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 jiffy" 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 type information" 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 bool "Generate BTF type information for kernel modules" 412 default y 413 depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF 414 help 415 Generate compact split BTF type information for kernel modules. 416 417config MODULE_ALLOW_BTF_MISMATCH 418 bool "Allow loading modules with non-matching BTF type info" 419 depends on DEBUG_INFO_BTF_MODULES 420 help 421 For modules whose split BTF does not match vmlinux, load without 422 BTF rather than refusing to load. The default behavior with 423 module BTF enabled is to reject modules with such mismatches; 424 this option will still load module BTF where possible but ignore 425 it when a mismatch is found. 426 427config GDB_SCRIPTS 428 bool "Provide GDB scripts for kernel debugging" 429 help 430 This creates the required links to GDB helper scripts in the 431 build directory. If you load vmlinux into gdb, the helper 432 scripts will be automatically imported by gdb as well, and 433 additional functions are available to analyze a Linux kernel 434 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst 435 for further details. 436 437endif # DEBUG_INFO 438 439config FRAME_WARN 440 int "Warn for stack frames larger than" 441 range 0 8192 442 default 0 if KMSAN 443 default 2048 if GCC_PLUGIN_LATENT_ENTROPY 444 default 2048 if PARISC 445 default 1536 if (!64BIT && XTENSA) 446 default 1280 if KASAN && !64BIT 447 default 1024 if !64BIT 448 default 2048 if 64BIT 449 help 450 Tell the compiler to warn at build time for stack frames larger than this. 451 Setting this too low will cause a lot of warnings. 452 Setting it to 0 disables the warning. 453 454config STRIP_ASM_SYMS 455 bool "Strip assembler-generated symbols during link" 456 default n 457 help 458 Strip internal assembler-generated symbols during a link (symbols 459 that look like '.Lxxx') so they don't pollute the output of 460 get_wchan() and suchlike. 461 462config READABLE_ASM 463 bool "Generate readable assembler code" 464 depends on DEBUG_KERNEL 465 depends on CC_IS_GCC 466 help 467 Disable some compiler optimizations that tend to generate human unreadable 468 assembler output. This may make the kernel slightly slower, but it helps 469 to keep kernel developers who have to stare a lot at assembler listings 470 sane. 471 472config HEADERS_INSTALL 473 bool "Install uapi headers to usr/include" 474 depends on !UML 475 help 476 This option will install uapi headers (headers exported to user-space) 477 into the usr/include directory for use during the kernel build. 478 This is unneeded for building the kernel itself, but needed for some 479 user-space program samples. It is also needed by some features such 480 as uapi header sanity checks. 481 482config DEBUG_SECTION_MISMATCH 483 bool "Enable full Section mismatch analysis" 484 depends on CC_IS_GCC 485 help 486 The section mismatch analysis checks if there are illegal 487 references from one section to another section. 488 During linktime or runtime, some sections are dropped; 489 any use of code/data previously in these sections would 490 most likely result in an oops. 491 In the code, functions and variables are annotated with 492 __init,, etc. (see the full list in include/linux/init.h), 493 which results in the code/data being placed in specific sections. 494 The section mismatch analysis is always performed after a full 495 kernel build, and enabling this option causes the following 496 additional step to occur: 497 - Add the option -fno-inline-functions-called-once to gcc commands. 498 When inlining a function annotated with __init in a non-init 499 function, we would lose the section information and thus 500 the analysis would not catch the illegal reference. 501 This option tells gcc to inline less (but it does result in 502 a larger kernel). 503 504config SECTION_MISMATCH_WARN_ONLY 505 bool "Make section mismatch errors non-fatal" 506 default y 507 help 508 If you say N here, the build process will fail if there are any 509 section mismatch, instead of just throwing warnings. 510 511 If unsure, say Y. 512 513config DEBUG_FORCE_FUNCTION_ALIGN_64B 514 bool "Force all function address 64B aligned" 515 depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC || RISCV || S390) 516 select FUNCTION_ALIGNMENT_64B 517 help 518 There are cases that a commit from one domain changes the function 519 address alignment of other domains, and cause magic performance 520 bump (regression or improvement). Enable this option will help to 521 verify if the bump is caused by function alignment changes, while 522 it will slightly increase the kernel size and affect icache usage. 523 524 It is mainly for debug and performance tuning use. 525 526# 527# Select this config option from the architecture Kconfig, if it 528# is preferred to always offer frame pointers as a config 529# option on the architecture (regardless of KERNEL_DEBUG): 530# 531config ARCH_WANT_FRAME_POINTERS 532 bool 533 534config FRAME_POINTER 535 bool "Compile the kernel with frame pointers" 536 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS 537 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 538 help 539 If you say Y here the resulting kernel image will be slightly 540 larger and slower, but it gives very useful debugging information 541 in case of kernel bugs. (precise oopses/stacktraces/warnings) 542 543config OBJTOOL 544 bool 545 546config STACK_VALIDATION 547 bool "Compile-time stack metadata validation" 548 depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER 549 select OBJTOOL 550 default n 551 help 552 Validate frame pointer rules at compile-time. This helps ensure that 553 runtime stack traces are more reliable. 554 555 For more information, see 556 tools/objtool/Documentation/objtool.txt. 557 558config NOINSTR_VALIDATION 559 bool 560 depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY 561 select OBJTOOL 562 default y 563 564config VMLINUX_MAP 565 bool "Generate vmlinux.map file when linking" 566 depends on EXPERT 567 help 568 Selecting this option will pass "-Map=vmlinux.map" to ld 569 when linking vmlinux. That file can be useful for verifying 570 and debugging magic section games, and for seeing which 571 pieces of code get eliminated with 572 CONFIG_LD_DEAD_CODE_DATA_ELIMINATION. 573 574config DEBUG_FORCE_WEAK_PER_CPU 575 bool "Force weak per-cpu definitions" 576 depends on DEBUG_KERNEL 577 help 578 s390 and alpha require percpu variables in modules to be 579 defined weak to work around addressing range issue which 580 puts the following two restrictions on percpu variable 581 definitions. 582 583 1. percpu symbols must be unique whether static or not 584 2. percpu variables can't be defined inside a function 585 586 To ensure that generic code follows the above rules, this 587 option forces all percpu variables to be defined as weak. 588 589endmenu # "Compiler options" 590 591menu "Generic Kernel Debugging Instruments" 592 593config MAGIC_SYSRQ 594 bool "Magic SysRq key" 595 depends on !UML 596 help 597 If you say Y here, you will have some control over the system even 598 if the system crashes for example during kernel debugging (e.g., you 599 will be able to flush the buffer cache to disk, reboot the system 600 immediately or dump some status information). This is accomplished 601 by pressing various keys while holding SysRq (Alt+PrintScreen). It 602 also works on a serial console (on PC hardware at least), if you 603 send a BREAK and then within 5 seconds a command keypress. The 604 keys are documented in <file:Documentation/admin-guide/sysrq.rst>. 605 Don't say Y unless you really know what this hack does. 606 607config MAGIC_SYSRQ_DEFAULT_ENABLE 608 hex "Enable magic SysRq key functions by default" 609 depends on MAGIC_SYSRQ 610 default 0x1 611 help 612 Specifies which SysRq key functions are enabled by default. 613 This may be set to 1 or 0 to enable or disable them all, or 614 to a bitmask as described in Documentation/admin-guide/sysrq.rst. 615 616config MAGIC_SYSRQ_SERIAL 617 bool "Enable magic SysRq key over serial" 618 depends on MAGIC_SYSRQ 619 default y 620 help 621 Many embedded boards have a disconnected TTL level serial which can 622 generate some garbage that can lead to spurious false sysrq detects. 623 This option allows you to decide whether you want to enable the 624 magic SysRq key. 625 626config MAGIC_SYSRQ_SERIAL_SEQUENCE 627 string "Char sequence that enables magic SysRq over serial" 628 depends on MAGIC_SYSRQ_SERIAL 629 default "" 630 help 631 Specifies a sequence of characters that can follow BREAK to enable 632 SysRq on a serial console. 633 634 If unsure, leave an empty string and the option will not be enabled. 635 636config DEBUG_FS 637 bool "Debug Filesystem" 638 help 639 debugfs is a virtual file system that kernel developers use to put 640 debugging files into. Enable this option to be able to read and 641 write to these files. 642 643 For detailed documentation on the debugfs API, see 644 Documentation/filesystems/. 645 646 If unsure, say N. 647 648choice 649 prompt "Debugfs default access" 650 depends on DEBUG_FS 651 default DEBUG_FS_ALLOW_ALL 652 help 653 This selects the default access restrictions for debugfs. 654 It can be overridden with kernel command line option 655 debugfs=[on,no-mount,off]. The restrictions apply for API access 656 and filesystem registration. 657 658config DEBUG_FS_ALLOW_ALL 659 bool "Access normal" 660 help 661 No restrictions apply. Both API and filesystem registration 662 is on. This is the normal default operation. 663 664config DEBUG_FS_DISALLOW_MOUNT 665 bool "Do not register debugfs as filesystem" 666 help 667 The API is open but filesystem is not loaded. Clients can still do 668 their work and read with debug tools that do not need 669 debugfs filesystem. 670 671config DEBUG_FS_ALLOW_NONE 672 bool "No access" 673 help 674 Access is off. Clients get -PERM when trying to create nodes in 675 debugfs tree and debugfs is not registered as a filesystem. 676 Client can then back-off or continue without debugfs access. 677 678endchoice 679 680source "lib/Kconfig.kgdb" 681source "lib/Kconfig.ubsan" 682source "lib/Kconfig.kcsan" 683 684endmenu 685 686menu "Networking Debugging" 687 688source "net/Kconfig.debug" 689 690endmenu # "Networking Debugging" 691 692menu "Memory Debugging" 693 694source "mm/Kconfig.debug" 695 696config DEBUG_OBJECTS 697 bool "Debug object operations" 698 depends on DEBUG_KERNEL 699 help 700 If you say Y here, additional code will be inserted into the 701 kernel to track the life time of various objects and validate 702 the operations on those objects. 703 704config DEBUG_OBJECTS_SELFTEST 705 bool "Debug objects selftest" 706 depends on DEBUG_OBJECTS 707 help 708 This enables the selftest of the object debug code. 709 710config DEBUG_OBJECTS_FREE 711 bool "Debug objects in freed memory" 712 depends on DEBUG_OBJECTS 713 help 714 This enables checks whether a k/v free operation frees an area 715 which contains an object which has not been deactivated 716 properly. This can make kmalloc/kfree-intensive workloads 717 much slower. 718 719config DEBUG_OBJECTS_TIMERS 720 bool "Debug timer objects" 721 depends on DEBUG_OBJECTS 722 help 723 If you say Y here, additional code will be inserted into the 724 timer routines to track the life time of timer objects and 725 validate the timer operations. 726 727config DEBUG_OBJECTS_WORK 728 bool "Debug work objects" 729 depends on DEBUG_OBJECTS 730 help 731 If you say Y here, additional code will be inserted into the 732 work queue routines to track the life time of work objects and 733 validate the work operations. 