But this is still 342 preferable to setting $KDEB_COMPRESS to "none" which would be even 343 larger. 344 345config DEBUG_INFO_COMPRESSED_ZSTD 346 bool "Compress debugging information with zstd" 347 depends on $(cc-option,-gz=zstd) 348 depends on $(ld-option,--compress-debug-sections=zstd) 349 help 350 Compress the debug information using zstd. This may provide better 351 compression than zlib, for about the same time costs, but requires newer 352 toolchain support. Requires GCC 13.0+ or Clang 16.0+, binutils 2.40+, and 353 zstd. 354 355endchoice # "Compressed Debug information" 356 357config DEBUG_INFO_SPLIT 358 bool "Produce split debuginfo in .dwo files" 359 depends on $(cc-option,-gsplit-dwarf) 360 # RISC-V linker relaxation + -gsplit-dwarf has issues with LLVM and GCC 361 # prior to 12.x: 362 # https://github.com/llvm/llvm-project/issues/56642 363 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99090 364 depends on !RISCV || GCC_VERSION >= 120000 365 help 366 Generate debug info into separate .dwo files. This significantly 367 reduces the build directory size for builds with DEBUG_INFO, 368 because it stores the information only once on disk in .dwo 369 files instead of multiple times in object files and executables. 370 In addition the debug information is also compressed. 371 372 Requires recent gcc (4.7+) and recent gdb/binutils. 373 Any tool that packages or reads debug information would need 374 to know about the .dwo files and include them. 375 Incompatible with older versions of ccache. 376 377config DEBUG_INFO_BTF 378 bool "Generate BTF type information" 379 depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED 380 depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST 381 depends on BPF_SYSCALL 382 depends on PAHOLE_VERSION >= 116 383 depends on DEBUG_INFO_DWARF4 || PAHOLE_VERSION >= 121 384 # pahole uses elfutils, which does not have support for Hexagon relocations 385 depends on !HEXAGON 386 help 387 Generate deduplicated BTF type information from DWARF debug info. 388 Turning this on requires pahole v1.16 or later (v1.21 or later to 389 support DWARF 5), which will convert DWARF type info into equivalent 390 deduplicated BTF type info. 391 392config PAHOLE_HAS_SPLIT_BTF 393 def_bool PAHOLE_VERSION >= 119 394 395config PAHOLE_HAS_BTF_TAG 396 def_bool PAHOLE_VERSION >= 123 397 depends on CC_IS_CLANG 398 help 399 Decide whether pahole emits btf_tag attributes (btf_type_tag and 400 btf_decl_tag) or not. Currently only clang compiler implements 401 these attributes, so make the config depend on CC_IS_CLANG. 402 403config PAHOLE_HAS_LANG_EXCLUDE 404 def_bool PAHOLE_VERSION >= 124 405 help 406 Support for the --lang_exclude flag which makes pahole exclude 407 compilation units from the supplied language. Used in Kbuild to 408 omit Rust CUs which are not supported in version 1.24 of pahole, 409 otherwise it would emit malformed kernel and module binaries when 410 using DEBUG_INFO_BTF_MODULES. 411 412config DEBUG_INFO_BTF_MODULES 413 bool "Generate BTF type information for kernel modules" 414 default y 415 depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF 416 help 417 Generate compact split BTF type information for kernel modules. 418 419config MODULE_ALLOW_BTF_MISMATCH 420 bool "Allow loading modules with non-matching BTF type info" 421 depends on DEBUG_INFO_BTF_MODULES 422 help 423 For modules whose split BTF does not match vmlinux, load without 424 BTF rather than refusing to load. The default behavior with 425 module BTF enabled is to reject modules with such mismatches; 426 this option will still load module BTF where possible but ignore 427 it when a mismatch is found. 428 429config GDB_SCRIPTS 430 bool "Provide GDB scripts for kernel debugging" 431 help 432 This creates the required links to GDB helper scripts in the 433 build directory. If you load vmlinux into gdb, the helper 434 scripts will be automatically imported by gdb as well, and 435 additional functions are available to analyze a Linux kernel 436 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst 437 for further details. 438 439endif # DEBUG_INFO 440 441config FRAME_WARN 442 int "Warn for stack frames larger than" 443 range 0 8192 444 default 0 if KMSAN 445 default 2048 if GCC_PLUGIN_LATENT_ENTROPY 446 default 2048 if PARISC 447 default 1536 if (!64BIT && XTENSA) 448 default 1280 if KASAN && !64BIT 449 default 1024 if !64BIT 450 default 2048 if 64BIT 451 help 452 Tell the compiler to warn at build time for stack frames larger than this. 453 Setting this too low will cause a lot of warnings. 454 Setting it to 0 disables the warning. 455 456config STRIP_ASM_SYMS 457 bool "Strip assembler-generated symbols during link" 458 default n 459 help 460 Strip internal assembler-generated symbols during a link (symbols 461 that look like '.Lxxx') so they don't pollute the output of 462 get_wchan() and suchlike. 463 464config READABLE_ASM 465 bool "Generate readable assembler code" 466 depends on DEBUG_KERNEL 467 depends on CC_IS_GCC 468 help 469 Disable some compiler optimizations that tend to generate human unreadable 470 assembler output. This may make the kernel slightly slower, but it helps 471 to keep kernel developers who have to stare a lot at assembler listings 472 sane. 473 474config HEADERS_INSTALL 475 bool "Install uapi headers to usr/include" 476 depends on !UML 477 help 478 This option will install uapi headers (headers exported to user-space) 479 into the usr/include directory for use during the kernel build. 480 This is unneeded for building the kernel itself, but needed for some 481 user-space program samples. It is also needed by some features such 482 as uapi header sanity checks. 483 484config DEBUG_SECTION_MISMATCH 485 bool "Enable full Section mismatch analysis" 486 depends on CC_IS_GCC 487 help 488 The section mismatch analysis checks if there are illegal 489 references from one section to another section. 490 During linktime or runtime, some sections are dropped; 491 any use of code/data previously in these sections would 492 most likely result in an oops. 493 In the code, functions and variables are annotated with 494 __init,, etc. (see the full list in include/linux/init.h), 495 which results in the code/data being placed in specific sections. 496 The section mismatch analysis is always performed after a full 497 kernel build, and enabling this option causes the following 498 additional step to occur: 499 - Add the option -fno-inline-functions-called-once to gcc commands. 500 When inlining a function annotated with __init in a non-init 501 function, we would lose the section information and thus 502 the analysis would not catch the illegal reference. 503 This option tells gcc to inline less (but it does result in 504 a larger kernel). 505 506config SECTION_MISMATCH_WARN_ONLY 507 bool "Make section mismatch errors non-fatal" 508 default y 509 help 510 If you say N here, the build process will fail if there are any 511 section mismatch, instead of just throwing warnings. 512 513 If unsure, say Y. 514 515config DEBUG_FORCE_FUNCTION_ALIGN_64B 516 bool "Force all function address 64B aligned" 517 depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC || RISCV || S390) 518 select FUNCTION_ALIGNMENT_64B 519 help 520 There are cases that a commit from one domain changes the function 521 address alignment of other domains, and cause magic performance 522 bump (regression or improvement). Enable this option will help to 523 verify if the bump is caused by function alignment changes, while 524 it will slightly increase the kernel size and affect icache usage. 525 526 It is mainly for debug and performance tuning use. 527 528# 529# Select this config option from the architecture Kconfig, if it 530# is preferred to always offer frame pointers as a config 531# option on the architecture (regardless of KERNEL_DEBUG): 532# 533config ARCH_WANT_FRAME_POINTERS 534 bool 535 536config FRAME_POINTER 537 bool "Compile the kernel with frame pointers" 538 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS 539 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 540 help 541 If you say Y here the resulting kernel image will be slightly 542 larger and slower, but it gives very useful debugging information 543 in case of kernel bugs. (precise oopses/stacktraces/warnings) 544 545config OBJTOOL 546 bool 547 548config STACK_VALIDATION 549 bool "Compile-time stack metadata validation" 550 depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER 551 select OBJTOOL 552 default n 553 help 554 Validate frame pointer rules at compile-time. This helps ensure that 555 runtime stack traces are more reliable. 556 557 For more information, see 558 tools/objtool/Documentation/objtool.txt. 559 560config NOINSTR_VALIDATION 561 bool 562 depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY 563 select OBJTOOL 564 default y 565 566config VMLINUX_MAP 567 bool "Generate vmlinux.map file when linking" 568 depends on EXPERT 569 help 570 Selecting this option will pass "-Map=vmlinux.map" to ld 571 when linking vmlinux. That file can be useful for verifying 572 and debugging magic section games, and for seeing which 573 pieces of code get eliminated with 574 CONFIG_LD_DEAD_CODE_DATA_ELIMINATION. 575 576config BUILTIN_MODULE_RANGES 577 bool "Generate address range information for builtin modules" 578 depends on !LTO 579 depends on VMLINUX_MAP 580 help 581 When modules are built into the kernel, there will be no module name 582 associated with its symbols in /proc/kallsyms. Tracers may want to 583 identify symbols by module name and symbol name regardless of whether 584 the module is configured as loadable or not. 585 586 This option generates modules.builtin.ranges in the build tree with 587 offset ranges (per ELF section) for the module(s) they belong to. 588 It also records an anchor symbol to determine the load address of the 589 section. 590 591config DEBUG_FORCE_WEAK_PER_CPU 592 bool "Force weak per-cpu definitions" 593 depends on DEBUG_KERNEL 594 help 595 s390 and alpha require percpu variables in modules to be 596 defined weak to work around addressing range issue which 597 puts the following two restrictions on percpu variable 598 definitions. 599 600 1. percpu symbols must be unique whether static or not 601 2. percpu variables can't be defined inside a function 602 603 To ensure that generic code follows the above rules, this 604 option forces all percpu variables to be defined as weak. 605 606endmenu # "Compiler options" 607 608menu "Generic Kernel Debugging Instruments" 609 610config MAGIC_SYSRQ 611 bool "Magic SysRq key" 612 depends on !UML 613 help 614 If you say Y here, you will have some control over the system even 615 if the system crashes for example during kernel debugging (e.g., you 616 will be able to flush the buffer cache to disk, reboot the system 617 immediately or dump some status information). This is accomplished 618 by pressing various keys while holding SysRq (Alt+PrintScreen). It 619 also works on a serial console (on PC hardware at least), if you 620 send a BREAK and then within 5 seconds a command keypress. The 621 keys are documented in <file:Documentation/admin-guide/sysrq.rst>. 622 Don't say Y unless you really know what this hack does. 623 624config MAGIC_SYSRQ_DEFAULT_ENABLE 625 hex "Enable magic SysRq key functions by default" 626 depends on MAGIC_SYSRQ 627 default 0x1 628 help 629 Specifies which SysRq key functions are enabled by default. 630 This may be set to 1 or 0 to enable or disable them all, or 631 to a bitmask as described in Documentation/admin-guide/sysrq.rst. 632 633config MAGIC_SYSRQ_SERIAL 634 bool "Enable magic SysRq key over serial" 635 depends on MAGIC_SYSRQ 636 default y 637 help 638 Many embedded boards have a disconnected TTL level serial which can 639 generate some garbage that can lead to spurious false sysrq detects. 640 This option allows you to decide whether you want to enable the 641 magic SysRq key. 642 643config MAGIC_SYSRQ_SERIAL_SEQUENCE 644 string "Char sequence that enables magic SysRq over serial" 645 depends on MAGIC_SYSRQ_SERIAL 646 default "" 647 help 648 Specifies a sequence of characters that can follow BREAK to enable 649 SysRq on a serial console. 