1# SPDX-License-Identifier: GPL-2.0-only 2menu "Kernel hacking" 3 4menu "printk and dmesg options" 5 6config PRINTK_TIME 7 bool "Show timing information on printks" 8 depends on PRINTK 9 help 10 Selecting this option causes time stamps of the printk() 11 messages to be added to the output of the syslog() system 12 call and at the console. 13 14 The timestamp is always recorded internally, and exported 15 to /dev/kmsg. This flag just specifies if the timestamp should 16 be included, not that the timestamp is recorded. 17 18 The behavior is also controlled by the kernel command line 19 parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst 20 21config PRINTK_CALLER 22 bool "Show caller information on printks" 23 depends on PRINTK 24 help 25 Selecting this option causes printk() to add a caller "thread id" (if 26 in task context) or a caller "processor id" (if not in task context) 27 to every message. 28 29 This option is intended for environments where multiple threads 30 concurrently call printk() for many times, for it is difficult to 31 interpret without knowing where these lines (or sometimes individual 32 line which was divided into multiple lines due to race) came from. 33 34 Since toggling after boot makes the code racy, currently there is 35 no option to enable/disable at the kernel command line parameter or 36 sysfs interface. 37 38config STACKTRACE_BUILD_ID 39 bool "Show build ID information in stacktraces" 40 depends on PRINTK 41 help 42 Selecting this option adds build ID information for symbols in 43 stacktraces printed with the printk format '%p[SR]b'. 44 45 This option is intended for distros where debuginfo is not easily 46 accessible but can be downloaded given the build ID of the vmlinux or 47 kernel module where the function is located. 48 49config CONSOLE_LOGLEVEL_DEFAULT 50 int "Default console loglevel (1-15)" 51 range 1 15 52 default "7" 53 help 54 Default loglevel to determine what will be printed on the console. 55 56 Setting a default here is equivalent to passing in loglevel=<x> in 57 the kernel bootargs. loglevel=<x> continues to override whatever 58 value is specified here as well. 59 60 Note: This does not affect the log level of un-prefixed printk() 61 usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT 62 option. 63 64config CONSOLE_LOGLEVEL_QUIET 65 int "quiet console loglevel (1-15)" 66 range 1 15 67 default "4" 68 help 69 loglevel to use when "quiet" is passed on the kernel commandline. 70 71 When "quiet" is passed on the kernel commandline this loglevel 72 will be used as the loglevel. IOW passing "quiet" will be the 73 equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>" 74 75config MESSAGE_LOGLEVEL_DEFAULT 76 int "Default message log level (1-7)" 77 range 1 7 78 default "4" 79 help 80 Default log level for printk statements with no specified priority. 81 82 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks 83 that are auditing their logs closely may want to set it to a lower 84 priority. 85 86 Note: This does not affect what message level gets printed on the console 87 by default. To change that, use loglevel=<x> in the kernel bootargs, 88 or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value. 89 90config BOOT_PRINTK_DELAY 91 bool "Delay each boot printk message by N milliseconds" 92 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY 93 help 94 This build option allows you to read kernel boot messages 95 by inserting a short delay after each one. The delay is 96 specified in milliseconds on the kernel command line, 97 using "boot_delay=N". 98 99 It is likely that you would also need to use "lpj=M" to preset 100 the "loops per jiffie" value. 101 See a previous boot log for the "lpj" value to use for your 102 system, and then set "lpj=M" before setting "boot_delay=N". 103 NOTE: Using this option may adversely affect SMP systems. 104 I.e., processors other than the first one may not boot up. 105 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect 106 what it believes to be lockup conditions. 107 108config DYNAMIC_DEBUG 109 bool "Enable dynamic printk() support" 110 default n 111 depends on PRINTK 112 depends on (DEBUG_FS || PROC_FS) 113 select DYNAMIC_DEBUG_CORE 114 help 115 116 Compiles debug level messages into the kernel, which would not 117 otherwise be available at runtime. These messages can then be 118 enabled/disabled based on various levels of scope - per source file, 119 function, module, format string, and line number. This mechanism 120 implicitly compiles in all pr_debug() and dev_dbg() calls, which 121 enlarges the kernel text size by about 2%. 122 123 If a source file is compiled with DEBUG flag set, any 124 pr_debug() calls in it are enabled by default, but can be 125 disabled at runtime as below. Note that DEBUG flag is 126 turned on by many CONFIG_*DEBUG* options. 127 128 Usage: 129 130 Dynamic debugging is controlled via the 'dynamic_debug/control' file, 131 which is contained in the 'debugfs' filesystem or procfs. 132 Thus, the debugfs or procfs filesystem must first be mounted before 133 making use of this feature. 134 We refer the control file as: <debugfs>/dynamic_debug/control. This 135 file contains a list of the debug statements that can be enabled. The 136 format for each line of the file is: 137 138 filename:lineno [module]function flags format 139 140 filename : source file of the debug statement 141 lineno : line number of the debug statement 142 module : module that contains the debug statement 143 function : function that contains the debug statement 144 flags : '=p' means the line is turned 'on' for printing 145 format : the format used for the debug statement 146 147 From a live system: 148 149 nullarbor:~ # cat <debugfs>/dynamic_debug/control 150 # filename:lineno [module]function flags format 151 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012" 152 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012" 153 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012" 154 155 Example usage: 156 157 // enable the message at line 1603 of file svcsock.c 158 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' > 159 <debugfs>/dynamic_debug/control 160 161 // enable all the messages in file svcsock.c 162 nullarbor:~ # echo -n 'file svcsock.c +p' > 163 <debugfs>/dynamic_debug/control 164 165 // enable all the messages in the NFS server module 166 nullarbor:~ # echo -n 'module nfsd +p' > 167 <debugfs>/dynamic_debug/control 168 169 // enable all 12 messages in the function svc_process() 170 nullarbor:~ # echo -n 'func svc_process +p' > 171 <debugfs>/dynamic_debug/control 172 173 // disable all 12 messages in the function svc_process() 174 nullarbor:~ # echo -n 'func svc_process -p' > 175 <debugfs>/dynamic_debug/control 176 177 See Documentation/admin-guide/dynamic-debug-howto.rst for additional 178 information. 179 180config DYNAMIC_DEBUG_CORE 181 bool "Enable core function of dynamic debug support" 182 depends on PRINTK 183 depends on (DEBUG_FS || PROC_FS) 184 help 185 Enable core functional support of dynamic debug. It is useful 186 when you want to tie dynamic debug to your kernel modules with 187 DYNAMIC_DEBUG_MODULE defined for each of them, especially for 188 the case of embedded system where the kernel image size is 189 sensitive for people. 190 191config SYMBOLIC_ERRNAME 192 bool "Support symbolic error names in printf" 193 default y if PRINTK 194 help 195 If you say Y here, the kernel's printf implementation will 196 be able to print symbolic error names such as ENOSPC instead 197 of the number 28. It makes the kernel image slightly larger 198 (about 3KB), but can make the kernel logs easier to read. 199 200config DEBUG_BUGVERBOSE 201 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT 202 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE) 203 default y 204 help 205 Say Y here to make BUG() panics output the file name and line number 206 of the BUG call as well as the EIP and oops trace. This aids 207 debugging but costs about 70-100K of memory. 208 209endmenu # "printk and dmesg options" 210 211config DEBUG_KERNEL 212 bool "Kernel debugging" 213 help 214 Say Y here if you are developing drivers or trying to debug and 215 identify kernel problems. 216 217config DEBUG_MISC 218 bool "Miscellaneous debug code" 219 default DEBUG_KERNEL 220 depends on DEBUG_KERNEL 221 help 222 Say Y here if you need to enable miscellaneous debug code that should 223 be under a more specific debug option but isn't. 224 225menu "Compile-time checks and compiler options" 226 227config DEBUG_INFO 228 bool 229 help 230 A kernel debug info option other than "None" has been selected 231 in the "Debug information" choice below, indicating that debug 232 information will be generated for build targets. 233 234# Clang is known to generate .{s,u}leb128 with symbol deltas with DWARF5, which 235# some targets may not support: https://sourceware.org/bugzilla/show_bug.cgi?id=27215 236config AS_HAS_NON_CONST_LEB128 237 def_bool $(as-instr,.uleb128 .Lexpr_end4 - .Lexpr_start3\n.Lexpr_start3:\n.Lexpr_end4:) 238 239choice 240 prompt "Debug information" 241 depends on DEBUG_KERNEL 242 help 243 Selecting something other than "None" results in a kernel image 244 that will include debugging info resulting in a larger kernel image. 245 This adds debug symbols to the kernel and modules (gcc -g), and 246 is needed if you intend to use kernel crashdump or binary object 247 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 248 249 Choose which version of DWARF debug info to emit. If unsure, 250 select "Toolchain default". 251 252config DEBUG_INFO_NONE 253 bool "Disable debug information" 254 help 255 Do not build the kernel with debugging information, which will 256 result in a faster and smaller build. 257 258config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT 259 bool "Rely on the toolchain's implicit default DWARF version" 260 select DEBUG_INFO 261 depends on !CC_IS_CLANG || AS_IS_LLVM || CLANG_VERSION < 140000 || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_LEB128) 262 help 263 The implicit default version of DWARF debug info produced by a 264 toolchain changes over time. 265 266 This can break consumers of the debug info that haven't upgraded to 267 support newer revisions, and prevent testing newer versions, but 268 those should be less common scenarios. 269 270config DEBUG_INFO_DWARF4 271 bool "Generate DWARF Version 4 debuginfo" 272 select DEBUG_INFO 273 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502) 274 help 275 Generate DWARF v4 debug info. This requires gcc 4.5+, binutils 2.35.2 276 if using clang without clang's integrated assembler, and gdb 7.0+. 277 278 If you have consumers of DWARF debug info that are not ready for 279 newer revisions of DWARF, you may wish to choose this or have your 280 config select this. 281 282config DEBUG_INFO_DWARF5 283 bool "Generate DWARF Version 5 debuginfo" 284 select DEBUG_INFO 285 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_LEB128) 286 help 287 Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc 288 5.0+ accepts the -gdwarf-5 flag but only had partial support for some 289 draft features until 7.0), and gdb 8.0+. 290 291 Changes to the structure of debug info in Version 5 allow for around 292 15-18% savings in resulting image and debug info section sizes as 293 compared to DWARF Version 4. DWARF Version 5 standardizes previous 294 extensions such as accelerators for symbol indexing and the format 295 for fission (.dwo/.dwp) files. Users may not want to select this 296 config if they rely on tooling that has not yet been updated to 297 support DWARF Version 5. 298 299endchoice # "Debug information" 300 301if DEBUG_INFO 302 303config DEBUG_INFO_REDUCED 304 bool "Reduce debugging information" 305 help 306 If you say Y here gcc is instructed to generate less debugging 307 information for structure types. This means that tools that 308 need full debugging information (like kgdb or systemtap) won't 309 be happy. But if you merely need debugging information to 310 resolve line numbers there is no loss. Advantage is that 311 build directory object sizes shrink dramatically over a full 312 DEBUG_INFO build and compile times are reduced too. 313 Only works with newer gcc versions. 314 315choice 316 prompt "Compressed Debug information" 317 help 318 Compress the resulting debug info. Results in smaller debug info sections, 319 but requires that consumers are able to decompress the results. 320 321 If unsure, choose DEBUG_INFO_COMPRESSED_NONE. 322 323config DEBUG_INFO_COMPRESSED_NONE 324 bool "Don't compress debug information" 325 help 326 Don't compress debug info sections. 327 328config DEBUG_INFO_COMPRESSED_ZLIB 329 bool "Compress debugging information with zlib" 330 depends on $(cc-option,-gz=zlib) 331 depends on $(ld-option,--compress-debug-sections=zlib) 332 help 333 Compress the debug information using zlib. Requires GCC 5.0+ or Clang 334 5.0+, binutils 2.26+, and zlib. 335 336 Users of dpkg-deb via scripts/package/builddeb may find an increase in 337 size of their debug .deb packages with this config set, due to the 338 debug info being compressed with zlib, then the object files being 339 recompressed with a different compression scheme. But this is still 340 preferable to setting $KDEB_COMPRESS to "none" which would be even 341 larger. 