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 typeinfo" 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 def_bool y 412 depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF 413 help 414 Generate compact split BTF type information for kernel modules. 415 416config MODULE_ALLOW_BTF_MISMATCH 417 bool "Allow loading modules with non-matching BTF type info" 418 depends on DEBUG_INFO_BTF_MODULES 419 help 420 For modules whose split BTF does not match vmlinux, load without 421 BTF rather than refusing to load. The default behavior with 422 module BTF enabled is to reject modules with such mismatches; 423 this option will still load module BTF where possible but ignore 424 it when a mismatch is found. 425 426config GDB_SCRIPTS 427 bool "Provide GDB scripts for kernel debugging" 428 help 429 This creates the required links to GDB helper scripts in the 430 build directory. If you load vmlinux into gdb, the helper 431 scripts will be automatically imported by gdb as well, and 432 additional functions are available to analyze a Linux kernel 433 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst 434 for further details. 435 436endif # DEBUG_INFO 437 438config FRAME_WARN 439 int "Warn for stack frames larger than" 440 range 0 8192 441 default 0 if KMSAN 442 default 2048 if GCC_PLUGIN_LATENT_ENTROPY 443 default 2048 if PARISC 444 default 1536 if (!64BIT && XTENSA) 445 default 1280 if KASAN && !64BIT 446 default 1024 if !64BIT 447 default 2048 if 64BIT 448 help 449 Tell the compiler to warn at build time for stack frames larger than this. 450 Setting this too low will cause a lot of warnings. 451 Setting it to 0 disables the warning. 452 453config STRIP_ASM_SYMS 454 bool "Strip assembler-generated symbols during link" 455 default n 456 help 457 Strip internal assembler-generated symbols during a link (symbols 458 that look like '.Lxxx') so they don't pollute the output of 459 get_wchan() and suchlike. 460 461config READABLE_ASM 462 bool "Generate readable assembler code" 463 depends on DEBUG_KERNEL 464 depends on CC_IS_GCC 465 help 466 Disable some compiler optimizations that tend to generate human unreadable 467 assembler output. This may make the kernel slightly slower, but it helps 468 to keep kernel developers who have to stare a lot at assembler listings 469 sane. 470 471config HEADERS_INSTALL 472 bool "Install uapi headers to usr/include" 473 depends on !UML 474 help 475 This option will install uapi headers (headers exported to user-space) 476 into the usr/include directory for use during the kernel build. 477 This is unneeded for building the kernel itself, but needed for some 478 user-space program samples. It is also needed by some features such 479 as uapi header sanity checks. 480 481config DEBUG_SECTION_MISMATCH 482 bool "Enable full Section mismatch analysis" 483 depends on CC_IS_GCC 484 help 485 The section mismatch analysis checks if there are illegal 486 references from one section to another section. 487 During linktime or runtime, some sections are dropped; 488 any use of code/data previously in these sections would 489 most likely result in an oops. 490 In the code, functions and variables are annotated with 491 __init,, etc. (see the full list in include/linux/init.h), 492 which results in the code/data being placed in specific sections. 493 The section mismatch analysis is always performed after a full 494 kernel build, and enabling this option causes the following 495 additional step to occur: 496 - Add the option -fno-inline-functions-called-once to gcc commands. 497 When inlining a function annotated with __init in a non-init 498 function, we would lose the section information and thus 499 the analysis would not catch the illegal reference. 500 This option tells gcc to inline less (but it does result in 501 a larger kernel). 502 503config SECTION_MISMATCH_WARN_ONLY 504 bool "Make section mismatch errors non-fatal" 505 default y 506 help 507 If you say N here, the build process will fail if there are any 508 section mismatch, instead of just throwing warnings. 509 510 If unsure, say Y. 511 512config DEBUG_FORCE_FUNCTION_ALIGN_64B 513 bool "Force all function address 64B aligned" 514 depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC || RISCV || S390) 515 select FUNCTION_ALIGNMENT_64B 516 help 517 There are cases that a commit from one domain changes the function 518 address alignment of other domains, and cause magic performance 519 bump (regression or improvement). Enable this option will help to 520 verify if the bump is caused by function alignment changes, while 521 it will slightly increase the kernel size and affect icache usage. 522 523 It is mainly for debug and performance tuning use. 524 525# 526# Select this config option from the architecture Kconfig, if it 527# is preferred to always offer frame pointers as a config 528# option on the architecture (regardless of KERNEL_DEBUG): 529# 530config ARCH_WANT_FRAME_POINTERS 531 bool 532 533config FRAME_POINTER 534 bool "Compile the kernel with frame pointers" 535 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS 536 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 537 help 538 If you say Y here the resulting kernel image will be slightly 539 larger and slower, but it gives very useful debugging information 540 in case of kernel bugs. (precise oopses/stacktraces/warnings) 541 542config OBJTOOL 543 bool 544 545config STACK_VALIDATION 546 bool "Compile-time stack metadata validation" 547 depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER 548 select OBJTOOL 549 default n 550 help 551 Validate frame pointer rules at compile-time. This helps ensure that 552 runtime stack traces are more reliable. 553 554 For more information, see 555 tools/objtool/Documentation/objtool.txt. 556 557config NOINSTR_VALIDATION 558 bool 559 depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY 560 select OBJTOOL 561 default y 562 563config VMLINUX_MAP 564 bool "Generate vmlinux.map file when linking" 565 depends on EXPERT 566 help 567 Selecting this option will pass "-Map=vmlinux.map" to ld 568 when linking vmlinux. That file can be useful for verifying 569 and debugging magic section games, and for seeing which 570 pieces of code get eliminated with 571 CONFIG_LD_DEAD_CODE_DATA_ELIMINATION. 572 573config DEBUG_FORCE_WEAK_PER_CPU 574 bool "Force weak per-cpu definitions" 575 depends on DEBUG_KERNEL 576 help 577 s390 and alpha require percpu variables in modules to be 578 defined weak to work around addressing range issue which 579 puts the following two restrictions on percpu variable 580 definitions. 581 582 1. percpu symbols must be unique whether static or not 583 2. percpu variables can't be defined inside a function 584 585 To ensure that generic code follows the above rules, this 586 option forces all percpu variables to be defined as weak. 587 588endmenu # "Compiler options" 589 590menu "Generic Kernel Debugging Instruments" 591 592config MAGIC_SYSRQ 593 bool "Magic SysRq key" 594 depends on !UML 595 help 596 If you say Y here, you will have some control over the system even 597 if the system crashes for example during kernel debugging (e.g., you 598 will be able to flush the buffer cache to disk, reboot the system 599 immediately or dump some status information). This is accomplished 600 by pressing various keys while holding SysRq (Alt+PrintScreen). It 601 also works on a serial console (on PC hardware at least), if you 602 send a BREAK and then within 5 seconds a command keypress. The 603 keys are documented in <file:Documentation/admin-guide/sysrq.rst>. 604 Don't say Y unless you really know what this hack does. 605 606config MAGIC_SYSRQ_DEFAULT_ENABLE 607 hex "Enable magic SysRq key functions by default" 608 depends on MAGIC_SYSRQ 609 default 0x1 610 help 611 Specifies which SysRq key functions are enabled by default. 612 This may be set to 1 or 0 to enable or disable them all, or 613 to a bitmask as described in Documentation/admin-guide/sysrq.rst. 614 615config MAGIC_SYSRQ_SERIAL 616 bool "Enable magic SysRq key over serial" 617 depends on MAGIC_SYSRQ 618 default y 619 help 620 Many embedded boards have a disconnected TTL level serial which can 621 generate some garbage that can lead to spurious false sysrq detects. 622 This option allows you to decide whether you want to enable the 623 magic SysRq key. 624 625config MAGIC_SYSRQ_SERIAL_SEQUENCE 626 string "Char sequence that enables magic SysRq over serial" 627 depends on MAGIC_SYSRQ_SERIAL 628 default "" 629 help 630 Specifies a sequence of characters that can follow BREAK to enable 631 SysRq on a serial console. 632 633 If unsure, leave an empty string and the option will not be enabled. 634 635config DEBUG_FS 636 bool "Debug Filesystem" 637 help 638 debugfs is a virtual file system that kernel developers use to put 639 debugging files into. Enable this option to be able to read and 640 write to these files. 641 642 For detailed documentation on the debugfs API, see 643 Documentation/filesystems/. 644 645 If unsure, say N. 646 647choice 648 prompt "Debugfs default access" 649 depends on DEBUG_FS 650 default DEBUG_FS_ALLOW_ALL 651 help 652 This selects the default access restrictions for debugfs. 653 It can be overridden with kernel command line option 654 debugfs=[on,no-mount,off]. The restrictions apply for API access 655 and filesystem registration. 656 657config DEBUG_FS_ALLOW_ALL 658 bool "Access normal" 659 help 660 No restrictions apply. Both API and filesystem registration 661 is on. This is the normal default operation. 662 663config DEBUG_FS_DISALLOW_MOUNT 664 bool "Do not register debugfs as filesystem" 665 help 666 The API is open but filesystem is not loaded. Clients can still do 667 their work and read with debug tools that do not need 668 debugfs filesystem. 669 670config DEBUG_FS_ALLOW_NONE 671 bool "No access" 672 help 673 Access is off. Clients get -PERM when trying to create nodes in 674 debugfs tree and debugfs is not registered as a filesystem. 675 Client can then back-off or continue without debugfs access. 676 677endchoice 678 679source "lib/Kconfig.kgdb" 680source "lib/Kconfig.ubsan" 681source "lib/Kconfig.kcsan" 682 683endmenu 684 685menu "Networking Debugging" 686 687source "net/Kconfig.debug" 688 689endmenu # "Networking Debugging" 690 691menu "Memory Debugging" 692 693source "mm/Kconfig.debug" 694 695config DEBUG_OBJECTS 696 bool "Debug object operations" 697 depends on DEBUG_KERNEL 698 help 699 If you say Y here, additional code will be inserted into the 700 kernel to track the life time of various objects and validate 701 the operations on those objects. 702 703config DEBUG_OBJECTS_SELFTEST 704 bool "Debug objects selftest" 705 depends on DEBUG_OBJECTS 706 help 707 This enables the selftest of the object debug code. 708 709config DEBUG_OBJECTS_FREE 710 bool "Debug objects in freed memory" 711 depends on DEBUG_OBJECTS 712 help 713 This enables checks whether a k/v free operation frees an area 714 which contains an object which has not been deactivated 715 properly. This can make kmalloc/kfree-intensive workloads 716 much slower. 717 718config DEBUG_OBJECTS_TIMERS 719 bool "Debug timer objects" 720 depends on DEBUG_OBJECTS 721 help 722 If you say Y here, additional code will be inserted into the 723 timer routines to track the life time of timer objects and 724 validate the timer operations. 725 726config DEBUG_OBJECTS_WORK 727 bool "Debug work objects" 728 depends on DEBUG_OBJECTS 729 help 730 If you say Y here, additional code will be inserted into the 731 work queue routines to track the life time of work objects and 732 validate the work operations. 