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 CONSOLE_LOGLEVEL_DEFAULT 39 int "Default console loglevel (1-15)" 40 range 1 15 41 default "7" 42 help 43 Default loglevel to determine what will be printed on the console. 44 45 Setting a default here is equivalent to passing in loglevel=<x> in 46 the kernel bootargs. loglevel=<x> continues to override whatever 47 value is specified here as well. 48 49 Note: This does not affect the log level of un-prefixed printk() 50 usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT 51 option. 52 53config CONSOLE_LOGLEVEL_QUIET 54 int "quiet console loglevel (1-15)" 55 range 1 15 56 default "4" 57 help 58 loglevel to use when "quiet" is passed on the kernel commandline. 59 60 When "quiet" is passed on the kernel commandline this loglevel 61 will be used as the loglevel. IOW passing "quiet" will be the 62 equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>" 63 64config MESSAGE_LOGLEVEL_DEFAULT 65 int "Default message log level (1-7)" 66 range 1 7 67 default "4" 68 help 69 Default log level for printk statements with no specified priority. 70 71 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks 72 that are auditing their logs closely may want to set it to a lower 73 priority. 74 75 Note: This does not affect what message level gets printed on the console 76 by default. To change that, use loglevel=<x> in the kernel bootargs, 77 or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value. 78 79config BOOT_PRINTK_DELAY 80 bool "Delay each boot printk message by N milliseconds" 81 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY 82 help 83 This build option allows you to read kernel boot messages 84 by inserting a short delay after each one. The delay is 85 specified in milliseconds on the kernel command line, 86 using "boot_delay=N". 87 88 It is likely that you would also need to use "lpj=M" to preset 89 the "loops per jiffie" value. 90 See a previous boot log for the "lpj" value to use for your 91 system, and then set "lpj=M" before setting "boot_delay=N". 92 NOTE: Using this option may adversely affect SMP systems. 93 I.e., processors other than the first one may not boot up. 94 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect 95 what it believes to be lockup conditions. 96 97config DYNAMIC_DEBUG 98 bool "Enable dynamic printk() support" 99 default n 100 depends on PRINTK 101 depends on (DEBUG_FS || PROC_FS) 102 select DYNAMIC_DEBUG_CORE 103 help 104 105 Compiles debug level messages into the kernel, which would not 106 otherwise be available at runtime. These messages can then be 107 enabled/disabled based on various levels of scope - per source file, 108 function, module, format string, and line number. This mechanism 109 implicitly compiles in all pr_debug() and dev_dbg() calls, which 110 enlarges the kernel text size by about 2%. 111 112 If a source file is compiled with DEBUG flag set, any 113 pr_debug() calls in it are enabled by default, but can be 114 disabled at runtime as below. Note that DEBUG flag is 115 turned on by many CONFIG_*DEBUG* options. 116 117 Usage: 118 119 Dynamic debugging is controlled via the 'dynamic_debug/control' file, 120 which is contained in the 'debugfs' filesystem or procfs. 121 Thus, the debugfs or procfs filesystem must first be mounted before 122 making use of this feature. 123 We refer the control file as: <debugfs>/dynamic_debug/control. This 124 file contains a list of the debug statements that can be enabled. The 125 format for each line of the file is: 126 127 filename:lineno [module]function flags format 128 129 filename : source file of the debug statement 130 lineno : line number of the debug statement 131 module : module that contains the debug statement 132 function : function that contains the debug statement 133 flags : '=p' means the line is turned 'on' for printing 134 format : the format used for the debug statement 135 136 From a live system: 137 138 nullarbor:~ # cat <debugfs>/dynamic_debug/control 139 # filename:lineno [module]function flags format 140 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012" 141 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012" 142 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012" 143 144 Example usage: 145 146 // enable the message at line 1603 of file svcsock.c 147 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' > 148 <debugfs>/dynamic_debug/control 149 150 // enable all the messages in file svcsock.c 151 nullarbor:~ # echo -n 'file svcsock.c +p' > 152 <debugfs>/dynamic_debug/control 153 154 // enable all the messages in the NFS server module 155 nullarbor:~ # echo -n 'module nfsd +p' > 156 <debugfs>/dynamic_debug/control 157 158 // enable all 12 messages in the function svc_process() 159 nullarbor:~ # echo -n 'func svc_process +p' > 160 <debugfs>/dynamic_debug/control 161 162 // disable all 12 messages in the function svc_process() 163 nullarbor:~ # echo -n 'func svc_process -p' > 164 <debugfs>/dynamic_debug/control 165 166 See Documentation/admin-guide/dynamic-debug-howto.rst for additional 167 information. 168 169config DYNAMIC_DEBUG_CORE 170 bool "Enable core function of dynamic debug support" 171 depends on PRINTK 172 depends on (DEBUG_FS || PROC_FS) 173 help 174 Enable core functional support of dynamic debug. It is useful 175 when you want to tie dynamic debug to your kernel modules with 176 DYNAMIC_DEBUG_MODULE defined for each of them, especially for 177 the case of embedded system where the kernel image size is 178 sensitive for people. 179 180config SYMBOLIC_ERRNAME 181 bool "Support symbolic error names in printf" 182 default y if PRINTK 183 help 184 If you say Y here, the kernel's printf implementation will 185 be able to print symbolic error names such as ENOSPC instead 186 of the number 28. It makes the kernel image slightly larger 187 (about 3KB), but can make the kernel logs easier to read. 188 189config DEBUG_BUGVERBOSE 190 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT 191 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE) 192 default y 193 help 194 Say Y here to make BUG() panics output the file name and line number 195 of the BUG call as well as the EIP and oops trace. This aids 196 debugging but costs about 70-100K of memory. 197 198endmenu # "printk and dmesg options" 199 200menu "Compile-time checks and compiler options" 201 202config DEBUG_INFO 203 bool "Compile the kernel with debug info" 204 depends on DEBUG_KERNEL && !COMPILE_TEST 205 help 206 If you say Y here the resulting kernel image will include 207 debugging info resulting in a larger kernel image. 208 This adds debug symbols to the kernel and modules (gcc -g), and 209 is needed if you intend to use kernel crashdump or binary object 210 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 211 Say Y here only if you plan to debug the kernel. 212 213 If unsure, say N. 214 215if DEBUG_INFO 216 217config DEBUG_INFO_REDUCED 218 bool "Reduce debugging information" 219 help 220 If you say Y here gcc is instructed to generate less debugging 221 information for structure types. This means that tools that 222 need full debugging information (like kgdb or systemtap) won't 223 be happy. But if you merely need debugging information to 224 resolve line numbers there is no loss. Advantage is that 225 build directory object sizes shrink dramatically over a full 226 DEBUG_INFO build and compile times are reduced too. 227 Only works with newer gcc versions. 228 229config DEBUG_INFO_COMPRESSED 230 bool "Compressed debugging information" 231 depends on $(cc-option,-gz=zlib) 232 depends on $(ld-option,--compress-debug-sections=zlib) 233 help 234 Compress the debug information using zlib. Requires GCC 5.0+ or Clang 235 5.0+, binutils 2.26+, and zlib. 236 237 Users of dpkg-deb via scripts/package/builddeb may find an increase in 238 size of their debug .deb packages with this config set, due to the 239 debug info being compressed with zlib, then the object files being 240 recompressed with a different compression scheme. But this is still 241 preferable to setting $KDEB_COMPRESS to "none" which would be even 242 larger. 243 244config DEBUG_INFO_SPLIT 245 bool "Produce split debuginfo in .dwo files" 246 depends on $(cc-option,-gsplit-dwarf) 247 help 248 Generate debug info into separate .dwo files. This significantly 249 reduces the build directory size for builds with DEBUG_INFO, 250 because it stores the information only once on disk in .dwo 251 files instead of multiple times in object files and executables. 252 In addition the debug information is also compressed. 253 254 Requires recent gcc (4.7+) and recent gdb/binutils. 255 Any tool that packages or reads debug information would need 256 to know about the .dwo files and include them. 257 Incompatible with older versions of ccache. 258 259choice 260 prompt "DWARF version" 261 help 262 Which version of DWARF debug info to emit. 263 264config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT 265 bool "Rely on the toolchain's implicit default DWARF version" 266 help 267 The implicit default version of DWARF debug info produced by a 268 toolchain changes over time. 269 270 This can break consumers of the debug info that haven't upgraded to 271 support newer revisions, and prevent testing newer versions, but 272 those should be less common scenarios. 273 274 If unsure, say Y. 275 276config DEBUG_INFO_DWARF4 277 bool "Generate DWARF Version 4 debuginfo" 278 help 279 Generate DWARF v4 debug info. This requires gcc 4.5+ and gdb 7.0+. 280 281 If you have consumers of DWARF debug info that are not ready for 282 newer revisions of DWARF, you may wish to choose this or have your 283 config select this. 284 285config DEBUG_INFO_DWARF5 286 bool "Generate DWARF Version 5 debuginfo" 287 depends on GCC_VERSION >= 50000 || (CC_IS_CLANG && (AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502))) 288 depends on !DEBUG_INFO_BTF 289 help 290 Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc 291 5.0+ accepts the -gdwarf-5 flag but only had partial support for some 292 draft features until 7.0), and gdb 8.0+. 293 294 Changes to the structure of debug info in Version 5 allow for around 295 15-18% savings in resulting image and debug info section sizes as 296 compared to DWARF Version 4. DWARF Version 5 standardizes previous 297 extensions such as accelerators for symbol indexing and the format 298 for fission (.dwo/.dwp) files. Users may not want to select this 299 config if they rely on tooling that has not yet been updated to 300 support DWARF Version 5. 301 302endchoice # "DWARF version" 303 304config DEBUG_INFO_BTF 305 bool "Generate BTF typeinfo" 306 depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED 307 depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST 308 help 309 Generate deduplicated BTF type information from DWARF debug info. 310 Turning this on expects presence of pahole tool, which will convert 311 DWARF type info into equivalent deduplicated BTF type info. 312 313config PAHOLE_HAS_SPLIT_BTF 314 def_bool $(success, test `$(PAHOLE) --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/'` -ge "119") 315 316config DEBUG_INFO_BTF_MODULES 317 def_bool y 318 depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF 319 help 320 Generate compact split BTF type information for kernel modules. 