1# SPDX-License-Identifier: GPL-2.0-only 2menu "Kernel hacking" 3 4menu "printk and dmesg options" 5 6config PRINTK_TIME 7 bool "Show timing information on printks" 8 depends on PRINTK 9 help 10 Selecting this option causes time stamps of the printk() 11 messages to be added to the output of the syslog() system 12 call and at the console. 13 14 The timestamp is always recorded internally, and exported 15 to /dev/kmsg. This flag just specifies if the timestamp should 16 be included, not that the timestamp is recorded. 17 18 The behavior is also controlled by the kernel command line 19 parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst 20 21config PRINTK_CALLER 22 bool "Show caller information on printks" 23 depends on PRINTK 24 help 25 Selecting this option causes printk() to add a caller "thread id" (if 26 in task context) or a caller "processor id" (if not in task context) 27 to every message. 28 29 This option is intended for environments where multiple threads 30 concurrently call printk() for many times, for it is difficult to 31 interpret without knowing where these lines (or sometimes individual 32 line which was divided into multiple lines due to race) came from. 33 34 Since toggling after boot makes the code racy, currently there is 35 no option to enable/disable at the kernel command line parameter or 36 sysfs interface. 37 38config STACKTRACE_BUILD_ID 39 bool "Show build ID information in stacktraces" 40 depends on PRINTK 41 help 42 Selecting this option adds build ID information for symbols in 43 stacktraces printed with the printk format '%p[SR]b'. 44 45 This option is intended for distros where debuginfo is not easily 46 accessible but can be downloaded given the build ID of the vmlinux or 47 kernel module where the function is located. 48 49config CONSOLE_LOGLEVEL_DEFAULT 50 int "Default console loglevel (1-15)" 51 range 1 15 52 default "7" 53 help 54 Default loglevel to determine what will be printed on the console. 55 56 Setting a default here is equivalent to passing in loglevel=<x> in 57 the kernel bootargs. loglevel=<x> continues to override whatever 58 value is specified here as well. 59 60 Note: This does not affect the log level of un-prefixed printk() 61 usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT 62 option. 63 64config CONSOLE_LOGLEVEL_QUIET 65 int "quiet console loglevel (1-15)" 66 range 1 15 67 default "4" 68 help 69 loglevel to use when "quiet" is passed on the kernel commandline. 70 71 When "quiet" is passed on the kernel commandline this loglevel 72 will be used as the loglevel. IOW passing "quiet" will be the 73 equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>" 74 75config MESSAGE_LOGLEVEL_DEFAULT 76 int "Default message log level (1-7)" 77 range 1 7 78 default "4" 79 help 80 Default log level for printk statements with no specified priority. 81 82 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks 83 that are auditing their logs closely may want to set it to a lower 84 priority. 85 86 Note: This does not affect what message level gets printed on the console 87 by default. To change that, use loglevel=<x> in the kernel bootargs, 88 or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value. 89 90config BOOT_PRINTK_DELAY 91 bool "Delay each boot printk message by N milliseconds" 92 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY 93 help 94 This build option allows you to read kernel boot messages 95 by inserting a short delay after each one. The delay is 96 specified in milliseconds on the kernel command line, 97 using "boot_delay=N". 98 99 It is likely that you would also need to use "lpj=M" to preset 100 the "loops per jiffie" value. 101 See a previous boot log for the "lpj" value to use for your 102 system, and then set "lpj=M" before setting "boot_delay=N". 103 NOTE: Using this option may adversely affect SMP systems. 104 I.e., processors other than the first one may not boot up. 105 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect 106 what it believes to be lockup conditions. 107 108config DYNAMIC_DEBUG 109 bool "Enable dynamic printk() support" 110 default n 111 depends on PRINTK 112 depends on (DEBUG_FS || PROC_FS) 113 select DYNAMIC_DEBUG_CORE 114 help 115 116 Compiles debug level messages into the kernel, which would not 117 otherwise be available at runtime. These messages can then be 118 enabled/disabled based on various levels of scope - per source file, 119 function, module, format string, and line number. This mechanism 120 implicitly compiles in all pr_debug() and dev_dbg() calls, which 121 enlarges the kernel text size by about 2%. 122 123 If a source file is compiled with DEBUG flag set, any 124 pr_debug() calls in it are enabled by default, but can be 125 disabled at runtime as below. Note that DEBUG flag is 126 turned on by many CONFIG_*DEBUG* options. 127 128 Usage: 129 130 Dynamic debugging is controlled via the 'dynamic_debug/control' file, 131 which is contained in the 'debugfs' filesystem or procfs. 132 Thus, the debugfs or procfs filesystem must first be mounted before 133 making use of this feature. 134 We refer the control file as: <debugfs>/dynamic_debug/control. This 135 file contains a list of the debug statements that can be enabled. The 136 format for each line of the file is: 137 138 filename:lineno [module]function flags format 139 140 filename : source file of the debug statement 141 lineno : line number of the debug statement 142 module : module that contains the debug statement 143 function : function that contains the debug statement 144 flags : '=p' means the line is turned 'on' for printing 145 format : the format used for the debug statement 146 147 From a live system: 148 149 nullarbor:~ # cat <debugfs>/dynamic_debug/control 150 # filename:lineno [module]function flags format 151 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012" 152 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012" 153 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012" 154 155 Example usage: 156 157 // enable the message at line 1603 of file svcsock.c 158 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' > 159 <debugfs>/dynamic_debug/control 160 161 // enable all the messages in file svcsock.c 162 nullarbor:~ # echo -n 'file svcsock.c +p' > 163 <debugfs>/dynamic_debug/control 164 165 // enable all the messages in the NFS server module 166 nullarbor:~ # echo -n 'module nfsd +p' > 167 <debugfs>/dynamic_debug/control 168 169 // enable all 12 messages in the function svc_process() 170 nullarbor:~ # echo -n 'func svc_process +p' > 171 <debugfs>/dynamic_debug/control 172 173 // disable all 12 messages in the function svc_process() 174 nullarbor:~ # echo -n 'func svc_process -p' > 175 <debugfs>/dynamic_debug/control 176 177 See Documentation/admin-guide/dynamic-debug-howto.rst for additional 178 information. 179 180config DYNAMIC_DEBUG_CORE 181 bool "Enable core function of dynamic debug support" 182 depends on PRINTK 183 depends on (DEBUG_FS || PROC_FS) 184 help 185 Enable core functional support of dynamic debug. It is useful 186 when you want to tie dynamic debug to your kernel modules with 187 DYNAMIC_DEBUG_MODULE defined for each of them, especially for 188 the case of embedded system where the kernel image size is 189 sensitive for people. 190 191config SYMBOLIC_ERRNAME 192 bool "Support symbolic error names in printf" 193 default y if PRINTK 194 help 195 If you say Y here, the kernel's printf implementation will 196 be able to print symbolic error names such as ENOSPC instead 197 of the number 28. It makes the kernel image slightly larger 198 (about 3KB), but can make the kernel logs easier to read. 199 200config DEBUG_BUGVERBOSE 201 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT 202 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE) 203 default y 204 help 205 Say Y here to make BUG() panics output the file name and line number 206 of the BUG call as well as the EIP and oops trace. This aids 207 debugging but costs about 70-100K of memory. 208 209endmenu # "printk and dmesg options" 210 211config DEBUG_KERNEL 212 bool "Kernel debugging" 213 help 214 Say Y here if you are developing drivers or trying to debug and 215 identify kernel problems. 216 217config DEBUG_MISC 218 bool "Miscellaneous debug code" 219 default DEBUG_KERNEL 220 depends on DEBUG_KERNEL 221 help 222 Say Y here if you need to enable miscellaneous debug code that should 223 be under a more specific debug option but isn't. 224 225menu "Compile-time checks and compiler options" 226 227config DEBUG_INFO 228 bool 229 help 230 A kernel debug info option other than "None" has been selected 231 in the "Debug information" choice below, indicating that debug 232 information will be generated for build targets. 233 234# Clang generates .uleb128 with label differences for DWARF v5, a feature that 235# older binutils ports do not support when utilizing RISC-V style linker 236# relaxation: https://sourceware.org/bugzilla/show_bug.cgi?id=27215 237config AS_HAS_NON_CONST_ULEB128 238 def_bool $(as-instr,.uleb128 .Lexpr_end4 - .Lexpr_start3\n.Lexpr_start3:\n.Lexpr_end4:) 239 240choice 241 prompt "Debug information" 242 depends on DEBUG_KERNEL 243 help 244 Selecting something other than "None" results in a kernel image 245 that will include debugging info resulting in a larger kernel image. 246 This adds debug symbols to the kernel and modules (gcc -g), and 247 is needed if you intend to use kernel crashdump or binary object 248 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 249 250 Choose which version of DWARF debug info to emit. If unsure, 251 select "Toolchain default". 252 253config DEBUG_INFO_NONE 254 bool "Disable debug information" 255 help 256 Do not build the kernel with debugging information, which will 257 result in a faster and smaller build. 258 259config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT 260 bool "Rely on the toolchain's implicit default DWARF version" 261 select DEBUG_INFO 262 depends on !CC_IS_CLANG || AS_IS_LLVM || CLANG_VERSION < 140000 || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128) 263 help 264 The implicit default version of DWARF debug info produced by a 265 toolchain changes over time. 266 267 This can break consumers of the debug info that haven't upgraded to 268 support newer revisions, and prevent testing newer versions, but 269 those should be less common scenarios. 270 271config DEBUG_INFO_DWARF4 272 bool "Generate DWARF Version 4 debuginfo" 273 select DEBUG_INFO 274 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502) 275 help 276 Generate DWARF v4 debug info. This requires gcc 4.5+, binutils 2.35.2 277 if using clang without clang's integrated assembler, and gdb 7.0+. 278 279 If you have consumers of DWARF debug info that are not ready for 280 newer revisions of DWARF, you may wish to choose this or have your 281 config select this. 282 283config DEBUG_INFO_DWARF5 284 bool "Generate DWARF Version 5 debuginfo" 285 select DEBUG_INFO 286 depends on !ARCH_HAS_BROKEN_DWARF5 287 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128) 288 help 289 Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc 290 5.0+ accepts the -gdwarf-5 flag but only had partial support for some 291 draft features until 7.0), and gdb 8.0+. 292 293 Changes to the structure of debug info in Version 5 allow for around 294 15-18% savings in resulting image and debug info section sizes as 295 compared to DWARF Version 4. DWARF Version 5 standardizes previous 296 extensions such as accelerators for symbol indexing and the format 297 for fission (.dwo/.dwp) files. Users may not want to select this 298 config if they rely on tooling that has not yet been updated to 299 support DWARF Version 5. 300 301endchoice # "Debug information" 302 303if DEBUG_INFO 304 305config DEBUG_INFO_REDUCED 306 bool "Reduce debugging information" 307 help 308 If you say Y here gcc is instructed to generate less debugging 309 information for structure types. This means that tools that 310 need full debugging information (like kgdb or systemtap) won't 311 be happy. But if you merely need debugging information to 312 resolve line numbers there is no loss. Advantage is that 313 build directory object sizes shrink dramatically over a full 314 DEBUG_INFO build and compile times are reduced too. 315 Only works with newer gcc versions. 316 317choice 318 prompt "Compressed Debug information" 319 help 320 Compress the resulting debug info. Results in smaller debug info sections, 321 but requires that consumers are able to decompress the results. 322 323 If unsure, choose DEBUG_INFO_COMPRESSED_NONE. 324 325config DEBUG_INFO_COMPRESSED_NONE 326 bool "Don't compress debug information" 327 help 328 Don't compress debug info sections. 329 330config DEBUG_INFO_COMPRESSED_ZLIB 331 bool "Compress debugging information with zlib" 332 depends on $(cc-option,-gz=zlib) 333 depends on $(ld-option,--compress-debug-sections=zlib) 334 help 335 Compress the debug information using zlib. Requires GCC 5.0+ or Clang 336 5.0+, binutils 2.26+, and zlib. 337 338 Users of dpkg-deb via scripts/package/builddeb may find an increase in 339 size of their debug .deb packages with this config set, due to the 340 debug info being compressed with zlib, then the object files being 341 recompressed with a different compression scheme. But this is still 342 preferable to setting $KDEB_COMPRESS to "none" which would be even 343 larger. 