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 help 477 This option will install uapi headers (headers exported to user-space) 478 into the usr/include directory for use during the kernel build. 479 This is unneeded for building the kernel itself, but needed for some 480 user-space program samples. It is also needed by some features such 481 as uapi header sanity checks. 482 483config DEBUG_SECTION_MISMATCH 484 bool "Enable full Section mismatch analysis" 485 depends on CC_IS_GCC 486 help 487 The section mismatch analysis checks if there are illegal 488 references from one section to another section. 489 During linktime or runtime, some sections are dropped; 490 any use of code/data previously in these sections would 491 most likely result in an oops. 492 In the code, functions and variables are annotated with 493 __init,, etc. (see the full list in include/linux/init.h), 494 which results in the code/data being placed in specific sections. 495 The section mismatch analysis is always performed after a full 496 kernel build, and enabling this option causes the following 497 additional step to occur: 498 - Add the option -fno-inline-functions-called-once to gcc commands. 499 When inlining a function annotated with __init in a non-init 500 function, we would lose the section information and thus 501 the analysis would not catch the illegal reference. 502 This option tells gcc to inline less (but it does result in 503 a larger kernel). 504 505config SECTION_MISMATCH_WARN_ONLY 506 bool "Make section mismatch errors non-fatal" 507 default y 508 help 509 If you say N here, the build process will fail if there are any 510 section mismatch, instead of just throwing warnings. 511 512 If unsure, say Y. 513 514config DEBUG_FORCE_FUNCTION_ALIGN_64B 515 bool "Force all function address 64B aligned" 516 depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC || RISCV || S390) 517 select FUNCTION_ALIGNMENT_64B 518 help 519 There are cases that a commit from one domain changes the function 520 address alignment of other domains, and cause magic performance 521 bump (regression or improvement). Enable this option will help to 522 verify if the bump is caused by function alignment changes, while 523 it will slightly increase the kernel size and affect icache usage. 524 525 It is mainly for debug and performance tuning use. 526 527# 528# Select this config option from the architecture Kconfig, if it 529# is preferred to always offer frame pointers as a config 530# option on the architecture (regardless of KERNEL_DEBUG): 531# 532config ARCH_WANT_FRAME_POINTERS 533 bool 534 535config FRAME_POINTER 536 bool "Compile the kernel with frame pointers" 537 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS 538 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 539 help 540 If you say Y here the resulting kernel image will be slightly 541 larger and slower, but it gives very useful debugging information 542 in case of kernel bugs. (precise oopses/stacktraces/warnings) 543 544config OBJTOOL 545 bool 546 547config STACK_VALIDATION 548 bool "Compile-time stack metadata validation" 549 depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER 550 select OBJTOOL 551 default n 552 help 553 Validate frame pointer rules at compile-time. This helps ensure that 554 runtime stack traces are more reliable. 555 556 For more information, see 557 tools/objtool/Documentation/objtool.txt. 558 559config NOINSTR_VALIDATION 560 bool 561 depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY 562 select OBJTOOL 563 default y 564 565config VMLINUX_MAP 566 bool "Generate vmlinux.map file when linking" 567 depends on EXPERT 568 help 569 Selecting this option will pass "-Map=vmlinux.map" to ld 570 when linking vmlinux. That file can be useful for verifying 571 and debugging magic section games, and for seeing which 572 pieces of code get eliminated with 573 CONFIG_LD_DEAD_CODE_DATA_ELIMINATION. 574 575config BUILTIN_MODULE_RANGES 576 bool "Generate address range information for builtin modules" 577 depends on !LTO 578 depends on VMLINUX_MAP 579 help 580 When modules are built into the kernel, there will be no module name 581 associated with its symbols in /proc/kallsyms. Tracers may want to 582 identify symbols by module name and symbol name regardless of whether 583 the module is configured as loadable or not. 584 585 This option generates modules.builtin.ranges in the build tree with 586 offset ranges (per ELF section) for the module(s) they belong to. 587 It also records an anchor symbol to determine the load address of the 588 section. 589 590config DEBUG_FORCE_WEAK_PER_CPU 591 bool "Force weak per-cpu definitions" 592 depends on DEBUG_KERNEL 593 help 594 s390 and alpha require percpu variables in modules to be 595 defined weak to work around addressing range issue which 596 puts the following two restrictions on percpu variable 597 definitions. 598 599 1. percpu symbols must be unique whether static or not 600 2. percpu variables can't be defined inside a function 601 602 To ensure that generic code follows the above rules, this 603 option forces all percpu variables to be defined as weak. 604 605endmenu # "Compiler options" 606 607menu "Generic Kernel Debugging Instruments" 608 609config MAGIC_SYSRQ 610 bool "Magic SysRq key" 611 depends on !UML 612 help 613 If you say Y here, you will have some control over the system even 614 if the system crashes for example during kernel debugging (e.g., you 615 will be able to flush the buffer cache to disk, reboot the system 616 immediately or dump some status information). This is accomplished 617 by pressing various keys while holding SysRq (Alt+PrintScreen). It 618 also works on a serial console (on PC hardware at least), if you 619 send a BREAK and then within 5 seconds a command keypress. The 620 keys are documented in <file:Documentation/admin-guide/sysrq.rst>. 621 Don't say Y unless you really know what this hack does. 622 623config MAGIC_SYSRQ_DEFAULT_ENABLE 624 hex "Enable magic SysRq key functions by default" 625 depends on MAGIC_SYSRQ 626 default 0x1 627 help 628 Specifies which SysRq key functions are enabled by default. 629 This may be set to 1 or 0 to enable or disable them all, or 630 to a bitmask as described in Documentation/admin-guide/sysrq.rst. 631 632config MAGIC_SYSRQ_SERIAL 633 bool "Enable magic SysRq key over serial" 634 depends on MAGIC_SYSRQ 635 default y 636 help 637 Many embedded boards have a disconnected TTL level serial which can 638 generate some garbage that can lead to spurious false sysrq detects. 639 This option allows you to decide whether you want to enable the 640 magic SysRq key. 641 642config MAGIC_SYSRQ_SERIAL_SEQUENCE 643 string "Char sequence that enables magic SysRq over serial" 644 depends on MAGIC_SYSRQ_SERIAL 645 default "" 646 help 647 Specifies a sequence of characters that can follow BREAK to enable 648 SysRq on a serial console. 649 650 If unsure, leave an empty string and the option will not be enabled. 651 652config DEBUG_FS 653 bool "Debug Filesystem" 654 help 655 debugfs is a virtual file system that kernel developers use to put 656 debugging files into. Enable this option to be able to read and 657 write to these files. 658 659 For detailed documentation on the debugfs API, see 660 Documentation/filesystems/. 661 662 If unsure, say N. 663 664choice 665 prompt "Debugfs default access" 666 depends on DEBUG_FS 667 default DEBUG_FS_ALLOW_ALL 668 help 669 This selects the default access restrictions for debugfs. 670 It can be overridden with kernel command line option 671 debugfs=[on,no-mount,off]. The restrictions apply for API access 672 and filesystem registration. 673 674config DEBUG_FS_ALLOW_ALL 675 bool "Access normal" 676 help 677 No restrictions apply. Both API and filesystem registration 678 is on. This is the normal default operation. 679 680config DEBUG_FS_DISALLOW_MOUNT 681 bool "Do not register debugfs as filesystem" 682 help 683 The API is open but filesystem is not loaded. Clients can still do 684 their work and read with debug tools that do not need 685 debugfs filesystem. 686 687config DEBUG_FS_ALLOW_NONE 688 bool "No access" 689 help 690 Access is off. Clients get -PERM when trying to create nodes in 691 debugfs tree and debugfs is not registered as a filesystem. 692 Client can then back-off or continue without debugfs access. 693 694endchoice 695 696source "lib/Kconfig.kgdb" 697source "lib/Kconfig.ubsan" 698source "lib/Kconfig.kcsan" 699 700endmenu 701 702menu "Networking Debugging" 703 704source "net/Kconfig.debug" 705 706endmenu # "Networking Debugging" 707 708menu "Memory Debugging" 709 710source "mm/Kconfig.debug" 711 712config DEBUG_OBJECTS 713 bool "Debug object operations" 714 depends on DEBUG_KERNEL 715 help 716 If you say Y here, additional code will be inserted into the 717 kernel to track the life time of various objects and validate 718 the operations on those objects. 719 720config DEBUG_OBJECTS_SELFTEST 721 bool "Debug objects selftest" 722 depends on DEBUG_OBJECTS 723 help 724 This enables the selftest of the object debug code. 725 726config DEBUG_OBJECTS_FREE 727 bool "Debug objects in freed memory" 728 depends on DEBUG_OBJECTS 729 help 730 This enables checks whether a k/v free operation frees an area 731 which contains an object which has not been deactivated 732 properly. This can make kmalloc/kfree-intensive workloads 733 much slower. 734 735config DEBUG_OBJECTS_TIMERS 736 bool "Debug timer objects" 737 depends on DEBUG_OBJECTS 738 help 739 If you say Y here, additional code will be inserted into the 740 timer routines to track the life time of timer objects and 741 validate the timer operations. 742 743config DEBUG_OBJECTS_WORK 744 bool "Debug work objects" 745 depends on DEBUG_OBJECTS 746 help 747 If you say Y here, additional code will be inserted into the 748 work queue routines to track the life time of work objects and 749 validate the work operations. 750 751config DEBUG_OBJECTS_RCU_HEAD 752 bool "Debug RCU callbacks objects" 753 depends on DEBUG_OBJECTS 754 help 755 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 756 757config DEBUG_OBJECTS_PERCPU_COUNTER 758 bool "Debug percpu counter objects" 759 depends on DEBUG_OBJECTS 760 help 761 If you say Y here, additional code will be inserted into the 762 percpu counter routines to track the life time of percpu counter 763 objects and validate the percpu counter operations. 764 765config DEBUG_OBJECTS_ENABLE_DEFAULT 766 int "debug_objects bootup default value (0-1)" 767 range 0 1 768 default "1" 769 depends on DEBUG_OBJECTS 770 help 771 Debug objects boot parameter default value 772 773config SHRINKER_DEBUG 774 bool "Enable shrinker debugging support" 775 depends on DEBUG_FS 776 help 777 Say Y to enable the shrinker debugfs interface which provides 778 visibility into the kernel memory shrinkers subsystem. 779 Disable it to avoid an extra memory footprint. 780 781config DEBUG_STACK_USAGE 782 bool "Stack utilization instrumentation" 783 depends on DEBUG_KERNEL 784 help 785 Enables the display of the minimum amount of free stack which each 786 task has ever had available in the sysrq-T and sysrq-P debug output. 787 Also emits a message to dmesg when a process exits if that process 788 used more stack space than previously exiting processes. 789 790 This option will slow down process creation somewhat. 791 792config SCHED_STACK_END_CHECK 793 bool "Detect stack corruption on calls to schedule()" 794 depends on DEBUG_KERNEL 795 default n 796 help 797 This option checks for a stack overrun on calls to schedule(). 798 If the stack end location is found to be over written always panic as 799 the content of the corrupted region can no longer be trusted. 800 This is to ensure no erroneous behaviour occurs which could result in 801 data corruption or a sporadic crash at a later stage once the region 802 is examined. The runtime overhead introduced is minimal. 803 804config ARCH_HAS_DEBUG_VM_PGTABLE 805 bool 806 help 807 An architecture should select this when it can successfully 808 build and run DEBUG_VM_PGTABLE. 809 810config DEBUG_VM_IRQSOFF 811 def_bool DEBUG_VM && !PREEMPT_RT 812 813config DEBUG_VM 814 bool "Debug VM" 815 depends on DEBUG_KERNEL 816 help 817 Enable this to turn on extended checks in the virtual-memory system 818 that may impact performance. 819 820 If unsure, say N. 821 822config DEBUG_VM_SHOOT_LAZIES 823 bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation" 824 depends on DEBUG_VM 825 depends on MMU_LAZY_TLB_SHOOTDOWN 826 help 827 Enable additional IPIs that ensure lazy tlb mm references are removed 828 before the mm is freed. 