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 SOFTLOCKUP_DETECTOR_INTR_STORM 1028 bool "Detect Interrupt Storm in Soft Lockups" 1029 depends on SOFTLOCKUP_DETECTOR && IRQ_TIME_ACCOUNTING 1030 select GENERIC_IRQ_STAT_SNAPSHOT 1031 default y if NR_CPUS <= 128 1032 help 1033 Say Y here to enable the kernel to detect interrupt storm 1034 during "soft lockups". 1035 1036 "soft lockups" can be caused by a variety of reasons. If one is 1037 caused by an interrupt storm, then the storming interrupts will not 1038 be on the callstack. To detect this case, it is necessary to report 1039 the CPU stats and the interrupt counts during the "soft lockups". 1040 1041config BOOTPARAM_SOFTLOCKUP_PANIC 1042 bool "Panic (Reboot) On Soft Lockups" 1043 depends on SOFTLOCKUP_DETECTOR 1044 help 1045 Say Y here to enable the kernel to panic on "soft lockups", 1046 which are bugs that cause the kernel to loop in kernel 1047 mode for more than 20 seconds (configurable using the watchdog_thresh 1048 sysctl), without giving other tasks a chance to run. 1049 1050 The panic can be used in combination with panic_timeout, 1051 to cause the system to reboot automatically after a 1052 lockup has been detected. This feature is useful for 1053 high-availability systems that have uptime guarantees and 1054 where a lockup must be resolved ASAP. 1055 1056 Say N if unsure. 1057 1058config HAVE_HARDLOCKUP_DETECTOR_BUDDY 1059 bool 1060 depends on SMP 1061 default y 1062 1063# 1064# Global switch whether to build a hardlockup detector at all. It is available 1065# only when the architecture supports at least one implementation. There are 1066# two exceptions. The hardlockup detector is never enabled on: 1067# 1068# s390: it reported many false positives there 1069# 1070# sparc64: has a custom implementation which is not using the common 1071# hardlockup command line options and sysctl interface. 1072# 1073config HARDLOCKUP_DETECTOR 1074 bool "Detect Hard Lockups" 1075 depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64 1076 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH 1077 imply HARDLOCKUP_DETECTOR_PERF 1078 imply HARDLOCKUP_DETECTOR_BUDDY 1079 imply HARDLOCKUP_DETECTOR_ARCH 1080 select LOCKUP_DETECTOR 1081 1082 help 1083 Say Y here to enable the kernel to act as a watchdog to detect 1084 hard lockups. 1085 1086 Hardlockups are bugs that cause the CPU to loop in kernel mode 1087 for more than 10 seconds, without letting other interrupts have a 1088 chance to run. The current stack trace is displayed upon detection 1089 and the system will stay locked up. 1090 1091# 1092# Note that arch-specific variants are always preferred. 1093# 1094config HARDLOCKUP_DETECTOR_PREFER_BUDDY 1095 bool "Prefer the buddy CPU hardlockup detector" 1096 depends on HARDLOCKUP_DETECTOR 1097 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY 1098 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1099 help 1100 Say Y here to prefer the buddy hardlockup detector over the perf one. 1101 1102 With the buddy detector, each CPU uses its softlockup hrtimer 1103 to check that the next CPU is processing hrtimer interrupts by 1104 verifying that a counter is increasing. 1105 1106 This hardlockup detector is useful on systems that don't have 1107 an arch-specific hardlockup detector or if resources needed 1108 for the hardlockup detector are better used for other things. 1109 1110config HARDLOCKUP_DETECTOR_PERF 1111 bool 1112 depends on HARDLOCKUP_DETECTOR 1113 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY 1114 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1115 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1116 1117config HARDLOCKUP_DETECTOR_BUDDY 1118 bool 1119 depends on HARDLOCKUP_DETECTOR 1120 depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY 1121 depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY 1122 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1123 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1124 1125config HARDLOCKUP_DETECTOR_ARCH 1126 bool 1127 depends on HARDLOCKUP_DETECTOR 1128 depends on HAVE_HARDLOCKUP_DETECTOR_ARCH 1129 help 1130 The arch-specific implementation of the hardlockup detector will 1131 be used. 1132 1133# 1134# Both the "perf" and "buddy" hardlockup detectors count hrtimer 1135# interrupts. This config enables functions managing this common code. 1136# 1137config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1138 bool 1139 select SOFTLOCKUP_DETECTOR 1140 1141# 1142# Enables a timestamp based low pass filter to compensate for perf based 1143# hard lockup detection which runs too fast due to turbo modes. 1144# 1145config HARDLOCKUP_CHECK_TIMESTAMP 1146 bool 1147 1148config BOOTPARAM_HARDLOCKUP_PANIC 1149 bool "Panic (Reboot) On Hard Lockups" 1150 depends on HARDLOCKUP_DETECTOR 1151 help 1152 Say Y here to enable the kernel to panic on "hard lockups", 1153 which are bugs that cause the kernel to loop in kernel 1154 mode with interrupts disabled for more than 10 seconds (configurable 1155 using the watchdog_thresh sysctl). 1156 1157 Say N if unsure. 1158 1159config DETECT_HUNG_TASK 1160 bool "Detect Hung Tasks" 1161 depends on DEBUG_KERNEL 1162 default SOFTLOCKUP_DETECTOR 1163 help 1164 Say Y here to enable the kernel to detect "hung tasks", 1165 which are bugs that cause the task to be stuck in 1166 uninterruptible "D" state indefinitely. 1167 1168 When a hung task is detected, the kernel will print the 1169 current stack trace (which you should report), but the 1170 task will stay in uninterruptible state. If lockdep is 1171 enabled then all held locks will also be reported. This 1172 feature has negligible overhead. 1173 1174config DEFAULT_HUNG_TASK_TIMEOUT 1175 int "Default timeout for hung task detection (in seconds)" 1176 depends on DETECT_HUNG_TASK 1177 default 120 1178 help 1179 This option controls the default timeout (in seconds) used 1180 to determine when a task has become non-responsive and should 1181 be considered hung. 1182 1183 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 1184 sysctl or by writing a value to 1185 /proc/sys/kernel/hung_task_timeout_secs. 1186 1187 A timeout of 0 disables the check. The default is two minutes. 1188 Keeping the default should be fine in most cases. 1189 1190config BOOTPARAM_HUNG_TASK_PANIC 1191 bool "Panic (Reboot) On Hung Tasks" 1192 depends on DETECT_HUNG_TASK 1193 help 1194 Say Y here to enable the kernel to panic on "hung tasks", 1195 which are bugs that cause the kernel to leave a task stuck 1196 in uninterruptible "D" state. 1197 1198 The panic can be used in combination with panic_timeout, 1199 to cause the system to reboot automatically after a 1200 hung task has been detected. This feature is useful for 1201 high-availability systems that have uptime guarantees and 1202 where a hung tasks must be resolved ASAP. 1203 1204 Say N if unsure. 1205 1206config WQ_WATCHDOG 1207 bool "Detect Workqueue Stalls" 1208 depends on DEBUG_KERNEL 1209 help 1210 Say Y here to enable stall detection on workqueues. If a 1211 worker pool doesn't make forward progress on a pending work 1212 item for over a given amount of time, 30s by default, a 1213 warning message is printed along with dump of workqueue 1214 state. This can be configured through kernel parameter 1215 "workqueue.watchdog_thresh" and its sysfs counterpart. 1216 1217config WQ_CPU_INTENSIVE_REPORT 1218 bool "Report per-cpu work items which hog CPU for too long" 1219 depends on DEBUG_KERNEL 1220 help 1221 Say Y here to enable reporting of concurrency-managed per-cpu work 1222 items that hog CPUs for longer than 1223 workqueue.cpu_intensive_thresh_us. Workqueue automatically 1224 detects and excludes them from concurrency management to prevent 1225 them from stalling other per-cpu work items. Occassional 1226 triggering may not necessarily indicate a problem. Repeated 1227 triggering likely indicates that the work item should be switched 1228 to use an unbound workqueue. 1229 1230config TEST_LOCKUP 1231 tristate "Test module to generate lockups" 1232 depends on m 1233 help 1234 This builds the "test_lockup" module that helps to make sure 1235 that watchdogs and lockup detectors are working properly. 1236 1237 Depending on module parameters it could emulate soft or hard 1238 lockup, "hung task", or locking arbitrary lock for a long time. 1239 Also it could generate series of lockups with cooling-down periods. 1240 1241 If unsure, say N. 1242 1243endmenu # "Debug lockups and hangs" 1244 1245menu "Scheduler Debugging" 1246 1247config SCHED_DEBUG 1248 bool "Collect scheduler debugging info" 1249 depends on DEBUG_KERNEL && DEBUG_FS 1250 default y 1251 help 1252 If you say Y here, the /sys/kernel/debug/sched file will be provided 1253 that can help debug the scheduler. The runtime overhead of this 1254 option is minimal. 