344 345config DEBUG_INFO_COMPRESSED_ZSTD 346 bool "Compress debugging information with zstd" 347 depends on $(cc-option,-gz=zstd) 348 depends on $(ld-option,--compress-debug-sections=zstd) 349 help 350 Compress the debug information using zstd. This may provide better 351 compression than zlib, for about the same time costs, but requires newer 352 toolchain support. Requires GCC 13.0+ or Clang 16.0+, binutils 2.40+, and 353 zstd. 354 355endchoice # "Compressed Debug information" 356 357config DEBUG_INFO_SPLIT 358 bool "Produce split debuginfo in .dwo files" 359 depends on $(cc-option,-gsplit-dwarf) 360 # RISC-V linker relaxation + -gsplit-dwarf has issues with LLVM and GCC 361 # prior to 12.x: 362 # https://github.com/llvm/llvm-project/issues/56642 363 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99090 364 depends on !RISCV || GCC_VERSION >= 120000 365 help 366 Generate debug info into separate .dwo files. This significantly 367 reduces the build directory size for builds with DEBUG_INFO, 368 because it stores the information only once on disk in .dwo 369 files instead of multiple times in object files and executables. 370 In addition the debug information is also compressed. 371 372 Requires recent gcc (4.7+) and recent gdb/binutils. 373 Any tool that packages or reads debug information would need 374 to know about the .dwo files and include them. 375 Incompatible with older versions of ccache. 376 377config DEBUG_INFO_BTF 378 bool "Generate BTF typeinfo" 379 depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED 380 depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST 381 depends on BPF_SYSCALL 382 depends on !DEBUG_INFO_DWARF5 || PAHOLE_VERSION >= 121 383 # pahole uses elfutils, which does not have support for Hexagon relocations 384 depends on !HEXAGON 385 help 386 Generate deduplicated BTF type information from DWARF debug info. 387 Turning this on expects presence of pahole tool, which will convert 388 DWARF type info into equivalent deduplicated BTF type info. 389 390config PAHOLE_HAS_SPLIT_BTF 391 def_bool PAHOLE_VERSION >= 119 392 393config PAHOLE_HAS_BTF_TAG 394 def_bool PAHOLE_VERSION >= 123 395 depends on CC_IS_CLANG 396 help 397 Decide whether pahole emits btf_tag attributes (btf_type_tag and 398 btf_decl_tag) or not. Currently only clang compiler implements 399 these attributes, so make the config depend on CC_IS_CLANG. 400 401config PAHOLE_HAS_LANG_EXCLUDE 402 def_bool PAHOLE_VERSION >= 124 403 help 404 Support for the --lang_exclude flag which makes pahole exclude 405 compilation units from the supplied language. Used in Kbuild to 406 omit Rust CUs which are not supported in version 1.24 of pahole, 407 otherwise it would emit malformed kernel and module binaries when 408 using DEBUG_INFO_BTF_MODULES. 409 410config DEBUG_INFO_BTF_MODULES 411 def_bool y 412 depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF 413 help 414 Generate compact split BTF type information for kernel modules. 415 416config MODULE_ALLOW_BTF_MISMATCH 417 bool "Allow loading modules with non-matching BTF type info" 418 depends on DEBUG_INFO_BTF_MODULES 419 help 420 For modules whose split BTF does not match vmlinux, load without 421 BTF rather than refusing to load. The default behavior with 422 module BTF enabled is to reject modules with such mismatches; 423 this option will still load module BTF where possible but ignore 424 it when a mismatch is found. 425 426config GDB_SCRIPTS 427 bool "Provide GDB scripts for kernel debugging" 428 help 429 This creates the required links to GDB helper scripts in the 430 build directory. If you load vmlinux into gdb, the helper 431 scripts will be automatically imported by gdb as well, and 432 additional functions are available to analyze a Linux kernel 433 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst 434 for further details. 435 436endif # DEBUG_INFO 437 438config FRAME_WARN 439 int "Warn for stack frames larger than" 440 range 0 8192 441 default 0 if KMSAN 442 default 2048 if GCC_PLUGIN_LATENT_ENTROPY 443 default 2048 if PARISC 444 default 1536 if (!64BIT && XTENSA) 445 default 1280 if KASAN && !64BIT 446 default 1024 if !64BIT 447 default 2048 if 64BIT 448 help 449 Tell the compiler to warn at build time for stack frames larger than this. 450 Setting this too low will cause a lot of warnings. 451 Setting it to 0 disables the warning. 452 453config STRIP_ASM_SYMS 454 bool "Strip assembler-generated symbols during link" 455 default n 456 help 457 Strip internal assembler-generated symbols during a link (symbols 458 that look like '.Lxxx') so they don't pollute the output of 459 get_wchan() and suchlike. 460 461config READABLE_ASM 462 bool "Generate readable assembler code" 463 depends on DEBUG_KERNEL 464 depends on CC_IS_GCC 465 help 466 Disable some compiler optimizations that tend to generate human unreadable 467 assembler output. This may make the kernel slightly slower, but it helps 468 to keep kernel developers who have to stare a lot at assembler listings 469 sane. 470 471config HEADERS_INSTALL 472 bool "Install uapi headers to usr/include" 473 depends on !UML 474 help 475 This option will install uapi headers (headers exported to user-space) 476 into the usr/include directory for use during the kernel build. 477 This is unneeded for building the kernel itself, but needed for some 478 user-space program samples. It is also needed by some features such 479 as uapi header sanity checks. 480 481config DEBUG_SECTION_MISMATCH 482 bool "Enable full Section mismatch analysis" 483 depends on CC_IS_GCC 484 help 485 The section mismatch analysis checks if there are illegal 486 references from one section to another section. 487 During linktime or runtime, some sections are dropped; 488 any use of code/data previously in these sections would 489 most likely result in an oops. 490 In the code, functions and variables are annotated with 491 __init,, etc. (see the full list in include/linux/init.h), 492 which results in the code/data being placed in specific sections. 493 The section mismatch analysis is always performed after a full 494 kernel build, and enabling this option causes the following 495 additional step to occur: 496 - Add the option -fno-inline-functions-called-once to gcc commands. 497 When inlining a function annotated with __init in a non-init 498 function, we would lose the section information and thus 499 the analysis would not catch the illegal reference. 500 This option tells gcc to inline less (but it does result in 501 a larger kernel). 502 503config SECTION_MISMATCH_WARN_ONLY 504 bool "Make section mismatch errors non-fatal" 505 default y 506 help 507 If you say N here, the build process will fail if there are any 508 section mismatch, instead of just throwing warnings. 509 510 If unsure, say Y. 511 512config DEBUG_FORCE_FUNCTION_ALIGN_64B 513 bool "Force all function address 64B aligned" 514 depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC || RISCV || S390) 515 select FUNCTION_ALIGNMENT_64B 516 help 517 There are cases that a commit from one domain changes the function 518 address alignment of other domains, and cause magic performance 519 bump (regression or improvement). Enable this option will help to 520 verify if the bump is caused by function alignment changes, while 521 it will slightly increase the kernel size and affect icache usage. 522 523 It is mainly for debug and performance tuning use. 524 525# 526# Select this config option from the architecture Kconfig, if it 527# is preferred to always offer frame pointers as a config 528# option on the architecture (regardless of KERNEL_DEBUG): 529# 530config ARCH_WANT_FRAME_POINTERS 531 bool 532 533config FRAME_POINTER 534 bool "Compile the kernel with frame pointers" 535 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS 536 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 537 help 538 If you say Y here the resulting kernel image will be slightly 539 larger and slower, but it gives very useful debugging information 540 in case of kernel bugs. (precise oopses/stacktraces/warnings) 541 542config OBJTOOL 543 bool 544 545config STACK_VALIDATION 546 bool "Compile-time stack metadata validation" 547 depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER 548 select OBJTOOL 549 default n 550 help 551 Validate frame pointer rules at compile-time. This helps ensure that 552 runtime stack traces are more reliable. 553 554 For more information, see 555 tools/objtool/Documentation/objtool.txt. 556 557config NOINSTR_VALIDATION 558 bool 559 depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY 560 select OBJTOOL 561 default y 562 563config VMLINUX_MAP 564 bool "Generate vmlinux.map file when linking" 565 depends on EXPERT 566 help 567 Selecting this option will pass "-Map=vmlinux.map" to ld 568 when linking vmlinux. That file can be useful for verifying 569 and debugging magic section games, and for seeing which 570 pieces of code get eliminated with 571 CONFIG_LD_DEAD_CODE_DATA_ELIMINATION. 572 573config DEBUG_FORCE_WEAK_PER_CPU 574 bool "Force weak per-cpu definitions" 575 depends on DEBUG_KERNEL 576 help 577 s390 and alpha require percpu variables in modules to be 578 defined weak to work around addressing range issue which 579 puts the following two restrictions on percpu variable 580 definitions. 581 582 1. percpu symbols must be unique whether static or not 583 2. percpu variables can't be defined inside a function 584 585 To ensure that generic code follows the above rules, this 586 option forces all percpu variables to be defined as weak. 587 588endmenu # "Compiler options" 589 590menu "Generic Kernel Debugging Instruments" 591 592config MAGIC_SYSRQ 593 bool "Magic SysRq key" 594 depends on !UML 595 help 596 If you say Y here, you will have some control over the system even 597 if the system crashes for example during kernel debugging (e.g., you 598 will be able to flush the buffer cache to disk, reboot the system 599 immediately or dump some status information). This is accomplished 600 by pressing various keys while holding SysRq (Alt+PrintScreen). It 601 also works on a serial console (on PC hardware at least), if you 602 send a BREAK and then within 5 seconds a command keypress. The 603 keys are documented in <file:Documentation/admin-guide/sysrq.rst>. 604 Don't say Y unless you really know what this hack does. 605 606config MAGIC_SYSRQ_DEFAULT_ENABLE 607 hex "Enable magic SysRq key functions by default" 608 depends on MAGIC_SYSRQ 609 default 0x1 610 help 611 Specifies which SysRq key functions are enabled by default. 612 This may be set to 1 or 0 to enable or disable them all, or 613 to a bitmask as described in Documentation/admin-guide/sysrq.rst. 614 615config MAGIC_SYSRQ_SERIAL 616 bool "Enable magic SysRq key over serial" 617 depends on MAGIC_SYSRQ 618 default y 619 help 620 Many embedded boards have a disconnected TTL level serial which can 621 generate some garbage that can lead to spurious false sysrq detects. 622 This option allows you to decide whether you want to enable the 623 magic SysRq key. 624 625config MAGIC_SYSRQ_SERIAL_SEQUENCE 626 string "Char sequence that enables magic SysRq over serial" 627 depends on MAGIC_SYSRQ_SERIAL 628 default "" 629 help 630 Specifies a sequence of characters that can follow BREAK to enable 631 SysRq on a serial console. 632 633 If unsure, leave an empty string and the option will not be enabled. 634 635config DEBUG_FS 636 bool "Debug Filesystem" 637 help 638 debugfs is a virtual file system that kernel developers use to put 639 debugging files into. Enable this option to be able to read and 640 write to these files. 641 642 For detailed documentation on the debugfs API, see 643 Documentation/filesystems/. 644 645 If unsure, say N. 646 647choice 648 prompt "Debugfs default access" 649 depends on DEBUG_FS 650 default DEBUG_FS_ALLOW_ALL 651 help 652 This selects the default access restrictions for debugfs. 653 It can be overridden with kernel command line option 654 debugfs=[on,no-mount,off]. The restrictions apply for API access 655 and filesystem registration. 656 657config DEBUG_FS_ALLOW_ALL 658 bool "Access normal" 659 help 660 No restrictions apply. Both API and filesystem registration 661 is on. This is the normal default operation. 662 663config DEBUG_FS_DISALLOW_MOUNT 664 bool "Do not register debugfs as filesystem" 665 help 666 The API is open but filesystem is not loaded. Clients can still do 667 their work and read with debug tools that do not need 668 debugfs filesystem. 669 670config DEBUG_FS_ALLOW_NONE 671 bool "No access" 672 help 673 Access is off. Clients get -PERM when trying to create nodes in 674 debugfs tree and debugfs is not registered as a filesystem. 675 Client can then back-off or continue without debugfs access. 676 677endchoice 678 679source "lib/Kconfig.kgdb" 680source "lib/Kconfig.ubsan" 681source "lib/Kconfig.kcsan" 682 683endmenu 684 685menu "Networking Debugging" 686 687source "net/Kconfig.debug" 688 689endmenu # "Networking Debugging" 690 691menu "Memory Debugging" 692 693source "mm/Kconfig.debug" 694 695config DEBUG_OBJECTS 696 bool "Debug object operations" 697 depends on DEBUG_KERNEL 698 help 699 If you say Y here, additional code will be inserted into the 700 kernel to track the life time of various objects and validate 701 the operations on those objects. 702 703config DEBUG_OBJECTS_SELFTEST 704 bool "Debug objects selftest" 705 depends on DEBUG_OBJECTS 706 help 707 This enables the selftest of the object debug code. 708 709config DEBUG_OBJECTS_FREE 710 bool "Debug objects in freed memory" 711 depends on DEBUG_OBJECTS 712 help 713 This enables checks whether a k/v free operation frees an area 714 which contains an object which has not been deactivated 715 properly. This can make kmalloc/kfree-intensive workloads 716 much slower. 