829 830 If unsure, say N. 831 832config DEBUG_VM_MAPLE_TREE 833 bool "Debug VM maple trees" 834 depends on DEBUG_VM 835 select DEBUG_MAPLE_TREE 836 help 837 Enable VM maple tree debugging information and extra validations. 838 839 If unsure, say N. 840 841config DEBUG_VM_RB 842 bool "Debug VM red-black trees" 843 depends on DEBUG_VM 844 help 845 Enable VM red-black tree debugging information and extra validations. 846 847 If unsure, say N. 848 849config DEBUG_VM_PGFLAGS 850 bool "Debug page-flags operations" 851 depends on DEBUG_VM 852 help 853 Enables extra validation on page flags operations. 854 855 If unsure, say N. 856 857config DEBUG_VM_PGTABLE 858 bool "Debug arch page table for semantics compliance" 859 depends on MMU 860 depends on ARCH_HAS_DEBUG_VM_PGTABLE 861 default y if DEBUG_VM 862 help 863 This option provides a debug method which can be used to test 864 architecture page table helper functions on various platforms in 865 verifying if they comply with expected generic MM semantics. This 866 will help architecture code in making sure that any changes or 867 new additions of these helpers still conform to expected 868 semantics of the generic MM. Platforms will have to opt in for 869 this through ARCH_HAS_DEBUG_VM_PGTABLE. 870 871 If unsure, say N. 872 873config ARCH_HAS_DEBUG_VIRTUAL 874 bool 875 876config DEBUG_VIRTUAL 877 bool "Debug VM translations" 878 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL 879 help 880 Enable some costly sanity checks in virtual to page code. This can 881 catch mistakes with virt_to_page() and friends. 882 883 If unsure, say N. 884 885config DEBUG_NOMMU_REGIONS 886 bool "Debug the global anon/private NOMMU mapping region tree" 887 depends on DEBUG_KERNEL && !MMU 888 help 889 This option causes the global tree of anonymous and private mapping 890 regions to be regularly checked for invalid topology. 891 892config DEBUG_MEMORY_INIT 893 bool "Debug memory initialisation" if EXPERT 894 default !EXPERT 895 help 896 Enable this for additional checks during memory initialisation. 897 The sanity checks verify aspects of the VM such as the memory model 898 and other information provided by the architecture. Verbose 899 information will be printed at KERN_DEBUG loglevel depending 900 on the mminit_loglevel= command-line option. 901 902 If unsure, say Y 903 904config MEMORY_NOTIFIER_ERROR_INJECT 905 tristate "Memory hotplug notifier error injection module" 906 depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION 907 help 908 This option provides the ability to inject artificial errors to 909 memory hotplug notifier chain callbacks. It is controlled through 910 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 911 912 If the notifier call chain should be failed with some events 913 notified, write the error code to "actions/<notifier event>/error". 914 915 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 916 917 # cd /sys/kernel/debug/notifier-error-inject/memory 918 # echo -12 > actions/MEM_GOING_OFFLINE/error 919 # echo offline > /sys/devices/system/memory/memoryXXX/state 920 bash: echo: write error: Cannot allocate memory 921 922 To compile this code as a module, choose M here: the module will 923 be called memory-notifier-error-inject. 924 925 If unsure, say N. 926 927config DEBUG_PER_CPU_MAPS 928 bool "Debug access to per_cpu maps" 929 depends on DEBUG_KERNEL 930 depends on SMP 931 help 932 Say Y to verify that the per_cpu map being accessed has 933 been set up. This adds a fair amount of code to kernel memory 934 and decreases performance. 935 936 Say N if unsure. 937 938config DEBUG_KMAP_LOCAL 939 bool "Debug kmap_local temporary mappings" 940 depends on DEBUG_KERNEL && KMAP_LOCAL 941 help 942 This option enables additional error checking for the kmap_local 943 infrastructure. Disable for production use. 944 945config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 946 bool 947 948config DEBUG_KMAP_LOCAL_FORCE_MAP 949 bool "Enforce kmap_local temporary mappings" 950 depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 951 select KMAP_LOCAL 952 select DEBUG_KMAP_LOCAL 953 help 954 This option enforces temporary mappings through the kmap_local 955 mechanism for non-highmem pages and on non-highmem systems. 956 Disable this for production systems! 957 958config DEBUG_HIGHMEM 959 bool "Highmem debugging" 960 depends on DEBUG_KERNEL && HIGHMEM 961 select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 962 select DEBUG_KMAP_LOCAL 963 help 964 This option enables additional error checking for high memory 965 systems. Disable for production systems. 966 967config HAVE_DEBUG_STACKOVERFLOW 968 bool 969 970config DEBUG_STACKOVERFLOW 971 bool "Check for stack overflows" 972 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 973 help 974 Say Y here if you want to check for overflows of kernel, IRQ 975 and exception stacks (if your architecture uses them). This 976 option will show detailed messages if free stack space drops 977 below a certain limit. 978 979 These kinds of bugs usually occur when call-chains in the 980 kernel get too deep, especially when interrupts are 981 involved. 982 983 Use this in cases where you see apparently random memory 984 corruption, especially if it appears in 'struct thread_info' 985 986 If in doubt, say "N". 987 988config CODE_TAGGING 989 bool 990 select KALLSYMS 991 992config MEM_ALLOC_PROFILING 993 bool "Enable memory allocation profiling" 994 default n 995 depends on MMU 996 depends on PROC_FS 997 depends on !DEBUG_FORCE_WEAK_PER_CPU 998 select CODE_TAGGING 999 select PAGE_EXTENSION 1000 select SLAB_OBJ_EXT 1001 help 1002 Track allocation source code and record total allocation size 1003 initiated at that code location. The mechanism can be used to track 1004 memory leaks with a low performance and memory impact. 1005 1006config MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT 1007 bool "Enable memory allocation profiling by default" 1008 default y 1009 depends on MEM_ALLOC_PROFILING 1010 1011config MEM_ALLOC_PROFILING_DEBUG 1012 bool "Memory allocation profiler debugging" 1013 default n 1014 depends on MEM_ALLOC_PROFILING 1015 select MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT 1016 help 1017 Adds warnings with helpful error messages for memory allocation 1018 profiling. 1019 1020source "lib/Kconfig.kasan" 1021source "lib/Kconfig.kfence" 1022source "lib/Kconfig.kmsan" 1023 1024endmenu # "Memory Debugging" 1025 1026config DEBUG_SHIRQ 1027 bool "Debug shared IRQ handlers" 1028 depends on DEBUG_KERNEL 1029 help 1030 Enable this to generate a spurious interrupt just before a shared 1031 interrupt handler is deregistered (generating one when registering 1032 is currently disabled). Drivers need to handle this correctly. Some 1033 don't and need to be caught. 1034 1035menu "Debug Oops, Lockups and Hangs" 1036 1037config PANIC_ON_OOPS 1038 bool "Panic on Oops" 1039 help 1040 Say Y here to enable the kernel to panic when it oopses. This 1041 has the same effect as setting oops=panic on the kernel command 1042 line. 1043 1044 This feature is useful to ensure that the kernel does not do 1045 anything erroneous after an oops which could result in data 1046 corruption or other issues. 1047 1048 Say N if unsure. 1049 1050config PANIC_ON_OOPS_VALUE 1051 int 1052 range 0 1 1053 default 0 if !PANIC_ON_OOPS 1054 default 1 if PANIC_ON_OOPS 1055 1056config PANIC_TIMEOUT 1057 int "panic timeout" 1058 default 0 1059 help 1060 Set the timeout value (in seconds) until a reboot occurs when 1061 the kernel panics. If n = 0, then we wait forever. A timeout 1062 value n > 0 will wait n seconds before rebooting, while a timeout 1063 value n < 0 will reboot immediately. This setting can be overridden 1064 with the kernel command line option panic=, and from userspace via 1065 /proc/sys/kernel/panic. 1066 1067config LOCKUP_DETECTOR 1068 bool 1069 1070config SOFTLOCKUP_DETECTOR 1071 bool "Detect Soft Lockups" 1072 depends on DEBUG_KERNEL && !S390 1073 select LOCKUP_DETECTOR 1074 help 1075 Say Y here to enable the kernel to act as a watchdog to detect 1076 soft lockups. 1077 1078 Softlockups are bugs that cause the kernel to loop in kernel 1079 mode for more than 20 seconds, without giving other tasks a 1080 chance to run. The current stack trace is displayed upon 1081 detection and the system will stay locked up. 1082 1083config SOFTLOCKUP_DETECTOR_INTR_STORM 1084 bool "Detect Interrupt Storm in Soft Lockups" 1085 depends on SOFTLOCKUP_DETECTOR && IRQ_TIME_ACCOUNTING 1086 select GENERIC_IRQ_STAT_SNAPSHOT 1087 default y if NR_CPUS <= 128 1088 help 1089 Say Y here to enable the kernel to detect interrupt storm 1090 during "soft lockups". 1091 1092 "soft lockups" can be caused by a variety of reasons. If one is 1093 caused by an interrupt storm, then the storming interrupts will not 1094 be on the callstack. To detect this case, it is necessary to report 1095 the CPU stats and the interrupt counts during the "soft lockups". 1096 1097config BOOTPARAM_SOFTLOCKUP_PANIC 1098 bool "Panic (Reboot) On Soft Lockups" 1099 depends on SOFTLOCKUP_DETECTOR 1100 help 1101 Say Y here to enable the kernel to panic on "soft lockups", 1102 which are bugs that cause the kernel to loop in kernel 1103 mode for more than 20 seconds (configurable using the watchdog_thresh 1104 sysctl), without giving other tasks a chance to run. 1105 1106 The panic can be used in combination with panic_timeout, 1107 to cause the system to reboot automatically after a 1108 lockup has been detected. This feature is useful for 1109 high-availability systems that have uptime guarantees and 1110 where a lockup must be resolved ASAP. 1111 1112 Say N if unsure. 1113 1114config HAVE_HARDLOCKUP_DETECTOR_BUDDY 1115 bool 1116 depends on SMP 1117 default y 1118 1119# 1120# Global switch whether to build a hardlockup detector at all. It is available 1121# only when the architecture supports at least one implementation. There are 1122# two exceptions. The hardlockup detector is never enabled on: 1123# 1124# s390: it reported many false positives there 1125# 1126# sparc64: has a custom implementation which is not using the common 1127# hardlockup command line options and sysctl interface. 1128# 1129config HARDLOCKUP_DETECTOR 1130 bool "Detect Hard Lockups" 1131 depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64 1132 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH 1133 imply HARDLOCKUP_DETECTOR_PERF 1134 imply HARDLOCKUP_DETECTOR_BUDDY 1135 imply HARDLOCKUP_DETECTOR_ARCH 1136 select LOCKUP_DETECTOR 1137 1138 help 1139 Say Y here to enable the kernel to act as a watchdog to detect 1140 hard lockups. 1141 1142 Hardlockups are bugs that cause the CPU to loop in kernel mode 1143 for more than 10 seconds, without letting other interrupts have a 1144 chance to run. The current stack trace is displayed upon detection 1145 and the system will stay locked up. 1146 1147# 1148# Note that arch-specific variants are always preferred. 1149# 1150config HARDLOCKUP_DETECTOR_PREFER_BUDDY 1151 bool "Prefer the buddy CPU hardlockup detector" 1152 depends on HARDLOCKUP_DETECTOR 1153 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY 1154 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1155 help 1156 Say Y here to prefer the buddy hardlockup detector over the perf one. 1157 1158 With the buddy detector, each CPU uses its softlockup hrtimer 1159 to check that the next CPU is processing hrtimer interrupts by 1160 verifying that a counter is increasing. 1161 1162 This hardlockup detector is useful on systems that don't have 1163 an arch-specific hardlockup detector or if resources needed 1164 for the hardlockup detector are better used for other things. 1165 1166config HARDLOCKUP_DETECTOR_PERF 1167 bool 1168 depends on HARDLOCKUP_DETECTOR 1169 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY 1170 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1171 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1172 1173config HARDLOCKUP_DETECTOR_BUDDY 1174 bool 1175 depends on HARDLOCKUP_DETECTOR 1176 depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY 1177 depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY 1178 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1179 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1180 1181config HARDLOCKUP_DETECTOR_ARCH 1182 bool 1183 depends on HARDLOCKUP_DETECTOR 1184 depends on HAVE_HARDLOCKUP_DETECTOR_ARCH 1185 help 1186 The arch-specific implementation of the hardlockup detector will 1187 be used. 1188 1189# 1190# Both the "perf" and "buddy" hardlockup detectors count hrtimer 1191# interrupts. This config enables functions managing this common code. 1192# 1193config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1194 bool 1195 select SOFTLOCKUP_DETECTOR 1196 1197# 1198# Enables a timestamp based low pass filter to compensate for perf based 1199# hard lockup detection which runs too fast due to turbo modes. 