342 343config DEBUG_INFO_COMPRESSED_ZSTD 344 bool "Compress debugging information with zstd" 345 depends on $(cc-option,-gz=zstd) 346 depends on $(ld-option,--compress-debug-sections=zstd) 347 help 348 Compress the debug information using zstd. This may provide better 349 compression than zlib, for about the same time costs, but requires newer 350 toolchain support. Requires GCC 13.0+ or Clang 16.0+, binutils 2.40+, and 351 zstd. 352 353endchoice # "Compressed Debug information" 354 355config DEBUG_INFO_SPLIT 356 bool "Produce split debuginfo in .dwo files" 357 depends on $(cc-option,-gsplit-dwarf) 358 help 359 Generate debug info into separate .dwo files. This significantly 360 reduces the build directory size for builds with DEBUG_INFO, 361 because it stores the information only once on disk in .dwo 362 files instead of multiple times in object files and executables. 363 In addition the debug information is also compressed. 364 365 Requires recent gcc (4.7+) and recent gdb/binutils. 366 Any tool that packages or reads debug information would need 367 to know about the .dwo files and include them. 368 Incompatible with older versions of ccache. 369 370config DEBUG_INFO_BTF 371 bool "Generate BTF typeinfo" 372 depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED 373 depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST 374 depends on BPF_SYSCALL 375 depends on !DEBUG_INFO_DWARF5 || PAHOLE_VERSION >= 121 376 help 377 Generate deduplicated BTF type information from DWARF debug info. 378 Turning this on expects presence of pahole tool, which will convert 379 DWARF type info into equivalent deduplicated BTF type info. 380 381config PAHOLE_HAS_SPLIT_BTF 382 def_bool PAHOLE_VERSION >= 119 383 384config PAHOLE_HAS_BTF_TAG 385 def_bool PAHOLE_VERSION >= 123 386 depends on CC_IS_CLANG 387 help 388 Decide whether pahole emits btf_tag attributes (btf_type_tag and 389 btf_decl_tag) or not. Currently only clang compiler implements 390 these attributes, so make the config depend on CC_IS_CLANG. 391 392config PAHOLE_HAS_LANG_EXCLUDE 393 def_bool PAHOLE_VERSION >= 124 394 help 395 Support for the --lang_exclude flag which makes pahole exclude 396 compilation units from the supplied language. Used in Kbuild to 397 omit Rust CUs which are not supported in version 1.24 of pahole, 398 otherwise it would emit malformed kernel and module binaries when 399 using DEBUG_INFO_BTF_MODULES. 400 401config DEBUG_INFO_BTF_MODULES 402 def_bool y 403 depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF 404 help 405 Generate compact split BTF type information for kernel modules. 406 407config MODULE_ALLOW_BTF_MISMATCH 408 bool "Allow loading modules with non-matching BTF type info" 409 depends on DEBUG_INFO_BTF_MODULES 410 help 411 For modules whose split BTF does not match vmlinux, load without 412 BTF rather than refusing to load. The default behavior with 413 module BTF enabled is to reject modules with such mismatches; 414 this option will still load module BTF where possible but ignore 415 it when a mismatch is found. 416 417config GDB_SCRIPTS 418 bool "Provide GDB scripts for kernel debugging" 419 help 420 This creates the required links to GDB helper scripts in the 421 build directory. If you load vmlinux into gdb, the helper 422 scripts will be automatically imported by gdb as well, and 423 additional functions are available to analyze a Linux kernel 424 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst 425 for further details. 426 427endif # DEBUG_INFO 428 429config FRAME_WARN 430 int "Warn for stack frames larger than" 431 range 0 8192 432 default 0 if KMSAN 433 default 2048 if GCC_PLUGIN_LATENT_ENTROPY 434 default 2048 if PARISC 435 default 1536 if (!64BIT && XTENSA) 436 default 1280 if KASAN && !64BIT 437 default 1024 if !64BIT 438 default 2048 if 64BIT 439 help 440 Tell the compiler to warn at build time for stack frames larger than this. 441 Setting this too low will cause a lot of warnings. 442 Setting it to 0 disables the warning. 443 444config STRIP_ASM_SYMS 445 bool "Strip assembler-generated symbols during link" 446 default n 447 help 448 Strip internal assembler-generated symbols during a link (symbols 449 that look like '.Lxxx') so they don't pollute the output of 450 get_wchan() and suchlike. 451 452config READABLE_ASM 453 bool "Generate readable assembler code" 454 depends on DEBUG_KERNEL 455 depends on CC_IS_GCC 456 help 457 Disable some compiler optimizations that tend to generate human unreadable 458 assembler output. This may make the kernel slightly slower, but it helps 459 to keep kernel developers who have to stare a lot at assembler listings 460 sane. 461 462config HEADERS_INSTALL 463 bool "Install uapi headers to usr/include" 464 depends on !UML 465 help 466 This option will install uapi headers (headers exported to user-space) 467 into the usr/include directory for use during the kernel build. 468 This is unneeded for building the kernel itself, but needed for some 469 user-space program samples. It is also needed by some features such 470 as uapi header sanity checks. 471 472config DEBUG_SECTION_MISMATCH 473 bool "Enable full Section mismatch analysis" 474 depends on CC_IS_GCC 475 help 476 The section mismatch analysis checks if there are illegal 477 references from one section to another section. 478 During linktime or runtime, some sections are dropped; 479 any use of code/data previously in these sections would 480 most likely result in an oops. 481 In the code, functions and variables are annotated with 482 __init,, etc. (see the full list in include/linux/init.h), 483 which results in the code/data being placed in specific sections. 484 The section mismatch analysis is always performed after a full 485 kernel build, and enabling this option causes the following 486 additional step to occur: 487 - Add the option -fno-inline-functions-called-once to gcc commands. 488 When inlining a function annotated with __init in a non-init 489 function, we would lose the section information and thus 490 the analysis would not catch the illegal reference. 491 This option tells gcc to inline less (but it does result in 492 a larger kernel). 493 494config SECTION_MISMATCH_WARN_ONLY 495 bool "Make section mismatch errors non-fatal" 496 default y 497 help 498 If you say N here, the build process will fail if there are any 499 section mismatch, instead of just throwing warnings. 500 501 If unsure, say Y. 502 503config DEBUG_FORCE_FUNCTION_ALIGN_64B 504 bool "Force all function address 64B aligned" 505 depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC || S390) 506 select FUNCTION_ALIGNMENT_64B 507 help 508 There are cases that a commit from one domain changes the function 509 address alignment of other domains, and cause magic performance 510 bump (regression or improvement). Enable this option will help to 511 verify if the bump is caused by function alignment changes, while 512 it will slightly increase the kernel size and affect icache usage. 513 514 It is mainly for debug and performance tuning use. 515 516# 517# Select this config option from the architecture Kconfig, if it 518# is preferred to always offer frame pointers as a config 519# option on the architecture (regardless of KERNEL_DEBUG): 520# 521config ARCH_WANT_FRAME_POINTERS 522 bool 523 524config FRAME_POINTER 525 bool "Compile the kernel with frame pointers" 526 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS 527 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 528 help 529 If you say Y here the resulting kernel image will be slightly 530 larger and slower, but it gives very useful debugging information 531 in case of kernel bugs. (precise oopses/stacktraces/warnings) 532 533config OBJTOOL 534 bool 535 536config STACK_VALIDATION 537 bool "Compile-time stack metadata validation" 538 depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER 539 select OBJTOOL 540 default n 541 help 542 Validate frame pointer rules at compile-time. This helps ensure that 543 runtime stack traces are more reliable. 544 545 For more information, see 546 tools/objtool/Documentation/objtool.txt. 547 548config NOINSTR_VALIDATION 549 bool 550 depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY 551 select OBJTOOL 552 default y 553 554config VMLINUX_MAP 555 bool "Generate vmlinux.map file when linking" 556 depends on EXPERT 557 help 558 Selecting this option will pass "-Map=vmlinux.map" to ld 559 when linking vmlinux. That file can be useful for verifying 560 and debugging magic section games, and for seeing which 561 pieces of code get eliminated with 562 CONFIG_LD_DEAD_CODE_DATA_ELIMINATION. 563 564config DEBUG_FORCE_WEAK_PER_CPU 565 bool "Force weak per-cpu definitions" 566 depends on DEBUG_KERNEL 567 help 568 s390 and alpha require percpu variables in modules to be 569 defined weak to work around addressing range issue which 570 puts the following two restrictions on percpu variable 571 definitions. 572 573 1. percpu symbols must be unique whether static or not 574 2. percpu variables can't be defined inside a function 575 576 To ensure that generic code follows the above rules, this 577 option forces all percpu variables to be defined as weak. 578 579endmenu # "Compiler options" 580 581menu "Generic Kernel Debugging Instruments" 582 583config MAGIC_SYSRQ 584 bool "Magic SysRq key" 585 depends on !UML 586 help 587 If you say Y here, you will have some control over the system even 588 if the system crashes for example during kernel debugging (e.g., you 589 will be able to flush the buffer cache to disk, reboot the system 590 immediately or dump some status information). This is accomplished 591 by pressing various keys while holding SysRq (Alt+PrintScreen). It 592 also works on a serial console (on PC hardware at least), if you 593 send a BREAK and then within 5 seconds a command keypress. The 594 keys are documented in <file:Documentation/admin-guide/sysrq.rst>. 595 Don't say Y unless you really know what this hack does. 596 597config MAGIC_SYSRQ_DEFAULT_ENABLE 598 hex "Enable magic SysRq key functions by default" 599 depends on MAGIC_SYSRQ 600 default 0x1 601 help 602 Specifies which SysRq key functions are enabled by default. 603 This may be set to 1 or 0 to enable or disable them all, or 604 to a bitmask as described in Documentation/admin-guide/sysrq.rst. 605 606config MAGIC_SYSRQ_SERIAL 607 bool "Enable magic SysRq key over serial" 608 depends on MAGIC_SYSRQ 609 default y 610 help 611 Many embedded boards have a disconnected TTL level serial which can 612 generate some garbage that can lead to spurious false sysrq detects. 613 This option allows you to decide whether you want to enable the 614 magic SysRq key. 615 616config MAGIC_SYSRQ_SERIAL_SEQUENCE 617 string "Char sequence that enables magic SysRq over serial" 618 depends on MAGIC_SYSRQ_SERIAL 619 default "" 620 help 621 Specifies a sequence of characters that can follow BREAK to enable 622 SysRq on a serial console. 623 624 If unsure, leave an empty string and the option will not be enabled. 625 626config DEBUG_FS 627 bool "Debug Filesystem" 628 help 629 debugfs is a virtual file system that kernel developers use to put 630 debugging files into. Enable this option to be able to read and 631 write to these files. 632 633 For detailed documentation on the debugfs API, see 634 Documentation/filesystems/. 635 636 If unsure, say N. 637 638choice 639 prompt "Debugfs default access" 640 depends on DEBUG_FS 641 default DEBUG_FS_ALLOW_ALL 642 help 643 This selects the default access restrictions for debugfs. 644 It can be overridden with kernel command line option 645 debugfs=[on,no-mount,off]. The restrictions apply for API access 646 and filesystem registration. 647 648config DEBUG_FS_ALLOW_ALL 649 bool "Access normal" 650 help 651 No restrictions apply. Both API and filesystem registration 652 is on. This is the normal default operation. 653 654config DEBUG_FS_DISALLOW_MOUNT 655 bool "Do not register debugfs as filesystem" 656 help 657 The API is open but filesystem is not loaded. Clients can still do 658 their work and read with debug tools that do not need 659 debugfs filesystem. 660 661config DEBUG_FS_ALLOW_NONE 662 bool "No access" 663 help 664 Access is off. Clients get -PERM when trying to create nodes in 665 debugfs tree and debugfs is not registered as a filesystem. 666 Client can then back-off or continue without debugfs access. 667 668endchoice 669 670source "lib/Kconfig.kgdb" 671source "lib/Kconfig.ubsan" 672source "lib/Kconfig.kcsan" 673 674endmenu 675 676menu "Networking Debugging" 677 678source "net/Kconfig.debug" 679 680endmenu # "Networking Debugging" 681 682menu "Memory Debugging" 683 684source "mm/Kconfig.debug" 685 686config DEBUG_OBJECTS 687 bool "Debug object operations" 688 depends on DEBUG_KERNEL 689 help 690 If you say Y here, additional code will be inserted into the 691 kernel to track the life time of various objects and validate 692 the operations on those objects. 693 694config DEBUG_OBJECTS_SELFTEST 695 bool "Debug objects selftest" 696 depends on DEBUG_OBJECTS 697 help 698 This enables the selftest of the object debug code. 699 700config DEBUG_OBJECTS_FREE 701 bool "Debug objects in freed memory" 702 depends on DEBUG_OBJECTS 703 help 704 This enables checks whether a k/v free operation frees an area 705 which contains an object which has not been deactivated 706 properly. This can make kmalloc/kfree-intensive workloads 707 much slower. 708 709config DEBUG_OBJECTS_TIMERS 710 bool "Debug timer objects" 711 depends on DEBUG_OBJECTS 712 help 713 If you say Y here, additional code will be inserted into the 714 timer routines to track the life time of timer objects and 715 validate the timer operations. 