717 718config DEBUG_OBJECTS_TIMERS 719 bool "Debug timer objects" 720 depends on DEBUG_OBJECTS 721 help 722 If you say Y here, additional code will be inserted into the 723 timer routines to track the life time of timer objects and 724 validate the timer operations. 725 726config DEBUG_OBJECTS_WORK 727 bool "Debug work objects" 728 depends on DEBUG_OBJECTS 729 help 730 If you say Y here, additional code will be inserted into the 731 work queue routines to track the life time of work objects and 732 validate the work operations. 733 734config DEBUG_OBJECTS_RCU_HEAD 735 bool "Debug RCU callbacks objects" 736 depends on DEBUG_OBJECTS 737 help 738 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 739 740config DEBUG_OBJECTS_PERCPU_COUNTER 741 bool "Debug percpu counter objects" 742 depends on DEBUG_OBJECTS 743 help 744 If you say Y here, additional code will be inserted into the 745 percpu counter routines to track the life time of percpu counter 746 objects and validate the percpu counter operations. 747 748config DEBUG_OBJECTS_ENABLE_DEFAULT 749 int "debug_objects bootup default value (0-1)" 750 range 0 1 751 default "1" 752 depends on DEBUG_OBJECTS 753 help 754 Debug objects boot parameter default value 755 756config SHRINKER_DEBUG 757 bool "Enable shrinker debugging support" 758 depends on DEBUG_FS 759 help 760 Say Y to enable the shrinker debugfs interface which provides 761 visibility into the kernel memory shrinkers subsystem. 762 Disable it to avoid an extra memory footprint. 763 764config DEBUG_STACK_USAGE 765 bool "Stack utilization instrumentation" 766 depends on DEBUG_KERNEL 767 help 768 Enables the display of the minimum amount of free stack which each 769 task has ever had available in the sysrq-T and sysrq-P debug output. 770 Also emits a message to dmesg when a process exits if that process 771 used more stack space than previously exiting processes. 772 773 This option will slow down process creation somewhat. 774 775config SCHED_STACK_END_CHECK 776 bool "Detect stack corruption on calls to schedule()" 777 depends on DEBUG_KERNEL 778 default n 779 help 780 This option checks for a stack overrun on calls to schedule(). 781 If the stack end location is found to be over written always panic as 782 the content of the corrupted region can no longer be trusted. 783 This is to ensure no erroneous behaviour occurs which could result in 784 data corruption or a sporadic crash at a later stage once the region 785 is examined. The runtime overhead introduced is minimal. 786 787config ARCH_HAS_DEBUG_VM_PGTABLE 788 bool 789 help 790 An architecture should select this when it can successfully 791 build and run DEBUG_VM_PGTABLE. 792 793config DEBUG_VM_IRQSOFF 794 def_bool DEBUG_VM && !PREEMPT_RT 795 796config DEBUG_VM 797 bool "Debug VM" 798 depends on DEBUG_KERNEL 799 help 800 Enable this to turn on extended checks in the virtual-memory system 801 that may impact performance. 802 803 If unsure, say N. 804 805config DEBUG_VM_SHOOT_LAZIES 806 bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation" 807 depends on DEBUG_VM 808 depends on MMU_LAZY_TLB_SHOOTDOWN 809 help 810 Enable additional IPIs that ensure lazy tlb mm references are removed 811 before the mm is freed. 812 813 If unsure, say N. 814 815config DEBUG_VM_MAPLE_TREE 816 bool "Debug VM maple trees" 817 depends on DEBUG_VM 818 select DEBUG_MAPLE_TREE 819 help 820 Enable VM maple tree debugging information and extra validations. 821 822 If unsure, say N. 823 824config DEBUG_VM_RB 825 bool "Debug VM red-black trees" 826 depends on DEBUG_VM 827 help 828 Enable VM red-black tree debugging information and extra validations. 829 830 If unsure, say N. 831 832config DEBUG_VM_PGFLAGS 833 bool "Debug page-flags operations" 834 depends on DEBUG_VM 835 help 836 Enables extra validation on page flags operations. 837 838 If unsure, say N. 839 840config DEBUG_VM_PGTABLE 841 bool "Debug arch page table for semantics compliance" 842 depends on MMU 843 depends on ARCH_HAS_DEBUG_VM_PGTABLE 844 default y if DEBUG_VM 845 help 846 This option provides a debug method which can be used to test 847 architecture page table helper functions on various platforms in 848 verifying if they comply with expected generic MM semantics. This 849 will help architecture code in making sure that any changes or 850 new additions of these helpers still conform to expected 851 semantics of the generic MM. Platforms will have to opt in for 852 this through ARCH_HAS_DEBUG_VM_PGTABLE. 853 854 If unsure, say N. 855 856config ARCH_HAS_DEBUG_VIRTUAL 857 bool 858 859config DEBUG_VIRTUAL 860 bool "Debug VM translations" 861 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL 862 help 863 Enable some costly sanity checks in virtual to page code. This can 864 catch mistakes with virt_to_page() and friends. 865 866 If unsure, say N. 867 868config DEBUG_NOMMU_REGIONS 869 bool "Debug the global anon/private NOMMU mapping region tree" 870 depends on DEBUG_KERNEL && !MMU 871 help 872 This option causes the global tree of anonymous and private mapping 873 regions to be regularly checked for invalid topology. 874 875config DEBUG_MEMORY_INIT 876 bool "Debug memory initialisation" if EXPERT 877 default !EXPERT 878 help 879 Enable this for additional checks during memory initialisation. 880 The sanity checks verify aspects of the VM such as the memory model 881 and other information provided by the architecture. Verbose 882 information will be printed at KERN_DEBUG loglevel depending 883 on the mminit_loglevel= command-line option. 884 885 If unsure, say Y 886 887config MEMORY_NOTIFIER_ERROR_INJECT 888 tristate "Memory hotplug notifier error injection module" 889 depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION 890 help 891 This option provides the ability to inject artificial errors to 892 memory hotplug notifier chain callbacks. It is controlled through 893 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 894 895 If the notifier call chain should be failed with some events 896 notified, write the error code to "actions/<notifier event>/error". 897 898 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 899 900 # cd /sys/kernel/debug/notifier-error-inject/memory 901 # echo -12 > actions/MEM_GOING_OFFLINE/error 902 # echo offline > /sys/devices/system/memory/memoryXXX/state 903 bash: echo: write error: Cannot allocate memory 904 905 To compile this code as a module, choose M here: the module will 906 be called memory-notifier-error-inject. 907 908 If unsure, say N. 909 910config DEBUG_PER_CPU_MAPS 911 bool "Debug access to per_cpu maps" 912 depends on DEBUG_KERNEL 913 depends on SMP 914 help 915 Say Y to verify that the per_cpu map being accessed has 916 been set up. This adds a fair amount of code to kernel memory 917 and decreases performance. 918 919 Say N if unsure. 920 921config DEBUG_KMAP_LOCAL 922 bool "Debug kmap_local temporary mappings" 923 depends on DEBUG_KERNEL && KMAP_LOCAL 924 help 925 This option enables additional error checking for the kmap_local 926 infrastructure. Disable for production use. 927 928config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 929 bool 930 931config DEBUG_KMAP_LOCAL_FORCE_MAP 932 bool "Enforce kmap_local temporary mappings" 933 depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 934 select KMAP_LOCAL 935 select DEBUG_KMAP_LOCAL 936 help 937 This option enforces temporary mappings through the kmap_local 938 mechanism for non-highmem pages and on non-highmem systems. 939 Disable this for production systems! 940 941config DEBUG_HIGHMEM 942 bool "Highmem debugging" 943 depends on DEBUG_KERNEL && HIGHMEM 944 select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 945 select DEBUG_KMAP_LOCAL 946 help 947 This option enables additional error checking for high memory 948 systems. Disable for production systems. 949 950config HAVE_DEBUG_STACKOVERFLOW 951 bool 952 953config DEBUG_STACKOVERFLOW 954 bool "Check for stack overflows" 955 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 956 help 957 Say Y here if you want to check for overflows of kernel, IRQ 958 and exception stacks (if your architecture uses them). This 959 option will show detailed messages if free stack space drops 960 below a certain limit. 961 962 These kinds of bugs usually occur when call-chains in the 963 kernel get too deep, especially when interrupts are 964 involved. 965 966 Use this in cases where you see apparently random memory 967 corruption, especially if it appears in 'struct thread_info' 968 969 If in doubt, say "N". 970 971config CODE_TAGGING 972 bool 973 select KALLSYMS 974 975config MEM_ALLOC_PROFILING 976 bool "Enable memory allocation profiling" 977 default n 978 depends on PROC_FS 979 depends on !DEBUG_FORCE_WEAK_PER_CPU 980 select CODE_TAGGING 981 select PAGE_EXTENSION 982 select SLAB_OBJ_EXT 983 help 984 Track allocation source code and record total allocation size 985 initiated at that code location. The mechanism can be used to track 986 memory leaks with a low performance and memory impact. 987 988config MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT 989 bool "Enable memory allocation profiling by default" 990 default y 991 depends on MEM_ALLOC_PROFILING 992 993config MEM_ALLOC_PROFILING_DEBUG 994 bool "Memory allocation profiler debugging" 995 default n 996 depends on MEM_ALLOC_PROFILING 997 select MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT 998 help 999 Adds warnings with helpful error messages for memory allocation 1000 profiling. 1001 1002source "lib/Kconfig.kasan" 1003source "lib/Kconfig.kfence" 1004source "lib/Kconfig.kmsan" 1005 1006endmenu # "Memory Debugging" 1007 1008config DEBUG_SHIRQ 1009 bool "Debug shared IRQ handlers" 1010 depends on DEBUG_KERNEL 1011 help 1012 Enable this to generate a spurious interrupt just before a shared 1013 interrupt handler is deregistered (generating one when registering 1014 is currently disabled). Drivers need to handle this correctly. Some 1015 don't and need to be caught. 1016 1017menu "Debug Oops, Lockups and Hangs" 1018 1019config PANIC_ON_OOPS 1020 bool "Panic on Oops" 1021 help 1022 Say Y here to enable the kernel to panic when it oopses. This 1023 has the same effect as setting oops=panic on the kernel command 1024 line. 1025 1026 This feature is useful to ensure that the kernel does not do 1027 anything erroneous after an oops which could result in data 1028 corruption or other issues. 1029 1030 Say N if unsure. 1031 1032config PANIC_ON_OOPS_VALUE 1033 int 1034 range 0 1 1035 default 0 if !PANIC_ON_OOPS 1036 default 1 if PANIC_ON_OOPS 1037 1038config PANIC_TIMEOUT 1039 int "panic timeout" 1040 default 0 1041 help 1042 Set the timeout value (in seconds) until a reboot occurs when 1043 the kernel panics. If n = 0, then we wait forever. A timeout 1044 value n > 0 will wait n seconds before rebooting, while a timeout 1045 value n < 0 will reboot immediately. 1046 1047config LOCKUP_DETECTOR 1048 bool 1049 1050config SOFTLOCKUP_DETECTOR 1051 bool "Detect Soft Lockups" 1052 depends on DEBUG_KERNEL && !S390 1053 select LOCKUP_DETECTOR 1054 help 1055 Say Y here to enable the kernel to act as a watchdog to detect 1056 soft lockups. 1057 1058 Softlockups are bugs that cause the kernel to loop in kernel 1059 mode for more than 20 seconds, without giving other tasks a 1060 chance to run. The current stack trace is displayed upon 1061 detection and the system will stay locked up. 1062 1063config BOOTPARAM_SOFTLOCKUP_PANIC 1064 bool "Panic (Reboot) On Soft Lockups" 1065 depends on SOFTLOCKUP_DETECTOR 1066 help 1067 Say Y here to enable the kernel to panic on "soft lockups", 1068 which are bugs that cause the kernel to loop in kernel 1069 mode for more than 20 seconds (configurable using the watchdog_thresh 1070 sysctl), without giving other tasks a chance to run. 1071 1072 The panic can be used in combination with panic_timeout, 1073 to cause the system to reboot automatically after a 1074 lockup has been detected. This feature is useful for 1075 high-availability systems that have uptime guarantees and 1076 where a lockup must be resolved ASAP. 1077 1078 Say N if unsure. 1079 1080config HAVE_HARDLOCKUP_DETECTOR_BUDDY 1081 bool 1082 depends on SMP 1083 default y 1084 1085# 1086# Global switch whether to build a hardlockup detector at all. It is available 1087# only when the architecture supports at least one implementation. There are 1088# two exceptions. The hardlockup detector is never enabled on: 1089# 1090# s390: it reported many false positives there 1091# 1092# sparc64: has a custom implementation which is not using the common 1093# hardlockup command line options and sysctl interface. 1094# 1095config HARDLOCKUP_DETECTOR 1096 bool "Detect Hard Lockups" 1097 depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64 1098 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH 1099 imply HARDLOCKUP_DETECTOR_PERF 1100 imply HARDLOCKUP_DETECTOR_BUDDY 1101 imply HARDLOCKUP_DETECTOR_ARCH 1102 select LOCKUP_DETECTOR 1103 1104 help 1105 Say Y here to enable the kernel to act as a watchdog to detect 1106 hard lockups. 1107 1108 Hardlockups are bugs that cause the CPU to loop in kernel mode 1109 for more than 10 seconds, without letting other interrupts have a 1110 chance to run. The current stack trace is displayed upon detection 1111 and the system will stay locked up. 1112 1113# 1114# Note that arch-specific variants are always preferred. 1115# 1116config HARDLOCKUP_DETECTOR_PREFER_BUDDY 1117 bool "Prefer the buddy CPU hardlockup detector" 1118 depends on HARDLOCKUP_DETECTOR 1119 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY 1120 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1121 help 1122 Say Y here to prefer the buddy hardlockup detector over the perf one. 1123 1124 With the buddy detector, each CPU uses its softlockup hrtimer 1125 to check that the next CPU is processing hrtimer interrupts by 1126 verifying that a counter is increasing. 