1# SPDX-License-Identifier: GPL-2.0-only 2menu "Kernel hacking" 3 4menu "printk and dmesg options" 5 6config PRINTK_TIME 7 bool "Show timing information on printks" 8 depends on PRINTK 9 help 10 Selecting this option causes time stamps of the printk() 11 messages to be added to the output of the syslog() system 12 call and at the console. 13 14 The timestamp is always recorded internally, and exported 15 to /dev/kmsg. This flag just specifies if the timestamp should 16 be included, not that the timestamp is recorded. 17 18 The behavior is also controlled by the kernel command line 19 parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst 20 21config PRINTK_CALLER 22 bool "Show caller information on printks" 23 depends on PRINTK 24 help 25 Selecting this option causes printk() to add a caller "thread id" (if 26 in task context) or a caller "processor id" (if not in task context) 27 to every message. 28 29 This option is intended for environments where multiple threads 30 concurrently call printk() for many times, for it is difficult to 31 interpret without knowing where these lines (or sometimes individual 32 line which was divided into multiple lines due to race) came from. 33 34 Since toggling after boot makes the code racy, currently there is 35 no option to enable/disable at the kernel command line parameter or 36 sysfs interface. 37 38config STACKTRACE_BUILD_ID 39 bool "Show build ID information in stacktraces" 40 depends on PRINTK 41 help 42 Selecting this option adds build ID information for symbols in 43 stacktraces printed with the printk format '%p[SR]b'. 44 45 This option is intended for distros where debuginfo is not easily 46 accessible but can be downloaded given the build ID of the vmlinux or 47 kernel module where the function is located. 48 49config CONSOLE_LOGLEVEL_DEFAULT 50 int "Default console loglevel (1-15)" 51 range 1 15 52 default "7" 53 help 54 Default loglevel to determine what will be printed on the console. 55 56 Setting a default here is equivalent to passing in loglevel=<x> in 57 the kernel bootargs. loglevel=<x> continues to override whatever 58 value is specified here as well. 59 60 Note: This does not affect the log level of un-prefixed printk() 61 usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT 62 option. 63 64config CONSOLE_LOGLEVEL_QUIET 65 int "quiet console loglevel (1-15)" 66 range 1 15 67 default "4" 68 help 69 loglevel to use when "quiet" is passed on the kernel commandline. 70 71 When "quiet" is passed on the kernel commandline this loglevel 72 will be used as the loglevel. IOW passing "quiet" will be the 73 equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>" 74 75config MESSAGE_LOGLEVEL_DEFAULT 76 int "Default message log level (1-7)" 77 range 1 7 78 default "4" 79 help 80 Default log level for printk statements with no specified priority. 81 82 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks 83 that are auditing their logs closely may want to set it to a lower 84 priority. 85 86 Note: This does not affect what message level gets printed on the console 87 by default. To change that, use loglevel=<x> in the kernel bootargs, 88 or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value. 89 90config BOOT_PRINTK_DELAY 91 bool "Delay each boot printk message by N milliseconds" 92 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY 93 help 94 This build option allows you to read kernel boot messages 95 by inserting a short delay after each one. The delay is 96 specified in milliseconds on the kernel command line, 97 using "boot_delay=N". 98 99 It is likely that you would also need to use "lpj=M" to preset 100 the "loops per jiffie" value. 101 See a previous boot log for the "lpj" value to use for your 102 system, and then set "lpj=M" before setting "boot_delay=N". 103 NOTE: Using this option may adversely affect SMP systems. 104 I.e., processors other than the first one may not boot up. 105 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect 106 what it believes to be lockup conditions. 107 108config DYNAMIC_DEBUG 109 bool "Enable dynamic printk() support" 110 default n 111 depends on PRINTK 112 depends on (DEBUG_FS || PROC_FS) 113 select DYNAMIC_DEBUG_CORE 114 help 115 116 Compiles debug level messages into the kernel, which would not 117 otherwise be available at runtime. These messages can then be 118 enabled/disabled based on various levels of scope - per source file, 119 function, module, format string, and line number. This mechanism 120 implicitly compiles in all pr_debug() and dev_dbg() calls, which 121 enlarges the kernel text size by about 2%. 122 123 If a source file is compiled with DEBUG flag set, any 124 pr_debug() calls in it are enabled by default, but can be 125 disabled at runtime as below. Note that DEBUG flag is 126 turned on by many CONFIG_*DEBUG* options. 127 128 Usage: 129 130 Dynamic debugging is controlled via the 'dynamic_debug/control' file, 131 which is contained in the 'debugfs' filesystem or procfs. 132 Thus, the debugfs or procfs filesystem must first be mounted before 133 making use of this feature. 134 We refer the control file as: <debugfs>/dynamic_debug/control. This 135 file contains a list of the debug statements that can be enabled. The 136 format for each line of the file is: 137 138 filename:lineno [module]function flags format 139 140 filename : source file of the debug statement 141 lineno : line number of the debug statement 142 module : module that contains the debug statement 143 function : function that contains the debug statement 144 flags : '=p' means the line is turned 'on' for printing 145 format : the format used for the debug statement 146 147 From a live system: 148 149 nullarbor:~ # cat <debugfs>/dynamic_debug/control 150 # filename:lineno [module]function flags format 151 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012" 152 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012" 153 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012" 154 155 Example usage: 156 157 // enable the message at line 1603 of file svcsock.c 158 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' > 159 <debugfs>/dynamic_debug/control 160 161 // enable all the messages in file svcsock.c 162 nullarbor:~ # echo -n 'file svcsock.c +p' > 163 <debugfs>/dynamic_debug/control 164 165 // enable all the messages in the NFS server module 166 nullarbor:~ # echo -n 'module nfsd +p' > 167 <debugfs>/dynamic_debug/control 168 169 // enable all 12 messages in the function svc_process() 170 nullarbor:~ # echo -n 'func svc_process +p' > 171 <debugfs>/dynamic_debug/control 172 173 // disable all 12 messages in the function svc_process() 174 nullarbor:~ # echo -n 'func svc_process -p' > 175 <debugfs>/dynamic_debug/control 176 177 See Documentation/admin-guide/dynamic-debug-howto.rst for additional 178 information. 179 180config DYNAMIC_DEBUG_CORE 181 bool "Enable core function of dynamic debug support" 182 depends on PRINTK 183 depends on (DEBUG_FS || PROC_FS) 184 help 185 Enable core functional support of dynamic debug. It is useful 186 when you want to tie dynamic debug to your kernel modules with 187 DYNAMIC_DEBUG_MODULE defined for each of them, especially for 188 the case of embedded system where the kernel image size is 189 sensitive for people. 190 191config SYMBOLIC_ERRNAME 192 bool "Support symbolic error names in printf" 193 default y if PRINTK 194 help 195 If you say Y here, the kernel's printf implementation will 196 be able to print symbolic error names such as ENOSPC instead 197 of the number 28. It makes the kernel image slightly larger 198 (about 3KB), but can make the kernel logs easier to read. 199 200config DEBUG_BUGVERBOSE 201 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT 202 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE) 203 default y 204 help 205 Say Y here to make BUG() panics output the file name and line number 206 of the BUG call as well as the EIP and oops trace. This aids 207 debugging but costs about 70-100K of memory. 208 209endmenu # "printk and dmesg options" 210 211config DEBUG_KERNEL 212 bool "Kernel debugging" 213 help 214 Say Y here if you are developing drivers or trying to debug and 215 identify kernel problems. 216 217config DEBUG_MISC 218 bool "Miscellaneous debug code" 219 default DEBUG_KERNEL 220 depends on DEBUG_KERNEL 221 help 222 Say Y here if you need to enable miscellaneous debug code that should 223 be under a more specific debug option but isn't. 224 225menu "Compile-time checks and compiler options" 226 227config DEBUG_INFO 228 bool 229 help 230 A kernel debug info option other than "None" has been selected 231 in the "Debug information" choice below, indicating that debug 232 information will be generated for build targets. 233 234# Clang generates .uleb128 with label differences for DWARF v5, a feature that 235# older binutils ports do not support when utilizing RISC-V style linker 236# relaxation: https://sourceware.org/bugzilla/show_bug.cgi?id=27215 237config AS_HAS_NON_CONST_ULEB128 238 def_bool $(as-instr,.uleb128 .Lexpr_end4 - .Lexpr_start3\n.Lexpr_start3:\n.Lexpr_end4:) 239 240choice 241 prompt "Debug information" 242 depends on DEBUG_KERNEL 243 help 244 Selecting something other than "None" results in a kernel image 245 that will include debugging info resulting in a larger kernel image. 246 This adds debug symbols to the kernel and modules (gcc -g), and 247 is needed if you intend to use kernel crashdump or binary object 248 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 249 250 Choose which version of DWARF debug info to emit. If unsure, 251 select "Toolchain default". 252 253config DEBUG_INFO_NONE 254 bool "Disable debug information" 255 help 256 Do not build the kernel with debugging information, which will 257 result in a faster and smaller build. 258 259config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT 260 bool "Rely on the toolchain's implicit default DWARF version" 261 select DEBUG_INFO 262 depends on !CC_IS_CLANG || AS_IS_LLVM || CLANG_VERSION < 140000 || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128) 263 help 264 The implicit default version of DWARF debug info produced by a 265 toolchain changes over time. 266 267 This can break consumers of the debug info that haven't upgraded to 268 support newer revisions, and prevent testing newer versions, but 269 those should be less common scenarios. 270 271config DEBUG_INFO_DWARF4 272 bool "Generate DWARF Version 4 debuginfo" 273 select DEBUG_INFO 274 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502) 275 help 276 Generate DWARF v4 debug info. This requires gcc 4.5+, binutils 2.35.2 277 if using clang without clang's integrated assembler, and gdb 7.0+. 