733 734config DEBUG_OBJECTS_RCU_HEAD 735 bool "Debug RCU callbacks objects" 736 depends on DEBUG_OBJECTS 737 help 738 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 739 740config DEBUG_OBJECTS_PERCPU_COUNTER 741 bool "Debug percpu counter objects" 742 depends on DEBUG_OBJECTS 743 help 744 If you say Y here, additional code will be inserted into the 745 percpu counter routines to track the life time of percpu counter 746 objects and validate the percpu counter operations. 747 748config DEBUG_OBJECTS_ENABLE_DEFAULT 749 int "debug_objects bootup default value (0-1)" 750 range 0 1 751 default "1" 752 depends on DEBUG_OBJECTS 753 help 754 Debug objects boot parameter default value 755 756config SHRINKER_DEBUG 757 bool "Enable shrinker debugging support" 758 depends on DEBUG_FS 759 help 760 Say Y to enable the shrinker debugfs interface which provides 761 visibility into the kernel memory shrinkers subsystem. 762 Disable it to avoid an extra memory footprint. 763 764config DEBUG_STACK_USAGE 765 bool "Stack utilization instrumentation" 766 depends on DEBUG_KERNEL 767 help 768 Enables the display of the minimum amount of free stack which each 769 task has ever had available in the sysrq-T and sysrq-P debug output. 770 Also emits a message to dmesg when a process exits if that process 771 used more stack space than previously exiting processes. 772 773 This option will slow down process creation somewhat. 774 775config SCHED_STACK_END_CHECK 776 bool "Detect stack corruption on calls to schedule()" 777 depends on DEBUG_KERNEL 778 default n 779 help 780 This option checks for a stack overrun on calls to schedule(). 781 If the stack end location is found to be over written always panic as 782 the content of the corrupted region can no longer be trusted. 783 This is to ensure no erroneous behaviour occurs which could result in 784 data corruption or a sporadic crash at a later stage once the region 785 is examined. The runtime overhead introduced is minimal. 786 787config ARCH_HAS_DEBUG_VM_PGTABLE 788 bool 789 help 790 An architecture should select this when it can successfully 791 build and run DEBUG_VM_PGTABLE. 792 793config DEBUG_VM_IRQSOFF 794 def_bool DEBUG_VM && !PREEMPT_RT 795 796config DEBUG_VM 797 bool "Debug VM" 798 depends on DEBUG_KERNEL 799 help 800 Enable this to turn on extended checks in the virtual-memory system 801 that may impact performance. 802 803 If unsure, say N. 804 805config DEBUG_VM_SHOOT_LAZIES 806 bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation" 807 depends on DEBUG_VM 808 depends on MMU_LAZY_TLB_SHOOTDOWN 809 help 810 Enable additional IPIs that ensure lazy tlb mm references are removed 811 before the mm is freed. 812 813 If unsure, say N. 814 815config DEBUG_VM_MAPLE_TREE 816 bool "Debug VM maple trees" 817 depends on DEBUG_VM 818 select DEBUG_MAPLE_TREE 819 help 820 Enable VM maple tree debugging information and extra validations. 821 822 If unsure, say N. 823 824config DEBUG_VM_RB 825 bool "Debug VM red-black trees" 826 depends on DEBUG_VM 827 help 828 Enable VM red-black tree debugging information and extra validations. 829 830 If unsure, say N. 831 832config DEBUG_VM_PGFLAGS 833 bool "Debug page-flags operations" 834 depends on DEBUG_VM 835 help 836 Enables extra validation on page flags operations. 837 838 If unsure, say N. 839 840config DEBUG_VM_PGTABLE 841 bool "Debug arch page table for semantics compliance" 842 depends on MMU 843 depends on ARCH_HAS_DEBUG_VM_PGTABLE 844 default y if DEBUG_VM 845 help 846 This option provides a debug method which can be used to test 847 architecture page table helper functions on various platforms in 848 verifying if they comply with expected generic MM semantics. This 849 will help architecture code in making sure that any changes or 850 new additions of these helpers still conform to expected 851 semantics of the generic MM. Platforms will have to opt in for 852 this through ARCH_HAS_DEBUG_VM_PGTABLE. 853 854 If unsure, say N. 855 856config ARCH_HAS_DEBUG_VIRTUAL 857 bool 858 859config DEBUG_VIRTUAL 860 bool "Debug VM translations" 861 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL 862 help 863 Enable some costly sanity checks in virtual to page code. This can 864 catch mistakes with virt_to_page() and friends. 865 866 If unsure, say N. 867 868config DEBUG_NOMMU_REGIONS 869 bool "Debug the global anon/private NOMMU mapping region tree" 870 depends on DEBUG_KERNEL && !MMU 871 help 872 This option causes the global tree of anonymous and private mapping 873 regions to be regularly checked for invalid topology. 874 875config DEBUG_MEMORY_INIT 876 bool "Debug memory initialisation" if EXPERT 877 default !EXPERT 878 help 879 Enable this for additional checks during memory initialisation. 880 The sanity checks verify aspects of the VM such as the memory model 881 and other information provided by the architecture. Verbose 882 information will be printed at KERN_DEBUG loglevel depending 883 on the mminit_loglevel= command-line option. 884 885 If unsure, say Y 886 887config MEMORY_NOTIFIER_ERROR_INJECT 888 tristate "Memory hotplug notifier error injection module" 889 depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION 890 help 891 This option provides the ability to inject artificial errors to 892 memory hotplug notifier chain callbacks. It is controlled through 893 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 894 895 If the notifier call chain should be failed with some events 896 notified, write the error code to "actions/<notifier event>/error". 897 898 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 899 900 # cd /sys/kernel/debug/notifier-error-inject/memory 901 # echo -12 > actions/MEM_GOING_OFFLINE/error 902 # echo offline > /sys/devices/system/memory/memoryXXX/state 903 bash: echo: write error: Cannot allocate memory 904 905 To compile this code as a module, choose M here: the module will 906 be called memory-notifier-error-inject. 907 908 If unsure, say N. 909 910config DEBUG_PER_CPU_MAPS 911 bool "Debug access to per_cpu maps" 912 depends on DEBUG_KERNEL 913 depends on SMP 914 help 915 Say Y to verify that the per_cpu map being accessed has 916 been set up. This adds a fair amount of code to kernel memory 917 and decreases performance. 918 919 Say N if unsure. 920 921config DEBUG_KMAP_LOCAL 922 bool "Debug kmap_local temporary mappings" 923 depends on DEBUG_KERNEL && KMAP_LOCAL 924 help 925 This option enables additional error checking for the kmap_local 926 infrastructure. Disable for production use. 927 928config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 929 bool 930 931config DEBUG_KMAP_LOCAL_FORCE_MAP 932 bool "Enforce kmap_local temporary mappings" 933 depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 934 select KMAP_LOCAL 935 select DEBUG_KMAP_LOCAL 936 help 937 This option enforces temporary mappings through the kmap_local 938 mechanism for non-highmem pages and on non-highmem systems. 939 Disable this for production systems! 940 941config DEBUG_HIGHMEM 942 bool "Highmem debugging" 943 depends on DEBUG_KERNEL && HIGHMEM 944 select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 945 select DEBUG_KMAP_LOCAL 946 help 947 This option enables additional error checking for high memory 948 systems. Disable for production systems. 949 950config HAVE_DEBUG_STACKOVERFLOW 951 bool 952 953config DEBUG_STACKOVERFLOW 954 bool "Check for stack overflows" 955 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 956 help 957 Say Y here if you want to check for overflows of kernel, IRQ 958 and exception stacks (if your architecture uses them). This 959 option will show detailed messages if free stack space drops 960 below a certain limit. 961 962 These kinds of bugs usually occur when call-chains in the 963 kernel get too deep, especially when interrupts are 964 involved. 965 966 Use this in cases where you see apparently random memory 967 corruption, especially if it appears in 'struct thread_info' 968 969 If in doubt, say "N". 970 971source "lib/Kconfig.kasan" 972source "lib/Kconfig.kfence" 973source "lib/Kconfig.kmsan" 974 975endmenu # "Memory Debugging" 976 977config DEBUG_SHIRQ 978 bool "Debug shared IRQ handlers" 979 depends on DEBUG_KERNEL 980 help 981 Enable this to generate a spurious interrupt just before a shared 982 interrupt handler is deregistered (generating one when registering 983 is currently disabled). Drivers need to handle this correctly. Some 984 don't and need to be caught. 985 986menu "Debug Oops, Lockups and Hangs" 987 988config PANIC_ON_OOPS 989 bool "Panic on Oops" 990 help 991 Say Y here to enable the kernel to panic when it oopses. This 992 has the same effect as setting oops=panic on the kernel command 993 line. 994 995 This feature is useful to ensure that the kernel does not do 996 anything erroneous after an oops which could result in data 997 corruption or other issues. 998 999 Say N if unsure. 1000 1001config PANIC_ON_OOPS_VALUE 1002 int 1003 range 0 1 1004 default 0 if !PANIC_ON_OOPS 1005 default 1 if PANIC_ON_OOPS 1006 1007config PANIC_TIMEOUT 1008 int "panic timeout" 1009 default 0 1010 help 1011 Set the timeout value (in seconds) until a reboot occurs when 1012 the kernel panics. If n = 0, then we wait forever. A timeout 1013 value n > 0 will wait n seconds before rebooting, while a timeout 1014 value n < 0 will reboot immediately. 1015 1016config LOCKUP_DETECTOR 1017 bool 1018 1019config SOFTLOCKUP_DETECTOR 1020 bool "Detect Soft Lockups" 1021 depends on DEBUG_KERNEL && !S390 1022 select LOCKUP_DETECTOR 1023 help 1024 Say Y here to enable the kernel to act as a watchdog to detect 1025 soft lockups. 1026 1027 Softlockups are bugs that cause the kernel to loop in kernel 1028 mode for more than 20 seconds, without giving other tasks a 1029 chance to run. The current stack trace is displayed upon 1030 detection and the system will stay locked up. 1031 1032config BOOTPARAM_SOFTLOCKUP_PANIC 1033 bool "Panic (Reboot) On Soft Lockups" 1034 depends on SOFTLOCKUP_DETECTOR 1035 help 1036 Say Y here to enable the kernel to panic on "soft lockups", 1037 which are bugs that cause the kernel to loop in kernel 1038 mode for more than 20 seconds (configurable using the watchdog_thresh 1039 sysctl), without giving other tasks a chance to run. 1040 1041 The panic can be used in combination with panic_timeout, 1042 to cause the system to reboot automatically after a 1043 lockup has been detected. This feature is useful for 1044 high-availability systems that have uptime guarantees and 1045 where a lockup must be resolved ASAP. 1046 1047 Say N if unsure. 1048 1049config HAVE_HARDLOCKUP_DETECTOR_BUDDY 1050 bool 1051 depends on SMP 1052 default y 1053 1054# 1055# Global switch whether to build a hardlockup detector at all. It is available 1056# only when the architecture supports at least one implementation. There are 1057# two exceptions. The hardlockup detector is never enabled on: 1058# 1059# s390: it reported many false positives there 1060# 1061# sparc64: has a custom implementation which is not using the common 1062# hardlockup command line options and sysctl interface. 1063# 1064config HARDLOCKUP_DETECTOR 1065 bool "Detect Hard Lockups" 1066 depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64 1067 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH 1068 imply HARDLOCKUP_DETECTOR_PERF 1069 imply HARDLOCKUP_DETECTOR_BUDDY 1070 imply HARDLOCKUP_DETECTOR_ARCH 1071 select LOCKUP_DETECTOR 1072 1073 help 1074 Say Y here to enable the kernel to act as a watchdog to detect 1075 hard lockups. 