1# SPDX-License-Identifier: GPL-2.0-only 2menu "Kernel hacking" 3 4menu "printk and dmesg options" 5 6config PRINTK_TIME 7 bool "Show timing information on printks" 8 depends on PRINTK 9 help 10 Selecting this option causes time stamps of the printk() 11 messages to be added to the output of the syslog() system 12 call and at the console. 13 14 The timestamp is always recorded internally, and exported 15 to /dev/kmsg. This flag just specifies if the timestamp should 16 be included, not that the timestamp is recorded. 17 18 The behavior is also controlled by the kernel command line 19 parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst 20 21config PRINTK_CALLER 22 bool "Show caller information on printks" 23 depends on PRINTK 24 help 25 Selecting this option causes printk() to add a caller "thread id" (if 26 in task context) or a caller "processor id" (if not in task context) 27 to every message. 28 29 This option is intended for environments where multiple threads 30 concurrently call printk() for many times, for it is difficult to 31 interpret without knowing where these lines (or sometimes individual 32 line which was divided into multiple lines due to race) came from. 33 34 Since toggling after boot makes the code racy, currently there is 35 no option to enable/disable at the kernel command line parameter or 36 sysfs interface. 37 38config STACKTRACE_BUILD_ID 39 bool "Show build ID information in stacktraces" 40 depends on PRINTK 41 help 42 Selecting this option adds build ID information for symbols in 43 stacktraces printed with the printk format '%p[SR]b'. 44 45 This option is intended for distros where debuginfo is not easily 46 accessible but can be downloaded given the build ID of the vmlinux or 47 kernel module where the function is located. 48 49config CONSOLE_LOGLEVEL_DEFAULT 50 int "Default console loglevel (1-15)" 51 range 1 15 52 default "7" 53 help 54 Default loglevel to determine what will be printed on the console. 55 56 Setting a default here is equivalent to passing in loglevel=<x> in 57 the kernel bootargs. loglevel=<x> continues to override whatever 58 value is specified here as well. 59 60 Note: This does not affect the log level of un-prefixed printk() 61 usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT 62 option. 63 64config CONSOLE_LOGLEVEL_QUIET 65 int "quiet console loglevel (1-15)" 66 range 1 15 67 default "4" 68 help 69 loglevel to use when "quiet" is passed on the kernel commandline. 70 71 When "quiet" is passed on the kernel commandline this loglevel 72 will be used as the loglevel. IOW passing "quiet" will be the 73 equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>" 74 75config MESSAGE_LOGLEVEL_DEFAULT 76 int "Default message log level (1-7)" 77 range 1 7 78 default "4" 79 help 80 Default log level for printk statements with no specified priority. 81 82 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks 83 that are auditing their logs closely may want to set it to a lower 84 priority. 85 86 Note: This does not affect what message level gets printed on the console 87 by default. To change that, use loglevel=<x> in the kernel bootargs, 88 or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value. 89 90config BOOT_PRINTK_DELAY 91 bool "Delay each boot printk message by N milliseconds" 92 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY 93 help 94 This build option allows you to read kernel boot messages 95 by inserting a short delay after each one. The delay is 96 specified in milliseconds on the kernel command line, 97 using "boot_delay=N". 98 99 It is likely that you would also need to use "lpj=M" to preset 100 the "loops per jiffie" value. 101 See a previous boot log for the "lpj" value to use for your 102 system, and then set "lpj=M" before setting "boot_delay=N". 103 NOTE: Using this option may adversely affect SMP systems. 104 I.e., processors other than the first one may not boot up. 105 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect 106 what it believes to be lockup conditions. 107 108config DYNAMIC_DEBUG 109 bool "Enable dynamic printk() support" 110 default n 111 depends on PRINTK 112 depends on (DEBUG_FS || PROC_FS) 113 select DYNAMIC_DEBUG_CORE 114 help 115 116 Compiles debug level messages into the kernel, which would not 117 otherwise be available at runtime. These messages can then be 118 enabled/disabled based on various levels of scope - per source file, 119 function, module, format string, and line number. This mechanism 120 implicitly compiles in all pr_debug() and dev_dbg() calls, which 121 enlarges the kernel text size by about 2%. 122 123 If a source file is compiled with DEBUG flag set, any 124 pr_debug() calls in it are enabled by default, but can be 125 disabled at runtime as below. Note that DEBUG flag is 126 turned on by many CONFIG_*DEBUG* options. 127 128 Usage: 129 130 Dynamic debugging is controlled via the 'dynamic_debug/control' file, 131 which is contained in the 'debugfs' filesystem or procfs. 132 Thus, the debugfs or procfs filesystem must first be mounted before 133 making use of this feature. 134 We refer the control file as: <debugfs>/dynamic_debug/control. This 135 file contains a list of the debug statements that can be enabled. The 136 format for each line of the file is: 137 138 filename:lineno [module]function flags format 139 140 filename : source file of the debug statement 141 lineno : line number of the debug statement 142 module : module that contains the debug statement 143 function : function that contains the debug statement 144 flags : '=p' means the line is turned 'on' for printing 145 format : the format used for the debug statement 146 147 From a live system: 148 149 nullarbor:~ # cat <debugfs>/dynamic_debug/control 150 # filename:lineno [module]function flags format 151 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012" 152 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012" 153 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012" 154 155 Example usage: 156 157 // enable the message at line 1603 of file svcsock.c 158 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' > 159 <debugfs>/dynamic_debug/control 160 161 // enable all the messages in file svcsock.c 162 nullarbor:~ # echo -n 'file svcsock.c +p' > 163 <debugfs>/dynamic_debug/control 164 165 // enable all the messages in the NFS server module 166 nullarbor:~ # echo -n 'module nfsd +p' > 167 <debugfs>/dynamic_debug/control 168 169 // enable all 12 messages in the function svc_process() 170 nullarbor:~ # echo -n 'func svc_process +p' > 171 <debugfs>/dynamic_debug/control 172 173 // disable all 12 messages in the function svc_process() 174 nullarbor:~ # echo -n 'func svc_process -p' > 175 <debugfs>/dynamic_debug/control 176 177 See Documentation/admin-guide/dynamic-debug-howto.rst for additional 178 information. 179 180config DYNAMIC_DEBUG_CORE 181 bool "Enable core function of dynamic debug support" 182 depends on PRINTK 183 depends on (DEBUG_FS || PROC_FS) 184 help 185 Enable core functional support of dynamic debug. It is useful 186 when you want to tie dynamic debug to your kernel modules with 187 DYNAMIC_DEBUG_MODULE defined for each of them, especially for 188 the case of embedded system where the kernel image size is 189 sensitive for people. 190 191config SYMBOLIC_ERRNAME 192 bool "Support symbolic error names in printf" 193 default y if PRINTK 194 help 195 If you say Y here, the kernel's printf implementation will 196 be able to print symbolic error names such as ENOSPC instead 197 of the number 28. It makes the kernel image slightly larger 198 (about 3KB), but can make the kernel logs easier to read. 199 200config DEBUG_BUGVERBOSE 201 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT 202 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE) 203 default y 204 help 205 Say Y here to make BUG() panics output the file name and line number 206 of the BUG call as well as the EIP and oops trace. This aids 207 debugging but costs about 70-100K of memory. 208 209endmenu # "printk and dmesg options" 210 211config DEBUG_KERNEL 212 bool "Kernel debugging" 213 help 214 Say Y here if you are developing drivers or trying to debug and 215 identify kernel problems. 216 217config DEBUG_MISC 218 bool "Miscellaneous debug code" 219 default DEBUG_KERNEL 220 depends on DEBUG_KERNEL 221 help 222 Say Y here if you need to enable miscellaneous debug code that should 223 be under a more specific debug option but isn't. 224 225menu "Compile-time checks and compiler options" 226 227config DEBUG_INFO 228 bool 229 help 230 A kernel debug info option other than "None" has been selected 231 in the "Debug information" choice below, indicating that debug 232 information will be generated for build targets. 233 234# Clang is known to generate .{s,u}leb128 with symbol deltas with DWARF5, which 235# some targets may not support: https://sourceware.org/bugzilla/show_bug.cgi?id=27215 236config AS_HAS_NON_CONST_LEB128 237 def_bool $(as-instr,.uleb128 .Lexpr_end4 - .Lexpr_start3\n.Lexpr_start3:\n.Lexpr_end4:) 238 239choice 240 prompt "Debug information" 241 depends on DEBUG_KERNEL 242 help 243 Selecting something other than "None" results in a kernel image 244 that will include debugging info resulting in a larger kernel image. 245 This adds debug symbols to the kernel and modules (gcc -g), and 246 is needed if you intend to use kernel crashdump or binary object 247 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 248 249 Choose which version of DWARF debug info to emit. If unsure, 250 select "Toolchain default". 251 252config DEBUG_INFO_NONE 253 bool "Disable debug information" 254 help 255 Do not build the kernel with debugging information, which will 256 result in a faster and smaller build. 257 258config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT 259 bool "Rely on the toolchain's implicit default DWARF version" 260 select DEBUG_INFO 261 depends on !CC_IS_CLANG || AS_IS_LLVM || CLANG_VERSION < 140000 || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_LEB128) 262 help 263 The implicit default version of DWARF debug info produced by a 264 toolchain changes over time. 265 266 This can break consumers of the debug info that haven't upgraded to 267 support newer revisions, and prevent testing newer versions, but 268 those should be less common scenarios. 269 270config DEBUG_INFO_DWARF4 271 bool "Generate DWARF Version 4 debuginfo" 272 select DEBUG_INFO 273 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502) 274 help 275 Generate DWARF v4 debug info. This requires gcc 4.5+, binutils 2.35.2 276 if using clang without clang's integrated assembler, and gdb 7.0+. 277 278 If you have consumers of DWARF debug info that are not ready for 279 newer revisions of DWARF, you may wish to choose this or have your 280 config select this. 281 282config DEBUG_INFO_DWARF5 283 bool "Generate DWARF Version 5 debuginfo" 284 select DEBUG_INFO 285 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_LEB128) 286 help 287 Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc 288 5.0+ accepts the -gdwarf-5 flag but only had partial support for some 289 draft features until 7.0), and gdb 8.0+. 290 291 Changes to the structure of debug info in Version 5 allow for around 292 15-18% savings in resulting image and debug info section sizes as 293 compared to DWARF Version 4. DWARF Version 5 standardizes previous 294 extensions such as accelerators for symbol indexing and the format 295 for fission (.dwo/.dwp) files. Users may not want to select this 296 config if they rely on tooling that has not yet been updated to 297 support DWARF Version 5. 298 299endchoice # "Debug information" 300 301if DEBUG_INFO 302 303config DEBUG_INFO_REDUCED 304 bool "Reduce debugging information" 305 help 306 If you say Y here gcc is instructed to generate less debugging 307 information for structure types. This means that tools that 308 need full debugging information (like kgdb or systemtap) won't 309 be happy. But if you merely need debugging information to 310 resolve line numbers there is no loss. Advantage is that 311 build directory object sizes shrink dramatically over a full 312 DEBUG_INFO build and compile times are reduced too. 313 Only works with newer gcc versions. 314 315choice 316 prompt "Compressed Debug information" 317 help 318 Compress the resulting debug info. Results in smaller debug info sections, 319 but requires that consumers are able to decompress the results. 320 321 If unsure, choose DEBUG_INFO_COMPRESSED_NONE. 322 323config DEBUG_INFO_COMPRESSED_NONE 324 bool "Don't compress debug information" 325 help 326 Don't compress debug info sections. 327 328config DEBUG_INFO_COMPRESSED_ZLIB 329 bool "Compress debugging information with zlib" 330 depends on $(cc-option,-gz=zlib) 331 depends on $(ld-option,--compress-debug-sections=zlib) 332 help 333 Compress the debug information using zlib. Requires GCC 5.0+ or Clang 334 5.0+, binutils 2.26+, and zlib. 335 336 Users of dpkg-deb via scripts/package/builddeb may find an increase in 337 size of their debug .deb packages with this config set, due to the 338 debug info being compressed with zlib, then the object files being 339 recompressed with a different compression scheme. But this is still 340 preferable to setting $KDEB_COMPRESS to "none" which would be even 341 larger. 