1# SPDX-License-Identifier: GPL-2.0-only 2menu "Kernel hacking" 3 4menu "printk and dmesg options" 5 6config PRINTK_TIME 7 bool "Show timing information on printks" 8 depends on PRINTK 9 help 10 Selecting this option causes time stamps of the printk() 11 messages to be added to the output of the syslog() system 12 call and at the console. 13 14 The timestamp is always recorded internally, and exported 15 to /dev/kmsg. This flag just specifies if the timestamp should 16 be included, not that the timestamp is recorded. 17 18 The behavior is also controlled by the kernel command line 19 parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst 20 21config PRINTK_CALLER 22 bool "Show caller information on printks" 23 depends on PRINTK 24 help 25 Selecting this option causes printk() to add a caller "thread id" (if 26 in task context) or a caller "processor id" (if not in task context) 27 to every message. 28 29 This option is intended for environments where multiple threads 30 concurrently call printk() for many times, for it is difficult to 31 interpret without knowing where these lines (or sometimes individual 32 line which was divided into multiple lines due to race) came from. 33 34 Since toggling after boot makes the code racy, currently there is 35 no option to enable/disable at the kernel command line parameter or 36 sysfs interface. 37 38config STACKTRACE_BUILD_ID 39 bool "Show build ID information in stacktraces" 40 depends on PRINTK 41 help 42 Selecting this option adds build ID information for symbols in 43 stacktraces printed with the printk format '%p[SR]b'. 44 45 This option is intended for distros where debuginfo is not easily 46 accessible but can be downloaded given the build ID of the vmlinux or 47 kernel module where the function is located. 48 49config CONSOLE_LOGLEVEL_DEFAULT 50 int "Default console loglevel (1-15)" 51 range 1 15 52 default "7" 53 help 54 Default loglevel to determine what will be printed on the console. 55 56 Setting a default here is equivalent to passing in loglevel=<x> in 57 the kernel bootargs. loglevel=<x> continues to override whatever 58 value is specified here as well. 59 60 Note: This does not affect the log level of un-prefixed printk() 61 usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT 62 option. 63 64config CONSOLE_LOGLEVEL_QUIET 65 int "quiet console loglevel (1-15)" 66 range 1 15 67 default "4" 68 help 69 loglevel to use when "quiet" is passed on the kernel commandline. 70 71 When "quiet" is passed on the kernel commandline this loglevel 72 will be used as the loglevel. IOW passing "quiet" will be the 73 equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>" 74 75config MESSAGE_LOGLEVEL_DEFAULT 76 int "Default message log level (1-7)" 77 range 1 7 78 default "4" 79 help 80 Default log level for printk statements with no specified priority. 81 82 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks 83 that are auditing their logs closely may want to set it to a lower 84 priority. 85 86 Note: This does not affect what message level gets printed on the console 87 by default. To change that, use loglevel=<x> in the kernel bootargs, 88 or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value. 89 90config BOOT_PRINTK_DELAY 91 bool "Delay each boot printk message by N milliseconds" 92 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY 93 help 94 This build option allows you to read kernel boot messages 95 by inserting a short delay after each one. The delay is 96 specified in milliseconds on the kernel command line, 97 using "boot_delay=N". 98 99 It is likely that you would also need to use "lpj=M" to preset 100 the "loops per jiffie" value. 101 See a previous boot log for the "lpj" value to use for your 102 system, and then set "lpj=M" before setting "boot_delay=N". 103 NOTE: Using this option may adversely affect SMP systems. 104 I.e., processors other than the first one may not boot up. 105 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect 106 what it believes to be lockup conditions. 107 108config DYNAMIC_DEBUG 109 bool "Enable dynamic printk() support" 110 default n 111 depends on PRINTK 112 depends on (DEBUG_FS || PROC_FS) 113 select DYNAMIC_DEBUG_CORE 114 help 115 116 Compiles debug level messages into the kernel, which would not 117 otherwise be available at runtime. These messages can then be 118 enabled/disabled based on various levels of scope - per source file, 119 function, module, format string, and line number. This mechanism 120 implicitly compiles in all pr_debug() and dev_dbg() calls, which 121 enlarges the kernel text size by about 2%. 122 123 If a source file is compiled with DEBUG flag set, any 124 pr_debug() calls in it are enabled by default, but can be 125 disabled at runtime as below. Note that DEBUG flag is 126 turned on by many CONFIG_*DEBUG* options. 127 128 Usage: 129 130 Dynamic debugging is controlled via the 'dynamic_debug/control' file, 131 which is contained in the 'debugfs' filesystem or procfs. 132 Thus, the debugfs or procfs filesystem must first be mounted before 133 making use of this feature. 134 We refer the control file as: <debugfs>/dynamic_debug/control. This 135 file contains a list of the debug statements that can be enabled. The 136 format for each line of the file is: 137 138 filename:lineno [module]function flags format 139 140 filename : source file of the debug statement 141 lineno : line number of the debug statement 142 module : module that contains the debug statement 143 function : function that contains the debug statement 144 flags : '=p' means the line is turned 'on' for printing 145 format : the format used for the debug statement 146 147 From a live system: 148 149 nullarbor:~ # cat <debugfs>/dynamic_debug/control 150 # filename:lineno [module]function flags format 151 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012" 152 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012" 153 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012" 154 155 Example usage: 156 157 // enable the message at line 1603 of file svcsock.c 158 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' > 159 <debugfs>/dynamic_debug/control 160 161 // enable all the messages in file svcsock.c 162 nullarbor:~ # echo -n 'file svcsock.c +p' > 163 <debugfs>/dynamic_debug/control 164 165 // enable all the messages in the NFS server module 166 nullarbor:~ # echo -n 'module nfsd +p' > 167 <debugfs>/dynamic_debug/control 168 169 // enable all 12 messages in the function svc_process() 170 nullarbor:~ # echo -n 'func svc_process +p' > 171 <debugfs>/dynamic_debug/control 172 173 // disable all 12 messages in the function svc_process() 174 nullarbor:~ # echo -n 'func svc_process -p' > 175 <debugfs>/dynamic_debug/control 176 177 See Documentation/admin-guide/dynamic-debug-howto.rst for additional 178 information. 179 180config DYNAMIC_DEBUG_CORE 181 bool "Enable core function of dynamic debug support" 182 depends on PRINTK 183 depends on (DEBUG_FS || PROC_FS) 184 help 185 Enable core functional support of dynamic debug. It is useful 186 when you want to tie dynamic debug to your kernel modules with 187 DYNAMIC_DEBUG_MODULE defined for each of them, especially for 188 the case of embedded system where the kernel image size is 189 sensitive for people. 190 191config SYMBOLIC_ERRNAME 192 bool "Support symbolic error names in printf" 193 default y if PRINTK 194 help 195 If you say Y here, the kernel's printf implementation will 196 be able to print symbolic error names such as ENOSPC instead 197 of the number 28. It makes the kernel image slightly larger 198 (about 3KB), but can make the kernel logs easier to read. 199 200config DEBUG_BUGVERBOSE 201 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT 202 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE) 203 default y 204 help 205 Say Y here to make BUG() panics output the file name and line number 206 of the BUG call as well as the EIP and oops trace. This aids 207 debugging but costs about 70-100K of memory. 208 209endmenu # "printk and dmesg options" 210 211config DEBUG_KERNEL 212 bool "Kernel debugging" 213 help 214 Say Y here if you are developing drivers or trying to debug and 215 identify kernel problems. 216 217config DEBUG_MISC 218 bool "Miscellaneous debug code" 219 default DEBUG_KERNEL 220 depends on DEBUG_KERNEL 221 help 222 Say Y here if you need to enable miscellaneous debug code that should 223 be under a more specific debug option but isn't. 224 225menu "Compile-time checks and compiler options" 226 227config DEBUG_INFO 228 bool 229 help 230 A kernel debug info option other than "None" has been selected 231 in the "Debug information" choice below, indicating that debug 232 information will be generated for build targets. 233 234# Clang is known to generate .{s,u}leb128 with symbol deltas with DWARF5, which 235# some targets may not support: https://sourceware.org/bugzilla/show_bug.cgi?id=27215 236config AS_HAS_NON_CONST_LEB128 237 def_bool $(as-instr,.uleb128 .Lexpr_end4 - .Lexpr_start3\n.Lexpr_start3:\n.Lexpr_end4:) 238 239choice 240 prompt "Debug information" 241 depends on DEBUG_KERNEL 242 help 243 Selecting something other than "None" results in a kernel image 244 that will include debugging info resulting in a larger kernel image. 245 This adds debug symbols to the kernel and modules (gcc -g), and 246 is needed if you intend to use kernel crashdump or binary object 247 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 248 249 Choose which version of DWARF debug info to emit. If unsure, 250 select "Toolchain default". 251 252config DEBUG_INFO_NONE 253 bool "Disable debug information" 254 help 255 Do not build the kernel with debugging information, which will 256 result in a faster and smaller build. 257 258config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT 259 bool "Rely on the toolchain's implicit default DWARF version" 260 select DEBUG_INFO 261 depends on !CC_IS_CLANG || AS_IS_LLVM || CLANG_VERSION < 140000 || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_LEB128) 262 help 263 The implicit default version of DWARF debug info produced by a 264 toolchain changes over time. 265 266 This can break consumers of the debug info that haven't upgraded to 267 support newer revisions, and prevent testing newer versions, but 268 those should be less common scenarios. 269 270config DEBUG_INFO_DWARF4 271 bool "Generate DWARF Version 4 debuginfo" 272 select DEBUG_INFO 273 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502) 274 help 275 Generate DWARF v4 debug info. This requires gcc 4.5+, binutils 2.35.2 276 if using clang without clang's integrated assembler, and gdb 7.0+. 277 278 If you have consumers of DWARF debug info that are not ready for 279 newer revisions of DWARF, you may wish to choose this or have your 280 config select this. 281 282config DEBUG_INFO_DWARF5 283 bool "Generate DWARF Version 5 debuginfo" 284 select DEBUG_INFO 285 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_LEB128) 286 help 287 Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc 288 5.0+ accepts the -gdwarf-5 flag but only had partial support for some 289 draft features until 7.0), and gdb 8.0+. 290 291 Changes to the structure of debug info in Version 5 allow for around 292 15-18% savings in resulting image and debug info section sizes as 293 compared to DWARF Version 4. DWARF Version 5 standardizes previous 294 extensions such as accelerators for symbol indexing and the format 295 for fission (.dwo/.dwp) files. Users may not want to select this 296 config if they rely on tooling that has not yet been updated to 297 support DWARF Version 5. 298 299endchoice # "Debug information" 300 301if DEBUG_INFO 302 303config DEBUG_INFO_REDUCED 304 bool "Reduce debugging information" 305 help 306 If you say Y here gcc is instructed to generate less debugging 307 information for structure types. This means that tools that 308 need full debugging information (like kgdb or systemtap) won't 309 be happy. But if you merely need debugging information to 310 resolve line numbers there is no loss. Advantage is that 311 build directory object sizes shrink dramatically over a full 312 DEBUG_INFO build and compile times are reduced too. 313 Only works with newer gcc versions. 314 315choice 316 prompt "Compressed Debug information" 317 help 318 Compress the resulting debug info. Results in smaller debug info sections, 319 but requires that consumers are able to decompress the results. 320 321 If unsure, choose DEBUG_INFO_COMPRESSED_NONE. 322 323config DEBUG_INFO_COMPRESSED_NONE 324 bool "Don't compress debug information" 325 help 326 Don't compress debug info sections. 