650 651 If unsure, leave an empty string and the option will not be enabled. 652 653config DEBUG_FS 654 bool "Debug Filesystem" 655 help 656 debugfs is a virtual file system that kernel developers use to put 657 debugging files into. Enable this option to be able to read and 658 write to these files. 659 660 For detailed documentation on the debugfs API, see 661 Documentation/filesystems/. 662 663 If unsure, say N. 664 665choice 666 prompt "Debugfs default access" 667 depends on DEBUG_FS 668 default DEBUG_FS_ALLOW_ALL 669 help 670 This selects the default access restrictions for debugfs. 671 It can be overridden with kernel command line option 672 debugfs=[on,no-mount,off]. The restrictions apply for API access 673 and filesystem registration. 674 675config DEBUG_FS_ALLOW_ALL 676 bool "Access normal" 677 help 678 No restrictions apply. Both API and filesystem registration 679 is on. This is the normal default operation. 680 681config DEBUG_FS_DISALLOW_MOUNT 682 bool "Do not register debugfs as filesystem" 683 help 684 The API is open but filesystem is not loaded. Clients can still do 685 their work and read with debug tools that do not need 686 debugfs filesystem. 687 688config DEBUG_FS_ALLOW_NONE 689 bool "No access" 690 help 691 Access is off. Clients get -PERM when trying to create nodes in 692 debugfs tree and debugfs is not registered as a filesystem. 693 Client can then back-off or continue without debugfs access. 694 695endchoice 696 697source "lib/Kconfig.kgdb" 698source "lib/Kconfig.ubsan" 699source "lib/Kconfig.kcsan" 700 701endmenu 702 703menu "Networking Debugging" 704 705source "net/Kconfig.debug" 706 707endmenu # "Networking Debugging" 708 709menu "Memory Debugging" 710 711source "mm/Kconfig.debug" 712 713config DEBUG_OBJECTS 714 bool "Debug object operations" 715 depends on DEBUG_KERNEL 716 help 717 If you say Y here, additional code will be inserted into the 718 kernel to track the life time of various objects and validate 719 the operations on those objects. 720 721config DEBUG_OBJECTS_SELFTEST 722 bool "Debug objects selftest" 723 depends on DEBUG_OBJECTS 724 help 725 This enables the selftest of the object debug code. 726 727config DEBUG_OBJECTS_FREE 728 bool "Debug objects in freed memory" 729 depends on DEBUG_OBJECTS 730 help 731 This enables checks whether a k/v free operation frees an area 732 which contains an object which has not been deactivated 733 properly. This can make kmalloc/kfree-intensive workloads 734 much slower. 735 736config DEBUG_OBJECTS_TIMERS 737 bool "Debug timer objects" 738 depends on DEBUG_OBJECTS 739 help 740 If you say Y here, additional code will be inserted into the 741 timer routines to track the life time of timer objects and 742 validate the timer operations. 743 744config DEBUG_OBJECTS_WORK 745 bool "Debug work objects" 746 depends on DEBUG_OBJECTS 747 help 748 If you say Y here, additional code will be inserted into the 749 work queue routines to track the life time of work objects and 750 validate the work operations. 751 752config DEBUG_OBJECTS_RCU_HEAD 753 bool "Debug RCU callbacks objects" 754 depends on DEBUG_OBJECTS 755 help 756 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 757 758config DEBUG_OBJECTS_PERCPU_COUNTER 759 bool "Debug percpu counter objects" 760 depends on DEBUG_OBJECTS 761 help 762 If you say Y here, additional code will be inserted into the 763 percpu counter routines to track the life time of percpu counter 764 objects and validate the percpu counter operations. 765 766config DEBUG_OBJECTS_ENABLE_DEFAULT 767 int "debug_objects bootup default value (0-1)" 768 range 0 1 769 default "1" 770 depends on DEBUG_OBJECTS 771 help 772 Debug objects boot parameter default value 773 774config SHRINKER_DEBUG 775 bool "Enable shrinker debugging support" 776 depends on DEBUG_FS 777 help 778 Say Y to enable the shrinker debugfs interface which provides 779 visibility into the kernel memory shrinkers subsystem. 780 Disable it to avoid an extra memory footprint. 781 782config DEBUG_STACK_USAGE 783 bool "Stack utilization instrumentation" 784 depends on DEBUG_KERNEL 785 help 786 Enables the display of the minimum amount of free stack which each 787 task has ever had available in the sysrq-T and sysrq-P debug output. 788 Also emits a message to dmesg when a process exits if that process 789 used more stack space than previously exiting processes. 790 791 This option will slow down process creation somewhat. 792 793config SCHED_STACK_END_CHECK 794 bool "Detect stack corruption on calls to schedule()" 795 depends on DEBUG_KERNEL 796 default n 797 help 798 This option checks for a stack overrun on calls to schedule(). 799 If the stack end location is found to be over written always panic as 800 the content of the corrupted region can no longer be trusted. 801 This is to ensure no erroneous behaviour occurs which could result in 802 data corruption or a sporadic crash at a later stage once the region 803 is examined. The runtime overhead introduced is minimal. 804 805config ARCH_HAS_DEBUG_VM_PGTABLE 806 bool 807 help 808 An architecture should select this when it can successfully 809 build and run DEBUG_VM_PGTABLE. 810 811config DEBUG_VM_IRQSOFF 812 def_bool DEBUG_VM && !PREEMPT_RT 813 814config DEBUG_VM 815 bool "Debug VM" 816 depends on DEBUG_KERNEL 817 help 818 Enable this to turn on extended checks in the virtual-memory system 819 that may impact performance. 820 821 If unsure, say N. 822 823config DEBUG_VM_SHOOT_LAZIES 824 bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation" 825 depends on DEBUG_VM 826 depends on MMU_LAZY_TLB_SHOOTDOWN 827 help 828 Enable additional IPIs that ensure lazy tlb mm references are removed 829 before the mm is freed. 830 831 If unsure, say N. 832 833config DEBUG_VM_MAPLE_TREE 834 bool "Debug VM maple trees" 835 depends on DEBUG_VM 836 select DEBUG_MAPLE_TREE 837 help 838 Enable VM maple tree debugging information and extra validations. 839 840 If unsure, say N. 841 842config DEBUG_VM_RB 843 bool "Debug VM red-black trees" 844 depends on DEBUG_VM 845 help 846 Enable VM red-black tree debugging information and extra validations. 847 848 If unsure, say N. 849 850config DEBUG_VM_PGFLAGS 851 bool "Debug page-flags operations" 852 depends on DEBUG_VM 853 help 854 Enables extra validation on page flags operations. 855 856 If unsure, say N. 857 858config DEBUG_VM_PGTABLE 859 bool "Debug arch page table for semantics compliance" 860 depends on MMU 861 depends on ARCH_HAS_DEBUG_VM_PGTABLE 862 default y if DEBUG_VM 863 help 864 This option provides a debug method which can be used to test 865 architecture page table helper functions on various platforms in 866 verifying if they comply with expected generic MM semantics. This 867 will help architecture code in making sure that any changes or 868 new additions of these helpers still conform to expected 869 semantics of the generic MM. Platforms will have to opt in for 870 this through ARCH_HAS_DEBUG_VM_PGTABLE. 871 872 If unsure, say N. 873 874config ARCH_HAS_DEBUG_VIRTUAL 875 bool 876 877config DEBUG_VIRTUAL 878 bool "Debug VM translations" 879 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL 880 help 881 Enable some costly sanity checks in virtual to page code. This can 882 catch mistakes with virt_to_page() and friends. 883 884 If unsure, say N. 885 886config DEBUG_NOMMU_REGIONS 887 bool "Debug the global anon/private NOMMU mapping region tree" 888 depends on DEBUG_KERNEL && !MMU 889 help 890 This option causes the global tree of anonymous and private mapping 891 regions to be regularly checked for invalid topology. 892 893config DEBUG_MEMORY_INIT 894 bool "Debug memory initialisation" if EXPERT 895 default !EXPERT 896 help 897 Enable this for additional checks during memory initialisation. 898 The sanity checks verify aspects of the VM such as the memory model 899 and other information provided by the architecture. Verbose 900 information will be printed at KERN_DEBUG loglevel depending 901 on the mminit_loglevel= command-line option. 902 903 If unsure, say Y 904 905config MEMORY_NOTIFIER_ERROR_INJECT 906 tristate "Memory hotplug notifier error injection module" 907 depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION 908 help 909 This option provides the ability to inject artificial errors to 910 memory hotplug notifier chain callbacks. It is controlled through 911 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 912 913 If the notifier call chain should be failed with some events 914 notified, write the error code to "actions/<notifier event>/error". 915 916 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 917 918 # cd /sys/kernel/debug/notifier-error-inject/memory 919 # echo -12 > actions/MEM_GOING_OFFLINE/error 920 # echo offline > /sys/devices/system/memory/memoryXXX/state 921 bash: echo: write error: Cannot allocate memory 922 923 To compile this code as a module, choose M here: the module will 924 be called memory-notifier-error-inject. 925 926 If unsure, say N. 927 928config DEBUG_PER_CPU_MAPS 929 bool "Debug access to per_cpu maps" 930 depends on DEBUG_KERNEL 931 depends on SMP 932 help 933 Say Y to verify that the per_cpu map being accessed has 934 been set up. This adds a fair amount of code to kernel memory 935 and decreases performance. 936 937 Say N if unsure. 938 939config DEBUG_KMAP_LOCAL 940 bool "Debug kmap_local temporary mappings" 941 depends on DEBUG_KERNEL && KMAP_LOCAL 942 help 943 This option enables additional error checking for the kmap_local 944 infrastructure. Disable for production use. 945 946config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 947 bool 948 949config DEBUG_KMAP_LOCAL_FORCE_MAP 950 bool "Enforce kmap_local temporary mappings" 951 depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 952 select KMAP_LOCAL 953 select DEBUG_KMAP_LOCAL 954 help 955 This option enforces temporary mappings through the kmap_local 956 mechanism for non-highmem pages and on non-highmem systems. 957 Disable this for production systems! 958 959config DEBUG_HIGHMEM 960 bool "Highmem debugging" 961 depends on DEBUG_KERNEL && HIGHMEM 962 select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 963 select DEBUG_KMAP_LOCAL 964 help 965 This option enables additional error checking for high memory 966 systems. Disable for production systems. 967 968config HAVE_DEBUG_STACKOVERFLOW 969 bool 970 971config DEBUG_STACKOVERFLOW 972 bool "Check for stack overflows" 973 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 974 help 975 Say Y here if you want to check for overflows of kernel, IRQ 976 and exception stacks (if your architecture uses them). This 977 option will show detailed messages if free stack space drops 978 below a certain limit. 979 980 These kinds of bugs usually occur when call-chains in the 981 kernel get too deep, especially when interrupts are 982 involved. 983 984 Use this in cases where you see apparently random memory 985 corruption, especially if it appears in 'struct thread_info' 986 987 If in doubt, say "N". 988 989config CODE_TAGGING 990 bool 991 select KALLSYMS 992 993config MEM_ALLOC_PROFILING 994 bool "Enable memory allocation profiling" 995 default n 996 depends on MMU 997 depends on PROC_FS 998 depends on !DEBUG_FORCE_WEAK_PER_CPU 999 select CODE_TAGGING 1000 select PAGE_EXTENSION 1001 select SLAB_OBJ_EXT 1002 help 1003 Track allocation source code and record total allocation size 1004 initiated at that code location. The mechanism can be used to track 1005 memory leaks with a low performance and memory impact. 1006 1007config MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT 1008 bool "Enable memory allocation profiling by default" 1009 default y 1010 depends on MEM_ALLOC_PROFILING 1011 1012config MEM_ALLOC_PROFILING_DEBUG 1013 bool "Memory allocation profiler debugging" 1014 default n 1015 depends on MEM_ALLOC_PROFILING 1016 select MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT 1017 help 1018 Adds warnings with helpful error messages for memory allocation 1019 profiling. 1020 1021source "lib/Kconfig.kasan" 1022source "lib/Kconfig.kfence" 1023source "lib/Kconfig.kmsan" 1024 1025endmenu # "Memory Debugging" 1026 1027config DEBUG_SHIRQ 1028 bool "Debug shared IRQ handlers" 1029 depends on DEBUG_KERNEL 1030 help 1031 Enable this to generate a spurious interrupt just before a shared 1032 interrupt handler is deregistered (generating one when registering 1033 is currently disabled). Drivers need to handle this correctly. Some 1034 don't and need to be caught. 