1# SPDX-License-Identifier: GPL-2.0-only 2menu "Kernel hacking" 3 4menu "printk and dmesg options" 5 6config PRINTK_TIME 7 bool "Show timing information on printks" 8 depends on PRINTK 9 help 10 Selecting this option causes time stamps of the printk() 11 messages to be added to the output of the syslog() system 12 call and at the console. 13 14 The timestamp is always recorded internally, and exported 15 to /dev/kmsg. This flag just specifies if the timestamp should 16 be included, not that the timestamp is recorded. 17 18 The behavior is also controlled by the kernel command line 19 parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst 20 21config PRINTK_CALLER 22 bool "Show caller information on printks" 23 depends on PRINTK 24 help 25 Selecting this option causes printk() to add a caller "thread id" (if 26 in task context) or a caller "processor id" (if not in task context) 27 to every message. 28 29 This option is intended for environments where multiple threads 30 concurrently call printk() for many times, for it is difficult to 31 interpret without knowing where these lines (or sometimes individual 32 line which was divided into multiple lines due to race) came from. 33 34 Since toggling after boot makes the code racy, currently there is 35 no option to enable/disable at the kernel command line parameter or 36 sysfs interface. 37 38config STACKTRACE_BUILD_ID 39 bool "Show build ID information in stacktraces" 40 depends on PRINTK 41 help 42 Selecting this option adds build ID information for symbols in 43 stacktraces printed with the printk format '%p[SR]b'. 44 45 This option is intended for distros where debuginfo is not easily 46 accessible but can be downloaded given the build ID of the vmlinux or 47 kernel module where the function is located. 48 49config CONSOLE_LOGLEVEL_DEFAULT 50 int "Default console loglevel (1-15)" 51 range 1 15 52 default "7" 53 help 54 Default loglevel to determine what will be printed on the console. 55 56 Setting a default here is equivalent to passing in loglevel=<x> in 57 the kernel bootargs. loglevel=<x> continues to override whatever 58 value is specified here as well. 59 60 Note: This does not affect the log level of un-prefixed printk() 61 usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT 62 option. 63 64config CONSOLE_LOGLEVEL_QUIET 65 int "quiet console loglevel (1-15)" 66 range 1 15 67 default "4" 68 help 69 loglevel to use when "quiet" is passed on the kernel commandline. 70 71 When "quiet" is passed on the kernel commandline this loglevel 72 will be used as the loglevel. IOW passing "quiet" will be the 73 equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>" 74 75config MESSAGE_LOGLEVEL_DEFAULT 76 int "Default message log level (1-7)" 77 range 1 7 78 default "4" 79 help 80 Default log level for printk statements with no specified priority. 81 82 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks 83 that are auditing their logs closely may want to set it to a lower 84 priority. 85 86 Note: This does not affect what message level gets printed on the console 87 by default. To change that, use loglevel=<x> in the kernel bootargs, 88 or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value. 89 90config BOOT_PRINTK_DELAY 91 bool "Delay each boot printk message by N milliseconds" 92 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY 93 help 94 This build option allows you to read kernel boot messages 95 by inserting a short delay after each one. The delay is 96 specified in milliseconds on the kernel command line, 97 using "boot_delay=N". 98 99 It is likely that you would also need to use "lpj=M" to preset 100 the "loops per jiffie" value. 101 See a previous boot log for the "lpj" value to use for your 102 system, and then set "lpj=M" before setting "boot_delay=N". 103 NOTE: Using this option may adversely affect SMP systems. 104 I.e., processors other than the first one may not boot up. 105 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect 106 what it believes to be lockup conditions. 107 108config DYNAMIC_DEBUG 109 bool "Enable dynamic printk() support" 110 default n 111 depends on PRINTK 112 depends on (DEBUG_FS || PROC_FS) 113 select DYNAMIC_DEBUG_CORE 114 help 115 116 Compiles debug level messages into the kernel, which would not 117 otherwise be available at runtime. These messages can then be 118 enabled/disabled based on various levels of scope - per source file, 119 function, module, format string, and line number. This mechanism 120 implicitly compiles in all pr_debug() and dev_dbg() calls, which 121 enlarges the kernel text size by about 2%. 122 123 If a source file is compiled with DEBUG flag set, any 124 pr_debug() calls in it are enabled by default, but can be 125 disabled at runtime as below. Note that DEBUG flag is 126 turned on by many CONFIG_*DEBUG* options. 127 128 Usage: 129 130 Dynamic debugging is controlled via the 'dynamic_debug/control' file, 131 which is contained in the 'debugfs' filesystem or procfs. 132 Thus, the debugfs or procfs filesystem must first be mounted before 133 making use of this feature. 134 We refer the control file as: <debugfs>/dynamic_debug/control. This 135 file contains a list of the debug statements that can be enabled. The 136 format for each line of the file is: 137 138 filename:lineno [module]function flags format 139 140 filename : source file of the debug statement 141 lineno : line number of the debug statement 142 module : module that contains the debug statement 143 function : function that contains the debug statement 144 flags : '=p' means the line is turned 'on' for printing 145 format : the format used for the debug statement 146 147 From a live system: 148 149 nullarbor:~ # cat <debugfs>/dynamic_debug/control 150 # filename:lineno [module]function flags format 151 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012" 152 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012" 153 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012" 154 155 Example usage: 156 157 // enable the message at line 1603 of file svcsock.c 158 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' > 159 <debugfs>/dynamic_debug/control 160 161 // enable all the messages in file svcsock.c 162 nullarbor:~ # echo -n 'file svcsock.c +p' > 163 <debugfs>/dynamic_debug/control 164 165 // enable all the messages in the NFS server module 166 nullarbor:~ # echo -n 'module nfsd +p' > 167 <debugfs>/dynamic_debug/control 168 169 // enable all 12 messages in the function svc_process() 170 nullarbor:~ # echo -n 'func svc_process +p' > 171 <debugfs>/dynamic_debug/control 172 173 // disable all 12 messages in the function svc_process() 174 nullarbor:~ # echo -n 'func svc_process -p' > 175 <debugfs>/dynamic_debug/control 176 177 See Documentation/admin-guide/dynamic-debug-howto.rst for additional 178 information. 179 180config DYNAMIC_DEBUG_CORE 181 bool "Enable core function of dynamic debug support" 182 depends on PRINTK 183 depends on (DEBUG_FS || PROC_FS) 184 help 185 Enable core functional support of dynamic debug. It is useful 186 when you want to tie dynamic debug to your kernel modules with 187 DYNAMIC_DEBUG_MODULE defined for each of them, especially for 188 the case of embedded system where the kernel image size is 189 sensitive for people. 190 191config SYMBOLIC_ERRNAME 192 bool "Support symbolic error names in printf" 193 default y if PRINTK 194 help 195 If you say Y here, the kernel's printf implementation will 196 be able to print symbolic error names such as ENOSPC instead 197 of the number 28. It makes the kernel image slightly larger 198 (about 3KB), but can make the kernel logs easier to read. 199 200config DEBUG_BUGVERBOSE 201 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT 202 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE) 203 default y 204 help 205 Say Y here to make BUG() panics output the file name and line number 206 of the BUG call as well as the EIP and oops trace. This aids 207 debugging but costs about 70-100K of memory. 208 209endmenu # "printk and dmesg options" 210 211config DEBUG_KERNEL 212 bool "Kernel debugging" 213 help 214 Say Y here if you are developing drivers or trying to debug and 215 identify kernel problems. 216 217config DEBUG_MISC 218 bool "Miscellaneous debug code" 219 default DEBUG_KERNEL 220 depends on DEBUG_KERNEL 221 help 222 Say Y here if you need to enable miscellaneous debug code that should 223 be under a more specific debug option but isn't. 224 225menu "Compile-time checks and compiler options" 226 227config DEBUG_INFO 228 bool 229 help 230 A kernel debug info option other than "None" has been selected 231 in the "Debug information" choice below, indicating that debug 232 information will be generated for build targets. 233 234# Clang 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 237config AS_HAS_NON_CONST_ULEB128 238 def_bool $(as-instr,.uleb128 .Lexpr_end4 - .Lexpr_start3\n.Lexpr_start3:\n.Lexpr_end4:) 239 240choice 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 253config 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 259config 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 271config 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 283config 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 301endchoice # "Debug information" 302 303if DEBUG_INFO 304 305config 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 317choice 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 325config DEBUG_INFO_COMPRESSED_NONE 326 bool "Don't compress debug information" 327 help 328 Don't compress debug info sections. 329 330config 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 345config 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 355endchoice # "Compressed Debug information" 356 357config 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 377config 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 390config PAHOLE_HAS_SPLIT_BTF 391 def_bool PAHOLE_VERSION >= 119 392 393config 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 401config 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 410config 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 417config 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 427config 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 437endif # DEBUG_INFO 438 439config 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 454config 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 462config 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 472config 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 482config 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 504config 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 513config 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# 531config ARCH_WANT_FRAME_POINTERS 532 bool 533 534config 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 543config OBJTOOL 544 bool 545 546config 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 558config NOINSTR_VALIDATION 559 bool 560 depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY 561 select OBJTOOL 562 default y 563 564config 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 574config BUILTIN_MODULE_RANGES 575 bool "Generate address range information for builtin modules" 576 depends on !LTO 577 depends on VMLINUX_MAP 578 help 579 When modules are built into the kernel, there will be no module name 580 associated with its symbols in /proc/kallsyms. Tracers may want to 581 identify symbols by module name and symbol name regardless of whether 582 the module is configured as loadable or not. 583 584 This option generates modules.builtin.ranges in the build tree with 585 offset ranges (per ELF section) for the module(s) they belong to. 586 It also records an anchor symbol to determine the load address of the 587 section. 588 589config DEBUG_FORCE_WEAK_PER_CPU 590 bool "Force weak per-cpu definitions" 591 depends on DEBUG_KERNEL 592 help 593 s390 and alpha require percpu variables in modules to be 594 defined weak to work around addressing range issue which 595 puts the following two restrictions on percpu variable 596 definitions. 