327 328config DEBUG_INFO_COMPRESSED_ZLIB 329 bool "Compress debugging information with zlib" 330 depends on $(cc-option,-gz=zlib) 331 depends on $(ld-option,--compress-debug-sections=zlib) 332 help 333 Compress the debug information using zlib. Requires GCC 5.0+ or Clang 334 5.0+, binutils 2.26+, and zlib. 335 336 Users of dpkg-deb via scripts/package/builddeb may find an increase in 337 size of their debug .deb packages with this config set, due to the 338 debug info being compressed with zlib, then the object files being 339 recompressed with a different compression scheme. But this is still 340 preferable to setting $KDEB_COMPRESS to "none" which would be even 341 larger. 342 343config DEBUG_INFO_COMPRESSED_ZSTD 344 bool "Compress debugging information with zstd" 345 depends on $(cc-option,-gz=zstd) 346 depends on $(ld-option,--compress-debug-sections=zstd) 347 help 348 Compress the debug information using zstd. This may provide better 349 compression than zlib, for about the same time costs, but requires newer 350 toolchain support. Requires GCC 13.0+ or Clang 16.0+, binutils 2.40+, and 351 zstd. 352 353endchoice # "Compressed Debug information" 354 355config DEBUG_INFO_SPLIT 356 bool "Produce split debuginfo in .dwo files" 357 depends on $(cc-option,-gsplit-dwarf) 358 help 359 Generate debug info into separate .dwo files. This significantly 360 reduces the build directory size for builds with DEBUG_INFO, 361 because it stores the information only once on disk in .dwo 362 files instead of multiple times in object files and executables. 363 In addition the debug information is also compressed. 364 365 Requires recent gcc (4.7+) and recent gdb/binutils. 366 Any tool that packages or reads debug information would need 367 to know about the .dwo files and include them. 368 Incompatible with older versions of ccache. 369 370config DEBUG_INFO_BTF 371 bool "Generate BTF typeinfo" 372 depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED 373 depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST 374 depends on BPF_SYSCALL 375 depends on !DEBUG_INFO_DWARF5 || PAHOLE_VERSION >= 121 376 help 377 Generate deduplicated BTF type information from DWARF debug info. 378 Turning this on expects presence of pahole tool, which will convert 379 DWARF type info into equivalent deduplicated BTF type info. 380 381config PAHOLE_HAS_SPLIT_BTF 382 def_bool PAHOLE_VERSION >= 119 383 384config PAHOLE_HAS_BTF_TAG 385 def_bool PAHOLE_VERSION >= 123 386 depends on CC_IS_CLANG 387 help 388 Decide whether pahole emits btf_tag attributes (btf_type_tag and 389 btf_decl_tag) or not. Currently only clang compiler implements 390 these attributes, so make the config depend on CC_IS_CLANG. 391 392config PAHOLE_HAS_LANG_EXCLUDE 393 def_bool PAHOLE_VERSION >= 124 394 help 395 Support for the --lang_exclude flag which makes pahole exclude 396 compilation units from the supplied language. Used in Kbuild to 397 omit Rust CUs which are not supported in version 1.24 of pahole, 398 otherwise it would emit malformed kernel and module binaries when 399 using DEBUG_INFO_BTF_MODULES. 400 401config DEBUG_INFO_BTF_MODULES 402 def_bool y 403 depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF 404 help 405 Generate compact split BTF type information for kernel modules. 406 407config MODULE_ALLOW_BTF_MISMATCH 408 bool "Allow loading modules with non-matching BTF type info" 409 depends on DEBUG_INFO_BTF_MODULES 410 help 411 For modules whose split BTF does not match vmlinux, load without 412 BTF rather than refusing to load. The default behavior with 413 module BTF enabled is to reject modules with such mismatches; 414 this option will still load module BTF where possible but ignore 415 it when a mismatch is found. 416 417config GDB_SCRIPTS 418 bool "Provide GDB scripts for kernel debugging" 419 help 420 This creates the required links to GDB helper scripts in the 421 build directory. If you load vmlinux into gdb, the helper 422 scripts will be automatically imported by gdb as well, and 423 additional functions are available to analyze a Linux kernel 424 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst 425 for further details. 426 427endif # DEBUG_INFO 428 429config FRAME_WARN 430 int "Warn for stack frames larger than" 431 range 0 8192 432 default 0 if KMSAN 433 default 2048 if GCC_PLUGIN_LATENT_ENTROPY 434 default 2048 if PARISC 435 default 1536 if (!64BIT && XTENSA) 436 default 1280 if KASAN && !64BIT 437 default 1024 if !64BIT 438 default 2048 if 64BIT 439 help 440 Tell the compiler to warn at build time for stack frames larger than this. 441 Setting this too low will cause a lot of warnings. 442 Setting it to 0 disables the warning. 443 444config STRIP_ASM_SYMS 445 bool "Strip assembler-generated symbols during link" 446 default n 447 help 448 Strip internal assembler-generated symbols during a link (symbols 449 that look like '.Lxxx') so they don't pollute the output of 450 get_wchan() and suchlike. 451 452config READABLE_ASM 453 bool "Generate readable assembler code" 454 depends on DEBUG_KERNEL 455 depends on CC_IS_GCC 456 help 457 Disable some compiler optimizations that tend to generate human unreadable 458 assembler output. This may make the kernel slightly slower, but it helps 459 to keep kernel developers who have to stare a lot at assembler listings 460 sane. 461 462config HEADERS_INSTALL 463 bool "Install uapi headers to usr/include" 464 depends on !UML 465 help 466 This option will install uapi headers (headers exported to user-space) 467 into the usr/include directory for use during the kernel build. 468 This is unneeded for building the kernel itself, but needed for some 469 user-space program samples. It is also needed by some features such 470 as uapi header sanity checks. 471 472config DEBUG_SECTION_MISMATCH 473 bool "Enable full Section mismatch analysis" 474 depends on CC_IS_GCC 475 help 476 The section mismatch analysis checks if there are illegal 477 references from one section to another section. 478 During linktime or runtime, some sections are dropped; 479 any use of code/data previously in these sections would 480 most likely result in an oops. 481 In the code, functions and variables are annotated with 482 __init,, etc. (see the full list in include/linux/init.h), 483 which results in the code/data being placed in specific sections. 484 The section mismatch analysis is always performed after a full 485 kernel build, and enabling this option causes the following 486 additional step to occur: 487 - Add the option -fno-inline-functions-called-once to gcc commands. 488 When inlining a function annotated with __init in a non-init 489 function, we would lose the section information and thus 490 the analysis would not catch the illegal reference. 491 This option tells gcc to inline less (but it does result in 492 a larger kernel). 493 494config SECTION_MISMATCH_WARN_ONLY 495 bool "Make section mismatch errors non-fatal" 496 default y 497 help 498 If you say N here, the build process will fail if there are any 499 section mismatch, instead of just throwing warnings. 500 501 If unsure, say Y. 502 503config DEBUG_FORCE_FUNCTION_ALIGN_64B 504 bool "Force all function address 64B aligned" 505 depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC) 506 select FUNCTION_ALIGNMENT_64B 507 help 508 There are cases that a commit from one domain changes the function 509 address alignment of other domains, and cause magic performance 510 bump (regression or improvement). Enable this option will help to 511 verify if the bump is caused by function alignment changes, while 512 it will slightly increase the kernel size and affect icache usage. 513 514 It is mainly for debug and performance tuning use. 515 516# 517# Select this config option from the architecture Kconfig, if it 518# is preferred to always offer frame pointers as a config 519# option on the architecture (regardless of KERNEL_DEBUG): 520# 521config ARCH_WANT_FRAME_POINTERS 522 bool 523 524config FRAME_POINTER 525 bool "Compile the kernel with frame pointers" 526 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS 527 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 528 help 529 If you say Y here the resulting kernel image will be slightly 530 larger and slower, but it gives very useful debugging information 531 in case of kernel bugs. (precise oopses/stacktraces/warnings) 532 533config OBJTOOL 534 bool 535 536config STACK_VALIDATION 537 bool "Compile-time stack metadata validation" 538 depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER 539 select OBJTOOL 540 default n 541 help 542 Validate frame pointer rules at compile-time. This helps ensure that 543 runtime stack traces are more reliable. 544 545 For more information, see 546 tools/objtool/Documentation/objtool.txt. 547 548config NOINSTR_VALIDATION 549 bool 550 depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY 551 select OBJTOOL 552 default y 553 554config VMLINUX_MAP 555 bool "Generate vmlinux.map file when linking" 556 depends on EXPERT 557 help 558 Selecting this option will pass "-Map=vmlinux.map" to ld 559 when linking vmlinux. That file can be useful for verifying 560 and debugging magic section games, and for seeing which 561 pieces of code get eliminated with 562 CONFIG_LD_DEAD_CODE_DATA_ELIMINATION. 563 564config DEBUG_FORCE_WEAK_PER_CPU 565 bool "Force weak per-cpu definitions" 566 depends on DEBUG_KERNEL 567 help 568 s390 and alpha require percpu variables in modules to be 569 defined weak to work around addressing range issue which 570 puts the following two restrictions on percpu variable 571 definitions. 572 573 1. percpu symbols must be unique whether static or not 574 2. percpu variables can't be defined inside a function 575 576 To ensure that generic code follows the above rules, this 577 option forces all percpu variables to be defined as weak. 578 579endmenu # "Compiler options" 580 581menu "Generic Kernel Debugging Instruments" 582 583config MAGIC_SYSRQ 584 bool "Magic SysRq key" 585 depends on !UML 586 help 587 If you say Y here, you will have some control over the system even 588 if the system crashes for example during kernel debugging (e.g., you 589 will be able to flush the buffer cache to disk, reboot the system 590 immediately or dump some status information). This is accomplished 591 by pressing various keys while holding SysRq (Alt+PrintScreen). It 592 also works on a serial console (on PC hardware at least), if you 593 send a BREAK and then within 5 seconds a command keypress. The 594 keys are documented in <file:Documentation/admin-guide/sysrq.rst>. 595 Don't say Y unless you really know what this hack does. 596 597config MAGIC_SYSRQ_DEFAULT_ENABLE 598 hex "Enable magic SysRq key functions by default" 599 depends on MAGIC_SYSRQ 600 default 0x1 601 help 602 Specifies which SysRq key functions are enabled by default. 603 This may be set to 1 or 0 to enable or disable them all, or 604 to a bitmask as described in Documentation/admin-guide/sysrq.rst. 605 606config MAGIC_SYSRQ_SERIAL 607 bool "Enable magic SysRq key over serial" 608 depends on MAGIC_SYSRQ 609 default y 610 help 611 Many embedded boards have a disconnected TTL level serial which can 612 generate some garbage that can lead to spurious false sysrq detects. 613 This option allows you to decide whether you want to enable the 614 magic SysRq key. 615 616config MAGIC_SYSRQ_SERIAL_SEQUENCE 617 string "Char sequence that enables magic SysRq over serial" 618 depends on MAGIC_SYSRQ_SERIAL 619 default "" 620 help 621 Specifies a sequence of characters that can follow BREAK to enable 622 SysRq on a serial console. 623 624 If unsure, leave an empty string and the option will not be enabled. 625 626config DEBUG_FS 627 bool "Debug Filesystem" 628 help 629 debugfs is a virtual file system that kernel developers use to put 630 debugging files into. Enable this option to be able to read and 631 write to these files. 632 633 For detailed documentation on the debugfs API, see 634 Documentation/filesystems/. 635 636 If unsure, say N. 637 638choice 639 prompt "Debugfs default access" 640 depends on DEBUG_FS 641 default DEBUG_FS_ALLOW_ALL 642 help 643 This selects the default access restrictions for debugfs. 644 It can be overridden with kernel command line option 645 debugfs=[on,no-mount,off]. The restrictions apply for API access 646 and filesystem registration. 647 648config DEBUG_FS_ALLOW_ALL 649 bool "Access normal" 650 help 651 No restrictions apply. Both API and filesystem registration 652 is on. This is the normal default operation. 653 654config DEBUG_FS_DISALLOW_MOUNT 655 bool "Do not register debugfs as filesystem" 656 help 657 The API is open but filesystem is not loaded. Clients can still do 658 their work and read with debug tools that do not need 659 debugfs filesystem. 660 661config DEBUG_FS_ALLOW_NONE 662 bool "No access" 663 help 664 Access is off. Clients get -PERM when trying to create nodes in 665 debugfs tree and debugfs is not registered as a filesystem. 666 Client can then back-off or continue without debugfs access. 