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/process/debugging/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_VFS 812 bool "Debug VFS" 813 depends on DEBUG_KERNEL 814 help 815 Enable this to turn on extended checks in the VFS layer that may impact 816 performance. 817 818 If unsure, say N. 819 820config DEBUG_VM_IRQSOFF 821 def_bool DEBUG_VM && !PREEMPT_RT 822 823config DEBUG_VM 824 bool "Debug VM" 825 depends on DEBUG_KERNEL 826 help 827 Enable this to turn on extended checks in the virtual-memory system 828 that may impact performance. 829 830 If unsure, say N. 831 832config DEBUG_VM_SHOOT_LAZIES 833 bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation" 834 depends on DEBUG_VM 835 depends on MMU_LAZY_TLB_SHOOTDOWN 836 help 837 Enable additional IPIs that ensure lazy tlb mm references are removed 838 before the mm is freed. 839 840 If unsure, say N. 841 842config DEBUG_VM_MAPLE_TREE 843 bool "Debug VM maple trees" 844 depends on DEBUG_VM 845 select DEBUG_MAPLE_TREE 846 help 847 Enable VM maple tree debugging information and extra validations. 848 849 If unsure, say N. 850 851config DEBUG_VM_RB 852 bool "Debug VM red-black trees" 853 depends on DEBUG_VM 854 help 855 Enable VM red-black tree debugging information and extra validations. 856 857 If unsure, say N. 858 859config DEBUG_VM_PGFLAGS 860 bool "Debug page-flags operations" 861 depends on DEBUG_VM 862 help 863 Enables extra validation on page flags operations. 864 865 If unsure, say N. 866 867config DEBUG_VM_PGTABLE 868 bool "Debug arch page table for semantics compliance" 869 depends on MMU 870 depends on ARCH_HAS_DEBUG_VM_PGTABLE 871 default y if DEBUG_VM 872 help 873 This option provides a debug method which can be used to test 874 architecture page table helper functions on various platforms in 875 verifying if they comply with expected generic MM semantics. This 876 will help architecture code in making sure that any changes or 877 new additions of these helpers still conform to expected 878 semantics of the generic MM. Platforms will have to opt in for 879 this through ARCH_HAS_DEBUG_VM_PGTABLE. 880 881 If unsure, say N. 882 883config ARCH_HAS_DEBUG_VIRTUAL 884 bool 885 886config DEBUG_VIRTUAL 887 bool "Debug VM translations" 888 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL 889 help 890 Enable some costly sanity checks in virtual to page code. This can 891 catch mistakes with virt_to_page() and friends. 892 893 If unsure, say N. 894 895config DEBUG_NOMMU_REGIONS 896 bool "Debug the global anon/private NOMMU mapping region tree" 897 depends on DEBUG_KERNEL && !MMU 898 help 899 This option causes the global tree of anonymous and private mapping 900 regions to be regularly checked for invalid topology. 901 902config DEBUG_MEMORY_INIT 903 bool "Debug memory initialisation" if EXPERT 904 default !EXPERT 905 help 906 Enable this for additional checks during memory initialisation. 907 The sanity checks verify aspects of the VM such as the memory model 908 and other information provided by the architecture. Verbose 909 information will be printed at KERN_DEBUG loglevel depending 910 on the mminit_loglevel= command-line option. 911 912 If unsure, say Y 913 914config MEMORY_NOTIFIER_ERROR_INJECT 915 tristate "Memory hotplug notifier error injection module" 916 depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION 917 help 918 This option provides the ability to inject artificial errors to 919 memory hotplug notifier chain callbacks. It is controlled through 920 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 921 922 If the notifier call chain should be failed with some events 923 notified, write the error code to "actions/<notifier event>/error". 924 925 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 926 927 # cd /sys/kernel/debug/notifier-error-inject/memory 928 # echo -12 > actions/MEM_GOING_OFFLINE/error 929 # echo offline > /sys/devices/system/memory/memoryXXX/state 930 bash: echo: write error: Cannot allocate memory 931 932 To compile this code as a module, choose M here: the module will 933 be called memory-notifier-error-inject. 934 935 If unsure, say N. 936 937config DEBUG_PER_CPU_MAPS 938 bool "Debug access to per_cpu maps" 939 depends on DEBUG_KERNEL 940 depends on SMP 941 help 942 Say Y to verify that the per_cpu map being accessed has 943 been set up. This adds a fair amount of code to kernel memory 944 and decreases performance. 945 946 Say N if unsure. 947 948config DEBUG_KMAP_LOCAL 949 bool "Debug kmap_local temporary mappings" 950 depends on DEBUG_KERNEL && KMAP_LOCAL 951 help 952 This option enables additional error checking for the kmap_local 953 infrastructure. Disable for production use. 954 955config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 956 bool 957 958config DEBUG_KMAP_LOCAL_FORCE_MAP 959 bool "Enforce kmap_local temporary mappings" 960 depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 961 select KMAP_LOCAL 962 select DEBUG_KMAP_LOCAL 963 help 964 This option enforces temporary mappings through the kmap_local 965 mechanism for non-highmem pages and on non-highmem systems. 966 Disable this for production systems! 967 968config DEBUG_HIGHMEM 969 bool "Highmem debugging" 970 depends on DEBUG_KERNEL && HIGHMEM 971 select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 972 select DEBUG_KMAP_LOCAL 973 help 974 This option enables additional error checking for high memory 975 systems. Disable for production systems. 976 977config HAVE_DEBUG_STACKOVERFLOW 978 bool 979 980config DEBUG_STACKOVERFLOW 981 bool "Check for stack overflows" 982 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 983 help 984 Say Y here if you want to check for overflows of kernel, IRQ 985 and exception stacks (if your architecture uses them). This 986 option will show detailed messages if free stack space drops 987 below a certain limit. 988 989 These kinds of bugs usually occur when call-chains in the 990 kernel get too deep, especially when interrupts are 991 involved. 992 993 Use this in cases where you see apparently random memory 994 corruption, especially if it appears in 'struct thread_info' 995 996 If in doubt, say "N". 997 998config CODE_TAGGING 999 bool 1000 select KALLSYMS 1001 1002config MEM_ALLOC_PROFILING 1003 bool "Enable memory allocation profiling" 1004 default n 1005 depends on MMU 1006 depends on PROC_FS 1007 depends on !DEBUG_FORCE_WEAK_PER_CPU 1008 select CODE_TAGGING 1009 select PAGE_EXTENSION 1010 select SLAB_OBJ_EXT 1011 help 1012 Track allocation source code and record total allocation size 1013 initiated at that code location. The mechanism can be used to track 1014 memory leaks with a low performance and memory impact. 1015 1016config MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT 1017 bool "Enable memory allocation profiling by default" 1018 default y 1019 depends on MEM_ALLOC_PROFILING 1020 1021config MEM_ALLOC_PROFILING_DEBUG 1022 bool "Memory allocation profiler debugging" 1023 default n 1024 depends on MEM_ALLOC_PROFILING 1025 select MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT 1026 help 1027 Adds warnings with helpful error messages for memory allocation 1028 profiling. 1029 1030source "lib/Kconfig.kasan" 1031source "lib/Kconfig.kfence" 1032source "lib/Kconfig.kmsan" 1033 1034endmenu # "Memory Debugging" 1035 1036config DEBUG_SHIRQ 1037 bool "Debug shared IRQ handlers" 1038 depends on DEBUG_KERNEL 1039 help 1040 Enable this to generate a spurious interrupt just before a shared 1041 interrupt handler is deregistered (generating one when registering 1042 is currently disabled). Drivers need to handle this correctly. Some 1043 don't and need to be caught. 1044 1045menu "Debug Oops, Lockups and Hangs" 1046 1047config PANIC_ON_OOPS 1048 bool "Panic on Oops" 1049 help 1050 Say Y here to enable the kernel to panic when it oopses. This 1051 has the same effect as setting oops=panic on the kernel command 1052 line. 1053 1054 This feature is useful to ensure that the kernel does not do 1055 anything erroneous after an oops which could result in data 1056 corruption or other issues. 1057 1058 Say N if unsure. 1059 1060config PANIC_ON_OOPS_VALUE 1061 int 1062 range 0 1 1063 default 0 if !PANIC_ON_OOPS 1064 default 1 if PANIC_ON_OOPS 1065 1066config PANIC_TIMEOUT 1067 int "panic timeout" 1068 default 0 1069 help 1070 Set the timeout value (in seconds) until a reboot occurs when 1071 the kernel panics. If n = 0, then we wait forever. A timeout 1072 value n > 0 will wait n seconds before rebooting, while a timeout 1073 value n < 0 will reboot immediately. This setting can be overridden 1074 with the kernel command line option panic=, and from userspace via 1075 /proc/sys/kernel/panic. 1076 1077config LOCKUP_DETECTOR 1078 bool 1079 1080config SOFTLOCKUP_DETECTOR 1081 bool "Detect Soft Lockups" 1082 depends on DEBUG_KERNEL && !S390 1083 select LOCKUP_DETECTOR 1084 help 1085 Say Y here to enable the kernel to act as a watchdog to detect 1086 soft lockups. 1087 1088 Softlockups are bugs that cause the kernel to loop in kernel 1089 mode for more than 20 seconds, without giving other tasks a 1090 chance to run. The current stack trace is displayed upon 1091 detection and the system will stay locked up. 1092 1093config SOFTLOCKUP_DETECTOR_INTR_STORM 1094 bool "Detect Interrupt Storm in Soft Lockups" 1095 depends on SOFTLOCKUP_DETECTOR && IRQ_TIME_ACCOUNTING 1096 select GENERIC_IRQ_STAT_SNAPSHOT 1097 default y if NR_CPUS <= 128 1098 help 1099 Say Y here to enable the kernel to detect interrupt storm 1100 during "soft lockups". 1101 1102 "soft lockups" can be caused by a variety of reasons. If one is 1103 caused by an interrupt storm, then the storming interrupts will not 1104 be on the callstack. To detect this case, it is necessary to report 1105 the CPU stats and the interrupt counts during the "soft lockups". 1106 1107config BOOTPARAM_SOFTLOCKUP_PANIC 1108 bool "Panic (Reboot) On Soft Lockups" 1109 depends on SOFTLOCKUP_DETECTOR 1110 help 1111 Say Y here to enable the kernel to panic on "soft lockups", 1112 which are bugs that cause the kernel to loop in kernel 1113 mode for more than 20 seconds (configurable using the watchdog_thresh 1114 sysctl), without giving other tasks a chance to run. 1115 1116 The panic can be used in combination with panic_timeout, 1117 to cause the system to reboot automatically after a 1118 lockup has been detected. This feature is useful for 1119 high-availability systems that have uptime guarantees and 1120 where a lockup must be resolved ASAP. 1121 1122 Say N if unsure. 1123 1124config HAVE_HARDLOCKUP_DETECTOR_BUDDY 1125 bool 1126 depends on SMP 1127 default y 1128 1129# 1130# Global switch whether to build a hardlockup detector at all. It is available 1131# only when the architecture supports at least one implementation. There are 1132# two exceptions. The hardlockup detector is never enabled on: 1133# 1134# s390: it reported many false positives there 1135# 1136# sparc64: has a custom implementation which is not using the common 1137# hardlockup command line options and sysctl interface. 