1255 1256config SCHED_INFO 1257 bool 1258 default n 1259 1260config SCHEDSTATS 1261 bool "Collect scheduler statistics" 1262 depends on DEBUG_KERNEL && PROC_FS 1263 select SCHED_INFO 1264 help 1265 If you say Y here, additional code will be inserted into the 1266 scheduler and related routines to collect statistics about 1267 scheduler behavior and provide them in /proc/schedstat. These 1268 stats may be useful for both tuning and debugging the scheduler 1269 If you aren't debugging the scheduler or trying to tune a specific 1270 application, you can say N to avoid the very slight overhead 1271 this adds. 1272 1273endmenu 1274 1275config DEBUG_TIMEKEEPING 1276 bool "Enable extra timekeeping sanity checking" 1277 help 1278 This option will enable additional timekeeping sanity checks 1279 which may be helpful when diagnosing issues where timekeeping 1280 problems are suspected. 1281 1282 This may include checks in the timekeeping hotpaths, so this 1283 option may have a (very small) performance impact to some 1284 workloads. 1285 1286 If unsure, say N. 1287 1288config DEBUG_PREEMPT 1289 bool "Debug preemptible kernel" 1290 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1291 help 1292 If you say Y here then the kernel will use a debug variant of the 1293 commonly used smp_processor_id() function and will print warnings 1294 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1295 will detect preemption count underflows. 1296 1297 This option has potential to introduce high runtime overhead, 1298 depending on workload as it triggers debugging routines for each 1299 this_cpu operation. It should only be used for debugging purposes. 1300 1301menu "Lock Debugging (spinlocks, mutexes, etc...)" 1302 1303config LOCK_DEBUGGING_SUPPORT 1304 bool 1305 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1306 default y 1307 1308config PROVE_LOCKING 1309 bool "Lock debugging: prove locking correctness" 1310 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1311 select LOCKDEP 1312 select DEBUG_SPINLOCK 1313 select DEBUG_MUTEXES if !PREEMPT_RT 1314 select DEBUG_RT_MUTEXES if RT_MUTEXES 1315 select DEBUG_RWSEMS 1316 select DEBUG_WW_MUTEX_SLOWPATH 1317 select DEBUG_LOCK_ALLOC 1318 select PREEMPT_COUNT if !ARCH_NO_PREEMPT 1319 select TRACE_IRQFLAGS 1320 default n 1321 help 1322 This feature enables the kernel to prove that all locking 1323 that occurs in the kernel runtime is mathematically 1324 correct: that under no circumstance could an arbitrary (and 1325 not yet triggered) combination of observed locking 1326 sequences (on an arbitrary number of CPUs, running an 1327 arbitrary number of tasks and interrupt contexts) cause a 1328 deadlock. 1329 1330 In short, this feature enables the kernel to report locking 1331 related deadlocks before they actually occur. 1332 1333 The proof does not depend on how hard and complex a 1334 deadlock scenario would be to trigger: how many 1335 participant CPUs, tasks and irq-contexts would be needed 1336 for it to trigger. The proof also does not depend on 1337 timing: if a race and a resulting deadlock is possible 1338 theoretically (no matter how unlikely the race scenario 1339 is), it will be proven so and will immediately be 1340 reported by the kernel (once the event is observed that 1341 makes the deadlock theoretically possible). 1342 1343 If a deadlock is impossible (i.e. the locking rules, as 1344 observed by the kernel, are mathematically correct), the 1345 kernel reports nothing. 1346 1347 NOTE: this feature can also be enabled for rwlocks, mutexes 1348 and rwsems - in which case all dependencies between these 1349 different locking variants are observed and mapped too, and 1350 the proof of observed correctness is also maintained for an 1351 arbitrary combination of these separate locking variants. 1352 1353 For more details, see Documentation/locking/lockdep-design.rst. 1354 1355config PROVE_RAW_LOCK_NESTING 1356 bool "Enable raw_spinlock - spinlock nesting checks" 1357 depends on PROVE_LOCKING 1358 default n 1359 help 1360 Enable the raw_spinlock vs. spinlock nesting checks which ensure 1361 that the lock nesting rules for PREEMPT_RT enabled kernels are 1362 not violated. 1363 1364 NOTE: There are known nesting problems. So if you enable this 1365 option expect lockdep splats until these problems have been fully 1366 addressed which is work in progress. This config switch allows to 1367 identify and analyze these problems. It will be removed and the 1368 check permanently enabled once the main issues have been fixed. 1369 1370 If unsure, select N. 1371 1372config LOCK_STAT 1373 bool "Lock usage statistics" 1374 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1375 select LOCKDEP 1376 select DEBUG_SPINLOCK 1377 select DEBUG_MUTEXES if !PREEMPT_RT 1378 select DEBUG_RT_MUTEXES if RT_MUTEXES 1379 select DEBUG_LOCK_ALLOC 1380 default n 1381 help 1382 This feature enables tracking lock contention points 1383 1384 For more details, see Documentation/locking/lockstat.rst 1385 1386 This also enables lock events required by "perf lock", 1387 subcommand of perf. 1388 If you want to use "perf lock", you also need to turn on 1389 CONFIG_EVENT_TRACING. 1390 1391 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1392 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1393 1394config DEBUG_RT_MUTEXES 1395 bool "RT Mutex debugging, deadlock detection" 1396 depends on DEBUG_KERNEL && RT_MUTEXES 1397 help 1398 This allows rt mutex semantics violations and rt mutex related 1399 deadlocks (lockups) to be detected and reported automatically. 1400 1401config DEBUG_SPINLOCK 1402 bool "Spinlock and rw-lock debugging: basic checks" 1403 depends on DEBUG_KERNEL 1404 select UNINLINE_SPIN_UNLOCK 1405 help 1406 Say Y here and build SMP to catch missing spinlock initialization 1407 and certain other kinds of spinlock errors commonly made. This is 1408 best used in conjunction with the NMI watchdog so that spinlock 1409 deadlocks are also debuggable. 1410 1411config DEBUG_MUTEXES 1412 bool "Mutex debugging: basic checks" 1413 depends on DEBUG_KERNEL && !PREEMPT_RT 1414 help 1415 This feature allows mutex semantics violations to be detected and 1416 reported. 1417 1418config DEBUG_WW_MUTEX_SLOWPATH 1419 bool "Wait/wound mutex debugging: Slowpath testing" 1420 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1421 select DEBUG_LOCK_ALLOC 1422 select DEBUG_SPINLOCK 1423 select DEBUG_MUTEXES if !PREEMPT_RT 1424 select DEBUG_RT_MUTEXES if PREEMPT_RT 1425 help 1426 This feature enables slowpath testing for w/w mutex users by 1427 injecting additional -EDEADLK wound/backoff cases. Together with 1428 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1429 will test all possible w/w mutex interface abuse with the 1430 exception of simply not acquiring all the required locks. 1431 Note that this feature can introduce significant overhead, so 1432 it really should not be enabled in a production or distro kernel, 1433 even a debug kernel. If you are a driver writer, enable it. If 1434 you are a distro, do not. 1435 1436config DEBUG_RWSEMS 1437 bool "RW Semaphore debugging: basic checks" 1438 depends on DEBUG_KERNEL 1439 help 1440 This debugging feature allows mismatched rw semaphore locks 1441 and unlocks to be detected and reported. 1442 1443config DEBUG_LOCK_ALLOC 1444 bool "Lock debugging: detect incorrect freeing of live locks" 1445 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1446 select DEBUG_SPINLOCK 1447 select DEBUG_MUTEXES if !PREEMPT_RT 1448 select DEBUG_RT_MUTEXES if RT_MUTEXES 1449 select LOCKDEP 1450 help 1451 This feature will check whether any held lock (spinlock, rwlock, 1452 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1453 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1454 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1455 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1456 held during task exit. 1457 1458config LOCKDEP 1459 bool 1460 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1461 select STACKTRACE 1462 select KALLSYMS 1463 select KALLSYMS_ALL 1464 1465config LOCKDEP_SMALL 1466 bool 1467 1468config LOCKDEP_BITS 1469 int "Bitsize for MAX_LOCKDEP_ENTRIES" 1470 depends on LOCKDEP && !LOCKDEP_SMALL 1471 range 10 30 1472 default 15 1473 help 1474 Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message. 1475 1476config LOCKDEP_CHAINS_BITS 1477 int "Bitsize for MAX_LOCKDEP_CHAINS" 1478 depends on LOCKDEP && !LOCKDEP_SMALL 1479 range 10 30 1480 default 16 1481 help 1482 Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message. 1483 1484config LOCKDEP_STACK_TRACE_BITS 1485 int "Bitsize for MAX_STACK_TRACE_ENTRIES" 1486 depends on LOCKDEP && !LOCKDEP_SMALL 1487 range 10 30 1488 default 19 1489 help 1490 Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message. 