734 735config DEBUG_OBJECTS_RCU_HEAD 736 bool "Debug RCU callbacks objects" 737 depends on DEBUG_OBJECTS 738 help 739 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 740 741config DEBUG_OBJECTS_PERCPU_COUNTER 742 bool "Debug percpu counter objects" 743 depends on DEBUG_OBJECTS 744 help 745 If you say Y here, additional code will be inserted into the 746 percpu counter routines to track the life time of percpu counter 747 objects and validate the percpu counter operations. 748 749config DEBUG_OBJECTS_ENABLE_DEFAULT 750 int "debug_objects bootup default value (0-1)" 751 range 0 1 752 default "1" 753 depends on DEBUG_OBJECTS 754 help 755 Debug objects boot parameter default value 756 757config SHRINKER_DEBUG 758 bool "Enable shrinker debugging support" 759 depends on DEBUG_FS 760 help 761 Say Y to enable the shrinker debugfs interface which provides 762 visibility into the kernel memory shrinkers subsystem. 763 Disable it to avoid an extra memory footprint. 764 765config DEBUG_STACK_USAGE 766 bool "Stack utilization instrumentation" 767 depends on DEBUG_KERNEL 768 help 769 Enables the display of the minimum amount of free stack which each 770 task has ever had available in the sysrq-T and sysrq-P debug output. 771 Also emits a message to dmesg when a process exits if that process 772 used more stack space than previously exiting processes. 773 774 This option will slow down process creation somewhat. 775 776config SCHED_STACK_END_CHECK 777 bool "Detect stack corruption on calls to schedule()" 778 depends on DEBUG_KERNEL 779 default n 780 help 781 This option checks for a stack overrun on calls to schedule(). 782 If the stack end location is found to be over written always panic as 783 the content of the corrupted region can no longer be trusted. 784 This is to ensure no erroneous behaviour occurs which could result in 785 data corruption or a sporadic crash at a later stage once the region 786 is examined. The runtime overhead introduced is minimal. 787 788config ARCH_HAS_DEBUG_VM_PGTABLE 789 bool 790 help 791 An architecture should select this when it can successfully 792 build and run DEBUG_VM_PGTABLE. 793 794config DEBUG_VM_IRQSOFF 795 def_bool DEBUG_VM && !PREEMPT_RT 796 797config DEBUG_VM 798 bool "Debug VM" 799 depends on DEBUG_KERNEL 800 help 801 Enable this to turn on extended checks in the virtual-memory system 802 that may impact performance. 803 804 If unsure, say N. 805 806config DEBUG_VM_SHOOT_LAZIES 807 bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation" 808 depends on DEBUG_VM 809 depends on MMU_LAZY_TLB_SHOOTDOWN 810 help 811 Enable additional IPIs that ensure lazy tlb mm references are removed 812 before the mm is freed. 813 814 If unsure, say N. 815 816config DEBUG_VM_MAPLE_TREE 817 bool "Debug VM maple trees" 818 depends on DEBUG_VM 819 select DEBUG_MAPLE_TREE 820 help 821 Enable VM maple tree debugging information and extra validations. 822 823 If unsure, say N. 824 825config DEBUG_VM_RB 826 bool "Debug VM red-black trees" 827 depends on DEBUG_VM 828 help 829 Enable VM red-black tree debugging information and extra validations. 830 831 If unsure, say N. 832 833config DEBUG_VM_PGFLAGS 834 bool "Debug page-flags operations" 835 depends on DEBUG_VM 836 help 837 Enables extra validation on page flags operations. 838 839 If unsure, say N. 840 841config DEBUG_VM_PGTABLE 842 bool "Debug arch page table for semantics compliance" 843 depends on MMU 844 depends on ARCH_HAS_DEBUG_VM_PGTABLE 845 default y if DEBUG_VM 846 help 847 This option provides a debug method which can be used to test 848 architecture page table helper functions on various platforms in 849 verifying if they comply with expected generic MM semantics. This 850 will help architecture code in making sure that any changes or 851 new additions of these helpers still conform to expected 852 semantics of the generic MM. Platforms will have to opt in for 853 this through ARCH_HAS_DEBUG_VM_PGTABLE. 854 855 If unsure, say N. 856 857config ARCH_HAS_DEBUG_VIRTUAL 858 bool 859 860config DEBUG_VIRTUAL 861 bool "Debug VM translations" 862 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL 863 help 864 Enable some costly sanity checks in virtual to page code. This can 865 catch mistakes with virt_to_page() and friends. 866 867 If unsure, say N. 868 869config DEBUG_NOMMU_REGIONS 870 bool "Debug the global anon/private NOMMU mapping region tree" 871 depends on DEBUG_KERNEL && !MMU 872 help 873 This option causes the global tree of anonymous and private mapping 874 regions to be regularly checked for invalid topology. 875 876config DEBUG_MEMORY_INIT 877 bool "Debug memory initialisation" if EXPERT 878 default !EXPERT 879 help 880 Enable this for additional checks during memory initialisation. 881 The sanity checks verify aspects of the VM such as the memory model 882 and other information provided by the architecture. Verbose 883 information will be printed at KERN_DEBUG loglevel depending 884 on the mminit_loglevel= command-line option. 885 886 If unsure, say Y 887 888config MEMORY_NOTIFIER_ERROR_INJECT 889 tristate "Memory hotplug notifier error injection module" 890 depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION 891 help 892 This option provides the ability to inject artificial errors to 893 memory hotplug notifier chain callbacks. It is controlled through 894 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 895 896 If the notifier call chain should be failed with some events 897 notified, write the error code to "actions/<notifier event>/error". 898 899 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 900 901 # cd /sys/kernel/debug/notifier-error-inject/memory 902 # echo -12 > actions/MEM_GOING_OFFLINE/error 903 # echo offline > /sys/devices/system/memory/memoryXXX/state 904 bash: echo: write error: Cannot allocate memory 905 906 To compile this code as a module, choose M here: the module will 907 be called memory-notifier-error-inject. 908 909 If unsure, say N. 910 911config DEBUG_PER_CPU_MAPS 912 bool "Debug access to per_cpu maps" 913 depends on DEBUG_KERNEL 914 depends on SMP 915 help 916 Say Y to verify that the per_cpu map being accessed has 917 been set up. This adds a fair amount of code to kernel memory 918 and decreases performance. 919 920 Say N if unsure. 921 922config DEBUG_KMAP_LOCAL 923 bool "Debug kmap_local temporary mappings" 924 depends on DEBUG_KERNEL && KMAP_LOCAL 925 help 926 This option enables additional error checking for the kmap_local 927 infrastructure. Disable for production use. 928 929config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 930 bool 931 932config DEBUG_KMAP_LOCAL_FORCE_MAP 933 bool "Enforce kmap_local temporary mappings" 934 depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 935 select KMAP_LOCAL 936 select DEBUG_KMAP_LOCAL 937 help 938 This option enforces temporary mappings through the kmap_local 939 mechanism for non-highmem pages and on non-highmem systems. 940 Disable this for production systems! 941 942config DEBUG_HIGHMEM 943 bool "Highmem debugging" 944 depends on DEBUG_KERNEL && HIGHMEM 945 select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 946 select DEBUG_KMAP_LOCAL 947 help 948 This option enables additional error checking for high memory 949 systems. Disable for production systems. 950 951config HAVE_DEBUG_STACKOVERFLOW 952 bool 953 954config DEBUG_STACKOVERFLOW 955 bool "Check for stack overflows" 956 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 957 help 958 Say Y here if you want to check for overflows of kernel, IRQ 959 and exception stacks (if your architecture uses them). This 960 option will show detailed messages if free stack space drops 961 below a certain limit. 962 963 These kinds of bugs usually occur when call-chains in the 964 kernel get too deep, especially when interrupts are 965 involved. 966 967 Use this in cases where you see apparently random memory 968 corruption, especially if it appears in 'struct thread_info' 969 970 If in doubt, say "N". 971 972config CODE_TAGGING 973 bool 974 select KALLSYMS 975 976config MEM_ALLOC_PROFILING 977 bool "Enable memory allocation profiling" 978 default n 979 depends on PROC_FS 980 depends on !DEBUG_FORCE_WEAK_PER_CPU 981 select CODE_TAGGING 982 select PAGE_EXTENSION 983 select SLAB_OBJ_EXT 984 help 985 Track allocation source code and record total allocation size 986 initiated at that code location. The mechanism can be used to track 987 memory leaks with a low performance and memory impact. 988 989config MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT 990 bool "Enable memory allocation profiling by default" 991 default y 992 depends on MEM_ALLOC_PROFILING 993 994config MEM_ALLOC_PROFILING_DEBUG 995 bool "Memory allocation profiler debugging" 996 default n 997 depends on MEM_ALLOC_PROFILING 998 select MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT 999 help 1000 Adds warnings with helpful error messages for memory allocation 1001 profiling. 1002 1003source "lib/Kconfig.kasan" 1004source "lib/Kconfig.kfence" 1005source "lib/Kconfig.kmsan" 1006 1007endmenu # "Memory Debugging" 1008 1009config DEBUG_SHIRQ 1010 bool "Debug shared IRQ handlers" 1011 depends on DEBUG_KERNEL 1012 help 1013 Enable this to generate a spurious interrupt just before a shared 1014 interrupt handler is deregistered (generating one when registering 1015 is currently disabled). Drivers need to handle this correctly. Some 1016 don't and need to be caught. 1017 1018menu "Debug Oops, Lockups and Hangs" 1019 1020config PANIC_ON_OOPS 1021 bool "Panic on Oops" 1022 help 1023 Say Y here to enable the kernel to panic when it oopses. This 1024 has the same effect as setting oops=panic on the kernel command 1025 line. 1026 1027 This feature is useful to ensure that the kernel does not do 1028 anything erroneous after an oops which could result in data 1029 corruption or other issues. 1030 1031 Say N if unsure. 1032 1033config PANIC_ON_OOPS_VALUE 1034 int 1035 range 0 1 1036 default 0 if !PANIC_ON_OOPS 1037 default 1 if PANIC_ON_OOPS 1038 1039config PANIC_TIMEOUT 1040 int "panic timeout" 1041 default 0 1042 help 1043 Set the timeout value (in seconds) until a reboot occurs when 1044 the kernel panics. If n = 0, then we wait forever. A timeout 1045 value n > 0 will wait n seconds before rebooting, while a timeout 1046 value n < 0 will reboot immediately. This setting can be overridden 1047 with the kernel command line option panic=, and from userspace via 1048 /proc/sys/kernel/panic. 1049 1050config LOCKUP_DETECTOR 1051 bool 1052 1053config SOFTLOCKUP_DETECTOR 1054 bool "Detect Soft Lockups" 1055 depends on DEBUG_KERNEL && !S390 1056 select LOCKUP_DETECTOR 1057 help 1058 Say Y here to enable the kernel to act as a watchdog to detect 1059 soft lockups. 1060 1061 Softlockups are bugs that cause the kernel to loop in kernel 1062 mode for more than 20 seconds, without giving other tasks a 1063 chance to run. The current stack trace is displayed upon 1064 detection and the system will stay locked up. 1065 1066config SOFTLOCKUP_DETECTOR_INTR_STORM 1067 bool "Detect Interrupt Storm in Soft Lockups" 1068 depends on SOFTLOCKUP_DETECTOR && IRQ_TIME_ACCOUNTING 1069 select GENERIC_IRQ_STAT_SNAPSHOT 1070 default y if NR_CPUS <= 128 1071 help 1072 Say Y here to enable the kernel to detect interrupt storm 1073 during "soft lockups". 1074 1075 "soft lockups" can be caused by a variety of reasons. If one is 1076 caused by an interrupt storm, then the storming interrupts will not 1077 be on the callstack. To detect this case, it is necessary to report 1078 the CPU stats and the interrupt counts during the "soft lockups". 