1138# 1139config HARDLOCKUP_DETECTOR 1140 bool "Detect Hard Lockups" 1141 depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64 1142 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH 1143 imply HARDLOCKUP_DETECTOR_PERF 1144 imply HARDLOCKUP_DETECTOR_BUDDY 1145 imply HARDLOCKUP_DETECTOR_ARCH 1146 select LOCKUP_DETECTOR 1147 1148 help 1149 Say Y here to enable the kernel to act as a watchdog to detect 1150 hard lockups. 1151 1152 Hardlockups are bugs that cause the CPU to loop in kernel mode 1153 for more than 10 seconds, without letting other interrupts have a 1154 chance to run. The current stack trace is displayed upon detection 1155 and the system will stay locked up. 1156 1157# 1158# Note that arch-specific variants are always preferred. 1159# 1160config HARDLOCKUP_DETECTOR_PREFER_BUDDY 1161 bool "Prefer the buddy CPU hardlockup detector" 1162 depends on HARDLOCKUP_DETECTOR 1163 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY 1164 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1165 help 1166 Say Y here to prefer the buddy hardlockup detector over the perf one. 1167 1168 With the buddy detector, each CPU uses its softlockup hrtimer 1169 to check that the next CPU is processing hrtimer interrupts by 1170 verifying that a counter is increasing. 1171 1172 This hardlockup detector is useful on systems that don't have 1173 an arch-specific hardlockup detector or if resources needed 1174 for the hardlockup detector are better used for other things. 1175 1176config HARDLOCKUP_DETECTOR_PERF 1177 bool 1178 depends on HARDLOCKUP_DETECTOR 1179 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY 1180 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1181 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1182 1183config HARDLOCKUP_DETECTOR_BUDDY 1184 bool 1185 depends on HARDLOCKUP_DETECTOR 1186 depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY 1187 depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY 1188 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1189 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1190 1191config HARDLOCKUP_DETECTOR_ARCH 1192 bool 1193 depends on HARDLOCKUP_DETECTOR 1194 depends on HAVE_HARDLOCKUP_DETECTOR_ARCH 1195 help 1196 The arch-specific implementation of the hardlockup detector will 1197 be used. 1198 1199# 1200# Both the "perf" and "buddy" hardlockup detectors count hrtimer 1201# interrupts. This config enables functions managing this common code. 1202# 1203config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1204 bool 1205 select SOFTLOCKUP_DETECTOR 1206 1207# 1208# Enables a timestamp based low pass filter to compensate for perf based 1209# hard lockup detection which runs too fast due to turbo modes. 1210# 1211config HARDLOCKUP_CHECK_TIMESTAMP 1212 bool 1213 1214config BOOTPARAM_HARDLOCKUP_PANIC 1215 bool "Panic (Reboot) On Hard Lockups" 1216 depends on HARDLOCKUP_DETECTOR 1217 help 1218 Say Y here to enable the kernel to panic on "hard lockups", 1219 which are bugs that cause the kernel to loop in kernel 1220 mode with interrupts disabled for more than 10 seconds (configurable 1221 using the watchdog_thresh sysctl). 1222 1223 Say N if unsure. 1224 1225config DETECT_HUNG_TASK 1226 bool "Detect Hung Tasks" 1227 depends on DEBUG_KERNEL 1228 default SOFTLOCKUP_DETECTOR 1229 help 1230 Say Y here to enable the kernel to detect "hung tasks", 1231 which are bugs that cause the task to be stuck in 1232 uninterruptible "D" state indefinitely. 1233 1234 When a hung task is detected, the kernel will print the 1235 current stack trace (which you should report), but the 1236 task will stay in uninterruptible state. If lockdep is 1237 enabled then all held locks will also be reported. This 1238 feature has negligible overhead. 1239 1240config DEFAULT_HUNG_TASK_TIMEOUT 1241 int "Default timeout for hung task detection (in seconds)" 1242 depends on DETECT_HUNG_TASK 1243 default 120 1244 help 1245 This option controls the default timeout (in seconds) used 1246 to determine when a task has become non-responsive and should 1247 be considered hung. 1248 1249 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 1250 sysctl or by writing a value to 1251 /proc/sys/kernel/hung_task_timeout_secs. 1252 1253 A timeout of 0 disables the check. The default is two minutes. 1254 Keeping the default should be fine in most cases. 1255 1256config BOOTPARAM_HUNG_TASK_PANIC 1257 bool "Panic (Reboot) On Hung Tasks" 1258 depends on DETECT_HUNG_TASK 1259 help 1260 Say Y here to enable the kernel to panic on "hung tasks", 1261 which are bugs that cause the kernel to leave a task stuck 1262 in uninterruptible "D" state. 1263 1264 The panic can be used in combination with panic_timeout, 1265 to cause the system to reboot automatically after a 1266 hung task has been detected. This feature is useful for 1267 high-availability systems that have uptime guarantees and 1268 where a hung tasks must be resolved ASAP. 1269 1270 Say N if unsure. 1271 1272config WQ_WATCHDOG 1273 bool "Detect Workqueue Stalls" 1274 depends on DEBUG_KERNEL 1275 help 1276 Say Y here to enable stall detection on workqueues. If a 1277 worker pool doesn't make forward progress on a pending work 1278 item for over a given amount of time, 30s by default, a 1279 warning message is printed along with dump of workqueue 1280 state. This can be configured through kernel parameter 1281 "workqueue.watchdog_thresh" and its sysfs counterpart. 1282 1283config WQ_CPU_INTENSIVE_REPORT 1284 bool "Report per-cpu work items which hog CPU for too long" 1285 depends on DEBUG_KERNEL 1286 help 1287 Say Y here to enable reporting of concurrency-managed per-cpu work 1288 items that hog CPUs for longer than 1289 workqueue.cpu_intensive_thresh_us. Workqueue automatically 1290 detects and excludes them from concurrency management to prevent 1291 them from stalling other per-cpu work items. Occassional 1292 triggering may not necessarily indicate a problem. Repeated 1293 triggering likely indicates that the work item should be switched 1294 to use an unbound workqueue. 1295 1296config TEST_LOCKUP 1297 tristate "Test module to generate lockups" 1298 depends on m 1299 help 1300 This builds the "test_lockup" module that helps to make sure 1301 that watchdogs and lockup detectors are working properly. 1302 1303 Depending on module parameters it could emulate soft or hard 1304 lockup, "hung task", or locking arbitrary lock for a long time. 1305 Also it could generate series of lockups with cooling-down periods. 1306 1307 If unsure, say N. 1308 1309endmenu # "Debug lockups and hangs" 1310 1311menu "Scheduler Debugging" 1312 1313config SCHED_DEBUG 1314 bool "Collect scheduler debugging info" 1315 depends on DEBUG_KERNEL && DEBUG_FS 1316 default y 1317 help 1318 If you say Y here, the /sys/kernel/debug/sched file will be provided 1319 that can help debug the scheduler. The runtime overhead of this 1320 option is minimal. 1321 1322config SCHED_INFO 1323 bool 1324 default n 1325 1326config SCHEDSTATS 1327 bool "Collect scheduler statistics" 1328 depends on PROC_FS 1329 select SCHED_INFO 1330 help 1331 If you say Y here, additional code will be inserted into the 1332 scheduler and related routines to collect statistics about 1333 scheduler behavior and provide them in /proc/schedstat. These 1334 stats may be useful for both tuning and debugging the scheduler 1335 If you aren't debugging the scheduler or trying to tune a specific 1336 application, you can say N to avoid the very slight overhead 1337 this adds. 1338 1339endmenu 1340 1341config DEBUG_PREEMPT 1342 bool "Debug preemptible kernel" 1343 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1344 help 1345 If you say Y here then the kernel will use a debug variant of the 1346 commonly used smp_processor_id() function and will print warnings 1347 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1348 will detect preemption count underflows. 1349 1350 This option has potential to introduce high runtime overhead, 1351 depending on workload as it triggers debugging routines for each 1352 this_cpu operation. It should only be used for debugging purposes. 1353 1354menu "Lock Debugging (spinlocks, mutexes, etc...)" 1355 1356config LOCK_DEBUGGING_SUPPORT 1357 bool 1358 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1359 default y 1360 1361config PROVE_LOCKING 1362 bool "Lock debugging: prove locking correctness" 1363 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1364 select LOCKDEP 1365 select DEBUG_SPINLOCK 1366 select DEBUG_MUTEXES if !PREEMPT_RT 1367 select DEBUG_RT_MUTEXES if RT_MUTEXES 1368 select DEBUG_RWSEMS if !PREEMPT_RT 1369 select DEBUG_WW_MUTEX_SLOWPATH 1370 select DEBUG_LOCK_ALLOC 1371 select PREEMPT_COUNT if !ARCH_NO_PREEMPT 1372 select TRACE_IRQFLAGS 1373 default n 1374 help 1375 This feature enables the kernel to prove that all locking 1376 that occurs in the kernel runtime is mathematically 1377 correct: that under no circumstance could an arbitrary (and 1378 not yet triggered) combination of observed locking 1379 sequences (on an arbitrary number of CPUs, running an 1380 arbitrary number of tasks and interrupt contexts) cause a 1381 deadlock. 1382 1383 In short, this feature enables the kernel to report locking 1384 related deadlocks before they actually occur. 1385 1386 The proof does not depend on how hard and complex a 1387 deadlock scenario would be to trigger: how many 1388 participant CPUs, tasks and irq-contexts would be needed 1389 for it to trigger. The proof also does not depend on 1390 timing: if a race and a resulting deadlock is possible 1391 theoretically (no matter how unlikely the race scenario 1392 is), it will be proven so and will immediately be 1393 reported by the kernel (once the event is observed that 1394 makes the deadlock theoretically possible). 1395 1396 If a deadlock is impossible (i.e. the locking rules, as 1397 observed by the kernel, are mathematically correct), the 1398 kernel reports nothing. 1399 1400 NOTE: this feature can also be enabled for rwlocks, mutexes 1401 and rwsems - in which case all dependencies between these 1402 different locking variants are observed and mapped too, and 1403 the proof of observed correctness is also maintained for an 1404 arbitrary combination of these separate locking variants. 1405 1406 For more details, see Documentation/locking/lockdep-design.rst. 1407 1408config PROVE_RAW_LOCK_NESTING 1409 bool "Enable raw_spinlock - spinlock nesting checks" if !ARCH_SUPPORTS_RT 1410 depends on PROVE_LOCKING 1411 default y if ARCH_SUPPORTS_RT 1412 help 1413 Enable the raw_spinlock vs. spinlock nesting checks which ensure 1414 that the lock nesting rules for PREEMPT_RT enabled kernels are 1415 not violated. 