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 type information" 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 bool "Generate BTF type information for kernel modules" 408 default y 409 depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF 410 help 411 Generate compact split BTF type information for kernel modules. 412 413config MODULE_ALLOW_BTF_MISMATCH 414 bool "Allow loading modules with non-matching BTF type info" 415 depends on DEBUG_INFO_BTF_MODULES 416 help 417 For modules whose split BTF does not match vmlinux, load without 418 BTF rather than refusing to load. The default behavior with 419 module BTF enabled is to reject modules with such mismatches; 420 this option will still load module BTF where possible but ignore 421 it when a mismatch is found. 422 423config GDB_SCRIPTS 424 bool "Provide GDB scripts for kernel debugging" 425 help 426 This creates the required links to GDB helper scripts in the 427 build directory. If you load vmlinux into gdb, the helper 428 scripts will be automatically imported by gdb as well, and 429 additional functions are available to analyze a Linux kernel 430 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst 431 for further details. 432 433endif # DEBUG_INFO 434 435config FRAME_WARN 436 int "Warn for stack frames larger than" 437 range 0 8192 438 default 0 if KMSAN 439 default 2048 if GCC_PLUGIN_LATENT_ENTROPY 440 default 2048 if PARISC 441 default 1536 if (!64BIT && XTENSA) 442 default 1280 if KASAN && !64BIT 443 default 1024 if !64BIT 444 default 2048 if 64BIT 445 help 446 Tell the compiler to warn at build time for stack frames larger than this. 447 Setting this too low will cause a lot of warnings. 448 Setting it to 0 disables the warning. 449 450config STRIP_ASM_SYMS 451 bool "Strip assembler-generated symbols during link" 452 default n 453 help 454 Strip internal assembler-generated symbols during a link (symbols 455 that look like '.Lxxx') so they don't pollute the output of 456 get_wchan() and suchlike. 457 458config READABLE_ASM 459 bool "Generate readable assembler code" 460 depends on DEBUG_KERNEL 461 depends on CC_IS_GCC 462 help 463 Disable some compiler optimizations that tend to generate human unreadable 464 assembler output. This may make the kernel slightly slower, but it helps 465 to keep kernel developers who have to stare a lot at assembler listings 466 sane. 467 468config HEADERS_INSTALL 469 bool "Install uapi headers to usr/include" 470 depends on !UML 471 help 472 This option will install uapi headers (headers exported to user-space) 473 into the usr/include directory for use during the kernel build. 474 This is unneeded for building the kernel itself, but needed for some 475 user-space program samples. It is also needed by some features such 476 as uapi header sanity checks. 477 478config DEBUG_SECTION_MISMATCH 479 bool "Enable full Section mismatch analysis" 480 depends on CC_IS_GCC 481 help 482 The section mismatch analysis checks if there are illegal 483 references from one section to another section. 484 During linktime or runtime, some sections are dropped; 485 any use of code/data previously in these sections would 486 most likely result in an oops. 487 In the code, functions and variables are annotated with 488 __init,, etc. (see the full list in include/linux/init.h), 489 which results in the code/data being placed in specific sections. 490 The section mismatch analysis is always performed after a full 491 kernel build, and enabling this option causes the following 492 additional step to occur: 493 - Add the option -fno-inline-functions-called-once to gcc commands. 494 When inlining a function annotated with __init in a non-init 495 function, we would lose the section information and thus 496 the analysis would not catch the illegal reference. 497 This option tells gcc to inline less (but it does result in 498 a larger kernel). 499 500config SECTION_MISMATCH_WARN_ONLY 501 bool "Make section mismatch errors non-fatal" 502 default y 503 help 504 If you say N here, the build process will fail if there are any 505 section mismatch, instead of just throwing warnings. 506 507 If unsure, say Y. 508 509config DEBUG_FORCE_FUNCTION_ALIGN_64B 510 bool "Force all function address 64B aligned" 511 depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC || RISCV || S390) 512 select FUNCTION_ALIGNMENT_64B 513 help 514 There are cases that a commit from one domain changes the function 515 address alignment of other domains, and cause magic performance 516 bump (regression or improvement). Enable this option will help to 517 verify if the bump is caused by function alignment changes, while 518 it will slightly increase the kernel size and affect icache usage. 519 520 It is mainly for debug and performance tuning use. 521 522# 523# Select this config option from the architecture Kconfig, if it 524# is preferred to always offer frame pointers as a config 525# option on the architecture (regardless of KERNEL_DEBUG): 526# 527config ARCH_WANT_FRAME_POINTERS 528 bool 529 530config FRAME_POINTER 531 bool "Compile the kernel with frame pointers" 532 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS 533 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 534 help 535 If you say Y here the resulting kernel image will be slightly 536 larger and slower, but it gives very useful debugging information 537 in case of kernel bugs. (precise oopses/stacktraces/warnings) 538 539config OBJTOOL 540 bool 541 542config STACK_VALIDATION 543 bool "Compile-time stack metadata validation" 544 depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER 545 select OBJTOOL 546 default n 547 help 548 Validate frame pointer rules at compile-time. This helps ensure that 549 runtime stack traces are more reliable. 550 551 For more information, see 552 tools/objtool/Documentation/objtool.txt. 553 554config NOINSTR_VALIDATION 555 bool 556 depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY 557 select OBJTOOL 558 default y 559 560config VMLINUX_MAP 561 bool "Generate vmlinux.map file when linking" 562 depends on EXPERT 563 help 564 Selecting this option will pass "-Map=vmlinux.map" to ld 565 when linking vmlinux. That file can be useful for verifying 566 and debugging magic section games, and for seeing which 567 pieces of code get eliminated with 568 CONFIG_LD_DEAD_CODE_DATA_ELIMINATION. 569 570config DEBUG_FORCE_WEAK_PER_CPU 571 bool "Force weak per-cpu definitions" 572 depends on DEBUG_KERNEL 573 help 574 s390 and alpha require percpu variables in modules to be 575 defined weak to work around addressing range issue which 576 puts the following two restrictions on percpu variable 577 definitions. 578 579 1. percpu symbols must be unique whether static or not 580 2. percpu variables can't be defined inside a function 581 582 To ensure that generic code follows the above rules, this 583 option forces all percpu variables to be defined as weak. 584 585endmenu # "Compiler options" 586 587menu "Generic Kernel Debugging Instruments" 588 589config MAGIC_SYSRQ 590 bool "Magic SysRq key" 591 depends on !UML 592 help 593 If you say Y here, you will have some control over the system even 594 if the system crashes for example during kernel debugging (e.g., you 595 will be able to flush the buffer cache to disk, reboot the system 596 immediately or dump some status information). This is accomplished 597 by pressing various keys while holding SysRq (Alt+PrintScreen). It 598 also works on a serial console (on PC hardware at least), if you 599 send a BREAK and then within 5 seconds a command keypress. The 600 keys are documented in <file:Documentation/admin-guide/sysrq.rst>. 601 Don't say Y unless you really know what this hack does. 602 603config MAGIC_SYSRQ_DEFAULT_ENABLE 604 hex "Enable magic SysRq key functions by default" 605 depends on MAGIC_SYSRQ 606 default 0x1 607 help 608 Specifies which SysRq key functions are enabled by default. 609 This may be set to 1 or 0 to enable or disable them all, or 610 to a bitmask as described in Documentation/admin-guide/sysrq.rst. 611 612config MAGIC_SYSRQ_SERIAL 613 bool "Enable magic SysRq key over serial" 614 depends on MAGIC_SYSRQ 615 default y 616 help 617 Many embedded boards have a disconnected TTL level serial which can 618 generate some garbage that can lead to spurious false sysrq detects. 619 This option allows you to decide whether you want to enable the 620 magic SysRq key. 621 622config MAGIC_SYSRQ_SERIAL_SEQUENCE 623 string "Char sequence that enables magic SysRq over serial" 624 depends on MAGIC_SYSRQ_SERIAL 625 default "" 626 help 627 Specifies a sequence of characters that can follow BREAK to enable 628 SysRq on a serial console. 629 630 If unsure, leave an empty string and the option will not be enabled. 631 632config DEBUG_FS 633 bool "Debug Filesystem" 634 help 635 debugfs is a virtual file system that kernel developers use to put 636 debugging files into. Enable this option to be able to read and 637 write to these files. 638 639 For detailed documentation on the debugfs API, see 640 Documentation/filesystems/. 641 642 If unsure, say N. 643 644choice 645 prompt "Debugfs default access" 646 depends on DEBUG_FS 647 default DEBUG_FS_ALLOW_ALL 648 help 649 This selects the default access restrictions for debugfs. 650 It can be overridden with kernel command line option 651 debugfs=[on,no-mount,off]. The restrictions apply for API access 652 and filesystem registration. 653 654config DEBUG_FS_ALLOW_ALL 655 bool "Access normal" 656 help 657 No restrictions apply. Both API and filesystem registration 658 is on. This is the normal default operation. 659 660config DEBUG_FS_DISALLOW_MOUNT 661 bool "Do not register debugfs as filesystem" 662 help 663 The API is open but filesystem is not loaded. Clients can still do 664 their work and read with debug tools that do not need 665 debugfs filesystem. 666 667config DEBUG_FS_ALLOW_NONE 668 bool "No access" 669 help 670 Access is off. Clients get -PERM when trying to create nodes in 671 debugfs tree and debugfs is not registered as a filesystem. 672 Client can then back-off or continue without debugfs access. 673 674endchoice 675 676source "lib/Kconfig.kgdb" 677source "lib/Kconfig.ubsan" 678source "lib/Kconfig.kcsan" 679 680endmenu 681 682menu "Networking Debugging" 683 684source "net/Kconfig.debug" 685 686endmenu # "Networking Debugging" 687 688menu "Memory Debugging" 689 690source "mm/Kconfig.debug" 691 692config DEBUG_OBJECTS 693 bool "Debug object operations" 694 depends on DEBUG_KERNEL 695 help 696 If you say Y here, additional code will be inserted into the 697 kernel to track the life time of various objects and validate 698 the operations on those objects. 699 700config DEBUG_OBJECTS_SELFTEST 701 bool "Debug objects selftest" 702 depends on DEBUG_OBJECTS 703 help 704 This enables the selftest of the object debug code. 705 706config DEBUG_OBJECTS_FREE 707 bool "Debug objects in freed memory" 708 depends on DEBUG_OBJECTS 709 help 710 This enables checks whether a k/v free operation frees an area 711 which contains an object which has not been deactivated 712 properly. This can make kmalloc/kfree-intensive workloads 713 much slower. 714 715config DEBUG_OBJECTS_TIMERS 716 bool "Debug timer objects" 717 depends on DEBUG_OBJECTS 718 help 719 If you say Y here, additional code will be inserted into the 720 timer routines to track the life time of timer objects and 721 validate the timer operations. 722 723config DEBUG_OBJECTS_WORK 724 bool "Debug work objects" 725 depends on DEBUG_OBJECTS 726 help 727 If you say Y here, additional code will be inserted into the 728 work queue routines to track the life time of work objects and 729 validate the work operations. 