278 279 If you have consumers of DWARF debug info that are not ready for 280 newer revisions of DWARF, you may wish to choose this or have your 281 config select this. 282 283config DEBUG_INFO_DWARF5 284 bool "Generate DWARF Version 5 debuginfo" 285 select DEBUG_INFO 286 depends on !ARCH_HAS_BROKEN_DWARF5 287 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128) 288 help 289 Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc 290 5.0+ accepts the -gdwarf-5 flag but only had partial support for some 291 draft features until 7.0), and gdb 8.0+. 292 293 Changes to the structure of debug info in Version 5 allow for around 294 15-18% savings in resulting image and debug info section sizes as 295 compared to DWARF Version 4. DWARF Version 5 standardizes previous 296 extensions such as accelerators for symbol indexing and the format 297 for fission (.dwo/.dwp) files. Users may not want to select this 298 config if they rely on tooling that has not yet been updated to 299 support DWARF Version 5. 300 301endchoice # "Debug information" 302 303if DEBUG_INFO 304 305config DEBUG_INFO_REDUCED 306 bool "Reduce debugging information" 307 help 308 If you say Y here gcc is instructed to generate less debugging 309 information for structure types. This means that tools that 310 need full debugging information (like kgdb or systemtap) won't 311 be happy. But if you merely need debugging information to 312 resolve line numbers there is no loss. Advantage is that 313 build directory object sizes shrink dramatically over a full 314 DEBUG_INFO build and compile times are reduced too. 315 Only works with newer gcc versions. 316 317choice 318 prompt "Compressed Debug information" 319 help 320 Compress the resulting debug info. Results in smaller debug info sections, 321 but requires that consumers are able to decompress the results. 322 323 If unsure, choose DEBUG_INFO_COMPRESSED_NONE. 324 325config DEBUG_INFO_COMPRESSED_NONE 326 bool "Don't compress debug information" 327 help 328 Don't compress debug info sections. 329 330config DEBUG_INFO_COMPRESSED_ZLIB 331 bool "Compress debugging information with zlib" 332 depends on $(cc-option,-gz=zlib) 333 depends on $(ld-option,--compress-debug-sections=zlib) 334 help 335 Compress the debug information using zlib. Requires GCC 5.0+ or Clang 336 5.0+, binutils 2.26+, and zlib. 337 338 Users of dpkg-deb via scripts/package/builddeb may find an increase in 339 size of their debug .deb packages with this config set, due to the 340 debug info being compressed with zlib, then the object files being 341 recompressed with a different compression scheme. But this is still 342 preferable to setting $KDEB_COMPRESS to "none" which would be even 343 larger. 344 345config DEBUG_INFO_COMPRESSED_ZSTD 346 bool "Compress debugging information with zstd" 347 depends on $(cc-option,-gz=zstd) 348 depends on $(ld-option,--compress-debug-sections=zstd) 349 help 350 Compress the debug information using zstd. This may provide better 351 compression than zlib, for about the same time costs, but requires newer 352 toolchain support. Requires GCC 13.0+ or Clang 16.0+, binutils 2.40+, and 353 zstd. 354 355endchoice # "Compressed Debug information" 356 357config DEBUG_INFO_SPLIT 358 bool "Produce split debuginfo in .dwo files" 359 depends on $(cc-option,-gsplit-dwarf) 360 # RISC-V linker relaxation + -gsplit-dwarf has issues with LLVM and GCC 361 # prior to 12.x: 362 # https://github.com/llvm/llvm-project/issues/56642 363 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99090 364 depends on !RISCV || GCC_VERSION >= 120000 365 help 366 Generate debug info into separate .dwo files. This significantly 367 reduces the build directory size for builds with DEBUG_INFO, 368 because it stores the information only once on disk in .dwo 369 files instead of multiple times in object files and executables. 370 In addition the debug information is also compressed. 371 372 Requires recent gcc (4.7+) and recent gdb/binutils. 373 Any tool that packages or reads debug information would need 374 to know about the .dwo files and include them. 375 Incompatible with older versions of ccache. 376 377config DEBUG_INFO_BTF 378 bool "Generate BTF 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. 1047 1048config LOCKUP_DETECTOR 1049 bool 1050 1051config SOFTLOCKUP_DETECTOR 1052 bool "Detect Soft Lockups" 1053 depends on DEBUG_KERNEL && !S390 1054 select LOCKUP_DETECTOR 1055 help 1056 Say Y here to enable the kernel to act as a watchdog to detect 1057 soft lockups. 1058 1059 Softlockups are bugs that cause the kernel to loop in kernel 1060 mode for more than 20 seconds, without giving other tasks a 1061 chance to run. The current stack trace is displayed upon 1062 detection and the system will stay locked up. 1063 1064config SOFTLOCKUP_DETECTOR_INTR_STORM 1065 bool "Detect Interrupt Storm in Soft Lockups" 1066 depends on SOFTLOCKUP_DETECTOR && IRQ_TIME_ACCOUNTING 1067 select GENERIC_IRQ_STAT_SNAPSHOT 1068 default y if NR_CPUS <= 128 1069 help 1070 Say Y here to enable the kernel to detect interrupt storm 1071 during "soft lockups". 1072 1073 "soft lockups" can be caused by a variety of reasons. If one is 1074 caused by an interrupt storm, then the storming interrupts will not 1075 be on the callstack. To detect this case, it is necessary to report 1076 the CPU stats and the interrupt counts during the "soft lockups". 1077 1078config BOOTPARAM_SOFTLOCKUP_PANIC 1079 bool "Panic (Reboot) On Soft Lockups" 1080 depends on SOFTLOCKUP_DETECTOR 1081 help 1082 Say Y here to enable the kernel to panic on "soft lockups", 1083 which are bugs that cause the kernel to loop in kernel 1084 mode for more than 20 seconds (configurable using the watchdog_thresh 1085 sysctl), without giving other tasks a chance to run. 1086 1087 The panic can be used in combination with panic_timeout, 1088 to cause the system to reboot automatically after a 1089 lockup has been detected. This feature is useful for 1090 high-availability systems that have uptime guarantees and 1091 where a lockup must be resolved ASAP. 1092 1093 Say N if unsure. 1094 1095config HAVE_HARDLOCKUP_DETECTOR_BUDDY 1096 bool 1097 depends on SMP 1098 default y 1099 1100# 1101# Global switch whether to build a hardlockup detector at all. It is available 1102# only when the architecture supports at least one implementation. There are 1103# two exceptions. The hardlockup detector is never enabled on: 1104# 1105# s390: it reported many false positives there 1106# 1107# sparc64: has a custom implementation which is not using the common 1108# hardlockup command line options and sysctl interface. 1109# 1110config HARDLOCKUP_DETECTOR 1111 bool "Detect Hard Lockups" 1112 depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64 1113 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH 1114 imply HARDLOCKUP_DETECTOR_PERF 1115 imply HARDLOCKUP_DETECTOR_BUDDY 1116 imply HARDLOCKUP_DETECTOR_ARCH 1117 select LOCKUP_DETECTOR 1118 1119 help 1120 Say Y here to enable the kernel to act as a watchdog to detect 1121 hard lockups. 1122 1123 Hardlockups are bugs that cause the CPU to loop in kernel mode 1124 for more than 10 seconds, without letting other interrupts have a 1125 chance to run. The current stack trace is displayed upon detection 1126 and the system will stay locked up. 1127 1128# 1129# Note that arch-specific variants are always preferred. 1130# 1131config HARDLOCKUP_DETECTOR_PREFER_BUDDY 1132 bool "Prefer the buddy CPU hardlockup detector" 1133 depends on HARDLOCKUP_DETECTOR 1134 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY 1135 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1136 help 1137 Say Y here to prefer the buddy hardlockup detector over the perf one. 1138 1139 With the buddy detector, each CPU uses its softlockup hrtimer 1140 to check that the next CPU is processing hrtimer interrupts by 1141 verifying that a counter is increasing. 1142 1143 This hardlockup detector is useful on systems that don't have 1144 an arch-specific hardlockup detector or if resources needed 1145 for the hardlockup detector are better used for other things. 1146 1147config HARDLOCKUP_DETECTOR_PERF 1148 bool 1149 depends on HARDLOCKUP_DETECTOR 1150 depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY 1151 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1152 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1153 1154config HARDLOCKUP_DETECTOR_BUDDY 1155 bool 1156 depends on HARDLOCKUP_DETECTOR 1157 depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY 1158 depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY 1159 depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH 1160 select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1161 1162config HARDLOCKUP_DETECTOR_ARCH 1163 bool 1164 depends on HARDLOCKUP_DETECTOR 1165 depends on HAVE_HARDLOCKUP_DETECTOR_ARCH 1166 help 1167 The arch-specific implementation of the hardlockup detector will 1168 be used. 1169 1170# 1171# Both the "perf" and "buddy" hardlockup detectors count hrtimer 1172# interrupts. This config enables functions managing this common code. 1173# 1174config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER 1175 bool 1176 select SOFTLOCKUP_DETECTOR 1177 1178# 1179# Enables a timestamp based low pass filter to compensate for perf based 1180# hard lockup detection which runs too fast due to turbo modes. 1181# 1182config HARDLOCKUP_CHECK_TIMESTAMP 1183 bool 1184 1185config BOOTPARAM_HARDLOCKUP_PANIC 1186 bool "Panic (Reboot) On Hard Lockups" 1187 depends on HARDLOCKUP_DETECTOR 1188 help 1189 Say Y here to enable the kernel to panic on "hard lockups", 1190 which are bugs that cause the kernel to loop in kernel 1191 mode with interrupts disabled for more than 10 seconds (configurable 1192 using the watchdog_thresh sysctl). 1193 1194 Say N if unsure. 1195 1196config DETECT_HUNG_TASK 1197 bool "Detect Hung Tasks" 1198 depends on DEBUG_KERNEL 1199 default SOFTLOCKUP_DETECTOR 1200 help 1201 Say Y here to enable the kernel to detect "hung tasks", 1202 which are bugs that cause the task to be stuck in 1203 uninterruptible "D" state indefinitely. 1204 1205 When a hung task is detected, the kernel will print the 1206 current stack trace (which you should report), but the 1207 task will stay in uninterruptible state. If lockdep is 1208 enabled then all held locks will also be reported. This 1209 feature has negligible overhead. 1210 1211config DEFAULT_HUNG_TASK_TIMEOUT 1212 int "Default timeout for hung task detection (in seconds)" 1213 depends on DETECT_HUNG_TASK 1214 default 120 1215 help 1216 This option controls the default timeout (in seconds) used 1217 to determine when a task has become non-responsive and should 1218 be considered hung. 1219 1220 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 1221 sysctl or by writing a value to 1222 /proc/sys/kernel/hung_task_timeout_secs. 1223 1224 A timeout of 0 disables the check. The default is two minutes. 