1076 1077 Hardlockups are bugs that cause the CPU to loop in kernel mode 1078 for more than 10 seconds, without letting other interrupts have a 1079 chance to run. The current stack trace is displayed upon detection 1080 and the system will stay locked up. 1081 1082# 1083# Note that arch-specific variants are always preferred. 1084# 1085config HARDLOCKUP_DETECTOR_PREFER_BUDDY 1086 bool "Prefer the buddy CPU hardlockup detector" 1087 depends on HARDLOCKUP_DETECTOR 1088 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY 1089 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1090 help 1091 Say Y here to prefer the buddy hardlockup detector over the perf one. 1092 1093 With the buddy detector, each CPU uses its softlockup hrtimer 1094 to check that the next CPU is processing hrtimer interrupts by 1095 verifying that a counter is increasing. 1096 1097 This hardlockup detector is useful on systems that don't have 1098 an arch-specific hardlockup detector or if resources needed 1099 for the hardlockup detector are better used for other things. 1100 1101config HARDLOCKUP_DETECTOR_PERF 1102 bool 1103 depends on HARDLOCKUP_DETECTOR 1104 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY 1105 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1106 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1107 1108config HARDLOCKUP_DETECTOR_BUDDY 1109 bool 1110 depends on HARDLOCKUP_DETECTOR 1111 depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY 1112 depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY 1113 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1114 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1115 1116config HARDLOCKUP_DETECTOR_ARCH 1117 bool 1118 depends on HARDLOCKUP_DETECTOR 1119 depends on HAVE_HARDLOCKUP_DETECTOR_ARCH 1120 help 1121 The arch-specific implementation of the hardlockup detector will 1122 be used. 1123 1124# 1125# Both the "perf" and "buddy" hardlockup detectors count hrtimer 1126# interrupts. This config enables functions managing this common code. 1127# 1128config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1129 bool 1130 select SOFTLOCKUP_DETECTOR 1131 1132# 1133# Enables a timestamp based low pass filter to compensate for perf based 1134# hard lockup detection which runs too fast due to turbo modes. 1135# 1136config HARDLOCKUP_CHECK_TIMESTAMP 1137 bool 1138 1139config BOOTPARAM_HARDLOCKUP_PANIC 1140 bool "Panic (Reboot) On Hard Lockups" 1141 depends on HARDLOCKUP_DETECTOR 1142 help 1143 Say Y here to enable the kernel to panic on "hard lockups", 1144 which are bugs that cause the kernel to loop in kernel 1145 mode with interrupts disabled for more than 10 seconds (configurable 1146 using the watchdog_thresh sysctl). 1147 1148 Say N if unsure. 1149 1150config DETECT_HUNG_TASK 1151 bool "Detect Hung Tasks" 1152 depends on DEBUG_KERNEL 1153 default SOFTLOCKUP_DETECTOR 1154 help 1155 Say Y here to enable the kernel to detect "hung tasks", 1156 which are bugs that cause the task to be stuck in 1157 uninterruptible "D" state indefinitely. 1158 1159 When a hung task is detected, the kernel will print the 1160 current stack trace (which you should report), but the 1161 task will stay in uninterruptible state. If lockdep is 1162 enabled then all held locks will also be reported. This 1163 feature has negligible overhead. 1164 1165config DEFAULT_HUNG_TASK_TIMEOUT 1166 int "Default timeout for hung task detection (in seconds)" 1167 depends on DETECT_HUNG_TASK 1168 default 120 1169 help 1170 This option controls the default timeout (in seconds) used 1171 to determine when a task has become non-responsive and should 1172 be considered hung. 1173 1174 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 1175 sysctl or by writing a value to 1176 /proc/sys/kernel/hung_task_timeout_secs. 1177 1178 A timeout of 0 disables the check. The default is two minutes. 1179 Keeping the default should be fine in most cases. 1180 1181config BOOTPARAM_HUNG_TASK_PANIC 1182 bool "Panic (Reboot) On Hung Tasks" 1183 depends on DETECT_HUNG_TASK 1184 help 1185 Say Y here to enable the kernel to panic on "hung tasks", 1186 which are bugs that cause the kernel to leave a task stuck 1187 in uninterruptible "D" state. 1188 1189 The panic can be used in combination with panic_timeout, 1190 to cause the system to reboot automatically after a 1191 hung task has been detected. This feature is useful for 1192 high-availability systems that have uptime guarantees and 1193 where a hung tasks must be resolved ASAP. 1194 1195 Say N if unsure. 1196 1197config WQ_WATCHDOG 1198 bool "Detect Workqueue Stalls" 1199 depends on DEBUG_KERNEL 1200 help 1201 Say Y here to enable stall detection on workqueues. If a 1202 worker pool doesn't make forward progress on a pending work 1203 item for over a given amount of time, 30s by default, a 1204 warning message is printed along with dump of workqueue 1205 state. This can be configured through kernel parameter 1206 "workqueue.watchdog_thresh" and its sysfs counterpart. 1207 1208config WQ_CPU_INTENSIVE_REPORT 1209 bool "Report per-cpu work items which hog CPU for too long" 1210 depends on DEBUG_KERNEL 1211 help 1212 Say Y here to enable reporting of concurrency-managed per-cpu work 1213 items that hog CPUs for longer than 1214 workqueue.cpu_intensive_thresh_us. Workqueue automatically 1215 detects and excludes them from concurrency management to prevent 1216 them from stalling other per-cpu work items. Occassional 1217 triggering may not necessarily indicate a problem. Repeated 1218 triggering likely indicates that the work item should be switched 1219 to use an unbound workqueue. 1220 1221config TEST_LOCKUP 1222 tristate "Test module to generate lockups" 1223 depends on m 1224 help 1225 This builds the "test_lockup" module that helps to make sure 1226 that watchdogs and lockup detectors are working properly. 1227 1228 Depending on module parameters it could emulate soft or hard 1229 lockup, "hung task", or locking arbitrary lock for a long time. 1230 Also it could generate series of lockups with cooling-down periods. 1231 1232 If unsure, say N. 1233 1234endmenu # "Debug lockups and hangs" 1235 1236menu "Scheduler Debugging" 1237 1238config SCHED_DEBUG 1239 bool "Collect scheduler debugging info" 1240 depends on DEBUG_KERNEL && DEBUG_FS 1241 default y 1242 help 1243 If you say Y here, the /sys/kernel/debug/sched file will be provided 1244 that can help debug the scheduler. The runtime overhead of this 1245 option is minimal. 1246 1247config SCHED_INFO 1248 bool 1249 default n 1250 1251config SCHEDSTATS 1252 bool "Collect scheduler statistics" 1253 depends on DEBUG_KERNEL && PROC_FS 1254 select SCHED_INFO 1255 help 1256 If you say Y here, additional code will be inserted into the 1257 scheduler and related routines to collect statistics about 1258 scheduler behavior and provide them in /proc/schedstat. These 1259 stats may be useful for both tuning and debugging the scheduler 1260 If you aren't debugging the scheduler or trying to tune a specific 1261 application, you can say N to avoid the very slight overhead 1262 this adds. 1263 1264endmenu 1265 1266config DEBUG_TIMEKEEPING 1267 bool "Enable extra timekeeping sanity checking" 1268 help 1269 This option will enable additional timekeeping sanity checks 1270 which may be helpful when diagnosing issues where timekeeping 1271 problems are suspected. 1272 1273 This may include checks in the timekeeping hotpaths, so this 1274 option may have a (very small) performance impact to some 1275 workloads. 1276 1277 If unsure, say N. 1278 1279config DEBUG_PREEMPT 1280 bool "Debug preemptible kernel" 1281 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1282 help 1283 If you say Y here then the kernel will use a debug variant of the 1284 commonly used smp_processor_id() function and will print warnings 1285 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1286 will detect preemption count underflows. 1287 1288 This option has potential to introduce high runtime overhead, 1289 depending on workload as it triggers debugging routines for each 1290 this_cpu operation. It should only be used for debugging purposes. 1291 1292menu "Lock Debugging (spinlocks, mutexes, etc...)" 1293 1294config LOCK_DEBUGGING_SUPPORT 1295 bool 1296 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1297 default y 1298 1299config PROVE_LOCKING 1300 bool "Lock debugging: prove locking correctness" 1301 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1302 select LOCKDEP 1303 select DEBUG_SPINLOCK 1304 select DEBUG_MUTEXES if !PREEMPT_RT 1305 select DEBUG_RT_MUTEXES if RT_MUTEXES 1306 select DEBUG_RWSEMS if !PREEMPT_RT 1307 select DEBUG_WW_MUTEX_SLOWPATH 1308 select DEBUG_LOCK_ALLOC 1309 select PREEMPT_COUNT if !ARCH_NO_PREEMPT 1310 select TRACE_IRQFLAGS 1311 default n 1312 help 1313 This feature enables the kernel to prove that all locking 1314 that occurs in the kernel runtime is mathematically 1315 correct: that under no circumstance could an arbitrary (and 1316 not yet triggered) combination of observed locking 1317 sequences (on an arbitrary number of CPUs, running an 1318 arbitrary number of tasks and interrupt contexts) cause a 1319 deadlock. 1320 1321 In short, this feature enables the kernel to report locking 1322 related deadlocks before they actually occur. 1323 1324 The proof does not depend on how hard and complex a 1325 deadlock scenario would be to trigger: how many 1326 participant CPUs, tasks and irq-contexts would be needed 1327 for it to trigger. The proof also does not depend on 1328 timing: if a race and a resulting deadlock is possible 1329 theoretically (no matter how unlikely the race scenario 1330 is), it will be proven so and will immediately be 1331 reported by the kernel (once the event is observed that 1332 makes the deadlock theoretically possible). 1333 1334 If a deadlock is impossible (i.e. the locking rules, as 1335 observed by the kernel, are mathematically correct), the 1336 kernel reports nothing. 1337 1338 NOTE: this feature can also be enabled for rwlocks, mutexes 1339 and rwsems - in which case all dependencies between these 1340 different locking variants are observed and mapped too, and 1341 the proof of observed correctness is also maintained for an 1342 arbitrary combination of these separate locking variants. 1343 1344 For more details, see Documentation/locking/lockdep-design.rst. 1345 1346config PROVE_RAW_LOCK_NESTING 1347 bool "Enable raw_spinlock - spinlock nesting checks" 1348 depends on PROVE_LOCKING 1349 default n 1350 help 1351 Enable the raw_spinlock vs. spinlock nesting checks which ensure 1352 that the lock nesting rules for PREEMPT_RT enabled kernels are 1353 not violated. 1354 1355 NOTE: There are known nesting problems. So if you enable this 1356 option expect lockdep splats until these problems have been fully 1357 addressed which is work in progress. This config switch allows to 1358 identify and analyze these problems. It will be removed and the 1359 check permanently enabled once the main issues have been fixed. 1360 1361 If unsure, select N. 1362 1363config LOCK_STAT 1364 bool "Lock usage statistics" 1365 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1366 select LOCKDEP 1367 select DEBUG_SPINLOCK 1368 select DEBUG_MUTEXES if !PREEMPT_RT 1369 select DEBUG_RT_MUTEXES if RT_MUTEXES 1370 select DEBUG_LOCK_ALLOC 1371 default n 1372 help 1373 This feature enables tracking lock contention points 1374 1375 For more details, see Documentation/locking/lockstat.rst 1376 1377 This also enables lock events required by "perf lock", 1378 subcommand of perf. 1379 If you want to use "perf lock", you also need to turn on 1380 CONFIG_EVENT_TRACING. 