667 668endchoice 669 670source "lib/Kconfig.kgdb" 671source "lib/Kconfig.ubsan" 672source "lib/Kconfig.kcsan" 673 674endmenu 675 676menu "Networking Debugging" 677 678source "net/Kconfig.debug" 679 680endmenu # "Networking Debugging" 681 682menu "Memory Debugging" 683 684source "mm/Kconfig.debug" 685 686config DEBUG_OBJECTS 687 bool "Debug object operations" 688 depends on DEBUG_KERNEL 689 help 690 If you say Y here, additional code will be inserted into the 691 kernel to track the life time of various objects and validate 692 the operations on those objects. 693 694config DEBUG_OBJECTS_SELFTEST 695 bool "Debug objects selftest" 696 depends on DEBUG_OBJECTS 697 help 698 This enables the selftest of the object debug code. 699 700config DEBUG_OBJECTS_FREE 701 bool "Debug objects in freed memory" 702 depends on DEBUG_OBJECTS 703 help 704 This enables checks whether a k/v free operation frees an area 705 which contains an object which has not been deactivated 706 properly. This can make kmalloc/kfree-intensive workloads 707 much slower. 708 709config DEBUG_OBJECTS_TIMERS 710 bool "Debug timer objects" 711 depends on DEBUG_OBJECTS 712 help 713 If you say Y here, additional code will be inserted into the 714 timer routines to track the life time of timer objects and 715 validate the timer operations. 716 717config DEBUG_OBJECTS_WORK 718 bool "Debug work objects" 719 depends on DEBUG_OBJECTS 720 help 721 If you say Y here, additional code will be inserted into the 722 work queue routines to track the life time of work objects and 723 validate the work operations. 724 725config DEBUG_OBJECTS_RCU_HEAD 726 bool "Debug RCU callbacks objects" 727 depends on DEBUG_OBJECTS 728 help 729 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 730 731config DEBUG_OBJECTS_PERCPU_COUNTER 732 bool "Debug percpu counter objects" 733 depends on DEBUG_OBJECTS 734 help 735 If you say Y here, additional code will be inserted into the 736 percpu counter routines to track the life time of percpu counter 737 objects and validate the percpu counter operations. 738 739config DEBUG_OBJECTS_ENABLE_DEFAULT 740 int "debug_objects bootup default value (0-1)" 741 range 0 1 742 default "1" 743 depends on DEBUG_OBJECTS 744 help 745 Debug objects boot parameter default value 746 747config SHRINKER_DEBUG 748 bool "Enable shrinker debugging support" 749 depends on DEBUG_FS 750 help 751 Say Y to enable the shrinker debugfs interface which provides 752 visibility into the kernel memory shrinkers subsystem. 753 Disable it to avoid an extra memory footprint. 754 755config DEBUG_STACK_USAGE 756 bool "Stack utilization instrumentation" 757 depends on DEBUG_KERNEL && !IA64 758 help 759 Enables the display of the minimum amount of free stack which each 760 task has ever had available in the sysrq-T and sysrq-P debug output. 761 762 This option will slow down process creation somewhat. 763 764config SCHED_STACK_END_CHECK 765 bool "Detect stack corruption on calls to schedule()" 766 depends on DEBUG_KERNEL 767 default n 768 help 769 This option checks for a stack overrun on calls to schedule(). 770 If the stack end location is found to be over written always panic as 771 the content of the corrupted region can no longer be trusted. 772 This is to ensure no erroneous behaviour occurs which could result in 773 data corruption or a sporadic crash at a later stage once the region 774 is examined. The runtime overhead introduced is minimal. 775 776config ARCH_HAS_DEBUG_VM_PGTABLE 777 bool 778 help 779 An architecture should select this when it can successfully 780 build and run DEBUG_VM_PGTABLE. 781 782config DEBUG_VM_IRQSOFF 783 def_bool DEBUG_VM && !PREEMPT_RT 784 785config DEBUG_VM 786 bool "Debug VM" 787 depends on DEBUG_KERNEL 788 help 789 Enable this to turn on extended checks in the virtual-memory system 790 that may impact performance. 791 792 If unsure, say N. 793 794config DEBUG_VM_SHOOT_LAZIES 795 bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation" 796 depends on DEBUG_VM 797 depends on MMU_LAZY_TLB_SHOOTDOWN 798 help 799 Enable additional IPIs that ensure lazy tlb mm references are removed 800 before the mm is freed. 801 802 If unsure, say N. 803 804config DEBUG_VM_MAPLE_TREE 805 bool "Debug VM maple trees" 806 depends on DEBUG_VM 807 select DEBUG_MAPLE_TREE 808 help 809 Enable VM maple tree debugging information and extra validations. 810 811 If unsure, say N. 812 813config DEBUG_VM_RB 814 bool "Debug VM red-black trees" 815 depends on DEBUG_VM 816 help 817 Enable VM red-black tree debugging information and extra validations. 818 819 If unsure, say N. 820 821config DEBUG_VM_PGFLAGS 822 bool "Debug page-flags operations" 823 depends on DEBUG_VM 824 help 825 Enables extra validation on page flags operations. 826 827 If unsure, say N. 828 829config DEBUG_VM_PGTABLE 830 bool "Debug arch page table for semantics compliance" 831 depends on MMU 832 depends on ARCH_HAS_DEBUG_VM_PGTABLE 833 default y if DEBUG_VM 834 help 835 This option provides a debug method which can be used to test 836 architecture page table helper functions on various platforms in 837 verifying if they comply with expected generic MM semantics. This 838 will help architecture code in making sure that any changes or 839 new additions of these helpers still conform to expected 840 semantics of the generic MM. Platforms will have to opt in for 841 this through ARCH_HAS_DEBUG_VM_PGTABLE. 842 843 If unsure, say N. 844 845config ARCH_HAS_DEBUG_VIRTUAL 846 bool 847 848config DEBUG_VIRTUAL 849 bool "Debug VM translations" 850 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL 851 help 852 Enable some costly sanity checks in virtual to page code. This can 853 catch mistakes with virt_to_page() and friends. 854 855 If unsure, say N. 856 857config DEBUG_NOMMU_REGIONS 858 bool "Debug the global anon/private NOMMU mapping region tree" 859 depends on DEBUG_KERNEL && !MMU 860 help 861 This option causes the global tree of anonymous and private mapping 862 regions to be regularly checked for invalid topology. 863 864config DEBUG_MEMORY_INIT 865 bool "Debug memory initialisation" if EXPERT 866 default !EXPERT 867 help 868 Enable this for additional checks during memory initialisation. 869 The sanity checks verify aspects of the VM such as the memory model 870 and other information provided by the architecture. Verbose 871 information will be printed at KERN_DEBUG loglevel depending 872 on the mminit_loglevel= command-line option. 873 874 If unsure, say Y 875 876config MEMORY_NOTIFIER_ERROR_INJECT 877 tristate "Memory hotplug notifier error injection module" 878 depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION 879 help 880 This option provides the ability to inject artificial errors to 881 memory hotplug notifier chain callbacks. It is controlled through 882 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 883 884 If the notifier call chain should be failed with some events 885 notified, write the error code to "actions/<notifier event>/error". 886 887 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 888 889 # cd /sys/kernel/debug/notifier-error-inject/memory 890 # echo -12 > actions/MEM_GOING_OFFLINE/error 891 # echo offline > /sys/devices/system/memory/memoryXXX/state 892 bash: echo: write error: Cannot allocate memory 893 894 To compile this code as a module, choose M here: the module will 895 be called memory-notifier-error-inject. 896 897 If unsure, say N. 898 899config DEBUG_PER_CPU_MAPS 900 bool "Debug access to per_cpu maps" 901 depends on DEBUG_KERNEL 902 depends on SMP 903 help 904 Say Y to verify that the per_cpu map being accessed has 905 been set up. This adds a fair amount of code to kernel memory 906 and decreases performance. 907 908 Say N if unsure. 909 910config DEBUG_KMAP_LOCAL 911 bool "Debug kmap_local temporary mappings" 912 depends on DEBUG_KERNEL && KMAP_LOCAL 913 help 914 This option enables additional error checking for the kmap_local 915 infrastructure. Disable for production use. 916 917config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 918 bool 919 920config DEBUG_KMAP_LOCAL_FORCE_MAP 921 bool "Enforce kmap_local temporary mappings" 922 depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 923 select KMAP_LOCAL 924 select DEBUG_KMAP_LOCAL 925 help 926 This option enforces temporary mappings through the kmap_local 927 mechanism for non-highmem pages and on non-highmem systems. 928 Disable this for production systems! 929 930config DEBUG_HIGHMEM 931 bool "Highmem debugging" 932 depends on DEBUG_KERNEL && HIGHMEM 933 select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 934 select DEBUG_KMAP_LOCAL 935 help 936 This option enables additional error checking for high memory 937 systems. Disable for production systems. 938 939config HAVE_DEBUG_STACKOVERFLOW 940 bool 941 942config DEBUG_STACKOVERFLOW 943 bool "Check for stack overflows" 944 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 945 help 946 Say Y here if you want to check for overflows of kernel, IRQ 947 and exception stacks (if your architecture uses them). This 948 option will show detailed messages if free stack space drops 949 below a certain limit. 950 951 These kinds of bugs usually occur when call-chains in the 952 kernel get too deep, especially when interrupts are 953 involved. 954 955 Use this in cases where you see apparently random memory 956 corruption, especially if it appears in 'struct thread_info' 957 958 If in doubt, say "N". 959 960source "lib/Kconfig.kasan" 961source "lib/Kconfig.kfence" 962source "lib/Kconfig.kmsan" 963 964endmenu # "Memory Debugging" 965 966config DEBUG_SHIRQ 967 bool "Debug shared IRQ handlers" 968 depends on DEBUG_KERNEL 969 help 970 Enable this to generate a spurious interrupt just before a shared 971 interrupt handler is deregistered (generating one when registering 972 is currently disabled). Drivers need to handle this correctly. Some 973 don't and need to be caught. 974 975menu "Debug Oops, Lockups and Hangs" 976 977config PANIC_ON_OOPS 978 bool "Panic on Oops" 979 help 980 Say Y here to enable the kernel to panic when it oopses. This 981 has the same effect as setting oops=panic on the kernel command 982 line. 983 984 This feature is useful to ensure that the kernel does not do 985 anything erroneous after an oops which could result in data 986 corruption or other issues. 987 988 Say N if unsure. 989 990config PANIC_ON_OOPS_VALUE 991 int 992 range 0 1 993 default 0 if !PANIC_ON_OOPS 994 default 1 if PANIC_ON_OOPS 995 996config PANIC_TIMEOUT 997 int "panic timeout" 998 default 0 999 help 1000 Set the timeout value (in seconds) until a reboot occurs when 1001 the kernel panics. If n = 0, then we wait forever. A timeout 1002 value n > 0 will wait n seconds before rebooting, while a timeout 1003 value n < 0 will reboot immediately. 1004 1005config LOCKUP_DETECTOR 1006 bool 1007 1008config SOFTLOCKUP_DETECTOR 1009 bool "Detect Soft Lockups" 1010 depends on DEBUG_KERNEL && !S390 1011 select LOCKUP_DETECTOR 1012 help 1013 Say Y here to enable the kernel to act as a watchdog to detect 1014 soft lockups. 1015 1016 Softlockups are bugs that cause the kernel to loop in kernel 1017 mode for more than 20 seconds, without giving other tasks a 1018 chance to run. The current stack trace is displayed upon 1019 detection and the system will stay locked up. 1020 1021config BOOTPARAM_SOFTLOCKUP_PANIC 1022 bool "Panic (Reboot) On Soft Lockups" 1023 depends on SOFTLOCKUP_DETECTOR 1024 help 1025 Say Y here to enable the kernel to panic on "soft lockups", 1026 which are bugs that cause the kernel to loop in kernel 1027 mode for more than 20 seconds (configurable using the watchdog_thresh 1028 sysctl), without giving other tasks a chance to run. 1029 1030 The panic can be used in combination with panic_timeout, 1031 to cause the system to reboot automatically after a 1032 lockup has been detected. This feature is useful for 1033 high-availability systems that have uptime guarantees and 1034 where a lockup must be resolved ASAP. 1035 1036 Say N if unsure. 1037 1038config HARDLOCKUP_DETECTOR_PERF 1039 bool 1040 select SOFTLOCKUP_DETECTOR 1041 1042# 1043# Enables a timestamp based low pass filter to compensate for perf based 1044# hard lockup detection which runs too fast due to turbo modes. 1045# 1046config HARDLOCKUP_CHECK_TIMESTAMP 1047 bool 1048 1049# 1050# arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard 1051# lockup detector rather than the perf based detector. 1052# 1053config HARDLOCKUP_DETECTOR 1054 bool "Detect Hard Lockups" 1055 depends on DEBUG_KERNEL && !S390 1056 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH 1057 select LOCKUP_DETECTOR 1058 select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF 1059 help 1060 Say Y here to enable the kernel to act as a watchdog to detect 1061 hard lockups. 