321 322config GDB_SCRIPTS 323 bool "Provide GDB scripts for kernel debugging" 324 help 325 This creates the required links to GDB helper scripts in the 326 build directory. If you load vmlinux into gdb, the helper 327 scripts will be automatically imported by gdb as well, and 328 additional functions are available to analyze a Linux kernel 329 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst 330 for further details. 331 332endif # DEBUG_INFO 333 334config FRAME_WARN 335 int "Warn for stack frames larger than" 336 range 0 8192 337 default 2048 if GCC_PLUGIN_LATENT_ENTROPY 338 default 1280 if (!64BIT && PARISC) 339 default 1024 if (!64BIT && !PARISC) 340 default 2048 if 64BIT 341 help 342 Tell gcc to warn at build time for stack frames larger than this. 343 Setting this too low will cause a lot of warnings. 344 Setting it to 0 disables the warning. 345 346config STRIP_ASM_SYMS 347 bool "Strip assembler-generated symbols during link" 348 default n 349 help 350 Strip internal assembler-generated symbols during a link (symbols 351 that look like '.Lxxx') so they don't pollute the output of 352 get_wchan() and suchlike. 353 354config READABLE_ASM 355 bool "Generate readable assembler code" 356 depends on DEBUG_KERNEL 357 help 358 Disable some compiler optimizations that tend to generate human unreadable 359 assembler output. This may make the kernel slightly slower, but it helps 360 to keep kernel developers who have to stare a lot at assembler listings 361 sane. 362 363config HEADERS_INSTALL 364 bool "Install uapi headers to usr/include" 365 depends on !UML 366 help 367 This option will install uapi headers (headers exported to user-space) 368 into the usr/include directory for use during the kernel build. 369 This is unneeded for building the kernel itself, but needed for some 370 user-space program samples. It is also needed by some features such 371 as uapi header sanity checks. 372 373config DEBUG_SECTION_MISMATCH 374 bool "Enable full Section mismatch analysis" 375 help 376 The section mismatch analysis checks if there are illegal 377 references from one section to another section. 378 During linktime or runtime, some sections are dropped; 379 any use of code/data previously in these sections would 380 most likely result in an oops. 381 In the code, functions and variables are annotated with 382 __init,, etc. (see the full list in include/linux/init.h), 383 which results in the code/data being placed in specific sections. 384 The section mismatch analysis is always performed after a full 385 kernel build, and enabling this option causes the following 386 additional step to occur: 387 - Add the option -fno-inline-functions-called-once to gcc commands. 388 When inlining a function annotated with __init in a non-init 389 function, we would lose the section information and thus 390 the analysis would not catch the illegal reference. 391 This option tells gcc to inline less (but it does result in 392 a larger kernel). 393 394config SECTION_MISMATCH_WARN_ONLY 395 bool "Make section mismatch errors non-fatal" 396 default y 397 help 398 If you say N here, the build process will fail if there are any 399 section mismatch, instead of just throwing warnings. 400 401 If unsure, say Y. 402 403config DEBUG_FORCE_FUNCTION_ALIGN_32B 404 bool "Force all function address 32B aligned" if EXPERT 405 help 406 There are cases that a commit from one domain changes the function 407 address alignment of other domains, and cause magic performance 408 bump (regression or improvement). Enable this option will help to 409 verify if the bump is caused by function alignment changes, while 410 it will slightly increase the kernel size and affect icache usage. 411 412 It is mainly for debug and performance tuning use. 413 414# 415# Select this config option from the architecture Kconfig, if it 416# is preferred to always offer frame pointers as a config 417# option on the architecture (regardless of KERNEL_DEBUG): 418# 419config ARCH_WANT_FRAME_POINTERS 420 bool 421 422config FRAME_POINTER 423 bool "Compile the kernel with frame pointers" 424 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS 425 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 426 help 427 If you say Y here the resulting kernel image will be slightly 428 larger and slower, but it gives very useful debugging information 429 in case of kernel bugs. (precise oopses/stacktraces/warnings) 430 431config STACK_VALIDATION 432 bool "Compile-time stack metadata validation" 433 depends on HAVE_STACK_VALIDATION 434 default n 435 help 436 Add compile-time checks to validate stack metadata, including frame 437 pointers (if CONFIG_FRAME_POINTER is enabled). This helps ensure 438 that runtime stack traces are more reliable. 439 440 This is also a prerequisite for generation of ORC unwind data, which 441 is needed for CONFIG_UNWINDER_ORC. 442 443 For more information, see 444 tools/objtool/Documentation/stack-validation.txt. 445 446config VMLINUX_VALIDATION 447 bool 448 depends on STACK_VALIDATION && DEBUG_ENTRY && !PARAVIRT 449 default y 450 451config VMLINUX_MAP 452 bool "Generate vmlinux.map file when linking" 453 depends on EXPERT 454 help 455 Selecting this option will pass "-Map=vmlinux.map" to ld 456 when linking vmlinux. That file can be useful for verifying 457 and debugging magic section games, and for seeing which 458 pieces of code get eliminated with 459 CONFIG_LD_DEAD_CODE_DATA_ELIMINATION. 460 461config DEBUG_FORCE_WEAK_PER_CPU 462 bool "Force weak per-cpu definitions" 463 depends on DEBUG_KERNEL 464 help 465 s390 and alpha require percpu variables in modules to be 466 defined weak to work around addressing range issue which 467 puts the following two restrictions on percpu variable 468 definitions. 469 470 1. percpu symbols must be unique whether static or not 471 2. percpu variables can't be defined inside a function 472 473 To ensure that generic code follows the above rules, this 474 option forces all percpu variables to be defined as weak. 475 476endmenu # "Compiler options" 477 478menu "Generic Kernel Debugging Instruments" 479 480config MAGIC_SYSRQ 481 bool "Magic SysRq key" 482 depends on !UML 483 help 484 If you say Y here, you will have some control over the system even 485 if the system crashes for example during kernel debugging (e.g., you 486 will be able to flush the buffer cache to disk, reboot the system 487 immediately or dump some status information). This is accomplished 488 by pressing various keys while holding SysRq (Alt+PrintScreen). It 489 also works on a serial console (on PC hardware at least), if you 490 send a BREAK and then within 5 seconds a command keypress. The 491 keys are documented in <file:Documentation/admin-guide/sysrq.rst>. 492 Don't say Y unless you really know what this hack does. 493 494config MAGIC_SYSRQ_DEFAULT_ENABLE 495 hex "Enable magic SysRq key functions by default" 496 depends on MAGIC_SYSRQ 497 default 0x1 498 help 499 Specifies which SysRq key functions are enabled by default. 500 This may be set to 1 or 0 to enable or disable them all, or 501 to a bitmask as described in Documentation/admin-guide/sysrq.rst. 502 503config MAGIC_SYSRQ_SERIAL 504 bool "Enable magic SysRq key over serial" 505 depends on MAGIC_SYSRQ 506 default y 507 help 508 Many embedded boards have a disconnected TTL level serial which can 509 generate some garbage that can lead to spurious false sysrq detects. 510 This option allows you to decide whether you want to enable the 511 magic SysRq key. 512 513config MAGIC_SYSRQ_SERIAL_SEQUENCE 514 string "Char sequence that enables magic SysRq over serial" 515 depends on MAGIC_SYSRQ_SERIAL 516 default "" 517 help 518 Specifies a sequence of characters that can follow BREAK to enable 519 SysRq on a serial console. 520 521 If unsure, leave an empty string and the option will not be enabled. 522 523config DEBUG_FS 524 bool "Debug Filesystem" 525 help 526 debugfs is a virtual file system that kernel developers use to put 527 debugging files into. Enable this option to be able to read and 528 write to these files. 529 530 For detailed documentation on the debugfs API, see 531 Documentation/filesystems/. 532 533 If unsure, say N. 534 535choice 536 prompt "Debugfs default access" 537 depends on DEBUG_FS 538 default DEBUG_FS_ALLOW_ALL 539 help 540 This selects the default access restrictions for debugfs. 541 It can be overridden with kernel command line option 542 debugfs=[on,no-mount,off]. The restrictions apply for API access 543 and filesystem registration. 544 545config DEBUG_FS_ALLOW_ALL 546 bool "Access normal" 547 help 548 No restrictions apply. Both API and filesystem registration 549 is on. This is the normal default operation. 550 551config DEBUG_FS_DISALLOW_MOUNT 552 bool "Do not register debugfs as filesystem" 553 help 554 The API is open but filesystem is not loaded. Clients can still do 555 their work and read with debug tools that do not need 556 debugfs filesystem. 557 558config DEBUG_FS_ALLOW_NONE 559 bool "No access" 560 help 561 Access is off. Clients get -PERM when trying to create nodes in 562 debugfs tree and debugfs is not registered as a filesystem. 563 Client can then back-off or continue without debugfs access. 564 565endchoice 566 567source "lib/Kconfig.kgdb" 568source "lib/Kconfig.ubsan" 569source "lib/Kconfig.kcsan" 570 571endmenu 572 573config DEBUG_KERNEL 574 bool "Kernel debugging" 575 help 576 Say Y here if you are developing drivers or trying to debug and 577 identify kernel problems. 578 579config DEBUG_MISC 580 bool "Miscellaneous debug code" 581 default DEBUG_KERNEL 582 depends on DEBUG_KERNEL 583 help 584 Say Y here if you need to enable miscellaneous debug code that should 585 be under a more specific debug option but isn't. 586 587 588menu "Memory Debugging" 589 590source "mm/Kconfig.debug" 591 592config DEBUG_OBJECTS 593 bool "Debug object operations" 594 depends on DEBUG_KERNEL 595 help 596 If you say Y here, additional code will be inserted into the 597 kernel to track the life time of various objects and validate 598 the operations on those objects. 599 600config DEBUG_OBJECTS_SELFTEST 601 bool "Debug objects selftest" 602 depends on DEBUG_OBJECTS 603 help 604 This enables the selftest of the object debug code. 605 606config DEBUG_OBJECTS_FREE 607 bool "Debug objects in freed memory" 608 depends on DEBUG_OBJECTS 609 help 610 This enables checks whether a k/v free operation frees an area 611 which contains an object which has not been deactivated 612 properly. This can make kmalloc/kfree-intensive workloads 613 much slower. 614 615config DEBUG_OBJECTS_TIMERS 616 bool "Debug timer objects" 617 depends on DEBUG_OBJECTS 618 help 619 If you say Y here, additional code will be inserted into the 620 timer routines to track the life time of timer objects and 621 validate the timer operations. 622 623config DEBUG_OBJECTS_WORK 624 bool "Debug work objects" 625 depends on DEBUG_OBJECTS 626 help 627 If you say Y here, additional code will be inserted into the 628 work queue routines to track the life time of work objects and 629 validate the work operations. 630 631config DEBUG_OBJECTS_RCU_HEAD 632 bool "Debug RCU callbacks objects" 633 depends on DEBUG_OBJECTS 634 help 635 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 636 637config DEBUG_OBJECTS_PERCPU_COUNTER 638 bool "Debug percpu counter objects" 639 depends on DEBUG_OBJECTS 640 help 641 If you say Y here, additional code will be inserted into the 642 percpu counter routines to track the life time of percpu counter 643 objects and validate the percpu counter operations. 