716 717config DEBUG_OBJECTS_WORK 718 bool "Debug work objects" 719 depends on DEBUG_OBJECTS 720 help 721 If you say Y here, additional code will be inserted into the 722 work queue routines to track the life time of work objects and 723 validate the work operations. 724 725config DEBUG_OBJECTS_RCU_HEAD 726 bool "Debug RCU callbacks objects" 727 depends on DEBUG_OBJECTS 728 help 729 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 730 731config DEBUG_OBJECTS_PERCPU_COUNTER 732 bool "Debug percpu counter objects" 733 depends on DEBUG_OBJECTS 734 help 735 If you say Y here, additional code will be inserted into the 736 percpu counter routines to track the life time of percpu counter 737 objects and validate the percpu counter operations. 738 739config DEBUG_OBJECTS_ENABLE_DEFAULT 740 int "debug_objects bootup default value (0-1)" 741 range 0 1 742 default "1" 743 depends on DEBUG_OBJECTS 744 help 745 Debug objects boot parameter default value 746 747config SHRINKER_DEBUG 748 bool "Enable shrinker debugging support" 749 depends on DEBUG_FS 750 help 751 Say Y to enable the shrinker debugfs interface which provides 752 visibility into the kernel memory shrinkers subsystem. 753 Disable it to avoid an extra memory footprint. 754 755config DEBUG_STACK_USAGE 756 bool "Stack utilization instrumentation" 757 depends on DEBUG_KERNEL && !IA64 758 help 759 Enables the display of the minimum amount of free stack which each 760 task has ever had available in the sysrq-T and sysrq-P debug output. 761 762 This option will slow down process creation somewhat. 763 764config SCHED_STACK_END_CHECK 765 bool "Detect stack corruption on calls to schedule()" 766 depends on DEBUG_KERNEL 767 default n 768 help 769 This option checks for a stack overrun on calls to schedule(). 770 If the stack end location is found to be over written always panic as 771 the content of the corrupted region can no longer be trusted. 772 This is to ensure no erroneous behaviour occurs which could result in 773 data corruption or a sporadic crash at a later stage once the region 774 is examined. The runtime overhead introduced is minimal. 775 776config ARCH_HAS_DEBUG_VM_PGTABLE 777 bool 778 help 779 An architecture should select this when it can successfully 780 build and run DEBUG_VM_PGTABLE. 781 782config DEBUG_VM_IRQSOFF 783 def_bool DEBUG_VM && !PREEMPT_RT 784 785config DEBUG_VM 786 bool "Debug VM" 787 depends on DEBUG_KERNEL 788 help 789 Enable this to turn on extended checks in the virtual-memory system 790 that may impact performance. 791 792 If unsure, say N. 793 794config DEBUG_VM_SHOOT_LAZIES 795 bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation" 796 depends on DEBUG_VM 797 depends on MMU_LAZY_TLB_SHOOTDOWN 798 help 799 Enable additional IPIs that ensure lazy tlb mm references are removed 800 before the mm is freed. 801 802 If unsure, say N. 803 804config DEBUG_VM_MAPLE_TREE 805 bool "Debug VM maple trees" 806 depends on DEBUG_VM 807 select DEBUG_MAPLE_TREE 808 help 809 Enable VM maple tree debugging information and extra validations. 810 811 If unsure, say N. 812 813config DEBUG_VM_RB 814 bool "Debug VM red-black trees" 815 depends on DEBUG_VM 816 help 817 Enable VM red-black tree debugging information and extra validations. 818 819 If unsure, say N. 820 821config DEBUG_VM_PGFLAGS 822 bool "Debug page-flags operations" 823 depends on DEBUG_VM 824 help 825 Enables extra validation on page flags operations. 826 827 If unsure, say N. 828 829config DEBUG_VM_PGTABLE 830 bool "Debug arch page table for semantics compliance" 831 depends on MMU 832 depends on ARCH_HAS_DEBUG_VM_PGTABLE 833 default y if DEBUG_VM 834 help 835 This option provides a debug method which can be used to test 836 architecture page table helper functions on various platforms in 837 verifying if they comply with expected generic MM semantics. This 838 will help architecture code in making sure that any changes or 839 new additions of these helpers still conform to expected 840 semantics of the generic MM. Platforms will have to opt in for 841 this through ARCH_HAS_DEBUG_VM_PGTABLE. 842 843 If unsure, say N. 844 845config ARCH_HAS_DEBUG_VIRTUAL 846 bool 847 848config DEBUG_VIRTUAL 849 bool "Debug VM translations" 850 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL 851 help 852 Enable some costly sanity checks in virtual to page code. This can 853 catch mistakes with virt_to_page() and friends. 854 855 If unsure, say N. 856 857config DEBUG_NOMMU_REGIONS 858 bool "Debug the global anon/private NOMMU mapping region tree" 859 depends on DEBUG_KERNEL && !MMU 860 help 861 This option causes the global tree of anonymous and private mapping 862 regions to be regularly checked for invalid topology. 863 864config DEBUG_MEMORY_INIT 865 bool "Debug memory initialisation" if EXPERT 866 default !EXPERT 867 help 868 Enable this for additional checks during memory initialisation. 869 The sanity checks verify aspects of the VM such as the memory model 870 and other information provided by the architecture. Verbose 871 information will be printed at KERN_DEBUG loglevel depending 872 on the mminit_loglevel= command-line option. 873 874 If unsure, say Y 875 876config MEMORY_NOTIFIER_ERROR_INJECT 877 tristate "Memory hotplug notifier error injection module" 878 depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION 879 help 880 This option provides the ability to inject artificial errors to 881 memory hotplug notifier chain callbacks. It is controlled through 882 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 883 884 If the notifier call chain should be failed with some events 885 notified, write the error code to "actions/<notifier event>/error". 886 887 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 888 889 # cd /sys/kernel/debug/notifier-error-inject/memory 890 # echo -12 > actions/MEM_GOING_OFFLINE/error 891 # echo offline > /sys/devices/system/memory/memoryXXX/state 892 bash: echo: write error: Cannot allocate memory 893 894 To compile this code as a module, choose M here: the module will 895 be called memory-notifier-error-inject. 896 897 If unsure, say N. 898 899config DEBUG_PER_CPU_MAPS 900 bool "Debug access to per_cpu maps" 901 depends on DEBUG_KERNEL 902 depends on SMP 903 help 904 Say Y to verify that the per_cpu map being accessed has 905 been set up. This adds a fair amount of code to kernel memory 906 and decreases performance. 907 908 Say N if unsure. 909 910config DEBUG_KMAP_LOCAL 911 bool "Debug kmap_local temporary mappings" 912 depends on DEBUG_KERNEL && KMAP_LOCAL 913 help 914 This option enables additional error checking for the kmap_local 915 infrastructure. Disable for production use. 916 917config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 918 bool 919 920config DEBUG_KMAP_LOCAL_FORCE_MAP 921 bool "Enforce kmap_local temporary mappings" 922 depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 923 select KMAP_LOCAL 924 select DEBUG_KMAP_LOCAL 925 help 926 This option enforces temporary mappings through the kmap_local 927 mechanism for non-highmem pages and on non-highmem systems. 928 Disable this for production systems! 929 930config DEBUG_HIGHMEM 931 bool "Highmem debugging" 932 depends on DEBUG_KERNEL && HIGHMEM 933 select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 934 select DEBUG_KMAP_LOCAL 935 help 936 This option enables additional error checking for high memory 937 systems. Disable for production systems. 938 939config HAVE_DEBUG_STACKOVERFLOW 940 bool 941 942config DEBUG_STACKOVERFLOW 943 bool "Check for stack overflows" 944 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 945 help 946 Say Y here if you want to check for overflows of kernel, IRQ 947 and exception stacks (if your architecture uses them). This 948 option will show detailed messages if free stack space drops 949 below a certain limit. 950 951 These kinds of bugs usually occur when call-chains in the 952 kernel get too deep, especially when interrupts are 953 involved. 954 955 Use this in cases where you see apparently random memory 956 corruption, especially if it appears in 'struct thread_info' 957 958 If in doubt, say "N". 959 960source "lib/Kconfig.kasan" 961source "lib/Kconfig.kfence" 962source "lib/Kconfig.kmsan" 963 964endmenu # "Memory Debugging" 965 966config DEBUG_SHIRQ 967 bool "Debug shared IRQ handlers" 968 depends on DEBUG_KERNEL 969 help 970 Enable this to generate a spurious interrupt just before a shared 971 interrupt handler is deregistered (generating one when registering 972 is currently disabled). Drivers need to handle this correctly. Some 973 don't and need to be caught. 974 975menu "Debug Oops, Lockups and Hangs" 976 977config PANIC_ON_OOPS 978 bool "Panic on Oops" 979 help 980 Say Y here to enable the kernel to panic when it oopses. This 981 has the same effect as setting oops=panic on the kernel command 982 line. 983 984 This feature is useful to ensure that the kernel does not do 985 anything erroneous after an oops which could result in data 986 corruption or other issues. 987 988 Say N if unsure. 989 990config PANIC_ON_OOPS_VALUE 991 int 992 range 0 1 993 default 0 if !PANIC_ON_OOPS 994 default 1 if PANIC_ON_OOPS 995 996config PANIC_TIMEOUT 997 int "panic timeout" 998 default 0 999 help 1000 Set the timeout value (in seconds) until a reboot occurs when 1001 the kernel panics. If n = 0, then we wait forever. A timeout 1002 value n > 0 will wait n seconds before rebooting, while a timeout 1003 value n < 0 will reboot immediately. 1004 1005config LOCKUP_DETECTOR 1006 bool 1007 1008config SOFTLOCKUP_DETECTOR 1009 bool "Detect Soft Lockups" 1010 depends on DEBUG_KERNEL && !S390 1011 select LOCKUP_DETECTOR 1012 help 1013 Say Y here to enable the kernel to act as a watchdog to detect 1014 soft lockups. 1015 1016 Softlockups are bugs that cause the kernel to loop in kernel 1017 mode for more than 20 seconds, without giving other tasks a 1018 chance to run. The current stack trace is displayed upon 1019 detection and the system will stay locked up. 1020 1021config BOOTPARAM_SOFTLOCKUP_PANIC 1022 bool "Panic (Reboot) On Soft Lockups" 1023 depends on SOFTLOCKUP_DETECTOR 1024 help 1025 Say Y here to enable the kernel to panic on "soft lockups", 1026 which are bugs that cause the kernel to loop in kernel 1027 mode for more than 20 seconds (configurable using the watchdog_thresh 1028 sysctl), without giving other tasks a chance to run. 1029 1030 The panic can be used in combination with panic_timeout, 1031 to cause the system to reboot automatically after a 1032 lockup has been detected. This feature is useful for 1033 high-availability systems that have uptime guarantees and 1034 where a lockup must be resolved ASAP. 1035 1036 Say N if unsure. 1037 1038config HAVE_HARDLOCKUP_DETECTOR_BUDDY 1039 bool 1040 depends on SMP 1041 default y 1042 1043# 1044# Global switch whether to build a hardlockup detector at all. It is available 1045# only when the architecture supports at least one implementation. There are 1046# two exceptions. The hardlockup detector is never enabled on: 1047# 1048# s390: it reported many false positives there 1049# 1050# sparc64: has a custom implementation which is not using the common 1051# hardlockup command line options and sysctl interface. 1052# 1053config HARDLOCKUP_DETECTOR 1054 bool "Detect Hard Lockups" 1055 depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64 1056 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH 1057 imply HARDLOCKUP_DETECTOR_PERF 1058 imply HARDLOCKUP_DETECTOR_BUDDY 1059 imply HARDLOCKUP_DETECTOR_ARCH 1060 select LOCKUP_DETECTOR 1061 1062 help 1063 Say Y here to enable the kernel to act as a watchdog to detect 1064 hard lockups. 1065 1066 Hardlockups are bugs that cause the CPU to loop in kernel mode 1067 for more than 10 seconds, without letting other interrupts have a 1068 chance to run. The current stack trace is displayed upon detection 1069 and the system will stay locked up. 1070 1071# 1072# Note that arch-specific variants are always preferred. 1073# 1074config HARDLOCKUP_DETECTOR_PREFER_BUDDY 1075 bool "Prefer the buddy CPU hardlockup detector" 1076 depends on HARDLOCKUP_DETECTOR 1077 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY 1078 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1079 help 1080 Say Y here to prefer the buddy hardlockup detector over the perf one. 1081 1082 With the buddy detector, each CPU uses its softlockup hrtimer 1083 to check that the next CPU is processing hrtimer interrupts by 1084 verifying that a counter is increasing. 1085 1086 This hardlockup detector is useful on systems that don't have 1087 an arch-specific hardlockup detector or if resources needed 1088 for the hardlockup detector are better used for other things. 1089 1090config HARDLOCKUP_DETECTOR_PERF 1091 bool 1092 depends on HARDLOCKUP_DETECTOR 1093 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY 1094 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1095 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1096 1097config HARDLOCKUP_DETECTOR_BUDDY 1098 bool 1099 depends on HARDLOCKUP_DETECTOR 1100 depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY 1101 depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY 1102 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1103 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1104 1105config HARDLOCKUP_DETECTOR_ARCH 1106 bool 1107 depends on HARDLOCKUP_DETECTOR 1108 depends on HAVE_HARDLOCKUP_DETECTOR_ARCH 1109 help 1110 The arch-specific implementation of the hardlockup detector will 1111 be used. 1112 1113# 1114# Both the "perf" and "buddy" hardlockup detectors count hrtimer 1115# interrupts. This config enables functions managing this common code. 1116# 1117config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1118 bool 1119 select SOFTLOCKUP_DETECTOR 1120 1121# 1122# Enables a timestamp based low pass filter to compensate for perf based 1123# hard lockup detection which runs too fast due to turbo modes. 