1062 1063 Hardlockups are bugs that cause the CPU to loop in kernel mode 1064 for more than 10 seconds, without letting other interrupts have a 1065 chance to run. The current stack trace is displayed upon detection 1066 and the system will stay locked up. 1067 1068config BOOTPARAM_HARDLOCKUP_PANIC 1069 bool "Panic (Reboot) On Hard Lockups" 1070 depends on HARDLOCKUP_DETECTOR 1071 help 1072 Say Y here to enable the kernel to panic on "hard lockups", 1073 which are bugs that cause the kernel to loop in kernel 1074 mode with interrupts disabled for more than 10 seconds (configurable 1075 using the watchdog_thresh sysctl). 1076 1077 Say N if unsure. 1078 1079config DETECT_HUNG_TASK 1080 bool "Detect Hung Tasks" 1081 depends on DEBUG_KERNEL 1082 default SOFTLOCKUP_DETECTOR 1083 help 1084 Say Y here to enable the kernel to detect "hung tasks", 1085 which are bugs that cause the task to be stuck in 1086 uninterruptible "D" state indefinitely. 1087 1088 When a hung task is detected, the kernel will print the 1089 current stack trace (which you should report), but the 1090 task will stay in uninterruptible state. If lockdep is 1091 enabled then all held locks will also be reported. This 1092 feature has negligible overhead. 1093 1094config DEFAULT_HUNG_TASK_TIMEOUT 1095 int "Default timeout for hung task detection (in seconds)" 1096 depends on DETECT_HUNG_TASK 1097 default 120 1098 help 1099 This option controls the default timeout (in seconds) used 1100 to determine when a task has become non-responsive and should 1101 be considered hung. 1102 1103 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 1104 sysctl or by writing a value to 1105 /proc/sys/kernel/hung_task_timeout_secs. 1106 1107 A timeout of 0 disables the check. The default is two minutes. 1108 Keeping the default should be fine in most cases. 1109 1110config BOOTPARAM_HUNG_TASK_PANIC 1111 bool "Panic (Reboot) On Hung Tasks" 1112 depends on DETECT_HUNG_TASK 1113 help 1114 Say Y here to enable the kernel to panic on "hung tasks", 1115 which are bugs that cause the kernel to leave a task stuck 1116 in uninterruptible "D" state. 1117 1118 The panic can be used in combination with panic_timeout, 1119 to cause the system to reboot automatically after a 1120 hung task has been detected. This feature is useful for 1121 high-availability systems that have uptime guarantees and 1122 where a hung tasks must be resolved ASAP. 1123 1124 Say N if unsure. 1125 1126config WQ_WATCHDOG 1127 bool "Detect Workqueue Stalls" 1128 depends on DEBUG_KERNEL 1129 help 1130 Say Y here to enable stall detection on workqueues. If a 1131 worker pool doesn't make forward progress on a pending work 1132 item for over a given amount of time, 30s by default, a 1133 warning message is printed along with dump of workqueue 1134 state. This can be configured through kernel parameter 1135 "workqueue.watchdog_thresh" and its sysfs counterpart. 1136 1137config TEST_LOCKUP 1138 tristate "Test module to generate lockups" 1139 depends on m 1140 help 1141 This builds the "test_lockup" module that helps to make sure 1142 that watchdogs and lockup detectors are working properly. 1143 1144 Depending on module parameters it could emulate soft or hard 1145 lockup, "hung task", or locking arbitrary lock for a long time. 1146 Also it could generate series of lockups with cooling-down periods. 1147 1148 If unsure, say N. 1149 1150endmenu # "Debug lockups and hangs" 1151 1152menu "Scheduler Debugging" 1153 1154config SCHED_DEBUG 1155 bool "Collect scheduler debugging info" 1156 depends on DEBUG_KERNEL && DEBUG_FS 1157 default y 1158 help 1159 If you say Y here, the /sys/kernel/debug/sched file will be provided 1160 that can help debug the scheduler. The runtime overhead of this 1161 option is minimal. 1162 1163config SCHED_INFO 1164 bool 1165 default n 1166 1167config SCHEDSTATS 1168 bool "Collect scheduler statistics" 1169 depends on DEBUG_KERNEL && PROC_FS 1170 select SCHED_INFO 1171 help 1172 If you say Y here, additional code will be inserted into the 1173 scheduler and related routines to collect statistics about 1174 scheduler behavior and provide them in /proc/schedstat. These 1175 stats may be useful for both tuning and debugging the scheduler 1176 If you aren't debugging the scheduler or trying to tune a specific 1177 application, you can say N to avoid the very slight overhead 1178 this adds. 1179 1180endmenu 1181 1182config DEBUG_TIMEKEEPING 1183 bool "Enable extra timekeeping sanity checking" 1184 help 1185 This option will enable additional timekeeping sanity checks 1186 which may be helpful when diagnosing issues where timekeeping 1187 problems are suspected. 1188 1189 This may include checks in the timekeeping hotpaths, so this 1190 option may have a (very small) performance impact to some 1191 workloads. 1192 1193 If unsure, say N. 1194 1195config DEBUG_PREEMPT 1196 bool "Debug preemptible kernel" 1197 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1198 help 1199 If you say Y here then the kernel will use a debug variant of the 1200 commonly used smp_processor_id() function and will print warnings 1201 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1202 will detect preemption count underflows. 1203 1204 This option has potential to introduce high runtime overhead, 1205 depending on workload as it triggers debugging routines for each 1206 this_cpu operation. It should only be used for debugging purposes. 1207 1208menu "Lock Debugging (spinlocks, mutexes, etc...)" 1209 1210config LOCK_DEBUGGING_SUPPORT 1211 bool 1212 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1213 default y 1214 1215config PROVE_LOCKING 1216 bool "Lock debugging: prove locking correctness" 1217 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1218 select LOCKDEP 1219 select DEBUG_SPINLOCK 1220 select DEBUG_MUTEXES if !PREEMPT_RT 1221 select DEBUG_RT_MUTEXES if RT_MUTEXES 1222 select DEBUG_RWSEMS 1223 select DEBUG_WW_MUTEX_SLOWPATH 1224 select DEBUG_LOCK_ALLOC 1225 select PREEMPT_COUNT if !ARCH_NO_PREEMPT 1226 select TRACE_IRQFLAGS 1227 default n 1228 help 1229 This feature enables the kernel to prove that all locking 1230 that occurs in the kernel runtime is mathematically 1231 correct: that under no circumstance could an arbitrary (and 1232 not yet triggered) combination of observed locking 1233 sequences (on an arbitrary number of CPUs, running an 1234 arbitrary number of tasks and interrupt contexts) cause a 1235 deadlock. 1236 1237 In short, this feature enables the kernel to report locking 1238 related deadlocks before they actually occur. 1239 1240 The proof does not depend on how hard and complex a 1241 deadlock scenario would be to trigger: how many 1242 participant CPUs, tasks and irq-contexts would be needed 1243 for it to trigger. The proof also does not depend on 1244 timing: if a race and a resulting deadlock is possible 1245 theoretically (no matter how unlikely the race scenario 1246 is), it will be proven so and will immediately be 1247 reported by the kernel (once the event is observed that 1248 makes the deadlock theoretically possible). 1249 1250 If a deadlock is impossible (i.e. the locking rules, as 1251 observed by the kernel, are mathematically correct), the 1252 kernel reports nothing. 1253 1254 NOTE: this feature can also be enabled for rwlocks, mutexes 1255 and rwsems - in which case all dependencies between these 1256 different locking variants are observed and mapped too, and 1257 the proof of observed correctness is also maintained for an 1258 arbitrary combination of these separate locking variants. 1259 1260 For more details, see Documentation/locking/lockdep-design.rst. 1261 1262config PROVE_RAW_LOCK_NESTING 1263 bool "Enable raw_spinlock - spinlock nesting checks" 1264 depends on PROVE_LOCKING 1265 default n 1266 help 1267 Enable the raw_spinlock vs. spinlock nesting checks which ensure 1268 that the lock nesting rules for PREEMPT_RT enabled kernels are 1269 not violated. 1270 1271 NOTE: There are known nesting problems. So if you enable this 1272 option expect lockdep splats until these problems have been fully 1273 addressed which is work in progress. This config switch allows to 1274 identify and analyze these problems. It will be removed and the 1275 check permanently enabled once the main issues have been fixed. 1276 1277 If unsure, select N. 1278 1279config LOCK_STAT 1280 bool "Lock usage statistics" 1281 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1282 select LOCKDEP 1283 select DEBUG_SPINLOCK 1284 select DEBUG_MUTEXES if !PREEMPT_RT 1285 select DEBUG_RT_MUTEXES if RT_MUTEXES 1286 select DEBUG_LOCK_ALLOC 1287 default n 1288 help 1289 This feature enables tracking lock contention points 1290 1291 For more details, see Documentation/locking/lockstat.rst 1292 1293 This also enables lock events required by "perf lock", 1294 subcommand of perf. 1295 If you want to use "perf lock", you also need to turn on 1296 CONFIG_EVENT_TRACING. 1297 1298 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1299 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1300 1301config DEBUG_RT_MUTEXES 1302 bool "RT Mutex debugging, deadlock detection" 1303 depends on DEBUG_KERNEL && RT_MUTEXES 1304 help 1305 This allows rt mutex semantics violations and rt mutex related 1306 deadlocks (lockups) to be detected and reported automatically. 1307 1308config DEBUG_SPINLOCK 1309 bool "Spinlock and rw-lock debugging: basic checks" 1310 depends on DEBUG_KERNEL 1311 select UNINLINE_SPIN_UNLOCK 1312 help 1313 Say Y here and build SMP to catch missing spinlock initialization 1314 and certain other kinds of spinlock errors commonly made. This is 1315 best used in conjunction with the NMI watchdog so that spinlock 1316 deadlocks are also debuggable. 1317 1318config DEBUG_MUTEXES 1319 bool "Mutex debugging: basic checks" 1320 depends on DEBUG_KERNEL && !PREEMPT_RT 1321 help 1322 This feature allows mutex semantics violations to be detected and 1323 reported. 1324 1325config DEBUG_WW_MUTEX_SLOWPATH 1326 bool "Wait/wound mutex debugging: Slowpath testing" 1327 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1328 select DEBUG_LOCK_ALLOC 1329 select DEBUG_SPINLOCK 1330 select DEBUG_MUTEXES if !PREEMPT_RT 1331 select DEBUG_RT_MUTEXES if PREEMPT_RT 1332 help 1333 This feature enables slowpath testing for w/w mutex users by 1334 injecting additional -EDEADLK wound/backoff cases. Together with 1335 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1336 will test all possible w/w mutex interface abuse with the 1337 exception of simply not acquiring all the required locks. 1338 Note that this feature can introduce significant overhead, so 1339 it really should not be enabled in a production or distro kernel, 1340 even a debug kernel. If you are a driver writer, enable it. If 1341 you are a distro, do not. 1342 1343config DEBUG_RWSEMS 1344 bool "RW Semaphore debugging: basic checks" 1345 depends on DEBUG_KERNEL 1346 help 1347 This debugging feature allows mismatched rw semaphore locks 1348 and unlocks to be detected and reported. 1349 1350config DEBUG_LOCK_ALLOC 1351 bool "Lock debugging: detect incorrect freeing of live locks" 1352 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1353 select DEBUG_SPINLOCK 1354 select DEBUG_MUTEXES if !PREEMPT_RT 1355 select DEBUG_RT_MUTEXES if RT_MUTEXES 1356 select LOCKDEP 1357 help 1358 This feature will check whether any held lock (spinlock, rwlock, 1359 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1360 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1361 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1362 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1363 held during task exit. 1364 1365config LOCKDEP 1366 bool 1367 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1368 select STACKTRACE 1369 select KALLSYMS 1370 select KALLSYMS_ALL 1371 1372config LOCKDEP_SMALL 1373 bool 1374 1375config LOCKDEP_BITS 1376 int "Bitsize for MAX_LOCKDEP_ENTRIES" 1377 depends on LOCKDEP && !LOCKDEP_SMALL 1378 range 10 30 1379 default 15 1380 help 1381 Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message. 1382 1383config LOCKDEP_CHAINS_BITS 1384 int "Bitsize for MAX_LOCKDEP_CHAINS" 1385 depends on LOCKDEP && !LOCKDEP_SMALL 1386 range 10 30 1387 default 16 1388 help 1389 Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message. 1390 1391config LOCKDEP_STACK_TRACE_BITS 1392 int "Bitsize for MAX_STACK_TRACE_ENTRIES" 1393 depends on LOCKDEP && !LOCKDEP_SMALL 1394 range 10 30 1395 default 19 1396 help 1397 Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message. 1398 1399config LOCKDEP_STACK_TRACE_HASH_BITS 1400 int "Bitsize for STACK_TRACE_HASH_SIZE" 1401 depends on LOCKDEP && !LOCKDEP_SMALL 1402 range 10 30 1403 default 14 1404 help 1405 Try increasing this value if you need large STACK_TRACE_HASH_SIZE. 1406 1407config LOCKDEP_CIRCULAR_QUEUE_BITS 1408 int "Bitsize for elements in circular_queue struct" 1409 depends on LOCKDEP 1410 range 10 30 1411 default 12 1412 help 1413 Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure. 1414 1415config DEBUG_LOCKDEP 1416 bool "Lock dependency engine debugging" 1417 depends on DEBUG_KERNEL && LOCKDEP 1418 select DEBUG_IRQFLAGS 1419 help 1420 If you say Y here, the lock dependency engine will do 1421 additional runtime checks to debug itself, at the price 1422 of more runtime overhead. 