597 598 1. percpu symbols must be unique whether static or not 599 2. percpu variables can't be defined inside a function 600 601 To ensure that generic code follows the above rules, this 602 option forces all percpu variables to be defined as weak. 603 604endmenu # "Compiler options" 605 606menu "Generic Kernel Debugging Instruments" 607 608config MAGIC_SYSRQ 609 bool "Magic SysRq key" 610 depends on !UML 611 help 612 If you say Y here, you will have some control over the system even 613 if the system crashes for example during kernel debugging (e.g., you 614 will be able to flush the buffer cache to disk, reboot the system 615 immediately or dump some status information). This is accomplished 616 by pressing various keys while holding SysRq (Alt+PrintScreen). It 617 also works on a serial console (on PC hardware at least), if you 618 send a BREAK and then within 5 seconds a command keypress. The 619 keys are documented in <file:Documentation/admin-guide/sysrq.rst>. 620 Don't say Y unless you really know what this hack does. 621 622config MAGIC_SYSRQ_DEFAULT_ENABLE 623 hex "Enable magic SysRq key functions by default" 624 depends on MAGIC_SYSRQ 625 default 0x1 626 help 627 Specifies which SysRq key functions are enabled by default. 628 This may be set to 1 or 0 to enable or disable them all, or 629 to a bitmask as described in Documentation/admin-guide/sysrq.rst. 630 631config MAGIC_SYSRQ_SERIAL 632 bool "Enable magic SysRq key over serial" 633 depends on MAGIC_SYSRQ 634 default y 635 help 636 Many embedded boards have a disconnected TTL level serial which can 637 generate some garbage that can lead to spurious false sysrq detects. 638 This option allows you to decide whether you want to enable the 639 magic SysRq key. 640 641config MAGIC_SYSRQ_SERIAL_SEQUENCE 642 string "Char sequence that enables magic SysRq over serial" 643 depends on MAGIC_SYSRQ_SERIAL 644 default "" 645 help 646 Specifies a sequence of characters that can follow BREAK to enable 647 SysRq on a serial console. 648 649 If unsure, leave an empty string and the option will not be enabled. 650 651config DEBUG_FS 652 bool "Debug Filesystem" 653 help 654 debugfs is a virtual file system that kernel developers use to put 655 debugging files into. Enable this option to be able to read and 656 write to these files. 657 658 For detailed documentation on the debugfs API, see 659 Documentation/filesystems/. 660 661 If unsure, say N. 662 663choice 664 prompt "Debugfs default access" 665 depends on DEBUG_FS 666 default DEBUG_FS_ALLOW_ALL 667 help 668 This selects the default access restrictions for debugfs. 669 It can be overridden with kernel command line option 670 debugfs=[on,no-mount,off]. The restrictions apply for API access 671 and filesystem registration. 672 673config DEBUG_FS_ALLOW_ALL 674 bool "Access normal" 675 help 676 No restrictions apply. Both API and filesystem registration 677 is on. This is the normal default operation. 678 679config DEBUG_FS_DISALLOW_MOUNT 680 bool "Do not register debugfs as filesystem" 681 help 682 The API is open but filesystem is not loaded. Clients can still do 683 their work and read with debug tools that do not need 684 debugfs filesystem. 685 686config DEBUG_FS_ALLOW_NONE 687 bool "No access" 688 help 689 Access is off. Clients get -PERM when trying to create nodes in 690 debugfs tree and debugfs is not registered as a filesystem. 691 Client can then back-off or continue without debugfs access. 692 693endchoice 694 695source "lib/Kconfig.kgdb" 696source "lib/Kconfig.ubsan" 697source "lib/Kconfig.kcsan" 698 699endmenu 700 701menu "Networking Debugging" 702 703source "net/Kconfig.debug" 704 705endmenu # "Networking Debugging" 706 707menu "Memory Debugging" 708 709source "mm/Kconfig.debug" 710 711config DEBUG_OBJECTS 712 bool "Debug object operations" 713 depends on DEBUG_KERNEL 714 help 715 If you say Y here, additional code will be inserted into the 716 kernel to track the life time of various objects and validate 717 the operations on those objects. 718 719config DEBUG_OBJECTS_SELFTEST 720 bool "Debug objects selftest" 721 depends on DEBUG_OBJECTS 722 help 723 This enables the selftest of the object debug code. 724 725config DEBUG_OBJECTS_FREE 726 bool "Debug objects in freed memory" 727 depends on DEBUG_OBJECTS 728 help 729 This enables checks whether a k/v free operation frees an area 730 which contains an object which has not been deactivated 731 properly. This can make kmalloc/kfree-intensive workloads 732 much slower. 733 734config DEBUG_OBJECTS_TIMERS 735 bool "Debug timer objects" 736 depends on DEBUG_OBJECTS 737 help 738 If you say Y here, additional code will be inserted into the 739 timer routines to track the life time of timer objects and 740 validate the timer operations. 741 742config DEBUG_OBJECTS_WORK 743 bool "Debug work objects" 744 depends on DEBUG_OBJECTS 745 help 746 If you say Y here, additional code will be inserted into the 747 work queue routines to track the life time of work objects and 748 validate the work operations. 749 750config DEBUG_OBJECTS_RCU_HEAD 751 bool "Debug RCU callbacks objects" 752 depends on DEBUG_OBJECTS 753 help 754 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 755 756config DEBUG_OBJECTS_PERCPU_COUNTER 757 bool "Debug percpu counter objects" 758 depends on DEBUG_OBJECTS 759 help 760 If you say Y here, additional code will be inserted into the 761 percpu counter routines to track the life time of percpu counter 762 objects and validate the percpu counter operations. 763 764config DEBUG_OBJECTS_ENABLE_DEFAULT 765 int "debug_objects bootup default value (0-1)" 766 range 0 1 767 default "1" 768 depends on DEBUG_OBJECTS 769 help 770 Debug objects boot parameter default value 771 772config SHRINKER_DEBUG 773 bool "Enable shrinker debugging support" 774 depends on DEBUG_FS 775 help 776 Say Y to enable the shrinker debugfs interface which provides 777 visibility into the kernel memory shrinkers subsystem. 778 Disable it to avoid an extra memory footprint. 779 780config DEBUG_STACK_USAGE 781 bool "Stack utilization instrumentation" 782 depends on DEBUG_KERNEL 783 help 784 Enables the display of the minimum amount of free stack which each 785 task has ever had available in the sysrq-T and sysrq-P debug output. 786 Also emits a message to dmesg when a process exits if that process 787 used more stack space than previously exiting processes. 788 789 This option will slow down process creation somewhat. 790 791config SCHED_STACK_END_CHECK 792 bool "Detect stack corruption on calls to schedule()" 793 depends on DEBUG_KERNEL 794 default n 795 help 796 This option checks for a stack overrun on calls to schedule(). 797 If the stack end location is found to be over written always panic as 798 the content of the corrupted region can no longer be trusted. 799 This is to ensure no erroneous behaviour occurs which could result in 800 data corruption or a sporadic crash at a later stage once the region 801 is examined. The runtime overhead introduced is minimal. 802 803config ARCH_HAS_DEBUG_VM_PGTABLE 804 bool 805 help 806 An architecture should select this when it can successfully 807 build and run DEBUG_VM_PGTABLE. 808 809config DEBUG_VM_IRQSOFF 810 def_bool DEBUG_VM && !PREEMPT_RT 811 812config DEBUG_VM 813 bool "Debug VM" 814 depends on DEBUG_KERNEL 815 help 816 Enable this to turn on extended checks in the virtual-memory system 817 that may impact performance. 818 819 If unsure, say N. 820 821config DEBUG_VM_SHOOT_LAZIES 822 bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation" 823 depends on DEBUG_VM 824 depends on MMU_LAZY_TLB_SHOOTDOWN 825 help 826 Enable additional IPIs that ensure lazy tlb mm references are removed 827 before the mm is freed. 828 829 If unsure, say N. 830 831config DEBUG_VM_MAPLE_TREE 832 bool "Debug VM maple trees" 833 depends on DEBUG_VM 834 select DEBUG_MAPLE_TREE 835 help 836 Enable VM maple tree debugging information and extra validations. 837 838 If unsure, say N. 839 840config DEBUG_VM_RB 841 bool "Debug VM red-black trees" 842 depends on DEBUG_VM 843 help 844 Enable VM red-black tree debugging information and extra validations. 845 846 If unsure, say N. 847 848config DEBUG_VM_PGFLAGS 849 bool "Debug page-flags operations" 850 depends on DEBUG_VM 851 help 852 Enables extra validation on page flags operations. 853 854 If unsure, say N. 855 856config DEBUG_VM_PGTABLE 857 bool "Debug arch page table for semantics compliance" 858 depends on MMU 859 depends on ARCH_HAS_DEBUG_VM_PGTABLE 860 default y if DEBUG_VM 861 help 862 This option provides a debug method which can be used to test 863 architecture page table helper functions on various platforms in 864 verifying if they comply with expected generic MM semantics. This 865 will help architecture code in making sure that any changes or 866 new additions of these helpers still conform to expected 867 semantics of the generic MM. Platforms will have to opt in for 868 this through ARCH_HAS_DEBUG_VM_PGTABLE. 869 870 If unsure, say N. 871 872config ARCH_HAS_DEBUG_VIRTUAL 873 bool 874 875config DEBUG_VIRTUAL 876 bool "Debug VM translations" 877 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL 878 help 879 Enable some costly sanity checks in virtual to page code. This can 880 catch mistakes with virt_to_page() and friends. 881 882 If unsure, say N. 883 884config DEBUG_NOMMU_REGIONS 885 bool "Debug the global anon/private NOMMU mapping region tree" 886 depends on DEBUG_KERNEL && !MMU 887 help 888 This option causes the global tree of anonymous and private mapping 889 regions to be regularly checked for invalid topology. 890 891config DEBUG_MEMORY_INIT 892 bool "Debug memory initialisation" if EXPERT 893 default !EXPERT 894 help 895 Enable this for additional checks during memory initialisation. 896 The sanity checks verify aspects of the VM such as the memory model 897 and other information provided by the architecture. Verbose 898 information will be printed at KERN_DEBUG loglevel depending 899 on the mminit_loglevel= command-line option. 900 901 If unsure, say Y 902 903config MEMORY_NOTIFIER_ERROR_INJECT 904 tristate "Memory hotplug notifier error injection module" 905 depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION 906 help 907 This option provides the ability to inject artificial errors to 908 memory hotplug notifier chain callbacks. It is controlled through 909 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 910 911 If the notifier call chain should be failed with some events 912 notified, write the error code to "actions/<notifier event>/error". 913 914 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 915 916 # cd /sys/kernel/debug/notifier-error-inject/memory 917 # echo -12 > actions/MEM_GOING_OFFLINE/error 918 # echo offline > /sys/devices/system/memory/memoryXXX/state 919 bash: echo: write error: Cannot allocate memory 920 921 To compile this code as a module, choose M here: the module will 922 be called memory-notifier-error-inject. 923 924 If unsure, say N. 925 926config DEBUG_PER_CPU_MAPS 927 bool "Debug access to per_cpu maps" 928 depends on DEBUG_KERNEL 929 depends on SMP 930 help 931 Say Y to verify that the per_cpu map being accessed has 932 been set up. This adds a fair amount of code to kernel memory 933 and decreases performance. 934 935 Say N if unsure. 936 937config DEBUG_KMAP_LOCAL 938 bool "Debug kmap_local temporary mappings" 939 depends on DEBUG_KERNEL && KMAP_LOCAL 940 help 941 This option enables additional error checking for the kmap_local 942 infrastructure. Disable for production use. 943 944config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 945 bool 946 947config DEBUG_KMAP_LOCAL_FORCE_MAP 948 bool "Enforce kmap_local temporary mappings" 949 depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 950 select KMAP_LOCAL 951 select DEBUG_KMAP_LOCAL 952 help 953 This option enforces temporary mappings through the kmap_local 954 mechanism for non-highmem pages and on non-highmem systems. 955 Disable this for production systems! 956 957config DEBUG_HIGHMEM 958 bool "Highmem debugging" 959 depends on DEBUG_KERNEL && HIGHMEM 960 select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 961 select DEBUG_KMAP_LOCAL 962 help 963 This option enables additional error checking for high memory 964 systems. Disable for production systems. 965 966config HAVE_DEBUG_STACKOVERFLOW 967 bool 968 969config DEBUG_STACKOVERFLOW 970 bool "Check for stack overflows" 971 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 972 help 973 Say Y here if you want to check for overflows of kernel, IRQ 974 and exception stacks (if your architecture uses them). This 975 option will show detailed messages if free stack space drops 976 below a certain limit. 