1079 1080config BOOTPARAM_SOFTLOCKUP_PANIC 1081 bool "Panic (Reboot) On Soft Lockups" 1082 depends on SOFTLOCKUP_DETECTOR 1083 help 1084 Say Y here to enable the kernel to panic on "soft lockups", 1085 which are bugs that cause the kernel to loop in kernel 1086 mode for more than 20 seconds (configurable using the watchdog_thresh 1087 sysctl), without giving other tasks a chance to run. 1088 1089 The panic can be used in combination with panic_timeout, 1090 to cause the system to reboot automatically after a 1091 lockup has been detected. This feature is useful for 1092 high-availability systems that have uptime guarantees and 1093 where a lockup must be resolved ASAP. 1094 1095 Say N if unsure. 1096 1097config HAVE_HARDLOCKUP_DETECTOR_BUDDY 1098 bool 1099 depends on SMP 1100 default y 1101 1102# 1103# Global switch whether to build a hardlockup detector at all. It is available 1104# only when the architecture supports at least one implementation. There are 1105# two exceptions. The hardlockup detector is never enabled on: 1106# 1107# s390: it reported many false positives there 1108# 1109# sparc64: has a custom implementation which is not using the common 1110# hardlockup command line options and sysctl interface. 1111# 1112config HARDLOCKUP_DETECTOR 1113 bool "Detect Hard Lockups" 1114 depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64 1115 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH 1116 imply HARDLOCKUP_DETECTOR_PERF 1117 imply HARDLOCKUP_DETECTOR_BUDDY 1118 imply HARDLOCKUP_DETECTOR_ARCH 1119 select LOCKUP_DETECTOR 1120 1121 help 1122 Say Y here to enable the kernel to act as a watchdog to detect 1123 hard lockups. 1124 1125 Hardlockups are bugs that cause the CPU to loop in kernel mode 1126 for more than 10 seconds, without letting other interrupts have a 1127 chance to run. The current stack trace is displayed upon detection 1128 and the system will stay locked up. 1129 1130# 1131# Note that arch-specific variants are always preferred. 1132# 1133config HARDLOCKUP_DETECTOR_PREFER_BUDDY 1134 bool "Prefer the buddy CPU hardlockup detector" 1135 depends on HARDLOCKUP_DETECTOR 1136 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY 1137 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1138 help 1139 Say Y here to prefer the buddy hardlockup detector over the perf one. 1140 1141 With the buddy detector, each CPU uses its softlockup hrtimer 1142 to check that the next CPU is processing hrtimer interrupts by 1143 verifying that a counter is increasing. 1144 1145 This hardlockup detector is useful on systems that don't have 1146 an arch-specific hardlockup detector or if resources needed 1147 for the hardlockup detector are better used for other things. 1148 1149config HARDLOCKUP_DETECTOR_PERF 1150 bool 1151 depends on HARDLOCKUP_DETECTOR 1152 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY 1153 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1154 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1155 1156config HARDLOCKUP_DETECTOR_BUDDY 1157 bool 1158 depends on HARDLOCKUP_DETECTOR 1159 depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY 1160 depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY 1161 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1162 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1163 1164config HARDLOCKUP_DETECTOR_ARCH 1165 bool 1166 depends on HARDLOCKUP_DETECTOR 1167 depends on HAVE_HARDLOCKUP_DETECTOR_ARCH 1168 help 1169 The arch-specific implementation of the hardlockup detector will 1170 be used. 1171 1172# 1173# Both the "perf" and "buddy" hardlockup detectors count hrtimer 1174# interrupts. This config enables functions managing this common code. 1175# 1176config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1177 bool 1178 select SOFTLOCKUP_DETECTOR 1179 1180# 1181# Enables a timestamp based low pass filter to compensate for perf based 1182# hard lockup detection which runs too fast due to turbo modes. 1183# 1184config HARDLOCKUP_CHECK_TIMESTAMP 1185 bool 1186 1187config BOOTPARAM_HARDLOCKUP_PANIC 1188 bool "Panic (Reboot) On Hard Lockups" 1189 depends on HARDLOCKUP_DETECTOR 1190 help 1191 Say Y here to enable the kernel to panic on "hard lockups", 1192 which are bugs that cause the kernel to loop in kernel 1193 mode with interrupts disabled for more than 10 seconds (configurable 1194 using the watchdog_thresh sysctl). 1195 1196 Say N if unsure. 1197 1198config DETECT_HUNG_TASK 1199 bool "Detect Hung Tasks" 1200 depends on DEBUG_KERNEL 1201 default SOFTLOCKUP_DETECTOR 1202 help 1203 Say Y here to enable the kernel to detect "hung tasks", 1204 which are bugs that cause the task to be stuck in 1205 uninterruptible "D" state indefinitely. 1206 1207 When a hung task is detected, the kernel will print the 1208 current stack trace (which you should report), but the 1209 task will stay in uninterruptible state. If lockdep is 1210 enabled then all held locks will also be reported. This 1211 feature has negligible overhead. 1212 1213config DEFAULT_HUNG_TASK_TIMEOUT 1214 int "Default timeout for hung task detection (in seconds)" 1215 depends on DETECT_HUNG_TASK 1216 default 120 1217 help 1218 This option controls the default timeout (in seconds) used 1219 to determine when a task has become non-responsive and should 1220 be considered hung. 1221 1222 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 1223 sysctl or by writing a value to 1224 /proc/sys/kernel/hung_task_timeout_secs. 1225 1226 A timeout of 0 disables the check. The default is two minutes. 1227 Keeping the default should be fine in most cases. 1228 1229config BOOTPARAM_HUNG_TASK_PANIC 1230 bool "Panic (Reboot) On Hung Tasks" 1231 depends on DETECT_HUNG_TASK 1232 help 1233 Say Y here to enable the kernel to panic on "hung tasks", 1234 which are bugs that cause the kernel to leave a task stuck 1235 in uninterruptible "D" state. 1236 1237 The panic can be used in combination with panic_timeout, 1238 to cause the system to reboot automatically after a 1239 hung task has been detected. This feature is useful for 1240 high-availability systems that have uptime guarantees and 1241 where a hung tasks must be resolved ASAP. 1242 1243 Say N if unsure. 1244 1245config WQ_WATCHDOG 1246 bool "Detect Workqueue Stalls" 1247 depends on DEBUG_KERNEL 1248 help 1249 Say Y here to enable stall detection on workqueues. If a 1250 worker pool doesn't make forward progress on a pending work 1251 item for over a given amount of time, 30s by default, a 1252 warning message is printed along with dump of workqueue 1253 state. This can be configured through kernel parameter 1254 "workqueue.watchdog_thresh" and its sysfs counterpart. 1255 1256config WQ_CPU_INTENSIVE_REPORT 1257 bool "Report per-cpu work items which hog CPU for too long" 1258 depends on DEBUG_KERNEL 1259 help 1260 Say Y here to enable reporting of concurrency-managed per-cpu work 1261 items that hog CPUs for longer than 1262 workqueue.cpu_intensive_thresh_us. Workqueue automatically 1263 detects and excludes them from concurrency management to prevent 1264 them from stalling other per-cpu work items. Occassional 1265 triggering may not necessarily indicate a problem. Repeated 1266 triggering likely indicates that the work item should be switched 1267 to use an unbound workqueue. 1268 1269config TEST_LOCKUP 1270 tristate "Test module to generate lockups" 1271 depends on m 1272 help 1273 This builds the "test_lockup" module that helps to make sure 1274 that watchdogs and lockup detectors are working properly. 1275 1276 Depending on module parameters it could emulate soft or hard 1277 lockup, "hung task", or locking arbitrary lock for a long time. 1278 Also it could generate series of lockups with cooling-down periods. 1279 1280 If unsure, say N. 1281 1282endmenu # "Debug lockups and hangs" 1283 1284menu "Scheduler Debugging" 1285 1286config SCHED_DEBUG 1287 bool "Collect scheduler debugging info" 1288 depends on DEBUG_KERNEL && DEBUG_FS 1289 default y 1290 help 1291 If you say Y here, the /sys/kernel/debug/sched file will be provided 1292 that can help debug the scheduler. The runtime overhead of this 1293 option is minimal. 1294 1295config SCHED_INFO 1296 bool 1297 default n 1298 1299config SCHEDSTATS 1300 bool "Collect scheduler statistics" 1301 depends on PROC_FS 1302 select SCHED_INFO 1303 help 1304 If you say Y here, additional code will be inserted into the 1305 scheduler and related routines to collect statistics about 1306 scheduler behavior and provide them in /proc/schedstat. These 1307 stats may be useful for both tuning and debugging the scheduler 1308 If you aren't debugging the scheduler or trying to tune a specific 1309 application, you can say N to avoid the very slight overhead 1310 this adds. 1311 1312endmenu 1313 1314config DEBUG_TIMEKEEPING 1315 bool "Enable extra timekeeping sanity checking" 1316 help 1317 This option will enable additional timekeeping sanity checks 1318 which may be helpful when diagnosing issues where timekeeping 1319 problems are suspected. 1320 1321 This may include checks in the timekeeping hotpaths, so this 1322 option may have a (very small) performance impact to some 1323 workloads. 1324 1325 If unsure, say N. 1326 1327config DEBUG_PREEMPT 1328 bool "Debug preemptible kernel" 1329 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1330 help 1331 If you say Y here then the kernel will use a debug variant of the 1332 commonly used smp_processor_id() function and will print warnings 1333 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1334 will detect preemption count underflows. 1335 1336 This option has potential to introduce high runtime overhead, 1337 depending on workload as it triggers debugging routines for each 1338 this_cpu operation. It should only be used for debugging purposes. 1339 1340menu "Lock Debugging (spinlocks, mutexes, etc...)" 1341 1342config LOCK_DEBUGGING_SUPPORT 1343 bool 1344 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1345 default y 1346 1347config PROVE_LOCKING 1348 bool "Lock debugging: prove locking correctness" 1349 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1350 select LOCKDEP 1351 select DEBUG_SPINLOCK 1352 select DEBUG_MUTEXES if !PREEMPT_RT 1353 select DEBUG_RT_MUTEXES if RT_MUTEXES 1354 select DEBUG_RWSEMS if !PREEMPT_RT 1355 select DEBUG_WW_MUTEX_SLOWPATH 1356 select DEBUG_LOCK_ALLOC 1357 select PREEMPT_COUNT if !ARCH_NO_PREEMPT 1358 select TRACE_IRQFLAGS 1359 default n 1360 help 1361 This feature enables the kernel to prove that all locking 1362 that occurs in the kernel runtime is mathematically 1363 correct: that under no circumstance could an arbitrary (and 1364 not yet triggered) combination of observed locking 1365 sequences (on an arbitrary number of CPUs, running an 1366 arbitrary number of tasks and interrupt contexts) cause a 1367 deadlock. 1368 1369 In short, this feature enables the kernel to report locking 1370 related deadlocks before they actually occur. 1371 1372 The proof does not depend on how hard and complex a 1373 deadlock scenario would be to trigger: how many 1374 participant CPUs, tasks and irq-contexts would be needed 1375 for it to trigger. The proof also does not depend on 1376 timing: if a race and a resulting deadlock is possible 1377 theoretically (no matter how unlikely the race scenario 1378 is), it will be proven so and will immediately be 1379 reported by the kernel (once the event is observed that 1380 makes the deadlock theoretically possible). 1381 1382 If a deadlock is impossible (i.e. the locking rules, as 1383 observed by the kernel, are mathematically correct), the 1384 kernel reports nothing. 1385 1386 NOTE: this feature can also be enabled for rwlocks, mutexes 1387 and rwsems - in which case all dependencies between these 1388 different locking variants are observed and mapped too, and 1389 the proof of observed correctness is also maintained for an 1390 arbitrary combination of these separate locking variants. 