1416 1417config LOCK_STAT 1418 bool "Lock usage statistics" 1419 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1420 select LOCKDEP 1421 select DEBUG_SPINLOCK 1422 select DEBUG_MUTEXES if !PREEMPT_RT 1423 select DEBUG_RT_MUTEXES if RT_MUTEXES 1424 select DEBUG_LOCK_ALLOC 1425 default n 1426 help 1427 This feature enables tracking lock contention points 1428 1429 For more details, see Documentation/locking/lockstat.rst 1430 1431 This also enables lock events required by "perf lock", 1432 subcommand of perf. 1433 If you want to use "perf lock", you also need to turn on 1434 CONFIG_EVENT_TRACING. 1435 1436 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1437 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1438 1439config DEBUG_RT_MUTEXES 1440 bool "RT Mutex debugging, deadlock detection" 1441 depends on DEBUG_KERNEL && RT_MUTEXES 1442 help 1443 This allows rt mutex semantics violations and rt mutex related 1444 deadlocks (lockups) to be detected and reported automatically. 1445 1446config DEBUG_SPINLOCK 1447 bool "Spinlock and rw-lock debugging: basic checks" 1448 depends on DEBUG_KERNEL 1449 select UNINLINE_SPIN_UNLOCK 1450 help 1451 Say Y here and build SMP to catch missing spinlock initialization 1452 and certain other kinds of spinlock errors commonly made. This is 1453 best used in conjunction with the NMI watchdog so that spinlock 1454 deadlocks are also debuggable. 1455 1456config DEBUG_MUTEXES 1457 bool "Mutex debugging: basic checks" 1458 depends on DEBUG_KERNEL && !PREEMPT_RT 1459 help 1460 This feature allows mutex semantics violations to be detected and 1461 reported. 1462 1463config DEBUG_WW_MUTEX_SLOWPATH 1464 bool "Wait/wound mutex debugging: Slowpath testing" 1465 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1466 select DEBUG_LOCK_ALLOC 1467 select DEBUG_SPINLOCK 1468 select DEBUG_MUTEXES if !PREEMPT_RT 1469 select DEBUG_RT_MUTEXES if PREEMPT_RT 1470 help 1471 This feature enables slowpath testing for w/w mutex users by 1472 injecting additional -EDEADLK wound/backoff cases. Together with 1473 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1474 will test all possible w/w mutex interface abuse with the 1475 exception of simply not acquiring all the required locks. 1476 Note that this feature can introduce significant overhead, so 1477 it really should not be enabled in a production or distro kernel, 1478 even a debug kernel. If you are a driver writer, enable it. If 1479 you are a distro, do not. 1480 1481config DEBUG_RWSEMS 1482 bool "RW Semaphore debugging: basic checks" 1483 depends on DEBUG_KERNEL && !PREEMPT_RT 1484 help 1485 This debugging feature allows mismatched rw semaphore locks 1486 and unlocks to be detected and reported. 1487 1488config DEBUG_LOCK_ALLOC 1489 bool "Lock debugging: detect incorrect freeing of live locks" 1490 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1491 select DEBUG_SPINLOCK 1492 select DEBUG_MUTEXES if !PREEMPT_RT 1493 select DEBUG_RT_MUTEXES if RT_MUTEXES 1494 select LOCKDEP 1495 help 1496 This feature will check whether any held lock (spinlock, rwlock, 1497 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1498 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1499 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1500 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1501 held during task exit. 1502 1503config LOCKDEP 1504 bool 1505 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1506 select STACKTRACE 1507 select KALLSYMS 1508 select KALLSYMS_ALL 1509 1510config LOCKDEP_SMALL 1511 bool 1512 1513config LOCKDEP_BITS 1514 int "Size for MAX_LOCKDEP_ENTRIES (as Nth power of 2)" 1515 depends on LOCKDEP && !LOCKDEP_SMALL 1516 range 10 24 1517 default 15 1518 help 1519 Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message. 1520 1521config LOCKDEP_CHAINS_BITS 1522 int "Size for MAX_LOCKDEP_CHAINS (as Nth power of 2)" 1523 depends on LOCKDEP && !LOCKDEP_SMALL 1524 range 10 21 1525 default 16 1526 help 1527 Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message. 1528 1529config LOCKDEP_STACK_TRACE_BITS 1530 int "Size for MAX_STACK_TRACE_ENTRIES (as Nth power of 2)" 1531 depends on LOCKDEP && !LOCKDEP_SMALL 1532 range 10 26 1533 default 19 1534 help 1535 Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message. 1536 1537config LOCKDEP_STACK_TRACE_HASH_BITS 1538 int "Size for STACK_TRACE_HASH_SIZE (as Nth power of 2)" 1539 depends on LOCKDEP && !LOCKDEP_SMALL 1540 range 10 26 1541 default 14 1542 help 1543 Try increasing this value if you need large STACK_TRACE_HASH_SIZE. 1544 1545config LOCKDEP_CIRCULAR_QUEUE_BITS 1546 int "Size for elements in circular_queue struct (as Nth power of 2)" 1547 depends on LOCKDEP 1548 range 10 26 1549 default 12 1550 help 1551 Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure. 1552 1553config DEBUG_LOCKDEP 1554 bool "Lock dependency engine debugging" 1555 depends on DEBUG_KERNEL && LOCKDEP 1556 select DEBUG_IRQFLAGS 1557 help 1558 If you say Y here, the lock dependency engine will do 1559 additional runtime checks to debug itself, at the price 1560 of more runtime overhead. 1561 1562config DEBUG_ATOMIC_SLEEP 1563 bool "Sleep inside atomic section checking" 1564 select PREEMPT_COUNT 1565 depends on DEBUG_KERNEL 1566 depends on !ARCH_NO_PREEMPT 1567 help 1568 If you say Y here, various routines which may sleep will become very 1569 noisy if they are called inside atomic sections: when a spinlock is 1570 held, inside an rcu read side critical section, inside preempt disabled 1571 sections, inside an interrupt, etc... 1572 1573config DEBUG_LOCKING_API_SELFTESTS 1574 bool "Locking API boot-time self-tests" 1575 depends on DEBUG_KERNEL 1576 help 1577 Say Y here if you want the kernel to run a short self-test during 1578 bootup. The self-test checks whether common types of locking bugs 1579 are detected by debugging mechanisms or not. (if you disable 1580 lock debugging then those bugs won't be detected of course.) 1581 The following locking APIs are covered: spinlocks, rwlocks, 1582 mutexes and rwsems. 1583 1584config LOCK_TORTURE_TEST 1585 tristate "torture tests for locking" 1586 depends on DEBUG_KERNEL 1587 select TORTURE_TEST 1588 help 1589 This option provides a kernel module that runs torture tests 1590 on kernel locking primitives. The kernel module may be built 1591 after the fact on the running kernel to be tested, if desired. 1592 1593 Say Y here if you want kernel locking-primitive torture tests 1594 to be built into the kernel. 1595 Say M if you want these torture tests to build as a module. 1596 Say N if you are unsure. 1597 1598config WW_MUTEX_SELFTEST 1599 tristate "Wait/wound mutex selftests" 1600 help 1601 This option provides a kernel module that runs tests on the 1602 on the struct ww_mutex locking API. 1603 1604 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1605 with this test harness. 1606 1607 Say M if you want these self tests to build as a module. 1608 Say N if you are unsure. 1609 1610config SCF_TORTURE_TEST 1611 tristate "torture tests for smp_call_function*()" 1612 depends on DEBUG_KERNEL 1613 select TORTURE_TEST 1614 help 1615 This option provides a kernel module that runs torture tests 1616 on the smp_call_function() family of primitives. The kernel 1617 module may be built after the fact on the running kernel to 1618 be tested, if desired. 1619 1620config CSD_LOCK_WAIT_DEBUG 1621 bool "Debugging for csd_lock_wait(), called from smp_call_function*()" 1622 depends on DEBUG_KERNEL 1623 depends on SMP 1624 depends on 64BIT 1625 default n 1626 help 1627 This option enables debug prints when CPUs are slow to respond 1628 to the smp_call_function*() IPI wrappers. These debug prints 1629 include the IPI handler function currently executing (if any) 1630 and relevant stack traces. 1631 1632config CSD_LOCK_WAIT_DEBUG_DEFAULT 1633 bool "Default csd_lock_wait() debugging on at boot time" 1634 depends on CSD_LOCK_WAIT_DEBUG 1635 depends on 64BIT 1636 default n 1637 help 1638 This option causes the csdlock_debug= kernel boot parameter to 1639 default to 1 (basic debugging) instead of 0 (no debugging). 1640 1641endmenu # lock debugging 1642 1643config TRACE_IRQFLAGS 1644 depends on TRACE_IRQFLAGS_SUPPORT 1645 bool 1646 help 1647 Enables hooks to interrupt enabling and disabling for 1648 either tracing or lock debugging. 1649 1650config TRACE_IRQFLAGS_NMI 1651 def_bool y 1652 depends on TRACE_IRQFLAGS 1653 depends on TRACE_IRQFLAGS_NMI_SUPPORT 1654 1655config NMI_CHECK_CPU 1656 bool "Debugging for CPUs failing to respond to backtrace requests" 1657 depends on DEBUG_KERNEL 1658 depends on X86 1659 default n 1660 help 1661 Enables debug prints when a CPU fails to respond to a given 1662 backtrace NMI. These prints provide some reasons why a CPU 1663 might legitimately be failing to respond, for example, if it 1664 is offline of if ignore_nmis is set. 1665 1666config DEBUG_IRQFLAGS 1667 bool "Debug IRQ flag manipulation" 1668 help 1669 Enables checks for potentially unsafe enabling or disabling of 1670 interrupts, such as calling raw_local_irq_restore() when interrupts 1671 are enabled. 1672 1673config STACKTRACE 1674 bool "Stack backtrace support" 1675 depends on STACKTRACE_SUPPORT 1676 help 1677 This option causes the kernel to create a /proc/pid/stack for 1678 every process, showing its current stack trace. 1679 It is also used by various kernel debugging features that require 1680 stack trace generation. 1681 1682config WARN_ALL_UNSEEDED_RANDOM 1683 bool "Warn for all uses of unseeded randomness" 1684 default n 1685 help 1686 Some parts of the kernel contain bugs relating to their use of 1687 cryptographically secure random numbers before it's actually possible 1688 to generate those numbers securely. This setting ensures that these 1689 flaws don't go unnoticed, by enabling a message, should this ever 1690 occur. This will allow people with obscure setups to know when things 1691 are going wrong, so that they might contact developers about fixing 1692 it. 1693 1694 Unfortunately, on some models of some architectures getting 1695 a fully seeded CRNG is extremely difficult, and so this can 1696 result in dmesg getting spammed for a surprisingly long 1697 time. This is really bad from a security perspective, and 1698 so architecture maintainers really need to do what they can 1699 to get the CRNG seeded sooner after the system is booted. 1700 However, since users cannot do anything actionable to 1701 address this, by default this option is disabled. 1702 1703 Say Y here if you want to receive warnings for all uses of 1704 unseeded randomness. This will be of use primarily for 1705 those developers interested in improving the security of 1706 Linux kernels running on their architecture (or 1707 subarchitecture). 1708 1709config DEBUG_KOBJECT 1710 bool "kobject debugging" 1711 depends on DEBUG_KERNEL 1712 help 1713 If you say Y here, some extra kobject debugging messages will be sent 1714 to the syslog. 1715 1716config DEBUG_KOBJECT_RELEASE 1717 bool "kobject release debugging" 1718 depends on DEBUG_OBJECTS_TIMERS 1719 help 1720 kobjects are reference counted objects. This means that their 1721 last reference count put is not predictable, and the kobject can 1722 live on past the point at which a driver decides to drop its 1723 initial reference to the kobject gained on allocation. An 1724 example of this would be a struct device which has just been 1725 unregistered. 