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 PAHOLE_HAS_ZEROSIZE_PERCPU_SUPPORT 317 def_bool $(success, test `$(PAHOLE) --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/'` -ge "122") 318 319config DEBUG_INFO_BTF_MODULES 320 def_bool y 321 depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF 322 help 323 Generate compact split BTF type information for kernel modules. 324 325config GDB_SCRIPTS 326 bool "Provide GDB scripts for kernel debugging" 327 help 328 This creates the required links to GDB helper scripts in the 329 build directory. If you load vmlinux into gdb, the helper 330 scripts will be automatically imported by gdb as well, and 331 additional functions are available to analyze a Linux kernel 332 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst 333 for further details. 334 335endif # DEBUG_INFO 336 337config FRAME_WARN 338 int "Warn for stack frames larger than" 339 range 0 8192 340 default 2048 if GCC_PLUGIN_LATENT_ENTROPY 341 default 1280 if (!64BIT && PARISC) 342 default 1024 if (!64BIT && !PARISC) 343 default 2048 if 64BIT 344 help 345 Tell gcc to warn at build time for stack frames larger than this. 346 Setting this too low will cause a lot of warnings. 347 Setting it to 0 disables the warning. 348 349config STRIP_ASM_SYMS 350 bool "Strip assembler-generated symbols during link" 351 default n 352 help 353 Strip internal assembler-generated symbols during a link (symbols 354 that look like '.Lxxx') so they don't pollute the output of 355 get_wchan() and suchlike. 356 357config READABLE_ASM 358 bool "Generate readable assembler code" 359 depends on DEBUG_KERNEL 360 help 361 Disable some compiler optimizations that tend to generate human unreadable 362 assembler output. This may make the kernel slightly slower, but it helps 363 to keep kernel developers who have to stare a lot at assembler listings 364 sane. 365 366config HEADERS_INSTALL 367 bool "Install uapi headers to usr/include" 368 depends on !UML 369 help 370 This option will install uapi headers (headers exported to user-space) 371 into the usr/include directory for use during the kernel build. 372 This is unneeded for building the kernel itself, but needed for some 373 user-space program samples. It is also needed by some features such 374 as uapi header sanity checks. 375 376config DEBUG_SECTION_MISMATCH 377 bool "Enable full Section mismatch analysis" 378 help 379 The section mismatch analysis checks if there are illegal 380 references from one section to another section. 381 During linktime or runtime, some sections are dropped; 382 any use of code/data previously in these sections would 383 most likely result in an oops. 384 In the code, functions and variables are annotated with 385 __init,, etc. (see the full list in include/linux/init.h), 386 which results in the code/data being placed in specific sections. 387 The section mismatch analysis is always performed after a full 388 kernel build, and enabling this option causes the following 389 additional step to occur: 390 - Add the option -fno-inline-functions-called-once to gcc commands. 391 When inlining a function annotated with __init in a non-init 392 function, we would lose the section information and thus 393 the analysis would not catch the illegal reference. 394 This option tells gcc to inline less (but it does result in 395 a larger kernel). 396 397config SECTION_MISMATCH_WARN_ONLY 398 bool "Make section mismatch errors non-fatal" 399 default y 400 help 401 If you say N here, the build process will fail if there are any 402 section mismatch, instead of just throwing warnings. 403 404 If unsure, say Y. 405 406config DEBUG_FORCE_FUNCTION_ALIGN_32B 407 bool "Force all function address 32B aligned" if EXPERT 408 help 409 There are cases that a commit from one domain changes the function 410 address alignment of other domains, and cause magic performance 411 bump (regression or improvement). Enable this option will help to 412 verify if the bump is caused by function alignment changes, while 413 it will slightly increase the kernel size and affect icache usage. 414 415 It is mainly for debug and performance tuning use. 416 417# 418# Select this config option from the architecture Kconfig, if it 419# is preferred to always offer frame pointers as a config 420# option on the architecture (regardless of KERNEL_DEBUG): 421# 422config ARCH_WANT_FRAME_POINTERS 423 bool 424 425config FRAME_POINTER 426 bool "Compile the kernel with frame pointers" 427 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS 428 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 429 help 430 If you say Y here the resulting kernel image will be slightly 431 larger and slower, but it gives very useful debugging information 432 in case of kernel bugs. (precise oopses/stacktraces/warnings) 433 434config STACK_VALIDATION 435 bool "Compile-time stack metadata validation" 436 depends on HAVE_STACK_VALIDATION 437 default n 438 help 439 Add compile-time checks to validate stack metadata, including frame 440 pointers (if CONFIG_FRAME_POINTER is enabled). This helps ensure 441 that runtime stack traces are more reliable. 442 443 This is also a prerequisite for generation of ORC unwind data, which 444 is needed for CONFIG_UNWINDER_ORC. 445 446 For more information, see 447 tools/objtool/Documentation/stack-validation.txt. 448 449config VMLINUX_VALIDATION 450 bool 451 depends on STACK_VALIDATION && DEBUG_ENTRY && !PARAVIRT 452 default y 453 454config VMLINUX_MAP 455 bool "Generate vmlinux.map file when linking" 456 depends on EXPERT 457 help 458 Selecting this option will pass "-Map=vmlinux.map" to ld 459 when linking vmlinux. That file can be useful for verifying 460 and debugging magic section games, and for seeing which 461 pieces of code get eliminated with 462 CONFIG_LD_DEAD_CODE_DATA_ELIMINATION. 463 464config DEBUG_FORCE_WEAK_PER_CPU 465 bool "Force weak per-cpu definitions" 466 depends on DEBUG_KERNEL 467 help 468 s390 and alpha require percpu variables in modules to be 469 defined weak to work around addressing range issue which 470 puts the following two restrictions on percpu variable 471 definitions. 472 473 1. percpu symbols must be unique whether static or not 474 2. percpu variables can't be defined inside a function 475 476 To ensure that generic code follows the above rules, this 477 option forces all percpu variables to be defined as weak. 478 479endmenu # "Compiler options" 480 481menu "Generic Kernel Debugging Instruments" 482 483config MAGIC_SYSRQ 484 bool "Magic SysRq key" 485 depends on !UML 486 help 487 If you say Y here, you will have some control over the system even 488 if the system crashes for example during kernel debugging (e.g., you 489 will be able to flush the buffer cache to disk, reboot the system 490 immediately or dump some status information). This is accomplished 491 by pressing various keys while holding SysRq (Alt+PrintScreen). It 492 also works on a serial console (on PC hardware at least), if you 493 send a BREAK and then within 5 seconds a command keypress. The 494 keys are documented in <file:Documentation/admin-guide/sysrq.rst>. 495 Don't say Y unless you really know what this hack does. 496 497config MAGIC_SYSRQ_DEFAULT_ENABLE 498 hex "Enable magic SysRq key functions by default" 499 depends on MAGIC_SYSRQ 500 default 0x1 501 help 502 Specifies which SysRq key functions are enabled by default. 503 This may be set to 1 or 0 to enable or disable them all, or 504 to a bitmask as described in Documentation/admin-guide/sysrq.rst. 505 506config MAGIC_SYSRQ_SERIAL 507 bool "Enable magic SysRq key over serial" 508 depends on MAGIC_SYSRQ 509 default y 510 help 511 Many embedded boards have a disconnected TTL level serial which can 512 generate some garbage that can lead to spurious false sysrq detects. 513 This option allows you to decide whether you want to enable the 514 magic SysRq key. 515 516config MAGIC_SYSRQ_SERIAL_SEQUENCE 517 string "Char sequence that enables magic SysRq over serial" 518 depends on MAGIC_SYSRQ_SERIAL 519 default "" 520 help 521 Specifies a sequence of characters that can follow BREAK to enable 522 SysRq on a serial console. 523 524 If unsure, leave an empty string and the option will not be enabled. 525 526config DEBUG_FS 527 bool "Debug Filesystem" 528 help 529 debugfs is a virtual file system that kernel developers use to put 530 debugging files into. Enable this option to be able to read and 531 write to these files. 532 533 For detailed documentation on the debugfs API, see 534 Documentation/filesystems/. 535 536 If unsure, say N. 537 538choice 539 prompt "Debugfs default access" 540 depends on DEBUG_FS 541 default DEBUG_FS_ALLOW_ALL 542 help 543 This selects the default access restrictions for debugfs. 544 It can be overridden with kernel command line option 545 debugfs=[on,no-mount,off]. The restrictions apply for API access 546 and filesystem registration. 547 548config DEBUG_FS_ALLOW_ALL 549 bool "Access normal" 550 help 551 No restrictions apply. Both API and filesystem registration 552 is on. This is the normal default operation. 553 554config DEBUG_FS_DISALLOW_MOUNT 555 bool "Do not register debugfs as filesystem" 556 help 557 The API is open but filesystem is not loaded. Clients can still do 558 their work and read with debug tools that do not need 559 debugfs filesystem. 560 561config DEBUG_FS_ALLOW_NONE 562 bool "No access" 563 help 564 Access is off. Clients get -PERM when trying to create nodes in 565 debugfs tree and debugfs is not registered as a filesystem. 566 Client can then back-off or continue without debugfs access. 567 568endchoice 569 570source "lib/Kconfig.kgdb" 571source "lib/Kconfig.ubsan" 572source "lib/Kconfig.kcsan" 573 574endmenu 575 576config DEBUG_KERNEL 577 bool "Kernel debugging" 578 help 579 Say Y here if you are developing drivers or trying to debug and 580 identify kernel problems. 581 582config DEBUG_MISC 583 bool "Miscellaneous debug code" 584 default DEBUG_KERNEL 585 depends on DEBUG_KERNEL 586 help 587 Say Y here if you need to enable miscellaneous debug code that should 588 be under a more specific debug option but isn't. 589 590 591menu "Memory Debugging" 592 593source "mm/Kconfig.debug" 594 595config DEBUG_OBJECTS 596 bool "Debug object operations" 597 depends on DEBUG_KERNEL 598 help 599 If you say Y here, additional code will be inserted into the 600 kernel to track the life time of various objects and validate 601 the operations on those objects. 