1491 1492config LOCKDEP_STACK_TRACE_HASH_BITS 1493 int "Bitsize for STACK_TRACE_HASH_SIZE" 1494 depends on LOCKDEP && !LOCKDEP_SMALL 1495 range 10 30 1496 default 14 1497 help 1498 Try increasing this value if you need large STACK_TRACE_HASH_SIZE. 1499 1500config LOCKDEP_CIRCULAR_QUEUE_BITS 1501 int "Bitsize for elements in circular_queue struct" 1502 depends on LOCKDEP 1503 range 10 30 1504 default 12 1505 help 1506 Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure. 1507 1508config DEBUG_LOCKDEP 1509 bool "Lock dependency engine debugging" 1510 depends on DEBUG_KERNEL && LOCKDEP 1511 select DEBUG_IRQFLAGS 1512 help 1513 If you say Y here, the lock dependency engine will do 1514 additional runtime checks to debug itself, at the price 1515 of more runtime overhead. 1516 1517config DEBUG_ATOMIC_SLEEP 1518 bool "Sleep inside atomic section checking" 1519 select PREEMPT_COUNT 1520 depends on DEBUG_KERNEL 1521 depends on !ARCH_NO_PREEMPT 1522 help 1523 If you say Y here, various routines which may sleep will become very 1524 noisy if they are called inside atomic sections: when a spinlock is 1525 held, inside an rcu read side critical section, inside preempt disabled 1526 sections, inside an interrupt, etc... 1527 1528config DEBUG_LOCKING_API_SELFTESTS 1529 bool "Locking API boot-time self-tests" 1530 depends on DEBUG_KERNEL 1531 help 1532 Say Y here if you want the kernel to run a short self-test during 1533 bootup. The self-test checks whether common types of locking bugs 1534 are detected by debugging mechanisms or not. (if you disable 1535 lock debugging then those bugs won't be detected of course.) 1536 The following locking APIs are covered: spinlocks, rwlocks, 1537 mutexes and rwsems. 1538 1539config LOCK_TORTURE_TEST 1540 tristate "torture tests for locking" 1541 depends on DEBUG_KERNEL 1542 select TORTURE_TEST 1543 help 1544 This option provides a kernel module that runs torture tests 1545 on kernel locking primitives. The kernel module may be built 1546 after the fact on the running kernel to be tested, if desired. 1547 1548 Say Y here if you want kernel locking-primitive torture tests 1549 to be built into the kernel. 1550 Say M if you want these torture tests to build as a module. 1551 Say N if you are unsure. 1552 1553config WW_MUTEX_SELFTEST 1554 tristate "Wait/wound mutex selftests" 1555 help 1556 This option provides a kernel module that runs tests on the 1557 on the struct ww_mutex locking API. 1558 1559 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1560 with this test harness. 1561 1562 Say M if you want these self tests to build as a module. 1563 Say N if you are unsure. 1564 1565config SCF_TORTURE_TEST 1566 tristate "torture tests for smp_call_function*()" 1567 depends on DEBUG_KERNEL 1568 select TORTURE_TEST 1569 help 1570 This option provides a kernel module that runs torture tests 1571 on the smp_call_function() family of primitives. The kernel 1572 module may be built after the fact on the running kernel to 1573 be tested, if desired. 1574 1575config CSD_LOCK_WAIT_DEBUG 1576 bool "Debugging for csd_lock_wait(), called from smp_call_function*()" 1577 depends on DEBUG_KERNEL 1578 depends on 64BIT 1579 default n 1580 help 1581 This option enables debug prints when CPUs are slow to respond 1582 to the smp_call_function*() IPI wrappers. These debug prints 1583 include the IPI handler function currently executing (if any) 1584 and relevant stack traces. 1585 1586config CSD_LOCK_WAIT_DEBUG_DEFAULT 1587 bool "Default csd_lock_wait() debugging on at boot time" 1588 depends on CSD_LOCK_WAIT_DEBUG 1589 depends on 64BIT 1590 default n 1591 help 1592 This option causes the csdlock_debug= kernel boot parameter to 1593 default to 1 (basic debugging) instead of 0 (no debugging). 1594 1595endmenu # lock debugging 1596 1597config TRACE_IRQFLAGS 1598 depends on TRACE_IRQFLAGS_SUPPORT 1599 bool 1600 help 1601 Enables hooks to interrupt enabling and disabling for 1602 either tracing or lock debugging. 1603 1604config TRACE_IRQFLAGS_NMI 1605 def_bool y 1606 depends on TRACE_IRQFLAGS 1607 depends on TRACE_IRQFLAGS_NMI_SUPPORT 1608 1609config NMI_CHECK_CPU 1610 bool "Debugging for CPUs failing to respond to backtrace requests" 1611 depends on DEBUG_KERNEL 1612 depends on X86 1613 default n 1614 help 1615 Enables debug prints when a CPU fails to respond to a given 1616 backtrace NMI. These prints provide some reasons why a CPU 1617 might legitimately be failing to respond, for example, if it 1618 is offline of if ignore_nmis is set. 1619 1620config DEBUG_IRQFLAGS 1621 bool "Debug IRQ flag manipulation" 1622 help 1623 Enables checks for potentially unsafe enabling or disabling of 1624 interrupts, such as calling raw_local_irq_restore() when interrupts 1625 are enabled. 1626 1627config STACKTRACE 1628 bool "Stack backtrace support" 1629 depends on STACKTRACE_SUPPORT 1630 help 1631 This option causes the kernel to create a /proc/pid/stack for 1632 every process, showing its current stack trace. 1633 It is also used by various kernel debugging features that require 1634 stack trace generation. 1635 1636config WARN_ALL_UNSEEDED_RANDOM 1637 bool "Warn for all uses of unseeded randomness" 1638 default n 1639 help 1640 Some parts of the kernel contain bugs relating to their use of 1641 cryptographically secure random numbers before it's actually possible 1642 to generate those numbers securely. This setting ensures that these 1643 flaws don't go unnoticed, by enabling a message, should this ever 1644 occur. This will allow people with obscure setups to know when things 1645 are going wrong, so that they might contact developers about fixing 1646 it. 1647 1648 Unfortunately, on some models of some architectures getting 1649 a fully seeded CRNG is extremely difficult, and so this can 1650 result in dmesg getting spammed for a surprisingly long 1651 time. This is really bad from a security perspective, and 1652 so architecture maintainers really need to do what they can 1653 to get the CRNG seeded sooner after the system is booted. 1654 However, since users cannot do anything actionable to 1655 address this, by default this option is disabled. 1656 1657 Say Y here if you want to receive warnings for all uses of 1658 unseeded randomness. This will be of use primarily for 1659 those developers interested in improving the security of 1660 Linux kernels running on their architecture (or 1661 subarchitecture). 1662 1663config DEBUG_KOBJECT 1664 bool "kobject debugging" 1665 depends on DEBUG_KERNEL 1666 help 1667 If you say Y here, some extra kobject debugging messages will be sent 1668 to the syslog. 1669 1670config DEBUG_KOBJECT_RELEASE 1671 bool "kobject release debugging" 1672 depends on DEBUG_OBJECTS_TIMERS 1673 help 1674 kobjects are reference counted objects. This means that their 1675 last reference count put is not predictable, and the kobject can 1676 live on past the point at which a driver decides to drop its 1677 initial reference to the kobject gained on allocation. An 1678 example of this would be a struct device which has just been 1679 unregistered. 1680 1681 However, some buggy drivers assume that after such an operation, 1682 the memory backing the kobject can be immediately freed. This 1683 goes completely against the principles of a refcounted object. 1684 1685 If you say Y here, the kernel will delay the release of kobjects 1686 on the last reference count to improve the visibility of this 1687 kind of kobject release bug. 1688 1689config HAVE_DEBUG_BUGVERBOSE 1690 bool 1691 1692menu "Debug kernel data structures" 1693 1694config DEBUG_LIST 1695 bool "Debug linked list manipulation" 1696 depends on DEBUG_KERNEL 1697 select LIST_HARDENED 1698 help 1699 Enable this to turn on extended checks in the linked-list walking 1700 routines. 1701 1702 This option trades better quality error reports for performance, and 1703 is more suitable for kernel debugging. If you care about performance, 1704 you should only enable CONFIG_LIST_HARDENED instead. 1705 1706 If unsure, say N. 1707 1708config DEBUG_PLIST 1709 bool "Debug priority linked list manipulation" 1710 depends on DEBUG_KERNEL 1711 help 1712 Enable this to turn on extended checks in the priority-ordered 1713 linked-list (plist) walking routines. This checks the entire 1714 list multiple times during each manipulation. 1715 1716 If unsure, say N. 1717 1718config DEBUG_SG 1719 bool "Debug SG table operations" 1720 depends on DEBUG_KERNEL 1721 help 1722 Enable this to turn on checks on scatter-gather tables. This can 1723 help find problems with drivers that do not properly initialize 1724 their sg tables. 1725 1726 If unsure, say N. 1727 1728config DEBUG_NOTIFIERS 1729 bool "Debug notifier call chains" 1730 depends on DEBUG_KERNEL 1731 help 1732 Enable this to turn on sanity checking for notifier call chains. 1733 This is most useful for kernel developers to make sure that 1734 modules properly unregister themselves from notifier chains. 1735 This is a relatively cheap check but if you care about maximum 1736 performance, say N. 1737 1738config DEBUG_MAPLE_TREE 1739 bool "Debug maple trees" 1740 depends on DEBUG_KERNEL 1741 help 1742 Enable maple tree debugging information and extra validations. 