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 PRINTK_EXECUTION_CTX 39 bool 40 depends on PRINTK 41 help 42 This option extends struct printk_info to include extra execution 43 context in printk, such as task name and CPU number from where the 44 message originated. This is useful for correlating printk messages 45 with specific execution contexts. 46 47 This is automatically enabled when a console driver that supports 48 execution context is selected. 49 50config STACKTRACE_BUILD_ID 51 bool "Show build ID information in stacktraces" 52 depends on PRINTK 53 help 54 Selecting this option adds build ID information for symbols in 55 stacktraces printed with the printk format '%p[SR]b'. 56 57 This option is intended for distros where debuginfo is not easily 58 accessible but can be downloaded given the build ID of the vmlinux or 59 kernel module where the function is located. 60 61config CONSOLE_LOGLEVEL_DEFAULT 62 int "Default console loglevel (1-15)" 63 range 1 15 64 default "7" 65 help 66 Default loglevel to determine what will be printed on the console. 67 68 Setting a default here is equivalent to passing in loglevel=<x> in 69 the kernel bootargs. loglevel=<x> continues to override whatever 70 value is specified here as well. 71 72 Note: This does not affect the log level of un-prefixed printk() 73 usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT 74 option. 75 76config CONSOLE_LOGLEVEL_QUIET 77 int "quiet console loglevel (1-15)" 78 range 1 15 79 default "4" 80 help 81 loglevel to use when "quiet" is passed on the kernel commandline. 82 83 When "quiet" is passed on the kernel commandline this loglevel 84 will be used as the loglevel. IOW passing "quiet" will be the 85 equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>" 86 87config MESSAGE_LOGLEVEL_DEFAULT 88 int "Default message log level (1-7)" 89 range 1 7 90 default "4" 91 help 92 Default log level for printk statements with no specified priority. 93 94 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks 95 that are auditing their logs closely may want to set it to a lower 96 priority. 97 98 Note: This does not affect what message level gets printed on the console 99 by default. To change that, use loglevel=<x> in the kernel bootargs, 100 or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value. 101 102config BOOT_PRINTK_DELAY 103 bool "Delay each boot printk message by N milliseconds" 104 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY 105 help 106 This build option allows you to read kernel boot messages 107 by inserting a short delay after each one. The delay is 108 specified in milliseconds on the kernel command line, 109 using "boot_delay=N". 110 111 It is likely that you would also need to use "lpj=M" to preset 112 the "loops per jiffy" value. 113 See a previous boot log for the "lpj" value to use for your 114 system, and then set "lpj=M" before setting "boot_delay=N". 115 NOTE: Using this option may adversely affect SMP systems. 116 I.e., processors other than the first one may not boot up. 117 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect 118 what it believes to be lockup conditions. 119 120config DYNAMIC_DEBUG 121 bool "Enable dynamic printk() support" 122 default n 123 depends on PRINTK 124 depends on (DEBUG_FS || PROC_FS) 125 select DYNAMIC_DEBUG_CORE 126 help 127 128 Compiles debug level messages into the kernel, which would not 129 otherwise be available at runtime. These messages can then be 130 enabled/disabled based on various levels of scope - per source file, 131 function, module, format string, and line number. This mechanism 132 implicitly compiles in all pr_debug() and dev_dbg() calls, which 133 enlarges the kernel text size by about 2%. 134 135 If a source file is compiled with DEBUG flag set, any 136 pr_debug() calls in it are enabled by default, but can be 137 disabled at runtime as below. Note that DEBUG flag is 138 turned on by many CONFIG_*DEBUG* options. 139 140 Usage: 141 142 Dynamic debugging is controlled via the 'dynamic_debug/control' file, 143 which is contained in the 'debugfs' filesystem or procfs. 144 Thus, the debugfs or procfs filesystem must first be mounted before 145 making use of this feature. 146 We refer the control file as: <debugfs>/dynamic_debug/control. This 147 file contains a list of the debug statements that can be enabled. The 148 format for each line of the file is: 149 150 filename:lineno [module]function flags format 151 152 filename : source file of the debug statement 153 lineno : line number of the debug statement 154 module : module that contains the debug statement 155 function : function that contains the debug statement 156 flags : '=p' means the line is turned 'on' for printing 157 format : the format used for the debug statement 158 159 From a live system: 160 161 nullarbor:~ # cat <debugfs>/dynamic_debug/control 162 # filename:lineno [module]function flags format 163 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012" 164 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012" 165 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012" 166 167 Example usage: 168 169 // enable the message at line 1603 of file svcsock.c 170 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' > 171 <debugfs>/dynamic_debug/control 172 173 // enable all the messages in file svcsock.c 174 nullarbor:~ # echo -n 'file svcsock.c +p' > 175 <debugfs>/dynamic_debug/control 176 177 // enable all the messages in the NFS server module 178 nullarbor:~ # echo -n 'module nfsd +p' > 179 <debugfs>/dynamic_debug/control 180 181 // enable all 12 messages in the function svc_process() 182 nullarbor:~ # echo -n 'func svc_process +p' > 183 <debugfs>/dynamic_debug/control 184 185 // disable all 12 messages in the function svc_process() 186 nullarbor:~ # echo -n 'func svc_process -p' > 187 <debugfs>/dynamic_debug/control 188 189 See Documentation/admin-guide/dynamic-debug-howto.rst for additional 190 information. 191 192config DYNAMIC_DEBUG_CORE 193 bool "Enable core function of dynamic debug support" 194 depends on PRINTK 195 depends on (DEBUG_FS || PROC_FS) 196 help 197 Enable core functional support of dynamic debug. It is useful 198 when you want to tie dynamic debug to your kernel modules with 199 DYNAMIC_DEBUG_MODULE defined for each of them, especially for 200 the case of embedded system where the kernel image size is 201 sensitive for people. 202 203config SYMBOLIC_ERRNAME 204 bool "Support symbolic error names in printf" 205 default y if PRINTK 206 help 207 If you say Y here, the kernel's printf implementation will 208 be able to print symbolic error names such as ENOSPC instead 209 of the number 28. It makes the kernel image slightly larger 210 (about 3KB), but can make the kernel logs easier to read. 211 212config DEBUG_BUGVERBOSE 213 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT 214 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE) 215 default y 216 help 217 Say Y here to make BUG() panics output the file name and line number 218 of the BUG call as well as the EIP and oops trace. This aids 219 debugging but costs about 70-100K of memory. 220 221config DEBUG_BUGVERBOSE_DETAILED 222 bool "Verbose WARN_ON_ONCE() reporting (adds 100K)" if DEBUG_BUGVERBOSE 223 help 224 Say Y here to make WARN_ON_ONCE() output the condition string of the 225 warning, in addition to the file name and line number. 226 This helps debugging, but costs about 100K of memory. 227 228 Say N if unsure. 229 230 231endmenu # "printk and dmesg options" 232 233config DEBUG_KERNEL 234 bool "Kernel debugging" 235 help 236 Say Y here if you are developing drivers or trying to debug and 237 identify kernel problems. 238 239config DEBUG_MISC 240 bool "Miscellaneous debug code" 241 default DEBUG_KERNEL 242 depends on DEBUG_KERNEL 243 help 244 Say Y here if you need to enable miscellaneous debug code that should 245 be under a more specific debug option but isn't. 246 247menu "Compile-time checks and compiler options" 248 249config DEBUG_INFO 250 bool 251 help 252 A kernel debug info option other than "None" has been selected 253 in the "Debug information" choice below, indicating that debug 254 information will be generated for build targets. 255 256# Clang generates .uleb128 with label differences for DWARF v5, a feature that 257# older binutils ports do not support when utilizing RISC-V style linker 258# relaxation: https://sourceware.org/bugzilla/show_bug.cgi?id=27215 259config AS_HAS_NON_CONST_ULEB128 260 def_bool $(as-instr,.uleb128 .Lexpr_end4 - .Lexpr_start3\n.Lexpr_start3:\n.Lexpr_end4:) 261 262choice 263 prompt "Debug information" 264 depends on DEBUG_KERNEL 265 help 266 Selecting something other than "None" results in a kernel image 267 that will include debugging info resulting in a larger kernel image. 268 This adds debug symbols to the kernel and modules (gcc -g), and 269 is needed if you intend to use kernel crashdump or binary object 270 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 271 272 Choose which version of DWARF debug info to emit. If unsure, 273 select "Toolchain default". 274 275config DEBUG_INFO_NONE 276 bool "Disable debug information" 277 help 278 Do not build the kernel with debugging information, which will 279 result in a faster and smaller build. 280 281config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT 282 bool "Rely on the toolchain's implicit default DWARF version" 283 select DEBUG_INFO 284 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128) 285 help 286 The implicit default version of DWARF debug info produced by a 287 toolchain changes over time. 288 289 This can break consumers of the debug info that haven't upgraded to 290 support newer revisions, and prevent testing newer versions, but 291 those should be less common scenarios. 292 293config DEBUG_INFO_DWARF4 294 bool "Generate DWARF Version 4 debuginfo" 295 select DEBUG_INFO 296 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502) 297 help 298 Generate DWARF v4 debug info. This requires gcc 4.5+, binutils 2.35.2 299 if using clang without clang's integrated assembler, and gdb 7.0+. 300 301 If you have consumers of DWARF debug info that are not ready for 302 newer revisions of DWARF, you may wish to choose this or have your 303 config select this. 304 305config DEBUG_INFO_DWARF5 306 bool "Generate DWARF Version 5 debuginfo" 307 select DEBUG_INFO 308 depends on !ARCH_HAS_BROKEN_DWARF5 309 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128) 310 help 311 Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc 312 5.0+ accepts the -gdwarf-5 flag but only had partial support for some 313 draft features until 7.0), and gdb 8.0+. 314 315 Changes to the structure of debug info in Version 5 allow for around 316 15-18% savings in resulting image and debug info section sizes as 317 compared to DWARF Version 4. DWARF Version 5 standardizes previous 318 extensions such as accelerators for symbol indexing and the format 319 for fission (.dwo/.dwp) files. Users may not want to select this 320 config if they rely on tooling that has not yet been updated to 321 support DWARF Version 5. 322 323endchoice # "Debug information" 324 325if DEBUG_INFO 326 327config DEBUG_INFO_REDUCED 328 bool "Reduce debugging information" 329 help 330 If you say Y here gcc is instructed to generate less debugging 331 information for structure types. This means that tools that 332 need full debugging information (like kgdb or systemtap) won't 333 be happy. But if you merely need debugging information to 334 resolve line numbers there is no loss. Advantage is that 335 build directory object sizes shrink dramatically over a full 336 DEBUG_INFO build and compile times are reduced too. 337 Only works with newer gcc versions. 338 339choice 340 prompt "Compressed Debug information" 341 help 342 Compress the resulting debug info. Results in smaller debug info sections, 343 but requires that consumers are able to decompress the results. 344 345 If unsure, choose DEBUG_INFO_COMPRESSED_NONE. 346 347config DEBUG_INFO_COMPRESSED_NONE 348 bool "Don't compress debug information" 349 help 350 Don't compress debug info sections. 351 352config DEBUG_INFO_COMPRESSED_ZLIB 353 bool "Compress debugging information with zlib" 354 depends on $(cc-option,-gz=zlib) 355 depends on $(ld-option,--compress-debug-sections=zlib) 356 help 357 Compress the debug information using zlib. 358 359 Users of dpkg-deb via debian/rules may find an increase in 360 size of their debug .deb packages with this config set, due to the 361 debug info being compressed with zlib, then the object files being 362 recompressed with a different compression scheme. But this is still 363 preferable to setting KDEB_COMPRESS or DPKG_DEB_COMPRESSOR_TYPE to 364 "none" which would be even larger. 365 366config DEBUG_INFO_COMPRESSED_ZSTD 367 bool "Compress debugging information with zstd" 368 depends on $(cc-option,-gz=zstd) 369 depends on $(ld-option,--compress-debug-sections=zstd) 370 help 371 Compress the debug information using zstd. This may provide better 372 compression than zlib, for about the same time costs, but requires newer 373 toolchain support. Requires GCC 13.0+ or Clang 16.0+, binutils 2.40+, and 374 zstd. 375 376endchoice # "Compressed Debug information" 377 378config DEBUG_INFO_SPLIT 379 bool "Produce split debuginfo in .dwo files" 380 depends on $(cc-option,-gsplit-dwarf) 381 # RISC-V linker relaxation + -gsplit-dwarf has issues with LLVM and GCC 382 # prior to 12.x: 383 # https://github.com/llvm/llvm-project/issues/56642 384 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99090 385 depends on !RISCV || GCC_VERSION >= 120000 386 help 387 Generate debug info into separate .dwo files. This significantly 388 reduces the build directory size for builds with DEBUG_INFO, 389 because it stores the information only once on disk in .dwo 390 files instead of multiple times in object files and executables. 391 In addition the debug information is also compressed. 392 393 Requires recent gcc (4.7+) and recent gdb/binutils. 394 Any tool that packages or reads debug information would need 395 to know about the .dwo files and include them. 396 Incompatible with older versions of ccache. 397 398config DEBUG_INFO_BTF 399 bool "Generate BTF type information" 400 depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED 401 depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST 402 depends on BPF_SYSCALL 403 depends on PAHOLE_VERSION >= 122 404 # pahole uses elfutils, which does not have support for Hexagon relocations 405 depends on !HEXAGON 406 help 407 Generate deduplicated BTF type information from DWARF debug info. 408 Turning this on requires pahole v1.22 or later, which will convert 409 DWARF type info into equivalent deduplicated BTF type info. 410 411config PAHOLE_HAS_BTF_TAG 412 def_bool PAHOLE_VERSION >= 123 413 depends on CC_IS_CLANG 414 help 415 Decide whether pahole emits btf_tag attributes (btf_type_tag and 416 btf_decl_tag) or not. Currently only clang compiler implements 417 these attributes, so make the config depend on CC_IS_CLANG. 418 419config PAHOLE_HAS_LANG_EXCLUDE 420 def_bool PAHOLE_VERSION >= 124 421 help 422 Support for the --lang_exclude flag which makes pahole exclude 423 compilation units from the supplied language. Used in Kbuild to 424 omit Rust CUs which are not supported in version 1.24 of pahole, 425 otherwise it would emit malformed kernel and module binaries when 426 using DEBUG_INFO_BTF_MODULES. 427 428config DEBUG_INFO_BTF_MODULES 429 bool "Generate BTF type information for kernel modules" 430 default y 431 depends on DEBUG_INFO_BTF && MODULES 432 help 433 Generate compact split BTF type information for kernel modules. 434 435config MODULE_ALLOW_BTF_MISMATCH 436 bool "Allow loading modules with non-matching BTF type info" 437 depends on DEBUG_INFO_BTF_MODULES 438 help 439 For modules whose split BTF does not match vmlinux, load without 440 BTF rather than refusing to load. The default behavior with 441 module BTF enabled is to reject modules with such mismatches; 442 this option will still load module BTF where possible but ignore 443 it when a mismatch is found. 