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 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 Also emits a message to dmesg when a process exits if that process 767 used more stack space than previously exiting processes. 768 769 This option will slow down process creation somewhat. 770 771config SCHED_STACK_END_CHECK 772 bool "Detect stack corruption on calls to schedule()" 773 depends on DEBUG_KERNEL 774 default n 775 help 776 This option checks for a stack overrun on calls to schedule(). 777 If the stack end location is found to be over written always panic as 778 the content of the corrupted region can no longer be trusted. 779 This is to ensure no erroneous behaviour occurs which could result in 780 data corruption or a sporadic crash at a later stage once the region 781 is examined. The runtime overhead introduced is minimal. 782 783config ARCH_HAS_DEBUG_VM_PGTABLE 784 bool 785 help 786 An architecture should select this when it can successfully 787 build and run DEBUG_VM_PGTABLE. 788 789config DEBUG_VM_IRQSOFF 790 def_bool DEBUG_VM && !PREEMPT_RT 791 792config DEBUG_VM 793 bool "Debug VM" 794 depends on DEBUG_KERNEL 795 help 796 Enable this to turn on extended checks in the virtual-memory system 797 that may impact performance. 798 799 If unsure, say N. 800 801config DEBUG_VM_SHOOT_LAZIES 802 bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation" 803 depends on DEBUG_VM 804 depends on MMU_LAZY_TLB_SHOOTDOWN 805 help 806 Enable additional IPIs that ensure lazy tlb mm references are removed 807 before the mm is freed. 808 809 If unsure, say N. 810 811config DEBUG_VM_MAPLE_TREE 812 bool "Debug VM maple trees" 813 depends on DEBUG_VM 814 select DEBUG_MAPLE_TREE 815 help 816 Enable VM maple tree debugging information and extra validations. 817 818 If unsure, say N. 819 820config DEBUG_VM_RB 821 bool "Debug VM red-black trees" 822 depends on DEBUG_VM 823 help 824 Enable VM red-black tree debugging information and extra validations. 825 826 If unsure, say N. 827 828config DEBUG_VM_PGFLAGS 829 bool "Debug page-flags operations" 830 depends on DEBUG_VM 831 help 832 Enables extra validation on page flags operations. 833 834 If unsure, say N. 835 836config DEBUG_VM_PGTABLE 837 bool "Debug arch page table for semantics compliance" 838 depends on MMU 839 depends on ARCH_HAS_DEBUG_VM_PGTABLE 840 default y if DEBUG_VM 841 help 842 This option provides a debug method which can be used to test 843 architecture page table helper functions on various platforms in 844 verifying if they comply with expected generic MM semantics. This 845 will help architecture code in making sure that any changes or 846 new additions of these helpers still conform to expected 847 semantics of the generic MM. Platforms will have to opt in for 848 this through ARCH_HAS_DEBUG_VM_PGTABLE. 849 850 If unsure, say N. 851 852config ARCH_HAS_DEBUG_VIRTUAL 853 bool 854 855config DEBUG_VIRTUAL 856 bool "Debug VM translations" 857 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL 858 help 859 Enable some costly sanity checks in virtual to page code. This can 860 catch mistakes with virt_to_page() and friends. 861 862 If unsure, say N. 863 864config DEBUG_NOMMU_REGIONS 865 bool "Debug the global anon/private NOMMU mapping region tree" 866 depends on DEBUG_KERNEL && !MMU 867 help 868 This option causes the global tree of anonymous and private mapping 869 regions to be regularly checked for invalid topology. 870 871config DEBUG_MEMORY_INIT 872 bool "Debug memory initialisation" if EXPERT 873 default !EXPERT 874 help 875 Enable this for additional checks during memory initialisation. 876 The sanity checks verify aspects of the VM such as the memory model 877 and other information provided by the architecture. Verbose 878 information will be printed at KERN_DEBUG loglevel depending 879 on the mminit_loglevel= command-line option. 880 881 If unsure, say Y 882 883config MEMORY_NOTIFIER_ERROR_INJECT 884 tristate "Memory hotplug notifier error injection module" 885 depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION 886 help 887 This option provides the ability to inject artificial errors to 888 memory hotplug notifier chain callbacks. It is controlled through 889 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 890 891 If the notifier call chain should be failed with some events 892 notified, write the error code to "actions/<notifier event>/error". 893 894 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 895 896 # cd /sys/kernel/debug/notifier-error-inject/memory 897 # echo -12 > actions/MEM_GOING_OFFLINE/error 898 # echo offline > /sys/devices/system/memory/memoryXXX/state 899 bash: echo: write error: Cannot allocate memory 900 901 To compile this code as a module, choose M here: the module will 902 be called memory-notifier-error-inject. 903 904 If unsure, say N. 905 906config DEBUG_PER_CPU_MAPS 907 bool "Debug access to per_cpu maps" 908 depends on DEBUG_KERNEL 909 depends on SMP 910 help 911 Say Y to verify that the per_cpu map being accessed has 912 been set up. This adds a fair amount of code to kernel memory 913 and decreases performance. 914 915 Say N if unsure. 916 917config DEBUG_KMAP_LOCAL 918 bool "Debug kmap_local temporary mappings" 919 depends on DEBUG_KERNEL && KMAP_LOCAL 920 help 921 This option enables additional error checking for the kmap_local 922 infrastructure. Disable for production use. 923 924config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 925 bool 926 927config DEBUG_KMAP_LOCAL_FORCE_MAP 928 bool "Enforce kmap_local temporary mappings" 929 depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 930 select KMAP_LOCAL 931 select DEBUG_KMAP_LOCAL 932 help 933 This option enforces temporary mappings through the kmap_local 934 mechanism for non-highmem pages and on non-highmem systems. 935 Disable this for production systems! 936 937config DEBUG_HIGHMEM 938 bool "Highmem debugging" 939 depends on DEBUG_KERNEL && HIGHMEM 940 select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 941 select DEBUG_KMAP_LOCAL 942 help 943 This option enables additional error checking for high memory 944 systems. Disable for production systems. 945 946config HAVE_DEBUG_STACKOVERFLOW 947 bool 948 949config DEBUG_STACKOVERFLOW 950 bool "Check for stack overflows" 951 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 952 help 953 Say Y here if you want to check for overflows of kernel, IRQ 954 and exception stacks (if your architecture uses them). This 955 option will show detailed messages if free stack space drops 956 below a certain limit. 957 958 These kinds of bugs usually occur when call-chains in the 959 kernel get too deep, especially when interrupts are 960 involved. 961 962 Use this in cases where you see apparently random memory 963 corruption, especially if it appears in 'struct thread_info' 964 965 If in doubt, say "N". 966 967source "lib/Kconfig.kasan" 968source "lib/Kconfig.kfence" 969source "lib/Kconfig.kmsan" 970 971endmenu # "Memory Debugging" 972 973config DEBUG_SHIRQ 974 bool "Debug shared IRQ handlers" 975 depends on DEBUG_KERNEL 976 help 977 Enable this to generate a spurious interrupt just before a shared 978 interrupt handler is deregistered (generating one when registering 979 is currently disabled). Drivers need to handle this correctly. Some 980 don't and need to be caught. 981 982menu "Debug Oops, Lockups and Hangs" 983 984config PANIC_ON_OOPS 985 bool "Panic on Oops" 986 help 987 Say Y here to enable the kernel to panic when it oopses. This 988 has the same effect as setting oops=panic on the kernel command 989 line. 990 991 This feature is useful to ensure that the kernel does not do 992 anything erroneous after an oops which could result in data 993 corruption or other issues. 994 995 Say N if unsure. 996 997config PANIC_ON_OOPS_VALUE 998 int 999 range 0 1 1000 default 0 if !PANIC_ON_OOPS 1001 default 1 if PANIC_ON_OOPS 1002 1003config PANIC_TIMEOUT 1004 int "panic timeout" 1005 default 0 1006 help 1007 Set the timeout value (in seconds) until a reboot occurs when 1008 the kernel panics. If n = 0, then we wait forever. A timeout 1009 value n > 0 will wait n seconds before rebooting, while a timeout 1010 value n < 0 will reboot immediately. 1011 1012config LOCKUP_DETECTOR 1013 bool 1014 1015config SOFTLOCKUP_DETECTOR 1016 bool "Detect Soft Lockups" 1017 depends on DEBUG_KERNEL && !S390 1018 select LOCKUP_DETECTOR 1019 help 1020 Say Y here to enable the kernel to act as a watchdog to detect 1021 soft lockups. 1022 1023 Softlockups are bugs that cause the kernel to loop in kernel 1024 mode for more than 20 seconds, without giving other tasks a 1025 chance to run. The current stack trace is displayed upon 1026 detection and the system will stay locked up. 1027 1028config BOOTPARAM_SOFTLOCKUP_PANIC 1029 bool "Panic (Reboot) On Soft Lockups" 1030 depends on SOFTLOCKUP_DETECTOR 1031 help 1032 Say Y here to enable the kernel to panic on "soft lockups", 1033 which are bugs that cause the kernel to loop in kernel 1034 mode for more than 20 seconds (configurable using the watchdog_thresh 1035 sysctl), without giving other tasks a chance to run. 1036 1037 The panic can be used in combination with panic_timeout, 1038 to cause the system to reboot automatically after a 1039 lockup has been detected. This feature is useful for 1040 high-availability systems that have uptime guarantees and 1041 where a lockup must be resolved ASAP. 1042 1043 Say N if unsure. 1044 1045config HAVE_HARDLOCKUP_DETECTOR_BUDDY 1046 bool 1047 depends on SMP 1048 default y 1049 1050# 1051# Global switch whether to build a hardlockup detector at all. It is available 1052# only when the architecture supports at least one implementation. There are 1053# two exceptions. The hardlockup detector is never enabled on: 1054# 1055# s390: it reported many false positives there 1056# 1057# sparc64: has a custom implementation which is not using the common 1058# hardlockup command line options and sysctl interface. 