1225 Keeping the default should be fine in most cases. 1226 1227config BOOTPARAM_HUNG_TASK_PANIC 1228 bool "Panic (Reboot) On Hung Tasks" 1229 depends on DETECT_HUNG_TASK 1230 help 1231 Say Y here to enable the kernel to panic on "hung tasks", 1232 which are bugs that cause the kernel to leave a task stuck 1233 in uninterruptible "D" state. 1234 1235 The panic can be used in combination with panic_timeout, 1236 to cause the system to reboot automatically after a 1237 hung task has been detected. This feature is useful for 1238 high-availability systems that have uptime guarantees and 1239 where a hung tasks must be resolved ASAP. 1240 1241 Say N if unsure. 1242 1243config WQ_WATCHDOG 1244 bool "Detect Workqueue Stalls" 1245 depends on DEBUG_KERNEL 1246 help 1247 Say Y here to enable stall detection on workqueues. If a 1248 worker pool doesn't make forward progress on a pending work 1249 item for over a given amount of time, 30s by default, a 1250 warning message is printed along with dump of workqueue 1251 state. This can be configured through kernel parameter 1252 "workqueue.watchdog_thresh" and its sysfs counterpart. 1253 1254config WQ_CPU_INTENSIVE_REPORT 1255 bool "Report per-cpu work items which hog CPU for too long" 1256 depends on DEBUG_KERNEL 1257 help 1258 Say Y here to enable reporting of concurrency-managed per-cpu work 1259 items that hog CPUs for longer than 1260 workqueue.cpu_intensive_thresh_us. Workqueue automatically 1261 detects and excludes them from concurrency management to prevent 1262 them from stalling other per-cpu work items. Occassional 1263 triggering may not necessarily indicate a problem. Repeated 1264 triggering likely indicates that the work item should be switched 1265 to use an unbound workqueue. 1266 1267config TEST_LOCKUP 1268 tristate "Test module to generate lockups" 1269 depends on m 1270 help 1271 This builds the "test_lockup" module that helps to make sure 1272 that watchdogs and lockup detectors are working properly. 1273 1274 Depending on module parameters it could emulate soft or hard 1275 lockup, "hung task", or locking arbitrary lock for a long time. 1276 Also it could generate series of lockups with cooling-down periods. 1277 1278 If unsure, say N. 1279 1280endmenu # "Debug lockups and hangs" 1281 1282menu "Scheduler Debugging" 1283 1284config SCHED_DEBUG 1285 bool "Collect scheduler debugging info" 1286 depends on DEBUG_KERNEL && DEBUG_FS 1287 default y 1288 help 1289 If you say Y here, the /sys/kernel/debug/sched file will be provided 1290 that can help debug the scheduler. The runtime overhead of this 1291 option is minimal. 1292 1293config SCHED_INFO 1294 bool 1295 default n 1296 1297config SCHEDSTATS 1298 bool "Collect scheduler statistics" 1299 depends on PROC_FS 1300 select SCHED_INFO 1301 help 1302 If you say Y here, additional code will be inserted into the 1303 scheduler and related routines to collect statistics about 1304 scheduler behavior and provide them in /proc/schedstat. These 1305 stats may be useful for both tuning and debugging the scheduler 1306 If you aren't debugging the scheduler or trying to tune a specific 1307 application, you can say N to avoid the very slight overhead 1308 this adds. 1309 1310endmenu 1311 1312config DEBUG_TIMEKEEPING 1313 bool "Enable extra timekeeping sanity checking" 1314 help 1315 This option will enable additional timekeeping sanity checks 1316 which may be helpful when diagnosing issues where timekeeping 1317 problems are suspected. 1318 1319 This may include checks in the timekeeping hotpaths, so this 1320 option may have a (very small) performance impact to some 1321 workloads. 1322 1323 If unsure, say N. 1324 1325config DEBUG_PREEMPT 1326 bool "Debug preemptible kernel" 1327 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1328 help 1329 If you say Y here then the kernel will use a debug variant of the 1330 commonly used smp_processor_id() function and will print warnings 1331 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1332 will detect preemption count underflows. 1333 1334 This option has potential to introduce high runtime overhead, 1335 depending on workload as it triggers debugging routines for each 1336 this_cpu operation. It should only be used for debugging purposes. 1337 1338menu "Lock Debugging (spinlocks, mutexes, etc...)" 1339 1340config LOCK_DEBUGGING_SUPPORT 1341 bool 1342 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1343 default y 1344 1345config PROVE_LOCKING 1346 bool "Lock debugging: prove locking correctness" 1347 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1348 select LOCKDEP 1349 select DEBUG_SPINLOCK 1350 select DEBUG_MUTEXES if !PREEMPT_RT 1351 select DEBUG_RT_MUTEXES if RT_MUTEXES 1352 select DEBUG_RWSEMS if !PREEMPT_RT 1353 select DEBUG_WW_MUTEX_SLOWPATH 1354 select DEBUG_LOCK_ALLOC 1355 select PREEMPT_COUNT if !ARCH_NO_PREEMPT 1356 select TRACE_IRQFLAGS 1357 default n 1358 help 1359 This feature enables the kernel to prove that all locking 1360 that occurs in the kernel runtime is mathematically 1361 correct: that under no circumstance could an arbitrary (and 1362 not yet triggered) combination of observed locking 1363 sequences (on an arbitrary number of CPUs, running an 1364 arbitrary number of tasks and interrupt contexts) cause a 1365 deadlock. 1366 1367 In short, this feature enables the kernel to report locking 1368 related deadlocks before they actually occur. 1369 1370 The proof does not depend on how hard and complex a 1371 deadlock scenario would be to trigger: how many 1372 participant CPUs, tasks and irq-contexts would be needed 1373 for it to trigger. The proof also does not depend on 1374 timing: if a race and a resulting deadlock is possible 1375 theoretically (no matter how unlikely the race scenario 1376 is), it will be proven so and will immediately be 1377 reported by the kernel (once the event is observed that 1378 makes the deadlock theoretically possible). 1379 1380 If a deadlock is impossible (i.e. the locking rules, as 1381 observed by the kernel, are mathematically correct), the 1382 kernel reports nothing. 1383 1384 NOTE: this feature can also be enabled for rwlocks, mutexes 1385 and rwsems - in which case all dependencies between these 1386 different locking variants are observed and mapped too, and 1387 the proof of observed correctness is also maintained for an 1388 arbitrary combination of these separate locking variants. 1389 1390 For more details, see Documentation/locking/lockdep-design.rst. 1391 1392config PROVE_RAW_LOCK_NESTING 1393 bool "Enable raw_spinlock - spinlock nesting checks" 1394 depends on PROVE_LOCKING 1395 default n 1396 help 1397 Enable the raw_spinlock vs. spinlock nesting checks which ensure 1398 that the lock nesting rules for PREEMPT_RT enabled kernels are 1399 not violated. 1400 1401 NOTE: There are known nesting problems. So if you enable this 1402 option expect lockdep splats until these problems have been fully 1403 addressed which is work in progress. This config switch allows to 1404 identify and analyze these problems. It will be removed and the 1405 check permanently enabled once the main issues have been fixed. 1406 1407 If unsure, select N. 1408 1409config LOCK_STAT 1410 bool "Lock usage statistics" 1411 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1412 select LOCKDEP 1413 select DEBUG_SPINLOCK 1414 select DEBUG_MUTEXES if !PREEMPT_RT 1415 select DEBUG_RT_MUTEXES if RT_MUTEXES 1416 select DEBUG_LOCK_ALLOC 1417 default n 1418 help 1419 This feature enables tracking lock contention points 1420 1421 For more details, see Documentation/locking/lockstat.rst 1422 1423 This also enables lock events required by "perf lock", 1424 subcommand of perf. 1425 If you want to use "perf lock", you also need to turn on 1426 CONFIG_EVENT_TRACING. 1427 1428 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1429 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1430 1431config DEBUG_RT_MUTEXES 1432 bool "RT Mutex debugging, deadlock detection" 1433 depends on DEBUG_KERNEL && RT_MUTEXES 1434 help 1435 This allows rt mutex semantics violations and rt mutex related 1436 deadlocks (lockups) to be detected and reported automatically. 1437 1438config DEBUG_SPINLOCK 1439 bool "Spinlock and rw-lock debugging: basic checks" 1440 depends on DEBUG_KERNEL 1441 select UNINLINE_SPIN_UNLOCK 1442 help 1443 Say Y here and build SMP to catch missing spinlock initialization 1444 and certain other kinds of spinlock errors commonly made. This is 1445 best used in conjunction with the NMI watchdog so that spinlock 1446 deadlocks are also debuggable. 1447 1448config DEBUG_MUTEXES 1449 bool "Mutex debugging: basic checks" 1450 depends on DEBUG_KERNEL && !PREEMPT_RT 1451 help 1452 This feature allows mutex semantics violations to be detected and 1453 reported. 1454 1455config DEBUG_WW_MUTEX_SLOWPATH 1456 bool "Wait/wound mutex debugging: Slowpath testing" 1457 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1458 select DEBUG_LOCK_ALLOC 1459 select DEBUG_SPINLOCK 1460 select DEBUG_MUTEXES if !PREEMPT_RT 1461 select DEBUG_RT_MUTEXES if PREEMPT_RT 1462 help 1463 This feature enables slowpath testing for w/w mutex users by 1464 injecting additional -EDEADLK wound/backoff cases. Together with 1465 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1466 will test all possible w/w mutex interface abuse with the 1467 exception of simply not acquiring all the required locks. 1468 Note that this feature can introduce significant overhead, so 1469 it really should not be enabled in a production or distro kernel, 1470 even a debug kernel. If you are a driver writer, enable it. If 1471 you are a distro, do not. 1472 1473config DEBUG_RWSEMS 1474 bool "RW Semaphore debugging: basic checks" 1475 depends on DEBUG_KERNEL && !PREEMPT_RT 1476 help 1477 This debugging feature allows mismatched rw semaphore locks 1478 and unlocks to be detected and reported. 1479 1480config DEBUG_LOCK_ALLOC 1481 bool "Lock debugging: detect incorrect freeing of live locks" 1482 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1483 select DEBUG_SPINLOCK 1484 select DEBUG_MUTEXES if !PREEMPT_RT 1485 select DEBUG_RT_MUTEXES if RT_MUTEXES 1486 select LOCKDEP 1487 help 1488 This feature will check whether any held lock (spinlock, rwlock, 1489 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1490 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1491 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1492 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1493 held during task exit. 1494 1495config LOCKDEP 1496 bool 1497 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1498 select STACKTRACE 1499 select KALLSYMS 1500 select KALLSYMS_ALL 1501 1502config LOCKDEP_SMALL 1503 bool 1504 1505config LOCKDEP_BITS 1506 int "Bitsize for MAX_LOCKDEP_ENTRIES" 1507 depends on LOCKDEP && !LOCKDEP_SMALL 1508 range 10 30 1509 default 15 1510 help 1511 Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message. 