1 # SPDX-License-Identifier: GPL-2.0-only 2 menu "Kernel hacking" 3 4 menu "printk and dmesg options" 5 6 config 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 21 config 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 38 config 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 49 config 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 64 config 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 75 config 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 90 config 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. 107 108 config 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. 179 180 config 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. 190 191 config 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. 199 200 config 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. 208 209 endmenu # "printk and dmesg options" 210 211 config 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. 216 217 config 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. 224 225 menu "Compile-time checks and compiler options" 226 227 config 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 generates .uleb128 with label differences for DWARF v5, a feature that 235 # older binutils ports do not support when utilizing RISC-V style linker 236 # relaxation: https://sourceware.org/bugzilla/show_bug.cgi?id=27215 237 config AS_HAS_NON_CONST_ULEB128 238 def_bool $(as-instr,.uleb128 .Lexpr_end4 - .Lexpr_start3\n.Lexpr_start3:\n.Lexpr_end4:) 239 240 choice 241 prompt "Debug information" 242 depends on DEBUG_KERNEL 243 help 244 Selecting something other than "None" results in a kernel image 245 that will include debugging info resulting in a larger kernel image. 246 This adds debug symbols to the kernel and modules (gcc -g), and 247 is needed if you intend to use kernel crashdump or binary object 248 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 249 250 Choose which version of DWARF debug info to emit. If unsure, 251 select "Toolchain default". 252 253 config DEBUG_INFO_NONE 254 bool "Disable debug information" 255 help 256 Do not build the kernel with debugging information, which will 257 result in a faster and smaller build. 258 259 config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT 260 bool "Rely on the toolchain's implicit default DWARF version" 261 select DEBUG_INFO 262 depends on !CC_IS_CLANG || AS_IS_LLVM || CLANG_VERSION < 140000 || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128) 263 help 264 The implicit default version of DWARF debug info produced by a 265 toolchain changes over time. 266 267 This can break consumers of the debug info that haven't upgraded to 268 support newer revisions, and prevent testing newer versions, but 269 those should be less common scenarios. 270 271 config DEBUG_INFO_DWARF4 272 bool "Generate DWARF Version 4 debuginfo" 273 select DEBUG_INFO 274 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502) 275 help 276 Generate DWARF v4 debug info. This requires gcc 4.5+, binutils 2.35.2 277 if using clang without clang's integrated assembler, and gdb 7.0+. 278 279 If you have consumers of DWARF debug info that are not ready for 280 newer revisions of DWARF, you may wish to choose this or have your 281 config select this. 282 283 config DEBUG_INFO_DWARF5 284 bool "Generate DWARF Version 5 debuginfo" 285 select DEBUG_INFO 286 depends on !ARCH_HAS_BROKEN_DWARF5 287 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128) 288 help 289 Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc 290 5.0+ accepts the -gdwarf-5 flag but only had partial support for some 291 draft features until 7.0), and gdb 8.0+. 292 293 Changes to the structure of debug info in Version 5 allow for around 294 15-18% savings in resulting image and debug info section sizes as 295 compared to DWARF Version 4. DWARF Version 5 standardizes previous 296 extensions such as accelerators for symbol indexing and the format 297 for fission (.dwo/.dwp) files. Users may not want to select this 298 config if they rely on tooling that has not yet been updated to 299 support DWARF Version 5. 300 301 endchoice # "Debug information" 302 303 if DEBUG_INFO 304 305 config DEBUG_INFO_REDUCED 306 bool "Reduce debugging information" 307 help 308 If you say Y here gcc is instructed to generate less debugging 309 information for structure types. This means that tools that 310 need full debugging information (like kgdb or systemtap) won't 311 be happy. But if you merely need debugging information to 312 resolve line numbers there is no loss. Advantage is that 313 build directory object sizes shrink dramatically over a full 314 DEBUG_INFO build and compile times are reduced too. 315 Only works with newer gcc versions. 316 317 choice 318 prompt "Compressed Debug information" 319 help 320 Compress the resulting debug info. Results in smaller debug info sections, 321 but requires that consumers are able to decompress the results. 322 323 If unsure, choose DEBUG_INFO_COMPRESSED_NONE. 324 325 config DEBUG_INFO_COMPRESSED_NONE 326 bool "Don't compress debug information" 327 help 328 Don't compress debug info sections. 329 330 config DEBUG_INFO_COMPRESSED_ZLIB 331 bool "Compress debugging information with zlib" 332 depends on $(cc-option,-gz=zlib) 333 depends on $(ld-option,--compress-debug-sections=zlib) 334 help 335 Compress the debug information using zlib. Requires GCC 5.0+ or Clang 336 5.0+, binutils 2.26+, and zlib. 337 338 Users of dpkg-deb via scripts/package/builddeb may find an increase in 339 size of their debug .deb packages with this config set, due to the 340 debug info being compressed with zlib, then the object files being 341 recompressed with a different compression scheme. But this is still 342 preferable to setting $KDEB_COMPRESS to "none" which would be even 343 larger. 344 345 config DEBUG_INFO_COMPRESSED_ZSTD 346 bool "Compress debugging information with zstd" 347 depends on $(cc-option,-gz=zstd) 348 depends on $(ld-option,--compress-debug-sections=zstd) 349 help 350 Compress the debug information using zstd. This may provide better 351 compression than zlib, for about the same time costs, but requires newer 352 toolchain support. Requires GCC 13.0+ or Clang 16.0+, binutils 2.40+, and 353 zstd. 354 355 endchoice # "Compressed Debug information" 356 357 config DEBUG_INFO_SPLIT 358 bool "Produce split debuginfo in .dwo files" 359 depends on $(cc-option,-gsplit-dwarf) 360 # RISC-V linker relaxation + -gsplit-dwarf has issues with LLVM and GCC 361 # prior to 12.x: 362 # https://github.com/llvm/llvm-project/issues/56642 363 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99090 364 depends on !RISCV || GCC_VERSION >= 120000 365 help 366 Generate debug info into separate .dwo files. This significantly 367 reduces the build directory size for builds with DEBUG_INFO, 368 because it stores the information only once on disk in .dwo 369 files instead of multiple times in object files and executables. 370 In addition the debug information is also compressed. 371 372 Requires recent gcc (4.7+) and recent gdb/binutils. 373 Any tool that packages or reads debug information would need 374 to know about the .dwo files and include them. 375 Incompatible with older versions of ccache. 376 377 config DEBUG_INFO_BTF 378 bool "Generate BTF type information" 379 depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED 380 depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST 381 depends on BPF_SYSCALL 382 depends on !DEBUG_INFO_DWARF5 || PAHOLE_VERSION >= 121 383 # pahole uses elfutils, which does not have support for Hexagon relocations 384 depends on !HEXAGON 385 help 386 Generate deduplicated BTF type information from DWARF debug info. 387 Turning this on expects presence of pahole tool, which will convert 388 DWARF type info into equivalent deduplicated BTF type info. 389 390 config PAHOLE_HAS_SPLIT_BTF 391 def_bool PAHOLE_VERSION >= 119 392 393 config PAHOLE_HAS_BTF_TAG 394 def_bool PAHOLE_VERSION >= 123 395 depends on CC_IS_CLANG 396 help 397 Decide whether pahole emits btf_tag attributes (btf_type_tag and 398 btf_decl_tag) or not. Currently only clang compiler implements 399 these attributes, so make the config depend on CC_IS_CLANG. 400 401 config PAHOLE_HAS_LANG_EXCLUDE 402 def_bool PAHOLE_VERSION >= 124 403 help 404 Support for the --lang_exclude flag which makes pahole exclude 405 compilation units from the supplied language. Used in Kbuild to 406 omit Rust CUs which are not supported in version 1.24 of pahole, 407 otherwise it would emit malformed kernel and module binaries when 408 using DEBUG_INFO_BTF_MODULES. 409 410 config DEBUG_INFO_BTF_MODULES 411 bool "Generate BTF type information for kernel modules" 412 default y 413 depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF 414 help 415 Generate compact split BTF type information for kernel modules. 416 417 config MODULE_ALLOW_BTF_MISMATCH 418 bool "Allow loading modules with non-matching BTF type info" 419 depends on DEBUG_INFO_BTF_MODULES 420 help 421 For modules whose split BTF does not match vmlinux, load without 422 BTF rather than refusing to load. The default behavior with 423 module BTF enabled is to reject modules with such mismatches; 424 this option will still load module BTF where possible but ignore 425 it when a mismatch is found. 426 427 config GDB_SCRIPTS 428 bool "Provide GDB scripts for kernel debugging" 429 help 430 This creates the required links to GDB helper scripts in the 431 build directory. If you load vmlinux into gdb, the helper 432 scripts will be automatically imported by gdb as well, and 433 additional functions are available to analyze a Linux kernel 434 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst 435 for further details. 436 437 endif # DEBUG_INFO 438 439 config FRAME_WARN 440 int "Warn for stack frames larger than" 441 range 0 8192 442 default 0 if KMSAN 443 default 2048 if GCC_PLUGIN_LATENT_ENTROPY 444 default 2048 if PARISC 445 default 1536 if (!64BIT && XTENSA) 446 default 1280 if KASAN && !64BIT 447 default 1024 if !64BIT 448 default 2048 if 64BIT 449 help 450 Tell the compiler to warn at build time for stack frames larger than this. 451 Setting this too low will cause a lot of warnings. 452 Setting it to 0 disables the warning. 453 454 config STRIP_ASM_SYMS 455 bool "Strip assembler-generated symbols during link" 456 default n 457 help 458 Strip internal assembler-generated symbols during a link (symbols 459 that look like '.Lxxx') so they don't pollute the output of 460 get_wchan() and suchlike. 461 462 config READABLE_ASM 463 bool "Generate readable assembler code" 464 depends on DEBUG_KERNEL 465 depends on CC_IS_GCC 466 help 467 Disable some compiler optimizations that tend to generate human unreadable 468 assembler output. This may make the kernel slightly slower, but it helps 469 to keep kernel developers who have to stare a lot at assembler listings 470 sane. 471 472 config HEADERS_INSTALL 473 bool "Install uapi headers to usr/include" 474 depends on !UML 475 help 476 This option will install uapi headers (headers exported to user-space) 477 into the usr/include directory for use during the kernel build. 