730 731config DEBUG_OBJECTS_RCU_HEAD 732 bool "Debug RCU callbacks objects" 733 depends on DEBUG_OBJECTS 734 help 735 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 736 737config DEBUG_OBJECTS_PERCPU_COUNTER 738 bool "Debug percpu counter objects" 739 depends on DEBUG_OBJECTS 740 help 741 If you say Y here, additional code will be inserted into the 742 percpu counter routines to track the life time of percpu counter 743 objects and validate the percpu counter operations. 744 745config DEBUG_OBJECTS_ENABLE_DEFAULT 746 int "debug_objects bootup default value (0-1)" 747 range 0 1 748 default "1" 749 depends on DEBUG_OBJECTS 750 help 751 Debug objects boot parameter default value 752 753config SHRINKER_DEBUG 754 bool "Enable shrinker debugging support" 755 depends on DEBUG_FS 756 help 757 Say Y to enable the shrinker debugfs interface which provides 758 visibility into the kernel memory shrinkers subsystem. 759 Disable it to avoid an extra memory footprint. 760 761config DEBUG_STACK_USAGE 762 bool "Stack utilization instrumentation" 763 depends on DEBUG_KERNEL && !IA64 764 help 765 Enables the display of the minimum amount of free stack which each 766 task has ever had available in the sysrq-T and sysrq-P debug output. 767 768 This option will slow down process creation somewhat. 769 770config SCHED_STACK_END_CHECK 771 bool "Detect stack corruption on calls to schedule()" 772 depends on DEBUG_KERNEL 773 default n 774 help 775 This option checks for a stack overrun on calls to schedule(). 776 If the stack end location is found to be over written always panic as 777 the content of the corrupted region can no longer be trusted. 778 This is to ensure no erroneous behaviour occurs which could result in 779 data corruption or a sporadic crash at a later stage once the region 780 is examined. The runtime overhead introduced is minimal. 781 782config ARCH_HAS_DEBUG_VM_PGTABLE 783 bool 784 help 785 An architecture should select this when it can successfully 786 build and run DEBUG_VM_PGTABLE. 787 788config DEBUG_VM_IRQSOFF 789 def_bool DEBUG_VM && !PREEMPT_RT 790 791config DEBUG_VM 792 bool "Debug VM" 793 depends on DEBUG_KERNEL 794 help 795 Enable this to turn on extended checks in the virtual-memory system 796 that may impact performance. 797 798 If unsure, say N. 799 800config DEBUG_VM_SHOOT_LAZIES 801 bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation" 802 depends on DEBUG_VM 803 depends on MMU_LAZY_TLB_SHOOTDOWN 804 help 805 Enable additional IPIs that ensure lazy tlb mm references are removed 806 before the mm is freed. 807 808 If unsure, say N. 809 810config DEBUG_VM_MAPLE_TREE 811 bool "Debug VM maple trees" 812 depends on DEBUG_VM 813 select DEBUG_MAPLE_TREE 814 help 815 Enable VM maple tree debugging information and extra validations. 816 817 If unsure, say N. 818 819config DEBUG_VM_RB 820 bool "Debug VM red-black trees" 821 depends on DEBUG_VM 822 help 823 Enable VM red-black tree debugging information and extra validations. 824 825 If unsure, say N. 826 827config DEBUG_VM_PGFLAGS 828 bool "Debug page-flags operations" 829 depends on DEBUG_VM 830 help 831 Enables extra validation on page flags operations. 832 833 If unsure, say N. 834 835config DEBUG_VM_PGTABLE 836 bool "Debug arch page table for semantics compliance" 837 depends on MMU 838 depends on ARCH_HAS_DEBUG_VM_PGTABLE 839 default y if DEBUG_VM 840 help 841 This option provides a debug method which can be used to test 842 architecture page table helper functions on various platforms in 843 verifying if they comply with expected generic MM semantics. This 844 will help architecture code in making sure that any changes or 845 new additions of these helpers still conform to expected 846 semantics of the generic MM. Platforms will have to opt in for 847 this through ARCH_HAS_DEBUG_VM_PGTABLE. 848 849 If unsure, say N. 850 851config ARCH_HAS_DEBUG_VIRTUAL 852 bool 853 854config DEBUG_VIRTUAL 855 bool "Debug VM translations" 856 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL 857 help 858 Enable some costly sanity checks in virtual to page code. This can 859 catch mistakes with virt_to_page() and friends. 860 861 If unsure, say N. 862 863config DEBUG_NOMMU_REGIONS 864 bool "Debug the global anon/private NOMMU mapping region tree" 865 depends on DEBUG_KERNEL && !MMU 866 help 867 This option causes the global tree of anonymous and private mapping 868 regions to be regularly checked for invalid topology. 869 870config DEBUG_MEMORY_INIT 871 bool "Debug memory initialisation" if EXPERT 872 default !EXPERT 873 help 874 Enable this for additional checks during memory initialisation. 875 The sanity checks verify aspects of the VM such as the memory model 876 and other information provided by the architecture. Verbose 877 information will be printed at KERN_DEBUG loglevel depending 878 on the mminit_loglevel= command-line option. 879 880 If unsure, say Y 881 882config MEMORY_NOTIFIER_ERROR_INJECT 883 tristate "Memory hotplug notifier error injection module" 884 depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION 885 help 886 This option provides the ability to inject artificial errors to 887 memory hotplug notifier chain callbacks. It is controlled through 888 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 889 890 If the notifier call chain should be failed with some events 891 notified, write the error code to "actions/<notifier event>/error". 892 893 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 894 895 # cd /sys/kernel/debug/notifier-error-inject/memory 896 # echo -12 > actions/MEM_GOING_OFFLINE/error 897 # echo offline > /sys/devices/system/memory/memoryXXX/state 898 bash: echo: write error: Cannot allocate memory 899 900 To compile this code as a module, choose M here: the module will 901 be called memory-notifier-error-inject. 902 903 If unsure, say N. 904 905config DEBUG_PER_CPU_MAPS 906 bool "Debug access to per_cpu maps" 907 depends on DEBUG_KERNEL 908 depends on SMP 909 help 910 Say Y to verify that the per_cpu map being accessed has 911 been set up. This adds a fair amount of code to kernel memory 912 and decreases performance. 913 914 Say N if unsure. 915 916config DEBUG_KMAP_LOCAL 917 bool "Debug kmap_local temporary mappings" 918 depends on DEBUG_KERNEL && KMAP_LOCAL 919 help 920 This option enables additional error checking for the kmap_local 921 infrastructure. Disable for production use. 922 923config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 924 bool 925 926config DEBUG_KMAP_LOCAL_FORCE_MAP 927 bool "Enforce kmap_local temporary mappings" 928 depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 929 select KMAP_LOCAL 930 select DEBUG_KMAP_LOCAL 931 help 932 This option enforces temporary mappings through the kmap_local 933 mechanism for non-highmem pages and on non-highmem systems. 934 Disable this for production systems! 935 936config DEBUG_HIGHMEM 937 bool "Highmem debugging" 938 depends on DEBUG_KERNEL && HIGHMEM 939 select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 940 select DEBUG_KMAP_LOCAL 941 help 942 This option enables additional error checking for high memory 943 systems. Disable for production systems. 944 945config HAVE_DEBUG_STACKOVERFLOW 946 bool 947 948config DEBUG_STACKOVERFLOW 949 bool "Check for stack overflows" 950 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 951 help 952 Say Y here if you want to check for overflows of kernel, IRQ 953 and exception stacks (if your architecture uses them). This 954 option will show detailed messages if free stack space drops 955 below a certain limit. 956 957 These kinds of bugs usually occur when call-chains in the 958 kernel get too deep, especially when interrupts are 959 involved. 960 961 Use this in cases where you see apparently random memory 962 corruption, especially if it appears in 'struct thread_info' 963 964 If in doubt, say "N". 965 966source "lib/Kconfig.kasan" 967source "lib/Kconfig.kfence" 968source "lib/Kconfig.kmsan" 969 970endmenu # "Memory Debugging" 971 972config DEBUG_SHIRQ 973 bool "Debug shared IRQ handlers" 974 depends on DEBUG_KERNEL 975 help 976 Enable this to generate a spurious interrupt just before a shared 977 interrupt handler is deregistered (generating one when registering 978 is currently disabled). Drivers need to handle this correctly. Some 979 don't and need to be caught. 980 981menu "Debug Oops, Lockups and Hangs" 982 983config PANIC_ON_OOPS 984 bool "Panic on Oops" 985 help 986 Say Y here to enable the kernel to panic when it oopses. This 987 has the same effect as setting oops=panic on the kernel command 988 line. 989 990 This feature is useful to ensure that the kernel does not do 991 anything erroneous after an oops which could result in data 992 corruption or other issues. 993 994 Say N if unsure. 995 996config PANIC_ON_OOPS_VALUE 997 int 998 range 0 1 999 default 0 if !PANIC_ON_OOPS 1000 default 1 if PANIC_ON_OOPS 1001 1002config PANIC_TIMEOUT 1003 int "panic timeout" 1004 default 0 1005 help 1006 Set the timeout value (in seconds) until a reboot occurs when 1007 the kernel panics. If n = 0, then we wait forever. A timeout 1008 value n > 0 will wait n seconds before rebooting, while a timeout 1009 value n < 0 will reboot immediately. 1010 1011config LOCKUP_DETECTOR 1012 bool 1013 1014config SOFTLOCKUP_DETECTOR 1015 bool "Detect Soft Lockups" 1016 depends on DEBUG_KERNEL && !S390 1017 select LOCKUP_DETECTOR 1018 help 1019 Say Y here to enable the kernel to act as a watchdog to detect 1020 soft lockups. 1021 1022 Softlockups are bugs that cause the kernel to loop in kernel 1023 mode for more than 20 seconds, without giving other tasks a 1024 chance to run. The current stack trace is displayed upon 1025 detection and the system will stay locked up. 1026 1027config BOOTPARAM_SOFTLOCKUP_PANIC 1028 bool "Panic (Reboot) On Soft Lockups" 1029 depends on SOFTLOCKUP_DETECTOR 1030 help 1031 Say Y here to enable the kernel to panic on "soft lockups", 1032 which are bugs that cause the kernel to loop in kernel 1033 mode for more than 20 seconds (configurable using the watchdog_thresh 1034 sysctl), without giving other tasks a chance to run. 1035 1036 The panic can be used in combination with panic_timeout, 1037 to cause the system to reboot automatically after a 1038 lockup has been detected. This feature is useful for 1039 high-availability systems that have uptime guarantees and 1040 where a lockup must be resolved ASAP. 1041 1042 Say N if unsure. 1043 1044config HAVE_HARDLOCKUP_DETECTOR_BUDDY 1045 bool 1046 depends on SMP 1047 default y 1048 1049# 1050# Global switch whether to build a hardlockup detector at all. It is available 1051# only when the architecture supports at least one implementation. There are 1052# two exceptions. The hardlockup detector is never enabled on: 1053# 1054# s390: it reported many false positives there 1055# 1056# sparc64: has a custom implementation which is not using the common 1057# hardlockup command line options and sysctl interface. 1058# 1059config HARDLOCKUP_DETECTOR 1060 bool "Detect Hard Lockups" 1061 depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64 1062 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH 1063 imply HARDLOCKUP_DETECTOR_PERF 1064 imply HARDLOCKUP_DETECTOR_BUDDY 1065 imply HARDLOCKUP_DETECTOR_ARCH 1066 select LOCKUP_DETECTOR 1067 1068 help 1069 Say Y here to enable the kernel to act as a watchdog to detect 1070 hard lockups. 