1124# 1125config HARDLOCKUP_CHECK_TIMESTAMP 1126 bool 1127 1128config BOOTPARAM_HARDLOCKUP_PANIC 1129 bool "Panic (Reboot) On Hard Lockups" 1130 depends on HARDLOCKUP_DETECTOR 1131 help 1132 Say Y here to enable the kernel to panic on "hard lockups", 1133 which are bugs that cause the kernel to loop in kernel 1134 mode with interrupts disabled for more than 10 seconds (configurable 1135 using the watchdog_thresh sysctl). 1136 1137 Say N if unsure. 1138 1139config DETECT_HUNG_TASK 1140 bool "Detect Hung Tasks" 1141 depends on DEBUG_KERNEL 1142 default SOFTLOCKUP_DETECTOR 1143 help 1144 Say Y here to enable the kernel to detect "hung tasks", 1145 which are bugs that cause the task to be stuck in 1146 uninterruptible "D" state indefinitely. 1147 1148 When a hung task is detected, the kernel will print the 1149 current stack trace (which you should report), but the 1150 task will stay in uninterruptible state. If lockdep is 1151 enabled then all held locks will also be reported. This 1152 feature has negligible overhead. 1153 1154config DEFAULT_HUNG_TASK_TIMEOUT 1155 int "Default timeout for hung task detection (in seconds)" 1156 depends on DETECT_HUNG_TASK 1157 default 120 1158 help 1159 This option controls the default timeout (in seconds) used 1160 to determine when a task has become non-responsive and should 1161 be considered hung. 1162 1163 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 1164 sysctl or by writing a value to 1165 /proc/sys/kernel/hung_task_timeout_secs. 1166 1167 A timeout of 0 disables the check. The default is two minutes. 1168 Keeping the default should be fine in most cases. 1169 1170config BOOTPARAM_HUNG_TASK_PANIC 1171 bool "Panic (Reboot) On Hung Tasks" 1172 depends on DETECT_HUNG_TASK 1173 help 1174 Say Y here to enable the kernel to panic on "hung tasks", 1175 which are bugs that cause the kernel to leave a task stuck 1176 in uninterruptible "D" state. 1177 1178 The panic can be used in combination with panic_timeout, 1179 to cause the system to reboot automatically after a 1180 hung task has been detected. This feature is useful for 1181 high-availability systems that have uptime guarantees and 1182 where a hung tasks must be resolved ASAP. 1183 1184 Say N if unsure. 1185 1186config WQ_WATCHDOG 1187 bool "Detect Workqueue Stalls" 1188 depends on DEBUG_KERNEL 1189 help 1190 Say Y here to enable stall detection on workqueues. If a 1191 worker pool doesn't make forward progress on a pending work 1192 item for over a given amount of time, 30s by default, a 1193 warning message is printed along with dump of workqueue 1194 state. This can be configured through kernel parameter 1195 "workqueue.watchdog_thresh" and its sysfs counterpart. 1196 1197config WQ_CPU_INTENSIVE_REPORT 1198 bool "Report per-cpu work items which hog CPU for too long" 1199 depends on DEBUG_KERNEL 1200 help 1201 Say Y here to enable reporting of concurrency-managed per-cpu work 1202 items that hog CPUs for longer than 1203 workqueue.cpu_intensive_threshold_us. Workqueue automatically 1204 detects and excludes them from concurrency management to prevent 1205 them from stalling other per-cpu work items. Occassional 1206 triggering may not necessarily indicate a problem. Repeated 1207 triggering likely indicates that the work item should be switched 1208 to use an unbound workqueue. 1209 1210config TEST_LOCKUP 1211 tristate "Test module to generate lockups" 1212 depends on m 1213 help 1214 This builds the "test_lockup" module that helps to make sure 1215 that watchdogs and lockup detectors are working properly. 1216 1217 Depending on module parameters it could emulate soft or hard 1218 lockup, "hung task", or locking arbitrary lock for a long time. 1219 Also it could generate series of lockups with cooling-down periods. 1220 1221 If unsure, say N. 1222 1223endmenu # "Debug lockups and hangs" 1224 1225menu "Scheduler Debugging" 1226 1227config SCHED_DEBUG 1228 bool "Collect scheduler debugging info" 1229 depends on DEBUG_KERNEL && DEBUG_FS 1230 default y 1231 help 1232 If you say Y here, the /sys/kernel/debug/sched file will be provided 1233 that can help debug the scheduler. The runtime overhead of this 1234 option is minimal. 1235 1236config SCHED_INFO 1237 bool 1238 default n 1239 1240config SCHEDSTATS 1241 bool "Collect scheduler statistics" 1242 depends on DEBUG_KERNEL && PROC_FS 1243 select SCHED_INFO 1244 help 1245 If you say Y here, additional code will be inserted into the 1246 scheduler and related routines to collect statistics about 1247 scheduler behavior and provide them in /proc/schedstat. These 1248 stats may be useful for both tuning and debugging the scheduler 1249 If you aren't debugging the scheduler or trying to tune a specific 1250 application, you can say N to avoid the very slight overhead 1251 this adds. 1252 1253endmenu 1254 1255config DEBUG_TIMEKEEPING 1256 bool "Enable extra timekeeping sanity checking" 1257 help 1258 This option will enable additional timekeeping sanity checks 1259 which may be helpful when diagnosing issues where timekeeping 1260 problems are suspected. 1261 1262 This may include checks in the timekeeping hotpaths, so this 1263 option may have a (very small) performance impact to some 1264 workloads. 1265 1266 If unsure, say N. 1267 1268config DEBUG_PREEMPT 1269 bool "Debug preemptible kernel" 1270 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1271 help 1272 If you say Y here then the kernel will use a debug variant of the 1273 commonly used smp_processor_id() function and will print warnings 1274 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1275 will detect preemption count underflows. 1276 1277 This option has potential to introduce high runtime overhead, 1278 depending on workload as it triggers debugging routines for each 1279 this_cpu operation. It should only be used for debugging purposes. 1280 1281menu "Lock Debugging (spinlocks, mutexes, etc...)" 1282 1283config LOCK_DEBUGGING_SUPPORT 1284 bool 1285 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1286 default y 1287 1288config PROVE_LOCKING 1289 bool "Lock debugging: prove locking correctness" 1290 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1291 select LOCKDEP 1292 select DEBUG_SPINLOCK 1293 select DEBUG_MUTEXES if !PREEMPT_RT 1294 select DEBUG_RT_MUTEXES if RT_MUTEXES 1295 select DEBUG_RWSEMS 1296 select DEBUG_WW_MUTEX_SLOWPATH 1297 select DEBUG_LOCK_ALLOC 1298 select PREEMPT_COUNT if !ARCH_NO_PREEMPT 1299 select TRACE_IRQFLAGS 1300 default n 1301 help 1302 This feature enables the kernel to prove that all locking 1303 that occurs in the kernel runtime is mathematically 1304 correct: that under no circumstance could an arbitrary (and 1305 not yet triggered) combination of observed locking 1306 sequences (on an arbitrary number of CPUs, running an 1307 arbitrary number of tasks and interrupt contexts) cause a 1308 deadlock. 1309 1310 In short, this feature enables the kernel to report locking 1311 related deadlocks before they actually occur. 1312 1313 The proof does not depend on how hard and complex a 1314 deadlock scenario would be to trigger: how many 1315 participant CPUs, tasks and irq-contexts would be needed 1316 for it to trigger. The proof also does not depend on 1317 timing: if a race and a resulting deadlock is possible 1318 theoretically (no matter how unlikely the race scenario 1319 is), it will be proven so and will immediately be 1320 reported by the kernel (once the event is observed that 1321 makes the deadlock theoretically possible). 1322 1323 If a deadlock is impossible (i.e. the locking rules, as 1324 observed by the kernel, are mathematically correct), the 1325 kernel reports nothing. 1326 1327 NOTE: this feature can also be enabled for rwlocks, mutexes 1328 and rwsems - in which case all dependencies between these 1329 different locking variants are observed and mapped too, and 1330 the proof of observed correctness is also maintained for an 1331 arbitrary combination of these separate locking variants. 1332 1333 For more details, see Documentation/locking/lockdep-design.rst. 1334 1335config PROVE_RAW_LOCK_NESTING 1336 bool "Enable raw_spinlock - spinlock nesting checks" 1337 depends on PROVE_LOCKING 1338 default n 1339 help 1340 Enable the raw_spinlock vs. spinlock nesting checks which ensure 1341 that the lock nesting rules for PREEMPT_RT enabled kernels are 1342 not violated. 1343 1344 NOTE: There are known nesting problems. So if you enable this 1345 option expect lockdep splats until these problems have been fully 1346 addressed which is work in progress. This config switch allows to 1347 identify and analyze these problems. It will be removed and the 1348 check permanently enabled once the main issues have been fixed. 1349 1350 If unsure, select N. 1351 1352config LOCK_STAT 1353 bool "Lock usage statistics" 1354 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1355 select LOCKDEP 1356 select DEBUG_SPINLOCK 1357 select DEBUG_MUTEXES if !PREEMPT_RT 1358 select DEBUG_RT_MUTEXES if RT_MUTEXES 1359 select DEBUG_LOCK_ALLOC 1360 default n 1361 help 1362 This feature enables tracking lock contention points 1363 1364 For more details, see Documentation/locking/lockstat.rst 1365 1366 This also enables lock events required by "perf lock", 1367 subcommand of perf. 1368 If you want to use "perf lock", you also need to turn on 1369 CONFIG_EVENT_TRACING. 1370 1371 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1372 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1373 1374config DEBUG_RT_MUTEXES 1375 bool "RT Mutex debugging, deadlock detection" 1376 depends on DEBUG_KERNEL && RT_MUTEXES 1377 help 1378 This allows rt mutex semantics violations and rt mutex related 1379 deadlocks (lockups) to be detected and reported automatically. 1380 1381config DEBUG_SPINLOCK 1382 bool "Spinlock and rw-lock debugging: basic checks" 1383 depends on DEBUG_KERNEL 1384 select UNINLINE_SPIN_UNLOCK 1385 help 1386 Say Y here and build SMP to catch missing spinlock initialization 1387 and certain other kinds of spinlock errors commonly made. This is 1388 best used in conjunction with the NMI watchdog so that spinlock 1389 deadlocks are also debuggable. 1390 1391config DEBUG_MUTEXES 1392 bool "Mutex debugging: basic checks" 1393 depends on DEBUG_KERNEL && !PREEMPT_RT 1394 help 1395 This feature allows mutex semantics violations to be detected and 1396 reported. 1397 1398config DEBUG_WW_MUTEX_SLOWPATH 1399 bool "Wait/wound mutex debugging: Slowpath testing" 1400 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1401 select DEBUG_LOCK_ALLOC 1402 select DEBUG_SPINLOCK 1403 select DEBUG_MUTEXES if !PREEMPT_RT 1404 select DEBUG_RT_MUTEXES if PREEMPT_RT 1405 help 1406 This feature enables slowpath testing for w/w mutex users by 1407 injecting additional -EDEADLK wound/backoff cases. Together with 1408 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1409 will test all possible w/w mutex interface abuse with the 1410 exception of simply not acquiring all the required locks. 1411 Note that this feature can introduce significant overhead, so 1412 it really should not be enabled in a production or distro kernel, 1413 even a debug kernel. If you are a driver writer, enable it. If 1414 you are a distro, do not. 1415 1416config DEBUG_RWSEMS 1417 bool "RW Semaphore debugging: basic checks" 1418 depends on DEBUG_KERNEL 1419 help 1420 This debugging feature allows mismatched rw semaphore locks 1421 and unlocks to be detected and reported. 1422 1423config DEBUG_LOCK_ALLOC 1424 bool "Lock debugging: detect incorrect freeing of live locks" 1425 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1426 select DEBUG_SPINLOCK 1427 select DEBUG_MUTEXES if !PREEMPT_RT 1428 select DEBUG_RT_MUTEXES if RT_MUTEXES 1429 select LOCKDEP 1430 help 1431 This feature will check whether any held lock (spinlock, rwlock, 1432 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1433 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1434 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1435 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1436 held during task exit. 1437 1438config LOCKDEP 1439 bool 1440 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1441 select STACKTRACE 1442 select KALLSYMS 1443 select KALLSYMS_ALL 1444 1445config LOCKDEP_SMALL 1446 bool 1447 1448config LOCKDEP_BITS 1449 int "Bitsize for MAX_LOCKDEP_ENTRIES" 1450 depends on LOCKDEP && !LOCKDEP_SMALL 1451 range 10 30 1452 default 15 1453 help 1454 Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message. 1455 1456config LOCKDEP_CHAINS_BITS 1457 int "Bitsize for MAX_LOCKDEP_CHAINS" 1458 depends on LOCKDEP && !LOCKDEP_SMALL 1459 range 10 30 1460 default 16 1461 help 1462 Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message. 1463 1464config LOCKDEP_STACK_TRACE_BITS 1465 int "Bitsize for MAX_STACK_TRACE_ENTRIES" 1466 depends on LOCKDEP && !LOCKDEP_SMALL 1467 range 10 30 1468 default 19 1469 help 1470 Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message. 