1512 1513config LOCKDEP_CHAINS_BITS 1514 int "Bitsize for MAX_LOCKDEP_CHAINS" 1515 depends on LOCKDEP && !LOCKDEP_SMALL 1516 range 10 30 1517 default 16 1518 help 1519 Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message. 1520 1521config LOCKDEP_STACK_TRACE_BITS 1522 int "Bitsize for MAX_STACK_TRACE_ENTRIES" 1523 depends on LOCKDEP && !LOCKDEP_SMALL 1524 range 10 30 1525 default 19 1526 help 1527 Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message. 1528 1529config LOCKDEP_STACK_TRACE_HASH_BITS 1530 int "Bitsize for STACK_TRACE_HASH_SIZE" 1531 depends on LOCKDEP && !LOCKDEP_SMALL 1532 range 10 30 1533 default 14 1534 help 1535 Try increasing this value if you need large STACK_TRACE_HASH_SIZE. 1536 1537config LOCKDEP_CIRCULAR_QUEUE_BITS 1538 int "Bitsize for elements in circular_queue struct" 1539 depends on LOCKDEP 1540 range 10 30 1541 default 12 1542 help 1543 Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure. 1544 1545config DEBUG_LOCKDEP 1546 bool "Lock dependency engine debugging" 1547 depends on DEBUG_KERNEL && LOCKDEP 1548 select DEBUG_IRQFLAGS 1549 help 1550 If you say Y here, the lock dependency engine will do 1551 additional runtime checks to debug itself, at the price 1552 of more runtime overhead. 1553 1554config DEBUG_ATOMIC_SLEEP 1555 bool "Sleep inside atomic section checking" 1556 select PREEMPT_COUNT 1557 depends on DEBUG_KERNEL 1558 depends on !ARCH_NO_PREEMPT 1559 help 1560 If you say Y here, various routines which may sleep will become very 1561 noisy if they are called inside atomic sections: when a spinlock is 1562 held, inside an rcu read side critical section, inside preempt disabled 1563 sections, inside an interrupt, etc... 1564 1565config DEBUG_LOCKING_API_SELFTESTS 1566 bool "Locking API boot-time self-tests" 1567 depends on DEBUG_KERNEL 1568 help 1569 Say Y here if you want the kernel to run a short self-test during 1570 bootup. The self-test checks whether common types of locking bugs 1571 are detected by debugging mechanisms or not. (if you disable 1572 lock debugging then those bugs won't be detected of course.) 1573 The following locking APIs are covered: spinlocks, rwlocks, 1574 mutexes and rwsems. 1575 1576config LOCK_TORTURE_TEST 1577 tristate "torture tests for locking" 1578 depends on DEBUG_KERNEL 1579 select TORTURE_TEST 1580 help 1581 This option provides a kernel module that runs torture tests 1582 on kernel locking primitives. The kernel module may be built 1583 after the fact on the running kernel to be tested, if desired. 1584 1585 Say Y here if you want kernel locking-primitive torture tests 1586 to be built into the kernel. 1587 Say M if you want these torture tests to build as a module. 1588 Say N if you are unsure. 1589 1590config WW_MUTEX_SELFTEST 1591 tristate "Wait/wound mutex selftests" 1592 help 1593 This option provides a kernel module that runs tests on the 1594 on the struct ww_mutex locking API. 1595 1596 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1597 with this test harness. 1598 1599 Say M if you want these self tests to build as a module. 1600 Say N if you are unsure. 1601 1602config SCF_TORTURE_TEST 1603 tristate "torture tests for smp_call_function*()" 1604 depends on DEBUG_KERNEL 1605 select TORTURE_TEST 1606 help 1607 This option provides a kernel module that runs torture tests 1608 on the smp_call_function() family of primitives. The kernel 1609 module may be built after the fact on the running kernel to 1610 be tested, if desired. 1611 1612config CSD_LOCK_WAIT_DEBUG 1613 bool "Debugging for csd_lock_wait(), called from smp_call_function*()" 1614 depends on DEBUG_KERNEL 1615 depends on 64BIT 1616 default n 1617 help 1618 This option enables debug prints when CPUs are slow to respond 1619 to the smp_call_function*() IPI wrappers. These debug prints 1620 include the IPI handler function currently executing (if any) 1621 and relevant stack traces. 1622 1623config CSD_LOCK_WAIT_DEBUG_DEFAULT 1624 bool "Default csd_lock_wait() debugging on at boot time" 1625 depends on CSD_LOCK_WAIT_DEBUG 1626 depends on 64BIT 1627 default n 1628 help 1629 This option causes the csdlock_debug= kernel boot parameter to 1630 default to 1 (basic debugging) instead of 0 (no debugging). 1631 1632endmenu # lock debugging 1633 1634config TRACE_IRQFLAGS 1635 depends on TRACE_IRQFLAGS_SUPPORT 1636 bool 1637 help 1638 Enables hooks to interrupt enabling and disabling for 1639 either tracing or lock debugging. 1640 1641config TRACE_IRQFLAGS_NMI 1642 def_bool y 1643 depends on TRACE_IRQFLAGS 1644 depends on TRACE_IRQFLAGS_NMI_SUPPORT 1645 1646config NMI_CHECK_CPU 1647 bool "Debugging for CPUs failing to respond to backtrace requests" 1648 depends on DEBUG_KERNEL 1649 depends on X86 1650 default n 1651 help 1652 Enables debug prints when a CPU fails to respond to a given 1653 backtrace NMI. These prints provide some reasons why a CPU 1654 might legitimately be failing to respond, for example, if it 1655 is offline of if ignore_nmis is set. 1656 1657config DEBUG_IRQFLAGS 1658 bool "Debug IRQ flag manipulation" 1659 help 1660 Enables checks for potentially unsafe enabling or disabling of 1661 interrupts, such as calling raw_local_irq_restore() when interrupts 1662 are enabled. 1663 1664config STACKTRACE 1665 bool "Stack backtrace support" 1666 depends on STACKTRACE_SUPPORT 1667 help 1668 This option causes the kernel to create a /proc/pid/stack for 1669 every process, showing its current stack trace. 1670 It is also used by various kernel debugging features that require 1671 stack trace generation. 1672 1673config WARN_ALL_UNSEEDED_RANDOM 1674 bool "Warn for all uses of unseeded randomness" 1675 default n 1676 help 1677 Some parts of the kernel contain bugs relating to their use of 1678 cryptographically secure random numbers before it's actually possible 1679 to generate those numbers securely. This setting ensures that these 1680 flaws don't go unnoticed, by enabling a message, should this ever 1681 occur. This will allow people with obscure setups to know when things 1682 are going wrong, so that they might contact developers about fixing 1683 it. 1684 1685 Unfortunately, on some models of some architectures getting 1686 a fully seeded CRNG is extremely difficult, and so this can 1687 result in dmesg getting spammed for a surprisingly long 1688 time. This is really bad from a security perspective, and 1689 so architecture maintainers really need to do what they can 1690 to get the CRNG seeded sooner after the system is booted. 1691 However, since users cannot do anything actionable to 1692 address this, by default this option is disabled. 1693 1694 Say Y here if you want to receive warnings for all uses of 1695 unseeded randomness. This will be of use primarily for 1696 those developers interested in improving the security of 1697 Linux kernels running on their architecture (or 1698 subarchitecture). 1699 1700config DEBUG_KOBJECT 1701 bool "kobject debugging" 1702 depends on DEBUG_KERNEL 1703 help 1704 If you say Y here, some extra kobject debugging messages will be sent 1705 to the syslog. 1706 1707config DEBUG_KOBJECT_RELEASE 1708 bool "kobject release debugging" 1709 depends on DEBUG_OBJECTS_TIMERS 1710 help 1711 kobjects are reference counted objects. This means that their 1712 last reference count put is not predictable, and the kobject can 1713 live on past the point at which a driver decides to drop its 1714 initial reference to the kobject gained on allocation. An 1715 example of this would be a struct device which has just been 1716 unregistered. 1717 1718 However, some buggy drivers assume that after such an operation, 1719 the memory backing the kobject can be immediately freed. This 1720 goes completely against the principles of a refcounted object. 1721 1722 If you say Y here, the kernel will delay the release of kobjects 1723 on the last reference count to improve the visibility of this 1724 kind of kobject release bug. 1725 1726config HAVE_DEBUG_BUGVERBOSE 1727 bool 1728 1729menu "Debug kernel data structures" 1730 1731config DEBUG_LIST 1732 bool "Debug linked list manipulation" 1733 depends on DEBUG_KERNEL 1734 select LIST_HARDENED 1735 help 1736 Enable this to turn on extended checks in the linked-list walking 1737 routines. 1738 1739 This option trades better quality error reports for performance, and 1740 is more suitable for kernel debugging. If you care about performance, 1741 you should only enable CONFIG_LIST_HARDENED instead. 1742 1743 If unsure, say N. 1744 1745config DEBUG_PLIST 1746 bool "Debug priority linked list manipulation" 1747 depends on DEBUG_KERNEL 1748 help 1749 Enable this to turn on extended checks in the priority-ordered 1750 linked-list (plist) walking routines. This checks the entire 1751 list multiple times during each manipulation. 1752 1753 If unsure, say N. 1754 1755config DEBUG_SG 1756 bool "Debug SG table operations" 1757 depends on DEBUG_KERNEL 1758 help 1759 Enable this to turn on checks on scatter-gather tables. This can 1760 help find problems with drivers that do not properly initialize 1761 their sg tables. 1762 1763 If unsure, say N. 1764 1765config DEBUG_NOTIFIERS 1766 bool "Debug notifier call chains" 1767 depends on DEBUG_KERNEL 1768 help 1769 Enable this to turn on sanity checking for notifier call chains. 1770 This is most useful for kernel developers to make sure that 1771 modules properly unregister themselves from notifier chains. 1772 This is a relatively cheap check but if you care about maximum 1773 performance, say N. 1774 1775config DEBUG_CLOSURES 1776 bool "Debug closures (bcache async widgits)" 1777 depends on CLOSURES 1778 select DEBUG_FS 1779 help 1780 Keeps all active closures in a linked list and provides a debugfs 1781 interface to list them, which makes it possible to see asynchronous 1782 operations that get stuck. 1783 1784config DEBUG_MAPLE_TREE 1785 bool "Debug maple trees" 1786 depends on DEBUG_KERNEL 1787 help 1788 Enable maple tree debugging information and extra validations. 1789 1790 If unsure, say N. 1791 1792endmenu 1793 1794source "kernel/rcu/Kconfig.debug" 1795 1796config DEBUG_WQ_FORCE_RR_CPU 1797 bool "Force round-robin CPU selection for unbound work items" 1798 depends on DEBUG_KERNEL 1799 default n 1800 help 1801 Workqueue used to implicitly guarantee that work items queued 1802 without explicit CPU specified are put on the local CPU. This 1803 guarantee is no longer true and while local CPU is still 1804 preferred work items may be put on foreign CPUs. Kernel 1805 parameter "workqueue.debug_force_rr_cpu" is added to force 1806 round-robin CPU selection to flush out usages which depend on the 1807 now broken guarantee. This config option enables the debug 1808 feature by default. When enabled, memory and cache locality will 1809 be impacted. 