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 DEBUG_INFO_BTF_MODULES 393 def_bool y 394 depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF 395 help 396 Generate compact split BTF type information for kernel modules. 397 398config MODULE_ALLOW_BTF_MISMATCH 399 bool "Allow loading modules with non-matching BTF type info" 400 depends on DEBUG_INFO_BTF_MODULES 401 help 402 For modules whose split BTF does not match vmlinux, load without 403 BTF rather than refusing to load. The default behavior with 404 module BTF enabled is to reject modules with such mismatches; 405 this option will still load module BTF where possible but ignore 406 it when a mismatch is found. 407 408config GDB_SCRIPTS 409 bool "Provide GDB scripts for kernel debugging" 410 help 411 This creates the required links to GDB helper scripts in the 412 build directory. If you load vmlinux into gdb, the helper 413 scripts will be automatically imported by gdb as well, and 414 additional functions are available to analyze a Linux kernel 415 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst 416 for further details. 417 418endif # DEBUG_INFO 419 420config FRAME_WARN 421 int "Warn for stack frames larger than" 422 range 0 8192 423 default 0 if KMSAN 424 default 2048 if GCC_PLUGIN_LATENT_ENTROPY 425 default 2048 if PARISC 426 default 1536 if (!64BIT && XTENSA) 427 default 1280 if KASAN && !64BIT 428 default 1024 if !64BIT 429 default 2048 if 64BIT 430 help 431 Tell the compiler to warn at build time for stack frames larger than this. 432 Setting this too low will cause a lot of warnings. 433 Setting it to 0 disables the warning. 434 435config STRIP_ASM_SYMS 436 bool "Strip assembler-generated symbols during link" 437 default n 438 help 439 Strip internal assembler-generated symbols during a link (symbols 440 that look like '.Lxxx') so they don't pollute the output of 441 get_wchan() and suchlike. 442 443config READABLE_ASM 444 bool "Generate readable assembler code" 445 depends on DEBUG_KERNEL 446 depends on CC_IS_GCC 447 help 448 Disable some compiler optimizations that tend to generate human unreadable 449 assembler output. This may make the kernel slightly slower, but it helps 450 to keep kernel developers who have to stare a lot at assembler listings 451 sane. 452 453config HEADERS_INSTALL 454 bool "Install uapi headers to usr/include" 455 depends on !UML 456 help 457 This option will install uapi headers (headers exported to user-space) 458 into the usr/include directory for use during the kernel build. 459 This is unneeded for building the kernel itself, but needed for some 460 user-space program samples. It is also needed by some features such 461 as uapi header sanity checks. 462 463config DEBUG_SECTION_MISMATCH 464 bool "Enable full Section mismatch analysis" 465 depends on CC_IS_GCC 466 help 467 The section mismatch analysis checks if there are illegal 468 references from one section to another section. 469 During linktime or runtime, some sections are dropped; 470 any use of code/data previously in these sections would 471 most likely result in an oops. 472 In the code, functions and variables are annotated with 473 __init,, etc. (see the full list in include/linux/init.h), 474 which results in the code/data being placed in specific sections. 475 The section mismatch analysis is always performed after a full 476 kernel build, and enabling this option causes the following 477 additional step to occur: 478 - Add the option -fno-inline-functions-called-once to gcc commands. 479 When inlining a function annotated with __init in a non-init 480 function, we would lose the section information and thus 481 the analysis would not catch the illegal reference. 482 This option tells gcc to inline less (but it does result in 483 a larger kernel). 484 485config SECTION_MISMATCH_WARN_ONLY 486 bool "Make section mismatch errors non-fatal" 487 default y 488 help 489 If you say N here, the build process will fail if there are any 490 section mismatch, instead of just throwing warnings. 491 492 If unsure, say Y. 493 494config DEBUG_FORCE_FUNCTION_ALIGN_64B 495 bool "Force all function address 64B aligned" 496 depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC) 497 select FUNCTION_ALIGNMENT_64B 498 help 499 There are cases that a commit from one domain changes the function 500 address alignment of other domains, and cause magic performance 501 bump (regression or improvement). Enable this option will help to 502 verify if the bump is caused by function alignment changes, while 503 it will slightly increase the kernel size and affect icache usage. 504 505 It is mainly for debug and performance tuning use. 506 507# 508# Select this config option from the architecture Kconfig, if it 509# is preferred to always offer frame pointers as a config 510# option on the architecture (regardless of KERNEL_DEBUG): 511# 512config ARCH_WANT_FRAME_POINTERS 513 bool 514 515config FRAME_POINTER 516 bool "Compile the kernel with frame pointers" 517 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS 518 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 519 help 520 If you say Y here the resulting kernel image will be slightly 521 larger and slower, but it gives very useful debugging information 522 in case of kernel bugs. (precise oopses/stacktraces/warnings) 523 524config OBJTOOL 525 bool 526 527config STACK_VALIDATION 528 bool "Compile-time stack metadata validation" 529 depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER 530 select OBJTOOL 531 default n 532 help 533 Validate frame pointer rules at compile-time. This helps ensure that 534 runtime stack traces are more reliable. 535 536 For more information, see 537 tools/objtool/Documentation/objtool.txt. 538 539config NOINSTR_VALIDATION 540 bool 541 depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY 542 select OBJTOOL 543 default y 544 545config VMLINUX_MAP 546 bool "Generate vmlinux.map file when linking" 547 depends on EXPERT 548 help 549 Selecting this option will pass "-Map=vmlinux.map" to ld 550 when linking vmlinux. That file can be useful for verifying 551 and debugging magic section games, and for seeing which 552 pieces of code get eliminated with 553 CONFIG_LD_DEAD_CODE_DATA_ELIMINATION. 554 555config DEBUG_FORCE_WEAK_PER_CPU 556 bool "Force weak per-cpu definitions" 557 depends on DEBUG_KERNEL 558 help 559 s390 and alpha require percpu variables in modules to be 560 defined weak to work around addressing range issue which 561 puts the following two restrictions on percpu variable 562 definitions. 563 564 1. percpu symbols must be unique whether static or not 565 2. percpu variables can't be defined inside a function 566 567 To ensure that generic code follows the above rules, this 568 option forces all percpu variables to be defined as weak. 569 570endmenu # "Compiler options" 571 572menu "Generic Kernel Debugging Instruments" 573 574config MAGIC_SYSRQ 575 bool "Magic SysRq key" 576 depends on !UML 577 help 578 If you say Y here, you will have some control over the system even 579 if the system crashes for example during kernel debugging (e.g., you 580 will be able to flush the buffer cache to disk, reboot the system 581 immediately or dump some status information). This is accomplished 582 by pressing various keys while holding SysRq (Alt+PrintScreen). It 583 also works on a serial console (on PC hardware at least), if you 584 send a BREAK and then within 5 seconds a command keypress. The 585 keys are documented in <file:Documentation/admin-guide/sysrq.rst>. 586 Don't say Y unless you really know what this hack does. 587 588config MAGIC_SYSRQ_DEFAULT_ENABLE 589 hex "Enable magic SysRq key functions by default" 590 depends on MAGIC_SYSRQ 591 default 0x1 592 help 593 Specifies which SysRq key functions are enabled by default. 594 This may be set to 1 or 0 to enable or disable them all, or 595 to a bitmask as described in Documentation/admin-guide/sysrq.rst. 596 597config MAGIC_SYSRQ_SERIAL 598 bool "Enable magic SysRq key over serial" 599 depends on MAGIC_SYSRQ 600 default y 601 help 602 Many embedded boards have a disconnected TTL level serial which can 603 generate some garbage that can lead to spurious false sysrq detects. 604 This option allows you to decide whether you want to enable the 605 magic SysRq key. 606 607config MAGIC_SYSRQ_SERIAL_SEQUENCE 608 string "Char sequence that enables magic SysRq over serial" 609 depends on MAGIC_SYSRQ_SERIAL 610 default "" 611 help 612 Specifies a sequence of characters that can follow BREAK to enable 613 SysRq on a serial console. 614 615 If unsure, leave an empty string and the option will not be enabled. 616 617config DEBUG_FS 618 bool "Debug Filesystem" 619 help 620 debugfs is a virtual file system that kernel developers use to put 621 debugging files into. Enable this option to be able to read and 622 write to these files. 623 624 For detailed documentation on the debugfs API, see 625 Documentation/filesystems/. 626 627 If unsure, say N. 628 629choice 630 prompt "Debugfs default access" 631 depends on DEBUG_FS 632 default DEBUG_FS_ALLOW_ALL 633 help 634 This selects the default access restrictions for debugfs. 635 It can be overridden with kernel command line option 636 debugfs=[on,no-mount,off]. The restrictions apply for API access 637 and filesystem registration. 638 639config DEBUG_FS_ALLOW_ALL 640 bool "Access normal" 641 help 642 No restrictions apply. Both API and filesystem registration 643 is on. This is the normal default operation. 644 645config DEBUG_FS_DISALLOW_MOUNT 646 bool "Do not register debugfs as filesystem" 647 help 648 The API is open but filesystem is not loaded. Clients can still do 649 their work and read with debug tools that do not need 650 debugfs filesystem. 651 652config DEBUG_FS_ALLOW_NONE 653 bool "No access" 654 help 655 Access is off. Clients get -PERM when trying to create nodes in 656 debugfs tree and debugfs is not registered as a filesystem. 657 Client can then back-off or continue without debugfs access. 658 659endchoice 660 661source "lib/Kconfig.kgdb" 662source "lib/Kconfig.ubsan" 663source "lib/Kconfig.kcsan" 664 665endmenu 666 667menu "Networking Debugging" 668 669source "net/Kconfig.debug" 670 671endmenu # "Networking Debugging" 672 673menu "Memory Debugging" 674 675source "mm/Kconfig.debug" 676 677config DEBUG_OBJECTS 678 bool "Debug object operations" 679 depends on DEBUG_KERNEL 680 help 681 If you say Y here, additional code will be inserted into the 682 kernel to track the life time of various objects and validate 683 the operations on those objects. 684 685config DEBUG_OBJECTS_SELFTEST 686 bool "Debug objects selftest" 687 depends on DEBUG_OBJECTS 688 help 689 This enables the selftest of the object debug code. 690 691config DEBUG_OBJECTS_FREE 692 bool "Debug objects in freed memory" 693 depends on DEBUG_OBJECTS 694 help 695 This enables checks whether a k/v free operation frees an area 696 which contains an object which has not been deactivated 697 properly. This can make kmalloc/kfree-intensive workloads 698 much slower. 