977 978 These kinds of bugs usually occur when call-chains in the 979 kernel get too deep, especially when interrupts are 980 involved. 981 982 Use this in cases where you see apparently random memory 983 corruption, especially if it appears in 'struct thread_info' 984 985 If in doubt, say "N". 986 987config CODE_TAGGING 988 bool 989 select KALLSYMS 990 991config MEM_ALLOC_PROFILING 992 bool "Enable memory allocation profiling" 993 default n 994 depends on PROC_FS 995 depends on !DEBUG_FORCE_WEAK_PER_CPU 996 select CODE_TAGGING 997 select PAGE_EXTENSION 998 select SLAB_OBJ_EXT 999 help 1000 Track allocation source code and record total allocation size 1001 initiated at that code location. The mechanism can be used to track 1002 memory leaks with a low performance and memory impact. 1003 1004config MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT 1005 bool "Enable memory allocation profiling by default" 1006 default y 1007 depends on MEM_ALLOC_PROFILING 1008 1009config MEM_ALLOC_PROFILING_DEBUG 1010 bool "Memory allocation profiler debugging" 1011 default n 1012 depends on MEM_ALLOC_PROFILING 1013 select MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT 1014 help 1015 Adds warnings with helpful error messages for memory allocation 1016 profiling. 1017 1018source "lib/Kconfig.kasan" 1019source "lib/Kconfig.kfence" 1020source "lib/Kconfig.kmsan" 1021 1022endmenu # "Memory Debugging" 1023 1024config DEBUG_SHIRQ 1025 bool "Debug shared IRQ handlers" 1026 depends on DEBUG_KERNEL 1027 help 1028 Enable this to generate a spurious interrupt just before a shared 1029 interrupt handler is deregistered (generating one when registering 1030 is currently disabled). Drivers need to handle this correctly. Some 1031 don't and need to be caught. 1032 1033menu "Debug Oops, Lockups and Hangs" 1034 1035config PANIC_ON_OOPS 1036 bool "Panic on Oops" 1037 help 1038 Say Y here to enable the kernel to panic when it oopses. This 1039 has the same effect as setting oops=panic on the kernel command 1040 line. 1041 1042 This feature is useful to ensure that the kernel does not do 1043 anything erroneous after an oops which could result in data 1044 corruption or other issues. 1045 1046 Say N if unsure. 1047 1048config PANIC_ON_OOPS_VALUE 1049 int 1050 range 0 1 1051 default 0 if !PANIC_ON_OOPS 1052 default 1 if PANIC_ON_OOPS 1053 1054config PANIC_TIMEOUT 1055 int "panic timeout" 1056 default 0 1057 help 1058 Set the timeout value (in seconds) until a reboot occurs when 1059 the kernel panics. If n = 0, then we wait forever. A timeout 1060 value n > 0 will wait n seconds before rebooting, while a timeout 1061 value n < 0 will reboot immediately. This setting can be overridden 1062 with the kernel command line option panic=, and from userspace via 1063 /proc/sys/kernel/panic. 1064 1065config LOCKUP_DETECTOR 1066 bool 1067 1068config SOFTLOCKUP_DETECTOR 1069 bool "Detect Soft Lockups" 1070 depends on DEBUG_KERNEL && !S390 1071 select LOCKUP_DETECTOR 1072 help 1073 Say Y here to enable the kernel to act as a watchdog to detect 1074 soft lockups. 1075 1076 Softlockups are bugs that cause the kernel to loop in kernel 1077 mode for more than 20 seconds, without giving other tasks a 1078 chance to run. The current stack trace is displayed upon 1079 detection and the system will stay locked up. 1080 1081config SOFTLOCKUP_DETECTOR_INTR_STORM 1082 bool "Detect Interrupt Storm in Soft Lockups" 1083 depends on SOFTLOCKUP_DETECTOR && IRQ_TIME_ACCOUNTING 1084 select GENERIC_IRQ_STAT_SNAPSHOT 1085 default y if NR_CPUS <= 128 1086 help 1087 Say Y here to enable the kernel to detect interrupt storm 1088 during "soft lockups". 1089 1090 "soft lockups" can be caused by a variety of reasons. If one is 1091 caused by an interrupt storm, then the storming interrupts will not 1092 be on the callstack. To detect this case, it is necessary to report 1093 the CPU stats and the interrupt counts during the "soft lockups". 1094 1095config BOOTPARAM_SOFTLOCKUP_PANIC 1096 bool "Panic (Reboot) On Soft Lockups" 1097 depends on SOFTLOCKUP_DETECTOR 1098 help 1099 Say Y here to enable the kernel to panic on "soft lockups", 1100 which are bugs that cause the kernel to loop in kernel 1101 mode for more than 20 seconds (configurable using the watchdog_thresh 1102 sysctl), without giving other tasks a chance to run. 1103 1104 The panic can be used in combination with panic_timeout, 1105 to cause the system to reboot automatically after a 1106 lockup has been detected. This feature is useful for 1107 high-availability systems that have uptime guarantees and 1108 where a lockup must be resolved ASAP. 1109 1110 Say N if unsure. 1111 1112config HAVE_HARDLOCKUP_DETECTOR_BUDDY 1113 bool 1114 depends on SMP 1115 default y 1116 1117# 1118# Global switch whether to build a hardlockup detector at all. It is available 1119# only when the architecture supports at least one implementation. There are 1120# two exceptions. The hardlockup detector is never enabled on: 1121# 1122# s390: it reported many false positives there 1123# 1124# sparc64: has a custom implementation which is not using the common 1125# hardlockup command line options and sysctl interface. 1126# 1127config HARDLOCKUP_DETECTOR 1128 bool "Detect Hard Lockups" 1129 depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64 1130 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH 1131 imply HARDLOCKUP_DETECTOR_PERF 1132 imply HARDLOCKUP_DETECTOR_BUDDY 1133 imply HARDLOCKUP_DETECTOR_ARCH 1134 select LOCKUP_DETECTOR 1135 1136 help 1137 Say Y here to enable the kernel to act as a watchdog to detect 1138 hard lockups. 1139 1140 Hardlockups are bugs that cause the CPU to loop in kernel mode 1141 for more than 10 seconds, without letting other interrupts have a 1142 chance to run. The current stack trace is displayed upon detection 1143 and the system will stay locked up. 1144 1145# 1146# Note that arch-specific variants are always preferred. 1147# 1148config HARDLOCKUP_DETECTOR_PREFER_BUDDY 1149 bool "Prefer the buddy CPU hardlockup detector" 1150 depends on HARDLOCKUP_DETECTOR 1151 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY 1152 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1153 help 1154 Say Y here to prefer the buddy hardlockup detector over the perf one. 1155 1156 With the buddy detector, each CPU uses its softlockup hrtimer 1157 to check that the next CPU is processing hrtimer interrupts by 1158 verifying that a counter is increasing. 1159 1160 This hardlockup detector is useful on systems that don't have 1161 an arch-specific hardlockup detector or if resources needed 1162 for the hardlockup detector are better used for other things. 1163 1164config HARDLOCKUP_DETECTOR_PERF 1165 bool 1166 depends on HARDLOCKUP_DETECTOR 1167 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY 1168 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1169 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1170 1171config HARDLOCKUP_DETECTOR_BUDDY 1172 bool 1173 depends on HARDLOCKUP_DETECTOR 1174 depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY 1175 depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY 1176 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1177 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1178 1179config HARDLOCKUP_DETECTOR_ARCH 1180 bool 1181 depends on HARDLOCKUP_DETECTOR 1182 depends on HAVE_HARDLOCKUP_DETECTOR_ARCH 1183 help 1184 The arch-specific implementation of the hardlockup detector will 1185 be used. 1186 1187# 1188# Both the "perf" and "buddy" hardlockup detectors count hrtimer 1189# interrupts. This config enables functions managing this common code. 1190# 1191config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1192 bool 1193 select SOFTLOCKUP_DETECTOR 1194 1195# 1196# Enables a timestamp based low pass filter to compensate for perf based 1197# hard lockup detection which runs too fast due to turbo modes. 1198# 1199config HARDLOCKUP_CHECK_TIMESTAMP 1200 bool 1201 1202config BOOTPARAM_HARDLOCKUP_PANIC 1203 bool "Panic (Reboot) On Hard Lockups" 1204 depends on HARDLOCKUP_DETECTOR 1205 help 1206 Say Y here to enable the kernel to panic on "hard lockups", 1207 which are bugs that cause the kernel to loop in kernel 1208 mode with interrupts disabled for more than 10 seconds (configurable 1209 using the watchdog_thresh sysctl). 1210 1211 Say N if unsure. 1212 1213config DETECT_HUNG_TASK 1214 bool "Detect Hung Tasks" 1215 depends on DEBUG_KERNEL 1216 default SOFTLOCKUP_DETECTOR 1217 help 1218 Say Y here to enable the kernel to detect "hung tasks", 1219 which are bugs that cause the task to be stuck in 1220 uninterruptible "D" state indefinitely. 1221 1222 When a hung task is detected, the kernel will print the 1223 current stack trace (which you should report), but the 1224 task will stay in uninterruptible state. If lockdep is 1225 enabled then all held locks will also be reported. This 1226 feature has negligible overhead. 1227 1228config DEFAULT_HUNG_TASK_TIMEOUT 1229 int "Default timeout for hung task detection (in seconds)" 1230 depends on DETECT_HUNG_TASK 1231 default 120 1232 help 1233 This option controls the default timeout (in seconds) used 1234 to determine when a task has become non-responsive and should 1235 be considered hung. 1236 1237 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 1238 sysctl or by writing a value to 1239 /proc/sys/kernel/hung_task_timeout_secs. 1240 1241 A timeout of 0 disables the check. The default is two minutes. 1242 Keeping the default should be fine in most cases. 1243 1244config BOOTPARAM_HUNG_TASK_PANIC 1245 bool "Panic (Reboot) On Hung Tasks" 1246 depends on DETECT_HUNG_TASK 1247 help 1248 Say Y here to enable the kernel to panic on "hung tasks", 1249 which are bugs that cause the kernel to leave a task stuck 1250 in uninterruptible "D" state. 1251 1252 The panic can be used in combination with panic_timeout, 1253 to cause the system to reboot automatically after a 1254 hung task has been detected. This feature is useful for 1255 high-availability systems that have uptime guarantees and 1256 where a hung tasks must be resolved ASAP. 1257 1258 Say N if unsure. 1259 1260config WQ_WATCHDOG 1261 bool "Detect Workqueue Stalls" 1262 depends on DEBUG_KERNEL 1263 help 1264 Say Y here to enable stall detection on workqueues. If a 1265 worker pool doesn't make forward progress on a pending work 1266 item for over a given amount of time, 30s by default, a 1267 warning message is printed along with dump of workqueue 1268 state. This can be configured through kernel parameter 1269 "workqueue.watchdog_thresh" and its sysfs counterpart. 1270 1271config WQ_CPU_INTENSIVE_REPORT 1272 bool "Report per-cpu work items which hog CPU for too long" 1273 depends on DEBUG_KERNEL 1274 help 1275 Say Y here to enable reporting of concurrency-managed per-cpu work 1276 items that hog CPUs for longer than 1277 workqueue.cpu_intensive_thresh_us. Workqueue automatically 1278 detects and excludes them from concurrency management to prevent 1279 them from stalling other per-cpu work items. Occassional 1280 triggering may not necessarily indicate a problem. Repeated 1281 triggering likely indicates that the work item should be switched 1282 to use an unbound workqueue. 1283 1284config TEST_LOCKUP 1285 tristate "Test module to generate lockups" 1286 depends on m 1287 help 1288 This builds the "test_lockup" module that helps to make sure 1289 that watchdogs and lockup detectors are working properly. 1290 1291 Depending on module parameters it could emulate soft or hard 1292 lockup, "hung task", or locking arbitrary lock for a long time. 1293 Also it could generate series of lockups with cooling-down periods. 1294 1295 If unsure, say N. 1296 1297endmenu # "Debug lockups and hangs" 1298 1299menu "Scheduler Debugging" 1300 1301config SCHED_DEBUG 1302 bool "Collect scheduler debugging info" 1303 depends on DEBUG_KERNEL && DEBUG_FS 1304 default y 1305 help 1306 If you say Y here, the /sys/kernel/debug/sched file will be provided 1307 that can help debug the scheduler. The runtime overhead of this 1308 option is minimal. 