1391 1392 For more details, see Documentation/locking/lockdep-design.rst. 1393 1394config PROVE_RAW_LOCK_NESTING 1395 bool "Enable raw_spinlock - spinlock nesting checks" 1396 depends on PROVE_LOCKING 1397 default n 1398 help 1399 Enable the raw_spinlock vs. spinlock nesting checks which ensure 1400 that the lock nesting rules for PREEMPT_RT enabled kernels are 1401 not violated. 1402 1403 NOTE: There are known nesting problems. So if you enable this 1404 option expect lockdep splats until these problems have been fully 1405 addressed which is work in progress. This config switch allows to 1406 identify and analyze these problems. It will be removed and the 1407 check permanently enabled once the main issues have been fixed. 1408 1409 If unsure, select N. 1410 1411config LOCK_STAT 1412 bool "Lock usage statistics" 1413 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1414 select LOCKDEP 1415 select DEBUG_SPINLOCK 1416 select DEBUG_MUTEXES if !PREEMPT_RT 1417 select DEBUG_RT_MUTEXES if RT_MUTEXES 1418 select DEBUG_LOCK_ALLOC 1419 default n 1420 help 1421 This feature enables tracking lock contention points 1422 1423 For more details, see Documentation/locking/lockstat.rst 1424 1425 This also enables lock events required by "perf lock", 1426 subcommand of perf. 1427 If you want to use "perf lock", you also need to turn on 1428 CONFIG_EVENT_TRACING. 1429 1430 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1431 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1432 1433config DEBUG_RT_MUTEXES 1434 bool "RT Mutex debugging, deadlock detection" 1435 depends on DEBUG_KERNEL && RT_MUTEXES 1436 help 1437 This allows rt mutex semantics violations and rt mutex related 1438 deadlocks (lockups) to be detected and reported automatically. 1439 1440config DEBUG_SPINLOCK 1441 bool "Spinlock and rw-lock debugging: basic checks" 1442 depends on DEBUG_KERNEL 1443 select UNINLINE_SPIN_UNLOCK 1444 help 1445 Say Y here and build SMP to catch missing spinlock initialization 1446 and certain other kinds of spinlock errors commonly made. This is 1447 best used in conjunction with the NMI watchdog so that spinlock 1448 deadlocks are also debuggable. 1449 1450config DEBUG_MUTEXES 1451 bool "Mutex debugging: basic checks" 1452 depends on DEBUG_KERNEL && !PREEMPT_RT 1453 help 1454 This feature allows mutex semantics violations to be detected and 1455 reported. 1456 1457config DEBUG_WW_MUTEX_SLOWPATH 1458 bool "Wait/wound mutex debugging: Slowpath testing" 1459 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1460 select DEBUG_LOCK_ALLOC 1461 select DEBUG_SPINLOCK 1462 select DEBUG_MUTEXES if !PREEMPT_RT 1463 select DEBUG_RT_MUTEXES if PREEMPT_RT 1464 help 1465 This feature enables slowpath testing for w/w mutex users by 1466 injecting additional -EDEADLK wound/backoff cases. Together with 1467 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1468 will test all possible w/w mutex interface abuse with the 1469 exception of simply not acquiring all the required locks. 1470 Note that this feature can introduce significant overhead, so 1471 it really should not be enabled in a production or distro kernel, 1472 even a debug kernel. If you are a driver writer, enable it. If 1473 you are a distro, do not. 1474 1475config DEBUG_RWSEMS 1476 bool "RW Semaphore debugging: basic checks" 1477 depends on DEBUG_KERNEL && !PREEMPT_RT 1478 help 1479 This debugging feature allows mismatched rw semaphore locks 1480 and unlocks to be detected and reported. 1481 1482config DEBUG_LOCK_ALLOC 1483 bool "Lock debugging: detect incorrect freeing of live locks" 1484 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1485 select DEBUG_SPINLOCK 1486 select DEBUG_MUTEXES if !PREEMPT_RT 1487 select DEBUG_RT_MUTEXES if RT_MUTEXES 1488 select LOCKDEP 1489 help 1490 This feature will check whether any held lock (spinlock, rwlock, 1491 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1492 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1493 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1494 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1495 held during task exit. 1496 1497config LOCKDEP 1498 bool 1499 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1500 select STACKTRACE 1501 select KALLSYMS 1502 select KALLSYMS_ALL 1503 1504config LOCKDEP_SMALL 1505 bool 1506 1507config LOCKDEP_BITS 1508 int "Bitsize for MAX_LOCKDEP_ENTRIES" 1509 depends on LOCKDEP && !LOCKDEP_SMALL 1510 range 10 30 1511 default 15 1512 help 1513 Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message. 1514 1515config LOCKDEP_CHAINS_BITS 1516 int "Bitsize for MAX_LOCKDEP_CHAINS" 1517 depends on LOCKDEP && !LOCKDEP_SMALL 1518 range 10 21 1519 default 16 1520 help 1521 Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message. 1522 1523config LOCKDEP_STACK_TRACE_BITS 1524 int "Bitsize for MAX_STACK_TRACE_ENTRIES" 1525 depends on LOCKDEP && !LOCKDEP_SMALL 1526 range 10 30 1527 default 19 1528 help 1529 Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message. 1530 1531config LOCKDEP_STACK_TRACE_HASH_BITS 1532 int "Bitsize for STACK_TRACE_HASH_SIZE" 1533 depends on LOCKDEP && !LOCKDEP_SMALL 1534 range 10 30 1535 default 14 1536 help 1537 Try increasing this value if you need large STACK_TRACE_HASH_SIZE. 1538 1539config LOCKDEP_CIRCULAR_QUEUE_BITS 1540 int "Bitsize for elements in circular_queue struct" 1541 depends on LOCKDEP 1542 range 10 30 1543 default 12 1544 help 1545 Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure. 1546 1547config DEBUG_LOCKDEP 1548 bool "Lock dependency engine debugging" 1549 depends on DEBUG_KERNEL && LOCKDEP 1550 select DEBUG_IRQFLAGS 1551 help 1552 If you say Y here, the lock dependency engine will do 1553 additional runtime checks to debug itself, at the price 1554 of more runtime overhead. 1555 1556config DEBUG_ATOMIC_SLEEP 1557 bool "Sleep inside atomic section checking" 1558 select PREEMPT_COUNT 1559 depends on DEBUG_KERNEL 1560 depends on !ARCH_NO_PREEMPT 1561 help 1562 If you say Y here, various routines which may sleep will become very 1563 noisy if they are called inside atomic sections: when a spinlock is 1564 held, inside an rcu read side critical section, inside preempt disabled 1565 sections, inside an interrupt, etc... 1566 1567config DEBUG_LOCKING_API_SELFTESTS 1568 bool "Locking API boot-time self-tests" 1569 depends on DEBUG_KERNEL 1570 help 1571 Say Y here if you want the kernel to run a short self-test during 1572 bootup. The self-test checks whether common types of locking bugs 1573 are detected by debugging mechanisms or not. (if you disable 1574 lock debugging then those bugs won't be detected of course.) 1575 The following locking APIs are covered: spinlocks, rwlocks, 1576 mutexes and rwsems. 1577 1578config LOCK_TORTURE_TEST 1579 tristate "torture tests for locking" 1580 depends on DEBUG_KERNEL 1581 select TORTURE_TEST 1582 help 1583 This option provides a kernel module that runs torture tests 1584 on kernel locking primitives. The kernel module may be built 1585 after the fact on the running kernel to be tested, if desired. 1586 1587 Say Y here if you want kernel locking-primitive torture tests 1588 to be built into the kernel. 1589 Say M if you want these torture tests to build as a module. 1590 Say N if you are unsure. 1591 1592config WW_MUTEX_SELFTEST 1593 tristate "Wait/wound mutex selftests" 1594 help 1595 This option provides a kernel module that runs tests on the 1596 on the struct ww_mutex locking API. 1597 1598 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1599 with this test harness. 1600 1601 Say M if you want these self tests to build as a module. 1602 Say N if you are unsure. 1603 1604config SCF_TORTURE_TEST 1605 tristate "torture tests for smp_call_function*()" 1606 depends on DEBUG_KERNEL 1607 select TORTURE_TEST 1608 help 1609 This option provides a kernel module that runs torture tests 1610 on the smp_call_function() family of primitives. The kernel 1611 module may be built after the fact on the running kernel to 1612 be tested, if desired. 1613 1614config CSD_LOCK_WAIT_DEBUG 1615 bool "Debugging for csd_lock_wait(), called from smp_call_function*()" 1616 depends on DEBUG_KERNEL 1617 depends on SMP 1618 depends on 64BIT 1619 default n 1620 help 1621 This option enables debug prints when CPUs are slow to respond 1622 to the smp_call_function*() IPI wrappers. These debug prints 1623 include the IPI handler function currently executing (if any) 1624 and relevant stack traces. 1625 1626config CSD_LOCK_WAIT_DEBUG_DEFAULT 1627 bool "Default csd_lock_wait() debugging on at boot time" 1628 depends on CSD_LOCK_WAIT_DEBUG 1629 depends on 64BIT 1630 default n 1631 help 1632 This option causes the csdlock_debug= kernel boot parameter to 1633 default to 1 (basic debugging) instead of 0 (no debugging). 1634 1635endmenu # lock debugging 1636 1637config TRACE_IRQFLAGS 1638 depends on TRACE_IRQFLAGS_SUPPORT 1639 bool 1640 help 1641 Enables hooks to interrupt enabling and disabling for 1642 either tracing or lock debugging. 1643 1644config TRACE_IRQFLAGS_NMI 1645 def_bool y 1646 depends on TRACE_IRQFLAGS 1647 depends on TRACE_IRQFLAGS_NMI_SUPPORT 1648 1649config NMI_CHECK_CPU 1650 bool "Debugging for CPUs failing to respond to backtrace requests" 1651 depends on DEBUG_KERNEL 1652 depends on X86 1653 default n 1654 help 1655 Enables debug prints when a CPU fails to respond to a given 1656 backtrace NMI. These prints provide some reasons why a CPU 1657 might legitimately be failing to respond, for example, if it 1658 is offline of if ignore_nmis is set. 1659 1660config DEBUG_IRQFLAGS 1661 bool "Debug IRQ flag manipulation" 1662 help 1663 Enables checks for potentially unsafe enabling or disabling of 1664 interrupts, such as calling raw_local_irq_restore() when interrupts 1665 are enabled. 1666 1667config STACKTRACE 1668 bool "Stack backtrace support" 1669 depends on STACKTRACE_SUPPORT 1670 help 1671 This option causes the kernel to create a /proc/pid/stack for 1672 every process, showing its current stack trace. 1673 It is also used by various kernel debugging features that require 1674 stack trace generation. 1675 1676config WARN_ALL_UNSEEDED_RANDOM 1677 bool "Warn for all uses of unseeded randomness" 1678 default n 1679 help 1680 Some parts of the kernel contain bugs relating to their use of 1681 cryptographically secure random numbers before it's actually possible 1682 to generate those numbers securely. This setting ensures that these 1683 flaws don't go unnoticed, by enabling a message, should this ever 1684 occur. This will allow people with obscure setups to know when things 1685 are going wrong, so that they might contact developers about fixing 1686 it. 1687 1688 Unfortunately, on some models of some architectures getting 1689 a fully seeded CRNG is extremely difficult, and so this can 1690 result in dmesg getting spammed for a surprisingly long 1691 time. This is really bad from a security perspective, and 1692 so architecture maintainers really need to do what they can 1693 to get the CRNG seeded sooner after the system is booted. 1694 However, since users cannot do anything actionable to 1695 address this, by default this option is disabled. 1696 1697 Say Y here if you want to receive warnings for all uses of 1698 unseeded randomness. This will be of use primarily for 1699 those developers interested in improving the security of 1700 Linux kernels running on their architecture (or 1701 subarchitecture). 1702 1703config DEBUG_KOBJECT 1704 bool "kobject debugging" 1705 depends on DEBUG_KERNEL 1706 help 1707 If you say Y here, some extra kobject debugging messages will be sent 1708 to the syslog. 1709 1710config DEBUG_KOBJECT_RELEASE 1711 bool "kobject release debugging" 1712 depends on DEBUG_OBJECTS_TIMERS 1713 help 1714 kobjects are reference counted objects. This means that their 1715 last reference count put is not predictable, and the kobject can 1716 live on past the point at which a driver decides to drop its 1717 initial reference to the kobject gained on allocation. An 1718 example of this would be a struct device which has just been 1719 unregistered. 