1035 1036menu "Debug Oops, Lockups and Hangs" 1037 1038config PANIC_ON_OOPS 1039 bool "Panic on Oops" 1040 help 1041 Say Y here to enable the kernel to panic when it oopses. This 1042 has the same effect as setting oops=panic on the kernel command 1043 line. 1044 1045 This feature is useful to ensure that the kernel does not do 1046 anything erroneous after an oops which could result in data 1047 corruption or other issues. 1048 1049 Say N if unsure. 1050 1051config PANIC_ON_OOPS_VALUE 1052 int 1053 range 0 1 1054 default 0 if !PANIC_ON_OOPS 1055 default 1 if PANIC_ON_OOPS 1056 1057config PANIC_TIMEOUT 1058 int "panic timeout" 1059 default 0 1060 help 1061 Set the timeout value (in seconds) until a reboot occurs when 1062 the kernel panics. If n = 0, then we wait forever. A timeout 1063 value n > 0 will wait n seconds before rebooting, while a timeout 1064 value n < 0 will reboot immediately. This setting can be overridden 1065 with the kernel command line option panic=, and from userspace via 1066 /proc/sys/kernel/panic. 1067 1068config LOCKUP_DETECTOR 1069 bool 1070 1071config SOFTLOCKUP_DETECTOR 1072 bool "Detect Soft Lockups" 1073 depends on DEBUG_KERNEL && !S390 1074 select LOCKUP_DETECTOR 1075 help 1076 Say Y here to enable the kernel to act as a watchdog to detect 1077 soft lockups. 1078 1079 Softlockups are bugs that cause the kernel to loop in kernel 1080 mode for more than 20 seconds, without giving other tasks a 1081 chance to run. The current stack trace is displayed upon 1082 detection and the system will stay locked up. 1083 1084config SOFTLOCKUP_DETECTOR_INTR_STORM 1085 bool "Detect Interrupt Storm in Soft Lockups" 1086 depends on SOFTLOCKUP_DETECTOR && IRQ_TIME_ACCOUNTING 1087 select GENERIC_IRQ_STAT_SNAPSHOT 1088 default y if NR_CPUS <= 128 1089 help 1090 Say Y here to enable the kernel to detect interrupt storm 1091 during "soft lockups". 1092 1093 "soft lockups" can be caused by a variety of reasons. If one is 1094 caused by an interrupt storm, then the storming interrupts will not 1095 be on the callstack. To detect this case, it is necessary to report 1096 the CPU stats and the interrupt counts during the "soft lockups". 1097 1098config BOOTPARAM_SOFTLOCKUP_PANIC 1099 bool "Panic (Reboot) On Soft Lockups" 1100 depends on SOFTLOCKUP_DETECTOR 1101 help 1102 Say Y here to enable the kernel to panic on "soft lockups", 1103 which are bugs that cause the kernel to loop in kernel 1104 mode for more than 20 seconds (configurable using the watchdog_thresh 1105 sysctl), without giving other tasks a chance to run. 1106 1107 The panic can be used in combination with panic_timeout, 1108 to cause the system to reboot automatically after a 1109 lockup has been detected. This feature is useful for 1110 high-availability systems that have uptime guarantees and 1111 where a lockup must be resolved ASAP. 1112 1113 Say N if unsure. 1114 1115config HAVE_HARDLOCKUP_DETECTOR_BUDDY 1116 bool 1117 depends on SMP 1118 default y 1119 1120# 1121# Global switch whether to build a hardlockup detector at all. It is available 1122# only when the architecture supports at least one implementation. There are 1123# two exceptions. The hardlockup detector is never enabled on: 1124# 1125# s390: it reported many false positives there 1126# 1127# sparc64: has a custom implementation which is not using the common 1128# hardlockup command line options and sysctl interface. 1129# 1130config HARDLOCKUP_DETECTOR 1131 bool "Detect Hard Lockups" 1132 depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64 1133 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH 1134 imply HARDLOCKUP_DETECTOR_PERF 1135 imply HARDLOCKUP_DETECTOR_BUDDY 1136 imply HARDLOCKUP_DETECTOR_ARCH 1137 select LOCKUP_DETECTOR 1138 1139 help 1140 Say Y here to enable the kernel to act as a watchdog to detect 1141 hard lockups. 1142 1143 Hardlockups are bugs that cause the CPU to loop in kernel mode 1144 for more than 10 seconds, without letting other interrupts have a 1145 chance to run. The current stack trace is displayed upon detection 1146 and the system will stay locked up. 1147 1148# 1149# Note that arch-specific variants are always preferred. 1150# 1151config HARDLOCKUP_DETECTOR_PREFER_BUDDY 1152 bool "Prefer the buddy CPU hardlockup detector" 1153 depends on HARDLOCKUP_DETECTOR 1154 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY 1155 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1156 help 1157 Say Y here to prefer the buddy hardlockup detector over the perf one. 1158 1159 With the buddy detector, each CPU uses its softlockup hrtimer 1160 to check that the next CPU is processing hrtimer interrupts by 1161 verifying that a counter is increasing. 1162 1163 This hardlockup detector is useful on systems that don't have 1164 an arch-specific hardlockup detector or if resources needed 1165 for the hardlockup detector are better used for other things. 1166 1167config HARDLOCKUP_DETECTOR_PERF 1168 bool 1169 depends on HARDLOCKUP_DETECTOR 1170 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY 1171 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1172 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1173 1174config HARDLOCKUP_DETECTOR_BUDDY 1175 bool 1176 depends on HARDLOCKUP_DETECTOR 1177 depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY 1178 depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY 1179 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1180 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1181 1182config HARDLOCKUP_DETECTOR_ARCH 1183 bool 1184 depends on HARDLOCKUP_DETECTOR 1185 depends on HAVE_HARDLOCKUP_DETECTOR_ARCH 1186 help 1187 The arch-specific implementation of the hardlockup detector will 1188 be used. 1189 1190# 1191# Both the "perf" and "buddy" hardlockup detectors count hrtimer 1192# interrupts. This config enables functions managing this common code. 1193# 1194config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1195 bool 1196 select SOFTLOCKUP_DETECTOR 1197 1198# 1199# Enables a timestamp based low pass filter to compensate for perf based 1200# hard lockup detection which runs too fast due to turbo modes. 1201# 1202config HARDLOCKUP_CHECK_TIMESTAMP 1203 bool 1204 1205config BOOTPARAM_HARDLOCKUP_PANIC 1206 bool "Panic (Reboot) On Hard Lockups" 1207 depends on HARDLOCKUP_DETECTOR 1208 help 1209 Say Y here to enable the kernel to panic on "hard lockups", 1210 which are bugs that cause the kernel to loop in kernel 1211 mode with interrupts disabled for more than 10 seconds (configurable 1212 using the watchdog_thresh sysctl). 1213 1214 Say N if unsure. 1215 1216config DETECT_HUNG_TASK 1217 bool "Detect Hung Tasks" 1218 depends on DEBUG_KERNEL 1219 default SOFTLOCKUP_DETECTOR 1220 help 1221 Say Y here to enable the kernel to detect "hung tasks", 1222 which are bugs that cause the task to be stuck in 1223 uninterruptible "D" state indefinitely. 1224 1225 When a hung task is detected, the kernel will print the 1226 current stack trace (which you should report), but the 1227 task will stay in uninterruptible state. If lockdep is 1228 enabled then all held locks will also be reported. This 1229 feature has negligible overhead. 1230 1231config DEFAULT_HUNG_TASK_TIMEOUT 1232 int "Default timeout for hung task detection (in seconds)" 1233 depends on DETECT_HUNG_TASK 1234 default 120 1235 help 1236 This option controls the default timeout (in seconds) used 1237 to determine when a task has become non-responsive and should 1238 be considered hung. 1239 1240 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 1241 sysctl or by writing a value to 1242 /proc/sys/kernel/hung_task_timeout_secs. 1243 1244 A timeout of 0 disables the check. The default is two minutes. 1245 Keeping the default should be fine in most cases. 1246 1247config BOOTPARAM_HUNG_TASK_PANIC 1248 bool "Panic (Reboot) On Hung Tasks" 1249 depends on DETECT_HUNG_TASK 1250 help 1251 Say Y here to enable the kernel to panic on "hung tasks", 1252 which are bugs that cause the kernel to leave a task stuck 1253 in uninterruptible "D" state. 1254 1255 The panic can be used in combination with panic_timeout, 1256 to cause the system to reboot automatically after a 1257 hung task has been detected. This feature is useful for 1258 high-availability systems that have uptime guarantees and 1259 where a hung tasks must be resolved ASAP. 1260 1261 Say N if unsure. 1262 1263config WQ_WATCHDOG 1264 bool "Detect Workqueue Stalls" 1265 depends on DEBUG_KERNEL 1266 help 1267 Say Y here to enable stall detection on workqueues. If a 1268 worker pool doesn't make forward progress on a pending work 1269 item for over a given amount of time, 30s by default, a 1270 warning message is printed along with dump of workqueue 1271 state. This can be configured through kernel parameter 1272 "workqueue.watchdog_thresh" and its sysfs counterpart. 1273 1274config WQ_CPU_INTENSIVE_REPORT 1275 bool "Report per-cpu work items which hog CPU for too long" 1276 depends on DEBUG_KERNEL 1277 help 1278 Say Y here to enable reporting of concurrency-managed per-cpu work 1279 items that hog CPUs for longer than 1280 workqueue.cpu_intensive_thresh_us. Workqueue automatically 1281 detects and excludes them from concurrency management to prevent 1282 them from stalling other per-cpu work items. Occassional 1283 triggering may not necessarily indicate a problem. Repeated 1284 triggering likely indicates that the work item should be switched 1285 to use an unbound workqueue. 1286 1287config TEST_LOCKUP 1288 tristate "Test module to generate lockups" 1289 depends on m 1290 help 1291 This builds the "test_lockup" module that helps to make sure 1292 that watchdogs and lockup detectors are working properly. 1293 1294 Depending on module parameters it could emulate soft or hard 1295 lockup, "hung task", or locking arbitrary lock for a long time. 1296 Also it could generate series of lockups with cooling-down periods. 1297 1298 If unsure, say N. 1299 1300endmenu # "Debug lockups and hangs" 1301 1302menu "Scheduler Debugging" 1303 1304config SCHED_DEBUG 1305 bool "Collect scheduler debugging info" 1306 depends on DEBUG_KERNEL && DEBUG_FS 1307 default y 1308 help 1309 If you say Y here, the /sys/kernel/debug/sched file will be provided 1310 that can help debug the scheduler. The runtime overhead of this 1311 option is minimal. 1312 1313config SCHED_INFO 1314 bool 1315 default n 1316 1317config SCHEDSTATS 1318 bool "Collect scheduler statistics" 1319 depends on PROC_FS 1320 select SCHED_INFO 1321 help 1322 If you say Y here, additional code will be inserted into the 1323 scheduler and related routines to collect statistics about 1324 scheduler behavior and provide them in /proc/schedstat. These 1325 stats may be useful for both tuning and debugging the scheduler 1326 If you aren't debugging the scheduler or trying to tune a specific 1327 application, you can say N to avoid the very slight overhead 1328 this adds. 1329 1330endmenu 1331 1332config DEBUG_PREEMPT 1333 bool "Debug preemptible kernel" 1334 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1335 help 1336 If you say Y here then the kernel will use a debug variant of the 1337 commonly used smp_processor_id() function and will print warnings 1338 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1339 will detect preemption count underflows. 1340 1341 This option has potential to introduce high runtime overhead, 1342 depending on workload as it triggers debugging routines for each 1343 this_cpu operation. It should only be used for debugging purposes. 