602 603config DEBUG_OBJECTS_SELFTEST 604 bool "Debug objects selftest" 605 depends on DEBUG_OBJECTS 606 help 607 This enables the selftest of the object debug code. 608 609config DEBUG_OBJECTS_FREE 610 bool "Debug objects in freed memory" 611 depends on DEBUG_OBJECTS 612 help 613 This enables checks whether a k/v free operation frees an area 614 which contains an object which has not been deactivated 615 properly. This can make kmalloc/kfree-intensive workloads 616 much slower. 617 618config DEBUG_OBJECTS_TIMERS 619 bool "Debug timer objects" 620 depends on DEBUG_OBJECTS 621 help 622 If you say Y here, additional code will be inserted into the 623 timer routines to track the life time of timer objects and 624 validate the timer operations. 625 626config DEBUG_OBJECTS_WORK 627 bool "Debug work objects" 628 depends on DEBUG_OBJECTS 629 help 630 If you say Y here, additional code will be inserted into the 631 work queue routines to track the life time of work objects and 632 validate the work operations. 633 634config DEBUG_OBJECTS_RCU_HEAD 635 bool "Debug RCU callbacks objects" 636 depends on DEBUG_OBJECTS 637 help 638 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 639 640config DEBUG_OBJECTS_PERCPU_COUNTER 641 bool "Debug percpu counter objects" 642 depends on DEBUG_OBJECTS 643 help 644 If you say Y here, additional code will be inserted into the 645 percpu counter routines to track the life time of percpu counter 646 objects and validate the percpu counter operations. 647 648config DEBUG_OBJECTS_ENABLE_DEFAULT 649 int "debug_objects bootup default value (0-1)" 650 range 0 1 651 default "1" 652 depends on DEBUG_OBJECTS 653 help 654 Debug objects boot parameter default value 655 656config DEBUG_SLAB 657 bool "Debug slab memory allocations" 658 depends on DEBUG_KERNEL && SLAB 659 help 660 Say Y here to have the kernel do limited verification on memory 661 allocation as well as poisoning memory on free to catch use of freed 662 memory. This can make kmalloc/kfree-intensive workloads much slower. 663 664config SLUB_DEBUG_ON 665 bool "SLUB debugging on by default" 666 depends on SLUB && SLUB_DEBUG 667 default n 668 help 669 Boot with debugging on by default. SLUB boots by default with 670 the runtime debug capabilities switched off. Enabling this is 671 equivalent to specifying the "slub_debug" parameter on boot. 672 There is no support for more fine grained debug control like 673 possible with slub_debug=xxx. SLUB debugging may be switched 674 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying 675 "slub_debug=-". 676 677config SLUB_STATS 678 default n 679 bool "Enable SLUB performance statistics" 680 depends on SLUB && SYSFS 681 help 682 SLUB statistics are useful to debug SLUBs allocation behavior in 683 order find ways to optimize the allocator. This should never be 684 enabled for production use since keeping statistics slows down 685 the allocator by a few percentage points. The slabinfo command 686 supports the determination of the most active slabs to figure 687 out which slabs are relevant to a particular load. 688 Try running: slabinfo -DA 689 690config HAVE_DEBUG_KMEMLEAK 691 bool 692 693config DEBUG_KMEMLEAK 694 bool "Kernel memory leak detector" 695 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK 696 select DEBUG_FS 697 select STACKTRACE if STACKTRACE_SUPPORT 698 select KALLSYMS 699 select CRC32 700 help 701 Say Y here if you want to enable the memory leak 702 detector. The memory allocation/freeing is traced in a way 703 similar to the Boehm's conservative garbage collector, the 704 difference being that the orphan objects are not freed but 705 only shown in /sys/kernel/debug/kmemleak. Enabling this 706 feature will introduce an overhead to memory 707 allocations. See Documentation/dev-tools/kmemleak.rst for more 708 details. 709 710 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances 711 of finding leaks due to the slab objects poisoning. 712 713 In order to access the kmemleak file, debugfs needs to be 714 mounted (usually at /sys/kernel/debug). 715 716config DEBUG_KMEMLEAK_MEM_POOL_SIZE 717 int "Kmemleak memory pool size" 718 depends on DEBUG_KMEMLEAK 719 range 200 1000000 720 default 16000 721 help 722 Kmemleak must track all the memory allocations to avoid 723 reporting false positives. Since memory may be allocated or 724 freed before kmemleak is fully initialised, use a static pool 725 of metadata objects to track such callbacks. After kmemleak is 726 fully initialised, this memory pool acts as an emergency one 727 if slab allocations fail. 728 729config DEBUG_KMEMLEAK_TEST 730 tristate "Simple test for the kernel memory leak detector" 731 depends on DEBUG_KMEMLEAK && m 732 help 733 This option enables a module that explicitly leaks memory. 734 735 If unsure, say N. 736 737config DEBUG_KMEMLEAK_DEFAULT_OFF 738 bool "Default kmemleak to off" 739 depends on DEBUG_KMEMLEAK 740 help 741 Say Y here to disable kmemleak by default. It can then be enabled 742 on the command line via kmemleak=on. 743 744config DEBUG_KMEMLEAK_AUTO_SCAN 745 bool "Enable kmemleak auto scan thread on boot up" 746 default y 747 depends on DEBUG_KMEMLEAK 748 help 749 Depending on the cpu, kmemleak scan may be cpu intensive and can 750 stall user tasks at times. This option enables/disables automatic 751 kmemleak scan at boot up. 752 753 Say N here to disable kmemleak auto scan thread to stop automatic 754 scanning. Disabling this option disables automatic reporting of 755 memory leaks. 756 757 If unsure, say Y. 758 759config DEBUG_STACK_USAGE 760 bool "Stack utilization instrumentation" 761 depends on DEBUG_KERNEL && !IA64 762 help 763 Enables the display of the minimum amount of free stack which each 764 task has ever had available in the sysrq-T and sysrq-P debug output. 765 766 This option will slow down process creation somewhat. 767 768config SCHED_STACK_END_CHECK 769 bool "Detect stack corruption on calls to schedule()" 770 depends on DEBUG_KERNEL 771 default n 772 help 773 This option checks for a stack overrun on calls to schedule(). 774 If the stack end location is found to be over written always panic as 775 the content of the corrupted region can no longer be trusted. 776 This is to ensure no erroneous behaviour occurs which could result in 777 data corruption or a sporadic crash at a later stage once the region 778 is examined. The runtime overhead introduced is minimal. 779 780config ARCH_HAS_DEBUG_VM_PGTABLE 781 bool 782 help 783 An architecture should select this when it can successfully 784 build and run DEBUG_VM_PGTABLE. 785 786config DEBUG_VM 787 bool "Debug VM" 788 depends on DEBUG_KERNEL 789 help 790 Enable this to turn on extended checks in the virtual-memory system 791 that may impact performance. 792 793 If unsure, say N. 794 795config DEBUG_VM_VMACACHE 796 bool "Debug VMA caching" 797 depends on DEBUG_VM 798 help 799 Enable this to turn on VMA caching debug information. Doing so 800 can cause significant overhead, so only enable it in non-production 801 environments. 802 803 If unsure, say N. 804 805config DEBUG_VM_RB 806 bool "Debug VM red-black trees" 807 depends on DEBUG_VM 808 help 809 Enable VM red-black tree debugging information and extra validations. 810 811 If unsure, say N. 812 813config DEBUG_VM_PGFLAGS 814 bool "Debug page-flags operations" 815 depends on DEBUG_VM 816 help 817 Enables extra validation on page flags operations. 818 819 If unsure, say N. 820 821config DEBUG_VM_PGTABLE 822 bool "Debug arch page table for semantics compliance" 823 depends on MMU 824 depends on ARCH_HAS_DEBUG_VM_PGTABLE 825 default y if DEBUG_VM 826 help 827 This option provides a debug method which can be used to test 828 architecture page table helper functions on various platforms in 829 verifying if they comply with expected generic MM semantics. This 830 will help architecture code in making sure that any changes or 831 new additions of these helpers still conform to expected 832 semantics of the generic MM. Platforms will have to opt in for 833 this through ARCH_HAS_DEBUG_VM_PGTABLE. 834 835 If unsure, say N. 836 837config ARCH_HAS_DEBUG_VIRTUAL 838 bool 839 840config DEBUG_VIRTUAL 841 bool "Debug VM translations" 842 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL 843 help 844 Enable some costly sanity checks in virtual to page code. This can 845 catch mistakes with virt_to_page() and friends. 846 847 If unsure, say N. 848 849config DEBUG_NOMMU_REGIONS 850 bool "Debug the global anon/private NOMMU mapping region tree" 851 depends on DEBUG_KERNEL && !MMU 852 help 853 This option causes the global tree of anonymous and private mapping 854 regions to be regularly checked for invalid topology. 855 856config DEBUG_MEMORY_INIT 857 bool "Debug memory initialisation" if EXPERT 858 default !EXPERT 859 help 860 Enable this for additional checks during memory initialisation. 861 The sanity checks verify aspects of the VM such as the memory model 862 and other information provided by the architecture. Verbose 863 information will be printed at KERN_DEBUG loglevel depending 864 on the mminit_loglevel= command-line option. 865 866 If unsure, say Y 867 868config MEMORY_NOTIFIER_ERROR_INJECT 869 tristate "Memory hotplug notifier error injection module" 870 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION 871 help 872 This option provides the ability to inject artificial errors to 873 memory hotplug notifier chain callbacks. It is controlled through 874 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 875 876 If the notifier call chain should be failed with some events 877 notified, write the error code to "actions/<notifier event>/error". 878 879 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 880 881 # cd /sys/kernel/debug/notifier-error-inject/memory 882 # echo -12 > actions/MEM_GOING_OFFLINE/error 883 # echo offline > /sys/devices/system/memory/memoryXXX/state 884 bash: echo: write error: Cannot allocate memory 885 886 To compile this code as a module, choose M here: the module will 887 be called memory-notifier-error-inject. 