342 343config DEBUG_INFO_COMPRESSED_ZSTD 344 bool "Compress debugging information with zstd" 345 depends on $(cc-option,-gz=zstd) 346 depends on $(ld-option,--compress-debug-sections=zstd) 347 help 348 Compress the debug information using zstd. This may provide better 349 compression than zlib, for about the same time costs, but requires newer 350 toolchain support. Requires GCC 13.0+ or Clang 16.0+, binutils 2.40+, and 351 zstd. 352 353endchoice # "Compressed Debug information" 354 355config DEBUG_INFO_SPLIT 356 bool "Produce split debuginfo in .dwo files" 357 depends on $(cc-option,-gsplit-dwarf) 358 # RISC-V linker relaxation + -gsplit-dwarf has issues with LLVM and GCC 359 # prior to 12.x: 360 # https://github.com/llvm/llvm-project/issues/56642 361 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99090 362 depends on !RISCV || GCC_VERSION >= 120000 363 help 364 Generate debug info into separate .dwo files. This significantly 365 reduces the build directory size for builds with DEBUG_INFO, 366 because it stores the information only once on disk in .dwo 367 files instead of multiple times in object files and executables. 368 In addition the debug information is also compressed. 369 370 Requires recent gcc (4.7+) and recent gdb/binutils. 371 Any tool that packages or reads debug information would need 372 to know about the .dwo files and include them. 373 Incompatible with older versions of ccache. 374 375config DEBUG_INFO_BTF 376 bool "Generate BTF typeinfo" 377 depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED 378 depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST 379 depends on BPF_SYSCALL 380 depends on !DEBUG_INFO_DWARF5 || PAHOLE_VERSION >= 121 381 help 382 Generate deduplicated BTF type information from DWARF debug info. 383 Turning this on expects presence of pahole tool, which will convert 384 DWARF type info into equivalent deduplicated BTF type info. 385 386config PAHOLE_HAS_SPLIT_BTF 387 def_bool PAHOLE_VERSION >= 119 388 389config PAHOLE_HAS_BTF_TAG 390 def_bool PAHOLE_VERSION >= 123 391 depends on CC_IS_CLANG 392 help 393 Decide whether pahole emits btf_tag attributes (btf_type_tag and 394 btf_decl_tag) or not. Currently only clang compiler implements 395 these attributes, so make the config depend on CC_IS_CLANG. 396 397config PAHOLE_HAS_LANG_EXCLUDE 398 def_bool PAHOLE_VERSION >= 124 399 help 400 Support for the --lang_exclude flag which makes pahole exclude 401 compilation units from the supplied language. Used in Kbuild to 402 omit Rust CUs which are not supported in version 1.24 of pahole, 403 otherwise it would emit malformed kernel and module binaries when 404 using DEBUG_INFO_BTF_MODULES. 405 406config DEBUG_INFO_BTF_MODULES 407 def_bool y 408 depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF 409 help 410 Generate compact split BTF type information for kernel modules. 411 412config MODULE_ALLOW_BTF_MISMATCH 413 bool "Allow loading modules with non-matching BTF type info" 414 depends on DEBUG_INFO_BTF_MODULES 415 help 416 For modules whose split BTF does not match vmlinux, load without 417 BTF rather than refusing to load. The default behavior with 418 module BTF enabled is to reject modules with such mismatches; 419 this option will still load module BTF where possible but ignore 420 it when a mismatch is found. 421 422config GDB_SCRIPTS 423 bool "Provide GDB scripts for kernel debugging" 424 help 425 This creates the required links to GDB helper scripts in the 426 build directory. If you load vmlinux into gdb, the helper 427 scripts will be automatically imported by gdb as well, and 428 additional functions are available to analyze a Linux kernel 429 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst 430 for further details. 431 432endif # DEBUG_INFO 433 434config FRAME_WARN 435 int "Warn for stack frames larger than" 436 range 0 8192 437 default 0 if KMSAN 438 default 2048 if GCC_PLUGIN_LATENT_ENTROPY 439 default 2048 if PARISC 440 default 1536 if (!64BIT && XTENSA) 441 default 1280 if KASAN && !64BIT 442 default 1024 if !64BIT 443 default 2048 if 64BIT 444 help 445 Tell the compiler to warn at build time for stack frames larger than this. 446 Setting this too low will cause a lot of warnings. 447 Setting it to 0 disables the warning. 448 449config STRIP_ASM_SYMS 450 bool "Strip assembler-generated symbols during link" 451 default n 452 help 453 Strip internal assembler-generated symbols during a link (symbols 454 that look like '.Lxxx') so they don't pollute the output of 455 get_wchan() and suchlike. 456 457config READABLE_ASM 458 bool "Generate readable assembler code" 459 depends on DEBUG_KERNEL 460 depends on CC_IS_GCC 461 help 462 Disable some compiler optimizations that tend to generate human unreadable 463 assembler output. This may make the kernel slightly slower, but it helps 464 to keep kernel developers who have to stare a lot at assembler listings 465 sane. 466 467config HEADERS_INSTALL 468 bool "Install uapi headers to usr/include" 469 depends on !UML 470 help 471 This option will install uapi headers (headers exported to user-space) 472 into the usr/include directory for use during the kernel build. 473 This is unneeded for building the kernel itself, but needed for some 474 user-space program samples. It is also needed by some features such 475 as uapi header sanity checks. 476 477config DEBUG_SECTION_MISMATCH 478 bool "Enable full Section mismatch analysis" 479 depends on CC_IS_GCC 480 help 481 The section mismatch analysis checks if there are illegal 482 references from one section to another section. 483 During linktime or runtime, some sections are dropped; 484 any use of code/data previously in these sections would 485 most likely result in an oops. 486 In the code, functions and variables are annotated with 487 __init,, etc. (see the full list in include/linux/init.h), 488 which results in the code/data being placed in specific sections. 489 The section mismatch analysis is always performed after a full 490 kernel build, and enabling this option causes the following 491 additional step to occur: 492 - Add the option -fno-inline-functions-called-once to gcc commands. 493 When inlining a function annotated with __init in a non-init 494 function, we would lose the section information and thus 495 the analysis would not catch the illegal reference. 496 This option tells gcc to inline less (but it does result in 497 a larger kernel). 498 499config SECTION_MISMATCH_WARN_ONLY 500 bool "Make section mismatch errors non-fatal" 501 default y 502 help 503 If you say N here, the build process will fail if there are any 504 section mismatch, instead of just throwing warnings. 505 506 If unsure, say Y. 507 508config DEBUG_FORCE_FUNCTION_ALIGN_64B 509 bool "Force all function address 64B aligned" 510 depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC || RISCV || S390) 511 select FUNCTION_ALIGNMENT_64B 512 help 513 There are cases that a commit from one domain changes the function 514 address alignment of other domains, and cause magic performance 515 bump (regression or improvement). Enable this option will help to 516 verify if the bump is caused by function alignment changes, while 517 it will slightly increase the kernel size and affect icache usage. 518 519 It is mainly for debug and performance tuning use. 520 521# 522# Select this config option from the architecture Kconfig, if it 523# is preferred to always offer frame pointers as a config 524# option on the architecture (regardless of KERNEL_DEBUG): 525# 526config ARCH_WANT_FRAME_POINTERS 527 bool 528 529config FRAME_POINTER 530 bool "Compile the kernel with frame pointers" 531 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS 532 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 533 help 534 If you say Y here the resulting kernel image will be slightly 535 larger and slower, but it gives very useful debugging information 536 in case of kernel bugs. (precise oopses/stacktraces/warnings) 537 538config OBJTOOL 539 bool 540 541config STACK_VALIDATION 542 bool "Compile-time stack metadata validation" 543 depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER 544 select OBJTOOL 545 default n 546 help 547 Validate frame pointer rules at compile-time. This helps ensure that 548 runtime stack traces are more reliable. 549 550 For more information, see 551 tools/objtool/Documentation/objtool.txt. 552 553config NOINSTR_VALIDATION 554 bool 555 depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY 556 select OBJTOOL 557 default y 558 559config VMLINUX_MAP 560 bool "Generate vmlinux.map file when linking" 561 depends on EXPERT 562 help 563 Selecting this option will pass "-Map=vmlinux.map" to ld 564 when linking vmlinux. That file can be useful for verifying 565 and debugging magic section games, and for seeing which 566 pieces of code get eliminated with 567 CONFIG_LD_DEAD_CODE_DATA_ELIMINATION. 568 569config DEBUG_FORCE_WEAK_PER_CPU 570 bool "Force weak per-cpu definitions" 571 depends on DEBUG_KERNEL 572 help 573 s390 and alpha require percpu variables in modules to be 574 defined weak to work around addressing range issue which 575 puts the following two restrictions on percpu variable 576 definitions. 577 578 1. percpu symbols must be unique whether static or not 579 2. percpu variables can't be defined inside a function 580 581 To ensure that generic code follows the above rules, this 582 option forces all percpu variables to be defined as weak. 583 584endmenu # "Compiler options" 585 586menu "Generic Kernel Debugging Instruments" 587 588config MAGIC_SYSRQ 589 bool "Magic SysRq key" 590 depends on !UML 591 help 592 If you say Y here, you will have some control over the system even 593 if the system crashes for example during kernel debugging (e.g., you 594 will be able to flush the buffer cache to disk, reboot the system 595 immediately or dump some status information). This is accomplished 596 by pressing various keys while holding SysRq (Alt+PrintScreen). It 597 also works on a serial console (on PC hardware at least), if you 598 send a BREAK and then within 5 seconds a command keypress. The 599 keys are documented in <file:Documentation/admin-guide/sysrq.rst>. 600 Don't say Y unless you really know what this hack does. 601 602config MAGIC_SYSRQ_DEFAULT_ENABLE 603 hex "Enable magic SysRq key functions by default" 604 depends on MAGIC_SYSRQ 605 default 0x1 606 help 607 Specifies which SysRq key functions are enabled by default. 608 This may be set to 1 or 0 to enable or disable them all, or 609 to a bitmask as described in Documentation/admin-guide/sysrq.rst. 610 611config MAGIC_SYSRQ_SERIAL 612 bool "Enable magic SysRq key over serial" 613 depends on MAGIC_SYSRQ 614 default y 615 help 616 Many embedded boards have a disconnected TTL level serial which can 617 generate some garbage that can lead to spurious false sysrq detects. 618 This option allows you to decide whether you want to enable the 619 magic SysRq key. 620 621config MAGIC_SYSRQ_SERIAL_SEQUENCE 622 string "Char sequence that enables magic SysRq over serial" 623 depends on MAGIC_SYSRQ_SERIAL 624 default "" 625 help 626 Specifies a sequence of characters that can follow BREAK to enable 627 SysRq on a serial console. 628 629 If unsure, leave an empty string and the option will not be enabled. 630 631config DEBUG_FS 632 bool "Debug Filesystem" 633 help 634 debugfs is a virtual file system that kernel developers use to put 635 debugging files into. Enable this option to be able to read and 636 write to these files. 637 638 For detailed documentation on the debugfs API, see 639 Documentation/filesystems/. 640 641 If unsure, say N. 642 643choice 644 prompt "Debugfs default access" 645 depends on DEBUG_FS 646 default DEBUG_FS_ALLOW_ALL 647 help 648 This selects the default access restrictions for debugfs. 649 It can be overridden with kernel command line option 650 debugfs=[on,no-mount,off]. The restrictions apply for API access 651 and filesystem registration. 652 653config DEBUG_FS_ALLOW_ALL 654 bool "Access normal" 655 help 656 No restrictions apply. Both API and filesystem registration 657 is on. This is the normal default operation. 658 659config DEBUG_FS_DISALLOW_MOUNT 660 bool "Do not register debugfs as filesystem" 661 help 662 The API is open but filesystem is not loaded. Clients can still do 663 their work and read with debug tools that do not need 664 debugfs filesystem. 665 666config DEBUG_FS_ALLOW_NONE 667 bool "No access" 668 help 669 Access is off. Clients get -PERM when trying to create nodes in 670 debugfs tree and debugfs is not registered as a filesystem. 671 Client can then back-off or continue without debugfs access. 672 673endchoice 674 675source "lib/Kconfig.kgdb" 676source "lib/Kconfig.ubsan" 677source "lib/Kconfig.kcsan" 678 679endmenu 680 681menu "Networking Debugging" 682 683source "net/Kconfig.debug" 684 685endmenu # "Networking Debugging" 686 687menu "Memory Debugging" 688 689source "mm/Kconfig.debug" 690 691config DEBUG_OBJECTS 692 bool "Debug object operations" 693 depends on DEBUG_KERNEL 694 help 695 If you say Y here, additional code will be inserted into the 696 kernel to track the life time of various objects and validate 697 the operations on those objects. 698 699config DEBUG_OBJECTS_SELFTEST 700 bool "Debug objects selftest" 701 depends on DEBUG_OBJECTS 702 help 703 This enables the selftest of the object debug code. 704 705config DEBUG_OBJECTS_FREE 706 bool "Debug objects in freed memory" 707 depends on DEBUG_OBJECTS 708 help 709 This enables checks whether a k/v free operation frees an area 710 which contains an object which has not been deactivated 711 properly. This can make kmalloc/kfree-intensive workloads 712 much slower. 713 714config DEBUG_OBJECTS_TIMERS 715 bool "Debug timer objects" 716 depends on DEBUG_OBJECTS 717 help 718 If you say Y here, additional code will be inserted into the 719 timer routines to track the life time of timer objects and 720 validate the timer operations. 