478 This is unneeded for building the kernel itself, but needed for some 479 user-space program samples. It is also needed by some features such 480 as uapi header sanity checks. 481 482 config DEBUG_SECTION_MISMATCH 483 bool "Enable full Section mismatch analysis" 484 depends on CC_IS_GCC 485 help 486 The section mismatch analysis checks if there are illegal 487 references from one section to another section. 488 During linktime or runtime, some sections are dropped; 489 any use of code/data previously in these sections would 490 most likely result in an oops. 491 In the code, functions and variables are annotated with 492 __init,, etc. (see the full list in include/linux/init.h), 493 which results in the code/data being placed in specific sections. 494 The section mismatch analysis is always performed after a full 495 kernel build, and enabling this option causes the following 496 additional step to occur: 497 - Add the option -fno-inline-functions-called-once to gcc commands. 498 When inlining a function annotated with __init in a non-init 499 function, we would lose the section information and thus 500 the analysis would not catch the illegal reference. 501 This option tells gcc to inline less (but it does result in 502 a larger kernel). 503 504 config SECTION_MISMATCH_WARN_ONLY 505 bool "Make section mismatch errors non-fatal" 506 default y 507 help 508 If you say N here, the build process will fail if there are any 509 section mismatch, instead of just throwing warnings. 510 511 If unsure, say Y. 512 513 config DEBUG_FORCE_FUNCTION_ALIGN_64B 514 bool "Force all function address 64B aligned" 515 depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC || RISCV || S390) 516 select FUNCTION_ALIGNMENT_64B 517 help 518 There are cases that a commit from one domain changes the function 519 address alignment of other domains, and cause magic performance 520 bump (regression or improvement). Enable this option will help to 521 verify if the bump is caused by function alignment changes, while 522 it will slightly increase the kernel size and affect icache usage. 523 524 It is mainly for debug and performance tuning use. 525 526 # 527 # Select this config option from the architecture Kconfig, if it 528 # is preferred to always offer frame pointers as a config 529 # option on the architecture (regardless of KERNEL_DEBUG): 530 # 531 config ARCH_WANT_FRAME_POINTERS 532 bool 533 534 config FRAME_POINTER 535 bool "Compile the kernel with frame pointers" 536 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS 537 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 538 help 539 If you say Y here the resulting kernel image will be slightly 540 larger and slower, but it gives very useful debugging information 541 in case of kernel bugs. (precise oopses/stacktraces/warnings) 542 543 config OBJTOOL 544 bool 545 546 config STACK_VALIDATION 547 bool "Compile-time stack metadata validation" 548 depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER 549 select OBJTOOL 550 default n 551 help 552 Validate frame pointer rules at compile-time. This helps ensure that 553 runtime stack traces are more reliable. 554 555 For more information, see 556 tools/objtool/Documentation/objtool.txt. 557 558 config NOINSTR_VALIDATION 559 bool 560 depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY 561 select OBJTOOL 562 default y 563 564 config VMLINUX_MAP 565 bool "Generate vmlinux.map file when linking" 566 depends on EXPERT 567 help 568 Selecting this option will pass "-Map=vmlinux.map" to ld 569 when linking vmlinux. That file can be useful for verifying 570 and debugging magic section games, and for seeing which 571 pieces of code get eliminated with 572 CONFIG_LD_DEAD_CODE_DATA_ELIMINATION. 573 574 config DEBUG_FORCE_WEAK_PER_CPU 575 bool "Force weak per-cpu definitions" 576 depends on DEBUG_KERNEL 577 help 578 s390 and alpha require percpu variables in modules to be 579 defined weak to work around addressing range issue which 580 puts the following two restrictions on percpu variable 581 definitions. 582 583 1. percpu symbols must be unique whether static or not 584 2. percpu variables can't be defined inside a function 585 586 To ensure that generic code follows the above rules, this 587 option forces all percpu variables to be defined as weak. 588 589 endmenu # "Compiler options" 590 591 menu "Generic Kernel Debugging Instruments" 592 593 config MAGIC_SYSRQ 594 bool "Magic SysRq key" 595 depends on !UML 596 help 597 If you say Y here, you will have some control over the system even 598 if the system crashes for example during kernel debugging (e.g., you 599 will be able to flush the buffer cache to disk, reboot the system 600 immediately or dump some status information). This is accomplished 601 by pressing various keys while holding SysRq (Alt+PrintScreen). It 602 also works on a serial console (on PC hardware at least), if you 603 send a BREAK and then within 5 seconds a command keypress. The 604 keys are documented in <file:Documentation/admin-guide/sysrq.rst>. 605 Don't say Y unless you really know what this hack does. 606 607 config MAGIC_SYSRQ_DEFAULT_ENABLE 608 hex "Enable magic SysRq key functions by default" 609 depends on MAGIC_SYSRQ 610 default 0x1 611 help 612 Specifies which SysRq key functions are enabled by default. 613 This may be set to 1 or 0 to enable or disable them all, or 614 to a bitmask as described in Documentation/admin-guide/sysrq.rst. 615 616 config MAGIC_SYSRQ_SERIAL 617 bool "Enable magic SysRq key over serial" 618 depends on MAGIC_SYSRQ 619 default y 620 help 621 Many embedded boards have a disconnected TTL level serial which can 622 generate some garbage that can lead to spurious false sysrq detects. 623 This option allows you to decide whether you want to enable the 624 magic SysRq key. 625 626 config MAGIC_SYSRQ_SERIAL_SEQUENCE 627 string "Char sequence that enables magic SysRq over serial" 628 depends on MAGIC_SYSRQ_SERIAL 629 default "" 630 help 631 Specifies a sequence of characters that can follow BREAK to enable 632 SysRq on a serial console. 633 634 If unsure, leave an empty string and the option will not be enabled. 635 636 config DEBUG_FS 637 bool "Debug Filesystem" 638 help 639 debugfs is a virtual file system that kernel developers use to put 640 debugging files into. Enable this option to be able to read and 641 write to these files. 642 643 For detailed documentation on the debugfs API, see 644 Documentation/filesystems/. 645 646 If unsure, say N. 647 648 choice 649 prompt "Debugfs default access" 650 depends on DEBUG_FS 651 default DEBUG_FS_ALLOW_ALL 652 help 653 This selects the default access restrictions for debugfs. 654 It can be overridden with kernel command line option 655 debugfs=[on,no-mount,off]. The restrictions apply for API access 656 and filesystem registration. 657 658 config DEBUG_FS_ALLOW_ALL 659 bool "Access normal" 660 help 661 No restrictions apply. Both API and filesystem registration 662 is on. This is the normal default operation. 663 664 config DEBUG_FS_DISALLOW_MOUNT 665 bool "Do not register debugfs as filesystem" 666 help 667 The API is open but filesystem is not loaded. Clients can still do 668 their work and read with debug tools that do not need 669 debugfs filesystem. 670 671 config DEBUG_FS_ALLOW_NONE 672 bool "No access" 673 help 674 Access is off. Clients get -PERM when trying to create nodes in 675 debugfs tree and debugfs is not registered as a filesystem. 676 Client can then back-off or continue without debugfs access. 677 678 endchoice 679 680 source "lib/Kconfig.kgdb" 681 source "lib/Kconfig.ubsan" 682 source "lib/Kconfig.kcsan" 683 684 endmenu 685 686 menu "Networking Debugging" 687 688 source "net/Kconfig.debug" 689 690 endmenu # "Networking Debugging" 691 692 menu "Memory Debugging" 693 694 source "mm/Kconfig.debug" 695 696 config DEBUG_OBJECTS 697 bool "Debug object operations" 698 depends on DEBUG_KERNEL 699 help 700 If you say Y here, additional code will be inserted into the 701 kernel to track the life time of various objects and validate 702 the operations on those objects. 703 704 config DEBUG_OBJECTS_SELFTEST 705 bool "Debug objects selftest" 706 depends on DEBUG_OBJECTS 707 help 708 This enables the selftest of the object debug code. 709 710 config DEBUG_OBJECTS_FREE 711 bool "Debug objects in freed memory" 712 depends on DEBUG_OBJECTS 713 help 714 This enables checks whether a k/v free operation frees an area 715 which contains an object which has not been deactivated 716 properly. This can make kmalloc/kfree-intensive workloads 717 much slower. 718 719 config DEBUG_OBJECTS_TIMERS 720 bool "Debug timer objects" 721 depends on DEBUG_OBJECTS 722 help 723 If you say Y here, additional code will be inserted into the 724 timer routines to track the life time of timer objects and 725 validate the timer operations. 726 727 config DEBUG_OBJECTS_WORK 728 bool "Debug work objects" 729 depends on DEBUG_OBJECTS 730 help 731 If you say Y here, additional code will be inserted into the 732 work queue routines to track the life time of work objects and 733 validate the work operations. 734 735 config DEBUG_OBJECTS_RCU_HEAD 736 bool "Debug RCU callbacks objects" 737 depends on DEBUG_OBJECTS 738 help 739 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 740 741 config DEBUG_OBJECTS_PERCPU_COUNTER 742 bool "Debug percpu counter objects" 743 depends on DEBUG_OBJECTS 744 help 745 If you say Y here, additional code will be inserted into the 746 percpu counter routines to track the life time of percpu counter 747 objects and validate the percpu counter operations. 748 749 config DEBUG_OBJECTS_ENABLE_DEFAULT 750 int "debug_objects bootup default value (0-1)" 751 range 0 1 752 default "1" 753 depends on DEBUG_OBJECTS 754 help 755 Debug objects boot parameter default value 756 757 config SHRINKER_DEBUG 758 bool "Enable shrinker debugging support" 759 depends on DEBUG_FS 760 help 761 Say Y to enable the shrinker debugfs interface which provides 762 visibility into the kernel memory shrinkers subsystem. 763 Disable it to avoid an extra memory footprint. 764 765 config DEBUG_STACK_USAGE 766 bool "Stack utilization instrumentation" 767 depends on DEBUG_KERNEL 768 help 769 Enables the display of the minimum amount of free stack which each 770 task has ever had available in the sysrq-T and sysrq-P debug output. 771 Also emits a message to dmesg when a process exits if that process 772 used more stack space than previously exiting processes. 773 774 This option will slow down process creation somewhat. 775 776 config SCHED_STACK_END_CHECK 777 bool "Detect stack corruption on calls to schedule()" 778 depends on DEBUG_KERNEL 779 default n 780 help 781 This option checks for a stack overrun on calls to schedule(). 782 If the stack end location is found to be over written always panic as 783 the content of the corrupted region can no longer be trusted. 