1344 1345menu "Lock Debugging (spinlocks, mutexes, etc...)" 1346 1347config LOCK_DEBUGGING_SUPPORT 1348 bool 1349 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1350 default y 1351 1352config PROVE_LOCKING 1353 bool "Lock debugging: prove locking correctness" 1354 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1355 select LOCKDEP 1356 select DEBUG_SPINLOCK 1357 select DEBUG_MUTEXES if !PREEMPT_RT 1358 select DEBUG_RT_MUTEXES if RT_MUTEXES 1359 select DEBUG_RWSEMS if !PREEMPT_RT 1360 select DEBUG_WW_MUTEX_SLOWPATH 1361 select DEBUG_LOCK_ALLOC 1362 select PREEMPT_COUNT if !ARCH_NO_PREEMPT 1363 select TRACE_IRQFLAGS 1364 default n 1365 help 1366 This feature enables the kernel to prove that all locking 1367 that occurs in the kernel runtime is mathematically 1368 correct: that under no circumstance could an arbitrary (and 1369 not yet triggered) combination of observed locking 1370 sequences (on an arbitrary number of CPUs, running an 1371 arbitrary number of tasks and interrupt contexts) cause a 1372 deadlock. 1373 1374 In short, this feature enables the kernel to report locking 1375 related deadlocks before they actually occur. 1376 1377 The proof does not depend on how hard and complex a 1378 deadlock scenario would be to trigger: how many 1379 participant CPUs, tasks and irq-contexts would be needed 1380 for it to trigger. The proof also does not depend on 1381 timing: if a race and a resulting deadlock is possible 1382 theoretically (no matter how unlikely the race scenario 1383 is), it will be proven so and will immediately be 1384 reported by the kernel (once the event is observed that 1385 makes the deadlock theoretically possible). 1386 1387 If a deadlock is impossible (i.e. the locking rules, as 1388 observed by the kernel, are mathematically correct), the 1389 kernel reports nothing. 1390 1391 NOTE: this feature can also be enabled for rwlocks, mutexes 1392 and rwsems - in which case all dependencies between these 1393 different locking variants are observed and mapped too, and 1394 the proof of observed correctness is also maintained for an 1395 arbitrary combination of these separate locking variants. 1396 1397 For more details, see Documentation/locking/lockdep-design.rst. 1398 1399config PROVE_RAW_LOCK_NESTING 1400 bool 1401 depends on PROVE_LOCKING 1402 default y 1403 help 1404 Enable the raw_spinlock vs. spinlock nesting checks which ensure 1405 that the lock nesting rules for PREEMPT_RT enabled kernels are 1406 not violated. 1407 1408config LOCK_STAT 1409 bool "Lock usage statistics" 1410 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1411 select LOCKDEP 1412 select DEBUG_SPINLOCK 1413 select DEBUG_MUTEXES if !PREEMPT_RT 1414 select DEBUG_RT_MUTEXES if RT_MUTEXES 1415 select DEBUG_LOCK_ALLOC 1416 default n 1417 help 1418 This feature enables tracking lock contention points 1419 1420 For more details, see Documentation/locking/lockstat.rst 1421 1422 This also enables lock events required by "perf lock", 1423 subcommand of perf. 1424 If you want to use "perf lock", you also need to turn on 1425 CONFIG_EVENT_TRACING. 1426 1427 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1428 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1429 1430config DEBUG_RT_MUTEXES 1431 bool "RT Mutex debugging, deadlock detection" 1432 depends on DEBUG_KERNEL && RT_MUTEXES 1433 help 1434 This allows rt mutex semantics violations and rt mutex related 1435 deadlocks (lockups) to be detected and reported automatically. 1436 1437config DEBUG_SPINLOCK 1438 bool "Spinlock and rw-lock debugging: basic checks" 1439 depends on DEBUG_KERNEL 1440 select UNINLINE_SPIN_UNLOCK 1441 help 1442 Say Y here and build SMP to catch missing spinlock initialization 1443 and certain other kinds of spinlock errors commonly made. This is 1444 best used in conjunction with the NMI watchdog so that spinlock 1445 deadlocks are also debuggable. 1446 1447config DEBUG_MUTEXES 1448 bool "Mutex debugging: basic checks" 1449 depends on DEBUG_KERNEL && !PREEMPT_RT 1450 help 1451 This feature allows mutex semantics violations to be detected and 1452 reported. 1453 1454config DEBUG_WW_MUTEX_SLOWPATH 1455 bool "Wait/wound mutex debugging: Slowpath testing" 1456 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1457 select DEBUG_LOCK_ALLOC 1458 select DEBUG_SPINLOCK 1459 select DEBUG_MUTEXES if !PREEMPT_RT 1460 select DEBUG_RT_MUTEXES if PREEMPT_RT 1461 help 1462 This feature enables slowpath testing for w/w mutex users by 1463 injecting additional -EDEADLK wound/backoff cases. Together with 1464 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1465 will test all possible w/w mutex interface abuse with the 1466 exception of simply not acquiring all the required locks. 1467 Note that this feature can introduce significant overhead, so 1468 it really should not be enabled in a production or distro kernel, 1469 even a debug kernel. If you are a driver writer, enable it. If 1470 you are a distro, do not. 1471 1472config DEBUG_RWSEMS 1473 bool "RW Semaphore debugging: basic checks" 1474 depends on DEBUG_KERNEL && !PREEMPT_RT 1475 help 1476 This debugging feature allows mismatched rw semaphore locks 1477 and unlocks to be detected and reported. 1478 1479config DEBUG_LOCK_ALLOC 1480 bool "Lock debugging: detect incorrect freeing of live locks" 1481 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1482 select DEBUG_SPINLOCK 1483 select DEBUG_MUTEXES if !PREEMPT_RT 1484 select DEBUG_RT_MUTEXES if RT_MUTEXES 1485 select LOCKDEP 1486 help 1487 This feature will check whether any held lock (spinlock, rwlock, 1488 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1489 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1490 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1491 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1492 held during task exit. 1493 1494config LOCKDEP 1495 bool 1496 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1497 select STACKTRACE 1498 select KALLSYMS 1499 select KALLSYMS_ALL 1500 1501config LOCKDEP_SMALL 1502 bool 1503 1504config LOCKDEP_BITS 1505 int "Bitsize for MAX_LOCKDEP_ENTRIES" 1506 depends on LOCKDEP && !LOCKDEP_SMALL 1507 range 10 30 1508 default 15 1509 help 1510 Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message. 1511 1512config LOCKDEP_CHAINS_BITS 1513 int "Bitsize for MAX_LOCKDEP_CHAINS" 1514 depends on LOCKDEP && !LOCKDEP_SMALL 1515 range 10 21 1516 default 16 1517 help 1518 Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message. 1519 1520config LOCKDEP_STACK_TRACE_BITS 1521 int "Bitsize for MAX_STACK_TRACE_ENTRIES" 1522 depends on LOCKDEP && !LOCKDEP_SMALL 1523 range 10 30 1524 default 19 1525 help 1526 Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message. 1527 1528config LOCKDEP_STACK_TRACE_HASH_BITS 1529 int "Bitsize for STACK_TRACE_HASH_SIZE" 1530 depends on LOCKDEP && !LOCKDEP_SMALL 1531 range 10 30 1532 default 14 1533 help 1534 Try increasing this value if you need large STACK_TRACE_HASH_SIZE. 1535 1536config LOCKDEP_CIRCULAR_QUEUE_BITS 1537 int "Bitsize for elements in circular_queue struct" 1538 depends on LOCKDEP 1539 range 10 30 1540 default 12 1541 help 1542 Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure. 1543 1544config DEBUG_LOCKDEP 1545 bool "Lock dependency engine debugging" 1546 depends on DEBUG_KERNEL && LOCKDEP 1547 select DEBUG_IRQFLAGS 1548 help 1549 If you say Y here, the lock dependency engine will do 1550 additional runtime checks to debug itself, at the price 1551 of more runtime overhead. 1552 1553config DEBUG_ATOMIC_SLEEP 1554 bool "Sleep inside atomic section checking" 1555 select PREEMPT_COUNT 1556 depends on DEBUG_KERNEL 1557 depends on !ARCH_NO_PREEMPT 1558 help 1559 If you say Y here, various routines which may sleep will become very 1560 noisy if they are called inside atomic sections: when a spinlock is 1561 held, inside an rcu read side critical section, inside preempt disabled 1562 sections, inside an interrupt, etc... 1563 1564config DEBUG_LOCKING_API_SELFTESTS 1565 bool "Locking API boot-time self-tests" 1566 depends on DEBUG_KERNEL 1567 help 1568 Say Y here if you want the kernel to run a short self-test during 1569 bootup. The self-test checks whether common types of locking bugs 1570 are detected by debugging mechanisms or not. (if you disable 1571 lock debugging then those bugs won't be detected of course.) 1572 The following locking APIs are covered: spinlocks, rwlocks, 1573 mutexes and rwsems. 1574 1575config LOCK_TORTURE_TEST 1576 tristate "torture tests for locking" 1577 depends on DEBUG_KERNEL 1578 select TORTURE_TEST 1579 help 1580 This option provides a kernel module that runs torture tests 1581 on kernel locking primitives. The kernel module may be built 1582 after the fact on the running kernel to be tested, if desired. 1583 1584 Say Y here if you want kernel locking-primitive torture tests 1585 to be built into the kernel. 1586 Say M if you want these torture tests to build as a module. 1587 Say N if you are unsure. 1588 1589config WW_MUTEX_SELFTEST 1590 tristate "Wait/wound mutex selftests" 1591 help 1592 This option provides a kernel module that runs tests on the 1593 on the struct ww_mutex locking API. 1594 1595 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1596 with this test harness. 1597 1598 Say M if you want these self tests to build as a module. 1599 Say N if you are unsure. 1600 1601config SCF_TORTURE_TEST 1602 tristate "torture tests for smp_call_function*()" 1603 depends on DEBUG_KERNEL 1604 select TORTURE_TEST 1605 help 1606 This option provides a kernel module that runs torture tests 1607 on the smp_call_function() family of primitives. The kernel 1608 module may be built after the fact on the running kernel to 1609 be tested, if desired. 1610 1611config CSD_LOCK_WAIT_DEBUG 1612 bool "Debugging for csd_lock_wait(), called from smp_call_function*()" 1613 depends on DEBUG_KERNEL 1614 depends on SMP 1615 depends on 64BIT 1616 default n 1617 help 1618 This option enables debug prints when CPUs are slow to respond 1619 to the smp_call_function*() IPI wrappers. These debug prints 1620 include the IPI handler function currently executing (if any) 1621 and relevant stack traces. 1622 1623config CSD_LOCK_WAIT_DEBUG_DEFAULT 1624 bool "Default csd_lock_wait() debugging on at boot time" 1625 depends on CSD_LOCK_WAIT_DEBUG 1626 depends on 64BIT 1627 default n 1628 help 1629 This option causes the csdlock_debug= kernel boot parameter to 1630 default to 1 (basic debugging) instead of 0 (no debugging). 1631 1632endmenu # lock debugging 1633 1634config TRACE_IRQFLAGS 1635 depends on TRACE_IRQFLAGS_SUPPORT 1636 bool 1637 help 1638 Enables hooks to interrupt enabling and disabling for 1639 either tracing or lock debugging. 1640 1641config TRACE_IRQFLAGS_NMI 1642 def_bool y 1643 depends on TRACE_IRQFLAGS 1644 depends on TRACE_IRQFLAGS_NMI_SUPPORT 1645 1646config NMI_CHECK_CPU 1647 bool "Debugging for CPUs failing to respond to backtrace requests" 1648 depends on DEBUG_KERNEL 1649 depends on X86 1650 default n 1651 help 1652 Enables debug prints when a CPU fails to respond to a given 1653 backtrace NMI. These prints provide some reasons why a CPU 1654 might legitimately be failing to respond, for example, if it 1655 is offline of if ignore_nmis is set. 1656 1657config DEBUG_IRQFLAGS 1658 bool "Debug IRQ flag manipulation" 1659 help 1660 Enables checks for potentially unsafe enabling or disabling of 1661 interrupts, such as calling raw_local_irq_restore() when interrupts 1662 are enabled. 1663 1664config STACKTRACE 1665 bool "Stack backtrace support" 1666 depends on STACKTRACE_SUPPORT 1667 help 1668 This option causes the kernel to create a /proc/pid/stack for 1669 every process, showing its current stack trace. 1670 It is also used by various kernel debugging features that require 1671 stack trace generation. 1672 1673config WARN_ALL_UNSEEDED_RANDOM 1674 bool "Warn for all uses of unseeded randomness" 1675 default n 1676 help 1677 Some parts of the kernel contain bugs relating to their use of 1678 cryptographically secure random numbers before it's actually possible 1679 to generate those numbers securely. This setting ensures that these 1680 flaws don't go unnoticed, by enabling a message, should this ever 1681 occur. This will allow people with obscure setups to know when things 1682 are going wrong, so that they might contact developers about fixing 1683 it. 1684 1685 Unfortunately, on some models of some architectures getting 1686 a fully seeded CRNG is extremely difficult, and so this can 1687 result in dmesg getting spammed for a surprisingly long 1688 time. This is really bad from a security perspective, and 1689 so architecture maintainers really need to do what they can 1690 to get the CRNG seeded sooner after the system is booted. 