721 722config DEBUG_OBJECTS_WORK 723 bool "Debug work objects" 724 depends on DEBUG_OBJECTS 725 help 726 If you say Y here, additional code will be inserted into the 727 work queue routines to track the life time of work objects and 728 validate the work operations. 729 730config DEBUG_OBJECTS_RCU_HEAD 731 bool "Debug RCU callbacks objects" 732 depends on DEBUG_OBJECTS 733 help 734 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 735 736config DEBUG_OBJECTS_PERCPU_COUNTER 737 bool "Debug percpu counter objects" 738 depends on DEBUG_OBJECTS 739 help 740 If you say Y here, additional code will be inserted into the 741 percpu counter routines to track the life time of percpu counter 742 objects and validate the percpu counter operations. 743 744config DEBUG_OBJECTS_ENABLE_DEFAULT 745 int "debug_objects bootup default value (0-1)" 746 range 0 1 747 default "1" 748 depends on DEBUG_OBJECTS 749 help 750 Debug objects boot parameter default value 751 752config SHRINKER_DEBUG 753 bool "Enable shrinker debugging support" 754 depends on DEBUG_FS 755 help 756 Say Y to enable the shrinker debugfs interface which provides 757 visibility into the kernel memory shrinkers subsystem. 758 Disable it to avoid an extra memory footprint. 759 760config DEBUG_STACK_USAGE 761 bool "Stack utilization instrumentation" 762 depends on DEBUG_KERNEL && !IA64 763 help 764 Enables the display of the minimum amount of free stack which each 765 task has ever had available in the sysrq-T and sysrq-P debug output. 766 767 This option will slow down process creation somewhat. 768 769config SCHED_STACK_END_CHECK 770 bool "Detect stack corruption on calls to schedule()" 771 depends on DEBUG_KERNEL 772 default n 773 help 774 This option checks for a stack overrun on calls to schedule(). 775 If the stack end location is found to be over written always panic as 776 the content of the corrupted region can no longer be trusted. 777 This is to ensure no erroneous behaviour occurs which could result in 778 data corruption or a sporadic crash at a later stage once the region 779 is examined. The runtime overhead introduced is minimal. 780 781config ARCH_HAS_DEBUG_VM_PGTABLE 782 bool 783 help 784 An architecture should select this when it can successfully 785 build and run DEBUG_VM_PGTABLE. 786 787config DEBUG_VM_IRQSOFF 788 def_bool DEBUG_VM && !PREEMPT_RT 789 790config DEBUG_VM 791 bool "Debug VM" 792 depends on DEBUG_KERNEL 793 help 794 Enable this to turn on extended checks in the virtual-memory system 795 that may impact performance. 796 797 If unsure, say N. 798 799config DEBUG_VM_SHOOT_LAZIES 800 bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation" 801 depends on DEBUG_VM 802 depends on MMU_LAZY_TLB_SHOOTDOWN 803 help 804 Enable additional IPIs that ensure lazy tlb mm references are removed 805 before the mm is freed. 806 807 If unsure, say N. 808 809config DEBUG_VM_MAPLE_TREE 810 bool "Debug VM maple trees" 811 depends on DEBUG_VM 812 select DEBUG_MAPLE_TREE 813 help 814 Enable VM maple tree debugging information and extra validations. 815 816 If unsure, say N. 817 818config DEBUG_VM_RB 819 bool "Debug VM red-black trees" 820 depends on DEBUG_VM 821 help 822 Enable VM red-black tree debugging information and extra validations. 823 824 If unsure, say N. 825 826config DEBUG_VM_PGFLAGS 827 bool "Debug page-flags operations" 828 depends on DEBUG_VM 829 help 830 Enables extra validation on page flags operations. 831 832 If unsure, say N. 833 834config DEBUG_VM_PGTABLE 835 bool "Debug arch page table for semantics compliance" 836 depends on MMU 837 depends on ARCH_HAS_DEBUG_VM_PGTABLE 838 default y if DEBUG_VM 839 help 840 This option provides a debug method which can be used to test 841 architecture page table helper functions on various platforms in 842 verifying if they comply with expected generic MM semantics. This 843 will help architecture code in making sure that any changes or 844 new additions of these helpers still conform to expected 845 semantics of the generic MM. Platforms will have to opt in for 846 this through ARCH_HAS_DEBUG_VM_PGTABLE. 847 848 If unsure, say N. 849 850config ARCH_HAS_DEBUG_VIRTUAL 851 bool 852 853config DEBUG_VIRTUAL 854 bool "Debug VM translations" 855 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL 856 help 857 Enable some costly sanity checks in virtual to page code. This can 858 catch mistakes with virt_to_page() and friends. 859 860 If unsure, say N. 861 862config DEBUG_NOMMU_REGIONS 863 bool "Debug the global anon/private NOMMU mapping region tree" 864 depends on DEBUG_KERNEL && !MMU 865 help 866 This option causes the global tree of anonymous and private mapping 867 regions to be regularly checked for invalid topology. 868 869config DEBUG_MEMORY_INIT 870 bool "Debug memory initialisation" if EXPERT 871 default !EXPERT 872 help 873 Enable this for additional checks during memory initialisation. 874 The sanity checks verify aspects of the VM such as the memory model 875 and other information provided by the architecture. Verbose 876 information will be printed at KERN_DEBUG loglevel depending 877 on the mminit_loglevel= command-line option. 878 879 If unsure, say Y 880 881config MEMORY_NOTIFIER_ERROR_INJECT 882 tristate "Memory hotplug notifier error injection module" 883 depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION 884 help 885 This option provides the ability to inject artificial errors to 886 memory hotplug notifier chain callbacks. It is controlled through 887 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 888 889 If the notifier call chain should be failed with some events 890 notified, write the error code to "actions/<notifier event>/error". 891 892 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 893 894 # cd /sys/kernel/debug/notifier-error-inject/memory 895 # echo -12 > actions/MEM_GOING_OFFLINE/error 896 # echo offline > /sys/devices/system/memory/memoryXXX/state 897 bash: echo: write error: Cannot allocate memory 898 899 To compile this code as a module, choose M here: the module will 900 be called memory-notifier-error-inject. 901 902 If unsure, say N. 903 904config DEBUG_PER_CPU_MAPS 905 bool "Debug access to per_cpu maps" 906 depends on DEBUG_KERNEL 907 depends on SMP 908 help 909 Say Y to verify that the per_cpu map being accessed has 910 been set up. This adds a fair amount of code to kernel memory 911 and decreases performance. 912 913 Say N if unsure. 914 915config DEBUG_KMAP_LOCAL 916 bool "Debug kmap_local temporary mappings" 917 depends on DEBUG_KERNEL && KMAP_LOCAL 918 help 919 This option enables additional error checking for the kmap_local 920 infrastructure. Disable for production use. 921 922config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 923 bool 924 925config DEBUG_KMAP_LOCAL_FORCE_MAP 926 bool "Enforce kmap_local temporary mappings" 927 depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 928 select KMAP_LOCAL 929 select DEBUG_KMAP_LOCAL 930 help 931 This option enforces temporary mappings through the kmap_local 932 mechanism for non-highmem pages and on non-highmem systems. 933 Disable this for production systems! 934 935config DEBUG_HIGHMEM 936 bool "Highmem debugging" 937 depends on DEBUG_KERNEL && HIGHMEM 938 select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 939 select DEBUG_KMAP_LOCAL 940 help 941 This option enables additional error checking for high memory 942 systems. Disable for production systems. 943 944config HAVE_DEBUG_STACKOVERFLOW 945 bool 946 947config DEBUG_STACKOVERFLOW 948 bool "Check for stack overflows" 949 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 950 help 951 Say Y here if you want to check for overflows of kernel, IRQ 952 and exception stacks (if your architecture uses them). This 953 option will show detailed messages if free stack space drops 954 below a certain limit. 955 956 These kinds of bugs usually occur when call-chains in the 957 kernel get too deep, especially when interrupts are 958 involved. 959 960 Use this in cases where you see apparently random memory 961 corruption, especially if it appears in 'struct thread_info' 962 963 If in doubt, say "N". 964 965source "lib/Kconfig.kasan" 966source "lib/Kconfig.kfence" 967source "lib/Kconfig.kmsan" 968 969endmenu # "Memory Debugging" 970 971config DEBUG_SHIRQ 972 bool "Debug shared IRQ handlers" 973 depends on DEBUG_KERNEL 974 help 975 Enable this to generate a spurious interrupt just before a shared 976 interrupt handler is deregistered (generating one when registering 977 is currently disabled). Drivers need to handle this correctly. Some 978 don't and need to be caught. 979 980menu "Debug Oops, Lockups and Hangs" 981 982config PANIC_ON_OOPS 983 bool "Panic on Oops" 984 help 985 Say Y here to enable the kernel to panic when it oopses. This 986 has the same effect as setting oops=panic on the kernel command 987 line. 988 989 This feature is useful to ensure that the kernel does not do 990 anything erroneous after an oops which could result in data 991 corruption or other issues. 992 993 Say N if unsure. 994 995config PANIC_ON_OOPS_VALUE 996 int 997 range 0 1 998 default 0 if !PANIC_ON_OOPS 999 default 1 if PANIC_ON_OOPS 1000 1001config PANIC_TIMEOUT 1002 int "panic timeout" 1003 default 0 1004 help 1005 Set the timeout value (in seconds) until a reboot occurs when 1006 the kernel panics. If n = 0, then we wait forever. A timeout 1007 value n > 0 will wait n seconds before rebooting, while a timeout 1008 value n < 0 will reboot immediately. 1009 1010config LOCKUP_DETECTOR 1011 bool 1012 1013config SOFTLOCKUP_DETECTOR 1014 bool "Detect Soft Lockups" 1015 depends on DEBUG_KERNEL && !S390 1016 select LOCKUP_DETECTOR 1017 help 1018 Say Y here to enable the kernel to act as a watchdog to detect 1019 soft lockups. 1020 1021 Softlockups are bugs that cause the kernel to loop in kernel 1022 mode for more than 20 seconds, without giving other tasks a 1023 chance to run. The current stack trace is displayed upon 1024 detection and the system will stay locked up. 1025 1026config BOOTPARAM_SOFTLOCKUP_PANIC 1027 bool "Panic (Reboot) On Soft Lockups" 1028 depends on SOFTLOCKUP_DETECTOR 1029 help 1030 Say Y here to enable the kernel to panic on "soft lockups", 1031 which are bugs that cause the kernel to loop in kernel 1032 mode for more than 20 seconds (configurable using the watchdog_thresh 1033 sysctl), without giving other tasks a chance to run. 1034 1035 The panic can be used in combination with panic_timeout, 1036 to cause the system to reboot automatically after a 1037 lockup has been detected. This feature is useful for 1038 high-availability systems that have uptime guarantees and 1039 where a lockup must be resolved ASAP. 1040 1041 Say N if unsure. 1042 1043config HAVE_HARDLOCKUP_DETECTOR_BUDDY 1044 bool 1045 depends on SMP 1046 default y 1047 1048# 1049# Global switch whether to build a hardlockup detector at all. It is available 1050# only when the architecture supports at least one implementation. There are 1051# two exceptions. The hardlockup detector is never enabled on: 1052# 1053# s390: it reported many false positives there 1054# 1055# sparc64: has a custom implementation which is not using the common 1056# hardlockup command line options and sysctl interface. 1057# 1058config HARDLOCKUP_DETECTOR 1059 bool "Detect Hard Lockups" 1060 depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64 1061 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH 1062 imply HARDLOCKUP_DETECTOR_PERF 1063 imply HARDLOCKUP_DETECTOR_BUDDY 1064 imply HARDLOCKUP_DETECTOR_ARCH 1065 select LOCKUP_DETECTOR 1066 1067 help 1068 Say Y here to enable the kernel to act as a watchdog to detect 1069 hard lockups. 1070 1071 Hardlockups are bugs that cause the CPU to loop in kernel mode 1072 for more than 10 seconds, without letting other interrupts have a 1073 chance to run. The current stack trace is displayed upon detection 1074 and the system will stay locked up. 1075 1076# 1077# Note that arch-specific variants are always preferred. 1078# 1079config HARDLOCKUP_DETECTOR_PREFER_BUDDY 1080 bool "Prefer the buddy CPU hardlockup detector" 1081 depends on HARDLOCKUP_DETECTOR 1082 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY 1083 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1084 help 1085 Say Y here to prefer the buddy hardlockup detector over the perf one. 1086 1087 With the buddy detector, each CPU uses its softlockup hrtimer 1088 to check that the next CPU is processing hrtimer interrupts by 1089 verifying that a counter is increasing. 1090 1091 This hardlockup detector is useful on systems that don't have 1092 an arch-specific hardlockup detector or if resources needed 1093 for the hardlockup detector are better used for other things. 1094 1095config HARDLOCKUP_DETECTOR_PERF 1096 bool 1097 depends on HARDLOCKUP_DETECTOR 1098 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY 1099 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1100 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1101 1102config HARDLOCKUP_DETECTOR_BUDDY 1103 bool 1104 depends on HARDLOCKUP_DETECTOR 1105 depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY 1106 depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY 1107 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1108 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1109 1110config HARDLOCKUP_DETECTOR_ARCH 1111 bool 1112 depends on HARDLOCKUP_DETECTOR 1113 depends on HAVE_HARDLOCKUP_DETECTOR_ARCH 1114 help 1115 The arch-specific implementation of the hardlockup detector will 1116 be used. 1117 1118# 1119# Both the "perf" and "buddy" hardlockup detectors count hrtimer 1120# interrupts. This config enables functions managing this common code. 1121# 1122config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1123 bool 1124 select SOFTLOCKUP_DETECTOR 1125 1126# 1127# Enables a timestamp based low pass filter to compensate for perf based 1128# hard lockup detection which runs too fast due to turbo modes. 