444 445config GDB_SCRIPTS 446 bool "Provide GDB scripts for kernel debugging" 447 help 448 This creates the required links to GDB helper scripts in the 449 build directory. If you load vmlinux into gdb, the helper 450 scripts will be automatically imported by gdb as well, and 451 additional functions are available to analyze a Linux kernel 452 instance. See Documentation/process/debugging/gdb-kernel-debugging.rst 453 for further details. 454 455endif # DEBUG_INFO 456 457config FRAME_WARN 458 int "Warn for stack frames larger than" 459 range 0 8192 460 default 0 if KMSAN 461 default 2048 if GCC_PLUGIN_LATENT_ENTROPY 462 default 2048 if PARISC 463 default 1536 if (!64BIT && XTENSA) 464 default 1280 if !64BIT 465 default 2048 if 64BIT 466 help 467 Tell the compiler to warn at build time for stack frames larger than this. 468 Setting this too low will cause a lot of warnings. 469 Setting it to 0 disables the warning. 470 471config STRIP_ASM_SYMS 472 bool "Strip assembler-generated symbols during link" 473 default n 474 help 475 Strip internal assembler-generated symbols during a link (symbols 476 that look like '.Lxxx') so they don't pollute the output of 477 get_wchan() and suchlike. 478 479config READABLE_ASM 480 bool "Generate readable assembler code" 481 depends on DEBUG_KERNEL 482 depends on CC_IS_GCC 483 help 484 Disable some compiler optimizations that tend to generate human unreadable 485 assembler output. This may make the kernel slightly slower, but it helps 486 to keep kernel developers who have to stare a lot at assembler listings 487 sane. 488 489config HEADERS_INSTALL 490 bool "Install uapi headers to usr/include" 491 help 492 This option will install uapi headers (headers exported to user-space) 493 into the usr/include directory for use during the kernel build. 494 This is unneeded for building the kernel itself, but needed for some 495 user-space program samples. It is also needed by some features such 496 as uapi header sanity checks. 497 498config DEBUG_SECTION_MISMATCH 499 bool "Enable full Section mismatch analysis" 500 depends on CC_IS_GCC 501 help 502 The section mismatch analysis checks if there are illegal references 503 from one section to another. During linktime or runtime, some 504 sections are dropped; any use of code/data previously in these 505 sections would most likely result in an oops. 506 507 In the code, functions and variables are annotated with __init, 508 __initdata, and so on (see the full list in include/linux/init.h). 509 This directs the toolchain to place code/data in specific sections. 510 511 The section mismatch analysis is always performed after a full 512 kernel build, and enabling this option causes the option 513 -fno-inline-functions-called-once to be added to gcc commands. 514 515 However, when inlining a function annotated with __init in 516 a non-init function, we would lose the section information and thus 517 the analysis would not catch the illegal reference. This option 518 tells gcc to inline less (but it does result in a larger kernel). 519 520config SECTION_MISMATCH_WARN_ONLY 521 bool "Make section mismatch errors non-fatal" 522 default y 523 help 524 If you say N here, the build process will fail if there are any 525 section mismatch, instead of just throwing warnings. 526 527 If unsure, say Y. 528 529config DEBUG_FORCE_FUNCTION_ALIGN_64B 530 bool "Force all function address 64B aligned" 531 depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC || RISCV || S390) 532 select FUNCTION_ALIGNMENT_64B 533 help 534 There are cases that a commit from one domain changes the function 535 address alignment of other domains, and cause magic performance 536 bump (regression or improvement). Enable this option will help to 537 verify if the bump is caused by function alignment changes, while 538 it will slightly increase the kernel size and affect icache usage. 539 540 It is mainly for debug and performance tuning use. 541 542# 543# Select this config option from the architecture Kconfig, if it 544# is preferred to always offer frame pointers as a config 545# option on the architecture (regardless of KERNEL_DEBUG): 546# 547config ARCH_WANT_FRAME_POINTERS 548 bool 549 550config FRAME_POINTER 551 bool "Compile the kernel with frame pointers" 552 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS 553 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 554 help 555 If you say Y here the resulting kernel image will be slightly 556 larger and slower, but it gives very useful debugging information 557 in case of kernel bugs. (precise oopses/stacktraces/warnings) 558 559config OBJTOOL 560 bool 561 562config OBJTOOL_WERROR 563 bool "Upgrade objtool warnings to errors" 564 depends on OBJTOOL && !COMPILE_TEST 565 help 566 Fail the build on objtool warnings. 567 568 Objtool warnings can indicate kernel instability, including boot 569 failures. This option is highly recommended. 570 571 If unsure, say Y. 572 573config STACK_VALIDATION 574 bool "Compile-time stack metadata validation" 575 depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER 576 select OBJTOOL 577 default n 578 help 579 Validate frame pointer rules at compile-time. This helps ensure that 580 runtime stack traces are more reliable. 581 582 For more information, see 583 tools/objtool/Documentation/objtool.txt. 584 585config NOINSTR_VALIDATION 586 bool 587 depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY 588 select OBJTOOL 589 default y 590 591config VMLINUX_MAP 592 bool "Generate vmlinux.map file when linking" 593 depends on EXPERT 594 help 595 Selecting this option will pass "-Map=vmlinux.map" to ld 596 when linking vmlinux. That file can be useful for verifying 597 and debugging magic section games, and for seeing which 598 pieces of code get eliminated with 599 CONFIG_LD_DEAD_CODE_DATA_ELIMINATION. 600 601config BUILTIN_MODULE_RANGES 602 bool "Generate address range information for builtin modules" 603 depends on !LTO 604 depends on VMLINUX_MAP 605 help 606 When modules are built into the kernel, there will be no module name 607 associated with its symbols in /proc/kallsyms. Tracers may want to 608 identify symbols by module name and symbol name regardless of whether 609 the module is configured as loadable or not. 610 611 This option generates modules.builtin.ranges in the build tree with 612 offset ranges (per ELF section) for the module(s) they belong to. 613 It also records an anchor symbol to determine the load address of the 614 section. 615 616config DEBUG_FORCE_WEAK_PER_CPU 617 bool "Force weak per-cpu definitions" 618 depends on DEBUG_KERNEL 619 help 620 s390 and alpha require percpu variables in modules to be 621 defined weak to work around addressing range issue which 622 puts the following two restrictions on percpu variable 623 definitions. 624 625 1. percpu symbols must be unique whether static or not 626 2. percpu variables can't be defined inside a function 627 628 To ensure that generic code follows the above rules, this 629 option forces all percpu variables to be defined as weak. 630 631config WARN_CONTEXT_ANALYSIS 632 bool "Compiler context-analysis warnings" 633 depends on CC_IS_CLANG && CLANG_VERSION >= 220000 634 # Branch profiling re-defines "if", which messes with the compiler's 635 # ability to analyze __cond_acquires(..), resulting in false positives. 636 depends on !TRACE_BRANCH_PROFILING 637 default y 638 help 639 Context Analysis is a language extension, which enables statically 640 checking that required contexts are active (or inactive) by acquiring 641 and releasing user-definable "context locks". 642 643 Clang's name of the feature is "Thread Safety Analysis". Requires 644 Clang 22 or later. 645 646 Produces warnings by default. Select CONFIG_WERROR if you wish to 647 turn these warnings into errors. 648 649 For more details, see Documentation/dev-tools/context-analysis.rst. 650 651config WARN_CONTEXT_ANALYSIS_ALL 652 bool "Enable context analysis for all source files" 653 depends on WARN_CONTEXT_ANALYSIS 654 depends on EXPERT && !COMPILE_TEST 655 help 656 Enable tree-wide context analysis. This is likely to produce a 657 large number of false positives - enable at your own risk. 658 659 If unsure, say N. 660 661endmenu # "Compiler options" 662 663menu "Generic Kernel Debugging Instruments" 664 665config MAGIC_SYSRQ 666 bool "Magic SysRq key" 667 depends on !UML 668 help 669 If you say Y here, you will have some control over the system even 670 if the system crashes for example during kernel debugging (e.g., you 671 will be able to flush the buffer cache to disk, reboot the system 672 immediately or dump some status information). This is accomplished 673 by pressing various keys while holding SysRq (Alt+PrintScreen). It 674 also works on a serial console (on PC hardware at least), if you 675 send a BREAK and then within 5 seconds a command keypress. The 676 keys are documented in <file:Documentation/admin-guide/sysrq.rst>. 677 Don't say Y unless you really know what this hack does. 678 679config MAGIC_SYSRQ_DEFAULT_ENABLE 680 hex "Enable magic SysRq key functions by default" 681 depends on MAGIC_SYSRQ 682 default 0x1 683 help 684 Specifies which SysRq key functions are enabled by default. 685 This may be set to 1 or 0 to enable or disable them all, or 686 to a bitmask as described in Documentation/admin-guide/sysrq.rst. 687 688config MAGIC_SYSRQ_SERIAL 689 bool "Enable magic SysRq key over serial" 690 depends on MAGIC_SYSRQ 691 default y 692 help 693 Many embedded boards have a disconnected TTL level serial which can 694 generate some garbage that can lead to spurious false sysrq detects. 695 This option allows you to decide whether you want to enable the 696 magic SysRq key. 697 698config MAGIC_SYSRQ_SERIAL_SEQUENCE 699 string "Char sequence that enables magic SysRq over serial" 700 depends on MAGIC_SYSRQ_SERIAL 701 default "" 702 help 703 Specifies a sequence of characters that can follow BREAK to enable 704 SysRq on a serial console. 705 706 If unsure, leave an empty string and the option will not be enabled. 707 708config DEBUG_FS 709 bool "Debug Filesystem" 710 help 711 debugfs is a virtual file system that kernel developers use to put 712 debugging files into. Enable this option to be able to read and 713 write to these files. 714 715 For detailed documentation on the debugfs API, see 716 Documentation/filesystems/. 717 718 If unsure, say N. 719 720choice 721 prompt "Debugfs default access" 722 depends on DEBUG_FS 723 default DEBUG_FS_ALLOW_ALL 724 help 725 This selects the default access restrictions for debugfs. 726 It can be overridden with kernel command line option 727 debugfs=[on,off]. The restrictions apply for API access 728 and filesystem registration. 729 730config DEBUG_FS_ALLOW_ALL 731 bool "Access normal" 732 help 733 No restrictions apply. Both API and filesystem registration 734 is on. This is the normal default operation. 735 736config DEBUG_FS_ALLOW_NONE 737 bool "No access" 738 help 739 Access is off. Clients get -PERM when trying to create nodes in 740 debugfs tree and debugfs is not registered as a filesystem. 741 Client can then back-off or continue without debugfs access. 742 743endchoice 744 745source "lib/Kconfig.kgdb" 746source "lib/Kconfig.ubsan" 747source "lib/Kconfig.kcsan" 748 749endmenu 750 751menu "Networking Debugging" 752 753source "net/Kconfig.debug" 754 755endmenu # "Networking Debugging" 756 757menu "Memory Debugging" 758 759source "mm/Kconfig.debug" 760 761config DEBUG_OBJECTS 762 bool "Debug object operations" 763 depends on DEBUG_KERNEL 764 help 765 If you say Y here, additional code will be inserted into the 766 kernel to track the life time of various objects and validate 767 the operations on those objects. 768 769config DEBUG_OBJECTS_SELFTEST 770 bool "Debug objects selftest" 771 depends on DEBUG_OBJECTS 772 help 773 This enables the selftest of the object debug code. 774 775config DEBUG_OBJECTS_FREE 776 bool "Debug objects in freed memory" 777 depends on DEBUG_OBJECTS 778 help 779 This enables checks whether a k/v free operation frees an area 780 which contains an object which has not been deactivated 781 properly. This can make kmalloc/kfree-intensive workloads 782 much slower. 783 784config DEBUG_OBJECTS_TIMERS 785 bool "Debug timer objects" 786 depends on DEBUG_OBJECTS 787 help 788 If you say Y here, additional code will be inserted into the 789 timer routines to track the life time of timer objects and 790 validate the timer operations. 791 792config DEBUG_OBJECTS_WORK 793 bool "Debug work objects" 794 depends on DEBUG_OBJECTS 795 help 796 If you say Y here, additional code will be inserted into the 797 work queue routines to track the life time of work objects and 798 validate the work operations. 799 800config DEBUG_OBJECTS_RCU_HEAD 801 bool "Debug RCU callbacks objects" 802 depends on DEBUG_OBJECTS 803 help 804 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 805 806config DEBUG_OBJECTS_PERCPU_COUNTER 807 bool "Debug percpu counter objects" 808 depends on DEBUG_OBJECTS 809 help 810 If you say Y here, additional code will be inserted into the 811 percpu counter routines to track the life time of percpu counter 812 objects and validate the percpu counter operations. 813 814config DEBUG_OBJECTS_ENABLE_DEFAULT 815 int "debug_objects bootup default value (0-1)" 816 range 0 1 817 default "1" 818 depends on DEBUG_OBJECTS 819 help 820 Debug objects boot parameter default value 821 822config SHRINKER_DEBUG 823 bool "Enable shrinker debugging support" 824 depends on DEBUG_FS 825 help 826 Say Y to enable the shrinker debugfs interface which provides 827 visibility into the kernel memory shrinkers subsystem. 828 Disable it to avoid an extra memory footprint. 829 830config DEBUG_STACK_USAGE 831 bool "Stack utilization instrumentation" 832 depends on DEBUG_KERNEL 833 help 834 Enables the display of the minimum amount of free stack which each 835 task has ever had available in the sysrq-T and sysrq-P debug output. 836 Also emits a message to dmesg when a process exits if that process 837 used more stack space than previously exiting processes. 838 839 This option will slow down process creation somewhat. 840 841config SCHED_STACK_END_CHECK 842 bool "Detect stack corruption on calls to schedule()" 843 depends on DEBUG_KERNEL 844 default n 845 help 846 This option checks for a stack overrun on calls to schedule(). 847 If the stack end location is found to be over written always panic as 848 the content of the corrupted region can no longer be trusted. 849 This is to ensure no erroneous behaviour occurs which could result in 850 data corruption or a sporadic crash at a later stage once the region 851 is examined. The runtime overhead introduced is minimal. 852 853config ARCH_HAS_DEBUG_VM_PGTABLE 854 bool 855 help 856 An architecture should select this when it can successfully 857 build and run DEBUG_VM_PGTABLE. 858 859config DEBUG_VFS 860 bool "Debug VFS" 861 depends on DEBUG_KERNEL 862 help 863 Enable this to turn on extended checks in the VFS layer that may impact 864 performance. 865 866 If unsure, say N. 867 868config DEBUG_VM_IRQSOFF 869 def_bool DEBUG_VM && !PREEMPT_RT 870 871config DEBUG_VM 872 bool "Debug VM" 873 depends on DEBUG_KERNEL 874 help 875 Enable this to turn on extended checks in the virtual-memory system 876 that may impact performance. 877 878 If unsure, say N. 879 880config DEBUG_VM_SHOOT_LAZIES 881 bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation" 882 depends on DEBUG_VM 883 depends on MMU_LAZY_TLB_SHOOTDOWN 884 help 885 Enable additional IPIs that ensure lazy tlb mm references are removed 886 before the mm is freed. 887 888 If unsure, say N. 889 890config DEBUG_VM_MAPLE_TREE 891 bool "Debug VM maple trees" 892 depends on DEBUG_VM 893 select DEBUG_MAPLE_TREE 894 help 895 Enable VM maple tree debugging information and extra validations. 896 897 If unsure, say N. 898 899config DEBUG_VM_RB 900 bool "Debug VM red-black trees" 901 depends on DEBUG_VM 902 help 903 Enable VM red-black tree debugging information and extra validations. 