1059# 1060config HARDLOCKUP_DETECTOR 1061 bool "Detect Hard Lockups" 1062 depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64 1063 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH 1064 imply HARDLOCKUP_DETECTOR_PERF 1065 imply HARDLOCKUP_DETECTOR_BUDDY 1066 imply HARDLOCKUP_DETECTOR_ARCH 1067 select LOCKUP_DETECTOR 1068 1069 help 1070 Say Y here to enable the kernel to act as a watchdog to detect 1071 hard lockups. 1072 1073 Hardlockups are bugs that cause the CPU to loop in kernel mode 1074 for more than 10 seconds, without letting other interrupts have a 1075 chance to run. The current stack trace is displayed upon detection 1076 and the system will stay locked up. 1077 1078# 1079# Note that arch-specific variants are always preferred. 1080# 1081config HARDLOCKUP_DETECTOR_PREFER_BUDDY 1082 bool "Prefer the buddy CPU hardlockup detector" 1083 depends on HARDLOCKUP_DETECTOR 1084 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY 1085 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1086 help 1087 Say Y here to prefer the buddy hardlockup detector over the perf one. 1088 1089 With the buddy detector, each CPU uses its softlockup hrtimer 1090 to check that the next CPU is processing hrtimer interrupts by 1091 verifying that a counter is increasing. 1092 1093 This hardlockup detector is useful on systems that don't have 1094 an arch-specific hardlockup detector or if resources needed 1095 for the hardlockup detector are better used for other things. 1096 1097config HARDLOCKUP_DETECTOR_PERF 1098 bool 1099 depends on HARDLOCKUP_DETECTOR 1100 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY 1101 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1102 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1103 1104config HARDLOCKUP_DETECTOR_BUDDY 1105 bool 1106 depends on HARDLOCKUP_DETECTOR 1107 depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY 1108 depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY 1109 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1110 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1111 1112config HARDLOCKUP_DETECTOR_ARCH 1113 bool 1114 depends on HARDLOCKUP_DETECTOR 1115 depends on HAVE_HARDLOCKUP_DETECTOR_ARCH 1116 help 1117 The arch-specific implementation of the hardlockup detector will 1118 be used. 1119 1120# 1121# Both the "perf" and "buddy" hardlockup detectors count hrtimer 1122# interrupts. This config enables functions managing this common code. 1123# 1124config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1125 bool 1126 select SOFTLOCKUP_DETECTOR 1127 1128# 1129# Enables a timestamp based low pass filter to compensate for perf based 1130# hard lockup detection which runs too fast due to turbo modes. 1131# 1132config HARDLOCKUP_CHECK_TIMESTAMP 1133 bool 1134 1135config BOOTPARAM_HARDLOCKUP_PANIC 1136 bool "Panic (Reboot) On Hard Lockups" 1137 depends on HARDLOCKUP_DETECTOR 1138 help 1139 Say Y here to enable the kernel to panic on "hard lockups", 1140 which are bugs that cause the kernel to loop in kernel 1141 mode with interrupts disabled for more than 10 seconds (configurable 1142 using the watchdog_thresh sysctl). 1143 1144 Say N if unsure. 1145 1146config DETECT_HUNG_TASK 1147 bool "Detect Hung Tasks" 1148 depends on DEBUG_KERNEL 1149 default SOFTLOCKUP_DETECTOR 1150 help 1151 Say Y here to enable the kernel to detect "hung tasks", 1152 which are bugs that cause the task to be stuck in 1153 uninterruptible "D" state indefinitely. 1154 1155 When a hung task is detected, the kernel will print the 1156 current stack trace (which you should report), but the 1157 task will stay in uninterruptible state. If lockdep is 1158 enabled then all held locks will also be reported. This 1159 feature has negligible overhead. 1160 1161config DEFAULT_HUNG_TASK_TIMEOUT 1162 int "Default timeout for hung task detection (in seconds)" 1163 depends on DETECT_HUNG_TASK 1164 default 120 1165 help 1166 This option controls the default timeout (in seconds) used 1167 to determine when a task has become non-responsive and should 1168 be considered hung. 1169 1170 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 1171 sysctl or by writing a value to 1172 /proc/sys/kernel/hung_task_timeout_secs. 1173 1174 A timeout of 0 disables the check. The default is two minutes. 1175 Keeping the default should be fine in most cases. 1176 1177config BOOTPARAM_HUNG_TASK_PANIC 1178 bool "Panic (Reboot) On Hung Tasks" 1179 depends on DETECT_HUNG_TASK 1180 help 1181 Say Y here to enable the kernel to panic on "hung tasks", 1182 which are bugs that cause the kernel to leave a task stuck 1183 in uninterruptible "D" state. 1184 1185 The panic can be used in combination with panic_timeout, 1186 to cause the system to reboot automatically after a 1187 hung task has been detected. This feature is useful for 1188 high-availability systems that have uptime guarantees and 1189 where a hung tasks must be resolved ASAP. 1190 1191 Say N if unsure. 1192 1193config WQ_WATCHDOG 1194 bool "Detect Workqueue Stalls" 1195 depends on DEBUG_KERNEL 1196 help 1197 Say Y here to enable stall detection on workqueues. If a 1198 worker pool doesn't make forward progress on a pending work 1199 item for over a given amount of time, 30s by default, a 1200 warning message is printed along with dump of workqueue 1201 state. This can be configured through kernel parameter 1202 "workqueue.watchdog_thresh" and its sysfs counterpart. 1203 1204config WQ_CPU_INTENSIVE_REPORT 1205 bool "Report per-cpu work items which hog CPU for too long" 1206 depends on DEBUG_KERNEL 1207 help 1208 Say Y here to enable reporting of concurrency-managed per-cpu work 1209 items that hog CPUs for longer than 1210 workqueue.cpu_intensive_thresh_us. Workqueue automatically 1211 detects and excludes them from concurrency management to prevent 1212 them from stalling other per-cpu work items. Occassional 1213 triggering may not necessarily indicate a problem. Repeated 1214 triggering likely indicates that the work item should be switched 1215 to use an unbound workqueue. 1216 1217config TEST_LOCKUP 1218 tristate "Test module to generate lockups" 1219 depends on m 1220 help 1221 This builds the "test_lockup" module that helps to make sure 1222 that watchdogs and lockup detectors are working properly. 1223 1224 Depending on module parameters it could emulate soft or hard 1225 lockup, "hung task", or locking arbitrary lock for a long time. 1226 Also it could generate series of lockups with cooling-down periods. 1227 1228 If unsure, say N. 1229 1230endmenu # "Debug lockups and hangs" 1231 1232menu "Scheduler Debugging" 1233 1234config SCHED_DEBUG 1235 bool "Collect scheduler debugging info" 1236 depends on DEBUG_KERNEL && DEBUG_FS 1237 default y 1238 help 1239 If you say Y here, the /sys/kernel/debug/sched file will be provided 1240 that can help debug the scheduler. The runtime overhead of this 1241 option is minimal. 1242 1243config SCHED_INFO 1244 bool 1245 default n 1246 1247config SCHEDSTATS 1248 bool "Collect scheduler statistics" 1249 depends on DEBUG_KERNEL && PROC_FS 1250 select SCHED_INFO 1251 help 1252 If you say Y here, additional code will be inserted into the 1253 scheduler and related routines to collect statistics about 1254 scheduler behavior and provide them in /proc/schedstat. These 1255 stats may be useful for both tuning and debugging the scheduler 1256 If you aren't debugging the scheduler or trying to tune a specific 1257 application, you can say N to avoid the very slight overhead 1258 this adds. 1259 1260endmenu 1261 1262config DEBUG_TIMEKEEPING 1263 bool "Enable extra timekeeping sanity checking" 1264 help 1265 This option will enable additional timekeeping sanity checks 1266 which may be helpful when diagnosing issues where timekeeping 1267 problems are suspected. 1268 1269 This may include checks in the timekeeping hotpaths, so this 1270 option may have a (very small) performance impact to some 1271 workloads. 1272 1273 If unsure, say N. 1274 1275config DEBUG_PREEMPT 1276 bool "Debug preemptible kernel" 1277 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1278 help 1279 If you say Y here then the kernel will use a debug variant of the 1280 commonly used smp_processor_id() function and will print warnings 1281 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1282 will detect preemption count underflows. 1283 1284 This option has potential to introduce high runtime overhead, 1285 depending on workload as it triggers debugging routines for each 1286 this_cpu operation. It should only be used for debugging purposes. 1287 1288menu "Lock Debugging (spinlocks, mutexes, etc...)" 1289 1290config LOCK_DEBUGGING_SUPPORT 1291 bool 1292 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1293 default y 1294 1295config PROVE_LOCKING 1296 bool "Lock debugging: prove locking correctness" 1297 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1298 select LOCKDEP 1299 select DEBUG_SPINLOCK 1300 select DEBUG_MUTEXES if !PREEMPT_RT 1301 select DEBUG_RT_MUTEXES if RT_MUTEXES 1302 select DEBUG_RWSEMS 1303 select DEBUG_WW_MUTEX_SLOWPATH 1304 select DEBUG_LOCK_ALLOC 1305 select PREEMPT_COUNT if !ARCH_NO_PREEMPT 1306 select TRACE_IRQFLAGS 1307 default n 1308 help 1309 This feature enables the kernel to prove that all locking 1310 that occurs in the kernel runtime is mathematically 1311 correct: that under no circumstance could an arbitrary (and 1312 not yet triggered) combination of observed locking 1313 sequences (on an arbitrary number of CPUs, running an 1314 arbitrary number of tasks and interrupt contexts) cause a 1315 deadlock. 1316 1317 In short, this feature enables the kernel to report locking 1318 related deadlocks before they actually occur. 1319 1320 The proof does not depend on how hard and complex a 1321 deadlock scenario would be to trigger: how many 1322 participant CPUs, tasks and irq-contexts would be needed 1323 for it to trigger. The proof also does not depend on 1324 timing: if a race and a resulting deadlock is possible 1325 theoretically (no matter how unlikely the race scenario 1326 is), it will be proven so and will immediately be 1327 reported by the kernel (once the event is observed that 1328 makes the deadlock theoretically possible). 