1200# 1201config HARDLOCKUP_CHECK_TIMESTAMP 1202 bool 1203 1204config BOOTPARAM_HARDLOCKUP_PANIC 1205 bool "Panic (Reboot) On Hard Lockups" 1206 depends on HARDLOCKUP_DETECTOR 1207 help 1208 Say Y here to enable the kernel to panic on "hard lockups", 1209 which are bugs that cause the kernel to loop in kernel 1210 mode with interrupts disabled for more than 10 seconds (configurable 1211 using the watchdog_thresh sysctl). 1212 1213 Say N if unsure. 1214 1215config DETECT_HUNG_TASK 1216 bool "Detect Hung Tasks" 1217 depends on DEBUG_KERNEL 1218 default SOFTLOCKUP_DETECTOR 1219 help 1220 Say Y here to enable the kernel to detect "hung tasks", 1221 which are bugs that cause the task to be stuck in 1222 uninterruptible "D" state indefinitely. 1223 1224 When a hung task is detected, the kernel will print the 1225 current stack trace (which you should report), but the 1226 task will stay in uninterruptible state. If lockdep is 1227 enabled then all held locks will also be reported. This 1228 feature has negligible overhead. 1229 1230config DEFAULT_HUNG_TASK_TIMEOUT 1231 int "Default timeout for hung task detection (in seconds)" 1232 depends on DETECT_HUNG_TASK 1233 default 120 1234 help 1235 This option controls the default timeout (in seconds) used 1236 to determine when a task has become non-responsive and should 1237 be considered hung. 1238 1239 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 1240 sysctl or by writing a value to 1241 /proc/sys/kernel/hung_task_timeout_secs. 1242 1243 A timeout of 0 disables the check. The default is two minutes. 1244 Keeping the default should be fine in most cases. 1245 1246config BOOTPARAM_HUNG_TASK_PANIC 1247 bool "Panic (Reboot) On Hung Tasks" 1248 depends on DETECT_HUNG_TASK 1249 help 1250 Say Y here to enable the kernel to panic on "hung tasks", 1251 which are bugs that cause the kernel to leave a task stuck 1252 in uninterruptible "D" state. 1253 1254 The panic can be used in combination with panic_timeout, 1255 to cause the system to reboot automatically after a 1256 hung task has been detected. This feature is useful for 1257 high-availability systems that have uptime guarantees and 1258 where a hung tasks must be resolved ASAP. 1259 1260 Say N if unsure. 1261 1262config WQ_WATCHDOG 1263 bool "Detect Workqueue Stalls" 1264 depends on DEBUG_KERNEL 1265 help 1266 Say Y here to enable stall detection on workqueues. If a 1267 worker pool doesn't make forward progress on a pending work 1268 item for over a given amount of time, 30s by default, a 1269 warning message is printed along with dump of workqueue 1270 state. This can be configured through kernel parameter 1271 "workqueue.watchdog_thresh" and its sysfs counterpart. 1272 1273config WQ_CPU_INTENSIVE_REPORT 1274 bool "Report per-cpu work items which hog CPU for too long" 1275 depends on DEBUG_KERNEL 1276 help 1277 Say Y here to enable reporting of concurrency-managed per-cpu work 1278 items that hog CPUs for longer than 1279 workqueue.cpu_intensive_thresh_us. Workqueue automatically 1280 detects and excludes them from concurrency management to prevent 1281 them from stalling other per-cpu work items. Occassional 1282 triggering may not necessarily indicate a problem. Repeated 1283 triggering likely indicates that the work item should be switched 1284 to use an unbound workqueue. 1285 1286config TEST_LOCKUP 1287 tristate "Test module to generate lockups" 1288 depends on m 1289 help 1290 This builds the "test_lockup" module that helps to make sure 1291 that watchdogs and lockup detectors are working properly. 1292 1293 Depending on module parameters it could emulate soft or hard 1294 lockup, "hung task", or locking arbitrary lock for a long time. 1295 Also it could generate series of lockups with cooling-down periods. 1296 1297 If unsure, say N. 1298 1299endmenu # "Debug lockups and hangs" 1300 1301menu "Scheduler Debugging" 1302 1303config SCHED_DEBUG 1304 bool "Collect scheduler debugging info" 1305 depends on DEBUG_KERNEL && DEBUG_FS 1306 default y 1307 help 1308 If you say Y here, the /sys/kernel/debug/sched file will be provided 1309 that can help debug the scheduler. The runtime overhead of this 1310 option is minimal. 1311 1312config SCHED_INFO 1313 bool 1314 default n 1315 1316config SCHEDSTATS 1317 bool "Collect scheduler statistics" 1318 depends on PROC_FS 1319 select SCHED_INFO 1320 help 1321 If you say Y here, additional code will be inserted into the 1322 scheduler and related routines to collect statistics about 1323 scheduler behavior and provide them in /proc/schedstat. These 1324 stats may be useful for both tuning and debugging the scheduler 1325 If you aren't debugging the scheduler or trying to tune a specific 1326 application, you can say N to avoid the very slight overhead 1327 this adds. 1328 1329endmenu 1330 1331config DEBUG_PREEMPT 1332 bool "Debug preemptible kernel" 1333 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1334 help 1335 If you say Y here then the kernel will use a debug variant of the 1336 commonly used smp_processor_id() function and will print warnings 1337 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1338 will detect preemption count underflows. 1339 1340 This option has potential to introduce high runtime overhead, 1341 depending on workload as it triggers debugging routines for each 1342 this_cpu operation. It should only be used for debugging purposes. 1343 1344menu "Lock Debugging (spinlocks, mutexes, etc...)" 1345 1346config LOCK_DEBUGGING_SUPPORT 1347 bool 1348 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1349 default y 1350 1351config PROVE_LOCKING 1352 bool "Lock debugging: prove locking correctness" 1353 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1354 select LOCKDEP 1355 select DEBUG_SPINLOCK 1356 select DEBUG_MUTEXES if !PREEMPT_RT 1357 select DEBUG_RT_MUTEXES if RT_MUTEXES 1358 select DEBUG_RWSEMS if !PREEMPT_RT 1359 select DEBUG_WW_MUTEX_SLOWPATH 1360 select DEBUG_LOCK_ALLOC 1361 select PREEMPT_COUNT if !ARCH_NO_PREEMPT 1362 select TRACE_IRQFLAGS 1363 default n 1364 help 1365 This feature enables the kernel to prove that all locking 1366 that occurs in the kernel runtime is mathematically 1367 correct: that under no circumstance could an arbitrary (and 1368 not yet triggered) combination of observed locking 1369 sequences (on an arbitrary number of CPUs, running an 1370 arbitrary number of tasks and interrupt contexts) cause a 1371 deadlock. 1372 1373 In short, this feature enables the kernel to report locking 1374 related deadlocks before they actually occur. 1375 1376 The proof does not depend on how hard and complex a 1377 deadlock scenario would be to trigger: how many 1378 participant CPUs, tasks and irq-contexts would be needed 1379 for it to trigger. The proof also does not depend on 1380 timing: if a race and a resulting deadlock is possible 1381 theoretically (no matter how unlikely the race scenario 1382 is), it will be proven so and will immediately be 1383 reported by the kernel (once the event is observed that 1384 makes the deadlock theoretically possible). 1385 1386 If a deadlock is impossible (i.e. the locking rules, as 1387 observed by the kernel, are mathematically correct), the 1388 kernel reports nothing. 1389 1390 NOTE: this feature can also be enabled for rwlocks, mutexes 1391 and rwsems - in which case all dependencies between these 1392 different locking variants are observed and mapped too, and 1393 the proof of observed correctness is also maintained for an 1394 arbitrary combination of these separate locking variants. 1395 1396 For more details, see Documentation/locking/lockdep-design.rst. 1397 1398config PROVE_RAW_LOCK_NESTING 1399 bool "Enable raw_spinlock - spinlock nesting checks" if !ARCH_SUPPORTS_RT 1400 depends on PROVE_LOCKING 1401 default y if ARCH_SUPPORTS_RT 1402 help 1403 Enable the raw_spinlock vs. spinlock nesting checks which ensure 1404 that the lock nesting rules for PREEMPT_RT enabled kernels are 1405 not violated. 1406 1407config LOCK_STAT 1408 bool "Lock usage statistics" 1409 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1410 select LOCKDEP 1411 select DEBUG_SPINLOCK 1412 select DEBUG_MUTEXES if !PREEMPT_RT 1413 select DEBUG_RT_MUTEXES if RT_MUTEXES 1414 select DEBUG_LOCK_ALLOC 1415 default n 1416 help 1417 This feature enables tracking lock contention points 1418 1419 For more details, see Documentation/locking/lockstat.rst 1420 1421 This also enables lock events required by "perf lock", 1422 subcommand of perf. 1423 If you want to use "perf lock", you also need to turn on 1424 CONFIG_EVENT_TRACING. 1425 1426 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1427 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1428 1429config DEBUG_RT_MUTEXES 1430 bool "RT Mutex debugging, deadlock detection" 1431 depends on DEBUG_KERNEL && RT_MUTEXES 1432 help 1433 This allows rt mutex semantics violations and rt mutex related 1434 deadlocks (lockups) to be detected and reported automatically. 1435 1436config DEBUG_SPINLOCK 1437 bool "Spinlock and rw-lock debugging: basic checks" 1438 depends on DEBUG_KERNEL 1439 select UNINLINE_SPIN_UNLOCK 1440 help 1441 Say Y here and build SMP to catch missing spinlock initialization 1442 and certain other kinds of spinlock errors commonly made. This is 1443 best used in conjunction with the NMI watchdog so that spinlock 1444 deadlocks are also debuggable. 1445 1446config DEBUG_MUTEXES 1447 bool "Mutex debugging: basic checks" 1448 depends on DEBUG_KERNEL && !PREEMPT_RT 1449 help 1450 This feature allows mutex semantics violations to be detected and 1451 reported. 1452 1453config DEBUG_WW_MUTEX_SLOWPATH 1454 bool "Wait/wound mutex debugging: Slowpath testing" 1455 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1456 select DEBUG_LOCK_ALLOC 1457 select DEBUG_SPINLOCK 1458 select DEBUG_MUTEXES if !PREEMPT_RT 1459 select DEBUG_RT_MUTEXES if PREEMPT_RT 1460 help 1461 This feature enables slowpath testing for w/w mutex users by 1462 injecting additional -EDEADLK wound/backoff cases. Together with 1463 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1464 will test all possible w/w mutex interface abuse with the 1465 exception of simply not acquiring all the required locks. 1466 Note that this feature can introduce significant overhead, so 1467 it really should not be enabled in a production or distro kernel, 1468 even a debug kernel. If you are a driver writer, enable it. If 1469 you are a distro, do not. 1470 1471config DEBUG_RWSEMS 1472 bool "RW Semaphore debugging: basic checks" 1473 depends on DEBUG_KERNEL && !PREEMPT_RT 1474 help 1475 This debugging feature allows mismatched rw semaphore locks 1476 and unlocks to be detected and reported. 1477 1478config DEBUG_LOCK_ALLOC 1479 bool "Lock debugging: detect incorrect freeing of live locks" 1480 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1481 select DEBUG_SPINLOCK 1482 select DEBUG_MUTEXES if !PREEMPT_RT 1483 select DEBUG_RT_MUTEXES if RT_MUTEXES 1484 select LOCKDEP 1485 help 1486 This feature will check whether any held lock (spinlock, rwlock, 1487 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1488 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1489 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1490 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1491 held during task exit. 1492 1493config LOCKDEP 1494 bool 1495 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1496 select STACKTRACE 1497 select KALLSYMS 1498 select KALLSYMS_ALL 1499 1500config LOCKDEP_SMALL 1501 bool 1502 1503config LOCKDEP_BITS 1504 int "Size for MAX_LOCKDEP_ENTRIES (as Nth power of 2)" 1505 depends on LOCKDEP && !LOCKDEP_SMALL 1506 range 10 24 1507 default 15 1508 help 1509 Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message. 1510 1511config LOCKDEP_CHAINS_BITS 1512 int "Size for MAX_LOCKDEP_CHAINS (as Nth power of 2)" 1513 depends on LOCKDEP && !LOCKDEP_SMALL 1514 range 10 21 1515 default 16 1516 help 1517 Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message. 