1471 1472config LOCKDEP_STACK_TRACE_HASH_BITS 1473 int "Bitsize for STACK_TRACE_HASH_SIZE" 1474 depends on LOCKDEP && !LOCKDEP_SMALL 1475 range 10 30 1476 default 14 1477 help 1478 Try increasing this value if you need large STACK_TRACE_HASH_SIZE. 1479 1480config LOCKDEP_CIRCULAR_QUEUE_BITS 1481 int "Bitsize for elements in circular_queue struct" 1482 depends on LOCKDEP 1483 range 10 30 1484 default 12 1485 help 1486 Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure. 1487 1488config DEBUG_LOCKDEP 1489 bool "Lock dependency engine debugging" 1490 depends on DEBUG_KERNEL && LOCKDEP 1491 select DEBUG_IRQFLAGS 1492 help 1493 If you say Y here, the lock dependency engine will do 1494 additional runtime checks to debug itself, at the price 1495 of more runtime overhead. 1496 1497config DEBUG_ATOMIC_SLEEP 1498 bool "Sleep inside atomic section checking" 1499 select PREEMPT_COUNT 1500 depends on DEBUG_KERNEL 1501 depends on !ARCH_NO_PREEMPT 1502 help 1503 If you say Y here, various routines which may sleep will become very 1504 noisy if they are called inside atomic sections: when a spinlock is 1505 held, inside an rcu read side critical section, inside preempt disabled 1506 sections, inside an interrupt, etc... 1507 1508config DEBUG_LOCKING_API_SELFTESTS 1509 bool "Locking API boot-time self-tests" 1510 depends on DEBUG_KERNEL 1511 help 1512 Say Y here if you want the kernel to run a short self-test during 1513 bootup. The self-test checks whether common types of locking bugs 1514 are detected by debugging mechanisms or not. (if you disable 1515 lock debugging then those bugs won't be detected of course.) 1516 The following locking APIs are covered: spinlocks, rwlocks, 1517 mutexes and rwsems. 1518 1519config LOCK_TORTURE_TEST 1520 tristate "torture tests for locking" 1521 depends on DEBUG_KERNEL 1522 select TORTURE_TEST 1523 help 1524 This option provides a kernel module that runs torture tests 1525 on kernel locking primitives. The kernel module may be built 1526 after the fact on the running kernel to be tested, if desired. 1527 1528 Say Y here if you want kernel locking-primitive torture tests 1529 to be built into the kernel. 1530 Say M if you want these torture tests to build as a module. 1531 Say N if you are unsure. 1532 1533config WW_MUTEX_SELFTEST 1534 tristate "Wait/wound mutex selftests" 1535 help 1536 This option provides a kernel module that runs tests on the 1537 on the struct ww_mutex locking API. 1538 1539 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1540 with this test harness. 1541 1542 Say M if you want these self tests to build as a module. 1543 Say N if you are unsure. 1544 1545config SCF_TORTURE_TEST 1546 tristate "torture tests for smp_call_function*()" 1547 depends on DEBUG_KERNEL 1548 select TORTURE_TEST 1549 help 1550 This option provides a kernel module that runs torture tests 1551 on the smp_call_function() family of primitives. The kernel 1552 module may be built after the fact on the running kernel to 1553 be tested, if desired. 1554 1555config CSD_LOCK_WAIT_DEBUG 1556 bool "Debugging for csd_lock_wait(), called from smp_call_function*()" 1557 depends on DEBUG_KERNEL 1558 depends on 64BIT 1559 default n 1560 help 1561 This option enables debug prints when CPUs are slow to respond 1562 to the smp_call_function*() IPI wrappers. These debug prints 1563 include the IPI handler function currently executing (if any) 1564 and relevant stack traces. 1565 1566config CSD_LOCK_WAIT_DEBUG_DEFAULT 1567 bool "Default csd_lock_wait() debugging on at boot time" 1568 depends on CSD_LOCK_WAIT_DEBUG 1569 depends on 64BIT 1570 default n 1571 help 1572 This option causes the csdlock_debug= kernel boot parameter to 1573 default to 1 (basic debugging) instead of 0 (no debugging). 1574 1575endmenu # lock debugging 1576 1577config TRACE_IRQFLAGS 1578 depends on TRACE_IRQFLAGS_SUPPORT 1579 bool 1580 help 1581 Enables hooks to interrupt enabling and disabling for 1582 either tracing or lock debugging. 1583 1584config TRACE_IRQFLAGS_NMI 1585 def_bool y 1586 depends on TRACE_IRQFLAGS 1587 depends on TRACE_IRQFLAGS_NMI_SUPPORT 1588 1589config NMI_CHECK_CPU 1590 bool "Debugging for CPUs failing to respond to backtrace requests" 1591 depends on DEBUG_KERNEL 1592 depends on X86 1593 default n 1594 help 1595 Enables debug prints when a CPU fails to respond to a given 1596 backtrace NMI. These prints provide some reasons why a CPU 1597 might legitimately be failing to respond, for example, if it 1598 is offline of if ignore_nmis is set. 1599 1600config DEBUG_IRQFLAGS 1601 bool "Debug IRQ flag manipulation" 1602 help 1603 Enables checks for potentially unsafe enabling or disabling of 1604 interrupts, such as calling raw_local_irq_restore() when interrupts 1605 are enabled. 1606 1607config STACKTRACE 1608 bool "Stack backtrace support" 1609 depends on STACKTRACE_SUPPORT 1610 help 1611 This option causes the kernel to create a /proc/pid/stack for 1612 every process, showing its current stack trace. 1613 It is also used by various kernel debugging features that require 1614 stack trace generation. 1615 1616config WARN_ALL_UNSEEDED_RANDOM 1617 bool "Warn for all uses of unseeded randomness" 1618 default n 1619 help 1620 Some parts of the kernel contain bugs relating to their use of 1621 cryptographically secure random numbers before it's actually possible 1622 to generate those numbers securely. This setting ensures that these 1623 flaws don't go unnoticed, by enabling a message, should this ever 1624 occur. This will allow people with obscure setups to know when things 1625 are going wrong, so that they might contact developers about fixing 1626 it. 1627 1628 Unfortunately, on some models of some architectures getting 1629 a fully seeded CRNG is extremely difficult, and so this can 1630 result in dmesg getting spammed for a surprisingly long 1631 time. This is really bad from a security perspective, and 1632 so architecture maintainers really need to do what they can 1633 to get the CRNG seeded sooner after the system is booted. 1634 However, since users cannot do anything actionable to 1635 address this, by default this option is disabled. 1636 1637 Say Y here if you want to receive warnings for all uses of 1638 unseeded randomness. This will be of use primarily for 1639 those developers interested in improving the security of 1640 Linux kernels running on their architecture (or 1641 subarchitecture). 1642 1643config DEBUG_KOBJECT 1644 bool "kobject debugging" 1645 depends on DEBUG_KERNEL 1646 help 1647 If you say Y here, some extra kobject debugging messages will be sent 1648 to the syslog. 1649 1650config DEBUG_KOBJECT_RELEASE 1651 bool "kobject release debugging" 1652 depends on DEBUG_OBJECTS_TIMERS 1653 help 1654 kobjects are reference counted objects. This means that their 1655 last reference count put is not predictable, and the kobject can 1656 live on past the point at which a driver decides to drop its 1657 initial reference to the kobject gained on allocation. An 1658 example of this would be a struct device which has just been 1659 unregistered. 1660 1661 However, some buggy drivers assume that after such an operation, 1662 the memory backing the kobject can be immediately freed. This 1663 goes completely against the principles of a refcounted object. 1664 1665 If you say Y here, the kernel will delay the release of kobjects 1666 on the last reference count to improve the visibility of this 1667 kind of kobject release bug. 1668 1669config HAVE_DEBUG_BUGVERBOSE 1670 bool 1671 1672menu "Debug kernel data structures" 1673 1674config DEBUG_LIST 1675 bool "Debug linked list manipulation" 1676 depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION 1677 help 1678 Enable this to turn on extended checks in the linked-list 1679 walking routines. 1680 1681 If unsure, say N. 1682 1683config DEBUG_PLIST 1684 bool "Debug priority linked list manipulation" 1685 depends on DEBUG_KERNEL 1686 help 1687 Enable this to turn on extended checks in the priority-ordered 1688 linked-list (plist) walking routines. This checks the entire 1689 list multiple times during each manipulation. 1690 1691 If unsure, say N. 1692 1693config DEBUG_SG 1694 bool "Debug SG table operations" 1695 depends on DEBUG_KERNEL 1696 help 1697 Enable this to turn on checks on scatter-gather tables. This can 1698 help find problems with drivers that do not properly initialize 1699 their sg tables. 1700 1701 If unsure, say N. 1702 1703config DEBUG_NOTIFIERS 1704 bool "Debug notifier call chains" 1705 depends on DEBUG_KERNEL 1706 help 1707 Enable this to turn on sanity checking for notifier call chains. 1708 This is most useful for kernel developers to make sure that 1709 modules properly unregister themselves from notifier chains. 1710 This is a relatively cheap check but if you care about maximum 1711 performance, say N. 1712 1713config BUG_ON_DATA_CORRUPTION 1714 bool "Trigger a BUG when data corruption is detected" 1715 select DEBUG_LIST 1716 help 1717 Select this option if the kernel should BUG when it encounters 1718 data corruption in kernel memory structures when they get checked 1719 for validity. 1720 1721 If unsure, say N. 1722 1723config DEBUG_MAPLE_TREE 1724 bool "Debug maple trees" 1725 depends on DEBUG_KERNEL 1726 help 1727 Enable maple tree debugging information and extra validations. 1728 1729 If unsure, say N. 1730 1731endmenu 1732 1733config DEBUG_CREDENTIALS 1734 bool "Debug credential management" 1735 depends on DEBUG_KERNEL 1736 help 1737 Enable this to turn on some debug checking for credential 1738 management. The additional code keeps track of the number of 1739 pointers from task_structs to any given cred struct, and checks to 1740 see that this number never exceeds the usage count of the cred 1741 struct. 1742 1743 Furthermore, if SELinux is enabled, this also checks that the 1744 security pointer in the cred struct is never seen to be invalid. 1745 1746 If unsure, say N. 1747 1748source "kernel/rcu/Kconfig.debug" 1749 1750config DEBUG_WQ_FORCE_RR_CPU 1751 bool "Force round-robin CPU selection for unbound work items" 1752 depends on DEBUG_KERNEL 1753 default n 1754 help 1755 Workqueue used to implicitly guarantee that work items queued 1756 without explicit CPU specified are put on the local CPU. This 1757 guarantee is no longer true and while local CPU is still 1758 preferred work items may be put on foreign CPUs. Kernel 1759 parameter "workqueue.debug_force_rr_cpu" is added to force 1760 round-robin CPU selection to flush out usages which depend on the 1761 now broken guarantee. This config option enables the debug 1762 feature by default. When enabled, memory and cache locality will 1763 be impacted. 1764 1765config CPU_HOTPLUG_STATE_CONTROL 1766 bool "Enable CPU hotplug state control" 1767 depends on DEBUG_KERNEL 1768 depends on HOTPLUG_CPU 1769 default n 1770 help 1771 Allows to write steps between "offline" and "online" to the CPUs 1772 sysfs target file so states can be stepped granular. This is a debug 1773 option for now as the hotplug machinery cannot be stopped and 1774 restarted at arbitrary points yet. 1775 1776 Say N if your are unsure. 1777 1778config LATENCYTOP 1779 bool "Latency measuring infrastructure" 1780 depends on DEBUG_KERNEL 1781 depends on STACKTRACE_SUPPORT 1782 depends on PROC_FS 1783 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 1784 select KALLSYMS 1785 select KALLSYMS_ALL 1786 select STACKTRACE 1787 select SCHEDSTATS 1788 help 1789 Enable this option if you want to use the LatencyTOP tool 1790 to find out which userspace is blocking on what kernel operations. 1791 1792config DEBUG_CGROUP_REF 1793 bool "Disable inlining of cgroup css reference count functions" 1794 depends on DEBUG_KERNEL 1795 depends on CGROUPS 1796 depends on KPROBES 1797 default n 1798 help 1799 Force cgroup css reference count functions to not be inlined so 1800 that they can be kprobed for debugging. 1801 1802source "kernel/trace/Kconfig" 1803 1804config PROVIDE_OHCI1394_DMA_INIT 1805 bool "Remote debugging over FireWire early on boot" 1806 depends on PCI && X86 1807 help 1808 If you want to debug problems which hang or crash the kernel early 1809 on boot and the crashing machine has a FireWire port, you can use 1810 this feature to remotely access the memory of the crashed machine 1811 over FireWire. This employs remote DMA as part of the OHCI1394 1812 specification which is now the standard for FireWire controllers. 1813 1814 With remote DMA, you can monitor the printk buffer remotely using 1815 firescope and access all memory below 4GB using fireproxy from gdb. 1816 Even controlling a kernel debugger is possible using remote DMA. 1817 1818 Usage: 1819 1820 If ohci1394_dma=early is used as boot parameter, it will initialize 1821 all OHCI1394 controllers which are found in the PCI config space. 1822 1823 As all changes to the FireWire bus such as enabling and disabling 1824 devices cause a bus reset and thereby disable remote DMA for all 1825 devices, be sure to have the cable plugged and FireWire enabled on 1826 the debugging host before booting the debug target for debugging. 1827 1828 This code (~1k) is freed after boot. By then, the firewire stack 1829 in charge of the OHCI-1394 controllers should be used instead. 1830 1831 See Documentation/core-api/debugging-via-ohci1394.rst for more information. 