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 is known to generate .{s,u}leb128 with symbol deltas with DWARF5, which 235# some targets may not support: https://sourceware.org/bugzilla/show_bug.cgi?id=27215 236config AS_HAS_NON_CONST_LEB128 237 def_bool $(as-instr,.uleb128 .Lexpr_end4 - .Lexpr_start3\n.Lexpr_start3:\n.Lexpr_end4:) 238 239choice 240 prompt "Debug information" 241 depends on DEBUG_KERNEL 242 help 243 Selecting something other than "None" results in a kernel image 244 that will include debugging info resulting in a larger kernel image. 245 This adds debug symbols to the kernel and modules (gcc -g), and 246 is needed if you intend to use kernel crashdump or binary object 247 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 248 249 Choose which version of DWARF debug info to emit. If unsure, 250 select "Toolchain default". 251 252config DEBUG_INFO_NONE 253 bool "Disable debug information" 254 help 255 Do not build the kernel with debugging information, which will 256 result in a faster and smaller build. 257 258config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT 259 bool "Rely on the toolchain's implicit default DWARF version" 260 select DEBUG_INFO 261 depends on !CC_IS_CLANG || AS_IS_LLVM || CLANG_VERSION < 140000 || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_LEB128) 262 help 263 The implicit default version of DWARF debug info produced by a 264 toolchain changes over time. 265 266 This can break consumers of the debug info that haven't upgraded to 267 support newer revisions, and prevent testing newer versions, but 268 those should be less common scenarios. 269 270config DEBUG_INFO_DWARF4 271 bool "Generate DWARF Version 4 debuginfo" 272 select DEBUG_INFO 273 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502) 274 help 275 Generate DWARF v4 debug info. This requires gcc 4.5+, binutils 2.35.2 276 if using clang without clang's integrated assembler, and gdb 7.0+. 277 278 If you have consumers of DWARF debug info that are not ready for 279 newer revisions of DWARF, you may wish to choose this or have your 280 config select this. 281 282config DEBUG_INFO_DWARF5 283 bool "Generate DWARF Version 5 debuginfo" 284 select DEBUG_INFO 285 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_LEB128) 286 help 287 Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc 288 5.0+ accepts the -gdwarf-5 flag but only had partial support for some 289 draft features until 7.0), and gdb 8.0+. 290 291 Changes to the structure of debug info in Version 5 allow for around 292 15-18% savings in resulting image and debug info section sizes as 293 compared to DWARF Version 4. DWARF Version 5 standardizes previous 294 extensions such as accelerators for symbol indexing and the format 295 for fission (.dwo/.dwp) files. Users may not want to select this 296 config if they rely on tooling that has not yet been updated to 297 support DWARF Version 5. 298 299endchoice # "Debug information" 300 301if DEBUG_INFO 302 303config DEBUG_INFO_REDUCED 304 bool "Reduce debugging information" 305 help 306 If you say Y here gcc is instructed to generate less debugging 307 information for structure types. This means that tools that 308 need full debugging information (like kgdb or systemtap) won't 309 be happy. But if you merely need debugging information to 310 resolve line numbers there is no loss. Advantage is that 311 build directory object sizes shrink dramatically over a full 312 DEBUG_INFO build and compile times are reduced too. 313 Only works with newer gcc versions. 314 315choice 316 prompt "Compressed Debug information" 317 help 318 Compress the resulting debug info. Results in smaller debug info sections, 319 but requires that consumers are able to decompress the results. 320 321 If unsure, choose DEBUG_INFO_COMPRESSED_NONE. 322 323config DEBUG_INFO_COMPRESSED_NONE 324 bool "Don't compress debug information" 325 help 326 Don't compress debug info sections. 327 328config DEBUG_INFO_COMPRESSED_ZLIB 329 bool "Compress debugging information with zlib" 330 depends on $(cc-option,-gz=zlib) 331 depends on $(ld-option,--compress-debug-sections=zlib) 332 help 333 Compress the debug information using zlib. Requires GCC 5.0+ or Clang 334 5.0+, binutils 2.26+, and zlib. 335 336 Users of dpkg-deb via scripts/package/builddeb may find an increase in 337 size of their debug .deb packages with this config set, due to the 338 debug info being compressed with zlib, then the object files being 339 recompressed with a different compression scheme. But this is still 340 preferable to setting $KDEB_COMPRESS to "none" which would be even 341 larger. 342 343config DEBUG_INFO_COMPRESSED_ZSTD 344 bool "Compress debugging information with zstd" 345 depends on $(cc-option,-gz=zstd) 346 depends on $(ld-option,--compress-debug-sections=zstd) 347 help 348 Compress the debug information using zstd. This may provide better 349 compression than zlib, for about the same time costs, but requires newer 350 toolchain support. Requires GCC 13.0+ or Clang 16.0+, binutils 2.40+, and 351 zstd. 352 353endchoice # "Compressed Debug information" 354 355config DEBUG_INFO_SPLIT 356 bool "Produce split debuginfo in .dwo files" 357 depends on $(cc-option,-gsplit-dwarf) 358 # RISC-V linker relaxation + -gsplit-dwarf has issues with LLVM and GCC 359 # prior to 12.x: 360 # https://github.com/llvm/llvm-project/issues/56642 361 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99090 362 depends on !RISCV || GCC_VERSION >= 120000 363 help 364 Generate debug info into separate .dwo files. This significantly 365 reduces the build directory size for builds with DEBUG_INFO, 366 because it stores the information only once on disk in .dwo 367 files instead of multiple times in object files and executables. 368 In addition the debug information is also compressed. 369 370 Requires recent gcc (4.7+) and recent gdb/binutils. 371 Any tool that packages or reads debug information would need 372 to know about the .dwo files and include them. 373 Incompatible with older versions of ccache. 374 375config DEBUG_INFO_BTF 376 bool "Generate BTF typeinfo" 377 depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED 378 depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST 379 depends on BPF_SYSCALL 380 depends on !DEBUG_INFO_DWARF5 || PAHOLE_VERSION >= 121 381 help 382 Generate deduplicated BTF type information from DWARF debug info. 383 Turning this on expects presence of pahole tool, which will convert 384 DWARF type info into equivalent deduplicated BTF type info. 385 386config PAHOLE_HAS_SPLIT_BTF 387 def_bool PAHOLE_VERSION >= 119 388 389config PAHOLE_HAS_BTF_TAG 390 def_bool PAHOLE_VERSION >= 123 391 depends on CC_IS_CLANG 392 help 393 Decide whether pahole emits btf_tag attributes (btf_type_tag and 394 btf_decl_tag) or not. Currently only clang compiler implements 395 these attributes, so make the config depend on CC_IS_CLANG. 396 397config PAHOLE_HAS_LANG_EXCLUDE 398 def_bool PAHOLE_VERSION >= 124 399 help 400 Support for the --lang_exclude flag which makes pahole exclude 401 compilation units from the supplied language. Used in Kbuild to 402 omit Rust CUs which are not supported in version 1.24 of pahole, 403 otherwise it would emit malformed kernel and module binaries when 404 using DEBUG_INFO_BTF_MODULES. 405 406config DEBUG_INFO_BTF_MODULES 407 def_bool y 408 depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF 409 help 410 Generate compact split BTF type information for kernel modules. 411 412config MODULE_ALLOW_BTF_MISMATCH 413 bool "Allow loading modules with non-matching BTF type info" 414 depends on DEBUG_INFO_BTF_MODULES 415 help 416 For modules whose split BTF does not match vmlinux, load without 417 BTF rather than refusing to load. The default behavior with 418 module BTF enabled is to reject modules with such mismatches; 419 this option will still load module BTF where possible but ignore 420 it when a mismatch is found. 421 422config GDB_SCRIPTS 423 bool "Provide GDB scripts for kernel debugging" 424 help 425 This creates the required links to GDB helper scripts in the 426 build directory. If you load vmlinux into gdb, the helper 427 scripts will be automatically imported by gdb as well, and 428 additional functions are available to analyze a Linux kernel 429 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst 430 for further details. 431 432endif # DEBUG_INFO 433 434config FRAME_WARN 435 int "Warn for stack frames larger than" 436 range 0 8192 437 default 0 if KMSAN 438 default 2048 if GCC_PLUGIN_LATENT_ENTROPY 439 default 2048 if PARISC 440 default 1536 if (!64BIT && XTENSA) 441 default 1280 if KASAN && !64BIT 442 default 1024 if !64BIT 443 default 2048 if 64BIT 444 help 445 Tell the compiler to warn at build time for stack frames larger than this. 446 Setting this too low will cause a lot of warnings. 447 Setting it to 0 disables the warning. 448 449config STRIP_ASM_SYMS 450 bool "Strip assembler-generated symbols during link" 451 default n 452 help 453 Strip internal assembler-generated symbols during a link (symbols 454 that look like '.Lxxx') so they don't pollute the output of 455 get_wchan() and suchlike. 