888 889 If unsure, say N. 890 891config DEBUG_PER_CPU_MAPS 892 bool "Debug access to per_cpu maps" 893 depends on DEBUG_KERNEL 894 depends on SMP 895 help 896 Say Y to verify that the per_cpu map being accessed has 897 been set up. This adds a fair amount of code to kernel memory 898 and decreases performance. 899 900 Say N if unsure. 901 902config DEBUG_KMAP_LOCAL 903 bool "Debug kmap_local temporary mappings" 904 depends on DEBUG_KERNEL && KMAP_LOCAL 905 help 906 This option enables additional error checking for the kmap_local 907 infrastructure. Disable for production use. 908 909config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 910 bool 911 912config DEBUG_KMAP_LOCAL_FORCE_MAP 913 bool "Enforce kmap_local temporary mappings" 914 depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 915 select KMAP_LOCAL 916 select DEBUG_KMAP_LOCAL 917 help 918 This option enforces temporary mappings through the kmap_local 919 mechanism for non-highmem pages and on non-highmem systems. 920 Disable this for production systems! 921 922config DEBUG_HIGHMEM 923 bool "Highmem debugging" 924 depends on DEBUG_KERNEL && HIGHMEM 925 select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 926 select DEBUG_KMAP_LOCAL 927 help 928 This option enables additional error checking for high memory 929 systems. Disable for production systems. 930 931config HAVE_DEBUG_STACKOVERFLOW 932 bool 933 934config DEBUG_STACKOVERFLOW 935 bool "Check for stack overflows" 936 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 937 help 938 Say Y here if you want to check for overflows of kernel, IRQ 939 and exception stacks (if your architecture uses them). This 940 option will show detailed messages if free stack space drops 941 below a certain limit. 942 943 These kinds of bugs usually occur when call-chains in the 944 kernel get too deep, especially when interrupts are 945 involved. 946 947 Use this in cases where you see apparently random memory 948 corruption, especially if it appears in 'struct thread_info' 949 950 If in doubt, say "N". 951 952source "lib/Kconfig.kasan" 953source "lib/Kconfig.kfence" 954 955endmenu # "Memory Debugging" 956 957config DEBUG_SHIRQ 958 bool "Debug shared IRQ handlers" 959 depends on DEBUG_KERNEL 960 help 961 Enable this to generate a spurious interrupt just before a shared 962 interrupt handler is deregistered (generating one when registering 963 is currently disabled). Drivers need to handle this correctly. Some 964 don't and need to be caught. 965 966menu "Debug Oops, Lockups and Hangs" 967 968config PANIC_ON_OOPS 969 bool "Panic on Oops" 970 help 971 Say Y here to enable the kernel to panic when it oopses. This 972 has the same effect as setting oops=panic on the kernel command 973 line. 974 975 This feature is useful to ensure that the kernel does not do 976 anything erroneous after an oops which could result in data 977 corruption or other issues. 978 979 Say N if unsure. 980 981config PANIC_ON_OOPS_VALUE 982 int 983 range 0 1 984 default 0 if !PANIC_ON_OOPS 985 default 1 if PANIC_ON_OOPS 986 987config PANIC_TIMEOUT 988 int "panic timeout" 989 default 0 990 help 991 Set the timeout value (in seconds) until a reboot occurs when 992 the kernel panics. If n = 0, then we wait forever. A timeout 993 value n > 0 will wait n seconds before rebooting, while a timeout 994 value n < 0 will reboot immediately. 995 996config LOCKUP_DETECTOR 997 bool 998 999config SOFTLOCKUP_DETECTOR 1000 bool "Detect Soft Lockups" 1001 depends on DEBUG_KERNEL && !S390 1002 select LOCKUP_DETECTOR 1003 help 1004 Say Y here to enable the kernel to act as a watchdog to detect 1005 soft lockups. 1006 1007 Softlockups are bugs that cause the kernel to loop in kernel 1008 mode for more than 20 seconds, without giving other tasks a 1009 chance to run. The current stack trace is displayed upon 1010 detection and the system will stay locked up. 1011 1012config BOOTPARAM_SOFTLOCKUP_PANIC 1013 bool "Panic (Reboot) On Soft Lockups" 1014 depends on SOFTLOCKUP_DETECTOR 1015 help 1016 Say Y here to enable the kernel to panic on "soft lockups", 1017 which are bugs that cause the kernel to loop in kernel 1018 mode for more than 20 seconds (configurable using the watchdog_thresh 1019 sysctl), without giving other tasks a chance to run. 1020 1021 The panic can be used in combination with panic_timeout, 1022 to cause the system to reboot automatically after a 1023 lockup has been detected. This feature is useful for 1024 high-availability systems that have uptime guarantees and 1025 where a lockup must be resolved ASAP. 1026 1027 Say N if unsure. 1028 1029config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE 1030 int 1031 depends on SOFTLOCKUP_DETECTOR 1032 range 0 1 1033 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC 1034 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC 1035 1036config HARDLOCKUP_DETECTOR_PERF 1037 bool 1038 select SOFTLOCKUP_DETECTOR 1039 1040# 1041# Enables a timestamp based low pass filter to compensate for perf based 1042# hard lockup detection which runs too fast due to turbo modes. 1043# 1044config HARDLOCKUP_CHECK_TIMESTAMP 1045 bool 1046 1047# 1048# arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard 1049# lockup detector rather than the perf based detector. 1050# 1051config HARDLOCKUP_DETECTOR 1052 bool "Detect Hard Lockups" 1053 depends on DEBUG_KERNEL && !S390 1054 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH 1055 select LOCKUP_DETECTOR 1056 select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF 1057 select HARDLOCKUP_DETECTOR_ARCH if HAVE_HARDLOCKUP_DETECTOR_ARCH 1058 help 1059 Say Y here to enable the kernel to act as a watchdog to detect 1060 hard lockups. 1061 1062 Hardlockups are bugs that cause the CPU to loop in kernel mode 1063 for more than 10 seconds, without letting other interrupts have a 1064 chance to run. The current stack trace is displayed upon detection 1065 and the system will stay locked up. 1066 1067config BOOTPARAM_HARDLOCKUP_PANIC 1068 bool "Panic (Reboot) On Hard Lockups" 1069 depends on HARDLOCKUP_DETECTOR 1070 help 1071 Say Y here to enable the kernel to panic on "hard lockups", 1072 which are bugs that cause the kernel to loop in kernel 1073 mode with interrupts disabled for more than 10 seconds (configurable 1074 using the watchdog_thresh sysctl). 1075 1076 Say N if unsure. 1077 1078config BOOTPARAM_HARDLOCKUP_PANIC_VALUE 1079 int 1080 depends on HARDLOCKUP_DETECTOR 1081 range 0 1 1082 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC 1083 default 1 if BOOTPARAM_HARDLOCKUP_PANIC 1084 1085config DETECT_HUNG_TASK 1086 bool "Detect Hung Tasks" 1087 depends on DEBUG_KERNEL 1088 default SOFTLOCKUP_DETECTOR 1089 help 1090 Say Y here to enable the kernel to detect "hung tasks", 1091 which are bugs that cause the task to be stuck in 1092 uninterruptible "D" state indefinitely. 1093 1094 When a hung task is detected, the kernel will print the 1095 current stack trace (which you should report), but the 1096 task will stay in uninterruptible state. If lockdep is 1097 enabled then all held locks will also be reported. This 1098 feature has negligible overhead. 1099 1100config DEFAULT_HUNG_TASK_TIMEOUT 1101 int "Default timeout for hung task detection (in seconds)" 1102 depends on DETECT_HUNG_TASK 1103 default 120 1104 help 1105 This option controls the default timeout (in seconds) used 1106 to determine when a task has become non-responsive and should 1107 be considered hung. 1108 1109 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 1110 sysctl or by writing a value to 1111 /proc/sys/kernel/hung_task_timeout_secs. 1112 1113 A timeout of 0 disables the check. The default is two minutes. 1114 Keeping the default should be fine in most cases. 1115 1116config BOOTPARAM_HUNG_TASK_PANIC 1117 bool "Panic (Reboot) On Hung Tasks" 1118 depends on DETECT_HUNG_TASK 1119 help 1120 Say Y here to enable the kernel to panic on "hung tasks", 1121 which are bugs that cause the kernel to leave a task stuck 1122 in uninterruptible "D" state. 1123 1124 The panic can be used in combination with panic_timeout, 1125 to cause the system to reboot automatically after a 1126 hung task has been detected. This feature is useful for 1127 high-availability systems that have uptime guarantees and 1128 where a hung tasks must be resolved ASAP. 1129 1130 Say N if unsure. 1131 1132config BOOTPARAM_HUNG_TASK_PANIC_VALUE 1133 int 1134 depends on DETECT_HUNG_TASK 1135 range 0 1 1136 default 0 if !BOOTPARAM_HUNG_TASK_PANIC 1137 default 1 if BOOTPARAM_HUNG_TASK_PANIC 1138 1139config WQ_WATCHDOG 1140 bool "Detect Workqueue Stalls" 1141 depends on DEBUG_KERNEL 1142 help 1143 Say Y here to enable stall detection on workqueues. If a 1144 worker pool doesn't make forward progress on a pending work 1145 item for over a given amount of time, 30s by default, a 1146 warning message is printed along with dump of workqueue 1147 state. This can be configured through kernel parameter 1148 "workqueue.watchdog_thresh" and its sysfs counterpart. 1149 1150config TEST_LOCKUP 1151 tristate "Test module to generate lockups" 1152 depends on m 1153 help 1154 This builds the "test_lockup" module that helps to make sure 1155 that watchdogs and lockup detectors are working properly. 1156 1157 Depending on module parameters it could emulate soft or hard 1158 lockup, "hung task", or locking arbitrary lock for a long time. 1159 Also it could generate series of lockups with cooling-down periods. 1160 1161 If unsure, say N. 1162 1163endmenu # "Debug lockups and hangs" 1164 1165menu "Scheduler Debugging" 1166 1167config SCHED_DEBUG 1168 bool "Collect scheduler debugging info" 1169 depends on DEBUG_KERNEL && PROC_FS 1170 default y 1171 help 1172 If you say Y here, the /proc/sched_debug file will be provided 1173 that can help debug the scheduler. The runtime overhead of this 1174 option is minimal. 1175 1176config SCHED_INFO 1177 bool 1178 default n 1179 1180config SCHEDSTATS 1181 bool "Collect scheduler statistics" 1182 depends on DEBUG_KERNEL && PROC_FS 1183 select SCHED_INFO 1184 help 1185 If you say Y here, additional code will be inserted into the 1186 scheduler and related routines to collect statistics about 1187 scheduler behavior and provide them in /proc/schedstat. These 1188 stats may be useful for both tuning and debugging the scheduler 1189 If you aren't debugging the scheduler or trying to tune a specific 1190 application, you can say N to avoid the very slight overhead 1191 this adds. 1192 1193endmenu 1194 1195config DEBUG_TIMEKEEPING 1196 bool "Enable extra timekeeping sanity checking" 1197 help 1198 This option will enable additional timekeeping sanity checks 1199 which may be helpful when diagnosing issues where timekeeping 1200 problems are suspected. 