784 This is to ensure no erroneous behaviour occurs which could result in 785 data corruption or a sporadic crash at a later stage once the region 786 is examined. The runtime overhead introduced is minimal. 787 788 config ARCH_HAS_DEBUG_VM_PGTABLE 789 bool 790 help 791 An architecture should select this when it can successfully 792 build and run DEBUG_VM_PGTABLE. 793 794 config DEBUG_VM_IRQSOFF 795 def_bool DEBUG_VM && !PREEMPT_RT 796 797 config DEBUG_VM 798 bool "Debug VM" 799 depends on DEBUG_KERNEL 800 help 801 Enable this to turn on extended checks in the virtual-memory system 802 that may impact performance. 803 804 If unsure, say N. 805 806 config DEBUG_VM_SHOOT_LAZIES 807 bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation" 808 depends on DEBUG_VM 809 depends on MMU_LAZY_TLB_SHOOTDOWN 810 help 811 Enable additional IPIs that ensure lazy tlb mm references are removed 812 before the mm is freed. 813 814 If unsure, say N. 815 816 config DEBUG_VM_MAPLE_TREE 817 bool "Debug VM maple trees" 818 depends on DEBUG_VM 819 select DEBUG_MAPLE_TREE 820 help 821 Enable VM maple tree debugging information and extra validations. 822 823 If unsure, say N. 824 825 config DEBUG_VM_RB 826 bool "Debug VM red-black trees" 827 depends on DEBUG_VM 828 help 829 Enable VM red-black tree debugging information and extra validations. 830 831 If unsure, say N. 832 833 config DEBUG_VM_PGFLAGS 834 bool "Debug page-flags operations" 835 depends on DEBUG_VM 836 help 837 Enables extra validation on page flags operations. 838 839 If unsure, say N. 840 841 config DEBUG_VM_PGTABLE 842 bool "Debug arch page table for semantics compliance" 843 depends on MMU 844 depends on ARCH_HAS_DEBUG_VM_PGTABLE 845 default y if DEBUG_VM 846 help 847 This option provides a debug method which can be used to test 848 architecture page table helper functions on various platforms in 849 verifying if they comply with expected generic MM semantics. This 850 will help architecture code in making sure that any changes or 851 new additions of these helpers still conform to expected 852 semantics of the generic MM. Platforms will have to opt in for 853 this through ARCH_HAS_DEBUG_VM_PGTABLE. 854 855 If unsure, say N. 856 857 config ARCH_HAS_DEBUG_VIRTUAL 858 bool 859 860 config DEBUG_VIRTUAL 861 bool "Debug VM translations" 862 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL 863 help 864 Enable some costly sanity checks in virtual to page code. This can 865 catch mistakes with virt_to_page() and friends. 866 867 If unsure, say N. 868 869 config DEBUG_NOMMU_REGIONS 870 bool "Debug the global anon/private NOMMU mapping region tree" 871 depends on DEBUG_KERNEL && !MMU 872 help 873 This option causes the global tree of anonymous and private mapping 874 regions to be regularly checked for invalid topology. 875 876 config DEBUG_MEMORY_INIT 877 bool "Debug memory initialisation" if EXPERT 878 default !EXPERT 879 help 880 Enable this for additional checks during memory initialisation. 881 The sanity checks verify aspects of the VM such as the memory model 882 and other information provided by the architecture. Verbose 883 information will be printed at KERN_DEBUG loglevel depending 884 on the mminit_loglevel= command-line option. 885 886 If unsure, say Y 887 888 config MEMORY_NOTIFIER_ERROR_INJECT 889 tristate "Memory hotplug notifier error injection module" 890 depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION 891 help 892 This option provides the ability to inject artificial errors to 893 memory hotplug notifier chain callbacks. It is controlled through 894 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 895 896 If the notifier call chain should be failed with some events 897 notified, write the error code to "actions/<notifier event>/error". 898 899 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 900 901 # cd /sys/kernel/debug/notifier-error-inject/memory 902 # echo -12 > actions/MEM_GOING_OFFLINE/error 903 # echo offline > /sys/devices/system/memory/memoryXXX/state 904 bash: echo: write error: Cannot allocate memory 905 906 To compile this code as a module, choose M here: the module will 907 be called memory-notifier-error-inject. 908 909 If unsure, say N. 910 911 config DEBUG_PER_CPU_MAPS 912 bool "Debug access to per_cpu maps" 913 depends on DEBUG_KERNEL 914 depends on SMP 915 help 916 Say Y to verify that the per_cpu map being accessed has 917 been set up. This adds a fair amount of code to kernel memory 918 and decreases performance. 919 920 Say N if unsure. 921 922 config DEBUG_KMAP_LOCAL 923 bool "Debug kmap_local temporary mappings" 924 depends on DEBUG_KERNEL && KMAP_LOCAL 925 help 926 This option enables additional error checking for the kmap_local 927 infrastructure. Disable for production use. 928 929 config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 930 bool 931 932 config DEBUG_KMAP_LOCAL_FORCE_MAP 933 bool "Enforce kmap_local temporary mappings" 934 depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 935 select KMAP_LOCAL 936 select DEBUG_KMAP_LOCAL 937 help 938 This option enforces temporary mappings through the kmap_local 939 mechanism for non-highmem pages and on non-highmem systems. 940 Disable this for production systems! 941 942 config DEBUG_HIGHMEM 943 bool "Highmem debugging" 944 depends on DEBUG_KERNEL && HIGHMEM 945 select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 946 select DEBUG_KMAP_LOCAL 947 help 948 This option enables additional error checking for high memory 949 systems. Disable for production systems. 950 951 config HAVE_DEBUG_STACKOVERFLOW 952 bool 953 954 config DEBUG_STACKOVERFLOW 955 bool "Check for stack overflows" 956 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 957 help 958 Say Y here if you want to check for overflows of kernel, IRQ 959 and exception stacks (if your architecture uses them). This 960 option will show detailed messages if free stack space drops 961 below a certain limit. 962 963 These kinds of bugs usually occur when call-chains in the 964 kernel get too deep, especially when interrupts are 965 involved. 966 967 Use this in cases where you see apparently random memory 968 corruption, especially if it appears in 'struct thread_info' 969 970 If in doubt, say "N". 971 972 source "lib/Kconfig.kasan" 973 source "lib/Kconfig.kfence" 974 source "lib/Kconfig.kmsan" 975 976 endmenu # "Memory Debugging" 977 978 config DEBUG_SHIRQ 979 bool "Debug shared IRQ handlers" 980 depends on DEBUG_KERNEL 981 help 982 Enable this to generate a spurious interrupt just before a shared 983 interrupt handler is deregistered (generating one when registering 984 is currently disabled). Drivers need to handle this correctly. Some 985 don't and need to be caught. 986 987 menu "Debug Oops, Lockups and Hangs" 988 989 config PANIC_ON_OOPS 990 bool "Panic on Oops" 991 help 992 Say Y here to enable the kernel to panic when it oopses. This 993 has the same effect as setting oops=panic on the kernel command 994 line. 995 996 This feature is useful to ensure that the kernel does not do 997 anything erroneous after an oops which could result in data 998 corruption or other issues. 999 1000 Say N if unsure. 1001 1002 config PANIC_ON_OOPS_VALUE 1003 int 1004 range 0 1 1005 default 0 if !PANIC_ON_OOPS 1006 default 1 if PANIC_ON_OOPS 1007 1008 config PANIC_TIMEOUT 1009 int "panic timeout" 1010 default 0 1011 help 1012 Set the timeout value (in seconds) until a reboot occurs when 1013 the kernel panics. If n = 0, then we wait forever. A timeout 1014 value n > 0 will wait n seconds before rebooting, while a timeout 1015 value n < 0 will reboot immediately. 1016 1017 config LOCKUP_DETECTOR 1018 bool 1019 1020 config SOFTLOCKUP_DETECTOR 1021 bool "Detect Soft Lockups" 1022 depends on DEBUG_KERNEL && !S390 1023 select LOCKUP_DETECTOR 1024 help 1025 Say Y here to enable the kernel to act as a watchdog to detect 1026 soft lockups. 1027 1028 Softlockups are bugs that cause the kernel to loop in kernel 1029 mode for more than 20 seconds, without giving other tasks a 1030 chance to run. The current stack trace is displayed upon 1031 detection and the system will stay locked up. 1032 1033 config BOOTPARAM_SOFTLOCKUP_PANIC 1034 bool "Panic (Reboot) On Soft Lockups" 1035 depends on SOFTLOCKUP_DETECTOR 1036 help 1037 Say Y here to enable the kernel to panic on "soft lockups", 1038 which are bugs that cause the kernel to loop in kernel 1039 mode for more than 20 seconds (configurable using the watchdog_thresh 1040 sysctl), without giving other tasks a chance to run. 1041 1042 The panic can be used in combination with panic_timeout, 1043 to cause the system to reboot automatically after a 1044 lockup has been detected. This feature is useful for 1045 high-availability systems that have uptime guarantees and 1046 where a lockup must be resolved ASAP. 1047 1048 Say N if unsure. 1049 1050 config HAVE_HARDLOCKUP_DETECTOR_BUDDY 1051 bool 1052 depends on SMP 1053 default y 1054 1055 # 1056 # Global switch whether to build a hardlockup detector at all. It is available 1057 # only when the architecture supports at least one implementation. There are 1058 # two exceptions. The hardlockup detector is never enabled on: 1059 # 1060 # s390: it reported many false positives there 1061 # 1062 # sparc64: has a custom implementation which is not using the common 1063 # hardlockup command line options and sysctl interface. 1064 # 1065 config HARDLOCKUP_DETECTOR 1066 bool "Detect Hard Lockups" 1067 depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64 1068 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH 1069 imply HARDLOCKUP_DETECTOR_PERF 1070 imply HARDLOCKUP_DETECTOR_BUDDY 1071 imply HARDLOCKUP_DETECTOR_ARCH 1072 select LOCKUP_DETECTOR 1073 1074 help 1075 Say Y here to enable the kernel to act as a watchdog to detect 1076 hard lockups. 1077 1078 Hardlockups are bugs that cause the CPU to loop in kernel mode 1079 for more than 10 seconds, without letting other interrupts have a 1080 chance to run. The current stack trace is displayed upon detection 1081 and the system will stay locked up. 1082 1083 # 1084 # Note that arch-specific variants are always preferred. 1085 # 1086 config HARDLOCKUP_DETECTOR_PREFER_BUDDY 1087 bool "Prefer the buddy CPU hardlockup detector" 1088 depends on HARDLOCKUP_DETECTOR 1089 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY 1090 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1091 help 1092 Say Y here to prefer the buddy hardlockup detector over the perf one. 1093 1094 With the buddy detector, each CPU uses its softlockup hrtimer 1095 to check that the next CPU is processing hrtimer interrupts by 1096 verifying that a counter is increasing. 1097 1098 This hardlockup detector is useful on systems that don't have 1099 an arch-specific hardlockup detector or if resources needed 1100 for the hardlockup detector are better used for other things. 