1309 1310config SCHED_INFO 1311 bool 1312 default n 1313 1314config SCHEDSTATS 1315 bool "Collect scheduler statistics" 1316 depends on PROC_FS 1317 select SCHED_INFO 1318 help 1319 If you say Y here, additional code will be inserted into the 1320 scheduler and related routines to collect statistics about 1321 scheduler behavior and provide them in /proc/schedstat. These 1322 stats may be useful for both tuning and debugging the scheduler 1323 If you aren't debugging the scheduler or trying to tune a specific 1324 application, you can say N to avoid the very slight overhead 1325 this adds. 1326 1327endmenu 1328 1329config DEBUG_TIMEKEEPING 1330 bool "Enable extra timekeeping sanity checking" 1331 help 1332 This option will enable additional timekeeping sanity checks 1333 which may be helpful when diagnosing issues where timekeeping 1334 problems are suspected. 1335 1336 This may include checks in the timekeeping hotpaths, so this 1337 option may have a (very small) performance impact to some 1338 workloads. 1339 1340 If unsure, say N. 1341 1342config DEBUG_PREEMPT 1343 bool "Debug preemptible kernel" 1344 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1345 help 1346 If you say Y here then the kernel will use a debug variant of the 1347 commonly used smp_processor_id() function and will print warnings 1348 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1349 will detect preemption count underflows. 1350 1351 This option has potential to introduce high runtime overhead, 1352 depending on workload as it triggers debugging routines for each 1353 this_cpu operation. It should only be used for debugging purposes. 1354 1355menu "Lock Debugging (spinlocks, mutexes, etc...)" 1356 1357config LOCK_DEBUGGING_SUPPORT 1358 bool 1359 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1360 default y 1361 1362config PROVE_LOCKING 1363 bool "Lock debugging: prove locking correctness" 1364 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1365 select LOCKDEP 1366 select DEBUG_SPINLOCK 1367 select DEBUG_MUTEXES if !PREEMPT_RT 1368 select DEBUG_RT_MUTEXES if RT_MUTEXES 1369 select DEBUG_RWSEMS if !PREEMPT_RT 1370 select DEBUG_WW_MUTEX_SLOWPATH 1371 select DEBUG_LOCK_ALLOC 1372 select PREEMPT_COUNT if !ARCH_NO_PREEMPT 1373 select TRACE_IRQFLAGS 1374 default n 1375 help 1376 This feature enables the kernel to prove that all locking 1377 that occurs in the kernel runtime is mathematically 1378 correct: that under no circumstance could an arbitrary (and 1379 not yet triggered) combination of observed locking 1380 sequences (on an arbitrary number of CPUs, running an 1381 arbitrary number of tasks and interrupt contexts) cause a 1382 deadlock. 1383 1384 In short, this feature enables the kernel to report locking 1385 related deadlocks before they actually occur. 1386 1387 The proof does not depend on how hard and complex a 1388 deadlock scenario would be to trigger: how many 1389 participant CPUs, tasks and irq-contexts would be needed 1390 for it to trigger. The proof also does not depend on 1391 timing: if a race and a resulting deadlock is possible 1392 theoretically (no matter how unlikely the race scenario 1393 is), it will be proven so and will immediately be 1394 reported by the kernel (once the event is observed that 1395 makes the deadlock theoretically possible). 1396 1397 If a deadlock is impossible (i.e. the locking rules, as 1398 observed by the kernel, are mathematically correct), the 1399 kernel reports nothing. 1400 1401 NOTE: this feature can also be enabled for rwlocks, mutexes 1402 and rwsems - in which case all dependencies between these 1403 different locking variants are observed and mapped too, and 1404 the proof of observed correctness is also maintained for an 1405 arbitrary combination of these separate locking variants. 1406 1407 For more details, see Documentation/locking/lockdep-design.rst. 1408 1409config PROVE_RAW_LOCK_NESTING 1410 bool "Enable raw_spinlock - spinlock nesting checks" 1411 depends on PROVE_LOCKING 1412 default n 1413 help 1414 Enable the raw_spinlock vs. spinlock nesting checks which ensure 1415 that the lock nesting rules for PREEMPT_RT enabled kernels are 1416 not violated. 1417 1418 NOTE: There are known nesting problems. So if you enable this 1419 option expect lockdep splats until these problems have been fully 1420 addressed which is work in progress. This config switch allows to 1421 identify and analyze these problems. It will be removed and the 1422 check permanently enabled once the main issues have been fixed. 1423 1424 If unsure, select N. 1425 1426config LOCK_STAT 1427 bool "Lock usage statistics" 1428 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1429 select LOCKDEP 1430 select DEBUG_SPINLOCK 1431 select DEBUG_MUTEXES if !PREEMPT_RT 1432 select DEBUG_RT_MUTEXES if RT_MUTEXES 1433 select DEBUG_LOCK_ALLOC 1434 default n 1435 help 1436 This feature enables tracking lock contention points 1437 1438 For more details, see Documentation/locking/lockstat.rst 1439 1440 This also enables lock events required by "perf lock", 1441 subcommand of perf. 1442 If you want to use "perf lock", you also need to turn on 1443 CONFIG_EVENT_TRACING. 1444 1445 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1446 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1447 1448config DEBUG_RT_MUTEXES 1449 bool "RT Mutex debugging, deadlock detection" 1450 depends on DEBUG_KERNEL && RT_MUTEXES 1451 help 1452 This allows rt mutex semantics violations and rt mutex related 1453 deadlocks (lockups) to be detected and reported automatically. 1454 1455config DEBUG_SPINLOCK 1456 bool "Spinlock and rw-lock debugging: basic checks" 1457 depends on DEBUG_KERNEL 1458 select UNINLINE_SPIN_UNLOCK 1459 help 1460 Say Y here and build SMP to catch missing spinlock initialization 1461 and certain other kinds of spinlock errors commonly made. This is 1462 best used in conjunction with the NMI watchdog so that spinlock 1463 deadlocks are also debuggable. 1464 1465config DEBUG_MUTEXES 1466 bool "Mutex debugging: basic checks" 1467 depends on DEBUG_KERNEL && !PREEMPT_RT 1468 help 1469 This feature allows mutex semantics violations to be detected and 1470 reported. 1471 1472config DEBUG_WW_MUTEX_SLOWPATH 1473 bool "Wait/wound mutex debugging: Slowpath testing" 1474 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1475 select DEBUG_LOCK_ALLOC 1476 select DEBUG_SPINLOCK 1477 select DEBUG_MUTEXES if !PREEMPT_RT 1478 select DEBUG_RT_MUTEXES if PREEMPT_RT 1479 help 1480 This feature enables slowpath testing for w/w mutex users by 1481 injecting additional -EDEADLK wound/backoff cases. Together with 1482 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1483 will test all possible w/w mutex interface abuse with the 1484 exception of simply not acquiring all the required locks. 1485 Note that this feature can introduce significant overhead, so 1486 it really should not be enabled in a production or distro kernel, 1487 even a debug kernel. If you are a driver writer, enable it. If 1488 you are a distro, do not. 1489 1490config DEBUG_RWSEMS 1491 bool "RW Semaphore debugging: basic checks" 1492 depends on DEBUG_KERNEL && !PREEMPT_RT 1493 help 1494 This debugging feature allows mismatched rw semaphore locks 1495 and unlocks to be detected and reported. 1496 1497config DEBUG_LOCK_ALLOC 1498 bool "Lock debugging: detect incorrect freeing of live locks" 1499 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1500 select DEBUG_SPINLOCK 1501 select DEBUG_MUTEXES if !PREEMPT_RT 1502 select DEBUG_RT_MUTEXES if RT_MUTEXES 1503 select LOCKDEP 1504 help 1505 This feature will check whether any held lock (spinlock, rwlock, 1506 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1507 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1508 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1509 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1510 held during task exit. 1511 1512config LOCKDEP 1513 bool 1514 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1515 select STACKTRACE 1516 select KALLSYMS 1517 select KALLSYMS_ALL 1518 1519config LOCKDEP_SMALL 1520 bool 1521 1522config LOCKDEP_BITS 1523 int "Bitsize for MAX_LOCKDEP_ENTRIES" 1524 depends on LOCKDEP && !LOCKDEP_SMALL 1525 range 10 30 1526 default 15 1527 help 1528 Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message. 1529 1530config LOCKDEP_CHAINS_BITS 1531 int "Bitsize for MAX_LOCKDEP_CHAINS" 1532 depends on LOCKDEP && !LOCKDEP_SMALL 1533 range 10 30 1534 default 16 1535 help 1536 Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message. 1537 1538config LOCKDEP_STACK_TRACE_BITS 1539 int "Bitsize for MAX_STACK_TRACE_ENTRIES" 1540 depends on LOCKDEP && !LOCKDEP_SMALL 1541 range 10 30 1542 default 19 1543 help 1544 Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message. 1545 1546config LOCKDEP_STACK_TRACE_HASH_BITS 1547 int "Bitsize for STACK_TRACE_HASH_SIZE" 1548 depends on LOCKDEP && !LOCKDEP_SMALL 1549 range 10 30 1550 default 14 1551 help 1552 Try increasing this value if you need large STACK_TRACE_HASH_SIZE. 1553 1554config LOCKDEP_CIRCULAR_QUEUE_BITS 1555 int "Bitsize for elements in circular_queue struct" 1556 depends on LOCKDEP 1557 range 10 30 1558 default 12 1559 help 1560 Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure. 1561 1562config DEBUG_LOCKDEP 1563 bool "Lock dependency engine debugging" 1564 depends on DEBUG_KERNEL && LOCKDEP 1565 select DEBUG_IRQFLAGS 1566 help 1567 If you say Y here, the lock dependency engine will do 1568 additional runtime checks to debug itself, at the price 1569 of more runtime overhead. 1570 1571config DEBUG_ATOMIC_SLEEP 1572 bool "Sleep inside atomic section checking" 1573 select PREEMPT_COUNT 1574 depends on DEBUG_KERNEL 1575 depends on !ARCH_NO_PREEMPT 1576 help 1577 If you say Y here, various routines which may sleep will become very 1578 noisy if they are called inside atomic sections: when a spinlock is 1579 held, inside an rcu read side critical section, inside preempt disabled 1580 sections, inside an interrupt, etc... 1581 1582config DEBUG_LOCKING_API_SELFTESTS 1583 bool "Locking API boot-time self-tests" 1584 depends on DEBUG_KERNEL 1585 help 1586 Say Y here if you want the kernel to run a short self-test during 1587 bootup. The self-test checks whether common types of locking bugs 1588 are detected by debugging mechanisms or not. (if you disable 1589 lock debugging then those bugs won't be detected of course.) 1590 The following locking APIs are covered: spinlocks, rwlocks, 1591 mutexes and rwsems. 1592 1593config LOCK_TORTURE_TEST 1594 tristate "torture tests for locking" 1595 depends on DEBUG_KERNEL 1596 select TORTURE_TEST 1597 help 1598 This option provides a kernel module that runs torture tests 1599 on kernel locking primitives. The kernel module may be built 1600 after the fact on the running kernel to be tested, if desired. 1601 1602 Say Y here if you want kernel locking-primitive torture tests 1603 to be built into the kernel. 1604 Say M if you want these torture tests to build as a module. 1605 Say N if you are unsure. 1606 1607config WW_MUTEX_SELFTEST 1608 tristate "Wait/wound mutex selftests" 1609 help 1610 This option provides a kernel module that runs tests on the 1611 on the struct ww_mutex locking API. 1612 1613 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1614 with this test harness. 1615 1616 Say M if you want these self tests to build as a module. 1617 Say N if you are unsure. 1618 1619config SCF_TORTURE_TEST 1620 tristate "torture tests for smp_call_function*()" 1621 depends on DEBUG_KERNEL 1622 select TORTURE_TEST 1623 help 1624 This option provides a kernel module that runs torture tests 1625 on the smp_call_function() family of primitives. The kernel 1626 module may be built after the fact on the running kernel to 1627 be tested, if desired. 1628 1629config CSD_LOCK_WAIT_DEBUG 1630 bool "Debugging for csd_lock_wait(), called from smp_call_function*()" 1631 depends on DEBUG_KERNEL 1632 depends on 64BIT 1633 default n 1634 help 1635 This option enables debug prints when CPUs are slow to respond 1636 to the smp_call_function*() IPI wrappers. These debug prints 1637 include the IPI handler function currently executing (if any) 1638 and relevant stack traces. 1639 1640config CSD_LOCK_WAIT_DEBUG_DEFAULT 1641 bool "Default csd_lock_wait() debugging on at boot time" 1642 depends on CSD_LOCK_WAIT_DEBUG 1643 depends on 64BIT 1644 default n 1645 help 1646 This option causes the csdlock_debug= kernel boot parameter to 1647 default to 1 (basic debugging) instead of 0 (no debugging). 