1691 However, since users cannot do anything actionable to 1692 address this, by default this option is disabled. 1693 1694 Say Y here if you want to receive warnings for all uses of 1695 unseeded randomness. This will be of use primarily for 1696 those developers interested in improving the security of 1697 Linux kernels running on their architecture (or 1698 subarchitecture). 1699 1700config DEBUG_KOBJECT 1701 bool "kobject debugging" 1702 depends on DEBUG_KERNEL 1703 help 1704 If you say Y here, some extra kobject debugging messages will be sent 1705 to the syslog. 1706 1707config DEBUG_KOBJECT_RELEASE 1708 bool "kobject release debugging" 1709 depends on DEBUG_OBJECTS_TIMERS 1710 help 1711 kobjects are reference counted objects. This means that their 1712 last reference count put is not predictable, and the kobject can 1713 live on past the point at which a driver decides to drop its 1714 initial reference to the kobject gained on allocation. An 1715 example of this would be a struct device which has just been 1716 unregistered. 1717 1718 However, some buggy drivers assume that after such an operation, 1719 the memory backing the kobject can be immediately freed. This 1720 goes completely against the principles of a refcounted object. 1721 1722 If you say Y here, the kernel will delay the release of kobjects 1723 on the last reference count to improve the visibility of this 1724 kind of kobject release bug. 1725 1726config HAVE_DEBUG_BUGVERBOSE 1727 bool 1728 1729menu "Debug kernel data structures" 1730 1731config DEBUG_LIST 1732 bool "Debug linked list manipulation" 1733 depends on DEBUG_KERNEL 1734 select LIST_HARDENED 1735 help 1736 Enable this to turn on extended checks in the linked-list walking 1737 routines. 1738 1739 This option trades better quality error reports for performance, and 1740 is more suitable for kernel debugging. If you care about performance, 1741 you should only enable CONFIG_LIST_HARDENED instead. 1742 1743 If unsure, say N. 1744 1745config DEBUG_PLIST 1746 bool "Debug priority linked list manipulation" 1747 depends on DEBUG_KERNEL 1748 help 1749 Enable this to turn on extended checks in the priority-ordered 1750 linked-list (plist) walking routines. This checks the entire 1751 list multiple times during each manipulation. 1752 1753 If unsure, say N. 1754 1755config DEBUG_SG 1756 bool "Debug SG table operations" 1757 depends on DEBUG_KERNEL 1758 help 1759 Enable this to turn on checks on scatter-gather tables. This can 1760 help find problems with drivers that do not properly initialize 1761 their sg tables. 1762 1763 If unsure, say N. 1764 1765config DEBUG_NOTIFIERS 1766 bool "Debug notifier call chains" 1767 depends on DEBUG_KERNEL 1768 help 1769 Enable this to turn on sanity checking for notifier call chains. 1770 This is most useful for kernel developers to make sure that 1771 modules properly unregister themselves from notifier chains. 1772 This is a relatively cheap check but if you care about maximum 1773 performance, say N. 1774 1775config DEBUG_CLOSURES 1776 bool "Debug closures (bcache async widgits)" 1777 depends on CLOSURES 1778 select DEBUG_FS 1779 help 1780 Keeps all active closures in a linked list and provides a debugfs 1781 interface to list them, which makes it possible to see asynchronous 1782 operations that get stuck. 1783 1784config DEBUG_MAPLE_TREE 1785 bool "Debug maple trees" 1786 depends on DEBUG_KERNEL 1787 help 1788 Enable maple tree debugging information and extra validations. 1789 1790 If unsure, say N. 1791 1792endmenu 1793 1794source "kernel/rcu/Kconfig.debug" 1795 1796config DEBUG_WQ_FORCE_RR_CPU 1797 bool "Force round-robin CPU selection for unbound work items" 1798 depends on DEBUG_KERNEL 1799 default n 1800 help 1801 Workqueue used to implicitly guarantee that work items queued 1802 without explicit CPU specified are put on the local CPU. This 1803 guarantee is no longer true and while local CPU is still 1804 preferred work items may be put on foreign CPUs. Kernel 1805 parameter "workqueue.debug_force_rr_cpu" is added to force 1806 round-robin CPU selection to flush out usages which depend on the 1807 now broken guarantee. This config option enables the debug 1808 feature by default. When enabled, memory and cache locality will 1809 be impacted. 1810 1811config CPU_HOTPLUG_STATE_CONTROL 1812 bool "Enable CPU hotplug state control" 1813 depends on DEBUG_KERNEL 1814 depends on HOTPLUG_CPU 1815 default n 1816 help 1817 Allows to write steps between "offline" and "online" to the CPUs 1818 sysfs target file so states can be stepped granular. This is a debug 1819 option for now as the hotplug machinery cannot be stopped and 1820 restarted at arbitrary points yet. 1821 1822 Say N if your are unsure. 1823 1824config LATENCYTOP 1825 bool "Latency measuring infrastructure" 1826 depends on DEBUG_KERNEL 1827 depends on STACKTRACE_SUPPORT 1828 depends on PROC_FS 1829 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 1830 select KALLSYMS 1831 select KALLSYMS_ALL 1832 select STACKTRACE 1833 select SCHEDSTATS 1834 help 1835 Enable this option if you want to use the LatencyTOP tool 1836 to find out which userspace is blocking on what kernel operations. 1837 1838config DEBUG_CGROUP_REF 1839 bool "Disable inlining of cgroup css reference count functions" 1840 depends on DEBUG_KERNEL 1841 depends on CGROUPS 1842 depends on KPROBES 1843 default n 1844 help 1845 Force cgroup css reference count functions to not be inlined so 1846 that they can be kprobed for debugging. 1847 1848source "kernel/trace/Kconfig" 1849 1850config PROVIDE_OHCI1394_DMA_INIT 1851 bool "Remote debugging over FireWire early on boot" 1852 depends on PCI && X86 1853 help 1854 If you want to debug problems which hang or crash the kernel early 1855 on boot and the crashing machine has a FireWire port, you can use 1856 this feature to remotely access the memory of the crashed machine 1857 over FireWire. This employs remote DMA as part of the OHCI1394 1858 specification which is now the standard for FireWire controllers. 1859 1860 With remote DMA, you can monitor the printk buffer remotely using 1861 firescope and access all memory below 4GB using fireproxy from gdb. 1862 Even controlling a kernel debugger is possible using remote DMA. 1863 1864 Usage: 1865 1866 If ohci1394_dma=early is used as boot parameter, it will initialize 1867 all OHCI1394 controllers which are found in the PCI config space. 1868 1869 As all changes to the FireWire bus such as enabling and disabling 1870 devices cause a bus reset and thereby disable remote DMA for all 1871 devices, be sure to have the cable plugged and FireWire enabled on 1872 the debugging host before booting the debug target for debugging. 1873 1874 This code (~1k) is freed after boot. By then, the firewire stack 1875 in charge of the OHCI-1394 controllers should be used instead. 1876 1877 See Documentation/core-api/debugging-via-ohci1394.rst for more information. 1878 1879source "samples/Kconfig" 1880 1881config ARCH_HAS_DEVMEM_IS_ALLOWED 1882 bool 1883 1884config STRICT_DEVMEM 1885 bool "Filter access to /dev/mem" 1886 depends on MMU && DEVMEM 1887 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED 1888 default y if PPC || X86 || ARM64 || S390 1889 help 1890 If this option is disabled, you allow userspace (root) access to all 1891 of memory, including kernel and userspace memory. Accidental 1892 access to this is obviously disastrous, but specific access can 1893 be used by people debugging the kernel. Note that with PAT support 1894 enabled, even in this case there are restrictions on /dev/mem 1895 use due to the cache aliasing requirements. 1896 1897 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 1898 file only allows userspace access to PCI space and the BIOS code and 1899 data regions. This is sufficient for dosemu and X and all common 1900 users of /dev/mem. 1901 1902 If in doubt, say Y. 1903 1904config IO_STRICT_DEVMEM 1905 bool "Filter I/O access to /dev/mem" 1906 depends on STRICT_DEVMEM 1907 help 1908 If this option is disabled, you allow userspace (root) access to all 1909 io-memory regardless of whether a driver is actively using that 1910 range. Accidental access to this is obviously disastrous, but 1911 specific access can be used by people debugging kernel drivers. 1912 1913 If this option is switched on, the /dev/mem file only allows 1914 userspace access to *idle* io-memory ranges (see /proc/iomem) This 1915 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 1916 if the driver using a given range cannot be disabled. 1917 1918 If in doubt, say Y. 1919 1920menu "$(SRCARCH) Debugging" 1921 1922source "arch/$(SRCARCH)/Kconfig.debug" 1923 1924endmenu 1925 1926menu "Kernel Testing and Coverage" 1927 1928source "lib/kunit/Kconfig" 1929 1930config NOTIFIER_ERROR_INJECTION 1931 tristate "Notifier error injection" 1932 depends on DEBUG_KERNEL 1933 select DEBUG_FS 1934 help 1935 This option provides the ability to inject artificial errors to 1936 specified notifier chain callbacks. It is useful to test the error 1937 handling of notifier call chain failures. 1938 1939 Say N if unsure. 1940 1941config PM_NOTIFIER_ERROR_INJECT 1942 tristate "PM notifier error injection module" 1943 depends on PM && NOTIFIER_ERROR_INJECTION 1944 default m if PM_DEBUG 1945 help 1946 This option provides the ability to inject artificial errors to 1947 PM notifier chain callbacks. It is controlled through debugfs 1948 interface /sys/kernel/debug/notifier-error-inject/pm 1949 1950 If the notifier call chain should be failed with some events 1951 notified, write the error code to "actions/<notifier event>/error". 1952 1953 Example: Inject PM suspend error (-12 = -ENOMEM) 1954 1955 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1956 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1957 # echo mem > /sys/power/state 1958 bash: echo: write error: Cannot allocate memory 1959 1960 To compile this code as a module, choose M here: the module will 1961 be called pm-notifier-error-inject. 1962 1963 If unsure, say N. 1964 1965config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1966 tristate "OF reconfig notifier error injection module" 1967 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1968 help 1969 This option provides the ability to inject artificial errors to 1970 OF reconfig notifier chain callbacks. It is controlled 1971 through debugfs interface under 1972 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1973 1974 If the notifier call chain should be failed with some events 1975 notified, write the error code to "actions/<notifier event>/error". 1976 1977 To compile this code as a module, choose M here: the module will 1978 be called of-reconfig-notifier-error-inject. 1979 1980 If unsure, say N. 1981 1982config NETDEV_NOTIFIER_ERROR_INJECT 1983 tristate "Netdev notifier error injection module" 1984 depends on NET && NOTIFIER_ERROR_INJECTION 1985 help 1986 This option provides the ability to inject artificial errors to 1987 netdevice notifier chain callbacks. It is controlled through debugfs 1988 interface /sys/kernel/debug/notifier-error-inject/netdev 1989 1990 If the notifier call chain should be failed with some events 1991 notified, write the error code to "actions/<notifier event>/error". 1992 1993 Example: Inject netdevice mtu change error (-22 = -EINVAL) 1994 1995 # cd /sys/kernel/debug/notifier-error-inject/netdev 1996 # echo -22 > actions/NETDEV_CHANGEMTU/error 1997 # ip link set eth0 mtu 1024 1998 RTNETLINK answers: Invalid argument 1999 2000 To compile this code as a module, choose M here: the module will 2001 be called netdev-notifier-error-inject. 2002 2003 If unsure, say N. 2004 2005config FUNCTION_ERROR_INJECTION 2006 bool "Fault-injections of functions" 2007 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 2008 help 2009 Add fault injections into various functions that are annotated with 2010 ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return 2011 value of these functions. This is useful to test error paths of code. 2012 2013 If unsure, say N 2014 2015config FAULT_INJECTION 2016 bool "Fault-injection framework" 2017 depends on DEBUG_KERNEL 2018 help 2019 Provide fault-injection framework. 