1071 1072 Hardlockups are bugs that cause the CPU to loop in kernel mode 1073 for more than 10 seconds, without letting other interrupts have a 1074 chance to run. The current stack trace is displayed upon detection 1075 and the system will stay locked up. 1076 1077# 1078# Note that arch-specific variants are always preferred. 1079# 1080config HARDLOCKUP_DETECTOR_PREFER_BUDDY 1081 bool "Prefer the buddy CPU hardlockup detector" 1082 depends on HARDLOCKUP_DETECTOR 1083 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY 1084 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1085 help 1086 Say Y here to prefer the buddy hardlockup detector over the perf one. 1087 1088 With the buddy detector, each CPU uses its softlockup hrtimer 1089 to check that the next CPU is processing hrtimer interrupts by 1090 verifying that a counter is increasing. 1091 1092 This hardlockup detector is useful on systems that don't have 1093 an arch-specific hardlockup detector or if resources needed 1094 for the hardlockup detector are better used for other things. 1095 1096config HARDLOCKUP_DETECTOR_PERF 1097 bool 1098 depends on HARDLOCKUP_DETECTOR 1099 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY 1100 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1101 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1102 1103config HARDLOCKUP_DETECTOR_BUDDY 1104 bool 1105 depends on HARDLOCKUP_DETECTOR 1106 depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY 1107 depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY 1108 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1109 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1110 1111config HARDLOCKUP_DETECTOR_ARCH 1112 bool 1113 depends on HARDLOCKUP_DETECTOR 1114 depends on HAVE_HARDLOCKUP_DETECTOR_ARCH 1115 help 1116 The arch-specific implementation of the hardlockup detector will 1117 be used. 1118 1119# 1120# Both the "perf" and "buddy" hardlockup detectors count hrtimer 1121# interrupts. This config enables functions managing this common code. 1122# 1123config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1124 bool 1125 select SOFTLOCKUP_DETECTOR 1126 1127# 1128# Enables a timestamp based low pass filter to compensate for perf based 1129# hard lockup detection which runs too fast due to turbo modes. 1130# 1131config HARDLOCKUP_CHECK_TIMESTAMP 1132 bool 1133 1134config BOOTPARAM_HARDLOCKUP_PANIC 1135 bool "Panic (Reboot) On Hard Lockups" 1136 depends on HARDLOCKUP_DETECTOR 1137 help 1138 Say Y here to enable the kernel to panic on "hard lockups", 1139 which are bugs that cause the kernel to loop in kernel 1140 mode with interrupts disabled for more than 10 seconds (configurable 1141 using the watchdog_thresh sysctl). 1142 1143 Say N if unsure. 1144 1145config DETECT_HUNG_TASK 1146 bool "Detect Hung Tasks" 1147 depends on DEBUG_KERNEL 1148 default SOFTLOCKUP_DETECTOR 1149 help 1150 Say Y here to enable the kernel to detect "hung tasks", 1151 which are bugs that cause the task to be stuck in 1152 uninterruptible "D" state indefinitely. 1153 1154 When a hung task is detected, the kernel will print the 1155 current stack trace (which you should report), but the 1156 task will stay in uninterruptible state. If lockdep is 1157 enabled then all held locks will also be reported. This 1158 feature has negligible overhead. 1159 1160config DEFAULT_HUNG_TASK_TIMEOUT 1161 int "Default timeout for hung task detection (in seconds)" 1162 depends on DETECT_HUNG_TASK 1163 default 120 1164 help 1165 This option controls the default timeout (in seconds) used 1166 to determine when a task has become non-responsive and should 1167 be considered hung. 1168 1169 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 1170 sysctl or by writing a value to 1171 /proc/sys/kernel/hung_task_timeout_secs. 1172 1173 A timeout of 0 disables the check. The default is two minutes. 1174 Keeping the default should be fine in most cases. 1175 1176config BOOTPARAM_HUNG_TASK_PANIC 1177 bool "Panic (Reboot) On Hung Tasks" 1178 depends on DETECT_HUNG_TASK 1179 help 1180 Say Y here to enable the kernel to panic on "hung tasks", 1181 which are bugs that cause the kernel to leave a task stuck 1182 in uninterruptible "D" state. 1183 1184 The panic can be used in combination with panic_timeout, 1185 to cause the system to reboot automatically after a 1186 hung task has been detected. This feature is useful for 1187 high-availability systems that have uptime guarantees and 1188 where a hung tasks must be resolved ASAP. 1189 1190 Say N if unsure. 1191 1192config BOOTPARAM_HUNG_TASK_PANIC_VALUE 1193 int 1194 depends on DETECT_HUNG_TASK 1195 range 0 1 1196 default 0 if !BOOTPARAM_HUNG_TASK_PANIC 1197 default 1 if BOOTPARAM_HUNG_TASK_PANIC 1198 1199config WQ_WATCHDOG 1200 bool "Detect Workqueue Stalls" 1201 depends on DEBUG_KERNEL 1202 help 1203 Say Y here to enable stall detection on workqueues. If a 1204 worker pool doesn't make forward progress on a pending work 1205 item for over a given amount of time, 30s by default, a 1206 warning message is printed along with dump of workqueue 1207 state. This can be configured through kernel parameter 1208 "workqueue.watchdog_thresh" and its sysfs counterpart. 1209 1210config WQ_CPU_INTENSIVE_REPORT 1211 bool "Report per-cpu work items which hog CPU for too long" 1212 depends on DEBUG_KERNEL 1213 help 1214 Say Y here to enable reporting of concurrency-managed per-cpu work 1215 items that hog CPUs for longer than 1216 workqueue.cpu_intensive_thresh_us. Workqueue automatically 1217 detects and excludes them from concurrency management to prevent 1218 them from stalling other per-cpu work items. Occassional 1219 triggering may not necessarily indicate a problem. Repeated 1220 triggering likely indicates that the work item should be switched 1221 to use an unbound workqueue. 1222 1223config TEST_LOCKUP 1224 tristate "Test module to generate lockups" 1225 depends on m 1226 help 1227 This builds the "test_lockup" module that helps to make sure 1228 that watchdogs and lockup detectors are working properly. 1229 1230 Depending on module parameters it could emulate soft or hard 1231 lockup, "hung task", or locking arbitrary lock for a long time. 1232 Also it could generate series of lockups with cooling-down periods. 1233 1234 If unsure, say N. 1235 1236endmenu # "Debug lockups and hangs" 1237 1238menu "Scheduler Debugging" 1239 1240config SCHED_DEBUG 1241 bool "Collect scheduler debugging info" 1242 depends on DEBUG_KERNEL && DEBUG_FS 1243 default y 1244 help 1245 If you say Y here, the /sys/kernel/debug/sched file will be provided 1246 that can help debug the scheduler. The runtime overhead of this 1247 option is minimal. 1248 1249config SCHED_INFO 1250 bool 1251 default n 1252 1253config SCHEDSTATS 1254 bool "Collect scheduler statistics" 1255 depends on DEBUG_KERNEL && PROC_FS 1256 select SCHED_INFO 1257 help 1258 If you say Y here, additional code will be inserted into the 1259 scheduler and related routines to collect statistics about 1260 scheduler behavior and provide them in /proc/schedstat. These 1261 stats may be useful for both tuning and debugging the scheduler 1262 If you aren't debugging the scheduler or trying to tune a specific 1263 application, you can say N to avoid the very slight overhead 1264 this adds. 1265 1266endmenu 1267 1268config DEBUG_TIMEKEEPING 1269 bool "Enable extra timekeeping sanity checking" 1270 help 1271 This option will enable additional timekeeping sanity checks 1272 which may be helpful when diagnosing issues where timekeeping 1273 problems are suspected. 1274 1275 This may include checks in the timekeeping hotpaths, so this 1276 option may have a (very small) performance impact to some 1277 workloads. 1278 1279 If unsure, say N. 1280 1281config DEBUG_PREEMPT 1282 bool "Debug preemptible kernel" 1283 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1284 help 1285 If you say Y here then the kernel will use a debug variant of the 1286 commonly used smp_processor_id() function and will print warnings 1287 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1288 will detect preemption count underflows. 1289 1290 This option has potential to introduce high runtime overhead, 1291 depending on workload as it triggers debugging routines for each 1292 this_cpu operation. It should only be used for debugging purposes. 1293 1294menu "Lock Debugging (spinlocks, mutexes, etc...)" 1295 1296config LOCK_DEBUGGING_SUPPORT 1297 bool 1298 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1299 default y 1300 1301config PROVE_LOCKING 1302 bool "Lock debugging: prove locking correctness" 1303 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1304 select LOCKDEP 1305 select DEBUG_SPINLOCK 1306 select DEBUG_MUTEXES if !PREEMPT_RT 1307 select DEBUG_RT_MUTEXES if RT_MUTEXES 1308 select DEBUG_RWSEMS 1309 select DEBUG_WW_MUTEX_SLOWPATH 1310 select DEBUG_LOCK_ALLOC 1311 select PREEMPT_COUNT if !ARCH_NO_PREEMPT 1312 select TRACE_IRQFLAGS 1313 default n 1314 help 1315 This feature enables the kernel to prove that all locking 1316 that occurs in the kernel runtime is mathematically 1317 correct: that under no circumstance could an arbitrary (and 1318 not yet triggered) combination of observed locking 1319 sequences (on an arbitrary number of CPUs, running an 1320 arbitrary number of tasks and interrupt contexts) cause a 1321 deadlock. 1322 1323 In short, this feature enables the kernel to report locking 1324 related deadlocks before they actually occur. 1325 1326 The proof does not depend on how hard and complex a 1327 deadlock scenario would be to trigger: how many 1328 participant CPUs, tasks and irq-contexts would be needed 1329 for it to trigger. The proof also does not depend on 1330 timing: if a race and a resulting deadlock is possible 1331 theoretically (no matter how unlikely the race scenario 1332 is), it will be proven so and will immediately be 1333 reported by the kernel (once the event is observed that 1334 makes the deadlock theoretically possible). 1335 1336 If a deadlock is impossible (i.e. the locking rules, as 1337 observed by the kernel, are mathematically correct), the 1338 kernel reports nothing. 1339 1340 NOTE: this feature can also be enabled for rwlocks, mutexes 1341 and rwsems - in which case all dependencies between these 1342 different locking variants are observed and mapped too, and 1343 the proof of observed correctness is also maintained for an 1344 arbitrary combination of these separate locking variants. 1345 1346 For more details, see Documentation/locking/lockdep-design.rst. 1347 1348config PROVE_RAW_LOCK_NESTING 1349 bool "Enable raw_spinlock - spinlock nesting checks" 1350 depends on PROVE_LOCKING 1351 default n 1352 help 1353 Enable the raw_spinlock vs. spinlock nesting checks which ensure 1354 that the lock nesting rules for PREEMPT_RT enabled kernels are 1355 not violated. 1356 1357 NOTE: There are known nesting problems. So if you enable this 1358 option expect lockdep splats until these problems have been fully 1359 addressed which is work in progress. This config switch allows to 1360 identify and analyze these problems. It will be removed and the 1361 check permanently enabled once the main issues have been fixed. 1362 1363 If unsure, select N. 1364 1365config LOCK_STAT 1366 bool "Lock usage statistics" 1367 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1368 select LOCKDEP 1369 select DEBUG_SPINLOCK 1370 select DEBUG_MUTEXES if !PREEMPT_RT 1371 select DEBUG_RT_MUTEXES if RT_MUTEXES 1372 select DEBUG_LOCK_ALLOC 1373 default n 1374 help 1375 This feature enables tracking lock contention points 1376 1377 For more details, see Documentation/locking/lockstat.rst 1378 1379 This also enables lock events required by "perf lock", 1380 subcommand of perf. 1381 If you want to use "perf lock", you also need to turn on 1382 CONFIG_EVENT_TRACING. 