1720 1721 However, some buggy drivers assume that after such an operation, 1722 the memory backing the kobject can be immediately freed. This 1723 goes completely against the principles of a refcounted object. 1724 1725 If you say Y here, the kernel will delay the release of kobjects 1726 on the last reference count to improve the visibility of this 1727 kind of kobject release bug. 1728 1729config HAVE_DEBUG_BUGVERBOSE 1730 bool 1731 1732menu "Debug kernel data structures" 1733 1734config DEBUG_LIST 1735 bool "Debug linked list manipulation" 1736 depends on DEBUG_KERNEL 1737 select LIST_HARDENED 1738 help 1739 Enable this to turn on extended checks in the linked-list walking 1740 routines. 1741 1742 This option trades better quality error reports for performance, and 1743 is more suitable for kernel debugging. If you care about performance, 1744 you should only enable CONFIG_LIST_HARDENED instead. 1745 1746 If unsure, say N. 1747 1748config DEBUG_PLIST 1749 bool "Debug priority linked list manipulation" 1750 depends on DEBUG_KERNEL 1751 help 1752 Enable this to turn on extended checks in the priority-ordered 1753 linked-list (plist) walking routines. This checks the entire 1754 list multiple times during each manipulation. 1755 1756 If unsure, say N. 1757 1758config DEBUG_SG 1759 bool "Debug SG table operations" 1760 depends on DEBUG_KERNEL 1761 help 1762 Enable this to turn on checks on scatter-gather tables. This can 1763 help find problems with drivers that do not properly initialize 1764 their sg tables. 1765 1766 If unsure, say N. 1767 1768config DEBUG_NOTIFIERS 1769 bool "Debug notifier call chains" 1770 depends on DEBUG_KERNEL 1771 help 1772 Enable this to turn on sanity checking for notifier call chains. 1773 This is most useful for kernel developers to make sure that 1774 modules properly unregister themselves from notifier chains. 1775 This is a relatively cheap check but if you care about maximum 1776 performance, say N. 1777 1778config DEBUG_CLOSURES 1779 bool "Debug closures (bcache async widgits)" 1780 depends on CLOSURES 1781 select DEBUG_FS 1782 help 1783 Keeps all active closures in a linked list and provides a debugfs 1784 interface to list them, which makes it possible to see asynchronous 1785 operations that get stuck. 1786 1787config DEBUG_MAPLE_TREE 1788 bool "Debug maple trees" 1789 depends on DEBUG_KERNEL 1790 help 1791 Enable maple tree debugging information and extra validations. 1792 1793 If unsure, say N. 1794 1795endmenu 1796 1797source "kernel/rcu/Kconfig.debug" 1798 1799config DEBUG_WQ_FORCE_RR_CPU 1800 bool "Force round-robin CPU selection for unbound work items" 1801 depends on DEBUG_KERNEL 1802 default n 1803 help 1804 Workqueue used to implicitly guarantee that work items queued 1805 without explicit CPU specified are put on the local CPU. This 1806 guarantee is no longer true and while local CPU is still 1807 preferred work items may be put on foreign CPUs. Kernel 1808 parameter "workqueue.debug_force_rr_cpu" is added to force 1809 round-robin CPU selection to flush out usages which depend on the 1810 now broken guarantee. This config option enables the debug 1811 feature by default. When enabled, memory and cache locality will 1812 be impacted. 1813 1814config CPU_HOTPLUG_STATE_CONTROL 1815 bool "Enable CPU hotplug state control" 1816 depends on DEBUG_KERNEL 1817 depends on HOTPLUG_CPU 1818 default n 1819 help 1820 Allows to write steps between "offline" and "online" to the CPUs 1821 sysfs target file so states can be stepped granular. This is a debug 1822 option for now as the hotplug machinery cannot be stopped and 1823 restarted at arbitrary points yet. 1824 1825 Say N if your are unsure. 1826 1827config LATENCYTOP 1828 bool "Latency measuring infrastructure" 1829 depends on DEBUG_KERNEL 1830 depends on STACKTRACE_SUPPORT 1831 depends on PROC_FS 1832 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 1833 select KALLSYMS 1834 select KALLSYMS_ALL 1835 select STACKTRACE 1836 select SCHEDSTATS 1837 help 1838 Enable this option if you want to use the LatencyTOP tool 1839 to find out which userspace is blocking on what kernel operations. 1840 1841config DEBUG_CGROUP_REF 1842 bool "Disable inlining of cgroup css reference count functions" 1843 depends on DEBUG_KERNEL 1844 depends on CGROUPS 1845 depends on KPROBES 1846 default n 1847 help 1848 Force cgroup css reference count functions to not be inlined so 1849 that they can be kprobed for debugging. 1850 1851source "kernel/trace/Kconfig" 1852 1853config PROVIDE_OHCI1394_DMA_INIT 1854 bool "Remote debugging over FireWire early on boot" 1855 depends on PCI && X86 1856 help 1857 If you want to debug problems which hang or crash the kernel early 1858 on boot and the crashing machine has a FireWire port, you can use 1859 this feature to remotely access the memory of the crashed machine 1860 over FireWire. This employs remote DMA as part of the OHCI1394 1861 specification which is now the standard for FireWire controllers. 1862 1863 With remote DMA, you can monitor the printk buffer remotely using 1864 firescope and access all memory below 4GB using fireproxy from gdb. 1865 Even controlling a kernel debugger is possible using remote DMA. 1866 1867 Usage: 1868 1869 If ohci1394_dma=early is used as boot parameter, it will initialize 1870 all OHCI1394 controllers which are found in the PCI config space. 1871 1872 As all changes to the FireWire bus such as enabling and disabling 1873 devices cause a bus reset and thereby disable remote DMA for all 1874 devices, be sure to have the cable plugged and FireWire enabled on 1875 the debugging host before booting the debug target for debugging. 1876 1877 This code (~1k) is freed after boot. By then, the firewire stack 1878 in charge of the OHCI-1394 controllers should be used instead. 1879 1880 See Documentation/core-api/debugging-via-ohci1394.rst for more information. 1881 1882source "samples/Kconfig" 1883 1884config ARCH_HAS_DEVMEM_IS_ALLOWED 1885 bool 1886 1887config STRICT_DEVMEM 1888 bool "Filter access to /dev/mem" 1889 depends on MMU && DEVMEM 1890 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED 1891 default y if PPC || X86 || ARM64 1892 help 1893 If this option is disabled, you allow userspace (root) access to all 1894 of memory, including kernel and userspace memory. Accidental 1895 access to this is obviously disastrous, but specific access can 1896 be used by people debugging the kernel. Note that with PAT support 1897 enabled, even in this case there are restrictions on /dev/mem 1898 use due to the cache aliasing requirements. 1899 1900 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 1901 file only allows userspace access to PCI space and the BIOS code and 1902 data regions. This is sufficient for dosemu and X and all common 1903 users of /dev/mem. 1904 1905 If in doubt, say Y. 1906 1907config IO_STRICT_DEVMEM 1908 bool "Filter I/O access to /dev/mem" 1909 depends on STRICT_DEVMEM 1910 help 1911 If this option is disabled, you allow userspace (root) access to all 1912 io-memory regardless of whether a driver is actively using that 1913 range. Accidental access to this is obviously disastrous, but 1914 specific access can be used by people debugging kernel drivers. 1915 1916 If this option is switched on, the /dev/mem file only allows 1917 userspace access to *idle* io-memory ranges (see /proc/iomem) This 1918 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 1919 if the driver using a given range cannot be disabled. 1920 1921 If in doubt, say Y. 1922 1923menu "$(SRCARCH) Debugging" 1924 1925source "arch/$(SRCARCH)/Kconfig.debug" 1926 1927endmenu 1928 1929menu "Kernel Testing and Coverage" 1930 1931source "lib/kunit/Kconfig" 1932 1933config NOTIFIER_ERROR_INJECTION 1934 tristate "Notifier error injection" 1935 depends on DEBUG_KERNEL 1936 select DEBUG_FS 1937 help 1938 This option provides the ability to inject artificial errors to 1939 specified notifier chain callbacks. It is useful to test the error 1940 handling of notifier call chain failures. 1941 1942 Say N if unsure. 1943 1944config PM_NOTIFIER_ERROR_INJECT 1945 tristate "PM notifier error injection module" 1946 depends on PM && NOTIFIER_ERROR_INJECTION 1947 default m if PM_DEBUG 1948 help 1949 This option provides the ability to inject artificial errors to 1950 PM notifier chain callbacks. It is controlled through debugfs 1951 interface /sys/kernel/debug/notifier-error-inject/pm 1952 1953 If the notifier call chain should be failed with some events 1954 notified, write the error code to "actions/<notifier event>/error". 1955 1956 Example: Inject PM suspend error (-12 = -ENOMEM) 1957 1958 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1959 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1960 # echo mem > /sys/power/state 1961 bash: echo: write error: Cannot allocate memory 1962 1963 To compile this code as a module, choose M here: the module will 1964 be called pm-notifier-error-inject. 1965 1966 If unsure, say N. 1967 1968config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1969 tristate "OF reconfig notifier error injection module" 1970 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1971 help 1972 This option provides the ability to inject artificial errors to 1973 OF reconfig notifier chain callbacks. It is controlled 1974 through debugfs interface under 1975 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1976 1977 If the notifier call chain should be failed with some events 1978 notified, write the error code to "actions/<notifier event>/error". 1979 1980 To compile this code as a module, choose M here: the module will 1981 be called of-reconfig-notifier-error-inject. 1982 1983 If unsure, say N. 1984 1985config NETDEV_NOTIFIER_ERROR_INJECT 1986 tristate "Netdev notifier error injection module" 1987 depends on NET && NOTIFIER_ERROR_INJECTION 1988 help 1989 This option provides the ability to inject artificial errors to 1990 netdevice notifier chain callbacks. It is controlled through debugfs 1991 interface /sys/kernel/debug/notifier-error-inject/netdev 1992 1993 If the notifier call chain should be failed with some events 1994 notified, write the error code to "actions/<notifier event>/error". 1995 1996 Example: Inject netdevice mtu change error (-22 = -EINVAL) 1997 1998 # cd /sys/kernel/debug/notifier-error-inject/netdev 1999 # echo -22 > actions/NETDEV_CHANGEMTU/error 2000 # ip link set eth0 mtu 1024 2001 RTNETLINK answers: Invalid argument 2002 2003 To compile this code as a module, choose M here: the module will 2004 be called netdev-notifier-error-inject. 2005 2006 If unsure, say N. 2007 2008config FUNCTION_ERROR_INJECTION 2009 bool "Fault-injections of functions" 2010 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 2011 help 2012 Add fault injections into various functions that are annotated with 2013 ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return 2014 value of these functions. This is useful to test error paths of code. 2015 2016 If unsure, say N 2017 2018config FAULT_INJECTION 2019 bool "Fault-injection framework" 2020 depends on DEBUG_KERNEL 2021 help 2022 Provide fault-injection framework. 2023 For more details, see Documentation/fault-injection/. 2024 2025config FAILSLAB 2026 bool "Fault-injection capability for kmalloc" 2027 depends on FAULT_INJECTION 2028 help 2029 Provide fault-injection capability for kmalloc. 2030 2031config FAIL_PAGE_ALLOC 2032 bool "Fault-injection capability for alloc_pages()" 2033 depends on FAULT_INJECTION 2034 help 2035 Provide fault-injection capability for alloc_pages(). 2036 2037config FAULT_INJECTION_USERCOPY 2038 bool "Fault injection capability for usercopy functions" 2039 depends on FAULT_INJECTION 2040 help 2041 Provides fault-injection capability to inject failures 2042 in usercopy functions (copy_from_user(), get_user(), ...). 