1648 1649endmenu # lock debugging 1650 1651config TRACE_IRQFLAGS 1652 depends on TRACE_IRQFLAGS_SUPPORT 1653 bool 1654 help 1655 Enables hooks to interrupt enabling and disabling for 1656 either tracing or lock debugging. 1657 1658config TRACE_IRQFLAGS_NMI 1659 def_bool y 1660 depends on TRACE_IRQFLAGS 1661 depends on TRACE_IRQFLAGS_NMI_SUPPORT 1662 1663config NMI_CHECK_CPU 1664 bool "Debugging for CPUs failing to respond to backtrace requests" 1665 depends on DEBUG_KERNEL 1666 depends on X86 1667 default n 1668 help 1669 Enables debug prints when a CPU fails to respond to a given 1670 backtrace NMI. These prints provide some reasons why a CPU 1671 might legitimately be failing to respond, for example, if it 1672 is offline of if ignore_nmis is set. 1673 1674config DEBUG_IRQFLAGS 1675 bool "Debug IRQ flag manipulation" 1676 help 1677 Enables checks for potentially unsafe enabling or disabling of 1678 interrupts, such as calling raw_local_irq_restore() when interrupts 1679 are enabled. 1680 1681config STACKTRACE 1682 bool "Stack backtrace support" 1683 depends on STACKTRACE_SUPPORT 1684 help 1685 This option causes the kernel to create a /proc/pid/stack for 1686 every process, showing its current stack trace. 1687 It is also used by various kernel debugging features that require 1688 stack trace generation. 1689 1690config WARN_ALL_UNSEEDED_RANDOM 1691 bool "Warn for all uses of unseeded randomness" 1692 default n 1693 help 1694 Some parts of the kernel contain bugs relating to their use of 1695 cryptographically secure random numbers before it's actually possible 1696 to generate those numbers securely. This setting ensures that these 1697 flaws don't go unnoticed, by enabling a message, should this ever 1698 occur. This will allow people with obscure setups to know when things 1699 are going wrong, so that they might contact developers about fixing 1700 it. 1701 1702 Unfortunately, on some models of some architectures getting 1703 a fully seeded CRNG is extremely difficult, and so this can 1704 result in dmesg getting spammed for a surprisingly long 1705 time. This is really bad from a security perspective, and 1706 so architecture maintainers really need to do what they can 1707 to get the CRNG seeded sooner after the system is booted. 1708 However, since users cannot do anything actionable to 1709 address this, by default this option is disabled. 1710 1711 Say Y here if you want to receive warnings for all uses of 1712 unseeded randomness. This will be of use primarily for 1713 those developers interested in improving the security of 1714 Linux kernels running on their architecture (or 1715 subarchitecture). 1716 1717config DEBUG_KOBJECT 1718 bool "kobject debugging" 1719 depends on DEBUG_KERNEL 1720 help 1721 If you say Y here, some extra kobject debugging messages will be sent 1722 to the syslog. 1723 1724config DEBUG_KOBJECT_RELEASE 1725 bool "kobject release debugging" 1726 depends on DEBUG_OBJECTS_TIMERS 1727 help 1728 kobjects are reference counted objects. This means that their 1729 last reference count put is not predictable, and the kobject can 1730 live on past the point at which a driver decides to drop its 1731 initial reference to the kobject gained on allocation. An 1732 example of this would be a struct device which has just been 1733 unregistered. 1734 1735 However, some buggy drivers assume that after such an operation, 1736 the memory backing the kobject can be immediately freed. This 1737 goes completely against the principles of a refcounted object. 1738 1739 If you say Y here, the kernel will delay the release of kobjects 1740 on the last reference count to improve the visibility of this 1741 kind of kobject release bug. 1742 1743config HAVE_DEBUG_BUGVERBOSE 1744 bool 1745 1746menu "Debug kernel data structures" 1747 1748config DEBUG_LIST 1749 bool "Debug linked list manipulation" 1750 depends on DEBUG_KERNEL 1751 select LIST_HARDENED 1752 help 1753 Enable this to turn on extended checks in the linked-list walking 1754 routines. 1755 1756 This option trades better quality error reports for performance, and 1757 is more suitable for kernel debugging. If you care about performance, 1758 you should only enable CONFIG_LIST_HARDENED instead. 1759 1760 If unsure, say N. 1761 1762config DEBUG_PLIST 1763 bool "Debug priority linked list manipulation" 1764 depends on DEBUG_KERNEL 1765 help 1766 Enable this to turn on extended checks in the priority-ordered 1767 linked-list (plist) walking routines. This checks the entire 1768 list multiple times during each manipulation. 1769 1770 If unsure, say N. 1771 1772config DEBUG_SG 1773 bool "Debug SG table operations" 1774 depends on DEBUG_KERNEL 1775 help 1776 Enable this to turn on checks on scatter-gather tables. This can 1777 help find problems with drivers that do not properly initialize 1778 their sg tables. 1779 1780 If unsure, say N. 1781 1782config DEBUG_NOTIFIERS 1783 bool "Debug notifier call chains" 1784 depends on DEBUG_KERNEL 1785 help 1786 Enable this to turn on sanity checking for notifier call chains. 1787 This is most useful for kernel developers to make sure that 1788 modules properly unregister themselves from notifier chains. 1789 This is a relatively cheap check but if you care about maximum 1790 performance, say N. 1791 1792config DEBUG_CLOSURES 1793 bool "Debug closures (bcache async widgits)" 1794 depends on CLOSURES 1795 select DEBUG_FS 1796 help 1797 Keeps all active closures in a linked list and provides a debugfs 1798 interface to list them, which makes it possible to see asynchronous 1799 operations that get stuck. 1800 1801config DEBUG_MAPLE_TREE 1802 bool "Debug maple trees" 1803 depends on DEBUG_KERNEL 1804 help 1805 Enable maple tree debugging information and extra validations. 1806 1807 If unsure, say N. 1808 1809endmenu 1810 1811source "kernel/rcu/Kconfig.debug" 1812 1813config DEBUG_WQ_FORCE_RR_CPU 1814 bool "Force round-robin CPU selection for unbound work items" 1815 depends on DEBUG_KERNEL 1816 default n 1817 help 1818 Workqueue used to implicitly guarantee that work items queued 1819 without explicit CPU specified are put on the local CPU. This 1820 guarantee is no longer true and while local CPU is still 1821 preferred work items may be put on foreign CPUs. Kernel 1822 parameter "workqueue.debug_force_rr_cpu" is added to force 1823 round-robin CPU selection to flush out usages which depend on the 1824 now broken guarantee. This config option enables the debug 1825 feature by default. When enabled, memory and cache locality will 1826 be impacted. 1827 1828config CPU_HOTPLUG_STATE_CONTROL 1829 bool "Enable CPU hotplug state control" 1830 depends on DEBUG_KERNEL 1831 depends on HOTPLUG_CPU 1832 default n 1833 help 1834 Allows to write steps between "offline" and "online" to the CPUs 1835 sysfs target file so states can be stepped granular. This is a debug 1836 option for now as the hotplug machinery cannot be stopped and 1837 restarted at arbitrary points yet. 1838 1839 Say N if your are unsure. 1840 1841config LATENCYTOP 1842 bool "Latency measuring infrastructure" 1843 depends on DEBUG_KERNEL 1844 depends on STACKTRACE_SUPPORT 1845 depends on PROC_FS 1846 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 1847 select KALLSYMS 1848 select KALLSYMS_ALL 1849 select STACKTRACE 1850 select SCHEDSTATS 1851 help 1852 Enable this option if you want to use the LatencyTOP tool 1853 to find out which userspace is blocking on what kernel operations. 1854 1855config DEBUG_CGROUP_REF 1856 bool "Disable inlining of cgroup css reference count functions" 1857 depends on DEBUG_KERNEL 1858 depends on CGROUPS 1859 depends on KPROBES 1860 default n 1861 help 1862 Force cgroup css reference count functions to not be inlined so 1863 that they can be kprobed for debugging. 1864 1865source "kernel/trace/Kconfig" 1866 1867config PROVIDE_OHCI1394_DMA_INIT 1868 bool "Remote debugging over FireWire early on boot" 1869 depends on PCI && X86 1870 help 1871 If you want to debug problems which hang or crash the kernel early 1872 on boot and the crashing machine has a FireWire port, you can use 1873 this feature to remotely access the memory of the crashed machine 1874 over FireWire. This employs remote DMA as part of the OHCI1394 1875 specification which is now the standard for FireWire controllers. 1876 1877 With remote DMA, you can monitor the printk buffer remotely using 1878 firescope and access all memory below 4GB using fireproxy from gdb. 1879 Even controlling a kernel debugger is possible using remote DMA. 1880 1881 Usage: 1882 1883 If ohci1394_dma=early is used as boot parameter, it will initialize 1884 all OHCI1394 controllers which are found in the PCI config space. 1885 1886 As all changes to the FireWire bus such as enabling and disabling 1887 devices cause a bus reset and thereby disable remote DMA for all 1888 devices, be sure to have the cable plugged and FireWire enabled on 1889 the debugging host before booting the debug target for debugging. 1890 1891 This code (~1k) is freed after boot. By then, the firewire stack 1892 in charge of the OHCI-1394 controllers should be used instead. 1893 1894 See Documentation/core-api/debugging-via-ohci1394.rst for more information. 1895 1896source "samples/Kconfig" 1897 1898config ARCH_HAS_DEVMEM_IS_ALLOWED 1899 bool 1900 1901config STRICT_DEVMEM 1902 bool "Filter access to /dev/mem" 1903 depends on MMU && DEVMEM 1904 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED 1905 default y if PPC || X86 || ARM64 1906 help 1907 If this option is disabled, you allow userspace (root) access to all 1908 of memory, including kernel and userspace memory. Accidental 1909 access to this is obviously disastrous, but specific access can 1910 be used by people debugging the kernel. Note that with PAT support 1911 enabled, even in this case there are restrictions on /dev/mem 1912 use due to the cache aliasing requirements. 1913 1914 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 1915 file only allows userspace access to PCI space and the BIOS code and 1916 data regions. This is sufficient for dosemu and X and all common 1917 users of /dev/mem. 1918 1919 If in doubt, say Y. 1920 1921config IO_STRICT_DEVMEM 1922 bool "Filter I/O access to /dev/mem" 1923 depends on STRICT_DEVMEM 1924 help 1925 If this option is disabled, you allow userspace (root) access to all 1926 io-memory regardless of whether a driver is actively using that 1927 range. Accidental access to this is obviously disastrous, but 1928 specific access can be used by people debugging kernel drivers. 1929 1930 If this option is switched on, the /dev/mem file only allows 1931 userspace access to *idle* io-memory ranges (see /proc/iomem) This 1932 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 1933 if the driver using a given range cannot be disabled. 1934 1935 If in doubt, say Y. 1936 1937menu "$(SRCARCH) Debugging" 1938 1939source "arch/$(SRCARCH)/Kconfig.debug" 1940 1941endmenu 1942 1943menu "Kernel Testing and Coverage" 1944 1945source "lib/kunit/Kconfig" 1946 1947config NOTIFIER_ERROR_INJECTION 1948 tristate "Notifier error injection" 1949 depends on DEBUG_KERNEL 1950 select DEBUG_FS 1951 help 1952 This option provides the ability to inject artificial errors to 1953 specified notifier chain callbacks. It is useful to test the error 1954 handling of notifier call chain failures. 1955 1956 Say N if unsure. 1957 1958config PM_NOTIFIER_ERROR_INJECT 1959 tristate "PM notifier error injection module" 1960 depends on PM && NOTIFIER_ERROR_INJECTION 1961 default m if PM_DEBUG 1962 help 1963 This option provides the ability to inject artificial errors to 1964 PM notifier chain callbacks. It is controlled through debugfs 1965 interface /sys/kernel/debug/notifier-error-inject/pm 1966 1967 If the notifier call chain should be failed with some events 1968 notified, write the error code to "actions/<notifier event>/error". 1969 1970 Example: Inject PM suspend error (-12 = -ENOMEM) 1971 1972 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1973 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1974 # echo mem > /sys/power/state 1975 bash: echo: write error: Cannot allocate memory 1976 1977 To compile this code as a module, choose M here: the module will 1978 be called pm-notifier-error-inject. 