1201 1202 This may include checks in the timekeeping hotpaths, so this 1203 option may have a (very small) performance impact to some 1204 workloads. 1205 1206 If unsure, say N. 1207 1208config DEBUG_PREEMPT 1209 bool "Debug preemptible kernel" 1210 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1211 default y 1212 help 1213 If you say Y here then the kernel will use a debug variant of the 1214 commonly used smp_processor_id() function and will print warnings 1215 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1216 will detect preemption count underflows. 1217 1218menu "Lock Debugging (spinlocks, mutexes, etc...)" 1219 1220config LOCK_DEBUGGING_SUPPORT 1221 bool 1222 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1223 default y 1224 1225config PROVE_LOCKING 1226 bool "Lock debugging: prove locking correctness" 1227 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1228 select LOCKDEP 1229 select DEBUG_SPINLOCK 1230 select DEBUG_MUTEXES 1231 select DEBUG_RT_MUTEXES if RT_MUTEXES 1232 select DEBUG_RWSEMS 1233 select DEBUG_WW_MUTEX_SLOWPATH 1234 select DEBUG_LOCK_ALLOC 1235 select PREEMPT_COUNT if !ARCH_NO_PREEMPT 1236 select TRACE_IRQFLAGS 1237 default n 1238 help 1239 This feature enables the kernel to prove that all locking 1240 that occurs in the kernel runtime is mathematically 1241 correct: that under no circumstance could an arbitrary (and 1242 not yet triggered) combination of observed locking 1243 sequences (on an arbitrary number of CPUs, running an 1244 arbitrary number of tasks and interrupt contexts) cause a 1245 deadlock. 1246 1247 In short, this feature enables the kernel to report locking 1248 related deadlocks before they actually occur. 1249 1250 The proof does not depend on how hard and complex a 1251 deadlock scenario would be to trigger: how many 1252 participant CPUs, tasks and irq-contexts would be needed 1253 for it to trigger. The proof also does not depend on 1254 timing: if a race and a resulting deadlock is possible 1255 theoretically (no matter how unlikely the race scenario 1256 is), it will be proven so and will immediately be 1257 reported by the kernel (once the event is observed that 1258 makes the deadlock theoretically possible). 1259 1260 If a deadlock is impossible (i.e. the locking rules, as 1261 observed by the kernel, are mathematically correct), the 1262 kernel reports nothing. 1263 1264 NOTE: this feature can also be enabled for rwlocks, mutexes 1265 and rwsems - in which case all dependencies between these 1266 different locking variants are observed and mapped too, and 1267 the proof of observed correctness is also maintained for an 1268 arbitrary combination of these separate locking variants. 1269 1270 For more details, see Documentation/locking/lockdep-design.rst. 1271 1272config PROVE_RAW_LOCK_NESTING 1273 bool "Enable raw_spinlock - spinlock nesting checks" 1274 depends on PROVE_LOCKING 1275 default n 1276 help 1277 Enable the raw_spinlock vs. spinlock nesting checks which ensure 1278 that the lock nesting rules for PREEMPT_RT enabled kernels are 1279 not violated. 1280 1281 NOTE: There are known nesting problems. So if you enable this 1282 option expect lockdep splats until these problems have been fully 1283 addressed which is work in progress. This config switch allows to 1284 identify and analyze these problems. It will be removed and the 1285 check permanently enabled once the main issues have been fixed. 1286 1287 If unsure, select N. 1288 1289config LOCK_STAT 1290 bool "Lock usage statistics" 1291 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1292 select LOCKDEP 1293 select DEBUG_SPINLOCK 1294 select DEBUG_MUTEXES 1295 select DEBUG_RT_MUTEXES if RT_MUTEXES 1296 select DEBUG_LOCK_ALLOC 1297 default n 1298 help 1299 This feature enables tracking lock contention points 1300 1301 For more details, see Documentation/locking/lockstat.rst 1302 1303 This also enables lock events required by "perf lock", 1304 subcommand of perf. 1305 If you want to use "perf lock", you also need to turn on 1306 CONFIG_EVENT_TRACING. 1307 1308 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1309 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1310 1311config DEBUG_RT_MUTEXES 1312 bool "RT Mutex debugging, deadlock detection" 1313 depends on DEBUG_KERNEL && RT_MUTEXES 1314 help 1315 This allows rt mutex semantics violations and rt mutex related 1316 deadlocks (lockups) to be detected and reported automatically. 1317 1318config DEBUG_SPINLOCK 1319 bool "Spinlock and rw-lock debugging: basic checks" 1320 depends on DEBUG_KERNEL 1321 select UNINLINE_SPIN_UNLOCK 1322 help 1323 Say Y here and build SMP to catch missing spinlock initialization 1324 and certain other kinds of spinlock errors commonly made. This is 1325 best used in conjunction with the NMI watchdog so that spinlock 1326 deadlocks are also debuggable. 1327 1328config DEBUG_MUTEXES 1329 bool "Mutex debugging: basic checks" 1330 depends on DEBUG_KERNEL 1331 help 1332 This feature allows mutex semantics violations to be detected and 1333 reported. 1334 1335config DEBUG_WW_MUTEX_SLOWPATH 1336 bool "Wait/wound mutex debugging: Slowpath testing" 1337 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1338 select DEBUG_LOCK_ALLOC 1339 select DEBUG_SPINLOCK 1340 select DEBUG_MUTEXES 1341 help 1342 This feature enables slowpath testing for w/w mutex users by 1343 injecting additional -EDEADLK wound/backoff cases. Together with 1344 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1345 will test all possible w/w mutex interface abuse with the 1346 exception of simply not acquiring all the required locks. 1347 Note that this feature can introduce significant overhead, so 1348 it really should not be enabled in a production or distro kernel, 1349 even a debug kernel. If you are a driver writer, enable it. If 1350 you are a distro, do not. 1351 1352config DEBUG_RWSEMS 1353 bool "RW Semaphore debugging: basic checks" 1354 depends on DEBUG_KERNEL 1355 help 1356 This debugging feature allows mismatched rw semaphore locks 1357 and unlocks to be detected and reported. 1358 1359config DEBUG_LOCK_ALLOC 1360 bool "Lock debugging: detect incorrect freeing of live locks" 1361 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1362 select DEBUG_SPINLOCK 1363 select DEBUG_MUTEXES 1364 select DEBUG_RT_MUTEXES if RT_MUTEXES 1365 select LOCKDEP 1366 help 1367 This feature will check whether any held lock (spinlock, rwlock, 1368 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1369 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1370 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1371 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1372 held during task exit. 1373 1374config LOCKDEP 1375 bool 1376 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1377 select STACKTRACE 1378 select KALLSYMS 1379 select KALLSYMS_ALL 1380 1381config LOCKDEP_SMALL 1382 bool 1383 1384config LOCKDEP_BITS 1385 int "Bitsize for MAX_LOCKDEP_ENTRIES" 1386 depends on LOCKDEP && !LOCKDEP_SMALL 1387 range 10 30 1388 default 15 1389 help 1390 Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message. 1391 1392config LOCKDEP_CHAINS_BITS 1393 int "Bitsize for MAX_LOCKDEP_CHAINS" 1394 depends on LOCKDEP && !LOCKDEP_SMALL 1395 range 10 30 1396 default 16 1397 help 1398 Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message. 1399 1400config LOCKDEP_STACK_TRACE_BITS 1401 int "Bitsize for MAX_STACK_TRACE_ENTRIES" 1402 depends on LOCKDEP && !LOCKDEP_SMALL 1403 range 10 30 1404 default 19 1405 help 1406 Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message. 1407 1408config LOCKDEP_STACK_TRACE_HASH_BITS 1409 int "Bitsize for STACK_TRACE_HASH_SIZE" 1410 depends on LOCKDEP && !LOCKDEP_SMALL 1411 range 10 30 1412 default 14 1413 help 1414 Try increasing this value if you need large MAX_STACK_TRACE_ENTRIES. 1415 1416config LOCKDEP_CIRCULAR_QUEUE_BITS 1417 int "Bitsize for elements in circular_queue struct" 1418 depends on LOCKDEP 1419 range 10 30 1420 default 12 1421 help 1422 Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure. 1423 1424config DEBUG_LOCKDEP 1425 bool "Lock dependency engine debugging" 1426 depends on DEBUG_KERNEL && LOCKDEP 1427 select DEBUG_IRQFLAGS 1428 help 1429 If you say Y here, the lock dependency engine will do 1430 additional runtime checks to debug itself, at the price 1431 of more runtime overhead. 1432 1433config DEBUG_ATOMIC_SLEEP 1434 bool "Sleep inside atomic section checking" 1435 select PREEMPT_COUNT 1436 depends on DEBUG_KERNEL 1437 depends on !ARCH_NO_PREEMPT 1438 help 1439 If you say Y here, various routines which may sleep will become very 1440 noisy if they are called inside atomic sections: when a spinlock is 1441 held, inside an rcu read side critical section, inside preempt disabled 1442 sections, inside an interrupt, etc... 1443 1444config DEBUG_LOCKING_API_SELFTESTS 1445 bool "Locking API boot-time self-tests" 1446 depends on DEBUG_KERNEL 1447 help 1448 Say Y here if you want the kernel to run a short self-test during 1449 bootup. The self-test checks whether common types of locking bugs 1450 are detected by debugging mechanisms or not. (if you disable 1451 lock debugging then those bugs won't be detected of course.) 1452 The following locking APIs are covered: spinlocks, rwlocks, 1453 mutexes and rwsems. 1454 1455config LOCK_TORTURE_TEST 1456 tristate "torture tests for locking" 1457 depends on DEBUG_KERNEL 1458 select TORTURE_TEST 1459 help 1460 This option provides a kernel module that runs torture tests 1461 on kernel locking primitives. The kernel module may be built 1462 after the fact on the running kernel to be tested, if desired. 1463 1464 Say Y here if you want kernel locking-primitive torture tests 1465 to be built into the kernel. 1466 Say M if you want these torture tests to build as a module. 1467 Say N if you are unsure. 