1423 1424config DEBUG_ATOMIC_SLEEP 1425 bool "Sleep inside atomic section checking" 1426 select PREEMPT_COUNT 1427 depends on DEBUG_KERNEL 1428 depends on !ARCH_NO_PREEMPT 1429 help 1430 If you say Y here, various routines which may sleep will become very 1431 noisy if they are called inside atomic sections: when a spinlock is 1432 held, inside an rcu read side critical section, inside preempt disabled 1433 sections, inside an interrupt, etc... 1434 1435config DEBUG_LOCKING_API_SELFTESTS 1436 bool "Locking API boot-time self-tests" 1437 depends on DEBUG_KERNEL 1438 help 1439 Say Y here if you want the kernel to run a short self-test during 1440 bootup. The self-test checks whether common types of locking bugs 1441 are detected by debugging mechanisms or not. (if you disable 1442 lock debugging then those bugs won't be detected of course.) 1443 The following locking APIs are covered: spinlocks, rwlocks, 1444 mutexes and rwsems. 1445 1446config LOCK_TORTURE_TEST 1447 tristate "torture tests for locking" 1448 depends on DEBUG_KERNEL 1449 select TORTURE_TEST 1450 help 1451 This option provides a kernel module that runs torture tests 1452 on kernel locking primitives. The kernel module may be built 1453 after the fact on the running kernel to be tested, if desired. 1454 1455 Say Y here if you want kernel locking-primitive torture tests 1456 to be built into the kernel. 1457 Say M if you want these torture tests to build as a module. 1458 Say N if you are unsure. 1459 1460config WW_MUTEX_SELFTEST 1461 tristate "Wait/wound mutex selftests" 1462 help 1463 This option provides a kernel module that runs tests on the 1464 on the struct ww_mutex locking API. 1465 1466 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1467 with this test harness. 1468 1469 Say M if you want these self tests to build as a module. 1470 Say N if you are unsure. 1471 1472config SCF_TORTURE_TEST 1473 tristate "torture tests for smp_call_function*()" 1474 depends on DEBUG_KERNEL 1475 select TORTURE_TEST 1476 help 1477 This option provides a kernel module that runs torture tests 1478 on the smp_call_function() family of primitives. The kernel 1479 module may be built after the fact on the running kernel to 1480 be tested, if desired. 1481 1482config CSD_LOCK_WAIT_DEBUG 1483 bool "Debugging for csd_lock_wait(), called from smp_call_function*()" 1484 depends on DEBUG_KERNEL 1485 depends on 64BIT 1486 default n 1487 help 1488 This option enables debug prints when CPUs are slow to respond 1489 to the smp_call_function*() IPI wrappers. These debug prints 1490 include the IPI handler function currently executing (if any) 1491 and relevant stack traces. 1492 1493endmenu # lock debugging 1494 1495config TRACE_IRQFLAGS 1496 depends on TRACE_IRQFLAGS_SUPPORT 1497 bool 1498 help 1499 Enables hooks to interrupt enabling and disabling for 1500 either tracing or lock debugging. 1501 1502config TRACE_IRQFLAGS_NMI 1503 def_bool y 1504 depends on TRACE_IRQFLAGS 1505 depends on TRACE_IRQFLAGS_NMI_SUPPORT 1506 1507config NMI_CHECK_CPU 1508 bool "Debugging for CPUs failing to respond to backtrace requests" 1509 depends on DEBUG_KERNEL 1510 depends on X86 1511 default n 1512 help 1513 Enables debug prints when a CPU fails to respond to a given 1514 backtrace NMI. These prints provide some reasons why a CPU 1515 might legitimately be failing to respond, for example, if it 1516 is offline of if ignore_nmis is set. 1517 1518config DEBUG_IRQFLAGS 1519 bool "Debug IRQ flag manipulation" 1520 help 1521 Enables checks for potentially unsafe enabling or disabling of 1522 interrupts, such as calling raw_local_irq_restore() when interrupts 1523 are enabled. 1524 1525config STACKTRACE 1526 bool "Stack backtrace support" 1527 depends on STACKTRACE_SUPPORT 1528 help 1529 This option causes the kernel to create a /proc/pid/stack for 1530 every process, showing its current stack trace. 1531 It is also used by various kernel debugging features that require 1532 stack trace generation. 1533 1534config WARN_ALL_UNSEEDED_RANDOM 1535 bool "Warn for all uses of unseeded randomness" 1536 default n 1537 help 1538 Some parts of the kernel contain bugs relating to their use of 1539 cryptographically secure random numbers before it's actually possible 1540 to generate those numbers securely. This setting ensures that these 1541 flaws don't go unnoticed, by enabling a message, should this ever 1542 occur. This will allow people with obscure setups to know when things 1543 are going wrong, so that they might contact developers about fixing 1544 it. 1545 1546 Unfortunately, on some models of some architectures getting 1547 a fully seeded CRNG is extremely difficult, and so this can 1548 result in dmesg getting spammed for a surprisingly long 1549 time. This is really bad from a security perspective, and 1550 so architecture maintainers really need to do what they can 1551 to get the CRNG seeded sooner after the system is booted. 1552 However, since users cannot do anything actionable to 1553 address this, by default this option is disabled. 1554 1555 Say Y here if you want to receive warnings for all uses of 1556 unseeded randomness. This will be of use primarily for 1557 those developers interested in improving the security of 1558 Linux kernels running on their architecture (or 1559 subarchitecture). 1560 1561config DEBUG_KOBJECT 1562 bool "kobject debugging" 1563 depends on DEBUG_KERNEL 1564 help 1565 If you say Y here, some extra kobject debugging messages will be sent 1566 to the syslog. 1567 1568config DEBUG_KOBJECT_RELEASE 1569 bool "kobject release debugging" 1570 depends on DEBUG_OBJECTS_TIMERS 1571 help 1572 kobjects are reference counted objects. This means that their 1573 last reference count put is not predictable, and the kobject can 1574 live on past the point at which a driver decides to drop its 1575 initial reference to the kobject gained on allocation. An 1576 example of this would be a struct device which has just been 1577 unregistered. 1578 1579 However, some buggy drivers assume that after such an operation, 1580 the memory backing the kobject can be immediately freed. This 1581 goes completely against the principles of a refcounted object. 1582 1583 If you say Y here, the kernel will delay the release of kobjects 1584 on the last reference count to improve the visibility of this 1585 kind of kobject release bug. 1586 1587config HAVE_DEBUG_BUGVERBOSE 1588 bool 1589 1590menu "Debug kernel data structures" 1591 1592config DEBUG_LIST 1593 bool "Debug linked list manipulation" 1594 depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION 1595 help 1596 Enable this to turn on extended checks in the linked-list 1597 walking routines. 1598 1599 If unsure, say N. 1600 1601config DEBUG_PLIST 1602 bool "Debug priority linked list manipulation" 1603 depends on DEBUG_KERNEL 1604 help 1605 Enable this to turn on extended checks in the priority-ordered 1606 linked-list (plist) walking routines. This checks the entire 1607 list multiple times during each manipulation. 1608 1609 If unsure, say N. 1610 1611config DEBUG_SG 1612 bool "Debug SG table operations" 1613 depends on DEBUG_KERNEL 1614 help 1615 Enable this to turn on checks on scatter-gather tables. This can 1616 help find problems with drivers that do not properly initialize 1617 their sg tables. 1618 1619 If unsure, say N. 1620 1621config DEBUG_NOTIFIERS 1622 bool "Debug notifier call chains" 1623 depends on DEBUG_KERNEL 1624 help 1625 Enable this to turn on sanity checking for notifier call chains. 1626 This is most useful for kernel developers to make sure that 1627 modules properly unregister themselves from notifier chains. 1628 This is a relatively cheap check but if you care about maximum 1629 performance, say N. 1630 1631config BUG_ON_DATA_CORRUPTION 1632 bool "Trigger a BUG when data corruption is detected" 1633 select DEBUG_LIST 1634 help 1635 Select this option if the kernel should BUG when it encounters 1636 data corruption in kernel memory structures when they get checked 1637 for validity. 1638 1639 If unsure, say N. 1640 1641config DEBUG_MAPLE_TREE 1642 bool "Debug maple trees" 1643 depends on DEBUG_KERNEL 1644 help 1645 Enable maple tree debugging information and extra validations. 1646 1647 If unsure, say N. 1648 1649endmenu 1650 1651config DEBUG_CREDENTIALS 1652 bool "Debug credential management" 1653 depends on DEBUG_KERNEL 1654 help 1655 Enable this to turn on some debug checking for credential 1656 management. The additional code keeps track of the number of 1657 pointers from task_structs to any given cred struct, and checks to 1658 see that this number never exceeds the usage count of the cred 1659 struct. 1660 1661 Furthermore, if SELinux is enabled, this also checks that the 1662 security pointer in the cred struct is never seen to be invalid. 1663 1664 If unsure, say N. 1665 1666source "kernel/rcu/Kconfig.debug" 1667 1668config DEBUG_WQ_FORCE_RR_CPU 1669 bool "Force round-robin CPU selection for unbound work items" 1670 depends on DEBUG_KERNEL 1671 default n 1672 help 1673 Workqueue used to implicitly guarantee that work items queued 1674 without explicit CPU specified are put on the local CPU. This 1675 guarantee is no longer true and while local CPU is still 1676 preferred work items may be put on foreign CPUs. Kernel 1677 parameter "workqueue.debug_force_rr_cpu" is added to force 1678 round-robin CPU selection to flush out usages which depend on the 1679 now broken guarantee. This config option enables the debug 1680 feature by default. When enabled, memory and cache locality will 1681 be impacted. 1682 1683config CPU_HOTPLUG_STATE_CONTROL 1684 bool "Enable CPU hotplug state control" 1685 depends on DEBUG_KERNEL 1686 depends on HOTPLUG_CPU 1687 default n 1688 help 1689 Allows to write steps between "offline" and "online" to the CPUs 1690 sysfs target file so states can be stepped granular. This is a debug 1691 option for now as the hotplug machinery cannot be stopped and 1692 restarted at arbitrary points yet. 1693 1694 Say N if your are unsure. 1695 1696config LATENCYTOP 1697 bool "Latency measuring infrastructure" 1698 depends on DEBUG_KERNEL 1699 depends on STACKTRACE_SUPPORT 1700 depends on PROC_FS 1701 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 1702 select KALLSYMS 1703 select KALLSYMS_ALL 1704 select STACKTRACE 1705 select SCHEDSTATS 1706 help 1707 Enable this option if you want to use the LatencyTOP tool 1708 to find out which userspace is blocking on what kernel operations. 1709 1710config DEBUG_CGROUP_REF 1711 bool "Disable inlining of cgroup css reference count functions" 1712 depends on DEBUG_KERNEL 1713 depends on CGROUPS 1714 depends on KPROBES 1715 default n 1716 help 1717 Force cgroup css reference count functions to not be inlined so 1718 that they can be kprobed for debugging. 1719 1720source "kernel/trace/Kconfig" 1721 1722config PROVIDE_OHCI1394_DMA_INIT 1723 bool "Remote debugging over FireWire early on boot" 1724 depends on PCI && X86 1725 help 1726 If you want to debug problems which hang or crash the kernel early 1727 on boot and the crashing machine has a FireWire port, you can use 1728 this feature to remotely access the memory of the crashed machine 1729 over FireWire. This employs remote DMA as part of the OHCI1394 1730 specification which is now the standard for FireWire controllers. 1731 1732 With remote DMA, you can monitor the printk buffer remotely using 1733 firescope and access all memory below 4GB using fireproxy from gdb. 1734 Even controlling a kernel debugger is possible using remote DMA. 1735 1736 Usage: 1737 1738 If ohci1394_dma=early is used as boot parameter, it will initialize 1739 all OHCI1394 controllers which are found in the PCI config space. 1740 1741 As all changes to the FireWire bus such as enabling and disabling 1742 devices cause a bus reset and thereby disable remote DMA for all 1743 devices, be sure to have the cable plugged and FireWire enabled on 1744 the debugging host before booting the debug target for debugging. 1745 1746 This code (~1k) is freed after boot. By then, the firewire stack 1747 in charge of the OHCI-1394 controllers should be used instead. 1748 1749 See Documentation/core-api/debugging-via-ohci1394.rst for more information. 1750 1751source "samples/Kconfig" 1752 1753config ARCH_HAS_DEVMEM_IS_ALLOWED 1754 bool 1755 1756config STRICT_DEVMEM 1757 bool "Filter access to /dev/mem" 1758 depends on MMU && DEVMEM 1759 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED 1760 default y if PPC || X86 || ARM64 1761 help 1762 If this option is disabled, you allow userspace (root) access to all 1763 of memory, including kernel and userspace memory. Accidental 1764 access to this is obviously disastrous, but specific access can 1765 be used by people debugging the kernel. Note that with PAT support 1766 enabled, even in this case there are restrictions on /dev/mem 1767 use due to the cache aliasing requirements. 