1127 1128 This hardlockup detector is useful on systems that don't have 1129 an arch-specific hardlockup detector or if resources needed 1130 for the hardlockup detector are better used for other things. 1131 1132config HARDLOCKUP_DETECTOR_PERF 1133 bool 1134 depends on HARDLOCKUP_DETECTOR 1135 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY 1136 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1137 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1138 1139config HARDLOCKUP_DETECTOR_BUDDY 1140 bool 1141 depends on HARDLOCKUP_DETECTOR 1142 depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY 1143 depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY 1144 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1145 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1146 1147config HARDLOCKUP_DETECTOR_ARCH 1148 bool 1149 depends on HARDLOCKUP_DETECTOR 1150 depends on HAVE_HARDLOCKUP_DETECTOR_ARCH 1151 help 1152 The arch-specific implementation of the hardlockup detector will 1153 be used. 1154 1155# 1156# Both the "perf" and "buddy" hardlockup detectors count hrtimer 1157# interrupts. This config enables functions managing this common code. 1158# 1159config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1160 bool 1161 select SOFTLOCKUP_DETECTOR 1162 1163# 1164# Enables a timestamp based low pass filter to compensate for perf based 1165# hard lockup detection which runs too fast due to turbo modes. 1166# 1167config HARDLOCKUP_CHECK_TIMESTAMP 1168 bool 1169 1170config BOOTPARAM_HARDLOCKUP_PANIC 1171 bool "Panic (Reboot) On Hard Lockups" 1172 depends on HARDLOCKUP_DETECTOR 1173 help 1174 Say Y here to enable the kernel to panic on "hard lockups", 1175 which are bugs that cause the kernel to loop in kernel 1176 mode with interrupts disabled for more than 10 seconds (configurable 1177 using the watchdog_thresh sysctl). 1178 1179 Say N if unsure. 1180 1181config DETECT_HUNG_TASK 1182 bool "Detect Hung Tasks" 1183 depends on DEBUG_KERNEL 1184 default SOFTLOCKUP_DETECTOR 1185 help 1186 Say Y here to enable the kernel to detect "hung tasks", 1187 which are bugs that cause the task to be stuck in 1188 uninterruptible "D" state indefinitely. 1189 1190 When a hung task is detected, the kernel will print the 1191 current stack trace (which you should report), but the 1192 task will stay in uninterruptible state. If lockdep is 1193 enabled then all held locks will also be reported. This 1194 feature has negligible overhead. 1195 1196config DEFAULT_HUNG_TASK_TIMEOUT 1197 int "Default timeout for hung task detection (in seconds)" 1198 depends on DETECT_HUNG_TASK 1199 default 120 1200 help 1201 This option controls the default timeout (in seconds) used 1202 to determine when a task has become non-responsive and should 1203 be considered hung. 1204 1205 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 1206 sysctl or by writing a value to 1207 /proc/sys/kernel/hung_task_timeout_secs. 1208 1209 A timeout of 0 disables the check. The default is two minutes. 1210 Keeping the default should be fine in most cases. 1211 1212config BOOTPARAM_HUNG_TASK_PANIC 1213 bool "Panic (Reboot) On Hung Tasks" 1214 depends on DETECT_HUNG_TASK 1215 help 1216 Say Y here to enable the kernel to panic on "hung tasks", 1217 which are bugs that cause the kernel to leave a task stuck 1218 in uninterruptible "D" state. 1219 1220 The panic can be used in combination with panic_timeout, 1221 to cause the system to reboot automatically after a 1222 hung task has been detected. This feature is useful for 1223 high-availability systems that have uptime guarantees and 1224 where a hung tasks must be resolved ASAP. 1225 1226 Say N if unsure. 1227 1228config WQ_WATCHDOG 1229 bool "Detect Workqueue Stalls" 1230 depends on DEBUG_KERNEL 1231 help 1232 Say Y here to enable stall detection on workqueues. If a 1233 worker pool doesn't make forward progress on a pending work 1234 item for over a given amount of time, 30s by default, a 1235 warning message is printed along with dump of workqueue 1236 state. This can be configured through kernel parameter 1237 "workqueue.watchdog_thresh" and its sysfs counterpart. 1238 1239config WQ_CPU_INTENSIVE_REPORT 1240 bool "Report per-cpu work items which hog CPU for too long" 1241 depends on DEBUG_KERNEL 1242 help 1243 Say Y here to enable reporting of concurrency-managed per-cpu work 1244 items that hog CPUs for longer than 1245 workqueue.cpu_intensive_thresh_us. Workqueue automatically 1246 detects and excludes them from concurrency management to prevent 1247 them from stalling other per-cpu work items. Occassional 1248 triggering may not necessarily indicate a problem. Repeated 1249 triggering likely indicates that the work item should be switched 1250 to use an unbound workqueue. 1251 1252config TEST_LOCKUP 1253 tristate "Test module to generate lockups" 1254 depends on m 1255 help 1256 This builds the "test_lockup" module that helps to make sure 1257 that watchdogs and lockup detectors are working properly. 1258 1259 Depending on module parameters it could emulate soft or hard 1260 lockup, "hung task", or locking arbitrary lock for a long time. 1261 Also it could generate series of lockups with cooling-down periods. 1262 1263 If unsure, say N. 1264 1265endmenu # "Debug lockups and hangs" 1266 1267menu "Scheduler Debugging" 1268 1269config SCHED_DEBUG 1270 bool "Collect scheduler debugging info" 1271 depends on DEBUG_KERNEL && DEBUG_FS 1272 default y 1273 help 1274 If you say Y here, the /sys/kernel/debug/sched file will be provided 1275 that can help debug the scheduler. The runtime overhead of this 1276 option is minimal. 1277 1278config SCHED_INFO 1279 bool 1280 default n 1281 1282config SCHEDSTATS 1283 bool "Collect scheduler statistics" 1284 depends on DEBUG_KERNEL && PROC_FS 1285 select SCHED_INFO 1286 help 1287 If you say Y here, additional code will be inserted into the 1288 scheduler and related routines to collect statistics about 1289 scheduler behavior and provide them in /proc/schedstat. These 1290 stats may be useful for both tuning and debugging the scheduler 1291 If you aren't debugging the scheduler or trying to tune a specific 1292 application, you can say N to avoid the very slight overhead 1293 this adds. 1294 1295endmenu 1296 1297config DEBUG_TIMEKEEPING 1298 bool "Enable extra timekeeping sanity checking" 1299 help 1300 This option will enable additional timekeeping sanity checks 1301 which may be helpful when diagnosing issues where timekeeping 1302 problems are suspected. 1303 1304 This may include checks in the timekeeping hotpaths, so this 1305 option may have a (very small) performance impact to some 1306 workloads. 1307 1308 If unsure, say N. 1309 1310config DEBUG_PREEMPT 1311 bool "Debug preemptible kernel" 1312 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1313 help 1314 If you say Y here then the kernel will use a debug variant of the 1315 commonly used smp_processor_id() function and will print warnings 1316 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1317 will detect preemption count underflows. 1318 1319 This option has potential to introduce high runtime overhead, 1320 depending on workload as it triggers debugging routines for each 1321 this_cpu operation. It should only be used for debugging purposes. 1322 1323menu "Lock Debugging (spinlocks, mutexes, etc...)" 1324 1325config LOCK_DEBUGGING_SUPPORT 1326 bool 1327 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1328 default y 1329 1330config PROVE_LOCKING 1331 bool "Lock debugging: prove locking correctness" 1332 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1333 select LOCKDEP 1334 select DEBUG_SPINLOCK 1335 select DEBUG_MUTEXES if !PREEMPT_RT 1336 select DEBUG_RT_MUTEXES if RT_MUTEXES 1337 select DEBUG_RWSEMS if !PREEMPT_RT 1338 select DEBUG_WW_MUTEX_SLOWPATH 1339 select DEBUG_LOCK_ALLOC 1340 select PREEMPT_COUNT if !ARCH_NO_PREEMPT 1341 select TRACE_IRQFLAGS 1342 default n 1343 help 1344 This feature enables the kernel to prove that all locking 1345 that occurs in the kernel runtime is mathematically 1346 correct: that under no circumstance could an arbitrary (and 1347 not yet triggered) combination of observed locking 1348 sequences (on an arbitrary number of CPUs, running an 1349 arbitrary number of tasks and interrupt contexts) cause a 1350 deadlock. 1351 1352 In short, this feature enables the kernel to report locking 1353 related deadlocks before they actually occur. 1354 1355 The proof does not depend on how hard and complex a 1356 deadlock scenario would be to trigger: how many 1357 participant CPUs, tasks and irq-contexts would be needed 1358 for it to trigger. The proof also does not depend on 1359 timing: if a race and a resulting deadlock is possible 1360 theoretically (no matter how unlikely the race scenario 1361 is), it will be proven so and will immediately be 1362 reported by the kernel (once the event is observed that 1363 makes the deadlock theoretically possible). 1364 1365 If a deadlock is impossible (i.e. the locking rules, as 1366 observed by the kernel, are mathematically correct), the 1367 kernel reports nothing. 1368 1369 NOTE: this feature can also be enabled for rwlocks, mutexes 1370 and rwsems - in which case all dependencies between these 1371 different locking variants are observed and mapped too, and 1372 the proof of observed correctness is also maintained for an 1373 arbitrary combination of these separate locking variants. 1374 1375 For more details, see Documentation/locking/lockdep-design.rst. 1376 1377config PROVE_RAW_LOCK_NESTING 1378 bool "Enable raw_spinlock - spinlock nesting checks" 1379 depends on PROVE_LOCKING 1380 default n 1381 help 1382 Enable the raw_spinlock vs. spinlock nesting checks which ensure 1383 that the lock nesting rules for PREEMPT_RT enabled kernels are 1384 not violated. 1385 1386 NOTE: There are known nesting problems. So if you enable this 1387 option expect lockdep splats until these problems have been fully 1388 addressed which is work in progress. This config switch allows to 1389 identify and analyze these problems. It will be removed and the 1390 check permanently enabled once the main issues have been fixed. 1391 1392 If unsure, select N. 1393 1394config LOCK_STAT 1395 bool "Lock usage statistics" 1396 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1397 select LOCKDEP 1398 select DEBUG_SPINLOCK 1399 select DEBUG_MUTEXES if !PREEMPT_RT 1400 select DEBUG_RT_MUTEXES if RT_MUTEXES 1401 select DEBUG_LOCK_ALLOC 1402 default n 1403 help 1404 This feature enables tracking lock contention points 1405 1406 For more details, see Documentation/locking/lockstat.rst 1407 1408 This also enables lock events required by "perf lock", 1409 subcommand of perf. 1410 If you want to use "perf lock", you also need to turn on 1411 CONFIG_EVENT_TRACING. 1412 1413 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1414 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1415 1416config DEBUG_RT_MUTEXES 1417 bool "RT Mutex debugging, deadlock detection" 1418 depends on DEBUG_KERNEL && RT_MUTEXES 1419 help 1420 This allows rt mutex semantics violations and rt mutex related 1421 deadlocks (lockups) to be detected and reported automatically. 1422 1423config DEBUG_SPINLOCK 1424 bool "Spinlock and rw-lock debugging: basic checks" 1425 depends on DEBUG_KERNEL 1426 select UNINLINE_SPIN_UNLOCK 1427 help 1428 Say Y here and build SMP to catch missing spinlock initialization 1429 and certain other kinds of spinlock errors commonly made. This is 1430 best used in conjunction with the NMI watchdog so that spinlock 1431 deadlocks are also debuggable. 1432 1433config DEBUG_MUTEXES 1434 bool "Mutex debugging: basic checks" 1435 depends on DEBUG_KERNEL && !PREEMPT_RT 1436 help 1437 This feature allows mutex semantics violations to be detected and 1438 reported. 1439 1440config DEBUG_WW_MUTEX_SLOWPATH 1441 bool "Wait/wound mutex debugging: Slowpath testing" 1442 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1443 select DEBUG_LOCK_ALLOC 1444 select DEBUG_SPINLOCK 1445 select DEBUG_MUTEXES if !PREEMPT_RT 1446 select DEBUG_RT_MUTEXES if PREEMPT_RT 1447 help 1448 This feature enables slowpath testing for w/w mutex users by 1449 injecting additional -EDEADLK wound/backoff cases. Together with 1450 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1451 will test all possible w/w mutex interface abuse with the 1452 exception of simply not acquiring all the required locks. 1453 Note that this feature can introduce significant overhead, so 1454 it really should not be enabled in a production or distro kernel, 1455 even a debug kernel. If you are a driver writer, enable it. If 1456 you are a distro, do not. 1457 1458config DEBUG_RWSEMS 1459 bool "RW Semaphore debugging: basic checks" 1460 depends on DEBUG_KERNEL && !PREEMPT_RT 1461 help 1462 This debugging feature allows mismatched rw semaphore locks 1463 and unlocks to be detected and reported. 1464 1465config DEBUG_LOCK_ALLOC 1466 bool "Lock debugging: detect incorrect freeing of live locks" 1467 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1468 select DEBUG_SPINLOCK 1469 select DEBUG_MUTEXES if !PREEMPT_RT 1470 select DEBUG_RT_MUTEXES if RT_MUTEXES 1471 select LOCKDEP 1472 help 1473 This feature will check whether any held lock (spinlock, rwlock, 1474 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1475 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1476 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1477 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1478 held during task exit. 1479 1480config LOCKDEP 1481 bool 1482 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1483 select STACKTRACE 1484 select KALLSYMS 1485 select KALLSYMS_ALL 1486 1487config LOCKDEP_SMALL 1488 bool 1489 1490config LOCKDEP_BITS 1491 int "Bitsize for MAX_LOCKDEP_ENTRIES" 1492 depends on LOCKDEP && !LOCKDEP_SMALL 1493 range 10 30 1494 default 15 1495 help 1496 Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message. 