1810 1811config CPU_HOTPLUG_STATE_CONTROL 1812 bool "Enable CPU hotplug state control" 1813 depends on DEBUG_KERNEL 1814 depends on HOTPLUG_CPU 1815 default n 1816 help 1817 Allows to write steps between "offline" and "online" to the CPUs 1818 sysfs target file so states can be stepped granular. This is a debug 1819 option for now as the hotplug machinery cannot be stopped and 1820 restarted at arbitrary points yet. 1821 1822 Say N if your are unsure. 1823 1824config LATENCYTOP 1825 bool "Latency measuring infrastructure" 1826 depends on DEBUG_KERNEL 1827 depends on STACKTRACE_SUPPORT 1828 depends on PROC_FS 1829 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 1830 select KALLSYMS 1831 select KALLSYMS_ALL 1832 select STACKTRACE 1833 select SCHEDSTATS 1834 help 1835 Enable this option if you want to use the LatencyTOP tool 1836 to find out which userspace is blocking on what kernel operations. 1837 1838config DEBUG_CGROUP_REF 1839 bool "Disable inlining of cgroup css reference count functions" 1840 depends on DEBUG_KERNEL 1841 depends on CGROUPS 1842 depends on KPROBES 1843 default n 1844 help 1845 Force cgroup css reference count functions to not be inlined so 1846 that they can be kprobed for debugging. 1847 1848source "kernel/trace/Kconfig" 1849 1850config PROVIDE_OHCI1394_DMA_INIT 1851 bool "Remote debugging over FireWire early on boot" 1852 depends on PCI && X86 1853 help 1854 If you want to debug problems which hang or crash the kernel early 1855 on boot and the crashing machine has a FireWire port, you can use 1856 this feature to remotely access the memory of the crashed machine 1857 over FireWire. This employs remote DMA as part of the OHCI1394 1858 specification which is now the standard for FireWire controllers. 1859 1860 With remote DMA, you can monitor the printk buffer remotely using 1861 firescope and access all memory below 4GB using fireproxy from gdb. 1862 Even controlling a kernel debugger is possible using remote DMA. 1863 1864 Usage: 1865 1866 If ohci1394_dma=early is used as boot parameter, it will initialize 1867 all OHCI1394 controllers which are found in the PCI config space. 1868 1869 As all changes to the FireWire bus such as enabling and disabling 1870 devices cause a bus reset and thereby disable remote DMA for all 1871 devices, be sure to have the cable plugged and FireWire enabled on 1872 the debugging host before booting the debug target for debugging. 1873 1874 This code (~1k) is freed after boot. By then, the firewire stack 1875 in charge of the OHCI-1394 controllers should be used instead. 1876 1877 See Documentation/core-api/debugging-via-ohci1394.rst for more information. 1878 1879source "samples/Kconfig" 1880 1881config ARCH_HAS_DEVMEM_IS_ALLOWED 1882 bool 1883 1884config STRICT_DEVMEM 1885 bool "Filter access to /dev/mem" 1886 depends on MMU && DEVMEM 1887 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED 1888 default y if PPC || X86 || ARM64 1889 help 1890 If this option is disabled, you allow userspace (root) access to all 1891 of memory, including kernel and userspace memory. Accidental 1892 access to this is obviously disastrous, but specific access can 1893 be used by people debugging the kernel. Note that with PAT support 1894 enabled, even in this case there are restrictions on /dev/mem 1895 use due to the cache aliasing requirements. 1896 1897 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 1898 file only allows userspace access to PCI space and the BIOS code and 1899 data regions. This is sufficient for dosemu and X and all common 1900 users of /dev/mem. 1901 1902 If in doubt, say Y. 1903 1904config IO_STRICT_DEVMEM 1905 bool "Filter I/O access to /dev/mem" 1906 depends on STRICT_DEVMEM 1907 help 1908 If this option is disabled, you allow userspace (root) access to all 1909 io-memory regardless of whether a driver is actively using that 1910 range. Accidental access to this is obviously disastrous, but 1911 specific access can be used by people debugging kernel drivers. 1912 1913 If this option is switched on, the /dev/mem file only allows 1914 userspace access to *idle* io-memory ranges (see /proc/iomem) This 1915 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 1916 if the driver using a given range cannot be disabled. 1917 1918 If in doubt, say Y. 1919 1920menu "$(SRCARCH) Debugging" 1921 1922source "arch/$(SRCARCH)/Kconfig.debug" 1923 1924endmenu 1925 1926menu "Kernel Testing and Coverage" 1927 1928source "lib/kunit/Kconfig" 1929 1930config NOTIFIER_ERROR_INJECTION 1931 tristate "Notifier error injection" 1932 depends on DEBUG_KERNEL 1933 select DEBUG_FS 1934 help 1935 This option provides the ability to inject artificial errors to 1936 specified notifier chain callbacks. It is useful to test the error 1937 handling of notifier call chain failures. 1938 1939 Say N if unsure. 1940 1941config PM_NOTIFIER_ERROR_INJECT 1942 tristate "PM notifier error injection module" 1943 depends on PM && NOTIFIER_ERROR_INJECTION 1944 default m if PM_DEBUG 1945 help 1946 This option provides the ability to inject artificial errors to 1947 PM notifier chain callbacks. It is controlled through debugfs 1948 interface /sys/kernel/debug/notifier-error-inject/pm 1949 1950 If the notifier call chain should be failed with some events 1951 notified, write the error code to "actions/<notifier event>/error". 1952 1953 Example: Inject PM suspend error (-12 = -ENOMEM) 1954 1955 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1956 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1957 # echo mem > /sys/power/state 1958 bash: echo: write error: Cannot allocate memory 1959 1960 To compile this code as a module, choose M here: the module will 1961 be called pm-notifier-error-inject. 1962 1963 If unsure, say N. 1964 1965config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1966 tristate "OF reconfig notifier error injection module" 1967 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1968 help 1969 This option provides the ability to inject artificial errors to 1970 OF reconfig notifier chain callbacks. It is controlled 1971 through debugfs interface under 1972 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1973 1974 If the notifier call chain should be failed with some events 1975 notified, write the error code to "actions/<notifier event>/error". 1976 1977 To compile this code as a module, choose M here: the module will 1978 be called of-reconfig-notifier-error-inject. 1979 1980 If unsure, say N. 1981 1982config NETDEV_NOTIFIER_ERROR_INJECT 1983 tristate "Netdev notifier error injection module" 1984 depends on NET && NOTIFIER_ERROR_INJECTION 1985 help 1986 This option provides the ability to inject artificial errors to 1987 netdevice notifier chain callbacks. It is controlled through debugfs 1988 interface /sys/kernel/debug/notifier-error-inject/netdev 1989 1990 If the notifier call chain should be failed with some events 1991 notified, write the error code to "actions/<notifier event>/error". 1992 1993 Example: Inject netdevice mtu change error (-22 = -EINVAL) 1994 1995 # cd /sys/kernel/debug/notifier-error-inject/netdev 1996 # echo -22 > actions/NETDEV_CHANGEMTU/error 1997 # ip link set eth0 mtu 1024 1998 RTNETLINK answers: Invalid argument 1999 2000 To compile this code as a module, choose M here: the module will 2001 be called netdev-notifier-error-inject. 2002 2003 If unsure, say N. 2004 2005config FUNCTION_ERROR_INJECTION 2006 bool "Fault-injections of functions" 2007 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 2008 help 2009 Add fault injections into various functions that are annotated with 2010 ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return 2011 value of these functions. This is useful to test error paths of code. 2012 2013 If unsure, say N 2014 2015config FAULT_INJECTION 2016 bool "Fault-injection framework" 2017 depends on DEBUG_KERNEL 2018 help 2019 Provide fault-injection framework. 2020 For more details, see Documentation/fault-injection/. 2021 2022config FAILSLAB 2023 bool "Fault-injection capability for kmalloc" 2024 depends on FAULT_INJECTION 2025 help 2026 Provide fault-injection capability for kmalloc. 2027 2028config FAIL_PAGE_ALLOC 2029 bool "Fault-injection capability for alloc_pages()" 2030 depends on FAULT_INJECTION 2031 help 2032 Provide fault-injection capability for alloc_pages(). 2033 2034config FAULT_INJECTION_USERCOPY 2035 bool "Fault injection capability for usercopy functions" 2036 depends on FAULT_INJECTION 2037 help 2038 Provides fault-injection capability to inject failures 2039 in usercopy functions (copy_from_user(), get_user(), ...). 2040 2041config FAIL_MAKE_REQUEST 2042 bool "Fault-injection capability for disk IO" 2043 depends on FAULT_INJECTION && BLOCK 2044 help 2045 Provide fault-injection capability for disk IO. 2046 2047config FAIL_IO_TIMEOUT 2048 bool "Fault-injection capability for faking disk interrupts" 2049 depends on FAULT_INJECTION && BLOCK 2050 help 2051 Provide fault-injection capability on end IO handling. This 2052 will make the block layer "forget" an interrupt as configured, 2053 thus exercising the error handling. 2054 2055 Only works with drivers that use the generic timeout handling, 2056 for others it won't do anything. 2057 2058config FAIL_FUTEX 2059 bool "Fault-injection capability for futexes" 2060 select DEBUG_FS 2061 depends on FAULT_INJECTION && FUTEX 2062 help 2063 Provide fault-injection capability for futexes. 2064 2065config FAULT_INJECTION_DEBUG_FS 2066 bool "Debugfs entries for fault-injection capabilities" 2067 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 2068 help 2069 Enable configuration of fault-injection capabilities via debugfs. 2070 2071config FAIL_FUNCTION 2072 bool "Fault-injection capability for functions" 2073 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 2074 help 2075 Provide function-based fault-injection capability. 2076 This will allow you to override a specific function with a return 2077 with given return value. As a result, function caller will see 2078 an error value and have to handle it. This is useful to test the 2079 error handling in various subsystems. 2080 2081config FAIL_MMC_REQUEST 2082 bool "Fault-injection capability for MMC IO" 2083 depends on FAULT_INJECTION_DEBUG_FS && MMC 2084 help 2085 Provide fault-injection capability for MMC IO. 2086 This will make the mmc core return data errors. This is 2087 useful to test the error handling in the mmc block device 2088 and to test how the mmc host driver handles retries from 2089 the block device. 2090 2091config FAIL_SUNRPC 2092 bool "Fault-injection capability for SunRPC" 2093 depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG 2094 help 2095 Provide fault-injection capability for SunRPC and 2096 its consumers. 