1518 1519config LOCKDEP_STACK_TRACE_BITS 1520 int "Size for MAX_STACK_TRACE_ENTRIES (as Nth power of 2)" 1521 depends on LOCKDEP && !LOCKDEP_SMALL 1522 range 10 26 1523 default 19 1524 help 1525 Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message. 1526 1527config LOCKDEP_STACK_TRACE_HASH_BITS 1528 int "Size for STACK_TRACE_HASH_SIZE (as Nth power of 2)" 1529 depends on LOCKDEP && !LOCKDEP_SMALL 1530 range 10 26 1531 default 14 1532 help 1533 Try increasing this value if you need large STACK_TRACE_HASH_SIZE. 1534 1535config LOCKDEP_CIRCULAR_QUEUE_BITS 1536 int "Size for elements in circular_queue struct (as Nth power of 2)" 1537 depends on LOCKDEP 1538 range 10 26 1539 default 12 1540 help 1541 Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure. 1542 1543config DEBUG_LOCKDEP 1544 bool "Lock dependency engine debugging" 1545 depends on DEBUG_KERNEL && LOCKDEP 1546 select DEBUG_IRQFLAGS 1547 help 1548 If you say Y here, the lock dependency engine will do 1549 additional runtime checks to debug itself, at the price 1550 of more runtime overhead. 1551 1552config DEBUG_ATOMIC_SLEEP 1553 bool "Sleep inside atomic section checking" 1554 select PREEMPT_COUNT 1555 depends on DEBUG_KERNEL 1556 depends on !ARCH_NO_PREEMPT 1557 help 1558 If you say Y here, various routines which may sleep will become very 1559 noisy if they are called inside atomic sections: when a spinlock is 1560 held, inside an rcu read side critical section, inside preempt disabled 1561 sections, inside an interrupt, etc... 1562 1563config DEBUG_LOCKING_API_SELFTESTS 1564 bool "Locking API boot-time self-tests" 1565 depends on DEBUG_KERNEL 1566 help 1567 Say Y here if you want the kernel to run a short self-test during 1568 bootup. The self-test checks whether common types of locking bugs 1569 are detected by debugging mechanisms or not. (if you disable 1570 lock debugging then those bugs won't be detected of course.) 1571 The following locking APIs are covered: spinlocks, rwlocks, 1572 mutexes and rwsems. 1573 1574config LOCK_TORTURE_TEST 1575 tristate "torture tests for locking" 1576 depends on DEBUG_KERNEL 1577 select TORTURE_TEST 1578 help 1579 This option provides a kernel module that runs torture tests 1580 on kernel locking primitives. The kernel module may be built 1581 after the fact on the running kernel to be tested, if desired. 1582 1583 Say Y here if you want kernel locking-primitive torture tests 1584 to be built into the kernel. 1585 Say M if you want these torture tests to build as a module. 1586 Say N if you are unsure. 1587 1588config WW_MUTEX_SELFTEST 1589 tristate "Wait/wound mutex selftests" 1590 help 1591 This option provides a kernel module that runs tests on the 1592 on the struct ww_mutex locking API. 1593 1594 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1595 with this test harness. 1596 1597 Say M if you want these self tests to build as a module. 1598 Say N if you are unsure. 1599 1600config SCF_TORTURE_TEST 1601 tristate "torture tests for smp_call_function*()" 1602 depends on DEBUG_KERNEL 1603 select TORTURE_TEST 1604 help 1605 This option provides a kernel module that runs torture tests 1606 on the smp_call_function() family of primitives. The kernel 1607 module may be built after the fact on the running kernel to 1608 be tested, if desired. 1609 1610config CSD_LOCK_WAIT_DEBUG 1611 bool "Debugging for csd_lock_wait(), called from smp_call_function*()" 1612 depends on DEBUG_KERNEL 1613 depends on SMP 1614 depends on 64BIT 1615 default n 1616 help 1617 This option enables debug prints when CPUs are slow to respond 1618 to the smp_call_function*() IPI wrappers. These debug prints 1619 include the IPI handler function currently executing (if any) 1620 and relevant stack traces. 1621 1622config CSD_LOCK_WAIT_DEBUG_DEFAULT 1623 bool "Default csd_lock_wait() debugging on at boot time" 1624 depends on CSD_LOCK_WAIT_DEBUG 1625 depends on 64BIT 1626 default n 1627 help 1628 This option causes the csdlock_debug= kernel boot parameter to 1629 default to 1 (basic debugging) instead of 0 (no debugging). 1630 1631endmenu # lock debugging 1632 1633config TRACE_IRQFLAGS 1634 depends on TRACE_IRQFLAGS_SUPPORT 1635 bool 1636 help 1637 Enables hooks to interrupt enabling and disabling for 1638 either tracing or lock debugging. 1639 1640config TRACE_IRQFLAGS_NMI 1641 def_bool y 1642 depends on TRACE_IRQFLAGS 1643 depends on TRACE_IRQFLAGS_NMI_SUPPORT 1644 1645config NMI_CHECK_CPU 1646 bool "Debugging for CPUs failing to respond to backtrace requests" 1647 depends on DEBUG_KERNEL 1648 depends on X86 1649 default n 1650 help 1651 Enables debug prints when a CPU fails to respond to a given 1652 backtrace NMI. These prints provide some reasons why a CPU 1653 might legitimately be failing to respond, for example, if it 1654 is offline of if ignore_nmis is set. 1655 1656config DEBUG_IRQFLAGS 1657 bool "Debug IRQ flag manipulation" 1658 help 1659 Enables checks for potentially unsafe enabling or disabling of 1660 interrupts, such as calling raw_local_irq_restore() when interrupts 1661 are enabled. 1662 1663config STACKTRACE 1664 bool "Stack backtrace support" 1665 depends on STACKTRACE_SUPPORT 1666 help 1667 This option causes the kernel to create a /proc/pid/stack for 1668 every process, showing its current stack trace. 1669 It is also used by various kernel debugging features that require 1670 stack trace generation. 1671 1672config WARN_ALL_UNSEEDED_RANDOM 1673 bool "Warn for all uses of unseeded randomness" 1674 default n 1675 help 1676 Some parts of the kernel contain bugs relating to their use of 1677 cryptographically secure random numbers before it's actually possible 1678 to generate those numbers securely. This setting ensures that these 1679 flaws don't go unnoticed, by enabling a message, should this ever 1680 occur. This will allow people with obscure setups to know when things 1681 are going wrong, so that they might contact developers about fixing 1682 it. 1683 1684 Unfortunately, on some models of some architectures getting 1685 a fully seeded CRNG is extremely difficult, and so this can 1686 result in dmesg getting spammed for a surprisingly long 1687 time. This is really bad from a security perspective, and 1688 so architecture maintainers really need to do what they can 1689 to get the CRNG seeded sooner after the system is booted. 1690 However, since users cannot do anything actionable to 1691 address this, by default this option is disabled. 1692 1693 Say Y here if you want to receive warnings for all uses of 1694 unseeded randomness. This will be of use primarily for 1695 those developers interested in improving the security of 1696 Linux kernels running on their architecture (or 1697 subarchitecture). 1698 1699config DEBUG_KOBJECT 1700 bool "kobject debugging" 1701 depends on DEBUG_KERNEL 1702 help 1703 If you say Y here, some extra kobject debugging messages will be sent 1704 to the syslog. 1705 1706config DEBUG_KOBJECT_RELEASE 1707 bool "kobject release debugging" 1708 depends on DEBUG_OBJECTS_TIMERS 1709 help 1710 kobjects are reference counted objects. This means that their 1711 last reference count put is not predictable, and the kobject can 1712 live on past the point at which a driver decides to drop its 1713 initial reference to the kobject gained on allocation. An 1714 example of this would be a struct device which has just been 1715 unregistered. 1716 1717 However, some buggy drivers assume that after such an operation, 1718 the memory backing the kobject can be immediately freed. This 1719 goes completely against the principles of a refcounted object. 1720 1721 If you say Y here, the kernel will delay the release of kobjects 1722 on the last reference count to improve the visibility of this 1723 kind of kobject release bug. 1724 1725config HAVE_DEBUG_BUGVERBOSE 1726 bool 1727 1728menu "Debug kernel data structures" 1729 1730config DEBUG_LIST 1731 bool "Debug linked list manipulation" 1732 depends on DEBUG_KERNEL 1733 select LIST_HARDENED 1734 help 1735 Enable this to turn on extended checks in the linked-list walking 1736 routines. 1737 1738 This option trades better quality error reports for performance, and 1739 is more suitable for kernel debugging. If you care about performance, 1740 you should only enable CONFIG_LIST_HARDENED instead. 1741 1742 If unsure, say N. 1743 1744config DEBUG_PLIST 1745 bool "Debug priority linked list manipulation" 1746 depends on DEBUG_KERNEL 1747 help 1748 Enable this to turn on extended checks in the priority-ordered 1749 linked-list (plist) walking routines. This checks the entire 1750 list multiple times during each manipulation. 1751 1752 If unsure, say N. 1753 1754config DEBUG_SG 1755 bool "Debug SG table operations" 1756 depends on DEBUG_KERNEL 1757 help 1758 Enable this to turn on checks on scatter-gather tables. This can 1759 help find problems with drivers that do not properly initialize 1760 their sg tables. 1761 1762 If unsure, say N. 1763 1764config DEBUG_NOTIFIERS 1765 bool "Debug notifier call chains" 1766 depends on DEBUG_KERNEL 1767 help 1768 Enable this to turn on sanity checking for notifier call chains. 1769 This is most useful for kernel developers to make sure that 1770 modules properly unregister themselves from notifier chains. 1771 This is a relatively cheap check but if you care about maximum 1772 performance, say N. 1773 1774config DEBUG_CLOSURES 1775 bool "Debug closures (bcache async widgits)" 1776 depends on CLOSURES 1777 select DEBUG_FS 1778 help 1779 Keeps all active closures in a linked list and provides a debugfs 1780 interface to list them, which makes it possible to see asynchronous 1781 operations that get stuck. 1782 1783config DEBUG_MAPLE_TREE 1784 bool "Debug maple trees" 1785 depends on DEBUG_KERNEL 1786 help 1787 Enable maple tree debugging information and extra validations. 1788 1789 If unsure, say N. 1790 1791endmenu 1792 1793source "kernel/rcu/Kconfig.debug" 1794 1795config DEBUG_WQ_FORCE_RR_CPU 1796 bool "Force round-robin CPU selection for unbound work items" 1797 depends on DEBUG_KERNEL 1798 default n 1799 help 1800 Workqueue used to implicitly guarantee that work items queued 1801 without explicit CPU specified are put on the local CPU. This 1802 guarantee is no longer true and while local CPU is still 1803 preferred work items may be put on foreign CPUs. Kernel 1804 parameter "workqueue.debug_force_rr_cpu" is added to force 1805 round-robin CPU selection to flush out usages which depend on the 1806 now broken guarantee. This config option enables the debug 1807 feature by default. When enabled, memory and cache locality will 1808 be impacted. 1809 1810config CPU_HOTPLUG_STATE_CONTROL 1811 bool "Enable CPU hotplug state control" 1812 depends on DEBUG_KERNEL 1813 depends on HOTPLUG_CPU 1814 default n 1815 help 1816 Allows to write steps between "offline" and "online" to the CPUs 1817 sysfs target file so states can be stepped granular. This is a debug 1818 option for now as the hotplug machinery cannot be stopped and 1819 restarted at arbitrary points yet. 1820 1821 Say N if your are unsure. 1822 1823config LATENCYTOP 1824 bool "Latency measuring infrastructure" 1825 depends on DEBUG_KERNEL 1826 depends on STACKTRACE_SUPPORT 1827 depends on PROC_FS 1828 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 1829 select KALLSYMS 1830 select KALLSYMS_ALL 1831 select STACKTRACE 1832 select SCHEDSTATS 1833 help 1834 Enable this option if you want to use the LatencyTOP tool 1835 to find out which userspace is blocking on what kernel operations. 1836 1837config DEBUG_CGROUP_REF 1838 bool "Disable inlining of cgroup css reference count functions" 1839 depends on DEBUG_KERNEL 1840 depends on CGROUPS 1841 depends on KPROBES 1842 default n 1843 help 1844 Force cgroup css reference count functions to not be inlined so 1845 that they can be kprobed for debugging. 1846 1847source "kernel/trace/Kconfig" 1848 1849config PROVIDE_OHCI1394_DMA_INIT 1850 bool "Remote debugging over FireWire early on boot" 1851 depends on PCI && X86 1852 help 1853 If you want to debug problems which hang or crash the kernel early 1854 on boot and the crashing machine has a FireWire port, you can use 1855 this feature to remotely access the memory of the crashed machine 1856 over FireWire. This employs remote DMA as part of the OHCI1394 1857 specification which is now the standard for FireWire controllers. 