1468 1469config WW_MUTEX_SELFTEST 1470 tristate "Wait/wound mutex selftests" 1471 help 1472 This option provides a kernel module that runs tests on the 1473 on the struct ww_mutex locking API. 1474 1475 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1476 with this test harness. 1477 1478 Say M if you want these self tests to build as a module. 1479 Say N if you are unsure. 1480 1481config SCF_TORTURE_TEST 1482 tristate "torture tests for smp_call_function*()" 1483 depends on DEBUG_KERNEL 1484 select TORTURE_TEST 1485 help 1486 This option provides a kernel module that runs torture tests 1487 on the smp_call_function() family of primitives. The kernel 1488 module may be built after the fact on the running kernel to 1489 be tested, if desired. 1490 1491config CSD_LOCK_WAIT_DEBUG 1492 bool "Debugging for csd_lock_wait(), called from smp_call_function*()" 1493 depends on DEBUG_KERNEL 1494 depends on 64BIT 1495 default n 1496 help 1497 This option enables debug prints when CPUs are slow to respond 1498 to the smp_call_function*() IPI wrappers. These debug prints 1499 include the IPI handler function currently executing (if any) 1500 and relevant stack traces. 1501 1502endmenu # lock debugging 1503 1504config TRACE_IRQFLAGS 1505 depends on TRACE_IRQFLAGS_SUPPORT 1506 bool 1507 help 1508 Enables hooks to interrupt enabling and disabling for 1509 either tracing or lock debugging. 1510 1511config TRACE_IRQFLAGS_NMI 1512 def_bool y 1513 depends on TRACE_IRQFLAGS 1514 depends on TRACE_IRQFLAGS_NMI_SUPPORT 1515 1516config DEBUG_IRQFLAGS 1517 bool "Debug IRQ flag manipulation" 1518 help 1519 Enables checks for potentially unsafe enabling or disabling of 1520 interrupts, such as calling raw_local_irq_restore() when interrupts 1521 are enabled. 1522 1523config STACKTRACE 1524 bool "Stack backtrace support" 1525 depends on STACKTRACE_SUPPORT 1526 help 1527 This option causes the kernel to create a /proc/pid/stack for 1528 every process, showing its current stack trace. 1529 It is also used by various kernel debugging features that require 1530 stack trace generation. 1531 1532config WARN_ALL_UNSEEDED_RANDOM 1533 bool "Warn for all uses of unseeded randomness" 1534 default n 1535 help 1536 Some parts of the kernel contain bugs relating to their use of 1537 cryptographically secure random numbers before it's actually possible 1538 to generate those numbers securely. This setting ensures that these 1539 flaws don't go unnoticed, by enabling a message, should this ever 1540 occur. This will allow people with obscure setups to know when things 1541 are going wrong, so that they might contact developers about fixing 1542 it. 1543 1544 Unfortunately, on some models of some architectures getting 1545 a fully seeded CRNG is extremely difficult, and so this can 1546 result in dmesg getting spammed for a surprisingly long 1547 time. This is really bad from a security perspective, and 1548 so architecture maintainers really need to do what they can 1549 to get the CRNG seeded sooner after the system is booted. 1550 However, since users cannot do anything actionable to 1551 address this, by default the kernel will issue only a single 1552 warning for the first use of unseeded randomness. 1553 1554 Say Y here if you want to receive warnings for all uses of 1555 unseeded randomness. This will be of use primarily for 1556 those developers interested in improving the security of 1557 Linux kernels running on their architecture (or 1558 subarchitecture). 1559 1560config DEBUG_KOBJECT 1561 bool "kobject debugging" 1562 depends on DEBUG_KERNEL 1563 help 1564 If you say Y here, some extra kobject debugging messages will be sent 1565 to the syslog. 1566 1567config DEBUG_KOBJECT_RELEASE 1568 bool "kobject release debugging" 1569 depends on DEBUG_OBJECTS_TIMERS 1570 help 1571 kobjects are reference counted objects. This means that their 1572 last reference count put is not predictable, and the kobject can 1573 live on past the point at which a driver decides to drop it's 1574 initial reference to the kobject gained on allocation. An 1575 example of this would be a struct device which has just been 1576 unregistered. 1577 1578 However, some buggy drivers assume that after such an operation, 1579 the memory backing the kobject can be immediately freed. This 1580 goes completely against the principles of a refcounted object. 1581 1582 If you say Y here, the kernel will delay the release of kobjects 1583 on the last reference count to improve the visibility of this 1584 kind of kobject release bug. 1585 1586config HAVE_DEBUG_BUGVERBOSE 1587 bool 1588 1589menu "Debug kernel data structures" 1590 1591config DEBUG_LIST 1592 bool "Debug linked list manipulation" 1593 depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION 1594 help 1595 Enable this to turn on extended checks in the linked-list 1596 walking routines. 1597 1598 If unsure, say N. 1599 1600config DEBUG_PLIST 1601 bool "Debug priority linked list manipulation" 1602 depends on DEBUG_KERNEL 1603 help 1604 Enable this to turn on extended checks in the priority-ordered 1605 linked-list (plist) walking routines. This checks the entire 1606 list multiple times during each manipulation. 1607 1608 If unsure, say N. 1609 1610config DEBUG_SG 1611 bool "Debug SG table operations" 1612 depends on DEBUG_KERNEL 1613 help 1614 Enable this to turn on checks on scatter-gather tables. This can 1615 help find problems with drivers that do not properly initialize 1616 their sg tables. 1617 1618 If unsure, say N. 1619 1620config DEBUG_NOTIFIERS 1621 bool "Debug notifier call chains" 1622 depends on DEBUG_KERNEL 1623 help 1624 Enable this to turn on sanity checking for notifier call chains. 1625 This is most useful for kernel developers to make sure that 1626 modules properly unregister themselves from notifier chains. 1627 This is a relatively cheap check but if you care about maximum 1628 performance, say N. 1629 1630config BUG_ON_DATA_CORRUPTION 1631 bool "Trigger a BUG when data corruption is detected" 1632 select DEBUG_LIST 1633 help 1634 Select this option if the kernel should BUG when it encounters 1635 data corruption in kernel memory structures when they get checked 1636 for validity. 1637 1638 If unsure, say N. 1639 1640endmenu 1641 1642config DEBUG_CREDENTIALS 1643 bool "Debug credential management" 1644 depends on DEBUG_KERNEL 1645 help 1646 Enable this to turn on some debug checking for credential 1647 management. The additional code keeps track of the number of 1648 pointers from task_structs to any given cred struct, and checks to 1649 see that this number never exceeds the usage count of the cred 1650 struct. 1651 1652 Furthermore, if SELinux is enabled, this also checks that the 1653 security pointer in the cred struct is never seen to be invalid. 1654 1655 If unsure, say N. 1656 1657source "kernel/rcu/Kconfig.debug" 1658 1659config DEBUG_WQ_FORCE_RR_CPU 1660 bool "Force round-robin CPU selection for unbound work items" 1661 depends on DEBUG_KERNEL 1662 default n 1663 help 1664 Workqueue used to implicitly guarantee that work items queued 1665 without explicit CPU specified are put on the local CPU. This 1666 guarantee is no longer true and while local CPU is still 1667 preferred work items may be put on foreign CPUs. Kernel 1668 parameter "workqueue.debug_force_rr_cpu" is added to force 1669 round-robin CPU selection to flush out usages which depend on the 1670 now broken guarantee. This config option enables the debug 1671 feature by default. When enabled, memory and cache locality will 1672 be impacted. 1673 1674config DEBUG_BLOCK_EXT_DEVT 1675 bool "Force extended block device numbers and spread them" 1676 depends on DEBUG_KERNEL 1677 depends on BLOCK 1678 default n 1679 help 1680 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON 1681 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT 1682 YOU ARE DOING. Distros, please enable this and fix whatever 1683 is broken. 1684 1685 Conventionally, block device numbers are allocated from 1686 predetermined contiguous area. However, extended block area 1687 may introduce non-contiguous block device numbers. This 1688 option forces most block device numbers to be allocated from 1689 the extended space and spreads them to discover kernel or 1690 userland code paths which assume predetermined contiguous 1691 device number allocation. 1692 1693 Note that turning on this debug option shuffles all the 1694 device numbers for all IDE and SCSI devices including libata 1695 ones, so root partition specified using device number 1696 directly (via rdev or root=MAJ:MIN) won't work anymore. 1697 Textual device names (root=/dev/sdXn) will continue to work. 1698 1699 Say N if you are unsure. 1700 1701config CPU_HOTPLUG_STATE_CONTROL 1702 bool "Enable CPU hotplug state control" 1703 depends on DEBUG_KERNEL 1704 depends on HOTPLUG_CPU 1705 default n 1706 help 1707 Allows to write steps between "offline" and "online" to the CPUs 1708 sysfs target file so states can be stepped granular. This is a debug 1709 option for now as the hotplug machinery cannot be stopped and 1710 restarted at arbitrary points yet. 1711 1712 Say N if your are unsure. 1713 1714config LATENCYTOP 1715 bool "Latency measuring infrastructure" 1716 depends on DEBUG_KERNEL 1717 depends on STACKTRACE_SUPPORT 1718 depends on PROC_FS 1719 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 1720 select KALLSYMS 1721 select KALLSYMS_ALL 1722 select STACKTRACE 1723 select SCHEDSTATS 1724 help 1725 Enable this option if you want to use the LatencyTOP tool 1726 to find out which userspace is blocking on what kernel operations. 1727 1728source "kernel/trace/Kconfig" 1729 1730config PROVIDE_OHCI1394_DMA_INIT 1731 bool "Remote debugging over FireWire early on boot" 1732 depends on PCI && X86 1733 help 1734 If you want to debug problems which hang or crash the kernel early 1735 on boot and the crashing machine has a FireWire port, you can use 1736 this feature to remotely access the memory of the crashed machine 1737 over FireWire. This employs remote DMA as part of the OHCI1394 1738 specification which is now the standard for FireWire controllers. 1739 1740 With remote DMA, you can monitor the printk buffer remotely using 1741 firescope and access all memory below 4GB using fireproxy from gdb. 1742 Even controlling a kernel debugger is possible using remote DMA. 1743 1744 Usage: 1745 1746 If ohci1394_dma=early is used as boot parameter, it will initialize 1747 all OHCI1394 controllers which are found in the PCI config space. 