1383 1384 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1385 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1386 1387config DEBUG_RT_MUTEXES 1388 bool "RT Mutex debugging, deadlock detection" 1389 depends on DEBUG_KERNEL && RT_MUTEXES 1390 help 1391 This allows rt mutex semantics violations and rt mutex related 1392 deadlocks (lockups) to be detected and reported automatically. 1393 1394config DEBUG_SPINLOCK 1395 bool "Spinlock and rw-lock debugging: basic checks" 1396 depends on DEBUG_KERNEL 1397 select UNINLINE_SPIN_UNLOCK 1398 help 1399 Say Y here and build SMP to catch missing spinlock initialization 1400 and certain other kinds of spinlock errors commonly made. This is 1401 best used in conjunction with the NMI watchdog so that spinlock 1402 deadlocks are also debuggable. 1403 1404config DEBUG_MUTEXES 1405 bool "Mutex debugging: basic checks" 1406 depends on DEBUG_KERNEL && !PREEMPT_RT 1407 help 1408 This feature allows mutex semantics violations to be detected and 1409 reported. 1410 1411config DEBUG_WW_MUTEX_SLOWPATH 1412 bool "Wait/wound mutex debugging: Slowpath testing" 1413 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1414 select DEBUG_LOCK_ALLOC 1415 select DEBUG_SPINLOCK 1416 select DEBUG_MUTEXES if !PREEMPT_RT 1417 select DEBUG_RT_MUTEXES if PREEMPT_RT 1418 help 1419 This feature enables slowpath testing for w/w mutex users by 1420 injecting additional -EDEADLK wound/backoff cases. Together with 1421 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1422 will test all possible w/w mutex interface abuse with the 1423 exception of simply not acquiring all the required locks. 1424 Note that this feature can introduce significant overhead, so 1425 it really should not be enabled in a production or distro kernel, 1426 even a debug kernel. If you are a driver writer, enable it. If 1427 you are a distro, do not. 1428 1429config DEBUG_RWSEMS 1430 bool "RW Semaphore debugging: basic checks" 1431 depends on DEBUG_KERNEL 1432 help 1433 This debugging feature allows mismatched rw semaphore locks 1434 and unlocks to be detected and reported. 1435 1436config DEBUG_LOCK_ALLOC 1437 bool "Lock debugging: detect incorrect freeing of live locks" 1438 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1439 select DEBUG_SPINLOCK 1440 select DEBUG_MUTEXES if !PREEMPT_RT 1441 select DEBUG_RT_MUTEXES if RT_MUTEXES 1442 select LOCKDEP 1443 help 1444 This feature will check whether any held lock (spinlock, rwlock, 1445 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1446 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1447 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1448 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1449 held during task exit. 1450 1451config LOCKDEP 1452 bool 1453 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1454 select STACKTRACE 1455 select KALLSYMS 1456 select KALLSYMS_ALL 1457 1458config LOCKDEP_SMALL 1459 bool 1460 1461config LOCKDEP_BITS 1462 int "Bitsize for MAX_LOCKDEP_ENTRIES" 1463 depends on LOCKDEP && !LOCKDEP_SMALL 1464 range 10 24 1465 default 15 1466 help 1467 Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message. 1468 1469config LOCKDEP_CHAINS_BITS 1470 int "Bitsize for MAX_LOCKDEP_CHAINS" 1471 depends on LOCKDEP && !LOCKDEP_SMALL 1472 range 10 30 1473 default 16 1474 help 1475 Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message. 1476 1477config LOCKDEP_STACK_TRACE_BITS 1478 int "Bitsize for MAX_STACK_TRACE_ENTRIES" 1479 depends on LOCKDEP && !LOCKDEP_SMALL 1480 range 10 26 1481 default 19 1482 help 1483 Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message. 1484 1485config LOCKDEP_STACK_TRACE_HASH_BITS 1486 int "Bitsize for STACK_TRACE_HASH_SIZE" 1487 depends on LOCKDEP && !LOCKDEP_SMALL 1488 range 10 26 1489 default 14 1490 help 1491 Try increasing this value if you need large STACK_TRACE_HASH_SIZE. 1492 1493config LOCKDEP_CIRCULAR_QUEUE_BITS 1494 int "Bitsize for elements in circular_queue struct" 1495 depends on LOCKDEP 1496 range 10 26 1497 default 12 1498 help 1499 Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure. 1500 1501config DEBUG_LOCKDEP 1502 bool "Lock dependency engine debugging" 1503 depends on DEBUG_KERNEL && LOCKDEP 1504 select DEBUG_IRQFLAGS 1505 help 1506 If you say Y here, the lock dependency engine will do 1507 additional runtime checks to debug itself, at the price 1508 of more runtime overhead. 1509 1510config DEBUG_ATOMIC_SLEEP 1511 bool "Sleep inside atomic section checking" 1512 select PREEMPT_COUNT 1513 depends on DEBUG_KERNEL 1514 depends on !ARCH_NO_PREEMPT 1515 help 1516 If you say Y here, various routines which may sleep will become very 1517 noisy if they are called inside atomic sections: when a spinlock is 1518 held, inside an rcu read side critical section, inside preempt disabled 1519 sections, inside an interrupt, etc... 1520 1521config DEBUG_LOCKING_API_SELFTESTS 1522 bool "Locking API boot-time self-tests" 1523 depends on DEBUG_KERNEL 1524 help 1525 Say Y here if you want the kernel to run a short self-test during 1526 bootup. The self-test checks whether common types of locking bugs 1527 are detected by debugging mechanisms or not. (if you disable 1528 lock debugging then those bugs won't be detected of course.) 1529 The following locking APIs are covered: spinlocks, rwlocks, 1530 mutexes and rwsems. 1531 1532config LOCK_TORTURE_TEST 1533 tristate "torture tests for locking" 1534 depends on DEBUG_KERNEL 1535 select TORTURE_TEST 1536 help 1537 This option provides a kernel module that runs torture tests 1538 on kernel locking primitives. The kernel module may be built 1539 after the fact on the running kernel to be tested, if desired. 1540 1541 Say Y here if you want kernel locking-primitive torture tests 1542 to be built into the kernel. 1543 Say M if you want these torture tests to build as a module. 1544 Say N if you are unsure. 1545 1546config WW_MUTEX_SELFTEST 1547 tristate "Wait/wound mutex selftests" 1548 help 1549 This option provides a kernel module that runs tests on the 1550 on the struct ww_mutex locking API. 1551 1552 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1553 with this test harness. 1554 1555 Say M if you want these self tests to build as a module. 1556 Say N if you are unsure. 1557 1558config SCF_TORTURE_TEST 1559 tristate "torture tests for smp_call_function*()" 1560 depends on DEBUG_KERNEL 1561 select TORTURE_TEST 1562 help 1563 This option provides a kernel module that runs torture tests 1564 on the smp_call_function() family of primitives. The kernel 1565 module may be built after the fact on the running kernel to 1566 be tested, if desired. 1567 1568config CSD_LOCK_WAIT_DEBUG 1569 bool "Debugging for csd_lock_wait(), called from smp_call_function*()" 1570 depends on DEBUG_KERNEL 1571 depends on 64BIT 1572 default n 1573 help 1574 This option enables debug prints when CPUs are slow to respond 1575 to the smp_call_function*() IPI wrappers. These debug prints 1576 include the IPI handler function currently executing (if any) 1577 and relevant stack traces. 1578 1579config CSD_LOCK_WAIT_DEBUG_DEFAULT 1580 bool "Default csd_lock_wait() debugging on at boot time" 1581 depends on CSD_LOCK_WAIT_DEBUG 1582 depends on 64BIT 1583 default n 1584 help 1585 This option causes the csdlock_debug= kernel boot parameter to 1586 default to 1 (basic debugging) instead of 0 (no debugging). 1587 1588endmenu # lock debugging 1589 1590config TRACE_IRQFLAGS 1591 depends on TRACE_IRQFLAGS_SUPPORT 1592 bool 1593 help 1594 Enables hooks to interrupt enabling and disabling for 1595 either tracing or lock debugging. 1596 1597config TRACE_IRQFLAGS_NMI 1598 def_bool y 1599 depends on TRACE_IRQFLAGS 1600 depends on TRACE_IRQFLAGS_NMI_SUPPORT 1601 1602config NMI_CHECK_CPU 1603 bool "Debugging for CPUs failing to respond to backtrace requests" 1604 depends on DEBUG_KERNEL 1605 depends on X86 1606 default n 1607 help 1608 Enables debug prints when a CPU fails to respond to a given 1609 backtrace NMI. These prints provide some reasons why a CPU 1610 might legitimately be failing to respond, for example, if it 1611 is offline of if ignore_nmis is set. 1612 1613config DEBUG_IRQFLAGS 1614 bool "Debug IRQ flag manipulation" 1615 help 1616 Enables checks for potentially unsafe enabling or disabling of 1617 interrupts, such as calling raw_local_irq_restore() when interrupts 1618 are enabled. 1619 1620config STACKTRACE 1621 bool "Stack backtrace support" 1622 depends on STACKTRACE_SUPPORT 1623 help 1624 This option causes the kernel to create a /proc/pid/stack for 1625 every process, showing its current stack trace. 1626 It is also used by various kernel debugging features that require 1627 stack trace generation. 1628 1629config WARN_ALL_UNSEEDED_RANDOM 1630 bool "Warn for all uses of unseeded randomness" 1631 default n 1632 help 1633 Some parts of the kernel contain bugs relating to their use of 1634 cryptographically secure random numbers before it's actually possible 1635 to generate those numbers securely. This setting ensures that these 1636 flaws don't go unnoticed, by enabling a message, should this ever 1637 occur. This will allow people with obscure setups to know when things 1638 are going wrong, so that they might contact developers about fixing 1639 it. 1640 1641 Unfortunately, on some models of some architectures getting 1642 a fully seeded CRNG is extremely difficult, and so this can 1643 result in dmesg getting spammed for a surprisingly long 1644 time. This is really bad from a security perspective, and 1645 so architecture maintainers really need to do what they can 1646 to get the CRNG seeded sooner after the system is booted. 1647 However, since users cannot do anything actionable to 1648 address this, by default this option is disabled. 1649 1650 Say Y here if you want to receive warnings for all uses of 1651 unseeded randomness. This will be of use primarily for 1652 those developers interested in improving the security of 1653 Linux kernels running on their architecture (or 1654 subarchitecture). 1655 1656config DEBUG_KOBJECT 1657 bool "kobject debugging" 1658 depends on DEBUG_KERNEL 1659 help 1660 If you say Y here, some extra kobject debugging messages will be sent 1661 to the syslog. 1662 1663config DEBUG_KOBJECT_RELEASE 1664 bool "kobject release debugging" 1665 depends on DEBUG_OBJECTS_TIMERS 1666 help 1667 kobjects are reference counted objects. This means that their 1668 last reference count put is not predictable, and the kobject can 1669 live on past the point at which a driver decides to drop its 1670 initial reference to the kobject gained on allocation. An 1671 example of this would be a struct device which has just been 1672 unregistered. 1673 1674 However, some buggy drivers assume that after such an operation, 1675 the memory backing the kobject can be immediately freed. This 1676 goes completely against the principles of a refcounted object. 1677 1678 If you say Y here, the kernel will delay the release of kobjects 1679 on the last reference count to improve the visibility of this 1680 kind of kobject release bug. 1681 1682config HAVE_DEBUG_BUGVERBOSE 1683 bool 1684 1685menu "Debug kernel data structures" 1686 1687config DEBUG_LIST 1688 bool "Debug linked list manipulation" 1689 depends on DEBUG_KERNEL 1690 select LIST_HARDENED 1691 help 1692 Enable this to turn on extended checks in the linked-list walking 1693 routines. 