1381 1382 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1383 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1384 1385config DEBUG_RT_MUTEXES 1386 bool "RT Mutex debugging, deadlock detection" 1387 depends on DEBUG_KERNEL && RT_MUTEXES 1388 help 1389 This allows rt mutex semantics violations and rt mutex related 1390 deadlocks (lockups) to be detected and reported automatically. 1391 1392config DEBUG_SPINLOCK 1393 bool "Spinlock and rw-lock debugging: basic checks" 1394 depends on DEBUG_KERNEL 1395 select UNINLINE_SPIN_UNLOCK 1396 help 1397 Say Y here and build SMP to catch missing spinlock initialization 1398 and certain other kinds of spinlock errors commonly made. This is 1399 best used in conjunction with the NMI watchdog so that spinlock 1400 deadlocks are also debuggable. 1401 1402config DEBUG_MUTEXES 1403 bool "Mutex debugging: basic checks" 1404 depends on DEBUG_KERNEL && !PREEMPT_RT 1405 help 1406 This feature allows mutex semantics violations to be detected and 1407 reported. 1408 1409config DEBUG_WW_MUTEX_SLOWPATH 1410 bool "Wait/wound mutex debugging: Slowpath testing" 1411 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1412 select DEBUG_LOCK_ALLOC 1413 select DEBUG_SPINLOCK 1414 select DEBUG_MUTEXES if !PREEMPT_RT 1415 select DEBUG_RT_MUTEXES if PREEMPT_RT 1416 help 1417 This feature enables slowpath testing for w/w mutex users by 1418 injecting additional -EDEADLK wound/backoff cases. Together with 1419 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1420 will test all possible w/w mutex interface abuse with the 1421 exception of simply not acquiring all the required locks. 1422 Note that this feature can introduce significant overhead, so 1423 it really should not be enabled in a production or distro kernel, 1424 even a debug kernel. If you are a driver writer, enable it. If 1425 you are a distro, do not. 1426 1427config DEBUG_RWSEMS 1428 bool "RW Semaphore debugging: basic checks" 1429 depends on DEBUG_KERNEL && !PREEMPT_RT 1430 help 1431 This debugging feature allows mismatched rw semaphore locks 1432 and unlocks to be detected and reported. 1433 1434config DEBUG_LOCK_ALLOC 1435 bool "Lock debugging: detect incorrect freeing of live locks" 1436 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1437 select DEBUG_SPINLOCK 1438 select DEBUG_MUTEXES if !PREEMPT_RT 1439 select DEBUG_RT_MUTEXES if RT_MUTEXES 1440 select LOCKDEP 1441 help 1442 This feature will check whether any held lock (spinlock, rwlock, 1443 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1444 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1445 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1446 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1447 held during task exit. 1448 1449config LOCKDEP 1450 bool 1451 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1452 select STACKTRACE 1453 select KALLSYMS 1454 select KALLSYMS_ALL 1455 1456config LOCKDEP_SMALL 1457 bool 1458 1459config LOCKDEP_BITS 1460 int "Bitsize for MAX_LOCKDEP_ENTRIES" 1461 depends on LOCKDEP && !LOCKDEP_SMALL 1462 range 10 30 1463 default 15 1464 help 1465 Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message. 1466 1467config LOCKDEP_CHAINS_BITS 1468 int "Bitsize for MAX_LOCKDEP_CHAINS" 1469 depends on LOCKDEP && !LOCKDEP_SMALL 1470 range 10 30 1471 default 16 1472 help 1473 Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message. 1474 1475config LOCKDEP_STACK_TRACE_BITS 1476 int "Bitsize for MAX_STACK_TRACE_ENTRIES" 1477 depends on LOCKDEP && !LOCKDEP_SMALL 1478 range 10 30 1479 default 19 1480 help 1481 Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message. 1482 1483config LOCKDEP_STACK_TRACE_HASH_BITS 1484 int "Bitsize for STACK_TRACE_HASH_SIZE" 1485 depends on LOCKDEP && !LOCKDEP_SMALL 1486 range 10 30 1487 default 14 1488 help 1489 Try increasing this value if you need large STACK_TRACE_HASH_SIZE. 1490 1491config LOCKDEP_CIRCULAR_QUEUE_BITS 1492 int "Bitsize for elements in circular_queue struct" 1493 depends on LOCKDEP 1494 range 10 30 1495 default 12 1496 help 1497 Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure. 1498 1499config DEBUG_LOCKDEP 1500 bool "Lock dependency engine debugging" 1501 depends on DEBUG_KERNEL && LOCKDEP 1502 select DEBUG_IRQFLAGS 1503 help 1504 If you say Y here, the lock dependency engine will do 1505 additional runtime checks to debug itself, at the price 1506 of more runtime overhead. 1507 1508config DEBUG_ATOMIC_SLEEP 1509 bool "Sleep inside atomic section checking" 1510 select PREEMPT_COUNT 1511 depends on DEBUG_KERNEL 1512 depends on !ARCH_NO_PREEMPT 1513 help 1514 If you say Y here, various routines which may sleep will become very 1515 noisy if they are called inside atomic sections: when a spinlock is 1516 held, inside an rcu read side critical section, inside preempt disabled 1517 sections, inside an interrupt, etc... 1518 1519config DEBUG_LOCKING_API_SELFTESTS 1520 bool "Locking API boot-time self-tests" 1521 depends on DEBUG_KERNEL 1522 help 1523 Say Y here if you want the kernel to run a short self-test during 1524 bootup. The self-test checks whether common types of locking bugs 1525 are detected by debugging mechanisms or not. (if you disable 1526 lock debugging then those bugs won't be detected of course.) 1527 The following locking APIs are covered: spinlocks, rwlocks, 1528 mutexes and rwsems. 1529 1530config LOCK_TORTURE_TEST 1531 tristate "torture tests for locking" 1532 depends on DEBUG_KERNEL 1533 select TORTURE_TEST 1534 help 1535 This option provides a kernel module that runs torture tests 1536 on kernel locking primitives. The kernel module may be built 1537 after the fact on the running kernel to be tested, if desired. 1538 1539 Say Y here if you want kernel locking-primitive torture tests 1540 to be built into the kernel. 1541 Say M if you want these torture tests to build as a module. 1542 Say N if you are unsure. 1543 1544config WW_MUTEX_SELFTEST 1545 tristate "Wait/wound mutex selftests" 1546 help 1547 This option provides a kernel module that runs tests on the 1548 on the struct ww_mutex locking API. 1549 1550 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1551 with this test harness. 1552 1553 Say M if you want these self tests to build as a module. 1554 Say N if you are unsure. 1555 1556config SCF_TORTURE_TEST 1557 tristate "torture tests for smp_call_function*()" 1558 depends on DEBUG_KERNEL 1559 select TORTURE_TEST 1560 help 1561 This option provides a kernel module that runs torture tests 1562 on the smp_call_function() family of primitives. The kernel 1563 module may be built after the fact on the running kernel to 1564 be tested, if desired. 1565 1566config CSD_LOCK_WAIT_DEBUG 1567 bool "Debugging for csd_lock_wait(), called from smp_call_function*()" 1568 depends on DEBUG_KERNEL 1569 depends on 64BIT 1570 default n 1571 help 1572 This option enables debug prints when CPUs are slow to respond 1573 to the smp_call_function*() IPI wrappers. These debug prints 1574 include the IPI handler function currently executing (if any) 1575 and relevant stack traces. 1576 1577config CSD_LOCK_WAIT_DEBUG_DEFAULT 1578 bool "Default csd_lock_wait() debugging on at boot time" 1579 depends on CSD_LOCK_WAIT_DEBUG 1580 depends on 64BIT 1581 default n 1582 help 1583 This option causes the csdlock_debug= kernel boot parameter to 1584 default to 1 (basic debugging) instead of 0 (no debugging). 1585 1586endmenu # lock debugging 1587 1588config TRACE_IRQFLAGS 1589 depends on TRACE_IRQFLAGS_SUPPORT 1590 bool 1591 help 1592 Enables hooks to interrupt enabling and disabling for 1593 either tracing or lock debugging. 1594 1595config TRACE_IRQFLAGS_NMI 1596 def_bool y 1597 depends on TRACE_IRQFLAGS 1598 depends on TRACE_IRQFLAGS_NMI_SUPPORT 1599 1600config NMI_CHECK_CPU 1601 bool "Debugging for CPUs failing to respond to backtrace requests" 1602 depends on DEBUG_KERNEL 1603 depends on X86 1604 default n 1605 help 1606 Enables debug prints when a CPU fails to respond to a given 1607 backtrace NMI. These prints provide some reasons why a CPU 1608 might legitimately be failing to respond, for example, if it 1609 is offline of if ignore_nmis is set. 1610 1611config DEBUG_IRQFLAGS 1612 bool "Debug IRQ flag manipulation" 1613 help 1614 Enables checks for potentially unsafe enabling or disabling of 1615 interrupts, such as calling raw_local_irq_restore() when interrupts 1616 are enabled. 1617 1618config STACKTRACE 1619 bool "Stack backtrace support" 1620 depends on STACKTRACE_SUPPORT 1621 help 1622 This option causes the kernel to create a /proc/pid/stack for 1623 every process, showing its current stack trace. 1624 It is also used by various kernel debugging features that require 1625 stack trace generation. 1626 1627config WARN_ALL_UNSEEDED_RANDOM 1628 bool "Warn for all uses of unseeded randomness" 1629 default n 1630 help 1631 Some parts of the kernel contain bugs relating to their use of 1632 cryptographically secure random numbers before it's actually possible 1633 to generate those numbers securely. This setting ensures that these 1634 flaws don't go unnoticed, by enabling a message, should this ever 1635 occur. This will allow people with obscure setups to know when things 1636 are going wrong, so that they might contact developers about fixing 1637 it. 1638 1639 Unfortunately, on some models of some architectures getting 1640 a fully seeded CRNG is extremely difficult, and so this can 1641 result in dmesg getting spammed for a surprisingly long 1642 time. This is really bad from a security perspective, and 1643 so architecture maintainers really need to do what they can 1644 to get the CRNG seeded sooner after the system is booted. 1645 However, since users cannot do anything actionable to 1646 address this, by default this option is disabled. 1647 1648 Say Y here if you want to receive warnings for all uses of 1649 unseeded randomness. This will be of use primarily for 1650 those developers interested in improving the security of 1651 Linux kernels running on their architecture (or 1652 subarchitecture). 1653 1654config DEBUG_KOBJECT 1655 bool "kobject debugging" 1656 depends on DEBUG_KERNEL 1657 help 1658 If you say Y here, some extra kobject debugging messages will be sent 1659 to the syslog. 1660 1661config DEBUG_KOBJECT_RELEASE 1662 bool "kobject release debugging" 1663 depends on DEBUG_OBJECTS_TIMERS 1664 help 1665 kobjects are reference counted objects. This means that their 1666 last reference count put is not predictable, and the kobject can 1667 live on past the point at which a driver decides to drop its 1668 initial reference to the kobject gained on allocation. An 1669 example of this would be a struct device which has just been 1670 unregistered. 1671 1672 However, some buggy drivers assume that after such an operation, 1673 the memory backing the kobject can be immediately freed. This 1674 goes completely against the principles of a refcounted object. 1675 1676 If you say Y here, the kernel will delay the release of kobjects 1677 on the last reference count to improve the visibility of this 1678 kind of kobject release bug. 1679 1680config HAVE_DEBUG_BUGVERBOSE 1681 bool 1682 1683menu "Debug kernel data structures" 1684 1685config DEBUG_LIST 1686 bool "Debug linked list manipulation" 1687 depends on DEBUG_KERNEL 1688 select LIST_HARDENED 1689 help 1690 Enable this to turn on extended checks in the linked-list walking 1691 routines. 