699 700config DEBUG_OBJECTS_TIMERS 701 bool "Debug timer objects" 702 depends on DEBUG_OBJECTS 703 help 704 If you say Y here, additional code will be inserted into the 705 timer routines to track the life time of timer objects and 706 validate the timer operations. 707 708config DEBUG_OBJECTS_WORK 709 bool "Debug work objects" 710 depends on DEBUG_OBJECTS 711 help 712 If you say Y here, additional code will be inserted into the 713 work queue routines to track the life time of work objects and 714 validate the work operations. 715 716config DEBUG_OBJECTS_RCU_HEAD 717 bool "Debug RCU callbacks objects" 718 depends on DEBUG_OBJECTS 719 help 720 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 721 722config DEBUG_OBJECTS_PERCPU_COUNTER 723 bool "Debug percpu counter objects" 724 depends on DEBUG_OBJECTS 725 help 726 If you say Y here, additional code will be inserted into the 727 percpu counter routines to track the life time of percpu counter 728 objects and validate the percpu counter operations. 729 730config DEBUG_OBJECTS_ENABLE_DEFAULT 731 int "debug_objects bootup default value (0-1)" 732 range 0 1 733 default "1" 734 depends on DEBUG_OBJECTS 735 help 736 Debug objects boot parameter default value 737 738config SHRINKER_DEBUG 739 bool "Enable shrinker debugging support" 740 depends on DEBUG_FS 741 help 742 Say Y to enable the shrinker debugfs interface which provides 743 visibility into the kernel memory shrinkers subsystem. 744 Disable it to avoid an extra memory footprint. 745 746config HAVE_DEBUG_KMEMLEAK 747 bool 748 749config DEBUG_KMEMLEAK 750 bool "Kernel memory leak detector" 751 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK 752 select DEBUG_FS 753 select STACKTRACE if STACKTRACE_SUPPORT 754 select KALLSYMS 755 select CRC32 756 select STACKDEPOT 757 help 758 Say Y here if you want to enable the memory leak 759 detector. The memory allocation/freeing is traced in a way 760 similar to the Boehm's conservative garbage collector, the 761 difference being that the orphan objects are not freed but 762 only shown in /sys/kernel/debug/kmemleak. Enabling this 763 feature will introduce an overhead to memory 764 allocations. See Documentation/dev-tools/kmemleak.rst for more 765 details. 766 767 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances 768 of finding leaks due to the slab objects poisoning. 769 770 In order to access the kmemleak file, debugfs needs to be 771 mounted (usually at /sys/kernel/debug). 772 773config DEBUG_KMEMLEAK_MEM_POOL_SIZE 774 int "Kmemleak memory pool size" 775 depends on DEBUG_KMEMLEAK 776 range 200 1000000 777 default 16000 778 help 779 Kmemleak must track all the memory allocations to avoid 780 reporting false positives. Since memory may be allocated or 781 freed before kmemleak is fully initialised, use a static pool 782 of metadata objects to track such callbacks. After kmemleak is 783 fully initialised, this memory pool acts as an emergency one 784 if slab allocations fail. 785 786config DEBUG_KMEMLEAK_TEST 787 tristate "Simple test for the kernel memory leak detector" 788 depends on DEBUG_KMEMLEAK && m 789 help 790 This option enables a module that explicitly leaks memory. 791 792 If unsure, say N. 793 794config DEBUG_KMEMLEAK_DEFAULT_OFF 795 bool "Default kmemleak to off" 796 depends on DEBUG_KMEMLEAK 797 help 798 Say Y here to disable kmemleak by default. It can then be enabled 799 on the command line via kmemleak=on. 800 801config DEBUG_KMEMLEAK_AUTO_SCAN 802 bool "Enable kmemleak auto scan thread on boot up" 803 default y 804 depends on DEBUG_KMEMLEAK 805 help 806 Depending on the cpu, kmemleak scan may be cpu intensive and can 807 stall user tasks at times. This option enables/disables automatic 808 kmemleak scan at boot up. 809 810 Say N here to disable kmemleak auto scan thread to stop automatic 811 scanning. Disabling this option disables automatic reporting of 812 memory leaks. 813 814 If unsure, say Y. 815 816config DEBUG_STACK_USAGE 817 bool "Stack utilization instrumentation" 818 depends on DEBUG_KERNEL && !IA64 819 help 820 Enables the display of the minimum amount of free stack which each 821 task has ever had available in the sysrq-T and sysrq-P debug output. 822 823 This option will slow down process creation somewhat. 824 825config SCHED_STACK_END_CHECK 826 bool "Detect stack corruption on calls to schedule()" 827 depends on DEBUG_KERNEL 828 default n 829 help 830 This option checks for a stack overrun on calls to schedule(). 831 If the stack end location is found to be over written always panic as 832 the content of the corrupted region can no longer be trusted. 833 This is to ensure no erroneous behaviour occurs which could result in 834 data corruption or a sporadic crash at a later stage once the region 835 is examined. The runtime overhead introduced is minimal. 836 837config ARCH_HAS_DEBUG_VM_PGTABLE 838 bool 839 help 840 An architecture should select this when it can successfully 841 build and run DEBUG_VM_PGTABLE. 842 843config DEBUG_VM_IRQSOFF 844 def_bool DEBUG_VM && !PREEMPT_RT 845 846config DEBUG_VM 847 bool "Debug VM" 848 depends on DEBUG_KERNEL 849 help 850 Enable this to turn on extended checks in the virtual-memory system 851 that may impact performance. 852 853 If unsure, say N. 854 855config DEBUG_VM_MAPLE_TREE 856 bool "Debug VM maple trees" 857 depends on DEBUG_VM 858 select DEBUG_MAPLE_TREE 859 help 860 Enable VM maple tree debugging information and extra validations. 861 862 If unsure, say N. 863 864config DEBUG_VM_RB 865 bool "Debug VM red-black trees" 866 depends on DEBUG_VM 867 help 868 Enable VM red-black tree debugging information and extra validations. 869 870 If unsure, say N. 871 872config DEBUG_VM_PGFLAGS 873 bool "Debug page-flags operations" 874 depends on DEBUG_VM 875 help 876 Enables extra validation on page flags operations. 877 878 If unsure, say N. 879 880config DEBUG_VM_PGTABLE 881 bool "Debug arch page table for semantics compliance" 882 depends on MMU 883 depends on ARCH_HAS_DEBUG_VM_PGTABLE 884 default y if DEBUG_VM 885 help 886 This option provides a debug method which can be used to test 887 architecture page table helper functions on various platforms in 888 verifying if they comply with expected generic MM semantics. This 889 will help architecture code in making sure that any changes or 890 new additions of these helpers still conform to expected 891 semantics of the generic MM. Platforms will have to opt in for 892 this through ARCH_HAS_DEBUG_VM_PGTABLE. 893 894 If unsure, say N. 895 896config ARCH_HAS_DEBUG_VIRTUAL 897 bool 898 899config DEBUG_VIRTUAL 900 bool "Debug VM translations" 901 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL 902 help 903 Enable some costly sanity checks in virtual to page code. This can 904 catch mistakes with virt_to_page() and friends. 905 906 If unsure, say N. 907 908config DEBUG_NOMMU_REGIONS 909 bool "Debug the global anon/private NOMMU mapping region tree" 910 depends on DEBUG_KERNEL && !MMU 911 help 912 This option causes the global tree of anonymous and private mapping 913 regions to be regularly checked for invalid topology. 914 915config DEBUG_MEMORY_INIT 916 bool "Debug memory initialisation" if EXPERT 917 default !EXPERT 918 help 919 Enable this for additional checks during memory initialisation. 920 The sanity checks verify aspects of the VM such as the memory model 921 and other information provided by the architecture. Verbose 922 information will be printed at KERN_DEBUG loglevel depending 923 on the mminit_loglevel= command-line option. 924 925 If unsure, say Y 926 927config MEMORY_NOTIFIER_ERROR_INJECT 928 tristate "Memory hotplug notifier error injection module" 929 depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION 930 help 931 This option provides the ability to inject artificial errors to 932 memory hotplug notifier chain callbacks. It is controlled through 933 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 934 935 If the notifier call chain should be failed with some events 936 notified, write the error code to "actions/<notifier event>/error". 937 938 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 939 940 # cd /sys/kernel/debug/notifier-error-inject/memory 941 # echo -12 > actions/MEM_GOING_OFFLINE/error 942 # echo offline > /sys/devices/system/memory/memoryXXX/state 943 bash: echo: write error: Cannot allocate memory 944 945 To compile this code as a module, choose M here: the module will 946 be called memory-notifier-error-inject. 947 948 If unsure, say N. 949 950config DEBUG_PER_CPU_MAPS 951 bool "Debug access to per_cpu maps" 952 depends on DEBUG_KERNEL 953 depends on SMP 954 help 955 Say Y to verify that the per_cpu map being accessed has 956 been set up. This adds a fair amount of code to kernel memory 957 and decreases performance. 958 959 Say N if unsure. 960 961config DEBUG_KMAP_LOCAL 962 bool "Debug kmap_local temporary mappings" 963 depends on DEBUG_KERNEL && KMAP_LOCAL 964 help 965 This option enables additional error checking for the kmap_local 966 infrastructure. Disable for production use. 967 968config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 969 bool 970 971config DEBUG_KMAP_LOCAL_FORCE_MAP 972 bool "Enforce kmap_local temporary mappings" 973 depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 974 select KMAP_LOCAL 975 select DEBUG_KMAP_LOCAL 976 help 977 This option enforces temporary mappings through the kmap_local 978 mechanism for non-highmem pages and on non-highmem systems. 979 Disable this for production systems! 980 981config DEBUG_HIGHMEM 982 bool "Highmem debugging" 983 depends on DEBUG_KERNEL && HIGHMEM 984 select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 985 select DEBUG_KMAP_LOCAL 986 help 987 This option enables additional error checking for high memory 988 systems. Disable for production systems. 989 990config HAVE_DEBUG_STACKOVERFLOW 991 bool 992 993config DEBUG_STACKOVERFLOW 994 bool "Check for stack overflows" 995 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 996 help 997 Say Y here if you want to check for overflows of kernel, IRQ 998 and exception stacks (if your architecture uses them). This 999 option will show detailed messages if free stack space drops 1000 below a certain limit. 1001 1002 These kinds of bugs usually occur when call-chains in the 1003 kernel get too deep, especially when interrupts are 1004 involved. 1005 1006 Use this in cases where you see apparently random memory 1007 corruption, especially if it appears in 'struct thread_info' 1008 1009 If in doubt, say "N". 1010 1011source "lib/Kconfig.kasan" 1012source "lib/Kconfig.kfence" 1013source "lib/Kconfig.kmsan" 1014 1015endmenu # "Memory Debugging" 1016 1017config DEBUG_SHIRQ 1018 bool "Debug shared IRQ handlers" 1019 depends on DEBUG_KERNEL 1020 help 1021 Enable this to generate a spurious interrupt just before a shared 1022 interrupt handler is deregistered (generating one when registering 1023 is currently disabled). Drivers need to handle this correctly. Some 1024 don't and need to be caught. 