1768 1769 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 1770 file only allows userspace access to PCI space and the BIOS code and 1771 data regions. This is sufficient for dosemu and X and all common 1772 users of /dev/mem. 1773 1774 If in doubt, say Y. 1775 1776config IO_STRICT_DEVMEM 1777 bool "Filter I/O access to /dev/mem" 1778 depends on STRICT_DEVMEM 1779 help 1780 If this option is disabled, you allow userspace (root) access to all 1781 io-memory regardless of whether a driver is actively using that 1782 range. Accidental access to this is obviously disastrous, but 1783 specific access can be used by people debugging kernel drivers. 1784 1785 If this option is switched on, the /dev/mem file only allows 1786 userspace access to *idle* io-memory ranges (see /proc/iomem) This 1787 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 1788 if the driver using a given range cannot be disabled. 1789 1790 If in doubt, say Y. 1791 1792menu "$(SRCARCH) Debugging" 1793 1794source "arch/$(SRCARCH)/Kconfig.debug" 1795 1796endmenu 1797 1798menu "Kernel Testing and Coverage" 1799 1800source "lib/kunit/Kconfig" 1801 1802config NOTIFIER_ERROR_INJECTION 1803 tristate "Notifier error injection" 1804 depends on DEBUG_KERNEL 1805 select DEBUG_FS 1806 help 1807 This option provides the ability to inject artificial errors to 1808 specified notifier chain callbacks. It is useful to test the error 1809 handling of notifier call chain failures. 1810 1811 Say N if unsure. 1812 1813config PM_NOTIFIER_ERROR_INJECT 1814 tristate "PM notifier error injection module" 1815 depends on PM && NOTIFIER_ERROR_INJECTION 1816 default m if PM_DEBUG 1817 help 1818 This option provides the ability to inject artificial errors to 1819 PM notifier chain callbacks. It is controlled through debugfs 1820 interface /sys/kernel/debug/notifier-error-inject/pm 1821 1822 If the notifier call chain should be failed with some events 1823 notified, write the error code to "actions/<notifier event>/error". 1824 1825 Example: Inject PM suspend error (-12 = -ENOMEM) 1826 1827 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1828 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1829 # echo mem > /sys/power/state 1830 bash: echo: write error: Cannot allocate memory 1831 1832 To compile this code as a module, choose M here: the module will 1833 be called pm-notifier-error-inject. 1834 1835 If unsure, say N. 1836 1837config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1838 tristate "OF reconfig notifier error injection module" 1839 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1840 help 1841 This option provides the ability to inject artificial errors to 1842 OF reconfig notifier chain callbacks. It is controlled 1843 through debugfs interface under 1844 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1845 1846 If the notifier call chain should be failed with some events 1847 notified, write the error code to "actions/<notifier event>/error". 1848 1849 To compile this code as a module, choose M here: the module will 1850 be called of-reconfig-notifier-error-inject. 1851 1852 If unsure, say N. 1853 1854config NETDEV_NOTIFIER_ERROR_INJECT 1855 tristate "Netdev notifier error injection module" 1856 depends on NET && NOTIFIER_ERROR_INJECTION 1857 help 1858 This option provides the ability to inject artificial errors to 1859 netdevice notifier chain callbacks. It is controlled through debugfs 1860 interface /sys/kernel/debug/notifier-error-inject/netdev 1861 1862 If the notifier call chain should be failed with some events 1863 notified, write the error code to "actions/<notifier event>/error". 1864 1865 Example: Inject netdevice mtu change error (-22 = -EINVAL) 1866 1867 # cd /sys/kernel/debug/notifier-error-inject/netdev 1868 # echo -22 > actions/NETDEV_CHANGEMTU/error 1869 # ip link set eth0 mtu 1024 1870 RTNETLINK answers: Invalid argument 1871 1872 To compile this code as a module, choose M here: the module will 1873 be called netdev-notifier-error-inject. 1874 1875 If unsure, say N. 1876 1877config FUNCTION_ERROR_INJECTION 1878 bool "Fault-injections of functions" 1879 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 1880 help 1881 Add fault injections into various functions that are annotated with 1882 ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return 1883 value of these functions. This is useful to test error paths of code. 1884 1885 If unsure, say N 1886 1887config FAULT_INJECTION 1888 bool "Fault-injection framework" 1889 depends on DEBUG_KERNEL 1890 help 1891 Provide fault-injection framework. 1892 For more details, see Documentation/fault-injection/. 1893 1894config FAILSLAB 1895 bool "Fault-injection capability for kmalloc" 1896 depends on FAULT_INJECTION 1897 depends on SLAB || SLUB 1898 help 1899 Provide fault-injection capability for kmalloc. 1900 1901config FAIL_PAGE_ALLOC 1902 bool "Fault-injection capability for alloc_pages()" 1903 depends on FAULT_INJECTION 1904 help 1905 Provide fault-injection capability for alloc_pages(). 1906 1907config FAULT_INJECTION_USERCOPY 1908 bool "Fault injection capability for usercopy functions" 1909 depends on FAULT_INJECTION 1910 help 1911 Provides fault-injection capability to inject failures 1912 in usercopy functions (copy_from_user(), get_user(), ...). 1913 1914config FAIL_MAKE_REQUEST 1915 bool "Fault-injection capability for disk IO" 1916 depends on FAULT_INJECTION && BLOCK 1917 help 1918 Provide fault-injection capability for disk IO. 1919 1920config FAIL_IO_TIMEOUT 1921 bool "Fault-injection capability for faking disk interrupts" 1922 depends on FAULT_INJECTION && BLOCK 1923 help 1924 Provide fault-injection capability on end IO handling. This 1925 will make the block layer "forget" an interrupt as configured, 1926 thus exercising the error handling. 1927 1928 Only works with drivers that use the generic timeout handling, 1929 for others it won't do anything. 1930 1931config FAIL_FUTEX 1932 bool "Fault-injection capability for futexes" 1933 select DEBUG_FS 1934 depends on FAULT_INJECTION && FUTEX 1935 help 1936 Provide fault-injection capability for futexes. 1937 1938config FAULT_INJECTION_DEBUG_FS 1939 bool "Debugfs entries for fault-injection capabilities" 1940 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 1941 help 1942 Enable configuration of fault-injection capabilities via debugfs. 1943 1944config FAIL_FUNCTION 1945 bool "Fault-injection capability for functions" 1946 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 1947 help 1948 Provide function-based fault-injection capability. 1949 This will allow you to override a specific function with a return 1950 with given return value. As a result, function caller will see 1951 an error value and have to handle it. This is useful to test the 1952 error handling in various subsystems. 1953 1954config FAIL_MMC_REQUEST 1955 bool "Fault-injection capability for MMC IO" 1956 depends on FAULT_INJECTION_DEBUG_FS && MMC 1957 help 1958 Provide fault-injection capability for MMC IO. 1959 This will make the mmc core return data errors. This is 1960 useful to test the error handling in the mmc block device 1961 and to test how the mmc host driver handles retries from 1962 the block device. 1963 1964config FAIL_SUNRPC 1965 bool "Fault-injection capability for SunRPC" 1966 depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG 1967 help 1968 Provide fault-injection capability for SunRPC and 1969 its consumers. 1970 1971config FAULT_INJECTION_STACKTRACE_FILTER 1972 bool "stacktrace filter for fault-injection capabilities" 1973 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 1974 select STACKTRACE 1975 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 1976 help 1977 Provide stacktrace filter for fault-injection capabilities 1978 1979config ARCH_HAS_KCOV 1980 bool 1981 help 1982 An architecture should select this when it can successfully 1983 build and run with CONFIG_KCOV. This typically requires 1984 disabling instrumentation for some early boot code. 1985 1986config CC_HAS_SANCOV_TRACE_PC 1987 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 1988 1989 1990config KCOV 1991 bool "Code coverage for fuzzing" 1992 depends on ARCH_HAS_KCOV 1993 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 1994 depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \ 1995 GCC_VERSION >= 120000 || CLANG_VERSION >= 130000 1996 select DEBUG_FS 1997 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 1998 select OBJTOOL if HAVE_NOINSTR_HACK 1999 help 2000 KCOV exposes kernel code coverage information in a form suitable 2001 for coverage-guided fuzzing (randomized testing). 2002 2003 If RANDOMIZE_BASE is enabled, PC values will not be stable across 2004 different machines and across reboots. If you need stable PC values, 2005 disable RANDOMIZE_BASE. 2006 2007 For more details, see Documentation/dev-tools/kcov.rst. 2008 2009config KCOV_ENABLE_COMPARISONS 2010 bool "Enable comparison operands collection by KCOV" 2011 depends on KCOV 2012 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 2013 help 2014 KCOV also exposes operands of every comparison in the instrumented 2015 code along with operand sizes and PCs of the comparison instructions. 2016 These operands can be used by fuzzing engines to improve the quality 2017 of fuzzing coverage. 2018 2019config KCOV_INSTRUMENT_ALL 2020 bool "Instrument all code by default" 2021 depends on KCOV 2022 default y 2023 help 2024 If you are doing generic system call fuzzing (like e.g. syzkaller), 2025 then you will want to instrument the whole kernel and you should 2026 say y here. If you are doing more targeted fuzzing (like e.g. 2027 filesystem fuzzing with AFL) then you will want to enable coverage 2028 for more specific subsets of files, and should say n here. 2029 2030config KCOV_IRQ_AREA_SIZE 2031 hex "Size of interrupt coverage collection area in words" 2032 depends on KCOV 2033 default 0x40000 2034 help 2035 KCOV uses preallocated per-cpu areas to collect coverage from 2036 soft interrupts. This specifies the size of those areas in the 2037 number of unsigned long words. 2038 2039menuconfig RUNTIME_TESTING_MENU 2040 bool "Runtime Testing" 2041 def_bool y 2042 2043if RUNTIME_TESTING_MENU 2044 2045config TEST_DHRY 2046 tristate "Dhrystone benchmark test" 2047 help 2048 Enable this to include the Dhrystone 2.1 benchmark. This test 2049 calculates the number of Dhrystones per second, and the number of 2050 DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided 2051 by 1757 (the number of Dhrystones per second obtained on the VAX 2052 11/780, nominally a 1 MIPS machine). 2053 2054 To run the benchmark, it needs to be enabled explicitly, either from 2055 the kernel command line (when built-in), or from userspace (when 2056 built-in or modular. 2057 2058 Run once during kernel boot: 2059 2060 test_dhry.run 2061 2062 Set number of iterations from kernel command line: 2063 2064 test_dhry.iterations=<n> 2065 2066 Set number of iterations from userspace: 2067 2068 echo <n> > /sys/module/test_dhry/parameters/iterations 2069 2070 Trigger manual run from userspace: 2071 2072 echo y > /sys/module/test_dhry/parameters/run 2073 2074 If the number of iterations is <= 0, the test will devise a suitable 2075 number of iterations (test runs for at least 2s) automatically. 2076 This process takes ca. 4s. 2077 2078 If unsure, say N. 2079 2080config LKDTM 2081 tristate "Linux Kernel Dump Test Tool Module" 2082 depends on DEBUG_FS 2083 help 2084 This module enables testing of the different dumping mechanisms by 2085 inducing system failures at predefined crash points. 2086 If you don't need it: say N 2087 Choose M here to compile this code as a module. The module will be 2088 called lkdtm. 2089 2090 Documentation on how to use the module can be found in 2091 Documentation/fault-injection/provoke-crashes.rst 2092 2093config CPUMASK_KUNIT_TEST 2094 tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS 2095 depends on KUNIT 2096 default KUNIT_ALL_TESTS 2097 help 2098 Enable to turn on cpumask tests, running at boot or module load time. 2099 2100 For more information on KUnit and unit tests in general, please refer 2101 to the KUnit documentation in Documentation/dev-tools/kunit/. 