1692 1693 This option trades better quality error reports for performance, and 1694 is more suitable for kernel debugging. If you care about performance, 1695 you should only enable CONFIG_LIST_HARDENED instead. 1696 1697 If unsure, say N. 1698 1699config DEBUG_PLIST 1700 bool "Debug priority linked list manipulation" 1701 depends on DEBUG_KERNEL 1702 help 1703 Enable this to turn on extended checks in the priority-ordered 1704 linked-list (plist) walking routines. This checks the entire 1705 list multiple times during each manipulation. 1706 1707 If unsure, say N. 1708 1709config DEBUG_SG 1710 bool "Debug SG table operations" 1711 depends on DEBUG_KERNEL 1712 help 1713 Enable this to turn on checks on scatter-gather tables. This can 1714 help find problems with drivers that do not properly initialize 1715 their sg tables. 1716 1717 If unsure, say N. 1718 1719config DEBUG_NOTIFIERS 1720 bool "Debug notifier call chains" 1721 depends on DEBUG_KERNEL 1722 help 1723 Enable this to turn on sanity checking for notifier call chains. 1724 This is most useful for kernel developers to make sure that 1725 modules properly unregister themselves from notifier chains. 1726 This is a relatively cheap check but if you care about maximum 1727 performance, say N. 1728 1729config DEBUG_CLOSURES 1730 bool "Debug closures (bcache async widgits)" 1731 depends on CLOSURES 1732 select DEBUG_FS 1733 help 1734 Keeps all active closures in a linked list and provides a debugfs 1735 interface to list them, which makes it possible to see asynchronous 1736 operations that get stuck. 1737 1738config DEBUG_MAPLE_TREE 1739 bool "Debug maple trees" 1740 depends on DEBUG_KERNEL 1741 help 1742 Enable maple tree debugging information and extra validations. 1743 1744 If unsure, say N. 1745 1746endmenu 1747 1748source "kernel/rcu/Kconfig.debug" 1749 1750config DEBUG_WQ_FORCE_RR_CPU 1751 bool "Force round-robin CPU selection for unbound work items" 1752 depends on DEBUG_KERNEL 1753 default n 1754 help 1755 Workqueue used to implicitly guarantee that work items queued 1756 without explicit CPU specified are put on the local CPU. This 1757 guarantee is no longer true and while local CPU is still 1758 preferred work items may be put on foreign CPUs. Kernel 1759 parameter "workqueue.debug_force_rr_cpu" is added to force 1760 round-robin CPU selection to flush out usages which depend on the 1761 now broken guarantee. This config option enables the debug 1762 feature by default. When enabled, memory and cache locality will 1763 be impacted. 1764 1765config CPU_HOTPLUG_STATE_CONTROL 1766 bool "Enable CPU hotplug state control" 1767 depends on DEBUG_KERNEL 1768 depends on HOTPLUG_CPU 1769 default n 1770 help 1771 Allows to write steps between "offline" and "online" to the CPUs 1772 sysfs target file so states can be stepped granular. This is a debug 1773 option for now as the hotplug machinery cannot be stopped and 1774 restarted at arbitrary points yet. 1775 1776 Say N if your are unsure. 1777 1778config LATENCYTOP 1779 bool "Latency measuring infrastructure" 1780 depends on DEBUG_KERNEL 1781 depends on STACKTRACE_SUPPORT 1782 depends on PROC_FS 1783 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 1784 select KALLSYMS 1785 select KALLSYMS_ALL 1786 select STACKTRACE 1787 select SCHEDSTATS 1788 help 1789 Enable this option if you want to use the LatencyTOP tool 1790 to find out which userspace is blocking on what kernel operations. 1791 1792config DEBUG_CGROUP_REF 1793 bool "Disable inlining of cgroup css reference count functions" 1794 depends on DEBUG_KERNEL 1795 depends on CGROUPS 1796 depends on KPROBES 1797 default n 1798 help 1799 Force cgroup css reference count functions to not be inlined so 1800 that they can be kprobed for debugging. 1801 1802source "kernel/trace/Kconfig" 1803 1804config PROVIDE_OHCI1394_DMA_INIT 1805 bool "Remote debugging over FireWire early on boot" 1806 depends on PCI && X86 1807 help 1808 If you want to debug problems which hang or crash the kernel early 1809 on boot and the crashing machine has a FireWire port, you can use 1810 this feature to remotely access the memory of the crashed machine 1811 over FireWire. This employs remote DMA as part of the OHCI1394 1812 specification which is now the standard for FireWire controllers. 1813 1814 With remote DMA, you can monitor the printk buffer remotely using 1815 firescope and access all memory below 4GB using fireproxy from gdb. 1816 Even controlling a kernel debugger is possible using remote DMA. 1817 1818 Usage: 1819 1820 If ohci1394_dma=early is used as boot parameter, it will initialize 1821 all OHCI1394 controllers which are found in the PCI config space. 1822 1823 As all changes to the FireWire bus such as enabling and disabling 1824 devices cause a bus reset and thereby disable remote DMA for all 1825 devices, be sure to have the cable plugged and FireWire enabled on 1826 the debugging host before booting the debug target for debugging. 1827 1828 This code (~1k) is freed after boot. By then, the firewire stack 1829 in charge of the OHCI-1394 controllers should be used instead. 1830 1831 See Documentation/core-api/debugging-via-ohci1394.rst for more information. 1832 1833source "samples/Kconfig" 1834 1835config ARCH_HAS_DEVMEM_IS_ALLOWED 1836 bool 1837 1838config STRICT_DEVMEM 1839 bool "Filter access to /dev/mem" 1840 depends on MMU && DEVMEM 1841 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED 1842 default y if PPC || X86 || ARM64 1843 help 1844 If this option is disabled, you allow userspace (root) access to all 1845 of memory, including kernel and userspace memory. Accidental 1846 access to this is obviously disastrous, but specific access can 1847 be used by people debugging the kernel. Note that with PAT support 1848 enabled, even in this case there are restrictions on /dev/mem 1849 use due to the cache aliasing requirements. 1850 1851 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 1852 file only allows userspace access to PCI space and the BIOS code and 1853 data regions. This is sufficient for dosemu and X and all common 1854 users of /dev/mem. 1855 1856 If in doubt, say Y. 1857 1858config IO_STRICT_DEVMEM 1859 bool "Filter I/O access to /dev/mem" 1860 depends on STRICT_DEVMEM 1861 help 1862 If this option is disabled, you allow userspace (root) access to all 1863 io-memory regardless of whether a driver is actively using that 1864 range. Accidental access to this is obviously disastrous, but 1865 specific access can be used by people debugging kernel drivers. 1866 1867 If this option is switched on, the /dev/mem file only allows 1868 userspace access to *idle* io-memory ranges (see /proc/iomem) This 1869 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 1870 if the driver using a given range cannot be disabled. 1871 1872 If in doubt, say Y. 1873 1874menu "$(SRCARCH) Debugging" 1875 1876source "arch/$(SRCARCH)/Kconfig.debug" 1877 1878endmenu 1879 1880menu "Kernel Testing and Coverage" 1881 1882source "lib/kunit/Kconfig" 1883 1884config NOTIFIER_ERROR_INJECTION 1885 tristate "Notifier error injection" 1886 depends on DEBUG_KERNEL 1887 select DEBUG_FS 1888 help 1889 This option provides the ability to inject artificial errors to 1890 specified notifier chain callbacks. It is useful to test the error 1891 handling of notifier call chain failures. 1892 1893 Say N if unsure. 1894 1895config PM_NOTIFIER_ERROR_INJECT 1896 tristate "PM notifier error injection module" 1897 depends on PM && NOTIFIER_ERROR_INJECTION 1898 default m if PM_DEBUG 1899 help 1900 This option provides the ability to inject artificial errors to 1901 PM notifier chain callbacks. It is controlled through debugfs 1902 interface /sys/kernel/debug/notifier-error-inject/pm 1903 1904 If the notifier call chain should be failed with some events 1905 notified, write the error code to "actions/<notifier event>/error". 1906 1907 Example: Inject PM suspend error (-12 = -ENOMEM) 1908 1909 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1910 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1911 # echo mem > /sys/power/state 1912 bash: echo: write error: Cannot allocate memory 1913 1914 To compile this code as a module, choose M here: the module will 1915 be called pm-notifier-error-inject. 1916 1917 If unsure, say N. 1918 1919config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1920 tristate "OF reconfig notifier error injection module" 1921 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1922 help 1923 This option provides the ability to inject artificial errors to 1924 OF reconfig notifier chain callbacks. It is controlled 1925 through debugfs interface under 1926 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1927 1928 If the notifier call chain should be failed with some events 1929 notified, write the error code to "actions/<notifier event>/error". 1930 1931 To compile this code as a module, choose M here: the module will 1932 be called of-reconfig-notifier-error-inject. 1933 1934 If unsure, say N. 1935 1936config NETDEV_NOTIFIER_ERROR_INJECT 1937 tristate "Netdev notifier error injection module" 1938 depends on NET && NOTIFIER_ERROR_INJECTION 1939 help 1940 This option provides the ability to inject artificial errors to 1941 netdevice notifier chain callbacks. It is controlled through debugfs 1942 interface /sys/kernel/debug/notifier-error-inject/netdev 1943 1944 If the notifier call chain should be failed with some events 1945 notified, write the error code to "actions/<notifier event>/error". 1946 1947 Example: Inject netdevice mtu change error (-22 = -EINVAL) 1948 1949 # cd /sys/kernel/debug/notifier-error-inject/netdev 1950 # echo -22 > actions/NETDEV_CHANGEMTU/error 1951 # ip link set eth0 mtu 1024 1952 RTNETLINK answers: Invalid argument 1953 1954 To compile this code as a module, choose M here: the module will 1955 be called netdev-notifier-error-inject. 1956 1957 If unsure, say N. 1958 1959config FUNCTION_ERROR_INJECTION 1960 bool "Fault-injections of functions" 1961 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 1962 help 1963 Add fault injections into various functions that are annotated with 1964 ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return 1965 value of these functions. This is useful to test error paths of code. 1966 1967 If unsure, say N 1968 1969config FAULT_INJECTION 1970 bool "Fault-injection framework" 1971 depends on DEBUG_KERNEL 1972 help 1973 Provide fault-injection framework. 1974 For more details, see Documentation/fault-injection/. 1975 1976config FAILSLAB 1977 bool "Fault-injection capability for kmalloc" 1978 depends on FAULT_INJECTION 1979 help 1980 Provide fault-injection capability for kmalloc. 1981 1982config FAIL_PAGE_ALLOC 1983 bool "Fault-injection capability for alloc_pages()" 1984 depends on FAULT_INJECTION 1985 help 1986 Provide fault-injection capability for alloc_pages(). 1987 1988config FAULT_INJECTION_USERCOPY 1989 bool "Fault injection capability for usercopy functions" 1990 depends on FAULT_INJECTION 1991 help 1992 Provides fault-injection capability to inject failures 1993 in usercopy functions (copy_from_user(), get_user(), ...). 1994 1995config FAIL_MAKE_REQUEST 1996 bool "Fault-injection capability for disk IO" 1997 depends on FAULT_INJECTION && BLOCK 1998 help 1999 Provide fault-injection capability for disk IO. 2000 2001config FAIL_IO_TIMEOUT 2002 bool "Fault-injection capability for faking disk interrupts" 2003 depends on FAULT_INJECTION && BLOCK 2004 help 2005 Provide fault-injection capability on end IO handling. This 2006 will make the block layer "forget" an interrupt as configured, 2007 thus exercising the error handling. 