1101 1102 config HARDLOCKUP_DETECTOR_PERF 1103 bool 1104 depends on HARDLOCKUP_DETECTOR 1105 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY 1106 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1107 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1108 1109 config HARDLOCKUP_DETECTOR_BUDDY 1110 bool 1111 depends on HARDLOCKUP_DETECTOR 1112 depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY 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 1117 config HARDLOCKUP_DETECTOR_ARCH 1118 bool 1119 depends on HARDLOCKUP_DETECTOR 1120 depends on HAVE_HARDLOCKUP_DETECTOR_ARCH 1121 help 1122 The arch-specific implementation of the hardlockup detector will 1123 be used. 1124 1125 # 1126 # Both the "perf" and "buddy" hardlockup detectors count hrtimer 1127 # interrupts. This config enables functions managing this common code. 1128 # 1129 config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1130 bool 1131 select SOFTLOCKUP_DETECTOR 1132 1133 # 1134 # Enables a timestamp based low pass filter to compensate for perf based 1135 # hard lockup detection which runs too fast due to turbo modes. 1136 # 1137 config HARDLOCKUP_CHECK_TIMESTAMP 1138 bool 1139 1140 config BOOTPARAM_HARDLOCKUP_PANIC 1141 bool "Panic (Reboot) On Hard Lockups" 1142 depends on HARDLOCKUP_DETECTOR 1143 help 1144 Say Y here to enable the kernel to panic on "hard lockups", 1145 which are bugs that cause the kernel to loop in kernel 1146 mode with interrupts disabled for more than 10 seconds (configurable 1147 using the watchdog_thresh sysctl). 1148 1149 Say N if unsure. 1150 1151 config DETECT_HUNG_TASK 1152 bool "Detect Hung Tasks" 1153 depends on DEBUG_KERNEL 1154 default SOFTLOCKUP_DETECTOR 1155 help 1156 Say Y here to enable the kernel to detect "hung tasks", 1157 which are bugs that cause the task to be stuck in 1158 uninterruptible "D" state indefinitely. 1159 1160 When a hung task is detected, the kernel will print the 1161 current stack trace (which you should report), but the 1162 task will stay in uninterruptible state. If lockdep is 1163 enabled then all held locks will also be reported. This 1164 feature has negligible overhead. 1165 1166 config DEFAULT_HUNG_TASK_TIMEOUT 1167 int "Default timeout for hung task detection (in seconds)" 1168 depends on DETECT_HUNG_TASK 1169 default 120 1170 help 1171 This option controls the default timeout (in seconds) used 1172 to determine when a task has become non-responsive and should 1173 be considered hung. 1174 1175 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 1176 sysctl or by writing a value to 1177 /proc/sys/kernel/hung_task_timeout_secs. 1178 1179 A timeout of 0 disables the check. The default is two minutes. 1180 Keeping the default should be fine in most cases. 1181 1182 config BOOTPARAM_HUNG_TASK_PANIC 1183 bool "Panic (Reboot) On Hung Tasks" 1184 depends on DETECT_HUNG_TASK 1185 help 1186 Say Y here to enable the kernel to panic on "hung tasks", 1187 which are bugs that cause the kernel to leave a task stuck 1188 in uninterruptible "D" state. 1189 1190 The panic can be used in combination with panic_timeout, 1191 to cause the system to reboot automatically after a 1192 hung task has been detected. This feature is useful for 1193 high-availability systems that have uptime guarantees and 1194 where a hung tasks must be resolved ASAP. 1195 1196 Say N if unsure. 1197 1198 config WQ_WATCHDOG 1199 bool "Detect Workqueue Stalls" 1200 depends on DEBUG_KERNEL 1201 help 1202 Say Y here to enable stall detection on workqueues. If a 1203 worker pool doesn't make forward progress on a pending work 1204 item for over a given amount of time, 30s by default, a 1205 warning message is printed along with dump of workqueue 1206 state. This can be configured through kernel parameter 1207 "workqueue.watchdog_thresh" and its sysfs counterpart. 1208 1209 config WQ_CPU_INTENSIVE_REPORT 1210 bool "Report per-cpu work items which hog CPU for too long" 1211 depends on DEBUG_KERNEL 1212 help 1213 Say Y here to enable reporting of concurrency-managed per-cpu work 1214 items that hog CPUs for longer than 1215 workqueue.cpu_intensive_thresh_us. Workqueue automatically 1216 detects and excludes them from concurrency management to prevent 1217 them from stalling other per-cpu work items. Occassional 1218 triggering may not necessarily indicate a problem. Repeated 1219 triggering likely indicates that the work item should be switched 1220 to use an unbound workqueue. 1221 1222 config TEST_LOCKUP 1223 tristate "Test module to generate lockups" 1224 depends on m 1225 help 1226 This builds the "test_lockup" module that helps to make sure 1227 that watchdogs and lockup detectors are working properly. 1228 1229 Depending on module parameters it could emulate soft or hard 1230 lockup, "hung task", or locking arbitrary lock for a long time. 1231 Also it could generate series of lockups with cooling-down periods. 1232 1233 If unsure, say N. 1234 1235 endmenu # "Debug lockups and hangs" 1236 1237 menu "Scheduler Debugging" 1238 1239 config SCHED_DEBUG 1240 bool "Collect scheduler debugging info" 1241 depends on DEBUG_KERNEL && DEBUG_FS 1242 default y 1243 help 1244 If you say Y here, the /sys/kernel/debug/sched file will be provided 1245 that can help debug the scheduler. The runtime overhead of this 1246 option is minimal. 1247 1248 config SCHED_INFO 1249 bool 1250 default n 1251 1252 config SCHEDSTATS 1253 bool "Collect scheduler statistics" 1254 depends on DEBUG_KERNEL && PROC_FS 1255 select SCHED_INFO 1256 help 1257 If you say Y here, additional code will be inserted into the 1258 scheduler and related routines to collect statistics about 1259 scheduler behavior and provide them in /proc/schedstat. These 1260 stats may be useful for both tuning and debugging the scheduler 1261 If you aren't debugging the scheduler or trying to tune a specific 1262 application, you can say N to avoid the very slight overhead 1263 this adds. 1264 1265 endmenu 1266 1267 config DEBUG_TIMEKEEPING 1268 bool "Enable extra timekeeping sanity checking" 1269 help 1270 This option will enable additional timekeeping sanity checks 1271 which may be helpful when diagnosing issues where timekeeping 1272 problems are suspected. 1273 1274 This may include checks in the timekeeping hotpaths, so this 1275 option may have a (very small) performance impact to some 1276 workloads. 1277 1278 If unsure, say N. 1279 1280 config DEBUG_PREEMPT 1281 bool "Debug preemptible kernel" 1282 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1283 help 1284 If you say Y here then the kernel will use a debug variant of the 1285 commonly used smp_processor_id() function and will print warnings 1286 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1287 will detect preemption count underflows. 1288 1289 This option has potential to introduce high runtime overhead, 1290 depending on workload as it triggers debugging routines for each 1291 this_cpu operation. It should only be used for debugging purposes. 1292 1293 menu "Lock Debugging (spinlocks, mutexes, etc...)" 1294 1295 config LOCK_DEBUGGING_SUPPORT 1296 bool 1297 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1298 default y 1299 1300 config PROVE_LOCKING 1301 bool "Lock debugging: prove locking correctness" 1302 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1303 select LOCKDEP 1304 select DEBUG_SPINLOCK 1305 select DEBUG_MUTEXES if !PREEMPT_RT 1306 select DEBUG_RT_MUTEXES if RT_MUTEXES 1307 select DEBUG_RWSEMS if !PREEMPT_RT 1308 select DEBUG_WW_MUTEX_SLOWPATH 1309 select DEBUG_LOCK_ALLOC 1310 select PREEMPT_COUNT if !ARCH_NO_PREEMPT 1311 select TRACE_IRQFLAGS 1312 default n 1313 help 1314 This feature enables the kernel to prove that all locking 1315 that occurs in the kernel runtime is mathematically 1316 correct: that under no circumstance could an arbitrary (and 1317 not yet triggered) combination of observed locking 1318 sequences (on an arbitrary number of CPUs, running an 1319 arbitrary number of tasks and interrupt contexts) cause a 1320 deadlock. 1321 1322 In short, this feature enables the kernel to report locking 1323 related deadlocks before they actually occur. 1324 1325 The proof does not depend on how hard and complex a 1326 deadlock scenario would be to trigger: how many 1327 participant CPUs, tasks and irq-contexts would be needed 1328 for it to trigger. The proof also does not depend on 1329 timing: if a race and a resulting deadlock is possible 1330 theoretically (no matter how unlikely the race scenario 1331 is), it will be proven so and will immediately be 1332 reported by the kernel (once the event is observed that 1333 makes the deadlock theoretically possible). 1334 1335 If a deadlock is impossible (i.e. the locking rules, as 1336 observed by the kernel, are mathematically correct), the 1337 kernel reports nothing. 1338 1339 NOTE: this feature can also be enabled for rwlocks, mutexes 1340 and rwsems - in which case all dependencies between these 1341 different locking variants are observed and mapped too, and 1342 the proof of observed correctness is also maintained for an 1343 arbitrary combination of these separate locking variants. 1344 1345 For more details, see Documentation/locking/lockdep-design.rst. 1346 1347 config PROVE_RAW_LOCK_NESTING 1348 bool "Enable raw_spinlock - spinlock nesting checks" 1349 depends on PROVE_LOCKING 1350 default n 1351 help 1352 Enable the raw_spinlock vs. spinlock nesting checks which ensure 1353 that the lock nesting rules for PREEMPT_RT enabled kernels are 1354 not violated. 1355 1356 NOTE: There are known nesting problems. So if you enable this 1357 option expect lockdep splats until these problems have been fully 1358 addressed which is work in progress. This config switch allows to 1359 identify and analyze these problems. It will be removed and the 1360 check permanently enabled once the main issues have been fixed. 1361 1362 If unsure, select N. 1363 1364 config LOCK_STAT 1365 bool "Lock usage statistics" 1366 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1367 select LOCKDEP 1368 select DEBUG_SPINLOCK 1369 select DEBUG_MUTEXES if !PREEMPT_RT 1370 select DEBUG_RT_MUTEXES if RT_MUTEXES 1371 select DEBUG_LOCK_ALLOC 1372 default n 1373 help 1374 This feature enables tracking lock contention points 1375 1376 For more details, see Documentation/locking/lockstat.rst 1377 1378 This also enables lock events required by "perf lock", 1379 subcommand of perf. 1380 If you want to use "perf lock", you also need to turn on 1381 CONFIG_EVENT_TRACING. 1382 1383 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1384 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1385 1386 config DEBUG_RT_MUTEXES 1387 bool "RT Mutex debugging, deadlock detection" 1388 depends on DEBUG_KERNEL && RT_MUTEXES 1389 help 1390 This allows rt mutex semantics violations and rt mutex related 1391 deadlocks (lockups) to be detected and reported automatically. 