1694 1695 This option trades better quality error reports for performance, and 1696 is more suitable for kernel debugging. If you care about performance, 1697 you should only enable CONFIG_LIST_HARDENED instead. 1698 1699 If unsure, say N. 1700 1701config DEBUG_PLIST 1702 bool "Debug priority linked list manipulation" 1703 depends on DEBUG_KERNEL 1704 help 1705 Enable this to turn on extended checks in the priority-ordered 1706 linked-list (plist) walking routines. This checks the entire 1707 list multiple times during each manipulation. 1708 1709 If unsure, say N. 1710 1711config DEBUG_SG 1712 bool "Debug SG table operations" 1713 depends on DEBUG_KERNEL 1714 help 1715 Enable this to turn on checks on scatter-gather tables. This can 1716 help find problems with drivers that do not properly initialize 1717 their sg tables. 1718 1719 If unsure, say N. 1720 1721config DEBUG_NOTIFIERS 1722 bool "Debug notifier call chains" 1723 depends on DEBUG_KERNEL 1724 help 1725 Enable this to turn on sanity checking for notifier call chains. 1726 This is most useful for kernel developers to make sure that 1727 modules properly unregister themselves from notifier chains. 1728 This is a relatively cheap check but if you care about maximum 1729 performance, say N. 1730 1731config DEBUG_MAPLE_TREE 1732 bool "Debug maple trees" 1733 depends on DEBUG_KERNEL 1734 help 1735 Enable maple tree debugging information and extra validations. 1736 1737 If unsure, say N. 1738 1739endmenu 1740 1741source "kernel/rcu/Kconfig.debug" 1742 1743config DEBUG_WQ_FORCE_RR_CPU 1744 bool "Force round-robin CPU selection for unbound work items" 1745 depends on DEBUG_KERNEL 1746 default n 1747 help 1748 Workqueue used to implicitly guarantee that work items queued 1749 without explicit CPU specified are put on the local CPU. This 1750 guarantee is no longer true and while local CPU is still 1751 preferred work items may be put on foreign CPUs. Kernel 1752 parameter "workqueue.debug_force_rr_cpu" is added to force 1753 round-robin CPU selection to flush out usages which depend on the 1754 now broken guarantee. This config option enables the debug 1755 feature by default. When enabled, memory and cache locality will 1756 be impacted. 1757 1758config CPU_HOTPLUG_STATE_CONTROL 1759 bool "Enable CPU hotplug state control" 1760 depends on DEBUG_KERNEL 1761 depends on HOTPLUG_CPU 1762 default n 1763 help 1764 Allows to write steps between "offline" and "online" to the CPUs 1765 sysfs target file so states can be stepped granular. This is a debug 1766 option for now as the hotplug machinery cannot be stopped and 1767 restarted at arbitrary points yet. 1768 1769 Say N if your are unsure. 1770 1771config LATENCYTOP 1772 bool "Latency measuring infrastructure" 1773 depends on DEBUG_KERNEL 1774 depends on STACKTRACE_SUPPORT 1775 depends on PROC_FS 1776 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 1777 select KALLSYMS 1778 select KALLSYMS_ALL 1779 select STACKTRACE 1780 select SCHEDSTATS 1781 help 1782 Enable this option if you want to use the LatencyTOP tool 1783 to find out which userspace is blocking on what kernel operations. 1784 1785config DEBUG_CGROUP_REF 1786 bool "Disable inlining of cgroup css reference count functions" 1787 depends on DEBUG_KERNEL 1788 depends on CGROUPS 1789 depends on KPROBES 1790 default n 1791 help 1792 Force cgroup css reference count functions to not be inlined so 1793 that they can be kprobed for debugging. 1794 1795source "kernel/trace/Kconfig" 1796 1797config PROVIDE_OHCI1394_DMA_INIT 1798 bool "Remote debugging over FireWire early on boot" 1799 depends on PCI && X86 1800 help 1801 If you want to debug problems which hang or crash the kernel early 1802 on boot and the crashing machine has a FireWire port, you can use 1803 this feature to remotely access the memory of the crashed machine 1804 over FireWire. This employs remote DMA as part of the OHCI1394 1805 specification which is now the standard for FireWire controllers. 1806 1807 With remote DMA, you can monitor the printk buffer remotely using 1808 firescope and access all memory below 4GB using fireproxy from gdb. 1809 Even controlling a kernel debugger is possible using remote DMA. 1810 1811 Usage: 1812 1813 If ohci1394_dma=early is used as boot parameter, it will initialize 1814 all OHCI1394 controllers which are found in the PCI config space. 1815 1816 As all changes to the FireWire bus such as enabling and disabling 1817 devices cause a bus reset and thereby disable remote DMA for all 1818 devices, be sure to have the cable plugged and FireWire enabled on 1819 the debugging host before booting the debug target for debugging. 1820 1821 This code (~1k) is freed after boot. By then, the firewire stack 1822 in charge of the OHCI-1394 controllers should be used instead. 1823 1824 See Documentation/core-api/debugging-via-ohci1394.rst for more information. 1825 1826source "samples/Kconfig" 1827 1828config ARCH_HAS_DEVMEM_IS_ALLOWED 1829 bool 1830 1831config STRICT_DEVMEM 1832 bool "Filter access to /dev/mem" 1833 depends on MMU && DEVMEM 1834 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED 1835 default y if PPC || X86 || ARM64 1836 help 1837 If this option is disabled, you allow userspace (root) access to all 1838 of memory, including kernel and userspace memory. Accidental 1839 access to this is obviously disastrous, but specific access can 1840 be used by people debugging the kernel. Note that with PAT support 1841 enabled, even in this case there are restrictions on /dev/mem 1842 use due to the cache aliasing requirements. 1843 1844 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 1845 file only allows userspace access to PCI space and the BIOS code and 1846 data regions. This is sufficient for dosemu and X and all common 1847 users of /dev/mem. 1848 1849 If in doubt, say Y. 1850 1851config IO_STRICT_DEVMEM 1852 bool "Filter I/O access to /dev/mem" 1853 depends on STRICT_DEVMEM 1854 help 1855 If this option is disabled, you allow userspace (root) access to all 1856 io-memory regardless of whether a driver is actively using that 1857 range. Accidental access to this is obviously disastrous, but 1858 specific access can be used by people debugging kernel drivers. 1859 1860 If this option is switched on, the /dev/mem file only allows 1861 userspace access to *idle* io-memory ranges (see /proc/iomem) This 1862 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 1863 if the driver using a given range cannot be disabled. 1864 1865 If in doubt, say Y. 1866 1867menu "$(SRCARCH) Debugging" 1868 1869source "arch/$(SRCARCH)/Kconfig.debug" 1870 1871endmenu 1872 1873menu "Kernel Testing and Coverage" 1874 1875source "lib/kunit/Kconfig" 1876 1877config NOTIFIER_ERROR_INJECTION 1878 tristate "Notifier error injection" 1879 depends on DEBUG_KERNEL 1880 select DEBUG_FS 1881 help 1882 This option provides the ability to inject artificial errors to 1883 specified notifier chain callbacks. It is useful to test the error 1884 handling of notifier call chain failures. 1885 1886 Say N if unsure. 1887 1888config PM_NOTIFIER_ERROR_INJECT 1889 tristate "PM notifier error injection module" 1890 depends on PM && NOTIFIER_ERROR_INJECTION 1891 default m if PM_DEBUG 1892 help 1893 This option provides the ability to inject artificial errors to 1894 PM notifier chain callbacks. It is controlled through debugfs 1895 interface /sys/kernel/debug/notifier-error-inject/pm 1896 1897 If the notifier call chain should be failed with some events 1898 notified, write the error code to "actions/<notifier event>/error". 1899 1900 Example: Inject PM suspend error (-12 = -ENOMEM) 1901 1902 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1903 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1904 # echo mem > /sys/power/state 1905 bash: echo: write error: Cannot allocate memory 1906 1907 To compile this code as a module, choose M here: the module will 1908 be called pm-notifier-error-inject. 1909 1910 If unsure, say N. 1911 1912config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1913 tristate "OF reconfig notifier error injection module" 1914 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1915 help 1916 This option provides the ability to inject artificial errors to 1917 OF reconfig notifier chain callbacks. It is controlled 1918 through debugfs interface under 1919 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1920 1921 If the notifier call chain should be failed with some events 1922 notified, write the error code to "actions/<notifier event>/error". 1923 1924 To compile this code as a module, choose M here: the module will 1925 be called of-reconfig-notifier-error-inject. 1926 1927 If unsure, say N. 1928 1929config NETDEV_NOTIFIER_ERROR_INJECT 1930 tristate "Netdev notifier error injection module" 1931 depends on NET && NOTIFIER_ERROR_INJECTION 1932 help 1933 This option provides the ability to inject artificial errors to 1934 netdevice notifier chain callbacks. It is controlled through debugfs 1935 interface /sys/kernel/debug/notifier-error-inject/netdev 1936 1937 If the notifier call chain should be failed with some events 1938 notified, write the error code to "actions/<notifier event>/error". 1939 1940 Example: Inject netdevice mtu change error (-22 = -EINVAL) 1941 1942 # cd /sys/kernel/debug/notifier-error-inject/netdev 1943 # echo -22 > actions/NETDEV_CHANGEMTU/error 1944 # ip link set eth0 mtu 1024 1945 RTNETLINK answers: Invalid argument 1946 1947 To compile this code as a module, choose M here: the module will 1948 be called netdev-notifier-error-inject. 1949 1950 If unsure, say N. 1951 1952config FUNCTION_ERROR_INJECTION 1953 bool "Fault-injections of functions" 1954 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 1955 help 1956 Add fault injections into various functions that are annotated with 1957 ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return 1958 value of these functions. This is useful to test error paths of code. 1959 1960 If unsure, say N 1961 1962config FAULT_INJECTION 1963 bool "Fault-injection framework" 1964 depends on DEBUG_KERNEL 1965 help 1966 Provide fault-injection framework. 1967 For more details, see Documentation/fault-injection/. 1968 1969config FAILSLAB 1970 bool "Fault-injection capability for kmalloc" 1971 depends on FAULT_INJECTION 1972 depends on SLAB || SLUB 1973 help 1974 Provide fault-injection capability for kmalloc. 1975 1976config FAIL_PAGE_ALLOC 1977 bool "Fault-injection capability for alloc_pages()" 1978 depends on FAULT_INJECTION 1979 help 1980 Provide fault-injection capability for alloc_pages(). 1981 1982config FAULT_INJECTION_USERCOPY 1983 bool "Fault injection capability for usercopy functions" 1984 depends on FAULT_INJECTION 1985 help 1986 Provides fault-injection capability to inject failures 1987 in usercopy functions (copy_from_user(), get_user(), ...). 1988 1989config FAIL_MAKE_REQUEST 1990 bool "Fault-injection capability for disk IO" 1991 depends on FAULT_INJECTION && BLOCK 1992 help 1993 Provide fault-injection capability for disk IO. 1994 1995config FAIL_IO_TIMEOUT 1996 bool "Fault-injection capability for faking disk interrupts" 1997 depends on FAULT_INJECTION && BLOCK 1998 help 1999 Provide fault-injection capability on end IO handling. This 2000 will make the block layer "forget" an interrupt as configured, 2001 thus exercising the error handling. 2002 2003 Only works with drivers that use the generic timeout handling, 2004 for others it won't do anything. 2005 2006config FAIL_FUTEX 2007 bool "Fault-injection capability for futexes" 2008 select DEBUG_FS 2009 depends on FAULT_INJECTION && FUTEX 2010 help 2011 Provide fault-injection capability for futexes. 