1497 1498config LOCKDEP_CHAINS_BITS 1499 int "Bitsize for MAX_LOCKDEP_CHAINS" 1500 depends on LOCKDEP && !LOCKDEP_SMALL 1501 range 10 30 1502 default 16 1503 help 1504 Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message. 1505 1506config LOCKDEP_STACK_TRACE_BITS 1507 int "Bitsize for MAX_STACK_TRACE_ENTRIES" 1508 depends on LOCKDEP && !LOCKDEP_SMALL 1509 range 10 30 1510 default 19 1511 help 1512 Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message. 1513 1514config LOCKDEP_STACK_TRACE_HASH_BITS 1515 int "Bitsize for STACK_TRACE_HASH_SIZE" 1516 depends on LOCKDEP && !LOCKDEP_SMALL 1517 range 10 30 1518 default 14 1519 help 1520 Try increasing this value if you need large STACK_TRACE_HASH_SIZE. 1521 1522config LOCKDEP_CIRCULAR_QUEUE_BITS 1523 int "Bitsize for elements in circular_queue struct" 1524 depends on LOCKDEP 1525 range 10 30 1526 default 12 1527 help 1528 Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure. 1529 1530config DEBUG_LOCKDEP 1531 bool "Lock dependency engine debugging" 1532 depends on DEBUG_KERNEL && LOCKDEP 1533 select DEBUG_IRQFLAGS 1534 help 1535 If you say Y here, the lock dependency engine will do 1536 additional runtime checks to debug itself, at the price 1537 of more runtime overhead. 1538 1539config DEBUG_ATOMIC_SLEEP 1540 bool "Sleep inside atomic section checking" 1541 select PREEMPT_COUNT 1542 depends on DEBUG_KERNEL 1543 depends on !ARCH_NO_PREEMPT 1544 help 1545 If you say Y here, various routines which may sleep will become very 1546 noisy if they are called inside atomic sections: when a spinlock is 1547 held, inside an rcu read side critical section, inside preempt disabled 1548 sections, inside an interrupt, etc... 1549 1550config DEBUG_LOCKING_API_SELFTESTS 1551 bool "Locking API boot-time self-tests" 1552 depends on DEBUG_KERNEL 1553 help 1554 Say Y here if you want the kernel to run a short self-test during 1555 bootup. The self-test checks whether common types of locking bugs 1556 are detected by debugging mechanisms or not. (if you disable 1557 lock debugging then those bugs won't be detected of course.) 1558 The following locking APIs are covered: spinlocks, rwlocks, 1559 mutexes and rwsems. 1560 1561config LOCK_TORTURE_TEST 1562 tristate "torture tests for locking" 1563 depends on DEBUG_KERNEL 1564 select TORTURE_TEST 1565 help 1566 This option provides a kernel module that runs torture tests 1567 on kernel locking primitives. The kernel module may be built 1568 after the fact on the running kernel to be tested, if desired. 1569 1570 Say Y here if you want kernel locking-primitive torture tests 1571 to be built into the kernel. 1572 Say M if you want these torture tests to build as a module. 1573 Say N if you are unsure. 1574 1575config WW_MUTEX_SELFTEST 1576 tristate "Wait/wound mutex selftests" 1577 help 1578 This option provides a kernel module that runs tests on the 1579 on the struct ww_mutex locking API. 1580 1581 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1582 with this test harness. 1583 1584 Say M if you want these self tests to build as a module. 1585 Say N if you are unsure. 1586 1587config SCF_TORTURE_TEST 1588 tristate "torture tests for smp_call_function*()" 1589 depends on DEBUG_KERNEL 1590 select TORTURE_TEST 1591 help 1592 This option provides a kernel module that runs torture tests 1593 on the smp_call_function() family of primitives. The kernel 1594 module may be built after the fact on the running kernel to 1595 be tested, if desired. 1596 1597config CSD_LOCK_WAIT_DEBUG 1598 bool "Debugging for csd_lock_wait(), called from smp_call_function*()" 1599 depends on DEBUG_KERNEL 1600 depends on 64BIT 1601 default n 1602 help 1603 This option enables debug prints when CPUs are slow to respond 1604 to the smp_call_function*() IPI wrappers. These debug prints 1605 include the IPI handler function currently executing (if any) 1606 and relevant stack traces. 1607 1608config CSD_LOCK_WAIT_DEBUG_DEFAULT 1609 bool "Default csd_lock_wait() debugging on at boot time" 1610 depends on CSD_LOCK_WAIT_DEBUG 1611 depends on 64BIT 1612 default n 1613 help 1614 This option causes the csdlock_debug= kernel boot parameter to 1615 default to 1 (basic debugging) instead of 0 (no debugging). 1616 1617endmenu # lock debugging 1618 1619config TRACE_IRQFLAGS 1620 depends on TRACE_IRQFLAGS_SUPPORT 1621 bool 1622 help 1623 Enables hooks to interrupt enabling and disabling for 1624 either tracing or lock debugging. 1625 1626config TRACE_IRQFLAGS_NMI 1627 def_bool y 1628 depends on TRACE_IRQFLAGS 1629 depends on TRACE_IRQFLAGS_NMI_SUPPORT 1630 1631config NMI_CHECK_CPU 1632 bool "Debugging for CPUs failing to respond to backtrace requests" 1633 depends on DEBUG_KERNEL 1634 depends on X86 1635 default n 1636 help 1637 Enables debug prints when a CPU fails to respond to a given 1638 backtrace NMI. These prints provide some reasons why a CPU 1639 might legitimately be failing to respond, for example, if it 1640 is offline of if ignore_nmis is set. 1641 1642config DEBUG_IRQFLAGS 1643 bool "Debug IRQ flag manipulation" 1644 help 1645 Enables checks for potentially unsafe enabling or disabling of 1646 interrupts, such as calling raw_local_irq_restore() when interrupts 1647 are enabled. 1648 1649config STACKTRACE 1650 bool "Stack backtrace support" 1651 depends on STACKTRACE_SUPPORT 1652 help 1653 This option causes the kernel to create a /proc/pid/stack for 1654 every process, showing its current stack trace. 1655 It is also used by various kernel debugging features that require 1656 stack trace generation. 1657 1658config WARN_ALL_UNSEEDED_RANDOM 1659 bool "Warn for all uses of unseeded randomness" 1660 default n 1661 help 1662 Some parts of the kernel contain bugs relating to their use of 1663 cryptographically secure random numbers before it's actually possible 1664 to generate those numbers securely. This setting ensures that these 1665 flaws don't go unnoticed, by enabling a message, should this ever 1666 occur. This will allow people with obscure setups to know when things 1667 are going wrong, so that they might contact developers about fixing 1668 it. 1669 1670 Unfortunately, on some models of some architectures getting 1671 a fully seeded CRNG is extremely difficult, and so this can 1672 result in dmesg getting spammed for a surprisingly long 1673 time. This is really bad from a security perspective, and 1674 so architecture maintainers really need to do what they can 1675 to get the CRNG seeded sooner after the system is booted. 1676 However, since users cannot do anything actionable to 1677 address this, by default this option is disabled. 1678 1679 Say Y here if you want to receive warnings for all uses of 1680 unseeded randomness. This will be of use primarily for 1681 those developers interested in improving the security of 1682 Linux kernels running on their architecture (or 1683 subarchitecture). 1684 1685config DEBUG_KOBJECT 1686 bool "kobject debugging" 1687 depends on DEBUG_KERNEL 1688 help 1689 If you say Y here, some extra kobject debugging messages will be sent 1690 to the syslog. 1691 1692config DEBUG_KOBJECT_RELEASE 1693 bool "kobject release debugging" 1694 depends on DEBUG_OBJECTS_TIMERS 1695 help 1696 kobjects are reference counted objects. This means that their 1697 last reference count put is not predictable, and the kobject can 1698 live on past the point at which a driver decides to drop its 1699 initial reference to the kobject gained on allocation. An 1700 example of this would be a struct device which has just been 1701 unregistered. 1702 1703 However, some buggy drivers assume that after such an operation, 1704 the memory backing the kobject can be immediately freed. This 1705 goes completely against the principles of a refcounted object. 1706 1707 If you say Y here, the kernel will delay the release of kobjects 1708 on the last reference count to improve the visibility of this 1709 kind of kobject release bug. 1710 1711config HAVE_DEBUG_BUGVERBOSE 1712 bool 1713 1714menu "Debug kernel data structures" 1715 1716config DEBUG_LIST 1717 bool "Debug linked list manipulation" 1718 depends on DEBUG_KERNEL 1719 select LIST_HARDENED 1720 help 1721 Enable this to turn on extended checks in the linked-list walking 1722 routines. 1723 1724 This option trades better quality error reports for performance, and 1725 is more suitable for kernel debugging. If you care about performance, 1726 you should only enable CONFIG_LIST_HARDENED instead. 1727 1728 If unsure, say N. 1729 1730config DEBUG_PLIST 1731 bool "Debug priority linked list manipulation" 1732 depends on DEBUG_KERNEL 1733 help 1734 Enable this to turn on extended checks in the priority-ordered 1735 linked-list (plist) walking routines. This checks the entire 1736 list multiple times during each manipulation. 1737 1738 If unsure, say N. 1739 1740config DEBUG_SG 1741 bool "Debug SG table operations" 1742 depends on DEBUG_KERNEL 1743 help 1744 Enable this to turn on checks on scatter-gather tables. This can 1745 help find problems with drivers that do not properly initialize 1746 their sg tables. 1747 1748 If unsure, say N. 1749 1750config DEBUG_NOTIFIERS 1751 bool "Debug notifier call chains" 1752 depends on DEBUG_KERNEL 1753 help 1754 Enable this to turn on sanity checking for notifier call chains. 1755 This is most useful for kernel developers to make sure that 1756 modules properly unregister themselves from notifier chains. 1757 This is a relatively cheap check but if you care about maximum 1758 performance, say N. 1759 1760config DEBUG_CLOSURES 1761 bool "Debug closures (bcache async widgits)" 1762 depends on CLOSURES 1763 select DEBUG_FS 1764 help 1765 Keeps all active closures in a linked list and provides a debugfs 1766 interface to list them, which makes it possible to see asynchronous 1767 operations that get stuck. 1768 1769config DEBUG_MAPLE_TREE 1770 bool "Debug maple trees" 1771 depends on DEBUG_KERNEL 1772 help 1773 Enable maple tree debugging information and extra validations. 1774 1775 If unsure, say N. 1776 1777endmenu 1778 1779source "kernel/rcu/Kconfig.debug" 1780 1781config DEBUG_WQ_FORCE_RR_CPU 1782 bool "Force round-robin CPU selection for unbound work items" 1783 depends on DEBUG_KERNEL 1784 default n 1785 help 1786 Workqueue used to implicitly guarantee that work items queued 1787 without explicit CPU specified are put on the local CPU. This 1788 guarantee is no longer true and while local CPU is still 1789 preferred work items may be put on foreign CPUs. Kernel 1790 parameter "workqueue.debug_force_rr_cpu" is added to force 1791 round-robin CPU selection to flush out usages which depend on the 1792 now broken guarantee. This config option enables the debug 1793 feature by default. When enabled, memory and cache locality will 1794 be impacted. 1795 1796config CPU_HOTPLUG_STATE_CONTROL 1797 bool "Enable CPU hotplug state control" 1798 depends on DEBUG_KERNEL 1799 depends on HOTPLUG_CPU 1800 default n 1801 help 1802 Allows to write steps between "offline" and "online" to the CPUs 1803 sysfs target file so states can be stepped granular. This is a debug 1804 option for now as the hotplug machinery cannot be stopped and 1805 restarted at arbitrary points yet. 1806 1807 Say N if your are unsure. 1808 1809config LATENCYTOP 1810 bool "Latency measuring infrastructure" 1811 depends on DEBUG_KERNEL 1812 depends on STACKTRACE_SUPPORT 1813 depends on PROC_FS 1814 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 1815 select KALLSYMS 1816 select KALLSYMS_ALL 1817 select STACKTRACE 1818 select SCHEDSTATS 1819 help 1820 Enable this option if you want to use the LatencyTOP tool 1821 to find out which userspace is blocking on what kernel operations. 1822 1823config DEBUG_CGROUP_REF 1824 bool "Disable inlining of cgroup css reference count functions" 1825 depends on DEBUG_KERNEL 1826 depends on CGROUPS 1827 depends on KPROBES 1828 default n 1829 help 1830 Force cgroup css reference count functions to not be inlined so 1831 that they can be kprobed for debugging. 1832 1833source "kernel/trace/Kconfig" 1834 1835config PROVIDE_OHCI1394_DMA_INIT 1836 bool "Remote debugging over FireWire early on boot" 1837 depends on PCI && X86 1838 help 1839 If you want to debug problems which hang or crash the kernel early 1840 on boot and the crashing machine has a FireWire port, you can use 1841 this feature to remotely access the memory of the crashed machine 1842 over FireWire. This employs remote DMA as part of the OHCI1394 1843 specification which is now the standard for FireWire controllers. 1844 1845 With remote DMA, you can monitor the printk buffer remotely using 1846 firescope and access all memory below 4GB using fireproxy from gdb. 1847 Even controlling a kernel debugger is possible using remote DMA. 1848 1849 Usage: 1850 1851 If ohci1394_dma=early is used as boot parameter, it will initialize 1852 all OHCI1394 controllers which are found in the PCI config space. 1853 1854 As all changes to the FireWire bus such as enabling and disabling 1855 devices cause a bus reset and thereby disable remote DMA for all 1856 devices, be sure to have the cable plugged and FireWire enabled on 1857 the debugging host before booting the debug target for debugging. 