2020 For more details, see Documentation/fault-injection/. 2021 2022config FAILSLAB 2023 bool "Fault-injection capability for kmalloc" 2024 depends on FAULT_INJECTION 2025 help 2026 Provide fault-injection capability for kmalloc. 2027 2028config FAIL_PAGE_ALLOC 2029 bool "Fault-injection capability for alloc_pages()" 2030 depends on FAULT_INJECTION 2031 help 2032 Provide fault-injection capability for alloc_pages(). 2033 2034config FAULT_INJECTION_USERCOPY 2035 bool "Fault injection capability for usercopy functions" 2036 depends on FAULT_INJECTION 2037 help 2038 Provides fault-injection capability to inject failures 2039 in usercopy functions (copy_from_user(), get_user(), ...). 2040 2041config FAIL_MAKE_REQUEST 2042 bool "Fault-injection capability for disk IO" 2043 depends on FAULT_INJECTION && BLOCK 2044 help 2045 Provide fault-injection capability for disk IO. 2046 2047config FAIL_IO_TIMEOUT 2048 bool "Fault-injection capability for faking disk interrupts" 2049 depends on FAULT_INJECTION && BLOCK 2050 help 2051 Provide fault-injection capability on end IO handling. This 2052 will make the block layer "forget" an interrupt as configured, 2053 thus exercising the error handling. 2054 2055 Only works with drivers that use the generic timeout handling, 2056 for others it won't do anything. 2057 2058config FAIL_FUTEX 2059 bool "Fault-injection capability for futexes" 2060 select DEBUG_FS 2061 depends on FAULT_INJECTION && FUTEX 2062 help 2063 Provide fault-injection capability for futexes. 2064 2065config FAULT_INJECTION_DEBUG_FS 2066 bool "Debugfs entries for fault-injection capabilities" 2067 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 2068 help 2069 Enable configuration of fault-injection capabilities via debugfs. 2070 2071config FAIL_FUNCTION 2072 bool "Fault-injection capability for functions" 2073 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 2074 help 2075 Provide function-based fault-injection capability. 2076 This will allow you to override a specific function with a return 2077 with given return value. As a result, function caller will see 2078 an error value and have to handle it. This is useful to test the 2079 error handling in various subsystems. 2080 2081config FAIL_MMC_REQUEST 2082 bool "Fault-injection capability for MMC IO" 2083 depends on FAULT_INJECTION_DEBUG_FS && MMC 2084 help 2085 Provide fault-injection capability for MMC IO. 2086 This will make the mmc core return data errors. This is 2087 useful to test the error handling in the mmc block device 2088 and to test how the mmc host driver handles retries from 2089 the block device. 2090 2091config FAIL_SUNRPC 2092 bool "Fault-injection capability for SunRPC" 2093 depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG 2094 help 2095 Provide fault-injection capability for SunRPC and 2096 its consumers. 2097 2098config FAIL_SKB_REALLOC 2099 bool "Fault-injection capability forcing skb to reallocate" 2100 depends on FAULT_INJECTION_DEBUG_FS 2101 help 2102 Provide fault-injection capability that forces the skb to be 2103 reallocated, catching possible invalid pointers to the skb. 2104 2105 For more information, check 2106 Documentation/dev-tools/fault-injection/fault-injection.rst 2107 2108config FAULT_INJECTION_CONFIGFS 2109 bool "Configfs interface for fault-injection capabilities" 2110 depends on FAULT_INJECTION 2111 select CONFIGFS_FS 2112 help 2113 This option allows configfs-based drivers to dynamically configure 2114 fault-injection via configfs. Each parameter for driver-specific 2115 fault-injection can be made visible as a configfs attribute in a 2116 configfs group. 2117 2118 2119config FAULT_INJECTION_STACKTRACE_FILTER 2120 bool "stacktrace filter for fault-injection capabilities" 2121 depends on FAULT_INJECTION 2122 depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT 2123 select STACKTRACE 2124 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 2125 help 2126 Provide stacktrace filter for fault-injection capabilities 2127 2128config ARCH_HAS_KCOV 2129 bool 2130 help 2131 An architecture should select this when it can successfully 2132 build and run with CONFIG_KCOV. This typically requires 2133 disabling instrumentation for some early boot code. 2134 2135config CC_HAS_SANCOV_TRACE_PC 2136 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 2137 2138 2139config KCOV 2140 bool "Code coverage for fuzzing" 2141 depends on ARCH_HAS_KCOV 2142 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 2143 depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \ 2144 GCC_VERSION >= 120000 || CC_IS_CLANG 2145 select DEBUG_FS 2146 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 2147 select OBJTOOL if HAVE_NOINSTR_HACK 2148 help 2149 KCOV exposes kernel code coverage information in a form suitable 2150 for coverage-guided fuzzing (randomized testing). 2151 2152 For more details, see Documentation/dev-tools/kcov.rst. 2153 2154config KCOV_ENABLE_COMPARISONS 2155 bool "Enable comparison operands collection by KCOV" 2156 depends on KCOV 2157 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 2158 help 2159 KCOV also exposes operands of every comparison in the instrumented 2160 code along with operand sizes and PCs of the comparison instructions. 2161 These operands can be used by fuzzing engines to improve the quality 2162 of fuzzing coverage. 2163 2164config KCOV_INSTRUMENT_ALL 2165 bool "Instrument all code by default" 2166 depends on KCOV 2167 default y 2168 help 2169 If you are doing generic system call fuzzing (like e.g. syzkaller), 2170 then you will want to instrument the whole kernel and you should 2171 say y here. If you are doing more targeted fuzzing (like e.g. 2172 filesystem fuzzing with AFL) then you will want to enable coverage 2173 for more specific subsets of files, and should say n here. 2174 2175config KCOV_IRQ_AREA_SIZE 2176 hex "Size of interrupt coverage collection area in words" 2177 depends on KCOV 2178 default 0x40000 2179 help 2180 KCOV uses preallocated per-cpu areas to collect coverage from 2181 soft interrupts. This specifies the size of those areas in the 2182 number of unsigned long words. 2183 2184config KCOV_SELFTEST 2185 bool "Perform short selftests on boot" 2186 depends on KCOV 2187 help 2188 Run short KCOV coverage collection selftests on boot. 2189 On test failure, causes the kernel to panic. Recommended to be 2190 enabled, ensuring critical functionality works as intended. 2191 2192menuconfig RUNTIME_TESTING_MENU 2193 bool "Runtime Testing" 2194 default y 2195 2196if RUNTIME_TESTING_MENU 2197 2198config TEST_DHRY 2199 tristate "Dhrystone benchmark test" 2200 help 2201 Enable this to include the Dhrystone 2.1 benchmark. This test 2202 calculates the number of Dhrystones per second, and the number of 2203 DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided 2204 by 1757 (the number of Dhrystones per second obtained on the VAX 2205 11/780, nominally a 1 MIPS machine). 2206 2207 To run the benchmark, it needs to be enabled explicitly, either from 2208 the kernel command line (when built-in), or from userspace (when 2209 built-in or modular). 2210 2211 Run once during kernel boot: 2212 2213 test_dhry.run 2214 2215 Set number of iterations from kernel command line: 2216 2217 test_dhry.iterations=<n> 2218 2219 Set number of iterations from userspace: 2220 2221 echo <n> > /sys/module/test_dhry/parameters/iterations 2222 2223 Trigger manual run from userspace: 2224 2225 echo y > /sys/module/test_dhry/parameters/run 2226 2227 If the number of iterations is <= 0, the test will devise a suitable 2228 number of iterations (test runs for at least 2s) automatically. 2229 This process takes ca. 4s. 2230 2231 If unsure, say N. 2232 2233config LKDTM 2234 tristate "Linux Kernel Dump Test Tool Module" 2235 depends on DEBUG_FS 2236 help 2237 This module enables testing of the different dumping mechanisms by 2238 inducing system failures at predefined crash points. 2239 If you don't need it: say N 2240 Choose M here to compile this code as a module. The module will be 2241 called lkdtm. 2242 2243 Documentation on how to use the module can be found in 2244 Documentation/fault-injection/provoke-crashes.rst 2245 2246config CPUMASK_KUNIT_TEST 2247 tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS 2248 depends on KUNIT 2249 default KUNIT_ALL_TESTS 2250 help 2251 Enable to turn on cpumask tests, running at boot or module load time. 2252 2253 For more information on KUnit and unit tests in general, please refer 2254 to the KUnit documentation in Documentation/dev-tools/kunit/. 2255 2256 If unsure, say N. 2257 2258config TEST_LIST_SORT 2259 tristate "Linked list sorting test" if !KUNIT_ALL_TESTS 2260 depends on KUNIT 2261 default KUNIT_ALL_TESTS 2262 help 2263 Enable this to turn on 'list_sort()' function test. This test is 2264 executed only once during system boot (so affects only boot time), 2265 or at module load time. 2266 2267 If unsure, say N. 2268 2269config TEST_MIN_HEAP 2270 tristate "Min heap test" 2271 depends on DEBUG_KERNEL || m 2272 help 2273 Enable this to turn on min heap function tests. This test is 2274 executed only once during system boot (so affects only boot time), 2275 or at module load time. 2276 2277 If unsure, say N. 2278 2279config TEST_SORT 2280 tristate "Array-based sort test" if !KUNIT_ALL_TESTS 2281 depends on KUNIT 2282 default KUNIT_ALL_TESTS 2283 help 2284 This option enables the self-test function of 'sort()' at boot, 2285 or at module load time. 2286 2287 If unsure, say N. 2288 2289config TEST_DIV64 2290 tristate "64bit/32bit division and modulo test" 2291 depends on DEBUG_KERNEL || m 2292 help 2293 Enable this to turn on 'do_div()' function test. This test is 2294 executed only once during system boot (so affects only boot time), 2295 or at module load time. 2296 2297 If unsure, say N. 2298 2299config TEST_MULDIV64 2300 tristate "mul_u64_u64_div_u64() test" 2301 depends on DEBUG_KERNEL || m 2302 help 2303 Enable this to turn on 'mul_u64_u64_div_u64()' function test. 2304 This test is executed only once during system boot (so affects 2305 only boot time), or at module load time. 2306 2307 If unsure, say N. 2308 2309config TEST_IOV_ITER 2310 tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS 2311 depends on KUNIT 2312 depends on MMU 2313 default KUNIT_ALL_TESTS 2314 help 2315 Enable this to turn on testing of the operation of the I/O iterator 2316 (iov_iter). This test is executed only once during system boot (so 2317 affects only boot time), or at module load time. 2318 2319 If unsure, say N. 2320 2321config KPROBES_SANITY_TEST 2322 tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS 2323 depends on DEBUG_KERNEL 2324 depends on KPROBES 2325 depends on KUNIT 2326 select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 2327 default KUNIT_ALL_TESTS 2328 help 2329 This option provides for testing basic kprobes functionality on 2330 boot. Samples of kprobe and kretprobe are inserted and 2331 verified for functionality. 2332 2333 Say N if you are unsure. 2334 2335config FPROBE_SANITY_TEST 2336 bool "Self test for fprobe" 2337 depends on DEBUG_KERNEL 2338 depends on FPROBE 2339 depends on KUNIT=y 2340 help 2341 This option will enable testing the fprobe when the system boot. 2342 A series of tests are made to verify that the fprobe is functioning 2343 properly. 2344 2345 Say N if you are unsure. 2346 2347config BACKTRACE_SELF_TEST 2348 tristate "Self test for the backtrace code" 2349 depends on DEBUG_KERNEL 2350 help 2351 This option provides a kernel module that can be used to test 2352 the kernel stack backtrace code. This option is not useful 2353 for distributions or general kernels, but only for kernel 2354 developers working on architecture code. 2355 2356 Note that if you want to also test saved backtraces, you will 2357 have to enable STACKTRACE as well. 2358 2359 Say N if you are unsure. 2360 2361config TEST_REF_TRACKER 2362 tristate "Self test for reference tracker" 2363 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT 2364 select REF_TRACKER 2365 help 2366 This option provides a kernel module performing tests 2367 using reference tracker infrastructure. 2368 2369 Say N if you are unsure. 