1129# 1130config HARDLOCKUP_CHECK_TIMESTAMP 1131 bool 1132 1133config BOOTPARAM_HARDLOCKUP_PANIC 1134 bool "Panic (Reboot) On Hard Lockups" 1135 depends on HARDLOCKUP_DETECTOR 1136 help 1137 Say Y here to enable the kernel to panic on "hard lockups", 1138 which are bugs that cause the kernel to loop in kernel 1139 mode with interrupts disabled for more than 10 seconds (configurable 1140 using the watchdog_thresh sysctl). 1141 1142 Say N if unsure. 1143 1144config DETECT_HUNG_TASK 1145 bool "Detect Hung Tasks" 1146 depends on DEBUG_KERNEL 1147 default SOFTLOCKUP_DETECTOR 1148 help 1149 Say Y here to enable the kernel to detect "hung tasks", 1150 which are bugs that cause the task to be stuck in 1151 uninterruptible "D" state indefinitely. 1152 1153 When a hung task is detected, the kernel will print the 1154 current stack trace (which you should report), but the 1155 task will stay in uninterruptible state. If lockdep is 1156 enabled then all held locks will also be reported. This 1157 feature has negligible overhead. 1158 1159config DEFAULT_HUNG_TASK_TIMEOUT 1160 int "Default timeout for hung task detection (in seconds)" 1161 depends on DETECT_HUNG_TASK 1162 default 120 1163 help 1164 This option controls the default timeout (in seconds) used 1165 to determine when a task has become non-responsive and should 1166 be considered hung. 1167 1168 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 1169 sysctl or by writing a value to 1170 /proc/sys/kernel/hung_task_timeout_secs. 1171 1172 A timeout of 0 disables the check. The default is two minutes. 1173 Keeping the default should be fine in most cases. 1174 1175config BOOTPARAM_HUNG_TASK_PANIC 1176 bool "Panic (Reboot) On Hung Tasks" 1177 depends on DETECT_HUNG_TASK 1178 help 1179 Say Y here to enable the kernel to panic on "hung tasks", 1180 which are bugs that cause the kernel to leave a task stuck 1181 in uninterruptible "D" state. 1182 1183 The panic can be used in combination with panic_timeout, 1184 to cause the system to reboot automatically after a 1185 hung task has been detected. This feature is useful for 1186 high-availability systems that have uptime guarantees and 1187 where a hung tasks must be resolved ASAP. 1188 1189 Say N if unsure. 1190 1191config BOOTPARAM_HUNG_TASK_PANIC_VALUE 1192 int 1193 depends on DETECT_HUNG_TASK 1194 range 0 1 1195 default 0 if !BOOTPARAM_HUNG_TASK_PANIC 1196 default 1 if BOOTPARAM_HUNG_TASK_PANIC 1197 1198config WQ_WATCHDOG 1199 bool "Detect Workqueue Stalls" 1200 depends on DEBUG_KERNEL 1201 help 1202 Say Y here to enable stall detection on workqueues. If a 1203 worker pool doesn't make forward progress on a pending work 1204 item for over a given amount of time, 30s by default, a 1205 warning message is printed along with dump of workqueue 1206 state. This can be configured through kernel parameter 1207 "workqueue.watchdog_thresh" and its sysfs counterpart. 1208 1209config WQ_CPU_INTENSIVE_REPORT 1210 bool "Report per-cpu work items which hog CPU for too long" 1211 depends on DEBUG_KERNEL 1212 help 1213 Say Y here to enable reporting of concurrency-managed per-cpu work 1214 items that hog CPUs for longer than 1215 workqueue.cpu_intensive_thresh_us. Workqueue automatically 1216 detects and excludes them from concurrency management to prevent 1217 them from stalling other per-cpu work items. Occassional 1218 triggering may not necessarily indicate a problem. Repeated 1219 triggering likely indicates that the work item should be switched 1220 to use an unbound workqueue. 1221 1222config TEST_LOCKUP 1223 tristate "Test module to generate lockups" 1224 depends on m 1225 help 1226 This builds the "test_lockup" module that helps to make sure 1227 that watchdogs and lockup detectors are working properly. 1228 1229 Depending on module parameters it could emulate soft or hard 1230 lockup, "hung task", or locking arbitrary lock for a long time. 1231 Also it could generate series of lockups with cooling-down periods. 1232 1233 If unsure, say N. 1234 1235endmenu # "Debug lockups and hangs" 1236 1237menu "Scheduler Debugging" 1238 1239config SCHED_DEBUG 1240 bool "Collect scheduler debugging info" 1241 depends on DEBUG_KERNEL && DEBUG_FS 1242 default y 1243 help 1244 If you say Y here, the /sys/kernel/debug/sched file will be provided 1245 that can help debug the scheduler. The runtime overhead of this 1246 option is minimal. 1247 1248config SCHED_INFO 1249 bool 1250 default n 1251 1252config SCHEDSTATS 1253 bool "Collect scheduler statistics" 1254 depends on DEBUG_KERNEL && PROC_FS 1255 select SCHED_INFO 1256 help 1257 If you say Y here, additional code will be inserted into the 1258 scheduler and related routines to collect statistics about 1259 scheduler behavior and provide them in /proc/schedstat. These 1260 stats may be useful for both tuning and debugging the scheduler 1261 If you aren't debugging the scheduler or trying to tune a specific 1262 application, you can say N to avoid the very slight overhead 1263 this adds. 1264 1265endmenu 1266 1267config DEBUG_TIMEKEEPING 1268 bool "Enable extra timekeeping sanity checking" 1269 help 1270 This option will enable additional timekeeping sanity checks 1271 which may be helpful when diagnosing issues where timekeeping 1272 problems are suspected. 1273 1274 This may include checks in the timekeeping hotpaths, so this 1275 option may have a (very small) performance impact to some 1276 workloads. 1277 1278 If unsure, say N. 1279 1280config DEBUG_PREEMPT 1281 bool "Debug preemptible kernel" 1282 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1283 help 1284 If you say Y here then the kernel will use a debug variant of the 1285 commonly used smp_processor_id() function and will print warnings 1286 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1287 will detect preemption count underflows. 1288 1289 This option has potential to introduce high runtime overhead, 1290 depending on workload as it triggers debugging routines for each 1291 this_cpu operation. It should only be used for debugging purposes. 1292 1293menu "Lock Debugging (spinlocks, mutexes, etc...)" 1294 1295config LOCK_DEBUGGING_SUPPORT 1296 bool 1297 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1298 default y 1299 1300config PROVE_LOCKING 1301 bool "Lock debugging: prove locking correctness" 1302 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1303 select LOCKDEP 1304 select DEBUG_SPINLOCK 1305 select DEBUG_MUTEXES if !PREEMPT_RT 1306 select DEBUG_RT_MUTEXES if RT_MUTEXES 1307 select DEBUG_RWSEMS 1308 select DEBUG_WW_MUTEX_SLOWPATH 1309 select DEBUG_LOCK_ALLOC 1310 select PREEMPT_COUNT if !ARCH_NO_PREEMPT 1311 select TRACE_IRQFLAGS 1312 default n 1313 help 1314 This feature enables the kernel to prove that all locking 1315 that occurs in the kernel runtime is mathematically 1316 correct: that under no circumstance could an arbitrary (and 1317 not yet triggered) combination of observed locking 1318 sequences (on an arbitrary number of CPUs, running an 1319 arbitrary number of tasks and interrupt contexts) cause a 1320 deadlock. 1321 1322 In short, this feature enables the kernel to report locking 1323 related deadlocks before they actually occur. 1324 1325 The proof does not depend on how hard and complex a 1326 deadlock scenario would be to trigger: how many 1327 participant CPUs, tasks and irq-contexts would be needed 1328 for it to trigger. The proof also does not depend on 1329 timing: if a race and a resulting deadlock is possible 1330 theoretically (no matter how unlikely the race scenario 1331 is), it will be proven so and will immediately be 1332 reported by the kernel (once the event is observed that 1333 makes the deadlock theoretically possible). 1334 1335 If a deadlock is impossible (i.e. the locking rules, as 1336 observed by the kernel, are mathematically correct), the 1337 kernel reports nothing. 1338 1339 NOTE: this feature can also be enabled for rwlocks, mutexes 1340 and rwsems - in which case all dependencies between these 1341 different locking variants are observed and mapped too, and 1342 the proof of observed correctness is also maintained for an 1343 arbitrary combination of these separate locking variants. 1344 1345 For more details, see Documentation/locking/lockdep-design.rst. 1346 1347config PROVE_RAW_LOCK_NESTING 1348 bool "Enable raw_spinlock - spinlock nesting checks" 1349 depends on PROVE_LOCKING 1350 default n 1351 help 1352 Enable the raw_spinlock vs. spinlock nesting checks which ensure 1353 that the lock nesting rules for PREEMPT_RT enabled kernels are 1354 not violated. 1355 1356 NOTE: There are known nesting problems. So if you enable this 1357 option expect lockdep splats until these problems have been fully 1358 addressed which is work in progress. This config switch allows to 1359 identify and analyze these problems. It will be removed and the 1360 check permanently enabled once the main issues have been fixed. 1361 1362 If unsure, select N. 1363 1364config LOCK_STAT 1365 bool "Lock usage statistics" 1366 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1367 select LOCKDEP 1368 select DEBUG_SPINLOCK 1369 select DEBUG_MUTEXES if !PREEMPT_RT 1370 select DEBUG_RT_MUTEXES if RT_MUTEXES 1371 select DEBUG_LOCK_ALLOC 1372 default n 1373 help 1374 This feature enables tracking lock contention points 1375 1376 For more details, see Documentation/locking/lockstat.rst 1377 1378 This also enables lock events required by "perf lock", 1379 subcommand of perf. 1380 If you want to use "perf lock", you also need to turn on 1381 CONFIG_EVENT_TRACING. 1382 1383 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1384 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1385 1386config DEBUG_RT_MUTEXES 1387 bool "RT Mutex debugging, deadlock detection" 1388 depends on DEBUG_KERNEL && RT_MUTEXES 1389 help 1390 This allows rt mutex semantics violations and rt mutex related 1391 deadlocks (lockups) to be detected and reported automatically. 1392 1393config DEBUG_SPINLOCK 1394 bool "Spinlock and rw-lock debugging: basic checks" 1395 depends on DEBUG_KERNEL 1396 select UNINLINE_SPIN_UNLOCK 1397 help 1398 Say Y here and build SMP to catch missing spinlock initialization 1399 and certain other kinds of spinlock errors commonly made. This is 1400 best used in conjunction with the NMI watchdog so that spinlock 1401 deadlocks are also debuggable. 1402 1403config DEBUG_MUTEXES 1404 bool "Mutex debugging: basic checks" 1405 depends on DEBUG_KERNEL && !PREEMPT_RT 1406 help 1407 This feature allows mutex semantics violations to be detected and 1408 reported. 1409 1410config DEBUG_WW_MUTEX_SLOWPATH 1411 bool "Wait/wound mutex debugging: Slowpath testing" 1412 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1413 select DEBUG_LOCK_ALLOC 1414 select DEBUG_SPINLOCK 1415 select DEBUG_MUTEXES if !PREEMPT_RT 1416 select DEBUG_RT_MUTEXES if PREEMPT_RT 1417 help 1418 This feature enables slowpath testing for w/w mutex users by 1419 injecting additional -EDEADLK wound/backoff cases. Together with 1420 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1421 will test all possible w/w mutex interface abuse with the 1422 exception of simply not acquiring all the required locks. 1423 Note that this feature can introduce significant overhead, so 1424 it really should not be enabled in a production or distro kernel, 1425 even a debug kernel. If you are a driver writer, enable it. If 1426 you are a distro, do not. 1427 1428config DEBUG_RWSEMS 1429 bool "RW Semaphore debugging: basic checks" 1430 depends on DEBUG_KERNEL 1431 help 1432 This debugging feature allows mismatched rw semaphore locks 1433 and unlocks to be detected and reported. 1434 1435config DEBUG_LOCK_ALLOC 1436 bool "Lock debugging: detect incorrect freeing of live locks" 1437 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1438 select DEBUG_SPINLOCK 1439 select DEBUG_MUTEXES if !PREEMPT_RT 1440 select DEBUG_RT_MUTEXES if RT_MUTEXES 1441 select LOCKDEP 1442 help 1443 This feature will check whether any held lock (spinlock, rwlock, 1444 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1445 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1446 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1447 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1448 held during task exit. 1449 1450config LOCKDEP 1451 bool 1452 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1453 select STACKTRACE 1454 select KALLSYMS 1455 select KALLSYMS_ALL 1456 1457config LOCKDEP_SMALL 1458 bool 1459 1460config LOCKDEP_BITS 1461 int "Bitsize for MAX_LOCKDEP_ENTRIES" 1462 depends on LOCKDEP && !LOCKDEP_SMALL 1463 range 10 30 1464 default 15 1465 help 1466 Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message. 1467 1468config LOCKDEP_CHAINS_BITS 1469 int "Bitsize for MAX_LOCKDEP_CHAINS" 1470 depends on LOCKDEP && !LOCKDEP_SMALL 1471 range 10 30 1472 default 16 1473 help 1474 Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message. 1475 1476config LOCKDEP_STACK_TRACE_BITS 1477 int "Bitsize for MAX_STACK_TRACE_ENTRIES" 1478 depends on LOCKDEP && !LOCKDEP_SMALL 1479 range 10 30 1480 default 19 1481 help 1482 Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message. 