1329 1330 If a deadlock is impossible (i.e. the locking rules, as 1331 observed by the kernel, are mathematically correct), the 1332 kernel reports nothing. 1333 1334 NOTE: this feature can also be enabled for rwlocks, mutexes 1335 and rwsems - in which case all dependencies between these 1336 different locking variants are observed and mapped too, and 1337 the proof of observed correctness is also maintained for an 1338 arbitrary combination of these separate locking variants. 1339 1340 For more details, see Documentation/locking/lockdep-design.rst. 1341 1342config PROVE_RAW_LOCK_NESTING 1343 bool "Enable raw_spinlock - spinlock nesting checks" 1344 depends on PROVE_LOCKING 1345 default n 1346 help 1347 Enable the raw_spinlock vs. spinlock nesting checks which ensure 1348 that the lock nesting rules for PREEMPT_RT enabled kernels are 1349 not violated. 1350 1351 NOTE: There are known nesting problems. So if you enable this 1352 option expect lockdep splats until these problems have been fully 1353 addressed which is work in progress. This config switch allows to 1354 identify and analyze these problems. It will be removed and the 1355 check permanently enabled once the main issues have been fixed. 1356 1357 If unsure, select N. 1358 1359config LOCK_STAT 1360 bool "Lock usage statistics" 1361 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1362 select LOCKDEP 1363 select DEBUG_SPINLOCK 1364 select DEBUG_MUTEXES if !PREEMPT_RT 1365 select DEBUG_RT_MUTEXES if RT_MUTEXES 1366 select DEBUG_LOCK_ALLOC 1367 default n 1368 help 1369 This feature enables tracking lock contention points 1370 1371 For more details, see Documentation/locking/lockstat.rst 1372 1373 This also enables lock events required by "perf lock", 1374 subcommand of perf. 1375 If you want to use "perf lock", you also need to turn on 1376 CONFIG_EVENT_TRACING. 1377 1378 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1379 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1380 1381config DEBUG_RT_MUTEXES 1382 bool "RT Mutex debugging, deadlock detection" 1383 depends on DEBUG_KERNEL && RT_MUTEXES 1384 help 1385 This allows rt mutex semantics violations and rt mutex related 1386 deadlocks (lockups) to be detected and reported automatically. 1387 1388config DEBUG_SPINLOCK 1389 bool "Spinlock and rw-lock debugging: basic checks" 1390 depends on DEBUG_KERNEL 1391 select UNINLINE_SPIN_UNLOCK 1392 help 1393 Say Y here and build SMP to catch missing spinlock initialization 1394 and certain other kinds of spinlock errors commonly made. This is 1395 best used in conjunction with the NMI watchdog so that spinlock 1396 deadlocks are also debuggable. 1397 1398config DEBUG_MUTEXES 1399 bool "Mutex debugging: basic checks" 1400 depends on DEBUG_KERNEL && !PREEMPT_RT 1401 help 1402 This feature allows mutex semantics violations to be detected and 1403 reported. 1404 1405config DEBUG_WW_MUTEX_SLOWPATH 1406 bool "Wait/wound mutex debugging: Slowpath testing" 1407 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1408 select DEBUG_LOCK_ALLOC 1409 select DEBUG_SPINLOCK 1410 select DEBUG_MUTEXES if !PREEMPT_RT 1411 select DEBUG_RT_MUTEXES if PREEMPT_RT 1412 help 1413 This feature enables slowpath testing for w/w mutex users by 1414 injecting additional -EDEADLK wound/backoff cases. Together with 1415 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1416 will test all possible w/w mutex interface abuse with the 1417 exception of simply not acquiring all the required locks. 1418 Note that this feature can introduce significant overhead, so 1419 it really should not be enabled in a production or distro kernel, 1420 even a debug kernel. If you are a driver writer, enable it. If 1421 you are a distro, do not. 1422 1423config DEBUG_RWSEMS 1424 bool "RW Semaphore debugging: basic checks" 1425 depends on DEBUG_KERNEL 1426 help 1427 This debugging feature allows mismatched rw semaphore locks 1428 and unlocks to be detected and reported. 1429 1430config DEBUG_LOCK_ALLOC 1431 bool "Lock debugging: detect incorrect freeing of live locks" 1432 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1433 select DEBUG_SPINLOCK 1434 select DEBUG_MUTEXES if !PREEMPT_RT 1435 select DEBUG_RT_MUTEXES if RT_MUTEXES 1436 select LOCKDEP 1437 help 1438 This feature will check whether any held lock (spinlock, rwlock, 1439 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1440 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1441 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1442 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1443 held during task exit. 1444 1445config LOCKDEP 1446 bool 1447 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1448 select STACKTRACE 1449 select KALLSYMS 1450 select KALLSYMS_ALL 1451 1452config LOCKDEP_SMALL 1453 bool 1454 1455config LOCKDEP_BITS 1456 int "Bitsize for MAX_LOCKDEP_ENTRIES" 1457 depends on LOCKDEP && !LOCKDEP_SMALL 1458 range 10 30 1459 default 15 1460 help 1461 Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message. 1462 1463config LOCKDEP_CHAINS_BITS 1464 int "Bitsize for MAX_LOCKDEP_CHAINS" 1465 depends on LOCKDEP && !LOCKDEP_SMALL 1466 range 10 30 1467 default 16 1468 help 1469 Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message. 1470 1471config LOCKDEP_STACK_TRACE_BITS 1472 int "Bitsize for MAX_STACK_TRACE_ENTRIES" 1473 depends on LOCKDEP && !LOCKDEP_SMALL 1474 range 10 30 1475 default 19 1476 help 1477 Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message. 1478 1479config LOCKDEP_STACK_TRACE_HASH_BITS 1480 int "Bitsize for STACK_TRACE_HASH_SIZE" 1481 depends on LOCKDEP && !LOCKDEP_SMALL 1482 range 10 30 1483 default 14 1484 help 1485 Try increasing this value if you need large STACK_TRACE_HASH_SIZE. 1486 1487config LOCKDEP_CIRCULAR_QUEUE_BITS 1488 int "Bitsize for elements in circular_queue struct" 1489 depends on LOCKDEP 1490 range 10 30 1491 default 12 1492 help 1493 Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure. 1494 1495config DEBUG_LOCKDEP 1496 bool "Lock dependency engine debugging" 1497 depends on DEBUG_KERNEL && LOCKDEP 1498 select DEBUG_IRQFLAGS 1499 help 1500 If you say Y here, the lock dependency engine will do 1501 additional runtime checks to debug itself, at the price 1502 of more runtime overhead. 1503 1504config DEBUG_ATOMIC_SLEEP 1505 bool "Sleep inside atomic section checking" 1506 select PREEMPT_COUNT 1507 depends on DEBUG_KERNEL 1508 depends on !ARCH_NO_PREEMPT 1509 help 1510 If you say Y here, various routines which may sleep will become very 1511 noisy if they are called inside atomic sections: when a spinlock is 1512 held, inside an rcu read side critical section, inside preempt disabled 1513 sections, inside an interrupt, etc... 1514 1515config DEBUG_LOCKING_API_SELFTESTS 1516 bool "Locking API boot-time self-tests" 1517 depends on DEBUG_KERNEL 1518 help 1519 Say Y here if you want the kernel to run a short self-test during 1520 bootup. The self-test checks whether common types of locking bugs 1521 are detected by debugging mechanisms or not. (if you disable 1522 lock debugging then those bugs won't be detected of course.) 1523 The following locking APIs are covered: spinlocks, rwlocks, 1524 mutexes and rwsems. 1525 1526config LOCK_TORTURE_TEST 1527 tristate "torture tests for locking" 1528 depends on DEBUG_KERNEL 1529 select TORTURE_TEST 1530 help 1531 This option provides a kernel module that runs torture tests 1532 on kernel locking primitives. The kernel module may be built 1533 after the fact on the running kernel to be tested, if desired. 1534 1535 Say Y here if you want kernel locking-primitive torture tests 1536 to be built into the kernel. 1537 Say M if you want these torture tests to build as a module. 1538 Say N if you are unsure. 1539 1540config WW_MUTEX_SELFTEST 1541 tristate "Wait/wound mutex selftests" 1542 help 1543 This option provides a kernel module that runs tests on the 1544 on the struct ww_mutex locking API. 1545 1546 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1547 with this test harness. 1548 1549 Say M if you want these self tests to build as a module. 1550 Say N if you are unsure. 1551 1552config SCF_TORTURE_TEST 1553 tristate "torture tests for smp_call_function*()" 1554 depends on DEBUG_KERNEL 1555 select TORTURE_TEST 1556 help 1557 This option provides a kernel module that runs torture tests 1558 on the smp_call_function() family of primitives. The kernel 1559 module may be built after the fact on the running kernel to 1560 be tested, if desired. 1561 1562config CSD_LOCK_WAIT_DEBUG 1563 bool "Debugging for csd_lock_wait(), called from smp_call_function*()" 1564 depends on DEBUG_KERNEL 1565 depends on 64BIT 1566 default n 1567 help 1568 This option enables debug prints when CPUs are slow to respond 1569 to the smp_call_function*() IPI wrappers. These debug prints 1570 include the IPI handler function currently executing (if any) 1571 and relevant stack traces. 1572 1573config CSD_LOCK_WAIT_DEBUG_DEFAULT 1574 bool "Default csd_lock_wait() debugging on at boot time" 1575 depends on CSD_LOCK_WAIT_DEBUG 1576 depends on 64BIT 1577 default n 1578 help 1579 This option causes the csdlock_debug= kernel boot parameter to 1580 default to 1 (basic debugging) instead of 0 (no debugging). 1581 1582endmenu # lock debugging 1583 1584config TRACE_IRQFLAGS 1585 depends on TRACE_IRQFLAGS_SUPPORT 1586 bool 1587 help 1588 Enables hooks to interrupt enabling and disabling for 1589 either tracing or lock debugging. 1590 1591config TRACE_IRQFLAGS_NMI 1592 def_bool y 1593 depends on TRACE_IRQFLAGS 1594 depends on TRACE_IRQFLAGS_NMI_SUPPORT 1595 1596config NMI_CHECK_CPU 1597 bool "Debugging for CPUs failing to respond to backtrace requests" 1598 depends on DEBUG_KERNEL 1599 depends on X86 1600 default n 1601 help 1602 Enables debug prints when a CPU fails to respond to a given 1603 backtrace NMI. These prints provide some reasons why a CPU 1604 might legitimately be failing to respond, for example, if it 1605 is offline of if ignore_nmis is set. 1606 1607config DEBUG_IRQFLAGS 1608 bool "Debug IRQ flag manipulation" 1609 help 1610 Enables checks for potentially unsafe enabling or disabling of 1611 interrupts, such as calling raw_local_irq_restore() when interrupts 1612 are enabled. 