2097 2098config FAULT_INJECTION_CONFIGFS 2099 bool "Configfs interface for fault-injection capabilities" 2100 depends on FAULT_INJECTION 2101 select CONFIGFS_FS 2102 help 2103 This option allows configfs-based drivers to dynamically configure 2104 fault-injection via configfs. Each parameter for driver-specific 2105 fault-injection can be made visible as a configfs attribute in a 2106 configfs group. 2107 2108 2109config FAULT_INJECTION_STACKTRACE_FILTER 2110 bool "stacktrace filter for fault-injection capabilities" 2111 depends on FAULT_INJECTION 2112 depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT 2113 select STACKTRACE 2114 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 2115 help 2116 Provide stacktrace filter for fault-injection capabilities 2117 2118config ARCH_HAS_KCOV 2119 bool 2120 help 2121 An architecture should select this when it can successfully 2122 build and run with CONFIG_KCOV. This typically requires 2123 disabling instrumentation for some early boot code. 2124 2125config CC_HAS_SANCOV_TRACE_PC 2126 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 2127 2128 2129config KCOV 2130 bool "Code coverage for fuzzing" 2131 depends on ARCH_HAS_KCOV 2132 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 2133 depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \ 2134 GCC_VERSION >= 120000 || CC_IS_CLANG 2135 select DEBUG_FS 2136 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 2137 select OBJTOOL if HAVE_NOINSTR_HACK 2138 help 2139 KCOV exposes kernel code coverage information in a form suitable 2140 for coverage-guided fuzzing (randomized testing). 2141 2142 For more details, see Documentation/dev-tools/kcov.rst. 2143 2144config KCOV_ENABLE_COMPARISONS 2145 bool "Enable comparison operands collection by KCOV" 2146 depends on KCOV 2147 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 2148 help 2149 KCOV also exposes operands of every comparison in the instrumented 2150 code along with operand sizes and PCs of the comparison instructions. 2151 These operands can be used by fuzzing engines to improve the quality 2152 of fuzzing coverage. 2153 2154config KCOV_INSTRUMENT_ALL 2155 bool "Instrument all code by default" 2156 depends on KCOV 2157 default y 2158 help 2159 If you are doing generic system call fuzzing (like e.g. syzkaller), 2160 then you will want to instrument the whole kernel and you should 2161 say y here. If you are doing more targeted fuzzing (like e.g. 2162 filesystem fuzzing with AFL) then you will want to enable coverage 2163 for more specific subsets of files, and should say n here. 2164 2165config KCOV_IRQ_AREA_SIZE 2166 hex "Size of interrupt coverage collection area in words" 2167 depends on KCOV 2168 default 0x40000 2169 help 2170 KCOV uses preallocated per-cpu areas to collect coverage from 2171 soft interrupts. This specifies the size of those areas in the 2172 number of unsigned long words. 2173 2174menuconfig RUNTIME_TESTING_MENU 2175 bool "Runtime Testing" 2176 default y 2177 2178if RUNTIME_TESTING_MENU 2179 2180config TEST_DHRY 2181 tristate "Dhrystone benchmark test" 2182 help 2183 Enable this to include the Dhrystone 2.1 benchmark. This test 2184 calculates the number of Dhrystones per second, and the number of 2185 DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided 2186 by 1757 (the number of Dhrystones per second obtained on the VAX 2187 11/780, nominally a 1 MIPS machine). 2188 2189 To run the benchmark, it needs to be enabled explicitly, either from 2190 the kernel command line (when built-in), or from userspace (when 2191 built-in or modular). 2192 2193 Run once during kernel boot: 2194 2195 test_dhry.run 2196 2197 Set number of iterations from kernel command line: 2198 2199 test_dhry.iterations=<n> 2200 2201 Set number of iterations from userspace: 2202 2203 echo <n> > /sys/module/test_dhry/parameters/iterations 2204 2205 Trigger manual run from userspace: 2206 2207 echo y > /sys/module/test_dhry/parameters/run 2208 2209 If the number of iterations is <= 0, the test will devise a suitable 2210 number of iterations (test runs for at least 2s) automatically. 2211 This process takes ca. 4s. 2212 2213 If unsure, say N. 2214 2215config LKDTM 2216 tristate "Linux Kernel Dump Test Tool Module" 2217 depends on DEBUG_FS 2218 help 2219 This module enables testing of the different dumping mechanisms by 2220 inducing system failures at predefined crash points. 2221 If you don't need it: say N 2222 Choose M here to compile this code as a module. The module will be 2223 called lkdtm. 2224 2225 Documentation on how to use the module can be found in 2226 Documentation/fault-injection/provoke-crashes.rst 2227 2228config CPUMASK_KUNIT_TEST 2229 tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS 2230 depends on KUNIT 2231 default KUNIT_ALL_TESTS 2232 help 2233 Enable to turn on cpumask tests, running at boot or module load time. 2234 2235 For more information on KUnit and unit tests in general, please refer 2236 to the KUnit documentation in Documentation/dev-tools/kunit/. 2237 2238 If unsure, say N. 2239 2240config TEST_LIST_SORT 2241 tristate "Linked list sorting test" if !KUNIT_ALL_TESTS 2242 depends on KUNIT 2243 default KUNIT_ALL_TESTS 2244 help 2245 Enable this to turn on 'list_sort()' function test. This test is 2246 executed only once during system boot (so affects only boot time), 2247 or at module load time. 2248 2249 If unsure, say N. 2250 2251config TEST_MIN_HEAP 2252 tristate "Min heap test" 2253 depends on DEBUG_KERNEL || m 2254 help 2255 Enable this to turn on min heap function tests. This test is 2256 executed only once during system boot (so affects only boot time), 2257 or at module load time. 2258 2259 If unsure, say N. 2260 2261config TEST_SORT 2262 tristate "Array-based sort test" if !KUNIT_ALL_TESTS 2263 depends on KUNIT 2264 default KUNIT_ALL_TESTS 2265 help 2266 This option enables the self-test function of 'sort()' at boot, 2267 or at module load time. 2268 2269 If unsure, say N. 2270 2271config TEST_DIV64 2272 tristate "64bit/32bit division and modulo test" 2273 depends on DEBUG_KERNEL || m 2274 help 2275 Enable this to turn on 'do_div()' function test. This test is 2276 executed only once during system boot (so affects only boot time), 2277 or at module load time. 2278 2279 If unsure, say N. 2280 2281config TEST_IOV_ITER 2282 tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS 2283 depends on KUNIT 2284 depends on MMU 2285 default KUNIT_ALL_TESTS 2286 help 2287 Enable this to turn on testing of the operation of the I/O iterator 2288 (iov_iter). This test is executed only once during system boot (so 2289 affects only boot time), or at module load time. 2290 2291 If unsure, say N. 2292 2293config KPROBES_SANITY_TEST 2294 tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS 2295 depends on DEBUG_KERNEL 2296 depends on KPROBES 2297 depends on KUNIT 2298 select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 2299 default KUNIT_ALL_TESTS 2300 help 2301 This option provides for testing basic kprobes functionality on 2302 boot. Samples of kprobe and kretprobe are inserted and 2303 verified for functionality. 2304 2305 Say N if you are unsure. 2306 2307config FPROBE_SANITY_TEST 2308 bool "Self test for fprobe" 2309 depends on DEBUG_KERNEL 2310 depends on FPROBE 2311 depends on KUNIT=y 2312 help 2313 This option will enable testing the fprobe when the system boot. 2314 A series of tests are made to verify that the fprobe is functioning 2315 properly. 2316 2317 Say N if you are unsure. 2318 2319config BACKTRACE_SELF_TEST 2320 tristate "Self test for the backtrace code" 2321 depends on DEBUG_KERNEL 2322 help 2323 This option provides a kernel module that can be used to test 2324 the kernel stack backtrace code. This option is not useful 2325 for distributions or general kernels, but only for kernel 2326 developers working on architecture code. 2327 2328 Note that if you want to also test saved backtraces, you will 2329 have to enable STACKTRACE as well. 2330 2331 Say N if you are unsure. 2332 2333config TEST_REF_TRACKER 2334 tristate "Self test for reference tracker" 2335 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT 2336 select REF_TRACKER 2337 help 2338 This option provides a kernel module performing tests 2339 using reference tracker infrastructure. 2340 2341 Say N if you are unsure. 2342 2343config RBTREE_TEST 2344 tristate "Red-Black tree test" 2345 depends on DEBUG_KERNEL 2346 help 2347 A benchmark measuring the performance of the rbtree library. 2348 Also includes rbtree invariant checks. 2349 2350config REED_SOLOMON_TEST 2351 tristate "Reed-Solomon library test" 2352 depends on DEBUG_KERNEL || m 2353 select REED_SOLOMON 2354 select REED_SOLOMON_ENC16 2355 select REED_SOLOMON_DEC16 2356 help 2357 This option enables the self-test function of rslib at boot, 2358 or at module load time. 2359 2360 If unsure, say N. 2361 2362config INTERVAL_TREE_TEST 2363 tristate "Interval tree test" 2364 depends on DEBUG_KERNEL 2365 select INTERVAL_TREE 2366 help 2367 A benchmark measuring the performance of the interval tree library 2368 2369config PERCPU_TEST 2370 tristate "Per cpu operations test" 2371 depends on m && DEBUG_KERNEL 2372 help 2373 Enable this option to build test module which validates per-cpu 2374 operations. 2375 2376 If unsure, say N. 2377 2378config ATOMIC64_SELFTEST 2379 tristate "Perform an atomic64_t self-test" 2380 help 2381 Enable this option to test the atomic64_t functions at boot or 2382 at module load time. 2383 2384 If unsure, say N. 2385 2386config ASYNC_RAID6_TEST 2387 tristate "Self test for hardware accelerated raid6 recovery" 2388 depends on ASYNC_RAID6_RECOV 2389 select ASYNC_MEMCPY 2390 help 2391 This is a one-shot self test that permutes through the 2392 recovery of all the possible two disk failure scenarios for a 2393 N-disk array. Recovery is performed with the asynchronous 2394 raid6 recovery routines, and will optionally use an offload 2395 engine if one is available. 2396 2397 If unsure, say N. 2398 2399config TEST_HEXDUMP 2400 tristate "Test functions located in the hexdump module at runtime" 2401 2402config STRING_KUNIT_TEST 2403 tristate "KUnit test string functions at runtime" if !KUNIT_ALL_TESTS 2404 depends on KUNIT 2405 default KUNIT_ALL_TESTS 2406 2407config STRING_HELPERS_KUNIT_TEST 2408 tristate "KUnit test string helpers at runtime" if !KUNIT_ALL_TESTS 2409 depends on KUNIT 2410 default KUNIT_ALL_TESTS 2411 2412config TEST_KSTRTOX 2413 tristate "Test kstrto*() family of functions at runtime" 2414 2415config TEST_PRINTF 2416 tristate "Test printf() family of functions at runtime" 2417 2418config TEST_SCANF 2419 tristate "Test scanf() family of functions at runtime" 2420 2421config TEST_BITMAP 2422 tristate "Test bitmap_*() family of functions at runtime" 2423 help 2424 Enable this option to test the bitmap functions at boot. 2425 2426 If unsure, say N. 2427 2428config TEST_UUID 2429 tristate "Test functions located in the uuid module at runtime" 2430 2431config TEST_XARRAY 2432 tristate "Test the XArray code at runtime" 2433 2434config TEST_MAPLE_TREE 2435 tristate "Test the Maple Tree code at runtime or module load" 2436 help 2437 Enable this option to test the maple tree code functions at boot, or 2438 when the module is loaded. Enable "Debug Maple Trees" will enable 2439 more verbose output on failures. 