1748 1749 As all changes to the FireWire bus such as enabling and disabling 1750 devices cause a bus reset and thereby disable remote DMA for all 1751 devices, be sure to have the cable plugged and FireWire enabled on 1752 the debugging host before booting the debug target for debugging. 1753 1754 This code (~1k) is freed after boot. By then, the firewire stack 1755 in charge of the OHCI-1394 controllers should be used instead. 1756 1757 See Documentation/core-api/debugging-via-ohci1394.rst for more information. 1758 1759source "samples/Kconfig" 1760 1761config ARCH_HAS_DEVMEM_IS_ALLOWED 1762 bool 1763 1764config STRICT_DEVMEM 1765 bool "Filter access to /dev/mem" 1766 depends on MMU && DEVMEM 1767 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED 1768 default y if PPC || X86 || ARM64 1769 help 1770 If this option is disabled, you allow userspace (root) access to all 1771 of memory, including kernel and userspace memory. Accidental 1772 access to this is obviously disastrous, but specific access can 1773 be used by people debugging the kernel. Note that with PAT support 1774 enabled, even in this case there are restrictions on /dev/mem 1775 use due to the cache aliasing requirements. 1776 1777 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 1778 file only allows userspace access to PCI space and the BIOS code and 1779 data regions. This is sufficient for dosemu and X and all common 1780 users of /dev/mem. 1781 1782 If in doubt, say Y. 1783 1784config IO_STRICT_DEVMEM 1785 bool "Filter I/O access to /dev/mem" 1786 depends on STRICT_DEVMEM 1787 help 1788 If this option is disabled, you allow userspace (root) access to all 1789 io-memory regardless of whether a driver is actively using that 1790 range. Accidental access to this is obviously disastrous, but 1791 specific access can be used by people debugging kernel drivers. 1792 1793 If this option is switched on, the /dev/mem file only allows 1794 userspace access to *idle* io-memory ranges (see /proc/iomem) This 1795 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 1796 if the driver using a given range cannot be disabled. 1797 1798 If in doubt, say Y. 1799 1800menu "$(SRCARCH) Debugging" 1801 1802source "arch/$(SRCARCH)/Kconfig.debug" 1803 1804endmenu 1805 1806menu "Kernel Testing and Coverage" 1807 1808source "lib/kunit/Kconfig" 1809 1810config NOTIFIER_ERROR_INJECTION 1811 tristate "Notifier error injection" 1812 depends on DEBUG_KERNEL 1813 select DEBUG_FS 1814 help 1815 This option provides the ability to inject artificial errors to 1816 specified notifier chain callbacks. It is useful to test the error 1817 handling of notifier call chain failures. 1818 1819 Say N if unsure. 1820 1821config PM_NOTIFIER_ERROR_INJECT 1822 tristate "PM notifier error injection module" 1823 depends on PM && NOTIFIER_ERROR_INJECTION 1824 default m if PM_DEBUG 1825 help 1826 This option provides the ability to inject artificial errors to 1827 PM notifier chain callbacks. It is controlled through debugfs 1828 interface /sys/kernel/debug/notifier-error-inject/pm 1829 1830 If the notifier call chain should be failed with some events 1831 notified, write the error code to "actions/<notifier event>/error". 1832 1833 Example: Inject PM suspend error (-12 = -ENOMEM) 1834 1835 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1836 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1837 # echo mem > /sys/power/state 1838 bash: echo: write error: Cannot allocate memory 1839 1840 To compile this code as a module, choose M here: the module will 1841 be called pm-notifier-error-inject. 1842 1843 If unsure, say N. 1844 1845config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1846 tristate "OF reconfig notifier error injection module" 1847 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1848 help 1849 This option provides the ability to inject artificial errors to 1850 OF reconfig notifier chain callbacks. It is controlled 1851 through debugfs interface under 1852 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1853 1854 If the notifier call chain should be failed with some events 1855 notified, write the error code to "actions/<notifier event>/error". 1856 1857 To compile this code as a module, choose M here: the module will 1858 be called of-reconfig-notifier-error-inject. 1859 1860 If unsure, say N. 1861 1862config NETDEV_NOTIFIER_ERROR_INJECT 1863 tristate "Netdev notifier error injection module" 1864 depends on NET && NOTIFIER_ERROR_INJECTION 1865 help 1866 This option provides the ability to inject artificial errors to 1867 netdevice notifier chain callbacks. It is controlled through debugfs 1868 interface /sys/kernel/debug/notifier-error-inject/netdev 1869 1870 If the notifier call chain should be failed with some events 1871 notified, write the error code to "actions/<notifier event>/error". 1872 1873 Example: Inject netdevice mtu change error (-22 = -EINVAL) 1874 1875 # cd /sys/kernel/debug/notifier-error-inject/netdev 1876 # echo -22 > actions/NETDEV_CHANGEMTU/error 1877 # ip link set eth0 mtu 1024 1878 RTNETLINK answers: Invalid argument 1879 1880 To compile this code as a module, choose M here: the module will 1881 be called netdev-notifier-error-inject. 1882 1883 If unsure, say N. 1884 1885config FUNCTION_ERROR_INJECTION 1886 def_bool y 1887 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 1888 1889config FAULT_INJECTION 1890 bool "Fault-injection framework" 1891 depends on DEBUG_KERNEL 1892 help 1893 Provide fault-injection framework. 1894 For more details, see Documentation/fault-injection/. 1895 1896config FAILSLAB 1897 bool "Fault-injection capability for kmalloc" 1898 depends on FAULT_INJECTION 1899 depends on SLAB || SLUB 1900 help 1901 Provide fault-injection capability for kmalloc. 1902 1903config FAIL_PAGE_ALLOC 1904 bool "Fault-injection capability for alloc_pages()" 1905 depends on FAULT_INJECTION 1906 help 1907 Provide fault-injection capability for alloc_pages(). 1908 1909config FAULT_INJECTION_USERCOPY 1910 bool "Fault injection capability for usercopy functions" 1911 depends on FAULT_INJECTION 1912 help 1913 Provides fault-injection capability to inject failures 1914 in usercopy functions (copy_from_user(), get_user(), ...). 1915 1916config FAIL_MAKE_REQUEST 1917 bool "Fault-injection capability for disk IO" 1918 depends on FAULT_INJECTION && BLOCK 1919 help 1920 Provide fault-injection capability for disk IO. 1921 1922config FAIL_IO_TIMEOUT 1923 bool "Fault-injection capability for faking disk interrupts" 1924 depends on FAULT_INJECTION && BLOCK 1925 help 1926 Provide fault-injection capability on end IO handling. This 1927 will make the block layer "forget" an interrupt as configured, 1928 thus exercising the error handling. 1929 1930 Only works with drivers that use the generic timeout handling, 1931 for others it won't do anything. 1932 1933config FAIL_FUTEX 1934 bool "Fault-injection capability for futexes" 1935 select DEBUG_FS 1936 depends on FAULT_INJECTION && FUTEX 1937 help 1938 Provide fault-injection capability for futexes. 1939 1940config FAULT_INJECTION_DEBUG_FS 1941 bool "Debugfs entries for fault-injection capabilities" 1942 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 1943 help 1944 Enable configuration of fault-injection capabilities via debugfs. 1945 1946config FAIL_FUNCTION 1947 bool "Fault-injection capability for functions" 1948 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 1949 help 1950 Provide function-based fault-injection capability. 1951 This will allow you to override a specific function with a return 1952 with given return value. As a result, function caller will see 1953 an error value and have to handle it. This is useful to test the 1954 error handling in various subsystems. 1955 1956config FAIL_MMC_REQUEST 1957 bool "Fault-injection capability for MMC IO" 1958 depends on FAULT_INJECTION_DEBUG_FS && MMC 1959 help 1960 Provide fault-injection capability for MMC IO. 1961 This will make the mmc core return data errors. This is 1962 useful to test the error handling in the mmc block device 1963 and to test how the mmc host driver handles retries from 1964 the block device. 1965 1966config FAULT_INJECTION_STACKTRACE_FILTER 1967 bool "stacktrace filter for fault-injection capabilities" 1968 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 1969 depends on !X86_64 1970 select STACKTRACE 1971 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 1972 help 1973 Provide stacktrace filter for fault-injection capabilities 1974 1975config ARCH_HAS_KCOV 1976 bool 1977 help 1978 An architecture should select this when it can successfully 1979 build and run with CONFIG_KCOV. This typically requires 1980 disabling instrumentation for some early boot code. 1981 1982config CC_HAS_SANCOV_TRACE_PC 1983 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 1984 1985 1986config KCOV 1987 bool "Code coverage for fuzzing" 1988 depends on ARCH_HAS_KCOV 1989 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 1990 select DEBUG_FS 1991 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 1992 help 1993 KCOV exposes kernel code coverage information in a form suitable 1994 for coverage-guided fuzzing (randomized testing). 1995 1996 If RANDOMIZE_BASE is enabled, PC values will not be stable across 1997 different machines and across reboots. If you need stable PC values, 1998 disable RANDOMIZE_BASE. 1999 2000 For more details, see Documentation/dev-tools/kcov.rst. 2001 2002config KCOV_ENABLE_COMPARISONS 2003 bool "Enable comparison operands collection by KCOV" 2004 depends on KCOV 2005 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 2006 help 2007 KCOV also exposes operands of every comparison in the instrumented 2008 code along with operand sizes and PCs of the comparison instructions. 2009 These operands can be used by fuzzing engines to improve the quality 2010 of fuzzing coverage. 