1025 1026menu "Debug Oops, Lockups and Hangs" 1027 1028config PANIC_ON_OOPS 1029 bool "Panic on Oops" 1030 help 1031 Say Y here to enable the kernel to panic when it oopses. This 1032 has the same effect as setting oops=panic on the kernel command 1033 line. 1034 1035 This feature is useful to ensure that the kernel does not do 1036 anything erroneous after an oops which could result in data 1037 corruption or other issues. 1038 1039 Say N if unsure. 1040 1041config PANIC_ON_OOPS_VALUE 1042 int 1043 range 0 1 1044 default 0 if !PANIC_ON_OOPS 1045 default 1 if PANIC_ON_OOPS 1046 1047config PANIC_TIMEOUT 1048 int "panic timeout" 1049 default 0 1050 help 1051 Set the timeout value (in seconds) until a reboot occurs when 1052 the kernel panics. If n = 0, then we wait forever. A timeout 1053 value n > 0 will wait n seconds before rebooting, while a timeout 1054 value n < 0 will reboot immediately. 1055 1056config LOCKUP_DETECTOR 1057 bool 1058 1059config SOFTLOCKUP_DETECTOR 1060 bool "Detect Soft Lockups" 1061 depends on DEBUG_KERNEL && !S390 1062 select LOCKUP_DETECTOR 1063 help 1064 Say Y here to enable the kernel to act as a watchdog to detect 1065 soft lockups. 1066 1067 Softlockups are bugs that cause the kernel to loop in kernel 1068 mode for more than 20 seconds, without giving other tasks a 1069 chance to run. The current stack trace is displayed upon 1070 detection and the system will stay locked up. 1071 1072config BOOTPARAM_SOFTLOCKUP_PANIC 1073 bool "Panic (Reboot) On Soft Lockups" 1074 depends on SOFTLOCKUP_DETECTOR 1075 help 1076 Say Y here to enable the kernel to panic on "soft lockups", 1077 which are bugs that cause the kernel to loop in kernel 1078 mode for more than 20 seconds (configurable using the watchdog_thresh 1079 sysctl), without giving other tasks a chance to run. 1080 1081 The panic can be used in combination with panic_timeout, 1082 to cause the system to reboot automatically after a 1083 lockup has been detected. This feature is useful for 1084 high-availability systems that have uptime guarantees and 1085 where a lockup must be resolved ASAP. 1086 1087 Say N if unsure. 1088 1089config HARDLOCKUP_DETECTOR_PERF 1090 bool 1091 select SOFTLOCKUP_DETECTOR 1092 1093# 1094# Enables a timestamp based low pass filter to compensate for perf based 1095# hard lockup detection which runs too fast due to turbo modes. 1096# 1097config HARDLOCKUP_CHECK_TIMESTAMP 1098 bool 1099 1100# 1101# arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard 1102# lockup detector rather than the perf based detector. 1103# 1104config HARDLOCKUP_DETECTOR 1105 bool "Detect Hard Lockups" 1106 depends on DEBUG_KERNEL && !S390 1107 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH 1108 select LOCKUP_DETECTOR 1109 select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF 1110 help 1111 Say Y here to enable the kernel to act as a watchdog to detect 1112 hard lockups. 1113 1114 Hardlockups are bugs that cause the CPU to loop in kernel mode 1115 for more than 10 seconds, without letting other interrupts have a 1116 chance to run. The current stack trace is displayed upon detection 1117 and the system will stay locked up. 1118 1119config BOOTPARAM_HARDLOCKUP_PANIC 1120 bool "Panic (Reboot) On Hard Lockups" 1121 depends on HARDLOCKUP_DETECTOR 1122 help 1123 Say Y here to enable the kernel to panic on "hard lockups", 1124 which are bugs that cause the kernel to loop in kernel 1125 mode with interrupts disabled for more than 10 seconds (configurable 1126 using the watchdog_thresh sysctl). 1127 1128 Say N if unsure. 1129 1130config DETECT_HUNG_TASK 1131 bool "Detect Hung Tasks" 1132 depends on DEBUG_KERNEL 1133 default SOFTLOCKUP_DETECTOR 1134 help 1135 Say Y here to enable the kernel to detect "hung tasks", 1136 which are bugs that cause the task to be stuck in 1137 uninterruptible "D" state indefinitely. 1138 1139 When a hung task is detected, the kernel will print the 1140 current stack trace (which you should report), but the 1141 task will stay in uninterruptible state. If lockdep is 1142 enabled then all held locks will also be reported. This 1143 feature has negligible overhead. 1144 1145config DEFAULT_HUNG_TASK_TIMEOUT 1146 int "Default timeout for hung task detection (in seconds)" 1147 depends on DETECT_HUNG_TASK 1148 default 120 1149 help 1150 This option controls the default timeout (in seconds) used 1151 to determine when a task has become non-responsive and should 1152 be considered hung. 1153 1154 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 1155 sysctl or by writing a value to 1156 /proc/sys/kernel/hung_task_timeout_secs. 1157 1158 A timeout of 0 disables the check. The default is two minutes. 1159 Keeping the default should be fine in most cases. 1160 1161config BOOTPARAM_HUNG_TASK_PANIC 1162 bool "Panic (Reboot) On Hung Tasks" 1163 depends on DETECT_HUNG_TASK 1164 help 1165 Say Y here to enable the kernel to panic on "hung tasks", 1166 which are bugs that cause the kernel to leave a task stuck 1167 in uninterruptible "D" state. 1168 1169 The panic can be used in combination with panic_timeout, 1170 to cause the system to reboot automatically after a 1171 hung task has been detected. This feature is useful for 1172 high-availability systems that have uptime guarantees and 1173 where a hung tasks must be resolved ASAP. 1174 1175 Say N if unsure. 1176 1177config WQ_WATCHDOG 1178 bool "Detect Workqueue Stalls" 1179 depends on DEBUG_KERNEL 1180 help 1181 Say Y here to enable stall detection on workqueues. If a 1182 worker pool doesn't make forward progress on a pending work 1183 item for over a given amount of time, 30s by default, a 1184 warning message is printed along with dump of workqueue 1185 state. This can be configured through kernel parameter 1186 "workqueue.watchdog_thresh" and its sysfs counterpart. 1187 1188config TEST_LOCKUP 1189 tristate "Test module to generate lockups" 1190 depends on m 1191 help 1192 This builds the "test_lockup" module that helps to make sure 1193 that watchdogs and lockup detectors are working properly. 1194 1195 Depending on module parameters it could emulate soft or hard 1196 lockup, "hung task", or locking arbitrary lock for a long time. 1197 Also it could generate series of lockups with cooling-down periods. 1198 1199 If unsure, say N. 1200 1201endmenu # "Debug lockups and hangs" 1202 1203menu "Scheduler Debugging" 1204 1205config SCHED_DEBUG 1206 bool "Collect scheduler debugging info" 1207 depends on DEBUG_KERNEL && PROC_FS 1208 default y 1209 help 1210 If you say Y here, the /proc/sched_debug file will be provided 1211 that can help debug the scheduler. The runtime overhead of this 1212 option is minimal. 1213 1214config SCHED_INFO 1215 bool 1216 default n 1217 1218config SCHEDSTATS 1219 bool "Collect scheduler statistics" 1220 depends on DEBUG_KERNEL && PROC_FS 1221 select SCHED_INFO 1222 help 1223 If you say Y here, additional code will be inserted into the 1224 scheduler and related routines to collect statistics about 1225 scheduler behavior and provide them in /proc/schedstat. These 1226 stats may be useful for both tuning and debugging the scheduler 1227 If you aren't debugging the scheduler or trying to tune a specific 1228 application, you can say N to avoid the very slight overhead 1229 this adds. 1230 1231endmenu 1232 1233config DEBUG_TIMEKEEPING 1234 bool "Enable extra timekeeping sanity checking" 1235 help 1236 This option will enable additional timekeeping sanity checks 1237 which may be helpful when diagnosing issues where timekeeping 1238 problems are suspected. 1239 1240 This may include checks in the timekeeping hotpaths, so this 1241 option may have a (very small) performance impact to some 1242 workloads. 1243 1244 If unsure, say N. 1245 1246config DEBUG_PREEMPT 1247 bool "Debug preemptible kernel" 1248 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1249 help 1250 If you say Y here then the kernel will use a debug variant of the 1251 commonly used smp_processor_id() function and will print warnings 1252 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1253 will detect preemption count underflows. 1254 1255 This option has potential to introduce high runtime overhead, 1256 depending on workload as it triggers debugging routines for each 1257 this_cpu operation. It should only be used for debugging purposes. 1258 1259menu "Lock Debugging (spinlocks, mutexes, etc...)" 1260 1261config LOCK_DEBUGGING_SUPPORT 1262 bool 1263 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1264 default y 1265 1266config PROVE_LOCKING 1267 bool "Lock debugging: prove locking correctness" 1268 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1269 select LOCKDEP 1270 select DEBUG_SPINLOCK 1271 select DEBUG_MUTEXES if !PREEMPT_RT 1272 select DEBUG_RT_MUTEXES if RT_MUTEXES 1273 select DEBUG_RWSEMS 1274 select DEBUG_WW_MUTEX_SLOWPATH 1275 select DEBUG_LOCK_ALLOC 1276 select PREEMPT_COUNT if !ARCH_NO_PREEMPT 1277 select TRACE_IRQFLAGS 1278 default n 1279 help 1280 This feature enables the kernel to prove that all locking 1281 that occurs in the kernel runtime is mathematically 1282 correct: that under no circumstance could an arbitrary (and 1283 not yet triggered) combination of observed locking 1284 sequences (on an arbitrary number of CPUs, running an 1285 arbitrary number of tasks and interrupt contexts) cause a 1286 deadlock. 1287 1288 In short, this feature enables the kernel to report locking 1289 related deadlocks before they actually occur. 1290 1291 The proof does not depend on how hard and complex a 1292 deadlock scenario would be to trigger: how many 1293 participant CPUs, tasks and irq-contexts would be needed 1294 for it to trigger. The proof also does not depend on 1295 timing: if a race and a resulting deadlock is possible 1296 theoretically (no matter how unlikely the race scenario 1297 is), it will be proven so and will immediately be 1298 reported by the kernel (once the event is observed that 1299 makes the deadlock theoretically possible). 1300 1301 If a deadlock is impossible (i.e. the locking rules, as 1302 observed by the kernel, are mathematically correct), the 1303 kernel reports nothing. 1304 1305 NOTE: this feature can also be enabled for rwlocks, mutexes 1306 and rwsems - in which case all dependencies between these 1307 different locking variants are observed and mapped too, and 1308 the proof of observed correctness is also maintained for an 1309 arbitrary combination of these separate locking variants. 1310 1311 For more details, see Documentation/locking/lockdep-design.rst. 1312 1313config PROVE_RAW_LOCK_NESTING 1314 bool "Enable raw_spinlock - spinlock nesting checks" 1315 depends on PROVE_LOCKING 1316 default n 1317 help 1318 Enable the raw_spinlock vs. spinlock nesting checks which ensure 1319 that the lock nesting rules for PREEMPT_RT enabled kernels are 1320 not violated. 1321 1322 NOTE: There are known nesting problems. So if you enable this 1323 option expect lockdep splats until these problems have been fully 1324 addressed which is work in progress. This config switch allows to 1325 identify and analyze these problems. It will be removed and the 1326 check permanently enabled once the main issues have been fixed. 