1613 1614config STACKTRACE 1615 bool "Stack backtrace support" 1616 depends on STACKTRACE_SUPPORT 1617 help 1618 This option causes the kernel to create a /proc/pid/stack for 1619 every process, showing its current stack trace. 1620 It is also used by various kernel debugging features that require 1621 stack trace generation. 1622 1623config WARN_ALL_UNSEEDED_RANDOM 1624 bool "Warn for all uses of unseeded randomness" 1625 default n 1626 help 1627 Some parts of the kernel contain bugs relating to their use of 1628 cryptographically secure random numbers before it's actually possible 1629 to generate those numbers securely. This setting ensures that these 1630 flaws don't go unnoticed, by enabling a message, should this ever 1631 occur. This will allow people with obscure setups to know when things 1632 are going wrong, so that they might contact developers about fixing 1633 it. 1634 1635 Unfortunately, on some models of some architectures getting 1636 a fully seeded CRNG is extremely difficult, and so this can 1637 result in dmesg getting spammed for a surprisingly long 1638 time. This is really bad from a security perspective, and 1639 so architecture maintainers really need to do what they can 1640 to get the CRNG seeded sooner after the system is booted. 1641 However, since users cannot do anything actionable to 1642 address this, by default this option is disabled. 1643 1644 Say Y here if you want to receive warnings for all uses of 1645 unseeded randomness. This will be of use primarily for 1646 those developers interested in improving the security of 1647 Linux kernels running on their architecture (or 1648 subarchitecture). 1649 1650config DEBUG_KOBJECT 1651 bool "kobject debugging" 1652 depends on DEBUG_KERNEL 1653 help 1654 If you say Y here, some extra kobject debugging messages will be sent 1655 to the syslog. 1656 1657config DEBUG_KOBJECT_RELEASE 1658 bool "kobject release debugging" 1659 depends on DEBUG_OBJECTS_TIMERS 1660 help 1661 kobjects are reference counted objects. This means that their 1662 last reference count put is not predictable, and the kobject can 1663 live on past the point at which a driver decides to drop its 1664 initial reference to the kobject gained on allocation. An 1665 example of this would be a struct device which has just been 1666 unregistered. 1667 1668 However, some buggy drivers assume that after such an operation, 1669 the memory backing the kobject can be immediately freed. This 1670 goes completely against the principles of a refcounted object. 1671 1672 If you say Y here, the kernel will delay the release of kobjects 1673 on the last reference count to improve the visibility of this 1674 kind of kobject release bug. 1675 1676config HAVE_DEBUG_BUGVERBOSE 1677 bool 1678 1679menu "Debug kernel data structures" 1680 1681config DEBUG_LIST 1682 bool "Debug linked list manipulation" 1683 depends on DEBUG_KERNEL 1684 select LIST_HARDENED 1685 help 1686 Enable this to turn on extended checks in the linked-list walking 1687 routines. 1688 1689 This option trades better quality error reports for performance, and 1690 is more suitable for kernel debugging. If you care about performance, 1691 you should only enable CONFIG_LIST_HARDENED instead. 1692 1693 If unsure, say N. 1694 1695config DEBUG_PLIST 1696 bool "Debug priority linked list manipulation" 1697 depends on DEBUG_KERNEL 1698 help 1699 Enable this to turn on extended checks in the priority-ordered 1700 linked-list (plist) walking routines. This checks the entire 1701 list multiple times during each manipulation. 1702 1703 If unsure, say N. 1704 1705config DEBUG_SG 1706 bool "Debug SG table operations" 1707 depends on DEBUG_KERNEL 1708 help 1709 Enable this to turn on checks on scatter-gather tables. This can 1710 help find problems with drivers that do not properly initialize 1711 their sg tables. 1712 1713 If unsure, say N. 1714 1715config DEBUG_NOTIFIERS 1716 bool "Debug notifier call chains" 1717 depends on DEBUG_KERNEL 1718 help 1719 Enable this to turn on sanity checking for notifier call chains. 1720 This is most useful for kernel developers to make sure that 1721 modules properly unregister themselves from notifier chains. 1722 This is a relatively cheap check but if you care about maximum 1723 performance, say N. 1724 1725config DEBUG_CLOSURES 1726 bool "Debug closures (bcache async widgits)" 1727 depends on CLOSURES 1728 select DEBUG_FS 1729 help 1730 Keeps all active closures in a linked list and provides a debugfs 1731 interface to list them, which makes it possible to see asynchronous 1732 operations that get stuck. 1733 1734config DEBUG_MAPLE_TREE 1735 bool "Debug maple trees" 1736 depends on DEBUG_KERNEL 1737 help 1738 Enable maple tree debugging information and extra validations. 1739 1740 If unsure, say N. 1741 1742endmenu 1743 1744source "kernel/rcu/Kconfig.debug" 1745 1746config DEBUG_WQ_FORCE_RR_CPU 1747 bool "Force round-robin CPU selection for unbound work items" 1748 depends on DEBUG_KERNEL 1749 default n 1750 help 1751 Workqueue used to implicitly guarantee that work items queued 1752 without explicit CPU specified are put on the local CPU. This 1753 guarantee is no longer true and while local CPU is still 1754 preferred work items may be put on foreign CPUs. Kernel 1755 parameter "workqueue.debug_force_rr_cpu" is added to force 1756 round-robin CPU selection to flush out usages which depend on the 1757 now broken guarantee. This config option enables the debug 1758 feature by default. When enabled, memory and cache locality will 1759 be impacted. 1760 1761config CPU_HOTPLUG_STATE_CONTROL 1762 bool "Enable CPU hotplug state control" 1763 depends on DEBUG_KERNEL 1764 depends on HOTPLUG_CPU 1765 default n 1766 help 1767 Allows to write steps between "offline" and "online" to the CPUs 1768 sysfs target file so states can be stepped granular. This is a debug 1769 option for now as the hotplug machinery cannot be stopped and 1770 restarted at arbitrary points yet. 1771 1772 Say N if your are unsure. 1773 1774config LATENCYTOP 1775 bool "Latency measuring infrastructure" 1776 depends on DEBUG_KERNEL 1777 depends on STACKTRACE_SUPPORT 1778 depends on PROC_FS 1779 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 1780 select KALLSYMS 1781 select KALLSYMS_ALL 1782 select STACKTRACE 1783 select SCHEDSTATS 1784 help 1785 Enable this option if you want to use the LatencyTOP tool 1786 to find out which userspace is blocking on what kernel operations. 1787 1788config DEBUG_CGROUP_REF 1789 bool "Disable inlining of cgroup css reference count functions" 1790 depends on DEBUG_KERNEL 1791 depends on CGROUPS 1792 depends on KPROBES 1793 default n 1794 help 1795 Force cgroup css reference count functions to not be inlined so 1796 that they can be kprobed for debugging. 1797 1798source "kernel/trace/Kconfig" 1799 1800config PROVIDE_OHCI1394_DMA_INIT 1801 bool "Remote debugging over FireWire early on boot" 1802 depends on PCI && X86 1803 help 1804 If you want to debug problems which hang or crash the kernel early 1805 on boot and the crashing machine has a FireWire port, you can use 1806 this feature to remotely access the memory of the crashed machine 1807 over FireWire. This employs remote DMA as part of the OHCI1394 1808 specification which is now the standard for FireWire controllers. 1809 1810 With remote DMA, you can monitor the printk buffer remotely using 1811 firescope and access all memory below 4GB using fireproxy from gdb. 1812 Even controlling a kernel debugger is possible using remote DMA. 1813 1814 Usage: 1815 1816 If ohci1394_dma=early is used as boot parameter, it will initialize 1817 all OHCI1394 controllers which are found in the PCI config space. 1818 1819 As all changes to the FireWire bus such as enabling and disabling 1820 devices cause a bus reset and thereby disable remote DMA for all 1821 devices, be sure to have the cable plugged and FireWire enabled on 1822 the debugging host before booting the debug target for debugging. 1823 1824 This code (~1k) is freed after boot. By then, the firewire stack 1825 in charge of the OHCI-1394 controllers should be used instead. 1826 1827 See Documentation/core-api/debugging-via-ohci1394.rst for more information. 1828 1829source "samples/Kconfig" 1830 1831config ARCH_HAS_DEVMEM_IS_ALLOWED 1832 bool 1833 1834config STRICT_DEVMEM 1835 bool "Filter access to /dev/mem" 1836 depends on MMU && DEVMEM 1837 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED 1838 default y if PPC || X86 || ARM64 1839 help 1840 If this option is disabled, you allow userspace (root) access to all 1841 of memory, including kernel and userspace memory. Accidental 1842 access to this is obviously disastrous, but specific access can 1843 be used by people debugging the kernel. Note that with PAT support 1844 enabled, even in this case there are restrictions on /dev/mem 1845 use due to the cache aliasing requirements. 1846 1847 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 1848 file only allows userspace access to PCI space and the BIOS code and 1849 data regions. This is sufficient for dosemu and X and all common 1850 users of /dev/mem. 1851 1852 If in doubt, say Y. 1853 1854config IO_STRICT_DEVMEM 1855 bool "Filter I/O access to /dev/mem" 1856 depends on STRICT_DEVMEM 1857 help 1858 If this option is disabled, you allow userspace (root) access to all 1859 io-memory regardless of whether a driver is actively using that 1860 range. Accidental access to this is obviously disastrous, but 1861 specific access can be used by people debugging kernel drivers. 1862 1863 If this option is switched on, the /dev/mem file only allows 1864 userspace access to *idle* io-memory ranges (see /proc/iomem) This 1865 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 1866 if the driver using a given range cannot be disabled. 