1832 1833source "samples/Kconfig" 1834 1835config ARCH_HAS_DEVMEM_IS_ALLOWED 1836 bool 1837 1838config STRICT_DEVMEM 1839 bool "Filter access to /dev/mem" 1840 depends on MMU && DEVMEM 1841 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED 1842 default y if PPC || X86 || ARM64 1843 help 1844 If this option is disabled, you allow userspace (root) access to all 1845 of memory, including kernel and userspace memory. Accidental 1846 access to this is obviously disastrous, but specific access can 1847 be used by people debugging the kernel. Note that with PAT support 1848 enabled, even in this case there are restrictions on /dev/mem 1849 use due to the cache aliasing requirements. 1850 1851 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 1852 file only allows userspace access to PCI space and the BIOS code and 1853 data regions. This is sufficient for dosemu and X and all common 1854 users of /dev/mem. 1855 1856 If in doubt, say Y. 1857 1858config IO_STRICT_DEVMEM 1859 bool "Filter I/O access to /dev/mem" 1860 depends on STRICT_DEVMEM 1861 help 1862 If this option is disabled, you allow userspace (root) access to all 1863 io-memory regardless of whether a driver is actively using that 1864 range. Accidental access to this is obviously disastrous, but 1865 specific access can be used by people debugging kernel drivers. 1866 1867 If this option is switched on, the /dev/mem file only allows 1868 userspace access to *idle* io-memory ranges (see /proc/iomem) This 1869 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 1870 if the driver using a given range cannot be disabled. 1871 1872 If in doubt, say Y. 1873 1874menu "$(SRCARCH) Debugging" 1875 1876source "arch/$(SRCARCH)/Kconfig.debug" 1877 1878endmenu 1879 1880menu "Kernel Testing and Coverage" 1881 1882source "lib/kunit/Kconfig" 1883 1884config NOTIFIER_ERROR_INJECTION 1885 tristate "Notifier error injection" 1886 depends on DEBUG_KERNEL 1887 select DEBUG_FS 1888 help 1889 This option provides the ability to inject artificial errors to 1890 specified notifier chain callbacks. It is useful to test the error 1891 handling of notifier call chain failures. 1892 1893 Say N if unsure. 1894 1895config PM_NOTIFIER_ERROR_INJECT 1896 tristate "PM notifier error injection module" 1897 depends on PM && NOTIFIER_ERROR_INJECTION 1898 default m if PM_DEBUG 1899 help 1900 This option provides the ability to inject artificial errors to 1901 PM notifier chain callbacks. It is controlled through debugfs 1902 interface /sys/kernel/debug/notifier-error-inject/pm 1903 1904 If the notifier call chain should be failed with some events 1905 notified, write the error code to "actions/<notifier event>/error". 1906 1907 Example: Inject PM suspend error (-12 = -ENOMEM) 1908 1909 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1910 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1911 # echo mem > /sys/power/state 1912 bash: echo: write error: Cannot allocate memory 1913 1914 To compile this code as a module, choose M here: the module will 1915 be called pm-notifier-error-inject. 1916 1917 If unsure, say N. 1918 1919config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1920 tristate "OF reconfig notifier error injection module" 1921 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1922 help 1923 This option provides the ability to inject artificial errors to 1924 OF reconfig notifier chain callbacks. It is controlled 1925 through debugfs interface under 1926 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1927 1928 If the notifier call chain should be failed with some events 1929 notified, write the error code to "actions/<notifier event>/error". 1930 1931 To compile this code as a module, choose M here: the module will 1932 be called of-reconfig-notifier-error-inject. 1933 1934 If unsure, say N. 1935 1936config NETDEV_NOTIFIER_ERROR_INJECT 1937 tristate "Netdev notifier error injection module" 1938 depends on NET && NOTIFIER_ERROR_INJECTION 1939 help 1940 This option provides the ability to inject artificial errors to 1941 netdevice notifier chain callbacks. It is controlled through debugfs 1942 interface /sys/kernel/debug/notifier-error-inject/netdev 1943 1944 If the notifier call chain should be failed with some events 1945 notified, write the error code to "actions/<notifier event>/error". 1946 1947 Example: Inject netdevice mtu change error (-22 = -EINVAL) 1948 1949 # cd /sys/kernel/debug/notifier-error-inject/netdev 1950 # echo -22 > actions/NETDEV_CHANGEMTU/error 1951 # ip link set eth0 mtu 1024 1952 RTNETLINK answers: Invalid argument 1953 1954 To compile this code as a module, choose M here: the module will 1955 be called netdev-notifier-error-inject. 1956 1957 If unsure, say N. 1958 1959config FUNCTION_ERROR_INJECTION 1960 bool "Fault-injections of functions" 1961 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 1962 help 1963 Add fault injections into various functions that are annotated with 1964 ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return 1965 value of these functions. This is useful to test error paths of code. 1966 1967 If unsure, say N 1968 1969config FAULT_INJECTION 1970 bool "Fault-injection framework" 1971 depends on DEBUG_KERNEL 1972 help 1973 Provide fault-injection framework. 1974 For more details, see Documentation/fault-injection/. 1975 1976config FAILSLAB 1977 bool "Fault-injection capability for kmalloc" 1978 depends on FAULT_INJECTION 1979 depends on SLAB || SLUB 1980 help 1981 Provide fault-injection capability for kmalloc. 1982 1983config FAIL_PAGE_ALLOC 1984 bool "Fault-injection capability for alloc_pages()" 1985 depends on FAULT_INJECTION 1986 help 1987 Provide fault-injection capability for alloc_pages(). 1988 1989config FAULT_INJECTION_USERCOPY 1990 bool "Fault injection capability for usercopy functions" 1991 depends on FAULT_INJECTION 1992 help 1993 Provides fault-injection capability to inject failures 1994 in usercopy functions (copy_from_user(), get_user(), ...). 1995 1996config FAIL_MAKE_REQUEST 1997 bool "Fault-injection capability for disk IO" 1998 depends on FAULT_INJECTION && BLOCK 1999 help 2000 Provide fault-injection capability for disk IO. 2001 2002config FAIL_IO_TIMEOUT 2003 bool "Fault-injection capability for faking disk interrupts" 2004 depends on FAULT_INJECTION && BLOCK 2005 help 2006 Provide fault-injection capability on end IO handling. This 2007 will make the block layer "forget" an interrupt as configured, 2008 thus exercising the error handling. 2009 2010 Only works with drivers that use the generic timeout handling, 2011 for others it won't do anything. 2012 2013config FAIL_FUTEX 2014 bool "Fault-injection capability for futexes" 2015 select DEBUG_FS 2016 depends on FAULT_INJECTION && FUTEX 2017 help 2018 Provide fault-injection capability for futexes. 2019 2020config FAULT_INJECTION_DEBUG_FS 2021 bool "Debugfs entries for fault-injection capabilities" 2022 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 2023 help 2024 Enable configuration of fault-injection capabilities via debugfs. 2025 2026config FAIL_FUNCTION 2027 bool "Fault-injection capability for functions" 2028 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 2029 help 2030 Provide function-based fault-injection capability. 2031 This will allow you to override a specific function with a return 2032 with given return value. As a result, function caller will see 2033 an error value and have to handle it. This is useful to test the 2034 error handling in various subsystems. 2035 2036config FAIL_MMC_REQUEST 2037 bool "Fault-injection capability for MMC IO" 2038 depends on FAULT_INJECTION_DEBUG_FS && MMC 2039 help 2040 Provide fault-injection capability for MMC IO. 2041 This will make the mmc core return data errors. This is 2042 useful to test the error handling in the mmc block device 2043 and to test how the mmc host driver handles retries from 2044 the block device. 2045 2046config FAIL_SUNRPC 2047 bool "Fault-injection capability for SunRPC" 2048 depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG 2049 help 2050 Provide fault-injection capability for SunRPC and 2051 its consumers. 2052 2053config FAULT_INJECTION_CONFIGFS 2054 bool "Configfs interface for fault-injection capabilities" 2055 depends on FAULT_INJECTION 2056 select CONFIGFS_FS 2057 help 2058 This option allows configfs-based drivers to dynamically configure 2059 fault-injection via configfs. Each parameter for driver-specific 2060 fault-injection can be made visible as a configfs attribute in a 2061 configfs group. 2062 2063 2064config FAULT_INJECTION_STACKTRACE_FILTER 2065 bool "stacktrace filter for fault-injection capabilities" 2066 depends on FAULT_INJECTION 2067 depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT 2068 select STACKTRACE 2069 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 2070 help 2071 Provide stacktrace filter for fault-injection capabilities 2072 2073config ARCH_HAS_KCOV 2074 bool 2075 help 2076 An architecture should select this when it can successfully 2077 build and run with CONFIG_KCOV. This typically requires 2078 disabling instrumentation for some early boot code. 2079 2080config CC_HAS_SANCOV_TRACE_PC 2081 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 2082 2083 2084config KCOV 2085 bool "Code coverage for fuzzing" 2086 depends on ARCH_HAS_KCOV 2087 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 2088 depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \ 2089 GCC_VERSION >= 120000 || CLANG_VERSION >= 130000 2090 select DEBUG_FS 2091 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 2092 select OBJTOOL if HAVE_NOINSTR_HACK 2093 help 2094 KCOV exposes kernel code coverage information in a form suitable 2095 for coverage-guided fuzzing (randomized testing). 2096 2097 If RANDOMIZE_BASE is enabled, PC values will not be stable across 2098 different machines and across reboots. If you need stable PC values, 2099 disable RANDOMIZE_BASE. 2100 2101 For more details, see Documentation/dev-tools/kcov.rst. 2102 2103config KCOV_ENABLE_COMPARISONS 2104 bool "Enable comparison operands collection by KCOV" 2105 depends on KCOV 2106 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 2107 help 2108 KCOV also exposes operands of every comparison in the instrumented 2109 code along with operand sizes and PCs of the comparison instructions. 2110 These operands can be used by fuzzing engines to improve the quality 2111 of fuzzing coverage. 2112 2113config KCOV_INSTRUMENT_ALL 2114 bool "Instrument all code by default" 2115 depends on KCOV 2116 default y 2117 help 2118 If you are doing generic system call fuzzing (like e.g. syzkaller), 2119 then you will want to instrument the whole kernel and you should 2120 say y here. If you are doing more targeted fuzzing (like e.g. 2121 filesystem fuzzing with AFL) then you will want to enable coverage 2122 for more specific subsets of files, and should say n here. 2123 2124config KCOV_IRQ_AREA_SIZE 2125 hex "Size of interrupt coverage collection area in words" 2126 depends on KCOV 2127 default 0x40000 2128 help 2129 KCOV uses preallocated per-cpu areas to collect coverage from 2130 soft interrupts. This specifies the size of those areas in the 2131 number of unsigned long words. 2132 2133menuconfig RUNTIME_TESTING_MENU 2134 bool "Runtime Testing" 2135 def_bool y 2136 2137if RUNTIME_TESTING_MENU 2138 2139config TEST_DHRY 2140 tristate "Dhrystone benchmark test" 2141 help 2142 Enable this to include the Dhrystone 2.1 benchmark. This test 2143 calculates the number of Dhrystones per second, and the number of 2144 DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided 2145 by 1757 (the number of Dhrystones per second obtained on the VAX 2146 11/780, nominally a 1 MIPS machine). 2147 2148 To run the benchmark, it needs to be enabled explicitly, either from 2149 the kernel command line (when built-in), or from userspace (when 2150 built-in or modular. 2151 2152 Run once during kernel boot: 2153 2154 test_dhry.run 2155 2156 Set number of iterations from kernel command line: 2157 2158 test_dhry.iterations=<n> 2159 2160 Set number of iterations from userspace: 2161 2162 echo <n> > /sys/module/test_dhry/parameters/iterations 2163 2164 Trigger manual run from userspace: 2165 2166 echo y > /sys/module/test_dhry/parameters/run 2167 2168 If the number of iterations is <= 0, the test will devise a suitable 2169 number of iterations (test runs for at least 2s) automatically. 2170 This process takes ca. 4s. 2171 2172 If unsure, say N. 2173 2174config LKDTM 2175 tristate "Linux Kernel Dump Test Tool Module" 2176 depends on DEBUG_FS 2177 help 2178 This module enables testing of the different dumping mechanisms by 2179 inducing system failures at predefined crash points. 2180 If you don't need it: say N 2181 Choose M here to compile this code as a module. The module will be 2182 called lkdtm. 2183 2184 Documentation on how to use the module can be found in 2185 Documentation/fault-injection/provoke-crashes.rst 2186 2187config CPUMASK_KUNIT_TEST 2188 tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS 2189 depends on KUNIT 2190 default KUNIT_ALL_TESTS 2191 help 2192 Enable to turn on cpumask tests, running at boot or module load time. 2193 2194 For more information on KUnit and unit tests in general, please refer 2195 to the KUnit documentation in Documentation/dev-tools/kunit/. 