1327 1328 If unsure, select N. 1329 1330config LOCK_STAT 1331 bool "Lock usage statistics" 1332 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1333 select LOCKDEP 1334 select DEBUG_SPINLOCK 1335 select DEBUG_MUTEXES if !PREEMPT_RT 1336 select DEBUG_RT_MUTEXES if RT_MUTEXES 1337 select DEBUG_LOCK_ALLOC 1338 default n 1339 help 1340 This feature enables tracking lock contention points 1341 1342 For more details, see Documentation/locking/lockstat.rst 1343 1344 This also enables lock events required by "perf lock", 1345 subcommand of perf. 1346 If you want to use "perf lock", you also need to turn on 1347 CONFIG_EVENT_TRACING. 1348 1349 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1350 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1351 1352config DEBUG_RT_MUTEXES 1353 bool "RT Mutex debugging, deadlock detection" 1354 depends on DEBUG_KERNEL && RT_MUTEXES 1355 help 1356 This allows rt mutex semantics violations and rt mutex related 1357 deadlocks (lockups) to be detected and reported automatically. 1358 1359config DEBUG_SPINLOCK 1360 bool "Spinlock and rw-lock debugging: basic checks" 1361 depends on DEBUG_KERNEL 1362 select UNINLINE_SPIN_UNLOCK 1363 help 1364 Say Y here and build SMP to catch missing spinlock initialization 1365 and certain other kinds of spinlock errors commonly made. This is 1366 best used in conjunction with the NMI watchdog so that spinlock 1367 deadlocks are also debuggable. 1368 1369config DEBUG_MUTEXES 1370 bool "Mutex debugging: basic checks" 1371 depends on DEBUG_KERNEL && !PREEMPT_RT 1372 help 1373 This feature allows mutex semantics violations to be detected and 1374 reported. 1375 1376config DEBUG_WW_MUTEX_SLOWPATH 1377 bool "Wait/wound mutex debugging: Slowpath testing" 1378 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1379 select DEBUG_LOCK_ALLOC 1380 select DEBUG_SPINLOCK 1381 select DEBUG_MUTEXES if !PREEMPT_RT 1382 select DEBUG_RT_MUTEXES if PREEMPT_RT 1383 help 1384 This feature enables slowpath testing for w/w mutex users by 1385 injecting additional -EDEADLK wound/backoff cases. Together with 1386 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1387 will test all possible w/w mutex interface abuse with the 1388 exception of simply not acquiring all the required locks. 1389 Note that this feature can introduce significant overhead, so 1390 it really should not be enabled in a production or distro kernel, 1391 even a debug kernel. If you are a driver writer, enable it. If 1392 you are a distro, do not. 1393 1394config DEBUG_RWSEMS 1395 bool "RW Semaphore debugging: basic checks" 1396 depends on DEBUG_KERNEL 1397 help 1398 This debugging feature allows mismatched rw semaphore locks 1399 and unlocks to be detected and reported. 1400 1401config DEBUG_LOCK_ALLOC 1402 bool "Lock debugging: detect incorrect freeing of live locks" 1403 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1404 select DEBUG_SPINLOCK 1405 select DEBUG_MUTEXES if !PREEMPT_RT 1406 select DEBUG_RT_MUTEXES if RT_MUTEXES 1407 select LOCKDEP 1408 help 1409 This feature will check whether any held lock (spinlock, rwlock, 1410 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1411 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1412 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1413 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1414 held during task exit. 1415 1416config LOCKDEP 1417 bool 1418 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1419 select STACKTRACE 1420 select KALLSYMS 1421 select KALLSYMS_ALL 1422 1423config LOCKDEP_SMALL 1424 bool 1425 1426config LOCKDEP_BITS 1427 int "Bitsize for MAX_LOCKDEP_ENTRIES" 1428 depends on LOCKDEP && !LOCKDEP_SMALL 1429 range 10 30 1430 default 15 1431 help 1432 Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message. 1433 1434config LOCKDEP_CHAINS_BITS 1435 int "Bitsize for MAX_LOCKDEP_CHAINS" 1436 depends on LOCKDEP && !LOCKDEP_SMALL 1437 range 10 30 1438 default 16 1439 help 1440 Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message. 1441 1442config LOCKDEP_STACK_TRACE_BITS 1443 int "Bitsize for MAX_STACK_TRACE_ENTRIES" 1444 depends on LOCKDEP && !LOCKDEP_SMALL 1445 range 10 30 1446 default 19 1447 help 1448 Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message. 1449 1450config LOCKDEP_STACK_TRACE_HASH_BITS 1451 int "Bitsize for STACK_TRACE_HASH_SIZE" 1452 depends on LOCKDEP && !LOCKDEP_SMALL 1453 range 10 30 1454 default 14 1455 help 1456 Try increasing this value if you need large MAX_STACK_TRACE_ENTRIES. 1457 1458config LOCKDEP_CIRCULAR_QUEUE_BITS 1459 int "Bitsize for elements in circular_queue struct" 1460 depends on LOCKDEP 1461 range 10 30 1462 default 12 1463 help 1464 Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure. 1465 1466config DEBUG_LOCKDEP 1467 bool "Lock dependency engine debugging" 1468 depends on DEBUG_KERNEL && LOCKDEP 1469 select DEBUG_IRQFLAGS 1470 help 1471 If you say Y here, the lock dependency engine will do 1472 additional runtime checks to debug itself, at the price 1473 of more runtime overhead. 1474 1475config DEBUG_ATOMIC_SLEEP 1476 bool "Sleep inside atomic section checking" 1477 select PREEMPT_COUNT 1478 depends on DEBUG_KERNEL 1479 depends on !ARCH_NO_PREEMPT 1480 help 1481 If you say Y here, various routines which may sleep will become very 1482 noisy if they are called inside atomic sections: when a spinlock is 1483 held, inside an rcu read side critical section, inside preempt disabled 1484 sections, inside an interrupt, etc... 1485 1486config DEBUG_LOCKING_API_SELFTESTS 1487 bool "Locking API boot-time self-tests" 1488 depends on DEBUG_KERNEL 1489 help 1490 Say Y here if you want the kernel to run a short self-test during 1491 bootup. The self-test checks whether common types of locking bugs 1492 are detected by debugging mechanisms or not. (if you disable 1493 lock debugging then those bugs won't be detected of course.) 1494 The following locking APIs are covered: spinlocks, rwlocks, 1495 mutexes and rwsems. 1496 1497config LOCK_TORTURE_TEST 1498 tristate "torture tests for locking" 1499 depends on DEBUG_KERNEL 1500 select TORTURE_TEST 1501 help 1502 This option provides a kernel module that runs torture tests 1503 on kernel locking primitives. The kernel module may be built 1504 after the fact on the running kernel to be tested, if desired. 1505 1506 Say Y here if you want kernel locking-primitive torture tests 1507 to be built into the kernel. 1508 Say M if you want these torture tests to build as a module. 1509 Say N if you are unsure. 1510 1511config WW_MUTEX_SELFTEST 1512 tristate "Wait/wound mutex selftests" 1513 help 1514 This option provides a kernel module that runs tests on the 1515 on the struct ww_mutex locking API. 1516 1517 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1518 with this test harness. 1519 1520 Say M if you want these self tests to build as a module. 1521 Say N if you are unsure. 1522 1523config SCF_TORTURE_TEST 1524 tristate "torture tests for smp_call_function*()" 1525 depends on DEBUG_KERNEL 1526 select TORTURE_TEST 1527 help 1528 This option provides a kernel module that runs torture tests 1529 on the smp_call_function() family of primitives. The kernel 1530 module may be built after the fact on the running kernel to 1531 be tested, if desired. 1532 1533config CSD_LOCK_WAIT_DEBUG 1534 bool "Debugging for csd_lock_wait(), called from smp_call_function*()" 1535 depends on DEBUG_KERNEL 1536 depends on 64BIT 1537 default n 1538 help 1539 This option enables debug prints when CPUs are slow to respond 1540 to the smp_call_function*() IPI wrappers. These debug prints 1541 include the IPI handler function currently executing (if any) 1542 and relevant stack traces. 1543 1544endmenu # lock debugging 1545 1546config TRACE_IRQFLAGS 1547 depends on TRACE_IRQFLAGS_SUPPORT 1548 bool 1549 help 1550 Enables hooks to interrupt enabling and disabling for 1551 either tracing or lock debugging. 1552 1553config TRACE_IRQFLAGS_NMI 1554 def_bool y 1555 depends on TRACE_IRQFLAGS 1556 depends on TRACE_IRQFLAGS_NMI_SUPPORT 1557 1558config DEBUG_IRQFLAGS 1559 bool "Debug IRQ flag manipulation" 1560 help 1561 Enables checks for potentially unsafe enabling or disabling of 1562 interrupts, such as calling raw_local_irq_restore() when interrupts 1563 are enabled. 1564 1565config STACKTRACE 1566 bool "Stack backtrace support" 1567 depends on STACKTRACE_SUPPORT 1568 help 1569 This option causes the kernel to create a /proc/pid/stack for 1570 every process, showing its current stack trace. 1571 It is also used by various kernel debugging features that require 1572 stack trace generation. 1573 1574config WARN_ALL_UNSEEDED_RANDOM 1575 bool "Warn for all uses of unseeded randomness" 1576 default n 1577 help 1578 Some parts of the kernel contain bugs relating to their use of 1579 cryptographically secure random numbers before it's actually possible 1580 to generate those numbers securely. This setting ensures that these 1581 flaws don't go unnoticed, by enabling a message, should this ever 1582 occur. This will allow people with obscure setups to know when things 1583 are going wrong, so that they might contact developers about fixing 1584 it. 1585 1586 Unfortunately, on some models of some architectures getting 1587 a fully seeded CRNG is extremely difficult, and so this can 1588 result in dmesg getting spammed for a surprisingly long 1589 time. This is really bad from a security perspective, and 1590 so architecture maintainers really need to do what they can 1591 to get the CRNG seeded sooner after the system is booted. 1592 However, since users cannot do anything actionable to 1593 address this, by default this option is disabled. 1594 1595 Say Y here if you want to receive warnings for all uses of 1596 unseeded randomness. This will be of use primarily for 1597 those developers interested in improving the security of 1598 Linux kernels running on their architecture (or 1599 subarchitecture). 1600 1601config DEBUG_KOBJECT 1602 bool "kobject debugging" 1603 depends on DEBUG_KERNEL 1604 help 1605 If you say Y here, some extra kobject debugging messages will be sent 1606 to the syslog. 1607 1608config DEBUG_KOBJECT_RELEASE 1609 bool "kobject release debugging" 1610 depends on DEBUG_OBJECTS_TIMERS 1611 help 1612 kobjects are reference counted objects. This means that their 1613 last reference count put is not predictable, and the kobject can 1614 live on past the point at which a driver decides to drop its 1615 initial reference to the kobject gained on allocation. An 1616 example of this would be a struct device which has just been 1617 unregistered. 1618 1619 However, some buggy drivers assume that after such an operation, 1620 the memory backing the kobject can be immediately freed. This 1621 goes completely against the principles of a refcounted object. 