1867 1868 If in doubt, say Y. 1869 1870menu "$(SRCARCH) Debugging" 1871 1872source "arch/$(SRCARCH)/Kconfig.debug" 1873 1874endmenu 1875 1876menu "Kernel Testing and Coverage" 1877 1878source "lib/kunit/Kconfig" 1879 1880config NOTIFIER_ERROR_INJECTION 1881 tristate "Notifier error injection" 1882 depends on DEBUG_KERNEL 1883 select DEBUG_FS 1884 help 1885 This option provides the ability to inject artificial errors to 1886 specified notifier chain callbacks. It is useful to test the error 1887 handling of notifier call chain failures. 1888 1889 Say N if unsure. 1890 1891config PM_NOTIFIER_ERROR_INJECT 1892 tristate "PM notifier error injection module" 1893 depends on PM && NOTIFIER_ERROR_INJECTION 1894 default m if PM_DEBUG 1895 help 1896 This option provides the ability to inject artificial errors to 1897 PM notifier chain callbacks. It is controlled through debugfs 1898 interface /sys/kernel/debug/notifier-error-inject/pm 1899 1900 If the notifier call chain should be failed with some events 1901 notified, write the error code to "actions/<notifier event>/error". 1902 1903 Example: Inject PM suspend error (-12 = -ENOMEM) 1904 1905 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1906 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1907 # echo mem > /sys/power/state 1908 bash: echo: write error: Cannot allocate memory 1909 1910 To compile this code as a module, choose M here: the module will 1911 be called pm-notifier-error-inject. 1912 1913 If unsure, say N. 1914 1915config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1916 tristate "OF reconfig notifier error injection module" 1917 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1918 help 1919 This option provides the ability to inject artificial errors to 1920 OF reconfig notifier chain callbacks. It is controlled 1921 through debugfs interface under 1922 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1923 1924 If the notifier call chain should be failed with some events 1925 notified, write the error code to "actions/<notifier event>/error". 1926 1927 To compile this code as a module, choose M here: the module will 1928 be called of-reconfig-notifier-error-inject. 1929 1930 If unsure, say N. 1931 1932config NETDEV_NOTIFIER_ERROR_INJECT 1933 tristate "Netdev notifier error injection module" 1934 depends on NET && NOTIFIER_ERROR_INJECTION 1935 help 1936 This option provides the ability to inject artificial errors to 1937 netdevice notifier chain callbacks. It is controlled through debugfs 1938 interface /sys/kernel/debug/notifier-error-inject/netdev 1939 1940 If the notifier call chain should be failed with some events 1941 notified, write the error code to "actions/<notifier event>/error". 1942 1943 Example: Inject netdevice mtu change error (-22 = -EINVAL) 1944 1945 # cd /sys/kernel/debug/notifier-error-inject/netdev 1946 # echo -22 > actions/NETDEV_CHANGEMTU/error 1947 # ip link set eth0 mtu 1024 1948 RTNETLINK answers: Invalid argument 1949 1950 To compile this code as a module, choose M here: the module will 1951 be called netdev-notifier-error-inject. 1952 1953 If unsure, say N. 1954 1955config FUNCTION_ERROR_INJECTION 1956 bool "Fault-injections of functions" 1957 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 1958 help 1959 Add fault injections into various functions that are annotated with 1960 ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return 1961 value of these functions. This is useful to test error paths of code. 1962 1963 If unsure, say N 1964 1965config FAULT_INJECTION 1966 bool "Fault-injection framework" 1967 depends on DEBUG_KERNEL 1968 help 1969 Provide fault-injection framework. 1970 For more details, see Documentation/fault-injection/. 1971 1972config FAILSLAB 1973 bool "Fault-injection capability for kmalloc" 1974 depends on FAULT_INJECTION 1975 help 1976 Provide fault-injection capability for kmalloc. 1977 1978config FAIL_PAGE_ALLOC 1979 bool "Fault-injection capability for alloc_pages()" 1980 depends on FAULT_INJECTION 1981 help 1982 Provide fault-injection capability for alloc_pages(). 1983 1984config FAULT_INJECTION_USERCOPY 1985 bool "Fault injection capability for usercopy functions" 1986 depends on FAULT_INJECTION 1987 help 1988 Provides fault-injection capability to inject failures 1989 in usercopy functions (copy_from_user(), get_user(), ...). 1990 1991config FAIL_MAKE_REQUEST 1992 bool "Fault-injection capability for disk IO" 1993 depends on FAULT_INJECTION && BLOCK 1994 help 1995 Provide fault-injection capability for disk IO. 1996 1997config FAIL_IO_TIMEOUT 1998 bool "Fault-injection capability for faking disk interrupts" 1999 depends on FAULT_INJECTION && BLOCK 2000 help 2001 Provide fault-injection capability on end IO handling. This 2002 will make the block layer "forget" an interrupt as configured, 2003 thus exercising the error handling. 2004 2005 Only works with drivers that use the generic timeout handling, 2006 for others it won't do anything. 2007 2008config FAIL_FUTEX 2009 bool "Fault-injection capability for futexes" 2010 select DEBUG_FS 2011 depends on FAULT_INJECTION && FUTEX 2012 help 2013 Provide fault-injection capability for futexes. 2014 2015config FAULT_INJECTION_DEBUG_FS 2016 bool "Debugfs entries for fault-injection capabilities" 2017 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 2018 help 2019 Enable configuration of fault-injection capabilities via debugfs. 2020 2021config FAIL_FUNCTION 2022 bool "Fault-injection capability for functions" 2023 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 2024 help 2025 Provide function-based fault-injection capability. 2026 This will allow you to override a specific function with a return 2027 with given return value. As a result, function caller will see 2028 an error value and have to handle it. This is useful to test the 2029 error handling in various subsystems. 2030 2031config FAIL_MMC_REQUEST 2032 bool "Fault-injection capability for MMC IO" 2033 depends on FAULT_INJECTION_DEBUG_FS && MMC 2034 help 2035 Provide fault-injection capability for MMC IO. 2036 This will make the mmc core return data errors. This is 2037 useful to test the error handling in the mmc block device 2038 and to test how the mmc host driver handles retries from 2039 the block device. 2040 2041config FAIL_SUNRPC 2042 bool "Fault-injection capability for SunRPC" 2043 depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG 2044 help 2045 Provide fault-injection capability for SunRPC and 2046 its consumers. 2047 2048config FAULT_INJECTION_CONFIGFS 2049 bool "Configfs interface for fault-injection capabilities" 2050 depends on FAULT_INJECTION 2051 select CONFIGFS_FS 2052 help 2053 This option allows configfs-based drivers to dynamically configure 2054 fault-injection via configfs. Each parameter for driver-specific 2055 fault-injection can be made visible as a configfs attribute in a 2056 configfs group. 2057 2058 2059config FAULT_INJECTION_STACKTRACE_FILTER 2060 bool "stacktrace filter for fault-injection capabilities" 2061 depends on FAULT_INJECTION 2062 depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT 2063 select STACKTRACE 2064 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 2065 help 2066 Provide stacktrace filter for fault-injection capabilities 2067 2068config ARCH_HAS_KCOV 2069 bool 2070 help 2071 An architecture should select this when it can successfully 2072 build and run with CONFIG_KCOV. This typically requires 2073 disabling instrumentation for some early boot code. 2074 2075config CC_HAS_SANCOV_TRACE_PC 2076 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 2077 2078 2079config KCOV 2080 bool "Code coverage for fuzzing" 2081 depends on ARCH_HAS_KCOV 2082 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 2083 depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \ 2084 GCC_VERSION >= 120000 || CLANG_VERSION >= 130000 2085 select DEBUG_FS 2086 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 2087 select OBJTOOL if HAVE_NOINSTR_HACK 2088 help 2089 KCOV exposes kernel code coverage information in a form suitable 2090 for coverage-guided fuzzing (randomized testing). 2091 2092 For more details, see Documentation/dev-tools/kcov.rst. 2093 2094config KCOV_ENABLE_COMPARISONS 2095 bool "Enable comparison operands collection by KCOV" 2096 depends on KCOV 2097 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 2098 help 2099 KCOV also exposes operands of every comparison in the instrumented 2100 code along with operand sizes and PCs of the comparison instructions. 2101 These operands can be used by fuzzing engines to improve the quality 2102 of fuzzing coverage. 2103 2104config KCOV_INSTRUMENT_ALL 2105 bool "Instrument all code by default" 2106 depends on KCOV 2107 default y 2108 help 2109 If you are doing generic system call fuzzing (like e.g. syzkaller), 2110 then you will want to instrument the whole kernel and you should 2111 say y here. If you are doing more targeted fuzzing (like e.g. 2112 filesystem fuzzing with AFL) then you will want to enable coverage 2113 for more specific subsets of files, and should say n here. 2114 2115config KCOV_IRQ_AREA_SIZE 2116 hex "Size of interrupt coverage collection area in words" 2117 depends on KCOV 2118 default 0x40000 2119 help 2120 KCOV uses preallocated per-cpu areas to collect coverage from 2121 soft interrupts. This specifies the size of those areas in the 2122 number of unsigned long words. 2123 2124menuconfig RUNTIME_TESTING_MENU 2125 bool "Runtime Testing" 2126 def_bool y 2127 2128if RUNTIME_TESTING_MENU 2129 2130config TEST_DHRY 2131 tristate "Dhrystone benchmark test" 2132 help 2133 Enable this to include the Dhrystone 2.1 benchmark. This test 2134 calculates the number of Dhrystones per second, and the number of 2135 DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided 2136 by 1757 (the number of Dhrystones per second obtained on the VAX 2137 11/780, nominally a 1 MIPS machine). 