2440 2441 If unsure, say N. 2442 2443config TEST_RHASHTABLE 2444 tristate "Perform selftest on resizable hash table" 2445 help 2446 Enable this option to test the rhashtable functions at boot. 2447 2448 If unsure, say N. 2449 2450config TEST_IDA 2451 tristate "Perform selftest on IDA functions" 2452 2453config TEST_PARMAN 2454 tristate "Perform selftest on priority array manager" 2455 depends on PARMAN 2456 help 2457 Enable this option to test priority array manager on boot 2458 (or module load). 2459 2460 If unsure, say N. 2461 2462config TEST_IRQ_TIMINGS 2463 bool "IRQ timings selftest" 2464 depends on IRQ_TIMINGS 2465 help 2466 Enable this option to test the irq timings code on boot. 2467 2468 If unsure, say N. 2469 2470config TEST_LKM 2471 tristate "Test module loading with 'hello world' module" 2472 depends on m 2473 help 2474 This builds the "test_module" module that emits "Hello, world" 2475 on printk when loaded. It is designed to be used for basic 2476 evaluation of the module loading subsystem (for example when 2477 validating module verification). It lacks any extra dependencies, 2478 and will not normally be loaded by the system unless explicitly 2479 requested by name. 2480 2481 If unsure, say N. 2482 2483config TEST_BITOPS 2484 tristate "Test module for compilation of bitops operations" 2485 help 2486 This builds the "test_bitops" module that is much like the 2487 TEST_LKM module except that it does a basic exercise of the 2488 set/clear_bit macros and get_count_order/long to make sure there are 2489 no compiler warnings from C=1 sparse checker or -Wextra 2490 compilations. It has no dependencies and doesn't run or load unless 2491 explicitly requested by name. for example: modprobe test_bitops. 2492 2493 If unsure, say N. 2494 2495config TEST_VMALLOC 2496 tristate "Test module for stress/performance analysis of vmalloc allocator" 2497 default n 2498 depends on MMU 2499 depends on m 2500 help 2501 This builds the "test_vmalloc" module that should be used for 2502 stress and performance analysis. So, any new change for vmalloc 2503 subsystem can be evaluated from performance and stability point 2504 of view. 2505 2506 If unsure, say N. 2507 2508config TEST_USER_COPY 2509 tristate "Test user/kernel boundary protections" 2510 depends on m 2511 help 2512 This builds the "test_user_copy" module that runs sanity checks 2513 on the copy_to/from_user infrastructure, making sure basic 2514 user/kernel boundary testing is working. If it fails to load, 2515 a regression has been detected in the user/kernel memory boundary 2516 protections. 2517 2518 If unsure, say N. 2519 2520config TEST_BPF 2521 tristate "Test BPF filter functionality" 2522 depends on m && NET 2523 help 2524 This builds the "test_bpf" module that runs various test vectors 2525 against the BPF interpreter or BPF JIT compiler depending on the 2526 current setting. This is in particular useful for BPF JIT compiler 2527 development, but also to run regression tests against changes in 2528 the interpreter code. It also enables test stubs for eBPF maps and 2529 verifier used by user space verifier testsuite. 2530 2531 If unsure, say N. 2532 2533config TEST_BLACKHOLE_DEV 2534 tristate "Test blackhole netdev functionality" 2535 depends on m && NET 2536 help 2537 This builds the "test_blackhole_dev" module that validates the 2538 data path through this blackhole netdev. 2539 2540 If unsure, say N. 2541 2542config FIND_BIT_BENCHMARK 2543 tristate "Test find_bit functions" 2544 help 2545 This builds the "test_find_bit" module that measure find_*_bit() 2546 functions performance. 2547 2548 If unsure, say N. 2549 2550config TEST_FIRMWARE 2551 tristate "Test firmware loading via userspace interface" 2552 depends on FW_LOADER 2553 help 2554 This builds the "test_firmware" module that creates a userspace 2555 interface for testing firmware loading. This can be used to 2556 control the triggering of firmware loading without needing an 2557 actual firmware-using device. The contents can be rechecked by 2558 userspace. 2559 2560 If unsure, say N. 2561 2562config TEST_SYSCTL 2563 tristate "sysctl test driver" 2564 depends on PROC_SYSCTL 2565 help 2566 This builds the "test_sysctl" module. This driver enables to test the 2567 proc sysctl interfaces available to drivers safely without affecting 2568 production knobs which might alter system functionality. 2569 2570 If unsure, say N. 2571 2572config BITFIELD_KUNIT 2573 tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS 2574 depends on KUNIT 2575 default KUNIT_ALL_TESTS 2576 help 2577 Enable this option to test the bitfield functions at boot. 2578 2579 KUnit tests run during boot and output the results to the debug log 2580 in TAP format (http://testanything.org/). Only useful for kernel devs 2581 running the KUnit test harness, and not intended for inclusion into a 2582 production build. 2583 2584 For more information on KUnit and unit tests in general please refer 2585 to the KUnit documentation in Documentation/dev-tools/kunit/. 2586 2587 If unsure, say N. 2588 2589config CHECKSUM_KUNIT 2590 tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS 2591 depends on KUNIT 2592 default KUNIT_ALL_TESTS 2593 help 2594 Enable this option to test the checksum functions at boot. 2595 2596 KUnit tests run during boot and output the results to the debug log 2597 in TAP format (http://testanything.org/). Only useful for kernel devs 2598 running the KUnit test harness, and not intended for inclusion into a 2599 production build. 2600 2601 For more information on KUnit and unit tests in general please refer 2602 to the KUnit documentation in Documentation/dev-tools/kunit/. 2603 2604 If unsure, say N. 2605 2606config HASH_KUNIT_TEST 2607 tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS 2608 depends on KUNIT 2609 default KUNIT_ALL_TESTS 2610 help 2611 Enable this option to test the kernel's string (<linux/stringhash.h>), and 2612 integer (<linux/hash.h>) hash functions on boot. 2613 2614 KUnit tests run during boot and output the results to the debug log 2615 in TAP format (https://testanything.org/). Only useful for kernel devs 2616 running the KUnit test harness, and not intended for inclusion into a 2617 production build. 2618 2619 For more information on KUnit and unit tests in general please refer 2620 to the KUnit documentation in Documentation/dev-tools/kunit/. 2621 2622 This is intended to help people writing architecture-specific 2623 optimized versions. If unsure, say N. 2624 2625config RESOURCE_KUNIT_TEST 2626 tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS 2627 depends on KUNIT 2628 default KUNIT_ALL_TESTS 2629 help 2630 This builds the resource API unit test. 2631 Tests the logic of API provided by resource.c and ioport.h. 2632 For more information on KUnit and unit tests in general please refer 2633 to the KUnit documentation in Documentation/dev-tools/kunit/. 2634 2635 If unsure, say N. 2636 2637config SYSCTL_KUNIT_TEST 2638 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS 2639 depends on KUNIT 2640 default KUNIT_ALL_TESTS 2641 help 2642 This builds the proc sysctl unit test, which runs on boot. 2643 Tests the API contract and implementation correctness of sysctl. 2644 For more information on KUnit and unit tests in general please refer 2645 to the KUnit documentation in Documentation/dev-tools/kunit/. 2646 2647 If unsure, say N. 2648 2649config LIST_KUNIT_TEST 2650 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS 2651 depends on KUNIT 2652 default KUNIT_ALL_TESTS 2653 help 2654 This builds the linked list KUnit test suite. 2655 It tests that the API and basic functionality of the list_head type 2656 and associated macros. 2657 2658 KUnit tests run during boot and output the results to the debug log 2659 in TAP format (https://testanything.org/). Only useful for kernel devs 2660 running the KUnit test harness, and not intended for inclusion into a 2661 production build. 2662 2663 For more information on KUnit and unit tests in general please refer 2664 to the KUnit documentation in Documentation/dev-tools/kunit/. 2665 2666 If unsure, say N. 2667 2668config HASHTABLE_KUNIT_TEST 2669 tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS 2670 depends on KUNIT 2671 default KUNIT_ALL_TESTS 2672 help 2673 This builds the hashtable KUnit test suite. 2674 It tests the basic functionality of the API defined in 2675 include/linux/hashtable.h. For more information on KUnit and 2676 unit tests in general please refer to the KUnit documentation 2677 in Documentation/dev-tools/kunit/. 2678 2679 If unsure, say N. 2680 2681config LINEAR_RANGES_TEST 2682 tristate "KUnit test for linear_ranges" 2683 depends on KUNIT 2684 select LINEAR_RANGES 2685 help 2686 This builds the linear_ranges unit test, which runs on boot. 2687 Tests the linear_ranges logic correctness. 2688 For more information on KUnit and unit tests in general please refer 2689 to the KUnit documentation in Documentation/dev-tools/kunit/. 2690 2691 If unsure, say N. 2692 2693config CMDLINE_KUNIT_TEST 2694 tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS 2695 depends on KUNIT 2696 default KUNIT_ALL_TESTS 2697 help 2698 This builds the cmdline API unit test. 2699 Tests the logic of API provided by cmdline.c. 2700 For more information on KUnit and unit tests in general please refer 2701 to the KUnit documentation in Documentation/dev-tools/kunit/. 2702 2703 If unsure, say N. 2704 2705config BITS_TEST 2706 tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS 2707 depends on KUNIT 2708 default KUNIT_ALL_TESTS 2709 help 2710 This builds the bits unit test. 2711 Tests the logic of macros defined in bits.h. 2712 For more information on KUnit and unit tests in general please refer 2713 to the KUnit documentation in Documentation/dev-tools/kunit/. 2714 2715 If unsure, say N. 2716 2717config SLUB_KUNIT_TEST 2718 tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS 2719 depends on SLUB_DEBUG && KUNIT 2720 default KUNIT_ALL_TESTS 2721 help 2722 This builds SLUB allocator unit test. 2723 Tests SLUB cache debugging functionality. 2724 For more information on KUnit and unit tests in general please refer 2725 to the KUnit documentation in Documentation/dev-tools/kunit/. 