1392 1393 config DEBUG_SPINLOCK 1394 bool "Spinlock and rw-lock debugging: basic checks" 1395 depends on DEBUG_KERNEL 1396 select UNINLINE_SPIN_UNLOCK 1397 help 1398 Say Y here and build SMP to catch missing spinlock initialization 1399 and certain other kinds of spinlock errors commonly made. This is 1400 best used in conjunction with the NMI watchdog so that spinlock 1401 deadlocks are also debuggable. 1402 1403 config DEBUG_MUTEXES 1404 bool "Mutex debugging: basic checks" 1405 depends on DEBUG_KERNEL && !PREEMPT_RT 1406 help 1407 This feature allows mutex semantics violations to be detected and 1408 reported. 1409 1410 config DEBUG_WW_MUTEX_SLOWPATH 1411 bool "Wait/wound mutex debugging: Slowpath testing" 1412 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1413 select DEBUG_LOCK_ALLOC 1414 select DEBUG_SPINLOCK 1415 select DEBUG_MUTEXES if !PREEMPT_RT 1416 select DEBUG_RT_MUTEXES if PREEMPT_RT 1417 help 1418 This feature enables slowpath testing for w/w mutex users by 1419 injecting additional -EDEADLK wound/backoff cases. Together with 1420 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1421 will test all possible w/w mutex interface abuse with the 1422 exception of simply not acquiring all the required locks. 1423 Note that this feature can introduce significant overhead, so 1424 it really should not be enabled in a production or distro kernel, 1425 even a debug kernel. If you are a driver writer, enable it. If 1426 you are a distro, do not. 1427 1428 config DEBUG_RWSEMS 1429 bool "RW Semaphore debugging: basic checks" 1430 depends on DEBUG_KERNEL && !PREEMPT_RT 1431 help 1432 This debugging feature allows mismatched rw semaphore locks 1433 and unlocks to be detected and reported. 1434 1435 config DEBUG_LOCK_ALLOC 1436 bool "Lock debugging: detect incorrect freeing of live locks" 1437 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1438 select DEBUG_SPINLOCK 1439 select DEBUG_MUTEXES if !PREEMPT_RT 1440 select DEBUG_RT_MUTEXES if RT_MUTEXES 1441 select LOCKDEP 1442 help 1443 This feature will check whether any held lock (spinlock, rwlock, 1444 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1445 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1446 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1447 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1448 held during task exit. 1449 1450 config LOCKDEP 1451 bool 1452 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1453 select STACKTRACE 1454 select KALLSYMS 1455 select KALLSYMS_ALL 1456 1457 config LOCKDEP_SMALL 1458 bool 1459 1460 config LOCKDEP_BITS 1461 int "Bitsize for MAX_LOCKDEP_ENTRIES" 1462 depends on LOCKDEP && !LOCKDEP_SMALL 1463 range 10 30 1464 default 15 1465 help 1466 Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message. 1467 1468 config LOCKDEP_CHAINS_BITS 1469 int "Bitsize for MAX_LOCKDEP_CHAINS" 1470 depends on LOCKDEP && !LOCKDEP_SMALL 1471 range 10 30 1472 default 16 1473 help 1474 Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message. 1475 1476 config LOCKDEP_STACK_TRACE_BITS 1477 int "Bitsize for MAX_STACK_TRACE_ENTRIES" 1478 depends on LOCKDEP && !LOCKDEP_SMALL 1479 range 10 30 1480 default 19 1481 help 1482 Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message. 1483 1484 config LOCKDEP_STACK_TRACE_HASH_BITS 1485 int "Bitsize for STACK_TRACE_HASH_SIZE" 1486 depends on LOCKDEP && !LOCKDEP_SMALL 1487 range 10 30 1488 default 14 1489 help 1490 Try increasing this value if you need large STACK_TRACE_HASH_SIZE. 1491 1492 config LOCKDEP_CIRCULAR_QUEUE_BITS 1493 int "Bitsize for elements in circular_queue struct" 1494 depends on LOCKDEP 1495 range 10 30 1496 default 12 1497 help 1498 Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure. 1499 1500 config DEBUG_LOCKDEP 1501 bool "Lock dependency engine debugging" 1502 depends on DEBUG_KERNEL && LOCKDEP 1503 select DEBUG_IRQFLAGS 1504 help 1505 If you say Y here, the lock dependency engine will do 1506 additional runtime checks to debug itself, at the price 1507 of more runtime overhead. 1508 1509 config DEBUG_ATOMIC_SLEEP 1510 bool "Sleep inside atomic section checking" 1511 select PREEMPT_COUNT 1512 depends on DEBUG_KERNEL 1513 depends on !ARCH_NO_PREEMPT 1514 help 1515 If you say Y here, various routines which may sleep will become very 1516 noisy if they are called inside atomic sections: when a spinlock is 1517 held, inside an rcu read side critical section, inside preempt disabled 1518 sections, inside an interrupt, etc... 1519 1520 config DEBUG_LOCKING_API_SELFTESTS 1521 bool "Locking API boot-time self-tests" 1522 depends on DEBUG_KERNEL 1523 help 1524 Say Y here if you want the kernel to run a short self-test during 1525 bootup. The self-test checks whether common types of locking bugs 1526 are detected by debugging mechanisms or not. (if you disable 1527 lock debugging then those bugs won't be detected of course.) 1528 The following locking APIs are covered: spinlocks, rwlocks, 1529 mutexes and rwsems. 1530 1531 config LOCK_TORTURE_TEST 1532 tristate "torture tests for locking" 1533 depends on DEBUG_KERNEL 1534 select TORTURE_TEST 1535 help 1536 This option provides a kernel module that runs torture tests 1537 on kernel locking primitives. The kernel module may be built 1538 after the fact on the running kernel to be tested, if desired. 1539 1540 Say Y here if you want kernel locking-primitive torture tests 1541 to be built into the kernel. 1542 Say M if you want these torture tests to build as a module. 1543 Say N if you are unsure. 1544 1545 config WW_MUTEX_SELFTEST 1546 tristate "Wait/wound mutex selftests" 1547 help 1548 This option provides a kernel module that runs tests on the 1549 on the struct ww_mutex locking API. 1550 1551 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1552 with this test harness. 1553 1554 Say M if you want these self tests to build as a module. 1555 Say N if you are unsure. 1556 1557 config SCF_TORTURE_TEST 1558 tristate "torture tests for smp_call_function*()" 1559 depends on DEBUG_KERNEL 1560 select TORTURE_TEST 1561 help 1562 This option provides a kernel module that runs torture tests 1563 on the smp_call_function() family of primitives. The kernel 1564 module may be built after the fact on the running kernel to 1565 be tested, if desired. 1566 1567 config CSD_LOCK_WAIT_DEBUG 1568 bool "Debugging for csd_lock_wait(), called from smp_call_function*()" 1569 depends on DEBUG_KERNEL 1570 depends on 64BIT 1571 default n 1572 help 1573 This option enables debug prints when CPUs are slow to respond 1574 to the smp_call_function*() IPI wrappers. These debug prints 1575 include the IPI handler function currently executing (if any) 1576 and relevant stack traces. 1577 1578 config CSD_LOCK_WAIT_DEBUG_DEFAULT 1579 bool "Default csd_lock_wait() debugging on at boot time" 1580 depends on CSD_LOCK_WAIT_DEBUG 1581 depends on 64BIT 1582 default n 1583 help 1584 This option causes the csdlock_debug= kernel boot parameter to 1585 default to 1 (basic debugging) instead of 0 (no debugging). 1586 1587 endmenu # lock debugging 1588 1589 config TRACE_IRQFLAGS 1590 depends on TRACE_IRQFLAGS_SUPPORT 1591 bool 1592 help 1593 Enables hooks to interrupt enabling and disabling for 1594 either tracing or lock debugging. 1595 1596 config TRACE_IRQFLAGS_NMI 1597 def_bool y 1598 depends on TRACE_IRQFLAGS 1599 depends on TRACE_IRQFLAGS_NMI_SUPPORT 1600 1601 config NMI_CHECK_CPU 1602 bool "Debugging for CPUs failing to respond to backtrace requests" 1603 depends on DEBUG_KERNEL 1604 depends on X86 1605 default n 1606 help 1607 Enables debug prints when a CPU fails to respond to a given 1608 backtrace NMI. These prints provide some reasons why a CPU 1609 might legitimately be failing to respond, for example, if it 1610 is offline of if ignore_nmis is set. 1611 1612 config DEBUG_IRQFLAGS 1613 bool "Debug IRQ flag manipulation" 1614 help 1615 Enables checks for potentially unsafe enabling or disabling of 1616 interrupts, such as calling raw_local_irq_restore() when interrupts 1617 are enabled. 1618 1619 config STACKTRACE 1620 bool "Stack backtrace support" 1621 depends on STACKTRACE_SUPPORT 1622 help 1623 This option causes the kernel to create a /proc/pid/stack for 1624 every process, showing its current stack trace. 1625 It is also used by various kernel debugging features that require 1626 stack trace generation. 1627 1628 config WARN_ALL_UNSEEDED_RANDOM 1629 bool "Warn for all uses of unseeded randomness" 1630 default n 1631 help 1632 Some parts of the kernel contain bugs relating to their use of 1633 cryptographically secure random numbers before it's actually possible 1634 to generate those numbers securely. This setting ensures that these 1635 flaws don't go unnoticed, by enabling a message, should this ever 1636 occur. This will allow people with obscure setups to know when things 1637 are going wrong, so that they might contact developers about fixing 1638 it. 1639 1640 Unfortunately, on some models of some architectures getting 1641 a fully seeded CRNG is extremely difficult, and so this can 1642 result in dmesg getting spammed for a surprisingly long 1643 time. This is really bad from a security perspective, and 1644 so architecture maintainers really need to do what they can 1645 to get the CRNG seeded sooner after the system is booted. 1646 However, since users cannot do anything actionable to 1647 address this, by default this option is disabled. 1648 1649 Say Y here if you want to receive warnings for all uses of 1650 unseeded randomness. This will be of use primarily for 1651 those developers interested in improving the security of 1652 Linux kernels running on their architecture (or 1653 subarchitecture). 1654 1655 config DEBUG_KOBJECT 1656 bool "kobject debugging" 1657 depends on DEBUG_KERNEL 1658 help 1659 If you say Y here, some extra kobject debugging messages will be sent 1660 to the syslog. 1661 1662 config DEBUG_KOBJECT_RELEASE 1663 bool "kobject release debugging" 1664 depends on DEBUG_OBJECTS_TIMERS 1665 help 1666 kobjects are reference counted objects. This means that their 1667 last reference count put is not predictable, and the kobject can 1668 live on past the point at which a driver decides to drop its 1669 initial reference to the kobject gained on allocation. An 1670 example of this would be a struct device which has just been 1671 unregistered. 1672 1673 However, some buggy drivers assume that after such an operation, 1674 the memory backing the kobject can be immediately freed. This 1675 goes completely against the principles of a refcounted object. 1676 1677 If you say Y here, the kernel will delay the release of kobjects 1678 on the last reference count to improve the visibility of this 1679 kind of kobject release bug. 1680 1681 config HAVE_DEBUG_BUGVERBOSE 1682 bool 1683 1684 menu "Debug kernel data structures" 1685 1686 config DEBUG_LIST 1687 bool "Debug linked list manipulation" 1688 depends on DEBUG_KERNEL 1689 select LIST_HARDENED 1690 help 1691 Enable this to turn on extended checks in the linked-list walking 1692 routines. 1693 1694 This option trades better quality error reports for performance, and 1695 is more suitable for kernel debugging. If you care about performance, 1696 you should only enable CONFIG_LIST_HARDENED instead. 