904 905 If unsure, say N. 906 907config DEBUG_VM_PGFLAGS 908 bool "Debug page-flags operations" 909 depends on DEBUG_VM 910 help 911 Enables extra validation on page flags operations. 912 913 If unsure, say N. 914 915config DEBUG_VM_PGTABLE 916 bool "Debug arch page table for semantics compliance" 917 depends on MMU 918 depends on ARCH_HAS_DEBUG_VM_PGTABLE 919 default y if DEBUG_VM 920 help 921 This option provides a debug method which can be used to test 922 architecture page table helper functions on various platforms in 923 verifying if they comply with expected generic MM semantics. This 924 will help architecture code in making sure that any changes or 925 new additions of these helpers still conform to expected 926 semantics of the generic MM. Platforms will have to opt in for 927 this through ARCH_HAS_DEBUG_VM_PGTABLE. 928 929 If unsure, say N. 930 931config ARCH_HAS_DEBUG_VIRTUAL 932 bool 933 934config DEBUG_VIRTUAL 935 bool "Debug VM translations" 936 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL 937 help 938 Enable some costly sanity checks in virtual to page code. This can 939 catch mistakes with virt_to_page() and friends. 940 941 If unsure, say N. 942 943config DEBUG_NOMMU_REGIONS 944 bool "Debug the global anon/private NOMMU mapping region tree" 945 depends on DEBUG_KERNEL && !MMU 946 help 947 This option causes the global tree of anonymous and private mapping 948 regions to be regularly checked for invalid topology. 949 950config DEBUG_MEMORY_INIT 951 bool "Debug memory initialisation" if EXPERT 952 default !EXPERT 953 help 954 Enable this for additional checks during memory initialisation. 955 The sanity checks verify aspects of the VM such as the memory model 956 and other information provided by the architecture. Verbose 957 information will be printed at KERN_DEBUG loglevel depending 958 on the mminit_loglevel= command-line option. 959 960 If unsure, say Y 961 962config MEMORY_NOTIFIER_ERROR_INJECT 963 tristate "Memory hotplug notifier error injection module" 964 depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION 965 help 966 This option provides the ability to inject artificial errors to 967 memory hotplug notifier chain callbacks. It is controlled through 968 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 969 970 If the notifier call chain should be failed with some events 971 notified, write the error code to "actions/<notifier event>/error". 972 973 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 974 975 # cd /sys/kernel/debug/notifier-error-inject/memory 976 # echo -12 > actions/MEM_GOING_OFFLINE/error 977 # echo offline > /sys/devices/system/memory/memoryXXX/state 978 bash: echo: write error: Cannot allocate memory 979 980 To compile this code as a module, choose M here: the module will 981 be called memory-notifier-error-inject. 982 983 If unsure, say N. 984 985config DEBUG_PER_CPU_MAPS 986 bool "Debug access to per_cpu maps" 987 depends on DEBUG_KERNEL 988 depends on SMP 989 help 990 Say Y to verify that the per_cpu map being accessed has 991 been set up. This adds a fair amount of code to kernel memory 992 and decreases performance. 993 994 Say N if unsure. 995 996config DEBUG_KMAP_LOCAL 997 bool "Debug kmap_local temporary mappings" 998 depends on DEBUG_KERNEL && KMAP_LOCAL 999 help 1000 This option enables additional error checking for the kmap_local 1001 infrastructure. Disable for production use. 1002 1003config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 1004 bool 1005 1006config DEBUG_KMAP_LOCAL_FORCE_MAP 1007 bool "Enforce kmap_local temporary mappings" 1008 depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 1009 select KMAP_LOCAL 1010 select DEBUG_KMAP_LOCAL 1011 help 1012 This option enforces temporary mappings through the kmap_local 1013 mechanism for non-highmem pages and on non-highmem systems. 1014 Disable this for production systems! 1015 1016config DEBUG_HIGHMEM 1017 bool "Highmem debugging" 1018 depends on DEBUG_KERNEL && HIGHMEM 1019 select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 1020 select DEBUG_KMAP_LOCAL 1021 help 1022 This option enables additional error checking for high memory 1023 systems. Disable for production systems. 1024 1025config HAVE_DEBUG_STACKOVERFLOW 1026 bool 1027 1028config DEBUG_STACKOVERFLOW 1029 bool "Check for stack overflows" 1030 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 1031 help 1032 Say Y here if you want to check for overflows of kernel, IRQ 1033 and exception stacks (if your architecture uses them). This 1034 option will show detailed messages if free stack space drops 1035 below a certain limit. 1036 1037 These kinds of bugs usually occur when call-chains in the 1038 kernel get too deep, especially when interrupts are 1039 involved. 1040 1041 Use this in cases where you see apparently random memory 1042 corruption, especially if it appears in 'struct thread_info' 1043 1044 If in doubt, say "N". 1045 1046config CODE_TAGGING 1047 bool 1048 select KALLSYMS 1049 1050config MEM_ALLOC_PROFILING 1051 bool "Enable memory allocation profiling" 1052 default n 1053 depends on MMU 1054 depends on PROC_FS 1055 depends on !DEBUG_FORCE_WEAK_PER_CPU 1056 select CODE_TAGGING 1057 select PAGE_EXTENSION 1058 select SLAB_OBJ_EXT 1059 help 1060 Track allocation source code and record total allocation size 1061 initiated at that code location. The mechanism can be used to track 1062 memory leaks with a low performance and memory impact. 1063 1064config MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT 1065 bool "Enable memory allocation profiling by default" 1066 default y 1067 depends on MEM_ALLOC_PROFILING 1068 1069config MEM_ALLOC_PROFILING_DEBUG 1070 bool "Memory allocation profiler debugging" 1071 default n 1072 depends on MEM_ALLOC_PROFILING 1073 select MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT 1074 help 1075 Adds warnings with helpful error messages for memory allocation 1076 profiling. 1077 1078source "lib/Kconfig.kasan" 1079source "lib/Kconfig.kfence" 1080source "lib/Kconfig.kmsan" 1081 1082endmenu # "Memory Debugging" 1083 1084config DEBUG_SHIRQ 1085 bool "Debug shared IRQ handlers" 1086 depends on DEBUG_KERNEL 1087 help 1088 Enable this to generate a spurious interrupt just before a shared 1089 interrupt handler is deregistered (generating one when registering 1090 is currently disabled). Drivers need to handle this correctly. Some 1091 don't and need to be caught. 1092 1093menu "Debug Oops, Lockups and Hangs" 1094 1095config PANIC_ON_OOPS 1096 bool "Panic on Oops" 1097 help 1098 Say Y here to enable the kernel to panic when it oopses. This 1099 has the same effect as setting oops=panic on the kernel command 1100 line. 1101 1102 This feature is useful to ensure that the kernel does not do 1103 anything erroneous after an oops which could result in data 1104 corruption or other issues. 1105 1106 Say N if unsure. 1107 1108config PANIC_TIMEOUT 1109 int "panic timeout" 1110 default 0 1111 help 1112 Set the timeout value (in seconds) until a reboot occurs when 1113 the kernel panics. If n = 0, then we wait forever. A timeout 1114 value n > 0 will wait n seconds before rebooting, while a timeout 1115 value n < 0 will reboot immediately. This setting can be overridden 1116 with the kernel command line option panic=, and from userspace via 1117 /proc/sys/kernel/panic. 1118 1119config LOCKUP_DETECTOR 1120 bool 1121 1122config SOFTLOCKUP_DETECTOR 1123 bool "Detect Soft Lockups" 1124 depends on DEBUG_KERNEL && !S390 1125 select LOCKUP_DETECTOR 1126 help 1127 Say Y here to enable the kernel to act as a watchdog to detect 1128 soft lockups. 1129 1130 Softlockups are bugs that cause the kernel to loop in kernel 1131 mode for more than 20 seconds, without giving other tasks a 1132 chance to run. The current stack trace is displayed upon 1133 detection and the system will stay locked up. 1134 1135config SOFTLOCKUP_DETECTOR_INTR_STORM 1136 bool "Detect Interrupt Storm in Soft Lockups" 1137 depends on SOFTLOCKUP_DETECTOR && IRQ_TIME_ACCOUNTING 1138 select GENERIC_IRQ_STAT_SNAPSHOT 1139 default y if NR_CPUS <= 128 1140 help 1141 Say Y here to enable the kernel to detect interrupt storm 1142 during "soft lockups". 1143 1144 "soft lockups" can be caused by a variety of reasons. If one is 1145 caused by an interrupt storm, then the storming interrupts will not 1146 be on the callstack. To detect this case, it is necessary to report 1147 the CPU stats and the interrupt counts during the "soft lockups". 1148 1149config BOOTPARAM_SOFTLOCKUP_PANIC 1150 int "Panic (Reboot) On Soft Lockups" 1151 depends on SOFTLOCKUP_DETECTOR 1152 default 0 1153 help 1154 Set to a non-zero value N to enable the kernel to panic on "soft 1155 lockups", which are bugs that cause the kernel to loop in kernel 1156 mode for more than (N * 20 seconds) (configurable using the 1157 watchdog_thresh sysctl), without giving other tasks a chance to run. 1158 1159 The panic can be used in combination with panic_timeout, 1160 to cause the system to reboot automatically after a 1161 lockup has been detected. This feature is useful for 1162 high-availability systems that have uptime guarantees and 1163 where a lockup must be resolved ASAP. 1164 1165 Say 0 if unsure. 1166 1167config HAVE_HARDLOCKUP_DETECTOR_BUDDY 1168 bool 1169 depends on SMP 1170 default y 1171 1172# 1173# Global switch whether to build a hardlockup detector at all. It is available 1174# only when the architecture supports at least one implementation. There are 1175# two exceptions. The hardlockup detector is never enabled on: 1176# 1177# s390: it reported many false positives there 1178# 1179# sparc64: has a custom implementation which is not using the common 1180# hardlockup command line options and sysctl interface. 1181# 1182config HARDLOCKUP_DETECTOR 1183 bool "Detect Hard Lockups" 1184 depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64 1185 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH 1186 imply HARDLOCKUP_DETECTOR_PERF 1187 imply HARDLOCKUP_DETECTOR_BUDDY 1188 imply HARDLOCKUP_DETECTOR_ARCH 1189 select LOCKUP_DETECTOR 1190 1191 help 1192 Say Y here to enable the kernel to act as a watchdog to detect 1193 hard lockups. 1194 1195 Hardlockups are bugs that cause the CPU to loop in kernel mode 1196 for more than 10 seconds, without letting other interrupts have a 1197 chance to run. The current stack trace is displayed upon detection 1198 and the system will stay locked up. 1199 1200# 1201# Note that arch-specific variants are always preferred. 1202# 1203config HARDLOCKUP_DETECTOR_PREFER_BUDDY 1204 bool "Prefer the buddy CPU hardlockup detector" 1205 depends on HARDLOCKUP_DETECTOR 1206 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY 1207 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1208 help 1209 Say Y here to prefer the buddy hardlockup detector over the perf one. 1210 1211 With the buddy detector, each CPU uses its softlockup hrtimer 1212 to check that the next CPU is processing hrtimer interrupts by 1213 verifying that a counter is increasing. 1214 1215 This hardlockup detector is useful on systems that don't have 1216 an arch-specific hardlockup detector or if resources needed 1217 for the hardlockup detector are better used for other things. 1218 1219config HARDLOCKUP_DETECTOR_PERF 1220 bool 1221 depends on HARDLOCKUP_DETECTOR 1222 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY 1223 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1224 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1225 1226config HARDLOCKUP_DETECTOR_BUDDY 1227 bool 1228 depends on HARDLOCKUP_DETECTOR 1229 depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY 1230 depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY 1231 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1232 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1233 1234config HARDLOCKUP_DETECTOR_ARCH 1235 bool 1236 depends on HARDLOCKUP_DETECTOR 1237 depends on HAVE_HARDLOCKUP_DETECTOR_ARCH 1238 help 1239 The arch-specific implementation of the hardlockup detector will 1240 be used. 1241 1242# 1243# Both the "perf" and "buddy" hardlockup detectors count hrtimer 1244# interrupts. This config enables functions managing this common code. 1245# 1246config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1247 bool 1248 select SOFTLOCKUP_DETECTOR 1249 1250# 1251# Enables a timestamp based low pass filter to compensate for perf based 1252# hard lockup detection which runs too fast due to turbo modes. 1253# 1254config HARDLOCKUP_CHECK_TIMESTAMP 1255 bool 1256 1257config BOOTPARAM_HARDLOCKUP_PANIC 1258 bool "Panic (Reboot) On Hard Lockups" 1259 depends on HARDLOCKUP_DETECTOR 1260 help 1261 Say Y here to enable the kernel to panic on "hard lockups", 1262 which are bugs that cause the kernel to loop in kernel 1263 mode with interrupts disabled for more than 10 seconds (configurable 1264 using the watchdog_thresh sysctl). 1265 1266 Say N if unsure. 1267 1268config DETECT_HUNG_TASK 1269 bool "Detect Hung Tasks" 1270 depends on DEBUG_KERNEL 1271 default SOFTLOCKUP_DETECTOR 1272 help 1273 Say Y here to enable the kernel to detect "hung tasks", 1274 which are bugs that cause the task to be stuck in 1275 uninterruptible "D" state indefinitely. 1276 1277 When a hung task is detected, the kernel will print the 1278 current stack trace (which you should report), but the 1279 task will stay in uninterruptible state. If lockdep is 1280 enabled then all held locks will also be reported. This 1281 feature has negligible overhead. 1282 1283config DEFAULT_HUNG_TASK_TIMEOUT 1284 int "Default timeout for hung task detection (in seconds)" 1285 depends on DETECT_HUNG_TASK 1286 default 120 1287 help 1288 This option controls the default timeout (in seconds) used 1289 to determine when a task has become non-responsive and should 1290 be considered hung. 1291 1292 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 1293 sysctl or by writing a value to 1294 /proc/sys/kernel/hung_task_timeout_secs. 1295 1296 A timeout of 0 disables the check. The default is two minutes. 1297 Keeping the default should be fine in most cases. 1298 1299config BOOTPARAM_HUNG_TASK_PANIC 1300 int "Number of hung tasks to trigger kernel panic" 1301 depends on DETECT_HUNG_TASK 1302 default 0 1303 help 1304 When set to a non-zero value, a kernel panic will be triggered 1305 if the number of hung tasks found during a single scan reaches 1306 this value. 1307 1308 The panic can be used in combination with panic_timeout, 1309 to cause the system to reboot automatically after a 1310 hung task has been detected. This feature is useful for 1311 high-availability systems that have uptime guarantees and 1312 where a hung tasks must be resolved ASAP. 1313 1314 Say 0 if unsure. 1315 1316config DETECT_HUNG_TASK_BLOCKER 1317 bool "Dump Hung Tasks Blocker" 1318 depends on DETECT_HUNG_TASK 1319 depends on !PREEMPT_RT 1320 default y 1321 help 1322 Say Y here to show the blocker task's stacktrace who acquires 1323 the mutex lock which "hung tasks" are waiting. 1324 This will add overhead a bit but shows suspicious tasks and 1325 call trace if it comes from waiting a mutex. 1326 1327config WQ_WATCHDOG 1328 bool "Detect Workqueue Stalls" 1329 depends on DEBUG_KERNEL 1330 help 1331 Say Y here to enable stall detection on workqueues. If a 1332 worker pool doesn't make forward progress on a pending work 1333 item for over a given amount of time, 30s by default, a 1334 warning message is printed along with dump of workqueue 1335 state. This can be configured through kernel parameter 1336 "workqueue.watchdog_thresh" and its sysfs counterpart. 1337 1338config BOOTPARAM_WQ_STALL_PANIC 1339 int "Panic on Nth workqueue stall" 1340 default 0 1341 range 0 100 1342 depends on WQ_WATCHDOG 1343 help 1344 Set the number of workqueue stalls to trigger a kernel panic. 1345 A workqueue stall occurs when a worker pool doesn't make forward 1346 progress on a pending work item for over 30 seconds (configurable 1347 using the workqueue.watchdog_thresh parameter). 