644 645config DEBUG_OBJECTS_ENABLE_DEFAULT 646 int "debug_objects bootup default value (0-1)" 647 range 0 1 648 default "1" 649 depends on DEBUG_OBJECTS 650 help 651 Debug objects boot parameter default value 652 653config DEBUG_SLAB 654 bool "Debug slab memory allocations" 655 depends on DEBUG_KERNEL && SLAB 656 help 657 Say Y here to have the kernel do limited verification on memory 658 allocation as well as poisoning memory on free to catch use of freed 659 memory. This can make kmalloc/kfree-intensive workloads much slower. 660 661config SLUB_DEBUG_ON 662 bool "SLUB debugging on by default" 663 depends on SLUB && SLUB_DEBUG 664 default n 665 help 666 Boot with debugging on by default. SLUB boots by default with 667 the runtime debug capabilities switched off. Enabling this is 668 equivalent to specifying the "slub_debug" parameter on boot. 669 There is no support for more fine grained debug control like 670 possible with slub_debug=xxx. SLUB debugging may be switched 671 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying 672 "slub_debug=-". 673 674config SLUB_STATS 675 default n 676 bool "Enable SLUB performance statistics" 677 depends on SLUB && SYSFS 678 help 679 SLUB statistics are useful to debug SLUBs allocation behavior in 680 order find ways to optimize the allocator. This should never be 681 enabled for production use since keeping statistics slows down 682 the allocator by a few percentage points. The slabinfo command 683 supports the determination of the most active slabs to figure 684 out which slabs are relevant to a particular load. 685 Try running: slabinfo -DA 686 687config HAVE_DEBUG_KMEMLEAK 688 bool 689 690config DEBUG_KMEMLEAK 691 bool "Kernel memory leak detector" 692 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK 693 select DEBUG_FS 694 select STACKTRACE if STACKTRACE_SUPPORT 695 select KALLSYMS 696 select CRC32 697 help 698 Say Y here if you want to enable the memory leak 699 detector. The memory allocation/freeing is traced in a way 700 similar to the Boehm's conservative garbage collector, the 701 difference being that the orphan objects are not freed but 702 only shown in /sys/kernel/debug/kmemleak. Enabling this 703 feature will introduce an overhead to memory 704 allocations. See Documentation/dev-tools/kmemleak.rst for more 705 details. 706 707 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances 708 of finding leaks due to the slab objects poisoning. 709 710 In order to access the kmemleak file, debugfs needs to be 711 mounted (usually at /sys/kernel/debug). 712 713config DEBUG_KMEMLEAK_MEM_POOL_SIZE 714 int "Kmemleak memory pool size" 715 depends on DEBUG_KMEMLEAK 716 range 200 1000000 717 default 16000 718 help 719 Kmemleak must track all the memory allocations to avoid 720 reporting false positives. Since memory may be allocated or 721 freed before kmemleak is fully initialised, use a static pool 722 of metadata objects to track such callbacks. After kmemleak is 723 fully initialised, this memory pool acts as an emergency one 724 if slab allocations fail. 725 726config DEBUG_KMEMLEAK_TEST 727 tristate "Simple test for the kernel memory leak detector" 728 depends on DEBUG_KMEMLEAK && m 729 help 730 This option enables a module that explicitly leaks memory. 731 732 If unsure, say N. 733 734config DEBUG_KMEMLEAK_DEFAULT_OFF 735 bool "Default kmemleak to off" 736 depends on DEBUG_KMEMLEAK 737 help 738 Say Y here to disable kmemleak by default. It can then be enabled 739 on the command line via kmemleak=on. 740 741config DEBUG_KMEMLEAK_AUTO_SCAN 742 bool "Enable kmemleak auto scan thread on boot up" 743 default y 744 depends on DEBUG_KMEMLEAK 745 help 746 Depending on the cpu, kmemleak scan may be cpu intensive and can 747 stall user tasks at times. This option enables/disables automatic 748 kmemleak scan at boot up. 749 750 Say N here to disable kmemleak auto scan thread to stop automatic 751 scanning. Disabling this option disables automatic reporting of 752 memory leaks. 753 754 If unsure, say Y. 755 756config DEBUG_STACK_USAGE 757 bool "Stack utilization instrumentation" 758 depends on DEBUG_KERNEL && !IA64 759 help 760 Enables the display of the minimum amount of free stack which each 761 task has ever had available in the sysrq-T and sysrq-P debug output. 762 763 This option will slow down process creation somewhat. 764 765config SCHED_STACK_END_CHECK 766 bool "Detect stack corruption on calls to schedule()" 767 depends on DEBUG_KERNEL 768 default n 769 help 770 This option checks for a stack overrun on calls to schedule(). 771 If the stack end location is found to be over written always panic as 772 the content of the corrupted region can no longer be trusted. 773 This is to ensure no erroneous behaviour occurs which could result in 774 data corruption or a sporadic crash at a later stage once the region 775 is examined. The runtime overhead introduced is minimal. 776 777config ARCH_HAS_DEBUG_VM_PGTABLE 778 bool 779 help 780 An architecture should select this when it can successfully 781 build and run DEBUG_VM_PGTABLE. 782 783config DEBUG_VM 784 bool "Debug VM" 785 depends on DEBUG_KERNEL 786 help 787 Enable this to turn on extended checks in the virtual-memory system 788 that may impact performance. 789 790 If unsure, say N. 791 792config DEBUG_VM_VMACACHE 793 bool "Debug VMA caching" 794 depends on DEBUG_VM 795 help 796 Enable this to turn on VMA caching debug information. Doing so 797 can cause significant overhead, so only enable it in non-production 798 environments. 799 800 If unsure, say N. 801 802config DEBUG_VM_RB 803 bool "Debug VM red-black trees" 804 depends on DEBUG_VM 805 help 806 Enable VM red-black tree debugging information and extra validations. 807 808 If unsure, say N. 809 810config DEBUG_VM_PGFLAGS 811 bool "Debug page-flags operations" 812 depends on DEBUG_VM 813 help 814 Enables extra validation on page flags operations. 815 816 If unsure, say N. 817 818config DEBUG_VM_PGTABLE 819 bool "Debug arch page table for semantics compliance" 820 depends on MMU 821 depends on ARCH_HAS_DEBUG_VM_PGTABLE 822 default y if DEBUG_VM 823 help 824 This option provides a debug method which can be used to test 825 architecture page table helper functions on various platforms in 826 verifying if they comply with expected generic MM semantics. This 827 will help architecture code in making sure that any changes or 828 new additions of these helpers still conform to expected 829 semantics of the generic MM. Platforms will have to opt in for 830 this through ARCH_HAS_DEBUG_VM_PGTABLE. 831 832 If unsure, say N. 833 834config ARCH_HAS_DEBUG_VIRTUAL 835 bool 836 837config DEBUG_VIRTUAL 838 bool "Debug VM translations" 839 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL 840 help 841 Enable some costly sanity checks in virtual to page code. This can 842 catch mistakes with virt_to_page() and friends. 843 844 If unsure, say N. 845 846config DEBUG_NOMMU_REGIONS 847 bool "Debug the global anon/private NOMMU mapping region tree" 848 depends on DEBUG_KERNEL && !MMU 849 help 850 This option causes the global tree of anonymous and private mapping 851 regions to be regularly checked for invalid topology. 852 853config DEBUG_MEMORY_INIT 854 bool "Debug memory initialisation" if EXPERT 855 default !EXPERT 856 help 857 Enable this for additional checks during memory initialisation. 858 The sanity checks verify aspects of the VM such as the memory model 859 and other information provided by the architecture. Verbose 860 information will be printed at KERN_DEBUG loglevel depending 861 on the mminit_loglevel= command-line option. 862 863 If unsure, say Y 864 865config MEMORY_NOTIFIER_ERROR_INJECT 866 tristate "Memory hotplug notifier error injection module" 867 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION 868 help 869 This option provides the ability to inject artificial errors to 870 memory hotplug notifier chain callbacks. It is controlled through 871 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 872 873 If the notifier call chain should be failed with some events 874 notified, write the error code to "actions/<notifier event>/error". 875 876 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 877 878 # cd /sys/kernel/debug/notifier-error-inject/memory 879 # echo -12 > actions/MEM_GOING_OFFLINE/error 880 # echo offline > /sys/devices/system/memory/memoryXXX/state 881 bash: echo: write error: Cannot allocate memory 882 883 To compile this code as a module, choose M here: the module will 884 be called memory-notifier-error-inject. 885 886 If unsure, say N. 887 888config DEBUG_PER_CPU_MAPS 889 bool "Debug access to per_cpu maps" 890 depends on DEBUG_KERNEL 891 depends on SMP 892 help 893 Say Y to verify that the per_cpu map being accessed has 894 been set up. This adds a fair amount of code to kernel memory 895 and decreases performance. 896 897 Say N if unsure. 898 899config DEBUG_KMAP_LOCAL 900 bool "Debug kmap_local temporary mappings" 901 depends on DEBUG_KERNEL && KMAP_LOCAL 902 help 903 This option enables additional error checking for the kmap_local 904 infrastructure. Disable for production use. 905 906config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 907 bool 908 909config DEBUG_KMAP_LOCAL_FORCE_MAP 910 bool "Enforce kmap_local temporary mappings" 911 depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 912 select KMAP_LOCAL 913 select DEBUG_KMAP_LOCAL 914 help 915 This option enforces temporary mappings through the kmap_local 916 mechanism for non-highmem pages and on non-highmem systems. 917 Disable this for production systems! 918 919config DEBUG_HIGHMEM 920 bool "Highmem debugging" 921 depends on DEBUG_KERNEL && HIGHMEM 922 select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 923 select DEBUG_KMAP_LOCAL 924 help 925 This option enables additional error checking for high memory 926 systems. Disable for production systems. 927 928config HAVE_DEBUG_STACKOVERFLOW 929 bool 930 931config DEBUG_STACKOVERFLOW 932 bool "Check for stack overflows" 933 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 934 help 935 Say Y here if you want to check for overflows of kernel, IRQ 936 and exception stacks (if your architecture uses them). This 937 option will show detailed messages if free stack space drops 938 below a certain limit. 939 940 These kinds of bugs usually occur when call-chains in the 941 kernel get too deep, especially when interrupts are 942 involved. 943 944 Use this in cases where you see apparently random memory 945 corruption, especially if it appears in 'struct thread_info' 946 947 If in doubt, say "N". 948 949source "lib/Kconfig.kasan" 950source "lib/Kconfig.kfence" 951 952endmenu # "Memory Debugging" 953 954config DEBUG_SHIRQ 955 bool "Debug shared IRQ handlers" 956 depends on DEBUG_KERNEL 957 help 958 Enable this to generate a spurious interrupt just before a shared 959 interrupt handler is deregistered (generating one when registering 960 is currently disabled). Drivers need to handle this correctly. Some 961 don't and need to be caught. 962 963menu "Debug Oops, Lockups and Hangs" 964 965config PANIC_ON_OOPS 966 bool "Panic on Oops" 967 help 968 Say Y here to enable the kernel to panic when it oopses. This 969 has the same effect as setting oops=panic on the kernel command 970 line. 971 972 This feature is useful to ensure that the kernel does not do 973 anything erroneous after an oops which could result in data 974 corruption or other issues. 975 976 Say N if unsure. 