1697 1698 If unsure, say N. 1699 1700 config DEBUG_PLIST 1701 bool "Debug priority linked list manipulation" 1702 depends on DEBUG_KERNEL 1703 help 1704 Enable this to turn on extended checks in the priority-ordered 1705 linked-list (plist) walking routines. This checks the entire 1706 list multiple times during each manipulation. 1707 1708 If unsure, say N. 1709 1710 config DEBUG_SG 1711 bool "Debug SG table operations" 1712 depends on DEBUG_KERNEL 1713 help 1714 Enable this to turn on checks on scatter-gather tables. This can 1715 help find problems with drivers that do not properly initialize 1716 their sg tables. 1717 1718 If unsure, say N. 1719 1720 config DEBUG_NOTIFIERS 1721 bool "Debug notifier call chains" 1722 depends on DEBUG_KERNEL 1723 help 1724 Enable this to turn on sanity checking for notifier call chains. 1725 This is most useful for kernel developers to make sure that 1726 modules properly unregister themselves from notifier chains. 1727 This is a relatively cheap check but if you care about maximum 1728 performance, say N. 1729 1730 config DEBUG_CLOSURES 1731 bool "Debug closures (bcache async widgits)" 1732 depends on CLOSURES 1733 select DEBUG_FS 1734 help 1735 Keeps all active closures in a linked list and provides a debugfs 1736 interface to list them, which makes it possible to see asynchronous 1737 operations that get stuck. 1738 1739 config DEBUG_MAPLE_TREE 1740 bool "Debug maple trees" 1741 depends on DEBUG_KERNEL 1742 help 1743 Enable maple tree debugging information and extra validations. 1744 1745 If unsure, say N. 1746 1747 endmenu 1748 1749 source "kernel/rcu/Kconfig.debug" 1750 1751 config DEBUG_WQ_FORCE_RR_CPU 1752 bool "Force round-robin CPU selection for unbound work items" 1753 depends on DEBUG_KERNEL 1754 default n 1755 help 1756 Workqueue used to implicitly guarantee that work items queued 1757 without explicit CPU specified are put on the local CPU. This 1758 guarantee is no longer true and while local CPU is still 1759 preferred work items may be put on foreign CPUs. Kernel 1760 parameter "workqueue.debug_force_rr_cpu" is added to force 1761 round-robin CPU selection to flush out usages which depend on the 1762 now broken guarantee. This config option enables the debug 1763 feature by default. When enabled, memory and cache locality will 1764 be impacted. 1765 1766 config CPU_HOTPLUG_STATE_CONTROL 1767 bool "Enable CPU hotplug state control" 1768 depends on DEBUG_KERNEL 1769 depends on HOTPLUG_CPU 1770 default n 1771 help 1772 Allows to write steps between "offline" and "online" to the CPUs 1773 sysfs target file so states can be stepped granular. This is a debug 1774 option for now as the hotplug machinery cannot be stopped and 1775 restarted at arbitrary points yet. 1776 1777 Say N if your are unsure. 1778 1779 config LATENCYTOP 1780 bool "Latency measuring infrastructure" 1781 depends on DEBUG_KERNEL 1782 depends on STACKTRACE_SUPPORT 1783 depends on PROC_FS 1784 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 1785 select KALLSYMS 1786 select KALLSYMS_ALL 1787 select STACKTRACE 1788 select SCHEDSTATS 1789 help 1790 Enable this option if you want to use the LatencyTOP tool 1791 to find out which userspace is blocking on what kernel operations. 1792 1793 config DEBUG_CGROUP_REF 1794 bool "Disable inlining of cgroup css reference count functions" 1795 depends on DEBUG_KERNEL 1796 depends on CGROUPS 1797 depends on KPROBES 1798 default n 1799 help 1800 Force cgroup css reference count functions to not be inlined so 1801 that they can be kprobed for debugging. 1802 1803 source "kernel/trace/Kconfig" 1804 1805 config PROVIDE_OHCI1394_DMA_INIT 1806 bool "Remote debugging over FireWire early on boot" 1807 depends on PCI && X86 1808 help 1809 If you want to debug problems which hang or crash the kernel early 1810 on boot and the crashing machine has a FireWire port, you can use 1811 this feature to remotely access the memory of the crashed machine 1812 over FireWire. This employs remote DMA as part of the OHCI1394 1813 specification which is now the standard for FireWire controllers. 1814 1815 With remote DMA, you can monitor the printk buffer remotely using 1816 firescope and access all memory below 4GB using fireproxy from gdb. 1817 Even controlling a kernel debugger is possible using remote DMA. 1818 1819 Usage: 1820 1821 If ohci1394_dma=early is used as boot parameter, it will initialize 1822 all OHCI1394 controllers which are found in the PCI config space. 1823 1824 As all changes to the FireWire bus such as enabling and disabling 1825 devices cause a bus reset and thereby disable remote DMA for all 1826 devices, be sure to have the cable plugged and FireWire enabled on 1827 the debugging host before booting the debug target for debugging. 1828 1829 This code (~1k) is freed after boot. By then, the firewire stack 1830 in charge of the OHCI-1394 controllers should be used instead. 1831 1832 See Documentation/core-api/debugging-via-ohci1394.rst for more information. 1833 1834 source "samples/Kconfig" 1835 1836 config ARCH_HAS_DEVMEM_IS_ALLOWED 1837 bool 1838 1839 config STRICT_DEVMEM 1840 bool "Filter access to /dev/mem" 1841 depends on MMU && DEVMEM 1842 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED 1843 default y if PPC || X86 || ARM64 1844 help 1845 If this option is disabled, you allow userspace (root) access to all 1846 of memory, including kernel and userspace memory. Accidental 1847 access to this is obviously disastrous, but specific access can 1848 be used by people debugging the kernel. Note that with PAT support 1849 enabled, even in this case there are restrictions on /dev/mem 1850 use due to the cache aliasing requirements. 1851 1852 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 1853 file only allows userspace access to PCI space and the BIOS code and 1854 data regions. This is sufficient for dosemu and X and all common 1855 users of /dev/mem. 1856 1857 If in doubt, say Y. 1858 1859 config IO_STRICT_DEVMEM 1860 bool "Filter I/O access to /dev/mem" 1861 depends on STRICT_DEVMEM 1862 help 1863 If this option is disabled, you allow userspace (root) access to all 1864 io-memory regardless of whether a driver is actively using that 1865 range. Accidental access to this is obviously disastrous, but 1866 specific access can be used by people debugging kernel drivers. 1867 1868 If this option is switched on, the /dev/mem file only allows 1869 userspace access to *idle* io-memory ranges (see /proc/iomem) This 1870 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 1871 if the driver using a given range cannot be disabled. 1872 1873 If in doubt, say Y. 1874 1875 menu "$(SRCARCH) Debugging" 1876 1877 source "arch/$(SRCARCH)/Kconfig.debug" 1878 1879 endmenu 1880 1881 menu "Kernel Testing and Coverage" 1882 1883 source "lib/kunit/Kconfig" 1884 1885 config NOTIFIER_ERROR_INJECTION 1886 tristate "Notifier error injection" 1887 depends on DEBUG_KERNEL 1888 select DEBUG_FS 1889 help 1890 This option provides the ability to inject artificial errors to 1891 specified notifier chain callbacks. It is useful to test the error 1892 handling of notifier call chain failures. 1893 1894 Say N if unsure. 1895 1896 config PM_NOTIFIER_ERROR_INJECT 1897 tristate "PM notifier error injection module" 1898 depends on PM && NOTIFIER_ERROR_INJECTION 1899 default m if PM_DEBUG 1900 help 1901 This option provides the ability to inject artificial errors to 1902 PM notifier chain callbacks. It is controlled through debugfs 1903 interface /sys/kernel/debug/notifier-error-inject/pm 1904 1905 If the notifier call chain should be failed with some events 1906 notified, write the error code to "actions/<notifier event>/error". 1907 1908 Example: Inject PM suspend error (-12 = -ENOMEM) 1909 1910 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1911 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1912 # echo mem > /sys/power/state 1913 bash: echo: write error: Cannot allocate memory 1914 1915 To compile this code as a module, choose M here: the module will 1916 be called pm-notifier-error-inject. 1917 1918 If unsure, say N. 1919 1920 config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1921 tristate "OF reconfig notifier error injection module" 1922 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1923 help 1924 This option provides the ability to inject artificial errors to 1925 OF reconfig notifier chain callbacks. It is controlled 1926 through debugfs interface under 1927 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1928 1929 If the notifier call chain should be failed with some events 1930 notified, write the error code to "actions/<notifier event>/error". 1931 1932 To compile this code as a module, choose M here: the module will 1933 be called of-reconfig-notifier-error-inject. 1934 1935 If unsure, say N. 1936 1937 config NETDEV_NOTIFIER_ERROR_INJECT 1938 tristate "Netdev notifier error injection module" 1939 depends on NET && NOTIFIER_ERROR_INJECTION 1940 help 1941 This option provides the ability to inject artificial errors to 1942 netdevice notifier chain callbacks. It is controlled through debugfs 1943 interface /sys/kernel/debug/notifier-error-inject/netdev 1944 1945 If the notifier call chain should be failed with some events 1946 notified, write the error code to "actions/<notifier event>/error". 1947 1948 Example: Inject netdevice mtu change error (-22 = -EINVAL) 1949 1950 # cd /sys/kernel/debug/notifier-error-inject/netdev 1951 # echo -22 > actions/NETDEV_CHANGEMTU/error 1952 # ip link set eth0 mtu 1024 1953 RTNETLINK answers: Invalid argument 1954 1955 To compile this code as a module, choose M here: the module will 1956 be called netdev-notifier-error-inject. 1957 1958 If unsure, say N. 1959 1960 config FUNCTION_ERROR_INJECTION 1961 bool "Fault-injections of functions" 1962 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 1963 help 1964 Add fault injections into various functions that are annotated with 1965 ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return 1966 value of these functions. This is useful to test error paths of code. 1967 1968 If unsure, say N 1969 1970 config FAULT_INJECTION 1971 bool "Fault-injection framework" 1972 depends on DEBUG_KERNEL 1973 help 1974 Provide fault-injection framework. 1975 For more details, see Documentation/fault-injection/. 1976 1977 config FAILSLAB 1978 bool "Fault-injection capability for kmalloc" 1979 depends on FAULT_INJECTION 1980 help 1981 Provide fault-injection capability for kmalloc. 