1979 1980 If unsure, say N. 1981 1982config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1983 tristate "OF reconfig notifier error injection module" 1984 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1985 help 1986 This option provides the ability to inject artificial errors to 1987 OF reconfig notifier chain callbacks. It is controlled 1988 through debugfs interface under 1989 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1990 1991 If the notifier call chain should be failed with some events 1992 notified, write the error code to "actions/<notifier event>/error". 1993 1994 To compile this code as a module, choose M here: the module will 1995 be called of-reconfig-notifier-error-inject. 1996 1997 If unsure, say N. 1998 1999config NETDEV_NOTIFIER_ERROR_INJECT 2000 tristate "Netdev notifier error injection module" 2001 depends on NET && NOTIFIER_ERROR_INJECTION 2002 help 2003 This option provides the ability to inject artificial errors to 2004 netdevice notifier chain callbacks. It is controlled through debugfs 2005 interface /sys/kernel/debug/notifier-error-inject/netdev 2006 2007 If the notifier call chain should be failed with some events 2008 notified, write the error code to "actions/<notifier event>/error". 2009 2010 Example: Inject netdevice mtu change error (-22 = -EINVAL) 2011 2012 # cd /sys/kernel/debug/notifier-error-inject/netdev 2013 # echo -22 > actions/NETDEV_CHANGEMTU/error 2014 # ip link set eth0 mtu 1024 2015 RTNETLINK answers: Invalid argument 2016 2017 To compile this code as a module, choose M here: the module will 2018 be called netdev-notifier-error-inject. 2019 2020 If unsure, say N. 2021 2022config FUNCTION_ERROR_INJECTION 2023 bool "Fault-injections of functions" 2024 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 2025 help 2026 Add fault injections into various functions that are annotated with 2027 ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return 2028 value of these functions. This is useful to test error paths of code. 2029 2030 If unsure, say N 2031 2032config FAULT_INJECTION 2033 bool "Fault-injection framework" 2034 depends on DEBUG_KERNEL 2035 help 2036 Provide fault-injection framework. 2037 For more details, see Documentation/fault-injection/. 2038 2039config FAILSLAB 2040 bool "Fault-injection capability for kmalloc" 2041 depends on FAULT_INJECTION 2042 help 2043 Provide fault-injection capability for kmalloc. 2044 2045config FAIL_PAGE_ALLOC 2046 bool "Fault-injection capability for alloc_pages()" 2047 depends on FAULT_INJECTION 2048 help 2049 Provide fault-injection capability for alloc_pages(). 2050 2051config FAULT_INJECTION_USERCOPY 2052 bool "Fault injection capability for usercopy functions" 2053 depends on FAULT_INJECTION 2054 help 2055 Provides fault-injection capability to inject failures 2056 in usercopy functions (copy_from_user(), get_user(), ...). 2057 2058config FAIL_MAKE_REQUEST 2059 bool "Fault-injection capability for disk IO" 2060 depends on FAULT_INJECTION && BLOCK 2061 help 2062 Provide fault-injection capability for disk IO. 2063 2064config FAIL_IO_TIMEOUT 2065 bool "Fault-injection capability for faking disk interrupts" 2066 depends on FAULT_INJECTION && BLOCK 2067 help 2068 Provide fault-injection capability on end IO handling. This 2069 will make the block layer "forget" an interrupt as configured, 2070 thus exercising the error handling. 2071 2072 Only works with drivers that use the generic timeout handling, 2073 for others it won't do anything. 2074 2075config FAIL_FUTEX 2076 bool "Fault-injection capability for futexes" 2077 select DEBUG_FS 2078 depends on FAULT_INJECTION && FUTEX 2079 help 2080 Provide fault-injection capability for futexes. 2081 2082config FAULT_INJECTION_DEBUG_FS 2083 bool "Debugfs entries for fault-injection capabilities" 2084 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 2085 help 2086 Enable configuration of fault-injection capabilities via debugfs. 2087 2088config FAIL_FUNCTION 2089 bool "Fault-injection capability for functions" 2090 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 2091 help 2092 Provide function-based fault-injection capability. 2093 This will allow you to override a specific function with a return 2094 with given return value. As a result, function caller will see 2095 an error value and have to handle it. This is useful to test the 2096 error handling in various subsystems. 2097 2098config FAIL_MMC_REQUEST 2099 bool "Fault-injection capability for MMC IO" 2100 depends on FAULT_INJECTION_DEBUG_FS && MMC 2101 help 2102 Provide fault-injection capability for MMC IO. 2103 This will make the mmc core return data errors. This is 2104 useful to test the error handling in the mmc block device 2105 and to test how the mmc host driver handles retries from 2106 the block device. 2107 2108config FAIL_SUNRPC 2109 bool "Fault-injection capability for SunRPC" 2110 depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG 2111 help 2112 Provide fault-injection capability for SunRPC and 2113 its consumers. 2114 2115config FAULT_INJECTION_CONFIGFS 2116 bool "Configfs interface for fault-injection capabilities" 2117 depends on FAULT_INJECTION 2118 select CONFIGFS_FS 2119 help 2120 This option allows configfs-based drivers to dynamically configure 2121 fault-injection via configfs. Each parameter for driver-specific 2122 fault-injection can be made visible as a configfs attribute in a 2123 configfs group. 2124 2125 2126config FAULT_INJECTION_STACKTRACE_FILTER 2127 bool "stacktrace filter for fault-injection capabilities" 2128 depends on FAULT_INJECTION 2129 depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT 2130 select STACKTRACE 2131 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 2132 help 2133 Provide stacktrace filter for fault-injection capabilities 2134 2135config ARCH_HAS_KCOV 2136 bool 2137 help 2138 An architecture should select this when it can successfully 2139 build and run with CONFIG_KCOV. This typically requires 2140 disabling instrumentation for some early boot code. 2141 2142config CC_HAS_SANCOV_TRACE_PC 2143 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 2144 2145 2146config KCOV 2147 bool "Code coverage for fuzzing" 2148 depends on ARCH_HAS_KCOV 2149 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 2150 depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \ 2151 GCC_VERSION >= 120000 || CC_IS_CLANG 2152 select DEBUG_FS 2153 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 2154 select OBJTOOL if HAVE_NOINSTR_HACK 2155 help 2156 KCOV exposes kernel code coverage information in a form suitable 2157 for coverage-guided fuzzing (randomized testing). 2158 2159 For more details, see Documentation/dev-tools/kcov.rst. 2160 2161config KCOV_ENABLE_COMPARISONS 2162 bool "Enable comparison operands collection by KCOV" 2163 depends on KCOV 2164 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 2165 help 2166 KCOV also exposes operands of every comparison in the instrumented 2167 code along with operand sizes and PCs of the comparison instructions. 2168 These operands can be used by fuzzing engines to improve the quality 2169 of fuzzing coverage. 2170 2171config KCOV_INSTRUMENT_ALL 2172 bool "Instrument all code by default" 2173 depends on KCOV 2174 default y 2175 help 2176 If you are doing generic system call fuzzing (like e.g. syzkaller), 2177 then you will want to instrument the whole kernel and you should 2178 say y here. If you are doing more targeted fuzzing (like e.g. 2179 filesystem fuzzing with AFL) then you will want to enable coverage 2180 for more specific subsets of files, and should say n here. 2181 2182config KCOV_IRQ_AREA_SIZE 2183 hex "Size of interrupt coverage collection area in words" 2184 depends on KCOV 2185 default 0x40000 2186 help 2187 KCOV uses preallocated per-cpu areas to collect coverage from 2188 soft interrupts. This specifies the size of those areas in the 2189 number of unsigned long words. 2190 2191menuconfig RUNTIME_TESTING_MENU 2192 bool "Runtime Testing" 2193 default y 2194 2195if RUNTIME_TESTING_MENU 2196 2197config TEST_DHRY 2198 tristate "Dhrystone benchmark test" 2199 help 2200 Enable this to include the Dhrystone 2.1 benchmark. This test 2201 calculates the number of Dhrystones per second, and the number of 2202 DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided 2203 by 1757 (the number of Dhrystones per second obtained on the VAX 2204 11/780, nominally a 1 MIPS machine). 2205 2206 To run the benchmark, it needs to be enabled explicitly, either from 2207 the kernel command line (when built-in), or from userspace (when 2208 built-in or modular). 2209 2210 Run once during kernel boot: 2211 2212 test_dhry.run 2213 2214 Set number of iterations from kernel command line: 2215 2216 test_dhry.iterations=<n> 2217 2218 Set number of iterations from userspace: 2219 2220 echo <n> > /sys/module/test_dhry/parameters/iterations 2221 2222 Trigger manual run from userspace: 2223 2224 echo y > /sys/module/test_dhry/parameters/run 2225 2226 If the number of iterations is <= 0, the test will devise a suitable 2227 number of iterations (test runs for at least 2s) automatically. 2228 This process takes ca. 4s. 2229 2230 If unsure, say N. 2231 2232config LKDTM 2233 tristate "Linux Kernel Dump Test Tool Module" 2234 depends on DEBUG_FS 2235 help 2236 This module enables testing of the different dumping mechanisms by 2237 inducing system failures at predefined crash points. 2238 If you don't need it: say N 2239 Choose M here to compile this code as a module. The module will be 2240 called lkdtm. 2241 2242 Documentation on how to use the module can be found in 2243 Documentation/fault-injection/provoke-crashes.rst 2244 2245config CPUMASK_KUNIT_TEST 2246 tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS 2247 depends on KUNIT 2248 default KUNIT_ALL_TESTS 2249 help 2250 Enable to turn on cpumask tests, running at boot or module load time. 2251 2252 For more information on KUnit and unit tests in general, please refer 2253 to the KUnit documentation in Documentation/dev-tools/kunit/. 2254 2255 If unsure, say N. 2256 2257config TEST_LIST_SORT 2258 tristate "Linked list sorting test" if !KUNIT_ALL_TESTS 2259 depends on KUNIT 2260 default KUNIT_ALL_TESTS 2261 help 2262 Enable this to turn on 'list_sort()' function test. This test is 2263 executed only once during system boot (so affects only boot time), 2264 or at module load time. 2265 2266 If unsure, say N. 2267 2268config TEST_MIN_HEAP 2269 tristate "Min heap test" 2270 depends on DEBUG_KERNEL || m 2271 help 2272 Enable this to turn on min heap function tests. This test is 2273 executed only once during system boot (so affects only boot time), 2274 or at module load time. 2275 2276 If unsure, say N. 2277 2278config TEST_SORT 2279 tristate "Array-based sort test" if !KUNIT_ALL_TESTS 2280 depends on KUNIT 2281 default KUNIT_ALL_TESTS 2282 help 2283 This option enables the self-test function of 'sort()' at boot, 2284 or at module load time. 2285 2286 If unsure, say N. 2287 2288config TEST_DIV64 2289 tristate "64bit/32bit division and modulo test" 2290 depends on DEBUG_KERNEL || m 2291 help 2292 Enable this to turn on 'do_div()' function test. This test is 2293 executed only once during system boot (so affects only boot time), 2294 or at module load time. 2295 2296 If unsure, say N. 2297 2298config TEST_IOV_ITER 2299 tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS 2300 depends on KUNIT 2301 depends on MMU 2302 default KUNIT_ALL_TESTS 2303 help 2304 Enable this to turn on testing of the operation of the I/O iterator 2305 (iov_iter). This test is executed only once during system boot (so 2306 affects only boot time), or at module load time. 2307 2308 If unsure, say N. 2309 2310config KPROBES_SANITY_TEST 2311 tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS 2312 depends on DEBUG_KERNEL 2313 depends on KPROBES 2314 depends on KUNIT 2315 select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 2316 default KUNIT_ALL_TESTS 2317 help 2318 This option provides for testing basic kprobes functionality on 2319 boot. Samples of kprobe and kretprobe are inserted and 2320 verified for functionality. 2321 2322 Say N if you are unsure. 2323 2324config FPROBE_SANITY_TEST 2325 bool "Self test for fprobe" 2326 depends on DEBUG_KERNEL 2327 depends on FPROBE 2328 depends on KUNIT=y 2329 help 2330 This option will enable testing the fprobe when the system boot. 2331 A series of tests are made to verify that the fprobe is functioning 2332 properly. 