1743 1744 If unsure, say N. 1745 1746endmenu 1747 1748source "kernel/rcu/Kconfig.debug" 1749 1750config DEBUG_WQ_FORCE_RR_CPU 1751 bool "Force round-robin CPU selection for unbound work items" 1752 depends on DEBUG_KERNEL 1753 default n 1754 help 1755 Workqueue used to implicitly guarantee that work items queued 1756 without explicit CPU specified are put on the local CPU. This 1757 guarantee is no longer true and while local CPU is still 1758 preferred work items may be put on foreign CPUs. Kernel 1759 parameter "workqueue.debug_force_rr_cpu" is added to force 1760 round-robin CPU selection to flush out usages which depend on the 1761 now broken guarantee. This config option enables the debug 1762 feature by default. When enabled, memory and cache locality will 1763 be impacted. 1764 1765config CPU_HOTPLUG_STATE_CONTROL 1766 bool "Enable CPU hotplug state control" 1767 depends on DEBUG_KERNEL 1768 depends on HOTPLUG_CPU 1769 default n 1770 help 1771 Allows to write steps between "offline" and "online" to the CPUs 1772 sysfs target file so states can be stepped granular. This is a debug 1773 option for now as the hotplug machinery cannot be stopped and 1774 restarted at arbitrary points yet. 1775 1776 Say N if your are unsure. 1777 1778config LATENCYTOP 1779 bool "Latency measuring infrastructure" 1780 depends on DEBUG_KERNEL 1781 depends on STACKTRACE_SUPPORT 1782 depends on PROC_FS 1783 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 1784 select KALLSYMS 1785 select KALLSYMS_ALL 1786 select STACKTRACE 1787 select SCHEDSTATS 1788 help 1789 Enable this option if you want to use the LatencyTOP tool 1790 to find out which userspace is blocking on what kernel operations. 1791 1792config DEBUG_CGROUP_REF 1793 bool "Disable inlining of cgroup css reference count functions" 1794 depends on DEBUG_KERNEL 1795 depends on CGROUPS 1796 depends on KPROBES 1797 default n 1798 help 1799 Force cgroup css reference count functions to not be inlined so 1800 that they can be kprobed for debugging. 1801 1802source "kernel/trace/Kconfig" 1803 1804config PROVIDE_OHCI1394_DMA_INIT 1805 bool "Remote debugging over FireWire early on boot" 1806 depends on PCI && X86 1807 help 1808 If you want to debug problems which hang or crash the kernel early 1809 on boot and the crashing machine has a FireWire port, you can use 1810 this feature to remotely access the memory of the crashed machine 1811 over FireWire. This employs remote DMA as part of the OHCI1394 1812 specification which is now the standard for FireWire controllers. 1813 1814 With remote DMA, you can monitor the printk buffer remotely using 1815 firescope and access all memory below 4GB using fireproxy from gdb. 1816 Even controlling a kernel debugger is possible using remote DMA. 1817 1818 Usage: 1819 1820 If ohci1394_dma=early is used as boot parameter, it will initialize 1821 all OHCI1394 controllers which are found in the PCI config space. 1822 1823 As all changes to the FireWire bus such as enabling and disabling 1824 devices cause a bus reset and thereby disable remote DMA for all 1825 devices, be sure to have the cable plugged and FireWire enabled on 1826 the debugging host before booting the debug target for debugging. 1827 1828 This code (~1k) is freed after boot. By then, the firewire stack 1829 in charge of the OHCI-1394 controllers should be used instead. 1830 1831 See Documentation/core-api/debugging-via-ohci1394.rst for more information. 1832 1833source "samples/Kconfig" 1834 1835config ARCH_HAS_DEVMEM_IS_ALLOWED 1836 bool 1837 1838config STRICT_DEVMEM 1839 bool "Filter access to /dev/mem" 1840 depends on MMU && DEVMEM 1841 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED 1842 default y if PPC || X86 || ARM64 1843 help 1844 If this option is disabled, you allow userspace (root) access to all 1845 of memory, including kernel and userspace memory. Accidental 1846 access to this is obviously disastrous, but specific access can 1847 be used by people debugging the kernel. Note that with PAT support 1848 enabled, even in this case there are restrictions on /dev/mem 1849 use due to the cache aliasing requirements. 1850 1851 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 1852 file only allows userspace access to PCI space and the BIOS code and 1853 data regions. This is sufficient for dosemu and X and all common 1854 users of /dev/mem. 1855 1856 If in doubt, say Y. 1857 1858config IO_STRICT_DEVMEM 1859 bool "Filter I/O access to /dev/mem" 1860 depends on STRICT_DEVMEM 1861 help 1862 If this option is disabled, you allow userspace (root) access to all 1863 io-memory regardless of whether a driver is actively using that 1864 range. Accidental access to this is obviously disastrous, but 1865 specific access can be used by people debugging kernel drivers. 1866 1867 If this option is switched on, the /dev/mem file only allows 1868 userspace access to *idle* io-memory ranges (see /proc/iomem) This 1869 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 1870 if the driver using a given range cannot be disabled. 1871 1872 If in doubt, say Y. 1873 1874menu "$(SRCARCH) Debugging" 1875 1876source "arch/$(SRCARCH)/Kconfig.debug" 1877 1878endmenu 1879 1880menu "Kernel Testing and Coverage" 1881 1882source "lib/kunit/Kconfig" 1883 1884config NOTIFIER_ERROR_INJECTION 1885 tristate "Notifier error injection" 1886 depends on DEBUG_KERNEL 1887 select DEBUG_FS 1888 help 1889 This option provides the ability to inject artificial errors to 1890 specified notifier chain callbacks. It is useful to test the error 1891 handling of notifier call chain failures. 1892 1893 Say N if unsure. 1894 1895config PM_NOTIFIER_ERROR_INJECT 1896 tristate "PM notifier error injection module" 1897 depends on PM && NOTIFIER_ERROR_INJECTION 1898 default m if PM_DEBUG 1899 help 1900 This option provides the ability to inject artificial errors to 1901 PM notifier chain callbacks. It is controlled through debugfs 1902 interface /sys/kernel/debug/notifier-error-inject/pm 1903 1904 If the notifier call chain should be failed with some events 1905 notified, write the error code to "actions/<notifier event>/error". 1906 1907 Example: Inject PM suspend error (-12 = -ENOMEM) 1908 1909 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1910 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1911 # echo mem > /sys/power/state 1912 bash: echo: write error: Cannot allocate memory 1913 1914 To compile this code as a module, choose M here: the module will 1915 be called pm-notifier-error-inject. 1916 1917 If unsure, say N. 1918 1919config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1920 tristate "OF reconfig notifier error injection module" 1921 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1922 help 1923 This option provides the ability to inject artificial errors to 1924 OF reconfig notifier chain callbacks. It is controlled 1925 through debugfs interface under 1926 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1927 1928 If the notifier call chain should be failed with some events 1929 notified, write the error code to "actions/<notifier event>/error". 1930 1931 To compile this code as a module, choose M here: the module will 1932 be called of-reconfig-notifier-error-inject. 1933 1934 If unsure, say N. 1935 1936config NETDEV_NOTIFIER_ERROR_INJECT 1937 tristate "Netdev notifier error injection module" 1938 depends on NET && NOTIFIER_ERROR_INJECTION 1939 help 1940 This option provides the ability to inject artificial errors to 1941 netdevice notifier chain callbacks. It is controlled through debugfs 1942 interface /sys/kernel/debug/notifier-error-inject/netdev 1943 1944 If the notifier call chain should be failed with some events 1945 notified, write the error code to "actions/<notifier event>/error". 1946 1947 Example: Inject netdevice mtu change error (-22 = -EINVAL) 1948 1949 # cd /sys/kernel/debug/notifier-error-inject/netdev 1950 # echo -22 > actions/NETDEV_CHANGEMTU/error 1951 # ip link set eth0 mtu 1024 1952 RTNETLINK answers: Invalid argument 1953 1954 To compile this code as a module, choose M here: the module will 1955 be called netdev-notifier-error-inject. 1956 1957 If unsure, say N. 1958 1959config FUNCTION_ERROR_INJECTION 1960 bool "Fault-injections of functions" 1961 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 1962 help 1963 Add fault injections into various functions that are annotated with 1964 ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return 1965 value of these functions. This is useful to test error paths of code. 1966 1967 If unsure, say N 1968 1969config FAULT_INJECTION 1970 bool "Fault-injection framework" 1971 depends on DEBUG_KERNEL 1972 help 1973 Provide fault-injection framework. 1974 For more details, see Documentation/fault-injection/. 1975 1976config FAILSLAB 1977 bool "Fault-injection capability for kmalloc" 1978 depends on FAULT_INJECTION 1979 depends on SLAB || SLUB 1980 help 1981 Provide fault-injection capability for kmalloc. 1982 1983config FAIL_PAGE_ALLOC 1984 bool "Fault-injection capability for alloc_pages()" 1985 depends on FAULT_INJECTION 1986 help 1987 Provide fault-injection capability for alloc_pages(). 