456 457config READABLE_ASM 458 bool "Generate readable assembler code" 459 depends on DEBUG_KERNEL 460 depends on CC_IS_GCC 461 help 462 Disable some compiler optimizations that tend to generate human unreadable 463 assembler output. This may make the kernel slightly slower, but it helps 464 to keep kernel developers who have to stare a lot at assembler listings 465 sane. 466 467config HEADERS_INSTALL 468 bool "Install uapi headers to usr/include" 469 depends on !UML 470 help 471 This option will install uapi headers (headers exported to user-space) 472 into the usr/include directory for use during the kernel build. 473 This is unneeded for building the kernel itself, but needed for some 474 user-space program samples. It is also needed by some features such 475 as uapi header sanity checks. 476 477config DEBUG_SECTION_MISMATCH 478 bool "Enable full Section mismatch analysis" 479 depends on CC_IS_GCC 480 help 481 The section mismatch analysis checks if there are illegal 482 references from one section to another section. 483 During linktime or runtime, some sections are dropped; 484 any use of code/data previously in these sections would 485 most likely result in an oops. 486 In the code, functions and variables are annotated with 487 __init,, etc. (see the full list in include/linux/init.h), 488 which results in the code/data being placed in specific sections. 489 The section mismatch analysis is always performed after a full 490 kernel build, and enabling this option causes the following 491 additional step to occur: 492 - Add the option -fno-inline-functions-called-once to gcc commands. 493 When inlining a function annotated with __init in a non-init 494 function, we would lose the section information and thus 495 the analysis would not catch the illegal reference. 496 This option tells gcc to inline less (but it does result in 497 a larger kernel). 498 499config SECTION_MISMATCH_WARN_ONLY 500 bool "Make section mismatch errors non-fatal" 501 default y 502 help 503 If you say N here, the build process will fail if there are any 504 section mismatch, instead of just throwing warnings. 505 506 If unsure, say Y. 507 508config DEBUG_FORCE_FUNCTION_ALIGN_64B 509 bool "Force all function address 64B aligned" 510 depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC || RISCV || S390) 511 select FUNCTION_ALIGNMENT_64B 512 help 513 There are cases that a commit from one domain changes the function 514 address alignment of other domains, and cause magic performance 515 bump (regression or improvement). Enable this option will help to 516 verify if the bump is caused by function alignment changes, while 517 it will slightly increase the kernel size and affect icache usage. 518 519 It is mainly for debug and performance tuning use. 520 521# 522# Select this config option from the architecture Kconfig, if it 523# is preferred to always offer frame pointers as a config 524# option on the architecture (regardless of KERNEL_DEBUG): 525# 526config ARCH_WANT_FRAME_POINTERS 527 bool 528 529config FRAME_POINTER 530 bool "Compile the kernel with frame pointers" 531 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS 532 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 533 help 534 If you say Y here the resulting kernel image will be slightly 535 larger and slower, but it gives very useful debugging information 536 in case of kernel bugs. (precise oopses/stacktraces/warnings) 537 538config OBJTOOL 539 bool 540 541config STACK_VALIDATION 542 bool "Compile-time stack metadata validation" 543 depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER 544 select OBJTOOL 545 default n 546 help 547 Validate frame pointer rules at compile-time. This helps ensure that 548 runtime stack traces are more reliable. 549 550 For more information, see 551 tools/objtool/Documentation/objtool.txt. 552 553config NOINSTR_VALIDATION 554 bool 555 depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY 556 select OBJTOOL 557 default y 558 559config VMLINUX_MAP 560 bool "Generate vmlinux.map file when linking" 561 depends on EXPERT 562 help 563 Selecting this option will pass "-Map=vmlinux.map" to ld 564 when linking vmlinux. That file can be useful for verifying 565 and debugging magic section games, and for seeing which 566 pieces of code get eliminated with 567 CONFIG_LD_DEAD_CODE_DATA_ELIMINATION. 568 569config DEBUG_FORCE_WEAK_PER_CPU 570 bool "Force weak per-cpu definitions" 571 depends on DEBUG_KERNEL 572 help 573 s390 and alpha require percpu variables in modules to be 574 defined weak to work around addressing range issue which 575 puts the following two restrictions on percpu variable 576 definitions. 577 578 1. percpu symbols must be unique whether static or not 579 2. percpu variables can't be defined inside a function 580 581 To ensure that generic code follows the above rules, this 582 option forces all percpu variables to be defined as weak. 583 584endmenu # "Compiler options" 585 586menu "Generic Kernel Debugging Instruments" 587 588config MAGIC_SYSRQ 589 bool "Magic SysRq key" 590 depends on !UML 591 help 592 If you say Y here, you will have some control over the system even 593 if the system crashes for example during kernel debugging (e.g., you 594 will be able to flush the buffer cache to disk, reboot the system 595 immediately or dump some status information). This is accomplished 596 by pressing various keys while holding SysRq (Alt+PrintScreen). It 597 also works on a serial console (on PC hardware at least), if you 598 send a BREAK and then within 5 seconds a command keypress. The 599 keys are documented in <file:Documentation/admin-guide/sysrq.rst>. 600 Don't say Y unless you really know what this hack does. 601 602config MAGIC_SYSRQ_DEFAULT_ENABLE 603 hex "Enable magic SysRq key functions by default" 604 depends on MAGIC_SYSRQ 605 default 0x1 606 help 607 Specifies which SysRq key functions are enabled by default. 608 This may be set to 1 or 0 to enable or disable them all, or 609 to a bitmask as described in Documentation/admin-guide/sysrq.rst. 610 611config MAGIC_SYSRQ_SERIAL 612 bool "Enable magic SysRq key over serial" 613 depends on MAGIC_SYSRQ 614 default y 615 help 616 Many embedded boards have a disconnected TTL level serial which can 617 generate some garbage that can lead to spurious false sysrq detects. 618 This option allows you to decide whether you want to enable the 619 magic SysRq key. 620 621config MAGIC_SYSRQ_SERIAL_SEQUENCE 622 string "Char sequence that enables magic SysRq over serial" 623 depends on MAGIC_SYSRQ_SERIAL 624 default "" 625 help 626 Specifies a sequence of characters that can follow BREAK to enable 627 SysRq on a serial console. 628 629 If unsure, leave an empty string and the option will not be enabled. 630 631config DEBUG_FS 632 bool "Debug Filesystem" 633 help 634 debugfs is a virtual file system that kernel developers use to put 635 debugging files into. Enable this option to be able to read and 636 write to these files. 637 638 For detailed documentation on the debugfs API, see 639 Documentation/filesystems/. 640 641 If unsure, say N. 642 643choice 644 prompt "Debugfs default access" 645 depends on DEBUG_FS 646 default DEBUG_FS_ALLOW_ALL 647 help 648 This selects the default access restrictions for debugfs. 649 It can be overridden with kernel command line option 650 debugfs=[on,no-mount,off]. The restrictions apply for API access 651 and filesystem registration. 652 653config DEBUG_FS_ALLOW_ALL 654 bool "Access normal" 655 help 656 No restrictions apply. Both API and filesystem registration 657 is on. This is the normal default operation. 658 659config DEBUG_FS_DISALLOW_MOUNT 660 bool "Do not register debugfs as filesystem" 661 help 662 The API is open but filesystem is not loaded. Clients can still do 663 their work and read with debug tools that do not need 664 debugfs filesystem. 665 666config DEBUG_FS_ALLOW_NONE 667 bool "No access" 668 help 669 Access is off. Clients get -PERM when trying to create nodes in 670 debugfs tree and debugfs is not registered as a filesystem. 671 Client can then back-off or continue without debugfs access. 672 673endchoice 674 675source "lib/Kconfig.kgdb" 676source "lib/Kconfig.ubsan" 677source "lib/Kconfig.kcsan" 678 679endmenu 680 681menu "Networking Debugging" 682 683source "net/Kconfig.debug" 684 685endmenu # "Networking Debugging" 686 687menu "Memory Debugging" 688 689source "mm/Kconfig.debug" 690 691config DEBUG_OBJECTS 692 bool "Debug object operations" 693 depends on DEBUG_KERNEL 694 help 695 If you say Y here, additional code will be inserted into the 696 kernel to track the life time of various objects and validate 697 the operations on those objects. 698 699config DEBUG_OBJECTS_SELFTEST 700 bool "Debug objects selftest" 701 depends on DEBUG_OBJECTS 702 help 703 This enables the selftest of the object debug code. 704 705config DEBUG_OBJECTS_FREE 706 bool "Debug objects in freed memory" 707 depends on DEBUG_OBJECTS 708 help 709 This enables checks whether a k/v free operation frees an area 710 which contains an object which has not been deactivated 711 properly. This can make kmalloc/kfree-intensive workloads 712 much slower. 713 714config DEBUG_OBJECTS_TIMERS 715 bool "Debug timer objects" 716 depends on DEBUG_OBJECTS 717 help 718 If you say Y here, additional code will be inserted into the 719 timer routines to track the life time of timer objects and 720 validate the timer operations. 