1726 1727 However, some buggy drivers assume that after such an operation, 1728 the memory backing the kobject can be immediately freed. This 1729 goes completely against the principles of a refcounted object. 1730 1731 If you say Y here, the kernel will delay the release of kobjects 1732 on the last reference count to improve the visibility of this 1733 kind of kobject release bug. 1734 1735config HAVE_DEBUG_BUGVERBOSE 1736 bool 1737 1738menu "Debug kernel data structures" 1739 1740config DEBUG_LIST 1741 bool "Debug linked list manipulation" 1742 depends on DEBUG_KERNEL 1743 select LIST_HARDENED 1744 help 1745 Enable this to turn on extended checks in the linked-list walking 1746 routines. 1747 1748 This option trades better quality error reports for performance, and 1749 is more suitable for kernel debugging. If you care about performance, 1750 you should only enable CONFIG_LIST_HARDENED instead. 1751 1752 If unsure, say N. 1753 1754config DEBUG_PLIST 1755 bool "Debug priority linked list manipulation" 1756 depends on DEBUG_KERNEL 1757 help 1758 Enable this to turn on extended checks in the priority-ordered 1759 linked-list (plist) walking routines. This checks the entire 1760 list multiple times during each manipulation. 1761 1762 If unsure, say N. 1763 1764config DEBUG_SG 1765 bool "Debug SG table operations" 1766 depends on DEBUG_KERNEL 1767 help 1768 Enable this to turn on checks on scatter-gather tables. This can 1769 help find problems with drivers that do not properly initialize 1770 their sg tables. 1771 1772 If unsure, say N. 1773 1774config DEBUG_NOTIFIERS 1775 bool "Debug notifier call chains" 1776 depends on DEBUG_KERNEL 1777 help 1778 Enable this to turn on sanity checking for notifier call chains. 1779 This is most useful for kernel developers to make sure that 1780 modules properly unregister themselves from notifier chains. 1781 This is a relatively cheap check but if you care about maximum 1782 performance, say N. 1783 1784config DEBUG_CLOSURES 1785 bool "Debug closures (bcache async widgits)" 1786 depends on CLOSURES 1787 select DEBUG_FS 1788 help 1789 Keeps all active closures in a linked list and provides a debugfs 1790 interface to list them, which makes it possible to see asynchronous 1791 operations that get stuck. 1792 1793config DEBUG_MAPLE_TREE 1794 bool "Debug maple trees" 1795 depends on DEBUG_KERNEL 1796 help 1797 Enable maple tree debugging information and extra validations. 1798 1799 If unsure, say N. 1800 1801endmenu 1802 1803source "kernel/rcu/Kconfig.debug" 1804 1805config DEBUG_WQ_FORCE_RR_CPU 1806 bool "Force round-robin CPU selection for unbound work items" 1807 depends on DEBUG_KERNEL 1808 default n 1809 help 1810 Workqueue used to implicitly guarantee that work items queued 1811 without explicit CPU specified are put on the local CPU. This 1812 guarantee is no longer true and while local CPU is still 1813 preferred work items may be put on foreign CPUs. Kernel 1814 parameter "workqueue.debug_force_rr_cpu" is added to force 1815 round-robin CPU selection to flush out usages which depend on the 1816 now broken guarantee. This config option enables the debug 1817 feature by default. When enabled, memory and cache locality will 1818 be impacted. 1819 1820config CPU_HOTPLUG_STATE_CONTROL 1821 bool "Enable CPU hotplug state control" 1822 depends on DEBUG_KERNEL 1823 depends on HOTPLUG_CPU 1824 default n 1825 help 1826 Allows to write steps between "offline" and "online" to the CPUs 1827 sysfs target file so states can be stepped granular. This is a debug 1828 option for now as the hotplug machinery cannot be stopped and 1829 restarted at arbitrary points yet. 1830 1831 Say N if your are unsure. 1832 1833config LATENCYTOP 1834 bool "Latency measuring infrastructure" 1835 depends on DEBUG_KERNEL 1836 depends on STACKTRACE_SUPPORT 1837 depends on PROC_FS 1838 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 1839 select KALLSYMS 1840 select KALLSYMS_ALL 1841 select STACKTRACE 1842 select SCHEDSTATS 1843 help 1844 Enable this option if you want to use the LatencyTOP tool 1845 to find out which userspace is blocking on what kernel operations. 1846 1847config DEBUG_CGROUP_REF 1848 bool "Disable inlining of cgroup css reference count functions" 1849 depends on DEBUG_KERNEL 1850 depends on CGROUPS 1851 depends on KPROBES 1852 default n 1853 help 1854 Force cgroup css reference count functions to not be inlined so 1855 that they can be kprobed for debugging. 1856 1857source "kernel/trace/Kconfig" 1858 1859config PROVIDE_OHCI1394_DMA_INIT 1860 bool "Remote debugging over FireWire early on boot" 1861 depends on PCI && X86 1862 help 1863 If you want to debug problems which hang or crash the kernel early 1864 on boot and the crashing machine has a FireWire port, you can use 1865 this feature to remotely access the memory of the crashed machine 1866 over FireWire. This employs remote DMA as part of the OHCI1394 1867 specification which is now the standard for FireWire controllers. 1868 1869 With remote DMA, you can monitor the printk buffer remotely using 1870 firescope and access all memory below 4GB using fireproxy from gdb. 1871 Even controlling a kernel debugger is possible using remote DMA. 1872 1873 Usage: 1874 1875 If ohci1394_dma=early is used as boot parameter, it will initialize 1876 all OHCI1394 controllers which are found in the PCI config space. 1877 1878 As all changes to the FireWire bus such as enabling and disabling 1879 devices cause a bus reset and thereby disable remote DMA for all 1880 devices, be sure to have the cable plugged and FireWire enabled on 1881 the debugging host before booting the debug target for debugging. 1882 1883 This code (~1k) is freed after boot. By then, the firewire stack 1884 in charge of the OHCI-1394 controllers should be used instead. 1885 1886 See Documentation/core-api/debugging-via-ohci1394.rst for more information. 1887 1888source "samples/Kconfig" 1889 1890config ARCH_HAS_DEVMEM_IS_ALLOWED 1891 bool 1892 1893config STRICT_DEVMEM 1894 bool "Filter access to /dev/mem" 1895 depends on MMU && DEVMEM 1896 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED 1897 default y if PPC || X86 || ARM64 || S390 1898 help 1899 If this option is disabled, you allow userspace (root) access to all 1900 of memory, including kernel and userspace memory. Accidental 1901 access to this is obviously disastrous, but specific access can 1902 be used by people debugging the kernel. Note that with PAT support 1903 enabled, even in this case there are restrictions on /dev/mem 1904 use due to the cache aliasing requirements. 1905 1906 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 1907 file only allows userspace access to PCI space and the BIOS code and 1908 data regions. This is sufficient for dosemu and X and all common 1909 users of /dev/mem. 1910 1911 If in doubt, say Y. 1912 1913config IO_STRICT_DEVMEM 1914 bool "Filter I/O access to /dev/mem" 1915 depends on STRICT_DEVMEM 1916 help 1917 If this option is disabled, you allow userspace (root) access to all 1918 io-memory regardless of whether a driver is actively using that 1919 range. Accidental access to this is obviously disastrous, but 1920 specific access can be used by people debugging kernel drivers. 1921 1922 If this option is switched on, the /dev/mem file only allows 1923 userspace access to *idle* io-memory ranges (see /proc/iomem) This 1924 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 1925 if the driver using a given range cannot be disabled. 1926 1927 If in doubt, say Y. 1928 1929menu "$(SRCARCH) Debugging" 1930 1931source "arch/$(SRCARCH)/Kconfig.debug" 1932 1933endmenu 1934 1935menu "Kernel Testing and Coverage" 1936 1937source "lib/kunit/Kconfig" 1938 1939config NOTIFIER_ERROR_INJECTION 1940 tristate "Notifier error injection" 1941 depends on DEBUG_KERNEL 1942 select DEBUG_FS 1943 help 1944 This option provides the ability to inject artificial errors to 1945 specified notifier chain callbacks. It is useful to test the error 1946 handling of notifier call chain failures. 1947 1948 Say N if unsure. 1949 1950config PM_NOTIFIER_ERROR_INJECT 1951 tristate "PM notifier error injection module" 1952 depends on PM && NOTIFIER_ERROR_INJECTION 1953 default m if PM_DEBUG 1954 help 1955 This option provides the ability to inject artificial errors to 1956 PM notifier chain callbacks. It is controlled through debugfs 1957 interface /sys/kernel/debug/notifier-error-inject/pm 1958 1959 If the notifier call chain should be failed with some events 1960 notified, write the error code to "actions/<notifier event>/error". 1961 1962 Example: Inject PM suspend error (-12 = -ENOMEM) 1963 1964 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1965 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1966 # echo mem > /sys/power/state 1967 bash: echo: write error: Cannot allocate memory 1968 1969 To compile this code as a module, choose M here: the module will 1970 be called pm-notifier-error-inject. 1971 1972 If unsure, say N. 1973 1974config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1975 tristate "OF reconfig notifier error injection module" 1976 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1977 help 1978 This option provides the ability to inject artificial errors to 1979 OF reconfig notifier chain callbacks. It is controlled 1980 through debugfs interface under 1981 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1982 1983 If the notifier call chain should be failed with some events 1984 notified, write the error code to "actions/<notifier event>/error". 1985 1986 To compile this code as a module, choose M here: the module will 1987 be called of-reconfig-notifier-error-inject. 1988 1989 If unsure, say N. 1990 1991config NETDEV_NOTIFIER_ERROR_INJECT 1992 tristate "Netdev notifier error injection module" 1993 depends on NET && NOTIFIER_ERROR_INJECTION 1994 help 1995 This option provides the ability to inject artificial errors to 1996 netdevice notifier chain callbacks. It is controlled through debugfs 1997 interface /sys/kernel/debug/notifier-error-inject/netdev 1998 1999 If the notifier call chain should be failed with some events 2000 notified, write the error code to "actions/<notifier event>/error". 2001 2002 Example: Inject netdevice mtu change error (-22 = -EINVAL) 2003 2004 # cd /sys/kernel/debug/notifier-error-inject/netdev 2005 # echo -22 > actions/NETDEV_CHANGEMTU/error 2006 # ip link set eth0 mtu 1024 2007 RTNETLINK answers: Invalid argument 2008 2009 To compile this code as a module, choose M here: the module will 2010 be called netdev-notifier-error-inject. 