2008 2009 Only works with drivers that use the generic timeout handling, 2010 for others it won't do anything. 2011 2012config FAIL_FUTEX 2013 bool "Fault-injection capability for futexes" 2014 select DEBUG_FS 2015 depends on FAULT_INJECTION && FUTEX 2016 help 2017 Provide fault-injection capability for futexes. 2018 2019config FAULT_INJECTION_DEBUG_FS 2020 bool "Debugfs entries for fault-injection capabilities" 2021 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 2022 help 2023 Enable configuration of fault-injection capabilities via debugfs. 2024 2025config FAIL_FUNCTION 2026 bool "Fault-injection capability for functions" 2027 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 2028 help 2029 Provide function-based fault-injection capability. 2030 This will allow you to override a specific function with a return 2031 with given return value. As a result, function caller will see 2032 an error value and have to handle it. This is useful to test the 2033 error handling in various subsystems. 2034 2035config FAIL_MMC_REQUEST 2036 bool "Fault-injection capability for MMC IO" 2037 depends on FAULT_INJECTION_DEBUG_FS && MMC 2038 help 2039 Provide fault-injection capability for MMC IO. 2040 This will make the mmc core return data errors. This is 2041 useful to test the error handling in the mmc block device 2042 and to test how the mmc host driver handles retries from 2043 the block device. 2044 2045config FAIL_SUNRPC 2046 bool "Fault-injection capability for SunRPC" 2047 depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG 2048 help 2049 Provide fault-injection capability for SunRPC and 2050 its consumers. 2051 2052config FAULT_INJECTION_CONFIGFS 2053 bool "Configfs interface for fault-injection capabilities" 2054 depends on FAULT_INJECTION 2055 select CONFIGFS_FS 2056 help 2057 This option allows configfs-based drivers to dynamically configure 2058 fault-injection via configfs. Each parameter for driver-specific 2059 fault-injection can be made visible as a configfs attribute in a 2060 configfs group. 2061 2062 2063config FAULT_INJECTION_STACKTRACE_FILTER 2064 bool "stacktrace filter for fault-injection capabilities" 2065 depends on FAULT_INJECTION 2066 depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT 2067 select STACKTRACE 2068 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 2069 help 2070 Provide stacktrace filter for fault-injection capabilities 2071 2072config ARCH_HAS_KCOV 2073 bool 2074 help 2075 An architecture should select this when it can successfully 2076 build and run with CONFIG_KCOV. This typically requires 2077 disabling instrumentation for some early boot code. 2078 2079config CC_HAS_SANCOV_TRACE_PC 2080 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 2081 2082 2083config KCOV 2084 bool "Code coverage for fuzzing" 2085 depends on ARCH_HAS_KCOV 2086 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 2087 depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \ 2088 GCC_VERSION >= 120000 || CLANG_VERSION >= 130000 2089 select DEBUG_FS 2090 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 2091 select OBJTOOL if HAVE_NOINSTR_HACK 2092 help 2093 KCOV exposes kernel code coverage information in a form suitable 2094 for coverage-guided fuzzing (randomized testing). 2095 2096 For more details, see Documentation/dev-tools/kcov.rst. 2097 2098config KCOV_ENABLE_COMPARISONS 2099 bool "Enable comparison operands collection by KCOV" 2100 depends on KCOV 2101 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 2102 help 2103 KCOV also exposes operands of every comparison in the instrumented 2104 code along with operand sizes and PCs of the comparison instructions. 2105 These operands can be used by fuzzing engines to improve the quality 2106 of fuzzing coverage. 2107 2108config KCOV_INSTRUMENT_ALL 2109 bool "Instrument all code by default" 2110 depends on KCOV 2111 default y 2112 help 2113 If you are doing generic system call fuzzing (like e.g. syzkaller), 2114 then you will want to instrument the whole kernel and you should 2115 say y here. If you are doing more targeted fuzzing (like e.g. 2116 filesystem fuzzing with AFL) then you will want to enable coverage 2117 for more specific subsets of files, and should say n here. 2118 2119config KCOV_IRQ_AREA_SIZE 2120 hex "Size of interrupt coverage collection area in words" 2121 depends on KCOV 2122 default 0x40000 2123 help 2124 KCOV uses preallocated per-cpu areas to collect coverage from 2125 soft interrupts. This specifies the size of those areas in the 2126 number of unsigned long words. 2127 2128menuconfig RUNTIME_TESTING_MENU 2129 bool "Runtime Testing" 2130 def_bool y 2131 2132if RUNTIME_TESTING_MENU 2133 2134config TEST_DHRY 2135 tristate "Dhrystone benchmark test" 2136 help 2137 Enable this to include the Dhrystone 2.1 benchmark. This test 2138 calculates the number of Dhrystones per second, and the number of 2139 DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided 2140 by 1757 (the number of Dhrystones per second obtained on the VAX 2141 11/780, nominally a 1 MIPS machine). 2142 2143 To run the benchmark, it needs to be enabled explicitly, either from 2144 the kernel command line (when built-in), or from userspace (when 2145 built-in or modular. 2146 2147 Run once during kernel boot: 2148 2149 test_dhry.run 2150 2151 Set number of iterations from kernel command line: 2152 2153 test_dhry.iterations=<n> 2154 2155 Set number of iterations from userspace: 2156 2157 echo <n> > /sys/module/test_dhry/parameters/iterations 2158 2159 Trigger manual run from userspace: 2160 2161 echo y > /sys/module/test_dhry/parameters/run 2162 2163 If the number of iterations is <= 0, the test will devise a suitable 2164 number of iterations (test runs for at least 2s) automatically. 2165 This process takes ca. 4s. 2166 2167 If unsure, say N. 2168 2169config LKDTM 2170 tristate "Linux Kernel Dump Test Tool Module" 2171 depends on DEBUG_FS 2172 help 2173 This module enables testing of the different dumping mechanisms by 2174 inducing system failures at predefined crash points. 2175 If you don't need it: say N 2176 Choose M here to compile this code as a module. The module will be 2177 called lkdtm. 2178 2179 Documentation on how to use the module can be found in 2180 Documentation/fault-injection/provoke-crashes.rst 2181 2182config CPUMASK_KUNIT_TEST 2183 tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS 2184 depends on KUNIT 2185 default KUNIT_ALL_TESTS 2186 help 2187 Enable to turn on cpumask tests, running at boot or module load time. 2188 2189 For more information on KUnit and unit tests in general, please refer 2190 to the KUnit documentation in Documentation/dev-tools/kunit/. 2191 2192 If unsure, say N. 2193 2194config TEST_LIST_SORT 2195 tristate "Linked list sorting test" if !KUNIT_ALL_TESTS 2196 depends on KUNIT 2197 default KUNIT_ALL_TESTS 2198 help 2199 Enable this to turn on 'list_sort()' function test. This test is 2200 executed only once during system boot (so affects only boot time), 2201 or at module load time. 2202 2203 If unsure, say N. 2204 2205config TEST_MIN_HEAP 2206 tristate "Min heap test" 2207 depends on DEBUG_KERNEL || m 2208 help 2209 Enable this to turn on min heap function tests. This test is 2210 executed only once during system boot (so affects only boot time), 2211 or at module load time. 2212 2213 If unsure, say N. 2214 2215config TEST_SORT 2216 tristate "Array-based sort test" if !KUNIT_ALL_TESTS 2217 depends on KUNIT 2218 default KUNIT_ALL_TESTS 2219 help 2220 This option enables the self-test function of 'sort()' at boot, 2221 or at module load time. 2222 2223 If unsure, say N. 2224 2225config TEST_DIV64 2226 tristate "64bit/32bit division and modulo test" 2227 depends on DEBUG_KERNEL || m 2228 help 2229 Enable this to turn on 'do_div()' function test. This test is 2230 executed only once during system boot (so affects only boot time), 2231 or at module load time. 2232 2233 If unsure, say N. 2234 2235config TEST_IOV_ITER 2236 tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS 2237 depends on KUNIT 2238 depends on MMU 2239 default KUNIT_ALL_TESTS 2240 help 2241 Enable this to turn on testing of the operation of the I/O iterator 2242 (iov_iter). This test is executed only once during system boot (so 2243 affects only boot time), or at module load time. 2244 2245 If unsure, say N. 2246 2247config KPROBES_SANITY_TEST 2248 tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS 2249 depends on DEBUG_KERNEL 2250 depends on KPROBES 2251 depends on KUNIT 2252 select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 2253 default KUNIT_ALL_TESTS 2254 help 2255 This option provides for testing basic kprobes functionality on 2256 boot. Samples of kprobe and kretprobe are inserted and 2257 verified for functionality. 2258 2259 Say N if you are unsure. 2260 2261config FPROBE_SANITY_TEST 2262 bool "Self test for fprobe" 2263 depends on DEBUG_KERNEL 2264 depends on FPROBE 2265 depends on KUNIT=y 2266 help 2267 This option will enable testing the fprobe when the system boot. 2268 A series of tests are made to verify that the fprobe is functioning 2269 properly. 2270 2271 Say N if you are unsure. 2272 2273config BACKTRACE_SELF_TEST 2274 tristate "Self test for the backtrace code" 2275 depends on DEBUG_KERNEL 2276 help 2277 This option provides a kernel module that can be used to test 2278 the kernel stack backtrace code. This option is not useful 2279 for distributions or general kernels, but only for kernel 2280 developers working on architecture code. 2281 2282 Note that if you want to also test saved backtraces, you will 2283 have to enable STACKTRACE as well. 2284 2285 Say N if you are unsure. 2286 2287config TEST_REF_TRACKER 2288 tristate "Self test for reference tracker" 2289 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT 2290 select REF_TRACKER 2291 help 2292 This option provides a kernel module performing tests 2293 using reference tracker infrastructure. 2294 2295 Say N if you are unsure. 2296 2297config RBTREE_TEST 2298 tristate "Red-Black tree test" 2299 depends on DEBUG_KERNEL 2300 help 2301 A benchmark measuring the performance of the rbtree library. 2302 Also includes rbtree invariant checks. 2303 2304config REED_SOLOMON_TEST 2305 tristate "Reed-Solomon library test" 2306 depends on DEBUG_KERNEL || m 2307 select REED_SOLOMON 2308 select REED_SOLOMON_ENC16 2309 select REED_SOLOMON_DEC16 2310 help 2311 This option enables the self-test function of rslib at boot, 2312 or at module load time. 2313 2314 If unsure, say N. 2315 2316config INTERVAL_TREE_TEST 2317 tristate "Interval tree test" 2318 depends on DEBUG_KERNEL 2319 select INTERVAL_TREE 2320 help 2321 A benchmark measuring the performance of the interval tree library 2322 2323config PERCPU_TEST 2324 tristate "Per cpu operations test" 2325 depends on m && DEBUG_KERNEL 2326 help 2327 Enable this option to build test module which validates per-cpu 2328 operations. 2329 2330 If unsure, say N. 2331 2332config ATOMIC64_SELFTEST 2333 tristate "Perform an atomic64_t self-test" 2334 help 2335 Enable this option to test the atomic64_t functions at boot or 2336 at module load time. 2337 2338 If unsure, say N. 2339 2340config ASYNC_RAID6_TEST 2341 tristate "Self test for hardware accelerated raid6 recovery" 2342 depends on ASYNC_RAID6_RECOV 2343 select ASYNC_MEMCPY 2344 help 2345 This is a one-shot self test that permutes through the 2346 recovery of all the possible two disk failure scenarios for a 2347 N-disk array. Recovery is performed with the asynchronous 2348 raid6 recovery routines, and will optionally use an offload 2349 engine if one is available. 