1483 1484config LOCKDEP_STACK_TRACE_HASH_BITS 1485 int "Bitsize for STACK_TRACE_HASH_SIZE" 1486 depends on LOCKDEP && !LOCKDEP_SMALL 1487 range 10 30 1488 default 14 1489 help 1490 Try increasing this value if you need large STACK_TRACE_HASH_SIZE. 1491 1492config LOCKDEP_CIRCULAR_QUEUE_BITS 1493 int "Bitsize for elements in circular_queue struct" 1494 depends on LOCKDEP 1495 range 10 30 1496 default 12 1497 help 1498 Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure. 1499 1500config DEBUG_LOCKDEP 1501 bool "Lock dependency engine debugging" 1502 depends on DEBUG_KERNEL && LOCKDEP 1503 select DEBUG_IRQFLAGS 1504 help 1505 If you say Y here, the lock dependency engine will do 1506 additional runtime checks to debug itself, at the price 1507 of more runtime overhead. 1508 1509config DEBUG_ATOMIC_SLEEP 1510 bool "Sleep inside atomic section checking" 1511 select PREEMPT_COUNT 1512 depends on DEBUG_KERNEL 1513 depends on !ARCH_NO_PREEMPT 1514 help 1515 If you say Y here, various routines which may sleep will become very 1516 noisy if they are called inside atomic sections: when a spinlock is 1517 held, inside an rcu read side critical section, inside preempt disabled 1518 sections, inside an interrupt, etc... 1519 1520config DEBUG_LOCKING_API_SELFTESTS 1521 bool "Locking API boot-time self-tests" 1522 depends on DEBUG_KERNEL 1523 help 1524 Say Y here if you want the kernel to run a short self-test during 1525 bootup. The self-test checks whether common types of locking bugs 1526 are detected by debugging mechanisms or not. (if you disable 1527 lock debugging then those bugs won't be detected of course.) 1528 The following locking APIs are covered: spinlocks, rwlocks, 1529 mutexes and rwsems. 1530 1531config LOCK_TORTURE_TEST 1532 tristate "torture tests for locking" 1533 depends on DEBUG_KERNEL 1534 select TORTURE_TEST 1535 help 1536 This option provides a kernel module that runs torture tests 1537 on kernel locking primitives. The kernel module may be built 1538 after the fact on the running kernel to be tested, if desired. 1539 1540 Say Y here if you want kernel locking-primitive torture tests 1541 to be built into the kernel. 1542 Say M if you want these torture tests to build as a module. 1543 Say N if you are unsure. 1544 1545config WW_MUTEX_SELFTEST 1546 tristate "Wait/wound mutex selftests" 1547 help 1548 This option provides a kernel module that runs tests on the 1549 on the struct ww_mutex locking API. 1550 1551 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1552 with this test harness. 1553 1554 Say M if you want these self tests to build as a module. 1555 Say N if you are unsure. 1556 1557config SCF_TORTURE_TEST 1558 tristate "torture tests for smp_call_function*()" 1559 depends on DEBUG_KERNEL 1560 select TORTURE_TEST 1561 help 1562 This option provides a kernel module that runs torture tests 1563 on the smp_call_function() family of primitives. The kernel 1564 module may be built after the fact on the running kernel to 1565 be tested, if desired. 1566 1567config CSD_LOCK_WAIT_DEBUG 1568 bool "Debugging for csd_lock_wait(), called from smp_call_function*()" 1569 depends on DEBUG_KERNEL 1570 depends on 64BIT 1571 default n 1572 help 1573 This option enables debug prints when CPUs are slow to respond 1574 to the smp_call_function*() IPI wrappers. These debug prints 1575 include the IPI handler function currently executing (if any) 1576 and relevant stack traces. 1577 1578config CSD_LOCK_WAIT_DEBUG_DEFAULT 1579 bool "Default csd_lock_wait() debugging on at boot time" 1580 depends on CSD_LOCK_WAIT_DEBUG 1581 depends on 64BIT 1582 default n 1583 help 1584 This option causes the csdlock_debug= kernel boot parameter to 1585 default to 1 (basic debugging) instead of 0 (no debugging). 1586 1587endmenu # lock debugging 1588 1589config TRACE_IRQFLAGS 1590 depends on TRACE_IRQFLAGS_SUPPORT 1591 bool 1592 help 1593 Enables hooks to interrupt enabling and disabling for 1594 either tracing or lock debugging. 1595 1596config TRACE_IRQFLAGS_NMI 1597 def_bool y 1598 depends on TRACE_IRQFLAGS 1599 depends on TRACE_IRQFLAGS_NMI_SUPPORT 1600 1601config NMI_CHECK_CPU 1602 bool "Debugging for CPUs failing to respond to backtrace requests" 1603 depends on DEBUG_KERNEL 1604 depends on X86 1605 default n 1606 help 1607 Enables debug prints when a CPU fails to respond to a given 1608 backtrace NMI. These prints provide some reasons why a CPU 1609 might legitimately be failing to respond, for example, if it 1610 is offline of if ignore_nmis is set. 1611 1612config DEBUG_IRQFLAGS 1613 bool "Debug IRQ flag manipulation" 1614 help 1615 Enables checks for potentially unsafe enabling or disabling of 1616 interrupts, such as calling raw_local_irq_restore() when interrupts 1617 are enabled. 1618 1619config STACKTRACE 1620 bool "Stack backtrace support" 1621 depends on STACKTRACE_SUPPORT 1622 help 1623 This option causes the kernel to create a /proc/pid/stack for 1624 every process, showing its current stack trace. 1625 It is also used by various kernel debugging features that require 1626 stack trace generation. 1627 1628config WARN_ALL_UNSEEDED_RANDOM 1629 bool "Warn for all uses of unseeded randomness" 1630 default n 1631 help 1632 Some parts of the kernel contain bugs relating to their use of 1633 cryptographically secure random numbers before it's actually possible 1634 to generate those numbers securely. This setting ensures that these 1635 flaws don't go unnoticed, by enabling a message, should this ever 1636 occur. This will allow people with obscure setups to know when things 1637 are going wrong, so that they might contact developers about fixing 1638 it. 1639 1640 Unfortunately, on some models of some architectures getting 1641 a fully seeded CRNG is extremely difficult, and so this can 1642 result in dmesg getting spammed for a surprisingly long 1643 time. This is really bad from a security perspective, and 1644 so architecture maintainers really need to do what they can 1645 to get the CRNG seeded sooner after the system is booted. 1646 However, since users cannot do anything actionable to 1647 address this, by default this option is disabled. 1648 1649 Say Y here if you want to receive warnings for all uses of 1650 unseeded randomness. This will be of use primarily for 1651 those developers interested in improving the security of 1652 Linux kernels running on their architecture (or 1653 subarchitecture). 1654 1655config DEBUG_KOBJECT 1656 bool "kobject debugging" 1657 depends on DEBUG_KERNEL 1658 help 1659 If you say Y here, some extra kobject debugging messages will be sent 1660 to the syslog. 1661 1662config DEBUG_KOBJECT_RELEASE 1663 bool "kobject release debugging" 1664 depends on DEBUG_OBJECTS_TIMERS 1665 help 1666 kobjects are reference counted objects. This means that their 1667 last reference count put is not predictable, and the kobject can 1668 live on past the point at which a driver decides to drop its 1669 initial reference to the kobject gained on allocation. An 1670 example of this would be a struct device which has just been 1671 unregistered. 1672 1673 However, some buggy drivers assume that after such an operation, 1674 the memory backing the kobject can be immediately freed. This 1675 goes completely against the principles of a refcounted object. 1676 1677 If you say Y here, the kernel will delay the release of kobjects 1678 on the last reference count to improve the visibility of this 1679 kind of kobject release bug. 1680 1681config HAVE_DEBUG_BUGVERBOSE 1682 bool 1683 1684menu "Debug kernel data structures" 1685 1686config DEBUG_LIST 1687 bool "Debug linked list manipulation" 1688 depends on DEBUG_KERNEL 1689 select LIST_HARDENED 1690 help 1691 Enable this to turn on extended checks in the linked-list walking 1692 routines. 1693 1694 This option trades better quality error reports for performance, and 1695 is more suitable for kernel debugging. If you care about performance, 1696 you should only enable CONFIG_LIST_HARDENED instead. 1697 1698 If unsure, say N. 1699 1700config DEBUG_PLIST 1701 bool "Debug priority linked list manipulation" 1702 depends on DEBUG_KERNEL 1703 help 1704 Enable this to turn on extended checks in the priority-ordered 1705 linked-list (plist) walking routines. This checks the entire 1706 list multiple times during each manipulation. 1707 1708 If unsure, say N. 1709 1710config DEBUG_SG 1711 bool "Debug SG table operations" 1712 depends on DEBUG_KERNEL 1713 help 1714 Enable this to turn on checks on scatter-gather tables. This can 1715 help find problems with drivers that do not properly initialize 1716 their sg tables. 1717 1718 If unsure, say N. 1719 1720config DEBUG_NOTIFIERS 1721 bool "Debug notifier call chains" 1722 depends on DEBUG_KERNEL 1723 help 1724 Enable this to turn on sanity checking for notifier call chains. 1725 This is most useful for kernel developers to make sure that 1726 modules properly unregister themselves from notifier chains. 1727 This is a relatively cheap check but if you care about maximum 1728 performance, say N. 1729 1730config DEBUG_MAPLE_TREE 1731 bool "Debug maple trees" 1732 depends on DEBUG_KERNEL 1733 help 1734 Enable maple tree debugging information and extra validations. 1735 1736 If unsure, say N. 1737 1738endmenu 1739 1740source "kernel/rcu/Kconfig.debug" 1741 1742config DEBUG_WQ_FORCE_RR_CPU 1743 bool "Force round-robin CPU selection for unbound work items" 1744 depends on DEBUG_KERNEL 1745 default n 1746 help 1747 Workqueue used to implicitly guarantee that work items queued 1748 without explicit CPU specified are put on the local CPU. This 1749 guarantee is no longer true and while local CPU is still 1750 preferred work items may be put on foreign CPUs. Kernel 1751 parameter "workqueue.debug_force_rr_cpu" is added to force 1752 round-robin CPU selection to flush out usages which depend on the 1753 now broken guarantee. This config option enables the debug 1754 feature by default. When enabled, memory and cache locality will 1755 be impacted. 1756 1757config CPU_HOTPLUG_STATE_CONTROL 1758 bool "Enable CPU hotplug state control" 1759 depends on DEBUG_KERNEL 1760 depends on HOTPLUG_CPU 1761 default n 1762 help 1763 Allows to write steps between "offline" and "online" to the CPUs 1764 sysfs target file so states can be stepped granular. This is a debug 1765 option for now as the hotplug machinery cannot be stopped and 1766 restarted at arbitrary points yet. 1767 1768 Say N if your are unsure. 1769 1770config LATENCYTOP 1771 bool "Latency measuring infrastructure" 1772 depends on DEBUG_KERNEL 1773 depends on STACKTRACE_SUPPORT 1774 depends on PROC_FS 1775 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 1776 select KALLSYMS 1777 select KALLSYMS_ALL 1778 select STACKTRACE 1779 select SCHEDSTATS 1780 help 1781 Enable this option if you want to use the LatencyTOP tool 1782 to find out which userspace is blocking on what kernel operations. 1783 1784config DEBUG_CGROUP_REF 1785 bool "Disable inlining of cgroup css reference count functions" 1786 depends on DEBUG_KERNEL 1787 depends on CGROUPS 1788 depends on KPROBES 1789 default n 1790 help 1791 Force cgroup css reference count functions to not be inlined so 1792 that they can be kprobed for debugging. 1793 1794source "kernel/trace/Kconfig" 1795 1796config PROVIDE_OHCI1394_DMA_INIT 1797 bool "Remote debugging over FireWire early on boot" 1798 depends on PCI && X86 1799 help 1800 If you want to debug problems which hang or crash the kernel early 1801 on boot and the crashing machine has a FireWire port, you can use 1802 this feature to remotely access the memory of the crashed machine 1803 over FireWire. This employs remote DMA as part of the OHCI1394 1804 specification which is now the standard for FireWire controllers. 1805 1806 With remote DMA, you can monitor the printk buffer remotely using 1807 firescope and access all memory below 4GB using fireproxy from gdb. 1808 Even controlling a kernel debugger is possible using remote DMA. 1809 1810 Usage: 1811 1812 If ohci1394_dma=early is used as boot parameter, it will initialize 1813 all OHCI1394 controllers which are found in the PCI config space. 1814 1815 As all changes to the FireWire bus such as enabling and disabling 1816 devices cause a bus reset and thereby disable remote DMA for all 1817 devices, be sure to have the cable plugged and FireWire enabled on 1818 the debugging host before booting the debug target for debugging. 1819 1820 This code (~1k) is freed after boot. By then, the firewire stack 1821 in charge of the OHCI-1394 controllers should be used instead. 1822 1823 See Documentation/core-api/debugging-via-ohci1394.rst for more information. 1824 1825source "samples/Kconfig" 1826 1827config ARCH_HAS_DEVMEM_IS_ALLOWED 1828 bool 1829 1830config STRICT_DEVMEM 1831 bool "Filter access to /dev/mem" 1832 depends on MMU && DEVMEM 1833 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED 1834 default y if PPC || X86 || ARM64 1835 help 1836 If this option is disabled, you allow userspace (root) access to all 1837 of memory, including kernel and userspace memory. Accidental 1838 access to this is obviously disastrous, but specific access can 1839 be used by people debugging the kernel. Note that with PAT support 1840 enabled, even in this case there are restrictions on /dev/mem 1841 use due to the cache aliasing requirements. 