2138 2139 To run the benchmark, it needs to be enabled explicitly, either from 2140 the kernel command line (when built-in), or from userspace (when 2141 built-in or modular. 2142 2143 Run once during kernel boot: 2144 2145 test_dhry.run 2146 2147 Set number of iterations from kernel command line: 2148 2149 test_dhry.iterations=<n> 2150 2151 Set number of iterations from userspace: 2152 2153 echo <n> > /sys/module/test_dhry/parameters/iterations 2154 2155 Trigger manual run from userspace: 2156 2157 echo y > /sys/module/test_dhry/parameters/run 2158 2159 If the number of iterations is <= 0, the test will devise a suitable 2160 number of iterations (test runs for at least 2s) automatically. 2161 This process takes ca. 4s. 2162 2163 If unsure, say N. 2164 2165config LKDTM 2166 tristate "Linux Kernel Dump Test Tool Module" 2167 depends on DEBUG_FS 2168 help 2169 This module enables testing of the different dumping mechanisms by 2170 inducing system failures at predefined crash points. 2171 If you don't need it: say N 2172 Choose M here to compile this code as a module. The module will be 2173 called lkdtm. 2174 2175 Documentation on how to use the module can be found in 2176 Documentation/fault-injection/provoke-crashes.rst 2177 2178config CPUMASK_KUNIT_TEST 2179 tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS 2180 depends on KUNIT 2181 default KUNIT_ALL_TESTS 2182 help 2183 Enable to turn on cpumask tests, running at boot or module load time. 2184 2185 For more information on KUnit and unit tests in general, please refer 2186 to the KUnit documentation in Documentation/dev-tools/kunit/. 2187 2188 If unsure, say N. 2189 2190config TEST_LIST_SORT 2191 tristate "Linked list sorting test" if !KUNIT_ALL_TESTS 2192 depends on KUNIT 2193 default KUNIT_ALL_TESTS 2194 help 2195 Enable this to turn on 'list_sort()' function test. This test is 2196 executed only once during system boot (so affects only boot time), 2197 or at module load time. 2198 2199 If unsure, say N. 2200 2201config TEST_MIN_HEAP 2202 tristate "Min heap test" 2203 depends on DEBUG_KERNEL || m 2204 help 2205 Enable this to turn on min heap function tests. This test is 2206 executed only once during system boot (so affects only boot time), 2207 or at module load time. 2208 2209 If unsure, say N. 2210 2211config TEST_SORT 2212 tristate "Array-based sort test" if !KUNIT_ALL_TESTS 2213 depends on KUNIT 2214 default KUNIT_ALL_TESTS 2215 help 2216 This option enables the self-test function of 'sort()' at boot, 2217 or at module load time. 2218 2219 If unsure, say N. 2220 2221config TEST_DIV64 2222 tristate "64bit/32bit division and modulo test" 2223 depends on DEBUG_KERNEL || m 2224 help 2225 Enable this to turn on 'do_div()' function test. This test is 2226 executed only once during system boot (so affects only boot time), 2227 or at module load time. 2228 2229 If unsure, say N. 2230 2231config TEST_IOV_ITER 2232 tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS 2233 depends on KUNIT 2234 default KUNIT_ALL_TESTS 2235 help 2236 Enable this to turn on testing of the operation of the I/O iterator 2237 (iov_iter). This test is executed only once during system boot (so 2238 affects only boot time), or at module load time. 2239 2240 If unsure, say N. 2241 2242config KPROBES_SANITY_TEST 2243 tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS 2244 depends on DEBUG_KERNEL 2245 depends on KPROBES 2246 depends on KUNIT 2247 select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 2248 default KUNIT_ALL_TESTS 2249 help 2250 This option provides for testing basic kprobes functionality on 2251 boot. Samples of kprobe and kretprobe are inserted and 2252 verified for functionality. 2253 2254 Say N if you are unsure. 2255 2256config FPROBE_SANITY_TEST 2257 bool "Self test for fprobe" 2258 depends on DEBUG_KERNEL 2259 depends on FPROBE 2260 depends on KUNIT=y 2261 help 2262 This option will enable testing the fprobe when the system boot. 2263 A series of tests are made to verify that the fprobe is functioning 2264 properly. 2265 2266 Say N if you are unsure. 2267 2268config BACKTRACE_SELF_TEST 2269 tristate "Self test for the backtrace code" 2270 depends on DEBUG_KERNEL 2271 help 2272 This option provides a kernel module that can be used to test 2273 the kernel stack backtrace code. This option is not useful 2274 for distributions or general kernels, but only for kernel 2275 developers working on architecture code. 2276 2277 Note that if you want to also test saved backtraces, you will 2278 have to enable STACKTRACE as well. 2279 2280 Say N if you are unsure. 2281 2282config TEST_REF_TRACKER 2283 tristate "Self test for reference tracker" 2284 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT 2285 select REF_TRACKER 2286 help 2287 This option provides a kernel module performing tests 2288 using reference tracker infrastructure. 2289 2290 Say N if you are unsure. 2291 2292config RBTREE_TEST 2293 tristate "Red-Black tree test" 2294 depends on DEBUG_KERNEL 2295 help 2296 A benchmark measuring the performance of the rbtree library. 2297 Also includes rbtree invariant checks. 2298 2299config REED_SOLOMON_TEST 2300 tristate "Reed-Solomon library test" 2301 depends on DEBUG_KERNEL || m 2302 select REED_SOLOMON 2303 select REED_SOLOMON_ENC16 2304 select REED_SOLOMON_DEC16 2305 help 2306 This option enables the self-test function of rslib at boot, 2307 or at module load time. 2308 2309 If unsure, say N. 2310 2311config INTERVAL_TREE_TEST 2312 tristate "Interval tree test" 2313 depends on DEBUG_KERNEL 2314 select INTERVAL_TREE 2315 help 2316 A benchmark measuring the performance of the interval tree library 2317 2318config PERCPU_TEST 2319 tristate "Per cpu operations test" 2320 depends on m && DEBUG_KERNEL 2321 help 2322 Enable this option to build test module which validates per-cpu 2323 operations. 2324 2325 If unsure, say N. 2326 2327config ATOMIC64_SELFTEST 2328 tristate "Perform an atomic64_t self-test" 2329 help 2330 Enable this option to test the atomic64_t functions at boot or 2331 at module load time. 2332 2333 If unsure, say N. 2334 2335config ASYNC_RAID6_TEST 2336 tristate "Self test for hardware accelerated raid6 recovery" 2337 depends on ASYNC_RAID6_RECOV 2338 select ASYNC_MEMCPY 2339 help 2340 This is a one-shot self test that permutes through the 2341 recovery of all the possible two disk failure scenarios for a 2342 N-disk array. Recovery is performed with the asynchronous 2343 raid6 recovery routines, and will optionally use an offload 2344 engine if one is available. 2345 2346 If unsure, say N. 2347 2348config TEST_HEXDUMP 2349 tristate "Test functions located in the hexdump module at runtime" 2350 2351config STRING_SELFTEST 2352 tristate "Test string functions at runtime" 2353 2354config TEST_STRING_HELPERS 2355 tristate "Test functions located in the string_helpers module at runtime" 2356 2357config TEST_KSTRTOX 2358 tristate "Test kstrto*() family of functions at runtime" 2359 2360config TEST_PRINTF 2361 tristate "Test printf() family of functions at runtime" 2362 2363config TEST_SCANF 2364 tristate "Test scanf() family of functions at runtime" 2365 2366config TEST_BITMAP 2367 tristate "Test bitmap_*() family of functions at runtime" 2368 help 2369 Enable this option to test the bitmap functions at boot. 2370 2371 If unsure, say N. 2372 2373config TEST_UUID 2374 tristate "Test functions located in the uuid module at runtime" 2375 2376config TEST_XARRAY 2377 tristate "Test the XArray code at runtime" 2378 2379config TEST_MAPLE_TREE 2380 tristate "Test the Maple Tree code at runtime or module load" 2381 help 2382 Enable this option to test the maple tree code functions at boot, or 2383 when the module is loaded. Enable "Debug Maple Trees" will enable 2384 more verbose output on failures. 2385 2386 If unsure, say N. 2387 2388config TEST_RHASHTABLE 2389 tristate "Perform selftest on resizable hash table" 2390 help 2391 Enable this option to test the rhashtable functions at boot. 2392 2393 If unsure, say N. 2394 2395config TEST_IDA 2396 tristate "Perform selftest on IDA functions" 2397 2398config TEST_PARMAN 2399 tristate "Perform selftest on priority array manager" 2400 depends on PARMAN 2401 help 2402 Enable this option to test priority array manager on boot 2403 (or module load). 2404 2405 If unsure, say N. 2406 2407config TEST_IRQ_TIMINGS 2408 bool "IRQ timings selftest" 2409 depends on IRQ_TIMINGS 2410 help 2411 Enable this option to test the irq timings code on boot. 2412 2413 If unsure, say N. 2414 2415config TEST_LKM 2416 tristate "Test module loading with 'hello world' module" 2417 depends on m 2418 help 2419 This builds the "test_module" module that emits "Hello, world" 2420 on printk when loaded. It is designed to be used for basic 2421 evaluation of the module loading subsystem (for example when 2422 validating module verification). It lacks any extra dependencies, 2423 and will not normally be loaded by the system unless explicitly 2424 requested by name. 2425 2426 If unsure, say N. 2427 2428config TEST_BITOPS 2429 tristate "Test module for compilation of bitops operations" 2430 depends on m 2431 help 2432 This builds the "test_bitops" module that is much like the 2433 TEST_LKM module except that it does a basic exercise of the 2434 set/clear_bit macros and get_count_order/long to make sure there are 2435 no compiler warnings from C=1 sparse checker or -Wextra 2436 compilations. It has no dependencies and doesn't run or load unless 2437 explicitly requested by name. for example: modprobe test_bitops. 2438 2439 If unsure, say N. 2440 2441config TEST_VMALLOC 2442 tristate "Test module for stress/performance analysis of vmalloc allocator" 2443 default n 2444 depends on MMU 2445 depends on m 2446 help 2447 This builds the "test_vmalloc" module that should be used for 2448 stress and performance analysis. So, any new change for vmalloc 2449 subsystem can be evaluated from performance and stability point 2450 of view. 2451 2452 If unsure, say N. 2453 2454config TEST_USER_COPY 2455 tristate "Test user/kernel boundary protections" 2456 depends on m 2457 help 2458 This builds the "test_user_copy" module that runs sanity checks 2459 on the copy_to/from_user infrastructure, making sure basic 2460 user/kernel boundary testing is working. If it fails to load, 2461 a regression has been detected in the user/kernel memory boundary 2462 protections. 