977 978config PANIC_ON_OOPS_VALUE 979 int 980 range 0 1 981 default 0 if !PANIC_ON_OOPS 982 default 1 if PANIC_ON_OOPS 983 984config PANIC_TIMEOUT 985 int "panic timeout" 986 default 0 987 help 988 Set the timeout value (in seconds) until a reboot occurs when 989 the kernel panics. If n = 0, then we wait forever. A timeout 990 value n > 0 will wait n seconds before rebooting, while a timeout 991 value n < 0 will reboot immediately. 992 993config LOCKUP_DETECTOR 994 bool 995 996config SOFTLOCKUP_DETECTOR 997 bool "Detect Soft Lockups" 998 depends on DEBUG_KERNEL && !S390 999 select LOCKUP_DETECTOR 1000 help 1001 Say Y here to enable the kernel to act as a watchdog to detect 1002 soft lockups. 1003 1004 Softlockups are bugs that cause the kernel to loop in kernel 1005 mode for more than 20 seconds, without giving other tasks a 1006 chance to run. The current stack trace is displayed upon 1007 detection and the system will stay locked up. 1008 1009config BOOTPARAM_SOFTLOCKUP_PANIC 1010 bool "Panic (Reboot) On Soft Lockups" 1011 depends on SOFTLOCKUP_DETECTOR 1012 help 1013 Say Y here to enable the kernel to panic on "soft lockups", 1014 which are bugs that cause the kernel to loop in kernel 1015 mode for more than 20 seconds (configurable using the watchdog_thresh 1016 sysctl), without giving other tasks a chance to run. 1017 1018 The panic can be used in combination with panic_timeout, 1019 to cause the system to reboot automatically after a 1020 lockup has been detected. This feature is useful for 1021 high-availability systems that have uptime guarantees and 1022 where a lockup must be resolved ASAP. 1023 1024 Say N if unsure. 1025 1026config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE 1027 int 1028 depends on SOFTLOCKUP_DETECTOR 1029 range 0 1 1030 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC 1031 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC 1032 1033config HARDLOCKUP_DETECTOR_PERF 1034 bool 1035 select SOFTLOCKUP_DETECTOR 1036 1037# 1038# Enables a timestamp based low pass filter to compensate for perf based 1039# hard lockup detection which runs too fast due to turbo modes. 1040# 1041config HARDLOCKUP_CHECK_TIMESTAMP 1042 bool 1043 1044# 1045# arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard 1046# lockup detector rather than the perf based detector. 1047# 1048config HARDLOCKUP_DETECTOR 1049 bool "Detect Hard Lockups" 1050 depends on DEBUG_KERNEL && !S390 1051 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH 1052 select LOCKUP_DETECTOR 1053 select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF 1054 select HARDLOCKUP_DETECTOR_ARCH if HAVE_HARDLOCKUP_DETECTOR_ARCH 1055 help 1056 Say Y here to enable the kernel to act as a watchdog to detect 1057 hard lockups. 1058 1059 Hardlockups are bugs that cause the CPU to loop in kernel mode 1060 for more than 10 seconds, without letting other interrupts have a 1061 chance to run. The current stack trace is displayed upon detection 1062 and the system will stay locked up. 1063 1064config BOOTPARAM_HARDLOCKUP_PANIC 1065 bool "Panic (Reboot) On Hard Lockups" 1066 depends on HARDLOCKUP_DETECTOR 1067 help 1068 Say Y here to enable the kernel to panic on "hard lockups", 1069 which are bugs that cause the kernel to loop in kernel 1070 mode with interrupts disabled for more than 10 seconds (configurable 1071 using the watchdog_thresh sysctl). 1072 1073 Say N if unsure. 1074 1075config BOOTPARAM_HARDLOCKUP_PANIC_VALUE 1076 int 1077 depends on HARDLOCKUP_DETECTOR 1078 range 0 1 1079 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC 1080 default 1 if BOOTPARAM_HARDLOCKUP_PANIC 1081 1082config DETECT_HUNG_TASK 1083 bool "Detect Hung Tasks" 1084 depends on DEBUG_KERNEL 1085 default SOFTLOCKUP_DETECTOR 1086 help 1087 Say Y here to enable the kernel to detect "hung tasks", 1088 which are bugs that cause the task to be stuck in 1089 uninterruptible "D" state indefinitely. 1090 1091 When a hung task is detected, the kernel will print the 1092 current stack trace (which you should report), but the 1093 task will stay in uninterruptible state. If lockdep is 1094 enabled then all held locks will also be reported. This 1095 feature has negligible overhead. 1096 1097config DEFAULT_HUNG_TASK_TIMEOUT 1098 int "Default timeout for hung task detection (in seconds)" 1099 depends on DETECT_HUNG_TASK 1100 default 120 1101 help 1102 This option controls the default timeout (in seconds) used 1103 to determine when a task has become non-responsive and should 1104 be considered hung. 1105 1106 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 1107 sysctl or by writing a value to 1108 /proc/sys/kernel/hung_task_timeout_secs. 1109 1110 A timeout of 0 disables the check. The default is two minutes. 1111 Keeping the default should be fine in most cases. 1112 1113config BOOTPARAM_HUNG_TASK_PANIC 1114 bool "Panic (Reboot) On Hung Tasks" 1115 depends on DETECT_HUNG_TASK 1116 help 1117 Say Y here to enable the kernel to panic on "hung tasks", 1118 which are bugs that cause the kernel to leave a task stuck 1119 in uninterruptible "D" state. 1120 1121 The panic can be used in combination with panic_timeout, 1122 to cause the system to reboot automatically after a 1123 hung task has been detected. This feature is useful for 1124 high-availability systems that have uptime guarantees and 1125 where a hung tasks must be resolved ASAP. 1126 1127 Say N if unsure. 1128 1129config BOOTPARAM_HUNG_TASK_PANIC_VALUE 1130 int 1131 depends on DETECT_HUNG_TASK 1132 range 0 1 1133 default 0 if !BOOTPARAM_HUNG_TASK_PANIC 1134 default 1 if BOOTPARAM_HUNG_TASK_PANIC 1135 1136config WQ_WATCHDOG 1137 bool "Detect Workqueue Stalls" 1138 depends on DEBUG_KERNEL 1139 help 1140 Say Y here to enable stall detection on workqueues. If a 1141 worker pool doesn't make forward progress on a pending work 1142 item for over a given amount of time, 30s by default, a 1143 warning message is printed along with dump of workqueue 1144 state. This can be configured through kernel parameter 1145 "workqueue.watchdog_thresh" and its sysfs counterpart. 1146 1147config TEST_LOCKUP 1148 tristate "Test module to generate lockups" 1149 depends on m 1150 help 1151 This builds the "test_lockup" module that helps to make sure 1152 that watchdogs and lockup detectors are working properly. 1153 1154 Depending on module parameters it could emulate soft or hard 1155 lockup, "hung task", or locking arbitrary lock for a long time. 1156 Also it could generate series of lockups with cooling-down periods. 1157 1158 If unsure, say N. 1159 1160endmenu # "Debug lockups and hangs" 1161 1162menu "Scheduler Debugging" 1163 1164config SCHED_DEBUG 1165 bool "Collect scheduler debugging info" 1166 depends on DEBUG_KERNEL && PROC_FS 1167 default y 1168 help 1169 If you say Y here, the /proc/sched_debug file will be provided 1170 that can help debug the scheduler. The runtime overhead of this 1171 option is minimal. 1172 1173config SCHED_INFO 1174 bool 1175 default n 1176 1177config SCHEDSTATS 1178 bool "Collect scheduler statistics" 1179 depends on DEBUG_KERNEL && PROC_FS 1180 select SCHED_INFO 1181 help 1182 If you say Y here, additional code will be inserted into the 1183 scheduler and related routines to collect statistics about 1184 scheduler behavior and provide them in /proc/schedstat. These 1185 stats may be useful for both tuning and debugging the scheduler 1186 If you aren't debugging the scheduler or trying to tune a specific 1187 application, you can say N to avoid the very slight overhead 1188 this adds. 1189 1190endmenu 1191 1192config DEBUG_TIMEKEEPING 1193 bool "Enable extra timekeeping sanity checking" 1194 help 1195 This option will enable additional timekeeping sanity checks 1196 which may be helpful when diagnosing issues where timekeeping 1197 problems are suspected. 1198 1199 This may include checks in the timekeeping hotpaths, so this 1200 option may have a (very small) performance impact to some 1201 workloads. 1202 1203 If unsure, say N. 1204 1205config DEBUG_PREEMPT 1206 bool "Debug preemptible kernel" 1207 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1208 default y 1209 help 1210 If you say Y here then the kernel will use a debug variant of the 1211 commonly used smp_processor_id() function and will print warnings 1212 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1213 will detect preemption count underflows. 1214 1215menu "Lock Debugging (spinlocks, mutexes, etc...)" 1216 1217config LOCK_DEBUGGING_SUPPORT 1218 bool 1219 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1220 default y 1221 1222config PROVE_LOCKING 1223 bool "Lock debugging: prove locking correctness" 1224 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1225 select LOCKDEP 1226 select DEBUG_SPINLOCK 1227 select DEBUG_MUTEXES 1228 select DEBUG_RT_MUTEXES if RT_MUTEXES 1229 select DEBUG_RWSEMS 1230 select DEBUG_WW_MUTEX_SLOWPATH 1231 select DEBUG_LOCK_ALLOC 1232 select PREEMPT_COUNT if !ARCH_NO_PREEMPT 1233 select TRACE_IRQFLAGS 1234 default n 1235 help 1236 This feature enables the kernel to prove that all locking 1237 that occurs in the kernel runtime is mathematically 1238 correct: that under no circumstance could an arbitrary (and 1239 not yet triggered) combination of observed locking 1240 sequences (on an arbitrary number of CPUs, running an 1241 arbitrary number of tasks and interrupt contexts) cause a 1242 deadlock. 1243 1244 In short, this feature enables the kernel to report locking 1245 related deadlocks before they actually occur. 1246 1247 The proof does not depend on how hard and complex a 1248 deadlock scenario would be to trigger: how many 1249 participant CPUs, tasks and irq-contexts would be needed 1250 for it to trigger. The proof also does not depend on 1251 timing: if a race and a resulting deadlock is possible 1252 theoretically (no matter how unlikely the race scenario 1253 is), it will be proven so and will immediately be 1254 reported by the kernel (once the event is observed that 1255 makes the deadlock theoretically possible). 1256 1257 If a deadlock is impossible (i.e. the locking rules, as 1258 observed by the kernel, are mathematically correct), the 1259 kernel reports nothing. 1260 1261 NOTE: this feature can also be enabled for rwlocks, mutexes 1262 and rwsems - in which case all dependencies between these 1263 different locking variants are observed and mapped too, and 1264 the proof of observed correctness is also maintained for an 1265 arbitrary combination of these separate locking variants. 1266 1267 For more details, see Documentation/locking/lockdep-design.rst. 1268 1269config PROVE_RAW_LOCK_NESTING 1270 bool "Enable raw_spinlock - spinlock nesting checks" 1271 depends on PROVE_LOCKING 1272 default n 1273 help 1274 Enable the raw_spinlock vs. spinlock nesting checks which ensure 1275 that the lock nesting rules for PREEMPT_RT enabled kernels are 1276 not violated. 1277 1278 NOTE: There are known nesting problems. So if you enable this 1279 option expect lockdep splats until these problems have been fully 1280 addressed which is work in progress. This config switch allows to 1281 identify and analyze these problems. It will be removed and the 1282 check permanentely enabled once the main issues have been fixed. 1283 1284 If unsure, select N. 1285 1286config LOCK_STAT 1287 bool "Lock usage statistics" 1288 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1289 select LOCKDEP 1290 select DEBUG_SPINLOCK 1291 select DEBUG_MUTEXES 1292 select DEBUG_RT_MUTEXES if RT_MUTEXES 1293 select DEBUG_LOCK_ALLOC 1294 default n 1295 help 1296 This feature enables tracking lock contention points 1297 1298 For more details, see Documentation/locking/lockstat.rst 1299 1300 This also enables lock events required by "perf lock", 1301 subcommand of perf. 1302 If you want to use "perf lock", you also need to turn on 1303 CONFIG_EVENT_TRACING. 