2011 2012config KCOV_INSTRUMENT_ALL 2013 bool "Instrument all code by default" 2014 depends on KCOV 2015 default y 2016 help 2017 If you are doing generic system call fuzzing (like e.g. syzkaller), 2018 then you will want to instrument the whole kernel and you should 2019 say y here. If you are doing more targeted fuzzing (like e.g. 2020 filesystem fuzzing with AFL) then you will want to enable coverage 2021 for more specific subsets of files, and should say n here. 2022 2023config KCOV_IRQ_AREA_SIZE 2024 hex "Size of interrupt coverage collection area in words" 2025 depends on KCOV 2026 default 0x40000 2027 help 2028 KCOV uses preallocated per-cpu areas to collect coverage from 2029 soft interrupts. This specifies the size of those areas in the 2030 number of unsigned long words. 2031 2032menuconfig RUNTIME_TESTING_MENU 2033 bool "Runtime Testing" 2034 def_bool y 2035 2036if RUNTIME_TESTING_MENU 2037 2038config LKDTM 2039 tristate "Linux Kernel Dump Test Tool Module" 2040 depends on DEBUG_FS 2041 help 2042 This module enables testing of the different dumping mechanisms by 2043 inducing system failures at predefined crash points. 2044 If you don't need it: say N 2045 Choose M here to compile this code as a module. The module will be 2046 called lkdtm. 2047 2048 Documentation on how to use the module can be found in 2049 Documentation/fault-injection/provoke-crashes.rst 2050 2051config TEST_LIST_SORT 2052 tristate "Linked list sorting test" if !KUNIT_ALL_TESTS 2053 depends on KUNIT 2054 default KUNIT_ALL_TESTS 2055 help 2056 Enable this to turn on 'list_sort()' function test. This test is 2057 executed only once during system boot (so affects only boot time), 2058 or at module load time. 2059 2060 If unsure, say N. 2061 2062config TEST_MIN_HEAP 2063 tristate "Min heap test" 2064 depends on DEBUG_KERNEL || m 2065 help 2066 Enable this to turn on min heap function tests. This test is 2067 executed only once during system boot (so affects only boot time), 2068 or at module load time. 2069 2070 If unsure, say N. 2071 2072config TEST_SORT 2073 tristate "Array-based sort test" 2074 depends on DEBUG_KERNEL || m 2075 help 2076 This option enables the self-test function of 'sort()' at boot, 2077 or at module load time. 2078 2079 If unsure, say N. 2080 2081config TEST_DIV64 2082 tristate "64bit/32bit division and modulo test" 2083 depends on DEBUG_KERNEL || m 2084 help 2085 Enable this to turn on 'do_div()' function test. This test is 2086 executed only once during system boot (so affects only boot time), 2087 or at module load time. 2088 2089 If unsure, say N. 2090 2091config KPROBES_SANITY_TEST 2092 bool "Kprobes sanity tests" 2093 depends on DEBUG_KERNEL 2094 depends on KPROBES 2095 help 2096 This option provides for testing basic kprobes functionality on 2097 boot. Samples of kprobe and kretprobe are inserted and 2098 verified for functionality. 2099 2100 Say N if you are unsure. 2101 2102config BACKTRACE_SELF_TEST 2103 tristate "Self test for the backtrace code" 2104 depends on DEBUG_KERNEL 2105 help 2106 This option provides a kernel module that can be used to test 2107 the kernel stack backtrace code. This option is not useful 2108 for distributions or general kernels, but only for kernel 2109 developers working on architecture code. 2110 2111 Note that if you want to also test saved backtraces, you will 2112 have to enable STACKTRACE as well. 2113 2114 Say N if you are unsure. 2115 2116config RBTREE_TEST 2117 tristate "Red-Black tree test" 2118 depends on DEBUG_KERNEL 2119 help 2120 A benchmark measuring the performance of the rbtree library. 2121 Also includes rbtree invariant checks. 2122 2123config REED_SOLOMON_TEST 2124 tristate "Reed-Solomon library test" 2125 depends on DEBUG_KERNEL || m 2126 select REED_SOLOMON 2127 select REED_SOLOMON_ENC16 2128 select REED_SOLOMON_DEC16 2129 help 2130 This option enables the self-test function of rslib at boot, 2131 or at module load time. 2132 2133 If unsure, say N. 2134 2135config INTERVAL_TREE_TEST 2136 tristate "Interval tree test" 2137 depends on DEBUG_KERNEL 2138 select INTERVAL_TREE 2139 help 2140 A benchmark measuring the performance of the interval tree library 2141 2142config PERCPU_TEST 2143 tristate "Per cpu operations test" 2144 depends on m && DEBUG_KERNEL 2145 help 2146 Enable this option to build test module which validates per-cpu 2147 operations. 2148 2149 If unsure, say N. 2150 2151config ATOMIC64_SELFTEST 2152 tristate "Perform an atomic64_t self-test" 2153 help 2154 Enable this option to test the atomic64_t functions at boot or 2155 at module load time. 2156 2157 If unsure, say N. 2158 2159config ASYNC_RAID6_TEST 2160 tristate "Self test for hardware accelerated raid6 recovery" 2161 depends on ASYNC_RAID6_RECOV 2162 select ASYNC_MEMCPY 2163 help 2164 This is a one-shot self test that permutes through the 2165 recovery of all the possible two disk failure scenarios for a 2166 N-disk array. Recovery is performed with the asynchronous 2167 raid6 recovery routines, and will optionally use an offload 2168 engine if one is available. 2169 2170 If unsure, say N. 2171 2172config TEST_HEXDUMP 2173 tristate "Test functions located in the hexdump module at runtime" 2174 2175config TEST_STRING_HELPERS 2176 tristate "Test functions located in the string_helpers module at runtime" 2177 2178config TEST_STRSCPY 2179 tristate "Test strscpy*() family of functions at runtime" 2180 2181config TEST_KSTRTOX 2182 tristate "Test kstrto*() family of functions at runtime" 2183 2184config TEST_PRINTF 2185 tristate "Test printf() family of functions at runtime" 2186 2187config TEST_SCANF 2188 tristate "Test scanf() family of functions at runtime" 2189 2190config TEST_BITMAP 2191 tristate "Test bitmap_*() family of functions at runtime" 2192 help 2193 Enable this option to test the bitmap functions at boot. 2194 2195 If unsure, say N. 2196 2197config TEST_UUID 2198 tristate "Test functions located in the uuid module at runtime" 2199 2200config TEST_XARRAY 2201 tristate "Test the XArray code at runtime" 2202 2203config TEST_OVERFLOW 2204 tristate "Test check_*_overflow() functions at runtime" 2205 2206config TEST_RHASHTABLE 2207 tristate "Perform selftest on resizable hash table" 2208 help 2209 Enable this option to test the rhashtable functions at boot. 2210 2211 If unsure, say N. 2212 2213config TEST_HASH 2214 tristate "Perform selftest on hash functions" 2215 help 2216 Enable this option to test the kernel's integer (<linux/hash.h>), 2217 string (<linux/stringhash.h>), and siphash (<linux/siphash.h>) 2218 hash functions on boot (or module load). 2219 2220 This is intended to help people writing architecture-specific 2221 optimized versions. If unsure, say N. 2222 2223config TEST_IDA 2224 tristate "Perform selftest on IDA functions" 2225 2226config TEST_PARMAN 2227 tristate "Perform selftest on priority array manager" 2228 depends on PARMAN 2229 help 2230 Enable this option to test priority array manager on boot 2231 (or module load). 2232 2233 If unsure, say N. 2234 2235config TEST_IRQ_TIMINGS 2236 bool "IRQ timings selftest" 2237 depends on IRQ_TIMINGS 2238 help 2239 Enable this option to test the irq timings code on boot. 2240 2241 If unsure, say N. 2242 2243config TEST_LKM 2244 tristate "Test module loading with 'hello world' module" 2245 depends on m 2246 help 2247 This builds the "test_module" module that emits "Hello, world" 2248 on printk when loaded. It is designed to be used for basic 2249 evaluation of the module loading subsystem (for example when 2250 validating module verification). It lacks any extra dependencies, 2251 and will not normally be loaded by the system unless explicitly 2252 requested by name. 2253 2254 If unsure, say N. 2255 2256config TEST_BITOPS 2257 tristate "Test module for compilation of bitops operations" 2258 depends on m 2259 help 2260 This builds the "test_bitops" module that is much like the 2261 TEST_LKM module except that it does a basic exercise of the 2262 set/clear_bit macros and get_count_order/long to make sure there are 2263 no compiler warnings from C=1 sparse checker or -Wextra 2264 compilations. It has no dependencies and doesn't run or load unless 2265 explicitly requested by name. for example: modprobe test_bitops. 2266 2267 If unsure, say N. 2268 2269config TEST_VMALLOC 2270 tristate "Test module for stress/performance analysis of vmalloc allocator" 2271 default n 2272 depends on MMU 2273 depends on m 2274 help 2275 This builds the "test_vmalloc" module that should be used for 2276 stress and performance analysis. So, any new change for vmalloc 2277 subsystem can be evaluated from performance and stability point 2278 of view. 2279 2280 If unsure, say N. 2281 2282config TEST_USER_COPY 2283 tristate "Test user/kernel boundary protections" 2284 depends on m 2285 help 2286 This builds the "test_user_copy" module that runs sanity checks 2287 on the copy_to/from_user infrastructure, making sure basic 2288 user/kernel boundary testing is working. If it fails to load, 2289 a regression has been detected in the user/kernel memory boundary 2290 protections. 2291 2292 If unsure, say N. 2293 2294config TEST_BPF 2295 tristate "Test BPF filter functionality" 2296 depends on m && NET 2297 help 2298 This builds the "test_bpf" module that runs various test vectors 2299 against the BPF interpreter or BPF JIT compiler depending on the 2300 current setting. This is in particular useful for BPF JIT compiler 2301 development, but also to run regression tests against changes in 2302 the interpreter code. It also enables test stubs for eBPF maps and 2303 verifier used by user space verifier testsuite. 2304 2305 If unsure, say N. 2306 2307config TEST_BLACKHOLE_DEV 2308 tristate "Test blackhole netdev functionality" 2309 depends on m && NET 2310 help 2311 This builds the "test_blackhole_dev" module that validates the 2312 data path through this blackhole netdev. 2313 2314 If unsure, say N. 2315 2316config FIND_BIT_BENCHMARK 2317 tristate "Test find_bit functions" 2318 help 2319 This builds the "test_find_bit" module that measure find_*_bit() 2320 functions performance. 2321 2322 If unsure, say N. 2323 2324config TEST_FIRMWARE 2325 tristate "Test firmware loading via userspace interface" 2326 depends on FW_LOADER 2327 help 2328 This builds the "test_firmware" module that creates a userspace 2329 interface for testing firmware loading. This can be used to 2330 control the triggering of firmware loading without needing an 2331 actual firmware-using device. The contents can be rechecked by 2332 userspace. 