1622 1623 If you say Y here, the kernel will delay the release of kobjects 1624 on the last reference count to improve the visibility of this 1625 kind of kobject release bug. 1626 1627config HAVE_DEBUG_BUGVERBOSE 1628 bool 1629 1630menu "Debug kernel data structures" 1631 1632config DEBUG_LIST 1633 bool "Debug linked list manipulation" 1634 depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION 1635 help 1636 Enable this to turn on extended checks in the linked-list 1637 walking routines. 1638 1639 If unsure, say N. 1640 1641config DEBUG_PLIST 1642 bool "Debug priority linked list manipulation" 1643 depends on DEBUG_KERNEL 1644 help 1645 Enable this to turn on extended checks in the priority-ordered 1646 linked-list (plist) walking routines. This checks the entire 1647 list multiple times during each manipulation. 1648 1649 If unsure, say N. 1650 1651config DEBUG_SG 1652 bool "Debug SG table operations" 1653 depends on DEBUG_KERNEL 1654 help 1655 Enable this to turn on checks on scatter-gather tables. This can 1656 help find problems with drivers that do not properly initialize 1657 their sg tables. 1658 1659 If unsure, say N. 1660 1661config DEBUG_NOTIFIERS 1662 bool "Debug notifier call chains" 1663 depends on DEBUG_KERNEL 1664 help 1665 Enable this to turn on sanity checking for notifier call chains. 1666 This is most useful for kernel developers to make sure that 1667 modules properly unregister themselves from notifier chains. 1668 This is a relatively cheap check but if you care about maximum 1669 performance, say N. 1670 1671config BUG_ON_DATA_CORRUPTION 1672 bool "Trigger a BUG when data corruption is detected" 1673 select DEBUG_LIST 1674 help 1675 Select this option if the kernel should BUG when it encounters 1676 data corruption in kernel memory structures when they get checked 1677 for validity. 1678 1679 If unsure, say N. 1680 1681config DEBUG_MAPLE_TREE 1682 bool "Debug maple trees" 1683 depends on DEBUG_KERNEL 1684 help 1685 Enable maple tree debugging information and extra validations. 1686 1687 If unsure, say N. 1688 1689endmenu 1690 1691config DEBUG_CREDENTIALS 1692 bool "Debug credential management" 1693 depends on DEBUG_KERNEL 1694 help 1695 Enable this to turn on some debug checking for credential 1696 management. The additional code keeps track of the number of 1697 pointers from task_structs to any given cred struct, and checks to 1698 see that this number never exceeds the usage count of the cred 1699 struct. 1700 1701 Furthermore, if SELinux is enabled, this also checks that the 1702 security pointer in the cred struct is never seen to be invalid. 1703 1704 If unsure, say N. 1705 1706source "kernel/rcu/Kconfig.debug" 1707 1708config DEBUG_WQ_FORCE_RR_CPU 1709 bool "Force round-robin CPU selection for unbound work items" 1710 depends on DEBUG_KERNEL 1711 default n 1712 help 1713 Workqueue used to implicitly guarantee that work items queued 1714 without explicit CPU specified are put on the local CPU. This 1715 guarantee is no longer true and while local CPU is still 1716 preferred work items may be put on foreign CPUs. Kernel 1717 parameter "workqueue.debug_force_rr_cpu" is added to force 1718 round-robin CPU selection to flush out usages which depend on the 1719 now broken guarantee. This config option enables the debug 1720 feature by default. When enabled, memory and cache locality will 1721 be impacted. 1722 1723config CPU_HOTPLUG_STATE_CONTROL 1724 bool "Enable CPU hotplug state control" 1725 depends on DEBUG_KERNEL 1726 depends on HOTPLUG_CPU 1727 default n 1728 help 1729 Allows to write steps between "offline" and "online" to the CPUs 1730 sysfs target file so states can be stepped granular. This is a debug 1731 option for now as the hotplug machinery cannot be stopped and 1732 restarted at arbitrary points yet. 1733 1734 Say N if your are unsure. 1735 1736config LATENCYTOP 1737 bool "Latency measuring infrastructure" 1738 depends on DEBUG_KERNEL 1739 depends on STACKTRACE_SUPPORT 1740 depends on PROC_FS 1741 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 1742 select KALLSYMS 1743 select KALLSYMS_ALL 1744 select STACKTRACE 1745 select SCHEDSTATS 1746 help 1747 Enable this option if you want to use the LatencyTOP tool 1748 to find out which userspace is blocking on what kernel operations. 1749 1750config DEBUG_CGROUP_REF 1751 bool "Disable inlining of cgroup css reference count functions" 1752 depends on DEBUG_KERNEL 1753 depends on CGROUPS 1754 depends on KPROBES 1755 default n 1756 help 1757 Force cgroup css reference count functions to not be inlined so 1758 that they can be kprobed for debugging. 1759 1760source "kernel/trace/Kconfig" 1761 1762config PROVIDE_OHCI1394_DMA_INIT 1763 bool "Remote debugging over FireWire early on boot" 1764 depends on PCI && X86 1765 help 1766 If you want to debug problems which hang or crash the kernel early 1767 on boot and the crashing machine has a FireWire port, you can use 1768 this feature to remotely access the memory of the crashed machine 1769 over FireWire. This employs remote DMA as part of the OHCI1394 1770 specification which is now the standard for FireWire controllers. 1771 1772 With remote DMA, you can monitor the printk buffer remotely using 1773 firescope and access all memory below 4GB using fireproxy from gdb. 1774 Even controlling a kernel debugger is possible using remote DMA. 1775 1776 Usage: 1777 1778 If ohci1394_dma=early is used as boot parameter, it will initialize 1779 all OHCI1394 controllers which are found in the PCI config space. 1780 1781 As all changes to the FireWire bus such as enabling and disabling 1782 devices cause a bus reset and thereby disable remote DMA for all 1783 devices, be sure to have the cable plugged and FireWire enabled on 1784 the debugging host before booting the debug target for debugging. 1785 1786 This code (~1k) is freed after boot. By then, the firewire stack 1787 in charge of the OHCI-1394 controllers should be used instead. 1788 1789 See Documentation/core-api/debugging-via-ohci1394.rst for more information. 1790 1791source "samples/Kconfig" 1792 1793config ARCH_HAS_DEVMEM_IS_ALLOWED 1794 bool 1795 1796config STRICT_DEVMEM 1797 bool "Filter access to /dev/mem" 1798 depends on MMU && DEVMEM 1799 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED 1800 default y if PPC || X86 || ARM64 1801 help 1802 If this option is disabled, you allow userspace (root) access to all 1803 of memory, including kernel and userspace memory. Accidental 1804 access to this is obviously disastrous, but specific access can 1805 be used by people debugging the kernel. Note that with PAT support 1806 enabled, even in this case there are restrictions on /dev/mem 1807 use due to the cache aliasing requirements. 1808 1809 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 1810 file only allows userspace access to PCI space and the BIOS code and 1811 data regions. This is sufficient for dosemu and X and all common 1812 users of /dev/mem. 1813 1814 If in doubt, say Y. 1815 1816config IO_STRICT_DEVMEM 1817 bool "Filter I/O access to /dev/mem" 1818 depends on STRICT_DEVMEM 1819 help 1820 If this option is disabled, you allow userspace (root) access to all 1821 io-memory regardless of whether a driver is actively using that 1822 range. Accidental access to this is obviously disastrous, but 1823 specific access can be used by people debugging kernel drivers. 1824 1825 If this option is switched on, the /dev/mem file only allows 1826 userspace access to *idle* io-memory ranges (see /proc/iomem) This 1827 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 1828 if the driver using a given range cannot be disabled. 1829 1830 If in doubt, say Y. 1831 1832menu "$(SRCARCH) Debugging" 1833 1834source "arch/$(SRCARCH)/Kconfig.debug" 1835 1836endmenu 1837 1838menu "Kernel Testing and Coverage" 1839 1840source "lib/kunit/Kconfig" 1841 1842config NOTIFIER_ERROR_INJECTION 1843 tristate "Notifier error injection" 1844 depends on DEBUG_KERNEL 1845 select DEBUG_FS 1846 help 1847 This option provides the ability to inject artificial errors to 1848 specified notifier chain callbacks. It is useful to test the error 1849 handling of notifier call chain failures. 1850 1851 Say N if unsure. 1852 1853config PM_NOTIFIER_ERROR_INJECT 1854 tristate "PM notifier error injection module" 1855 depends on PM && NOTIFIER_ERROR_INJECTION 1856 default m if PM_DEBUG 1857 help 1858 This option provides the ability to inject artificial errors to 1859 PM notifier chain callbacks. It is controlled through debugfs 1860 interface /sys/kernel/debug/notifier-error-inject/pm 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 PM suspend error (-12 = -ENOMEM) 1866 1867 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1868 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1869 # echo mem > /sys/power/state 1870 bash: echo: write error: Cannot allocate memory 1871 1872 To compile this code as a module, choose M here: the module will 1873 be called pm-notifier-error-inject. 1874 1875 If unsure, say N. 1876 1877config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1878 tristate "OF reconfig notifier error injection module" 1879 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1880 help 1881 This option provides the ability to inject artificial errors to 1882 OF reconfig notifier chain callbacks. It is controlled 1883 through debugfs interface under 1884 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1885 1886 If the notifier call chain should be failed with some events 1887 notified, write the error code to "actions/<notifier event>/error". 1888 1889 To compile this code as a module, choose M here: the module will 1890 be called of-reconfig-notifier-error-inject. 1891 1892 If unsure, say N. 1893 1894config NETDEV_NOTIFIER_ERROR_INJECT 1895 tristate "Netdev notifier error injection module" 1896 depends on NET && NOTIFIER_ERROR_INJECTION 1897 help 1898 This option provides the ability to inject artificial errors to 1899 netdevice notifier chain callbacks. It is controlled through debugfs 1900 interface /sys/kernel/debug/notifier-error-inject/netdev 1901 1902 If the notifier call chain should be failed with some events 1903 notified, write the error code to "actions/<notifier event>/error". 1904 1905 Example: Inject netdevice mtu change error (-22 = -EINVAL) 1906 1907 # cd /sys/kernel/debug/notifier-error-inject/netdev 1908 # echo -22 > actions/NETDEV_CHANGEMTU/error 1909 # ip link set eth0 mtu 1024 1910 RTNETLINK answers: Invalid argument 1911 1912 To compile this code as a module, choose M here: the module will 1913 be called netdev-notifier-error-inject. 1914 1915 If unsure, say N. 1916 1917config FUNCTION_ERROR_INJECTION 1918 bool "Fault-injections of functions" 1919 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 1920 help 1921 Add fault injections into various functions that are annotated with 1922 ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return 1923 value of theses functions. This is useful to test error paths of code. 1924 1925 If unsure, say N 1926 1927config FAULT_INJECTION 1928 bool "Fault-injection framework" 1929 depends on DEBUG_KERNEL 1930 help 1931 Provide fault-injection framework. 1932 For more details, see Documentation/fault-injection/. 