1988 1989config FAULT_INJECTION_USERCOPY 1990 bool "Fault injection capability for usercopy functions" 1991 depends on FAULT_INJECTION 1992 help 1993 Provides fault-injection capability to inject failures 1994 in usercopy functions (copy_from_user(), get_user(), ...). 1995 1996config FAIL_MAKE_REQUEST 1997 bool "Fault-injection capability for disk IO" 1998 depends on FAULT_INJECTION && BLOCK 1999 help 2000 Provide fault-injection capability for disk IO. 2001 2002config FAIL_IO_TIMEOUT 2003 bool "Fault-injection capability for faking disk interrupts" 2004 depends on FAULT_INJECTION && BLOCK 2005 help 2006 Provide fault-injection capability on end IO handling. This 2007 will make the block layer "forget" an interrupt as configured, 2008 thus exercising the error handling. 2009 2010 Only works with drivers that use the generic timeout handling, 2011 for others it won't do anything. 2012 2013config FAIL_FUTEX 2014 bool "Fault-injection capability for futexes" 2015 select DEBUG_FS 2016 depends on FAULT_INJECTION && FUTEX 2017 help 2018 Provide fault-injection capability for futexes. 2019 2020config FAULT_INJECTION_DEBUG_FS 2021 bool "Debugfs entries for fault-injection capabilities" 2022 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 2023 help 2024 Enable configuration of fault-injection capabilities via debugfs. 2025 2026config FAIL_FUNCTION 2027 bool "Fault-injection capability for functions" 2028 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 2029 help 2030 Provide function-based fault-injection capability. 2031 This will allow you to override a specific function with a return 2032 with given return value. As a result, function caller will see 2033 an error value and have to handle it. This is useful to test the 2034 error handling in various subsystems. 2035 2036config FAIL_MMC_REQUEST 2037 bool "Fault-injection capability for MMC IO" 2038 depends on FAULT_INJECTION_DEBUG_FS && MMC 2039 help 2040 Provide fault-injection capability for MMC IO. 2041 This will make the mmc core return data errors. This is 2042 useful to test the error handling in the mmc block device 2043 and to test how the mmc host driver handles retries from 2044 the block device. 2045 2046config FAIL_SUNRPC 2047 bool "Fault-injection capability for SunRPC" 2048 depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG 2049 help 2050 Provide fault-injection capability for SunRPC and 2051 its consumers. 2052 2053config FAULT_INJECTION_CONFIGFS 2054 bool "Configfs interface for fault-injection capabilities" 2055 depends on FAULT_INJECTION 2056 select CONFIGFS_FS 2057 help 2058 This option allows configfs-based drivers to dynamically configure 2059 fault-injection via configfs. Each parameter for driver-specific 2060 fault-injection can be made visible as a configfs attribute in a 2061 configfs group. 2062 2063 2064config FAULT_INJECTION_STACKTRACE_FILTER 2065 bool "stacktrace filter for fault-injection capabilities" 2066 depends on FAULT_INJECTION 2067 depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT 2068 select STACKTRACE 2069 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 2070 help 2071 Provide stacktrace filter for fault-injection capabilities 2072 2073config ARCH_HAS_KCOV 2074 bool 2075 help 2076 An architecture should select this when it can successfully 2077 build and run with CONFIG_KCOV. This typically requires 2078 disabling instrumentation for some early boot code. 2079 2080config CC_HAS_SANCOV_TRACE_PC 2081 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 2082 2083 2084config KCOV 2085 bool "Code coverage for fuzzing" 2086 depends on ARCH_HAS_KCOV 2087 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 2088 depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \ 2089 GCC_VERSION >= 120000 || CLANG_VERSION >= 130000 2090 select DEBUG_FS 2091 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 2092 select OBJTOOL if HAVE_NOINSTR_HACK 2093 help 2094 KCOV exposes kernel code coverage information in a form suitable 2095 for coverage-guided fuzzing (randomized testing). 2096 2097 If RANDOMIZE_BASE is enabled, PC values will not be stable across 2098 different machines and across reboots. If you need stable PC values, 2099 disable RANDOMIZE_BASE. 2100 2101 For more details, see Documentation/dev-tools/kcov.rst. 2102 2103config KCOV_ENABLE_COMPARISONS 2104 bool "Enable comparison operands collection by KCOV" 2105 depends on KCOV 2106 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 2107 help 2108 KCOV also exposes operands of every comparison in the instrumented 2109 code along with operand sizes and PCs of the comparison instructions. 2110 These operands can be used by fuzzing engines to improve the quality 2111 of fuzzing coverage. 2112 2113config KCOV_INSTRUMENT_ALL 2114 bool "Instrument all code by default" 2115 depends on KCOV 2116 default y 2117 help 2118 If you are doing generic system call fuzzing (like e.g. syzkaller), 2119 then you will want to instrument the whole kernel and you should 2120 say y here. If you are doing more targeted fuzzing (like e.g. 2121 filesystem fuzzing with AFL) then you will want to enable coverage 2122 for more specific subsets of files, and should say n here. 2123 2124config KCOV_IRQ_AREA_SIZE 2125 hex "Size of interrupt coverage collection area in words" 2126 depends on KCOV 2127 default 0x40000 2128 help 2129 KCOV uses preallocated per-cpu areas to collect coverage from 2130 soft interrupts. This specifies the size of those areas in the 2131 number of unsigned long words. 2132 2133menuconfig RUNTIME_TESTING_MENU 2134 bool "Runtime Testing" 2135 def_bool y 2136 2137if RUNTIME_TESTING_MENU 2138 2139config TEST_DHRY 2140 tristate "Dhrystone benchmark test" 2141 help 2142 Enable this to include the Dhrystone 2.1 benchmark. This test 2143 calculates the number of Dhrystones per second, and the number of 2144 DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided 2145 by 1757 (the number of Dhrystones per second obtained on the VAX 2146 11/780, nominally a 1 MIPS machine). 2147 2148 To run the benchmark, it needs to be enabled explicitly, either from 2149 the kernel command line (when built-in), or from userspace (when 2150 built-in or modular. 2151 2152 Run once during kernel boot: 2153 2154 test_dhry.run 2155 2156 Set number of iterations from kernel command line: 2157 2158 test_dhry.iterations=<n> 2159 2160 Set number of iterations from userspace: 2161 2162 echo <n> > /sys/module/test_dhry/parameters/iterations 2163 2164 Trigger manual run from userspace: 2165 2166 echo y > /sys/module/test_dhry/parameters/run 2167 2168 If the number of iterations is <= 0, the test will devise a suitable 2169 number of iterations (test runs for at least 2s) automatically. 2170 This process takes ca. 4s. 2171 2172 If unsure, say N. 2173 2174config LKDTM 2175 tristate "Linux Kernel Dump Test Tool Module" 2176 depends on DEBUG_FS 2177 help 2178 This module enables testing of the different dumping mechanisms by 2179 inducing system failures at predefined crash points. 2180 If you don't need it: say N 2181 Choose M here to compile this code as a module. The module will be 2182 called lkdtm. 2183 2184 Documentation on how to use the module can be found in 2185 Documentation/fault-injection/provoke-crashes.rst 2186 2187config CPUMASK_KUNIT_TEST 2188 tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS 2189 depends on KUNIT 2190 default KUNIT_ALL_TESTS 2191 help 2192 Enable to turn on cpumask tests, running at boot or module load time. 2193 2194 For more information on KUnit and unit tests in general, please refer 2195 to the KUnit documentation in Documentation/dev-tools/kunit/. 2196 2197 If unsure, say N. 2198 2199config TEST_LIST_SORT 2200 tristate "Linked list sorting test" if !KUNIT_ALL_TESTS 2201 depends on KUNIT 2202 default KUNIT_ALL_TESTS 2203 help 2204 Enable this to turn on 'list_sort()' function test. This test is 2205 executed only once during system boot (so affects only boot time), 2206 or at module load time. 2207 2208 If unsure, say N. 2209 2210config TEST_MIN_HEAP 2211 tristate "Min heap test" 2212 depends on DEBUG_KERNEL || m 2213 help 2214 Enable this to turn on min heap function tests. This test is 2215 executed only once during system boot (so affects only boot time), 2216 or at module load time. 2217 2218 If unsure, say N. 2219 2220config TEST_SORT 2221 tristate "Array-based sort test" if !KUNIT_ALL_TESTS 2222 depends on KUNIT 2223 default KUNIT_ALL_TESTS 2224 help 2225 This option enables the self-test function of 'sort()' at boot, 2226 or at module load time. 2227 2228 If unsure, say N. 2229 2230config TEST_DIV64 2231 tristate "64bit/32bit division and modulo test" 2232 depends on DEBUG_KERNEL || m 2233 help 2234 Enable this to turn on 'do_div()' function test. This test is 2235 executed only once during system boot (so affects only boot time), 2236 or at module load time. 2237 2238 If unsure, say N. 2239 2240config TEST_IOV_ITER 2241 tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS 2242 depends on KUNIT 2243 depends on MMU 2244 default KUNIT_ALL_TESTS 2245 help 2246 Enable this to turn on testing of the operation of the I/O iterator 2247 (iov_iter). This test is executed only once during system boot (so 2248 affects only boot time), or at module load time. 2249 2250 If unsure, say N. 2251 2252config KPROBES_SANITY_TEST 2253 tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS 2254 depends on DEBUG_KERNEL 2255 depends on KPROBES 2256 depends on KUNIT 2257 select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 2258 default KUNIT_ALL_TESTS 2259 help 2260 This option provides for testing basic kprobes functionality on 2261 boot. Samples of kprobe and kretprobe are inserted and 2262 verified for functionality. 