1858 1859 With remote DMA, you can monitor the printk buffer remotely using 1860 firescope and access all memory below 4GB using fireproxy from gdb. 1861 Even controlling a kernel debugger is possible using remote DMA. 1862 1863 Usage: 1864 1865 If ohci1394_dma=early is used as boot parameter, it will initialize 1866 all OHCI1394 controllers which are found in the PCI config space. 1867 1868 As all changes to the FireWire bus such as enabling and disabling 1869 devices cause a bus reset and thereby disable remote DMA for all 1870 devices, be sure to have the cable plugged and FireWire enabled on 1871 the debugging host before booting the debug target for debugging. 1872 1873 This code (~1k) is freed after boot. By then, the firewire stack 1874 in charge of the OHCI-1394 controllers should be used instead. 1875 1876 See Documentation/core-api/debugging-via-ohci1394.rst for more information. 1877 1878source "samples/Kconfig" 1879 1880config ARCH_HAS_DEVMEM_IS_ALLOWED 1881 bool 1882 1883config STRICT_DEVMEM 1884 bool "Filter access to /dev/mem" 1885 depends on MMU && DEVMEM 1886 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED 1887 default y if PPC || X86 || ARM64 || S390 1888 help 1889 If this option is disabled, you allow userspace (root) access to all 1890 of memory, including kernel and userspace memory. Accidental 1891 access to this is obviously disastrous, but specific access can 1892 be used by people debugging the kernel. Note that with PAT support 1893 enabled, even in this case there are restrictions on /dev/mem 1894 use due to the cache aliasing requirements. 1895 1896 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 1897 file only allows userspace access to PCI space and the BIOS code and 1898 data regions. This is sufficient for dosemu and X and all common 1899 users of /dev/mem. 1900 1901 If in doubt, say Y. 1902 1903config IO_STRICT_DEVMEM 1904 bool "Filter I/O access to /dev/mem" 1905 depends on STRICT_DEVMEM 1906 help 1907 If this option is disabled, you allow userspace (root) access to all 1908 io-memory regardless of whether a driver is actively using that 1909 range. Accidental access to this is obviously disastrous, but 1910 specific access can be used by people debugging kernel drivers. 1911 1912 If this option is switched on, the /dev/mem file only allows 1913 userspace access to *idle* io-memory ranges (see /proc/iomem) This 1914 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 1915 if the driver using a given range cannot be disabled. 1916 1917 If in doubt, say Y. 1918 1919menu "$(SRCARCH) Debugging" 1920 1921source "arch/$(SRCARCH)/Kconfig.debug" 1922 1923endmenu 1924 1925menu "Kernel Testing and Coverage" 1926 1927source "lib/kunit/Kconfig" 1928 1929config NOTIFIER_ERROR_INJECTION 1930 tristate "Notifier error injection" 1931 depends on DEBUG_KERNEL 1932 select DEBUG_FS 1933 help 1934 This option provides the ability to inject artificial errors to 1935 specified notifier chain callbacks. It is useful to test the error 1936 handling of notifier call chain failures. 1937 1938 Say N if unsure. 1939 1940config PM_NOTIFIER_ERROR_INJECT 1941 tristate "PM notifier error injection module" 1942 depends on PM && NOTIFIER_ERROR_INJECTION 1943 default m if PM_DEBUG 1944 help 1945 This option provides the ability to inject artificial errors to 1946 PM notifier chain callbacks. It is controlled through debugfs 1947 interface /sys/kernel/debug/notifier-error-inject/pm 1948 1949 If the notifier call chain should be failed with some events 1950 notified, write the error code to "actions/<notifier event>/error". 1951 1952 Example: Inject PM suspend error (-12 = -ENOMEM) 1953 1954 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1955 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1956 # echo mem > /sys/power/state 1957 bash: echo: write error: Cannot allocate memory 1958 1959 To compile this code as a module, choose M here: the module will 1960 be called pm-notifier-error-inject. 1961 1962 If unsure, say N. 1963 1964config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1965 tristate "OF reconfig notifier error injection module" 1966 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1967 help 1968 This option provides the ability to inject artificial errors to 1969 OF reconfig notifier chain callbacks. It is controlled 1970 through debugfs interface under 1971 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1972 1973 If the notifier call chain should be failed with some events 1974 notified, write the error code to "actions/<notifier event>/error". 1975 1976 To compile this code as a module, choose M here: the module will 1977 be called of-reconfig-notifier-error-inject. 1978 1979 If unsure, say N. 1980 1981config NETDEV_NOTIFIER_ERROR_INJECT 1982 tristate "Netdev notifier error injection module" 1983 depends on NET && NOTIFIER_ERROR_INJECTION 1984 help 1985 This option provides the ability to inject artificial errors to 1986 netdevice notifier chain callbacks. It is controlled through debugfs 1987 interface /sys/kernel/debug/notifier-error-inject/netdev 1988 1989 If the notifier call chain should be failed with some events 1990 notified, write the error code to "actions/<notifier event>/error". 1991 1992 Example: Inject netdevice mtu change error (-22 = -EINVAL) 1993 1994 # cd /sys/kernel/debug/notifier-error-inject/netdev 1995 # echo -22 > actions/NETDEV_CHANGEMTU/error 1996 # ip link set eth0 mtu 1024 1997 RTNETLINK answers: Invalid argument 1998 1999 To compile this code as a module, choose M here: the module will 2000 be called netdev-notifier-error-inject. 2001 2002 If unsure, say N. 2003 2004config FUNCTION_ERROR_INJECTION 2005 bool "Fault-injections of functions" 2006 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 2007 help 2008 Add fault injections into various functions that are annotated with 2009 ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return 2010 value of these functions. This is useful to test error paths of code. 2011 2012 If unsure, say N 2013 2014config FAULT_INJECTION 2015 bool "Fault-injection framework" 2016 depends on DEBUG_KERNEL 2017 help 2018 Provide fault-injection framework. 2019 For more details, see Documentation/fault-injection/. 2020 2021config FAILSLAB 2022 bool "Fault-injection capability for kmalloc" 2023 depends on FAULT_INJECTION 2024 help 2025 Provide fault-injection capability for kmalloc. 2026 2027config FAIL_PAGE_ALLOC 2028 bool "Fault-injection capability for alloc_pages()" 2029 depends on FAULT_INJECTION 2030 help 2031 Provide fault-injection capability for alloc_pages(). 2032 2033config FAULT_INJECTION_USERCOPY 2034 bool "Fault injection capability for usercopy functions" 2035 depends on FAULT_INJECTION 2036 help 2037 Provides fault-injection capability to inject failures 2038 in usercopy functions (copy_from_user(), get_user(), ...). 2039 2040config FAIL_MAKE_REQUEST 2041 bool "Fault-injection capability for disk IO" 2042 depends on FAULT_INJECTION && BLOCK 2043 help 2044 Provide fault-injection capability for disk IO. 2045 2046config FAIL_IO_TIMEOUT 2047 bool "Fault-injection capability for faking disk interrupts" 2048 depends on FAULT_INJECTION && BLOCK 2049 help 2050 Provide fault-injection capability on end IO handling. This 2051 will make the block layer "forget" an interrupt as configured, 2052 thus exercising the error handling. 2053 2054 Only works with drivers that use the generic timeout handling, 2055 for others it won't do anything. 2056 2057config FAIL_FUTEX 2058 bool "Fault-injection capability for futexes" 2059 select DEBUG_FS 2060 depends on FAULT_INJECTION && FUTEX 2061 help 2062 Provide fault-injection capability for futexes. 2063 2064config FAULT_INJECTION_DEBUG_FS 2065 bool "Debugfs entries for fault-injection capabilities" 2066 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 2067 help 2068 Enable configuration of fault-injection capabilities via debugfs. 2069 2070config FAIL_FUNCTION 2071 bool "Fault-injection capability for functions" 2072 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 2073 help 2074 Provide function-based fault-injection capability. 2075 This will allow you to override a specific function with a return 2076 with given return value. As a result, function caller will see 2077 an error value and have to handle it. This is useful to test the 2078 error handling in various subsystems. 2079 2080config FAIL_MMC_REQUEST 2081 bool "Fault-injection capability for MMC IO" 2082 depends on FAULT_INJECTION_DEBUG_FS && MMC 2083 help 2084 Provide fault-injection capability for MMC IO. 2085 This will make the mmc core return data errors. This is 2086 useful to test the error handling in the mmc block device 2087 and to test how the mmc host driver handles retries from 2088 the block device. 2089 2090config FAIL_SUNRPC 2091 bool "Fault-injection capability for SunRPC" 2092 depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG 2093 help 2094 Provide fault-injection capability for SunRPC and 2095 its consumers. 2096 2097config FAIL_SKB_REALLOC 2098 bool "Fault-injection capability forcing skb to reallocate" 2099 depends on FAULT_INJECTION_DEBUG_FS 2100 help 2101 Provide fault-injection capability that forces the skb to be 2102 reallocated, catching possible invalid pointers to the skb. 2103 2104 For more information, check 2105 Documentation/fault-injection/fault-injection.rst 2106 2107config FAULT_INJECTION_CONFIGFS 2108 bool "Configfs interface for fault-injection capabilities" 2109 depends on FAULT_INJECTION 2110 select CONFIGFS_FS 2111 help 2112 This option allows configfs-based drivers to dynamically configure 2113 fault-injection via configfs. Each parameter for driver-specific 2114 fault-injection can be made visible as a configfs attribute in a 2115 configfs group. 2116 2117 2118config FAULT_INJECTION_STACKTRACE_FILTER 2119 bool "stacktrace filter for fault-injection capabilities" 2120 depends on FAULT_INJECTION 2121 depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT 2122 select STACKTRACE 2123 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 2124 help 2125 Provide stacktrace filter for fault-injection capabilities 2126 2127config ARCH_HAS_KCOV 2128 bool 2129 help 2130 An architecture should select this when it can successfully 2131 build and run with CONFIG_KCOV. This typically requires 2132 disabling instrumentation for some early boot code. 2133 2134config CC_HAS_SANCOV_TRACE_PC 2135 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 2136 2137 2138config KCOV 2139 bool "Code coverage for fuzzing" 2140 depends on ARCH_HAS_KCOV 2141 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 2142 depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \ 2143 GCC_VERSION >= 120000 || CC_IS_CLANG 2144 select DEBUG_FS 2145 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 2146 select OBJTOOL if HAVE_NOINSTR_HACK 2147 help 2148 KCOV exposes kernel code coverage information in a form suitable 2149 for coverage-guided fuzzing (randomized testing). 2150 2151 For more details, see Documentation/dev-tools/kcov.rst. 2152 2153config KCOV_ENABLE_COMPARISONS 2154 bool "Enable comparison operands collection by KCOV" 2155 depends on KCOV 2156 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 2157 help 2158 KCOV also exposes operands of every comparison in the instrumented 2159 code along with operand sizes and PCs of the comparison instructions. 2160 These operands can be used by fuzzing engines to improve the quality 2161 of fuzzing coverage. 2162 2163config KCOV_INSTRUMENT_ALL 2164 bool "Instrument all code by default" 2165 depends on KCOV 2166 default y 2167 help 2168 If you are doing generic system call fuzzing (like e.g. syzkaller), 2169 then you will want to instrument the whole kernel and you should 2170 say y here. If you are doing more targeted fuzzing (like e.g. 2171 filesystem fuzzing with AFL) then you will want to enable coverage 2172 for more specific subsets of files, and should say n here. 2173 2174config KCOV_IRQ_AREA_SIZE 2175 hex "Size of interrupt coverage collection area in words" 2176 depends on KCOV 2177 default 0x40000 2178 help 2179 KCOV uses preallocated per-cpu areas to collect coverage from 2180 soft interrupts. This specifies the size of those areas in the 2181 number of unsigned long words. 2182 2183config KCOV_SELFTEST 2184 bool "Perform short selftests on boot" 2185 depends on KCOV 2186 help 2187 Run short KCOV coverage collection selftests on boot. 2188 On test failure, causes the kernel to panic. Recommended to be 2189 enabled, ensuring critical functionality works as intended. 