1933 1934config FAILSLAB 1935 bool "Fault-injection capability for kmalloc" 1936 depends on FAULT_INJECTION 1937 depends on SLAB || SLUB 1938 help 1939 Provide fault-injection capability for kmalloc. 1940 1941config FAIL_PAGE_ALLOC 1942 bool "Fault-injection capability for alloc_pages()" 1943 depends on FAULT_INJECTION 1944 help 1945 Provide fault-injection capability for alloc_pages(). 1946 1947config FAULT_INJECTION_USERCOPY 1948 bool "Fault injection capability for usercopy functions" 1949 depends on FAULT_INJECTION 1950 help 1951 Provides fault-injection capability to inject failures 1952 in usercopy functions (copy_from_user(), get_user(), ...). 1953 1954config FAIL_MAKE_REQUEST 1955 bool "Fault-injection capability for disk IO" 1956 depends on FAULT_INJECTION && BLOCK 1957 help 1958 Provide fault-injection capability for disk IO. 1959 1960config FAIL_IO_TIMEOUT 1961 bool "Fault-injection capability for faking disk interrupts" 1962 depends on FAULT_INJECTION && BLOCK 1963 help 1964 Provide fault-injection capability on end IO handling. This 1965 will make the block layer "forget" an interrupt as configured, 1966 thus exercising the error handling. 1967 1968 Only works with drivers that use the generic timeout handling, 1969 for others it won't do anything. 1970 1971config FAIL_FUTEX 1972 bool "Fault-injection capability for futexes" 1973 select DEBUG_FS 1974 depends on FAULT_INJECTION && FUTEX 1975 help 1976 Provide fault-injection capability for futexes. 1977 1978config FAULT_INJECTION_DEBUG_FS 1979 bool "Debugfs entries for fault-injection capabilities" 1980 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 1981 help 1982 Enable configuration of fault-injection capabilities via debugfs. 1983 1984config FAIL_FUNCTION 1985 bool "Fault-injection capability for functions" 1986 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 1987 help 1988 Provide function-based fault-injection capability. 1989 This will allow you to override a specific function with a return 1990 with given return value. As a result, function caller will see 1991 an error value and have to handle it. This is useful to test the 1992 error handling in various subsystems. 1993 1994config FAIL_MMC_REQUEST 1995 bool "Fault-injection capability for MMC IO" 1996 depends on FAULT_INJECTION_DEBUG_FS && MMC 1997 help 1998 Provide fault-injection capability for MMC IO. 1999 This will make the mmc core return data errors. This is 2000 useful to test the error handling in the mmc block device 2001 and to test how the mmc host driver handles retries from 2002 the block device. 2003 2004config FAIL_SUNRPC 2005 bool "Fault-injection capability for SunRPC" 2006 depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG 2007 help 2008 Provide fault-injection capability for SunRPC and 2009 its consumers. 2010 2011config FAULT_INJECTION_STACKTRACE_FILTER 2012 bool "stacktrace filter for fault-injection capabilities" 2013 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 2014 select STACKTRACE 2015 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 2016 help 2017 Provide stacktrace filter for fault-injection capabilities 2018 2019config ARCH_HAS_KCOV 2020 bool 2021 help 2022 An architecture should select this when it can successfully 2023 build and run with CONFIG_KCOV. This typically requires 2024 disabling instrumentation for some early boot code. 2025 2026config CC_HAS_SANCOV_TRACE_PC 2027 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 2028 2029 2030config KCOV 2031 bool "Code coverage for fuzzing" 2032 depends on ARCH_HAS_KCOV 2033 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 2034 depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \ 2035 GCC_VERSION >= 120000 || CLANG_VERSION >= 130000 2036 select DEBUG_FS 2037 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 2038 select OBJTOOL if HAVE_NOINSTR_HACK 2039 help 2040 KCOV exposes kernel code coverage information in a form suitable 2041 for coverage-guided fuzzing (randomized testing). 2042 2043 If RANDOMIZE_BASE is enabled, PC values will not be stable across 2044 different machines and across reboots. If you need stable PC values, 2045 disable RANDOMIZE_BASE. 2046 2047 For more details, see Documentation/dev-tools/kcov.rst. 2048 2049config KCOV_ENABLE_COMPARISONS 2050 bool "Enable comparison operands collection by KCOV" 2051 depends on KCOV 2052 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 2053 help 2054 KCOV also exposes operands of every comparison in the instrumented 2055 code along with operand sizes and PCs of the comparison instructions. 2056 These operands can be used by fuzzing engines to improve the quality 2057 of fuzzing coverage. 2058 2059config KCOV_INSTRUMENT_ALL 2060 bool "Instrument all code by default" 2061 depends on KCOV 2062 default y 2063 help 2064 If you are doing generic system call fuzzing (like e.g. syzkaller), 2065 then you will want to instrument the whole kernel and you should 2066 say y here. If you are doing more targeted fuzzing (like e.g. 2067 filesystem fuzzing with AFL) then you will want to enable coverage 2068 for more specific subsets of files, and should say n here. 2069 2070config KCOV_IRQ_AREA_SIZE 2071 hex "Size of interrupt coverage collection area in words" 2072 depends on KCOV 2073 default 0x40000 2074 help 2075 KCOV uses preallocated per-cpu areas to collect coverage from 2076 soft interrupts. This specifies the size of those areas in the 2077 number of unsigned long words. 2078 2079menuconfig RUNTIME_TESTING_MENU 2080 bool "Runtime Testing" 2081 def_bool y 2082 2083if RUNTIME_TESTING_MENU 2084 2085config TEST_DHRY 2086 tristate "Dhrystone benchmark test" 2087 help 2088 Enable this to include the Dhrystone 2.1 benchmark. This test 2089 calculates the number of Dhrystones per second, and the number of 2090 DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided 2091 by 1757 (the number of Dhrystones per second obtained on the VAX 2092 11/780, nominally a 1 MIPS machine). 2093 2094 To run the benchmark, it needs to be enabled explicitly, either from 2095 the kernel command line (when built-in), or from userspace (when 2096 built-in or modular. 2097 2098 Run once during kernel boot: 2099 2100 test_dhry.run 2101 2102 Set number of iterations from kernel command line: 2103 2104 test_dhry.iterations=<n> 2105 2106 Set number of iterations from userspace: 2107 2108 echo <n> > /sys/module/test_dhry/parameters/iterations 2109 2110 Trigger manual run from userspace: 2111 2112 echo y > /sys/module/test_dhry/parameters/run 2113 2114 If the number of iterations is <= 0, the test will devise a suitable 2115 number of iterations (test runs for at least 2s) automatically. 2116 This process takes ca. 4s. 2117 2118 If unsure, say N. 2119 2120config LKDTM 2121 tristate "Linux Kernel Dump Test Tool Module" 2122 depends on DEBUG_FS 2123 help 2124 This module enables testing of the different dumping mechanisms by 2125 inducing system failures at predefined crash points. 2126 If you don't need it: say N 2127 Choose M here to compile this code as a module. The module will be 2128 called lkdtm. 2129 2130 Documentation on how to use the module can be found in 2131 Documentation/fault-injection/provoke-crashes.rst 2132 2133config CPUMASK_KUNIT_TEST 2134 tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS 2135 depends on KUNIT 2136 default KUNIT_ALL_TESTS 2137 help 2138 Enable to turn on cpumask tests, running at boot or module load time. 2139 2140 For more information on KUnit and unit tests in general, please refer 2141 to the KUnit documentation in Documentation/dev-tools/kunit/. 2142 2143 If unsure, say N. 2144 2145config TEST_LIST_SORT 2146 tristate "Linked list sorting test" if !KUNIT_ALL_TESTS 2147 depends on KUNIT 2148 default KUNIT_ALL_TESTS 2149 help 2150 Enable this to turn on 'list_sort()' function test. This test is 2151 executed only once during system boot (so affects only boot time), 2152 or at module load time. 2153 2154 If unsure, say N. 2155 2156config TEST_MIN_HEAP 2157 tristate "Min heap test" 2158 depends on DEBUG_KERNEL || m 2159 help 2160 Enable this to turn on min heap function tests. This test is 2161 executed only once during system boot (so affects only boot time), 2162 or at module load time. 2163 2164 If unsure, say N. 2165 2166config TEST_SORT 2167 tristate "Array-based sort test" if !KUNIT_ALL_TESTS 2168 depends on KUNIT 2169 default KUNIT_ALL_TESTS 2170 help 2171 This option enables the self-test function of 'sort()' at boot, 2172 or at module load time. 2173 2174 If unsure, say N. 2175 2176config TEST_DIV64 2177 tristate "64bit/32bit division and modulo test" 2178 depends on DEBUG_KERNEL || m 2179 help 2180 Enable this to turn on 'do_div()' function test. This test is 2181 executed only once during system boot (so affects only boot time), 2182 or at module load time. 2183 2184 If unsure, say N. 2185 2186config KPROBES_SANITY_TEST 2187 tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS 2188 depends on DEBUG_KERNEL 2189 depends on KPROBES 2190 depends on KUNIT 2191 select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 2192 default KUNIT_ALL_TESTS 2193 help 2194 This option provides for testing basic kprobes functionality on 2195 boot. Samples of kprobe and kretprobe are inserted and 2196 verified for functionality. 2197 2198 Say N if you are unsure. 2199 2200config FPROBE_SANITY_TEST 2201 bool "Self test for fprobe" 2202 depends on DEBUG_KERNEL 2203 depends on FPROBE 2204 depends on KUNIT=y 2205 help 2206 This option will enable testing the fprobe when the system boot. 2207 A series of tests are made to verify that the fprobe is functioning 2208 properly. 2209 2210 Say N if you are unsure. 2211 2212config BACKTRACE_SELF_TEST 2213 tristate "Self test for the backtrace code" 2214 depends on DEBUG_KERNEL 2215 help 2216 This option provides a kernel module that can be used to test 2217 the kernel stack backtrace code. This option is not useful 2218 for distributions or general kernels, but only for kernel 2219 developers working on architecture code. 2220 2221 Note that if you want to also test saved backtraces, you will 2222 have to enable STACKTRACE as well. 2223 2224 Say N if you are unsure. 2225 2226config TEST_REF_TRACKER 2227 tristate "Self test for reference tracker" 2228 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT 2229 select REF_TRACKER 2230 help 2231 This option provides a kernel module performing tests 2232 using reference tracker infrastructure. 2233 2234 Say N if you are unsure. 2235 2236config RBTREE_TEST 2237 tristate "Red-Black tree test" 2238 depends on DEBUG_KERNEL 2239 help 2240 A benchmark measuring the performance of the rbtree library. 2241 Also includes rbtree invariant checks. 