2011 2012 If unsure, say N. 2013 2014config FUNCTION_ERROR_INJECTION 2015 bool "Fault-injections of functions" 2016 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 2017 help 2018 Add fault injections into various functions that are annotated with 2019 ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return 2020 value of these functions. This is useful to test error paths of code. 2021 2022 If unsure, say N 2023 2024config FAULT_INJECTION 2025 bool "Fault-injection framework" 2026 depends on DEBUG_KERNEL 2027 help 2028 Provide fault-injection framework. 2029 For more details, see Documentation/fault-injection/. 2030 2031config FAILSLAB 2032 bool "Fault-injection capability for kmalloc" 2033 depends on FAULT_INJECTION 2034 help 2035 Provide fault-injection capability for kmalloc. 2036 2037config FAIL_PAGE_ALLOC 2038 bool "Fault-injection capability for alloc_pages()" 2039 depends on FAULT_INJECTION 2040 help 2041 Provide fault-injection capability for alloc_pages(). 2042 2043config FAULT_INJECTION_USERCOPY 2044 bool "Fault injection capability for usercopy functions" 2045 depends on FAULT_INJECTION 2046 help 2047 Provides fault-injection capability to inject failures 2048 in usercopy functions (copy_from_user(), get_user(), ...). 2049 2050config FAIL_MAKE_REQUEST 2051 bool "Fault-injection capability for disk IO" 2052 depends on FAULT_INJECTION && BLOCK 2053 help 2054 Provide fault-injection capability for disk IO. 2055 2056config FAIL_IO_TIMEOUT 2057 bool "Fault-injection capability for faking disk interrupts" 2058 depends on FAULT_INJECTION && BLOCK 2059 help 2060 Provide fault-injection capability on end IO handling. This 2061 will make the block layer "forget" an interrupt as configured, 2062 thus exercising the error handling. 2063 2064 Only works with drivers that use the generic timeout handling, 2065 for others it won't do anything. 2066 2067config FAIL_FUTEX 2068 bool "Fault-injection capability for futexes" 2069 select DEBUG_FS 2070 depends on FAULT_INJECTION && FUTEX 2071 help 2072 Provide fault-injection capability for futexes. 2073 2074config FAULT_INJECTION_DEBUG_FS 2075 bool "Debugfs entries for fault-injection capabilities" 2076 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 2077 help 2078 Enable configuration of fault-injection capabilities via debugfs. 2079 2080config FAIL_FUNCTION 2081 bool "Fault-injection capability for functions" 2082 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 2083 help 2084 Provide function-based fault-injection capability. 2085 This will allow you to override a specific function with a return 2086 with given return value. As a result, function caller will see 2087 an error value and have to handle it. This is useful to test the 2088 error handling in various subsystems. 2089 2090config FAIL_MMC_REQUEST 2091 bool "Fault-injection capability for MMC IO" 2092 depends on FAULT_INJECTION_DEBUG_FS && MMC 2093 help 2094 Provide fault-injection capability for MMC IO. 2095 This will make the mmc core return data errors. This is 2096 useful to test the error handling in the mmc block device 2097 and to test how the mmc host driver handles retries from 2098 the block device. 2099 2100config FAIL_SUNRPC 2101 bool "Fault-injection capability for SunRPC" 2102 depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG 2103 help 2104 Provide fault-injection capability for SunRPC and 2105 its consumers. 2106 2107config FAIL_SKB_REALLOC 2108 bool "Fault-injection capability forcing skb to reallocate" 2109 depends on FAULT_INJECTION_DEBUG_FS 2110 help 2111 Provide fault-injection capability that forces the skb to be 2112 reallocated, catching possible invalid pointers to the skb. 2113 2114 For more information, check 2115 Documentation/dev-tools/fault-injection/fault-injection.rst 2116 2117config FAULT_INJECTION_CONFIGFS 2118 bool "Configfs interface for fault-injection capabilities" 2119 depends on FAULT_INJECTION 2120 select CONFIGFS_FS 2121 help 2122 This option allows configfs-based drivers to dynamically configure 2123 fault-injection via configfs. Each parameter for driver-specific 2124 fault-injection can be made visible as a configfs attribute in a 2125 configfs group. 2126 2127 2128config FAULT_INJECTION_STACKTRACE_FILTER 2129 bool "stacktrace filter for fault-injection capabilities" 2130 depends on FAULT_INJECTION 2131 depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT 2132 select STACKTRACE 2133 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 2134 help 2135 Provide stacktrace filter for fault-injection capabilities 2136 2137config ARCH_HAS_KCOV 2138 bool 2139 help 2140 An architecture should select this when it can successfully 2141 build and run with CONFIG_KCOV. This typically requires 2142 disabling instrumentation for some early boot code. 2143 2144config CC_HAS_SANCOV_TRACE_PC 2145 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 2146 2147 2148config KCOV 2149 bool "Code coverage for fuzzing" 2150 depends on ARCH_HAS_KCOV 2151 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 2152 depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \ 2153 GCC_VERSION >= 120000 || CC_IS_CLANG 2154 select DEBUG_FS 2155 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 2156 select OBJTOOL if HAVE_NOINSTR_HACK 2157 help 2158 KCOV exposes kernel code coverage information in a form suitable 2159 for coverage-guided fuzzing (randomized testing). 2160 2161 For more details, see Documentation/dev-tools/kcov.rst. 2162 2163config KCOV_ENABLE_COMPARISONS 2164 bool "Enable comparison operands collection by KCOV" 2165 depends on KCOV 2166 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 2167 help 2168 KCOV also exposes operands of every comparison in the instrumented 2169 code along with operand sizes and PCs of the comparison instructions. 2170 These operands can be used by fuzzing engines to improve the quality 2171 of fuzzing coverage. 2172 2173config KCOV_INSTRUMENT_ALL 2174 bool "Instrument all code by default" 2175 depends on KCOV 2176 default y 2177 help 2178 If you are doing generic system call fuzzing (like e.g. syzkaller), 2179 then you will want to instrument the whole kernel and you should 2180 say y here. If you are doing more targeted fuzzing (like e.g. 2181 filesystem fuzzing with AFL) then you will want to enable coverage 2182 for more specific subsets of files, and should say n here. 2183 2184config KCOV_IRQ_AREA_SIZE 2185 hex "Size of interrupt coverage collection area in words" 2186 depends on KCOV 2187 default 0x40000 2188 help 2189 KCOV uses preallocated per-cpu areas to collect coverage from 2190 soft interrupts. This specifies the size of those areas in the 2191 number of unsigned long words. 2192 2193config KCOV_SELFTEST 2194 bool "Perform short selftests on boot" 2195 depends on KCOV 2196 help 2197 Run short KCOV coverage collection selftests on boot. 2198 On test failure, causes the kernel to panic. Recommended to be 2199 enabled, ensuring critical functionality works as intended. 2200 2201menuconfig RUNTIME_TESTING_MENU 2202 bool "Runtime Testing" 2203 default y 2204 2205if RUNTIME_TESTING_MENU 2206 2207config TEST_DHRY 2208 tristate "Dhrystone benchmark test" 2209 help 2210 Enable this to include the Dhrystone 2.1 benchmark. This test 2211 calculates the number of Dhrystones per second, and the number of 2212 DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided 2213 by 1757 (the number of Dhrystones per second obtained on the VAX 2214 11/780, nominally a 1 MIPS machine). 2215 2216 To run the benchmark, it needs to be enabled explicitly, either from 2217 the kernel command line (when built-in), or from userspace (when 2218 built-in or modular). 2219 2220 Run once during kernel boot: 2221 2222 test_dhry.run 2223 2224 Set number of iterations from kernel command line: 2225 2226 test_dhry.iterations=<n> 2227 2228 Set number of iterations from userspace: 2229 2230 echo <n> > /sys/module/test_dhry/parameters/iterations 2231 2232 Trigger manual run from userspace: 2233 2234 echo y > /sys/module/test_dhry/parameters/run 2235 2236 If the number of iterations is <= 0, the test will devise a suitable 2237 number of iterations (test runs for at least 2s) automatically. 2238 This process takes ca. 4s. 2239 2240 If unsure, say N. 2241 2242config LKDTM 2243 tristate "Linux Kernel Dump Test Tool Module" 2244 depends on DEBUG_FS 2245 help 2246 This module enables testing of the different dumping mechanisms by 2247 inducing system failures at predefined crash points. 2248 If you don't need it: say N 2249 Choose M here to compile this code as a module. The module will be 2250 called lkdtm. 2251 2252 Documentation on how to use the module can be found in 2253 Documentation/fault-injection/provoke-crashes.rst 2254 2255config CPUMASK_KUNIT_TEST 2256 tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS 2257 depends on KUNIT 2258 default KUNIT_ALL_TESTS 2259 help 2260 Enable to turn on cpumask tests, running at boot or module load time. 2261 2262 For more information on KUnit and unit tests in general, please refer 2263 to the KUnit documentation in Documentation/dev-tools/kunit/. 2264 2265 If unsure, say N. 2266 2267config TEST_LIST_SORT 2268 tristate "Linked list sorting test" if !KUNIT_ALL_TESTS 2269 depends on KUNIT 2270 default KUNIT_ALL_TESTS 2271 help 2272 Enable this to turn on 'list_sort()' function test. This test is 2273 executed only once during system boot (so affects only boot time), 2274 or at module load time. 2275 2276 If unsure, say N. 2277 2278config TEST_MIN_HEAP 2279 tristate "Min heap test" 2280 depends on DEBUG_KERNEL || m 2281 help 2282 Enable this to turn on min heap function tests. This test is 2283 executed only once during system boot (so affects only boot time), 2284 or at module load time. 2285 2286 If unsure, say N. 2287 2288config TEST_SORT 2289 tristate "Array-based sort test" if !KUNIT_ALL_TESTS 2290 depends on KUNIT 2291 default KUNIT_ALL_TESTS 2292 help 2293 This option enables the self-test function of 'sort()' at boot, 2294 or at module load time. 2295 2296 If unsure, say N. 2297 2298config TEST_DIV64 2299 tristate "64bit/32bit division and modulo test" 2300 depends on DEBUG_KERNEL || m 2301 help 2302 Enable this to turn on 'do_div()' function test. This test is 2303 executed only once during system boot (so affects only boot time), 2304 or at module load time. 2305 2306 If unsure, say N. 2307 2308config TEST_MULDIV64 2309 tristate "mul_u64_u64_div_u64() test" 2310 depends on DEBUG_KERNEL || m 2311 help 2312 Enable this to turn on 'mul_u64_u64_div_u64()' function test. 2313 This test is executed only once during system boot (so affects 2314 only boot time), or at module load time. 2315 2316 If unsure, say N. 2317 2318config TEST_IOV_ITER 2319 tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS 2320 depends on KUNIT 2321 depends on MMU 2322 default KUNIT_ALL_TESTS 2323 help 2324 Enable this to turn on testing of the operation of the I/O iterator 2325 (iov_iter). This test is executed only once during system boot (so 2326 affects only boot time), or at module load time. 2327 2328 If unsure, say N. 2329 2330config KPROBES_SANITY_TEST 2331 tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS 2332 depends on DEBUG_KERNEL 2333 depends on KPROBES 2334 depends on KUNIT 2335 select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 2336 default KUNIT_ALL_TESTS 2337 help 2338 This option provides for testing basic kprobes functionality on 2339 boot. Samples of kprobe and kretprobe are inserted and 2340 verified for functionality. 