2333 2334 Say N if you are unsure. 2335 2336config BACKTRACE_SELF_TEST 2337 tristate "Self test for the backtrace code" 2338 depends on DEBUG_KERNEL 2339 help 2340 This option provides a kernel module that can be used to test 2341 the kernel stack backtrace code. This option is not useful 2342 for distributions or general kernels, but only for kernel 2343 developers working on architecture code. 2344 2345 Note that if you want to also test saved backtraces, you will 2346 have to enable STACKTRACE as well. 2347 2348 Say N if you are unsure. 2349 2350config TEST_REF_TRACKER 2351 tristate "Self test for reference tracker" 2352 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT 2353 select REF_TRACKER 2354 help 2355 This option provides a kernel module performing tests 2356 using reference tracker infrastructure. 2357 2358 Say N if you are unsure. 2359 2360config RBTREE_TEST 2361 tristate "Red-Black tree test" 2362 depends on DEBUG_KERNEL 2363 help 2364 A benchmark measuring the performance of the rbtree library. 2365 Also includes rbtree invariant checks. 2366 2367config REED_SOLOMON_TEST 2368 tristate "Reed-Solomon library test" 2369 depends on DEBUG_KERNEL || m 2370 select REED_SOLOMON 2371 select REED_SOLOMON_ENC16 2372 select REED_SOLOMON_DEC16 2373 help 2374 This option enables the self-test function of rslib at boot, 2375 or at module load time. 2376 2377 If unsure, say N. 2378 2379config INTERVAL_TREE_TEST 2380 tristate "Interval tree test" 2381 depends on DEBUG_KERNEL 2382 select INTERVAL_TREE 2383 help 2384 A benchmark measuring the performance of the interval tree library 2385 2386config PERCPU_TEST 2387 tristate "Per cpu operations test" 2388 depends on m && DEBUG_KERNEL 2389 help 2390 Enable this option to build test module which validates per-cpu 2391 operations. 2392 2393 If unsure, say N. 2394 2395config ATOMIC64_SELFTEST 2396 tristate "Perform an atomic64_t self-test" 2397 help 2398 Enable this option to test the atomic64_t functions at boot or 2399 at module load time. 2400 2401 If unsure, say N. 2402 2403config ASYNC_RAID6_TEST 2404 tristate "Self test for hardware accelerated raid6 recovery" 2405 depends on ASYNC_RAID6_RECOV 2406 select ASYNC_MEMCPY 2407 help 2408 This is a one-shot self test that permutes through the 2409 recovery of all the possible two disk failure scenarios for a 2410 N-disk array. Recovery is performed with the asynchronous 2411 raid6 recovery routines, and will optionally use an offload 2412 engine if one is available. 2413 2414 If unsure, say N. 2415 2416config TEST_HEXDUMP 2417 tristate "Test functions located in the hexdump module at runtime" 2418 2419config STRING_KUNIT_TEST 2420 tristate "KUnit test string functions at runtime" if !KUNIT_ALL_TESTS 2421 depends on KUNIT 2422 default KUNIT_ALL_TESTS 2423 2424config STRING_HELPERS_KUNIT_TEST 2425 tristate "KUnit test string helpers at runtime" if !KUNIT_ALL_TESTS 2426 depends on KUNIT 2427 default KUNIT_ALL_TESTS 2428 2429config TEST_KSTRTOX 2430 tristate "Test kstrto*() family of functions at runtime" 2431 2432config TEST_PRINTF 2433 tristate "Test printf() family of functions at runtime" 2434 2435config TEST_SCANF 2436 tristate "Test scanf() family of functions at runtime" 2437 2438config TEST_BITMAP 2439 tristate "Test bitmap_*() family of functions at runtime" 2440 help 2441 Enable this option to test the bitmap functions at boot. 2442 2443 If unsure, say N. 2444 2445config TEST_UUID 2446 tristate "Test functions located in the uuid module at runtime" 2447 2448config TEST_XARRAY 2449 tristate "Test the XArray code at runtime" 2450 2451config TEST_MAPLE_TREE 2452 tristate "Test the Maple Tree code at runtime or module load" 2453 help 2454 Enable this option to test the maple tree code functions at boot, or 2455 when the module is loaded. Enable "Debug Maple Trees" will enable 2456 more verbose output on failures. 2457 2458 If unsure, say N. 2459 2460config TEST_RHASHTABLE 2461 tristate "Perform selftest on resizable hash table" 2462 help 2463 Enable this option to test the rhashtable functions at boot. 2464 2465 If unsure, say N. 2466 2467config TEST_IDA 2468 tristate "Perform selftest on IDA functions" 2469 2470config TEST_PARMAN 2471 tristate "Perform selftest on priority array manager" 2472 depends on PARMAN 2473 help 2474 Enable this option to test priority array manager on boot 2475 (or module load). 2476 2477 If unsure, say N. 2478 2479config TEST_IRQ_TIMINGS 2480 bool "IRQ timings selftest" 2481 depends on IRQ_TIMINGS 2482 help 2483 Enable this option to test the irq timings code on boot. 2484 2485 If unsure, say N. 2486 2487config TEST_LKM 2488 tristate "Test module loading with 'hello world' module" 2489 depends on m 2490 help 2491 This builds the "test_module" module that emits "Hello, world" 2492 on printk when loaded. It is designed to be used for basic 2493 evaluation of the module loading subsystem (for example when 2494 validating module verification). It lacks any extra dependencies, 2495 and will not normally be loaded by the system unless explicitly 2496 requested by name. 2497 2498 If unsure, say N. 2499 2500config TEST_BITOPS 2501 tristate "Test module for compilation of bitops operations" 2502 help 2503 This builds the "test_bitops" module that is much like the 2504 TEST_LKM module except that it does a basic exercise of the 2505 set/clear_bit macros and get_count_order/long to make sure there are 2506 no compiler warnings from C=1 sparse checker or -Wextra 2507 compilations. It has no dependencies and doesn't run or load unless 2508 explicitly requested by name. for example: modprobe test_bitops. 2509 2510 If unsure, say N. 2511 2512config TEST_VMALLOC 2513 tristate "Test module for stress/performance analysis of vmalloc allocator" 2514 default n 2515 depends on MMU 2516 depends on m 2517 help 2518 This builds the "test_vmalloc" module that should be used for 2519 stress and performance analysis. So, any new change for vmalloc 2520 subsystem can be evaluated from performance and stability point 2521 of view. 2522 2523 If unsure, say N. 2524 2525config TEST_BPF 2526 tristate "Test BPF filter functionality" 2527 depends on m && NET 2528 help 2529 This builds the "test_bpf" module that runs various test vectors 2530 against the BPF interpreter or BPF JIT compiler depending on the 2531 current setting. This is in particular useful for BPF JIT compiler 2532 development, but also to run regression tests against changes in 2533 the interpreter code. It also enables test stubs for eBPF maps and 2534 verifier used by user space verifier testsuite. 2535 2536 If unsure, say N. 2537 2538config TEST_BLACKHOLE_DEV 2539 tristate "Test blackhole netdev functionality" 2540 depends on m && NET 2541 help 2542 This builds the "test_blackhole_dev" module that validates the 2543 data path through this blackhole netdev. 2544 2545 If unsure, say N. 2546 2547config FIND_BIT_BENCHMARK 2548 tristate "Test find_bit functions" 2549 help 2550 This builds the "test_find_bit" module that measure find_*_bit() 2551 functions performance. 2552 2553 If unsure, say N. 2554 2555config TEST_FIRMWARE 2556 tristate "Test firmware loading via userspace interface" 2557 depends on FW_LOADER 2558 help 2559 This builds the "test_firmware" module that creates a userspace 2560 interface for testing firmware loading. This can be used to 2561 control the triggering of firmware loading without needing an 2562 actual firmware-using device. The contents can be rechecked by 2563 userspace. 2564 2565 If unsure, say N. 2566 2567config TEST_SYSCTL 2568 tristate "sysctl test driver" 2569 depends on PROC_SYSCTL 2570 help 2571 This builds the "test_sysctl" module. This driver enables to test the 2572 proc sysctl interfaces available to drivers safely without affecting 2573 production knobs which might alter system functionality. 2574 2575 If unsure, say N. 2576 2577config BITFIELD_KUNIT 2578 tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS 2579 depends on KUNIT 2580 default KUNIT_ALL_TESTS 2581 help 2582 Enable this option to test the bitfield functions at boot. 2583 2584 KUnit tests run during boot and output the results to the debug log 2585 in TAP format (http://testanything.org/). Only useful for kernel devs 2586 running the KUnit test harness, and not intended for inclusion into a 2587 production build. 2588 2589 For more information on KUnit and unit tests in general please refer 2590 to the KUnit documentation in Documentation/dev-tools/kunit/. 2591 2592 If unsure, say N. 2593 2594config CHECKSUM_KUNIT 2595 tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS 2596 depends on KUNIT 2597 default KUNIT_ALL_TESTS 2598 help 2599 Enable this option to test the checksum functions at boot. 2600 2601 KUnit tests run during boot and output the results to the debug log 2602 in TAP format (http://testanything.org/). Only useful for kernel devs 2603 running the KUnit test harness, and not intended for inclusion into a 2604 production build. 2605 2606 For more information on KUnit and unit tests in general please refer 2607 to the KUnit documentation in Documentation/dev-tools/kunit/. 2608 2609 If unsure, say N. 2610 2611config HASH_KUNIT_TEST 2612 tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS 2613 depends on KUNIT 2614 default KUNIT_ALL_TESTS 2615 help 2616 Enable this option to test the kernel's string (<linux/stringhash.h>), and 2617 integer (<linux/hash.h>) hash functions on boot. 2618 2619 KUnit tests run during boot and output the results to the debug log 2620 in TAP format (https://testanything.org/). Only useful for kernel devs 2621 running the KUnit test harness, and not intended for inclusion into a 2622 production build. 2623 2624 For more information on KUnit and unit tests in general please refer 2625 to the KUnit documentation in Documentation/dev-tools/kunit/. 2626 2627 This is intended to help people writing architecture-specific 2628 optimized versions. If unsure, say N. 2629 2630config RESOURCE_KUNIT_TEST 2631 tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS 2632 depends on KUNIT 2633 default KUNIT_ALL_TESTS 2634 help 2635 This builds the resource API unit test. 2636 Tests the logic of API provided by resource.c and ioport.h. 2637 For more information on KUnit and unit tests in general please refer 2638 to the KUnit documentation in Documentation/dev-tools/kunit/. 2639 2640 If unsure, say N. 2641 2642config SYSCTL_KUNIT_TEST 2643 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS 2644 depends on KUNIT 2645 default KUNIT_ALL_TESTS 2646 help 2647 This builds the proc sysctl unit test, which runs on boot. 2648 Tests the API contract and implementation correctness of sysctl. 2649 For more information on KUnit and unit tests in general please refer 2650 to the KUnit documentation in Documentation/dev-tools/kunit/. 2651 2652 If unsure, say N. 2653 2654config LIST_KUNIT_TEST 2655 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS 2656 depends on KUNIT 2657 default KUNIT_ALL_TESTS 2658 help 2659 This builds the linked list KUnit test suite. 2660 It tests that the API and basic functionality of the list_head type 2661 and associated macros. 2662 2663 KUnit tests run during boot and output the results to the debug log 2664 in TAP format (https://testanything.org/). Only useful for kernel devs 2665 running the KUnit test harness, and not intended for inclusion into a 2666 production build. 2667 2668 For more information on KUnit and unit tests in general please refer 2669 to the KUnit documentation in Documentation/dev-tools/kunit/. 2670 2671 If unsure, say N. 2672 2673config HASHTABLE_KUNIT_TEST 2674 tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS 2675 depends on KUNIT 2676 default KUNIT_ALL_TESTS 2677 help 2678 This builds the hashtable KUnit test suite. 2679 It tests the basic functionality of the API defined in 2680 include/linux/hashtable.h. For more information on KUnit and 2681 unit tests in general please refer to the KUnit documentation 2682 in Documentation/dev-tools/kunit/. 2683 2684 If unsure, say N. 2685 2686config LINEAR_RANGES_TEST 2687 tristate "KUnit test for linear_ranges" 2688 depends on KUNIT 2689 select LINEAR_RANGES 2690 help 2691 This builds the linear_ranges unit test, which runs on boot. 2692 Tests the linear_ranges logic correctness. 2693 For more information on KUnit and unit tests in general please refer 2694 to the KUnit documentation in Documentation/dev-tools/kunit/. 