1982 1983 config 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 1989 config 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 1996 config 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 2002 config 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 2013 config 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 2020 config 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 2026 config 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 2036 config 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 2046 config 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 2053 config 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 2064 config 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 2073 config 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 2080 config CC_HAS_SANCOV_TRACE_PC 2081 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 2082 2083 2084 config 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 || CC_IS_CLANG 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 For more details, see Documentation/dev-tools/kcov.rst. 2098 2099 config KCOV_ENABLE_COMPARISONS 2100 bool "Enable comparison operands collection by KCOV" 2101 depends on KCOV 2102 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 2103 help 2104 KCOV also exposes operands of every comparison in the instrumented 2105 code along with operand sizes and PCs of the comparison instructions. 2106 These operands can be used by fuzzing engines to improve the quality 2107 of fuzzing coverage. 2108 2109 config KCOV_INSTRUMENT_ALL 2110 bool "Instrument all code by default" 2111 depends on KCOV 2112 default y 2113 help 2114 If you are doing generic system call fuzzing (like e.g. syzkaller), 2115 then you will want to instrument the whole kernel and you should 2116 say y here. If you are doing more targeted fuzzing (like e.g. 2117 filesystem fuzzing with AFL) then you will want to enable coverage 2118 for more specific subsets of files, and should say n here. 2119 2120 config KCOV_IRQ_AREA_SIZE 2121 hex "Size of interrupt coverage collection area in words" 2122 depends on KCOV 2123 default 0x40000 2124 help 2125 KCOV uses preallocated per-cpu areas to collect coverage from 2126 soft interrupts. This specifies the size of those areas in the 2127 number of unsigned long words. 2128 2129 menuconfig RUNTIME_TESTING_MENU 2130 bool "Runtime Testing" 2131 default y 2132 2133 if RUNTIME_TESTING_MENU 2134 2135 config TEST_DHRY 2136 tristate "Dhrystone benchmark test" 2137 help 2138 Enable this to include the Dhrystone 2.1 benchmark. This test 2139 calculates the number of Dhrystones per second, and the number of 2140 DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided 2141 by 1757 (the number of Dhrystones per second obtained on the VAX 2142 11/780, nominally a 1 MIPS machine). 2143 2144 To run the benchmark, it needs to be enabled explicitly, either from 2145 the kernel command line (when built-in), or from userspace (when 2146 built-in or modular). 2147 2148 Run once during kernel boot: 2149 2150 test_dhry.run 2151 2152 Set number of iterations from kernel command line: 2153 2154 test_dhry.iterations=<n> 2155 2156 Set number of iterations from userspace: 2157 2158 echo <n> > /sys/module/test_dhry/parameters/iterations 2159 2160 Trigger manual run from userspace: 2161 2162 echo y > /sys/module/test_dhry/parameters/run 2163 2164 If the number of iterations is <= 0, the test will devise a suitable 2165 number of iterations (test runs for at least 2s) automatically. 2166 This process takes ca. 4s. 2167 2168 If unsure, say N. 2169 2170 config LKDTM 2171 tristate "Linux Kernel Dump Test Tool Module" 2172 depends on DEBUG_FS 2173 help 2174 This module enables testing of the different dumping mechanisms by 2175 inducing system failures at predefined crash points. 2176 If you don't need it: say N 2177 Choose M here to compile this code as a module. The module will be 2178 called lkdtm. 2179 2180 Documentation on how to use the module can be found in 2181 Documentation/fault-injection/provoke-crashes.rst 2182 2183 config CPUMASK_KUNIT_TEST 2184 tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS 2185 depends on KUNIT 2186 default KUNIT_ALL_TESTS 2187 help 2188 Enable to turn on cpumask tests, running at boot or module load time. 2189 2190 For more information on KUnit and unit tests in general, please refer 2191 to the KUnit documentation in Documentation/dev-tools/kunit/. 2192 2193 If unsure, say N. 2194 2195 config TEST_LIST_SORT 2196 tristate "Linked list sorting test" if !KUNIT_ALL_TESTS 2197 depends on KUNIT 2198 default KUNIT_ALL_TESTS 2199 help 2200 Enable this to turn on 'list_sort()' function test. This test is 2201 executed only once during system boot (so affects only boot time), 2202 or at module load time. 2203 2204 If unsure, say N. 2205 2206 config TEST_MIN_HEAP 2207 tristate "Min heap test" 2208 depends on DEBUG_KERNEL || m 2209 help 2210 Enable this to turn on min heap function tests. This test is 2211 executed only once during system boot (so affects only boot time), 2212 or at module load time. 2213 2214 If unsure, say N. 2215 2216 config TEST_SORT 2217 tristate "Array-based sort test" if !KUNIT_ALL_TESTS 2218 depends on KUNIT 2219 default KUNIT_ALL_TESTS 2220 help 2221 This option enables the self-test function of 'sort()' at boot, 2222 or at module load time. 2223 2224 If unsure, say N. 2225 2226 config TEST_DIV64 2227 tristate "64bit/32bit division and modulo test" 2228 depends on DEBUG_KERNEL || m 2229 help 2230 Enable this to turn on 'do_div()' function test. This test is 2231 executed only once during system boot (so affects only boot time), 2232 or at module load time. 2233 2234 If unsure, say N. 2235 2236 config TEST_IOV_ITER 2237 tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS 2238 depends on KUNIT 2239 depends on MMU 2240 default KUNIT_ALL_TESTS 2241 help 2242 Enable this to turn on testing of the operation of the I/O iterator 2243 (iov_iter). This test is executed only once during system boot (so 2244 affects only boot time), or at module load time. 2245 2246 If unsure, say N. 2247 2248 config KPROBES_SANITY_TEST 2249 tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS 2250 depends on DEBUG_KERNEL 2251 depends on KPROBES 2252 depends on KUNIT 2253 select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 2254 default KUNIT_ALL_TESTS 2255 help 2256 This option provides for testing basic kprobes functionality on 2257 boot. Samples of kprobe and kretprobe are inserted and 2258 verified for functionality. 2259 2260 Say N if you are unsure. 2261 2262 config FPROBE_SANITY_TEST 2263 bool "Self test for fprobe" 2264 depends on DEBUG_KERNEL 2265 depends on FPROBE 2266 depends on KUNIT=y 2267 help 2268 This option will enable testing the fprobe when the system boot. 2269 A series of tests are made to verify that the fprobe is functioning 2270 properly. 2271 2272 Say N if you are unsure. 2273 2274 config BACKTRACE_SELF_TEST 2275 tristate "Self test for the backtrace code" 2276 depends on DEBUG_KERNEL 2277 help 2278 This option provides a kernel module that can be used to test 2279 the kernel stack backtrace code. This option is not useful 2280 for distributions or general kernels, but only for kernel 2281 developers working on architecture code. 2282 2283 Note that if you want to also test saved backtraces, you will 2284 have to enable STACKTRACE as well. 2285 2286 Say N if you are unsure. 2287 2288 config TEST_REF_TRACKER 2289 tristate "Self test for reference tracker" 2290 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT 2291 select REF_TRACKER 2292 help 2293 This option provides a kernel module performing tests 2294 using reference tracker infrastructure. 2295 2296 Say N if you are unsure. 2297 2298 config RBTREE_TEST 2299 tristate "Red-Black tree test" 2300 depends on DEBUG_KERNEL 2301 help 2302 A benchmark measuring the performance of the rbtree library. 2303 Also includes rbtree invariant checks. 2304 2305 config REED_SOLOMON_TEST 2306 tristate "Reed-Solomon library test" 2307 depends on DEBUG_KERNEL || m 2308 select REED_SOLOMON 2309 select REED_SOLOMON_ENC16 2310 select REED_SOLOMON_DEC16 2311 help 2312 This option enables the self-test function of rslib at boot, 2313 or at module load time. 2314 2315 If unsure, say N. 2316 2317 config INTERVAL_TREE_TEST 2318 tristate "Interval tree test" 2319 depends on DEBUG_KERNEL 2320 select INTERVAL_TREE 2321 help 2322 A benchmark measuring the performance of the interval tree library 2323 2324 config PERCPU_TEST 2325 tristate "Per cpu operations test" 2326 depends on m && DEBUG_KERNEL 2327 help 2328 Enable this option to build test module which validates per-cpu 2329 operations. 2330 2331 If unsure, say N. 2332 2333 config ATOMIC64_SELFTEST 2334 tristate "Perform an atomic64_t self-test" 2335 help 2336 Enable this option to test the atomic64_t functions at boot or 2337 at module load time. 2338 2339 If unsure, say N. 2340 2341 config ASYNC_RAID6_TEST 2342 tristate "Self test for hardware accelerated raid6 recovery" 2343 depends on ASYNC_RAID6_RECOV 2344 select ASYNC_MEMCPY 2345 help 2346 This is a one-shot self test that permutes through the 2347 recovery of all the possible two disk failure scenarios for a 2348 N-disk array. Recovery is performed with the asynchronous 2349 raid6 recovery routines, and will optionally use an offload 2350 engine if one is available. 2351 2352 If unsure, say N. 2353 2354 config TEST_HEXDUMP 2355 tristate "Test functions located in the hexdump module at runtime" 2356 2357 config STRING_KUNIT_TEST 2358 tristate "KUnit test string functions at runtime" if !KUNIT_ALL_TESTS 2359 depends on KUNIT 2360 default KUNIT_ALL_TESTS 2361 2362 config STRING_HELPERS_KUNIT_TEST 2363 tristate "KUnit test string helpers at runtime" if !KUNIT_ALL_TESTS 2364 depends on KUNIT 2365 default KUNIT_ALL_TESTS 2366 2367 config TEST_KSTRTOX 2368 tristate "Test kstrto*() family of functions at runtime" 2369 2370 config TEST_PRINTF 2371 tristate "Test printf() family of functions at runtime" 2372 2373 config TEST_SCANF 2374 tristate "Test scanf() family of functions at runtime" 2375 2376 config 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 2383 config TEST_UUID 2384 tristate "Test functions located in the uuid module at runtime" 2385 2386 config TEST_XARRAY 2387 tristate "Test the XArray code at runtime" 2388 2389 config 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 2398 config 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 2405 config TEST_IDA 2406 tristate "Perform selftest on IDA functions" 2407 2408 config 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 2417 config 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 2425 config 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 2438 config 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 2451 config 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 2464 config 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 2476 config 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 2489 config 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 2498 config 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 2506 config 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 2518 config 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 2528 config 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 2545 config 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 2562 config 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 2581 config 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 2593 config 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 2605 config 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 2624 config 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 2637 config 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 2649 config 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 2661 config 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 2673 config 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 2685 config 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 2696 config 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 2707 config IS_SIGNED_TYPE_KUNIT_TEST 2708 tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS 2709 depends on KUNIT 2710 default KUNIT_ALL_TESTS 2711 help 2712 Builds unit tests for the is_signed_type() macro. 