2341 2342 Say N if you are unsure. 2343 2344config FPROBE_SANITY_TEST 2345 bool "Self test for fprobe" 2346 depends on DEBUG_KERNEL 2347 depends on FPROBE 2348 depends on KUNIT=y 2349 help 2350 This option will enable testing the fprobe when the system boot. 2351 A series of tests are made to verify that the fprobe is functioning 2352 properly. 2353 2354 Say N if you are unsure. 2355 2356config BACKTRACE_SELF_TEST 2357 tristate "Self test for the backtrace code" 2358 depends on DEBUG_KERNEL 2359 help 2360 This option provides a kernel module that can be used to test 2361 the kernel stack backtrace code. This option is not useful 2362 for distributions or general kernels, but only for kernel 2363 developers working on architecture code. 2364 2365 Note that if you want to also test saved backtraces, you will 2366 have to enable STACKTRACE as well. 2367 2368 Say N if you are unsure. 2369 2370config TEST_REF_TRACKER 2371 tristate "Self test for reference tracker" 2372 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT 2373 select REF_TRACKER 2374 help 2375 This option provides a kernel module performing tests 2376 using reference tracker infrastructure. 2377 2378 Say N if you are unsure. 2379 2380config RBTREE_TEST 2381 tristate "Red-Black tree test" 2382 depends on DEBUG_KERNEL 2383 help 2384 A benchmark measuring the performance of the rbtree library. 2385 Also includes rbtree invariant checks. 2386 2387config REED_SOLOMON_TEST 2388 tristate "Reed-Solomon library test" 2389 depends on DEBUG_KERNEL || m 2390 select REED_SOLOMON 2391 select REED_SOLOMON_ENC16 2392 select REED_SOLOMON_DEC16 2393 help 2394 This option enables the self-test function of rslib at boot, 2395 or at module load time. 2396 2397 If unsure, say N. 2398 2399config INTERVAL_TREE_TEST 2400 tristate "Interval tree test" 2401 depends on DEBUG_KERNEL 2402 select INTERVAL_TREE 2403 help 2404 A benchmark measuring the performance of the interval tree library 2405 2406config PERCPU_TEST 2407 tristate "Per cpu operations test" 2408 depends on m && DEBUG_KERNEL 2409 help 2410 Enable this option to build test module which validates per-cpu 2411 operations. 2412 2413 If unsure, say N. 2414 2415config ATOMIC64_SELFTEST 2416 tristate "Perform an atomic64_t self-test" 2417 help 2418 Enable this option to test the atomic64_t functions at boot or 2419 at module load time. 2420 2421 If unsure, say N. 2422 2423config ASYNC_RAID6_TEST 2424 tristate "Self test for hardware accelerated raid6 recovery" 2425 depends on ASYNC_RAID6_RECOV 2426 select ASYNC_MEMCPY 2427 help 2428 This is a one-shot self test that permutes through the 2429 recovery of all the possible two disk failure scenarios for a 2430 N-disk array. Recovery is performed with the asynchronous 2431 raid6 recovery routines, and will optionally use an offload 2432 engine if one is available. 2433 2434 If unsure, say N. 2435 2436config TEST_HEXDUMP 2437 tristate "Test functions located in the hexdump module at runtime" 2438 2439config STRING_KUNIT_TEST 2440 tristate "KUnit test string functions at runtime" if !KUNIT_ALL_TESTS 2441 depends on KUNIT 2442 default KUNIT_ALL_TESTS 2443 2444config STRING_HELPERS_KUNIT_TEST 2445 tristate "KUnit test string helpers at runtime" if !KUNIT_ALL_TESTS 2446 depends on KUNIT 2447 default KUNIT_ALL_TESTS 2448 2449config TEST_KSTRTOX 2450 tristate "Test kstrto*() family of functions at runtime" 2451 2452config TEST_PRINTF 2453 tristate "Test printf() family of functions at runtime" 2454 2455config TEST_SCANF 2456 tristate "Test scanf() family of functions at runtime" 2457 2458config TEST_BITMAP 2459 tristate "Test bitmap_*() family of functions at runtime" 2460 help 2461 Enable this option to test the bitmap functions at boot. 2462 2463 If unsure, say N. 2464 2465config TEST_UUID 2466 tristate "Test functions located in the uuid module at runtime" 2467 2468config TEST_XARRAY 2469 tristate "Test the XArray code at runtime" 2470 2471config TEST_MAPLE_TREE 2472 tristate "Test the Maple Tree code at runtime or module load" 2473 help 2474 Enable this option to test the maple tree code functions at boot, or 2475 when the module is loaded. Enable "Debug Maple Trees" will enable 2476 more verbose output on failures. 2477 2478 If unsure, say N. 2479 2480config TEST_RHASHTABLE 2481 tristate "Perform selftest on resizable hash table" 2482 help 2483 Enable this option to test the rhashtable functions at boot. 2484 2485 If unsure, say N. 2486 2487config TEST_IDA 2488 tristate "Perform selftest on IDA functions" 2489 2490config TEST_MISC_MINOR 2491 tristate "Basic misc minor Kunit test" if !KUNIT_ALL_TESTS 2492 depends on KUNIT 2493 default KUNIT_ALL_TESTS 2494 help 2495 Kunit test for the misc minor. 2496 It tests misc minor functions for dynamic and misc dynamic minor. 2497 This include misc_xxx functions 2498 2499 If unsure, say N. 2500 2501config TEST_PARMAN 2502 tristate "Perform selftest on priority array manager" 2503 depends on PARMAN 2504 help 2505 Enable this option to test priority array manager on boot 2506 (or module load). 2507 2508 If unsure, say N. 2509 2510config TEST_IRQ_TIMINGS 2511 bool "IRQ timings selftest" 2512 depends on IRQ_TIMINGS 2513 help 2514 Enable this option to test the irq timings code on boot. 2515 2516 If unsure, say N. 2517 2518config TEST_LKM 2519 tristate "Test module loading with 'hello world' module" 2520 depends on m 2521 help 2522 This builds the "test_module" module that emits "Hello, world" 2523 on printk when loaded. It is designed to be used for basic 2524 evaluation of the module loading subsystem (for example when 2525 validating module verification). It lacks any extra dependencies, 2526 and will not normally be loaded by the system unless explicitly 2527 requested by name. 2528 2529 If unsure, say N. 2530 2531config TEST_BITOPS 2532 tristate "Test module for compilation of bitops operations" 2533 help 2534 This builds the "test_bitops" module that is much like the 2535 TEST_LKM module except that it does a basic exercise of the 2536 set/clear_bit macros and get_count_order/long to make sure there are 2537 no compiler warnings from C=1 sparse checker or -Wextra 2538 compilations. It has no dependencies and doesn't run or load unless 2539 explicitly requested by name. for example: modprobe test_bitops. 2540 2541 If unsure, say N. 2542 2543config TEST_VMALLOC 2544 tristate "Test module for stress/performance analysis of vmalloc allocator" 2545 default n 2546 depends on MMU 2547 depends on m 2548 help 2549 This builds the "test_vmalloc" module that should be used for 2550 stress and performance analysis. So, any new change for vmalloc 2551 subsystem can be evaluated from performance and stability point 2552 of view. 2553 2554 If unsure, say N. 2555 2556config TEST_BPF 2557 tristate "Test BPF filter functionality" 2558 depends on m && NET 2559 help 2560 This builds the "test_bpf" module that runs various test vectors 2561 against the BPF interpreter or BPF JIT compiler depending on the 2562 current setting. This is in particular useful for BPF JIT compiler 2563 development, but also to run regression tests against changes in 2564 the interpreter code. It also enables test stubs for eBPF maps and 2565 verifier used by user space verifier testsuite. 2566 2567 If unsure, say N. 2568 2569config TEST_BLACKHOLE_DEV 2570 tristate "Test blackhole netdev functionality" 2571 depends on m && NET 2572 help 2573 This builds the "test_blackhole_dev" module that validates the 2574 data path through this blackhole netdev. 2575 2576 If unsure, say N. 2577 2578config FIND_BIT_BENCHMARK 2579 tristate "Test find_bit functions" 2580 help 2581 This builds the "test_find_bit" module that measure find_*_bit() 2582 functions performance. 2583 2584 If unsure, say N. 2585 2586config TEST_FIRMWARE 2587 tristate "Test firmware loading via userspace interface" 2588 depends on FW_LOADER 2589 help 2590 This builds the "test_firmware" module that creates a userspace 2591 interface for testing firmware loading. This can be used to 2592 control the triggering of firmware loading without needing an 2593 actual firmware-using device. The contents can be rechecked by 2594 userspace. 2595 2596 If unsure, say N. 2597 2598config TEST_SYSCTL 2599 tristate "sysctl test driver" 2600 depends on PROC_SYSCTL 2601 help 2602 This builds the "test_sysctl" module. This driver enables to test the 2603 proc sysctl interfaces available to drivers safely without affecting 2604 production knobs which might alter system functionality. 2605 2606 If unsure, say N. 2607 2608config BITFIELD_KUNIT 2609 tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS 2610 depends on KUNIT 2611 default KUNIT_ALL_TESTS 2612 help 2613 Enable this option to test the bitfield functions at boot. 2614 2615 KUnit tests run during boot and output the results to the debug log 2616 in TAP format (http://testanything.org/). Only useful for kernel devs 2617 running the KUnit test harness, and not intended for inclusion into a 2618 production build. 2619 2620 For more information on KUnit and unit tests in general please refer 2621 to the KUnit documentation in Documentation/dev-tools/kunit/. 2622 2623 If unsure, say N. 2624 2625config CHECKSUM_KUNIT 2626 tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS 2627 depends on KUNIT 2628 default KUNIT_ALL_TESTS 2629 help 2630 Enable this option to test the checksum functions at boot. 2631 2632 KUnit tests run during boot and output the results to the debug log 2633 in TAP format (http://testanything.org/). Only useful for kernel devs 2634 running the KUnit test harness, and not intended for inclusion into a 2635 production build. 2636 2637 For more information on KUnit and unit tests in general please refer 2638 to the KUnit documentation in Documentation/dev-tools/kunit/. 2639 2640 If unsure, say N. 2641 2642config UTIL_MACROS_KUNIT 2643 tristate "KUnit test util_macros.h functions at runtime" if !KUNIT_ALL_TESTS 2644 depends on KUNIT 2645 default KUNIT_ALL_TESTS 2646 help 2647 Enable this option to test the util_macros.h function at boot. 2648 2649 KUnit tests run during boot and output the results to the debug log 2650 in TAP format (http://testanything.org/). Only useful for kernel devs 2651 running the KUnit test harness, and not intended for inclusion into a 2652 production build. 2653 2654 For more information on KUnit and unit tests in general please refer 2655 to the KUnit documentation in Documentation/dev-tools/kunit/. 2656 2657 If unsure, say N. 2658 2659config HASH_KUNIT_TEST 2660 tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS 2661 depends on KUNIT 2662 default KUNIT_ALL_TESTS 2663 help 2664 Enable this option to test the kernel's string (<linux/stringhash.h>), and 2665 integer (<linux/hash.h>) hash functions on boot. 2666 2667 KUnit tests run during boot and output the results to the debug log 2668 in TAP format (https://testanything.org/). Only useful for kernel devs 2669 running the KUnit test harness, and not intended for inclusion into a 2670 production build. 