2012 2013config FAULT_INJECTION_DEBUG_FS 2014 bool "Debugfs entries for fault-injection capabilities" 2015 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 2016 help 2017 Enable configuration of fault-injection capabilities via debugfs. 2018 2019config FAIL_FUNCTION 2020 bool "Fault-injection capability for functions" 2021 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 2022 help 2023 Provide function-based fault-injection capability. 2024 This will allow you to override a specific function with a return 2025 with given return value. As a result, function caller will see 2026 an error value and have to handle it. This is useful to test the 2027 error handling in various subsystems. 2028 2029config FAIL_MMC_REQUEST 2030 bool "Fault-injection capability for MMC IO" 2031 depends on FAULT_INJECTION_DEBUG_FS && MMC 2032 help 2033 Provide fault-injection capability for MMC IO. 2034 This will make the mmc core return data errors. This is 2035 useful to test the error handling in the mmc block device 2036 and to test how the mmc host driver handles retries from 2037 the block device. 2038 2039config FAIL_SUNRPC 2040 bool "Fault-injection capability for SunRPC" 2041 depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG 2042 help 2043 Provide fault-injection capability for SunRPC and 2044 its consumers. 2045 2046config FAULT_INJECTION_CONFIGFS 2047 bool "Configfs interface for fault-injection capabilities" 2048 depends on FAULT_INJECTION 2049 select CONFIGFS_FS 2050 help 2051 This option allows configfs-based drivers to dynamically configure 2052 fault-injection via configfs. Each parameter for driver-specific 2053 fault-injection can be made visible as a configfs attribute in a 2054 configfs group. 2055 2056 2057config FAULT_INJECTION_STACKTRACE_FILTER 2058 bool "stacktrace filter for fault-injection capabilities" 2059 depends on FAULT_INJECTION 2060 depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT 2061 select STACKTRACE 2062 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 2063 help 2064 Provide stacktrace filter for fault-injection capabilities 2065 2066config ARCH_HAS_KCOV 2067 bool 2068 help 2069 An architecture should select this when it can successfully 2070 build and run with CONFIG_KCOV. This typically requires 2071 disabling instrumentation for some early boot code. 2072 2073config CC_HAS_SANCOV_TRACE_PC 2074 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 2075 2076 2077config KCOV 2078 bool "Code coverage for fuzzing" 2079 depends on ARCH_HAS_KCOV 2080 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 2081 depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \ 2082 GCC_VERSION >= 120000 || CLANG_VERSION >= 130000 2083 select DEBUG_FS 2084 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 2085 select OBJTOOL if HAVE_NOINSTR_HACK 2086 help 2087 KCOV exposes kernel code coverage information in a form suitable 2088 for coverage-guided fuzzing (randomized testing). 2089 2090 If RANDOMIZE_BASE is enabled, PC values will not be stable across 2091 different machines and across reboots. If you need stable PC values, 2092 disable RANDOMIZE_BASE. 2093 2094 For more details, see Documentation/dev-tools/kcov.rst. 2095 2096config KCOV_ENABLE_COMPARISONS 2097 bool "Enable comparison operands collection by KCOV" 2098 depends on KCOV 2099 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 2100 help 2101 KCOV also exposes operands of every comparison in the instrumented 2102 code along with operand sizes and PCs of the comparison instructions. 2103 These operands can be used by fuzzing engines to improve the quality 2104 of fuzzing coverage. 2105 2106config KCOV_INSTRUMENT_ALL 2107 bool "Instrument all code by default" 2108 depends on KCOV 2109 default y 2110 help 2111 If you are doing generic system call fuzzing (like e.g. syzkaller), 2112 then you will want to instrument the whole kernel and you should 2113 say y here. If you are doing more targeted fuzzing (like e.g. 2114 filesystem fuzzing with AFL) then you will want to enable coverage 2115 for more specific subsets of files, and should say n here. 2116 2117config KCOV_IRQ_AREA_SIZE 2118 hex "Size of interrupt coverage collection area in words" 2119 depends on KCOV 2120 default 0x40000 2121 help 2122 KCOV uses preallocated per-cpu areas to collect coverage from 2123 soft interrupts. This specifies the size of those areas in the 2124 number of unsigned long words. 2125 2126menuconfig RUNTIME_TESTING_MENU 2127 bool "Runtime Testing" 2128 def_bool y 2129 2130if RUNTIME_TESTING_MENU 2131 2132config TEST_DHRY 2133 tristate "Dhrystone benchmark test" 2134 help 2135 Enable this to include the Dhrystone 2.1 benchmark. This test 2136 calculates the number of Dhrystones per second, and the number of 2137 DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided 2138 by 1757 (the number of Dhrystones per second obtained on the VAX 2139 11/780, nominally a 1 MIPS machine). 2140 2141 To run the benchmark, it needs to be enabled explicitly, either from 2142 the kernel command line (when built-in), or from userspace (when 2143 built-in or modular. 2144 2145 Run once during kernel boot: 2146 2147 test_dhry.run 2148 2149 Set number of iterations from kernel command line: 2150 2151 test_dhry.iterations=<n> 2152 2153 Set number of iterations from userspace: 2154 2155 echo <n> > /sys/module/test_dhry/parameters/iterations 2156 2157 Trigger manual run from userspace: 2158 2159 echo y > /sys/module/test_dhry/parameters/run 2160 2161 If the number of iterations is <= 0, the test will devise a suitable 2162 number of iterations (test runs for at least 2s) automatically. 2163 This process takes ca. 4s. 2164 2165 If unsure, say N. 2166 2167config LKDTM 2168 tristate "Linux Kernel Dump Test Tool Module" 2169 depends on DEBUG_FS 2170 help 2171 This module enables testing of the different dumping mechanisms by 2172 inducing system failures at predefined crash points. 2173 If you don't need it: say N 2174 Choose M here to compile this code as a module. The module will be 2175 called lkdtm. 2176 2177 Documentation on how to use the module can be found in 2178 Documentation/fault-injection/provoke-crashes.rst 2179 2180config CPUMASK_KUNIT_TEST 2181 tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS 2182 depends on KUNIT 2183 default KUNIT_ALL_TESTS 2184 help 2185 Enable to turn on cpumask tests, running at boot or module load time. 2186 2187 For more information on KUnit and unit tests in general, please refer 2188 to the KUnit documentation in Documentation/dev-tools/kunit/. 2189 2190 If unsure, say N. 2191 2192config TEST_LIST_SORT 2193 tristate "Linked list sorting test" if !KUNIT_ALL_TESTS 2194 depends on KUNIT 2195 default KUNIT_ALL_TESTS 2196 help 2197 Enable this to turn on 'list_sort()' function test. This test is 2198 executed only once during system boot (so affects only boot time), 2199 or at module load time. 2200 2201 If unsure, say N. 2202 2203config TEST_MIN_HEAP 2204 tristate "Min heap test" 2205 depends on DEBUG_KERNEL || m 2206 help 2207 Enable this to turn on min heap function tests. This test is 2208 executed only once during system boot (so affects only boot time), 2209 or at module load time. 2210 2211 If unsure, say N. 2212 2213config TEST_SORT 2214 tristate "Array-based sort test" if !KUNIT_ALL_TESTS 2215 depends on KUNIT 2216 default KUNIT_ALL_TESTS 2217 help 2218 This option enables the self-test function of 'sort()' at boot, 2219 or at module load time. 2220 2221 If unsure, say N. 2222 2223config TEST_DIV64 2224 tristate "64bit/32bit division and modulo test" 2225 depends on DEBUG_KERNEL || m 2226 help 2227 Enable this to turn on 'do_div()' function test. This test is 2228 executed only once during system boot (so affects only boot time), 2229 or at module load time. 2230 2231 If unsure, say N. 2232 2233config TEST_IOV_ITER 2234 tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS 2235 depends on KUNIT 2236 depends on MMU 2237 default KUNIT_ALL_TESTS 2238 help 2239 Enable this to turn on testing of the operation of the I/O iterator 2240 (iov_iter). This test is executed only once during system boot (so 2241 affects only boot time), or at module load time. 2242 2243 If unsure, say N. 2244 2245config KPROBES_SANITY_TEST 2246 tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS 2247 depends on DEBUG_KERNEL 2248 depends on KPROBES 2249 depends on KUNIT 2250 select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 2251 default KUNIT_ALL_TESTS 2252 help 2253 This option provides for testing basic kprobes functionality on 2254 boot. Samples of kprobe and kretprobe are inserted and 2255 verified for functionality. 2256 2257 Say N if you are unsure. 2258 2259config FPROBE_SANITY_TEST 2260 bool "Self test for fprobe" 2261 depends on DEBUG_KERNEL 2262 depends on FPROBE 2263 depends on KUNIT=y 2264 help 2265 This option will enable testing the fprobe when the system boot. 2266 A series of tests are made to verify that the fprobe is functioning 2267 properly. 2268 2269 Say N if you are unsure. 2270 2271config BACKTRACE_SELF_TEST 2272 tristate "Self test for the backtrace code" 2273 depends on DEBUG_KERNEL 2274 help 2275 This option provides a kernel module that can be used to test 2276 the kernel stack backtrace code. This option is not useful 2277 for distributions or general kernels, but only for kernel 2278 developers working on architecture code. 2279 2280 Note that if you want to also test saved backtraces, you will 2281 have to enable STACKTRACE as well. 2282 2283 Say N if you are unsure. 2284 2285config TEST_REF_TRACKER 2286 tristate "Self test for reference tracker" 2287 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT 2288 select REF_TRACKER 2289 help 2290 This option provides a kernel module performing tests 2291 using reference tracker infrastructure. 2292 2293 Say N if you are unsure. 2294 2295config RBTREE_TEST 2296 tristate "Red-Black tree test" 2297 depends on DEBUG_KERNEL 2298 help 2299 A benchmark measuring the performance of the rbtree library. 2300 Also includes rbtree invariant checks. 2301 2302config REED_SOLOMON_TEST 2303 tristate "Reed-Solomon library test" 2304 depends on DEBUG_KERNEL || m 2305 select REED_SOLOMON 2306 select REED_SOLOMON_ENC16 2307 select REED_SOLOMON_DEC16 2308 help 2309 This option enables the self-test function of rslib at boot, 2310 or at module load time. 2311 2312 If unsure, say N. 2313 2314config INTERVAL_TREE_TEST 2315 tristate "Interval tree test" 2316 depends on DEBUG_KERNEL 2317 select INTERVAL_TREE 2318 help 2319 A benchmark measuring the performance of the interval tree library 2320 2321config PERCPU_TEST 2322 tristate "Per cpu operations test" 2323 depends on m && DEBUG_KERNEL 2324 help 2325 Enable this option to build test module which validates per-cpu 2326 operations. 2327 2328 If unsure, say N. 2329 2330config ATOMIC64_SELFTEST 2331 tristate "Perform an atomic64_t self-test" 2332 help 2333 Enable this option to test the atomic64_t functions at boot or 2334 at module load time. 2335 2336 If unsure, say N. 2337 2338config ASYNC_RAID6_TEST 2339 tristate "Self test for hardware accelerated raid6 recovery" 2340 depends on ASYNC_RAID6_RECOV 2341 select ASYNC_MEMCPY 2342 help 2343 This is a one-shot self test that permutes through the 2344 recovery of all the possible two disk failure scenarios for a 2345 N-disk array. Recovery is performed with the asynchronous 2346 raid6 recovery routines, and will optionally use an offload 2347 engine if one is available. 