1304 1305 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1306 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1307 1308config DEBUG_RT_MUTEXES 1309 bool "RT Mutex debugging, deadlock detection" 1310 depends on DEBUG_KERNEL && RT_MUTEXES 1311 help 1312 This allows rt mutex semantics violations and rt mutex related 1313 deadlocks (lockups) to be detected and reported automatically. 1314 1315config DEBUG_SPINLOCK 1316 bool "Spinlock and rw-lock debugging: basic checks" 1317 depends on DEBUG_KERNEL 1318 select UNINLINE_SPIN_UNLOCK 1319 help 1320 Say Y here and build SMP to catch missing spinlock initialization 1321 and certain other kinds of spinlock errors commonly made. This is 1322 best used in conjunction with the NMI watchdog so that spinlock 1323 deadlocks are also debuggable. 1324 1325config DEBUG_MUTEXES 1326 bool "Mutex debugging: basic checks" 1327 depends on DEBUG_KERNEL 1328 help 1329 This feature allows mutex semantics violations to be detected and 1330 reported. 1331 1332config DEBUG_WW_MUTEX_SLOWPATH 1333 bool "Wait/wound mutex debugging: Slowpath testing" 1334 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1335 select DEBUG_LOCK_ALLOC 1336 select DEBUG_SPINLOCK 1337 select DEBUG_MUTEXES 1338 help 1339 This feature enables slowpath testing for w/w mutex users by 1340 injecting additional -EDEADLK wound/backoff cases. Together with 1341 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1342 will test all possible w/w mutex interface abuse with the 1343 exception of simply not acquiring all the required locks. 1344 Note that this feature can introduce significant overhead, so 1345 it really should not be enabled in a production or distro kernel, 1346 even a debug kernel. If you are a driver writer, enable it. If 1347 you are a distro, do not. 1348 1349config DEBUG_RWSEMS 1350 bool "RW Semaphore debugging: basic checks" 1351 depends on DEBUG_KERNEL 1352 help 1353 This debugging feature allows mismatched rw semaphore locks 1354 and unlocks to be detected and reported. 1355 1356config DEBUG_LOCK_ALLOC 1357 bool "Lock debugging: detect incorrect freeing of live locks" 1358 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1359 select DEBUG_SPINLOCK 1360 select DEBUG_MUTEXES 1361 select DEBUG_RT_MUTEXES if RT_MUTEXES 1362 select LOCKDEP 1363 help 1364 This feature will check whether any held lock (spinlock, rwlock, 1365 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1366 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1367 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1368 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1369 held during task exit. 1370 1371config LOCKDEP 1372 bool 1373 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1374 select STACKTRACE 1375 select KALLSYMS 1376 select KALLSYMS_ALL 1377 1378config LOCKDEP_SMALL 1379 bool 1380 1381config LOCKDEP_BITS 1382 int "Bitsize for MAX_LOCKDEP_ENTRIES" 1383 depends on LOCKDEP && !LOCKDEP_SMALL 1384 range 10 30 1385 default 15 1386 help 1387 Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message. 1388 1389config LOCKDEP_CHAINS_BITS 1390 int "Bitsize for MAX_LOCKDEP_CHAINS" 1391 depends on LOCKDEP && !LOCKDEP_SMALL 1392 range 10 30 1393 default 16 1394 help 1395 Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message. 1396 1397config LOCKDEP_STACK_TRACE_BITS 1398 int "Bitsize for MAX_STACK_TRACE_ENTRIES" 1399 depends on LOCKDEP && !LOCKDEP_SMALL 1400 range 10 30 1401 default 19 1402 help 1403 Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message. 1404 1405config LOCKDEP_STACK_TRACE_HASH_BITS 1406 int "Bitsize for STACK_TRACE_HASH_SIZE" 1407 depends on LOCKDEP && !LOCKDEP_SMALL 1408 range 10 30 1409 default 14 1410 help 1411 Try increasing this value if you need large MAX_STACK_TRACE_ENTRIES. 1412 1413config LOCKDEP_CIRCULAR_QUEUE_BITS 1414 int "Bitsize for elements in circular_queue struct" 1415 depends on LOCKDEP 1416 range 10 30 1417 default 12 1418 help 1419 Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure. 1420 1421config DEBUG_LOCKDEP 1422 bool "Lock dependency engine debugging" 1423 depends on DEBUG_KERNEL && LOCKDEP 1424 select DEBUG_IRQFLAGS 1425 help 1426 If you say Y here, the lock dependency engine will do 1427 additional runtime checks to debug itself, at the price 1428 of more runtime overhead. 1429 1430config DEBUG_ATOMIC_SLEEP 1431 bool "Sleep inside atomic section checking" 1432 select PREEMPT_COUNT 1433 depends on DEBUG_KERNEL 1434 depends on !ARCH_NO_PREEMPT 1435 help 1436 If you say Y here, various routines which may sleep will become very 1437 noisy if they are called inside atomic sections: when a spinlock is 1438 held, inside an rcu read side critical section, inside preempt disabled 1439 sections, inside an interrupt, etc... 1440 1441config DEBUG_LOCKING_API_SELFTESTS 1442 bool "Locking API boot-time self-tests" 1443 depends on DEBUG_KERNEL 1444 help 1445 Say Y here if you want the kernel to run a short self-test during 1446 bootup. The self-test checks whether common types of locking bugs 1447 are detected by debugging mechanisms or not. (if you disable 1448 lock debugging then those bugs wont be detected of course.) 1449 The following locking APIs are covered: spinlocks, rwlocks, 1450 mutexes and rwsems. 1451 1452config LOCK_TORTURE_TEST 1453 tristate "torture tests for locking" 1454 depends on DEBUG_KERNEL 1455 select TORTURE_TEST 1456 help 1457 This option provides a kernel module that runs torture tests 1458 on kernel locking primitives. The kernel module may be built 1459 after the fact on the running kernel to be tested, if desired. 1460 1461 Say Y here if you want kernel locking-primitive torture tests 1462 to be built into the kernel. 1463 Say M if you want these torture tests to build as a module. 1464 Say N if you are unsure. 1465 1466config WW_MUTEX_SELFTEST 1467 tristate "Wait/wound mutex selftests" 1468 help 1469 This option provides a kernel module that runs tests on the 1470 on the struct ww_mutex locking API. 1471 1472 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1473 with this test harness. 1474 1475 Say M if you want these self tests to build as a module. 1476 Say N if you are unsure. 1477 1478config SCF_TORTURE_TEST 1479 tristate "torture tests for smp_call_function*()" 1480 depends on DEBUG_KERNEL 1481 select TORTURE_TEST 1482 help 1483 This option provides a kernel module that runs torture tests 1484 on the smp_call_function() family of primitives. The kernel 1485 module may be built after the fact on the running kernel to 1486 be tested, if desired. 1487 1488config CSD_LOCK_WAIT_DEBUG 1489 bool "Debugging for csd_lock_wait(), called from smp_call_function*()" 1490 depends on DEBUG_KERNEL 1491 depends on 64BIT 1492 default n 1493 help 1494 This option enables debug prints when CPUs are slow to respond 1495 to the smp_call_function*() IPI wrappers. These debug prints 1496 include the IPI handler function currently executing (if any) 1497 and relevant stack traces. 1498 1499endmenu # lock debugging 1500 1501config TRACE_IRQFLAGS 1502 depends on TRACE_IRQFLAGS_SUPPORT 1503 bool 1504 help 1505 Enables hooks to interrupt enabling and disabling for 1506 either tracing or lock debugging. 1507 1508config TRACE_IRQFLAGS_NMI 1509 def_bool y 1510 depends on TRACE_IRQFLAGS 1511 depends on TRACE_IRQFLAGS_NMI_SUPPORT 1512 1513config DEBUG_IRQFLAGS 1514 bool "Debug IRQ flag manipulation" 1515 help 1516 Enables checks for potentially unsafe enabling or disabling of 1517 interrupts, such as calling raw_local_irq_restore() when interrupts 1518 are enabled. 1519 1520config STACKTRACE 1521 bool "Stack backtrace support" 1522 depends on STACKTRACE_SUPPORT 1523 help 1524 This option causes the kernel to create a /proc/pid/stack for 1525 every process, showing its current stack trace. 1526 It is also used by various kernel debugging features that require 1527 stack trace generation. 1528 1529config WARN_ALL_UNSEEDED_RANDOM 1530 bool "Warn for all uses of unseeded randomness" 1531 default n 1532 help 1533 Some parts of the kernel contain bugs relating to their use of 1534 cryptographically secure random numbers before it's actually possible 1535 to generate those numbers securely. This setting ensures that these 1536 flaws don't go unnoticed, by enabling a message, should this ever 1537 occur. This will allow people with obscure setups to know when things 1538 are going wrong, so that they might contact developers about fixing 1539 it. 1540 1541 Unfortunately, on some models of some architectures getting 1542 a fully seeded CRNG is extremely difficult, and so this can 1543 result in dmesg getting spammed for a surprisingly long 1544 time. This is really bad from a security perspective, and 1545 so architecture maintainers really need to do what they can 1546 to get the CRNG seeded sooner after the system is booted. 1547 However, since users cannot do anything actionable to 1548 address this, by default the kernel will issue only a single 1549 warning for the first use of unseeded randomness. 1550 1551 Say Y here if you want to receive warnings for all uses of 1552 unseeded randomness. This will be of use primarily for 1553 those developers interested in improving the security of 1554 Linux kernels running on their architecture (or 1555 subarchitecture). 1556 1557config DEBUG_KOBJECT 1558 bool "kobject debugging" 1559 depends on DEBUG_KERNEL 1560 help 1561 If you say Y here, some extra kobject debugging messages will be sent 1562 to the syslog. 1563 1564config DEBUG_KOBJECT_RELEASE 1565 bool "kobject release debugging" 1566 depends on DEBUG_OBJECTS_TIMERS 1567 help 1568 kobjects are reference counted objects. This means that their 1569 last reference count put is not predictable, and the kobject can 1570 live on past the point at which a driver decides to drop it's 1571 initial reference to the kobject gained on allocation. An 1572 example of this would be a struct device which has just been 1573 unregistered. 1574 1575 However, some buggy drivers assume that after such an operation, 1576 the memory backing the kobject can be immediately freed. This 1577 goes completely against the principles of a refcounted object. 1578 1579 If you say Y here, the kernel will delay the release of kobjects 1580 on the last reference count to improve the visibility of this 1581 kind of kobject release bug. 1582 1583config HAVE_DEBUG_BUGVERBOSE 1584 bool 1585 1586menu "Debug kernel data structures" 1587 1588config DEBUG_LIST 1589 bool "Debug linked list manipulation" 1590 depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION 1591 help 1592 Enable this to turn on extended checks in the linked-list 1593 walking routines. 1594 1595 If unsure, say N. 1596 1597config DEBUG_PLIST 1598 bool "Debug priority linked list manipulation" 1599 depends on DEBUG_KERNEL 1600 help 1601 Enable this to turn on extended checks in the priority-ordered 1602 linked-list (plist) walking routines. This checks the entire 1603 list multiple times during each manipulation. 1604 1605 If unsure, say N. 1606 1607config DEBUG_SG 1608 bool "Debug SG table operations" 1609 depends on DEBUG_KERNEL 1610 help 1611 Enable this to turn on checks on scatter-gather tables. This can 1612 help find problems with drivers that do not properly initialize 1613 their sg tables. 