1858 1859 This code (~1k) is freed after boot. By then, the firewire stack 1860 in charge of the OHCI-1394 controllers should be used instead. 1861 1862 See Documentation/core-api/debugging-via-ohci1394.rst for more information. 1863 1864source "samples/Kconfig" 1865 1866config ARCH_HAS_DEVMEM_IS_ALLOWED 1867 bool 1868 1869config STRICT_DEVMEM 1870 bool "Filter access to /dev/mem" 1871 depends on MMU && DEVMEM 1872 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED 1873 default y if PPC || X86 || ARM64 1874 help 1875 If this option is disabled, you allow userspace (root) access to all 1876 of memory, including kernel and userspace memory. Accidental 1877 access to this is obviously disastrous, but specific access can 1878 be used by people debugging the kernel. Note that with PAT support 1879 enabled, even in this case there are restrictions on /dev/mem 1880 use due to the cache aliasing requirements. 1881 1882 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 1883 file only allows userspace access to PCI space and the BIOS code and 1884 data regions. This is sufficient for dosemu and X and all common 1885 users of /dev/mem. 1886 1887 If in doubt, say Y. 1888 1889config IO_STRICT_DEVMEM 1890 bool "Filter I/O access to /dev/mem" 1891 depends on STRICT_DEVMEM 1892 help 1893 If this option is disabled, you allow userspace (root) access to all 1894 io-memory regardless of whether a driver is actively using that 1895 range. Accidental access to this is obviously disastrous, but 1896 specific access can be used by people debugging kernel drivers. 1897 1898 If this option is switched on, the /dev/mem file only allows 1899 userspace access to *idle* io-memory ranges (see /proc/iomem) This 1900 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 1901 if the driver using a given range cannot be disabled. 1902 1903 If in doubt, say Y. 1904 1905menu "$(SRCARCH) Debugging" 1906 1907source "arch/$(SRCARCH)/Kconfig.debug" 1908 1909endmenu 1910 1911menu "Kernel Testing and Coverage" 1912 1913source "lib/kunit/Kconfig" 1914 1915config NOTIFIER_ERROR_INJECTION 1916 tristate "Notifier error injection" 1917 depends on DEBUG_KERNEL 1918 select DEBUG_FS 1919 help 1920 This option provides the ability to inject artificial errors to 1921 specified notifier chain callbacks. It is useful to test the error 1922 handling of notifier call chain failures. 1923 1924 Say N if unsure. 1925 1926config PM_NOTIFIER_ERROR_INJECT 1927 tristate "PM notifier error injection module" 1928 depends on PM && NOTIFIER_ERROR_INJECTION 1929 default m if PM_DEBUG 1930 help 1931 This option provides the ability to inject artificial errors to 1932 PM notifier chain callbacks. It is controlled through debugfs 1933 interface /sys/kernel/debug/notifier-error-inject/pm 1934 1935 If the notifier call chain should be failed with some events 1936 notified, write the error code to "actions/<notifier event>/error". 1937 1938 Example: Inject PM suspend error (-12 = -ENOMEM) 1939 1940 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1941 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1942 # echo mem > /sys/power/state 1943 bash: echo: write error: Cannot allocate memory 1944 1945 To compile this code as a module, choose M here: the module will 1946 be called pm-notifier-error-inject. 1947 1948 If unsure, say N. 1949 1950config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1951 tristate "OF reconfig notifier error injection module" 1952 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1953 help 1954 This option provides the ability to inject artificial errors to 1955 OF reconfig notifier chain callbacks. It is controlled 1956 through debugfs interface under 1957 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1958 1959 If the notifier call chain should be failed with some events 1960 notified, write the error code to "actions/<notifier event>/error". 1961 1962 To compile this code as a module, choose M here: the module will 1963 be called of-reconfig-notifier-error-inject. 1964 1965 If unsure, say N. 1966 1967config NETDEV_NOTIFIER_ERROR_INJECT 1968 tristate "Netdev notifier error injection module" 1969 depends on NET && NOTIFIER_ERROR_INJECTION 1970 help 1971 This option provides the ability to inject artificial errors to 1972 netdevice notifier chain callbacks. It is controlled through debugfs 1973 interface /sys/kernel/debug/notifier-error-inject/netdev 1974 1975 If the notifier call chain should be failed with some events 1976 notified, write the error code to "actions/<notifier event>/error". 1977 1978 Example: Inject netdevice mtu change error (-22 = -EINVAL) 1979 1980 # cd /sys/kernel/debug/notifier-error-inject/netdev 1981 # echo -22 > actions/NETDEV_CHANGEMTU/error 1982 # ip link set eth0 mtu 1024 1983 RTNETLINK answers: Invalid argument 1984 1985 To compile this code as a module, choose M here: the module will 1986 be called netdev-notifier-error-inject. 1987 1988 If unsure, say N. 1989 1990config FUNCTION_ERROR_INJECTION 1991 bool "Fault-injections of functions" 1992 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 1993 help 1994 Add fault injections into various functions that are annotated with 1995 ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return 1996 value of these functions. This is useful to test error paths of code. 1997 1998 If unsure, say N 1999 2000config FAULT_INJECTION 2001 bool "Fault-injection framework" 2002 depends on DEBUG_KERNEL 2003 help 2004 Provide fault-injection framework. 2005 For more details, see Documentation/fault-injection/. 2006 2007config FAILSLAB 2008 bool "Fault-injection capability for kmalloc" 2009 depends on FAULT_INJECTION 2010 help 2011 Provide fault-injection capability for kmalloc. 2012 2013config FAIL_PAGE_ALLOC 2014 bool "Fault-injection capability for alloc_pages()" 2015 depends on FAULT_INJECTION 2016 help 2017 Provide fault-injection capability for alloc_pages(). 2018 2019config FAULT_INJECTION_USERCOPY 2020 bool "Fault injection capability for usercopy functions" 2021 depends on FAULT_INJECTION 2022 help 2023 Provides fault-injection capability to inject failures 2024 in usercopy functions (copy_from_user(), get_user(), ...). 2025 2026config FAIL_MAKE_REQUEST 2027 bool "Fault-injection capability for disk IO" 2028 depends on FAULT_INJECTION && BLOCK 2029 help 2030 Provide fault-injection capability for disk IO. 2031 2032config FAIL_IO_TIMEOUT 2033 bool "Fault-injection capability for faking disk interrupts" 2034 depends on FAULT_INJECTION && BLOCK 2035 help 2036 Provide fault-injection capability on end IO handling. This 2037 will make the block layer "forget" an interrupt as configured, 2038 thus exercising the error handling. 2039 2040 Only works with drivers that use the generic timeout handling, 2041 for others it won't do anything. 2042 2043config FAIL_FUTEX 2044 bool "Fault-injection capability for futexes" 2045 select DEBUG_FS 2046 depends on FAULT_INJECTION && FUTEX 2047 help 2048 Provide fault-injection capability for futexes. 2049 2050config FAULT_INJECTION_DEBUG_FS 2051 bool "Debugfs entries for fault-injection capabilities" 2052 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 2053 help 2054 Enable configuration of fault-injection capabilities via debugfs. 2055 2056config FAIL_FUNCTION 2057 bool "Fault-injection capability for functions" 2058 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 2059 help 2060 Provide function-based fault-injection capability. 2061 This will allow you to override a specific function with a return 2062 with given return value. As a result, function caller will see 2063 an error value and have to handle it. This is useful to test the 2064 error handling in various subsystems. 2065 2066config FAIL_MMC_REQUEST 2067 bool "Fault-injection capability for MMC IO" 2068 depends on FAULT_INJECTION_DEBUG_FS && MMC 2069 help 2070 Provide fault-injection capability for MMC IO. 2071 This will make the mmc core return data errors. This is 2072 useful to test the error handling in the mmc block device 2073 and to test how the mmc host driver handles retries from 2074 the block device. 2075 2076config FAIL_SUNRPC 2077 bool "Fault-injection capability for SunRPC" 2078 depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG 2079 help 2080 Provide fault-injection capability for SunRPC and 2081 its consumers. 2082 2083config FAULT_INJECTION_CONFIGFS 2084 bool "Configfs interface for fault-injection capabilities" 2085 depends on FAULT_INJECTION 2086 select CONFIGFS_FS 2087 help 2088 This option allows configfs-based drivers to dynamically configure 2089 fault-injection via configfs. Each parameter for driver-specific 2090 fault-injection can be made visible as a configfs attribute in a 2091 configfs group. 2092 2093 2094config FAULT_INJECTION_STACKTRACE_FILTER 2095 bool "stacktrace filter for fault-injection capabilities" 2096 depends on FAULT_INJECTION 2097 depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT 2098 select STACKTRACE 2099 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 2100 help 2101 Provide stacktrace filter for fault-injection capabilities 2102 2103config ARCH_HAS_KCOV 2104 bool 2105 help 2106 An architecture should select this when it can successfully 2107 build and run with CONFIG_KCOV. This typically requires 2108 disabling instrumentation for some early boot code. 2109 2110config CC_HAS_SANCOV_TRACE_PC 2111 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 2112 2113 2114config KCOV 2115 bool "Code coverage for fuzzing" 2116 depends on ARCH_HAS_KCOV 2117 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 2118 depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \ 2119 GCC_VERSION >= 120000 || CC_IS_CLANG 2120 select DEBUG_FS 2121 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 2122 select OBJTOOL if HAVE_NOINSTR_HACK 2123 help 2124 KCOV exposes kernel code coverage information in a form suitable 2125 for coverage-guided fuzzing (randomized testing). 2126 2127 For more details, see Documentation/dev-tools/kcov.rst. 2128 2129config KCOV_ENABLE_COMPARISONS 2130 bool "Enable comparison operands collection by KCOV" 2131 depends on KCOV 2132 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 2133 help 2134 KCOV also exposes operands of every comparison in the instrumented 2135 code along with operand sizes and PCs of the comparison instructions. 2136 These operands can be used by fuzzing engines to improve the quality 2137 of fuzzing coverage. 2138 2139config KCOV_INSTRUMENT_ALL 2140 bool "Instrument all code by default" 2141 depends on KCOV 2142 default y 2143 help 2144 If you are doing generic system call fuzzing (like e.g. syzkaller), 2145 then you will want to instrument the whole kernel and you should 2146 say y here. If you are doing more targeted fuzzing (like e.g. 2147 filesystem fuzzing with AFL) then you will want to enable coverage 2148 for more specific subsets of files, and should say n here. 2149 2150config KCOV_IRQ_AREA_SIZE 2151 hex "Size of interrupt coverage collection area in words" 2152 depends on KCOV 2153 default 0x40000 2154 help 2155 KCOV uses preallocated per-cpu areas to collect coverage from 2156 soft interrupts. This specifies the size of those areas in the 2157 number of unsigned long words. 2158 2159menuconfig RUNTIME_TESTING_MENU 2160 bool "Runtime Testing" 2161 default y 2162 2163if RUNTIME_TESTING_MENU 2164 2165config TEST_DHRY 2166 tristate "Dhrystone benchmark test" 2167 help 2168 Enable this to include the Dhrystone 2.1 benchmark. This test 2169 calculates the number of Dhrystones per second, and the number of 2170 DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided 2171 by 1757 (the number of Dhrystones per second obtained on the VAX 2172 11/780, nominally a 1 MIPS machine). 2173 2174 To run the benchmark, it needs to be enabled explicitly, either from 2175 the kernel command line (when built-in), or from userspace (when 2176 built-in or modular). 2177 2178 Run once during kernel boot: 2179 2180 test_dhry.run 2181 2182 Set number of iterations from kernel command line: 2183 2184 test_dhry.iterations=<n> 2185 2186 Set number of iterations from userspace: 2187 2188 echo <n> > /sys/module/test_dhry/parameters/iterations 2189 2190 Trigger manual run from userspace: 2191 2192 echo y > /sys/module/test_dhry/parameters/run 2193 2194 If the number of iterations is <= 0, the test will devise a suitable 2195 number of iterations (test runs for at least 2s) automatically. 2196 This process takes ca. 4s. 2197 2198 If unsure, say N. 2199 2200config LKDTM 2201 tristate "Linux Kernel Dump Test Tool Module" 2202 depends on DEBUG_FS 2203 help 2204 This module enables testing of the different dumping mechanisms by 2205 inducing system failures at predefined crash points. 2206 If you don't need it: say N 2207 Choose M here to compile this code as a module. The module will be 2208 called lkdtm. 2209 2210 Documentation on how to use the module can be found in 2211 Documentation/fault-injection/provoke-crashes.rst 2212 2213config CPUMASK_KUNIT_TEST 2214 tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS 2215 depends on KUNIT 2216 default KUNIT_ALL_TESTS 2217 help 2218 Enable to turn on cpumask tests, running at boot or module load time. 2219 2220 For more information on KUnit and unit tests in general, please refer 2221 to the KUnit documentation in Documentation/dev-tools/kunit/. 