2043 2044config FAIL_MAKE_REQUEST 2045 bool "Fault-injection capability for disk IO" 2046 depends on FAULT_INJECTION && BLOCK 2047 help 2048 Provide fault-injection capability for disk IO. 2049 2050config FAIL_IO_TIMEOUT 2051 bool "Fault-injection capability for faking disk interrupts" 2052 depends on FAULT_INJECTION && BLOCK 2053 help 2054 Provide fault-injection capability on end IO handling. This 2055 will make the block layer "forget" an interrupt as configured, 2056 thus exercising the error handling. 2057 2058 Only works with drivers that use the generic timeout handling, 2059 for others it won't do anything. 2060 2061config FAIL_FUTEX 2062 bool "Fault-injection capability for futexes" 2063 select DEBUG_FS 2064 depends on FAULT_INJECTION && FUTEX 2065 help 2066 Provide fault-injection capability for futexes. 2067 2068config FAULT_INJECTION_DEBUG_FS 2069 bool "Debugfs entries for fault-injection capabilities" 2070 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 2071 help 2072 Enable configuration of fault-injection capabilities via debugfs. 2073 2074config FAIL_FUNCTION 2075 bool "Fault-injection capability for functions" 2076 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 2077 help 2078 Provide function-based fault-injection capability. 2079 This will allow you to override a specific function with a return 2080 with given return value. As a result, function caller will see 2081 an error value and have to handle it. This is useful to test the 2082 error handling in various subsystems. 2083 2084config FAIL_MMC_REQUEST 2085 bool "Fault-injection capability for MMC IO" 2086 depends on FAULT_INJECTION_DEBUG_FS && MMC 2087 help 2088 Provide fault-injection capability for MMC IO. 2089 This will make the mmc core return data errors. This is 2090 useful to test the error handling in the mmc block device 2091 and to test how the mmc host driver handles retries from 2092 the block device. 2093 2094config FAIL_SUNRPC 2095 bool "Fault-injection capability for SunRPC" 2096 depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG 2097 help 2098 Provide fault-injection capability for SunRPC and 2099 its consumers. 2100 2101config FAULT_INJECTION_CONFIGFS 2102 bool "Configfs interface for fault-injection capabilities" 2103 depends on FAULT_INJECTION 2104 select CONFIGFS_FS 2105 help 2106 This option allows configfs-based drivers to dynamically configure 2107 fault-injection via configfs. Each parameter for driver-specific 2108 fault-injection can be made visible as a configfs attribute in a 2109 configfs group. 2110 2111 2112config FAULT_INJECTION_STACKTRACE_FILTER 2113 bool "stacktrace filter for fault-injection capabilities" 2114 depends on FAULT_INJECTION 2115 depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT 2116 select STACKTRACE 2117 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 2118 help 2119 Provide stacktrace filter for fault-injection capabilities 2120 2121config ARCH_HAS_KCOV 2122 bool 2123 help 2124 An architecture should select this when it can successfully 2125 build and run with CONFIG_KCOV. This typically requires 2126 disabling instrumentation for some early boot code. 2127 2128config CC_HAS_SANCOV_TRACE_PC 2129 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 2130 2131 2132config KCOV 2133 bool "Code coverage for fuzzing" 2134 depends on ARCH_HAS_KCOV 2135 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 2136 depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \ 2137 GCC_VERSION >= 120000 || CC_IS_CLANG 2138 select DEBUG_FS 2139 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 2140 select OBJTOOL if HAVE_NOINSTR_HACK 2141 help 2142 KCOV exposes kernel code coverage information in a form suitable 2143 for coverage-guided fuzzing (randomized testing). 2144 2145 For more details, see Documentation/dev-tools/kcov.rst. 2146 2147config KCOV_ENABLE_COMPARISONS 2148 bool "Enable comparison operands collection by KCOV" 2149 depends on KCOV 2150 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 2151 help 2152 KCOV also exposes operands of every comparison in the instrumented 2153 code along with operand sizes and PCs of the comparison instructions. 2154 These operands can be used by fuzzing engines to improve the quality 2155 of fuzzing coverage. 2156 2157config KCOV_INSTRUMENT_ALL 2158 bool "Instrument all code by default" 2159 depends on KCOV 2160 default y 2161 help 2162 If you are doing generic system call fuzzing (like e.g. syzkaller), 2163 then you will want to instrument the whole kernel and you should 2164 say y here. If you are doing more targeted fuzzing (like e.g. 2165 filesystem fuzzing with AFL) then you will want to enable coverage 2166 for more specific subsets of files, and should say n here. 2167 2168config KCOV_IRQ_AREA_SIZE 2169 hex "Size of interrupt coverage collection area in words" 2170 depends on KCOV 2171 default 0x40000 2172 help 2173 KCOV uses preallocated per-cpu areas to collect coverage from 2174 soft interrupts. This specifies the size of those areas in the 2175 number of unsigned long words. 2176 2177config KCOV_SELFTEST 2178 bool "Perform short selftests on boot" 2179 depends on KCOV 2180 help 2181 Run short KCOV coverage collection selftests on boot. 2182 On test failure, causes the kernel to panic. Recommended to be 2183 enabled, ensuring critical functionality works as intended. 2184 2185menuconfig RUNTIME_TESTING_MENU 2186 bool "Runtime Testing" 2187 default y 2188 2189if RUNTIME_TESTING_MENU 2190 2191config TEST_DHRY 2192 tristate "Dhrystone benchmark test" 2193 help 2194 Enable this to include the Dhrystone 2.1 benchmark. This test 2195 calculates the number of Dhrystones per second, and the number of 2196 DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided 2197 by 1757 (the number of Dhrystones per second obtained on the VAX 2198 11/780, nominally a 1 MIPS machine). 2199 2200 To run the benchmark, it needs to be enabled explicitly, either from 2201 the kernel command line (when built-in), or from userspace (when 2202 built-in or modular). 2203 2204 Run once during kernel boot: 2205 2206 test_dhry.run 2207 2208 Set number of iterations from kernel command line: 2209 2210 test_dhry.iterations=<n> 2211 2212 Set number of iterations from userspace: 2213 2214 echo <n> > /sys/module/test_dhry/parameters/iterations 2215 2216 Trigger manual run from userspace: 2217 2218 echo y > /sys/module/test_dhry/parameters/run 2219 2220 If the number of iterations is <= 0, the test will devise a suitable 2221 number of iterations (test runs for at least 2s) automatically. 2222 This process takes ca. 4s. 2223 2224 If unsure, say N. 2225 2226config LKDTM 2227 tristate "Linux Kernel Dump Test Tool Module" 2228 depends on DEBUG_FS 2229 help 2230 This module enables testing of the different dumping mechanisms by 2231 inducing system failures at predefined crash points. 2232 If you don't need it: say N 2233 Choose M here to compile this code as a module. The module will be 2234 called lkdtm. 2235 2236 Documentation on how to use the module can be found in 2237 Documentation/fault-injection/provoke-crashes.rst 2238 2239config CPUMASK_KUNIT_TEST 2240 tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS 2241 depends on KUNIT 2242 default KUNIT_ALL_TESTS 2243 help 2244 Enable to turn on cpumask tests, running at boot or module load time. 2245 2246 For more information on KUnit and unit tests in general, please refer 2247 to the KUnit documentation in Documentation/dev-tools/kunit/. 2248 2249 If unsure, say N. 2250 2251config TEST_LIST_SORT 2252 tristate "Linked list sorting test" if !KUNIT_ALL_TESTS 2253 depends on KUNIT 2254 default KUNIT_ALL_TESTS 2255 help 2256 Enable this to turn on 'list_sort()' function test. This test is 2257 executed only once during system boot (so affects only boot time), 2258 or at module load time. 2259 2260 If unsure, say N. 2261 2262config TEST_MIN_HEAP 2263 tristate "Min heap test" 2264 depends on DEBUG_KERNEL || m 2265 help 2266 Enable this to turn on min heap function tests. This test is 2267 executed only once during system boot (so affects only boot time), 2268 or at module load time. 2269 2270 If unsure, say N. 2271 2272config TEST_SORT 2273 tristate "Array-based sort test" if !KUNIT_ALL_TESTS 2274 depends on KUNIT 2275 default KUNIT_ALL_TESTS 2276 help 2277 This option enables the self-test function of 'sort()' at boot, 2278 or at module load time. 2279 2280 If unsure, say N. 2281 2282config TEST_DIV64 2283 tristate "64bit/32bit division and modulo test" 2284 depends on DEBUG_KERNEL || m 2285 help 2286 Enable this to turn on 'do_div()' function test. This test is 2287 executed only once during system boot (so affects only boot time), 2288 or at module load time. 2289 2290 If unsure, say N. 2291 2292config TEST_MULDIV64 2293 tristate "mul_u64_u64_div_u64() test" 2294 depends on DEBUG_KERNEL || m 2295 help 2296 Enable this to turn on 'mul_u64_u64_div_u64()' function test. 2297 This test is executed only once during system boot (so affects 2298 only boot time), or at module load time. 2299 2300 If unsure, say N. 2301 2302config TEST_IOV_ITER 2303 tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS 2304 depends on KUNIT 2305 depends on MMU 2306 default KUNIT_ALL_TESTS 2307 help 2308 Enable this to turn on testing of the operation of the I/O iterator 2309 (iov_iter). This test is executed only once during system boot (so 2310 affects only boot time), or at module load time. 2311 2312 If unsure, say N. 2313 2314config KPROBES_SANITY_TEST 2315 tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS 2316 depends on DEBUG_KERNEL 2317 depends on KPROBES 2318 depends on KUNIT 2319 select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 2320 default KUNIT_ALL_TESTS 2321 help 2322 This option provides for testing basic kprobes functionality on 2323 boot. Samples of kprobe and kretprobe are inserted and 2324 verified for functionality. 2325 2326 Say N if you are unsure. 2327 2328config FPROBE_SANITY_TEST 2329 bool "Self test for fprobe" 2330 depends on DEBUG_KERNEL 2331 depends on FPROBE 2332 depends on KUNIT=y 2333 help 2334 This option will enable testing the fprobe when the system boot. 2335 A series of tests are made to verify that the fprobe is functioning 2336 properly. 2337 2338 Say N if you are unsure. 2339 2340config BACKTRACE_SELF_TEST 2341 tristate "Self test for the backtrace code" 2342 depends on DEBUG_KERNEL 2343 help 2344 This option provides a kernel module that can be used to test 2345 the kernel stack backtrace code. This option is not useful 2346 for distributions or general kernels, but only for kernel 2347 developers working on architecture code. 2348 2349 Note that if you want to also test saved backtraces, you will 2350 have to enable STACKTRACE as well. 2351 2352 Say N if you are unsure. 2353 2354config TEST_REF_TRACKER 2355 tristate "Self test for reference tracker" 2356 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT 2357 select REF_TRACKER 2358 help 2359 This option provides a kernel module performing tests 2360 using reference tracker infrastructure. 2361 2362 Say N if you are unsure. 2363 2364config RBTREE_TEST 2365 tristate "Red-Black tree test" 2366 depends on DEBUG_KERNEL 2367 help 2368 A benchmark measuring the performance of the rbtree library. 2369 Also includes rbtree invariant checks. 2370 2371config REED_SOLOMON_TEST 2372 tristate "Reed-Solomon library test" 2373 depends on DEBUG_KERNEL || m 2374 select REED_SOLOMON 2375 select REED_SOLOMON_ENC16 2376 select REED_SOLOMON_DEC16 2377 help 2378 This option enables the self-test function of rslib at boot, 2379 or at module load time. 2380 2381 If unsure, say N. 2382 2383config INTERVAL_TREE_TEST 2384 tristate "Interval tree test" 2385 depends on DEBUG_KERNEL 2386 select INTERVAL_TREE 2387 help 2388 A benchmark measuring the performance of the interval tree library 2389 2390config PERCPU_TEST 2391 tristate "Per cpu operations test" 2392 depends on m && DEBUG_KERNEL 2393 help 2394 Enable this option to build test module which validates per-cpu 2395 operations. 