2463 2464 If unsure, say N. 2465 2466config TEST_BPF 2467 tristate "Test BPF filter functionality" 2468 depends on m && NET 2469 help 2470 This builds the "test_bpf" module that runs various test vectors 2471 against the BPF interpreter or BPF JIT compiler depending on the 2472 current setting. This is in particular useful for BPF JIT compiler 2473 development, but also to run regression tests against changes in 2474 the interpreter code. It also enables test stubs for eBPF maps and 2475 verifier used by user space verifier testsuite. 2476 2477 If unsure, say N. 2478 2479config TEST_BLACKHOLE_DEV 2480 tristate "Test blackhole netdev functionality" 2481 depends on m && NET 2482 help 2483 This builds the "test_blackhole_dev" module that validates the 2484 data path through this blackhole netdev. 2485 2486 If unsure, say N. 2487 2488config FIND_BIT_BENCHMARK 2489 tristate "Test find_bit functions" 2490 help 2491 This builds the "test_find_bit" module that measure find_*_bit() 2492 functions performance. 2493 2494 If unsure, say N. 2495 2496config TEST_FIRMWARE 2497 tristate "Test firmware loading via userspace interface" 2498 depends on FW_LOADER 2499 help 2500 This builds the "test_firmware" module that creates a userspace 2501 interface for testing firmware loading. This can be used to 2502 control the triggering of firmware loading without needing an 2503 actual firmware-using device. The contents can be rechecked by 2504 userspace. 2505 2506 If unsure, say N. 2507 2508config TEST_SYSCTL 2509 tristate "sysctl test driver" 2510 depends on PROC_SYSCTL 2511 help 2512 This builds the "test_sysctl" module. This driver enables to test the 2513 proc sysctl interfaces available to drivers safely without affecting 2514 production knobs which might alter system functionality. 2515 2516 If unsure, say N. 2517 2518config BITFIELD_KUNIT 2519 tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS 2520 depends on KUNIT 2521 default KUNIT_ALL_TESTS 2522 help 2523 Enable this option to test the bitfield functions at boot. 2524 2525 KUnit tests run during boot and output the results to the debug log 2526 in TAP format (http://testanything.org/). Only useful for kernel devs 2527 running the KUnit test harness, and not intended for inclusion into a 2528 production build. 2529 2530 For more information on KUnit and unit tests in general please refer 2531 to the KUnit documentation in Documentation/dev-tools/kunit/. 2532 2533 If unsure, say N. 2534 2535config CHECKSUM_KUNIT 2536 tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS 2537 depends on KUNIT 2538 default KUNIT_ALL_TESTS 2539 help 2540 Enable this option to test the checksum functions at boot. 2541 2542 KUnit tests run during boot and output the results to the debug log 2543 in TAP format (http://testanything.org/). Only useful for kernel devs 2544 running the KUnit test harness, and not intended for inclusion into a 2545 production build. 2546 2547 For more information on KUnit and unit tests in general please refer 2548 to the KUnit documentation in Documentation/dev-tools/kunit/. 2549 2550 If unsure, say N. 2551 2552config HASH_KUNIT_TEST 2553 tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS 2554 depends on KUNIT 2555 default KUNIT_ALL_TESTS 2556 help 2557 Enable this option to test the kernel's string (<linux/stringhash.h>), and 2558 integer (<linux/hash.h>) hash functions on boot. 2559 2560 KUnit tests run during boot and output the results to the debug log 2561 in TAP format (https://testanything.org/). Only useful for kernel devs 2562 running the KUnit test harness, and not intended for inclusion into a 2563 production build. 2564 2565 For more information on KUnit and unit tests in general please refer 2566 to the KUnit documentation in Documentation/dev-tools/kunit/. 2567 2568 This is intended to help people writing architecture-specific 2569 optimized versions. If unsure, say N. 2570 2571config RESOURCE_KUNIT_TEST 2572 tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS 2573 depends on KUNIT 2574 default KUNIT_ALL_TESTS 2575 help 2576 This builds the resource API unit test. 2577 Tests the logic of API provided by resource.c and ioport.h. 2578 For more information on KUnit and unit tests in general please refer 2579 to the KUnit documentation in Documentation/dev-tools/kunit/. 2580 2581 If unsure, say N. 2582 2583config SYSCTL_KUNIT_TEST 2584 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS 2585 depends on KUNIT 2586 default KUNIT_ALL_TESTS 2587 help 2588 This builds the proc sysctl unit test, which runs on boot. 2589 Tests the API contract and implementation correctness of sysctl. 2590 For more information on KUnit and unit tests in general please refer 2591 to the KUnit documentation in Documentation/dev-tools/kunit/. 2592 2593 If unsure, say N. 2594 2595config LIST_KUNIT_TEST 2596 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS 2597 depends on KUNIT 2598 default KUNIT_ALL_TESTS 2599 help 2600 This builds the linked list KUnit test suite. 2601 It tests that the API and basic functionality of the list_head type 2602 and associated macros. 2603 2604 KUnit tests run during boot and output the results to the debug log 2605 in TAP format (https://testanything.org/). Only useful for kernel devs 2606 running the KUnit test harness, and not intended for inclusion into a 2607 production build. 2608 2609 For more information on KUnit and unit tests in general please refer 2610 to the KUnit documentation in Documentation/dev-tools/kunit/. 2611 2612 If unsure, say N. 2613 2614config HASHTABLE_KUNIT_TEST 2615 tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS 2616 depends on KUNIT 2617 default KUNIT_ALL_TESTS 2618 help 2619 This builds the hashtable KUnit test suite. 2620 It tests the basic functionality of the API defined in 2621 include/linux/hashtable.h. For more information on KUnit and 2622 unit tests in general please refer to the KUnit documentation 2623 in Documentation/dev-tools/kunit/. 2624 2625 If unsure, say N. 2626 2627config LINEAR_RANGES_TEST 2628 tristate "KUnit test for linear_ranges" 2629 depends on KUNIT 2630 select LINEAR_RANGES 2631 help 2632 This builds the linear_ranges unit test, which runs on boot. 2633 Tests the linear_ranges logic correctness. 2634 For more information on KUnit and unit tests in general please refer 2635 to the KUnit documentation in Documentation/dev-tools/kunit/. 2636 2637 If unsure, say N. 2638 2639config CMDLINE_KUNIT_TEST 2640 tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS 2641 depends on KUNIT 2642 default KUNIT_ALL_TESTS 2643 help 2644 This builds the cmdline API unit test. 2645 Tests the logic of API provided by cmdline.c. 2646 For more information on KUnit and unit tests in general please refer 2647 to the KUnit documentation in Documentation/dev-tools/kunit/. 2648 2649 If unsure, say N. 2650 2651config BITS_TEST 2652 tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS 2653 depends on KUNIT 2654 default KUNIT_ALL_TESTS 2655 help 2656 This builds the bits unit test. 2657 Tests the logic of macros defined in bits.h. 2658 For more information on KUnit and unit tests in general please refer 2659 to the KUnit documentation in Documentation/dev-tools/kunit/. 2660 2661 If unsure, say N. 2662 2663config SLUB_KUNIT_TEST 2664 tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS 2665 depends on SLUB_DEBUG && KUNIT 2666 default KUNIT_ALL_TESTS 2667 help 2668 This builds SLUB allocator unit test. 2669 Tests SLUB cache debugging functionality. 2670 For more information on KUnit and unit tests in general please refer 2671 to the KUnit documentation in Documentation/dev-tools/kunit/. 2672 2673 If unsure, say N. 2674 2675config RATIONAL_KUNIT_TEST 2676 tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS 2677 depends on KUNIT && RATIONAL 2678 default KUNIT_ALL_TESTS 2679 help 2680 This builds the rational math unit test. 2681 For more information on KUnit and unit tests in general please refer 2682 to the KUnit documentation in Documentation/dev-tools/kunit/. 2683 2684 If unsure, say N. 2685 2686config MEMCPY_KUNIT_TEST 2687 tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS 2688 depends on KUNIT 2689 default KUNIT_ALL_TESTS 2690 help 2691 Builds unit tests for memcpy(), memmove(), and memset() functions. 2692 For more information on KUnit and unit tests in general please refer 2693 to the KUnit documentation in Documentation/dev-tools/kunit/. 2694 2695 If unsure, say N. 2696 2697config MEMCPY_SLOW_KUNIT_TEST 2698 bool "Include exhaustive memcpy tests" 2699 depends on MEMCPY_KUNIT_TEST 2700 default y 2701 help 2702 Some memcpy tests are quite exhaustive in checking for overlaps 2703 and bit ranges. These can be very slow, so they are split out 2704 as a separate config, in case they need to be disabled. 2705 2706 Note this config option will be replaced by the use of KUnit test 2707 attributes. 2708 2709config IS_SIGNED_TYPE_KUNIT_TEST 2710 tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS 2711 depends on KUNIT 2712 default KUNIT_ALL_TESTS 2713 help 2714 Builds unit tests for the is_signed_type() macro. 2715 2716 For more information on KUnit and unit tests in general please refer 2717 to the KUnit documentation in Documentation/dev-tools/kunit/. 2718 2719 If unsure, say N. 2720 2721config OVERFLOW_KUNIT_TEST 2722 tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS 2723 depends on KUNIT 2724 default KUNIT_ALL_TESTS 2725 help 2726 Builds unit tests for the check_*_overflow(), size_*(), allocation, and 2727 related functions. 2728 2729 For more information on KUnit and unit tests in general please refer 2730 to the KUnit documentation in Documentation/dev-tools/kunit/. 