2350 2351 If unsure, say N. 2352 2353config TEST_HEXDUMP 2354 tristate "Test functions located in the hexdump module at runtime" 2355 2356config STRING_KUNIT_TEST 2357 tristate "KUnit test string functions at runtime" if !KUNIT_ALL_TESTS 2358 depends on KUNIT 2359 default KUNIT_ALL_TESTS 2360 2361config STRING_HELPERS_KUNIT_TEST 2362 tristate "KUnit test string helpers at runtime" if !KUNIT_ALL_TESTS 2363 depends on KUNIT 2364 default KUNIT_ALL_TESTS 2365 2366config TEST_KSTRTOX 2367 tristate "Test kstrto*() family of functions at runtime" 2368 2369config TEST_PRINTF 2370 tristate "Test printf() family of functions at runtime" 2371 2372config TEST_SCANF 2373 tristate "Test scanf() family of functions at runtime" 2374 2375config TEST_BITMAP 2376 tristate "Test bitmap_*() family of functions at runtime" 2377 help 2378 Enable this option to test the bitmap functions at boot. 2379 2380 If unsure, say N. 2381 2382config TEST_UUID 2383 tristate "Test functions located in the uuid module at runtime" 2384 2385config TEST_XARRAY 2386 tristate "Test the XArray code at runtime" 2387 2388config TEST_MAPLE_TREE 2389 tristate "Test the Maple Tree code at runtime or module load" 2390 help 2391 Enable this option to test the maple tree code functions at boot, or 2392 when the module is loaded. Enable "Debug Maple Trees" will enable 2393 more verbose output on failures. 2394 2395 If unsure, say N. 2396 2397config TEST_RHASHTABLE 2398 tristate "Perform selftest on resizable hash table" 2399 help 2400 Enable this option to test the rhashtable functions at boot. 2401 2402 If unsure, say N. 2403 2404config TEST_IDA 2405 tristate "Perform selftest on IDA functions" 2406 2407config TEST_PARMAN 2408 tristate "Perform selftest on priority array manager" 2409 depends on PARMAN 2410 help 2411 Enable this option to test priority array manager on boot 2412 (or module load). 2413 2414 If unsure, say N. 2415 2416config TEST_IRQ_TIMINGS 2417 bool "IRQ timings selftest" 2418 depends on IRQ_TIMINGS 2419 help 2420 Enable this option to test the irq timings code on boot. 2421 2422 If unsure, say N. 2423 2424config TEST_LKM 2425 tristate "Test module loading with 'hello world' module" 2426 depends on m 2427 help 2428 This builds the "test_module" module that emits "Hello, world" 2429 on printk when loaded. It is designed to be used for basic 2430 evaluation of the module loading subsystem (for example when 2431 validating module verification). It lacks any extra dependencies, 2432 and will not normally be loaded by the system unless explicitly 2433 requested by name. 2434 2435 If unsure, say N. 2436 2437config TEST_BITOPS 2438 tristate "Test module for compilation of bitops operations" 2439 depends on m 2440 help 2441 This builds the "test_bitops" module that is much like the 2442 TEST_LKM module except that it does a basic exercise of the 2443 set/clear_bit macros and get_count_order/long to make sure there are 2444 no compiler warnings from C=1 sparse checker or -Wextra 2445 compilations. It has no dependencies and doesn't run or load unless 2446 explicitly requested by name. for example: modprobe test_bitops. 2447 2448 If unsure, say N. 2449 2450config TEST_VMALLOC 2451 tristate "Test module for stress/performance analysis of vmalloc allocator" 2452 default n 2453 depends on MMU 2454 depends on m 2455 help 2456 This builds the "test_vmalloc" module that should be used for 2457 stress and performance analysis. So, any new change for vmalloc 2458 subsystem can be evaluated from performance and stability point 2459 of view. 2460 2461 If unsure, say N. 2462 2463config TEST_USER_COPY 2464 tristate "Test user/kernel boundary protections" 2465 depends on m 2466 help 2467 This builds the "test_user_copy" module that runs sanity checks 2468 on the copy_to/from_user infrastructure, making sure basic 2469 user/kernel boundary testing is working. If it fails to load, 2470 a regression has been detected in the user/kernel memory boundary 2471 protections. 2472 2473 If unsure, say N. 2474 2475config TEST_BPF 2476 tristate "Test BPF filter functionality" 2477 depends on m && NET 2478 help 2479 This builds the "test_bpf" module that runs various test vectors 2480 against the BPF interpreter or BPF JIT compiler depending on the 2481 current setting. This is in particular useful for BPF JIT compiler 2482 development, but also to run regression tests against changes in 2483 the interpreter code. It also enables test stubs for eBPF maps and 2484 verifier used by user space verifier testsuite. 2485 2486 If unsure, say N. 2487 2488config TEST_BLACKHOLE_DEV 2489 tristate "Test blackhole netdev functionality" 2490 depends on m && NET 2491 help 2492 This builds the "test_blackhole_dev" module that validates the 2493 data path through this blackhole netdev. 2494 2495 If unsure, say N. 2496 2497config FIND_BIT_BENCHMARK 2498 tristate "Test find_bit functions" 2499 help 2500 This builds the "test_find_bit" module that measure find_*_bit() 2501 functions performance. 2502 2503 If unsure, say N. 2504 2505config TEST_FIRMWARE 2506 tristate "Test firmware loading via userspace interface" 2507 depends on FW_LOADER 2508 help 2509 This builds the "test_firmware" module that creates a userspace 2510 interface for testing firmware loading. This can be used to 2511 control the triggering of firmware loading without needing an 2512 actual firmware-using device. The contents can be rechecked by 2513 userspace. 2514 2515 If unsure, say N. 2516 2517config TEST_SYSCTL 2518 tristate "sysctl test driver" 2519 depends on PROC_SYSCTL 2520 help 2521 This builds the "test_sysctl" module. This driver enables to test the 2522 proc sysctl interfaces available to drivers safely without affecting 2523 production knobs which might alter system functionality. 2524 2525 If unsure, say N. 2526 2527config BITFIELD_KUNIT 2528 tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS 2529 depends on KUNIT 2530 default KUNIT_ALL_TESTS 2531 help 2532 Enable this option to test the bitfield functions at boot. 2533 2534 KUnit tests run during boot and output the results to the debug log 2535 in TAP format (http://testanything.org/). Only useful for kernel devs 2536 running the KUnit test harness, and not intended for inclusion into a 2537 production build. 2538 2539 For more information on KUnit and unit tests in general please refer 2540 to the KUnit documentation in Documentation/dev-tools/kunit/. 2541 2542 If unsure, say N. 2543 2544config CHECKSUM_KUNIT 2545 tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS 2546 depends on KUNIT 2547 default KUNIT_ALL_TESTS 2548 help 2549 Enable this option to test the checksum functions at boot. 2550 2551 KUnit tests run during boot and output the results to the debug log 2552 in TAP format (http://testanything.org/). Only useful for kernel devs 2553 running the KUnit test harness, and not intended for inclusion into a 2554 production build. 2555 2556 For more information on KUnit and unit tests in general please refer 2557 to the KUnit documentation in Documentation/dev-tools/kunit/. 2558 2559 If unsure, say N. 2560 2561config HASH_KUNIT_TEST 2562 tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS 2563 depends on KUNIT 2564 default KUNIT_ALL_TESTS 2565 help 2566 Enable this option to test the kernel's string (<linux/stringhash.h>), and 2567 integer (<linux/hash.h>) hash functions on boot. 2568 2569 KUnit tests run during boot and output the results to the debug log 2570 in TAP format (https://testanything.org/). Only useful for kernel devs 2571 running the KUnit test harness, and not intended for inclusion into a 2572 production build. 2573 2574 For more information on KUnit and unit tests in general please refer 2575 to the KUnit documentation in Documentation/dev-tools/kunit/. 2576 2577 This is intended to help people writing architecture-specific 2578 optimized versions. If unsure, say N. 2579 2580config RESOURCE_KUNIT_TEST 2581 tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS 2582 depends on KUNIT 2583 default KUNIT_ALL_TESTS 2584 help 2585 This builds the resource API unit test. 2586 Tests the logic of API provided by resource.c and ioport.h. 2587 For more information on KUnit and unit tests in general please refer 2588 to the KUnit documentation in Documentation/dev-tools/kunit/. 2589 2590 If unsure, say N. 2591 2592config SYSCTL_KUNIT_TEST 2593 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS 2594 depends on KUNIT 2595 default KUNIT_ALL_TESTS 2596 help 2597 This builds the proc sysctl unit test, which runs on boot. 2598 Tests the API contract and implementation correctness of sysctl. 2599 For more information on KUnit and unit tests in general please refer 2600 to the KUnit documentation in Documentation/dev-tools/kunit/. 2601 2602 If unsure, say N. 2603 2604config LIST_KUNIT_TEST 2605 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS 2606 depends on KUNIT 2607 default KUNIT_ALL_TESTS 2608 help 2609 This builds the linked list KUnit test suite. 2610 It tests that the API and basic functionality of the list_head type 2611 and associated macros. 2612 2613 KUnit tests run during boot and output the results to the debug log 2614 in TAP format (https://testanything.org/). Only useful for kernel devs 2615 running the KUnit test harness, and not intended for inclusion into a 2616 production build. 2617 2618 For more information on KUnit and unit tests in general please refer 2619 to the KUnit documentation in Documentation/dev-tools/kunit/. 2620 2621 If unsure, say N. 2622 2623config HASHTABLE_KUNIT_TEST 2624 tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS 2625 depends on KUNIT 2626 default KUNIT_ALL_TESTS 2627 help 2628 This builds the hashtable KUnit test suite. 2629 It tests the basic functionality of the API defined in 2630 include/linux/hashtable.h. For more information on KUnit and 2631 unit tests in general please refer to the KUnit documentation 2632 in Documentation/dev-tools/kunit/. 2633 2634 If unsure, say N. 2635 2636config LINEAR_RANGES_TEST 2637 tristate "KUnit test for linear_ranges" 2638 depends on KUNIT 2639 select LINEAR_RANGES 2640 help 2641 This builds the linear_ranges unit test, which runs on boot. 2642 Tests the linear_ranges logic correctness. 2643 For more information on KUnit and unit tests in general please refer 2644 to the KUnit documentation in Documentation/dev-tools/kunit/. 2645 2646 If unsure, say N. 2647 2648config CMDLINE_KUNIT_TEST 2649 tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS 2650 depends on KUNIT 2651 default KUNIT_ALL_TESTS 2652 help 2653 This builds the cmdline API unit test. 2654 Tests the logic of API provided by cmdline.c. 2655 For more information on KUnit and unit tests in general please refer 2656 to the KUnit documentation in Documentation/dev-tools/kunit/. 2657 2658 If unsure, say N. 2659 2660config BITS_TEST 2661 tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS 2662 depends on KUNIT 2663 default KUNIT_ALL_TESTS 2664 help 2665 This builds the bits unit test. 2666 Tests the logic of macros defined in bits.h. 2667 For more information on KUnit and unit tests in general please refer 2668 to the KUnit documentation in Documentation/dev-tools/kunit/. 2669 2670 If unsure, say N. 2671 2672config SLUB_KUNIT_TEST 2673 tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS 2674 depends on SLUB_DEBUG && KUNIT 2675 default KUNIT_ALL_TESTS 2676 help 2677 This builds SLUB allocator unit test. 2678 Tests SLUB cache debugging functionality. 