2671 2672 For more information on KUnit and unit tests in general please refer 2673 to the KUnit documentation in Documentation/dev-tools/kunit/. 2674 2675 This is intended to help people writing architecture-specific 2676 optimized versions. If unsure, say N. 2677 2678config RESOURCE_KUNIT_TEST 2679 tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS 2680 depends on KUNIT 2681 default KUNIT_ALL_TESTS 2682 select GET_FREE_REGION 2683 help 2684 This builds the resource API unit test. 2685 Tests the logic of API provided by resource.c and ioport.h. 2686 For more information on KUnit and unit tests in general please refer 2687 to the KUnit documentation in Documentation/dev-tools/kunit/. 2688 2689 If unsure, say N. 2690 2691config SYSCTL_KUNIT_TEST 2692 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS 2693 depends on KUNIT 2694 default KUNIT_ALL_TESTS 2695 help 2696 This builds the proc sysctl unit test, which runs on boot. 2697 Tests the API contract and implementation correctness of sysctl. 2698 For more information on KUnit and unit tests in general please refer 2699 to the KUnit documentation in Documentation/dev-tools/kunit/. 2700 2701 If unsure, say N. 2702 2703config LIST_KUNIT_TEST 2704 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS 2705 depends on KUNIT 2706 default KUNIT_ALL_TESTS 2707 help 2708 This builds the linked list KUnit test suite. 2709 It tests that the API and basic functionality of the list_head type 2710 and associated macros. 2711 2712 KUnit tests run during boot and output the results to the debug log 2713 in TAP format (https://testanything.org/). Only useful for kernel devs 2714 running the KUnit test harness, and not intended for inclusion into a 2715 production build. 2716 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 HASHTABLE_KUNIT_TEST 2723 tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS 2724 depends on KUNIT 2725 default KUNIT_ALL_TESTS 2726 help 2727 This builds the hashtable KUnit test suite. 2728 It tests the basic functionality of the API defined in 2729 include/linux/hashtable.h. For more information on KUnit and 2730 unit tests in general please refer to the KUnit documentation 2731 in Documentation/dev-tools/kunit/. 2732 2733 If unsure, say N. 2734 2735config LINEAR_RANGES_TEST 2736 tristate "KUnit test for linear_ranges" 2737 depends on KUNIT 2738 select LINEAR_RANGES 2739 help 2740 This builds the linear_ranges unit test, which runs on boot. 2741 Tests the linear_ranges logic correctness. 2742 For more information on KUnit and unit tests in general please refer 2743 to the KUnit documentation in Documentation/dev-tools/kunit/. 2744 2745 If unsure, say N. 2746 2747config CMDLINE_KUNIT_TEST 2748 tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS 2749 depends on KUNIT 2750 default KUNIT_ALL_TESTS 2751 help 2752 This builds the cmdline API unit test. 2753 Tests the logic of API provided by cmdline.c. 2754 For more information on KUnit and unit tests in general please refer 2755 to the KUnit documentation in Documentation/dev-tools/kunit/. 2756 2757 If unsure, say N. 2758 2759config BITS_TEST 2760 tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS 2761 depends on KUNIT 2762 default KUNIT_ALL_TESTS 2763 help 2764 This builds the bits unit test. 2765 Tests the logic of macros defined in bits.h. 2766 For more information on KUnit and unit tests in general please refer 2767 to the KUnit documentation in Documentation/dev-tools/kunit/. 2768 2769 If unsure, say N. 2770 2771config SLUB_KUNIT_TEST 2772 tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS 2773 depends on SLUB_DEBUG && KUNIT 2774 default KUNIT_ALL_TESTS 2775 help 2776 This builds SLUB allocator unit test. 2777 Tests SLUB cache debugging functionality. 2778 For more information on KUnit and unit tests in general please refer 2779 to the KUnit documentation in Documentation/dev-tools/kunit/. 2780 2781 If unsure, say N. 2782 2783config RATIONAL_KUNIT_TEST 2784 tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS 2785 depends on KUNIT && RATIONAL 2786 default KUNIT_ALL_TESTS 2787 help 2788 This builds the rational math unit test. 2789 For more information on KUnit and unit tests in general please refer 2790 to the KUnit documentation in Documentation/dev-tools/kunit/. 2791 2792 If unsure, say N. 2793 2794config MEMCPY_KUNIT_TEST 2795 tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS 2796 depends on KUNIT 2797 default KUNIT_ALL_TESTS 2798 help 2799 Builds unit tests for memcpy(), memmove(), and memset() functions. 2800 For more information on KUnit and unit tests in general please refer 2801 to the KUnit documentation in Documentation/dev-tools/kunit/. 2802 2803 If unsure, say N. 2804 2805config IS_SIGNED_TYPE_KUNIT_TEST 2806 tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS 2807 depends on KUNIT 2808 default KUNIT_ALL_TESTS 2809 help 2810 Builds unit tests for the is_signed_type() macro. 2811 2812 For more information on KUnit and unit tests in general please refer 2813 to the KUnit documentation in Documentation/dev-tools/kunit/. 2814 2815 If unsure, say N. 2816 2817config OVERFLOW_KUNIT_TEST 2818 tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS 2819 depends on KUNIT 2820 default KUNIT_ALL_TESTS 2821 help 2822 Builds unit tests for the check_*_overflow(), size_*(), allocation, and 2823 related functions. 2824 2825 For more information on KUnit and unit tests in general please refer 2826 to the KUnit documentation in Documentation/dev-tools/kunit/. 2827 2828 If unsure, say N. 2829 2830config STACKINIT_KUNIT_TEST 2831 tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS 2832 depends on KUNIT 2833 default KUNIT_ALL_TESTS 2834 help 2835 Test if the kernel is zero-initializing stack variables and 2836 padding. Coverage is controlled by compiler flags, 2837 CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO, 2838 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2839 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2840 2841config FORTIFY_KUNIT_TEST 2842 tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS 2843 depends on KUNIT 2844 default KUNIT_ALL_TESTS 2845 help 2846 Builds unit tests for checking internals of FORTIFY_SOURCE as used 2847 by the str*() and mem*() family of functions. For testing runtime 2848 traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests. 2849 2850config HW_BREAKPOINT_KUNIT_TEST 2851 bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS 2852 depends on HAVE_HW_BREAKPOINT 2853 depends on KUNIT=y 2854 default KUNIT_ALL_TESTS 2855 help 2856 Tests for hw_breakpoint constraints accounting. 2857 2858 If unsure, say N. 2859 2860config CRC_KUNIT_TEST 2861 tristate "KUnit tests for CRC functions" if !KUNIT_ALL_TESTS 2862 depends on KUNIT 2863 default KUNIT_ALL_TESTS 2864 select CRC16 2865 select CRC_T10DIF 2866 select CRC32 2867 select CRC64 2868 help 2869 Unit tests for the CRC library functions. 2870 2871 This is intended to help people writing architecture-specific 2872 optimized versions. If unsure, say N. 2873 2874config CRC_BENCHMARK 2875 bool "Benchmark for the CRC functions" 2876 depends on CRC_KUNIT_TEST 2877 help 2878 Include benchmarks in the KUnit test suite for the CRC functions. 2879 2880config SIPHASH_KUNIT_TEST 2881 tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS 2882 depends on KUNIT 2883 default KUNIT_ALL_TESTS 2884 help 2885 Enable this option to test the kernel's siphash (<linux/siphash.h>) hash 2886 functions on boot (or module load). 2887 2888 This is intended to help people writing architecture-specific 2889 optimized versions. If unsure, say N. 2890 2891config USERCOPY_KUNIT_TEST 2892 tristate "KUnit Test for user/kernel boundary protections" 2893 depends on KUNIT 2894 default KUNIT_ALL_TESTS 2895 help 2896 This builds the "usercopy_kunit" module that runs sanity checks 2897 on the copy_to/from_user infrastructure, making sure basic 2898 user/kernel boundary testing is working. 2899 2900config TEST_UDELAY 2901 tristate "udelay test driver" 2902 help 2903 This builds the "udelay_test" module that helps to make sure 2904 that udelay() is working properly. 2905 2906 If unsure, say N. 2907 2908config TEST_STATIC_KEYS 2909 tristate "Test static keys" 2910 depends on m 2911 help 2912 Test the static key interfaces. 2913 2914 If unsure, say N. 2915 2916config TEST_DYNAMIC_DEBUG 2917 tristate "Test DYNAMIC_DEBUG" 2918 depends on DYNAMIC_DEBUG 2919 help 2920 This module registers a tracer callback to count enabled 2921 pr_debugs in a 'do_debugging' function, then alters their 2922 enablements, calls the function, and compares counts. 2923 2924 If unsure, say N. 2925 2926config TEST_KMOD 2927 tristate "kmod stress tester" 2928 depends on m 2929 depends on NETDEVICES && NET_CORE && INET # for TUN 2930 depends on BLOCK 2931 depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS 2932 select TEST_LKM 2933 select XFS_FS 2934 select TUN 2935 select BTRFS_FS 2936 help 2937 Test the kernel's module loading mechanism: kmod. kmod implements 2938 support to load modules using the Linux kernel's usermode helper. 2939 This test provides a series of tests against kmod. 2940 2941 Although technically you can either build test_kmod as a module or 2942 into the kernel we disallow building it into the kernel since 2943 it stress tests request_module() and this will very likely cause 2944 some issues by taking over precious threads available from other 2945 module load requests, ultimately this could be fatal. 2946 2947 To run tests run: 2948 2949 tools/testing/selftests/kmod/kmod.sh --help 2950 2951 If unsure, say N. 2952 2953config TEST_RUNTIME 2954 bool 2955 2956config TEST_RUNTIME_MODULE 2957 bool 2958 2959config TEST_KALLSYMS 2960 tristate "module kallsyms find_symbol() test" 2961 depends on m 2962 select TEST_RUNTIME 2963 select TEST_RUNTIME_MODULE 2964 select TEST_KALLSYMS_A 2965 select TEST_KALLSYMS_B 2966 select TEST_KALLSYMS_C 2967 select TEST_KALLSYMS_D 2968 help 2969 This allows us to stress test find_symbol() through the kallsyms 2970 used to place symbols on the kernel ELF kallsyms and modules kallsyms 2971 where we place kernel symbols such as exported symbols. 2972 2973 We have four test modules: 2974 2975 A: has KALLSYSMS_NUMSYMS exported symbols 2976 B: uses one of A's symbols 2977 C: adds KALLSYMS_SCALE_FACTOR * KALLSYSMS_NUMSYMS exported 2978 D: adds 2 * the symbols than C 2979 2980 We stress test find_symbol() through two means: 2981 2982 1) Upon load of B it will trigger simplify_symbols() to look for the 2983 one symbol it uses from the module A with tons of symbols. This is an 2984 indirect way for us to have B call resolve_symbol_wait() upon module 2985 load. This will eventually call find_symbol() which will eventually 2986 try to find the symbols used with find_exported_symbol_in_section(). 