1348 1349 If n = 0, the kernel will not panic on stall. If n > 0, the kernel 1350 will panic after n stall warnings. 1351 1352 The panic can be used in combination with panic_timeout, 1353 to cause the system to reboot automatically after a 1354 stall has been detected. This feature is useful for 1355 high-availability systems that have uptime guarantees and 1356 where a stall must be resolved ASAP. 1357 1358 This setting can be overridden at runtime via the 1359 workqueue.panic_on_stall kernel parameter. 1360 1361config WQ_CPU_INTENSIVE_REPORT 1362 bool "Report per-cpu work items which hog CPU for too long" 1363 depends on DEBUG_KERNEL 1364 help 1365 Say Y here to enable reporting of concurrency-managed per-cpu work 1366 items that hog CPUs for longer than 1367 workqueue.cpu_intensive_thresh_us. Workqueue automatically 1368 detects and excludes them from concurrency management to prevent 1369 them from stalling other per-cpu work items. Occassional 1370 triggering may not necessarily indicate a problem. Repeated 1371 triggering likely indicates that the work item should be switched 1372 to use an unbound workqueue. 1373 1374config TEST_LOCKUP 1375 tristate "Test module to generate lockups" 1376 depends on m 1377 help 1378 This builds the "test_lockup" module that helps to make sure 1379 that watchdogs and lockup detectors are working properly. 1380 1381 Depending on module parameters it could emulate soft or hard 1382 lockup, "hung task", or locking arbitrary lock for a long time. 1383 Also it could generate series of lockups with cooling-down periods. 1384 1385 If unsure, say N. 1386 1387endmenu # "Debug lockups and hangs" 1388 1389menu "Scheduler Debugging" 1390 1391config SCHED_INFO 1392 bool 1393 default n 1394 1395config SCHEDSTATS 1396 bool "Collect scheduler statistics" 1397 depends on PROC_FS 1398 select SCHED_INFO 1399 help 1400 If you say Y here, additional code will be inserted into the 1401 scheduler and related routines to collect statistics about 1402 scheduler behavior and provide them in /proc/schedstat. These 1403 stats may be useful for both tuning and debugging the scheduler 1404 If you aren't debugging the scheduler or trying to tune a specific 1405 application, you can say N to avoid the very slight overhead 1406 this adds. 1407 1408endmenu 1409 1410config DEBUG_PREEMPT 1411 bool "Debug preemptible kernel" 1412 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1413 help 1414 If you say Y here then the kernel will use a debug variant of the 1415 commonly used smp_processor_id() function and will print warnings 1416 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1417 will detect preemption count underflows. 1418 1419 This option has potential to introduce high runtime overhead, 1420 depending on workload as it triggers debugging routines for each 1421 this_cpu operation. It should only be used for debugging purposes. 1422 1423config DEBUG_ATOMIC 1424 bool "Debug atomic variables" 1425 depends on DEBUG_KERNEL 1426 help 1427 If you say Y here then the kernel will add a runtime alignment check 1428 to atomic accesses. Useful for architectures that do not have trap on 1429 mis-aligned access. 1430 1431 This option has potentially significant overhead. 1432 1433config DEBUG_ATOMIC_LARGEST_ALIGN 1434 bool "Check alignment only up to __aligned_largest" 1435 depends on DEBUG_ATOMIC 1436 help 1437 If you say Y here then the check for natural alignment of 1438 atomic accesses will be constrained to the compiler's largest 1439 alignment for scalar types. 1440 1441menu "Lock Debugging (spinlocks, mutexes, etc...)" 1442 1443config LOCK_DEBUGGING_SUPPORT 1444 bool 1445 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1446 default y 1447 1448config PROVE_LOCKING 1449 bool "Lock debugging: prove locking correctness" 1450 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1451 select LOCKDEP 1452 select DEBUG_SPINLOCK 1453 select DEBUG_MUTEXES if !PREEMPT_RT 1454 select DEBUG_RT_MUTEXES if RT_MUTEXES 1455 select DEBUG_RWSEMS if !PREEMPT_RT 1456 select DEBUG_WW_MUTEX_SLOWPATH 1457 select DEBUG_LOCK_ALLOC 1458 select PREEMPT_COUNT if !ARCH_NO_PREEMPT 1459 select TRACE_IRQFLAGS 1460 default n 1461 help 1462 This feature enables the kernel to prove that all locking 1463 that occurs in the kernel runtime is mathematically 1464 correct: that under no circumstance could an arbitrary (and 1465 not yet triggered) combination of observed locking 1466 sequences (on an arbitrary number of CPUs, running an 1467 arbitrary number of tasks and interrupt contexts) cause a 1468 deadlock. 1469 1470 In short, this feature enables the kernel to report locking 1471 related deadlocks before they actually occur. 1472 1473 The proof does not depend on how hard and complex a 1474 deadlock scenario would be to trigger: how many 1475 participant CPUs, tasks and irq-contexts would be needed 1476 for it to trigger. The proof also does not depend on 1477 timing: if a race and a resulting deadlock is possible 1478 theoretically (no matter how unlikely the race scenario 1479 is), it will be proven so and will immediately be 1480 reported by the kernel (once the event is observed that 1481 makes the deadlock theoretically possible). 1482 1483 If a deadlock is impossible (i.e. the locking rules, as 1484 observed by the kernel, are mathematically correct), the 1485 kernel reports nothing. 1486 1487 NOTE: this feature can also be enabled for rwlocks, mutexes 1488 and rwsems - in which case all dependencies between these 1489 different locking variants are observed and mapped too, and 1490 the proof of observed correctness is also maintained for an 1491 arbitrary combination of these separate locking variants. 1492 1493 For more details, see Documentation/locking/lockdep-design.rst. 1494 1495config PROVE_RAW_LOCK_NESTING 1496 bool "Enable raw_spinlock - spinlock nesting checks" if !ARCH_SUPPORTS_RT 1497 depends on PROVE_LOCKING 1498 default y if ARCH_SUPPORTS_RT 1499 help 1500 Enable the raw_spinlock vs. spinlock nesting checks which ensure 1501 that the lock nesting rules for PREEMPT_RT enabled kernels are 1502 not violated. 1503 1504config LOCK_STAT 1505 bool "Lock usage statistics" 1506 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1507 select LOCKDEP 1508 select DEBUG_SPINLOCK 1509 select DEBUG_MUTEXES if !PREEMPT_RT 1510 select DEBUG_RT_MUTEXES if RT_MUTEXES 1511 select DEBUG_LOCK_ALLOC 1512 default n 1513 help 1514 This feature enables tracking lock contention points 1515 1516 For more details, see Documentation/locking/lockstat.rst 1517 1518 This also enables lock events required by "perf lock", 1519 subcommand of perf. 1520 If you want to use "perf lock", you also need to turn on 1521 CONFIG_EVENT_TRACING. 1522 1523 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1524 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1525 1526config DEBUG_RT_MUTEXES 1527 bool "RT Mutex debugging, deadlock detection" 1528 depends on DEBUG_KERNEL && RT_MUTEXES 1529 help 1530 This allows rt mutex semantics violations and rt mutex related 1531 deadlocks (lockups) to be detected and reported automatically. 1532 1533config DEBUG_SPINLOCK 1534 bool "Spinlock and rw-lock debugging: basic checks" 1535 depends on DEBUG_KERNEL 1536 select UNINLINE_SPIN_UNLOCK 1537 help 1538 Say Y here and build SMP to catch missing spinlock initialization 1539 and certain other kinds of spinlock errors commonly made. This is 1540 best used in conjunction with the NMI watchdog so that spinlock 1541 deadlocks are also debuggable. 1542 1543config DEBUG_MUTEXES 1544 bool "Mutex debugging: basic checks" 1545 depends on DEBUG_KERNEL && !PREEMPT_RT 1546 help 1547 This feature allows mutex semantics violations to be detected and 1548 reported. 1549 1550config DEBUG_WW_MUTEX_SLOWPATH 1551 bool "Wait/wound mutex debugging: Slowpath testing" 1552 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1553 select DEBUG_LOCK_ALLOC 1554 select DEBUG_SPINLOCK 1555 select DEBUG_MUTEXES if !PREEMPT_RT 1556 select DEBUG_RT_MUTEXES if PREEMPT_RT 1557 help 1558 This feature enables slowpath testing for w/w mutex users by 1559 injecting additional -EDEADLK wound/backoff cases. Together with 1560 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1561 will test all possible w/w mutex interface abuse with the 1562 exception of simply not acquiring all the required locks. 1563 Note that this feature can introduce significant overhead, so 1564 it really should not be enabled in a production or distro kernel, 1565 even a debug kernel. If you are a driver writer, enable it. If 1566 you are a distro, do not. 1567 1568config DEBUG_RWSEMS 1569 bool "RW Semaphore debugging: basic checks" 1570 depends on DEBUG_KERNEL && !PREEMPT_RT 1571 help 1572 This debugging feature allows mismatched rw semaphore locks 1573 and unlocks to be detected and reported. 1574 1575config DEBUG_LOCK_ALLOC 1576 bool "Lock debugging: detect incorrect freeing of live locks" 1577 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1578 select DEBUG_SPINLOCK 1579 select DEBUG_MUTEXES if !PREEMPT_RT 1580 select DEBUG_RT_MUTEXES if RT_MUTEXES 1581 select LOCKDEP 1582 help 1583 This feature will check whether any held lock (spinlock, rwlock, 1584 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1585 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1586 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1587 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1588 held during task exit. 1589 1590config LOCKDEP 1591 bool 1592 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1593 select STACKTRACE 1594 select KALLSYMS 1595 select KALLSYMS_ALL 1596 1597config LOCKDEP_SMALL 1598 bool 1599 1600config LOCKDEP_BITS 1601 int "Size for MAX_LOCKDEP_ENTRIES (as Nth power of 2)" 1602 depends on LOCKDEP && !LOCKDEP_SMALL 1603 range 10 24 1604 default 15 1605 help 1606 Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message. 1607 1608config LOCKDEP_CHAINS_BITS 1609 int "Size for MAX_LOCKDEP_CHAINS (as Nth power of 2)" 1610 depends on LOCKDEP && !LOCKDEP_SMALL 1611 range 10 21 1612 default 16 1613 help 1614 Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message. 1615 1616config LOCKDEP_STACK_TRACE_BITS 1617 int "Size for MAX_STACK_TRACE_ENTRIES (as Nth power of 2)" 1618 depends on LOCKDEP && !LOCKDEP_SMALL 1619 range 10 26 1620 default 19 1621 help 1622 Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message. 1623 1624config LOCKDEP_STACK_TRACE_HASH_BITS 1625 int "Size for STACK_TRACE_HASH_SIZE (as Nth power of 2)" 1626 depends on LOCKDEP && !LOCKDEP_SMALL 1627 range 10 26 1628 default 14 1629 help 1630 Try increasing this value if you need large STACK_TRACE_HASH_SIZE. 1631 1632config LOCKDEP_CIRCULAR_QUEUE_BITS 1633 int "Size for elements in circular_queue struct (as Nth power of 2)" 1634 depends on LOCKDEP 1635 range 10 26 1636 default 12 1637 help 1638 Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure. 1639 1640config DEBUG_LOCKDEP 1641 bool "Lock dependency engine debugging" 1642 depends on DEBUG_KERNEL && LOCKDEP 1643 select DEBUG_IRQFLAGS 1644 help 1645 If you say Y here, the lock dependency engine will do 1646 additional runtime checks to debug itself, at the price 1647 of more runtime overhead. 1648 1649config DEBUG_ATOMIC_SLEEP 1650 bool "Sleep inside atomic section checking" 1651 select PREEMPT_COUNT 1652 depends on DEBUG_KERNEL 1653 depends on !ARCH_NO_PREEMPT 1654 help 1655 If you say Y here, various routines which may sleep will become very 1656 noisy if they are called inside atomic sections: when a spinlock is 1657 held, inside an rcu read side critical section, inside preempt disabled 1658 sections, inside an interrupt, etc... 1659 1660config DEBUG_LOCKING_API_SELFTESTS 1661 bool "Locking API boot-time self-tests" 1662 depends on DEBUG_KERNEL 1663 help 1664 Say Y here if you want the kernel to run a short self-test during 1665 bootup. The self-test checks whether common types of locking bugs 1666 are detected by debugging mechanisms or not. (if you disable 1667 lock debugging then those bugs won't be detected of course.) 1668 The following locking APIs are covered: spinlocks, rwlocks, 1669 mutexes and rwsems. 1670 1671config LOCK_TORTURE_TEST 1672 tristate "torture tests for locking" 1673 depends on DEBUG_KERNEL 1674 select TORTURE_TEST 1675 help 1676 This option provides a kernel module that runs torture tests 1677 on kernel locking primitives. The kernel module may be built 1678 after the fact on the running kernel to be tested, if desired. 1679 1680 Say Y here if you want kernel locking-primitive torture tests 1681 to be built into the kernel. 1682 Say M if you want these torture tests to build as a module. 1683 Say N if you are unsure. 1684 1685config WW_MUTEX_SELFTEST 1686 tristate "Wait/wound mutex selftests" 1687 help 1688 This option provides a kernel module that runs tests on the 1689 on the struct ww_mutex locking API. 1690 1691 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1692 with this test harness. 1693 1694 Say M if you want these self tests to build as a module. 1695 Say N if you are unsure. 1696 1697config SCF_TORTURE_TEST 1698 tristate "torture tests for smp_call_function*()" 1699 depends on DEBUG_KERNEL 1700 select TORTURE_TEST 1701 help 1702 This option provides a kernel module that runs torture tests 1703 on the smp_call_function() family of primitives. The kernel 1704 module may be built after the fact on the running kernel to 1705 be tested, if desired. 1706 1707config CSD_LOCK_WAIT_DEBUG 1708 bool "Debugging for csd_lock_wait(), called from smp_call_function*()" 1709 depends on DEBUG_KERNEL 1710 depends on SMP 1711 depends on 64BIT 1712 default n 1713 help 1714 This option enables debug prints when CPUs are slow to respond 1715 to the smp_call_function*() IPI wrappers. These debug prints 1716 include the IPI handler function currently executing (if any) 1717 and relevant stack traces. 1718 1719config CSD_LOCK_WAIT_DEBUG_DEFAULT 1720 bool "Default csd_lock_wait() debugging on at boot time" 1721 depends on CSD_LOCK_WAIT_DEBUG 1722 depends on 64BIT 1723 default n 1724 help 1725 This option causes the csdlock_debug= kernel boot parameter to 1726 default to 1 (basic debugging) instead of 0 (no debugging). 1727 1728endmenu # lock debugging 1729 1730config TRACE_IRQFLAGS 1731 depends on TRACE_IRQFLAGS_SUPPORT 1732 bool 1733 help 1734 Enables hooks to interrupt enabling and disabling for 1735 either tracing or lock debugging. 1736 1737config TRACE_IRQFLAGS_NMI 1738 def_bool y 1739 depends on TRACE_IRQFLAGS 1740 depends on TRACE_IRQFLAGS_NMI_SUPPORT 1741 1742config NMI_CHECK_CPU 1743 bool "Debugging for CPUs failing to respond to backtrace requests" 1744 depends on DEBUG_KERNEL 1745 depends on X86 1746 default n 1747 help 1748 Enables debug prints when a CPU fails to respond to a given 1749 backtrace NMI. These prints provide some reasons why a CPU 1750 might legitimately be failing to respond, for example, if it 1751 is offline of if ignore_nmis is set. 1752 1753config DEBUG_IRQFLAGS 1754 bool "Debug IRQ flag manipulation" 1755 help 1756 Enables checks for potentially unsafe enabling or disabling of 1757 interrupts, such as calling raw_local_irq_restore() when interrupts 1758 are enabled. 1759 1760config STACKTRACE 1761 bool "Stack backtrace support" 1762 depends on STACKTRACE_SUPPORT 1763 help 1764 This option causes the kernel to create a /proc/pid/stack for 1765 every process, showing its current stack trace. 1766 It is also used by various kernel debugging features that require 1767 stack trace generation. 1768 1769config WARN_ALL_UNSEEDED_RANDOM 1770 bool "Warn for all uses of unseeded randomness" 1771 default n 1772 help 1773 Some parts of the kernel contain bugs relating to their use of 1774 cryptographically secure random numbers before it's actually possible 1775 to generate those numbers securely. This setting ensures that these 1776 flaws don't go unnoticed, by enabling a message, should this ever 1777 occur. This will allow people with obscure setups to know when things 1778 are going wrong, so that they might contact developers about fixing 1779 it. 1780 1781 Unfortunately, on some models of some architectures getting 1782 a fully seeded CRNG is extremely difficult, and so this can 1783 result in dmesg getting spammed for a surprisingly long 1784 time. This is really bad from a security perspective, and 1785 so architecture maintainers really need to do what they can 1786 to get the CRNG seeded sooner after the system is booted. 