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