1614 1615 If unsure, say N. 1616 1617config DEBUG_NOTIFIERS 1618 bool "Debug notifier call chains" 1619 depends on DEBUG_KERNEL 1620 help 1621 Enable this to turn on sanity checking for notifier call chains. 1622 This is most useful for kernel developers to make sure that 1623 modules properly unregister themselves from notifier chains. 1624 This is a relatively cheap check but if you care about maximum 1625 performance, say N. 1626 1627config BUG_ON_DATA_CORRUPTION 1628 bool "Trigger a BUG when data corruption is detected" 1629 select DEBUG_LIST 1630 help 1631 Select this option if the kernel should BUG when it encounters 1632 data corruption in kernel memory structures when they get checked 1633 for validity. 1634 1635 If unsure, say N. 1636 1637endmenu 1638 1639config DEBUG_CREDENTIALS 1640 bool "Debug credential management" 1641 depends on DEBUG_KERNEL 1642 help 1643 Enable this to turn on some debug checking for credential 1644 management. The additional code keeps track of the number of 1645 pointers from task_structs to any given cred struct, and checks to 1646 see that this number never exceeds the usage count of the cred 1647 struct. 1648 1649 Furthermore, if SELinux is enabled, this also checks that the 1650 security pointer in the cred struct is never seen to be invalid. 1651 1652 If unsure, say N. 1653 1654source "kernel/rcu/Kconfig.debug" 1655 1656config DEBUG_WQ_FORCE_RR_CPU 1657 bool "Force round-robin CPU selection for unbound work items" 1658 depends on DEBUG_KERNEL 1659 default n 1660 help 1661 Workqueue used to implicitly guarantee that work items queued 1662 without explicit CPU specified are put on the local CPU. This 1663 guarantee is no longer true and while local CPU is still 1664 preferred work items may be put on foreign CPUs. Kernel 1665 parameter "workqueue.debug_force_rr_cpu" is added to force 1666 round-robin CPU selection to flush out usages which depend on the 1667 now broken guarantee. This config option enables the debug 1668 feature by default. When enabled, memory and cache locality will 1669 be impacted. 1670 1671config DEBUG_BLOCK_EXT_DEVT 1672 bool "Force extended block device numbers and spread them" 1673 depends on DEBUG_KERNEL 1674 depends on BLOCK 1675 default n 1676 help 1677 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON 1678 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT 1679 YOU ARE DOING. Distros, please enable this and fix whatever 1680 is broken. 1681 1682 Conventionally, block device numbers are allocated from 1683 predetermined contiguous area. However, extended block area 1684 may introduce non-contiguous block device numbers. This 1685 option forces most block device numbers to be allocated from 1686 the extended space and spreads them to discover kernel or 1687 userland code paths which assume predetermined contiguous 1688 device number allocation. 1689 1690 Note that turning on this debug option shuffles all the 1691 device numbers for all IDE and SCSI devices including libata 1692 ones, so root partition specified using device number 1693 directly (via rdev or root=MAJ:MIN) won't work anymore. 1694 Textual device names (root=/dev/sdXn) will continue to work. 1695 1696 Say N if you are unsure. 1697 1698config CPU_HOTPLUG_STATE_CONTROL 1699 bool "Enable CPU hotplug state control" 1700 depends on DEBUG_KERNEL 1701 depends on HOTPLUG_CPU 1702 default n 1703 help 1704 Allows to write steps between "offline" and "online" to the CPUs 1705 sysfs target file so states can be stepped granular. This is a debug 1706 option for now as the hotplug machinery cannot be stopped and 1707 restarted at arbitrary points yet. 1708 1709 Say N if your are unsure. 1710 1711config LATENCYTOP 1712 bool "Latency measuring infrastructure" 1713 depends on DEBUG_KERNEL 1714 depends on STACKTRACE_SUPPORT 1715 depends on PROC_FS 1716 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 1717 select KALLSYMS 1718 select KALLSYMS_ALL 1719 select STACKTRACE 1720 select SCHEDSTATS 1721 help 1722 Enable this option if you want to use the LatencyTOP tool 1723 to find out which userspace is blocking on what kernel operations. 1724 1725source "kernel/trace/Kconfig" 1726 1727config PROVIDE_OHCI1394_DMA_INIT 1728 bool "Remote debugging over FireWire early on boot" 1729 depends on PCI && X86 1730 help 1731 If you want to debug problems which hang or crash the kernel early 1732 on boot and the crashing machine has a FireWire port, you can use 1733 this feature to remotely access the memory of the crashed machine 1734 over FireWire. This employs remote DMA as part of the OHCI1394 1735 specification which is now the standard for FireWire controllers. 1736 1737 With remote DMA, you can monitor the printk buffer remotely using 1738 firescope and access all memory below 4GB using fireproxy from gdb. 1739 Even controlling a kernel debugger is possible using remote DMA. 1740 1741 Usage: 1742 1743 If ohci1394_dma=early is used as boot parameter, it will initialize 1744 all OHCI1394 controllers which are found in the PCI config space. 1745 1746 As all changes to the FireWire bus such as enabling and disabling 1747 devices cause a bus reset and thereby disable remote DMA for all 1748 devices, be sure to have the cable plugged and FireWire enabled on 1749 the debugging host before booting the debug target for debugging. 1750 1751 This code (~1k) is freed after boot. By then, the firewire stack 1752 in charge of the OHCI-1394 controllers should be used instead. 1753 1754 See Documentation/core-api/debugging-via-ohci1394.rst for more information. 1755 1756source "samples/Kconfig" 1757 1758config ARCH_HAS_DEVMEM_IS_ALLOWED 1759 bool 1760 1761config STRICT_DEVMEM 1762 bool "Filter access to /dev/mem" 1763 depends on MMU && DEVMEM 1764 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED 1765 default y if PPC || X86 || ARM64 1766 help 1767 If this option is disabled, you allow userspace (root) access to all 1768 of memory, including kernel and userspace memory. Accidental 1769 access to this is obviously disastrous, but specific access can 1770 be used by people debugging the kernel. Note that with PAT support 1771 enabled, even in this case there are restrictions on /dev/mem 1772 use due to the cache aliasing requirements. 1773 1774 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 1775 file only allows userspace access to PCI space and the BIOS code and 1776 data regions. This is sufficient for dosemu and X and all common 1777 users of /dev/mem. 1778 1779 If in doubt, say Y. 1780 1781config IO_STRICT_DEVMEM 1782 bool "Filter I/O access to /dev/mem" 1783 depends on STRICT_DEVMEM 1784 help 1785 If this option is disabled, you allow userspace (root) access to all 1786 io-memory regardless of whether a driver is actively using that 1787 range. Accidental access to this is obviously disastrous, but 1788 specific access can be used by people debugging kernel drivers. 1789 1790 If this option is switched on, the /dev/mem file only allows 1791 userspace access to *idle* io-memory ranges (see /proc/iomem) This 1792 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 1793 if the driver using a given range cannot be disabled. 1794 1795 If in doubt, say Y. 1796 1797menu "$(SRCARCH) Debugging" 1798 1799source "arch/$(SRCARCH)/Kconfig.debug" 1800 1801endmenu 1802 1803menu "Kernel Testing and Coverage" 1804 1805source "lib/kunit/Kconfig" 1806 1807config NOTIFIER_ERROR_INJECTION 1808 tristate "Notifier error injection" 1809 depends on DEBUG_KERNEL 1810 select DEBUG_FS 1811 help 1812 This option provides the ability to inject artificial errors to 1813 specified notifier chain callbacks. It is useful to test the error 1814 handling of notifier call chain failures. 1815 1816 Say N if unsure. 1817 1818config PM_NOTIFIER_ERROR_INJECT 1819 tristate "PM notifier error injection module" 1820 depends on PM && NOTIFIER_ERROR_INJECTION 1821 default m if PM_DEBUG 1822 help 1823 This option provides the ability to inject artificial errors to 1824 PM notifier chain callbacks. It is controlled through debugfs 1825 interface /sys/kernel/debug/notifier-error-inject/pm 1826 1827 If the notifier call chain should be failed with some events 1828 notified, write the error code to "actions/<notifier event>/error". 1829 1830 Example: Inject PM suspend error (-12 = -ENOMEM) 1831 1832 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1833 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1834 # echo mem > /sys/power/state 1835 bash: echo: write error: Cannot allocate memory 1836 1837 To compile this code as a module, choose M here: the module will 1838 be called pm-notifier-error-inject. 1839 1840 If unsure, say N. 1841 1842config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1843 tristate "OF reconfig notifier error injection module" 1844 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1845 help 1846 This option provides the ability to inject artificial errors to 1847 OF reconfig notifier chain callbacks. It is controlled 1848 through debugfs interface under 1849 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1850 1851 If the notifier call chain should be failed with some events 1852 notified, write the error code to "actions/<notifier event>/error". 1853 1854 To compile this code as a module, choose M here: the module will 1855 be called of-reconfig-notifier-error-inject. 1856 1857 If unsure, say N. 1858 1859config NETDEV_NOTIFIER_ERROR_INJECT 1860 tristate "Netdev notifier error injection module" 1861 depends on NET && NOTIFIER_ERROR_INJECTION 1862 help 1863 This option provides the ability to inject artificial errors to 1864 netdevice notifier chain callbacks. It is controlled through debugfs 1865 interface /sys/kernel/debug/notifier-error-inject/netdev 1866 1867 If the notifier call chain should be failed with some events 1868 notified, write the error code to "actions/<notifier event>/error". 1869 1870 Example: Inject netdevice mtu change error (-22 = -EINVAL) 1871 1872 # cd /sys/kernel/debug/notifier-error-inject/netdev 1873 # echo -22 > actions/NETDEV_CHANGEMTU/error 1874 # ip link set eth0 mtu 1024 1875 RTNETLINK answers: Invalid argument 1876 1877 To compile this code as a module, choose M here: the module will 1878 be called netdev-notifier-error-inject. 1879 1880 If unsure, say N. 1881 1882config FUNCTION_ERROR_INJECTION 1883 def_bool y 1884 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 1885 1886config FAULT_INJECTION 1887 bool "Fault-injection framework" 1888 depends on DEBUG_KERNEL 1889 help 1890 Provide fault-injection framework. 1891 For more details, see Documentation/fault-injection/. 1892 1893config FAILSLAB 1894 bool "Fault-injection capability for kmalloc" 1895 depends on FAULT_INJECTION 1896 depends on SLAB || SLUB 1897 help 1898 Provide fault-injection capability for kmalloc. 1899 1900config FAIL_PAGE_ALLOC 1901 bool "Fault-injection capability for alloc_pages()" 1902 depends on FAULT_INJECTION 1903 help 1904 Provide fault-injection capability for alloc_pages(). 1905 1906config FAULT_INJECTION_USERCOPY 1907 bool "Fault injection capability for usercopy functions" 1908 depends on FAULT_INJECTION 1909 help 1910 Provides fault-injection capability to inject failures 1911 in usercopy functions (copy_from_user(), get_user(), ...). 