2102 2103 If unsure, say N. 2104 2105config TEST_LIST_SORT 2106 tristate "Linked list sorting test" if !KUNIT_ALL_TESTS 2107 depends on KUNIT 2108 default KUNIT_ALL_TESTS 2109 help 2110 Enable this to turn on 'list_sort()' function test. This test is 2111 executed only once during system boot (so affects only boot time), 2112 or at module load time. 2113 2114 If unsure, say N. 2115 2116config TEST_MIN_HEAP 2117 tristate "Min heap test" 2118 depends on DEBUG_KERNEL || m 2119 help 2120 Enable this to turn on min heap function tests. This test is 2121 executed only once during system boot (so affects only boot time), 2122 or at module load time. 2123 2124 If unsure, say N. 2125 2126config TEST_SORT 2127 tristate "Array-based sort test" if !KUNIT_ALL_TESTS 2128 depends on KUNIT 2129 default KUNIT_ALL_TESTS 2130 help 2131 This option enables the self-test function of 'sort()' at boot, 2132 or at module load time. 2133 2134 If unsure, say N. 2135 2136config TEST_DIV64 2137 tristate "64bit/32bit division and modulo test" 2138 depends on DEBUG_KERNEL || m 2139 help 2140 Enable this to turn on 'do_div()' function test. This test is 2141 executed only once during system boot (so affects only boot time), 2142 or at module load time. 2143 2144 If unsure, say N. 2145 2146config KPROBES_SANITY_TEST 2147 tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS 2148 depends on DEBUG_KERNEL 2149 depends on KPROBES 2150 depends on KUNIT 2151 select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 2152 default KUNIT_ALL_TESTS 2153 help 2154 This option provides for testing basic kprobes functionality on 2155 boot. Samples of kprobe and kretprobe are inserted and 2156 verified for functionality. 2157 2158 Say N if you are unsure. 2159 2160config FPROBE_SANITY_TEST 2161 bool "Self test for fprobe" 2162 depends on DEBUG_KERNEL 2163 depends on FPROBE 2164 depends on KUNIT=y 2165 help 2166 This option will enable testing the fprobe when the system boot. 2167 A series of tests are made to verify that the fprobe is functioning 2168 properly. 2169 2170 Say N if you are unsure. 2171 2172config BACKTRACE_SELF_TEST 2173 tristate "Self test for the backtrace code" 2174 depends on DEBUG_KERNEL 2175 help 2176 This option provides a kernel module that can be used to test 2177 the kernel stack backtrace code. This option is not useful 2178 for distributions or general kernels, but only for kernel 2179 developers working on architecture code. 2180 2181 Note that if you want to also test saved backtraces, you will 2182 have to enable STACKTRACE as well. 2183 2184 Say N if you are unsure. 2185 2186config TEST_REF_TRACKER 2187 tristate "Self test for reference tracker" 2188 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT 2189 select REF_TRACKER 2190 help 2191 This option provides a kernel module performing tests 2192 using reference tracker infrastructure. 2193 2194 Say N if you are unsure. 2195 2196config RBTREE_TEST 2197 tristate "Red-Black tree test" 2198 depends on DEBUG_KERNEL 2199 help 2200 A benchmark measuring the performance of the rbtree library. 2201 Also includes rbtree invariant checks. 2202 2203config REED_SOLOMON_TEST 2204 tristate "Reed-Solomon library test" 2205 depends on DEBUG_KERNEL || m 2206 select REED_SOLOMON 2207 select REED_SOLOMON_ENC16 2208 select REED_SOLOMON_DEC16 2209 help 2210 This option enables the self-test function of rslib at boot, 2211 or at module load time. 2212 2213 If unsure, say N. 2214 2215config INTERVAL_TREE_TEST 2216 tristate "Interval tree test" 2217 depends on DEBUG_KERNEL 2218 select INTERVAL_TREE 2219 help 2220 A benchmark measuring the performance of the interval tree library 2221 2222config PERCPU_TEST 2223 tristate "Per cpu operations test" 2224 depends on m && DEBUG_KERNEL 2225 help 2226 Enable this option to build test module which validates per-cpu 2227 operations. 2228 2229 If unsure, say N. 2230 2231config ATOMIC64_SELFTEST 2232 tristate "Perform an atomic64_t self-test" 2233 help 2234 Enable this option to test the atomic64_t functions at boot or 2235 at module load time. 2236 2237 If unsure, say N. 2238 2239config ASYNC_RAID6_TEST 2240 tristate "Self test for hardware accelerated raid6 recovery" 2241 depends on ASYNC_RAID6_RECOV 2242 select ASYNC_MEMCPY 2243 help 2244 This is a one-shot self test that permutes through the 2245 recovery of all the possible two disk failure scenarios for a 2246 N-disk array. Recovery is performed with the asynchronous 2247 raid6 recovery routines, and will optionally use an offload 2248 engine if one is available. 2249 2250 If unsure, say N. 2251 2252config TEST_HEXDUMP 2253 tristate "Test functions located in the hexdump module at runtime" 2254 2255config STRING_SELFTEST 2256 tristate "Test string functions at runtime" 2257 2258config TEST_STRING_HELPERS 2259 tristate "Test functions located in the string_helpers module at runtime" 2260 2261config TEST_KSTRTOX 2262 tristate "Test kstrto*() family of functions at runtime" 2263 2264config TEST_PRINTF 2265 tristate "Test printf() family of functions at runtime" 2266 2267config TEST_SCANF 2268 tristate "Test scanf() family of functions at runtime" 2269 2270config TEST_BITMAP 2271 tristate "Test bitmap_*() family of functions at runtime" 2272 help 2273 Enable this option to test the bitmap functions at boot. 2274 2275 If unsure, say N. 2276 2277config TEST_UUID 2278 tristate "Test functions located in the uuid module at runtime" 2279 2280config TEST_XARRAY 2281 tristate "Test the XArray code at runtime" 2282 2283config TEST_MAPLE_TREE 2284 depends on DEBUG_KERNEL 2285 select DEBUG_MAPLE_TREE 2286 tristate "Test the Maple Tree code at runtime" 2287 2288config TEST_RHASHTABLE 2289 tristate "Perform selftest on resizable hash table" 2290 help 2291 Enable this option to test the rhashtable functions at boot. 2292 2293 If unsure, say N. 2294 2295config TEST_IDA 2296 tristate "Perform selftest on IDA functions" 2297 2298config TEST_PARMAN 2299 tristate "Perform selftest on priority array manager" 2300 depends on PARMAN 2301 help 2302 Enable this option to test priority array manager on boot 2303 (or module load). 2304 2305 If unsure, say N. 2306 2307config TEST_IRQ_TIMINGS 2308 bool "IRQ timings selftest" 2309 depends on IRQ_TIMINGS 2310 help 2311 Enable this option to test the irq timings code on boot. 2312 2313 If unsure, say N. 2314 2315config TEST_LKM 2316 tristate "Test module loading with 'hello world' module" 2317 depends on m 2318 help 2319 This builds the "test_module" module that emits "Hello, world" 2320 on printk when loaded. It is designed to be used for basic 2321 evaluation of the module loading subsystem (for example when 2322 validating module verification). It lacks any extra dependencies, 2323 and will not normally be loaded by the system unless explicitly 2324 requested by name. 2325 2326 If unsure, say N. 2327 2328config TEST_BITOPS 2329 tristate "Test module for compilation of bitops operations" 2330 depends on m 2331 help 2332 This builds the "test_bitops" module that is much like the 2333 TEST_LKM module except that it does a basic exercise of the 2334 set/clear_bit macros and get_count_order/long to make sure there are 2335 no compiler warnings from C=1 sparse checker or -Wextra 2336 compilations. It has no dependencies and doesn't run or load unless 2337 explicitly requested by name. for example: modprobe test_bitops. 2338 2339 If unsure, say N. 2340 2341config TEST_VMALLOC 2342 tristate "Test module for stress/performance analysis of vmalloc allocator" 2343 default n 2344 depends on MMU 2345 depends on m 2346 help 2347 This builds the "test_vmalloc" module that should be used for 2348 stress and performance analysis. So, any new change for vmalloc 2349 subsystem can be evaluated from performance and stability point 2350 of view. 2351 2352 If unsure, say N. 2353 2354config TEST_USER_COPY 2355 tristate "Test user/kernel boundary protections" 2356 depends on m 2357 help 2358 This builds the "test_user_copy" module that runs sanity checks 2359 on the copy_to/from_user infrastructure, making sure basic 2360 user/kernel boundary testing is working. If it fails to load, 2361 a regression has been detected in the user/kernel memory boundary 2362 protections. 2363 2364 If unsure, say N. 2365 2366config TEST_BPF 2367 tristate "Test BPF filter functionality" 2368 depends on m && NET 2369 help 2370 This builds the "test_bpf" module that runs various test vectors 2371 against the BPF interpreter or BPF JIT compiler depending on the 2372 current setting. This is in particular useful for BPF JIT compiler 2373 development, but also to run regression tests against changes in 2374 the interpreter code. It also enables test stubs for eBPF maps and 2375 verifier used by user space verifier testsuite. 2376 2377 If unsure, say N. 2378 2379config TEST_BLACKHOLE_DEV 2380 tristate "Test blackhole netdev functionality" 2381 depends on m && NET 2382 help 2383 This builds the "test_blackhole_dev" module that validates the 2384 data path through this blackhole netdev. 2385 2386 If unsure, say N. 2387 2388config FIND_BIT_BENCHMARK 2389 tristate "Test find_bit functions" 2390 help 2391 This builds the "test_find_bit" module that measure find_*_bit() 2392 functions performance. 2393 2394 If unsure, say N. 2395 2396config TEST_FIRMWARE 2397 tristate "Test firmware loading via userspace interface" 2398 depends on FW_LOADER 2399 help 2400 This builds the "test_firmware" module that creates a userspace 2401 interface for testing firmware loading. This can be used to 2402 control the triggering of firmware loading without needing an 2403 actual firmware-using device. The contents can be rechecked by 2404 userspace. 2405 2406 If unsure, say N. 2407 2408config TEST_SYSCTL 2409 tristate "sysctl test driver" 2410 depends on PROC_SYSCTL 2411 help 2412 This builds the "test_sysctl" module. This driver enables to test the 2413 proc sysctl interfaces available to drivers safely without affecting 2414 production knobs which might alter system functionality. 2415 2416 If unsure, say N. 2417 2418config BITFIELD_KUNIT 2419 tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS 2420 depends on KUNIT 2421 default KUNIT_ALL_TESTS 2422 help 2423 Enable this option to test the bitfield functions at boot. 2424 2425 KUnit tests run during boot and output the results to the debug log 2426 in TAP format (http://testanything.org/). Only useful for kernel devs 2427 running the KUnit test harness, and not intended for inclusion into a 2428 production build. 2429 2430 For more information on KUnit and unit tests in general please refer 2431 to the KUnit documentation in Documentation/dev-tools/kunit/. 2432 2433 If unsure, say N. 2434 2435config HASH_KUNIT_TEST 2436 tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS 2437 depends on KUNIT 2438 default KUNIT_ALL_TESTS 2439 help 2440 Enable this option to test the kernel's string (<linux/stringhash.h>), and 2441 integer (<linux/hash.h>) hash functions on boot. 2442 2443 KUnit tests run during boot and output the results to the debug log 2444 in TAP format (https://testanything.org/). Only useful for kernel devs 2445 running the KUnit test harness, and not intended for inclusion into a 2446 production build. 2447 2448 For more information on KUnit and unit tests in general please refer 2449 to the KUnit documentation in Documentation/dev-tools/kunit/. 2450 2451 This is intended to help people writing architecture-specific 2452 optimized versions. If unsure, say N. 2453 2454config RESOURCE_KUNIT_TEST 2455 tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS 2456 depends on KUNIT 2457 default KUNIT_ALL_TESTS 2458 help 2459 This builds the resource API unit test. 2460 Tests the logic of API provided by resource.c and ioport.h. 2461 For more information on KUnit and unit tests in general please refer 2462 to the KUnit documentation in Documentation/dev-tools/kunit/. 2463 2464 If unsure, say N. 2465 2466config SYSCTL_KUNIT_TEST 2467 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS 2468 depends on KUNIT 2469 default KUNIT_ALL_TESTS 2470 help 2471 This builds the proc sysctl unit test, which runs on boot. 2472 Tests the API contract and implementation correctness of sysctl. 2473 For more information on KUnit and unit tests in general please refer 2474 to the KUnit documentation in Documentation/dev-tools/kunit/. 2475 2476 If unsure, say N. 2477 2478config LIST_KUNIT_TEST 2479 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS 2480 depends on KUNIT 2481 default KUNIT_ALL_TESTS 2482 help 2483 This builds the linked list KUnit test suite. 2484 It tests that the API and basic functionality of the list_head type 2485 and associated macros. 2486 2487 KUnit tests run during boot and output the results to the debug log 2488 in TAP format (https://testanything.org/). Only useful for kernel devs 2489 running the KUnit test harness, and not intended for inclusion into a 2490 production build. 2491 2492 For more information on KUnit and unit tests in general please refer 2493 to the KUnit documentation in Documentation/dev-tools/kunit/. 2494 2495 If unsure, say N. 2496 2497config HASHTABLE_KUNIT_TEST 2498 tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS 2499 depends on KUNIT 2500 default KUNIT_ALL_TESTS 2501 help 2502 This builds the hashtable KUnit test suite. 2503 It tests the basic functionality of the API defined in 2504 include/linux/hashtable.h. For more information on KUnit and 2505 unit tests in general please refer to the KUnit documentation 2506 in Documentation/dev-tools/kunit/. 