1842 1843 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 1844 file only allows userspace access to PCI space and the BIOS code and 1845 data regions. This is sufficient for dosemu and X and all common 1846 users of /dev/mem. 1847 1848 If in doubt, say Y. 1849 1850config IO_STRICT_DEVMEM 1851 bool "Filter I/O access to /dev/mem" 1852 depends on STRICT_DEVMEM 1853 help 1854 If this option is disabled, you allow userspace (root) access to all 1855 io-memory regardless of whether a driver is actively using that 1856 range. Accidental access to this is obviously disastrous, but 1857 specific access can be used by people debugging kernel drivers. 1858 1859 If this option is switched on, the /dev/mem file only allows 1860 userspace access to *idle* io-memory ranges (see /proc/iomem) This 1861 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 1862 if the driver using a given range cannot be disabled. 1863 1864 If in doubt, say Y. 1865 1866menu "$(SRCARCH) Debugging" 1867 1868source "arch/$(SRCARCH)/Kconfig.debug" 1869 1870endmenu 1871 1872menu "Kernel Testing and Coverage" 1873 1874source "lib/kunit/Kconfig" 1875 1876config NOTIFIER_ERROR_INJECTION 1877 tristate "Notifier error injection" 1878 depends on DEBUG_KERNEL 1879 select DEBUG_FS 1880 help 1881 This option provides the ability to inject artificial errors to 1882 specified notifier chain callbacks. It is useful to test the error 1883 handling of notifier call chain failures. 1884 1885 Say N if unsure. 1886 1887config PM_NOTIFIER_ERROR_INJECT 1888 tristate "PM notifier error injection module" 1889 depends on PM && NOTIFIER_ERROR_INJECTION 1890 default m if PM_DEBUG 1891 help 1892 This option provides the ability to inject artificial errors to 1893 PM notifier chain callbacks. It is controlled through debugfs 1894 interface /sys/kernel/debug/notifier-error-inject/pm 1895 1896 If the notifier call chain should be failed with some events 1897 notified, write the error code to "actions/<notifier event>/error". 1898 1899 Example: Inject PM suspend error (-12 = -ENOMEM) 1900 1901 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1902 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1903 # echo mem > /sys/power/state 1904 bash: echo: write error: Cannot allocate memory 1905 1906 To compile this code as a module, choose M here: the module will 1907 be called pm-notifier-error-inject. 1908 1909 If unsure, say N. 1910 1911config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1912 tristate "OF reconfig notifier error injection module" 1913 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1914 help 1915 This option provides the ability to inject artificial errors to 1916 OF reconfig notifier chain callbacks. It is controlled 1917 through debugfs interface under 1918 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1919 1920 If the notifier call chain should be failed with some events 1921 notified, write the error code to "actions/<notifier event>/error". 1922 1923 To compile this code as a module, choose M here: the module will 1924 be called of-reconfig-notifier-error-inject. 1925 1926 If unsure, say N. 1927 1928config NETDEV_NOTIFIER_ERROR_INJECT 1929 tristate "Netdev notifier error injection module" 1930 depends on NET && NOTIFIER_ERROR_INJECTION 1931 help 1932 This option provides the ability to inject artificial errors to 1933 netdevice notifier chain callbacks. It is controlled through debugfs 1934 interface /sys/kernel/debug/notifier-error-inject/netdev 1935 1936 If the notifier call chain should be failed with some events 1937 notified, write the error code to "actions/<notifier event>/error". 1938 1939 Example: Inject netdevice mtu change error (-22 = -EINVAL) 1940 1941 # cd /sys/kernel/debug/notifier-error-inject/netdev 1942 # echo -22 > actions/NETDEV_CHANGEMTU/error 1943 # ip link set eth0 mtu 1024 1944 RTNETLINK answers: Invalid argument 1945 1946 To compile this code as a module, choose M here: the module will 1947 be called netdev-notifier-error-inject. 1948 1949 If unsure, say N. 1950 1951config FUNCTION_ERROR_INJECTION 1952 bool "Fault-injections of functions" 1953 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 1954 help 1955 Add fault injections into various functions that are annotated with 1956 ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return 1957 value of these functions. This is useful to test error paths of code. 1958 1959 If unsure, say N 1960 1961config FAULT_INJECTION 1962 bool "Fault-injection framework" 1963 depends on DEBUG_KERNEL 1964 help 1965 Provide fault-injection framework. 1966 For more details, see Documentation/fault-injection/. 1967 1968config FAILSLAB 1969 bool "Fault-injection capability for kmalloc" 1970 depends on FAULT_INJECTION 1971 depends on SLAB || SLUB 1972 help 1973 Provide fault-injection capability for kmalloc. 1974 1975config FAIL_PAGE_ALLOC 1976 bool "Fault-injection capability for alloc_pages()" 1977 depends on FAULT_INJECTION 1978 help 1979 Provide fault-injection capability for alloc_pages(). 1980 1981config FAULT_INJECTION_USERCOPY 1982 bool "Fault injection capability for usercopy functions" 1983 depends on FAULT_INJECTION 1984 help 1985 Provides fault-injection capability to inject failures 1986 in usercopy functions (copy_from_user(), get_user(), ...). 1987 1988config FAIL_MAKE_REQUEST 1989 bool "Fault-injection capability for disk IO" 1990 depends on FAULT_INJECTION && BLOCK 1991 help 1992 Provide fault-injection capability for disk IO. 1993 1994config FAIL_IO_TIMEOUT 1995 bool "Fault-injection capability for faking disk interrupts" 1996 depends on FAULT_INJECTION && BLOCK 1997 help 1998 Provide fault-injection capability on end IO handling. This 1999 will make the block layer "forget" an interrupt as configured, 2000 thus exercising the error handling. 2001 2002 Only works with drivers that use the generic timeout handling, 2003 for others it won't do anything. 2004 2005config FAIL_FUTEX 2006 bool "Fault-injection capability for futexes" 2007 select DEBUG_FS 2008 depends on FAULT_INJECTION && FUTEX 2009 help 2010 Provide fault-injection capability for futexes. 2011 2012config FAULT_INJECTION_DEBUG_FS 2013 bool "Debugfs entries for fault-injection capabilities" 2014 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 2015 help 2016 Enable configuration of fault-injection capabilities via debugfs. 2017 2018config FAIL_FUNCTION 2019 bool "Fault-injection capability for functions" 2020 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 2021 help 2022 Provide function-based fault-injection capability. 2023 This will allow you to override a specific function with a return 2024 with given return value. As a result, function caller will see 2025 an error value and have to handle it. This is useful to test the 2026 error handling in various subsystems. 2027 2028config FAIL_MMC_REQUEST 2029 bool "Fault-injection capability for MMC IO" 2030 depends on FAULT_INJECTION_DEBUG_FS && MMC 2031 help 2032 Provide fault-injection capability for MMC IO. 2033 This will make the mmc core return data errors. This is 2034 useful to test the error handling in the mmc block device 2035 and to test how the mmc host driver handles retries from 2036 the block device. 2037 2038config FAIL_SUNRPC 2039 bool "Fault-injection capability for SunRPC" 2040 depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG 2041 help 2042 Provide fault-injection capability for SunRPC and 2043 its consumers. 2044 2045config FAULT_INJECTION_CONFIGFS 2046 bool "Configfs interface for fault-injection capabilities" 2047 depends on FAULT_INJECTION 2048 select CONFIGFS_FS 2049 help 2050 This option allows configfs-based drivers to dynamically configure 2051 fault-injection via configfs. Each parameter for driver-specific 2052 fault-injection can be made visible as a configfs attribute in a 2053 configfs group. 2054 2055 2056config FAULT_INJECTION_STACKTRACE_FILTER 2057 bool "stacktrace filter for fault-injection capabilities" 2058 depends on FAULT_INJECTION 2059 depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT 2060 select STACKTRACE 2061 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 2062 help 2063 Provide stacktrace filter for fault-injection capabilities 2064 2065config ARCH_HAS_KCOV 2066 bool 2067 help 2068 An architecture should select this when it can successfully 2069 build and run with CONFIG_KCOV. This typically requires 2070 disabling instrumentation for some early boot code. 2071 2072config CC_HAS_SANCOV_TRACE_PC 2073 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 2074 2075 2076config KCOV 2077 bool "Code coverage for fuzzing" 2078 depends on ARCH_HAS_KCOV 2079 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 2080 depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \ 2081 GCC_VERSION >= 120000 || CLANG_VERSION >= 130000 2082 select DEBUG_FS 2083 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 2084 select OBJTOOL if HAVE_NOINSTR_HACK 2085 help 2086 KCOV exposes kernel code coverage information in a form suitable 2087 for coverage-guided fuzzing (randomized testing). 2088 2089 If RANDOMIZE_BASE is enabled, PC values will not be stable across 2090 different machines and across reboots. If you need stable PC values, 2091 disable RANDOMIZE_BASE. 2092 2093 For more details, see Documentation/dev-tools/kcov.rst. 2094 2095config KCOV_ENABLE_COMPARISONS 2096 bool "Enable comparison operands collection by KCOV" 2097 depends on KCOV 2098 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 2099 help 2100 KCOV also exposes operands of every comparison in the instrumented 2101 code along with operand sizes and PCs of the comparison instructions. 2102 These operands can be used by fuzzing engines to improve the quality 2103 of fuzzing coverage. 2104 2105config KCOV_INSTRUMENT_ALL 2106 bool "Instrument all code by default" 2107 depends on KCOV 2108 default y 2109 help 2110 If you are doing generic system call fuzzing (like e.g. syzkaller), 2111 then you will want to instrument the whole kernel and you should 2112 say y here. If you are doing more targeted fuzzing (like e.g. 2113 filesystem fuzzing with AFL) then you will want to enable coverage 2114 for more specific subsets of files, and should say n here. 2115 2116config KCOV_IRQ_AREA_SIZE 2117 hex "Size of interrupt coverage collection area in words" 2118 depends on KCOV 2119 default 0x40000 2120 help 2121 KCOV uses preallocated per-cpu areas to collect coverage from 2122 soft interrupts. This specifies the size of those areas in the 2123 number of unsigned long words. 2124 2125menuconfig RUNTIME_TESTING_MENU 2126 bool "Runtime Testing" 2127 def_bool y 2128 2129if RUNTIME_TESTING_MENU 2130 2131config TEST_DHRY 2132 tristate "Dhrystone benchmark test" 2133 help 2134 Enable this to include the Dhrystone 2.1 benchmark. This test 2135 calculates the number of Dhrystones per second, and the number of 2136 DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided 2137 by 1757 (the number of Dhrystones per second obtained on the VAX 2138 11/780, nominally a 1 MIPS machine). 2139 2140 To run the benchmark, it needs to be enabled explicitly, either from 2141 the kernel command line (when built-in), or from userspace (when 2142 built-in or modular. 2143 2144 Run once during kernel boot: 2145 2146 test_dhry.run 2147 2148 Set number of iterations from kernel command line: 2149 2150 test_dhry.iterations=<n> 2151 2152 Set number of iterations from userspace: 2153 2154 echo <n> > /sys/module/test_dhry/parameters/iterations 2155 2156 Trigger manual run from userspace: 2157 2158 echo y > /sys/module/test_dhry/parameters/run 2159 2160 If the number of iterations is <= 0, the test will devise a suitable 2161 number of iterations (test runs for at least 2s) automatically. 2162 This process takes ca. 4s. 2163 2164 If unsure, say N. 2165 2166config LKDTM 2167 tristate "Linux Kernel Dump Test Tool Module" 2168 depends on DEBUG_FS 2169 help 2170 This module enables testing of the different dumping mechanisms by 2171 inducing system failures at predefined crash points. 2172 If you don't need it: say N 2173 Choose M here to compile this code as a module. The module will be 2174 called lkdtm. 2175 2176 Documentation on how to use the module can be found in 2177 Documentation/fault-injection/provoke-crashes.rst 2178 2179config CPUMASK_KUNIT_TEST 2180 tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS 2181 depends on KUNIT 2182 default KUNIT_ALL_TESTS 2183 help 2184 Enable to turn on cpumask tests, running at boot or module load time. 2185 2186 For more information on KUnit and unit tests in general, please refer 2187 to the KUnit documentation in Documentation/dev-tools/kunit/. 2188 2189 If unsure, say N. 2190 2191config TEST_LIST_SORT 2192 tristate "Linked list sorting test" if !KUNIT_ALL_TESTS 2193 depends on KUNIT 2194 default KUNIT_ALL_TESTS 2195 help 2196 Enable this to turn on 'list_sort()' function test. This test is 2197 executed only once during system boot (so affects only boot time), 2198 or at module load time. 2199 2200 If unsure, say N. 2201 2202config TEST_MIN_HEAP 2203 tristate "Min heap test" 2204 depends on DEBUG_KERNEL || m 2205 help 2206 Enable this to turn on min heap function tests. This test is 2207 executed only once during system boot (so affects only boot time), 2208 or at module load time. 2209 2210 If unsure, say N. 2211 2212config TEST_SORT 2213 tristate "Array-based sort test" if !KUNIT_ALL_TESTS 2214 depends on KUNIT 2215 default KUNIT_ALL_TESTS 2216 help 2217 This option enables the self-test function of 'sort()' at boot, 2218 or at module load time. 2219 2220 If unsure, say N. 2221 2222config TEST_DIV64 2223 tristate "64bit/32bit division and modulo test" 2224 depends on DEBUG_KERNEL || m 2225 help 2226 Enable this to turn on 'do_div()' function test. This test is 2227 executed only once during system boot (so affects only boot time), 2228 or at module load time. 2229 2230 If unsure, say N. 2231 2232config TEST_IOV_ITER 2233 tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS 2234 depends on KUNIT 2235 depends on MMU 2236 default KUNIT_ALL_TESTS 2237 help 2238 Enable this to turn on testing of the operation of the I/O iterator 2239 (iov_iter). This test is executed only once during system boot (so 2240 affects only boot time), or at module load time. 2241 2242 If unsure, say N. 2243 2244config KPROBES_SANITY_TEST 2245 tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS 2246 depends on DEBUG_KERNEL 2247 depends on KPROBES 2248 depends on KUNIT 2249 select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 2250 default KUNIT_ALL_TESTS 2251 help 2252 This option provides for testing basic kprobes functionality on 2253 boot. Samples of kprobe and kretprobe are inserted and 2254 verified for functionality. 