2222 2223 If unsure, say N. 2224 2225config TEST_LIST_SORT 2226 tristate "Linked list sorting test" if !KUNIT_ALL_TESTS 2227 depends on KUNIT 2228 default KUNIT_ALL_TESTS 2229 help 2230 Enable this to turn on 'list_sort()' function test. This test is 2231 executed only once during system boot (so affects only boot time), 2232 or at module load time. 2233 2234 If unsure, say N. 2235 2236config TEST_MIN_HEAP 2237 tristate "Min heap test" 2238 depends on DEBUG_KERNEL || m 2239 help 2240 Enable this to turn on min heap function tests. This test is 2241 executed only once during system boot (so affects only boot time), 2242 or at module load time. 2243 2244 If unsure, say N. 2245 2246config TEST_SORT 2247 tristate "Array-based sort test" if !KUNIT_ALL_TESTS 2248 depends on KUNIT 2249 default KUNIT_ALL_TESTS 2250 help 2251 This option enables the self-test function of 'sort()' at boot, 2252 or at module load time. 2253 2254 If unsure, say N. 2255 2256config TEST_DIV64 2257 tristate "64bit/32bit division and modulo test" 2258 depends on DEBUG_KERNEL || m 2259 help 2260 Enable this to turn on 'do_div()' function test. This test is 2261 executed only once during system boot (so affects only boot time), 2262 or at module load time. 2263 2264 If unsure, say N. 2265 2266config TEST_IOV_ITER 2267 tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS 2268 depends on KUNIT 2269 depends on MMU 2270 default KUNIT_ALL_TESTS 2271 help 2272 Enable this to turn on testing of the operation of the I/O iterator 2273 (iov_iter). This test is executed only once during system boot (so 2274 affects only boot time), or at module load time. 2275 2276 If unsure, say N. 2277 2278config KPROBES_SANITY_TEST 2279 tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS 2280 depends on DEBUG_KERNEL 2281 depends on KPROBES 2282 depends on KUNIT 2283 select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 2284 default KUNIT_ALL_TESTS 2285 help 2286 This option provides for testing basic kprobes functionality on 2287 boot. Samples of kprobe and kretprobe are inserted and 2288 verified for functionality. 2289 2290 Say N if you are unsure. 2291 2292config FPROBE_SANITY_TEST 2293 bool "Self test for fprobe" 2294 depends on DEBUG_KERNEL 2295 depends on FPROBE 2296 depends on KUNIT=y 2297 help 2298 This option will enable testing the fprobe when the system boot. 2299 A series of tests are made to verify that the fprobe is functioning 2300 properly. 2301 2302 Say N if you are unsure. 2303 2304config BACKTRACE_SELF_TEST 2305 tristate "Self test for the backtrace code" 2306 depends on DEBUG_KERNEL 2307 help 2308 This option provides a kernel module that can be used to test 2309 the kernel stack backtrace code. This option is not useful 2310 for distributions or general kernels, but only for kernel 2311 developers working on architecture code. 2312 2313 Note that if you want to also test saved backtraces, you will 2314 have to enable STACKTRACE as well. 2315 2316 Say N if you are unsure. 2317 2318config TEST_REF_TRACKER 2319 tristate "Self test for reference tracker" 2320 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT 2321 select REF_TRACKER 2322 help 2323 This option provides a kernel module performing tests 2324 using reference tracker infrastructure. 2325 2326 Say N if you are unsure. 2327 2328config RBTREE_TEST 2329 tristate "Red-Black tree test" 2330 depends on DEBUG_KERNEL 2331 help 2332 A benchmark measuring the performance of the rbtree library. 2333 Also includes rbtree invariant checks. 2334 2335config REED_SOLOMON_TEST 2336 tristate "Reed-Solomon library test" 2337 depends on DEBUG_KERNEL || m 2338 select REED_SOLOMON 2339 select REED_SOLOMON_ENC16 2340 select REED_SOLOMON_DEC16 2341 help 2342 This option enables the self-test function of rslib at boot, 2343 or at module load time. 2344 2345 If unsure, say N. 2346 2347config INTERVAL_TREE_TEST 2348 tristate "Interval tree test" 2349 depends on DEBUG_KERNEL 2350 select INTERVAL_TREE 2351 help 2352 A benchmark measuring the performance of the interval tree library 2353 2354config PERCPU_TEST 2355 tristate "Per cpu operations test" 2356 depends on m && DEBUG_KERNEL 2357 help 2358 Enable this option to build test module which validates per-cpu 2359 operations. 2360 2361 If unsure, say N. 2362 2363config ATOMIC64_SELFTEST 2364 tristate "Perform an atomic64_t self-test" 2365 help 2366 Enable this option to test the atomic64_t functions at boot or 2367 at module load time. 2368 2369 If unsure, say N. 2370 2371config ASYNC_RAID6_TEST 2372 tristate "Self test for hardware accelerated raid6 recovery" 2373 depends on ASYNC_RAID6_RECOV 2374 select ASYNC_MEMCPY 2375 help 2376 This is a one-shot self test that permutes through the 2377 recovery of all the possible two disk failure scenarios for a 2378 N-disk array. Recovery is performed with the asynchronous 2379 raid6 recovery routines, and will optionally use an offload 2380 engine if one is available. 2381 2382 If unsure, say N. 2383 2384config TEST_HEXDUMP 2385 tristate "Test functions located in the hexdump module at runtime" 2386 2387config STRING_KUNIT_TEST 2388 tristate "KUnit test string functions at runtime" if !KUNIT_ALL_TESTS 2389 depends on KUNIT 2390 default KUNIT_ALL_TESTS 2391 2392config STRING_HELPERS_KUNIT_TEST 2393 tristate "KUnit test string helpers at runtime" if !KUNIT_ALL_TESTS 2394 depends on KUNIT 2395 default KUNIT_ALL_TESTS 2396 2397config TEST_KSTRTOX 2398 tristate "Test kstrto*() family of functions at runtime" 2399 2400config TEST_PRINTF 2401 tristate "Test printf() family of functions at runtime" 2402 2403config TEST_SCANF 2404 tristate "Test scanf() family of functions at runtime" 2405 2406config TEST_BITMAP 2407 tristate "Test bitmap_*() family of functions at runtime" 2408 help 2409 Enable this option to test the bitmap functions at boot. 2410 2411 If unsure, say N. 2412 2413config TEST_UUID 2414 tristate "Test functions located in the uuid module at runtime" 2415 2416config TEST_XARRAY 2417 tristate "Test the XArray code at runtime" 2418 2419config TEST_MAPLE_TREE 2420 tristate "Test the Maple Tree code at runtime or module load" 2421 help 2422 Enable this option to test the maple tree code functions at boot, or 2423 when the module is loaded. Enable "Debug Maple Trees" will enable 2424 more verbose output on failures. 2425 2426 If unsure, say N. 2427 2428config TEST_RHASHTABLE 2429 tristate "Perform selftest on resizable hash table" 2430 help 2431 Enable this option to test the rhashtable functions at boot. 2432 2433 If unsure, say N. 2434 2435config TEST_IDA 2436 tristate "Perform selftest on IDA functions" 2437 2438config TEST_PARMAN 2439 tristate "Perform selftest on priority array manager" 2440 depends on PARMAN 2441 help 2442 Enable this option to test priority array manager on boot 2443 (or module load). 2444 2445 If unsure, say N. 2446 2447config TEST_IRQ_TIMINGS 2448 bool "IRQ timings selftest" 2449 depends on IRQ_TIMINGS 2450 help 2451 Enable this option to test the irq timings code on boot. 2452 2453 If unsure, say N. 2454 2455config TEST_LKM 2456 tristate "Test module loading with 'hello world' module" 2457 depends on m 2458 help 2459 This builds the "test_module" module that emits "Hello, world" 2460 on printk when loaded. It is designed to be used for basic 2461 evaluation of the module loading subsystem (for example when 2462 validating module verification). It lacks any extra dependencies, 2463 and will not normally be loaded by the system unless explicitly 2464 requested by name. 2465 2466 If unsure, say N. 2467 2468config TEST_BITOPS 2469 tristate "Test module for compilation of bitops operations" 2470 depends on m 2471 help 2472 This builds the "test_bitops" module that is much like the 2473 TEST_LKM module except that it does a basic exercise of the 2474 set/clear_bit macros and get_count_order/long to make sure there are 2475 no compiler warnings from C=1 sparse checker or -Wextra 2476 compilations. It has no dependencies and doesn't run or load unless 2477 explicitly requested by name. for example: modprobe test_bitops. 2478 2479 If unsure, say N. 2480 2481config TEST_VMALLOC 2482 tristate "Test module for stress/performance analysis of vmalloc allocator" 2483 default n 2484 depends on MMU 2485 depends on m 2486 help 2487 This builds the "test_vmalloc" module that should be used for 2488 stress and performance analysis. So, any new change for vmalloc 2489 subsystem can be evaluated from performance and stability point 2490 of view. 2491 2492 If unsure, say N. 2493 2494config TEST_USER_COPY 2495 tristate "Test user/kernel boundary protections" 2496 depends on m 2497 help 2498 This builds the "test_user_copy" module that runs sanity checks 2499 on the copy_to/from_user infrastructure, making sure basic 2500 user/kernel boundary testing is working. If it fails to load, 2501 a regression has been detected in the user/kernel memory boundary 2502 protections. 2503 2504 If unsure, say N. 2505 2506config TEST_BPF 2507 tristate "Test BPF filter functionality" 2508 depends on m && NET 2509 help 2510 This builds the "test_bpf" module that runs various test vectors 2511 against the BPF interpreter or BPF JIT compiler depending on the 2512 current setting. This is in particular useful for BPF JIT compiler 2513 development, but also to run regression tests against changes in 2514 the interpreter code. It also enables test stubs for eBPF maps and 2515 verifier used by user space verifier testsuite. 2516 2517 If unsure, say N. 2518 2519config TEST_BLACKHOLE_DEV 2520 tristate "Test blackhole netdev functionality" 2521 depends on m && NET 2522 help 2523 This builds the "test_blackhole_dev" module that validates the 2524 data path through this blackhole netdev. 2525 2526 If unsure, say N. 2527 2528config FIND_BIT_BENCHMARK 2529 tristate "Test find_bit functions" 2530 help 2531 This builds the "test_find_bit" module that measure find_*_bit() 2532 functions performance. 2533 2534 If unsure, say N. 2535 2536config TEST_FIRMWARE 2537 tristate "Test firmware loading via userspace interface" 2538 depends on FW_LOADER 2539 help 2540 This builds the "test_firmware" module that creates a userspace 2541 interface for testing firmware loading. This can be used to 2542 control the triggering of firmware loading without needing an 2543 actual firmware-using device. The contents can be rechecked by 2544 userspace. 2545 2546 If unsure, say N. 2547 2548config TEST_SYSCTL 2549 tristate "sysctl test driver" 2550 depends on PROC_SYSCTL 2551 help 2552 This builds the "test_sysctl" module. This driver enables to test the 2553 proc sysctl interfaces available to drivers safely without affecting 2554 production knobs which might alter system functionality. 2555 2556 If unsure, say N. 2557 2558config BITFIELD_KUNIT 2559 tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS 2560 depends on KUNIT 2561 default KUNIT_ALL_TESTS 2562 help 2563 Enable this option to test the bitfield functions at boot. 2564 2565 KUnit tests run during boot and output the results to the debug log 2566 in TAP format (http://testanything.org/). Only useful for kernel devs 2567 running the KUnit test harness, and not intended for inclusion into a 2568 production build. 2569 2570 For more information on KUnit and unit tests in general please refer 2571 to the KUnit documentation in Documentation/dev-tools/kunit/. 2572 2573 If unsure, say N. 2574 2575config CHECKSUM_KUNIT 2576 tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS 2577 depends on KUNIT 2578 default KUNIT_ALL_TESTS 2579 help 2580 Enable this option to test the checksum functions at boot. 2581 2582 KUnit tests run during boot and output the results to the debug log 2583 in TAP format (http://testanything.org/). Only useful for kernel devs 2584 running the KUnit test harness, and not intended for inclusion into a 2585 production build. 2586 2587 For more information on KUnit and unit tests in general please refer 2588 to the KUnit documentation in Documentation/dev-tools/kunit/. 2589 2590 If unsure, say N. 2591 2592config HASH_KUNIT_TEST 2593 tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS 2594 depends on KUNIT 2595 default KUNIT_ALL_TESTS 2596 help 2597 Enable this option to test the kernel's string (<linux/stringhash.h>), and 2598 integer (<linux/hash.h>) hash functions on boot. 2599 2600 KUnit tests run during boot and output the results to the debug log 2601 in TAP format (https://testanything.org/). Only useful for kernel devs 2602 running the KUnit test harness, and not intended for inclusion into a 2603 production build. 2604 2605 For more information on KUnit and unit tests in general please refer 2606 to the KUnit documentation in Documentation/dev-tools/kunit/. 2607 2608 This is intended to help people writing architecture-specific 2609 optimized versions. If unsure, say N. 2610 2611config RESOURCE_KUNIT_TEST 2612 tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS 2613 depends on KUNIT 2614 default KUNIT_ALL_TESTS 2615 help 2616 This builds the resource API unit test. 2617 Tests the logic of API provided by resource.c and ioport.h. 2618 For more information on KUnit and unit tests in general please refer 2619 to the KUnit documentation in Documentation/dev-tools/kunit/. 2620 2621 If unsure, say N. 2622 2623config SYSCTL_KUNIT_TEST 2624 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS 2625 depends on KUNIT 2626 default KUNIT_ALL_TESTS 2627 help 2628 This builds the proc sysctl unit test, which runs on boot. 2629 Tests the API contract and implementation correctness of sysctl. 2630 For more information on KUnit and unit tests in general please refer 2631 to the KUnit documentation in Documentation/dev-tools/kunit/. 2632 2633 If unsure, say N. 2634 2635config LIST_KUNIT_TEST 2636 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS 2637 depends on KUNIT 2638 default KUNIT_ALL_TESTS 2639 help 2640 This builds the linked list KUnit test suite. 