1912 1913config FAIL_MAKE_REQUEST 1914 bool "Fault-injection capability for disk IO" 1915 depends on FAULT_INJECTION && BLOCK 1916 help 1917 Provide fault-injection capability for disk IO. 1918 1919config FAIL_IO_TIMEOUT 1920 bool "Fault-injection capability for faking disk interrupts" 1921 depends on FAULT_INJECTION && BLOCK 1922 help 1923 Provide fault-injection capability on end IO handling. This 1924 will make the block layer "forget" an interrupt as configured, 1925 thus exercising the error handling. 1926 1927 Only works with drivers that use the generic timeout handling, 1928 for others it wont do anything. 1929 1930config FAIL_FUTEX 1931 bool "Fault-injection capability for futexes" 1932 select DEBUG_FS 1933 depends on FAULT_INJECTION && FUTEX 1934 help 1935 Provide fault-injection capability for futexes. 1936 1937config FAULT_INJECTION_DEBUG_FS 1938 bool "Debugfs entries for fault-injection capabilities" 1939 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 1940 help 1941 Enable configuration of fault-injection capabilities via debugfs. 1942 1943config FAIL_FUNCTION 1944 bool "Fault-injection capability for functions" 1945 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 1946 help 1947 Provide function-based fault-injection capability. 1948 This will allow you to override a specific function with a return 1949 with given return value. As a result, function caller will see 1950 an error value and have to handle it. This is useful to test the 1951 error handling in various subsystems. 1952 1953config FAIL_MMC_REQUEST 1954 bool "Fault-injection capability for MMC IO" 1955 depends on FAULT_INJECTION_DEBUG_FS && MMC 1956 help 1957 Provide fault-injection capability for MMC IO. 1958 This will make the mmc core return data errors. This is 1959 useful to test the error handling in the mmc block device 1960 and to test how the mmc host driver handles retries from 1961 the block device. 1962 1963config FAULT_INJECTION_STACKTRACE_FILTER 1964 bool "stacktrace filter for fault-injection capabilities" 1965 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 1966 depends on !X86_64 1967 select STACKTRACE 1968 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 1969 help 1970 Provide stacktrace filter for fault-injection capabilities 1971 1972config ARCH_HAS_KCOV 1973 bool 1974 help 1975 An architecture should select this when it can successfully 1976 build and run with CONFIG_KCOV. This typically requires 1977 disabling instrumentation for some early boot code. 1978 1979config CC_HAS_SANCOV_TRACE_PC 1980 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 1981 1982 1983config KCOV 1984 bool "Code coverage for fuzzing" 1985 depends on ARCH_HAS_KCOV 1986 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 1987 select DEBUG_FS 1988 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 1989 help 1990 KCOV exposes kernel code coverage information in a form suitable 1991 for coverage-guided fuzzing (randomized testing). 1992 1993 If RANDOMIZE_BASE is enabled, PC values will not be stable across 1994 different machines and across reboots. If you need stable PC values, 1995 disable RANDOMIZE_BASE. 1996 1997 For more details, see Documentation/dev-tools/kcov.rst. 1998 1999config KCOV_ENABLE_COMPARISONS 2000 bool "Enable comparison operands collection by KCOV" 2001 depends on KCOV 2002 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 2003 help 2004 KCOV also exposes operands of every comparison in the instrumented 2005 code along with operand sizes and PCs of the comparison instructions. 2006 These operands can be used by fuzzing engines to improve the quality 2007 of fuzzing coverage. 2008 2009config KCOV_INSTRUMENT_ALL 2010 bool "Instrument all code by default" 2011 depends on KCOV 2012 default y 2013 help 2014 If you are doing generic system call fuzzing (like e.g. syzkaller), 2015 then you will want to instrument the whole kernel and you should 2016 say y here. If you are doing more targeted fuzzing (like e.g. 2017 filesystem fuzzing with AFL) then you will want to enable coverage 2018 for more specific subsets of files, and should say n here. 2019 2020config KCOV_IRQ_AREA_SIZE 2021 hex "Size of interrupt coverage collection area in words" 2022 depends on KCOV 2023 default 0x40000 2024 help 2025 KCOV uses preallocated per-cpu areas to collect coverage from 2026 soft interrupts. This specifies the size of those areas in the 2027 number of unsigned long words. 2028 2029menuconfig RUNTIME_TESTING_MENU 2030 bool "Runtime Testing" 2031 def_bool y 2032 2033if RUNTIME_TESTING_MENU 2034 2035config LKDTM 2036 tristate "Linux Kernel Dump Test Tool Module" 2037 depends on DEBUG_FS 2038 help 2039 This module enables testing of the different dumping mechanisms by 2040 inducing system failures at predefined crash points. 2041 If you don't need it: say N 2042 Choose M here to compile this code as a module. The module will be 2043 called lkdtm. 2044 2045 Documentation on how to use the module can be found in 2046 Documentation/fault-injection/provoke-crashes.rst 2047 2048config TEST_LIST_SORT 2049 tristate "Linked list sorting test" 2050 depends on DEBUG_KERNEL || m 2051 help 2052 Enable this to turn on 'list_sort()' function test. This test is 2053 executed only once during system boot (so affects only boot time), 2054 or at module load time. 2055 2056 If unsure, say N. 2057 2058config TEST_MIN_HEAP 2059 tristate "Min heap test" 2060 depends on DEBUG_KERNEL || m 2061 help 2062 Enable this to turn on min heap function tests. This test is 2063 executed only once during system boot (so affects only boot time), 2064 or at module load time. 2065 2066 If unsure, say N. 2067 2068config TEST_SORT 2069 tristate "Array-based sort test" 2070 depends on DEBUG_KERNEL || m 2071 help 2072 This option enables the self-test function of 'sort()' at boot, 2073 or at module load time. 2074 2075 If unsure, say N. 2076 2077config TEST_DIV64 2078 tristate "64bit/32bit division and modulo test" 2079 depends on DEBUG_KERNEL || m 2080 help 2081 Enable this to turn on 'do_div()' function test. This test is 2082 executed only once during system boot (so affects only boot time), 2083 or at module load time. 2084 2085 If unsure, say N. 2086 2087config KPROBES_SANITY_TEST 2088 bool "Kprobes sanity tests" 2089 depends on DEBUG_KERNEL 2090 depends on KPROBES 2091 help 2092 This option provides for testing basic kprobes functionality on 2093 boot. Samples of kprobe and kretprobe are inserted and 2094 verified for functionality. 2095 2096 Say N if you are unsure. 2097 2098config BACKTRACE_SELF_TEST 2099 tristate "Self test for the backtrace code" 2100 depends on DEBUG_KERNEL 2101 help 2102 This option provides a kernel module that can be used to test 2103 the kernel stack backtrace code. This option is not useful 2104 for distributions or general kernels, but only for kernel 2105 developers working on architecture code. 2106 2107 Note that if you want to also test saved backtraces, you will 2108 have to enable STACKTRACE as well. 2109 2110 Say N if you are unsure. 2111 2112config RBTREE_TEST 2113 tristate "Red-Black tree test" 2114 depends on DEBUG_KERNEL 2115 help 2116 A benchmark measuring the performance of the rbtree library. 2117 Also includes rbtree invariant checks. 2118 2119config REED_SOLOMON_TEST 2120 tristate "Reed-Solomon library test" 2121 depends on DEBUG_KERNEL || m 2122 select REED_SOLOMON 2123 select REED_SOLOMON_ENC16 2124 select REED_SOLOMON_DEC16 2125 help 2126 This option enables the self-test function of rslib at boot, 2127 or at module load time. 2128 2129 If unsure, say N. 2130 2131config INTERVAL_TREE_TEST 2132 tristate "Interval tree test" 2133 depends on DEBUG_KERNEL 2134 select INTERVAL_TREE 2135 help 2136 A benchmark measuring the performance of the interval tree library 2137 2138config PERCPU_TEST 2139 tristate "Per cpu operations test" 2140 depends on m && DEBUG_KERNEL 2141 help 2142 Enable this option to build test module which validates per-cpu 2143 operations. 2144 2145 If unsure, say N. 2146 2147config ATOMIC64_SELFTEST 2148 tristate "Perform an atomic64_t self-test" 2149 help 2150 Enable this option to test the atomic64_t functions at boot or 2151 at module load time. 2152 2153 If unsure, say N. 2154 2155config ASYNC_RAID6_TEST 2156 tristate "Self test for hardware accelerated raid6 recovery" 2157 depends on ASYNC_RAID6_RECOV 2158 select ASYNC_MEMCPY 2159 help 2160 This is a one-shot self test that permutes through the 2161 recovery of all the possible two disk failure scenarios for a 2162 N-disk array. Recovery is performed with the asynchronous 2163 raid6 recovery routines, and will optionally use an offload 2164 engine if one is available. 2165 2166 If unsure, say N. 2167 2168config TEST_HEXDUMP 2169 tristate "Test functions located in the hexdump module at runtime" 2170 2171config TEST_STRING_HELPERS 2172 tristate "Test functions located in the string_helpers module at runtime" 2173 2174config TEST_STRSCPY 2175 tristate "Test strscpy*() family of functions at runtime" 2176 2177config TEST_KSTRTOX 2178 tristate "Test kstrto*() family of functions at runtime" 2179 2180config TEST_PRINTF 2181 tristate "Test printf() family of functions at runtime" 2182 2183config TEST_BITMAP 2184 tristate "Test bitmap_*() family of functions at runtime" 2185 help 2186 Enable this option to test the bitmap functions at boot. 2187 2188 If unsure, say N. 2189 2190config TEST_UUID 2191 tristate "Test functions located in the uuid module at runtime" 2192 2193config TEST_XARRAY 2194 tristate "Test the XArray code at runtime" 2195 2196config TEST_OVERFLOW 2197 tristate "Test check_*_overflow() functions at runtime" 2198 2199config TEST_RHASHTABLE 2200 tristate "Perform selftest on resizable hash table" 2201 help 2202 Enable this option to test the rhashtable functions at boot. 2203 2204 If unsure, say N. 2205 2206config TEST_HASH 2207 tristate "Perform selftest on hash functions" 2208 help 2209 Enable this option to test the kernel's integer (<linux/hash.h>), 2210 string (<linux/stringhash.h>), and siphash (<linux/siphash.h>) 2211 hash functions on boot (or module load). 2212 2213 This is intended to help people writing architecture-specific 2214 optimized versions. If unsure, say N. 2215 2216config TEST_IDA 2217 tristate "Perform selftest on IDA functions" 2218 2219config TEST_PARMAN 2220 tristate "Perform selftest on priority array manager" 2221 depends on PARMAN 2222 help 2223 Enable this option to test priority array manager on boot 2224 (or module load). 2225 2226 If unsure, say N. 2227 2228config TEST_IRQ_TIMINGS 2229 bool "IRQ timings selftest" 2230 depends on IRQ_TIMINGS 2231 help 2232 Enable this option to test the irq timings code on boot. 2233 2234 If unsure, say N. 2235 2236config TEST_LKM 2237 tristate "Test module loading with 'hello world' module" 2238 depends on m 2239 help 2240 This builds the "test_module" module that emits "Hello, world" 2241 on printk when loaded. It is designed to be used for basic 2242 evaluation of the module loading subsystem (for example when 2243 validating module verification). It lacks any extra dependencies, 2244 and will not normally be loaded by the system unless explicitly 2245 requested by name. 2246 2247 If unsure, say N. 2248 2249config TEST_BITOPS 2250 tristate "Test module for compilation of bitops operations" 2251 depends on m 2252 help 2253 This builds the "test_bitops" module that is much like the 2254 TEST_LKM module except that it does a basic exercise of the 2255 set/clear_bit macros and get_count_order/long to make sure there are 2256 no compiler warnings from C=1 sparse checker or -Wextra 2257 compilations. It has no dependencies and doesn't run or load unless 2258 explicitly requested by name. for example: modprobe test_bitops. 