2190 2191menuconfig RUNTIME_TESTING_MENU 2192 bool "Runtime Testing" 2193 default y 2194 2195if RUNTIME_TESTING_MENU 2196 2197config TEST_DHRY 2198 tristate "Dhrystone benchmark test" 2199 help 2200 Enable this to include the Dhrystone 2.1 benchmark. This test 2201 calculates the number of Dhrystones per second, and the number of 2202 DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided 2203 by 1757 (the number of Dhrystones per second obtained on the VAX 2204 11/780, nominally a 1 MIPS machine). 2205 2206 To run the benchmark, it needs to be enabled explicitly, either from 2207 the kernel command line (when built-in), or from userspace (when 2208 built-in or modular). 2209 2210 Run once during kernel boot: 2211 2212 test_dhry.run 2213 2214 Set number of iterations from kernel command line: 2215 2216 test_dhry.iterations=<n> 2217 2218 Set number of iterations from userspace: 2219 2220 echo <n> > /sys/module/test_dhry/parameters/iterations 2221 2222 Trigger manual run from userspace: 2223 2224 echo y > /sys/module/test_dhry/parameters/run 2225 2226 If the number of iterations is <= 0, the test will devise a suitable 2227 number of iterations (test runs for at least 2s) automatically. 2228 This process takes ca. 4s. 2229 2230 If unsure, say N. 2231 2232config LKDTM 2233 tristate "Linux Kernel Dump Test Tool Module" 2234 depends on DEBUG_FS 2235 help 2236 This module enables testing of the different dumping mechanisms by 2237 inducing system failures at predefined crash points. 2238 If you don't need it: say N 2239 Choose M here to compile this code as a module. The module will be 2240 called lkdtm. 2241 2242 Documentation on how to use the module can be found in 2243 Documentation/fault-injection/provoke-crashes.rst 2244 2245config CPUMASK_KUNIT_TEST 2246 tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS 2247 depends on KUNIT 2248 default KUNIT_ALL_TESTS 2249 help 2250 Enable to turn on cpumask tests, running at boot or module load time. 2251 2252 For more information on KUnit and unit tests in general, please refer 2253 to the KUnit documentation in Documentation/dev-tools/kunit/. 2254 2255 If unsure, say N. 2256 2257config TEST_LIST_SORT 2258 tristate "Linked list sorting test" if !KUNIT_ALL_TESTS 2259 depends on KUNIT 2260 default KUNIT_ALL_TESTS 2261 help 2262 Enable this to turn on 'list_sort()' function test. This test is 2263 executed only once during system boot (so affects only boot time), 2264 or at module load time. 2265 2266 If unsure, say N. 2267 2268config TEST_MIN_HEAP 2269 tristate "Min heap test" 2270 depends on DEBUG_KERNEL || m 2271 help 2272 Enable this to turn on min heap function tests. This test is 2273 executed only once during system boot (so affects only boot time), 2274 or at module load time. 2275 2276 If unsure, say N. 2277 2278config TEST_SORT 2279 tristate "Array-based sort test" if !KUNIT_ALL_TESTS 2280 depends on KUNIT 2281 default KUNIT_ALL_TESTS 2282 help 2283 This option enables the self-test function of 'sort()' at boot, 2284 or at module load time. 2285 2286 If unsure, say N. 2287 2288config TEST_DIV64 2289 tristate "64bit/32bit division and modulo test" 2290 depends on DEBUG_KERNEL || m 2291 help 2292 Enable this to turn on 'do_div()' function test. This test is 2293 executed only once during system boot (so affects only boot time), 2294 or at module load time. 2295 2296 If unsure, say N. 2297 2298config TEST_MULDIV64 2299 tristate "mul_u64_u64_div_u64() test" 2300 depends on DEBUG_KERNEL || m 2301 help 2302 Enable this to turn on 'mul_u64_u64_div_u64()' function test. 2303 This test is executed only once during system boot (so affects 2304 only boot time), or at module load time. 2305 2306 If unsure, say N. 2307 2308config TEST_IOV_ITER 2309 tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS 2310 depends on KUNIT 2311 depends on MMU 2312 default KUNIT_ALL_TESTS 2313 help 2314 Enable this to turn on testing of the operation of the I/O iterator 2315 (iov_iter). This test is executed only once during system boot (so 2316 affects only boot time), or at module load time. 2317 2318 If unsure, say N. 2319 2320config KPROBES_SANITY_TEST 2321 tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS 2322 depends on DEBUG_KERNEL 2323 depends on KPROBES 2324 depends on KUNIT 2325 select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 2326 default KUNIT_ALL_TESTS 2327 help 2328 This option provides for testing basic kprobes functionality on 2329 boot. Samples of kprobe and kretprobe are inserted and 2330 verified for functionality. 2331 2332 Say N if you are unsure. 2333 2334config FPROBE_SANITY_TEST 2335 bool "Self test for fprobe" 2336 depends on DEBUG_KERNEL 2337 depends on FPROBE 2338 depends on KUNIT=y 2339 help 2340 This option will enable testing the fprobe when the system boot. 2341 A series of tests are made to verify that the fprobe is functioning 2342 properly. 2343 2344 Say N if you are unsure. 2345 2346config BACKTRACE_SELF_TEST 2347 tristate "Self test for the backtrace code" 2348 depends on DEBUG_KERNEL 2349 help 2350 This option provides a kernel module that can be used to test 2351 the kernel stack backtrace code. This option is not useful 2352 for distributions or general kernels, but only for kernel 2353 developers working on architecture code. 2354 2355 Note that if you want to also test saved backtraces, you will 2356 have to enable STACKTRACE as well. 2357 2358 Say N if you are unsure. 2359 2360config TEST_REF_TRACKER 2361 tristate "Self test for reference tracker" 2362 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT 2363 select REF_TRACKER 2364 help 2365 This option provides a kernel module performing tests 2366 using reference tracker infrastructure. 2367 2368 Say N if you are unsure. 2369 2370config RBTREE_TEST 2371 tristate "Red-Black tree test" 2372 depends on DEBUG_KERNEL 2373 help 2374 A benchmark measuring the performance of the rbtree library. 2375 Also includes rbtree invariant checks. 2376 2377config REED_SOLOMON_TEST 2378 tristate "Reed-Solomon library test" 2379 depends on DEBUG_KERNEL || m 2380 select REED_SOLOMON 2381 select REED_SOLOMON_ENC16 2382 select REED_SOLOMON_DEC16 2383 help 2384 This option enables the self-test function of rslib at boot, 2385 or at module load time. 2386 2387 If unsure, say N. 2388 2389config INTERVAL_TREE_TEST 2390 tristate "Interval tree test" 2391 depends on DEBUG_KERNEL 2392 select INTERVAL_TREE 2393 help 2394 A benchmark measuring the performance of the interval tree library 2395 2396config PERCPU_TEST 2397 tristate "Per cpu operations test" 2398 depends on m && DEBUG_KERNEL 2399 help 2400 Enable this option to build test module which validates per-cpu 2401 operations. 2402 2403 If unsure, say N. 2404 2405config ATOMIC64_SELFTEST 2406 tristate "Perform an atomic64_t self-test" 2407 help 2408 Enable this option to test the atomic64_t functions at boot or 2409 at module load time. 2410 2411 If unsure, say N. 2412 2413config ASYNC_RAID6_TEST 2414 tristate "Self test for hardware accelerated raid6 recovery" 2415 depends on ASYNC_RAID6_RECOV 2416 select ASYNC_MEMCPY 2417 help 2418 This is a one-shot self test that permutes through the 2419 recovery of all the possible two disk failure scenarios for a 2420 N-disk array. Recovery is performed with the asynchronous 2421 raid6 recovery routines, and will optionally use an offload 2422 engine if one is available. 2423 2424 If unsure, say N. 2425 2426config TEST_HEXDUMP 2427 tristate "Test functions located in the hexdump module at runtime" 2428 2429config STRING_KUNIT_TEST 2430 tristate "KUnit test string functions at runtime" if !KUNIT_ALL_TESTS 2431 depends on KUNIT 2432 default KUNIT_ALL_TESTS 2433 2434config STRING_HELPERS_KUNIT_TEST 2435 tristate "KUnit test string helpers at runtime" if !KUNIT_ALL_TESTS 2436 depends on KUNIT 2437 default KUNIT_ALL_TESTS 2438 2439config TEST_KSTRTOX 2440 tristate "Test kstrto*() family of functions at runtime" 2441 2442config TEST_PRINTF 2443 tristate "Test printf() family of functions at runtime" 2444 2445config TEST_SCANF 2446 tristate "Test scanf() family of functions at runtime" 2447 2448config TEST_BITMAP 2449 tristate "Test bitmap_*() family of functions at runtime" 2450 help 2451 Enable this option to test the bitmap functions at boot. 2452 2453 If unsure, say N. 2454 2455config TEST_UUID 2456 tristate "Test functions located in the uuid module at runtime" 2457 2458config TEST_XARRAY 2459 tristate "Test the XArray code at runtime" 2460 2461config TEST_MAPLE_TREE 2462 tristate "Test the Maple Tree code at runtime or module load" 2463 help 2464 Enable this option to test the maple tree code functions at boot, or 2465 when the module is loaded. Enable "Debug Maple Trees" will enable 2466 more verbose output on failures. 2467 2468 If unsure, say N. 2469 2470config TEST_RHASHTABLE 2471 tristate "Perform selftest on resizable hash table" 2472 help 2473 Enable this option to test the rhashtable functions at boot. 2474 2475 If unsure, say N. 2476 2477config TEST_IDA 2478 tristate "Perform selftest on IDA functions" 2479 2480config TEST_MISC_MINOR 2481 tristate "Basic misc minor Kunit test" if !KUNIT_ALL_TESTS 2482 depends on KUNIT 2483 default KUNIT_ALL_TESTS 2484 help 2485 Kunit test for the misc minor. 2486 It tests misc minor functions for dynamic and misc dynamic minor. 2487 This include misc_xxx functions 2488 2489 If unsure, say N. 2490 2491config TEST_PARMAN 2492 tristate "Perform selftest on priority array manager" 2493 depends on PARMAN 2494 help 2495 Enable this option to test priority array manager on boot 2496 (or module load). 2497 2498 If unsure, say N. 2499 2500config TEST_IRQ_TIMINGS 2501 bool "IRQ timings selftest" 2502 depends on IRQ_TIMINGS 2503 help 2504 Enable this option to test the irq timings code on boot. 2505 2506 If unsure, say N. 2507 2508config TEST_LKM 2509 tristate "Test module loading with 'hello world' module" 2510 depends on m 2511 help 2512 This builds the "test_module" module that emits "Hello, world" 2513 on printk when loaded. It is designed to be used for basic 2514 evaluation of the module loading subsystem (for example when 2515 validating module verification). It lacks any extra dependencies, 2516 and will not normally be loaded by the system unless explicitly 2517 requested by name. 2518 2519 If unsure, say N. 2520 2521config TEST_BITOPS 2522 tristate "Test module for compilation of bitops operations" 2523 help 2524 This builds the "test_bitops" module that is much like the 2525 TEST_LKM module except that it does a basic exercise of the 2526 set/clear_bit macros and get_count_order/long to make sure there are 2527 no compiler warnings from C=1 sparse checker or -Wextra 2528 compilations. It has no dependencies and doesn't run or load unless 2529 explicitly requested by name. for example: modprobe test_bitops. 2530 2531 If unsure, say N. 2532 2533config TEST_VMALLOC 2534 tristate "Test module for stress/performance analysis of vmalloc allocator" 2535 default n 2536 depends on MMU 2537 depends on m 2538 help 2539 This builds the "test_vmalloc" module that should be used for 2540 stress and performance analysis. So, any new change for vmalloc 2541 subsystem can be evaluated from performance and stability point 2542 of view. 2543 2544 If unsure, say N. 2545 2546config TEST_BPF 2547 tristate "Test BPF filter functionality" 2548 depends on m && NET 2549 help 2550 This builds the "test_bpf" module that runs various test vectors 2551 against the BPF interpreter or BPF JIT compiler depending on the 2552 current setting. This is in particular useful for BPF JIT compiler 2553 development, but also to run regression tests against changes in 2554 the interpreter code. It also enables test stubs for eBPF maps and 2555 verifier used by user space verifier testsuite. 2556 2557 If unsure, say N. 2558 2559config TEST_BLACKHOLE_DEV 2560 tristate "Test blackhole netdev functionality" 2561 depends on m && NET 2562 help 2563 This builds the "test_blackhole_dev" module that validates the 2564 data path through this blackhole netdev. 2565 2566 If unsure, say N. 2567 2568config FIND_BIT_BENCHMARK 2569 tristate "Test find_bit functions" 2570 help 2571 This builds the "test_find_bit" module that measure find_*_bit() 2572 functions performance. 