721 722config DEBUG_OBJECTS_WORK 723 bool "Debug work objects" 724 depends on DEBUG_OBJECTS 725 help 726 If you say Y here, additional code will be inserted into the 727 work queue routines to track the life time of work objects and 728 validate the work operations. 729 730config DEBUG_OBJECTS_RCU_HEAD 731 bool "Debug RCU callbacks objects" 732 depends on DEBUG_OBJECTS 733 help 734 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 735 736config DEBUG_OBJECTS_PERCPU_COUNTER 737 bool "Debug percpu counter objects" 738 depends on DEBUG_OBJECTS 739 help 740 If you say Y here, additional code will be inserted into the 741 percpu counter routines to track the life time of percpu counter 742 objects and validate the percpu counter operations. 743 744config DEBUG_OBJECTS_ENABLE_DEFAULT 745 int "debug_objects bootup default value (0-1)" 746 range 0 1 747 default "1" 748 depends on DEBUG_OBJECTS 749 help 750 Debug objects boot parameter default value 751 752config SHRINKER_DEBUG 753 bool "Enable shrinker debugging support" 754 depends on DEBUG_FS 755 help 756 Say Y to enable the shrinker debugfs interface which provides 757 visibility into the kernel memory shrinkers subsystem. 758 Disable it to avoid an extra memory footprint. 759 760config DEBUG_STACK_USAGE 761 bool "Stack utilization instrumentation" 762 depends on DEBUG_KERNEL && !IA64 763 help 764 Enables the display of the minimum amount of free stack which each 765 task has ever had available in the sysrq-T and sysrq-P debug output. 766 767 This option will slow down process creation somewhat. 768 769config SCHED_STACK_END_CHECK 770 bool "Detect stack corruption on calls to schedule()" 771 depends on DEBUG_KERNEL 772 default n 773 help 774 This option checks for a stack overrun on calls to schedule(). 775 If the stack end location is found to be over written always panic as 776 the content of the corrupted region can no longer be trusted. 777 This is to ensure no erroneous behaviour occurs which could result in 778 data corruption or a sporadic crash at a later stage once the region 779 is examined. The runtime overhead introduced is minimal. 780 781config ARCH_HAS_DEBUG_VM_PGTABLE 782 bool 783 help 784 An architecture should select this when it can successfully 785 build and run DEBUG_VM_PGTABLE. 786 787config DEBUG_VM_IRQSOFF 788 def_bool DEBUG_VM && !PREEMPT_RT 789 790config DEBUG_VM 791 bool "Debug VM" 792 depends on DEBUG_KERNEL 793 help 794 Enable this to turn on extended checks in the virtual-memory system 795 that may impact performance. 796 797 If unsure, say N. 798 799config DEBUG_VM_SHOOT_LAZIES 800 bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation" 801 depends on DEBUG_VM 802 depends on MMU_LAZY_TLB_SHOOTDOWN 803 help 804 Enable additional IPIs that ensure lazy tlb mm references are removed 805 before the mm is freed. 806 807 If unsure, say N. 808 809config DEBUG_VM_MAPLE_TREE 810 bool "Debug VM maple trees" 811 depends on DEBUG_VM 812 select DEBUG_MAPLE_TREE 813 help 814 Enable VM maple tree debugging information and extra validations. 815 816 If unsure, say N. 817 818config DEBUG_VM_RB 819 bool "Debug VM red-black trees" 820 depends on DEBUG_VM 821 help 822 Enable VM red-black tree debugging information and extra validations. 823 824 If unsure, say N. 825 826config DEBUG_VM_PGFLAGS 827 bool "Debug page-flags operations" 828 depends on DEBUG_VM 829 help 830 Enables extra validation on page flags operations. 831 832 If unsure, say N. 833 834config DEBUG_VM_PGTABLE 835 bool "Debug arch page table for semantics compliance" 836 depends on MMU 837 depends on ARCH_HAS_DEBUG_VM_PGTABLE 838 default y if DEBUG_VM 839 help 840 This option provides a debug method which can be used to test 841 architecture page table helper functions on various platforms in 842 verifying if they comply with expected generic MM semantics. This 843 will help architecture code in making sure that any changes or 844 new additions of these helpers still conform to expected 845 semantics of the generic MM. Platforms will have to opt in for 846 this through ARCH_HAS_DEBUG_VM_PGTABLE. 847 848 If unsure, say N. 849 850config ARCH_HAS_DEBUG_VIRTUAL 851 bool 852 853config DEBUG_VIRTUAL 854 bool "Debug VM translations" 855 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL 856 help 857 Enable some costly sanity checks in virtual to page code. This can 858 catch mistakes with virt_to_page() and friends. 859 860 If unsure, say N. 861 862config DEBUG_NOMMU_REGIONS 863 bool "Debug the global anon/private NOMMU mapping region tree" 864 depends on DEBUG_KERNEL && !MMU 865 help 866 This option causes the global tree of anonymous and private mapping 867 regions to be regularly checked for invalid topology. 868 869config DEBUG_MEMORY_INIT 870 bool "Debug memory initialisation" if EXPERT 871 default !EXPERT 872 help 873 Enable this for additional checks during memory initialisation. 874 The sanity checks verify aspects of the VM such as the memory model 875 and other information provided by the architecture. Verbose 876 information will be printed at KERN_DEBUG loglevel depending 877 on the mminit_loglevel= command-line option. 878 879 If unsure, say Y 880 881config MEMORY_NOTIFIER_ERROR_INJECT 882 tristate "Memory hotplug notifier error injection module" 883 depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION 884 help 885 This option provides the ability to inject artificial errors to 886 memory hotplug notifier chain callbacks. It is controlled through 887 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 888 889 If the notifier call chain should be failed with some events 890 notified, write the error code to "actions/<notifier event>/error". 891 892 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 893 894 # cd /sys/kernel/debug/notifier-error-inject/memory 895 # echo -12 > actions/MEM_GOING_OFFLINE/error 896 # echo offline > /sys/devices/system/memory/memoryXXX/state 897 bash: echo: write error: Cannot allocate memory 898 899 To compile this code as a module, choose M here: the module will 900 be called memory-notifier-error-inject. 901 902 If unsure, say N. 903 904config DEBUG_PER_CPU_MAPS 905 bool "Debug access to per_cpu maps" 906 depends on DEBUG_KERNEL 907 depends on SMP 908 help 909 Say Y to verify that the per_cpu map being accessed has 910 been set up. This adds a fair amount of code to kernel memory 911 and decreases performance. 912 913 Say N if unsure. 914 915config DEBUG_KMAP_LOCAL 916 bool "Debug kmap_local temporary mappings" 917 depends on DEBUG_KERNEL && KMAP_LOCAL 918 help 919 This option enables additional error checking for the kmap_local 920 infrastructure. Disable for production use. 921 922config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 923 bool 924 925config DEBUG_KMAP_LOCAL_FORCE_MAP 926 bool "Enforce kmap_local temporary mappings" 927 depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 928 select KMAP_LOCAL 929 select DEBUG_KMAP_LOCAL 930 help 931 This option enforces temporary mappings through the kmap_local 932 mechanism for non-highmem pages and on non-highmem systems. 933 Disable this for production systems! 934 935config DEBUG_HIGHMEM 936 bool "Highmem debugging" 937 depends on DEBUG_KERNEL && HIGHMEM 938 select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 939 select DEBUG_KMAP_LOCAL 940 help 941 This option enables additional error checking for high memory 942 systems. Disable for production systems. 943 944config HAVE_DEBUG_STACKOVERFLOW 945 bool 946 947config DEBUG_STACKOVERFLOW 948 bool "Check for stack overflows" 949 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 950 help 951 Say Y here if you want to check for overflows of kernel, IRQ 952 and exception stacks (if your architecture uses them). This 953 option will show detailed messages if free stack space drops 954 below a certain limit. 955 956 These kinds of bugs usually occur when call-chains in the 957 kernel get too deep, especially when interrupts are 958 involved. 959 960 Use this in cases where you see apparently random memory 961 corruption, especially if it appears in 'struct thread_info' 962 963 If in doubt, say "N". 964 965source "lib/Kconfig.kasan" 966source "lib/Kconfig.kfence" 967source "lib/Kconfig.kmsan" 968 969endmenu # "Memory Debugging" 970 971config DEBUG_SHIRQ 972 bool "Debug shared IRQ handlers" 973 depends on DEBUG_KERNEL 974 help 975 Enable this to generate a spurious interrupt just before a shared 976 interrupt handler is deregistered (generating one when registering 977 is currently disabled). Drivers need to handle this correctly. Some 978 don't and need to be caught. 979 980menu "Debug Oops, Lockups and Hangs" 981 982config PANIC_ON_OOPS 983 bool "Panic on Oops" 984 help 985 Say Y here to enable the kernel to panic when it oopses. This 986 has the same effect as setting oops=panic on the kernel command 987 line. 988 989 This feature is useful to ensure that the kernel does not do 990 anything erroneous after an oops which could result in data 991 corruption or other issues. 992 993 Say N if unsure. 994 995config PANIC_ON_OOPS_VALUE 996 int 997 range 0 1 998 default 0 if !PANIC_ON_OOPS 999 default 1 if PANIC_ON_OOPS 1000 1001config PANIC_TIMEOUT 1002 int "panic timeout" 1003 default 0 1004 help 1005 Set the timeout value (in seconds) until a reboot occurs when 1006 the kernel panics. If n = 0, then we wait forever. A timeout 1007 value n > 0 will wait n seconds before rebooting, while a timeout 1008 value n < 0 will reboot immediately. 