2695 2696 If unsure, say N. 2697 2698config CMDLINE_KUNIT_TEST 2699 tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS 2700 depends on KUNIT 2701 default KUNIT_ALL_TESTS 2702 help 2703 This builds the cmdline API unit test. 2704 Tests the logic of API provided by cmdline.c. 2705 For more information on KUnit and unit tests in general please refer 2706 to the KUnit documentation in Documentation/dev-tools/kunit/. 2707 2708 If unsure, say N. 2709 2710config BITS_TEST 2711 tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS 2712 depends on KUNIT 2713 default KUNIT_ALL_TESTS 2714 help 2715 This builds the bits unit test. 2716 Tests the logic of macros defined in bits.h. 2717 For more information on KUnit and unit tests in general please refer 2718 to the KUnit documentation in Documentation/dev-tools/kunit/. 2719 2720 If unsure, say N. 2721 2722config SLUB_KUNIT_TEST 2723 tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS 2724 depends on SLUB_DEBUG && KUNIT 2725 default KUNIT_ALL_TESTS 2726 help 2727 This builds SLUB allocator unit test. 2728 Tests SLUB cache debugging functionality. 2729 For more information on KUnit and unit tests in general please refer 2730 to the KUnit documentation in Documentation/dev-tools/kunit/. 2731 2732 If unsure, say N. 2733 2734config RATIONAL_KUNIT_TEST 2735 tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS 2736 depends on KUNIT && RATIONAL 2737 default KUNIT_ALL_TESTS 2738 help 2739 This builds the rational math unit test. 2740 For more information on KUnit and unit tests in general please refer 2741 to the KUnit documentation in Documentation/dev-tools/kunit/. 2742 2743 If unsure, say N. 2744 2745config MEMCPY_KUNIT_TEST 2746 tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS 2747 depends on KUNIT 2748 default KUNIT_ALL_TESTS 2749 help 2750 Builds unit tests for memcpy(), memmove(), and memset() functions. 2751 For more information on KUnit and unit tests in general please refer 2752 to the KUnit documentation in Documentation/dev-tools/kunit/. 2753 2754 If unsure, say N. 2755 2756config IS_SIGNED_TYPE_KUNIT_TEST 2757 tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS 2758 depends on KUNIT 2759 default KUNIT_ALL_TESTS 2760 help 2761 Builds unit tests for the is_signed_type() macro. 2762 2763 For more information on KUnit and unit tests in general please refer 2764 to the KUnit documentation in Documentation/dev-tools/kunit/. 2765 2766 If unsure, say N. 2767 2768config OVERFLOW_KUNIT_TEST 2769 tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS 2770 depends on KUNIT 2771 default KUNIT_ALL_TESTS 2772 help 2773 Builds unit tests for the check_*_overflow(), size_*(), allocation, and 2774 related functions. 2775 2776 For more information on KUnit and unit tests in general please refer 2777 to the KUnit documentation in Documentation/dev-tools/kunit/. 2778 2779 If unsure, say N. 2780 2781config STACKINIT_KUNIT_TEST 2782 tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS 2783 depends on KUNIT 2784 default KUNIT_ALL_TESTS 2785 help 2786 Test if the kernel is zero-initializing stack variables and 2787 padding. Coverage is controlled by compiler flags, 2788 CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO, 2789 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2790 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2791 2792config FORTIFY_KUNIT_TEST 2793 tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS 2794 depends on KUNIT 2795 default KUNIT_ALL_TESTS 2796 help 2797 Builds unit tests for checking internals of FORTIFY_SOURCE as used 2798 by the str*() and mem*() family of functions. For testing runtime 2799 traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests. 2800 2801config HW_BREAKPOINT_KUNIT_TEST 2802 bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS 2803 depends on HAVE_HW_BREAKPOINT 2804 depends on KUNIT=y 2805 default KUNIT_ALL_TESTS 2806 help 2807 Tests for hw_breakpoint constraints accounting. 2808 2809 If unsure, say N. 2810 2811config SIPHASH_KUNIT_TEST 2812 tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS 2813 depends on KUNIT 2814 default KUNIT_ALL_TESTS 2815 help 2816 Enable this option to test the kernel's siphash (<linux/siphash.h>) hash 2817 functions on boot (or module load). 2818 2819 This is intended to help people writing architecture-specific 2820 optimized versions. If unsure, say N. 2821 2822config USERCOPY_KUNIT_TEST 2823 tristate "KUnit Test for user/kernel boundary protections" 2824 depends on KUNIT 2825 default KUNIT_ALL_TESTS 2826 help 2827 This builds the "usercopy_kunit" module that runs sanity checks 2828 on the copy_to/from_user infrastructure, making sure basic 2829 user/kernel boundary testing is working. 2830 2831config TEST_UDELAY 2832 tristate "udelay test driver" 2833 help 2834 This builds the "udelay_test" module that helps to make sure 2835 that udelay() is working properly. 2836 2837 If unsure, say N. 2838 2839config TEST_STATIC_KEYS 2840 tristate "Test static keys" 2841 depends on m 2842 help 2843 Test the static key interfaces. 2844 2845 If unsure, say N. 2846 2847config TEST_DYNAMIC_DEBUG 2848 tristate "Test DYNAMIC_DEBUG" 2849 depends on DYNAMIC_DEBUG 2850 help 2851 This module registers a tracer callback to count enabled 2852 pr_debugs in a 'do_debugging' function, then alters their 2853 enablements, calls the function, and compares counts. 2854 2855 If unsure, say N. 2856 2857config TEST_KMOD 2858 tristate "kmod stress tester" 2859 depends on m 2860 depends on NETDEVICES && NET_CORE && INET # for TUN 2861 depends on BLOCK 2862 depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS 2863 select TEST_LKM 2864 select XFS_FS 2865 select TUN 2866 select BTRFS_FS 2867 help 2868 Test the kernel's module loading mechanism: kmod. kmod implements 2869 support to load modules using the Linux kernel's usermode helper. 2870 This test provides a series of tests against kmod. 2871 2872 Although technically you can either build test_kmod as a module or 2873 into the kernel we disallow building it into the kernel since 2874 it stress tests request_module() and this will very likely cause 2875 some issues by taking over precious threads available from other 2876 module load requests, ultimately this could be fatal. 2877 2878 To run tests run: 2879 2880 tools/testing/selftests/kmod/kmod.sh --help 2881 2882 If unsure, say N. 2883 2884config TEST_DEBUG_VIRTUAL 2885 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 2886 depends on DEBUG_VIRTUAL 2887 help 2888 Test the kernel's ability to detect incorrect calls to 2889 virt_to_phys() done against the non-linear part of the 2890 kernel's virtual address map. 2891 2892 If unsure, say N. 2893 2894config TEST_MEMCAT_P 2895 tristate "Test memcat_p() helper function" 2896 help 2897 Test the memcat_p() helper for correctly merging two 2898 pointer arrays together. 2899 2900 If unsure, say N. 2901 2902config TEST_OBJAGG 2903 tristate "Perform selftest on object aggreration manager" 2904 default n 2905 depends on OBJAGG 2906 help 2907 Enable this option to test object aggregation manager on boot 2908 (or module load). 2909 2910config TEST_MEMINIT 2911 tristate "Test heap/page initialization" 2912 help 2913 Test if the kernel is zero-initializing heap and page allocations. 2914 This can be useful to test init_on_alloc and init_on_free features. 2915 2916 If unsure, say N. 2917 2918config TEST_HMM 2919 tristate "Test HMM (Heterogeneous Memory Management)" 2920 depends on TRANSPARENT_HUGEPAGE 2921 depends on DEVICE_PRIVATE 2922 select HMM_MIRROR 2923 select MMU_NOTIFIER 2924 help 2925 This is a pseudo device driver solely for testing HMM. 2926 Say M here if you want to build the HMM test module. 2927 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests. 2928 2929 If unsure, say N. 2930 2931config TEST_FREE_PAGES 2932 tristate "Test freeing pages" 2933 help 2934 Test that a memory leak does not occur due to a race between 2935 freeing a block of pages and a speculative page reference. 2936 Loading this module is safe if your kernel has the bug fixed. 2937 If the bug is not fixed, it will leak gigabytes of memory and 2938 probably OOM your system. 2939 2940config TEST_FPU 2941 tristate "Test floating point operations in kernel space" 2942 depends on ARCH_HAS_KERNEL_FPU_SUPPORT && !KCOV_INSTRUMENT_ALL 2943 help 2944 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu 2945 which will trigger a sequence of floating point operations. This is used 2946 for self-testing floating point control register setting in 2947 kernel_fpu_begin(). 2948 2949 If unsure, say N. 2950 2951config TEST_CLOCKSOURCE_WATCHDOG 2952 tristate "Test clocksource watchdog in kernel space" 2953 depends on CLOCKSOURCE_WATCHDOG 2954 help 2955 Enable this option to create a kernel module that will trigger 2956 a test of the clocksource watchdog. This module may be loaded 2957 via modprobe or insmod in which case it will run upon being 2958 loaded, or it may be built in, in which case it will run 2959 shortly after boot. 2960 2961 If unsure, say N. 2962 2963config TEST_OBJPOOL 2964 tristate "Test module for correctness and stress of objpool" 2965 default n 2966 depends on m && DEBUG_KERNEL 2967 help 2968 This builds the "test_objpool" module that should be used for 2969 correctness verification and concurrent testings of objects 2970 allocation and reclamation. 2971 2972 If unsure, say N. 2973 2974endif # RUNTIME_TESTING_MENU 2975 2976config ARCH_USE_MEMTEST 2977 bool 2978 help 2979 An architecture should select this when it uses early_memtest() 2980 during boot process. 2981 2982config MEMTEST 2983 bool "Memtest" 2984 depends on ARCH_USE_MEMTEST 2985 help 2986 This option adds a kernel parameter 'memtest', which allows memtest 2987 to be set and executed. 2988 memtest=0, mean disabled; -- default 2989 memtest=1, mean do 1 test pattern; 2990 ... 2991 memtest=17, mean do 17 test patterns. 2992 If you are unsure how to answer this question, answer N. 2993 2994 2995 2996config HYPERV_TESTING 2997 bool "Microsoft Hyper-V driver testing" 2998 default n 2999 depends on HYPERV && DEBUG_FS 3000 help 3001 Select this option to enable Hyper-V vmbus testing. 3002 3003endmenu # "Kernel Testing and Coverage" 3004 3005menu "Rust hacking" 3006 3007config RUST_DEBUG_ASSERTIONS 3008 bool "Debug assertions" 3009 depends on RUST 3010 help 3011 Enables rustc's `-Cdebug-assertions` codegen option. 3012 3013 This flag lets you turn `cfg(debug_assertions)` conditional 3014 compilation on or off. This can be used to enable extra debugging 3015 code in development but not in production. For example, it controls 3016 the behavior of the standard library's `debug_assert!` macro. 3017 3018 Note that this will apply to all Rust code, including `core`. 3019 3020 If unsure, say N. 3021 3022config RUST_OVERFLOW_CHECKS 3023 bool "Overflow checks" 3024 default y 3025 depends on RUST 3026 help 3027 Enables rustc's `-Coverflow-checks` codegen option. 3028 3029 This flag allows you to control the behavior of runtime integer 3030 overflow. When overflow-checks are enabled, a Rust panic will occur 3031 on overflow. 3032 3033 Note that this will apply to all Rust code, including `core`. 3034 3035 If unsure, say Y. 3036 3037config RUST_BUILD_ASSERT_ALLOW 3038 bool "Allow unoptimized build-time assertions" 3039 depends on RUST 3040 help 3041 Controls how are `build_error!` and `build_assert!` handled during build. 3042 3043 If calls to them exist in the binary, it may indicate a violated invariant 3044 or that the optimizer failed to verify the invariant during compilation. 3045 3046 This should not happen, thus by default the build is aborted. However, 3047 as an escape hatch, you can choose Y here to ignore them during build 3048 and let the check be carried at runtime (with `panic!` being called if 3049 the check fails). 3050 3051 If unsure, say N. 3052 3053config RUST_KERNEL_DOCTESTS 3054 bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS 3055 depends on RUST && KUNIT=y 3056 default KUNIT_ALL_TESTS 3057 help 3058 This builds the documentation tests of the `kernel` crate 3059 as KUnit tests. 3060 3061 For more information on KUnit and unit tests in general, 3062 please refer to the KUnit documentation in Documentation/dev-tools/kunit/. 3063 3064 If unsure, say N. 3065 3066endmenu # "Rust" 3067 3068endmenu # Kernel hacking 3069