2348 2349 If unsure, say N. 2350 2351config TEST_HEXDUMP 2352 tristate "Test functions located in the hexdump module at runtime" 2353 2354config STRING_SELFTEST 2355 tristate "Test string functions at runtime" 2356 2357config TEST_STRING_HELPERS 2358 tristate "Test functions located in the string_helpers module at runtime" 2359 2360config TEST_KSTRTOX 2361 tristate "Test kstrto*() family of functions at runtime" 2362 2363config TEST_PRINTF 2364 tristate "Test printf() family of functions at runtime" 2365 2366config TEST_SCANF 2367 tristate "Test scanf() family of functions at runtime" 2368 2369config TEST_BITMAP 2370 tristate "Test bitmap_*() family of functions at runtime" 2371 help 2372 Enable this option to test the bitmap functions at boot. 2373 2374 If unsure, say N. 2375 2376config TEST_UUID 2377 tristate "Test functions located in the uuid module at runtime" 2378 2379config TEST_XARRAY 2380 tristate "Test the XArray code at runtime" 2381 2382config TEST_MAPLE_TREE 2383 tristate "Test the Maple Tree code at runtime or module load" 2384 help 2385 Enable this option to test the maple tree code functions at boot, or 2386 when the module is loaded. Enable "Debug Maple Trees" will enable 2387 more verbose output on failures. 2388 2389 If unsure, say N. 2390 2391config TEST_RHASHTABLE 2392 tristate "Perform selftest on resizable hash table" 2393 help 2394 Enable this option to test the rhashtable functions at boot. 2395 2396 If unsure, say N. 2397 2398config TEST_IDA 2399 tristate "Perform selftest on IDA functions" 2400 2401config TEST_PARMAN 2402 tristate "Perform selftest on priority array manager" 2403 depends on PARMAN 2404 help 2405 Enable this option to test priority array manager on boot 2406 (or module load). 2407 2408 If unsure, say N. 2409 2410config TEST_IRQ_TIMINGS 2411 bool "IRQ timings selftest" 2412 depends on IRQ_TIMINGS 2413 help 2414 Enable this option to test the irq timings code on boot. 2415 2416 If unsure, say N. 2417 2418config TEST_LKM 2419 tristate "Test module loading with 'hello world' module" 2420 depends on m 2421 help 2422 This builds the "test_module" module that emits "Hello, world" 2423 on printk when loaded. It is designed to be used for basic 2424 evaluation of the module loading subsystem (for example when 2425 validating module verification). It lacks any extra dependencies, 2426 and will not normally be loaded by the system unless explicitly 2427 requested by name. 2428 2429 If unsure, say N. 2430 2431config TEST_BITOPS 2432 tristate "Test module for compilation of bitops operations" 2433 depends on m 2434 help 2435 This builds the "test_bitops" module that is much like the 2436 TEST_LKM module except that it does a basic exercise of the 2437 set/clear_bit macros and get_count_order/long to make sure there are 2438 no compiler warnings from C=1 sparse checker or -Wextra 2439 compilations. It has no dependencies and doesn't run or load unless 2440 explicitly requested by name. for example: modprobe test_bitops. 2441 2442 If unsure, say N. 2443 2444config TEST_VMALLOC 2445 tristate "Test module for stress/performance analysis of vmalloc allocator" 2446 default n 2447 depends on MMU 2448 depends on m 2449 help 2450 This builds the "test_vmalloc" module that should be used for 2451 stress and performance analysis. So, any new change for vmalloc 2452 subsystem can be evaluated from performance and stability point 2453 of view. 2454 2455 If unsure, say N. 2456 2457config TEST_USER_COPY 2458 tristate "Test user/kernel boundary protections" 2459 depends on m 2460 help 2461 This builds the "test_user_copy" module that runs sanity checks 2462 on the copy_to/from_user infrastructure, making sure basic 2463 user/kernel boundary testing is working. If it fails to load, 2464 a regression has been detected in the user/kernel memory boundary 2465 protections. 2466 2467 If unsure, say N. 2468 2469config TEST_BPF 2470 tristate "Test BPF filter functionality" 2471 depends on m && NET 2472 help 2473 This builds the "test_bpf" module that runs various test vectors 2474 against the BPF interpreter or BPF JIT compiler depending on the 2475 current setting. This is in particular useful for BPF JIT compiler 2476 development, but also to run regression tests against changes in 2477 the interpreter code. It also enables test stubs for eBPF maps and 2478 verifier used by user space verifier testsuite. 2479 2480 If unsure, say N. 2481 2482config TEST_BLACKHOLE_DEV 2483 tristate "Test blackhole netdev functionality" 2484 depends on m && NET 2485 help 2486 This builds the "test_blackhole_dev" module that validates the 2487 data path through this blackhole netdev. 2488 2489 If unsure, say N. 2490 2491config FIND_BIT_BENCHMARK 2492 tristate "Test find_bit functions" 2493 help 2494 This builds the "test_find_bit" module that measure find_*_bit() 2495 functions performance. 2496 2497 If unsure, say N. 2498 2499config TEST_FIRMWARE 2500 tristate "Test firmware loading via userspace interface" 2501 depends on FW_LOADER 2502 help 2503 This builds the "test_firmware" module that creates a userspace 2504 interface for testing firmware loading. This can be used to 2505 control the triggering of firmware loading without needing an 2506 actual firmware-using device. The contents can be rechecked by 2507 userspace. 2508 2509 If unsure, say N. 2510 2511config TEST_SYSCTL 2512 tristate "sysctl test driver" 2513 depends on PROC_SYSCTL 2514 help 2515 This builds the "test_sysctl" module. This driver enables to test the 2516 proc sysctl interfaces available to drivers safely without affecting 2517 production knobs which might alter system functionality. 2518 2519 If unsure, say N. 2520 2521config BITFIELD_KUNIT 2522 tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS 2523 depends on KUNIT 2524 default KUNIT_ALL_TESTS 2525 help 2526 Enable this option to test the bitfield functions at boot. 2527 2528 KUnit tests run during boot and output the results to the debug log 2529 in TAP format (http://testanything.org/). Only useful for kernel devs 2530 running the KUnit test harness, and not intended for inclusion into a 2531 production build. 2532 2533 For more information on KUnit and unit tests in general please refer 2534 to the KUnit documentation in Documentation/dev-tools/kunit/. 2535 2536 If unsure, say N. 2537 2538config CHECKSUM_KUNIT 2539 tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS 2540 depends on KUNIT 2541 default KUNIT_ALL_TESTS 2542 help 2543 Enable this option to test the checksum functions at boot. 2544 2545 KUnit tests run during boot and output the results to the debug log 2546 in TAP format (http://testanything.org/). Only useful for kernel devs 2547 running the KUnit test harness, and not intended for inclusion into a 2548 production build. 2549 2550 For more information on KUnit and unit tests in general please refer 2551 to the KUnit documentation in Documentation/dev-tools/kunit/. 2552 2553 If unsure, say N. 2554 2555config HASH_KUNIT_TEST 2556 tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS 2557 depends on KUNIT 2558 default KUNIT_ALL_TESTS 2559 help 2560 Enable this option to test the kernel's string (<linux/stringhash.h>), and 2561 integer (<linux/hash.h>) hash functions on boot. 2562 2563 KUnit tests run during boot and output the results to the debug log 2564 in TAP format (https://testanything.org/). Only useful for kernel devs 2565 running the KUnit test harness, and not intended for inclusion into a 2566 production build. 2567 2568 For more information on KUnit and unit tests in general please refer 2569 to the KUnit documentation in Documentation/dev-tools/kunit/. 2570 2571 This is intended to help people writing architecture-specific 2572 optimized versions. If unsure, say N. 2573 2574config RESOURCE_KUNIT_TEST 2575 tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS 2576 depends on KUNIT 2577 default KUNIT_ALL_TESTS 2578 help 2579 This builds the resource API unit test. 2580 Tests the logic of API provided by resource.c and ioport.h. 2581 For more information on KUnit and unit tests in general please refer 2582 to the KUnit documentation in Documentation/dev-tools/kunit/. 2583 2584 If unsure, say N. 2585 2586config SYSCTL_KUNIT_TEST 2587 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS 2588 depends on KUNIT 2589 default KUNIT_ALL_TESTS 2590 help 2591 This builds the proc sysctl unit test, which runs on boot. 2592 Tests the API contract and implementation correctness of sysctl. 2593 For more information on KUnit and unit tests in general please refer 2594 to the KUnit documentation in Documentation/dev-tools/kunit/. 2595 2596 If unsure, say N. 2597 2598config LIST_KUNIT_TEST 2599 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS 2600 depends on KUNIT 2601 default KUNIT_ALL_TESTS 2602 help 2603 This builds the linked list KUnit test suite. 2604 It tests that the API and basic functionality of the list_head type 2605 and associated macros. 2606 2607 KUnit tests run during boot and output the results to the debug log 2608 in TAP format (https://testanything.org/). Only useful for kernel devs 2609 running the KUnit test harness, and not intended for inclusion into a 2610 production build. 2611 2612 For more information on KUnit and unit tests in general please refer 2613 to the KUnit documentation in Documentation/dev-tools/kunit/. 2614 2615 If unsure, say N. 2616 2617config HASHTABLE_KUNIT_TEST 2618 tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS 2619 depends on KUNIT 2620 default KUNIT_ALL_TESTS 2621 help 2622 This builds the hashtable KUnit test suite. 2623 It tests the basic functionality of the API defined in 2624 include/linux/hashtable.h. For more information on KUnit and 2625 unit tests in general please refer to the KUnit documentation 2626 in Documentation/dev-tools/kunit/. 2627 2628 If unsure, say N. 2629 2630config LINEAR_RANGES_TEST 2631 tristate "KUnit test for linear_ranges" 2632 depends on KUNIT 2633 select LINEAR_RANGES 2634 help 2635 This builds the linear_ranges unit test, which runs on boot. 2636 Tests the linear_ranges logic correctness. 2637 For more information on KUnit and unit tests in general please refer 2638 to the KUnit documentation in Documentation/dev-tools/kunit/. 2639 2640 If unsure, say N. 2641 2642config CMDLINE_KUNIT_TEST 2643 tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS 2644 depends on KUNIT 2645 default KUNIT_ALL_TESTS 2646 help 2647 This builds the cmdline API unit test. 2648 Tests the logic of API provided by cmdline.c. 2649 For more information on KUnit and unit tests in general please refer 2650 to the KUnit documentation in Documentation/dev-tools/kunit/. 2651 2652 If unsure, say N. 2653 2654config BITS_TEST 2655 tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS 2656 depends on KUNIT 2657 default KUNIT_ALL_TESTS 2658 help 2659 This builds the bits unit test. 2660 Tests the logic of macros defined in bits.h. 2661 For more information on KUnit and unit tests in general please refer 2662 to the KUnit documentation in Documentation/dev-tools/kunit/. 2663 2664 If unsure, say N. 2665 2666config SLUB_KUNIT_TEST 2667 tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS 2668 depends on SLUB_DEBUG && KUNIT 2669 default KUNIT_ALL_TESTS 2670 help 2671 This builds SLUB allocator unit test. 2672 Tests SLUB cache debugging functionality. 2673 For more information on KUnit and unit tests in general please refer 2674 to the KUnit documentation in Documentation/dev-tools/kunit/. 2675 2676 If unsure, say N. 2677 2678config RATIONAL_KUNIT_TEST 2679 tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS 2680 depends on KUNIT && RATIONAL 2681 default KUNIT_ALL_TESTS 2682 help 2683 This builds the rational math unit test. 2684 For more information on KUnit and unit tests in general please refer 2685 to the KUnit documentation in Documentation/dev-tools/kunit/. 