1009 1010config LOCKUP_DETECTOR 1011 bool 1012 1013config SOFTLOCKUP_DETECTOR 1014 bool "Detect Soft Lockups" 1015 depends on DEBUG_KERNEL && !S390 1016 select LOCKUP_DETECTOR 1017 help 1018 Say Y here to enable the kernel to act as a watchdog to detect 1019 soft lockups. 1020 1021 Softlockups are bugs that cause the kernel to loop in kernel 1022 mode for more than 20 seconds, without giving other tasks a 1023 chance to run. The current stack trace is displayed upon 1024 detection and the system will stay locked up. 1025 1026config BOOTPARAM_SOFTLOCKUP_PANIC 1027 bool "Panic (Reboot) On Soft Lockups" 1028 depends on SOFTLOCKUP_DETECTOR 1029 help 1030 Say Y here to enable the kernel to panic on "soft lockups", 1031 which are bugs that cause the kernel to loop in kernel 1032 mode for more than 20 seconds (configurable using the watchdog_thresh 1033 sysctl), without giving other tasks a chance to run. 1034 1035 The panic can be used in combination with panic_timeout, 1036 to cause the system to reboot automatically after a 1037 lockup has been detected. This feature is useful for 1038 high-availability systems that have uptime guarantees and 1039 where a lockup must be resolved ASAP. 1040 1041 Say N if unsure. 1042 1043config HAVE_HARDLOCKUP_DETECTOR_BUDDY 1044 bool 1045 depends on SMP 1046 default y 1047 1048# 1049# Global switch whether to build a hardlockup detector at all. It is available 1050# only when the architecture supports at least one implementation. There are 1051# two exceptions. The hardlockup detector is never enabled on: 1052# 1053# s390: it reported many false positives there 1054# 1055# sparc64: has a custom implementation which is not using the common 1056# hardlockup command line options and sysctl interface. 1057# 1058config HARDLOCKUP_DETECTOR 1059 bool "Detect Hard Lockups" 1060 depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64 1061 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH 1062 imply HARDLOCKUP_DETECTOR_PERF 1063 imply HARDLOCKUP_DETECTOR_BUDDY 1064 imply HARDLOCKUP_DETECTOR_ARCH 1065 select LOCKUP_DETECTOR 1066 1067 help 1068 Say Y here to enable the kernel to act as a watchdog to detect 1069 hard lockups. 1070 1071 Hardlockups are bugs that cause the CPU to loop in kernel mode 1072 for more than 10 seconds, without letting other interrupts have a 1073 chance to run. The current stack trace is displayed upon detection 1074 and the system will stay locked up. 1075 1076# 1077# Note that arch-specific variants are always preferred. 1078# 1079config HARDLOCKUP_DETECTOR_PREFER_BUDDY 1080 bool "Prefer the buddy CPU hardlockup detector" 1081 depends on HARDLOCKUP_DETECTOR 1082 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY 1083 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1084 help 1085 Say Y here to prefer the buddy hardlockup detector over the perf one. 1086 1087 With the buddy detector, each CPU uses its softlockup hrtimer 1088 to check that the next CPU is processing hrtimer interrupts by 1089 verifying that a counter is increasing. 1090 1091 This hardlockup detector is useful on systems that don't have 1092 an arch-specific hardlockup detector or if resources needed 1093 for the hardlockup detector are better used for other things. 1094 1095config HARDLOCKUP_DETECTOR_PERF 1096 bool 1097 depends on HARDLOCKUP_DETECTOR 1098 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY 1099 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1100 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1101 1102config HARDLOCKUP_DETECTOR_BUDDY 1103 bool 1104 depends on HARDLOCKUP_DETECTOR 1105 depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY 1106 depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY 1107 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1108 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1109 1110config HARDLOCKUP_DETECTOR_ARCH 1111 bool 1112 depends on HARDLOCKUP_DETECTOR 1113 depends on HAVE_HARDLOCKUP_DETECTOR_ARCH 1114 help 1115 The arch-specific implementation of the hardlockup detector will 1116 be used. 1117 1118# 1119# Both the "perf" and "buddy" hardlockup detectors count hrtimer 1120# interrupts. This config enables functions managing this common code. 1121# 1122config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1123 bool 1124 select SOFTLOCKUP_DETECTOR 1125 1126# 1127# Enables a timestamp based low pass filter to compensate for perf based 1128# hard lockup detection which runs too fast due to turbo modes. 1129# 1130config HARDLOCKUP_CHECK_TIMESTAMP 1131 bool 1132 1133config BOOTPARAM_HARDLOCKUP_PANIC 1134 bool "Panic (Reboot) On Hard Lockups" 1135 depends on HARDLOCKUP_DETECTOR 1136 help 1137 Say Y here to enable the kernel to panic on "hard lockups", 1138 which are bugs that cause the kernel to loop in kernel 1139 mode with interrupts disabled for more than 10 seconds (configurable 1140 using the watchdog_thresh sysctl). 1141 1142 Say N if unsure. 1143 1144config DETECT_HUNG_TASK 1145 bool "Detect Hung Tasks" 1146 depends on DEBUG_KERNEL 1147 default SOFTLOCKUP_DETECTOR 1148 help 1149 Say Y here to enable the kernel to detect "hung tasks", 1150 which are bugs that cause the task to be stuck in 1151 uninterruptible "D" state indefinitely. 1152 1153 When a hung task is detected, the kernel will print the 1154 current stack trace (which you should report), but the 1155 task will stay in uninterruptible state. If lockdep is 1156 enabled then all held locks will also be reported. This 1157 feature has negligible overhead. 1158 1159config DEFAULT_HUNG_TASK_TIMEOUT 1160 int "Default timeout for hung task detection (in seconds)" 1161 depends on DETECT_HUNG_TASK 1162 default 120 1163 help 1164 This option controls the default timeout (in seconds) used 1165 to determine when a task has become non-responsive and should 1166 be considered hung. 1167 1168 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 1169 sysctl or by writing a value to 1170 /proc/sys/kernel/hung_task_timeout_secs. 1171 1172 A timeout of 0 disables the check. The default is two minutes. 1173 Keeping the default should be fine in most cases. 1174 1175config BOOTPARAM_HUNG_TASK_PANIC 1176 bool "Panic (Reboot) On Hung Tasks" 1177 depends on DETECT_HUNG_TASK 1178 help 1179 Say Y here to enable the kernel to panic on "hung tasks", 1180 which are bugs that cause the kernel to leave a task stuck 1181 in uninterruptible "D" state. 1182 1183 The panic can be used in combination with panic_timeout, 1184 to cause the system to reboot automatically after a 1185 hung task has been detected. This feature is useful for 1186 high-availability systems that have uptime guarantees and 1187 where a hung tasks must be resolved ASAP. 1188 1189 Say N if unsure. 1190 1191config WQ_WATCHDOG 1192 bool "Detect Workqueue Stalls" 1193 depends on DEBUG_KERNEL 1194 help 1195 Say Y here to enable stall detection on workqueues. If a 1196 worker pool doesn't make forward progress on a pending work 1197 item for over a given amount of time, 30s by default, a 1198 warning message is printed along with dump of workqueue 1199 state. This can be configured through kernel parameter 1200 "workqueue.watchdog_thresh" and its sysfs counterpart. 1201 1202config WQ_CPU_INTENSIVE_REPORT 1203 bool "Report per-cpu work items which hog CPU for too long" 1204 depends on DEBUG_KERNEL 1205 help 1206 Say Y here to enable reporting of concurrency-managed per-cpu work 1207 items that hog CPUs for longer than 1208 workqueue.cpu_intensive_thresh_us. Workqueue automatically 1209 detects and excludes them from concurrency management to prevent 1210 them from stalling other per-cpu work items. Occassional 1211 triggering may not necessarily indicate a problem. Repeated 1212 triggering likely indicates that the work item should be switched 1213 to use an unbound workqueue. 1214 1215config TEST_LOCKUP 1216 tristate "Test module to generate lockups" 1217 depends on m 1218 help 1219 This builds the "test_lockup" module that helps to make sure 1220 that watchdogs and lockup detectors are working properly. 1221 1222 Depending on module parameters it could emulate soft or hard 1223 lockup, "hung task", or locking arbitrary lock for a long time. 1224 Also it could generate series of lockups with cooling-down periods. 1225 1226 If unsure, say N. 1227 1228endmenu # "Debug lockups and hangs" 1229 1230menu "Scheduler Debugging" 1231 1232config SCHED_DEBUG 1233 bool "Collect scheduler debugging info" 1234 depends on DEBUG_KERNEL && DEBUG_FS 1235 default y 1236 help 1237 If you say Y here, the /sys/kernel/debug/sched file will be provided 1238 that can help debug the scheduler. The runtime overhead of this 1239 option is minimal. 1240 1241config SCHED_INFO 1242 bool 1243 default n 1244 1245config SCHEDSTATS 1246 bool "Collect scheduler statistics" 1247 depends on DEBUG_KERNEL && PROC_FS 1248 select SCHED_INFO 1249 help 1250 If you say Y here, additional code will be inserted into the 1251 scheduler and related routines to collect statistics about 1252 scheduler behavior and provide them in /proc/schedstat. These 1253 stats may be useful for both tuning and debugging the scheduler 1254 If you aren't debugging the scheduler or trying to tune a specific 1255 application, you can say N to avoid the very slight overhead 1256 this adds. 1257 1258endmenu 1259 1260config DEBUG_TIMEKEEPING 1261 bool "Enable extra timekeeping sanity checking" 1262 help 1263 This option will enable additional timekeeping sanity checks 1264 which may be helpful when diagnosing issues where timekeeping 1265 problems are suspected. 