2679 For more information on KUnit and unit tests in general please refer 2680 to the KUnit documentation in Documentation/dev-tools/kunit/. 2681 2682 If unsure, say N. 2683 2684config RATIONAL_KUNIT_TEST 2685 tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS 2686 depends on KUNIT && RATIONAL 2687 default KUNIT_ALL_TESTS 2688 help 2689 This builds the rational math unit test. 2690 For more information on KUnit and unit tests in general please refer 2691 to the KUnit documentation in Documentation/dev-tools/kunit/. 2692 2693 If unsure, say N. 2694 2695config MEMCPY_KUNIT_TEST 2696 tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS 2697 depends on KUNIT 2698 default KUNIT_ALL_TESTS 2699 help 2700 Builds unit tests for memcpy(), memmove(), and memset() functions. 2701 For more information on KUnit and unit tests in general please refer 2702 to the KUnit documentation in Documentation/dev-tools/kunit/. 2703 2704 If unsure, say N. 2705 2706config MEMCPY_SLOW_KUNIT_TEST 2707 bool "Include exhaustive memcpy tests" 2708 depends on MEMCPY_KUNIT_TEST 2709 default y 2710 help 2711 Some memcpy tests are quite exhaustive in checking for overlaps 2712 and bit ranges. These can be very slow, so they are split out 2713 as a separate config, in case they need to be disabled. 2714 2715 Note this config option will be replaced by the use of KUnit test 2716 attributes. 2717 2718config IS_SIGNED_TYPE_KUNIT_TEST 2719 tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS 2720 depends on KUNIT 2721 default KUNIT_ALL_TESTS 2722 help 2723 Builds unit tests for the is_signed_type() macro. 2724 2725 For more information on KUnit and unit tests in general please refer 2726 to the KUnit documentation in Documentation/dev-tools/kunit/. 2727 2728 If unsure, say N. 2729 2730config OVERFLOW_KUNIT_TEST 2731 tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS 2732 depends on KUNIT 2733 default KUNIT_ALL_TESTS 2734 help 2735 Builds unit tests for the check_*_overflow(), size_*(), allocation, and 2736 related functions. 2737 2738 For more information on KUnit and unit tests in general please refer 2739 to the KUnit documentation in Documentation/dev-tools/kunit/. 2740 2741 If unsure, say N. 2742 2743config STACKINIT_KUNIT_TEST 2744 tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS 2745 depends on KUNIT 2746 default KUNIT_ALL_TESTS 2747 help 2748 Test if the kernel is zero-initializing stack variables and 2749 padding. Coverage is controlled by compiler flags, 2750 CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO, 2751 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2752 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2753 2754config FORTIFY_KUNIT_TEST 2755 tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS 2756 depends on KUNIT 2757 default KUNIT_ALL_TESTS 2758 help 2759 Builds unit tests for checking internals of FORTIFY_SOURCE as used 2760 by the str*() and mem*() family of functions. For testing runtime 2761 traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests. 2762 2763config HW_BREAKPOINT_KUNIT_TEST 2764 bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS 2765 depends on HAVE_HW_BREAKPOINT 2766 depends on KUNIT=y 2767 default KUNIT_ALL_TESTS 2768 help 2769 Tests for hw_breakpoint constraints accounting. 2770 2771 If unsure, say N. 2772 2773config STRCAT_KUNIT_TEST 2774 tristate "Test strcat() family of functions at runtime" if !KUNIT_ALL_TESTS 2775 depends on KUNIT 2776 default KUNIT_ALL_TESTS 2777 2778config STRSCPY_KUNIT_TEST 2779 tristate "Test strscpy*() family of functions at runtime" if !KUNIT_ALL_TESTS 2780 depends on KUNIT 2781 default KUNIT_ALL_TESTS 2782 2783config SIPHASH_KUNIT_TEST 2784 tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS 2785 depends on KUNIT 2786 default KUNIT_ALL_TESTS 2787 help 2788 Enable this option to test the kernel's siphash (<linux/siphash.h>) hash 2789 functions on boot (or module load). 2790 2791 This is intended to help people writing architecture-specific 2792 optimized versions. If unsure, say N. 2793 2794config TEST_UDELAY 2795 tristate "udelay test driver" 2796 help 2797 This builds the "udelay_test" module that helps to make sure 2798 that udelay() is working properly. 2799 2800 If unsure, say N. 2801 2802config TEST_STATIC_KEYS 2803 tristate "Test static keys" 2804 depends on m 2805 help 2806 Test the static key interfaces. 2807 2808 If unsure, say N. 2809 2810config TEST_DYNAMIC_DEBUG 2811 tristate "Test DYNAMIC_DEBUG" 2812 depends on DYNAMIC_DEBUG 2813 help 2814 This module registers a tracer callback to count enabled 2815 pr_debugs in a 'do_debugging' function, then alters their 2816 enablements, calls the function, and compares counts. 2817 2818 If unsure, say N. 2819 2820config TEST_KMOD 2821 tristate "kmod stress tester" 2822 depends on m 2823 depends on NETDEVICES && NET_CORE && INET # for TUN 2824 depends on BLOCK 2825 depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS 2826 select TEST_LKM 2827 select XFS_FS 2828 select TUN 2829 select BTRFS_FS 2830 help 2831 Test the kernel's module loading mechanism: kmod. kmod implements 2832 support to load modules using the Linux kernel's usermode helper. 2833 This test provides a series of tests against kmod. 2834 2835 Although technically you can either build test_kmod as a module or 2836 into the kernel we disallow building it into the kernel since 2837 it stress tests request_module() and this will very likely cause 2838 some issues by taking over precious threads available from other 2839 module load requests, ultimately this could be fatal. 2840 2841 To run tests run: 2842 2843 tools/testing/selftests/kmod/kmod.sh --help 2844 2845 If unsure, say N. 2846 2847config TEST_DEBUG_VIRTUAL 2848 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 2849 depends on DEBUG_VIRTUAL 2850 help 2851 Test the kernel's ability to detect incorrect calls to 2852 virt_to_phys() done against the non-linear part of the 2853 kernel's virtual address map. 2854 2855 If unsure, say N. 2856 2857config TEST_MEMCAT_P 2858 tristate "Test memcat_p() helper function" 2859 help 2860 Test the memcat_p() helper for correctly merging two 2861 pointer arrays together. 2862 2863 If unsure, say N. 2864 2865config TEST_OBJAGG 2866 tristate "Perform selftest on object aggreration manager" 2867 default n 2868 depends on OBJAGG 2869 help 2870 Enable this option to test object aggregation manager on boot 2871 (or module load). 2872 2873config TEST_MEMINIT 2874 tristate "Test heap/page initialization" 2875 help 2876 Test if the kernel is zero-initializing heap and page allocations. 2877 This can be useful to test init_on_alloc and init_on_free features. 2878 2879 If unsure, say N. 2880 2881config TEST_HMM 2882 tristate "Test HMM (Heterogeneous Memory Management)" 2883 depends on TRANSPARENT_HUGEPAGE 2884 depends on DEVICE_PRIVATE 2885 select HMM_MIRROR 2886 select MMU_NOTIFIER 2887 help 2888 This is a pseudo device driver solely for testing HMM. 2889 Say M here if you want to build the HMM test module. 2890 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests. 2891 2892 If unsure, say N. 2893 2894config TEST_FREE_PAGES 2895 tristate "Test freeing pages" 2896 help 2897 Test that a memory leak does not occur due to a race between 2898 freeing a block of pages and a speculative page reference. 2899 Loading this module is safe if your kernel has the bug fixed. 2900 If the bug is not fixed, it will leak gigabytes of memory and 2901 probably OOM your system. 2902 2903config TEST_FPU 2904 tristate "Test floating point operations in kernel space" 2905 depends on X86 && !KCOV_INSTRUMENT_ALL 2906 help 2907 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu 2908 which will trigger a sequence of floating point operations. This is used 2909 for self-testing floating point control register setting in 2910 kernel_fpu_begin(). 2911 2912 If unsure, say N. 2913 2914config TEST_CLOCKSOURCE_WATCHDOG 2915 tristate "Test clocksource watchdog in kernel space" 2916 depends on CLOCKSOURCE_WATCHDOG 2917 help 2918 Enable this option to create a kernel module that will trigger 2919 a test of the clocksource watchdog. This module may be loaded 2920 via modprobe or insmod in which case it will run upon being 2921 loaded, or it may be built in, in which case it will run 2922 shortly after boot. 2923 2924 If unsure, say N. 2925 2926config TEST_OBJPOOL 2927 tristate "Test module for correctness and stress of objpool" 2928 default n 2929 depends on m && DEBUG_KERNEL 2930 help 2931 This builds the "test_objpool" module that should be used for 2932 correctness verification and concurrent testings of objects 2933 allocation and reclamation. 2934 2935 If unsure, say N. 2936 2937endif # RUNTIME_TESTING_MENU 2938 2939config ARCH_USE_MEMTEST 2940 bool 2941 help 2942 An architecture should select this when it uses early_memtest() 2943 during boot process. 2944 2945config MEMTEST 2946 bool "Memtest" 2947 depends on ARCH_USE_MEMTEST 2948 help 2949 This option adds a kernel parameter 'memtest', which allows memtest 2950 to be set and executed. 2951 memtest=0, mean disabled; -- default 2952 memtest=1, mean do 1 test pattern; 2953 ... 2954 memtest=17, mean do 17 test patterns. 2955 If you are unsure how to answer this question, answer N. 2956 2957 2958 2959config HYPERV_TESTING 2960 bool "Microsoft Hyper-V driver testing" 2961 default n 2962 depends on HYPERV && DEBUG_FS 2963 help 2964 Select this option to enable Hyper-V vmbus testing. 2965 2966endmenu # "Kernel Testing and Coverage" 2967 2968menu "Rust hacking" 2969 2970config RUST_DEBUG_ASSERTIONS 2971 bool "Debug assertions" 2972 depends on RUST 2973 help 2974 Enables rustc's `-Cdebug-assertions` codegen option. 2975 2976 This flag lets you turn `cfg(debug_assertions)` conditional 2977 compilation on or off. This can be used to enable extra debugging 2978 code in development but not in production. For example, it controls 2979 the behavior of the standard library's `debug_assert!` macro. 2980 2981 Note that this will apply to all Rust code, including `core`. 2982 2983 If unsure, say N. 2984 2985config RUST_OVERFLOW_CHECKS 2986 bool "Overflow checks" 2987 default y 2988 depends on RUST 2989 help 2990 Enables rustc's `-Coverflow-checks` codegen option. 2991 2992 This flag allows you to control the behavior of runtime integer 2993 overflow. When overflow-checks are enabled, a Rust panic will occur 2994 on overflow. 2995 2996 Note that this will apply to all Rust code, including `core`. 2997 2998 If unsure, say Y. 2999 3000config RUST_BUILD_ASSERT_ALLOW 3001 bool "Allow unoptimized build-time assertions" 3002 depends on RUST 3003 help 3004 Controls how are `build_error!` and `build_assert!` handled during build. 3005 3006 If calls to them exist in the binary, it may indicate a violated invariant 3007 or that the optimizer failed to verify the invariant during compilation. 3008 3009 This should not happen, thus by default the build is aborted. However, 3010 as an escape hatch, you can choose Y here to ignore them during build 3011 and let the check be carried at runtime (with `panic!` being called if 3012 the check fails). 3013 3014 If unsure, say N. 3015 3016config RUST_KERNEL_DOCTESTS 3017 bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS 3018 depends on RUST && KUNIT=y 3019 default KUNIT_ALL_TESTS 3020 help 3021 This builds the documentation tests of the `kernel` crate 3022 as KUnit tests. 3023 3024 For more information on KUnit and unit tests in general, 3025 please refer to the KUnit documentation in Documentation/dev-tools/kunit/. 3026 3027 If unsure, say N. 3028 3029endmenu # "Rust" 3030 3031endmenu # Kernel hacking 3032