2263 2264 Say N if you are unsure. 2265 2266config FPROBE_SANITY_TEST 2267 bool "Self test for fprobe" 2268 depends on DEBUG_KERNEL 2269 depends on FPROBE 2270 depends on KUNIT=y 2271 help 2272 This option will enable testing the fprobe when the system boot. 2273 A series of tests are made to verify that the fprobe is functioning 2274 properly. 2275 2276 Say N if you are unsure. 2277 2278config BACKTRACE_SELF_TEST 2279 tristate "Self test for the backtrace code" 2280 depends on DEBUG_KERNEL 2281 help 2282 This option provides a kernel module that can be used to test 2283 the kernel stack backtrace code. This option is not useful 2284 for distributions or general kernels, but only for kernel 2285 developers working on architecture code. 2286 2287 Note that if you want to also test saved backtraces, you will 2288 have to enable STACKTRACE as well. 2289 2290 Say N if you are unsure. 2291 2292config TEST_REF_TRACKER 2293 tristate "Self test for reference tracker" 2294 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT 2295 select REF_TRACKER 2296 help 2297 This option provides a kernel module performing tests 2298 using reference tracker infrastructure. 2299 2300 Say N if you are unsure. 2301 2302config RBTREE_TEST 2303 tristate "Red-Black tree test" 2304 depends on DEBUG_KERNEL 2305 help 2306 A benchmark measuring the performance of the rbtree library. 2307 Also includes rbtree invariant checks. 2308 2309config REED_SOLOMON_TEST 2310 tristate "Reed-Solomon library test" 2311 depends on DEBUG_KERNEL || m 2312 select REED_SOLOMON 2313 select REED_SOLOMON_ENC16 2314 select REED_SOLOMON_DEC16 2315 help 2316 This option enables the self-test function of rslib at boot, 2317 or at module load time. 2318 2319 If unsure, say N. 2320 2321config INTERVAL_TREE_TEST 2322 tristate "Interval tree test" 2323 depends on DEBUG_KERNEL 2324 select INTERVAL_TREE 2325 help 2326 A benchmark measuring the performance of the interval tree library 2327 2328config PERCPU_TEST 2329 tristate "Per cpu operations test" 2330 depends on m && DEBUG_KERNEL 2331 help 2332 Enable this option to build test module which validates per-cpu 2333 operations. 2334 2335 If unsure, say N. 2336 2337config ATOMIC64_SELFTEST 2338 tristate "Perform an atomic64_t self-test" 2339 help 2340 Enable this option to test the atomic64_t functions at boot or 2341 at module load time. 2342 2343 If unsure, say N. 2344 2345config ASYNC_RAID6_TEST 2346 tristate "Self test for hardware accelerated raid6 recovery" 2347 depends on ASYNC_RAID6_RECOV 2348 select ASYNC_MEMCPY 2349 help 2350 This is a one-shot self test that permutes through the 2351 recovery of all the possible two disk failure scenarios for a 2352 N-disk array. Recovery is performed with the asynchronous 2353 raid6 recovery routines, and will optionally use an offload 2354 engine if one is available. 2355 2356 If unsure, say N. 2357 2358config TEST_HEXDUMP 2359 tristate "Test functions located in the hexdump module at runtime" 2360 2361config STRING_SELFTEST 2362 tristate "Test string functions at runtime" 2363 2364config TEST_STRING_HELPERS 2365 tristate "Test functions located in the string_helpers module at runtime" 2366 2367config TEST_KSTRTOX 2368 tristate "Test kstrto*() family of functions at runtime" 2369 2370config TEST_PRINTF 2371 tristate "Test printf() family of functions at runtime" 2372 2373config TEST_SCANF 2374 tristate "Test scanf() family of functions at runtime" 2375 2376config TEST_BITMAP 2377 tristate "Test bitmap_*() family of functions at runtime" 2378 help 2379 Enable this option to test the bitmap functions at boot. 2380 2381 If unsure, say N. 2382 2383config TEST_UUID 2384 tristate "Test functions located in the uuid module at runtime" 2385 2386config TEST_XARRAY 2387 tristate "Test the XArray code at runtime" 2388 2389config TEST_MAPLE_TREE 2390 tristate "Test the Maple Tree code at runtime or module load" 2391 help 2392 Enable this option to test the maple tree code functions at boot, or 2393 when the module is loaded. Enable "Debug Maple Trees" will enable 2394 more verbose output on failures. 2395 2396 If unsure, say N. 2397 2398config TEST_RHASHTABLE 2399 tristate "Perform selftest on resizable hash table" 2400 help 2401 Enable this option to test the rhashtable functions at boot. 2402 2403 If unsure, say N. 2404 2405config TEST_IDA 2406 tristate "Perform selftest on IDA functions" 2407 2408config TEST_PARMAN 2409 tristate "Perform selftest on priority array manager" 2410 depends on PARMAN 2411 help 2412 Enable this option to test priority array manager on boot 2413 (or module load). 2414 2415 If unsure, say N. 2416 2417config TEST_IRQ_TIMINGS 2418 bool "IRQ timings selftest" 2419 depends on IRQ_TIMINGS 2420 help 2421 Enable this option to test the irq timings code on boot. 2422 2423 If unsure, say N. 2424 2425config TEST_LKM 2426 tristate "Test module loading with 'hello world' module" 2427 depends on m 2428 help 2429 This builds the "test_module" module that emits "Hello, world" 2430 on printk when loaded. It is designed to be used for basic 2431 evaluation of the module loading subsystem (for example when 2432 validating module verification). It lacks any extra dependencies, 2433 and will not normally be loaded by the system unless explicitly 2434 requested by name. 2435 2436 If unsure, say N. 2437 2438config TEST_BITOPS 2439 tristate "Test module for compilation of bitops operations" 2440 depends on m 2441 help 2442 This builds the "test_bitops" module that is much like the 2443 TEST_LKM module except that it does a basic exercise of the 2444 set/clear_bit macros and get_count_order/long to make sure there are 2445 no compiler warnings from C=1 sparse checker or -Wextra 2446 compilations. It has no dependencies and doesn't run or load unless 2447 explicitly requested by name. for example: modprobe test_bitops. 2448 2449 If unsure, say N. 2450 2451config TEST_VMALLOC 2452 tristate "Test module for stress/performance analysis of vmalloc allocator" 2453 default n 2454 depends on MMU 2455 depends on m 2456 help 2457 This builds the "test_vmalloc" module that should be used for 2458 stress and performance analysis. So, any new change for vmalloc 2459 subsystem can be evaluated from performance and stability point 2460 of view. 2461 2462 If unsure, say N. 2463 2464config TEST_USER_COPY 2465 tristate "Test user/kernel boundary protections" 2466 depends on m 2467 help 2468 This builds the "test_user_copy" module that runs sanity checks 2469 on the copy_to/from_user infrastructure, making sure basic 2470 user/kernel boundary testing is working. If it fails to load, 2471 a regression has been detected in the user/kernel memory boundary 2472 protections. 2473 2474 If unsure, say N. 2475 2476config TEST_BPF 2477 tristate "Test BPF filter functionality" 2478 depends on m && NET 2479 help 2480 This builds the "test_bpf" module that runs various test vectors 2481 against the BPF interpreter or BPF JIT compiler depending on the 2482 current setting. This is in particular useful for BPF JIT compiler 2483 development, but also to run regression tests against changes in 2484 the interpreter code. It also enables test stubs for eBPF maps and 2485 verifier used by user space verifier testsuite. 2486 2487 If unsure, say N. 2488 2489config TEST_BLACKHOLE_DEV 2490 tristate "Test blackhole netdev functionality" 2491 depends on m && NET 2492 help 2493 This builds the "test_blackhole_dev" module that validates the 2494 data path through this blackhole netdev. 2495 2496 If unsure, say N. 2497 2498config FIND_BIT_BENCHMARK 2499 tristate "Test find_bit functions" 2500 help 2501 This builds the "test_find_bit" module that measure find_*_bit() 2502 functions performance. 2503 2504 If unsure, say N. 2505 2506config TEST_FIRMWARE 2507 tristate "Test firmware loading via userspace interface" 2508 depends on FW_LOADER 2509 help 2510 This builds the "test_firmware" module that creates a userspace 2511 interface for testing firmware loading. This can be used to 2512 control the triggering of firmware loading without needing an 2513 actual firmware-using device. The contents can be rechecked by 2514 userspace. 