2573 2574 If unsure, say N. 2575 2576config TEST_FIRMWARE 2577 tristate "Test firmware loading via userspace interface" 2578 depends on FW_LOADER 2579 help 2580 This builds the "test_firmware" module that creates a userspace 2581 interface for testing firmware loading. This can be used to 2582 control the triggering of firmware loading without needing an 2583 actual firmware-using device. The contents can be rechecked by 2584 userspace. 2585 2586 If unsure, say N. 2587 2588config TEST_SYSCTL 2589 tristate "sysctl test driver" 2590 depends on PROC_SYSCTL 2591 help 2592 This builds the "test_sysctl" module. This driver enables to test the 2593 proc sysctl interfaces available to drivers safely without affecting 2594 production knobs which might alter system functionality. 2595 2596 If unsure, say N. 2597 2598config BITFIELD_KUNIT 2599 tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS 2600 depends on KUNIT 2601 default KUNIT_ALL_TESTS 2602 help 2603 Enable this option to test the bitfield functions at boot. 2604 2605 KUnit tests run during boot and output the results to the debug log 2606 in TAP format (http://testanything.org/). Only useful for kernel devs 2607 running the KUnit test harness, and not intended for inclusion into a 2608 production build. 2609 2610 For more information on KUnit and unit tests in general please refer 2611 to the KUnit documentation in Documentation/dev-tools/kunit/. 2612 2613 If unsure, say N. 2614 2615config CHECKSUM_KUNIT 2616 tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS 2617 depends on KUNIT 2618 default KUNIT_ALL_TESTS 2619 help 2620 Enable this option to test the checksum functions at boot. 2621 2622 KUnit tests run during boot and output the results to the debug log 2623 in TAP format (http://testanything.org/). Only useful for kernel devs 2624 running the KUnit test harness, and not intended for inclusion into a 2625 production build. 2626 2627 For more information on KUnit and unit tests in general please refer 2628 to the KUnit documentation in Documentation/dev-tools/kunit/. 2629 2630 If unsure, say N. 2631 2632config UTIL_MACROS_KUNIT 2633 tristate "KUnit test util_macros.h functions at runtime" if !KUNIT_ALL_TESTS 2634 depends on KUNIT 2635 default KUNIT_ALL_TESTS 2636 help 2637 Enable this option to test the util_macros.h function at boot. 2638 2639 KUnit tests run during boot and output the results to the debug log 2640 in TAP format (http://testanything.org/). Only useful for kernel devs 2641 running the KUnit test harness, and not intended for inclusion into a 2642 production build. 2643 2644 For more information on KUnit and unit tests in general please refer 2645 to the KUnit documentation in Documentation/dev-tools/kunit/. 2646 2647 If unsure, say N. 2648 2649config HASH_KUNIT_TEST 2650 tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS 2651 depends on KUNIT 2652 default KUNIT_ALL_TESTS 2653 help 2654 Enable this option to test the kernel's string (<linux/stringhash.h>), and 2655 integer (<linux/hash.h>) hash functions on boot. 2656 2657 KUnit tests run during boot and output the results to the debug log 2658 in TAP format (https://testanything.org/). Only useful for kernel devs 2659 running the KUnit test harness, and not intended for inclusion into a 2660 production build. 2661 2662 For more information on KUnit and unit tests in general please refer 2663 to the KUnit documentation in Documentation/dev-tools/kunit/. 2664 2665 This is intended to help people writing architecture-specific 2666 optimized versions. If unsure, say N. 2667 2668config RESOURCE_KUNIT_TEST 2669 tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS 2670 depends on KUNIT 2671 default KUNIT_ALL_TESTS 2672 select GET_FREE_REGION 2673 help 2674 This builds the resource API unit test. 2675 Tests the logic of API provided by resource.c and ioport.h. 2676 For more information on KUnit and unit tests in general please refer 2677 to the KUnit documentation in Documentation/dev-tools/kunit/. 2678 2679 If unsure, say N. 2680 2681config SYSCTL_KUNIT_TEST 2682 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS 2683 depends on KUNIT 2684 default KUNIT_ALL_TESTS 2685 help 2686 This builds the proc sysctl unit test, which runs on boot. 2687 Tests the API contract and implementation correctness of sysctl. 2688 For more information on KUnit and unit tests in general please refer 2689 to the KUnit documentation in Documentation/dev-tools/kunit/. 2690 2691 If unsure, say N. 2692 2693config LIST_KUNIT_TEST 2694 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS 2695 depends on KUNIT 2696 default KUNIT_ALL_TESTS 2697 help 2698 This builds the linked list KUnit test suite. 2699 It tests that the API and basic functionality of the list_head type 2700 and associated macros. 2701 2702 KUnit tests run during boot and output the results to the debug log 2703 in TAP format (https://testanything.org/). Only useful for kernel devs 2704 running the KUnit test harness, and not intended for inclusion into a 2705 production build. 2706 2707 For more information on KUnit and unit tests in general please refer 2708 to the KUnit documentation in Documentation/dev-tools/kunit/. 2709 2710 If unsure, say N. 2711 2712config HASHTABLE_KUNIT_TEST 2713 tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS 2714 depends on KUNIT 2715 default KUNIT_ALL_TESTS 2716 help 2717 This builds the hashtable KUnit test suite. 2718 It tests the basic functionality of the API defined in 2719 include/linux/hashtable.h. For more information on KUnit and 2720 unit tests in general please refer to the KUnit documentation 2721 in Documentation/dev-tools/kunit/. 2722 2723 If unsure, say N. 2724 2725config LINEAR_RANGES_TEST 2726 tristate "KUnit test for linear_ranges" 2727 depends on KUNIT 2728 select LINEAR_RANGES 2729 help 2730 This builds the linear_ranges unit test, which runs on boot. 2731 Tests the linear_ranges logic correctness. 2732 For more information on KUnit and unit tests in general please refer 2733 to the KUnit documentation in Documentation/dev-tools/kunit/. 2734 2735 If unsure, say N. 2736 2737config CMDLINE_KUNIT_TEST 2738 tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS 2739 depends on KUNIT 2740 default KUNIT_ALL_TESTS 2741 help 2742 This builds the cmdline API unit test. 2743 Tests the logic of API provided by cmdline.c. 2744 For more information on KUnit and unit tests in general please refer 2745 to the KUnit documentation in Documentation/dev-tools/kunit/. 2746 2747 If unsure, say N. 2748 2749config BITS_TEST 2750 tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS 2751 depends on KUNIT 2752 default KUNIT_ALL_TESTS 2753 help 2754 This builds the bits unit test. 2755 Tests the logic of macros defined in bits.h. 2756 For more information on KUnit and unit tests in general please refer 2757 to the KUnit documentation in Documentation/dev-tools/kunit/. 2758 2759 If unsure, say N. 2760 2761config SLUB_KUNIT_TEST 2762 tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS 2763 depends on SLUB_DEBUG && KUNIT 2764 default KUNIT_ALL_TESTS 2765 help 2766 This builds SLUB allocator unit test. 2767 Tests SLUB cache debugging functionality. 2768 For more information on KUnit and unit tests in general please refer 2769 to the KUnit documentation in Documentation/dev-tools/kunit/. 2770 2771 If unsure, say N. 2772 2773config RATIONAL_KUNIT_TEST 2774 tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS 2775 depends on KUNIT && RATIONAL 2776 default KUNIT_ALL_TESTS 2777 help 2778 This builds the rational math unit test. 2779 For more information on KUnit and unit tests in general please refer 2780 to the KUnit documentation in Documentation/dev-tools/kunit/. 2781 2782 If unsure, say N. 2783 2784config MEMCPY_KUNIT_TEST 2785 tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS 2786 depends on KUNIT 2787 default KUNIT_ALL_TESTS 2788 help 2789 Builds unit tests for memcpy(), memmove(), and memset() functions. 2790 For more information on KUnit and unit tests in general please refer 2791 to the KUnit documentation in Documentation/dev-tools/kunit/. 2792 2793 If unsure, say N. 2794 2795config IS_SIGNED_TYPE_KUNIT_TEST 2796 tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS 2797 depends on KUNIT 2798 default KUNIT_ALL_TESTS 2799 help 2800 Builds unit tests for the is_signed_type() macro. 2801 2802 For more information on KUnit and unit tests in general please refer 2803 to the KUnit documentation in Documentation/dev-tools/kunit/. 2804 2805 If unsure, say N. 2806 2807config OVERFLOW_KUNIT_TEST 2808 tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS 2809 depends on KUNIT 2810 default KUNIT_ALL_TESTS 2811 help 2812 Builds unit tests for the check_*_overflow(), size_*(), allocation, and 2813 related functions. 2814 2815 For more information on KUnit and unit tests in general please refer 2816 to the KUnit documentation in Documentation/dev-tools/kunit/. 2817 2818 If unsure, say N. 2819 2820config STACKINIT_KUNIT_TEST 2821 tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS 2822 depends on KUNIT 2823 default KUNIT_ALL_TESTS 2824 help 2825 Test if the kernel is zero-initializing stack variables and 2826 padding. Coverage is controlled by compiler flags, 2827 CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO, 2828 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2829 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2830 2831config FORTIFY_KUNIT_TEST 2832 tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS 2833 depends on KUNIT 2834 default KUNIT_ALL_TESTS 2835 help 2836 Builds unit tests for checking internals of FORTIFY_SOURCE as used 2837 by the str*() and mem*() family of functions. For testing runtime 2838 traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests. 2839 2840config HW_BREAKPOINT_KUNIT_TEST 2841 bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS 2842 depends on HAVE_HW_BREAKPOINT 2843 depends on KUNIT=y 2844 default KUNIT_ALL_TESTS 2845 help 2846 Tests for hw_breakpoint constraints accounting. 2847 2848 If unsure, say N. 2849 2850config CRC_KUNIT_TEST 2851 tristate "KUnit tests for CRC functions" if !KUNIT_ALL_TESTS 2852 depends on KUNIT 2853 default KUNIT_ALL_TESTS 2854 select CRC16 2855 select CRC_T10DIF 2856 select CRC32 2857 select CRC64 2858 help 2859 Unit tests for the CRC library functions. 2860 2861 This is intended to help people writing architecture-specific 2862 optimized versions. If unsure, say N. 2863 2864config CRC_BENCHMARK 2865 bool "Benchmark for the CRC functions" 2866 depends on CRC_KUNIT_TEST 2867 help 2868 Include benchmarks in the KUnit test suite for the CRC functions. 2869 2870config SIPHASH_KUNIT_TEST 2871 tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS 2872 depends on KUNIT 2873 default KUNIT_ALL_TESTS 2874 help 2875 Enable this option to test the kernel's siphash (<linux/siphash.h>) hash 2876 functions on boot (or module load). 2877 2878 This is intended to help people writing architecture-specific 2879 optimized versions. If unsure, say N. 2880 2881config USERCOPY_KUNIT_TEST 2882 tristate "KUnit Test for user/kernel boundary protections" 2883 depends on KUNIT 2884 default KUNIT_ALL_TESTS 2885 help 2886 This builds the "usercopy_kunit" module that runs sanity checks 2887 on the copy_to/from_user infrastructure, making sure basic 2888 user/kernel boundary testing is working. 2889 2890config TEST_UDELAY 2891 tristate "udelay test driver" 2892 help 2893 This builds the "udelay_test" module that helps to make sure 2894 that udelay() is working properly. 2895 2896 If unsure, say N. 2897 2898config TEST_STATIC_KEYS 2899 tristate "Test static keys" 2900 depends on m 2901 help 2902 Test the static key interfaces. 2903 2904 If unsure, say N. 2905 2906config TEST_DYNAMIC_DEBUG 2907 tristate "Test DYNAMIC_DEBUG" 2908 depends on DYNAMIC_DEBUG 2909 help 2910 This module registers a tracer callback to count enabled 2911 pr_debugs in a 'do_debugging' function, then alters their 2912 enablements, calls the function, and compares counts. 2913 2914 If unsure, say N. 2915 2916config TEST_KMOD 2917 tristate "kmod stress tester" 2918 depends on m 2919 depends on NETDEVICES && NET_CORE && INET # for TUN 2920 depends on BLOCK 2921 depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS 2922 select TEST_LKM 2923 select XFS_FS 2924 select TUN 2925 select BTRFS_FS 2926 help 2927 Test the kernel's module loading mechanism: kmod. kmod implements 2928 support to load modules using the Linux kernel's usermode helper. 2929 This test provides a series of tests against kmod. 2930 2931 Although technically you can either build test_kmod as a module or 2932 into the kernel we disallow building it into the kernel since 2933 it stress tests request_module() and this will very likely cause 2934 some issues by taking over precious threads available from other 2935 module load requests, ultimately this could be fatal. 