2259 2260 If unsure, say N. 2261 2262config TEST_VMALLOC 2263 tristate "Test module for stress/performance analysis of vmalloc allocator" 2264 default n 2265 depends on MMU 2266 depends on m 2267 help 2268 This builds the "test_vmalloc" module that should be used for 2269 stress and performance analysis. So, any new change for vmalloc 2270 subsystem can be evaluated from performance and stability point 2271 of view. 2272 2273 If unsure, say N. 2274 2275config TEST_USER_COPY 2276 tristate "Test user/kernel boundary protections" 2277 depends on m 2278 help 2279 This builds the "test_user_copy" module that runs sanity checks 2280 on the copy_to/from_user infrastructure, making sure basic 2281 user/kernel boundary testing is working. If it fails to load, 2282 a regression has been detected in the user/kernel memory boundary 2283 protections. 2284 2285 If unsure, say N. 2286 2287config TEST_BPF 2288 tristate "Test BPF filter functionality" 2289 depends on m && NET 2290 help 2291 This builds the "test_bpf" module that runs various test vectors 2292 against the BPF interpreter or BPF JIT compiler depending on the 2293 current setting. This is in particular useful for BPF JIT compiler 2294 development, but also to run regression tests against changes in 2295 the interpreter code. It also enables test stubs for eBPF maps and 2296 verifier used by user space verifier testsuite. 2297 2298 If unsure, say N. 2299 2300config TEST_BLACKHOLE_DEV 2301 tristate "Test blackhole netdev functionality" 2302 depends on m && NET 2303 help 2304 This builds the "test_blackhole_dev" module that validates the 2305 data path through this blackhole netdev. 2306 2307 If unsure, say N. 2308 2309config FIND_BIT_BENCHMARK 2310 tristate "Test find_bit functions" 2311 help 2312 This builds the "test_find_bit" module that measure find_*_bit() 2313 functions performance. 2314 2315 If unsure, say N. 2316 2317config TEST_FIRMWARE 2318 tristate "Test firmware loading via userspace interface" 2319 depends on FW_LOADER 2320 help 2321 This builds the "test_firmware" module that creates a userspace 2322 interface for testing firmware loading. This can be used to 2323 control the triggering of firmware loading without needing an 2324 actual firmware-using device. The contents can be rechecked by 2325 userspace. 2326 2327 If unsure, say N. 2328 2329config TEST_SYSCTL 2330 tristate "sysctl test driver" 2331 depends on PROC_SYSCTL 2332 help 2333 This builds the "test_sysctl" module. This driver enables to test the 2334 proc sysctl interfaces available to drivers safely without affecting 2335 production knobs which might alter system functionality. 2336 2337 If unsure, say N. 2338 2339config BITFIELD_KUNIT 2340 tristate "KUnit test bitfield functions at runtime" 2341 depends on KUNIT 2342 help 2343 Enable this option to test the bitfield functions at boot. 2344 2345 KUnit tests run during boot and output the results to the debug log 2346 in TAP format (http://testanything.org/). Only useful for kernel devs 2347 running the KUnit test harness, and not intended for inclusion into a 2348 production build. 2349 2350 For more information on KUnit and unit tests in general please refer 2351 to the KUnit documentation in Documentation/dev-tools/kunit/. 2352 2353 If unsure, say N. 2354 2355config RESOURCE_KUNIT_TEST 2356 tristate "KUnit test for resource API" 2357 depends on KUNIT 2358 help 2359 This builds the resource API unit test. 2360 Tests the logic of API provided by resource.c and ioport.h. 2361 For more information on KUnit and unit tests in general please refer 2362 to the KUnit documentation in Documentation/dev-tools/kunit/. 2363 2364 If unsure, say N. 2365 2366config SYSCTL_KUNIT_TEST 2367 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS 2368 depends on KUNIT 2369 default KUNIT_ALL_TESTS 2370 help 2371 This builds the proc sysctl unit test, which runs on boot. 2372 Tests the API contract and implementation correctness of sysctl. 2373 For more information on KUnit and unit tests in general please refer 2374 to the KUnit documentation in Documentation/dev-tools/kunit/. 2375 2376 If unsure, say N. 2377 2378config LIST_KUNIT_TEST 2379 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS 2380 depends on KUNIT 2381 default KUNIT_ALL_TESTS 2382 help 2383 This builds the linked list KUnit test suite. 2384 It tests that the API and basic functionality of the list_head type 2385 and associated macros. 2386 2387 KUnit tests run during boot and output the results to the debug log 2388 in TAP format (https://testanything.org/). Only useful for kernel devs 2389 running the KUnit test harness, and not intended for inclusion into a 2390 production build. 2391 2392 For more information on KUnit and unit tests in general please refer 2393 to the KUnit documentation in Documentation/dev-tools/kunit/. 2394 2395 If unsure, say N. 2396 2397config LINEAR_RANGES_TEST 2398 tristate "KUnit test for linear_ranges" 2399 depends on KUNIT 2400 select LINEAR_RANGES 2401 help 2402 This builds the linear_ranges unit test, which runs on boot. 2403 Tests the linear_ranges logic correctness. 2404 For more information on KUnit and unit tests in general please refer 2405 to the KUnit documentation in Documentation/dev-tools/kunit/. 2406 2407 If unsure, say N. 2408 2409config CMDLINE_KUNIT_TEST 2410 tristate "KUnit test for cmdline API" 2411 depends on KUNIT 2412 help 2413 This builds the cmdline API unit test. 2414 Tests the logic of API provided by cmdline.c. 2415 For more information on KUnit and unit tests in general please refer 2416 to the KUnit documentation in Documentation/dev-tools/kunit/. 2417 2418 If unsure, say N. 2419 2420config BITS_TEST 2421 tristate "KUnit test for bits.h" 2422 depends on KUNIT 2423 help 2424 This builds the bits unit test. 2425 Tests the logic of macros defined in bits.h. 2426 For more information on KUnit and unit tests in general please refer 2427 to the KUnit documentation in Documentation/dev-tools/kunit/. 2428 2429 If unsure, say N. 2430 2431config TEST_UDELAY 2432 tristate "udelay test driver" 2433 help 2434 This builds the "udelay_test" module that helps to make sure 2435 that udelay() is working properly. 2436 2437 If unsure, say N. 2438 2439config TEST_STATIC_KEYS 2440 tristate "Test static keys" 2441 depends on m 2442 help 2443 Test the static key interfaces. 2444 2445 If unsure, say N. 2446 2447config TEST_KMOD 2448 tristate "kmod stress tester" 2449 depends on m 2450 depends on NETDEVICES && NET_CORE && INET # for TUN 2451 depends on BLOCK 2452 select TEST_LKM 2453 select XFS_FS 2454 select TUN 2455 select BTRFS_FS 2456 help 2457 Test the kernel's module loading mechanism: kmod. kmod implements 2458 support to load modules using the Linux kernel's usermode helper. 2459 This test provides a series of tests against kmod. 2460 2461 Although technically you can either build test_kmod as a module or 2462 into the kernel we disallow building it into the kernel since 2463 it stress tests request_module() and this will very likely cause 2464 some issues by taking over precious threads available from other 2465 module load requests, ultimately this could be fatal. 2466 2467 To run tests run: 2468 2469 tools/testing/selftests/kmod/kmod.sh --help 2470 2471 If unsure, say N. 2472 2473config TEST_DEBUG_VIRTUAL 2474 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 2475 depends on DEBUG_VIRTUAL 2476 help 2477 Test the kernel's ability to detect incorrect calls to 2478 virt_to_phys() done against the non-linear part of the 2479 kernel's virtual address map. 2480 2481 If unsure, say N. 2482 2483config TEST_MEMCAT_P 2484 tristate "Test memcat_p() helper function" 2485 help 2486 Test the memcat_p() helper for correctly merging two 2487 pointer arrays together. 2488 2489 If unsure, say N. 2490 2491config TEST_LIVEPATCH 2492 tristate "Test livepatching" 2493 default n 2494 depends on DYNAMIC_DEBUG 2495 depends on LIVEPATCH 2496 depends on m 2497 help 2498 Test kernel livepatching features for correctness. The tests will 2499 load test modules that will be livepatched in various scenarios. 2500 2501 To run all the livepatching tests: 2502 2503 make -C tools/testing/selftests TARGETS=livepatch run_tests 2504 2505 Alternatively, individual tests may be invoked: 2506 2507 tools/testing/selftests/livepatch/test-callbacks.sh 2508 tools/testing/selftests/livepatch/test-livepatch.sh 2509 tools/testing/selftests/livepatch/test-shadow-vars.sh 2510 2511 If unsure, say N. 2512 2513config TEST_OBJAGG 2514 tristate "Perform selftest on object aggreration manager" 2515 default n 2516 depends on OBJAGG 2517 help 2518 Enable this option to test object aggregation manager on boot 2519 (or module load). 2520 2521 2522config TEST_STACKINIT 2523 tristate "Test level of stack variable initialization" 2524 help 2525 Test if the kernel is zero-initializing stack variables and 2526 padding. Coverage is controlled by compiler flags, 2527 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2528 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2529 2530 If unsure, say N. 2531 2532config TEST_MEMINIT 2533 tristate "Test heap/page initialization" 2534 help 2535 Test if the kernel is zero-initializing heap and page allocations. 2536 This can be useful to test init_on_alloc and init_on_free features. 2537 2538 If unsure, say N. 2539 2540config TEST_HMM 2541 tristate "Test HMM (Heterogeneous Memory Management)" 2542 depends on TRANSPARENT_HUGEPAGE 2543 depends on DEVICE_PRIVATE 2544 select HMM_MIRROR 2545 select MMU_NOTIFIER 2546 help 2547 This is a pseudo device driver solely for testing HMM. 2548 Say M here if you want to build the HMM test module. 2549 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests. 2550 2551 If unsure, say N. 2552 2553config TEST_FREE_PAGES 2554 tristate "Test freeing pages" 2555 help 2556 Test that a memory leak does not occur due to a race between 2557 freeing a block of pages and a speculative page reference. 2558 Loading this module is safe if your kernel has the bug fixed. 2559 If the bug is not fixed, it will leak gigabytes of memory and 2560 probably OOM your system. 2561 2562config TEST_FPU 2563 tristate "Test floating point operations in kernel space" 2564 depends on X86 && !KCOV_INSTRUMENT_ALL 2565 help 2566 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu 2567 which will trigger a sequence of floating point operations. This is used 2568 for self-testing floating point control register setting in 2569 kernel_fpu_begin(). 2570 2571 If unsure, say N. 2572 2573endif # RUNTIME_TESTING_MENU 2574 2575config ARCH_USE_MEMTEST 2576 bool 2577 help 2578 An architecture should select this when it uses early_memtest() 2579 during boot process. 2580 2581config MEMTEST 2582 bool "Memtest" 2583 depends on ARCH_USE_MEMTEST 2584 help 2585 This option adds a kernel parameter 'memtest', which allows memtest 2586 to be set and executed. 2587 memtest=0, mean disabled; -- default 2588 memtest=1, mean do 1 test pattern; 2589 ... 2590 memtest=17, mean do 17 test patterns. 2591 If you are unsure how to answer this question, answer N. 2592 2593 2594 2595config HYPERV_TESTING 2596 bool "Microsoft Hyper-V driver testing" 2597 default n 2598 depends on HYPERV && DEBUG_FS 2599 help 2600 Select this option to enable Hyper-V vmbus testing. 2601 2602endmenu # "Kernel Testing and Coverage" 2603 2604source "Documentation/Kconfig" 2605 2606endmenu # Kernel hacking 2607