1266 1267 This may include checks in the timekeeping hotpaths, so this 1268 option may have a (very small) performance impact to some 1269 workloads. 1270 1271 If unsure, say N. 1272 1273config DEBUG_PREEMPT 1274 bool "Debug preemptible kernel" 1275 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1276 help 1277 If you say Y here then the kernel will use a debug variant of the 1278 commonly used smp_processor_id() function and will print warnings 1279 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1280 will detect preemption count underflows. 1281 1282 This option has potential to introduce high runtime overhead, 1283 depending on workload as it triggers debugging routines for each 1284 this_cpu operation. It should only be used for debugging purposes. 1285 1286menu "Lock Debugging (spinlocks, mutexes, etc...)" 1287 1288config LOCK_DEBUGGING_SUPPORT 1289 bool 1290 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1291 default y 1292 1293config PROVE_LOCKING 1294 bool "Lock debugging: prove locking correctness" 1295 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1296 select LOCKDEP 1297 select DEBUG_SPINLOCK 1298 select DEBUG_MUTEXES if !PREEMPT_RT 1299 select DEBUG_RT_MUTEXES if RT_MUTEXES 1300 select DEBUG_RWSEMS 1301 select DEBUG_WW_MUTEX_SLOWPATH 1302 select DEBUG_LOCK_ALLOC 1303 select PREEMPT_COUNT if !ARCH_NO_PREEMPT 1304 select TRACE_IRQFLAGS 1305 default n 1306 help 1307 This feature enables the kernel to prove that all locking 1308 that occurs in the kernel runtime is mathematically 1309 correct: that under no circumstance could an arbitrary (and 1310 not yet triggered) combination of observed locking 1311 sequences (on an arbitrary number of CPUs, running an 1312 arbitrary number of tasks and interrupt contexts) cause a 1313 deadlock. 1314 1315 In short, this feature enables the kernel to report locking 1316 related deadlocks before they actually occur. 1317 1318 The proof does not depend on how hard and complex a 1319 deadlock scenario would be to trigger: how many 1320 participant CPUs, tasks and irq-contexts would be needed 1321 for it to trigger. The proof also does not depend on 1322 timing: if a race and a resulting deadlock is possible 1323 theoretically (no matter how unlikely the race scenario 1324 is), it will be proven so and will immediately be 1325 reported by the kernel (once the event is observed that 1326 makes the deadlock theoretically possible). 1327 1328 If a deadlock is impossible (i.e. the locking rules, as 1329 observed by the kernel, are mathematically correct), the 1330 kernel reports nothing. 1331 1332 NOTE: this feature can also be enabled for rwlocks, mutexes 1333 and rwsems - in which case all dependencies between these 1334 different locking variants are observed and mapped too, and 1335 the proof of observed correctness is also maintained for an 1336 arbitrary combination of these separate locking variants. 1337 1338 For more details, see Documentation/locking/lockdep-design.rst. 1339 1340config PROVE_RAW_LOCK_NESTING 1341 bool "Enable raw_spinlock - spinlock nesting checks" 1342 depends on PROVE_LOCKING 1343 default n 1344 help 1345 Enable the raw_spinlock vs. spinlock nesting checks which ensure 1346 that the lock nesting rules for PREEMPT_RT enabled kernels are 1347 not violated. 1348 1349 NOTE: There are known nesting problems. So if you enable this 1350 option expect lockdep splats until these problems have been fully 1351 addressed which is work in progress. This config switch allows to 1352 identify and analyze these problems. It will be removed and the 1353 check permanently enabled once the main issues have been fixed. 1354 1355 If unsure, select N. 1356 1357config LOCK_STAT 1358 bool "Lock usage statistics" 1359 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1360 select LOCKDEP 1361 select DEBUG_SPINLOCK 1362 select DEBUG_MUTEXES if !PREEMPT_RT 1363 select DEBUG_RT_MUTEXES if RT_MUTEXES 1364 select DEBUG_LOCK_ALLOC 1365 default n 1366 help 1367 This feature enables tracking lock contention points 1368 1369 For more details, see Documentation/locking/lockstat.rst 1370 1371 This also enables lock events required by "perf lock", 1372 subcommand of perf. 1373 If you want to use "perf lock", you also need to turn on 1374 CONFIG_EVENT_TRACING. 1375 1376 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1377 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1378 1379config DEBUG_RT_MUTEXES 1380 bool "RT Mutex debugging, deadlock detection" 1381 depends on DEBUG_KERNEL && RT_MUTEXES 1382 help 1383 This allows rt mutex semantics violations and rt mutex related 1384 deadlocks (lockups) to be detected and reported automatically. 1385 1386config DEBUG_SPINLOCK 1387 bool "Spinlock and rw-lock debugging: basic checks" 1388 depends on DEBUG_KERNEL 1389 select UNINLINE_SPIN_UNLOCK 1390 help 1391 Say Y here and build SMP to catch missing spinlock initialization 1392 and certain other kinds of spinlock errors commonly made. This is 1393 best used in conjunction with the NMI watchdog so that spinlock 1394 deadlocks are also debuggable. 1395 1396config DEBUG_MUTEXES 1397 bool "Mutex debugging: basic checks" 1398 depends on DEBUG_KERNEL && !PREEMPT_RT 1399 help 1400 This feature allows mutex semantics violations to be detected and 1401 reported. 1402 1403config DEBUG_WW_MUTEX_SLOWPATH 1404 bool "Wait/wound mutex debugging: Slowpath testing" 1405 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1406 select DEBUG_LOCK_ALLOC 1407 select DEBUG_SPINLOCK 1408 select DEBUG_MUTEXES if !PREEMPT_RT 1409 select DEBUG_RT_MUTEXES if PREEMPT_RT 1410 help 1411 This feature enables slowpath testing for w/w mutex users by 1412 injecting additional -EDEADLK wound/backoff cases. Together with 1413 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1414 will test all possible w/w mutex interface abuse with the 1415 exception of simply not acquiring all the required locks. 1416 Note that this feature can introduce significant overhead, so 1417 it really should not be enabled in a production or distro kernel, 1418 even a debug kernel. If you are a driver writer, enable it. If 1419 you are a distro, do not. 1420 1421config DEBUG_RWSEMS 1422 bool "RW Semaphore debugging: basic checks" 1423 depends on DEBUG_KERNEL 1424 help 1425 This debugging feature allows mismatched rw semaphore locks 1426 and unlocks to be detected and reported. 1427 1428config DEBUG_LOCK_ALLOC 1429 bool "Lock debugging: detect incorrect freeing of live locks" 1430 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1431 select DEBUG_SPINLOCK 1432 select DEBUG_MUTEXES if !PREEMPT_RT 1433 select DEBUG_RT_MUTEXES if RT_MUTEXES 1434 select LOCKDEP 1435 help 1436 This feature will check whether any held lock (spinlock, rwlock, 1437 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1438 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1439 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1440 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1441 held during task exit. 1442 1443config LOCKDEP 1444 bool 1445 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1446 select STACKTRACE 1447 select KALLSYMS 1448 select KALLSYMS_ALL 1449 1450config LOCKDEP_SMALL 1451 bool 1452 1453config LOCKDEP_BITS 1454 int "Bitsize for MAX_LOCKDEP_ENTRIES" 1455 depends on LOCKDEP && !LOCKDEP_SMALL 1456 range 10 30 1457 default 15 1458 help 1459 Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message. 1460 1461config LOCKDEP_CHAINS_BITS 1462 int "Bitsize for MAX_LOCKDEP_CHAINS" 1463 depends on LOCKDEP && !LOCKDEP_SMALL 1464 range 10 30 1465 default 16 1466 help 1467 Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message. 1468 1469config LOCKDEP_STACK_TRACE_BITS 1470 int "Bitsize for MAX_STACK_TRACE_ENTRIES" 1471 depends on LOCKDEP && !LOCKDEP_SMALL 1472 range 10 30 1473 default 19 1474 help 1475 Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message. 1476 1477config LOCKDEP_STACK_TRACE_HASH_BITS 1478 int "Bitsize for STACK_TRACE_HASH_SIZE" 1479 depends on LOCKDEP && !LOCKDEP_SMALL 1480 range 10 30 1481 default 14 1482 help 1483 Try increasing this value if you need large STACK_TRACE_HASH_SIZE. 1484 1485config LOCKDEP_CIRCULAR_QUEUE_BITS 1486 int "Bitsize for elements in circular_queue struct" 1487 depends on LOCKDEP 1488 range 10 30 1489 default 12 1490 help 1491 Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure. 1492 1493config DEBUG_LOCKDEP 1494 bool "Lock dependency engine debugging" 1495 depends on DEBUG_KERNEL && LOCKDEP 1496 select DEBUG_IRQFLAGS 1497 help 1498 If you say Y here, the lock dependency engine will do 1499 additional runtime checks to debug itself, at the price 1500 of more runtime overhead. 