2396 2397 If unsure, say N. 2398 2399config ATOMIC64_SELFTEST 2400 tristate "Perform an atomic64_t self-test" 2401 help 2402 Enable this option to test the atomic64_t functions at boot or 2403 at module load time. 2404 2405 If unsure, say N. 2406 2407config ASYNC_RAID6_TEST 2408 tristate "Self test for hardware accelerated raid6 recovery" 2409 depends on ASYNC_RAID6_RECOV 2410 select ASYNC_MEMCPY 2411 help 2412 This is a one-shot self test that permutes through the 2413 recovery of all the possible two disk failure scenarios for a 2414 N-disk array. Recovery is performed with the asynchronous 2415 raid6 recovery routines, and will optionally use an offload 2416 engine if one is available. 2417 2418 If unsure, say N. 2419 2420config TEST_HEXDUMP 2421 tristate "Test functions located in the hexdump module at runtime" 2422 2423config STRING_KUNIT_TEST 2424 tristate "KUnit test string functions at runtime" if !KUNIT_ALL_TESTS 2425 depends on KUNIT 2426 default KUNIT_ALL_TESTS 2427 2428config STRING_HELPERS_KUNIT_TEST 2429 tristate "KUnit test string helpers at runtime" if !KUNIT_ALL_TESTS 2430 depends on KUNIT 2431 default KUNIT_ALL_TESTS 2432 2433config TEST_KSTRTOX 2434 tristate "Test kstrto*() family of functions at runtime" 2435 2436config TEST_PRINTF 2437 tristate "Test printf() family of functions at runtime" 2438 2439config TEST_SCANF 2440 tristate "Test scanf() family of functions at runtime" 2441 2442config TEST_BITMAP 2443 tristate "Test bitmap_*() family of functions at runtime" 2444 help 2445 Enable this option to test the bitmap functions at boot. 2446 2447 If unsure, say N. 2448 2449config TEST_UUID 2450 tristate "Test functions located in the uuid module at runtime" 2451 2452config TEST_XARRAY 2453 tristate "Test the XArray code at runtime" 2454 2455config TEST_MAPLE_TREE 2456 tristate "Test the Maple Tree code at runtime or module load" 2457 help 2458 Enable this option to test the maple tree code functions at boot, or 2459 when the module is loaded. Enable "Debug Maple Trees" will enable 2460 more verbose output on failures. 2461 2462 If unsure, say N. 2463 2464config TEST_RHASHTABLE 2465 tristate "Perform selftest on resizable hash table" 2466 help 2467 Enable this option to test the rhashtable functions at boot. 2468 2469 If unsure, say N. 2470 2471config TEST_IDA 2472 tristate "Perform selftest on IDA functions" 2473 2474config TEST_PARMAN 2475 tristate "Perform selftest on priority array manager" 2476 depends on PARMAN 2477 help 2478 Enable this option to test priority array manager on boot 2479 (or module load). 2480 2481 If unsure, say N. 2482 2483config TEST_IRQ_TIMINGS 2484 bool "IRQ timings selftest" 2485 depends on IRQ_TIMINGS 2486 help 2487 Enable this option to test the irq timings code on boot. 2488 2489 If unsure, say N. 2490 2491config TEST_LKM 2492 tristate "Test module loading with 'hello world' module" 2493 depends on m 2494 help 2495 This builds the "test_module" module that emits "Hello, world" 2496 on printk when loaded. It is designed to be used for basic 2497 evaluation of the module loading subsystem (for example when 2498 validating module verification). It lacks any extra dependencies, 2499 and will not normally be loaded by the system unless explicitly 2500 requested by name. 2501 2502 If unsure, say N. 2503 2504config TEST_BITOPS 2505 tristate "Test module for compilation of bitops operations" 2506 help 2507 This builds the "test_bitops" module that is much like the 2508 TEST_LKM module except that it does a basic exercise of the 2509 set/clear_bit macros and get_count_order/long to make sure there are 2510 no compiler warnings from C=1 sparse checker or -Wextra 2511 compilations. It has no dependencies and doesn't run or load unless 2512 explicitly requested by name. for example: modprobe test_bitops. 2513 2514 If unsure, say N. 2515 2516config TEST_VMALLOC 2517 tristate "Test module for stress/performance analysis of vmalloc allocator" 2518 default n 2519 depends on MMU 2520 depends on m 2521 help 2522 This builds the "test_vmalloc" module that should be used for 2523 stress and performance analysis. So, any new change for vmalloc 2524 subsystem can be evaluated from performance and stability point 2525 of view. 2526 2527 If unsure, say N. 2528 2529config TEST_BPF 2530 tristate "Test BPF filter functionality" 2531 depends on m && NET 2532 help 2533 This builds the "test_bpf" module that runs various test vectors 2534 against the BPF interpreter or BPF JIT compiler depending on the 2535 current setting. This is in particular useful for BPF JIT compiler 2536 development, but also to run regression tests against changes in 2537 the interpreter code. It also enables test stubs for eBPF maps and 2538 verifier used by user space verifier testsuite. 2539 2540 If unsure, say N. 2541 2542config TEST_BLACKHOLE_DEV 2543 tristate "Test blackhole netdev functionality" 2544 depends on m && NET 2545 help 2546 This builds the "test_blackhole_dev" module that validates the 2547 data path through this blackhole netdev. 2548 2549 If unsure, say N. 2550 2551config FIND_BIT_BENCHMARK 2552 tristate "Test find_bit functions" 2553 help 2554 This builds the "test_find_bit" module that measure find_*_bit() 2555 functions performance. 2556 2557 If unsure, say N. 2558 2559config TEST_FIRMWARE 2560 tristate "Test firmware loading via userspace interface" 2561 depends on FW_LOADER 2562 help 2563 This builds the "test_firmware" module that creates a userspace 2564 interface for testing firmware loading. This can be used to 2565 control the triggering of firmware loading without needing an 2566 actual firmware-using device. The contents can be rechecked by 2567 userspace. 2568 2569 If unsure, say N. 2570 2571config TEST_SYSCTL 2572 tristate "sysctl test driver" 2573 depends on PROC_SYSCTL 2574 help 2575 This builds the "test_sysctl" module. This driver enables to test the 2576 proc sysctl interfaces available to drivers safely without affecting 2577 production knobs which might alter system functionality. 2578 2579 If unsure, say N. 2580 2581config BITFIELD_KUNIT 2582 tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS 2583 depends on KUNIT 2584 default KUNIT_ALL_TESTS 2585 help 2586 Enable this option to test the bitfield functions at boot. 2587 2588 KUnit tests run during boot and output the results to the debug log 2589 in TAP format (http://testanything.org/). Only useful for kernel devs 2590 running the KUnit test harness, and not intended for inclusion into a 2591 production build. 2592 2593 For more information on KUnit and unit tests in general please refer 2594 to the KUnit documentation in Documentation/dev-tools/kunit/. 2595 2596 If unsure, say N. 2597 2598config CHECKSUM_KUNIT 2599 tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS 2600 depends on KUNIT 2601 default KUNIT_ALL_TESTS 2602 help 2603 Enable this option to test the checksum functions at boot. 2604 2605 KUnit tests run during boot and output the results to the debug log 2606 in TAP format (http://testanything.org/). Only useful for kernel devs 2607 running the KUnit test harness, and not intended for inclusion into a 2608 production build. 2609 2610 For more information on KUnit and unit tests in general please refer 2611 to the KUnit documentation in Documentation/dev-tools/kunit/. 2612 2613 If unsure, say N. 2614 2615config HASH_KUNIT_TEST 2616 tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS 2617 depends on KUNIT 2618 default KUNIT_ALL_TESTS 2619 help 2620 Enable this option to test the kernel's string (<linux/stringhash.h>), and 2621 integer (<linux/hash.h>) hash functions on boot. 2622 2623 KUnit tests run during boot and output the results to the debug log 2624 in TAP format (https://testanything.org/). Only useful for kernel devs 2625 running the KUnit test harness, and not intended for inclusion into a 2626 production build. 2627 2628 For more information on KUnit and unit tests in general please refer 2629 to the KUnit documentation in Documentation/dev-tools/kunit/. 2630 2631 This is intended to help people writing architecture-specific 2632 optimized versions. If unsure, say N. 2633 2634config RESOURCE_KUNIT_TEST 2635 tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS 2636 depends on KUNIT 2637 default KUNIT_ALL_TESTS 2638 select GET_FREE_REGION 2639 help 2640 This builds the resource API unit test. 2641 Tests the logic of API provided by resource.c and ioport.h. 2642 For more information on KUnit and unit tests in general please refer 2643 to the KUnit documentation in Documentation/dev-tools/kunit/. 2644 2645 If unsure, say N. 2646 2647config SYSCTL_KUNIT_TEST 2648 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS 2649 depends on KUNIT 2650 default KUNIT_ALL_TESTS 2651 help 2652 This builds the proc sysctl unit test, which runs on boot. 2653 Tests the API contract and implementation correctness of sysctl. 2654 For more information on KUnit and unit tests in general please refer 2655 to the KUnit documentation in Documentation/dev-tools/kunit/. 2656 2657 If unsure, say N. 2658 2659config LIST_KUNIT_TEST 2660 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS 2661 depends on KUNIT 2662 default KUNIT_ALL_TESTS 2663 help 2664 This builds the linked list KUnit test suite. 2665 It tests that the API and basic functionality of the list_head type 2666 and associated macros. 2667 2668 KUnit tests run during boot and output the results to the debug log 2669 in TAP format (https://testanything.org/). Only useful for kernel devs 2670 running the KUnit test harness, and not intended for inclusion into a 2671 production build. 2672 2673 For more information on KUnit and unit tests in general please refer 2674 to the KUnit documentation in Documentation/dev-tools/kunit/. 2675 2676 If unsure, say N. 2677 2678config HASHTABLE_KUNIT_TEST 2679 tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS 2680 depends on KUNIT 2681 default KUNIT_ALL_TESTS 2682 help 2683 This builds the hashtable KUnit test suite. 2684 It tests the basic functionality of the API defined in 2685 include/linux/hashtable.h. For more information on KUnit and 2686 unit tests in general please refer to the KUnit documentation 2687 in Documentation/dev-tools/kunit/. 2688 2689 If unsure, say N. 2690 2691config LINEAR_RANGES_TEST 2692 tristate "KUnit test for linear_ranges" 2693 depends on KUNIT 2694 select LINEAR_RANGES 2695 help 2696 This builds the linear_ranges unit test, which runs on boot. 2697 Tests the linear_ranges logic correctness. 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 CMDLINE_KUNIT_TEST 2704 tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS 2705 depends on KUNIT 2706 default KUNIT_ALL_TESTS 2707 help 2708 This builds the cmdline API unit test. 2709 Tests the logic of API provided by cmdline.c. 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 BITS_TEST 2716 tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS 2717 depends on KUNIT 2718 default KUNIT_ALL_TESTS 2719 help 2720 This builds the bits unit test. 2721 Tests the logic of macros defined in bits.h. 2722 For more information on KUnit and unit tests in general please refer 2723 to the KUnit documentation in Documentation/dev-tools/kunit/. 2724 2725 If unsure, say N. 2726 2727config SLUB_KUNIT_TEST 2728 tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS 2729 depends on SLUB_DEBUG && KUNIT 2730 default KUNIT_ALL_TESTS 2731 help 2732 This builds SLUB allocator unit test. 2733 Tests SLUB cache debugging functionality. 