2196 2197 If unsure, say N. 2198 2199config TEST_LIST_SORT 2200 tristate "Linked list sorting test" if !KUNIT_ALL_TESTS 2201 depends on KUNIT 2202 default KUNIT_ALL_TESTS 2203 help 2204 Enable this to turn on 'list_sort()' function test. This test is 2205 executed only once during system boot (so affects only boot time), 2206 or at module load time. 2207 2208 If unsure, say N. 2209 2210config TEST_MIN_HEAP 2211 tristate "Min heap test" 2212 depends on DEBUG_KERNEL || m 2213 help 2214 Enable this to turn on min heap function tests. This test is 2215 executed only once during system boot (so affects only boot time), 2216 or at module load time. 2217 2218 If unsure, say N. 2219 2220config TEST_SORT 2221 tristate "Array-based sort test" if !KUNIT_ALL_TESTS 2222 depends on KUNIT 2223 default KUNIT_ALL_TESTS 2224 help 2225 This option enables the self-test function of 'sort()' at boot, 2226 or at module load time. 2227 2228 If unsure, say N. 2229 2230config TEST_DIV64 2231 tristate "64bit/32bit division and modulo test" 2232 depends on DEBUG_KERNEL || m 2233 help 2234 Enable this to turn on 'do_div()' function test. This test is 2235 executed only once during system boot (so affects only boot time), 2236 or at module load time. 2237 2238 If unsure, say N. 2239 2240config KPROBES_SANITY_TEST 2241 tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS 2242 depends on DEBUG_KERNEL 2243 depends on KPROBES 2244 depends on KUNIT 2245 select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 2246 default KUNIT_ALL_TESTS 2247 help 2248 This option provides for testing basic kprobes functionality on 2249 boot. Samples of kprobe and kretprobe are inserted and 2250 verified for functionality. 2251 2252 Say N if you are unsure. 2253 2254config FPROBE_SANITY_TEST 2255 bool "Self test for fprobe" 2256 depends on DEBUG_KERNEL 2257 depends on FPROBE 2258 depends on KUNIT=y 2259 help 2260 This option will enable testing the fprobe when the system boot. 2261 A series of tests are made to verify that the fprobe is functioning 2262 properly. 2263 2264 Say N if you are unsure. 2265 2266config BACKTRACE_SELF_TEST 2267 tristate "Self test for the backtrace code" 2268 depends on DEBUG_KERNEL 2269 help 2270 This option provides a kernel module that can be used to test 2271 the kernel stack backtrace code. This option is not useful 2272 for distributions or general kernels, but only for kernel 2273 developers working on architecture code. 2274 2275 Note that if you want to also test saved backtraces, you will 2276 have to enable STACKTRACE as well. 2277 2278 Say N if you are unsure. 2279 2280config TEST_REF_TRACKER 2281 tristate "Self test for reference tracker" 2282 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT 2283 select REF_TRACKER 2284 help 2285 This option provides a kernel module performing tests 2286 using reference tracker infrastructure. 2287 2288 Say N if you are unsure. 2289 2290config RBTREE_TEST 2291 tristate "Red-Black tree test" 2292 depends on DEBUG_KERNEL 2293 help 2294 A benchmark measuring the performance of the rbtree library. 2295 Also includes rbtree invariant checks. 2296 2297config REED_SOLOMON_TEST 2298 tristate "Reed-Solomon library test" 2299 depends on DEBUG_KERNEL || m 2300 select REED_SOLOMON 2301 select REED_SOLOMON_ENC16 2302 select REED_SOLOMON_DEC16 2303 help 2304 This option enables the self-test function of rslib at boot, 2305 or at module load time. 2306 2307 If unsure, say N. 2308 2309config INTERVAL_TREE_TEST 2310 tristate "Interval tree test" 2311 depends on DEBUG_KERNEL 2312 select INTERVAL_TREE 2313 help 2314 A benchmark measuring the performance of the interval tree library 2315 2316config PERCPU_TEST 2317 tristate "Per cpu operations test" 2318 depends on m && DEBUG_KERNEL 2319 help 2320 Enable this option to build test module which validates per-cpu 2321 operations. 2322 2323 If unsure, say N. 2324 2325config ATOMIC64_SELFTEST 2326 tristate "Perform an atomic64_t self-test" 2327 help 2328 Enable this option to test the atomic64_t functions at boot or 2329 at module load time. 2330 2331 If unsure, say N. 2332 2333config ASYNC_RAID6_TEST 2334 tristate "Self test for hardware accelerated raid6 recovery" 2335 depends on ASYNC_RAID6_RECOV 2336 select ASYNC_MEMCPY 2337 help 2338 This is a one-shot self test that permutes through the 2339 recovery of all the possible two disk failure scenarios for a 2340 N-disk array. Recovery is performed with the asynchronous 2341 raid6 recovery routines, and will optionally use an offload 2342 engine if one is available. 2343 2344 If unsure, say N. 2345 2346config TEST_HEXDUMP 2347 tristate "Test functions located in the hexdump module at runtime" 2348 2349config STRING_SELFTEST 2350 tristate "Test string functions at runtime" 2351 2352config TEST_STRING_HELPERS 2353 tristate "Test functions located in the string_helpers module at runtime" 2354 2355config TEST_KSTRTOX 2356 tristate "Test kstrto*() family of functions at runtime" 2357 2358config TEST_PRINTF 2359 tristate "Test printf() family of functions at runtime" 2360 2361config TEST_SCANF 2362 tristate "Test scanf() family of functions at runtime" 2363 2364config TEST_BITMAP 2365 tristate "Test bitmap_*() family of functions at runtime" 2366 help 2367 Enable this option to test the bitmap functions at boot. 2368 2369 If unsure, say N. 2370 2371config TEST_UUID 2372 tristate "Test functions located in the uuid module at runtime" 2373 2374config TEST_XARRAY 2375 tristate "Test the XArray code at runtime" 2376 2377config TEST_MAPLE_TREE 2378 tristate "Test the Maple Tree code at runtime or module load" 2379 help 2380 Enable this option to test the maple tree code functions at boot, or 2381 when the module is loaded. Enable "Debug Maple Trees" will enable 2382 more verbose output on failures. 2383 2384 If unsure, say N. 2385 2386config TEST_RHASHTABLE 2387 tristate "Perform selftest on resizable hash table" 2388 help 2389 Enable this option to test the rhashtable functions at boot. 2390 2391 If unsure, say N. 2392 2393config TEST_IDA 2394 tristate "Perform selftest on IDA functions" 2395 2396config TEST_PARMAN 2397 tristate "Perform selftest on priority array manager" 2398 depends on PARMAN 2399 help 2400 Enable this option to test priority array manager on boot 2401 (or module load). 2402 2403 If unsure, say N. 2404 2405config TEST_IRQ_TIMINGS 2406 bool "IRQ timings selftest" 2407 depends on IRQ_TIMINGS 2408 help 2409 Enable this option to test the irq timings code on boot. 2410 2411 If unsure, say N. 2412 2413config TEST_LKM 2414 tristate "Test module loading with 'hello world' module" 2415 depends on m 2416 help 2417 This builds the "test_module" module that emits "Hello, world" 2418 on printk when loaded. It is designed to be used for basic 2419 evaluation of the module loading subsystem (for example when 2420 validating module verification). It lacks any extra dependencies, 2421 and will not normally be loaded by the system unless explicitly 2422 requested by name. 2423 2424 If unsure, say N. 2425 2426config TEST_BITOPS 2427 tristate "Test module for compilation of bitops operations" 2428 depends on m 2429 help 2430 This builds the "test_bitops" module that is much like the 2431 TEST_LKM module except that it does a basic exercise of the 2432 set/clear_bit macros and get_count_order/long to make sure there are 2433 no compiler warnings from C=1 sparse checker or -Wextra 2434 compilations. It has no dependencies and doesn't run or load unless 2435 explicitly requested by name. for example: modprobe test_bitops. 2436 2437 If unsure, say N. 2438 2439config TEST_VMALLOC 2440 tristate "Test module for stress/performance analysis of vmalloc allocator" 2441 default n 2442 depends on MMU 2443 depends on m 2444 help 2445 This builds the "test_vmalloc" module that should be used for 2446 stress and performance analysis. So, any new change for vmalloc 2447 subsystem can be evaluated from performance and stability point 2448 of view. 2449 2450 If unsure, say N. 2451 2452config TEST_USER_COPY 2453 tristate "Test user/kernel boundary protections" 2454 depends on m 2455 help 2456 This builds the "test_user_copy" module that runs sanity checks 2457 on the copy_to/from_user infrastructure, making sure basic 2458 user/kernel boundary testing is working. If it fails to load, 2459 a regression has been detected in the user/kernel memory boundary 2460 protections. 2461 2462 If unsure, say N. 2463 2464config TEST_BPF 2465 tristate "Test BPF filter functionality" 2466 depends on m && NET 2467 help 2468 This builds the "test_bpf" module that runs various test vectors 2469 against the BPF interpreter or BPF JIT compiler depending on the 2470 current setting. This is in particular useful for BPF JIT compiler 2471 development, but also to run regression tests against changes in 2472 the interpreter code. It also enables test stubs for eBPF maps and 2473 verifier used by user space verifier testsuite. 2474 2475 If unsure, say N. 2476 2477config TEST_BLACKHOLE_DEV 2478 tristate "Test blackhole netdev functionality" 2479 depends on m && NET 2480 help 2481 This builds the "test_blackhole_dev" module that validates the 2482 data path through this blackhole netdev. 2483 2484 If unsure, say N. 2485 2486config FIND_BIT_BENCHMARK 2487 tristate "Test find_bit functions" 2488 help 2489 This builds the "test_find_bit" module that measure find_*_bit() 2490 functions performance. 2491 2492 If unsure, say N. 2493 2494config TEST_FIRMWARE 2495 tristate "Test firmware loading via userspace interface" 2496 depends on FW_LOADER 2497 help 2498 This builds the "test_firmware" module that creates a userspace 2499 interface for testing firmware loading. This can be used to 2500 control the triggering of firmware loading without needing an 2501 actual firmware-using device. The contents can be rechecked by 2502 userspace. 2503 2504 If unsure, say N. 2505 2506config TEST_SYSCTL 2507 tristate "sysctl test driver" 2508 depends on PROC_SYSCTL 2509 help 2510 This builds the "test_sysctl" module. This driver enables to test the 2511 proc sysctl interfaces available to drivers safely without affecting 2512 production knobs which might alter system functionality. 2513 2514 If unsure, say N. 2515 2516config BITFIELD_KUNIT 2517 tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS 2518 depends on KUNIT 2519 default KUNIT_ALL_TESTS 2520 help 2521 Enable this option to test the bitfield functions at boot. 2522 2523 KUnit tests run during boot and output the results to the debug log 2524 in TAP format (http://testanything.org/). Only useful for kernel devs 2525 running the KUnit test harness, and not intended for inclusion into a 2526 production build. 2527 2528 For more information on KUnit and unit tests in general please refer 2529 to the KUnit documentation in Documentation/dev-tools/kunit/. 2530 2531 If unsure, say N. 2532 2533config CHECKSUM_KUNIT 2534 tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS 2535 depends on KUNIT 2536 default KUNIT_ALL_TESTS 2537 help 2538 Enable this option to test the checksum functions at boot. 2539 2540 KUnit tests run during boot and output the results to the debug log 2541 in TAP format (http://testanything.org/). Only useful for kernel devs 2542 running the KUnit test harness, and not intended for inclusion into a 2543 production build. 2544 2545 For more information on KUnit and unit tests in general please refer 2546 to the KUnit documentation in Documentation/dev-tools/kunit/. 2547 2548 If unsure, say N. 2549 2550config HASH_KUNIT_TEST 2551 tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS 2552 depends on KUNIT 2553 default KUNIT_ALL_TESTS 2554 help 2555 Enable this option to test the kernel's string (<linux/stringhash.h>), and 2556 integer (<linux/hash.h>) hash functions on boot. 2557 2558 KUnit tests run during boot and output the results to the debug log 2559 in TAP format (https://testanything.org/). Only useful for kernel devs 2560 running the KUnit test harness, and not intended for inclusion into a 2561 production build. 2562 2563 For more information on KUnit and unit tests in general please refer 2564 to the KUnit documentation in Documentation/dev-tools/kunit/. 2565 2566 This is intended to help people writing architecture-specific 2567 optimized versions. If unsure, say N. 2568 2569config RESOURCE_KUNIT_TEST 2570 tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS 2571 depends on KUNIT 2572 default KUNIT_ALL_TESTS 2573 help 2574 This builds the resource API unit test. 2575 Tests the logic of API provided by resource.c and ioport.h. 2576 For more information on KUnit and unit tests in general please refer 2577 to the KUnit documentation in Documentation/dev-tools/kunit/. 2578 2579 If unsure, say N. 2580 2581config SYSCTL_KUNIT_TEST 2582 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS 2583 depends on KUNIT 2584 default KUNIT_ALL_TESTS 2585 help 2586 This builds the proc sysctl unit test, which runs on boot. 2587 Tests the API contract and implementation correctness of sysctl. 2588 For more information on KUnit and unit tests in general please refer 2589 to the KUnit documentation in Documentation/dev-tools/kunit/. 2590 2591 If unsure, say N. 2592 2593config LIST_KUNIT_TEST 2594 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS 2595 depends on KUNIT 2596 default KUNIT_ALL_TESTS 2597 help 2598 This builds the linked list KUnit test suite. 2599 It tests that the API and basic functionality of the list_head type 2600 and associated macros. 2601 2602 KUnit tests run during boot and output the results to the debug log 2603 in TAP format (https://testanything.org/). Only useful for kernel devs 2604 running the KUnit test harness, and not intended for inclusion into a 2605 production build. 2606 2607 For more information on KUnit and unit tests in general please refer 2608 to the KUnit documentation in Documentation/dev-tools/kunit/. 