1501 1502config DEBUG_ATOMIC_SLEEP 1503 bool "Sleep inside atomic section checking" 1504 select PREEMPT_COUNT 1505 depends on DEBUG_KERNEL 1506 depends on !ARCH_NO_PREEMPT 1507 help 1508 If you say Y here, various routines which may sleep will become very 1509 noisy if they are called inside atomic sections: when a spinlock is 1510 held, inside an rcu read side critical section, inside preempt disabled 1511 sections, inside an interrupt, etc... 1512 1513config DEBUG_LOCKING_API_SELFTESTS 1514 bool "Locking API boot-time self-tests" 1515 depends on DEBUG_KERNEL 1516 help 1517 Say Y here if you want the kernel to run a short self-test during 1518 bootup. The self-test checks whether common types of locking bugs 1519 are detected by debugging mechanisms or not. (if you disable 1520 lock debugging then those bugs won't be detected of course.) 1521 The following locking APIs are covered: spinlocks, rwlocks, 1522 mutexes and rwsems. 1523 1524config LOCK_TORTURE_TEST 1525 tristate "torture tests for locking" 1526 depends on DEBUG_KERNEL 1527 select TORTURE_TEST 1528 help 1529 This option provides a kernel module that runs torture tests 1530 on kernel locking primitives. The kernel module may be built 1531 after the fact on the running kernel to be tested, if desired. 1532 1533 Say Y here if you want kernel locking-primitive torture tests 1534 to be built into the kernel. 1535 Say M if you want these torture tests to build as a module. 1536 Say N if you are unsure. 1537 1538config WW_MUTEX_SELFTEST 1539 tristate "Wait/wound mutex selftests" 1540 help 1541 This option provides a kernel module that runs tests on the 1542 on the struct ww_mutex locking API. 1543 1544 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1545 with this test harness. 1546 1547 Say M if you want these self tests to build as a module. 1548 Say N if you are unsure. 1549 1550config SCF_TORTURE_TEST 1551 tristate "torture tests for smp_call_function*()" 1552 depends on DEBUG_KERNEL 1553 select TORTURE_TEST 1554 help 1555 This option provides a kernel module that runs torture tests 1556 on the smp_call_function() family of primitives. The kernel 1557 module may be built after the fact on the running kernel to 1558 be tested, if desired. 1559 1560config CSD_LOCK_WAIT_DEBUG 1561 bool "Debugging for csd_lock_wait(), called from smp_call_function*()" 1562 depends on DEBUG_KERNEL 1563 depends on 64BIT 1564 default n 1565 help 1566 This option enables debug prints when CPUs are slow to respond 1567 to the smp_call_function*() IPI wrappers. These debug prints 1568 include the IPI handler function currently executing (if any) 1569 and relevant stack traces. 1570 1571config CSD_LOCK_WAIT_DEBUG_DEFAULT 1572 bool "Default csd_lock_wait() debugging on at boot time" 1573 depends on CSD_LOCK_WAIT_DEBUG 1574 depends on 64BIT 1575 default n 1576 help 1577 This option causes the csdlock_debug= kernel boot parameter to 1578 default to 1 (basic debugging) instead of 0 (no debugging). 1579 1580endmenu # lock debugging 1581 1582config TRACE_IRQFLAGS 1583 depends on TRACE_IRQFLAGS_SUPPORT 1584 bool 1585 help 1586 Enables hooks to interrupt enabling and disabling for 1587 either tracing or lock debugging. 1588 1589config TRACE_IRQFLAGS_NMI 1590 def_bool y 1591 depends on TRACE_IRQFLAGS 1592 depends on TRACE_IRQFLAGS_NMI_SUPPORT 1593 1594config NMI_CHECK_CPU 1595 bool "Debugging for CPUs failing to respond to backtrace requests" 1596 depends on DEBUG_KERNEL 1597 depends on X86 1598 default n 1599 help 1600 Enables debug prints when a CPU fails to respond to a given 1601 backtrace NMI. These prints provide some reasons why a CPU 1602 might legitimately be failing to respond, for example, if it 1603 is offline of if ignore_nmis is set. 1604 1605config DEBUG_IRQFLAGS 1606 bool "Debug IRQ flag manipulation" 1607 help 1608 Enables checks for potentially unsafe enabling or disabling of 1609 interrupts, such as calling raw_local_irq_restore() when interrupts 1610 are enabled. 1611 1612config STACKTRACE 1613 bool "Stack backtrace support" 1614 depends on STACKTRACE_SUPPORT 1615 help 1616 This option causes the kernel to create a /proc/pid/stack for 1617 every process, showing its current stack trace. 1618 It is also used by various kernel debugging features that require 1619 stack trace generation. 1620 1621config WARN_ALL_UNSEEDED_RANDOM 1622 bool "Warn for all uses of unseeded randomness" 1623 default n 1624 help 1625 Some parts of the kernel contain bugs relating to their use of 1626 cryptographically secure random numbers before it's actually possible 1627 to generate those numbers securely. This setting ensures that these 1628 flaws don't go unnoticed, by enabling a message, should this ever 1629 occur. This will allow people with obscure setups to know when things 1630 are going wrong, so that they might contact developers about fixing 1631 it. 1632 1633 Unfortunately, on some models of some architectures getting 1634 a fully seeded CRNG is extremely difficult, and so this can 1635 result in dmesg getting spammed for a surprisingly long 1636 time. This is really bad from a security perspective, and 1637 so architecture maintainers really need to do what they can 1638 to get the CRNG seeded sooner after the system is booted. 1639 However, since users cannot do anything actionable to 1640 address this, by default this option is disabled. 1641 1642 Say Y here if you want to receive warnings for all uses of 1643 unseeded randomness. This will be of use primarily for 1644 those developers interested in improving the security of 1645 Linux kernels running on their architecture (or 1646 subarchitecture). 1647 1648config DEBUG_KOBJECT 1649 bool "kobject debugging" 1650 depends on DEBUG_KERNEL 1651 help 1652 If you say Y here, some extra kobject debugging messages will be sent 1653 to the syslog. 1654 1655config DEBUG_KOBJECT_RELEASE 1656 bool "kobject release debugging" 1657 depends on DEBUG_OBJECTS_TIMERS 1658 help 1659 kobjects are reference counted objects. This means that their 1660 last reference count put is not predictable, and the kobject can 1661 live on past the point at which a driver decides to drop its 1662 initial reference to the kobject gained on allocation. An 1663 example of this would be a struct device which has just been 1664 unregistered. 1665 1666 However, some buggy drivers assume that after such an operation, 1667 the memory backing the kobject can be immediately freed. This 1668 goes completely against the principles of a refcounted object. 1669 1670 If you say Y here, the kernel will delay the release of kobjects 1671 on the last reference count to improve the visibility of this 1672 kind of kobject release bug. 1673 1674config HAVE_DEBUG_BUGVERBOSE 1675 bool 1676 1677menu "Debug kernel data structures" 1678 1679config DEBUG_LIST 1680 bool "Debug linked list manipulation" 1681 depends on DEBUG_KERNEL 1682 select LIST_HARDENED 1683 help 1684 Enable this to turn on extended checks in the linked-list walking 1685 routines. 1686 1687 This option trades better quality error reports for performance, and 1688 is more suitable for kernel debugging. If you care about performance, 1689 you should only enable CONFIG_LIST_HARDENED instead. 1690 1691 If unsure, say N. 1692 1693config DEBUG_PLIST 1694 bool "Debug priority linked list manipulation" 1695 depends on DEBUG_KERNEL 1696 help 1697 Enable this to turn on extended checks in the priority-ordered 1698 linked-list (plist) walking routines. This checks the entire 1699 list multiple times during each manipulation. 1700 1701 If unsure, say N. 1702 1703config DEBUG_SG 1704 bool "Debug SG table operations" 1705 depends on DEBUG_KERNEL 1706 help 1707 Enable this to turn on checks on scatter-gather tables. This can 1708 help find problems with drivers that do not properly initialize 1709 their sg tables. 1710 1711 If unsure, say N. 1712 1713config DEBUG_NOTIFIERS 1714 bool "Debug notifier call chains" 1715 depends on DEBUG_KERNEL 1716 help 1717 Enable this to turn on sanity checking for notifier call chains. 1718 This is most useful for kernel developers to make sure that 1719 modules properly unregister themselves from notifier chains. 1720 This is a relatively cheap check but if you care about maximum 1721 performance, say N. 1722 1723config DEBUG_MAPLE_TREE 1724 bool "Debug maple trees" 1725 depends on DEBUG_KERNEL 1726 help 1727 Enable maple tree debugging information and extra validations. 1728 1729 If unsure, say N. 1730 1731endmenu 1732 1733config DEBUG_CREDENTIALS 1734 bool "Debug credential management" 1735 depends on DEBUG_KERNEL 1736 help 1737 Enable this to turn on some debug checking for credential 1738 management. The additional code keeps track of the number of 1739 pointers from task_structs to any given cred struct, and checks to 1740 see that this number never exceeds the usage count of the cred 1741 struct. 1742 1743 Furthermore, if SELinux is enabled, this also checks that the 1744 security pointer in the cred struct is never seen to be invalid. 1745 1746 If unsure, say N. 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 depends on SLAB || SLUB 1980 help 1981 Provide fault-injection capability for kmalloc. 1982 1983config FAIL_PAGE_ALLOC 1984 bool "Fault-injection capability for alloc_pages()" 1985 depends on FAULT_INJECTION 1986 help 1987 Provide fault-injection capability for alloc_pages(). 1988 1989config FAULT_INJECTION_USERCOPY 1990 bool "Fault injection capability for usercopy functions" 1991 depends on FAULT_INJECTION 1992 help 1993 Provides fault-injection capability to inject failures 1994 in usercopy functions (copy_from_user(), get_user(), ...). 