2734 For more information on KUnit and unit tests in general please refer 2735 to the KUnit documentation in Documentation/dev-tools/kunit/. 2736 2737 If unsure, say N. 2738 2739config RATIONAL_KUNIT_TEST 2740 tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS 2741 depends on KUNIT && RATIONAL 2742 default KUNIT_ALL_TESTS 2743 help 2744 This builds the rational math unit test. 2745 For more information on KUnit and unit tests in general please refer 2746 to the KUnit documentation in Documentation/dev-tools/kunit/. 2747 2748 If unsure, say N. 2749 2750config MEMCPY_KUNIT_TEST 2751 tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS 2752 depends on KUNIT 2753 default KUNIT_ALL_TESTS 2754 help 2755 Builds unit tests for memcpy(), memmove(), and memset() functions. 2756 For more information on KUnit and unit tests in general please refer 2757 to the KUnit documentation in Documentation/dev-tools/kunit/. 2758 2759 If unsure, say N. 2760 2761config IS_SIGNED_TYPE_KUNIT_TEST 2762 tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS 2763 depends on KUNIT 2764 default KUNIT_ALL_TESTS 2765 help 2766 Builds unit tests for the is_signed_type() macro. 2767 2768 For more information on KUnit and unit tests in general please refer 2769 to the KUnit documentation in Documentation/dev-tools/kunit/. 2770 2771 If unsure, say N. 2772 2773config OVERFLOW_KUNIT_TEST 2774 tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS 2775 depends on KUNIT 2776 default KUNIT_ALL_TESTS 2777 help 2778 Builds unit tests for the check_*_overflow(), size_*(), allocation, and 2779 related functions. 2780 2781 For more information on KUnit and unit tests in general please refer 2782 to the KUnit documentation in Documentation/dev-tools/kunit/. 2783 2784 If unsure, say N. 2785 2786config STACKINIT_KUNIT_TEST 2787 tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS 2788 depends on KUNIT 2789 default KUNIT_ALL_TESTS 2790 help 2791 Test if the kernel is zero-initializing stack variables and 2792 padding. Coverage is controlled by compiler flags, 2793 CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO, 2794 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2795 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2796 2797config FORTIFY_KUNIT_TEST 2798 tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS 2799 depends on KUNIT 2800 default KUNIT_ALL_TESTS 2801 help 2802 Builds unit tests for checking internals of FORTIFY_SOURCE as used 2803 by the str*() and mem*() family of functions. For testing runtime 2804 traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests. 2805 2806config HW_BREAKPOINT_KUNIT_TEST 2807 bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS 2808 depends on HAVE_HW_BREAKPOINT 2809 depends on KUNIT=y 2810 default KUNIT_ALL_TESTS 2811 help 2812 Tests for hw_breakpoint constraints accounting. 2813 2814 If unsure, say N. 2815 2816config SIPHASH_KUNIT_TEST 2817 tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS 2818 depends on KUNIT 2819 default KUNIT_ALL_TESTS 2820 help 2821 Enable this option to test the kernel's siphash (<linux/siphash.h>) hash 2822 functions on boot (or module load). 2823 2824 This is intended to help people writing architecture-specific 2825 optimized versions. If unsure, say N. 2826 2827config USERCOPY_KUNIT_TEST 2828 tristate "KUnit Test for user/kernel boundary protections" 2829 depends on KUNIT 2830 default KUNIT_ALL_TESTS 2831 help 2832 This builds the "usercopy_kunit" module that runs sanity checks 2833 on the copy_to/from_user infrastructure, making sure basic 2834 user/kernel boundary testing is working. 2835 2836config TEST_UDELAY 2837 tristate "udelay test driver" 2838 help 2839 This builds the "udelay_test" module that helps to make sure 2840 that udelay() is working properly. 2841 2842 If unsure, say N. 2843 2844config TEST_STATIC_KEYS 2845 tristate "Test static keys" 2846 depends on m 2847 help 2848 Test the static key interfaces. 2849 2850 If unsure, say N. 2851 2852config TEST_DYNAMIC_DEBUG 2853 tristate "Test DYNAMIC_DEBUG" 2854 depends on DYNAMIC_DEBUG 2855 help 2856 This module registers a tracer callback to count enabled 2857 pr_debugs in a 'do_debugging' function, then alters their 2858 enablements, calls the function, and compares counts. 2859 2860 If unsure, say N. 2861 2862config TEST_KMOD 2863 tristate "kmod stress tester" 2864 depends on m 2865 depends on NETDEVICES && NET_CORE && INET # for TUN 2866 depends on BLOCK 2867 depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS 2868 select TEST_LKM 2869 select XFS_FS 2870 select TUN 2871 select BTRFS_FS 2872 help 2873 Test the kernel's module loading mechanism: kmod. kmod implements 2874 support to load modules using the Linux kernel's usermode helper. 2875 This test provides a series of tests against kmod. 2876 2877 Although technically you can either build test_kmod as a module or 2878 into the kernel we disallow building it into the kernel since 2879 it stress tests request_module() and this will very likely cause 2880 some issues by taking over precious threads available from other 2881 module load requests, ultimately this could be fatal. 2882 2883 To run tests run: 2884 2885 tools/testing/selftests/kmod/kmod.sh --help 2886 2887 If unsure, say N. 2888 2889config TEST_DEBUG_VIRTUAL 2890 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 2891 depends on DEBUG_VIRTUAL 2892 help 2893 Test the kernel's ability to detect incorrect calls to 2894 virt_to_phys() done against the non-linear part of the 2895 kernel's virtual address map. 2896 2897 If unsure, say N. 2898 2899config TEST_MEMCAT_P 2900 tristate "Test memcat_p() helper function" 2901 help 2902 Test the memcat_p() helper for correctly merging two 2903 pointer arrays together. 2904 2905 If unsure, say N. 2906 2907config TEST_OBJAGG 2908 tristate "Perform selftest on object aggreration manager" 2909 default n 2910 depends on OBJAGG 2911 help 2912 Enable this option to test object aggregation manager on boot 2913 (or module load). 2914 2915config TEST_MEMINIT 2916 tristate "Test heap/page initialization" 2917 help 2918 Test if the kernel is zero-initializing heap and page allocations. 2919 This can be useful to test init_on_alloc and init_on_free features. 2920 2921 If unsure, say N. 2922 2923config TEST_HMM 2924 tristate "Test HMM (Heterogeneous Memory Management)" 2925 depends on TRANSPARENT_HUGEPAGE 2926 depends on DEVICE_PRIVATE 2927 select HMM_MIRROR 2928 select MMU_NOTIFIER 2929 help 2930 This is a pseudo device driver solely for testing HMM. 2931 Say M here if you want to build the HMM test module. 2932 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests. 2933 2934 If unsure, say N. 2935 2936config TEST_FREE_PAGES 2937 tristate "Test freeing pages" 2938 help 2939 Test that a memory leak does not occur due to a race between 2940 freeing a block of pages and a speculative page reference. 2941 Loading this module is safe if your kernel has the bug fixed. 2942 If the bug is not fixed, it will leak gigabytes of memory and 2943 probably OOM your system. 2944 2945config TEST_FPU 2946 tristate "Test floating point operations in kernel space" 2947 depends on ARCH_HAS_KERNEL_FPU_SUPPORT && !KCOV_INSTRUMENT_ALL 2948 help 2949 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu 2950 which will trigger a sequence of floating point operations. This is used 2951 for self-testing floating point control register setting in 2952 kernel_fpu_begin(). 2953 2954 If unsure, say N. 2955 2956config TEST_CLOCKSOURCE_WATCHDOG 2957 tristate "Test clocksource watchdog in kernel space" 2958 depends on CLOCKSOURCE_WATCHDOG 2959 help 2960 Enable this option to create a kernel module that will trigger 2961 a test of the clocksource watchdog. This module may be loaded 2962 via modprobe or insmod in which case it will run upon being 2963 loaded, or it may be built in, in which case it will run 2964 shortly after boot. 2965 2966 If unsure, say N. 2967 2968config TEST_OBJPOOL 2969 tristate "Test module for correctness and stress of objpool" 2970 default n 2971 depends on m && DEBUG_KERNEL 2972 help 2973 This builds the "test_objpool" module that should be used for 2974 correctness verification and concurrent testings of objects 2975 allocation and reclamation. 2976 2977 If unsure, say N. 2978 2979endif # RUNTIME_TESTING_MENU 2980 2981config ARCH_USE_MEMTEST 2982 bool 2983 help 2984 An architecture should select this when it uses early_memtest() 2985 during boot process. 2986 2987config MEMTEST 2988 bool "Memtest" 2989 depends on ARCH_USE_MEMTEST 2990 help 2991 This option adds a kernel parameter 'memtest', which allows memtest 2992 to be set and executed. 2993 memtest=0, mean disabled; -- default 2994 memtest=1, mean do 1 test pattern; 2995 ... 2996 memtest=17, mean do 17 test patterns. 2997 If you are unsure how to answer this question, answer N. 2998 2999 3000 3001config HYPERV_TESTING 3002 bool "Microsoft Hyper-V driver testing" 3003 default n 3004 depends on HYPERV && DEBUG_FS 3005 help 3006 Select this option to enable Hyper-V vmbus testing. 3007 3008endmenu # "Kernel Testing and Coverage" 3009 3010menu "Rust hacking" 3011 3012config RUST_DEBUG_ASSERTIONS 3013 bool "Debug assertions" 3014 depends on RUST 3015 help 3016 Enables rustc's `-Cdebug-assertions` codegen option. 3017 3018 This flag lets you turn `cfg(debug_assertions)` conditional 3019 compilation on or off. This can be used to enable extra debugging 3020 code in development but not in production. For example, it controls 3021 the behavior of the standard library's `debug_assert!` macro. 3022 3023 Note that this will apply to all Rust code, including `core`. 3024 3025 If unsure, say N. 3026 3027config RUST_OVERFLOW_CHECKS 3028 bool "Overflow checks" 3029 default y 3030 depends on RUST 3031 help 3032 Enables rustc's `-Coverflow-checks` codegen option. 3033 3034 This flag allows you to control the behavior of runtime integer 3035 overflow. When overflow-checks are enabled, a Rust panic will occur 3036 on overflow. 3037 3038 Note that this will apply to all Rust code, including `core`. 3039 3040 If unsure, say Y. 3041 3042config RUST_BUILD_ASSERT_ALLOW 3043 bool "Allow unoptimized build-time assertions" 3044 depends on RUST 3045 help 3046 Controls how are `build_error!` and `build_assert!` handled during build. 3047 3048 If calls to them exist in the binary, it may indicate a violated invariant 3049 or that the optimizer failed to verify the invariant during compilation. 3050 3051 This should not happen, thus by default the build is aborted. However, 3052 as an escape hatch, you can choose Y here to ignore them during build 3053 and let the check be carried at runtime (with `panic!` being called if 3054 the check fails). 3055 3056 If unsure, say N. 3057 3058config RUST_KERNEL_DOCTESTS 3059 bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS 3060 depends on RUST && KUNIT=y 3061 default KUNIT_ALL_TESTS 3062 help 3063 This builds the documentation tests of the `kernel` crate 3064 as KUnit tests. 3065 3066 For more information on KUnit and unit tests in general, 3067 please refer to the KUnit documentation in Documentation/dev-tools/kunit/. 3068 3069 If unsure, say N. 3070 3071endmenu # "Rust" 3072 3073endmenu # Kernel hacking 3074 3075config INT_POW_TEST 3076 tristate "Integer exponentiation (int_pow) test" if !KUNIT_ALL_TESTS 3077 depends on KUNIT 3078 default KUNIT_ALL_TESTS 3079 help 3080 This option enables the KUnit test suite for the int_pow function, 3081 which performs integer exponentiation. The test suite is designed to 3082 verify that the implementation of int_pow correctly computes the power 3083 of a given base raised to a given exponent. 3084 3085 Enabling this option will include tests that check various scenarios 3086 and edge cases to ensure the accuracy and reliability of the exponentiation 3087 function. 3088 3089 If unsure, say N 3090