1787 However, since users cannot do anything actionable to 1788 address this, by default this option is disabled. 1789 1790 Say Y here if you want to receive warnings for all uses of 1791 unseeded randomness. This will be of use primarily for 1792 those developers interested in improving the security of 1793 Linux kernels running on their architecture (or 1794 subarchitecture). 1795 1796config DEBUG_KOBJECT 1797 bool "kobject debugging" 1798 depends on DEBUG_KERNEL 1799 help 1800 If you say Y here, some extra kobject debugging messages will be sent 1801 to the syslog. 1802 1803config DEBUG_KOBJECT_RELEASE 1804 bool "kobject release debugging" 1805 depends on DEBUG_OBJECTS_TIMERS 1806 help 1807 kobjects are reference counted objects. This means that their 1808 last reference count put is not predictable, and the kobject can 1809 live on past the point at which a driver decides to drop its 1810 initial reference to the kobject gained on allocation. An 1811 example of this would be a struct device which has just been 1812 unregistered. 1813 1814 However, some buggy drivers assume that after such an operation, 1815 the memory backing the kobject can be immediately freed. This 1816 goes completely against the principles of a refcounted object. 1817 1818 If you say Y here, the kernel will delay the release of kobjects 1819 on the last reference count to improve the visibility of this 1820 kind of kobject release bug. 1821 1822config HAVE_DEBUG_BUGVERBOSE 1823 bool 1824 1825menu "Debug kernel data structures" 1826 1827config DEBUG_LIST 1828 bool "Debug linked list manipulation" 1829 depends on DEBUG_KERNEL 1830 select LIST_HARDENED 1831 help 1832 Enable this to turn on extended checks in the linked-list walking 1833 routines. 1834 1835 This option trades better quality error reports for performance, and 1836 is more suitable for kernel debugging. If you care about performance, 1837 you should only enable CONFIG_LIST_HARDENED instead. 1838 1839 If unsure, say N. 1840 1841config DEBUG_PLIST 1842 bool "Debug priority linked list manipulation" 1843 depends on DEBUG_KERNEL 1844 help 1845 Enable this to turn on extended checks in the priority-ordered 1846 linked-list (plist) walking routines. This checks the entire 1847 list multiple times during each manipulation. 1848 1849 If unsure, say N. 1850 1851config DEBUG_SG 1852 bool "Debug SG table operations" 1853 depends on DEBUG_KERNEL 1854 help 1855 Enable this to turn on checks on scatter-gather tables. This can 1856 help find problems with drivers that do not properly initialize 1857 their sg tables. 1858 1859 If unsure, say N. 1860 1861config DEBUG_NOTIFIERS 1862 bool "Debug notifier call chains" 1863 depends on DEBUG_KERNEL 1864 help 1865 Enable this to turn on sanity checking for notifier call chains. 1866 This is most useful for kernel developers to make sure that 1867 modules properly unregister themselves from notifier chains. 1868 This is a relatively cheap check but if you care about maximum 1869 performance, say N. 1870 1871config DEBUG_CLOSURES 1872 bool "Debug closures (bcache async widgits)" 1873 depends on CLOSURES 1874 select DEBUG_FS 1875 help 1876 Keeps all active closures in a linked list and provides a debugfs 1877 interface to list them, which makes it possible to see asynchronous 1878 operations that get stuck. 1879 1880config DEBUG_MAPLE_TREE 1881 bool "Debug maple trees" 1882 depends on DEBUG_KERNEL 1883 help 1884 Enable maple tree debugging information and extra validations. 1885 1886 If unsure, say N. 1887 1888endmenu 1889 1890source "kernel/rcu/Kconfig.debug" 1891 1892config DEBUG_WQ_FORCE_RR_CPU 1893 bool "Force round-robin CPU selection for unbound work items" 1894 depends on DEBUG_KERNEL 1895 default n 1896 help 1897 Workqueue used to implicitly guarantee that work items queued 1898 without explicit CPU specified are put on the local CPU. This 1899 guarantee is no longer true and while local CPU is still 1900 preferred work items may be put on foreign CPUs. Kernel 1901 parameter "workqueue.debug_force_rr_cpu" is added to force 1902 round-robin CPU selection to flush out usages which depend on the 1903 now broken guarantee. This config option enables the debug 1904 feature by default. When enabled, memory and cache locality will 1905 be impacted. 1906 1907config CPU_HOTPLUG_STATE_CONTROL 1908 bool "Enable CPU hotplug state control" 1909 depends on DEBUG_KERNEL 1910 depends on HOTPLUG_CPU 1911 default n 1912 help 1913 Allows to write steps between "offline" and "online" to the CPUs 1914 sysfs target file so states can be stepped granular. This is a debug 1915 option for now as the hotplug machinery cannot be stopped and 1916 restarted at arbitrary points yet. 1917 1918 Say N if your are unsure. 1919 1920config LATENCYTOP 1921 bool "Latency measuring infrastructure" 1922 depends on DEBUG_KERNEL 1923 depends on STACKTRACE_SUPPORT 1924 depends on PROC_FS 1925 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 1926 select KALLSYMS 1927 select KALLSYMS_ALL 1928 select STACKTRACE 1929 select SCHEDSTATS 1930 help 1931 Enable this option if you want to use the LatencyTOP tool 1932 to find out which userspace is blocking on what kernel operations. 1933 1934config DEBUG_CGROUP_REF 1935 bool "Disable inlining of cgroup css reference count functions" 1936 depends on DEBUG_KERNEL 1937 depends on CGROUPS 1938 depends on KPROBES 1939 default n 1940 help 1941 Force cgroup css reference count functions to not be inlined so 1942 that they can be kprobed for debugging. 1943 1944source "kernel/trace/Kconfig" 1945 1946config PROVIDE_OHCI1394_DMA_INIT 1947 bool "Remote debugging over FireWire early on boot" 1948 depends on PCI && X86 1949 help 1950 If you want to debug problems which hang or crash the kernel early 1951 on boot and the crashing machine has a FireWire port, you can use 1952 this feature to remotely access the memory of the crashed machine 1953 over FireWire. This employs remote DMA as part of the OHCI1394 1954 specification which is now the standard for FireWire controllers. 1955 1956 With remote DMA, you can monitor the printk buffer remotely using 1957 firescope and access all memory below 4GB using fireproxy from gdb. 1958 Even controlling a kernel debugger is possible using remote DMA. 1959 1960 Usage: 1961 1962 If ohci1394_dma=early is used as boot parameter, it will initialize 1963 all OHCI1394 controllers which are found in the PCI config space. 1964 1965 As all changes to the FireWire bus such as enabling and disabling 1966 devices cause a bus reset and thereby disable remote DMA for all 1967 devices, be sure to have the cable plugged and FireWire enabled on 1968 the debugging host before booting the debug target for debugging. 1969 1970 This code (~1k) is freed after boot. By then, the firewire stack 1971 in charge of the OHCI-1394 controllers should be used instead. 1972 1973 See Documentation/core-api/debugging-via-ohci1394.rst for more information. 1974 1975source "samples/Kconfig" 1976 1977config ARCH_HAS_DEVMEM_IS_ALLOWED 1978 bool 1979 1980config STRICT_DEVMEM 1981 bool "Filter access to /dev/mem" 1982 depends on MMU && DEVMEM 1983 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED 1984 default y if PPC || X86 || ARM64 || S390 1985 help 1986 If this option is disabled, you allow userspace (root) access to all 1987 of memory, including kernel and userspace memory. Accidental 1988 access to this is obviously disastrous, but specific access can 1989 be used by people debugging the kernel. Note that with PAT support 1990 enabled, even in this case there are restrictions on /dev/mem 1991 use due to the cache aliasing requirements. 1992 1993 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 1994 file only allows userspace access to PCI space and the BIOS code and 1995 data regions. This is sufficient for dosemu and X and all common 1996 users of /dev/mem. 1997 1998 If in doubt, say Y. 1999 2000config IO_STRICT_DEVMEM 2001 bool "Filter I/O access to /dev/mem" 2002 depends on STRICT_DEVMEM 2003 help 2004 If this option is disabled, you allow userspace (root) access to all 2005 io-memory regardless of whether a driver is actively using that 2006 range. Accidental access to this is obviously disastrous, but 2007 specific access can be used by people debugging kernel drivers. 2008 2009 If this option is switched on, the /dev/mem file only allows 2010 userspace access to *idle* io-memory ranges (see /proc/iomem) This 2011 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 2012 if the driver using a given range cannot be disabled. 2013 2014 If in doubt, say Y. 2015 2016menu "$(SRCARCH) Debugging" 2017 2018source "arch/$(SRCARCH)/Kconfig.debug" 2019 2020endmenu 2021 2022menu "Kernel Testing and Coverage" 2023 2024source "lib/kunit/Kconfig" 2025 2026config NOTIFIER_ERROR_INJECTION 2027 tristate "Notifier error injection" 2028 depends on DEBUG_KERNEL 2029 select DEBUG_FS 2030 help 2031 This option provides the ability to inject artificial errors to 2032 specified notifier chain callbacks. It is useful to test the error 2033 handling of notifier call chain failures. 2034 2035 Say N if unsure. 2036 2037config PM_NOTIFIER_ERROR_INJECT 2038 tristate "PM notifier error injection module" 2039 depends on PM && NOTIFIER_ERROR_INJECTION 2040 default m if PM_DEBUG 2041 help 2042 This option provides the ability to inject artificial errors to 2043 PM notifier chain callbacks. It is controlled through debugfs 2044 interface /sys/kernel/debug/notifier-error-inject/pm 2045 2046 If the notifier call chain should be failed with some events 2047 notified, write the error code to "actions/<notifier event>/error". 2048 2049 Example: Inject PM suspend error (-12 = -ENOMEM) 2050 2051 # cd /sys/kernel/debug/notifier-error-inject/pm/ 2052 # echo -12 > actions/PM_SUSPEND_PREPARE/error 2053 # echo mem > /sys/power/state 2054 bash: echo: write error: Cannot allocate memory 2055 2056 To compile this code as a module, choose M here: the module will 2057 be called pm-notifier-error-inject. 2058 2059 If unsure, say N. 2060 2061config OF_RECONFIG_NOTIFIER_ERROR_INJECT 2062 tristate "OF reconfig notifier error injection module" 2063 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 2064 help 2065 This option provides the ability to inject artificial errors to 2066 OF reconfig notifier chain callbacks. It is controlled 2067 through debugfs interface under 2068 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 2069 2070 If the notifier call chain should be failed with some events 2071 notified, write the error code to "actions/<notifier event>/error". 2072 2073 To compile this code as a module, choose M here: the module will 2074 be called of-reconfig-notifier-error-inject. 2075 2076 If unsure, say N. 2077 2078config NETDEV_NOTIFIER_ERROR_INJECT 2079 tristate "Netdev notifier error injection module" 2080 depends on NET && NOTIFIER_ERROR_INJECTION 2081 help 2082 This option provides the ability to inject artificial errors to 2083 netdevice notifier chain callbacks. It is controlled through debugfs 2084 interface /sys/kernel/debug/notifier-error-inject/netdev 2085 2086 If the notifier call chain should be failed with some events 2087 notified, write the error code to "actions/<notifier event>/error". 2088 2089 Example: Inject netdevice mtu change error (-22 = -EINVAL) 2090 2091 # cd /sys/kernel/debug/notifier-error-inject/netdev 2092 # echo -22 > actions/NETDEV_CHANGEMTU/error 2093 # ip link set eth0 mtu 1024 2094 RTNETLINK answers: Invalid argument 2095 2096 To compile this code as a module, choose M here: the module will 2097 be called netdev-notifier-error-inject. 2098 2099 If unsure, say N. 2100 2101config FUNCTION_ERROR_INJECTION 2102 bool "Fault-injections of functions" 2103 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 2104 help 2105 Add fault injections into various functions that are annotated with 2106 ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return 2107 value of these functions. This is useful to test error paths of code. 2108 2109 If unsure, say N 2110 2111config FAULT_INJECTION 2112 bool "Fault-injection framework" 2113 depends on DEBUG_KERNEL 2114 help 2115 Provide fault-injection framework. 2116 For more details, see Documentation/fault-injection/. 2117 2118config FAILSLAB 2119 bool "Fault-injection capability for kmalloc" 2120 depends on FAULT_INJECTION 2121 help 2122 Provide fault-injection capability for kmalloc. 2123 2124config FAIL_PAGE_ALLOC 2125 bool "Fault-injection capability for alloc_pages()" 2126 depends on FAULT_INJECTION 2127 help 2128 Provide fault-injection capability for alloc_pages(). 2129 2130config FAULT_INJECTION_USERCOPY 2131 bool "Fault injection capability for usercopy functions" 2132 depends on FAULT_INJECTION 2133 help 2134 Provides fault-injection capability to inject failures 2135 in usercopy functions (copy_from_user(), get_user(), ...). 2136 2137config FAIL_MAKE_REQUEST 2138 bool "Fault-injection capability for disk IO" 2139 depends on FAULT_INJECTION && BLOCK 2140 help 2141 Provide fault-injection capability for disk IO. 2142 2143config FAIL_IO_TIMEOUT 2144 bool "Fault-injection capability for faking disk interrupts" 2145 depends on FAULT_INJECTION && BLOCK 2146 help 2147 Provide fault-injection capability on end IO handling. This 2148 will make the block layer "forget" an interrupt as configured, 2149 thus exercising the error handling. 2150 2151 Only works with drivers that use the generic timeout handling, 2152 for others it won't do anything. 2153 2154config FAIL_FUTEX 2155 bool "Fault-injection capability for futexes" 2156 select DEBUG_FS 2157 depends on FAULT_INJECTION && FUTEX 2158 help 2159 Provide fault-injection capability for futexes. 2160 2161config FAULT_INJECTION_DEBUG_FS 2162 bool "Debugfs entries for fault-injection capabilities" 2163 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 2164 help 2165 Enable configuration of fault-injection capabilities via debugfs. 2166 2167config FAIL_FUNCTION 2168 bool "Fault-injection capability for functions" 2169 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 2170 help 2171 Provide function-based fault-injection capability. 2172 This will allow you to override a specific function with a return 2173 with given return value. As a result, function caller will see 2174 an error value and have to handle it. This is useful to test the 2175 error handling in various subsystems. 2176 2177config FAIL_MMC_REQUEST 2178 bool "Fault-injection capability for MMC IO" 2179 depends on FAULT_INJECTION_DEBUG_FS && MMC 2180 help 2181 Provide fault-injection capability for MMC IO. 2182 This will make the mmc core return data errors. This is 2183 useful to test the error handling in the mmc block device 2184 and to test how the mmc host driver handles retries from 2185 the block device. 2186 2187config FAIL_SUNRPC 2188 bool "Fault-injection capability for SunRPC" 2189 depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG 2190 help 2191 Provide fault-injection capability for SunRPC and 2192 its consumers. 2193 2194config FAIL_SKB_REALLOC 2195 bool "Fault-injection capability forcing skb to reallocate" 2196 depends on FAULT_INJECTION_DEBUG_FS 2197 help 2198 Provide fault-injection capability that forces the skb to be 2199 reallocated, catching possible invalid pointers to the skb. 2200 2201 For more information, check 2202 Documentation/fault-injection/fault-injection.rst 2203 2204config FAULT_INJECTION_CONFIGFS 2205 bool "Configfs interface for fault-injection capabilities" 2206 depends on FAULT_INJECTION 2207 select CONFIGFS_FS 2208 help 2209 This option allows configfs-based drivers to dynamically configure 2210 fault-injection via configfs. Each parameter for driver-specific 2211 fault-injection can be made visible as a configfs attribute in a 2212 configfs group. 