1995 1996config FAIL_MAKE_REQUEST 1997 bool "Fault-injection capability for disk IO" 1998 depends on FAULT_INJECTION && BLOCK 1999 help 2000 Provide fault-injection capability for disk IO. 2001 2002config FAIL_IO_TIMEOUT 2003 bool "Fault-injection capability for faking disk interrupts" 2004 depends on FAULT_INJECTION && BLOCK 2005 help 2006 Provide fault-injection capability on end IO handling. This 2007 will make the block layer "forget" an interrupt as configured, 2008 thus exercising the error handling. 2009 2010 Only works with drivers that use the generic timeout handling, 2011 for others it won't do anything. 2012 2013config FAIL_FUTEX 2014 bool "Fault-injection capability for futexes" 2015 select DEBUG_FS 2016 depends on FAULT_INJECTION && FUTEX 2017 help 2018 Provide fault-injection capability for futexes. 2019 2020config FAULT_INJECTION_DEBUG_FS 2021 bool "Debugfs entries for fault-injection capabilities" 2022 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 2023 help 2024 Enable configuration of fault-injection capabilities via debugfs. 2025 2026config FAIL_FUNCTION 2027 bool "Fault-injection capability for functions" 2028 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 2029 help 2030 Provide function-based fault-injection capability. 2031 This will allow you to override a specific function with a return 2032 with given return value. As a result, function caller will see 2033 an error value and have to handle it. This is useful to test the 2034 error handling in various subsystems. 2035 2036config FAIL_MMC_REQUEST 2037 bool "Fault-injection capability for MMC IO" 2038 depends on FAULT_INJECTION_DEBUG_FS && MMC 2039 help 2040 Provide fault-injection capability for MMC IO. 2041 This will make the mmc core return data errors. This is 2042 useful to test the error handling in the mmc block device 2043 and to test how the mmc host driver handles retries from 2044 the block device. 2045 2046config FAIL_SUNRPC 2047 bool "Fault-injection capability for SunRPC" 2048 depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG 2049 help 2050 Provide fault-injection capability for SunRPC and 2051 its consumers. 2052 2053config FAULT_INJECTION_CONFIGFS 2054 bool "Configfs interface for fault-injection capabilities" 2055 depends on FAULT_INJECTION 2056 select CONFIGFS_FS 2057 help 2058 This option allows configfs-based drivers to dynamically configure 2059 fault-injection via configfs. Each parameter for driver-specific 2060 fault-injection can be made visible as a configfs attribute in a 2061 configfs group. 2062 2063 2064config FAULT_INJECTION_STACKTRACE_FILTER 2065 bool "stacktrace filter for fault-injection capabilities" 2066 depends on FAULT_INJECTION 2067 depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT 2068 select STACKTRACE 2069 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 2070 help 2071 Provide stacktrace filter for fault-injection capabilities 2072 2073config ARCH_HAS_KCOV 2074 bool 2075 help 2076 An architecture should select this when it can successfully 2077 build and run with CONFIG_KCOV. This typically requires 2078 disabling instrumentation for some early boot code. 2079 2080config CC_HAS_SANCOV_TRACE_PC 2081 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 2082 2083 2084config KCOV 2085 bool "Code coverage for fuzzing" 2086 depends on ARCH_HAS_KCOV 2087 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 2088 depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \ 2089 GCC_VERSION >= 120000 || CLANG_VERSION >= 130000 2090 select DEBUG_FS 2091 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 2092 select OBJTOOL if HAVE_NOINSTR_HACK 2093 help 2094 KCOV exposes kernel code coverage information in a form suitable 2095 for coverage-guided fuzzing (randomized testing). 2096 2097 If RANDOMIZE_BASE is enabled, PC values will not be stable across 2098 different machines and across reboots. If you need stable PC values, 2099 disable RANDOMIZE_BASE. 2100 2101 For more details, see Documentation/dev-tools/kcov.rst. 2102 2103config KCOV_ENABLE_COMPARISONS 2104 bool "Enable comparison operands collection by KCOV" 2105 depends on KCOV 2106 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 2107 help 2108 KCOV also exposes operands of every comparison in the instrumented 2109 code along with operand sizes and PCs of the comparison instructions. 2110 These operands can be used by fuzzing engines to improve the quality 2111 of fuzzing coverage. 2112 2113config KCOV_INSTRUMENT_ALL 2114 bool "Instrument all code by default" 2115 depends on KCOV 2116 default y 2117 help 2118 If you are doing generic system call fuzzing (like e.g. syzkaller), 2119 then you will want to instrument the whole kernel and you should 2120 say y here. If you are doing more targeted fuzzing (like e.g. 2121 filesystem fuzzing with AFL) then you will want to enable coverage 2122 for more specific subsets of files, and should say n here. 2123 2124config KCOV_IRQ_AREA_SIZE 2125 hex "Size of interrupt coverage collection area in words" 2126 depends on KCOV 2127 default 0x40000 2128 help 2129 KCOV uses preallocated per-cpu areas to collect coverage from 2130 soft interrupts. This specifies the size of those areas in the 2131 number of unsigned long words. 2132 2133menuconfig RUNTIME_TESTING_MENU 2134 bool "Runtime Testing" 2135 def_bool y 2136 2137if RUNTIME_TESTING_MENU 2138 2139config TEST_DHRY 2140 tristate "Dhrystone benchmark test" 2141 help 2142 Enable this to include the Dhrystone 2.1 benchmark. This test 2143 calculates the number of Dhrystones per second, and the number of 2144 DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided 2145 by 1757 (the number of Dhrystones per second obtained on the VAX 2146 11/780, nominally a 1 MIPS machine). 2147 2148 To run the benchmark, it needs to be enabled explicitly, either from 2149 the kernel command line (when built-in), or from userspace (when 2150 built-in or modular. 2151 2152 Run once during kernel boot: 2153 2154 test_dhry.run 2155 2156 Set number of iterations from kernel command line: 2157 2158 test_dhry.iterations=<n> 2159 2160 Set number of iterations from userspace: 2161 2162 echo <n> > /sys/module/test_dhry/parameters/iterations 2163 2164 Trigger manual run from userspace: 2165 2166 echo y > /sys/module/test_dhry/parameters/run 2167 2168 If the number of iterations is <= 0, the test will devise a suitable 2169 number of iterations (test runs for at least 2s) automatically. 2170 This process takes ca. 4s. 2171 2172 If unsure, say N. 2173 2174config LKDTM 2175 tristate "Linux Kernel Dump Test Tool Module" 2176 depends on DEBUG_FS 2177 help 2178 This module enables testing of the different dumping mechanisms by 2179 inducing system failures at predefined crash points. 2180 If you don't need it: say N 2181 Choose M here to compile this code as a module. The module will be 2182 called lkdtm. 2183 2184 Documentation on how to use the module can be found in 2185 Documentation/fault-injection/provoke-crashes.rst 2186 2187config CPUMASK_KUNIT_TEST 2188 tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS 2189 depends on KUNIT 2190 default KUNIT_ALL_TESTS 2191 help 2192 Enable to turn on cpumask tests, running at boot or module load time. 2193 2194 For more information on KUnit and unit tests in general, please refer 2195 to the KUnit documentation in Documentation/dev-tools/kunit/. 2196 2197 If unsure, say N. 2198 2199config TEST_LIST_SORT 2200 tristate "Linked list sorting test" if !KUNIT_ALL_TESTS 2201 depends on KUNIT 2202 default KUNIT_ALL_TESTS 2203 help 2204 Enable this to turn on 'list_sort()' function test. This test is 2205 executed only once during system boot (so affects only boot time), 2206 or at module load time. 2207 2208 If unsure, say N. 2209 2210config TEST_MIN_HEAP 2211 tristate "Min heap test" 2212 depends on DEBUG_KERNEL || m 2213 help 2214 Enable this to turn on min heap function tests. This test is 2215 executed only once during system boot (so affects only boot time), 2216 or at module load time. 2217 2218 If unsure, say N. 2219 2220config TEST_SORT 2221 tristate "Array-based sort test" if !KUNIT_ALL_TESTS 2222 depends on KUNIT 2223 default KUNIT_ALL_TESTS 2224 help 2225 This option enables the self-test function of 'sort()' at boot, 2226 or at module load time. 2227 2228 If unsure, say N. 2229 2230config TEST_DIV64 2231 tristate "64bit/32bit division and modulo test" 2232 depends on DEBUG_KERNEL || m 2233 help 2234 Enable this to turn on 'do_div()' function test. This test is 2235 executed only once during system boot (so affects only boot time), 2236 or at module load time. 2237 2238 If unsure, say N. 2239 2240config TEST_IOV_ITER 2241 tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS 2242 depends on KUNIT 2243 default KUNIT_ALL_TESTS 2244 help 2245 Enable this to turn on testing of the operation of the I/O iterator 2246 (iov_iter). This test is executed only once during system boot (so 2247 affects only boot time), or at module load time. 2248 2249 If unsure, say N. 2250 2251config KPROBES_SANITY_TEST 2252 tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS 2253 depends on DEBUG_KERNEL 2254 depends on KPROBES 2255 depends on KUNIT 2256 select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 2257 default KUNIT_ALL_TESTS 2258 help 2259 This option provides for testing basic kprobes functionality on 2260 boot. Samples of kprobe and kretprobe are inserted and 2261 verified for functionality. 