2370 2371config RBTREE_TEST 2372 tristate "Red-Black tree test" 2373 depends on DEBUG_KERNEL 2374 help 2375 A benchmark measuring the performance of the rbtree library. 2376 Also includes rbtree invariant checks. 2377 2378config REED_SOLOMON_TEST 2379 tristate "Reed-Solomon library test" 2380 depends on DEBUG_KERNEL || m 2381 select REED_SOLOMON 2382 select REED_SOLOMON_ENC16 2383 select REED_SOLOMON_DEC16 2384 help 2385 This option enables the self-test function of rslib at boot, 2386 or at module load time. 2387 2388 If unsure, say N. 2389 2390config INTERVAL_TREE_TEST 2391 tristate "Interval tree test" 2392 depends on DEBUG_KERNEL 2393 select INTERVAL_TREE 2394 help 2395 A benchmark measuring the performance of the interval tree library 2396 2397config PERCPU_TEST 2398 tristate "Per cpu operations test" 2399 depends on m && DEBUG_KERNEL 2400 help 2401 Enable this option to build test module which validates per-cpu 2402 operations. 2403 2404 If unsure, say N. 2405 2406config ATOMIC64_SELFTEST 2407 tristate "Perform an atomic64_t self-test" 2408 help 2409 Enable this option to test the atomic64_t functions at boot or 2410 at module load time. 2411 2412 If unsure, say N. 2413 2414config ASYNC_RAID6_TEST 2415 tristate "Self test for hardware accelerated raid6 recovery" 2416 depends on ASYNC_RAID6_RECOV 2417 select ASYNC_MEMCPY 2418 help 2419 This is a one-shot self test that permutes through the 2420 recovery of all the possible two disk failure scenarios for a 2421 N-disk array. Recovery is performed with the asynchronous 2422 raid6 recovery routines, and will optionally use an offload 2423 engine if one is available. 2424 2425 If unsure, say N. 2426 2427config TEST_HEXDUMP 2428 tristate "Test functions located in the hexdump module at runtime" 2429 2430config STRING_KUNIT_TEST 2431 tristate "KUnit test string functions at runtime" if !KUNIT_ALL_TESTS 2432 depends on KUNIT 2433 default KUNIT_ALL_TESTS 2434 2435config STRING_HELPERS_KUNIT_TEST 2436 tristate "KUnit test string helpers at runtime" if !KUNIT_ALL_TESTS 2437 depends on KUNIT 2438 default KUNIT_ALL_TESTS 2439 2440config TEST_KSTRTOX 2441 tristate "Test kstrto*() family of functions at runtime" 2442 2443config TEST_PRINTF 2444 tristate "Test printf() family of functions at runtime" 2445 2446config TEST_SCANF 2447 tristate "Test scanf() family of functions at runtime" 2448 2449config TEST_BITMAP 2450 tristate "Test bitmap_*() family of functions at runtime" 2451 help 2452 Enable this option to test the bitmap functions at boot. 2453 2454 If unsure, say N. 2455 2456config TEST_UUID 2457 tristate "Test functions located in the uuid module at runtime" 2458 2459config TEST_XARRAY 2460 tristate "Test the XArray code at runtime" 2461 2462config TEST_MAPLE_TREE 2463 tristate "Test the Maple Tree code at runtime or module load" 2464 help 2465 Enable this option to test the maple tree code functions at boot, or 2466 when the module is loaded. Enable "Debug Maple Trees" will enable 2467 more verbose output on failures. 2468 2469 If unsure, say N. 2470 2471config TEST_RHASHTABLE 2472 tristate "Perform selftest on resizable hash table" 2473 help 2474 Enable this option to test the rhashtable functions at boot. 2475 2476 If unsure, say N. 2477 2478config TEST_IDA 2479 tristate "Perform selftest on IDA functions" 2480 2481config TEST_PARMAN 2482 tristate "Perform selftest on priority array manager" 2483 depends on PARMAN 2484 help 2485 Enable this option to test priority array manager on boot 2486 (or module load). 2487 2488 If unsure, say N. 2489 2490config TEST_IRQ_TIMINGS 2491 bool "IRQ timings selftest" 2492 depends on IRQ_TIMINGS 2493 help 2494 Enable this option to test the irq timings code on boot. 2495 2496 If unsure, say N. 2497 2498config TEST_LKM 2499 tristate "Test module loading with 'hello world' module" 2500 depends on m 2501 help 2502 This builds the "test_module" module that emits "Hello, world" 2503 on printk when loaded. It is designed to be used for basic 2504 evaluation of the module loading subsystem (for example when 2505 validating module verification). It lacks any extra dependencies, 2506 and will not normally be loaded by the system unless explicitly 2507 requested by name. 2508 2509 If unsure, say N. 2510 2511config TEST_BITOPS 2512 tristate "Test module for compilation of bitops operations" 2513 help 2514 This builds the "test_bitops" module that is much like the 2515 TEST_LKM module except that it does a basic exercise of the 2516 set/clear_bit macros and get_count_order/long to make sure there are 2517 no compiler warnings from C=1 sparse checker or -Wextra 2518 compilations. It has no dependencies and doesn't run or load unless 2519 explicitly requested by name. for example: modprobe test_bitops. 2520 2521 If unsure, say N. 2522 2523config TEST_VMALLOC 2524 tristate "Test module for stress/performance analysis of vmalloc allocator" 2525 default n 2526 depends on MMU 2527 depends on m 2528 help 2529 This builds the "test_vmalloc" module that should be used for 2530 stress and performance analysis. So, any new change for vmalloc 2531 subsystem can be evaluated from performance and stability point 2532 of view. 2533 2534 If unsure, say N. 2535 2536config TEST_BPF 2537 tristate "Test BPF filter functionality" 2538 depends on m && NET 2539 help 2540 This builds the "test_bpf" module that runs various test vectors 2541 against the BPF interpreter or BPF JIT compiler depending on the 2542 current setting. This is in particular useful for BPF JIT compiler 2543 development, but also to run regression tests against changes in 2544 the interpreter code. It also enables test stubs for eBPF maps and 2545 verifier used by user space verifier testsuite. 2546 2547 If unsure, say N. 2548 2549config TEST_BLACKHOLE_DEV 2550 tristate "Test blackhole netdev functionality" 2551 depends on m && NET 2552 help 2553 This builds the "test_blackhole_dev" module that validates the 2554 data path through this blackhole netdev. 2555 2556 If unsure, say N. 2557 2558config FIND_BIT_BENCHMARK 2559 tristate "Test find_bit functions" 2560 help 2561 This builds the "test_find_bit" module that measure find_*_bit() 2562 functions performance. 2563 2564 If unsure, say N. 2565 2566config TEST_FIRMWARE 2567 tristate "Test firmware loading via userspace interface" 2568 depends on FW_LOADER 2569 help 2570 This builds the "test_firmware" module that creates a userspace 2571 interface for testing firmware loading. This can be used to 2572 control the triggering of firmware loading without needing an 2573 actual firmware-using device. The contents can be rechecked by 2574 userspace. 2575 2576 If unsure, say N. 2577 2578config TEST_SYSCTL 2579 tristate "sysctl test driver" 2580 depends on PROC_SYSCTL 2581 help 2582 This builds the "test_sysctl" module. This driver enables to test the 2583 proc sysctl interfaces available to drivers safely without affecting 2584 production knobs which might alter system functionality. 2585 2586 If unsure, say N. 2587 2588config BITFIELD_KUNIT 2589 tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS 2590 depends on KUNIT 2591 default KUNIT_ALL_TESTS 2592 help 2593 Enable this option to test the bitfield functions at boot. 2594 2595 KUnit tests run during boot and output the results to the debug log 2596 in TAP format (http://testanything.org/). Only useful for kernel devs 2597 running the KUnit test harness, and not intended for inclusion into a 2598 production build. 2599 2600 For more information on KUnit and unit tests in general please refer 2601 to the KUnit documentation in Documentation/dev-tools/kunit/. 2602 2603 If unsure, say N. 2604 2605config CHECKSUM_KUNIT 2606 tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS 2607 depends on KUNIT 2608 default KUNIT_ALL_TESTS 2609 help 2610 Enable this option to test the checksum functions at boot. 2611 2612 KUnit tests run during boot and output the results to the debug log 2613 in TAP format (http://testanything.org/). Only useful for kernel devs 2614 running the KUnit test harness, and not intended for inclusion into a 2615 production build. 2616 2617 For more information on KUnit and unit tests in general please refer 2618 to the KUnit documentation in Documentation/dev-tools/kunit/. 2619 2620 If unsure, say N. 2621 2622config HASH_KUNIT_TEST 2623 tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS 2624 depends on KUNIT 2625 default KUNIT_ALL_TESTS 2626 help 2627 Enable this option to test the kernel's string (<linux/stringhash.h>), and 2628 integer (<linux/hash.h>) hash functions on boot. 2629 2630 KUnit tests run during boot and output the results to the debug log 2631 in TAP format (https://testanything.org/). Only useful for kernel devs 2632 running the KUnit test harness, and not intended for inclusion into a 2633 production build. 2634 2635 For more information on KUnit and unit tests in general please refer 2636 to the KUnit documentation in Documentation/dev-tools/kunit/. 2637 2638 This is intended to help people writing architecture-specific 2639 optimized versions. If unsure, say N. 2640 2641config RESOURCE_KUNIT_TEST 2642 tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS 2643 depends on KUNIT 2644 default KUNIT_ALL_TESTS 2645 select GET_FREE_REGION 2646 help 2647 This builds the resource API unit test. 2648 Tests the logic of API provided by resource.c and ioport.h. 2649 For more information on KUnit and unit tests in general please refer 2650 to the KUnit documentation in Documentation/dev-tools/kunit/. 2651 2652 If unsure, say N. 2653 2654config SYSCTL_KUNIT_TEST 2655 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS 2656 depends on KUNIT 2657 default KUNIT_ALL_TESTS 2658 help 2659 This builds the proc sysctl unit test, which runs on boot. 2660 Tests the API contract and implementation correctness of sysctl. 2661 For more information on KUnit and unit tests in general please refer 2662 to the KUnit documentation in Documentation/dev-tools/kunit/. 2663 2664 If unsure, say N. 2665 2666config LIST_KUNIT_TEST 2667 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS 2668 depends on KUNIT 2669 default KUNIT_ALL_TESTS 2670 help 2671 This builds the linked list KUnit test suite. 2672 It tests that the API and basic functionality of the list_head type 2673 and associated macros. 2674 2675 KUnit tests run during boot and output the results to the debug log 2676 in TAP format (https://testanything.org/). Only useful for kernel devs 2677 running the KUnit test harness, and not intended for inclusion into a 2678 production build. 2679 2680 For more information on KUnit and unit tests in general please refer 2681 to the KUnit documentation in Documentation/dev-tools/kunit/. 2682 2683 If unsure, say N. 2684 2685config HASHTABLE_KUNIT_TEST 2686 tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS 2687 depends on KUNIT 2688 default KUNIT_ALL_TESTS 2689 help 2690 This builds the hashtable KUnit test suite. 2691 It tests the basic functionality of the API defined in 2692 include/linux/hashtable.h. For more information on KUnit and 2693 unit tests in general please refer to the KUnit documentation 2694 in Documentation/dev-tools/kunit/. 2695 2696 If unsure, say N. 2697 2698config LINEAR_RANGES_TEST 2699 tristate "KUnit test for linear_ranges" 2700 depends on KUNIT 2701 select LINEAR_RANGES 2702 help 2703 This builds the linear_ranges unit test, which runs on boot. 2704 Tests the linear_ranges logic correctness. 2705 For more information on KUnit and unit tests in general please refer 2706 to the KUnit documentation in Documentation/dev-tools/kunit/. 2707 2708 If unsure, say N. 2709 2710config CMDLINE_KUNIT_TEST 2711 tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS 2712 depends on KUNIT 2713 default KUNIT_ALL_TESTS 2714 help 2715 This builds the cmdline API unit test. 2716 Tests the logic of API provided by cmdline.c. 2717 For more information on KUnit and unit tests in general please refer 2718 to the KUnit documentation in Documentation/dev-tools/kunit/. 2719 2720 If unsure, say N. 2721 2722config BITS_TEST 2723 tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS 2724 depends on KUNIT 2725 default KUNIT_ALL_TESTS 2726 help 2727 This builds the bits unit test. 2728 Tests the logic of macros defined in bits.h. 2729 For more information on KUnit and unit tests in general please refer 2730 to the KUnit documentation in Documentation/dev-tools/kunit/. 