2686 2687 If unsure, say N. 2688 2689config MEMCPY_KUNIT_TEST 2690 tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS 2691 depends on KUNIT 2692 default KUNIT_ALL_TESTS 2693 help 2694 Builds unit tests for memcpy(), memmove(), and memset() functions. 2695 For more information on KUnit and unit tests in general please refer 2696 to the KUnit documentation in Documentation/dev-tools/kunit/. 2697 2698 If unsure, say N. 2699 2700config MEMCPY_SLOW_KUNIT_TEST 2701 bool "Include exhaustive memcpy tests" 2702 depends on MEMCPY_KUNIT_TEST 2703 default y 2704 help 2705 Some memcpy tests are quite exhaustive in checking for overlaps 2706 and bit ranges. These can be very slow, so they are split out 2707 as a separate config, in case they need to be disabled. 2708 2709 Note this config option will be replaced by the use of KUnit test 2710 attributes. 2711 2712config IS_SIGNED_TYPE_KUNIT_TEST 2713 tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS 2714 depends on KUNIT 2715 default KUNIT_ALL_TESTS 2716 help 2717 Builds unit tests for the is_signed_type() macro. 2718 2719 For more information on KUnit and unit tests in general please refer 2720 to the KUnit documentation in Documentation/dev-tools/kunit/. 2721 2722 If unsure, say N. 2723 2724config OVERFLOW_KUNIT_TEST 2725 tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS 2726 depends on KUNIT 2727 default KUNIT_ALL_TESTS 2728 help 2729 Builds unit tests for the check_*_overflow(), size_*(), allocation, and 2730 related functions. 2731 2732 For more information on KUnit and unit tests in general please refer 2733 to the KUnit documentation in Documentation/dev-tools/kunit/. 2734 2735 If unsure, say N. 2736 2737config STACKINIT_KUNIT_TEST 2738 tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS 2739 depends on KUNIT 2740 default KUNIT_ALL_TESTS 2741 help 2742 Test if the kernel is zero-initializing stack variables and 2743 padding. Coverage is controlled by compiler flags, 2744 CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO, 2745 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2746 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2747 2748config FORTIFY_KUNIT_TEST 2749 tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS 2750 depends on KUNIT && FORTIFY_SOURCE 2751 default KUNIT_ALL_TESTS 2752 help 2753 Builds unit tests for checking internals of FORTIFY_SOURCE as used 2754 by the str*() and mem*() family of functions. For testing runtime 2755 traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests. 2756 2757config HW_BREAKPOINT_KUNIT_TEST 2758 bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS 2759 depends on HAVE_HW_BREAKPOINT 2760 depends on KUNIT=y 2761 default KUNIT_ALL_TESTS 2762 help 2763 Tests for hw_breakpoint constraints accounting. 2764 2765 If unsure, say N. 2766 2767config STRCAT_KUNIT_TEST 2768 tristate "Test strcat() family of functions at runtime" if !KUNIT_ALL_TESTS 2769 depends on KUNIT 2770 default KUNIT_ALL_TESTS 2771 2772config STRSCPY_KUNIT_TEST 2773 tristate "Test strscpy*() family of functions at runtime" if !KUNIT_ALL_TESTS 2774 depends on KUNIT 2775 default KUNIT_ALL_TESTS 2776 2777config SIPHASH_KUNIT_TEST 2778 tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS 2779 depends on KUNIT 2780 default KUNIT_ALL_TESTS 2781 help 2782 Enable this option to test the kernel's siphash (<linux/siphash.h>) hash 2783 functions on boot (or module load). 2784 2785 This is intended to help people writing architecture-specific 2786 optimized versions. If unsure, say N. 2787 2788config TEST_UDELAY 2789 tristate "udelay test driver" 2790 help 2791 This builds the "udelay_test" module that helps to make sure 2792 that udelay() is working properly. 2793 2794 If unsure, say N. 2795 2796config TEST_STATIC_KEYS 2797 tristate "Test static keys" 2798 depends on m 2799 help 2800 Test the static key interfaces. 2801 2802 If unsure, say N. 2803 2804config TEST_DYNAMIC_DEBUG 2805 tristate "Test DYNAMIC_DEBUG" 2806 depends on DYNAMIC_DEBUG 2807 help 2808 This module registers a tracer callback to count enabled 2809 pr_debugs in a 'do_debugging' function, then alters their 2810 enablements, calls the function, and compares counts. 2811 2812 If unsure, say N. 2813 2814config TEST_KMOD 2815 tristate "kmod stress tester" 2816 depends on m 2817 depends on NETDEVICES && NET_CORE && INET # for TUN 2818 depends on BLOCK 2819 depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS 2820 select TEST_LKM 2821 select XFS_FS 2822 select TUN 2823 select BTRFS_FS 2824 help 2825 Test the kernel's module loading mechanism: kmod. kmod implements 2826 support to load modules using the Linux kernel's usermode helper. 2827 This test provides a series of tests against kmod. 2828 2829 Although technically you can either build test_kmod as a module or 2830 into the kernel we disallow building it into the kernel since 2831 it stress tests request_module() and this will very likely cause 2832 some issues by taking over precious threads available from other 2833 module load requests, ultimately this could be fatal. 2834 2835 To run tests run: 2836 2837 tools/testing/selftests/kmod/kmod.sh --help 2838 2839 If unsure, say N. 2840 2841config TEST_DEBUG_VIRTUAL 2842 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 2843 depends on DEBUG_VIRTUAL 2844 help 2845 Test the kernel's ability to detect incorrect calls to 2846 virt_to_phys() done against the non-linear part of the 2847 kernel's virtual address map. 2848 2849 If unsure, say N. 2850 2851config TEST_MEMCAT_P 2852 tristate "Test memcat_p() helper function" 2853 help 2854 Test the memcat_p() helper for correctly merging two 2855 pointer arrays together. 2856 2857 If unsure, say N. 2858 2859config TEST_LIVEPATCH 2860 tristate "Test livepatching" 2861 default n 2862 depends on DYNAMIC_DEBUG 2863 depends on LIVEPATCH 2864 depends on m 2865 help 2866 Test kernel livepatching features for correctness. The tests will 2867 load test modules that will be livepatched in various scenarios. 2868 2869 To run all the livepatching tests: 2870 2871 make -C tools/testing/selftests TARGETS=livepatch run_tests 2872 2873 Alternatively, individual tests may be invoked: 2874 2875 tools/testing/selftests/livepatch/test-callbacks.sh 2876 tools/testing/selftests/livepatch/test-livepatch.sh 2877 tools/testing/selftests/livepatch/test-shadow-vars.sh 2878 2879 If unsure, say N. 2880 2881config TEST_OBJAGG 2882 tristate "Perform selftest on object aggreration manager" 2883 default n 2884 depends on OBJAGG 2885 help 2886 Enable this option to test object aggregation manager on boot 2887 (or module load). 2888 2889config TEST_MEMINIT 2890 tristate "Test heap/page initialization" 2891 help 2892 Test if the kernel is zero-initializing heap and page allocations. 2893 This can be useful to test init_on_alloc and init_on_free features. 2894 2895 If unsure, say N. 2896 2897config TEST_HMM 2898 tristate "Test HMM (Heterogeneous Memory Management)" 2899 depends on TRANSPARENT_HUGEPAGE 2900 depends on DEVICE_PRIVATE 2901 select HMM_MIRROR 2902 select MMU_NOTIFIER 2903 help 2904 This is a pseudo device driver solely for testing HMM. 2905 Say M here if you want to build the HMM test module. 2906 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests. 2907 2908 If unsure, say N. 2909 2910config TEST_FREE_PAGES 2911 tristate "Test freeing pages" 2912 help 2913 Test that a memory leak does not occur due to a race between 2914 freeing a block of pages and a speculative page reference. 2915 Loading this module is safe if your kernel has the bug fixed. 2916 If the bug is not fixed, it will leak gigabytes of memory and 2917 probably OOM your system. 2918 2919config TEST_FPU 2920 tristate "Test floating point operations in kernel space" 2921 depends on X86 && !KCOV_INSTRUMENT_ALL 2922 help 2923 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu 2924 which will trigger a sequence of floating point operations. This is used 2925 for self-testing floating point control register setting in 2926 kernel_fpu_begin(). 2927 2928 If unsure, say N. 2929 2930config TEST_CLOCKSOURCE_WATCHDOG 2931 tristate "Test clocksource watchdog in kernel space" 2932 depends on CLOCKSOURCE_WATCHDOG 2933 help 2934 Enable this option to create a kernel module that will trigger 2935 a test of the clocksource watchdog. This module may be loaded 2936 via modprobe or insmod in which case it will run upon being 2937 loaded, or it may be built in, in which case it will run 2938 shortly after boot. 2939 2940 If unsure, say N. 2941 2942endif # RUNTIME_TESTING_MENU 2943 2944config ARCH_USE_MEMTEST 2945 bool 2946 help 2947 An architecture should select this when it uses early_memtest() 2948 during boot process. 2949 2950config MEMTEST 2951 bool "Memtest" 2952 depends on ARCH_USE_MEMTEST 2953 help 2954 This option adds a kernel parameter 'memtest', which allows memtest 2955 to be set and executed. 2956 memtest=0, mean disabled; -- default 2957 memtest=1, mean do 1 test pattern; 2958 ... 2959 memtest=17, mean do 17 test patterns. 2960 If you are unsure how to answer this question, answer N. 2961 2962 2963 2964config HYPERV_TESTING 2965 bool "Microsoft Hyper-V driver testing" 2966 default n 2967 depends on HYPERV && DEBUG_FS 2968 help 2969 Select this option to enable Hyper-V vmbus testing. 2970 2971endmenu # "Kernel Testing and Coverage" 2972 2973menu "Rust hacking" 2974 2975config RUST_DEBUG_ASSERTIONS 2976 bool "Debug assertions" 2977 depends on RUST 2978 help 2979 Enables rustc's `-Cdebug-assertions` codegen option. 2980 2981 This flag lets you turn `cfg(debug_assertions)` conditional 2982 compilation on or off. This can be used to enable extra debugging 2983 code in development but not in production. For example, it controls 2984 the behavior of the standard library's `debug_assert!` macro. 2985 2986 Note that this will apply to all Rust code, including `core`. 2987 2988 If unsure, say N. 2989 2990config RUST_OVERFLOW_CHECKS 2991 bool "Overflow checks" 2992 default y 2993 depends on RUST 2994 help 2995 Enables rustc's `-Coverflow-checks` codegen option. 2996 2997 This flag allows you to control the behavior of runtime integer 2998 overflow. When overflow-checks are enabled, a Rust panic will occur 2999 on overflow. 3000 3001 Note that this will apply to all Rust code, including `core`. 3002 3003 If unsure, say Y. 3004 3005config RUST_BUILD_ASSERT_ALLOW 3006 bool "Allow unoptimized build-time assertions" 3007 depends on RUST 3008 help 3009 Controls how `build_error!` and `build_assert!` are handled during the build. 3010 3011 If calls to them exist in the binary, it may indicate a violated invariant 3012 or that the optimizer failed to verify the invariant during compilation. 3013 3014 This should not happen, thus by default the build is aborted. However, 3015 as an escape hatch, you can choose Y here to ignore them during build 3016 and let the check be carried at runtime (with `panic!` being called if 3017 the check fails). 3018 3019 If unsure, say N. 3020 3021config RUST_KERNEL_DOCTESTS 3022 bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS 3023 depends on RUST && KUNIT=y 3024 default KUNIT_ALL_TESTS 3025 help 3026 This builds the documentation tests of the `kernel` crate 3027 as KUnit tests. 3028 3029 For more information on KUnit and unit tests in general, 3030 please refer to the KUnit documentation in Documentation/dev-tools/kunit/. 3031 3032 If unsure, say N. 3033 3034endmenu # "Rust" 3035 3036endmenu # Kernel hacking 3037