2515 2516 If unsure, say N. 2517 2518config TEST_SYSCTL 2519 tristate "sysctl test driver" 2520 depends on PROC_SYSCTL 2521 help 2522 This builds the "test_sysctl" module. This driver enables to test the 2523 proc sysctl interfaces available to drivers safely without affecting 2524 production knobs which might alter system functionality. 2525 2526 If unsure, say N. 2527 2528config BITFIELD_KUNIT 2529 tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS 2530 depends on KUNIT 2531 default KUNIT_ALL_TESTS 2532 help 2533 Enable this option to test the bitfield functions at boot. 2534 2535 KUnit tests run during boot and output the results to the debug log 2536 in TAP format (http://testanything.org/). Only useful for kernel devs 2537 running the KUnit test harness, and not intended for inclusion into a 2538 production build. 2539 2540 For more information on KUnit and unit tests in general please refer 2541 to the KUnit documentation in Documentation/dev-tools/kunit/. 2542 2543 If unsure, say N. 2544 2545config CHECKSUM_KUNIT 2546 tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS 2547 depends on KUNIT 2548 default KUNIT_ALL_TESTS 2549 help 2550 Enable this option to test the checksum functions at boot. 2551 2552 KUnit tests run during boot and output the results to the debug log 2553 in TAP format (http://testanything.org/). Only useful for kernel devs 2554 running the KUnit test harness, and not intended for inclusion into a 2555 production build. 2556 2557 For more information on KUnit and unit tests in general please refer 2558 to the KUnit documentation in Documentation/dev-tools/kunit/. 2559 2560 If unsure, say N. 2561 2562config HASH_KUNIT_TEST 2563 tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS 2564 depends on KUNIT 2565 default KUNIT_ALL_TESTS 2566 help 2567 Enable this option to test the kernel's string (<linux/stringhash.h>), and 2568 integer (<linux/hash.h>) hash functions on boot. 2569 2570 KUnit tests run during boot and output the results to the debug log 2571 in TAP format (https://testanything.org/). Only useful for kernel devs 2572 running the KUnit test harness, and not intended for inclusion into a 2573 production build. 2574 2575 For more information on KUnit and unit tests in general please refer 2576 to the KUnit documentation in Documentation/dev-tools/kunit/. 2577 2578 This is intended to help people writing architecture-specific 2579 optimized versions. If unsure, say N. 2580 2581config RESOURCE_KUNIT_TEST 2582 tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS 2583 depends on KUNIT 2584 default KUNIT_ALL_TESTS 2585 help 2586 This builds the resource API unit test. 2587 Tests the logic of API provided by resource.c and ioport.h. 2588 For more information on KUnit and unit tests in general please refer 2589 to the KUnit documentation in Documentation/dev-tools/kunit/. 2590 2591 If unsure, say N. 2592 2593config SYSCTL_KUNIT_TEST 2594 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS 2595 depends on KUNIT 2596 default KUNIT_ALL_TESTS 2597 help 2598 This builds the proc sysctl unit test, which runs on boot. 2599 Tests the API contract and implementation correctness of sysctl. 2600 For more information on KUnit and unit tests in general please refer 2601 to the KUnit documentation in Documentation/dev-tools/kunit/. 2602 2603 If unsure, say N. 2604 2605config LIST_KUNIT_TEST 2606 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS 2607 depends on KUNIT 2608 default KUNIT_ALL_TESTS 2609 help 2610 This builds the linked list KUnit test suite. 2611 It tests that the API and basic functionality of the list_head type 2612 and associated macros. 2613 2614 KUnit tests run during boot and output the results to the debug log 2615 in TAP format (https://testanything.org/). Only useful for kernel devs 2616 running the KUnit test harness, and not intended for inclusion into a 2617 production build. 2618 2619 For more information on KUnit and unit tests in general please refer 2620 to the KUnit documentation in Documentation/dev-tools/kunit/. 2621 2622 If unsure, say N. 2623 2624config HASHTABLE_KUNIT_TEST 2625 tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS 2626 depends on KUNIT 2627 default KUNIT_ALL_TESTS 2628 help 2629 This builds the hashtable KUnit test suite. 2630 It tests the basic functionality of the API defined in 2631 include/linux/hashtable.h. For more information on KUnit and 2632 unit tests in general please refer to the KUnit documentation 2633 in Documentation/dev-tools/kunit/. 2634 2635 If unsure, say N. 2636 2637config LINEAR_RANGES_TEST 2638 tristate "KUnit test for linear_ranges" 2639 depends on KUNIT 2640 select LINEAR_RANGES 2641 help 2642 This builds the linear_ranges unit test, which runs on boot. 2643 Tests the linear_ranges logic correctness. 2644 For more information on KUnit and unit tests in general please refer 2645 to the KUnit documentation in Documentation/dev-tools/kunit/. 2646 2647 If unsure, say N. 2648 2649config CMDLINE_KUNIT_TEST 2650 tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS 2651 depends on KUNIT 2652 default KUNIT_ALL_TESTS 2653 help 2654 This builds the cmdline API unit test. 2655 Tests the logic of API provided by cmdline.c. 2656 For more information on KUnit and unit tests in general please refer 2657 to the KUnit documentation in Documentation/dev-tools/kunit/. 2658 2659 If unsure, say N. 2660 2661config BITS_TEST 2662 tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS 2663 depends on KUNIT 2664 default KUNIT_ALL_TESTS 2665 help 2666 This builds the bits unit test. 2667 Tests the logic of macros defined in bits.h. 2668 For more information on KUnit and unit tests in general please refer 2669 to the KUnit documentation in Documentation/dev-tools/kunit/. 2670 2671 If unsure, say N. 2672 2673config SLUB_KUNIT_TEST 2674 tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS 2675 depends on SLUB_DEBUG && KUNIT 2676 default KUNIT_ALL_TESTS 2677 help 2678 This builds SLUB allocator unit test. 2679 Tests SLUB cache debugging functionality. 2680 For more information on KUnit and unit tests in general please refer 2681 to the KUnit documentation in Documentation/dev-tools/kunit/. 2682 2683 If unsure, say N. 2684 2685config RATIONAL_KUNIT_TEST 2686 tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS 2687 depends on KUNIT && RATIONAL 2688 default KUNIT_ALL_TESTS 2689 help 2690 This builds the rational math unit test. 2691 For more information on KUnit and unit tests in general please refer 2692 to the KUnit documentation in Documentation/dev-tools/kunit/. 2693 2694 If unsure, say N. 2695 2696config MEMCPY_KUNIT_TEST 2697 tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS 2698 depends on KUNIT 2699 default KUNIT_ALL_TESTS 2700 help 2701 Builds unit tests for memcpy(), memmove(), and memset() functions. 2702 For more information on KUnit and unit tests in general please refer 2703 to the KUnit documentation in Documentation/dev-tools/kunit/. 2704 2705 If unsure, say N. 2706 2707config MEMCPY_SLOW_KUNIT_TEST 2708 bool "Include exhaustive memcpy tests" 2709 depends on MEMCPY_KUNIT_TEST 2710 default y 2711 help 2712 Some memcpy tests are quite exhaustive in checking for overlaps 2713 and bit ranges. These can be very slow, so they are split out 2714 as a separate config, in case they need to be disabled. 2715 2716 Note this config option will be replaced by the use of KUnit test 2717 attributes. 2718 2719config IS_SIGNED_TYPE_KUNIT_TEST 2720 tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS 2721 depends on KUNIT 2722 default KUNIT_ALL_TESTS 2723 help 2724 Builds unit tests for the is_signed_type() macro. 2725 2726 For more information on KUnit and unit tests in general please refer 2727 to the KUnit documentation in Documentation/dev-tools/kunit/. 2728 2729 If unsure, say N. 2730 2731config OVERFLOW_KUNIT_TEST 2732 tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS 2733 depends on KUNIT 2734 default KUNIT_ALL_TESTS 2735 help 2736 Builds unit tests for the check_*_overflow(), size_*(), allocation, and 2737 related functions. 2738 2739 For more information on KUnit and unit tests in general please refer 2740 to the KUnit documentation in Documentation/dev-tools/kunit/. 2741 2742 If unsure, say N. 2743 2744config STACKINIT_KUNIT_TEST 2745 tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS 2746 depends on KUNIT 2747 default KUNIT_ALL_TESTS 2748 help 2749 Test if the kernel is zero-initializing stack variables and 2750 padding. Coverage is controlled by compiler flags, 2751 CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO, 2752 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2753 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2754 2755config FORTIFY_KUNIT_TEST 2756 tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS 2757 depends on KUNIT && FORTIFY_SOURCE 2758 default KUNIT_ALL_TESTS 2759 help 2760 Builds unit tests for checking internals of FORTIFY_SOURCE as used 2761 by the str*() and mem*() family of functions. For testing runtime 2762 traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests. 2763 2764config HW_BREAKPOINT_KUNIT_TEST 2765 bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS 2766 depends on HAVE_HW_BREAKPOINT 2767 depends on KUNIT=y 2768 default KUNIT_ALL_TESTS 2769 help 2770 Tests for hw_breakpoint constraints accounting. 