2987 find_exported_symbol_in_section() uses bsearch() so a binary search 2988 for each symbol. Binary search will at worst be O(log(n)) so the 2989 larger TEST_MODULE_KALLSYSMS the worse the search. 2990 2991 2) The selftests should load C first, before B. Upon B's load towards 2992 the end right before we call module B's init routine we get 2993 complete_formation() called on the module. That will first check 2994 for duplicate symbols with the call to verify_exported_symbols(). 2995 That is when we'll force iteration on module C's insane symbol list. 2996 Since it has 10 * KALLSYMS_NUMSYMS it means we can first test 2997 just loading B without C. The amount of time it takes to load C Vs 2998 B can give us an idea of the impact growth of the symbol space and 2999 give us projection. Module A only uses one symbol from B so to allow 3000 this scaling in module C to be proportional, if it used more symbols 3001 then the first test would be doing more and increasing just the 3002 search space would be slightly different. The last module, module D 3003 will just increase the search space by twice the number of symbols in 3004 C so to allow for full projects. 3005 3006 tools/testing/selftests/module/find_symbol.sh 3007 3008 The current defaults will incur a build delay of about 7 minutes 3009 on an x86_64 with only 8 cores. Enable this only if you want to 3010 stress test find_symbol() with thousands of symbols. At the same 3011 time this is also useful to test building modules with thousands of 3012 symbols, and if BTF is enabled this also stress tests adding BTF 3013 information for each module. Currently enabling many more symbols 3014 will segfault the build system. 3015 3016 If unsure, say N. 3017 3018if TEST_KALLSYMS 3019 3020config TEST_KALLSYMS_A 3021 tristate 3022 depends on m 3023 3024config TEST_KALLSYMS_B 3025 tristate 3026 depends on m 3027 3028config TEST_KALLSYMS_C 3029 tristate 3030 depends on m 3031 3032config TEST_KALLSYMS_D 3033 tristate 3034 depends on m 3035 3036choice 3037 prompt "Kallsym test range" 3038 default TEST_KALLSYMS_LARGE 3039 help 3040 Selecting something other than "Fast" will enable tests which slow 3041 down the build and may crash your build. 3042 3043config TEST_KALLSYMS_FAST 3044 bool "Fast builds" 3045 help 3046 You won't really be testing kallsysms, so this just helps fast builds 3047 when allmodconfig is used.. 3048 3049config TEST_KALLSYMS_LARGE 3050 bool "Enable testing kallsyms with large exports" 3051 help 3052 This will enable larger number of symbols. This will slow down 3053 your build considerably. 3054 3055config TEST_KALLSYMS_MAX 3056 bool "Known kallsysms limits" 3057 help 3058 This will enable exports to the point we know we'll start crashing 3059 builds. 3060 3061endchoice 3062 3063config TEST_KALLSYMS_NUMSYMS 3064 int "test kallsyms number of symbols" 3065 range 2 10000 3066 default 2 if TEST_KALLSYMS_FAST 3067 default 100 if TEST_KALLSYMS_LARGE 3068 default 10000 if TEST_KALLSYMS_MAX 3069 help 3070 The number of symbols to create on TEST_KALLSYMS_A, only one of which 3071 module TEST_KALLSYMS_B will use. This also will be used 3072 for how many symbols TEST_KALLSYMS_C will have, scaled up by 3073 TEST_KALLSYMS_SCALE_FACTOR. Note that setting this to 10,000 will 3074 trigger a segfault today, don't use anything close to it unless 3075 you are aware that this should not be used for automated build tests. 3076 3077config TEST_KALLSYMS_SCALE_FACTOR 3078 int "test kallsyms scale factor" 3079 default 8 3080 help 3081 How many more unusued symbols will TEST_KALLSYSMS_C have than 3082 TEST_KALLSYMS_A. If 8, then module C will have 8 * syms 3083 than module A. Then TEST_KALLSYMS_D will have double the amount 3084 of symbols than C so to allow projections. 3085 3086endif # TEST_KALLSYMS 3087 3088config TEST_DEBUG_VIRTUAL 3089 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 3090 depends on DEBUG_VIRTUAL 3091 help 3092 Test the kernel's ability to detect incorrect calls to 3093 virt_to_phys() done against the non-linear part of the 3094 kernel's virtual address map. 3095 3096 If unsure, say N. 3097 3098config TEST_MEMCAT_P 3099 tristate "Test memcat_p() helper function" 3100 help 3101 Test the memcat_p() helper for correctly merging two 3102 pointer arrays together. 3103 3104 If unsure, say N. 3105 3106config TEST_OBJAGG 3107 tristate "Perform selftest on object aggreration manager" 3108 default n 3109 depends on OBJAGG 3110 help 3111 Enable this option to test object aggregation manager on boot 3112 (or module load). 3113 3114config TEST_MEMINIT 3115 tristate "Test heap/page initialization" 3116 help 3117 Test if the kernel is zero-initializing heap and page allocations. 3118 This can be useful to test init_on_alloc and init_on_free features. 3119 3120 If unsure, say N. 3121 3122config TEST_HMM 3123 tristate "Test HMM (Heterogeneous Memory Management)" 3124 depends on TRANSPARENT_HUGEPAGE 3125 depends on DEVICE_PRIVATE 3126 select HMM_MIRROR 3127 select MMU_NOTIFIER 3128 help 3129 This is a pseudo device driver solely for testing HMM. 3130 Say M here if you want to build the HMM test module. 3131 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests. 3132 3133 If unsure, say N. 3134 3135config TEST_FREE_PAGES 3136 tristate "Test freeing pages" 3137 help 3138 Test that a memory leak does not occur due to a race between 3139 freeing a block of pages and a speculative page reference. 3140 Loading this module is safe if your kernel has the bug fixed. 3141 If the bug is not fixed, it will leak gigabytes of memory and 3142 probably OOM your system. 3143 3144config TEST_FPU 3145 tristate "Test floating point operations in kernel space" 3146 depends on ARCH_HAS_KERNEL_FPU_SUPPORT && !KCOV_INSTRUMENT_ALL 3147 help 3148 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu 3149 which will trigger a sequence of floating point operations. This is used 3150 for self-testing floating point control register setting in 3151 kernel_fpu_begin(). 3152 3153 If unsure, say N. 3154 3155config TEST_CLOCKSOURCE_WATCHDOG 3156 tristate "Test clocksource watchdog in kernel space" 3157 depends on CLOCKSOURCE_WATCHDOG 3158 help 3159 Enable this option to create a kernel module that will trigger 3160 a test of the clocksource watchdog. This module may be loaded 3161 via modprobe or insmod in which case it will run upon being 3162 loaded, or it may be built in, in which case it will run 3163 shortly after boot. 3164 3165 If unsure, say N. 3166 3167config TEST_OBJPOOL 3168 tristate "Test module for correctness and stress of objpool" 3169 default n 3170 depends on m && DEBUG_KERNEL 3171 help 3172 This builds the "test_objpool" module that should be used for 3173 correctness verification and concurrent testings of objects 3174 allocation and reclamation. 3175 3176 If unsure, say N. 3177 3178config INT_POW_TEST 3179 tristate "Integer exponentiation (int_pow) test" if !KUNIT_ALL_TESTS 3180 depends on KUNIT 3181 default KUNIT_ALL_TESTS 3182 help 3183 This option enables the KUnit test suite for the int_pow function, 3184 which performs integer exponentiation. The test suite is designed to 3185 verify that the implementation of int_pow correctly computes the power 3186 of a given base raised to a given exponent. 3187 3188 Enabling this option will include tests that check various scenarios 3189 and edge cases to ensure the accuracy and reliability of the exponentiation 3190 function. 3191 3192 If unsure, say N 3193 3194config INT_SQRT_KUNIT_TEST 3195 tristate "Integer square root test" if !KUNIT_ALL_TESTS 3196 depends on KUNIT 3197 default KUNIT_ALL_TESTS 3198 help 3199 This option enables the KUnit test suite for the int_sqrt() function, 3200 which performs square root calculation. The test suite checks 3201 various scenarios, including edge cases, to ensure correctness. 3202 3203 Enabling this option will include tests that check various scenarios 3204 and edge cases to ensure the accuracy and reliability of the square root 3205 function. 3206 3207 If unsure, say N 3208 3209endif # RUNTIME_TESTING_MENU 3210 3211config ARCH_USE_MEMTEST 3212 bool 3213 help 3214 An architecture should select this when it uses early_memtest() 3215 during boot process. 3216 3217config MEMTEST 3218 bool "Memtest" 3219 depends on ARCH_USE_MEMTEST 3220 help 3221 This option adds a kernel parameter 'memtest', which allows memtest 3222 to be set and executed. 3223 memtest=0, mean disabled; -- default 3224 memtest=1, mean do 1 test pattern; 3225 ... 3226 memtest=17, mean do 17 test patterns. 3227 If you are unsure how to answer this question, answer N. 3228 3229 3230 3231config HYPERV_TESTING 3232 bool "Microsoft Hyper-V driver testing" 3233 default n 3234 depends on HYPERV && DEBUG_FS 3235 help 3236 Select this option to enable Hyper-V vmbus testing. 3237 3238endmenu # "Kernel Testing and Coverage" 3239 3240menu "Rust hacking" 3241 3242config RUST_DEBUG_ASSERTIONS 3243 bool "Debug assertions" 3244 depends on RUST 3245 help 3246 Enables rustc's `-Cdebug-assertions` codegen option. 3247 3248 This flag lets you turn `cfg(debug_assertions)` conditional 3249 compilation on or off. This can be used to enable extra debugging 3250 code in development but not in production. For example, it controls 3251 the behavior of the standard library's `debug_assert!` macro. 3252 3253 Note that this will apply to all Rust code, including `core`. 3254 3255 If unsure, say N. 3256 3257config RUST_OVERFLOW_CHECKS 3258 bool "Overflow checks" 3259 default y 3260 depends on RUST 3261 help 3262 Enables rustc's `-Coverflow-checks` codegen option. 3263 3264 This flag allows you to control the behavior of runtime integer 3265 overflow. When overflow-checks are enabled, a Rust panic will occur 3266 on overflow. 3267 3268 Note that this will apply to all Rust code, including `core`. 3269 3270 If unsure, say Y. 3271 3272config RUST_BUILD_ASSERT_ALLOW 3273 bool "Allow unoptimized build-time assertions" 3274 depends on RUST 3275 help 3276 Controls how `build_error!` and `build_assert!` are handled during the build. 3277 3278 If calls to them exist in the binary, it may indicate a violated invariant 3279 or that the optimizer failed to verify the invariant during compilation. 3280 3281 This should not happen, thus by default the build is aborted. However, 3282 as an escape hatch, you can choose Y here to ignore them during build 3283 and let the check be carried at runtime (with `panic!` being called if 3284 the check fails). 3285 3286 If unsure, say N. 3287 3288config RUST_KERNEL_DOCTESTS 3289 bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS 3290 depends on RUST && KUNIT=y 3291 default KUNIT_ALL_TESTS 3292 help 3293 This builds the documentation tests of the `kernel` crate 3294 as KUnit tests. 3295 3296 For more information on KUnit and unit tests in general, 3297 please refer to the KUnit documentation in Documentation/dev-tools/kunit/. 3298 3299 If unsure, say N. 3300 3301endmenu # "Rust" 3302 3303endmenu # Kernel hacking 3304