2255 2256 Say N if you are unsure. 2257 2258config FPROBE_SANITY_TEST 2259 bool "Self test for fprobe" 2260 depends on DEBUG_KERNEL 2261 depends on FPROBE 2262 depends on KUNIT=y 2263 help 2264 This option will enable testing the fprobe when the system boot. 2265 A series of tests are made to verify that the fprobe is functioning 2266 properly. 2267 2268 Say N if you are unsure. 2269 2270config BACKTRACE_SELF_TEST 2271 tristate "Self test for the backtrace code" 2272 depends on DEBUG_KERNEL 2273 help 2274 This option provides a kernel module that can be used to test 2275 the kernel stack backtrace code. This option is not useful 2276 for distributions or general kernels, but only for kernel 2277 developers working on architecture code. 2278 2279 Note that if you want to also test saved backtraces, you will 2280 have to enable STACKTRACE as well. 2281 2282 Say N if you are unsure. 2283 2284config TEST_REF_TRACKER 2285 tristate "Self test for reference tracker" 2286 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT 2287 select REF_TRACKER 2288 help 2289 This option provides a kernel module performing tests 2290 using reference tracker infrastructure. 2291 2292 Say N if you are unsure. 2293 2294config RBTREE_TEST 2295 tristate "Red-Black tree test" 2296 depends on DEBUG_KERNEL 2297 help 2298 A benchmark measuring the performance of the rbtree library. 2299 Also includes rbtree invariant checks. 2300 2301config REED_SOLOMON_TEST 2302 tristate "Reed-Solomon library test" 2303 depends on DEBUG_KERNEL || m 2304 select REED_SOLOMON 2305 select REED_SOLOMON_ENC16 2306 select REED_SOLOMON_DEC16 2307 help 2308 This option enables the self-test function of rslib at boot, 2309 or at module load time. 2310 2311 If unsure, say N. 2312 2313config INTERVAL_TREE_TEST 2314 tristate "Interval tree test" 2315 depends on DEBUG_KERNEL 2316 select INTERVAL_TREE 2317 help 2318 A benchmark measuring the performance of the interval tree library 2319 2320config PERCPU_TEST 2321 tristate "Per cpu operations test" 2322 depends on m && DEBUG_KERNEL 2323 help 2324 Enable this option to build test module which validates per-cpu 2325 operations. 2326 2327 If unsure, say N. 2328 2329config ATOMIC64_SELFTEST 2330 tristate "Perform an atomic64_t self-test" 2331 help 2332 Enable this option to test the atomic64_t functions at boot or 2333 at module load time. 2334 2335 If unsure, say N. 2336 2337config ASYNC_RAID6_TEST 2338 tristate "Self test for hardware accelerated raid6 recovery" 2339 depends on ASYNC_RAID6_RECOV 2340 select ASYNC_MEMCPY 2341 help 2342 This is a one-shot self test that permutes through the 2343 recovery of all the possible two disk failure scenarios for a 2344 N-disk array. Recovery is performed with the asynchronous 2345 raid6 recovery routines, and will optionally use an offload 2346 engine if one is available. 2347 2348 If unsure, say N. 2349 2350config TEST_HEXDUMP 2351 tristate "Test functions located in the hexdump module at runtime" 2352 2353config STRING_SELFTEST 2354 tristate "Test string functions at runtime" 2355 2356config TEST_STRING_HELPERS 2357 tristate "Test functions located in the string_helpers module at runtime" 2358 2359config TEST_KSTRTOX 2360 tristate "Test kstrto*() family of functions at runtime" 2361 2362config TEST_PRINTF 2363 tristate "Test printf() family of functions at runtime" 2364 2365config TEST_SCANF 2366 tristate "Test scanf() family of functions at runtime" 2367 2368config TEST_BITMAP 2369 tristate "Test bitmap_*() family of functions at runtime" 2370 help 2371 Enable this option to test the bitmap functions at boot. 2372 2373 If unsure, say N. 2374 2375config TEST_UUID 2376 tristate "Test functions located in the uuid module at runtime" 2377 2378config TEST_XARRAY 2379 tristate "Test the XArray code at runtime" 2380 2381config TEST_MAPLE_TREE 2382 tristate "Test the Maple Tree code at runtime or module load" 2383 help 2384 Enable this option to test the maple tree code functions at boot, or 2385 when the module is loaded. Enable "Debug Maple Trees" will enable 2386 more verbose output on failures. 2387 2388 If unsure, say N. 2389 2390config TEST_RHASHTABLE 2391 tristate "Perform selftest on resizable hash table" 2392 help 2393 Enable this option to test the rhashtable functions at boot. 2394 2395 If unsure, say N. 2396 2397config TEST_IDA 2398 tristate "Perform selftest on IDA functions" 2399 2400config TEST_PARMAN 2401 tristate "Perform selftest on priority array manager" 2402 depends on PARMAN 2403 help 2404 Enable this option to test priority array manager on boot 2405 (or module load). 2406 2407 If unsure, say N. 2408 2409config TEST_IRQ_TIMINGS 2410 bool "IRQ timings selftest" 2411 depends on IRQ_TIMINGS 2412 help 2413 Enable this option to test the irq timings code on boot. 2414 2415 If unsure, say N. 2416 2417config TEST_LKM 2418 tristate "Test module loading with 'hello world' module" 2419 depends on m 2420 help 2421 This builds the "test_module" module that emits "Hello, world" 2422 on printk when loaded. It is designed to be used for basic 2423 evaluation of the module loading subsystem (for example when 2424 validating module verification). It lacks any extra dependencies, 2425 and will not normally be loaded by the system unless explicitly 2426 requested by name. 2427 2428 If unsure, say N. 2429 2430config TEST_BITOPS 2431 tristate "Test module for compilation of bitops operations" 2432 depends on m 2433 help 2434 This builds the "test_bitops" module that is much like the 2435 TEST_LKM module except that it does a basic exercise of the 2436 set/clear_bit macros and get_count_order/long to make sure there are 2437 no compiler warnings from C=1 sparse checker or -Wextra 2438 compilations. It has no dependencies and doesn't run or load unless 2439 explicitly requested by name. for example: modprobe test_bitops. 2440 2441 If unsure, say N. 2442 2443config TEST_VMALLOC 2444 tristate "Test module for stress/performance analysis of vmalloc allocator" 2445 default n 2446 depends on MMU 2447 depends on m 2448 help 2449 This builds the "test_vmalloc" module that should be used for 2450 stress and performance analysis. So, any new change for vmalloc 2451 subsystem can be evaluated from performance and stability point 2452 of view. 2453 2454 If unsure, say N. 2455 2456config TEST_USER_COPY 2457 tristate "Test user/kernel boundary protections" 2458 depends on m 2459 help 2460 This builds the "test_user_copy" module that runs sanity checks 2461 on the copy_to/from_user infrastructure, making sure basic 2462 user/kernel boundary testing is working. If it fails to load, 2463 a regression has been detected in the user/kernel memory boundary 2464 protections. 2465 2466 If unsure, say N. 2467 2468config TEST_BPF 2469 tristate "Test BPF filter functionality" 2470 depends on m && NET 2471 help 2472 This builds the "test_bpf" module that runs various test vectors 2473 against the BPF interpreter or BPF JIT compiler depending on the 2474 current setting. This is in particular useful for BPF JIT compiler 2475 development, but also to run regression tests against changes in 2476 the interpreter code. It also enables test stubs for eBPF maps and 2477 verifier used by user space verifier testsuite. 2478 2479 If unsure, say N. 2480 2481config TEST_BLACKHOLE_DEV 2482 tristate "Test blackhole netdev functionality" 2483 depends on m && NET 2484 help 2485 This builds the "test_blackhole_dev" module that validates the 2486 data path through this blackhole netdev. 2487 2488 If unsure, say N. 2489 2490config FIND_BIT_BENCHMARK 2491 tristate "Test find_bit functions" 2492 help 2493 This builds the "test_find_bit" module that measure find_*_bit() 2494 functions performance. 2495 2496 If unsure, say N. 2497 2498config TEST_FIRMWARE 2499 tristate "Test firmware loading via userspace interface" 2500 depends on FW_LOADER 2501 help 2502 This builds the "test_firmware" module that creates a userspace 2503 interface for testing firmware loading. This can be used to 2504 control the triggering of firmware loading without needing an 2505 actual firmware-using device. The contents can be rechecked by 2506 userspace. 2507 2508 If unsure, say N. 2509 2510config TEST_SYSCTL 2511 tristate "sysctl test driver" 2512 depends on PROC_SYSCTL 2513 help 2514 This builds the "test_sysctl" module. This driver enables to test the 2515 proc sysctl interfaces available to drivers safely without affecting 2516 production knobs which might alter system functionality. 2517 2518 If unsure, say N. 2519 2520config BITFIELD_KUNIT 2521 tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS 2522 depends on KUNIT 2523 default KUNIT_ALL_TESTS 2524 help 2525 Enable this option to test the bitfield functions at boot. 2526 2527 KUnit tests run during boot and output the results to the debug log 2528 in TAP format (http://testanything.org/). Only useful for kernel devs 2529 running the KUnit test harness, and not intended for inclusion into a 2530 production build. 2531 2532 For more information on KUnit and unit tests in general please refer 2533 to the KUnit documentation in Documentation/dev-tools/kunit/. 2534 2535 If unsure, say N. 2536 2537config CHECKSUM_KUNIT 2538 tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS 2539 depends on KUNIT 2540 default KUNIT_ALL_TESTS 2541 help 2542 Enable this option to test the checksum functions at boot. 2543 2544 KUnit tests run during boot and output the results to the debug log 2545 in TAP format (http://testanything.org/). Only useful for kernel devs 2546 running the KUnit test harness, and not intended for inclusion into a 2547 production build. 2548 2549 For more information on KUnit and unit tests in general please refer 2550 to the KUnit documentation in Documentation/dev-tools/kunit/. 2551 2552 If unsure, say N. 2553 2554config HASH_KUNIT_TEST 2555 tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS 2556 depends on KUNIT 2557 default KUNIT_ALL_TESTS 2558 help 2559 Enable this option to test the kernel's string (<linux/stringhash.h>), and 2560 integer (<linux/hash.h>) hash functions on boot. 2561 2562 KUnit tests run during boot and output the results to the debug log 2563 in TAP format (https://testanything.org/). Only useful for kernel devs 2564 running the KUnit test harness, and not intended for inclusion into a 2565 production build. 2566 2567 For more information on KUnit and unit tests in general please refer 2568 to the KUnit documentation in Documentation/dev-tools/kunit/. 2569 2570 This is intended to help people writing architecture-specific 2571 optimized versions. If unsure, say N. 2572 2573config RESOURCE_KUNIT_TEST 2574 tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS 2575 depends on KUNIT 2576 default KUNIT_ALL_TESTS 2577 help 2578 This builds the resource API unit test. 2579 Tests the logic of API provided by resource.c and ioport.h. 2580 For more information on KUnit and unit tests in general please refer 2581 to the KUnit documentation in Documentation/dev-tools/kunit/. 2582 2583 If unsure, say N. 2584 2585config SYSCTL_KUNIT_TEST 2586 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS 2587 depends on KUNIT 2588 default KUNIT_ALL_TESTS 2589 help 2590 This builds the proc sysctl unit test, which runs on boot. 2591 Tests the API contract and implementation correctness of sysctl. 2592 For more information on KUnit and unit tests in general please refer 2593 to the KUnit documentation in Documentation/dev-tools/kunit/. 2594 2595 If unsure, say N. 2596 2597config LIST_KUNIT_TEST 2598 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS 2599 depends on KUNIT 2600 default KUNIT_ALL_TESTS 2601 help 2602 This builds the linked list KUnit test suite. 2603 It tests that the API and basic functionality of the list_head type 2604 and associated macros. 2605 2606 KUnit tests run during boot and output the results to the debug log 2607 in TAP format (https://testanything.org/). Only useful for kernel devs 2608 running the KUnit test harness, and not intended for inclusion into a 2609 production build. 2610 2611 For more information on KUnit and unit tests in general please refer 2612 to the KUnit documentation in Documentation/dev-tools/kunit/. 2613 2614 If unsure, say N. 2615 2616config HASHTABLE_KUNIT_TEST 2617 tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS 2618 depends on KUNIT 2619 default KUNIT_ALL_TESTS 2620 help 2621 This builds the hashtable KUnit test suite. 2622 It tests the basic functionality of the API defined in 2623 include/linux/hashtable.h. For more information on KUnit and 2624 unit tests in general please refer to the KUnit documentation 2625 in Documentation/dev-tools/kunit/. 