2731 2732 If unsure, say N. 2733 2734config SLUB_KUNIT_TEST 2735 tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS 2736 depends on SLUB_DEBUG && KUNIT 2737 default KUNIT_ALL_TESTS 2738 help 2739 This builds SLUB allocator unit test. 2740 Tests SLUB cache debugging functionality. 2741 For more information on KUnit and unit tests in general please refer 2742 to the KUnit documentation in Documentation/dev-tools/kunit/. 2743 2744 If unsure, say N. 2745 2746config RATIONAL_KUNIT_TEST 2747 tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS 2748 depends on KUNIT && RATIONAL 2749 default KUNIT_ALL_TESTS 2750 help 2751 This builds the rational math unit test. 2752 For more information on KUnit and unit tests in general please refer 2753 to the KUnit documentation in Documentation/dev-tools/kunit/. 2754 2755 If unsure, say N. 2756 2757config MEMCPY_KUNIT_TEST 2758 tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS 2759 depends on KUNIT 2760 default KUNIT_ALL_TESTS 2761 help 2762 Builds unit tests for memcpy(), memmove(), and memset() functions. 2763 For more information on KUnit and unit tests in general please refer 2764 to the KUnit documentation in Documentation/dev-tools/kunit/. 2765 2766 If unsure, say N. 2767 2768config IS_SIGNED_TYPE_KUNIT_TEST 2769 tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS 2770 depends on KUNIT 2771 default KUNIT_ALL_TESTS 2772 help 2773 Builds unit tests for the is_signed_type() macro. 2774 2775 For more information on KUnit and unit tests in general please refer 2776 to the KUnit documentation in Documentation/dev-tools/kunit/. 2777 2778 If unsure, say N. 2779 2780config OVERFLOW_KUNIT_TEST 2781 tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS 2782 depends on KUNIT 2783 default KUNIT_ALL_TESTS 2784 help 2785 Builds unit tests for the check_*_overflow(), size_*(), allocation, and 2786 related functions. 2787 2788 For more information on KUnit and unit tests in general please refer 2789 to the KUnit documentation in Documentation/dev-tools/kunit/. 2790 2791 If unsure, say N. 2792 2793config STACKINIT_KUNIT_TEST 2794 tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS 2795 depends on KUNIT 2796 default KUNIT_ALL_TESTS 2797 help 2798 Test if the kernel is zero-initializing stack variables and 2799 padding. Coverage is controlled by compiler flags, 2800 CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO, 2801 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2802 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2803 2804config FORTIFY_KUNIT_TEST 2805 tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS 2806 depends on KUNIT 2807 default KUNIT_ALL_TESTS 2808 help 2809 Builds unit tests for checking internals of FORTIFY_SOURCE as used 2810 by the str*() and mem*() family of functions. For testing runtime 2811 traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests. 2812 2813config HW_BREAKPOINT_KUNIT_TEST 2814 bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS 2815 depends on HAVE_HW_BREAKPOINT 2816 depends on KUNIT=y 2817 default KUNIT_ALL_TESTS 2818 help 2819 Tests for hw_breakpoint constraints accounting. 2820 2821 If unsure, say N. 2822 2823config SIPHASH_KUNIT_TEST 2824 tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS 2825 depends on KUNIT 2826 default KUNIT_ALL_TESTS 2827 help 2828 Enable this option to test the kernel's siphash (<linux/siphash.h>) hash 2829 functions on boot (or module load). 2830 2831 This is intended to help people writing architecture-specific 2832 optimized versions. If unsure, say N. 2833 2834config USERCOPY_KUNIT_TEST 2835 tristate "KUnit Test for user/kernel boundary protections" 2836 depends on KUNIT 2837 default KUNIT_ALL_TESTS 2838 help 2839 This builds the "usercopy_kunit" module that runs sanity checks 2840 on the copy_to/from_user infrastructure, making sure basic 2841 user/kernel boundary testing is working. 2842 2843config TEST_UDELAY 2844 tristate "udelay test driver" 2845 help 2846 This builds the "udelay_test" module that helps to make sure 2847 that udelay() is working properly. 2848 2849 If unsure, say N. 2850 2851config TEST_STATIC_KEYS 2852 tristate "Test static keys" 2853 depends on m 2854 help 2855 Test the static key interfaces. 2856 2857 If unsure, say N. 2858 2859config TEST_DYNAMIC_DEBUG 2860 tristate "Test DYNAMIC_DEBUG" 2861 depends on DYNAMIC_DEBUG 2862 help 2863 This module registers a tracer callback to count enabled 2864 pr_debugs in a 'do_debugging' function, then alters their 2865 enablements, calls the function, and compares counts. 2866 2867 If unsure, say N. 2868 2869config TEST_KMOD 2870 tristate "kmod stress tester" 2871 depends on m 2872 depends on NETDEVICES && NET_CORE && INET # for TUN 2873 depends on BLOCK 2874 depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS 2875 select TEST_LKM 2876 select XFS_FS 2877 select TUN 2878 select BTRFS_FS 2879 help 2880 Test the kernel's module loading mechanism: kmod. kmod implements 2881 support to load modules using the Linux kernel's usermode helper. 2882 This test provides a series of tests against kmod. 2883 2884 Although technically you can either build test_kmod as a module or 2885 into the kernel we disallow building it into the kernel since 2886 it stress tests request_module() and this will very likely cause 2887 some issues by taking over precious threads available from other 2888 module load requests, ultimately this could be fatal. 2889 2890 To run tests run: 2891 2892 tools/testing/selftests/kmod/kmod.sh --help 2893 2894 If unsure, say N. 2895 2896config TEST_DEBUG_VIRTUAL 2897 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 2898 depends on DEBUG_VIRTUAL 2899 help 2900 Test the kernel's ability to detect incorrect calls to 2901 virt_to_phys() done against the non-linear part of the 2902 kernel's virtual address map. 2903 2904 If unsure, say N. 2905 2906config TEST_MEMCAT_P 2907 tristate "Test memcat_p() helper function" 2908 help 2909 Test the memcat_p() helper for correctly merging two 2910 pointer arrays together. 2911 2912 If unsure, say N. 2913 2914config TEST_OBJAGG 2915 tristate "Perform selftest on object aggreration manager" 2916 default n 2917 depends on OBJAGG 2918 help 2919 Enable this option to test object aggregation manager on boot 2920 (or module load). 2921 2922config TEST_MEMINIT 2923 tristate "Test heap/page initialization" 2924 help 2925 Test if the kernel is zero-initializing heap and page allocations. 2926 This can be useful to test init_on_alloc and init_on_free features. 2927 2928 If unsure, say N. 2929 2930config TEST_HMM 2931 tristate "Test HMM (Heterogeneous Memory Management)" 2932 depends on TRANSPARENT_HUGEPAGE 2933 depends on DEVICE_PRIVATE 2934 select HMM_MIRROR 2935 select MMU_NOTIFIER 2936 help 2937 This is a pseudo device driver solely for testing HMM. 2938 Say M here if you want to build the HMM test module. 2939 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests. 2940 2941 If unsure, say N. 2942 2943config TEST_FREE_PAGES 2944 tristate "Test freeing pages" 2945 help 2946 Test that a memory leak does not occur due to a race between 2947 freeing a block of pages and a speculative page reference. 2948 Loading this module is safe if your kernel has the bug fixed. 2949 If the bug is not fixed, it will leak gigabytes of memory and 2950 probably OOM your system. 2951 2952config TEST_FPU 2953 tristate "Test floating point operations in kernel space" 2954 depends on ARCH_HAS_KERNEL_FPU_SUPPORT && !KCOV_INSTRUMENT_ALL 2955 help 2956 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu 2957 which will trigger a sequence of floating point operations. This is used 2958 for self-testing floating point control register setting in 2959 kernel_fpu_begin(). 2960 2961 If unsure, say N. 2962 2963config TEST_CLOCKSOURCE_WATCHDOG 2964 tristate "Test clocksource watchdog in kernel space" 2965 depends on CLOCKSOURCE_WATCHDOG 2966 help 2967 Enable this option to create a kernel module that will trigger 2968 a test of the clocksource watchdog. This module may be loaded 2969 via modprobe or insmod in which case it will run upon being 2970 loaded, or it may be built in, in which case it will run 2971 shortly after boot. 2972 2973 If unsure, say N. 2974 2975config TEST_OBJPOOL 2976 tristate "Test module for correctness and stress of objpool" 2977 default n 2978 depends on m && DEBUG_KERNEL 2979 help 2980 This builds the "test_objpool" module that should be used for 2981 correctness verification and concurrent testings of objects 2982 allocation and reclamation. 2983 2984 If unsure, say N. 2985 2986endif # RUNTIME_TESTING_MENU 2987 2988config ARCH_USE_MEMTEST 2989 bool 2990 help 2991 An architecture should select this when it uses early_memtest() 2992 during boot process. 2993 2994config MEMTEST 2995 bool "Memtest" 2996 depends on ARCH_USE_MEMTEST 2997 help 2998 This option adds a kernel parameter 'memtest', which allows memtest 2999 to be set and executed. 3000 memtest=0, mean disabled; -- default 3001 memtest=1, mean do 1 test pattern; 3002 ... 3003 memtest=17, mean do 17 test patterns. 3004 If you are unsure how to answer this question, answer N. 3005 3006 3007 3008config HYPERV_TESTING 3009 bool "Microsoft Hyper-V driver testing" 3010 default n 3011 depends on HYPERV && DEBUG_FS 3012 help 3013 Select this option to enable Hyper-V vmbus testing. 3014 3015endmenu # "Kernel Testing and Coverage" 3016 3017menu "Rust hacking" 3018 3019config RUST_DEBUG_ASSERTIONS 3020 bool "Debug assertions" 3021 depends on RUST 3022 help 3023 Enables rustc's `-Cdebug-assertions` codegen option. 3024 3025 This flag lets you turn `cfg(debug_assertions)` conditional 3026 compilation on or off. This can be used to enable extra debugging 3027 code in development but not in production. For example, it controls 3028 the behavior of the standard library's `debug_assert!` macro. 3029 3030 Note that this will apply to all Rust code, including `core`. 3031 3032 If unsure, say N. 3033 3034config RUST_OVERFLOW_CHECKS 3035 bool "Overflow checks" 3036 default y 3037 depends on RUST 3038 help 3039 Enables rustc's `-Coverflow-checks` codegen option. 3040 3041 This flag allows you to control the behavior of runtime integer 3042 overflow. When overflow-checks are enabled, a Rust panic will occur 3043 on overflow. 3044 3045 Note that this will apply to all Rust code, including `core`. 3046 3047 If unsure, say Y. 3048 3049config RUST_BUILD_ASSERT_ALLOW 3050 bool "Allow unoptimized build-time assertions" 3051 depends on RUST 3052 help 3053 Controls how `build_error!` and `build_assert!` are handled during the build. 3054 3055 If calls to them exist in the binary, it may indicate a violated invariant 3056 or that the optimizer failed to verify the invariant during compilation. 3057 3058 This should not happen, thus by default the build is aborted. However, 3059 as an escape hatch, you can choose Y here to ignore them during build 3060 and let the check be carried at runtime (with `panic!` being called if 3061 the check fails). 3062 3063 If unsure, say N. 3064 3065config RUST_KERNEL_DOCTESTS 3066 bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS 3067 depends on RUST && KUNIT=y 3068 default KUNIT_ALL_TESTS 3069 help 3070 This builds the documentation tests of the `kernel` crate 3071 as KUnit tests. 3072 3073 For more information on KUnit and unit tests in general, 3074 please refer to the KUnit documentation in Documentation/dev-tools/kunit/. 3075 3076 If unsure, say N. 3077 3078endmenu # "Rust" 3079 3080endmenu # Kernel hacking 3081 3082config INT_POW_TEST 3083 tristate "Integer exponentiation (int_pow) test" if !KUNIT_ALL_TESTS 3084 depends on KUNIT 3085 default KUNIT_ALL_TESTS 3086 help 3087 This option enables the KUnit test suite for the int_pow function, 3088 which performs integer exponentiation. The test suite is designed to 3089 verify that the implementation of int_pow correctly computes the power 3090 of a given base raised to a given exponent. 3091 3092 Enabling this option will include tests that check various scenarios 3093 and edge cases to ensure the accuracy and reliability of the exponentiation 3094 function. 3095 3096 If unsure, say N 3097