2242 2243config REED_SOLOMON_TEST 2244 tristate "Reed-Solomon library test" 2245 depends on DEBUG_KERNEL || m 2246 select REED_SOLOMON 2247 select REED_SOLOMON_ENC16 2248 select REED_SOLOMON_DEC16 2249 help 2250 This option enables the self-test function of rslib at boot, 2251 or at module load time. 2252 2253 If unsure, say N. 2254 2255config INTERVAL_TREE_TEST 2256 tristate "Interval tree test" 2257 depends on DEBUG_KERNEL 2258 select INTERVAL_TREE 2259 help 2260 A benchmark measuring the performance of the interval tree library 2261 2262config PERCPU_TEST 2263 tristate "Per cpu operations test" 2264 depends on m && DEBUG_KERNEL 2265 help 2266 Enable this option to build test module which validates per-cpu 2267 operations. 2268 2269 If unsure, say N. 2270 2271config ATOMIC64_SELFTEST 2272 tristate "Perform an atomic64_t self-test" 2273 help 2274 Enable this option to test the atomic64_t functions at boot or 2275 at module load time. 2276 2277 If unsure, say N. 2278 2279config ASYNC_RAID6_TEST 2280 tristate "Self test for hardware accelerated raid6 recovery" 2281 depends on ASYNC_RAID6_RECOV 2282 select ASYNC_MEMCPY 2283 help 2284 This is a one-shot self test that permutes through the 2285 recovery of all the possible two disk failure scenarios for a 2286 N-disk array. Recovery is performed with the asynchronous 2287 raid6 recovery routines, and will optionally use an offload 2288 engine if one is available. 2289 2290 If unsure, say N. 2291 2292config TEST_HEXDUMP 2293 tristate "Test functions located in the hexdump module at runtime" 2294 2295config STRING_SELFTEST 2296 tristate "Test string functions at runtime" 2297 2298config TEST_STRING_HELPERS 2299 tristate "Test functions located in the string_helpers module at runtime" 2300 2301config TEST_KSTRTOX 2302 tristate "Test kstrto*() family of functions at runtime" 2303 2304config TEST_PRINTF 2305 tristate "Test printf() family of functions at runtime" 2306 2307config TEST_SCANF 2308 tristate "Test scanf() family of functions at runtime" 2309 2310config TEST_BITMAP 2311 tristate "Test bitmap_*() family of functions at runtime" 2312 help 2313 Enable this option to test the bitmap functions at boot. 2314 2315 If unsure, say N. 2316 2317config TEST_UUID 2318 tristate "Test functions located in the uuid module at runtime" 2319 2320config TEST_XARRAY 2321 tristate "Test the XArray code at runtime" 2322 2323config TEST_MAPLE_TREE 2324 depends on DEBUG_KERNEL 2325 select DEBUG_MAPLE_TREE 2326 tristate "Test the Maple Tree code at runtime" 2327 2328config TEST_RHASHTABLE 2329 tristate "Perform selftest on resizable hash table" 2330 help 2331 Enable this option to test the rhashtable functions at boot. 2332 2333 If unsure, say N. 2334 2335config TEST_IDA 2336 tristate "Perform selftest on IDA functions" 2337 2338config TEST_PARMAN 2339 tristate "Perform selftest on priority array manager" 2340 depends on PARMAN 2341 help 2342 Enable this option to test priority array manager on boot 2343 (or module load). 2344 2345 If unsure, say N. 2346 2347config TEST_IRQ_TIMINGS 2348 bool "IRQ timings selftest" 2349 depends on IRQ_TIMINGS 2350 help 2351 Enable this option to test the irq timings code on boot. 2352 2353 If unsure, say N. 2354 2355config TEST_LKM 2356 tristate "Test module loading with 'hello world' module" 2357 depends on m 2358 help 2359 This builds the "test_module" module that emits "Hello, world" 2360 on printk when loaded. It is designed to be used for basic 2361 evaluation of the module loading subsystem (for example when 2362 validating module verification). It lacks any extra dependencies, 2363 and will not normally be loaded by the system unless explicitly 2364 requested by name. 2365 2366 If unsure, say N. 2367 2368config TEST_BITOPS 2369 tristate "Test module for compilation of bitops operations" 2370 depends on m 2371 help 2372 This builds the "test_bitops" module that is much like the 2373 TEST_LKM module except that it does a basic exercise of the 2374 set/clear_bit macros and get_count_order/long to make sure there are 2375 no compiler warnings from C=1 sparse checker or -Wextra 2376 compilations. It has no dependencies and doesn't run or load unless 2377 explicitly requested by name. for example: modprobe test_bitops. 2378 2379 If unsure, say N. 2380 2381config TEST_VMALLOC 2382 tristate "Test module for stress/performance analysis of vmalloc allocator" 2383 default n 2384 depends on MMU 2385 depends on m 2386 help 2387 This builds the "test_vmalloc" module that should be used for 2388 stress and performance analysis. So, any new change for vmalloc 2389 subsystem can be evaluated from performance and stability point 2390 of view. 2391 2392 If unsure, say N. 2393 2394config TEST_USER_COPY 2395 tristate "Test user/kernel boundary protections" 2396 depends on m 2397 help 2398 This builds the "test_user_copy" module that runs sanity checks 2399 on the copy_to/from_user infrastructure, making sure basic 2400 user/kernel boundary testing is working. If it fails to load, 2401 a regression has been detected in the user/kernel memory boundary 2402 protections. 2403 2404 If unsure, say N. 2405 2406config TEST_BPF 2407 tristate "Test BPF filter functionality" 2408 depends on m && NET 2409 help 2410 This builds the "test_bpf" module that runs various test vectors 2411 against the BPF interpreter or BPF JIT compiler depending on the 2412 current setting. This is in particular useful for BPF JIT compiler 2413 development, but also to run regression tests against changes in 2414 the interpreter code. It also enables test stubs for eBPF maps and 2415 verifier used by user space verifier testsuite. 2416 2417 If unsure, say N. 2418 2419config TEST_BLACKHOLE_DEV 2420 tristate "Test blackhole netdev functionality" 2421 depends on m && NET 2422 help 2423 This builds the "test_blackhole_dev" module that validates the 2424 data path through this blackhole netdev. 2425 2426 If unsure, say N. 2427 2428config FIND_BIT_BENCHMARK 2429 tristate "Test find_bit functions" 2430 help 2431 This builds the "test_find_bit" module that measure find_*_bit() 2432 functions performance. 2433 2434 If unsure, say N. 2435 2436config TEST_FIRMWARE 2437 tristate "Test firmware loading via userspace interface" 2438 depends on FW_LOADER 2439 help 2440 This builds the "test_firmware" module that creates a userspace 2441 interface for testing firmware loading. This can be used to 2442 control the triggering of firmware loading without needing an 2443 actual firmware-using device. The contents can be rechecked by 2444 userspace. 2445 2446 If unsure, say N. 2447 2448config TEST_SYSCTL 2449 tristate "sysctl test driver" 2450 depends on PROC_SYSCTL 2451 help 2452 This builds the "test_sysctl" module. This driver enables to test the 2453 proc sysctl interfaces available to drivers safely without affecting 2454 production knobs which might alter system functionality. 2455 2456 If unsure, say N. 2457 2458config BITFIELD_KUNIT 2459 tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS 2460 depends on KUNIT 2461 default KUNIT_ALL_TESTS 2462 help 2463 Enable this option to test the bitfield functions at boot. 2464 2465 KUnit tests run during boot and output the results to the debug log 2466 in TAP format (http://testanything.org/). Only useful for kernel devs 2467 running the KUnit test harness, and not intended for inclusion into a 2468 production build. 2469 2470 For more information on KUnit and unit tests in general please refer 2471 to the KUnit documentation in Documentation/dev-tools/kunit/. 2472 2473 If unsure, say N. 2474 2475config HASH_KUNIT_TEST 2476 tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS 2477 depends on KUNIT 2478 default KUNIT_ALL_TESTS 2479 help 2480 Enable this option to test the kernel's string (<linux/stringhash.h>), and 2481 integer (<linux/hash.h>) hash functions on boot. 2482 2483 KUnit tests run during boot and output the results to the debug log 2484 in TAP format (https://testanything.org/). Only useful for kernel devs 2485 running the KUnit test harness, and not intended for inclusion into a 2486 production build. 2487 2488 For more information on KUnit and unit tests in general please refer 2489 to the KUnit documentation in Documentation/dev-tools/kunit/. 2490 2491 This is intended to help people writing architecture-specific 2492 optimized versions. If unsure, say N. 2493 2494config RESOURCE_KUNIT_TEST 2495 tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS 2496 depends on KUNIT 2497 default KUNIT_ALL_TESTS 2498 help 2499 This builds the resource API unit test. 2500 Tests the logic of API provided by resource.c and ioport.h. 2501 For more information on KUnit and unit tests in general please refer 2502 to the KUnit documentation in Documentation/dev-tools/kunit/. 2503 2504 If unsure, say N. 2505 2506config SYSCTL_KUNIT_TEST 2507 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS 2508 depends on KUNIT 2509 default KUNIT_ALL_TESTS 2510 help 2511 This builds the proc sysctl unit test, which runs on boot. 2512 Tests the API contract and implementation correctness of sysctl. 2513 For more information on KUnit and unit tests in general please refer 2514 to the KUnit documentation in Documentation/dev-tools/kunit/. 2515 2516 If unsure, say N. 2517 2518config LIST_KUNIT_TEST 2519 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS 2520 depends on KUNIT 2521 default KUNIT_ALL_TESTS 2522 help 2523 This builds the linked list KUnit test suite. 2524 It tests that the API and basic functionality of the list_head type 2525 and associated macros. 2526 2527 KUnit tests run during boot and output the results to the debug log 2528 in TAP format (https://testanything.org/). Only useful for kernel devs 2529 running the KUnit test harness, and not intended for inclusion into a 2530 production build. 2531 2532 For more information on KUnit and unit tests in general please refer 2533 to the KUnit documentation in Documentation/dev-tools/kunit/. 2534 2535 If unsure, say N. 2536 2537config LINEAR_RANGES_TEST 2538 tristate "KUnit test for linear_ranges" 2539 depends on KUNIT 2540 select LINEAR_RANGES 2541 help 2542 This builds the linear_ranges unit test, which runs on boot. 2543 Tests the linear_ranges logic correctness. 2544 For more information on KUnit and unit tests in general please refer 2545 to the KUnit documentation in Documentation/dev-tools/kunit/. 2546 2547 If unsure, say N. 2548 2549config CMDLINE_KUNIT_TEST 2550 tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS 2551 depends on KUNIT 2552 default KUNIT_ALL_TESTS 2553 help 2554 This builds the cmdline API unit test. 2555 Tests the logic of API provided by cmdline.c. 2556 For more information on KUnit and unit tests in general please refer 2557 to the KUnit documentation in Documentation/dev-tools/kunit/. 2558 2559 If unsure, say N. 2560 2561config BITS_TEST 2562 tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS 2563 depends on KUNIT 2564 default KUNIT_ALL_TESTS 2565 help 2566 This builds the bits unit test. 2567 Tests the logic of macros defined in bits.h. 2568 For more information on KUnit and unit tests in general please refer 2569 to the KUnit documentation in Documentation/dev-tools/kunit/. 2570 2571 If unsure, say N. 2572 2573config SLUB_KUNIT_TEST 2574 tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS 2575 depends on SLUB_DEBUG && KUNIT 2576 default KUNIT_ALL_TESTS 2577 help 2578 This builds SLUB allocator unit test. 2579 Tests SLUB cache debugging functionality. 