2731 2732 If unsure, say N. 2733 2734config STACKINIT_KUNIT_TEST 2735 tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS 2736 depends on KUNIT 2737 default KUNIT_ALL_TESTS 2738 help 2739 Test if the kernel is zero-initializing stack variables and 2740 padding. Coverage is controlled by compiler flags, 2741 CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO, 2742 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2743 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2744 2745config FORTIFY_KUNIT_TEST 2746 tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS 2747 depends on KUNIT && FORTIFY_SOURCE 2748 default KUNIT_ALL_TESTS 2749 help 2750 Builds unit tests for checking internals of FORTIFY_SOURCE as used 2751 by the str*() and mem*() family of functions. For testing runtime 2752 traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests. 2753 2754config HW_BREAKPOINT_KUNIT_TEST 2755 bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS 2756 depends on HAVE_HW_BREAKPOINT 2757 depends on KUNIT=y 2758 default KUNIT_ALL_TESTS 2759 help 2760 Tests for hw_breakpoint constraints accounting. 2761 2762 If unsure, say N. 2763 2764config STRCAT_KUNIT_TEST 2765 tristate "Test strcat() family of functions at runtime" if !KUNIT_ALL_TESTS 2766 depends on KUNIT 2767 default KUNIT_ALL_TESTS 2768 2769config STRSCPY_KUNIT_TEST 2770 tristate "Test strscpy*() family of functions at runtime" if !KUNIT_ALL_TESTS 2771 depends on KUNIT 2772 default KUNIT_ALL_TESTS 2773 2774config SIPHASH_KUNIT_TEST 2775 tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS 2776 depends on KUNIT 2777 default KUNIT_ALL_TESTS 2778 help 2779 Enable this option to test the kernel's siphash (<linux/siphash.h>) hash 2780 functions on boot (or module load). 2781 2782 This is intended to help people writing architecture-specific 2783 optimized versions. If unsure, say N. 2784 2785config TEST_UDELAY 2786 tristate "udelay test driver" 2787 help 2788 This builds the "udelay_test" module that helps to make sure 2789 that udelay() is working properly. 2790 2791 If unsure, say N. 2792 2793config TEST_STATIC_KEYS 2794 tristate "Test static keys" 2795 depends on m 2796 help 2797 Test the static key interfaces. 2798 2799 If unsure, say N. 2800 2801config TEST_DYNAMIC_DEBUG 2802 tristate "Test DYNAMIC_DEBUG" 2803 depends on DYNAMIC_DEBUG 2804 help 2805 This module registers a tracer callback to count enabled 2806 pr_debugs in a 'do_debugging' function, then alters their 2807 enablements, calls the function, and compares counts. 2808 2809 If unsure, say N. 2810 2811config TEST_KMOD 2812 tristate "kmod stress tester" 2813 depends on m 2814 depends on NETDEVICES && NET_CORE && INET # for TUN 2815 depends on BLOCK 2816 depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS 2817 select TEST_LKM 2818 select XFS_FS 2819 select TUN 2820 select BTRFS_FS 2821 help 2822 Test the kernel's module loading mechanism: kmod. kmod implements 2823 support to load modules using the Linux kernel's usermode helper. 2824 This test provides a series of tests against kmod. 2825 2826 Although technically you can either build test_kmod as a module or 2827 into the kernel we disallow building it into the kernel since 2828 it stress tests request_module() and this will very likely cause 2829 some issues by taking over precious threads available from other 2830 module load requests, ultimately this could be fatal. 2831 2832 To run tests run: 2833 2834 tools/testing/selftests/kmod/kmod.sh --help 2835 2836 If unsure, say N. 2837 2838config TEST_DEBUG_VIRTUAL 2839 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 2840 depends on DEBUG_VIRTUAL 2841 help 2842 Test the kernel's ability to detect incorrect calls to 2843 virt_to_phys() done against the non-linear part of the 2844 kernel's virtual address map. 2845 2846 If unsure, say N. 2847 2848config TEST_MEMCAT_P 2849 tristate "Test memcat_p() helper function" 2850 help 2851 Test the memcat_p() helper for correctly merging two 2852 pointer arrays together. 2853 2854 If unsure, say N. 2855 2856config TEST_LIVEPATCH 2857 tristate "Test livepatching" 2858 default n 2859 depends on DYNAMIC_DEBUG 2860 depends on LIVEPATCH 2861 depends on m 2862 help 2863 Test kernel livepatching features for correctness. The tests will 2864 load test modules that will be livepatched in various scenarios. 2865 2866 To run all the livepatching tests: 2867 2868 make -C tools/testing/selftests TARGETS=livepatch run_tests 2869 2870 Alternatively, individual tests may be invoked: 2871 2872 tools/testing/selftests/livepatch/test-callbacks.sh 2873 tools/testing/selftests/livepatch/test-livepatch.sh 2874 tools/testing/selftests/livepatch/test-shadow-vars.sh 2875 2876 If unsure, say N. 2877 2878config TEST_OBJAGG 2879 tristate "Perform selftest on object aggreration manager" 2880 default n 2881 depends on OBJAGG 2882 help 2883 Enable this option to test object aggregation manager on boot 2884 (or module load). 2885 2886config TEST_MEMINIT 2887 tristate "Test heap/page initialization" 2888 help 2889 Test if the kernel is zero-initializing heap and page allocations. 2890 This can be useful to test init_on_alloc and init_on_free features. 2891 2892 If unsure, say N. 2893 2894config TEST_HMM 2895 tristate "Test HMM (Heterogeneous Memory Management)" 2896 depends on TRANSPARENT_HUGEPAGE 2897 depends on DEVICE_PRIVATE 2898 select HMM_MIRROR 2899 select MMU_NOTIFIER 2900 help 2901 This is a pseudo device driver solely for testing HMM. 2902 Say M here if you want to build the HMM test module. 2903 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests. 2904 2905 If unsure, say N. 2906 2907config TEST_FREE_PAGES 2908 tristate "Test freeing pages" 2909 help 2910 Test that a memory leak does not occur due to a race between 2911 freeing a block of pages and a speculative page reference. 2912 Loading this module is safe if your kernel has the bug fixed. 2913 If the bug is not fixed, it will leak gigabytes of memory and 2914 probably OOM your system. 2915 2916config TEST_FPU 2917 tristate "Test floating point operations in kernel space" 2918 depends on X86 && !KCOV_INSTRUMENT_ALL 2919 help 2920 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu 2921 which will trigger a sequence of floating point operations. This is used 2922 for self-testing floating point control register setting in 2923 kernel_fpu_begin(). 2924 2925 If unsure, say N. 2926 2927config TEST_CLOCKSOURCE_WATCHDOG 2928 tristate "Test clocksource watchdog in kernel space" 2929 depends on CLOCKSOURCE_WATCHDOG 2930 help 2931 Enable this option to create a kernel module that will trigger 2932 a test of the clocksource watchdog. This module may be loaded 2933 via modprobe or insmod in which case it will run upon being 2934 loaded, or it may be built in, in which case it will run 2935 shortly after boot. 2936 2937 If unsure, say N. 2938 2939config TEST_OBJPOOL 2940 tristate "Test module for correctness and stress of objpool" 2941 default n 2942 depends on m && DEBUG_KERNEL 2943 help 2944 This builds the "test_objpool" module that should be used for 2945 correctness verification and concurrent testings of objects 2946 allocation and reclamation. 2947 2948 If unsure, say N. 2949 2950endif # RUNTIME_TESTING_MENU 2951 2952config ARCH_USE_MEMTEST 2953 bool 2954 help 2955 An architecture should select this when it uses early_memtest() 2956 during boot process. 2957 2958config MEMTEST 2959 bool "Memtest" 2960 depends on ARCH_USE_MEMTEST 2961 help 2962 This option adds a kernel parameter 'memtest', which allows memtest 2963 to be set and executed. 2964 memtest=0, mean disabled; -- default 2965 memtest=1, mean do 1 test pattern; 2966 ... 2967 memtest=17, mean do 17 test patterns. 2968 If you are unsure how to answer this question, answer N. 2969 2970 2971 2972config HYPERV_TESTING 2973 bool "Microsoft Hyper-V driver testing" 2974 default n 2975 depends on HYPERV && DEBUG_FS 2976 help 2977 Select this option to enable Hyper-V vmbus testing. 2978 2979endmenu # "Kernel Testing and Coverage" 2980 2981menu "Rust hacking" 2982 2983config RUST_DEBUG_ASSERTIONS 2984 bool "Debug assertions" 2985 depends on RUST 2986 help 2987 Enables rustc's `-Cdebug-assertions` codegen option. 2988 2989 This flag lets you turn `cfg(debug_assertions)` conditional 2990 compilation on or off. This can be used to enable extra debugging 2991 code in development but not in production. For example, it controls 2992 the behavior of the standard library's `debug_assert!` macro. 2993 2994 Note that this will apply to all Rust code, including `core`. 2995 2996 If unsure, say N. 2997 2998config RUST_OVERFLOW_CHECKS 2999 bool "Overflow checks" 3000 default y 3001 depends on RUST 3002 help 3003 Enables rustc's `-Coverflow-checks` codegen option. 3004 3005 This flag allows you to control the behavior of runtime integer 3006 overflow. When overflow-checks are enabled, a Rust panic will occur 3007 on overflow. 3008 3009 Note that this will apply to all Rust code, including `core`. 3010 3011 If unsure, say Y. 3012 3013config RUST_BUILD_ASSERT_ALLOW 3014 bool "Allow unoptimized build-time assertions" 3015 depends on RUST 3016 help 3017 Controls how are `build_error!` and `build_assert!` handled during build. 3018 3019 If calls to them exist in the binary, it may indicate a violated invariant 3020 or that the optimizer failed to verify the invariant during compilation. 3021 3022 This should not happen, thus by default the build is aborted. However, 3023 as an escape hatch, you can choose Y here to ignore them during build 3024 and let the check be carried at runtime (with `panic!` being called if 3025 the check fails). 3026 3027 If unsure, say N. 3028 3029config RUST_KERNEL_DOCTESTS 3030 bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS 3031 depends on RUST && KUNIT=y 3032 default KUNIT_ALL_TESTS 3033 help 3034 This builds the documentation tests of the `kernel` crate 3035 as KUnit tests. 3036 3037 For more information on KUnit and unit tests in general, 3038 please refer to the KUnit documentation in Documentation/dev-tools/kunit/. 3039 3040 If unsure, say N. 3041 3042endmenu # "Rust" 3043 3044endmenu # Kernel hacking 3045