2641 It tests that the API and basic functionality of the list_head type 2642 and associated macros. 2643 2644 KUnit tests run during boot and output the results to the debug log 2645 in TAP format (https://testanything.org/). Only useful for kernel devs 2646 running the KUnit test harness, and not intended for inclusion into a 2647 production build. 2648 2649 For more information on KUnit and unit tests in general please refer 2650 to the KUnit documentation in Documentation/dev-tools/kunit/. 2651 2652 If unsure, say N. 2653 2654config HASHTABLE_KUNIT_TEST 2655 tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS 2656 depends on KUNIT 2657 default KUNIT_ALL_TESTS 2658 help 2659 This builds the hashtable KUnit test suite. 2660 It tests the basic functionality of the API defined in 2661 include/linux/hashtable.h. For more information on KUnit and 2662 unit tests in general please refer to the KUnit documentation 2663 in Documentation/dev-tools/kunit/. 2664 2665 If unsure, say N. 2666 2667config LINEAR_RANGES_TEST 2668 tristate "KUnit test for linear_ranges" 2669 depends on KUNIT 2670 select LINEAR_RANGES 2671 help 2672 This builds the linear_ranges unit test, which runs on boot. 2673 Tests the linear_ranges logic correctness. 2674 For more information on KUnit and unit tests in general please refer 2675 to the KUnit documentation in Documentation/dev-tools/kunit/. 2676 2677 If unsure, say N. 2678 2679config CMDLINE_KUNIT_TEST 2680 tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS 2681 depends on KUNIT 2682 default KUNIT_ALL_TESTS 2683 help 2684 This builds the cmdline API unit test. 2685 Tests the logic of API provided by cmdline.c. 2686 For more information on KUnit and unit tests in general please refer 2687 to the KUnit documentation in Documentation/dev-tools/kunit/. 2688 2689 If unsure, say N. 2690 2691config BITS_TEST 2692 tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS 2693 depends on KUNIT 2694 default KUNIT_ALL_TESTS 2695 help 2696 This builds the bits unit test. 2697 Tests the logic of macros defined in bits.h. 2698 For more information on KUnit and unit tests in general please refer 2699 to the KUnit documentation in Documentation/dev-tools/kunit/. 2700 2701 If unsure, say N. 2702 2703config SLUB_KUNIT_TEST 2704 tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS 2705 depends on SLUB_DEBUG && KUNIT 2706 default KUNIT_ALL_TESTS 2707 help 2708 This builds SLUB allocator unit test. 2709 Tests SLUB cache debugging functionality. 2710 For more information on KUnit and unit tests in general please refer 2711 to the KUnit documentation in Documentation/dev-tools/kunit/. 2712 2713 If unsure, say N. 2714 2715config RATIONAL_KUNIT_TEST 2716 tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS 2717 depends on KUNIT && RATIONAL 2718 default KUNIT_ALL_TESTS 2719 help 2720 This builds the rational math unit test. 2721 For more information on KUnit and unit tests in general please refer 2722 to the KUnit documentation in Documentation/dev-tools/kunit/. 2723 2724 If unsure, say N. 2725 2726config MEMCPY_KUNIT_TEST 2727 tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS 2728 depends on KUNIT 2729 default KUNIT_ALL_TESTS 2730 help 2731 Builds unit tests for memcpy(), memmove(), and memset() functions. 2732 For more information on KUnit and unit tests in general please refer 2733 to the KUnit documentation in Documentation/dev-tools/kunit/. 2734 2735 If unsure, say N. 2736 2737config IS_SIGNED_TYPE_KUNIT_TEST 2738 tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS 2739 depends on KUNIT 2740 default KUNIT_ALL_TESTS 2741 help 2742 Builds unit tests for the is_signed_type() macro. 2743 2744 For more information on KUnit and unit tests in general please refer 2745 to the KUnit documentation in Documentation/dev-tools/kunit/. 2746 2747 If unsure, say N. 2748 2749config OVERFLOW_KUNIT_TEST 2750 tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS 2751 depends on KUNIT 2752 default KUNIT_ALL_TESTS 2753 help 2754 Builds unit tests for the check_*_overflow(), size_*(), allocation, and 2755 related functions. 2756 2757 For more information on KUnit and unit tests in general please refer 2758 to the KUnit documentation in Documentation/dev-tools/kunit/. 2759 2760 If unsure, say N. 2761 2762config STACKINIT_KUNIT_TEST 2763 tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS 2764 depends on KUNIT 2765 default KUNIT_ALL_TESTS 2766 help 2767 Test if the kernel is zero-initializing stack variables and 2768 padding. Coverage is controlled by compiler flags, 2769 CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO, 2770 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2771 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2772 2773config FORTIFY_KUNIT_TEST 2774 tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS 2775 depends on KUNIT 2776 default KUNIT_ALL_TESTS 2777 help 2778 Builds unit tests for checking internals of FORTIFY_SOURCE as used 2779 by the str*() and mem*() family of functions. For testing runtime 2780 traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests. 2781 2782config HW_BREAKPOINT_KUNIT_TEST 2783 bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS 2784 depends on HAVE_HW_BREAKPOINT 2785 depends on KUNIT=y 2786 default KUNIT_ALL_TESTS 2787 help 2788 Tests for hw_breakpoint constraints accounting. 2789 2790 If unsure, say N. 2791 2792config STRCAT_KUNIT_TEST 2793 tristate "Test strcat() family of functions at runtime" if !KUNIT_ALL_TESTS 2794 depends on KUNIT 2795 default KUNIT_ALL_TESTS 2796 2797config STRSCPY_KUNIT_TEST 2798 tristate "Test strscpy*() family of functions at runtime" if !KUNIT_ALL_TESTS 2799 depends on KUNIT 2800 default KUNIT_ALL_TESTS 2801 2802config SIPHASH_KUNIT_TEST 2803 tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS 2804 depends on KUNIT 2805 default KUNIT_ALL_TESTS 2806 help 2807 Enable this option to test the kernel's siphash (<linux/siphash.h>) hash 2808 functions on boot (or module load). 2809 2810 This is intended to help people writing architecture-specific 2811 optimized versions. If unsure, say N. 2812 2813config TEST_UDELAY 2814 tristate "udelay test driver" 2815 help 2816 This builds the "udelay_test" module that helps to make sure 2817 that udelay() is working properly. 2818 2819 If unsure, say N. 2820 2821config TEST_STATIC_KEYS 2822 tristate "Test static keys" 2823 depends on m 2824 help 2825 Test the static key interfaces. 2826 2827 If unsure, say N. 2828 2829config TEST_DYNAMIC_DEBUG 2830 tristate "Test DYNAMIC_DEBUG" 2831 depends on DYNAMIC_DEBUG 2832 help 2833 This module registers a tracer callback to count enabled 2834 pr_debugs in a 'do_debugging' function, then alters their 2835 enablements, calls the function, and compares counts. 2836 2837 If unsure, say N. 2838 2839config TEST_KMOD 2840 tristate "kmod stress tester" 2841 depends on m 2842 depends on NETDEVICES && NET_CORE && INET # for TUN 2843 depends on BLOCK 2844 depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS 2845 select TEST_LKM 2846 select XFS_FS 2847 select TUN 2848 select BTRFS_FS 2849 help 2850 Test the kernel's module loading mechanism: kmod. kmod implements 2851 support to load modules using the Linux kernel's usermode helper. 2852 This test provides a series of tests against kmod. 2853 2854 Although technically you can either build test_kmod as a module or 2855 into the kernel we disallow building it into the kernel since 2856 it stress tests request_module() and this will very likely cause 2857 some issues by taking over precious threads available from other 2858 module load requests, ultimately this could be fatal. 2859 2860 To run tests run: 2861 2862 tools/testing/selftests/kmod/kmod.sh --help 2863 2864 If unsure, say N. 2865 2866config TEST_DEBUG_VIRTUAL 2867 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 2868 depends on DEBUG_VIRTUAL 2869 help 2870 Test the kernel's ability to detect incorrect calls to 2871 virt_to_phys() done against the non-linear part of the 2872 kernel's virtual address map. 2873 2874 If unsure, say N. 2875 2876config TEST_MEMCAT_P 2877 tristate "Test memcat_p() helper function" 2878 help 2879 Test the memcat_p() helper for correctly merging two 2880 pointer arrays together. 2881 2882 If unsure, say N. 2883 2884config TEST_OBJAGG 2885 tristate "Perform selftest on object aggreration manager" 2886 default n 2887 depends on OBJAGG 2888 help 2889 Enable this option to test object aggregation manager on boot 2890 (or module load). 2891 2892config TEST_MEMINIT 2893 tristate "Test heap/page initialization" 2894 help 2895 Test if the kernel is zero-initializing heap and page allocations. 2896 This can be useful to test init_on_alloc and init_on_free features. 2897 2898 If unsure, say N. 2899 2900config TEST_HMM 2901 tristate "Test HMM (Heterogeneous Memory Management)" 2902 depends on TRANSPARENT_HUGEPAGE 2903 depends on DEVICE_PRIVATE 2904 select HMM_MIRROR 2905 select MMU_NOTIFIER 2906 help 2907 This is a pseudo device driver solely for testing HMM. 2908 Say M here if you want to build the HMM test module. 2909 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests. 2910 2911 If unsure, say N. 2912 2913config TEST_FREE_PAGES 2914 tristate "Test freeing pages" 2915 help 2916 Test that a memory leak does not occur due to a race between 2917 freeing a block of pages and a speculative page reference. 2918 Loading this module is safe if your kernel has the bug fixed. 2919 If the bug is not fixed, it will leak gigabytes of memory and 2920 probably OOM your system. 2921 2922config TEST_FPU 2923 tristate "Test floating point operations in kernel space" 2924 depends on X86 && !KCOV_INSTRUMENT_ALL 2925 help 2926 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu 2927 which will trigger a sequence of floating point operations. This is used 2928 for self-testing floating point control register setting in 2929 kernel_fpu_begin(). 2930 2931 If unsure, say N. 2932 2933config TEST_CLOCKSOURCE_WATCHDOG 2934 tristate "Test clocksource watchdog in kernel space" 2935 depends on CLOCKSOURCE_WATCHDOG 2936 help 2937 Enable this option to create a kernel module that will trigger 2938 a test of the clocksource watchdog. This module may be loaded 2939 via modprobe or insmod in which case it will run upon being 2940 loaded, or it may be built in, in which case it will run 2941 shortly after boot. 2942 2943 If unsure, say N. 2944 2945config TEST_OBJPOOL 2946 tristate "Test module for correctness and stress of objpool" 2947 default n 2948 depends on m && DEBUG_KERNEL 2949 help 2950 This builds the "test_objpool" module that should be used for 2951 correctness verification and concurrent testings of objects 2952 allocation and reclamation. 2953 2954 If unsure, say N. 2955 2956endif # RUNTIME_TESTING_MENU 2957 2958config ARCH_USE_MEMTEST 2959 bool 2960 help 2961 An architecture should select this when it uses early_memtest() 2962 during boot process. 2963 2964config MEMTEST 2965 bool "Memtest" 2966 depends on ARCH_USE_MEMTEST 2967 help 2968 This option adds a kernel parameter 'memtest', which allows memtest 2969 to be set and executed. 2970 memtest=0, mean disabled; -- default 2971 memtest=1, mean do 1 test pattern; 2972 ... 2973 memtest=17, mean do 17 test patterns. 2974 If you are unsure how to answer this question, answer N. 2975 2976 2977 2978config HYPERV_TESTING 2979 bool "Microsoft Hyper-V driver testing" 2980 default n 2981 depends on HYPERV && DEBUG_FS 2982 help 2983 Select this option to enable Hyper-V vmbus testing. 2984 2985endmenu # "Kernel Testing and Coverage" 2986 2987menu "Rust hacking" 2988 2989config RUST_DEBUG_ASSERTIONS 2990 bool "Debug assertions" 2991 depends on RUST 2992 help 2993 Enables rustc's `-Cdebug-assertions` codegen option. 2994 2995 This flag lets you turn `cfg(debug_assertions)` conditional 2996 compilation on or off. This can be used to enable extra debugging 2997 code in development but not in production. For example, it controls 2998 the behavior of the standard library's `debug_assert!` macro. 2999 3000 Note that this will apply to all Rust code, including `core`. 3001 3002 If unsure, say N. 3003 3004config RUST_OVERFLOW_CHECKS 3005 bool "Overflow checks" 3006 default y 3007 depends on RUST 3008 help 3009 Enables rustc's `-Coverflow-checks` codegen option. 3010 3011 This flag allows you to control the behavior of runtime integer 3012 overflow. When overflow-checks are enabled, a Rust panic will occur 3013 on overflow. 3014 3015 Note that this will apply to all Rust code, including `core`. 3016 3017 If unsure, say Y. 3018 3019config RUST_BUILD_ASSERT_ALLOW 3020 bool "Allow unoptimized build-time assertions" 3021 depends on RUST 3022 help 3023 Controls how are `build_error!` and `build_assert!` handled during build. 3024 3025 If calls to them exist in the binary, it may indicate a violated invariant 3026 or that the optimizer failed to verify the invariant during compilation. 3027 3028 This should not happen, thus by default the build is aborted. However, 3029 as an escape hatch, you can choose Y here to ignore them during build 3030 and let the check be carried at runtime (with `panic!` being called if 3031 the check fails). 3032 3033 If unsure, say N. 3034 3035config RUST_KERNEL_DOCTESTS 3036 bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS 3037 depends on RUST && KUNIT=y 3038 default KUNIT_ALL_TESTS 3039 help 3040 This builds the documentation tests of the `kernel` crate 3041 as KUnit tests. 3042 3043 For more information on KUnit and unit tests in general, 3044 please refer to the KUnit documentation in Documentation/dev-tools/kunit/. 3045 3046 If unsure, say N. 3047 3048endmenu # "Rust" 3049 3050endmenu # Kernel hacking 3051