2580 For more information on KUnit and unit tests in general please refer 2581 to the KUnit documentation in Documentation/dev-tools/kunit/. 2582 2583 If unsure, say N. 2584 2585config RATIONAL_KUNIT_TEST 2586 tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS 2587 depends on KUNIT && RATIONAL 2588 default KUNIT_ALL_TESTS 2589 help 2590 This builds the rational math unit test. 2591 For more information on KUnit and unit tests in general please refer 2592 to the KUnit documentation in Documentation/dev-tools/kunit/. 2593 2594 If unsure, say N. 2595 2596config MEMCPY_KUNIT_TEST 2597 tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS 2598 depends on KUNIT 2599 default KUNIT_ALL_TESTS 2600 help 2601 Builds unit tests for memcpy(), memmove(), and memset() functions. 2602 For more information on KUnit and unit tests in general please refer 2603 to the KUnit documentation in Documentation/dev-tools/kunit/. 2604 2605 If unsure, say N. 2606 2607config IS_SIGNED_TYPE_KUNIT_TEST 2608 tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS 2609 depends on KUNIT 2610 default KUNIT_ALL_TESTS 2611 help 2612 Builds unit tests for the is_signed_type() macro. 2613 2614 For more information on KUnit and unit tests in general please refer 2615 to the KUnit documentation in Documentation/dev-tools/kunit/. 2616 2617 If unsure, say N. 2618 2619config OVERFLOW_KUNIT_TEST 2620 tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS 2621 depends on KUNIT 2622 default KUNIT_ALL_TESTS 2623 help 2624 Builds unit tests for the check_*_overflow(), size_*(), allocation, and 2625 related functions. 2626 2627 For more information on KUnit and unit tests in general please refer 2628 to the KUnit documentation in Documentation/dev-tools/kunit/. 2629 2630 If unsure, say N. 2631 2632config STACKINIT_KUNIT_TEST 2633 tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS 2634 depends on KUNIT 2635 default KUNIT_ALL_TESTS 2636 help 2637 Test if the kernel is zero-initializing stack variables and 2638 padding. Coverage is controlled by compiler flags, 2639 CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO, 2640 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2641 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2642 2643config FORTIFY_KUNIT_TEST 2644 tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS 2645 depends on KUNIT && FORTIFY_SOURCE 2646 default KUNIT_ALL_TESTS 2647 help 2648 Builds unit tests for checking internals of FORTIFY_SOURCE as used 2649 by the str*() and mem*() family of functions. For testing runtime 2650 traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests. 2651 2652config HW_BREAKPOINT_KUNIT_TEST 2653 bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS 2654 depends on HAVE_HW_BREAKPOINT 2655 depends on KUNIT=y 2656 default KUNIT_ALL_TESTS 2657 help 2658 Tests for hw_breakpoint constraints accounting. 2659 2660 If unsure, say N. 2661 2662config STRSCPY_KUNIT_TEST 2663 tristate "Test strscpy*() family of functions at runtime" if !KUNIT_ALL_TESTS 2664 depends on KUNIT 2665 default KUNIT_ALL_TESTS 2666 2667config SIPHASH_KUNIT_TEST 2668 tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS 2669 depends on KUNIT 2670 default KUNIT_ALL_TESTS 2671 help 2672 Enable this option to test the kernel's siphash (<linux/siphash.h>) hash 2673 functions on boot (or module load). 2674 2675 This is intended to help people writing architecture-specific 2676 optimized versions. If unsure, say N. 2677 2678config TEST_UDELAY 2679 tristate "udelay test driver" 2680 help 2681 This builds the "udelay_test" module that helps to make sure 2682 that udelay() is working properly. 2683 2684 If unsure, say N. 2685 2686config TEST_STATIC_KEYS 2687 tristate "Test static keys" 2688 depends on m 2689 help 2690 Test the static key interfaces. 2691 2692 If unsure, say N. 2693 2694config TEST_DYNAMIC_DEBUG 2695 tristate "Test DYNAMIC_DEBUG" 2696 depends on DYNAMIC_DEBUG 2697 help 2698 This module registers a tracer callback to count enabled 2699 pr_debugs in a 'do_debugging' function, then alters their 2700 enablements, calls the function, and compares counts. 2701 2702 If unsure, say N. 2703 2704config TEST_KMOD 2705 tristate "kmod stress tester" 2706 depends on m 2707 depends on NETDEVICES && NET_CORE && INET # for TUN 2708 depends on BLOCK 2709 depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS 2710 select TEST_LKM 2711 select XFS_FS 2712 select TUN 2713 select BTRFS_FS 2714 help 2715 Test the kernel's module loading mechanism: kmod. kmod implements 2716 support to load modules using the Linux kernel's usermode helper. 2717 This test provides a series of tests against kmod. 2718 2719 Although technically you can either build test_kmod as a module or 2720 into the kernel we disallow building it into the kernel since 2721 it stress tests request_module() and this will very likely cause 2722 some issues by taking over precious threads available from other 2723 module load requests, ultimately this could be fatal. 2724 2725 To run tests run: 2726 2727 tools/testing/selftests/kmod/kmod.sh --help 2728 2729 If unsure, say N. 2730 2731config TEST_DEBUG_VIRTUAL 2732 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 2733 depends on DEBUG_VIRTUAL 2734 help 2735 Test the kernel's ability to detect incorrect calls to 2736 virt_to_phys() done against the non-linear part of the 2737 kernel's virtual address map. 2738 2739 If unsure, say N. 2740 2741config TEST_MEMCAT_P 2742 tristate "Test memcat_p() helper function" 2743 help 2744 Test the memcat_p() helper for correctly merging two 2745 pointer arrays together. 2746 2747 If unsure, say N. 2748 2749config TEST_LIVEPATCH 2750 tristate "Test livepatching" 2751 default n 2752 depends on DYNAMIC_DEBUG 2753 depends on LIVEPATCH 2754 depends on m 2755 help 2756 Test kernel livepatching features for correctness. The tests will 2757 load test modules that will be livepatched in various scenarios. 2758 2759 To run all the livepatching tests: 2760 2761 make -C tools/testing/selftests TARGETS=livepatch run_tests 2762 2763 Alternatively, individual tests may be invoked: 2764 2765 tools/testing/selftests/livepatch/test-callbacks.sh 2766 tools/testing/selftests/livepatch/test-livepatch.sh 2767 tools/testing/selftests/livepatch/test-shadow-vars.sh 2768 2769 If unsure, say N. 2770 2771config TEST_OBJAGG 2772 tristate "Perform selftest on object aggreration manager" 2773 default n 2774 depends on OBJAGG 2775 help 2776 Enable this option to test object aggregation manager on boot 2777 (or module load). 2778 2779config TEST_MEMINIT 2780 tristate "Test heap/page initialization" 2781 help 2782 Test if the kernel is zero-initializing heap and page allocations. 2783 This can be useful to test init_on_alloc and init_on_free features. 2784 2785 If unsure, say N. 2786 2787config TEST_HMM 2788 tristate "Test HMM (Heterogeneous Memory Management)" 2789 depends on TRANSPARENT_HUGEPAGE 2790 depends on DEVICE_PRIVATE 2791 select HMM_MIRROR 2792 select MMU_NOTIFIER 2793 help 2794 This is a pseudo device driver solely for testing HMM. 2795 Say M here if you want to build the HMM test module. 2796 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests. 2797 2798 If unsure, say N. 2799 2800config TEST_FREE_PAGES 2801 tristate "Test freeing pages" 2802 help 2803 Test that a memory leak does not occur due to a race between 2804 freeing a block of pages and a speculative page reference. 2805 Loading this module is safe if your kernel has the bug fixed. 2806 If the bug is not fixed, it will leak gigabytes of memory and 2807 probably OOM your system. 2808 2809config TEST_FPU 2810 tristate "Test floating point operations in kernel space" 2811 depends on X86 && !KCOV_INSTRUMENT_ALL 2812 help 2813 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu 2814 which will trigger a sequence of floating point operations. This is used 2815 for self-testing floating point control register setting in 2816 kernel_fpu_begin(). 2817 2818 If unsure, say N. 2819 2820config TEST_CLOCKSOURCE_WATCHDOG 2821 tristate "Test clocksource watchdog in kernel space" 2822 depends on CLOCKSOURCE_WATCHDOG 2823 help 2824 Enable this option to create a kernel module that will trigger 2825 a test of the clocksource watchdog. This module may be loaded 2826 via modprobe or insmod in which case it will run upon being 2827 loaded, or it may be built in, in which case it will run 2828 shortly after boot. 2829 2830 If unsure, say N. 2831 2832endif # RUNTIME_TESTING_MENU 2833 2834config ARCH_USE_MEMTEST 2835 bool 2836 help 2837 An architecture should select this when it uses early_memtest() 2838 during boot process. 2839 2840config MEMTEST 2841 bool "Memtest" 2842 depends on ARCH_USE_MEMTEST 2843 help 2844 This option adds a kernel parameter 'memtest', which allows memtest 2845 to be set and executed. 2846 memtest=0, mean disabled; -- default 2847 memtest=1, mean do 1 test pattern; 2848 ... 2849 memtest=17, mean do 17 test patterns. 2850 If you are unsure how to answer this question, answer N. 2851 2852 2853 2854config HYPERV_TESTING 2855 bool "Microsoft Hyper-V driver testing" 2856 default n 2857 depends on HYPERV && DEBUG_FS 2858 help 2859 Select this option to enable Hyper-V vmbus testing. 2860 2861endmenu # "Kernel Testing and Coverage" 2862 2863menu "Rust hacking" 2864 2865config RUST_DEBUG_ASSERTIONS 2866 bool "Debug assertions" 2867 depends on RUST 2868 help 2869 Enables rustc's `-Cdebug-assertions` codegen option. 2870 2871 This flag lets you turn `cfg(debug_assertions)` conditional 2872 compilation on or off. This can be used to enable extra debugging 2873 code in development but not in production. For example, it controls 2874 the behavior of the standard library's `debug_assert!` macro. 2875 2876 Note that this will apply to all Rust code, including `core`. 2877 2878 If unsure, say N. 2879 2880config RUST_OVERFLOW_CHECKS 2881 bool "Overflow checks" 2882 default y 2883 depends on RUST 2884 help 2885 Enables rustc's `-Coverflow-checks` codegen option. 2886 2887 This flag allows you to control the behavior of runtime integer 2888 overflow. When overflow-checks are enabled, a Rust panic will occur 2889 on overflow. 2890 2891 Note that this will apply to all Rust code, including `core`. 2892 2893 If unsure, say Y. 2894 2895config RUST_BUILD_ASSERT_ALLOW 2896 bool "Allow unoptimized build-time assertions" 2897 depends on RUST 2898 help 2899 Controls how are `build_error!` and `build_assert!` handled during build. 2900 2901 If calls to them exist in the binary, it may indicate a violated invariant 2902 or that the optimizer failed to verify the invariant during compilation. 2903 2904 This should not happen, thus by default the build is aborted. However, 2905 as an escape hatch, you can choose Y here to ignore them during build 2906 and let the check be carried at runtime (with `panic!` being called if 2907 the check fails). 2908 2909 If unsure, say N. 2910 2911endmenu # "Rust" 2912 2913source "Documentation/Kconfig" 2914 2915endmenu # Kernel hacking 2916