2609 2610 If unsure, say N. 2611 2612config HASHTABLE_KUNIT_TEST 2613 tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS 2614 depends on KUNIT 2615 default KUNIT_ALL_TESTS 2616 help 2617 This builds the hashtable KUnit test suite. 2618 It tests the basic functionality of the API defined in 2619 include/linux/hashtable.h. For more information on KUnit and 2620 unit tests in general please refer to the KUnit documentation 2621 in Documentation/dev-tools/kunit/. 2622 2623 If unsure, say N. 2624 2625config LINEAR_RANGES_TEST 2626 tristate "KUnit test for linear_ranges" 2627 depends on KUNIT 2628 select LINEAR_RANGES 2629 help 2630 This builds the linear_ranges unit test, which runs on boot. 2631 Tests the linear_ranges logic correctness. 2632 For more information on KUnit and unit tests in general please refer 2633 to the KUnit documentation in Documentation/dev-tools/kunit/. 2634 2635 If unsure, say N. 2636 2637config CMDLINE_KUNIT_TEST 2638 tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS 2639 depends on KUNIT 2640 default KUNIT_ALL_TESTS 2641 help 2642 This builds the cmdline API unit test. 2643 Tests the logic of API provided by cmdline.c. 2644 For more information on KUnit and unit tests in general please refer 2645 to the KUnit documentation in Documentation/dev-tools/kunit/. 2646 2647 If unsure, say N. 2648 2649config BITS_TEST 2650 tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS 2651 depends on KUNIT 2652 default KUNIT_ALL_TESTS 2653 help 2654 This builds the bits unit test. 2655 Tests the logic of macros defined in bits.h. 2656 For more information on KUnit and unit tests in general please refer 2657 to the KUnit documentation in Documentation/dev-tools/kunit/. 2658 2659 If unsure, say N. 2660 2661config SLUB_KUNIT_TEST 2662 tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS 2663 depends on SLUB_DEBUG && KUNIT 2664 default KUNIT_ALL_TESTS 2665 help 2666 This builds SLUB allocator unit test. 2667 Tests SLUB cache debugging functionality. 2668 For more information on KUnit and unit tests in general please refer 2669 to the KUnit documentation in Documentation/dev-tools/kunit/. 2670 2671 If unsure, say N. 2672 2673config RATIONAL_KUNIT_TEST 2674 tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS 2675 depends on KUNIT && RATIONAL 2676 default KUNIT_ALL_TESTS 2677 help 2678 This builds the rational math unit test. 2679 For more information on KUnit and unit tests in general please refer 2680 to the KUnit documentation in Documentation/dev-tools/kunit/. 2681 2682 If unsure, say N. 2683 2684config MEMCPY_KUNIT_TEST 2685 tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS 2686 depends on KUNIT 2687 default KUNIT_ALL_TESTS 2688 help 2689 Builds unit tests for memcpy(), memmove(), and memset() functions. 2690 For more information on KUnit and unit tests in general please refer 2691 to the KUnit documentation in Documentation/dev-tools/kunit/. 2692 2693 If unsure, say N. 2694 2695config MEMCPY_SLOW_KUNIT_TEST 2696 bool "Include exhaustive memcpy tests" 2697 depends on MEMCPY_KUNIT_TEST 2698 default y 2699 help 2700 Some memcpy tests are quite exhaustive in checking for overlaps 2701 and bit ranges. These can be very slow, so they are split out 2702 as a separate config, in case they need to be disabled. 2703 2704config IS_SIGNED_TYPE_KUNIT_TEST 2705 tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS 2706 depends on KUNIT 2707 default KUNIT_ALL_TESTS 2708 help 2709 Builds unit tests for the is_signed_type() macro. 2710 2711 For more information on KUnit and unit tests in general please refer 2712 to the KUnit documentation in Documentation/dev-tools/kunit/. 2713 2714 If unsure, say N. 2715 2716config OVERFLOW_KUNIT_TEST 2717 tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS 2718 depends on KUNIT 2719 default KUNIT_ALL_TESTS 2720 help 2721 Builds unit tests for the check_*_overflow(), size_*(), allocation, and 2722 related functions. 2723 2724 For more information on KUnit and unit tests in general please refer 2725 to the KUnit documentation in Documentation/dev-tools/kunit/. 2726 2727 If unsure, say N. 2728 2729config STACKINIT_KUNIT_TEST 2730 tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS 2731 depends on KUNIT 2732 default KUNIT_ALL_TESTS 2733 help 2734 Test if the kernel is zero-initializing stack variables and 2735 padding. Coverage is controlled by compiler flags, 2736 CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO, 2737 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2738 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2739 2740config FORTIFY_KUNIT_TEST 2741 tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS 2742 depends on KUNIT && FORTIFY_SOURCE 2743 default KUNIT_ALL_TESTS 2744 help 2745 Builds unit tests for checking internals of FORTIFY_SOURCE as used 2746 by the str*() and mem*() family of functions. For testing runtime 2747 traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests. 2748 2749config HW_BREAKPOINT_KUNIT_TEST 2750 bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS 2751 depends on HAVE_HW_BREAKPOINT 2752 depends on KUNIT=y 2753 default KUNIT_ALL_TESTS 2754 help 2755 Tests for hw_breakpoint constraints accounting. 2756 2757 If unsure, say N. 2758 2759config STRCAT_KUNIT_TEST 2760 tristate "Test strcat() family of functions at runtime" if !KUNIT_ALL_TESTS 2761 depends on KUNIT 2762 default KUNIT_ALL_TESTS 2763 2764config STRSCPY_KUNIT_TEST 2765 tristate "Test strscpy*() family of functions at runtime" if !KUNIT_ALL_TESTS 2766 depends on KUNIT 2767 default KUNIT_ALL_TESTS 2768 2769config SIPHASH_KUNIT_TEST 2770 tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS 2771 depends on KUNIT 2772 default KUNIT_ALL_TESTS 2773 help 2774 Enable this option to test the kernel's siphash (<linux/siphash.h>) hash 2775 functions on boot (or module load). 2776 2777 This is intended to help people writing architecture-specific 2778 optimized versions. If unsure, say N. 2779 2780config TEST_UDELAY 2781 tristate "udelay test driver" 2782 help 2783 This builds the "udelay_test" module that helps to make sure 2784 that udelay() is working properly. 2785 2786 If unsure, say N. 2787 2788config TEST_STATIC_KEYS 2789 tristate "Test static keys" 2790 depends on m 2791 help 2792 Test the static key interfaces. 2793 2794 If unsure, say N. 2795 2796config TEST_DYNAMIC_DEBUG 2797 tristate "Test DYNAMIC_DEBUG" 2798 depends on DYNAMIC_DEBUG 2799 help 2800 This module registers a tracer callback to count enabled 2801 pr_debugs in a 'do_debugging' function, then alters their 2802 enablements, calls the function, and compares counts. 2803 2804 If unsure, say N. 2805 2806config TEST_KMOD 2807 tristate "kmod stress tester" 2808 depends on m 2809 depends on NETDEVICES && NET_CORE && INET # for TUN 2810 depends on BLOCK 2811 depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS 2812 select TEST_LKM 2813 select XFS_FS 2814 select TUN 2815 select BTRFS_FS 2816 help 2817 Test the kernel's module loading mechanism: kmod. kmod implements 2818 support to load modules using the Linux kernel's usermode helper. 2819 This test provides a series of tests against kmod. 2820 2821 Although technically you can either build test_kmod as a module or 2822 into the kernel we disallow building it into the kernel since 2823 it stress tests request_module() and this will very likely cause 2824 some issues by taking over precious threads available from other 2825 module load requests, ultimately this could be fatal. 2826 2827 To run tests run: 2828 2829 tools/testing/selftests/kmod/kmod.sh --help 2830 2831 If unsure, say N. 2832 2833config TEST_DEBUG_VIRTUAL 2834 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 2835 depends on DEBUG_VIRTUAL 2836 help 2837 Test the kernel's ability to detect incorrect calls to 2838 virt_to_phys() done against the non-linear part of the 2839 kernel's virtual address map. 2840 2841 If unsure, say N. 2842 2843config TEST_MEMCAT_P 2844 tristate "Test memcat_p() helper function" 2845 help 2846 Test the memcat_p() helper for correctly merging two 2847 pointer arrays together. 2848 2849 If unsure, say N. 2850 2851config TEST_LIVEPATCH 2852 tristate "Test livepatching" 2853 default n 2854 depends on DYNAMIC_DEBUG 2855 depends on LIVEPATCH 2856 depends on m 2857 help 2858 Test kernel livepatching features for correctness. The tests will 2859 load test modules that will be livepatched in various scenarios. 2860 2861 To run all the livepatching tests: 2862 2863 make -C tools/testing/selftests TARGETS=livepatch run_tests 2864 2865 Alternatively, individual tests may be invoked: 2866 2867 tools/testing/selftests/livepatch/test-callbacks.sh 2868 tools/testing/selftests/livepatch/test-livepatch.sh 2869 tools/testing/selftests/livepatch/test-shadow-vars.sh 2870 2871 If unsure, say N. 2872 2873config TEST_OBJAGG 2874 tristate "Perform selftest on object aggreration manager" 2875 default n 2876 depends on OBJAGG 2877 help 2878 Enable this option to test object aggregation manager on boot 2879 (or module load). 2880 2881config TEST_MEMINIT 2882 tristate "Test heap/page initialization" 2883 help 2884 Test if the kernel is zero-initializing heap and page allocations. 2885 This can be useful to test init_on_alloc and init_on_free features. 2886 2887 If unsure, say N. 2888 2889config TEST_HMM 2890 tristate "Test HMM (Heterogeneous Memory Management)" 2891 depends on TRANSPARENT_HUGEPAGE 2892 depends on DEVICE_PRIVATE 2893 select HMM_MIRROR 2894 select MMU_NOTIFIER 2895 help 2896 This is a pseudo device driver solely for testing HMM. 2897 Say M here if you want to build the HMM test module. 2898 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests. 2899 2900 If unsure, say N. 2901 2902config TEST_FREE_PAGES 2903 tristate "Test freeing pages" 2904 help 2905 Test that a memory leak does not occur due to a race between 2906 freeing a block of pages and a speculative page reference. 2907 Loading this module is safe if your kernel has the bug fixed. 2908 If the bug is not fixed, it will leak gigabytes of memory and 2909 probably OOM your system. 2910 2911config TEST_FPU 2912 tristate "Test floating point operations in kernel space" 2913 depends on X86 && !KCOV_INSTRUMENT_ALL 2914 help 2915 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu 2916 which will trigger a sequence of floating point operations. This is used 2917 for self-testing floating point control register setting in 2918 kernel_fpu_begin(). 2919 2920 If unsure, say N. 2921 2922config TEST_CLOCKSOURCE_WATCHDOG 2923 tristate "Test clocksource watchdog in kernel space" 2924 depends on CLOCKSOURCE_WATCHDOG 2925 help 2926 Enable this option to create a kernel module that will trigger 2927 a test of the clocksource watchdog. This module may be loaded 2928 via modprobe or insmod in which case it will run upon being 2929 loaded, or it may be built in, in which case it will run 2930 shortly after boot. 2931 2932 If unsure, say N. 2933 2934endif # RUNTIME_TESTING_MENU 2935 2936config ARCH_USE_MEMTEST 2937 bool 2938 help 2939 An architecture should select this when it uses early_memtest() 2940 during boot process. 2941 2942config MEMTEST 2943 bool "Memtest" 2944 depends on ARCH_USE_MEMTEST 2945 help 2946 This option adds a kernel parameter 'memtest', which allows memtest 2947 to be set and executed. 2948 memtest=0, mean disabled; -- default 2949 memtest=1, mean do 1 test pattern; 2950 ... 2951 memtest=17, mean do 17 test patterns. 2952 If you are unsure how to answer this question, answer N. 2953 2954 2955 2956config HYPERV_TESTING 2957 bool "Microsoft Hyper-V driver testing" 2958 default n 2959 depends on HYPERV && DEBUG_FS 2960 help 2961 Select this option to enable Hyper-V vmbus testing. 2962 2963endmenu # "Kernel Testing and Coverage" 2964 2965menu "Rust hacking" 2966 2967config RUST_DEBUG_ASSERTIONS 2968 bool "Debug assertions" 2969 depends on RUST 2970 help 2971 Enables rustc's `-Cdebug-assertions` codegen option. 2972 2973 This flag lets you turn `cfg(debug_assertions)` conditional 2974 compilation on or off. This can be used to enable extra debugging 2975 code in development but not in production. For example, it controls 2976 the behavior of the standard library's `debug_assert!` macro. 2977 2978 Note that this will apply to all Rust code, including `core`. 2979 2980 If unsure, say N. 2981 2982config RUST_OVERFLOW_CHECKS 2983 bool "Overflow checks" 2984 default y 2985 depends on RUST 2986 help 2987 Enables rustc's `-Coverflow-checks` codegen option. 2988 2989 This flag allows you to control the behavior of runtime integer 2990 overflow. When overflow-checks are enabled, a Rust panic will occur 2991 on overflow. 2992 2993 Note that this will apply to all Rust code, including `core`. 2994 2995 If unsure, say Y. 2996 2997config RUST_BUILD_ASSERT_ALLOW 2998 bool "Allow unoptimized build-time assertions" 2999 depends on RUST 3000 help 3001 Controls how are `build_error!` and `build_assert!` handled during build. 3002 3003 If calls to them exist in the binary, it may indicate a violated invariant 3004 or that the optimizer failed to verify the invariant during compilation. 3005 3006 This should not happen, thus by default the build is aborted. However, 3007 as an escape hatch, you can choose Y here to ignore them during build 3008 and let the check be carried at runtime (with `panic!` being called if 3009 the check fails). 3010 3011 If unsure, say N. 3012 3013endmenu # "Rust" 3014 3015endmenu # Kernel hacking 3016