2936 2937 To run tests run: 2938 2939 tools/testing/selftests/kmod/kmod.sh --help 2940 2941 If unsure, say N. 2942 2943config TEST_RUNTIME 2944 bool 2945 2946config TEST_RUNTIME_MODULE 2947 bool 2948 2949config TEST_KALLSYMS 2950 tristate "module kallsyms find_symbol() test" 2951 depends on m 2952 select TEST_RUNTIME 2953 select TEST_RUNTIME_MODULE 2954 select TEST_KALLSYMS_A 2955 select TEST_KALLSYMS_B 2956 select TEST_KALLSYMS_C 2957 select TEST_KALLSYMS_D 2958 help 2959 This allows us to stress test find_symbol() through the kallsyms 2960 used to place symbols on the kernel ELF kallsyms and modules kallsyms 2961 where we place kernel symbols such as exported symbols. 2962 2963 We have four test modules: 2964 2965 A: has KALLSYSMS_NUMSYMS exported symbols 2966 B: uses one of A's symbols 2967 C: adds KALLSYMS_SCALE_FACTOR * KALLSYSMS_NUMSYMS exported 2968 D: adds 2 * the symbols than C 2969 2970 We stress test find_symbol() through two means: 2971 2972 1) Upon load of B it will trigger simplify_symbols() to look for the 2973 one symbol it uses from the module A with tons of symbols. This is an 2974 indirect way for us to have B call resolve_symbol_wait() upon module 2975 load. This will eventually call find_symbol() which will eventually 2976 try to find the symbols used with find_exported_symbol_in_section(). 2977 find_exported_symbol_in_section() uses bsearch() so a binary search 2978 for each symbol. Binary search will at worst be O(log(n)) so the 2979 larger TEST_MODULE_KALLSYSMS the worse the search. 2980 2981 2) The selftests should load C first, before B. Upon B's load towards 2982 the end right before we call module B's init routine we get 2983 complete_formation() called on the module. That will first check 2984 for duplicate symbols with the call to verify_exported_symbols(). 2985 That is when we'll force iteration on module C's insane symbol list. 2986 Since it has 10 * KALLSYMS_NUMSYMS it means we can first test 2987 just loading B without C. The amount of time it takes to load C Vs 2988 B can give us an idea of the impact growth of the symbol space and 2989 give us projection. Module A only uses one symbol from B so to allow 2990 this scaling in module C to be proportional, if it used more symbols 2991 then the first test would be doing more and increasing just the 2992 search space would be slightly different. The last module, module D 2993 will just increase the search space by twice the number of symbols in 2994 C so to allow for full projects. 2995 2996 tools/testing/selftests/module/find_symbol.sh 2997 2998 The current defaults will incur a build delay of about 7 minutes 2999 on an x86_64 with only 8 cores. Enable this only if you want to 3000 stress test find_symbol() with thousands of symbols. At the same 3001 time this is also useful to test building modules with thousands of 3002 symbols, and if BTF is enabled this also stress tests adding BTF 3003 information for each module. Currently enabling many more symbols 3004 will segfault the build system. 3005 3006 If unsure, say N. 3007 3008if TEST_KALLSYMS 3009 3010config TEST_KALLSYMS_A 3011 tristate 3012 depends on m 3013 3014config TEST_KALLSYMS_B 3015 tristate 3016 depends on m 3017 3018config TEST_KALLSYMS_C 3019 tristate 3020 depends on m 3021 3022config TEST_KALLSYMS_D 3023 tristate 3024 depends on m 3025 3026choice 3027 prompt "Kallsym test range" 3028 default TEST_KALLSYMS_LARGE 3029 help 3030 Selecting something other than "Fast" will enable tests which slow 3031 down the build and may crash your build. 3032 3033config TEST_KALLSYMS_FAST 3034 bool "Fast builds" 3035 help 3036 You won't really be testing kallsysms, so this just helps fast builds 3037 when allmodconfig is used.. 3038 3039config TEST_KALLSYMS_LARGE 3040 bool "Enable testing kallsyms with large exports" 3041 help 3042 This will enable larger number of symbols. This will slow down 3043 your build considerably. 3044 3045config TEST_KALLSYMS_MAX 3046 bool "Known kallsysms limits" 3047 help 3048 This will enable exports to the point we know we'll start crashing 3049 builds. 3050 3051endchoice 3052 3053config TEST_KALLSYMS_NUMSYMS 3054 int "test kallsyms number of symbols" 3055 range 2 10000 3056 default 2 if TEST_KALLSYMS_FAST 3057 default 100 if TEST_KALLSYMS_LARGE 3058 default 10000 if TEST_KALLSYMS_MAX 3059 help 3060 The number of symbols to create on TEST_KALLSYMS_A, only one of which 3061 module TEST_KALLSYMS_B will use. This also will be used 3062 for how many symbols TEST_KALLSYMS_C will have, scaled up by 3063 TEST_KALLSYMS_SCALE_FACTOR. Note that setting this to 10,000 will 3064 trigger a segfault today, don't use anything close to it unless 3065 you are aware that this should not be used for automated build tests. 3066 3067config TEST_KALLSYMS_SCALE_FACTOR 3068 int "test kallsyms scale factor" 3069 default 8 3070 help 3071 How many more unusued symbols will TEST_KALLSYSMS_C have than 3072 TEST_KALLSYMS_A. If 8, then module C will have 8 * syms 3073 than module A. Then TEST_KALLSYMS_D will have double the amount 3074 of symbols than C so to allow projections. 3075 3076endif # TEST_KALLSYMS 3077 3078config TEST_DEBUG_VIRTUAL 3079 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 3080 depends on DEBUG_VIRTUAL 3081 help 3082 Test the kernel's ability to detect incorrect calls to 3083 virt_to_phys() done against the non-linear part of the 3084 kernel's virtual address map. 3085 3086 If unsure, say N. 3087 3088config TEST_MEMCAT_P 3089 tristate "Test memcat_p() helper function" 3090 help 3091 Test the memcat_p() helper for correctly merging two 3092 pointer arrays together. 3093 3094 If unsure, say N. 3095 3096config TEST_OBJAGG 3097 tristate "Perform selftest on object aggreration manager" 3098 default n 3099 depends on OBJAGG 3100 help 3101 Enable this option to test object aggregation manager on boot 3102 (or module load). 3103 3104config TEST_MEMINIT 3105 tristate "Test heap/page initialization" 3106 help 3107 Test if the kernel is zero-initializing heap and page allocations. 3108 This can be useful to test init_on_alloc and init_on_free features. 3109 3110 If unsure, say N. 3111 3112config TEST_HMM 3113 tristate "Test HMM (Heterogeneous Memory Management)" 3114 depends on TRANSPARENT_HUGEPAGE 3115 depends on DEVICE_PRIVATE 3116 select HMM_MIRROR 3117 select MMU_NOTIFIER 3118 help 3119 This is a pseudo device driver solely for testing HMM. 3120 Say M here if you want to build the HMM test module. 3121 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests. 3122 3123 If unsure, say N. 3124 3125config TEST_FREE_PAGES 3126 tristate "Test freeing pages" 3127 help 3128 Test that a memory leak does not occur due to a race between 3129 freeing a block of pages and a speculative page reference. 3130 Loading this module is safe if your kernel has the bug fixed. 3131 If the bug is not fixed, it will leak gigabytes of memory and 3132 probably OOM your system. 3133 3134config TEST_FPU 3135 tristate "Test floating point operations in kernel space" 3136 depends on ARCH_HAS_KERNEL_FPU_SUPPORT && !KCOV_INSTRUMENT_ALL 3137 help 3138 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu 3139 which will trigger a sequence of floating point operations. This is used 3140 for self-testing floating point control register setting in 3141 kernel_fpu_begin(). 3142 3143 If unsure, say N. 3144 3145config TEST_CLOCKSOURCE_WATCHDOG 3146 tristate "Test clocksource watchdog in kernel space" 3147 depends on CLOCKSOURCE_WATCHDOG 3148 help 3149 Enable this option to create a kernel module that will trigger 3150 a test of the clocksource watchdog. This module may be loaded 3151 via modprobe or insmod in which case it will run upon being 3152 loaded, or it may be built in, in which case it will run 3153 shortly after boot. 3154 3155 If unsure, say N. 3156 3157config TEST_OBJPOOL 3158 tristate "Test module for correctness and stress of objpool" 3159 default n 3160 depends on m && DEBUG_KERNEL 3161 help 3162 This builds the "test_objpool" module that should be used for 3163 correctness verification and concurrent testings of objects 3164 allocation and reclamation. 3165 3166 If unsure, say N. 3167 3168config INT_POW_TEST 3169 tristate "Integer exponentiation (int_pow) test" if !KUNIT_ALL_TESTS 3170 depends on KUNIT 3171 default KUNIT_ALL_TESTS 3172 help 3173 This option enables the KUnit test suite for the int_pow function, 3174 which performs integer exponentiation. The test suite is designed to 3175 verify that the implementation of int_pow correctly computes the power 3176 of a given base raised to a given exponent. 3177 3178 Enabling this option will include tests that check various scenarios 3179 and edge cases to ensure the accuracy and reliability of the exponentiation 3180 function. 3181 3182 If unsure, say N 3183 3184config INT_SQRT_KUNIT_TEST 3185 tristate "Integer square root test" if !KUNIT_ALL_TESTS 3186 depends on KUNIT 3187 default KUNIT_ALL_TESTS 3188 help 3189 This option enables the KUnit test suite for the int_sqrt() function, 3190 which performs square root calculation. The test suite checks 3191 various scenarios, including edge cases, to ensure correctness. 3192 3193 Enabling this option will include tests that check various scenarios 3194 and edge cases to ensure the accuracy and reliability of the square root 3195 function. 3196 3197 If unsure, say N 3198 3199endif # RUNTIME_TESTING_MENU 3200 3201config ARCH_USE_MEMTEST 3202 bool 3203 help 3204 An architecture should select this when it uses early_memtest() 3205 during boot process. 3206 3207config MEMTEST 3208 bool "Memtest" 3209 depends on ARCH_USE_MEMTEST 3210 help 3211 This option adds a kernel parameter 'memtest', which allows memtest 3212 to be set and executed. 3213 memtest=0, mean disabled; -- default 3214 memtest=1, mean do 1 test pattern; 3215 ... 3216 memtest=17, mean do 17 test patterns. 3217 If you are unsure how to answer this question, answer N. 3218 3219 3220 3221config HYPERV_TESTING 3222 bool "Microsoft Hyper-V driver testing" 3223 default n 3224 depends on HYPERV && DEBUG_FS 3225 help 3226 Select this option to enable Hyper-V vmbus testing. 3227 3228endmenu # "Kernel Testing and Coverage" 3229 3230menu "Rust hacking" 3231 3232config RUST_DEBUG_ASSERTIONS 3233 bool "Debug assertions" 3234 depends on RUST 3235 help 3236 Enables rustc's `-Cdebug-assertions` codegen option. 3237 3238 This flag lets you turn `cfg(debug_assertions)` conditional 3239 compilation on or off. This can be used to enable extra debugging 3240 code in development but not in production. For example, it controls 3241 the behavior of the standard library's `debug_assert!` macro. 3242 3243 Note that this will apply to all Rust code, including `core`. 3244 3245 If unsure, say N. 3246 3247config RUST_OVERFLOW_CHECKS 3248 bool "Overflow checks" 3249 default y 3250 depends on RUST 3251 help 3252 Enables rustc's `-Coverflow-checks` codegen option. 3253 3254 This flag allows you to control the behavior of runtime integer 3255 overflow. When overflow-checks are enabled, a Rust panic will occur 3256 on overflow. 3257 3258 Note that this will apply to all Rust code, including `core`. 3259 3260 If unsure, say Y. 3261 3262config RUST_BUILD_ASSERT_ALLOW 3263 bool "Allow unoptimized build-time assertions" 3264 depends on RUST 3265 help 3266 Controls how `build_error!` and `build_assert!` are handled during the build. 3267 3268 If calls to them exist in the binary, it may indicate a violated invariant 3269 or that the optimizer failed to verify the invariant during compilation. 3270 3271 This should not happen, thus by default the build is aborted. However, 3272 as an escape hatch, you can choose Y here to ignore them during build 3273 and let the check be carried at runtime (with `panic!` being called if 3274 the check fails). 3275 3276 If unsure, say N. 3277 3278config RUST_KERNEL_DOCTESTS 3279 bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS 3280 depends on RUST && KUNIT=y 3281 default KUNIT_ALL_TESTS 3282 help 3283 This builds the documentation tests of the `kernel` crate 3284 as KUnit tests. 3285 3286 For more information on KUnit and unit tests in general, 3287 please refer to the KUnit documentation in Documentation/dev-tools/kunit/. 3288 3289 If unsure, say N. 3290 3291endmenu # "Rust" 3292 3293endmenu # Kernel hacking 3294