2333 2334 If unsure, say N. 2335 2336config TEST_SYSCTL 2337 tristate "sysctl test driver" 2338 depends on PROC_SYSCTL 2339 help 2340 This builds the "test_sysctl" module. This driver enables to test the 2341 proc sysctl interfaces available to drivers safely without affecting 2342 production knobs which might alter system functionality. 2343 2344 If unsure, say N. 2345 2346config BITFIELD_KUNIT 2347 tristate "KUnit test bitfield functions at runtime" 2348 depends on KUNIT 2349 help 2350 Enable this option to test the bitfield functions at boot. 2351 2352 KUnit tests run during boot and output the results to the debug log 2353 in TAP format (http://testanything.org/). Only useful for kernel devs 2354 running the KUnit test harness, and not intended for inclusion into a 2355 production build. 2356 2357 For more information on KUnit and unit tests in general please refer 2358 to the KUnit documentation in Documentation/dev-tools/kunit/. 2359 2360 If unsure, say N. 2361 2362config RESOURCE_KUNIT_TEST 2363 tristate "KUnit test for resource API" 2364 depends on KUNIT 2365 help 2366 This builds the resource API unit test. 2367 Tests the logic of API provided by resource.c and ioport.h. 2368 For more information on KUnit and unit tests in general please refer 2369 to the KUnit documentation in Documentation/dev-tools/kunit/. 2370 2371 If unsure, say N. 2372 2373config SYSCTL_KUNIT_TEST 2374 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS 2375 depends on KUNIT 2376 default KUNIT_ALL_TESTS 2377 help 2378 This builds the proc sysctl unit test, which runs on boot. 2379 Tests the API contract and implementation correctness of sysctl. 2380 For more information on KUnit and unit tests in general please refer 2381 to the KUnit documentation in Documentation/dev-tools/kunit/. 2382 2383 If unsure, say N. 2384 2385config LIST_KUNIT_TEST 2386 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS 2387 depends on KUNIT 2388 default KUNIT_ALL_TESTS 2389 help 2390 This builds the linked list KUnit test suite. 2391 It tests that the API and basic functionality of the list_head type 2392 and associated macros. 2393 2394 KUnit tests run during boot and output the results to the debug log 2395 in TAP format (https://testanything.org/). Only useful for kernel devs 2396 running the KUnit test harness, and not intended for inclusion into a 2397 production build. 2398 2399 For more information on KUnit and unit tests in general please refer 2400 to the KUnit documentation in Documentation/dev-tools/kunit/. 2401 2402 If unsure, say N. 2403 2404config LINEAR_RANGES_TEST 2405 tristate "KUnit test for linear_ranges" 2406 depends on KUNIT 2407 select LINEAR_RANGES 2408 help 2409 This builds the linear_ranges unit test, which runs on boot. 2410 Tests the linear_ranges logic correctness. 2411 For more information on KUnit and unit tests in general please refer 2412 to the KUnit documentation in Documentation/dev-tools/kunit/. 2413 2414 If unsure, say N. 2415 2416config CMDLINE_KUNIT_TEST 2417 tristate "KUnit test for cmdline API" 2418 depends on KUNIT 2419 help 2420 This builds the cmdline API unit test. 2421 Tests the logic of API provided by cmdline.c. 2422 For more information on KUnit and unit tests in general please refer 2423 to the KUnit documentation in Documentation/dev-tools/kunit/. 2424 2425 If unsure, say N. 2426 2427config BITS_TEST 2428 tristate "KUnit test for bits.h" 2429 depends on KUNIT 2430 help 2431 This builds the bits unit test. 2432 Tests the logic of macros defined in bits.h. 2433 For more information on KUnit and unit tests in general please refer 2434 to the KUnit documentation in Documentation/dev-tools/kunit/. 2435 2436 If unsure, say N. 2437 2438config SLUB_KUNIT_TEST 2439 tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS 2440 depends on SLUB_DEBUG && KUNIT 2441 default KUNIT_ALL_TESTS 2442 help 2443 This builds SLUB allocator unit test. 2444 Tests SLUB cache debugging functionality. 2445 For more information on KUnit and unit tests in general please refer 2446 to the KUnit documentation in Documentation/dev-tools/kunit/. 2447 2448 If unsure, say N. 2449 2450config RATIONAL_KUNIT_TEST 2451 tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS 2452 depends on KUNIT 2453 select RATIONAL 2454 default KUNIT_ALL_TESTS 2455 help 2456 This builds the rational math unit test. 2457 For more information on KUnit and unit tests in general please refer 2458 to the KUnit documentation in Documentation/dev-tools/kunit/. 2459 2460 If unsure, say N. 2461 2462config TEST_UDELAY 2463 tristate "udelay test driver" 2464 help 2465 This builds the "udelay_test" module that helps to make sure 2466 that udelay() is working properly. 2467 2468 If unsure, say N. 2469 2470config TEST_STATIC_KEYS 2471 tristate "Test static keys" 2472 depends on m 2473 help 2474 Test the static key interfaces. 2475 2476 If unsure, say N. 2477 2478config TEST_KMOD 2479 tristate "kmod stress tester" 2480 depends on m 2481 depends on NETDEVICES && NET_CORE && INET # for TUN 2482 depends on BLOCK 2483 select TEST_LKM 2484 select XFS_FS 2485 select TUN 2486 select BTRFS_FS 2487 help 2488 Test the kernel's module loading mechanism: kmod. kmod implements 2489 support to load modules using the Linux kernel's usermode helper. 2490 This test provides a series of tests against kmod. 2491 2492 Although technically you can either build test_kmod as a module or 2493 into the kernel we disallow building it into the kernel since 2494 it stress tests request_module() and this will very likely cause 2495 some issues by taking over precious threads available from other 2496 module load requests, ultimately this could be fatal. 2497 2498 To run tests run: 2499 2500 tools/testing/selftests/kmod/kmod.sh --help 2501 2502 If unsure, say N. 2503 2504config TEST_DEBUG_VIRTUAL 2505 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 2506 depends on DEBUG_VIRTUAL 2507 help 2508 Test the kernel's ability to detect incorrect calls to 2509 virt_to_phys() done against the non-linear part of the 2510 kernel's virtual address map. 2511 2512 If unsure, say N. 2513 2514config TEST_MEMCAT_P 2515 tristate "Test memcat_p() helper function" 2516 help 2517 Test the memcat_p() helper for correctly merging two 2518 pointer arrays together. 2519 2520 If unsure, say N. 2521 2522config TEST_LIVEPATCH 2523 tristate "Test livepatching" 2524 default n 2525 depends on DYNAMIC_DEBUG 2526 depends on LIVEPATCH 2527 depends on m 2528 help 2529 Test kernel livepatching features for correctness. The tests will 2530 load test modules that will be livepatched in various scenarios. 2531 2532 To run all the livepatching tests: 2533 2534 make -C tools/testing/selftests TARGETS=livepatch run_tests 2535 2536 Alternatively, individual tests may be invoked: 2537 2538 tools/testing/selftests/livepatch/test-callbacks.sh 2539 tools/testing/selftests/livepatch/test-livepatch.sh 2540 tools/testing/selftests/livepatch/test-shadow-vars.sh 2541 2542 If unsure, say N. 2543 2544config TEST_OBJAGG 2545 tristate "Perform selftest on object aggreration manager" 2546 default n 2547 depends on OBJAGG 2548 help 2549 Enable this option to test object aggregation manager on boot 2550 (or module load). 2551 2552 2553config TEST_STACKINIT 2554 tristate "Test level of stack variable initialization" 2555 help 2556 Test if the kernel is zero-initializing stack variables and 2557 padding. Coverage is controlled by compiler flags, 2558 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2559 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2560 2561 If unsure, say N. 2562 2563config TEST_MEMINIT 2564 tristate "Test heap/page initialization" 2565 help 2566 Test if the kernel is zero-initializing heap and page allocations. 2567 This can be useful to test init_on_alloc and init_on_free features. 2568 2569 If unsure, say N. 2570 2571config TEST_HMM 2572 tristate "Test HMM (Heterogeneous Memory Management)" 2573 depends on TRANSPARENT_HUGEPAGE 2574 depends on DEVICE_PRIVATE 2575 select HMM_MIRROR 2576 select MMU_NOTIFIER 2577 help 2578 This is a pseudo device driver solely for testing HMM. 2579 Say M here if you want to build the HMM test module. 2580 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests. 2581 2582 If unsure, say N. 2583 2584config TEST_FREE_PAGES 2585 tristate "Test freeing pages" 2586 help 2587 Test that a memory leak does not occur due to a race between 2588 freeing a block of pages and a speculative page reference. 2589 Loading this module is safe if your kernel has the bug fixed. 2590 If the bug is not fixed, it will leak gigabytes of memory and 2591 probably OOM your system. 2592 2593config TEST_FPU 2594 tristate "Test floating point operations in kernel space" 2595 depends on X86 && !KCOV_INSTRUMENT_ALL 2596 help 2597 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu 2598 which will trigger a sequence of floating point operations. This is used 2599 for self-testing floating point control register setting in 2600 kernel_fpu_begin(). 2601 2602 If unsure, say N. 2603 2604config TEST_CLOCKSOURCE_WATCHDOG 2605 tristate "Test clocksource watchdog in kernel space" 2606 depends on CLOCKSOURCE_WATCHDOG 2607 help 2608 Enable this option to create a kernel module that will trigger 2609 a test of the clocksource watchdog. This module may be loaded 2610 via modprobe or insmod in which case it will run upon being 2611 loaded, or it may be built in, in which case it will run 2612 shortly after boot. 2613 2614 If unsure, say N. 2615 2616endif # RUNTIME_TESTING_MENU 2617 2618config ARCH_USE_MEMTEST 2619 bool 2620 help 2621 An architecture should select this when it uses early_memtest() 2622 during boot process. 2623 2624config MEMTEST 2625 bool "Memtest" 2626 depends on ARCH_USE_MEMTEST 2627 help 2628 This option adds a kernel parameter 'memtest', which allows memtest 2629 to be set and executed. 2630 memtest=0, mean disabled; -- default 2631 memtest=1, mean do 1 test pattern; 2632 ... 2633 memtest=17, mean do 17 test patterns. 2634 If you are unsure how to answer this question, answer N. 2635 2636 2637 2638config HYPERV_TESTING 2639 bool "Microsoft Hyper-V driver testing" 2640 default n 2641 depends on HYPERV && DEBUG_FS 2642 help 2643 Select this option to enable Hyper-V vmbus testing. 2644 2645endmenu # "Kernel Testing and Coverage" 2646 2647source "Documentation/Kconfig" 2648 2649endmenu # Kernel hacking 2650