2507 2508 If unsure, say N. 2509 2510config LINEAR_RANGES_TEST 2511 tristate "KUnit test for linear_ranges" 2512 depends on KUNIT 2513 select LINEAR_RANGES 2514 help 2515 This builds the linear_ranges unit test, which runs on boot. 2516 Tests the linear_ranges logic correctness. 2517 For more information on KUnit and unit tests in general please refer 2518 to the KUnit documentation in Documentation/dev-tools/kunit/. 2519 2520 If unsure, say N. 2521 2522config CMDLINE_KUNIT_TEST 2523 tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS 2524 depends on KUNIT 2525 default KUNIT_ALL_TESTS 2526 help 2527 This builds the cmdline API unit test. 2528 Tests the logic of API provided by cmdline.c. 2529 For more information on KUnit and unit tests in general please refer 2530 to the KUnit documentation in Documentation/dev-tools/kunit/. 2531 2532 If unsure, say N. 2533 2534config BITS_TEST 2535 tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS 2536 depends on KUNIT 2537 default KUNIT_ALL_TESTS 2538 help 2539 This builds the bits unit test. 2540 Tests the logic of macros defined in bits.h. 2541 For more information on KUnit and unit tests in general please refer 2542 to the KUnit documentation in Documentation/dev-tools/kunit/. 2543 2544 If unsure, say N. 2545 2546config SLUB_KUNIT_TEST 2547 tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS 2548 depends on SLUB_DEBUG && KUNIT 2549 default KUNIT_ALL_TESTS 2550 help 2551 This builds SLUB allocator unit test. 2552 Tests SLUB cache debugging functionality. 2553 For more information on KUnit and unit tests in general please refer 2554 to the KUnit documentation in Documentation/dev-tools/kunit/. 2555 2556 If unsure, say N. 2557 2558config RATIONAL_KUNIT_TEST 2559 tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS 2560 depends on KUNIT && RATIONAL 2561 default KUNIT_ALL_TESTS 2562 help 2563 This builds the rational math unit test. 2564 For more information on KUnit and unit tests in general please refer 2565 to the KUnit documentation in Documentation/dev-tools/kunit/. 2566 2567 If unsure, say N. 2568 2569config MEMCPY_KUNIT_TEST 2570 tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS 2571 depends on KUNIT 2572 default KUNIT_ALL_TESTS 2573 help 2574 Builds unit tests for memcpy(), memmove(), and memset() functions. 2575 For more information on KUnit and unit tests in general please refer 2576 to the KUnit documentation in Documentation/dev-tools/kunit/. 2577 2578 If unsure, say N. 2579 2580config MEMCPY_SLOW_KUNIT_TEST 2581 bool "Include exhaustive memcpy tests" 2582 depends on MEMCPY_KUNIT_TEST 2583 default y 2584 help 2585 Some memcpy tests are quite exhaustive in checking for overlaps 2586 and bit ranges. These can be very slow, so they are split out 2587 as a separate config, in case they need to be disabled. 2588 2589config IS_SIGNED_TYPE_KUNIT_TEST 2590 tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS 2591 depends on KUNIT 2592 default KUNIT_ALL_TESTS 2593 help 2594 Builds unit tests for the is_signed_type() macro. 2595 2596 For more information on KUnit and unit tests in general please refer 2597 to the KUnit documentation in Documentation/dev-tools/kunit/. 2598 2599 If unsure, say N. 2600 2601config OVERFLOW_KUNIT_TEST 2602 tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS 2603 depends on KUNIT 2604 default KUNIT_ALL_TESTS 2605 help 2606 Builds unit tests for the check_*_overflow(), size_*(), allocation, and 2607 related functions. 2608 2609 For more information on KUnit and unit tests in general please refer 2610 to the KUnit documentation in Documentation/dev-tools/kunit/. 2611 2612 If unsure, say N. 2613 2614config STACKINIT_KUNIT_TEST 2615 tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS 2616 depends on KUNIT 2617 default KUNIT_ALL_TESTS 2618 help 2619 Test if the kernel is zero-initializing stack variables and 2620 padding. Coverage is controlled by compiler flags, 2621 CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO, 2622 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2623 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2624 2625config FORTIFY_KUNIT_TEST 2626 tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS 2627 depends on KUNIT && FORTIFY_SOURCE 2628 default KUNIT_ALL_TESTS 2629 help 2630 Builds unit tests for checking internals of FORTIFY_SOURCE as used 2631 by the str*() and mem*() family of functions. For testing runtime 2632 traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests. 2633 2634config HW_BREAKPOINT_KUNIT_TEST 2635 bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS 2636 depends on HAVE_HW_BREAKPOINT 2637 depends on KUNIT=y 2638 default KUNIT_ALL_TESTS 2639 help 2640 Tests for hw_breakpoint constraints accounting. 2641 2642 If unsure, say N. 2643 2644config STRSCPY_KUNIT_TEST 2645 tristate "Test strscpy*() family of functions at runtime" if !KUNIT_ALL_TESTS 2646 depends on KUNIT 2647 default KUNIT_ALL_TESTS 2648 2649config SIPHASH_KUNIT_TEST 2650 tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS 2651 depends on KUNIT 2652 default KUNIT_ALL_TESTS 2653 help 2654 Enable this option to test the kernel's siphash (<linux/siphash.h>) hash 2655 functions on boot (or module load). 2656 2657 This is intended to help people writing architecture-specific 2658 optimized versions. If unsure, say N. 2659 2660config TEST_UDELAY 2661 tristate "udelay test driver" 2662 help 2663 This builds the "udelay_test" module that helps to make sure 2664 that udelay() is working properly. 2665 2666 If unsure, say N. 2667 2668config TEST_STATIC_KEYS 2669 tristate "Test static keys" 2670 depends on m 2671 help 2672 Test the static key interfaces. 2673 2674 If unsure, say N. 2675 2676config TEST_DYNAMIC_DEBUG 2677 tristate "Test DYNAMIC_DEBUG" 2678 depends on DYNAMIC_DEBUG 2679 help 2680 This module registers a tracer callback to count enabled 2681 pr_debugs in a 'do_debugging' function, then alters their 2682 enablements, calls the function, and compares counts. 2683 2684 If unsure, say N. 2685 2686config TEST_KMOD 2687 tristate "kmod stress tester" 2688 depends on m 2689 depends on NETDEVICES && NET_CORE && INET # for TUN 2690 depends on BLOCK 2691 depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS 2692 select TEST_LKM 2693 select XFS_FS 2694 select TUN 2695 select BTRFS_FS 2696 help 2697 Test the kernel's module loading mechanism: kmod. kmod implements 2698 support to load modules using the Linux kernel's usermode helper. 2699 This test provides a series of tests against kmod. 2700 2701 Although technically you can either build test_kmod as a module or 2702 into the kernel we disallow building it into the kernel since 2703 it stress tests request_module() and this will very likely cause 2704 some issues by taking over precious threads available from other 2705 module load requests, ultimately this could be fatal. 2706 2707 To run tests run: 2708 2709 tools/testing/selftests/kmod/kmod.sh --help 2710 2711 If unsure, say N. 2712 2713config TEST_DEBUG_VIRTUAL 2714 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 2715 depends on DEBUG_VIRTUAL 2716 help 2717 Test the kernel's ability to detect incorrect calls to 2718 virt_to_phys() done against the non-linear part of the 2719 kernel's virtual address map. 2720 2721 If unsure, say N. 2722 2723config TEST_MEMCAT_P 2724 tristate "Test memcat_p() helper function" 2725 help 2726 Test the memcat_p() helper for correctly merging two 2727 pointer arrays together. 2728 2729 If unsure, say N. 2730 2731config TEST_LIVEPATCH 2732 tristate "Test livepatching" 2733 default n 2734 depends on DYNAMIC_DEBUG 2735 depends on LIVEPATCH 2736 depends on m 2737 help 2738 Test kernel livepatching features for correctness. The tests will 2739 load test modules that will be livepatched in various scenarios. 2740 2741 To run all the livepatching tests: 2742 2743 make -C tools/testing/selftests TARGETS=livepatch run_tests 2744 2745 Alternatively, individual tests may be invoked: 2746 2747 tools/testing/selftests/livepatch/test-callbacks.sh 2748 tools/testing/selftests/livepatch/test-livepatch.sh 2749 tools/testing/selftests/livepatch/test-shadow-vars.sh 2750 2751 If unsure, say N. 2752 2753config TEST_OBJAGG 2754 tristate "Perform selftest on object aggreration manager" 2755 default n 2756 depends on OBJAGG 2757 help 2758 Enable this option to test object aggregation manager on boot 2759 (or module load). 2760 2761config TEST_MEMINIT 2762 tristate "Test heap/page initialization" 2763 help 2764 Test if the kernel is zero-initializing heap and page allocations. 2765 This can be useful to test init_on_alloc and init_on_free features. 2766 2767 If unsure, say N. 2768 2769config TEST_HMM 2770 tristate "Test HMM (Heterogeneous Memory Management)" 2771 depends on TRANSPARENT_HUGEPAGE 2772 depends on DEVICE_PRIVATE 2773 select HMM_MIRROR 2774 select MMU_NOTIFIER 2775 help 2776 This is a pseudo device driver solely for testing HMM. 2777 Say M here if you want to build the HMM test module. 2778 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests. 2779 2780 If unsure, say N. 2781 2782config TEST_FREE_PAGES 2783 tristate "Test freeing pages" 2784 help 2785 Test that a memory leak does not occur due to a race between 2786 freeing a block of pages and a speculative page reference. 2787 Loading this module is safe if your kernel has the bug fixed. 2788 If the bug is not fixed, it will leak gigabytes of memory and 2789 probably OOM your system. 2790 2791config TEST_FPU 2792 tristate "Test floating point operations in kernel space" 2793 depends on X86 && !KCOV_INSTRUMENT_ALL 2794 help 2795 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu 2796 which will trigger a sequence of floating point operations. This is used 2797 for self-testing floating point control register setting in 2798 kernel_fpu_begin(). 2799 2800 If unsure, say N. 2801 2802config TEST_CLOCKSOURCE_WATCHDOG 2803 tristate "Test clocksource watchdog in kernel space" 2804 depends on CLOCKSOURCE_WATCHDOG 2805 help 2806 Enable this option to create a kernel module that will trigger 2807 a test of the clocksource watchdog. This module may be loaded 2808 via modprobe or insmod in which case it will run upon being 2809 loaded, or it may be built in, in which case it will run 2810 shortly after boot. 2811 2812 If unsure, say N. 2813 2814endif # RUNTIME_TESTING_MENU 2815 2816config ARCH_USE_MEMTEST 2817 bool 2818 help 2819 An architecture should select this when it uses early_memtest() 2820 during boot process. 2821 2822config MEMTEST 2823 bool "Memtest" 2824 depends on ARCH_USE_MEMTEST 2825 help 2826 This option adds a kernel parameter 'memtest', which allows memtest 2827 to be set and executed. 2828 memtest=0, mean disabled; -- default 2829 memtest=1, mean do 1 test pattern; 2830 ... 2831 memtest=17, mean do 17 test patterns. 2832 If you are unsure how to answer this question, answer N. 2833 2834 2835 2836config HYPERV_TESTING 2837 bool "Microsoft Hyper-V driver testing" 2838 default n 2839 depends on HYPERV && DEBUG_FS 2840 help 2841 Select this option to enable Hyper-V vmbus testing. 2842 2843endmenu # "Kernel Testing and Coverage" 2844 2845menu "Rust hacking" 2846 2847config RUST_DEBUG_ASSERTIONS 2848 bool "Debug assertions" 2849 depends on RUST 2850 help 2851 Enables rustc's `-Cdebug-assertions` codegen option. 2852 2853 This flag lets you turn `cfg(debug_assertions)` conditional 2854 compilation on or off. This can be used to enable extra debugging 2855 code in development but not in production. For example, it controls 2856 the behavior of the standard library's `debug_assert!` macro. 2857 2858 Note that this will apply to all Rust code, including `core`. 2859 2860 If unsure, say N. 2861 2862config RUST_OVERFLOW_CHECKS 2863 bool "Overflow checks" 2864 default y 2865 depends on RUST 2866 help 2867 Enables rustc's `-Coverflow-checks` codegen option. 2868 2869 This flag allows you to control the behavior of runtime integer 2870 overflow. When overflow-checks are enabled, a Rust panic will occur 2871 on overflow. 2872 2873 Note that this will apply to all Rust code, including `core`. 2874 2875 If unsure, say Y. 2876 2877config RUST_BUILD_ASSERT_ALLOW 2878 bool "Allow unoptimized build-time assertions" 2879 depends on RUST 2880 help 2881 Controls how are `build_error!` and `build_assert!` handled during build. 2882 2883 If calls to them exist in the binary, it may indicate a violated invariant 2884 or that the optimizer failed to verify the invariant during compilation. 2885 2886 This should not happen, thus by default the build is aborted. However, 2887 as an escape hatch, you can choose Y here to ignore them during build 2888 and let the check be carried at runtime (with `panic!` being called if 2889 the check fails). 2890 2891 If unsure, say N. 2892 2893endmenu # "Rust" 2894 2895endmenu # Kernel hacking 2896