2213 2214 2215config FAULT_INJECTION_STACKTRACE_FILTER 2216 bool "stacktrace filter for fault-injection capabilities" 2217 depends on FAULT_INJECTION 2218 depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT 2219 select STACKTRACE 2220 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 2221 help 2222 Provide stacktrace filter for fault-injection capabilities 2223 2224config ARCH_HAS_KCOV 2225 bool 2226 help 2227 An architecture should select this when it can successfully 2228 build and run with CONFIG_KCOV. This typically requires 2229 disabling instrumentation for some early boot code. 2230 2231config KCOV 2232 bool "Code coverage for fuzzing" 2233 depends on ARCH_HAS_KCOV 2234 depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \ 2235 GCC_VERSION >= 120000 || CC_IS_CLANG 2236 select DEBUG_FS 2237 select OBJTOOL if HAVE_NOINSTR_HACK 2238 help 2239 KCOV exposes kernel code coverage information in a form suitable 2240 for coverage-guided fuzzing (randomized testing). 2241 2242 For more details, see Documentation/dev-tools/kcov.rst. 2243 2244config KCOV_ENABLE_COMPARISONS 2245 bool "Enable comparison operands collection by KCOV" 2246 depends on KCOV 2247 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 2248 help 2249 KCOV also exposes operands of every comparison in the instrumented 2250 code along with operand sizes and PCs of the comparison instructions. 2251 These operands can be used by fuzzing engines to improve the quality 2252 of fuzzing coverage. 2253 2254config KCOV_INSTRUMENT_ALL 2255 bool "Instrument all code by default" 2256 depends on KCOV 2257 default y 2258 help 2259 If you are doing generic system call fuzzing (like e.g. syzkaller), 2260 then you will want to instrument the whole kernel and you should 2261 say y here. If you are doing more targeted fuzzing (like e.g. 2262 filesystem fuzzing with AFL) then you will want to enable coverage 2263 for more specific subsets of files, and should say n here. 2264 2265config KCOV_IRQ_AREA_SIZE 2266 hex "Size of interrupt coverage collection area in words" 2267 depends on KCOV 2268 default 0x40000 2269 help 2270 KCOV uses preallocated per-cpu areas to collect coverage from 2271 soft interrupts. This specifies the size of those areas in the 2272 number of unsigned long words. 2273 2274config KCOV_SELFTEST 2275 bool "Perform short selftests on boot" 2276 depends on KCOV 2277 help 2278 Run short KCOV coverage collection selftests on boot. 2279 On test failure, causes the kernel to panic. Recommended to be 2280 enabled, ensuring critical functionality works as intended. 2281 2282menuconfig RUNTIME_TESTING_MENU 2283 bool "Runtime Testing" 2284 default y 2285 2286if RUNTIME_TESTING_MENU 2287 2288config TEST_DHRY 2289 tristate "Dhrystone benchmark test" 2290 help 2291 Enable this to include the Dhrystone 2.1 benchmark. This test 2292 calculates the number of Dhrystones per second, and the number of 2293 DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided 2294 by 1757 (the number of Dhrystones per second obtained on the VAX 2295 11/780, nominally a 1 MIPS machine). 2296 2297 To run the benchmark, it needs to be enabled explicitly, either from 2298 the kernel command line (when built-in), or from userspace (when 2299 built-in or modular). 2300 2301 Run once during kernel boot: 2302 2303 test_dhry.run 2304 2305 Set number of iterations from kernel command line: 2306 2307 test_dhry.iterations=<n> 2308 2309 Set number of iterations from userspace: 2310 2311 echo <n> > /sys/module/test_dhry/parameters/iterations 2312 2313 Trigger manual run from userspace: 2314 2315 echo y > /sys/module/test_dhry/parameters/run 2316 2317 If the number of iterations is <= 0, the test will devise a suitable 2318 number of iterations (test runs for at least 2s) automatically. 2319 This process takes ca. 4s. 2320 2321 If unsure, say N. 2322 2323config LKDTM 2324 tristate "Linux Kernel Dump Test Tool Module" 2325 depends on DEBUG_FS 2326 help 2327 This module enables testing of the different dumping mechanisms by 2328 inducing system failures at predefined crash points. 2329 If you don't need it: say N 2330 Choose M here to compile this code as a module. The module will be 2331 called lkdtm. 2332 2333 Documentation on how to use the module can be found in 2334 Documentation/fault-injection/provoke-crashes.rst 2335 2336config CPUMASK_KUNIT_TEST 2337 tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS 2338 depends on KUNIT 2339 default KUNIT_ALL_TESTS 2340 help 2341 Enable to turn on cpumask tests, running at boot or module load time. 2342 2343 For more information on KUnit and unit tests in general, please refer 2344 to the KUnit documentation in Documentation/dev-tools/kunit/. 2345 2346 If unsure, say N. 2347 2348config TEST_LIST_SORT 2349 tristate "Linked list sorting test" if !KUNIT_ALL_TESTS 2350 depends on KUNIT 2351 default KUNIT_ALL_TESTS 2352 help 2353 Enable this to turn on 'list_sort()' function test. This test is 2354 executed only once during system boot (so affects only boot time), 2355 or at module load time. 2356 2357 If unsure, say N. 2358 2359config TEST_SORT 2360 tristate "Array-based sort test" if !KUNIT_ALL_TESTS 2361 depends on KUNIT 2362 default KUNIT_ALL_TESTS 2363 help 2364 This option enables the self-test function of 'sort()' at boot, 2365 or at module load time. 2366 2367 If unsure, say N. 2368 2369config TEST_DIV64 2370 tristate "64bit/32bit division and modulo test" 2371 depends on DEBUG_KERNEL || m 2372 help 2373 Enable this to turn on 'do_div()' function test. This test is 2374 executed only once during system boot (so affects only boot time), 2375 or at module load time. 2376 2377 If unsure, say N. 2378 2379config TEST_MULDIV64 2380 tristate "mul_u64_u64_div_u64() test" 2381 depends on DEBUG_KERNEL || m 2382 help 2383 Enable this to turn on 'mul_u64_u64_div_u64()' function test. 2384 This test is executed only once during system boot (so affects 2385 only boot time), or at module load time. 2386 2387 If unsure, say N. 2388 2389config TEST_IOV_ITER 2390 tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS 2391 depends on KUNIT 2392 depends on MMU 2393 default KUNIT_ALL_TESTS 2394 help 2395 Enable this to turn on testing of the operation of the I/O iterator 2396 (iov_iter). This test is executed only once during system boot (so 2397 affects only boot time), or at module load time. 2398 2399 If unsure, say N. 2400 2401config KPROBES_SANITY_TEST 2402 tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS 2403 depends on DEBUG_KERNEL 2404 depends on KPROBES 2405 depends on KUNIT 2406 select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 2407 default KUNIT_ALL_TESTS 2408 help 2409 This option provides for testing basic kprobes functionality on 2410 boot. Samples of kprobe and kretprobe are inserted and 2411 verified for functionality. 2412 2413 Say N if you are unsure. 2414 2415config FPROBE_SANITY_TEST 2416 bool "Self test for fprobe" 2417 depends on DEBUG_KERNEL 2418 depends on FPROBE 2419 depends on KUNIT=y 2420 help 2421 This option will enable testing the fprobe when the system boot. 2422 A series of tests are made to verify that the fprobe is functioning 2423 properly. 2424 2425 Say N if you are unsure. 2426 2427config BACKTRACE_SELF_TEST 2428 tristate "Self test for the backtrace code" 2429 depends on DEBUG_KERNEL 2430 help 2431 This option provides a kernel module that can be used to test 2432 the kernel stack backtrace code. This option is not useful 2433 for distributions or general kernels, but only for kernel 2434 developers working on architecture code. 2435 2436 Note that if you want to also test saved backtraces, you will 2437 have to enable STACKTRACE as well. 2438 2439 Say N if you are unsure. 2440 2441config TEST_REF_TRACKER 2442 tristate "Self test for reference tracker" 2443 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT 2444 select REF_TRACKER 2445 help 2446 This option provides a kernel module performing tests 2447 using reference tracker infrastructure. 2448 2449 Say N if you are unsure. 2450 2451config RBTREE_TEST 2452 tristate "Red-Black tree test" 2453 depends on DEBUG_KERNEL 2454 help 2455 A benchmark measuring the performance of the rbtree library. 2456 Also includes rbtree invariant checks. 2457 2458config REED_SOLOMON_TEST 2459 tristate "Reed-Solomon library test" 2460 depends on DEBUG_KERNEL || m 2461 select REED_SOLOMON 2462 select REED_SOLOMON_ENC16 2463 select REED_SOLOMON_DEC16 2464 help 2465 This option enables the self-test function of rslib at boot, 2466 or at module load time. 2467 2468 If unsure, say N. 2469 2470config INTERVAL_TREE_TEST 2471 tristate "Interval tree test" 2472 depends on DEBUG_KERNEL 2473 select INTERVAL_TREE 2474 help 2475 A benchmark measuring the performance of the interval tree library 2476 2477config PERCPU_TEST 2478 tristate "Per cpu operations test" 2479 depends on m && DEBUG_KERNEL 2480 help 2481 Enable this option to build test module which validates per-cpu 2482 operations. 2483 2484 If unsure, say N. 2485 2486config ATOMIC64_SELFTEST 2487 tristate "Perform an atomic64_t self-test" 2488 help 2489 Enable this option to test the atomic64_t functions at boot or 2490 at module load time. 2491 2492 If unsure, say N. 2493 2494config ASYNC_RAID6_TEST 2495 tristate "Self test for hardware accelerated raid6 recovery" 2496 depends on ASYNC_RAID6_RECOV 2497 select ASYNC_MEMCPY 2498 help 2499 This is a one-shot self test that permutes through the 2500 recovery of all the possible two disk failure scenarios for a 2501 N-disk array. Recovery is performed with the asynchronous 2502 raid6 recovery routines, and will optionally use an offload 2503 engine if one is available. 2504 2505 If unsure, say N. 2506 2507config TEST_HEXDUMP 2508 tristate "Test functions located in the hexdump module at runtime" 2509 2510config PRINTF_KUNIT_TEST 2511 tristate "KUnit test printf() family of functions at runtime" if !KUNIT_ALL_TESTS 2512 depends on KUNIT 2513 default KUNIT_ALL_TESTS 2514 help 2515 Enable this option to test the printf functions at runtime. 2516 2517 If unsure, say N. 2518 2519config SCANF_KUNIT_TEST 2520 tristate "KUnit test scanf() family of functions at runtime" if !KUNIT_ALL_TESTS 2521 depends on KUNIT 2522 default KUNIT_ALL_TESTS 2523 help 2524 Enable this option to test the scanf functions at runtime. 2525 2526 If unsure, say N. 2527 2528config SEQ_BUF_KUNIT_TEST 2529 tristate "KUnit test for seq_buf" if !KUNIT_ALL_TESTS 2530 depends on KUNIT 2531 default KUNIT_ALL_TESTS 2532 help 2533 This builds unit tests for the seq_buf library. 2534 2535 If unsure, say N. 2536 2537config STRING_KUNIT_TEST 2538 tristate "KUnit test string functions at runtime" if !KUNIT_ALL_TESTS 2539 depends on KUNIT 2540 default KUNIT_ALL_TESTS 2541 2542config STRING_HELPERS_KUNIT_TEST 2543 tristate "KUnit test string helpers at runtime" if !KUNIT_ALL_TESTS 2544 depends on KUNIT 2545 default KUNIT_ALL_TESTS 2546 2547config FFS_KUNIT_TEST 2548 tristate "KUnit test ffs-family functions at runtime" if !KUNIT_ALL_TESTS 2549 depends on KUNIT 2550 default KUNIT_ALL_TESTS 2551 help 2552 This builds KUnit tests for ffs-family bit manipulation functions 2553 including ffs(), __ffs(), fls(), __fls(), fls64(), and __ffs64(). 2554 2555 These tests validate mathematical correctness, edge case handling, 2556 and cross-architecture consistency of bit scanning functions. 2557 2558 For more information on KUnit and unit tests in general, 2559 please refer to Documentation/dev-tools/kunit/. 2560 2561config TEST_KSTRTOX 2562 tristate "Test kstrto*() family of functions at runtime" 2563 2564config TEST_BITMAP 2565 tristate "Test bitmap_*() family of functions at runtime" 2566 help 2567 Enable this option to test the bitmap functions at boot. 2568 2569 If unsure, say N. 2570 2571config TEST_XARRAY 2572 tristate "Test the XArray code at runtime" 2573 2574config TEST_MAPLE_TREE 2575 tristate "Test the Maple Tree code at runtime or module load" 2576 help 2577 Enable this option to test the maple tree code functions at boot, or 2578 when the module is loaded. Enable "Debug Maple Trees" will enable 2579 more verbose output on failures. 2580 2581 If unsure, say N. 2582 2583config TEST_RHASHTABLE 2584 tristate "Perform selftest on resizable hash table" 2585 help 2586 Enable this option to test the rhashtable functions at boot. 2587 2588 If unsure, say N. 2589 2590config TEST_IDA 2591 tristate "Perform selftest on IDA functions" 2592 2593config TEST_MISC_MINOR 2594 bool "miscdevice KUnit test" if !KUNIT_ALL_TESTS 2595 depends on KUNIT=y 2596 default KUNIT_ALL_TESTS 2597 help 2598 Kunit test for miscdevice API, specially its behavior in respect to 2599 static and dynamic minor numbers. 2600 2601 KUnit tests run during boot and output the results to the debug log 2602 in TAP format (https://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 TEST_PARMAN 2612 tristate "Perform selftest on priority array manager" 2613 depends on PARMAN 2614 help 2615 Enable this option to test priority array manager on boot 2616 (or module load). 2617 2618 If unsure, say N. 2619 2620config TEST_LKM 2621 tristate "Test module loading with 'hello world' module" 2622 depends on m 2623 help 2624 This builds the "test_module" module that emits "Hello, world" 2625 on printk when loaded. It is designed to be used for basic 2626 evaluation of the module loading subsystem (for example when 2627 validating module verification). It lacks any extra dependencies, 2628 and will not normally be loaded by the system unless explicitly 2629 requested by name. 2630 2631 If unsure, say N. 2632 2633config TEST_BITOPS 2634 tristate "Test module for compilation of bitops operations" 2635 help 2636 This builds the "test_bitops" module that is much like the 2637 TEST_LKM module except that it does a basic exercise of the 2638 set/clear_bit macros and get_count_order/long to make sure there are 2639 no compiler warnings from C=1 sparse checker or -Wextra 2640 compilations. It has no dependencies and doesn't run or load unless 2641 explicitly requested by name. for example: modprobe test_bitops. 2642 2643 If unsure, say N. 2644 2645config TEST_VMALLOC 2646 tristate "Test module for stress/performance analysis of vmalloc allocator" 2647 default n 2648 depends on MMU 2649 help 2650 This builds the "test_vmalloc" module that should be used for 2651 stress and performance analysis. So, any new change for vmalloc 2652 subsystem can be evaluated from performance and stability point 2653 of view. 2654 2655 If unsure, say N. 2656 2657config TEST_BPF 2658 tristate "Test BPF filter functionality" 2659 depends on m && NET 2660 help 2661 This builds the "test_bpf" module that runs various test vectors 2662 against the BPF interpreter or BPF JIT compiler depending on the 2663 current setting. This is in particular useful for BPF JIT compiler 2664 development, but also to run regression tests against changes in 2665 the interpreter code. It also enables test stubs for eBPF maps and 2666 verifier used by user space verifier testsuite. 2667 2668 If unsure, say N. 2669 2670config FIND_BIT_BENCHMARK 2671 tristate "Test find_bit functions" 2672 help 2673 This builds the "test_find_bit" module that measure find_*_bit() 2674 functions performance. 2675 2676 If unsure, say N. 2677 2678config FIND_BIT_BENCHMARK_RUST 2679 tristate "Test find_bit functions in Rust" 2680 depends on RUST 2681 help 2682 This builds the "find_bit_benchmark_rust" module. It is a micro 2683 benchmark that measures the performance of Rust functions that 2684 correspond to the find_*_bit() operations in C. It follows the 2685 FIND_BIT_BENCHMARK closely but will in general not yield same 2686 numbers due to extra bounds checks and overhead of foreign 2687 function calls. 