2262 2263 Say N if you are unsure. 2264 2265config FPROBE_SANITY_TEST 2266 bool "Self test for fprobe" 2267 depends on DEBUG_KERNEL 2268 depends on FPROBE 2269 depends on KUNIT=y 2270 help 2271 This option will enable testing the fprobe when the system boot. 2272 A series of tests are made to verify that the fprobe is functioning 2273 properly. 2274 2275 Say N if you are unsure. 2276 2277config BACKTRACE_SELF_TEST 2278 tristate "Self test for the backtrace code" 2279 depends on DEBUG_KERNEL 2280 help 2281 This option provides a kernel module that can be used to test 2282 the kernel stack backtrace code. This option is not useful 2283 for distributions or general kernels, but only for kernel 2284 developers working on architecture code. 2285 2286 Note that if you want to also test saved backtraces, you will 2287 have to enable STACKTRACE as well. 2288 2289 Say N if you are unsure. 2290 2291config TEST_REF_TRACKER 2292 tristate "Self test for reference tracker" 2293 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT 2294 select REF_TRACKER 2295 help 2296 This option provides a kernel module performing tests 2297 using reference tracker infrastructure. 2298 2299 Say N if you are unsure. 2300 2301config RBTREE_TEST 2302 tristate "Red-Black tree test" 2303 depends on DEBUG_KERNEL 2304 help 2305 A benchmark measuring the performance of the rbtree library. 2306 Also includes rbtree invariant checks. 2307 2308config REED_SOLOMON_TEST 2309 tristate "Reed-Solomon library test" 2310 depends on DEBUG_KERNEL || m 2311 select REED_SOLOMON 2312 select REED_SOLOMON_ENC16 2313 select REED_SOLOMON_DEC16 2314 help 2315 This option enables the self-test function of rslib at boot, 2316 or at module load time. 2317 2318 If unsure, say N. 2319 2320config INTERVAL_TREE_TEST 2321 tristate "Interval tree test" 2322 depends on DEBUG_KERNEL 2323 select INTERVAL_TREE 2324 help 2325 A benchmark measuring the performance of the interval tree library 2326 2327config PERCPU_TEST 2328 tristate "Per cpu operations test" 2329 depends on m && DEBUG_KERNEL 2330 help 2331 Enable this option to build test module which validates per-cpu 2332 operations. 2333 2334 If unsure, say N. 2335 2336config ATOMIC64_SELFTEST 2337 tristate "Perform an atomic64_t self-test" 2338 help 2339 Enable this option to test the atomic64_t functions at boot or 2340 at module load time. 2341 2342 If unsure, say N. 2343 2344config ASYNC_RAID6_TEST 2345 tristate "Self test for hardware accelerated raid6 recovery" 2346 depends on ASYNC_RAID6_RECOV 2347 select ASYNC_MEMCPY 2348 help 2349 This is a one-shot self test that permutes through the 2350 recovery of all the possible two disk failure scenarios for a 2351 N-disk array. Recovery is performed with the asynchronous 2352 raid6 recovery routines, and will optionally use an offload 2353 engine if one is available. 2354 2355 If unsure, say N. 2356 2357config TEST_HEXDUMP 2358 tristate "Test functions located in the hexdump module at runtime" 2359 2360config STRING_SELFTEST 2361 tristate "Test string functions at runtime" 2362 2363config TEST_STRING_HELPERS 2364 tristate "Test functions located in the string_helpers module at runtime" 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 && FORTIFY_SOURCE 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_LIVEPATCH 2866 tristate "Test livepatching" 2867 default n 2868 depends on DYNAMIC_DEBUG 2869 depends on LIVEPATCH 2870 depends on m 2871 help 2872 Test kernel livepatching features for correctness. The tests will 2873 load test modules that will be livepatched in various scenarios. 2874 2875 To run all the livepatching tests: 2876 2877 make -C tools/testing/selftests TARGETS=livepatch run_tests 2878 2879 Alternatively, individual tests may be invoked: 2880 2881 tools/testing/selftests/livepatch/test-callbacks.sh 2882 tools/testing/selftests/livepatch/test-livepatch.sh 2883 tools/testing/selftests/livepatch/test-shadow-vars.sh 2884 2885 If unsure, say N. 2886 2887config TEST_OBJAGG 2888 tristate "Perform selftest on object aggreration manager" 2889 default n 2890 depends on OBJAGG 2891 help 2892 Enable this option to test object aggregation manager on boot 2893 (or module load). 2894 2895config TEST_MEMINIT 2896 tristate "Test heap/page initialization" 2897 help 2898 Test if the kernel is zero-initializing heap and page allocations. 2899 This can be useful to test init_on_alloc and init_on_free features. 2900 2901 If unsure, say N. 2902 2903config TEST_HMM 2904 tristate "Test HMM (Heterogeneous Memory Management)" 2905 depends on TRANSPARENT_HUGEPAGE 2906 depends on DEVICE_PRIVATE 2907 select HMM_MIRROR 2908 select MMU_NOTIFIER 2909 help 2910 This is a pseudo device driver solely for testing HMM. 2911 Say M here if you want to build the HMM test module. 2912 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests. 2913 2914 If unsure, say N. 2915 2916config TEST_FREE_PAGES 2917 tristate "Test freeing pages" 2918 help 2919 Test that a memory leak does not occur due to a race between 2920 freeing a block of pages and a speculative page reference. 2921 Loading this module is safe if your kernel has the bug fixed. 2922 If the bug is not fixed, it will leak gigabytes of memory and 2923 probably OOM your system. 2924 2925config TEST_FPU 2926 tristate "Test floating point operations in kernel space" 2927 depends on X86 && !KCOV_INSTRUMENT_ALL 2928 help 2929 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu 2930 which will trigger a sequence of floating point operations. This is used 2931 for self-testing floating point control register setting in 2932 kernel_fpu_begin(). 2933 2934 If unsure, say N. 2935 2936config TEST_CLOCKSOURCE_WATCHDOG 2937 tristate "Test clocksource watchdog in kernel space" 2938 depends on CLOCKSOURCE_WATCHDOG 2939 help 2940 Enable this option to create a kernel module that will trigger 2941 a test of the clocksource watchdog. This module may be loaded 2942 via modprobe or insmod in which case it will run upon being 2943 loaded, or it may be built in, in which case it will run 2944 shortly after boot. 2945 2946 If unsure, say N. 2947 2948endif # RUNTIME_TESTING_MENU 2949 2950config ARCH_USE_MEMTEST 2951 bool 2952 help 2953 An architecture should select this when it uses early_memtest() 2954 during boot process. 2955 2956config MEMTEST 2957 bool "Memtest" 2958 depends on ARCH_USE_MEMTEST 2959 help 2960 This option adds a kernel parameter 'memtest', which allows memtest 2961 to be set and executed. 2962 memtest=0, mean disabled; -- default 2963 memtest=1, mean do 1 test pattern; 2964 ... 2965 memtest=17, mean do 17 test patterns. 2966 If you are unsure how to answer this question, answer N. 2967 2968 2969 2970config HYPERV_TESTING 2971 bool "Microsoft Hyper-V driver testing" 2972 default n 2973 depends on HYPERV && DEBUG_FS 2974 help 2975 Select this option to enable Hyper-V vmbus testing. 2976 2977endmenu # "Kernel Testing and Coverage" 2978 2979menu "Rust hacking" 2980 2981config RUST_DEBUG_ASSERTIONS 2982 bool "Debug assertions" 2983 depends on RUST 2984 help 2985 Enables rustc's `-Cdebug-assertions` codegen option. 2986 2987 This flag lets you turn `cfg(debug_assertions)` conditional 2988 compilation on or off. This can be used to enable extra debugging 2989 code in development but not in production. For example, it controls 2990 the behavior of the standard library's `debug_assert!` macro. 2991 2992 Note that this will apply to all Rust code, including `core`. 2993 2994 If unsure, say N. 2995 2996config RUST_OVERFLOW_CHECKS 2997 bool "Overflow checks" 2998 default y 2999 depends on RUST 3000 help 3001 Enables rustc's `-Coverflow-checks` codegen option. 3002 3003 This flag allows you to control the behavior of runtime integer 3004 overflow. When overflow-checks are enabled, a Rust panic will occur 3005 on overflow. 3006 3007 Note that this will apply to all Rust code, including `core`. 3008 3009 If unsure, say Y. 3010 3011config RUST_BUILD_ASSERT_ALLOW 3012 bool "Allow unoptimized build-time assertions" 3013 depends on RUST 3014 help 3015 Controls how are `build_error!` and `build_assert!` handled during build. 3016 3017 If calls to them exist in the binary, it may indicate a violated invariant 3018 or that the optimizer failed to verify the invariant during compilation. 3019 3020 This should not happen, thus by default the build is aborted. However, 3021 as an escape hatch, you can choose Y here to ignore them during build 3022 and let the check be carried at runtime (with `panic!` being called if 3023 the check fails). 3024 3025 If unsure, say N. 3026 3027config RUST_KERNEL_DOCTESTS 3028 bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS 3029 depends on RUST && KUNIT=y 3030 default KUNIT_ALL_TESTS 3031 help 3032 This builds the documentation tests of the `kernel` crate 3033 as KUnit tests. 3034 3035 For more information on KUnit and unit tests in general, 3036 please refer to the KUnit documentation in Documentation/dev-tools/kunit/. 3037 3038 If unsure, say N. 3039 3040endmenu # "Rust" 3041 3042endmenu # Kernel hacking 3043