2726 2727 If unsure, say N. 2728 2729config RATIONAL_KUNIT_TEST 2730 tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS 2731 depends on KUNIT && RATIONAL 2732 default KUNIT_ALL_TESTS 2733 help 2734 This builds the rational math unit test. 2735 For more information on KUnit and unit tests in general please refer 2736 to the KUnit documentation in Documentation/dev-tools/kunit/. 2737 2738 If unsure, say N. 2739 2740config MEMCPY_KUNIT_TEST 2741 tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS 2742 depends on KUNIT 2743 default KUNIT_ALL_TESTS 2744 help 2745 Builds unit tests for memcpy(), memmove(), and memset() functions. 2746 For more information on KUnit and unit tests in general please refer 2747 to the KUnit documentation in Documentation/dev-tools/kunit/. 2748 2749 If unsure, say N. 2750 2751config IS_SIGNED_TYPE_KUNIT_TEST 2752 tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS 2753 depends on KUNIT 2754 default KUNIT_ALL_TESTS 2755 help 2756 Builds unit tests for the is_signed_type() macro. 2757 2758 For more information on KUnit and unit tests in general please refer 2759 to the KUnit documentation in Documentation/dev-tools/kunit/. 2760 2761 If unsure, say N. 2762 2763config OVERFLOW_KUNIT_TEST 2764 tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS 2765 depends on KUNIT 2766 default KUNIT_ALL_TESTS 2767 help 2768 Builds unit tests for the check_*_overflow(), size_*(), allocation, and 2769 related functions. 2770 2771 For more information on KUnit and unit tests in general please refer 2772 to the KUnit documentation in Documentation/dev-tools/kunit/. 2773 2774 If unsure, say N. 2775 2776config STACKINIT_KUNIT_TEST 2777 tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS 2778 depends on KUNIT 2779 default KUNIT_ALL_TESTS 2780 help 2781 Test if the kernel is zero-initializing stack variables and 2782 padding. Coverage is controlled by compiler flags, 2783 CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO, 2784 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2785 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2786 2787config FORTIFY_KUNIT_TEST 2788 tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS 2789 depends on KUNIT 2790 default KUNIT_ALL_TESTS 2791 help 2792 Builds unit tests for checking internals of FORTIFY_SOURCE as used 2793 by the str*() and mem*() family of functions. For testing runtime 2794 traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests. 2795 2796config HW_BREAKPOINT_KUNIT_TEST 2797 bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS 2798 depends on HAVE_HW_BREAKPOINT 2799 depends on KUNIT=y 2800 default KUNIT_ALL_TESTS 2801 help 2802 Tests for hw_breakpoint constraints accounting. 2803 2804 If unsure, say N. 2805 2806config SIPHASH_KUNIT_TEST 2807 tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS 2808 depends on KUNIT 2809 default KUNIT_ALL_TESTS 2810 help 2811 Enable this option to test the kernel's siphash (<linux/siphash.h>) hash 2812 functions on boot (or module load). 2813 2814 This is intended to help people writing architecture-specific 2815 optimized versions. If unsure, say N. 2816 2817config TEST_UDELAY 2818 tristate "udelay test driver" 2819 help 2820 This builds the "udelay_test" module that helps to make sure 2821 that udelay() is working properly. 2822 2823 If unsure, say N. 2824 2825config TEST_STATIC_KEYS 2826 tristate "Test static keys" 2827 depends on m 2828 help 2829 Test the static key interfaces. 2830 2831 If unsure, say N. 2832 2833config TEST_DYNAMIC_DEBUG 2834 tristate "Test DYNAMIC_DEBUG" 2835 depends on DYNAMIC_DEBUG 2836 help 2837 This module registers a tracer callback to count enabled 2838 pr_debugs in a 'do_debugging' function, then alters their 2839 enablements, calls the function, and compares counts. 2840 2841 If unsure, say N. 2842 2843config TEST_KMOD 2844 tristate "kmod stress tester" 2845 depends on m 2846 depends on NETDEVICES && NET_CORE && INET # for TUN 2847 depends on BLOCK 2848 depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS 2849 select TEST_LKM 2850 select XFS_FS 2851 select TUN 2852 select BTRFS_FS 2853 help 2854 Test the kernel's module loading mechanism: kmod. kmod implements 2855 support to load modules using the Linux kernel's usermode helper. 2856 This test provides a series of tests against kmod. 2857 2858 Although technically you can either build test_kmod as a module or 2859 into the kernel we disallow building it into the kernel since 2860 it stress tests request_module() and this will very likely cause 2861 some issues by taking over precious threads available from other 2862 module load requests, ultimately this could be fatal. 2863 2864 To run tests run: 2865 2866 tools/testing/selftests/kmod/kmod.sh --help 2867 2868 If unsure, say N. 2869 2870config TEST_DEBUG_VIRTUAL 2871 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 2872 depends on DEBUG_VIRTUAL 2873 help 2874 Test the kernel's ability to detect incorrect calls to 2875 virt_to_phys() done against the non-linear part of the 2876 kernel's virtual address map. 2877 2878 If unsure, say N. 2879 2880config TEST_MEMCAT_P 2881 tristate "Test memcat_p() helper function" 2882 help 2883 Test the memcat_p() helper for correctly merging two 2884 pointer arrays together. 2885 2886 If unsure, say N. 2887 2888config TEST_OBJAGG 2889 tristate "Perform selftest on object aggreration manager" 2890 default n 2891 depends on OBJAGG 2892 help 2893 Enable this option to test object aggregation manager on boot 2894 (or module load). 2895 2896config TEST_MEMINIT 2897 tristate "Test heap/page initialization" 2898 help 2899 Test if the kernel is zero-initializing heap and page allocations. 2900 This can be useful to test init_on_alloc and init_on_free features. 2901 2902 If unsure, say N. 2903 2904config TEST_HMM 2905 tristate "Test HMM (Heterogeneous Memory Management)" 2906 depends on TRANSPARENT_HUGEPAGE 2907 depends on DEVICE_PRIVATE 2908 select HMM_MIRROR 2909 select MMU_NOTIFIER 2910 help 2911 This is a pseudo device driver solely for testing HMM. 2912 Say M here if you want to build the HMM test module. 2913 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests. 2914 2915 If unsure, say N. 2916 2917config TEST_FREE_PAGES 2918 tristate "Test freeing pages" 2919 help 2920 Test that a memory leak does not occur due to a race between 2921 freeing a block of pages and a speculative page reference. 2922 Loading this module is safe if your kernel has the bug fixed. 2923 If the bug is not fixed, it will leak gigabytes of memory and 2924 probably OOM your system. 2925 2926config TEST_FPU 2927 tristate "Test floating point operations in kernel space" 2928 depends on ARCH_HAS_KERNEL_FPU_SUPPORT && !KCOV_INSTRUMENT_ALL 2929 help 2930 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu 2931 which will trigger a sequence of floating point operations. This is used 2932 for self-testing floating point control register setting in 2933 kernel_fpu_begin(). 2934 2935 If unsure, say N. 2936 2937config TEST_CLOCKSOURCE_WATCHDOG 2938 tristate "Test clocksource watchdog in kernel space" 2939 depends on CLOCKSOURCE_WATCHDOG 2940 help 2941 Enable this option to create a kernel module that will trigger 2942 a test of the clocksource watchdog. This module may be loaded 2943 via modprobe or insmod in which case it will run upon being 2944 loaded, or it may be built in, in which case it will run 2945 shortly after boot. 2946 2947 If unsure, say N. 2948 2949config TEST_OBJPOOL 2950 tristate "Test module for correctness and stress of objpool" 2951 default n 2952 depends on m && DEBUG_KERNEL 2953 help 2954 This builds the "test_objpool" module that should be used for 2955 correctness verification and concurrent testings of objects 2956 allocation and reclamation. 2957 2958 If unsure, say N. 2959 2960endif # RUNTIME_TESTING_MENU 2961 2962config ARCH_USE_MEMTEST 2963 bool 2964 help 2965 An architecture should select this when it uses early_memtest() 2966 during boot process. 2967 2968config MEMTEST 2969 bool "Memtest" 2970 depends on ARCH_USE_MEMTEST 2971 help 2972 This option adds a kernel parameter 'memtest', which allows memtest 2973 to be set and executed. 2974 memtest=0, mean disabled; -- default 2975 memtest=1, mean do 1 test pattern; 2976 ... 2977 memtest=17, mean do 17 test patterns. 2978 If you are unsure how to answer this question, answer N. 2979 2980 2981 2982config HYPERV_TESTING 2983 bool "Microsoft Hyper-V driver testing" 2984 default n 2985 depends on HYPERV && DEBUG_FS 2986 help 2987 Select this option to enable Hyper-V vmbus testing. 2988 2989endmenu # "Kernel Testing and Coverage" 2990 2991menu "Rust hacking" 2992 2993config RUST_DEBUG_ASSERTIONS 2994 bool "Debug assertions" 2995 depends on RUST 2996 help 2997 Enables rustc's `-Cdebug-assertions` codegen option. 2998 2999 This flag lets you turn `cfg(debug_assertions)` conditional 3000 compilation on or off. This can be used to enable extra debugging 3001 code in development but not in production. For example, it controls 3002 the behavior of the standard library's `debug_assert!` macro. 3003 3004 Note that this will apply to all Rust code, including `core`. 3005 3006 If unsure, say N. 3007 3008config RUST_OVERFLOW_CHECKS 3009 bool "Overflow checks" 3010 default y 3011 depends on RUST 3012 help 3013 Enables rustc's `-Coverflow-checks` codegen option. 3014 3015 This flag allows you to control the behavior of runtime integer 3016 overflow. When overflow-checks are enabled, a Rust panic will occur 3017 on overflow. 3018 3019 Note that this will apply to all Rust code, including `core`. 3020 3021 If unsure, say Y. 3022 3023config RUST_BUILD_ASSERT_ALLOW 3024 bool "Allow unoptimized build-time assertions" 3025 depends on RUST 3026 help 3027 Controls how are `build_error!` and `build_assert!` handled during build. 3028 3029 If calls to them exist in the binary, it may indicate a violated invariant 3030 or that the optimizer failed to verify the invariant during compilation. 3031 3032 This should not happen, thus by default the build is aborted. However, 3033 as an escape hatch, you can choose Y here to ignore them during build 3034 and let the check be carried at runtime (with `panic!` being called if 3035 the check fails). 3036 3037 If unsure, say N. 3038 3039config RUST_KERNEL_DOCTESTS 3040 bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS 3041 depends on RUST && KUNIT=y 3042 default KUNIT_ALL_TESTS 3043 help 3044 This builds the documentation tests of the `kernel` crate 3045 as KUnit tests. 3046 3047 For more information on KUnit and unit tests in general, 3048 please refer to the KUnit documentation in Documentation/dev-tools/kunit/. 3049 3050 If unsure, say N. 3051 3052endmenu # "Rust" 3053 3054endmenu # Kernel hacking 3055