2688 2689 If unsure, say N. 2690 2691config TEST_FIRMWARE 2692 tristate "Test firmware loading via userspace interface" 2693 depends on FW_LOADER 2694 help 2695 This builds the "test_firmware" module that creates a userspace 2696 interface for testing firmware loading. This can be used to 2697 control the triggering of firmware loading without needing an 2698 actual firmware-using device. The contents can be rechecked by 2699 userspace. 2700 2701 If unsure, say N. 2702 2703config TEST_SYSCTL 2704 tristate "sysctl test driver" 2705 depends on PROC_SYSCTL 2706 help 2707 This builds the "test_sysctl" module. This driver enables to test the 2708 proc sysctl interfaces available to drivers safely without affecting 2709 production knobs which might alter system functionality. 2710 2711 If unsure, say N. 2712 2713config BITOPS_KUNIT 2714 tristate "KUnit test for bitops" if !KUNIT_ALL_TESTS 2715 depends on KUNIT 2716 default KUNIT_ALL_TESTS 2717 help 2718 This option enables the KUnit test for the bitops library 2719 which provides functions for bit operations. 2720 2721 Note that this is derived from the original test_bitops module. 2722 For micro-benchmarks and compiler warning checks, enable TEST_BITOPS. 2723 2724 If unsure, say N. 2725 2726config BITFIELD_KUNIT 2727 tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS 2728 depends on KUNIT 2729 default KUNIT_ALL_TESTS 2730 help 2731 Enable this option to test the bitfield functions at boot. 2732 2733 KUnit tests run during boot and output the results to the debug log 2734 in TAP format (http://testanything.org/). Only useful for kernel devs 2735 running the KUnit test harness, and not intended for inclusion into a 2736 production build. 2737 2738 For more information on KUnit and unit tests in general please refer 2739 to the KUnit documentation in Documentation/dev-tools/kunit/. 2740 2741 If unsure, say N. 2742 2743config CHECKSUM_KUNIT 2744 tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS 2745 depends on KUNIT 2746 default KUNIT_ALL_TESTS 2747 help 2748 Enable this option to test the checksum functions at boot. 2749 2750 KUnit tests run during boot and output the results to the debug log 2751 in TAP format (http://testanything.org/). Only useful for kernel devs 2752 running the KUnit test harness, and not intended for inclusion into a 2753 production build. 2754 2755 For more information on KUnit and unit tests in general please refer 2756 to the KUnit documentation in Documentation/dev-tools/kunit/. 2757 2758 If unsure, say N. 2759 2760config UTIL_MACROS_KUNIT 2761 tristate "KUnit test util_macros.h functions at runtime" if !KUNIT_ALL_TESTS 2762 depends on KUNIT 2763 default KUNIT_ALL_TESTS 2764 help 2765 Enable this option to test the util_macros.h function at boot. 2766 2767 KUnit tests run during boot and output the results to the debug log 2768 in TAP format (http://testanything.org/). Only useful for kernel devs 2769 running the KUnit test harness, and not intended for inclusion into a 2770 production build. 2771 2772 For more information on KUnit and unit tests in general please refer 2773 to the KUnit documentation in Documentation/dev-tools/kunit/. 2774 2775 If unsure, say N. 2776 2777config HASH_KUNIT_TEST 2778 tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS 2779 depends on KUNIT 2780 default KUNIT_ALL_TESTS 2781 help 2782 Enable this option to test the kernel's string (<linux/stringhash.h>), and 2783 integer (<linux/hash.h>) hash functions on boot. 2784 2785 KUnit tests run during boot and output the results to the debug log 2786 in TAP format (https://testanything.org/). Only useful for kernel devs 2787 running the KUnit test harness, and not intended for inclusion into a 2788 production build. 2789 2790 For more information on KUnit and unit tests in general please refer 2791 to the KUnit documentation in Documentation/dev-tools/kunit/. 2792 2793 This is intended to help people writing architecture-specific 2794 optimized versions. If unsure, say N. 2795 2796config RESOURCE_KUNIT_TEST 2797 tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS 2798 depends on KUNIT 2799 default KUNIT_ALL_TESTS 2800 select GET_FREE_REGION 2801 help 2802 This builds the resource API unit test. 2803 Tests the logic of API provided by resource.c and ioport.h. 2804 For more information on KUnit and unit tests in general please refer 2805 to the KUnit documentation in Documentation/dev-tools/kunit/. 2806 2807 If unsure, say N. 2808 2809config SYSCTL_KUNIT_TEST 2810 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS 2811 depends on KUNIT 2812 default KUNIT_ALL_TESTS 2813 help 2814 This builds the proc sysctl unit test, which runs on boot. 2815 Tests the API contract and implementation correctness of sysctl. 2816 For more information on KUnit and unit tests in general please refer 2817 to the KUnit documentation in Documentation/dev-tools/kunit/. 2818 2819 If unsure, say N. 2820 2821config KFIFO_KUNIT_TEST 2822 tristate "KUnit Test for the generic kernel FIFO implementation" if !KUNIT_ALL_TESTS 2823 depends on KUNIT 2824 default KUNIT_ALL_TESTS 2825 help 2826 This builds the generic FIFO implementation KUnit test suite. 2827 It tests that the API and basic functionality of the kfifo type 2828 and associated macros. 2829 2830 For more information on KUnit and unit tests in general please refer 2831 to the KUnit documentation in Documentation/dev-tools/kunit/. 2832 2833 If unsure, say N. 2834 2835config LIST_KUNIT_TEST 2836 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS 2837 depends on KUNIT 2838 default KUNIT_ALL_TESTS 2839 help 2840 This builds the linked list KUnit test suite. 2841 It tests that the API and basic functionality of the list_head type 2842 and associated macros. 2843 2844 KUnit tests run during boot and output the results to the debug log 2845 in TAP format (https://testanything.org/). Only useful for kernel devs 2846 running the KUnit test harness, and not intended for inclusion into a 2847 production build. 2848 2849 For more information on KUnit and unit tests in general please refer 2850 to the KUnit documentation in Documentation/dev-tools/kunit/. 2851 2852 If unsure, say N. 2853 2854config LIST_PRIVATE_KUNIT_TEST 2855 tristate "KUnit Test for Kernel Private Linked-list structures" if !KUNIT_ALL_TESTS 2856 depends on KUNIT 2857 default KUNIT_ALL_TESTS 2858 help 2859 This builds the KUnit test for the private linked-list primitives 2860 defined in include/linux/list_private.h. 2861 2862 These primitives allow manipulation of list_head members that are 2863 marked as private and require special accessors (ACCESS_PRIVATE) 2864 to strip qualifiers or handle encapsulation. 2865 2866 If unsure, say N. 2867 2868config HASHTABLE_KUNIT_TEST 2869 tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS 2870 depends on KUNIT 2871 default KUNIT_ALL_TESTS 2872 help 2873 This builds the hashtable KUnit test suite. 2874 It tests the basic functionality of the API defined in 2875 include/linux/hashtable.h. For more information on KUnit and 2876 unit tests in general please refer to the KUnit documentation 2877 in Documentation/dev-tools/kunit/. 2878 2879 If unsure, say N. 2880 2881config LINEAR_RANGES_TEST 2882 tristate "KUnit test for linear_ranges" 2883 depends on KUNIT 2884 select LINEAR_RANGES 2885 help 2886 This builds the linear_ranges unit test, which runs on boot. 2887 Tests the linear_ranges logic correctness. 2888 For more information on KUnit and unit tests in general please refer 2889 to the KUnit documentation in Documentation/dev-tools/kunit/. 2890 2891 If unsure, say N. 2892 2893config CONTEXT_ANALYSIS_TEST 2894 bool "Compiler context-analysis warnings test" 2895 depends on EXPERT 2896 help 2897 This builds the test for compiler-based context analysis. The test 2898 does not add executable code to the kernel, but is meant to test that 2899 common patterns supported by the analysis do not result in false 2900 positive warnings. 2901 2902 When adding support for new context locks, it is strongly recommended 2903 to add supported patterns to this test. 2904 2905 If unsure, say N. 2906 2907config LIVEUPDATE_TEST 2908 bool "Live Update Kernel Test" 2909 default n 2910 depends on LIVEUPDATE 2911 help 2912 Enable a built-in kernel test module for the Live Update 2913 Orchestrator. 2914 2915 This module validates the File-Lifecycle-Bound subsystem by 2916 registering a set of mock FLB objects with any real file handlers 2917 that support live update (such as the memfd handler). 2918 2919 When live update operations are performed, this test module will 2920 output messages to the kernel log (dmesg), confirming that its 2921 registration and various callback functions (preserve, retrieve, 2922 finish, etc.) are being invoked correctly. 2923 2924 This is a debugging and regression testing tool for developers 2925 working on the Live Update subsystem. It should not be enabled in 2926 production kernels. 2927 2928 If unsure, say N 2929 2930config CMDLINE_KUNIT_TEST 2931 tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS 2932 depends on KUNIT 2933 default KUNIT_ALL_TESTS 2934 help 2935 This builds the cmdline API unit test. 2936 Tests the logic of API provided by cmdline.c. 2937 For more information on KUnit and unit tests in general please refer 2938 to the KUnit documentation in Documentation/dev-tools/kunit/. 2939 2940 If unsure, say N. 2941 2942config BASE64_KUNIT 2943 tristate "KUnit test for base64 decoding and encoding" if !KUNIT_ALL_TESTS 2944 depends on KUNIT 2945 default KUNIT_ALL_TESTS 2946 help 2947 This builds the base64 unit tests. 2948 2949 The tests cover the encoding and decoding logic of Base64 functions 2950 in the kernel. 2951 In addition to correctness checks, simple performance benchmarks 2952 for both encoding and decoding are also included. 2953 2954 For more information on KUnit and unit tests in general please refer 2955 to the KUnit documentation in Documentation/dev-tools/kunit/. 2956 2957 If unsure, say N. 2958 2959config BITS_TEST 2960 tristate "KUnit test for bit functions and macros" if !KUNIT_ALL_TESTS 2961 depends on KUNIT 2962 default KUNIT_ALL_TESTS 2963 help 2964 This builds the bits unit test. 2965 Tests the logic of macros defined in bits.h. 2966 For more information on KUnit and unit tests in general please refer 2967 to the KUnit documentation in Documentation/dev-tools/kunit/. 2968 2969 If unsure, say N. 2970 2971config SLUB_KUNIT_TEST 2972 tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS 2973 depends on SLUB_DEBUG && KUNIT 2974 default KUNIT_ALL_TESTS 2975 help 2976 This builds SLUB allocator unit test. 2977 Tests SLUB cache debugging functionality. 2978 For more information on KUnit and unit tests in general please refer 2979 to the KUnit documentation in Documentation/dev-tools/kunit/. 2980 2981 If unsure, say N. 2982 2983config RATIONAL_KUNIT_TEST 2984 tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS 2985 depends on KUNIT && RATIONAL 2986 default KUNIT_ALL_TESTS 2987 help 2988 This builds the rational math unit test. 2989 For more information on KUnit and unit tests in general please refer 2990 to the KUnit documentation in Documentation/dev-tools/kunit/. 2991 2992 If unsure, say N. 2993 2994config MEMCPY_KUNIT_TEST 2995 tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS 2996 depends on KUNIT 2997 default KUNIT_ALL_TESTS 2998 help 2999 Builds unit tests for memcpy(), memmove(), and memset() functions. 3000 For more information on KUnit and unit tests in general please refer 3001 to the KUnit documentation in Documentation/dev-tools/kunit/. 3002 3003 If unsure, say N. 3004 3005config MIN_HEAP_KUNIT_TEST 3006 tristate "Min heap test" if !KUNIT_ALL_TESTS 3007 depends on KUNIT 3008 default KUNIT_ALL_TESTS 3009 help 3010 This option enables the KUnit test suite for the min heap library 3011 which provides functions for creating and managing min heaps. 3012 The test suite checks the functionality of the min heap library. 3013 3014 If unsure, say N 3015 3016config IS_SIGNED_TYPE_KUNIT_TEST 3017 tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS 3018 depends on KUNIT 3019 default KUNIT_ALL_TESTS 3020 help 3021 Builds unit tests for the is_signed_type() macro. 3022 3023 For more information on KUnit and unit tests in general please refer 3024 to the KUnit documentation in Documentation/dev-tools/kunit/. 3025 3026 If unsure, say N. 3027 3028config OVERFLOW_KUNIT_TEST 3029 tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS 3030 depends on KUNIT 3031 default KUNIT_ALL_TESTS 3032 help 3033 Builds unit tests for the check_*_overflow(), size_*(), allocation, and 3034 related functions. 3035 3036 For more information on KUnit and unit tests in general please refer 3037 to the KUnit documentation in Documentation/dev-tools/kunit/. 3038 3039 If unsure, say N. 3040 3041config RANDSTRUCT_KUNIT_TEST 3042 tristate "Test randstruct structure layout randomization at runtime" if !KUNIT_ALL_TESTS 3043 depends on KUNIT 3044 default KUNIT_ALL_TESTS 3045 help 3046 Builds unit tests for the checking CONFIG_RANDSTRUCT=y, which 3047 randomizes structure layouts. 3048 3049config STACKINIT_KUNIT_TEST 3050 tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS 3051 depends on KUNIT 3052 default KUNIT_ALL_TESTS 3053 help 3054 Test if the kernel is zero-initializing stack variables and 3055 padding. Coverage is controlled by compiler flags, 3056 CONFIG_INIT_STACK_ALL_PATTERN or CONFIG_INIT_STACK_ALL_ZERO. 3057 3058config FORTIFY_KUNIT_TEST 3059 tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS 3060 depends on KUNIT 3061 default KUNIT_ALL_TESTS 3062 help 3063 Builds unit tests for checking internals of FORTIFY_SOURCE as used 3064 by the str*() and mem*() family of functions. For testing runtime 3065 traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests. 3066 3067config LONGEST_SYM_KUNIT_TEST 3068 tristate "Test the longest symbol possible" if !KUNIT_ALL_TESTS 3069 depends on KUNIT && KPROBES 3070 depends on !PREFIX_SYMBOLS && !CFI && !GCOV_KERNEL 3071 default KUNIT_ALL_TESTS 3072 help 3073 Tests the longest symbol possible 3074 3075 If unsure, say N. 3076 3077config HW_BREAKPOINT_KUNIT_TEST 3078 bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS 3079 depends on HAVE_HW_BREAKPOINT 3080 depends on KUNIT=y 3081 default KUNIT_ALL_TESTS 3082 help 3083 Tests for hw_breakpoint constraints accounting. 3084 3085 If unsure, say N. 3086 3087config SIPHASH_KUNIT_TEST 3088 tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS 3089 depends on KUNIT 3090 default KUNIT_ALL_TESTS 3091 help 3092 Enable this option to test the kernel's siphash (<linux/siphash.h>) hash 3093 functions on boot (or module load). 3094 3095 This is intended to help people writing architecture-specific 3096 optimized versions. If unsure, say N. 3097 3098config USERCOPY_KUNIT_TEST 3099 tristate "KUnit Test for user/kernel boundary protections" 3100 depends on KUNIT 3101 default KUNIT_ALL_TESTS 3102 help 3103 This builds the "usercopy_kunit" module that runs sanity checks 3104 on the copy_to/from_user infrastructure, making sure basic 3105 user/kernel boundary testing is working. 3106 3107config BLACKHOLE_DEV_KUNIT_TEST 3108 tristate "Test blackhole netdev functionality" if !KUNIT_ALL_TESTS 3109 depends on NET 3110 depends on KUNIT 3111 default KUNIT_ALL_TESTS 3112 help 3113 This builds the "blackhole_dev_kunit" module that validates the 3114 data path through this blackhole netdev. 3115 3116 If unsure, say N. 3117 3118config TEST_UDELAY 3119 tristate "udelay test driver" 3120 help 3121 This builds the "udelay_test" module that helps to make sure 3122 that udelay() is working properly. 3123 3124 If unsure, say N. 3125 3126config TEST_STATIC_KEYS 3127 tristate "Test static keys" 3128 depends on m 3129 help 3130 Test the static key interfaces. 3131 3132 If unsure, say N. 3133 3134config TEST_DYNAMIC_DEBUG 3135 tristate "Test DYNAMIC_DEBUG" 3136 depends on DYNAMIC_DEBUG 3137 help 3138 This module registers a tracer callback to count enabled 3139 pr_debugs in a 'do_debugging' function, then alters their 3140 enablements, calls the function, and compares counts. 