2713 2714 For more information on KUnit and unit tests in general please refer 2715 to the KUnit documentation in Documentation/dev-tools/kunit/. 2716 2717 If unsure, say N. 2718 2719 config OVERFLOW_KUNIT_TEST 2720 tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS 2721 depends on KUNIT 2722 default KUNIT_ALL_TESTS 2723 help 2724 Builds unit tests for the check_*_overflow(), size_*(), allocation, and 2725 related functions. 2726 2727 For more information on KUnit and unit tests in general please refer 2728 to the KUnit documentation in Documentation/dev-tools/kunit/. 2729 2730 If unsure, say N. 2731 2732 config STACKINIT_KUNIT_TEST 2733 tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS 2734 depends on KUNIT 2735 default KUNIT_ALL_TESTS 2736 help 2737 Test if the kernel is zero-initializing stack variables and 2738 padding. Coverage is controlled by compiler flags, 2739 CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO, 2740 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2741 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2742 2743 config FORTIFY_KUNIT_TEST 2744 tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS 2745 depends on KUNIT 2746 default KUNIT_ALL_TESTS 2747 help 2748 Builds unit tests for checking internals of FORTIFY_SOURCE as used 2749 by the str*() and mem*() family of functions. For testing runtime 2750 traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests. 2751 2752 config HW_BREAKPOINT_KUNIT_TEST 2753 bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS 2754 depends on HAVE_HW_BREAKPOINT 2755 depends on KUNIT=y 2756 default KUNIT_ALL_TESTS 2757 help 2758 Tests for hw_breakpoint constraints accounting. 2759 2760 If unsure, say N. 2761 2762 config STRCAT_KUNIT_TEST 2763 tristate "Test strcat() family of functions at runtime" if !KUNIT_ALL_TESTS 2764 depends on KUNIT 2765 default KUNIT_ALL_TESTS 2766 2767 config STRSCPY_KUNIT_TEST 2768 tristate "Test strscpy*() family of functions at runtime" if !KUNIT_ALL_TESTS 2769 depends on KUNIT 2770 default KUNIT_ALL_TESTS 2771 2772 config SIPHASH_KUNIT_TEST 2773 tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS 2774 depends on KUNIT 2775 default KUNIT_ALL_TESTS 2776 help 2777 Enable this option to test the kernel's siphash (<linux/siphash.h>) hash 2778 functions on boot (or module load). 2779 2780 This is intended to help people writing architecture-specific 2781 optimized versions. If unsure, say N. 2782 2783 config TEST_UDELAY 2784 tristate "udelay test driver" 2785 help 2786 This builds the "udelay_test" module that helps to make sure 2787 that udelay() is working properly. 2788 2789 If unsure, say N. 2790 2791 config TEST_STATIC_KEYS 2792 tristate "Test static keys" 2793 depends on m 2794 help 2795 Test the static key interfaces. 2796 2797 If unsure, say N. 2798 2799 config TEST_DYNAMIC_DEBUG 2800 tristate "Test DYNAMIC_DEBUG" 2801 depends on DYNAMIC_DEBUG 2802 help 2803 This module registers a tracer callback to count enabled 2804 pr_debugs in a 'do_debugging' function, then alters their 2805 enablements, calls the function, and compares counts. 2806 2807 If unsure, say N. 2808 2809 config TEST_KMOD 2810 tristate "kmod stress tester" 2811 depends on m 2812 depends on NETDEVICES && NET_CORE && INET # for TUN 2813 depends on BLOCK 2814 depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS 2815 select TEST_LKM 2816 select XFS_FS 2817 select TUN 2818 select BTRFS_FS 2819 help 2820 Test the kernel's module loading mechanism: kmod. kmod implements 2821 support to load modules using the Linux kernel's usermode helper. 2822 This test provides a series of tests against kmod. 2823 2824 Although technically you can either build test_kmod as a module or 2825 into the kernel we disallow building it into the kernel since 2826 it stress tests request_module() and this will very likely cause 2827 some issues by taking over precious threads available from other 2828 module load requests, ultimately this could be fatal. 2829 2830 To run tests run: 2831 2832 tools/testing/selftests/kmod/kmod.sh --help 2833 2834 If unsure, say N. 2835 2836 config TEST_DEBUG_VIRTUAL 2837 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 2838 depends on DEBUG_VIRTUAL 2839 help 2840 Test the kernel's ability to detect incorrect calls to 2841 virt_to_phys() done against the non-linear part of the 2842 kernel's virtual address map. 2843 2844 If unsure, say N. 2845 2846 config TEST_MEMCAT_P 2847 tristate "Test memcat_p() helper function" 2848 help 2849 Test the memcat_p() helper for correctly merging two 2850 pointer arrays together. 2851 2852 If unsure, say N. 2853 2854 config TEST_OBJAGG 2855 tristate "Perform selftest on object aggreration manager" 2856 default n 2857 depends on OBJAGG 2858 help 2859 Enable this option to test object aggregation manager on boot 2860 (or module load). 2861 2862 config TEST_MEMINIT 2863 tristate "Test heap/page initialization" 2864 help 2865 Test if the kernel is zero-initializing heap and page allocations. 2866 This can be useful to test init_on_alloc and init_on_free features. 2867 2868 If unsure, say N. 2869 2870 config TEST_HMM 2871 tristate "Test HMM (Heterogeneous Memory Management)" 2872 depends on TRANSPARENT_HUGEPAGE 2873 depends on DEVICE_PRIVATE 2874 select HMM_MIRROR 2875 select MMU_NOTIFIER 2876 help 2877 This is a pseudo device driver solely for testing HMM. 2878 Say M here if you want to build the HMM test module. 2879 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests. 2880 2881 If unsure, say N. 2882 2883 config TEST_FREE_PAGES 2884 tristate "Test freeing pages" 2885 help 2886 Test that a memory leak does not occur due to a race between 2887 freeing a block of pages and a speculative page reference. 2888 Loading this module is safe if your kernel has the bug fixed. 2889 If the bug is not fixed, it will leak gigabytes of memory and 2890 probably OOM your system. 2891 2892 config TEST_FPU 2893 tristate "Test floating point operations in kernel space" 2894 depends on X86 && !KCOV_INSTRUMENT_ALL 2895 help 2896 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu 2897 which will trigger a sequence of floating point operations. This is used 2898 for self-testing floating point control register setting in 2899 kernel_fpu_begin(). 2900 2901 If unsure, say N. 2902 2903 config TEST_CLOCKSOURCE_WATCHDOG 2904 tristate "Test clocksource watchdog in kernel space" 2905 depends on CLOCKSOURCE_WATCHDOG 2906 help 2907 Enable this option to create a kernel module that will trigger 2908 a test of the clocksource watchdog. This module may be loaded 2909 via modprobe or insmod in which case it will run upon being 2910 loaded, or it may be built in, in which case it will run 2911 shortly after boot. 2912 2913 If unsure, say N. 2914 2915 config TEST_OBJPOOL 2916 tristate "Test module for correctness and stress of objpool" 2917 default n 2918 depends on m && DEBUG_KERNEL 2919 help 2920 This builds the "test_objpool" module that should be used for 2921 correctness verification and concurrent testings of objects 2922 allocation and reclamation. 2923 2924 If unsure, say N. 2925 2926 endif # RUNTIME_TESTING_MENU 2927 2928 config ARCH_USE_MEMTEST 2929 bool 2930 help 2931 An architecture should select this when it uses early_memtest() 2932 during boot process. 2933 2934 config MEMTEST 2935 bool "Memtest" 2936 depends on ARCH_USE_MEMTEST 2937 help 2938 This option adds a kernel parameter 'memtest', which allows memtest 2939 to be set and executed. 2940 memtest=0, mean disabled; -- default 2941 memtest=1, mean do 1 test pattern; 2942 ... 2943 memtest=17, mean do 17 test patterns. 2944 If you are unsure how to answer this question, answer N. 2945 2946 2947 2948 config HYPERV_TESTING 2949 bool "Microsoft Hyper-V driver testing" 2950 default n 2951 depends on HYPERV && DEBUG_FS 2952 help 2953 Select this option to enable Hyper-V vmbus testing. 2954 2955 endmenu # "Kernel Testing and Coverage" 2956 2957 menu "Rust hacking" 2958 2959 config RUST_DEBUG_ASSERTIONS 2960 bool "Debug assertions" 2961 depends on RUST 2962 help 2963 Enables rustc's `-Cdebug-assertions` codegen option. 2964 2965 This flag lets you turn `cfg(debug_assertions)` conditional 2966 compilation on or off. This can be used to enable extra debugging 2967 code in development but not in production. For example, it controls 2968 the behavior of the standard library's `debug_assert!` macro. 2969 2970 Note that this will apply to all Rust code, including `core`. 2971 2972 If unsure, say N. 2973 2974 config RUST_OVERFLOW_CHECKS 2975 bool "Overflow checks" 2976 default y 2977 depends on RUST 2978 help 2979 Enables rustc's `-Coverflow-checks` codegen option. 2980 2981 This flag allows you to control the behavior of runtime integer 2982 overflow. When overflow-checks are enabled, a Rust panic will occur 2983 on overflow. 2984 2985 Note that this will apply to all Rust code, including `core`. 2986 2987 If unsure, say Y. 2988 2989 config RUST_BUILD_ASSERT_ALLOW 2990 bool "Allow unoptimized build-time assertions" 2991 depends on RUST 2992 help 2993 Controls how are `build_error!` and `build_assert!` handled during build. 2994 2995 If calls to them exist in the binary, it may indicate a violated invariant 2996 or that the optimizer failed to verify the invariant during compilation. 2997 2998 This should not happen, thus by default the build is aborted. However, 2999 as an escape hatch, you can choose Y here to ignore them during build 3000 and let the check be carried at runtime (with `panic!` being called if 3001 the check fails). 3002 3003 If unsure, say N. 3004 3005 config RUST_KERNEL_DOCTESTS 3006 bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS 3007 depends on RUST && KUNIT=y 3008 default KUNIT_ALL_TESTS 3009 help 3010 This builds the documentation tests of the `kernel` crate 3011 as KUnit tests. 3012 3013 For more information on KUnit and unit tests in general, 3014 please refer to the KUnit documentation in Documentation/dev-tools/kunit/. 3015 3016 If unsure, say N. 3017 3018 endmenu # "Rust" 3019 3020 endmenu # Kernel hacking 3021