2626 2627 If unsure, say N. 2628 2629config LINEAR_RANGES_TEST 2630 tristate "KUnit test for linear_ranges" 2631 depends on KUNIT 2632 select LINEAR_RANGES 2633 help 2634 This builds the linear_ranges unit test, which runs on boot. 2635 Tests the linear_ranges logic correctness. 2636 For more information on KUnit and unit tests in general please refer 2637 to the KUnit documentation in Documentation/dev-tools/kunit/. 2638 2639 If unsure, say N. 2640 2641config CMDLINE_KUNIT_TEST 2642 tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS 2643 depends on KUNIT 2644 default KUNIT_ALL_TESTS 2645 help 2646 This builds the cmdline API unit test. 2647 Tests the logic of API provided by cmdline.c. 2648 For more information on KUnit and unit tests in general please refer 2649 to the KUnit documentation in Documentation/dev-tools/kunit/. 2650 2651 If unsure, say N. 2652 2653config BITS_TEST 2654 tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS 2655 depends on KUNIT 2656 default KUNIT_ALL_TESTS 2657 help 2658 This builds the bits unit test. 2659 Tests the logic of macros defined in bits.h. 2660 For more information on KUnit and unit tests in general please refer 2661 to the KUnit documentation in Documentation/dev-tools/kunit/. 2662 2663 If unsure, say N. 2664 2665config SLUB_KUNIT_TEST 2666 tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS 2667 depends on SLUB_DEBUG && KUNIT 2668 default KUNIT_ALL_TESTS 2669 help 2670 This builds SLUB allocator unit test. 2671 Tests SLUB cache debugging functionality. 2672 For more information on KUnit and unit tests in general please refer 2673 to the KUnit documentation in Documentation/dev-tools/kunit/. 2674 2675 If unsure, say N. 2676 2677config RATIONAL_KUNIT_TEST 2678 tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS 2679 depends on KUNIT && RATIONAL 2680 default KUNIT_ALL_TESTS 2681 help 2682 This builds the rational math unit test. 2683 For more information on KUnit and unit tests in general please refer 2684 to the KUnit documentation in Documentation/dev-tools/kunit/. 2685 2686 If unsure, say N. 2687 2688config MEMCPY_KUNIT_TEST 2689 tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS 2690 depends on KUNIT 2691 default KUNIT_ALL_TESTS 2692 help 2693 Builds unit tests for memcpy(), memmove(), and memset() functions. 2694 For more information on KUnit and unit tests in general please refer 2695 to the KUnit documentation in Documentation/dev-tools/kunit/. 2696 2697 If unsure, say N. 2698 2699config MEMCPY_SLOW_KUNIT_TEST 2700 bool "Include exhaustive memcpy tests" 2701 depends on MEMCPY_KUNIT_TEST 2702 default y 2703 help 2704 Some memcpy tests are quite exhaustive in checking for overlaps 2705 and bit ranges. These can be very slow, so they are split out 2706 as a separate config, in case they need to be disabled. 2707 2708 Note this config option will be replaced by the use of KUnit test 2709 attributes. 2710 2711config IS_SIGNED_TYPE_KUNIT_TEST 2712 tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS 2713 depends on KUNIT 2714 default KUNIT_ALL_TESTS 2715 help 2716 Builds unit tests for the is_signed_type() macro. 2717 2718 For more information on KUnit and unit tests in general please refer 2719 to the KUnit documentation in Documentation/dev-tools/kunit/. 2720 2721 If unsure, say N. 2722 2723config OVERFLOW_KUNIT_TEST 2724 tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS 2725 depends on KUNIT 2726 default KUNIT_ALL_TESTS 2727 help 2728 Builds unit tests for the check_*_overflow(), size_*(), allocation, and 2729 related functions. 2730 2731 For more information on KUnit and unit tests in general please refer 2732 to the KUnit documentation in Documentation/dev-tools/kunit/. 2733 2734 If unsure, say N. 2735 2736config STACKINIT_KUNIT_TEST 2737 tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS 2738 depends on KUNIT 2739 default KUNIT_ALL_TESTS 2740 help 2741 Test if the kernel is zero-initializing stack variables and 2742 padding. Coverage is controlled by compiler flags, 2743 CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO, 2744 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2745 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2746 2747config FORTIFY_KUNIT_TEST 2748 tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS 2749 depends on KUNIT && FORTIFY_SOURCE 2750 default KUNIT_ALL_TESTS 2751 help 2752 Builds unit tests for checking internals of FORTIFY_SOURCE as used 2753 by the str*() and mem*() family of functions. For testing runtime 2754 traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests. 2755 2756config HW_BREAKPOINT_KUNIT_TEST 2757 bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS 2758 depends on HAVE_HW_BREAKPOINT 2759 depends on KUNIT=y 2760 default KUNIT_ALL_TESTS 2761 help 2762 Tests for hw_breakpoint constraints accounting. 2763 2764 If unsure, say N. 2765 2766config STRCAT_KUNIT_TEST 2767 tristate "Test strcat() family of functions at runtime" if !KUNIT_ALL_TESTS 2768 depends on KUNIT 2769 default KUNIT_ALL_TESTS 2770 2771config STRSCPY_KUNIT_TEST 2772 tristate "Test strscpy*() family of functions at runtime" if !KUNIT_ALL_TESTS 2773 depends on KUNIT 2774 default KUNIT_ALL_TESTS 2775 2776config SIPHASH_KUNIT_TEST 2777 tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS 2778 depends on KUNIT 2779 default KUNIT_ALL_TESTS 2780 help 2781 Enable this option to test the kernel's siphash (<linux/siphash.h>) hash 2782 functions on boot (or module load). 2783 2784 This is intended to help people writing architecture-specific 2785 optimized versions. If unsure, say N. 2786 2787config TEST_UDELAY 2788 tristate "udelay test driver" 2789 help 2790 This builds the "udelay_test" module that helps to make sure 2791 that udelay() is working properly. 2792 2793 If unsure, say N. 2794 2795config TEST_STATIC_KEYS 2796 tristate "Test static keys" 2797 depends on m 2798 help 2799 Test the static key interfaces. 2800 2801 If unsure, say N. 2802 2803config TEST_DYNAMIC_DEBUG 2804 tristate "Test DYNAMIC_DEBUG" 2805 depends on DYNAMIC_DEBUG 2806 help 2807 This module registers a tracer callback to count enabled 2808 pr_debugs in a 'do_debugging' function, then alters their 2809 enablements, calls the function, and compares counts. 2810 2811 If unsure, say N. 2812 2813config TEST_KMOD 2814 tristate "kmod stress tester" 2815 depends on m 2816 depends on NETDEVICES && NET_CORE && INET # for TUN 2817 depends on BLOCK 2818 depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS 2819 select TEST_LKM 2820 select XFS_FS 2821 select TUN 2822 select BTRFS_FS 2823 help 2824 Test the kernel's module loading mechanism: kmod. kmod implements 2825 support to load modules using the Linux kernel's usermode helper. 2826 This test provides a series of tests against kmod. 2827 2828 Although technically you can either build test_kmod as a module or 2829 into the kernel we disallow building it into the kernel since 2830 it stress tests request_module() and this will very likely cause 2831 some issues by taking over precious threads available from other 2832 module load requests, ultimately this could be fatal. 2833 2834 To run tests run: 2835 2836 tools/testing/selftests/kmod/kmod.sh --help 2837 2838 If unsure, say N. 2839 2840config TEST_DEBUG_VIRTUAL 2841 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 2842 depends on DEBUG_VIRTUAL 2843 help 2844 Test the kernel's ability to detect incorrect calls to 2845 virt_to_phys() done against the non-linear part of the 2846 kernel's virtual address map. 2847 2848 If unsure, say N. 2849 2850config TEST_MEMCAT_P 2851 tristate "Test memcat_p() helper function" 2852 help 2853 Test the memcat_p() helper for correctly merging two 2854 pointer arrays together. 2855 2856 If unsure, say N. 2857 2858config TEST_LIVEPATCH 2859 tristate "Test livepatching" 2860 default n 2861 depends on DYNAMIC_DEBUG 2862 depends on LIVEPATCH 2863 depends on m 2864 help 2865 Test kernel livepatching features for correctness. The tests will 2866 load test modules that will be livepatched in various scenarios. 2867 2868 To run all the livepatching tests: 2869 2870 make -C tools/testing/selftests TARGETS=livepatch run_tests 2871 2872 Alternatively, individual tests may be invoked: 2873 2874 tools/testing/selftests/livepatch/test-callbacks.sh 2875 tools/testing/selftests/livepatch/test-livepatch.sh 2876 tools/testing/selftests/livepatch/test-shadow-vars.sh 2877 2878 If unsure, say N. 2879 2880config TEST_OBJAGG 2881 tristate "Perform selftest on object aggreration manager" 2882 default n 2883 depends on OBJAGG 2884 help 2885 Enable this option to test object aggregation manager on boot 2886 (or module load). 2887 2888config TEST_MEMINIT 2889 tristate "Test heap/page initialization" 2890 help 2891 Test if the kernel is zero-initializing heap and page allocations. 2892 This can be useful to test init_on_alloc and init_on_free features. 2893 2894 If unsure, say N. 2895 2896config TEST_HMM 2897 tristate "Test HMM (Heterogeneous Memory Management)" 2898 depends on TRANSPARENT_HUGEPAGE 2899 depends on DEVICE_PRIVATE 2900 select HMM_MIRROR 2901 select MMU_NOTIFIER 2902 help 2903 This is a pseudo device driver solely for testing HMM. 2904 Say M here if you want to build the HMM test module. 2905 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests. 2906 2907 If unsure, say N. 2908 2909config TEST_FREE_PAGES 2910 tristate "Test freeing pages" 2911 help 2912 Test that a memory leak does not occur due to a race between 2913 freeing a block of pages and a speculative page reference. 2914 Loading this module is safe if your kernel has the bug fixed. 2915 If the bug is not fixed, it will leak gigabytes of memory and 2916 probably OOM your system. 2917 2918config TEST_FPU 2919 tristate "Test floating point operations in kernel space" 2920 depends on X86 && !KCOV_INSTRUMENT_ALL 2921 help 2922 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu 2923 which will trigger a sequence of floating point operations. This is used 2924 for self-testing floating point control register setting in 2925 kernel_fpu_begin(). 2926 2927 If unsure, say N. 2928 2929config TEST_CLOCKSOURCE_WATCHDOG 2930 tristate "Test clocksource watchdog in kernel space" 2931 depends on CLOCKSOURCE_WATCHDOG 2932 help 2933 Enable this option to create a kernel module that will trigger 2934 a test of the clocksource watchdog. This module may be loaded 2935 via modprobe or insmod in which case it will run upon being 2936 loaded, or it may be built in, in which case it will run 2937 shortly after boot. 2938 2939 If unsure, say N. 2940 2941endif # RUNTIME_TESTING_MENU 2942 2943config ARCH_USE_MEMTEST 2944 bool 2945 help 2946 An architecture should select this when it uses early_memtest() 2947 during boot process. 2948 2949config MEMTEST 2950 bool "Memtest" 2951 depends on ARCH_USE_MEMTEST 2952 help 2953 This option adds a kernel parameter 'memtest', which allows memtest 2954 to be set and executed. 2955 memtest=0, mean disabled; -- default 2956 memtest=1, mean do 1 test pattern; 2957 ... 2958 memtest=17, mean do 17 test patterns. 2959 If you are unsure how to answer this question, answer N. 2960 2961 2962 2963config HYPERV_TESTING 2964 bool "Microsoft Hyper-V driver testing" 2965 default n 2966 depends on HYPERV && DEBUG_FS 2967 help 2968 Select this option to enable Hyper-V vmbus testing. 2969 2970endmenu # "Kernel Testing and Coverage" 2971 2972menu "Rust hacking" 2973 2974config RUST_DEBUG_ASSERTIONS 2975 bool "Debug assertions" 2976 depends on RUST 2977 help 2978 Enables rustc's `-Cdebug-assertions` codegen option. 2979 2980 This flag lets you turn `cfg(debug_assertions)` conditional 2981 compilation on or off. This can be used to enable extra debugging 2982 code in development but not in production. For example, it controls 2983 the behavior of the standard library's `debug_assert!` macro. 2984 2985 Note that this will apply to all Rust code, including `core`. 2986 2987 If unsure, say N. 2988 2989config RUST_OVERFLOW_CHECKS 2990 bool "Overflow checks" 2991 default y 2992 depends on RUST 2993 help 2994 Enables rustc's `-Coverflow-checks` codegen option. 2995 2996 This flag allows you to control the behavior of runtime integer 2997 overflow. When overflow-checks are enabled, a Rust panic will occur 2998 on overflow. 2999 3000 Note that this will apply to all Rust code, including `core`. 3001 3002 If unsure, say Y. 3003 3004config RUST_BUILD_ASSERT_ALLOW 3005 bool "Allow unoptimized build-time assertions" 3006 depends on RUST 3007 help 3008 Controls how are `build_error!` and `build_assert!` handled during build. 3009 3010 If calls to them exist in the binary, it may indicate a violated invariant 3011 or that the optimizer failed to verify the invariant during compilation. 3012 3013 This should not happen, thus by default the build is aborted. However, 3014 as an escape hatch, you can choose Y here to ignore them during build 3015 and let the check be carried at runtime (with `panic!` being called if 3016 the check fails). 3017 3018 If unsure, say N. 3019 3020config RUST_KERNEL_DOCTESTS 3021 bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS 3022 depends on RUST && KUNIT=y 3023 default KUNIT_ALL_TESTS 3024 help 3025 This builds the documentation tests of the `kernel` crate 3026 as KUnit tests. 3027 3028 For more information on KUnit and unit tests in general, 3029 please refer to the KUnit documentation in Documentation/dev-tools/kunit/. 3030 3031 If unsure, say N. 3032 3033endmenu # "Rust" 3034 3035endmenu # Kernel hacking 3036