3141 3142 If unsure, say N. 3143 3144config TEST_KMOD 3145 tristate "kmod stress tester" 3146 depends on m 3147 select TEST_LKM 3148 help 3149 Test the kernel's module loading mechanism: kmod. kmod implements 3150 support to load modules using the Linux kernel's usermode helper. 3151 This test provides a series of tests against kmod. 3152 3153 Although technically you can either build test_kmod as a module or 3154 into the kernel we disallow building it into the kernel since 3155 it stress tests request_module() and this will very likely cause 3156 some issues by taking over precious threads available from other 3157 module load requests, ultimately this could be fatal. 3158 3159 To run tests run: 3160 3161 tools/testing/selftests/kmod/kmod.sh --help 3162 3163 If unsure, say N. 3164 3165config TEST_RUNTIME 3166 bool 3167 3168config TEST_RUNTIME_MODULE 3169 bool 3170 3171config TEST_KALLSYMS 3172 tristate "module kallsyms find_symbol() test" 3173 depends on m 3174 select TEST_RUNTIME 3175 select TEST_RUNTIME_MODULE 3176 select TEST_KALLSYMS_A 3177 select TEST_KALLSYMS_B 3178 select TEST_KALLSYMS_C 3179 select TEST_KALLSYMS_D 3180 help 3181 This allows us to stress test find_symbol() through the kallsyms 3182 used to place symbols on the kernel ELF kallsyms and modules kallsyms 3183 where we place kernel symbols such as exported symbols. 3184 3185 We have four test modules: 3186 3187 A: has KALLSYSMS_NUMSYMS exported symbols 3188 B: uses one of A's symbols 3189 C: adds KALLSYMS_SCALE_FACTOR * KALLSYSMS_NUMSYMS exported 3190 D: adds 2 * the symbols than C 3191 3192 We stress test find_symbol() through two means: 3193 3194 1) Upon load of B it will trigger simplify_symbols() to look for the 3195 one symbol it uses from the module A with tons of symbols. This is an 3196 indirect way for us to have B call resolve_symbol_wait() upon module 3197 load. This will eventually call find_symbol() which will eventually 3198 try to find the symbols used with find_exported_symbol_in_section(). 3199 find_exported_symbol_in_section() uses bsearch() so a binary search 3200 for each symbol. Binary search will at worst be O(log(n)) so the 3201 larger TEST_MODULE_KALLSYSMS the worse the search. 3202 3203 2) The selftests should load C first, before B. Upon B's load towards 3204 the end right before we call module B's init routine we get 3205 complete_formation() called on the module. That will first check 3206 for duplicate symbols with the call to verify_exported_symbols(). 3207 That is when we'll force iteration on module C's insane symbol list. 3208 Since it has 10 * KALLSYMS_NUMSYMS it means we can first test 3209 just loading B without C. The amount of time it takes to load C Vs 3210 B can give us an idea of the impact growth of the symbol space and 3211 give us projection. Module A only uses one symbol from B so to allow 3212 this scaling in module C to be proportional, if it used more symbols 3213 then the first test would be doing more and increasing just the 3214 search space would be slightly different. The last module, module D 3215 will just increase the search space by twice the number of symbols in 3216 C so to allow for full projects. 3217 3218 tools/testing/selftests/module/find_symbol.sh 3219 3220 The current defaults will incur a build delay of about 7 minutes 3221 on an x86_64 with only 8 cores. Enable this only if you want to 3222 stress test find_symbol() with thousands of symbols. At the same 3223 time this is also useful to test building modules with thousands of 3224 symbols, and if BTF is enabled this also stress tests adding BTF 3225 information for each module. Currently enabling many more symbols 3226 will segfault the build system. 3227 3228 If unsure, say N. 3229 3230if TEST_KALLSYMS 3231 3232config TEST_KALLSYMS_A 3233 tristate 3234 depends on m 3235 3236config TEST_KALLSYMS_B 3237 tristate 3238 depends on m 3239 3240config TEST_KALLSYMS_C 3241 tristate 3242 depends on m 3243 3244config TEST_KALLSYMS_D 3245 tristate 3246 depends on m 3247 3248choice 3249 prompt "Kallsym test range" 3250 default TEST_KALLSYMS_LARGE 3251 help 3252 Selecting something other than "Fast" will enable tests which slow 3253 down the build and may crash your build. 3254 3255config TEST_KALLSYMS_FAST 3256 bool "Fast builds" 3257 help 3258 You won't really be testing kallsysms, so this just helps fast builds 3259 when allmodconfig is used.. 3260 3261config TEST_KALLSYMS_LARGE 3262 bool "Enable testing kallsyms with large exports" 3263 help 3264 This will enable larger number of symbols. This will slow down 3265 your build considerably. 3266 3267config TEST_KALLSYMS_MAX 3268 bool "Known kallsysms limits" 3269 help 3270 This will enable exports to the point we know we'll start crashing 3271 builds. 3272 3273endchoice 3274 3275config TEST_KALLSYMS_NUMSYMS 3276 int "test kallsyms number of symbols" 3277 range 2 10000 3278 default 2 if TEST_KALLSYMS_FAST 3279 default 100 if TEST_KALLSYMS_LARGE 3280 default 10000 if TEST_KALLSYMS_MAX 3281 help 3282 The number of symbols to create on TEST_KALLSYMS_A, only one of which 3283 module TEST_KALLSYMS_B will use. This also will be used 3284 for how many symbols TEST_KALLSYMS_C will have, scaled up by 3285 TEST_KALLSYMS_SCALE_FACTOR. Note that setting this to 10,000 will 3286 trigger a segfault today, don't use anything close to it unless 3287 you are aware that this should not be used for automated build tests. 3288 3289config TEST_KALLSYMS_SCALE_FACTOR 3290 int "test kallsyms scale factor" 3291 default 8 3292 help 3293 How many more unusued symbols will TEST_KALLSYSMS_C have than 3294 TEST_KALLSYMS_A. If 8, then module C will have 8 * syms 3295 than module A. Then TEST_KALLSYMS_D will have double the amount 3296 of symbols than C so to allow projections. 3297 3298endif # TEST_KALLSYMS 3299 3300config TEST_DEBUG_VIRTUAL 3301 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 3302 depends on DEBUG_VIRTUAL 3303 help 3304 Test the kernel's ability to detect incorrect calls to 3305 virt_to_phys() done against the non-linear part of the 3306 kernel's virtual address map. 3307 3308 If unsure, say N. 3309 3310config TEST_MEMCAT_P 3311 tristate "Test memcat_p() helper function" 3312 help 3313 Test the memcat_p() helper for correctly merging two 3314 pointer arrays together. 3315 3316 If unsure, say N. 3317 3318config TEST_OBJAGG 3319 tristate "Perform selftest on object aggreration manager" 3320 default n 3321 depends on OBJAGG 3322 help 3323 Enable this option to test object aggregation manager on boot 3324 (or module load). 3325 3326config TEST_MEMINIT 3327 tristate "Test heap/page initialization" 3328 help 3329 Test if the kernel is zero-initializing heap and page allocations. 3330 This can be useful to test init_on_alloc and init_on_free features. 3331 3332 If unsure, say N. 3333 3334config TEST_HMM 3335 tristate "Test HMM (Heterogeneous Memory Management)" 3336 depends on TRANSPARENT_HUGEPAGE 3337 depends on DEVICE_PRIVATE 3338 select HMM_MIRROR 3339 select MMU_NOTIFIER 3340 help 3341 This is a pseudo device driver solely for testing HMM. 3342 Say M here if you want to build the HMM test module. 3343 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests. 3344 3345 If unsure, say N. 3346 3347config TEST_FREE_PAGES 3348 tristate "Test freeing pages" 3349 help 3350 Test that a memory leak does not occur due to a race between 3351 freeing a block of pages and a speculative page reference. 3352 Loading this module is safe if your kernel has the bug fixed. 3353 If the bug is not fixed, it will leak gigabytes of memory and 3354 probably OOM your system. 3355 3356config TEST_FPU 3357 tristate "Test floating point operations in kernel space" 3358 depends on ARCH_HAS_KERNEL_FPU_SUPPORT && !KCOV_INSTRUMENT_ALL 3359 help 3360 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu 3361 which will trigger a sequence of floating point operations. This is used 3362 for self-testing floating point control register setting in 3363 kernel_fpu_begin(). 3364 3365 If unsure, say N. 3366 3367config TEST_CLOCKSOURCE_WATCHDOG 3368 tristate "Test clocksource watchdog in kernel space" 3369 depends on CLOCKSOURCE_WATCHDOG 3370 help 3371 Enable this option to create a kernel module that will trigger 3372 a test of the clocksource watchdog. This module may be loaded 3373 via modprobe or insmod in which case it will run upon being 3374 loaded, or it may be built in, in which case it will run 3375 shortly after boot. 3376 3377 If unsure, say N. 3378 3379config TEST_OBJPOOL 3380 tristate "Test module for correctness and stress of objpool" 3381 default n 3382 depends on m && DEBUG_KERNEL 3383 help 3384 This builds the "test_objpool" module that should be used for 3385 correctness verification and concurrent testings of objects 3386 allocation and reclamation. 3387 3388 If unsure, say N. 3389 3390config TEST_KEXEC_HANDOVER 3391 bool "Test for Kexec HandOver" 3392 default n 3393 depends on KEXEC_HANDOVER 3394 help 3395 This option enables test for Kexec HandOver (KHO). 3396 The test consists of two parts: saving kernel data before kexec and 3397 restoring the data after kexec and verifying that it was properly 3398 handed over. This test module creates and saves data on the boot of 3399 the first kernel and restores and verifies the data on the boot of 3400 kexec'ed kernel. 3401 3402 For detailed documentation about KHO, see Documentation/core-api/kho. 3403 3404 To run the test run: 3405 3406 tools/testing/selftests/kho/vmtest.sh -h 3407 3408 If unsure, say N. 3409 3410config RATELIMIT_KUNIT_TEST 3411 tristate "KUnit Test for correctness and stress of ratelimit" if !KUNIT_ALL_TESTS 3412 depends on KUNIT 3413 default KUNIT_ALL_TESTS 3414 help 3415 This builds the "test_ratelimit" module that should be used 3416 for correctness verification and concurrent testings of rate 3417 limiting. 3418 3419 If unsure, say N. 3420 3421config UUID_KUNIT_TEST 3422 tristate "KUnit test for UUID" if !KUNIT_ALL_TESTS 3423 depends on KUNIT 3424 default KUNIT_ALL_TESTS 3425 help 3426 This option enables the KUnit test suite for the uuid library, 3427 which provides functions for generating and parsing UUID and GUID. 3428 The test suite checks parsing of UUID and GUID strings. 3429 3430 If unsure, say N. 3431 3432config INT_POW_KUNIT_TEST 3433 tristate "Integer exponentiation (int_pow) test" if !KUNIT_ALL_TESTS 3434 depends on KUNIT 3435 default KUNIT_ALL_TESTS 3436 help 3437 This option enables the KUnit test suite for the int_pow function, 3438 which performs integer exponentiation. The test suite is designed to 3439 verify that the implementation of int_pow correctly computes the power 3440 of a given base raised to a given exponent. 3441 3442 Enabling this option will include tests that check various scenarios 3443 and edge cases to ensure the accuracy and reliability of the exponentiation 3444 function. 3445 3446 If unsure, say N 3447 3448config INT_SQRT_KUNIT_TEST 3449 tristate "Integer square root test" if !KUNIT_ALL_TESTS 3450 depends on KUNIT 3451 default KUNIT_ALL_TESTS 3452 help 3453 This option enables the KUnit test suite for the int_sqrt() function, 3454 which performs square root calculation. The test suite checks 3455 various scenarios, including edge cases, to ensure correctness. 3456 3457 Enabling this option will include tests that check various scenarios 3458 and edge cases to ensure the accuracy and reliability of the square root 3459 function. 3460 3461 If unsure, say N 3462 3463config INT_LOG_KUNIT_TEST 3464 tristate "Integer log (int_log) test" if !KUNIT_ALL_TESTS 3465 depends on KUNIT 3466 default KUNIT_ALL_TESTS 3467 help 3468 This option enables the KUnit test suite for the int_log library, which 3469 provides two functions to compute the integer logarithm in base 2 and 3470 base 10, called respectively as intlog2 and intlog10. 3471 3472 If unsure, say N 3473 3474config GCD_KUNIT_TEST 3475 tristate "Greatest common divisor test" if !KUNIT_ALL_TESTS 3476 depends on KUNIT 3477 default KUNIT_ALL_TESTS 3478 help 3479 This option enables the KUnit test suite for the gcd() function, 3480 which computes the greatest common divisor of two numbers. 3481 3482 This test suite verifies the correctness of gcd() across various 3483 scenarios, including edge cases. 3484 3485 If unsure, say N 3486 3487config PRIME_NUMBERS_KUNIT_TEST 3488 tristate "Prime number generator test" if !KUNIT_ALL_TESTS 3489 depends on KUNIT 3490 depends on PRIME_NUMBERS 3491 default KUNIT_ALL_TESTS 3492 help 3493 This option enables the KUnit test suite for the {is,next}_prime_number 3494 functions. 3495 3496 Enabling this option will include tests that compare the prime number 3497 generator functions against a brute force implementation. 3498 3499 If unsure, say N 3500 3501config GLOB_KUNIT_TEST 3502 tristate "Glob matching test" if !KUNIT_ALL_TESTS 3503 depends on GLOB 3504 depends on KUNIT 3505 default KUNIT_ALL_TESTS 3506 help 3507 Enable this option to test the glob functions at runtime. 3508 3509 This test suite verifies the correctness of glob_match() across various 3510 scenarios, including edge cases. 3511 3512 If unsure, say N 3513 3514endif # RUNTIME_TESTING_MENU 3515 3516config ARCH_USE_MEMTEST 3517 bool 3518 help 3519 An architecture should select this when it uses early_memtest() 3520 during boot process. 3521 3522config MEMTEST 3523 bool "Memtest" 3524 depends on ARCH_USE_MEMTEST 3525 help 3526 This option adds a kernel parameter 'memtest', which allows memtest 3527 to be set and executed. 3528 memtest=0, mean disabled; -- default 3529 memtest=1, mean do 1 test pattern; 3530 ... 3531 memtest=17, mean do 17 test patterns. 3532 If you are unsure how to answer this question, answer N. 3533 3534 3535 3536config HYPERV_TESTING 3537 bool "Microsoft Hyper-V driver testing" 3538 default n 3539 depends on HYPERV && DEBUG_FS 3540 help 3541 Select this option to enable Hyper-V vmbus testing. 3542 3543endmenu # "Kernel Testing and Coverage" 3544 3545menu "Rust hacking" 3546 3547config RUST_DEBUG_ASSERTIONS 3548 bool "Debug assertions" 3549 depends on RUST 3550 help 3551 Enables rustc's `-Cdebug-assertions` codegen option. 3552 3553 This flag lets you turn `cfg(debug_assertions)` conditional 3554 compilation on or off. This can be used to enable extra debugging 3555 code in development but not in production. For example, it controls 3556 the behavior of the standard library's `debug_assert!` macro. 3557 3558 Note that this will apply to all Rust code, including `core`. 3559 3560 If unsure, say N. 3561 3562config RUST_OVERFLOW_CHECKS 3563 bool "Overflow checks" 3564 default y 3565 depends on RUST 3566 help 3567 Enables rustc's `-Coverflow-checks` codegen option. 3568 3569 This flag allows you to control the behavior of runtime integer 3570 overflow. When overflow-checks are enabled, a Rust panic will occur 3571 on overflow. 3572 3573 Note that this will apply to all Rust code, including `core`. 3574 3575 If unsure, say Y. 3576 3577config RUST_BUILD_ASSERT_ALLOW 3578 bool "Allow unoptimized build-time assertions" 3579 depends on RUST 3580 help 3581 Controls how `build_error!` and `build_assert!` are handled during the build. 3582 3583 If calls to them exist in the binary, it may indicate a violated invariant 3584 or that the optimizer failed to verify the invariant during compilation. 3585 3586 This should not happen, thus by default the build is aborted. However, 3587 as an escape hatch, you can choose Y here to ignore them during build 3588 and let the check be carried at runtime (with `panic!` being called if 3589 the check fails). 3590 3591 If unsure, say N. 3592 3593config RUST_KERNEL_DOCTESTS 3594 bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS 3595 depends on RUST && KUNIT=y 3596 default KUNIT_ALL_TESTS 3597 help 3598 This builds the documentation tests of the `kernel` crate 3599 as KUnit tests. 3600 3601 For more information on KUnit and unit tests in general, 3602 please refer to the KUnit documentation in Documentation/dev-tools/kunit/. 3603 3604 If unsure, say N. 3605 3606endmenu # "Rust" 3607 3608endmenu # Kernel hacking 3609