2771 2772 If unsure, say N. 2773 2774config STRCAT_KUNIT_TEST 2775 tristate "Test strcat() family of functions at runtime" if !KUNIT_ALL_TESTS 2776 depends on KUNIT 2777 default KUNIT_ALL_TESTS 2778 2779config STRSCPY_KUNIT_TEST 2780 tristate "Test strscpy*() family of functions at runtime" if !KUNIT_ALL_TESTS 2781 depends on KUNIT 2782 default KUNIT_ALL_TESTS 2783 2784config SIPHASH_KUNIT_TEST 2785 tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS 2786 depends on KUNIT 2787 default KUNIT_ALL_TESTS 2788 help 2789 Enable this option to test the kernel's siphash (<linux/siphash.h>) hash 2790 functions on boot (or module load). 2791 2792 This is intended to help people writing architecture-specific 2793 optimized versions. If unsure, say N. 2794 2795config TEST_UDELAY 2796 tristate "udelay test driver" 2797 help 2798 This builds the "udelay_test" module that helps to make sure 2799 that udelay() is working properly. 2800 2801 If unsure, say N. 2802 2803config TEST_STATIC_KEYS 2804 tristate "Test static keys" 2805 depends on m 2806 help 2807 Test the static key interfaces. 2808 2809 If unsure, say N. 2810 2811config TEST_DYNAMIC_DEBUG 2812 tristate "Test DYNAMIC_DEBUG" 2813 depends on DYNAMIC_DEBUG 2814 help 2815 This module registers a tracer callback to count enabled 2816 pr_debugs in a 'do_debugging' function, then alters their 2817 enablements, calls the function, and compares counts. 2818 2819 If unsure, say N. 2820 2821config TEST_KMOD 2822 tristate "kmod stress tester" 2823 depends on m 2824 depends on NETDEVICES && NET_CORE && INET # for TUN 2825 depends on BLOCK 2826 depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS 2827 select TEST_LKM 2828 select XFS_FS 2829 select TUN 2830 select BTRFS_FS 2831 help 2832 Test the kernel's module loading mechanism: kmod. kmod implements 2833 support to load modules using the Linux kernel's usermode helper. 2834 This test provides a series of tests against kmod. 2835 2836 Although technically you can either build test_kmod as a module or 2837 into the kernel we disallow building it into the kernel since 2838 it stress tests request_module() and this will very likely cause 2839 some issues by taking over precious threads available from other 2840 module load requests, ultimately this could be fatal. 2841 2842 To run tests run: 2843 2844 tools/testing/selftests/kmod/kmod.sh --help 2845 2846 If unsure, say N. 2847 2848config TEST_DEBUG_VIRTUAL 2849 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 2850 depends on DEBUG_VIRTUAL 2851 help 2852 Test the kernel's ability to detect incorrect calls to 2853 virt_to_phys() done against the non-linear part of the 2854 kernel's virtual address map. 2855 2856 If unsure, say N. 2857 2858config TEST_MEMCAT_P 2859 tristate "Test memcat_p() helper function" 2860 help 2861 Test the memcat_p() helper for correctly merging two 2862 pointer arrays together. 2863 2864 If unsure, say N. 2865 2866config TEST_LIVEPATCH 2867 tristate "Test livepatching" 2868 default n 2869 depends on DYNAMIC_DEBUG 2870 depends on LIVEPATCH 2871 depends on m 2872 help 2873 Test kernel livepatching features for correctness. The tests will 2874 load test modules that will be livepatched in various scenarios. 2875 2876 To run all the livepatching tests: 2877 2878 make -C tools/testing/selftests TARGETS=livepatch run_tests 2879 2880 Alternatively, individual tests may be invoked: 2881 2882 tools/testing/selftests/livepatch/test-callbacks.sh 2883 tools/testing/selftests/livepatch/test-livepatch.sh 2884 tools/testing/selftests/livepatch/test-shadow-vars.sh 2885 2886 If unsure, say N. 2887 2888config TEST_OBJAGG 2889 tristate "Perform selftest on object aggreration manager" 2890 default n 2891 depends on OBJAGG 2892 help 2893 Enable this option to test object aggregation manager on boot 2894 (or module load). 2895 2896config TEST_MEMINIT 2897 tristate "Test heap/page initialization" 2898 help 2899 Test if the kernel is zero-initializing heap and page allocations. 2900 This can be useful to test init_on_alloc and init_on_free features. 2901 2902 If unsure, say N. 2903 2904config TEST_HMM 2905 tristate "Test HMM (Heterogeneous Memory Management)" 2906 depends on TRANSPARENT_HUGEPAGE 2907 depends on DEVICE_PRIVATE 2908 select HMM_MIRROR 2909 select MMU_NOTIFIER 2910 help 2911 This is a pseudo device driver solely for testing HMM. 2912 Say M here if you want to build the HMM test module. 2913 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests. 2914 2915 If unsure, say N. 2916 2917config TEST_FREE_PAGES 2918 tristate "Test freeing pages" 2919 help 2920 Test that a memory leak does not occur due to a race between 2921 freeing a block of pages and a speculative page reference. 2922 Loading this module is safe if your kernel has the bug fixed. 2923 If the bug is not fixed, it will leak gigabytes of memory and 2924 probably OOM your system. 2925 2926config TEST_FPU 2927 tristate "Test floating point operations in kernel space" 2928 depends on X86 && !KCOV_INSTRUMENT_ALL 2929 help 2930 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu 2931 which will trigger a sequence of floating point operations. This is used 2932 for self-testing floating point control register setting in 2933 kernel_fpu_begin(). 2934 2935 If unsure, say N. 2936 2937config TEST_CLOCKSOURCE_WATCHDOG 2938 tristate "Test clocksource watchdog in kernel space" 2939 depends on CLOCKSOURCE_WATCHDOG 2940 help 2941 Enable this option to create a kernel module that will trigger 2942 a test of the clocksource watchdog. This module may be loaded 2943 via modprobe or insmod in which case it will run upon being 2944 loaded, or it may be built in, in which case it will run 2945 shortly after boot. 2946 2947 If unsure, say N. 2948 2949endif # RUNTIME_TESTING_MENU 2950 2951config ARCH_USE_MEMTEST 2952 bool 2953 help 2954 An architecture should select this when it uses early_memtest() 2955 during boot process. 2956 2957config MEMTEST 2958 bool "Memtest" 2959 depends on ARCH_USE_MEMTEST 2960 help 2961 This option adds a kernel parameter 'memtest', which allows memtest 2962 to be set and executed. 2963 memtest=0, mean disabled; -- default 2964 memtest=1, mean do 1 test pattern; 2965 ... 2966 memtest=17, mean do 17 test patterns. 2967 If you are unsure how to answer this question, answer N. 2968 2969 2970 2971config HYPERV_TESTING 2972 bool "Microsoft Hyper-V driver testing" 2973 default n 2974 depends on HYPERV && DEBUG_FS 2975 help 2976 Select this option to enable Hyper-V vmbus testing. 2977 2978endmenu # "Kernel Testing and Coverage" 2979 2980menu "Rust hacking" 2981 2982config RUST_DEBUG_ASSERTIONS 2983 bool "Debug assertions" 2984 depends on RUST 2985 help 2986 Enables rustc's `-Cdebug-assertions` codegen option. 2987 2988 This flag lets you turn `cfg(debug_assertions)` conditional 2989 compilation on or off. This can be used to enable extra debugging 2990 code in development but not in production. For example, it controls 2991 the behavior of the standard library's `debug_assert!` macro. 2992 2993 Note that this will apply to all Rust code, including `core`. 2994 2995 If unsure, say N. 2996 2997config RUST_OVERFLOW_CHECKS 2998 bool "Overflow checks" 2999 default y 3000 depends on RUST 3001 help 3002 Enables rustc's `-Coverflow-checks` codegen option. 3003 3004 This flag allows you to control the behavior of runtime integer 3005 overflow. When overflow-checks are enabled, a Rust panic will occur 3006 on overflow. 3007 3008 Note that this will apply to all Rust code, including `core`. 3009 3010 If unsure, say Y. 3011 3012config RUST_BUILD_ASSERT_ALLOW 3013 bool "Allow unoptimized build-time assertions" 3014 depends on RUST 3015 help 3016 Controls how are `build_error!` and `build_assert!` handled during build. 3017 3018 If calls to them exist in the binary, it may indicate a violated invariant 3019 or that the optimizer failed to verify the invariant during compilation. 3020 3021 This should not happen, thus by default the build is aborted. However, 3022 as an escape hatch, you can choose Y here to ignore them during build 3023 and let the check be carried at runtime (with `panic!` being called if 3024 the check fails). 3025 3026 If unsure, say N. 3027 3028config RUST_KERNEL_DOCTESTS 3029 bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS 3030 depends on RUST && KUNIT=y 3031 default KUNIT_ALL_TESTS 3032 help 3033 This builds the documentation tests of the `kernel` crate 3034 as KUnit tests. 3035 3036 For more information on KUnit and unit tests in general, 3037 please refer to the KUnit documentation in Documentation/dev-tools/kunit/. 3038 3039 If unsure, say N. 3040 3041endmenu # "Rust" 3042 3043endmenu # Kernel hacking 3044