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 help 103 104 Compiles debug level messages into the kernel, which would not 105 otherwise be available at runtime. These messages can then be 106 enabled/disabled based on various levels of scope - per source file, 107 function, module, format string, and line number. This mechanism 108 implicitly compiles in all pr_debug() and dev_dbg() calls, which 109 enlarges the kernel text size by about 2%. 110 111 If a source file is compiled with DEBUG flag set, any 112 pr_debug() calls in it are enabled by default, but can be 113 disabled at runtime as below. Note that DEBUG flag is 114 turned on by many CONFIG_*DEBUG* options. 115 116 Usage: 117 118 Dynamic debugging is controlled via the 'dynamic_debug/control' file, 119 which is contained in the 'debugfs' filesystem or procfs. 120 Thus, the debugfs or procfs filesystem must first be mounted before 121 making use of this feature. 122 We refer the control file as: <debugfs>/dynamic_debug/control. This 123 file contains a list of the debug statements that can be enabled. The 124 format for each line of the file is: 125 126 filename:lineno [module]function flags format 127 128 filename : source file of the debug statement 129 lineno : line number of the debug statement 130 module : module that contains the debug statement 131 function : function that contains the debug statement 132 flags : '=p' means the line is turned 'on' for printing 133 format : the format used for the debug statement 134 135 From a live system: 136 137 nullarbor:~ # cat <debugfs>/dynamic_debug/control 138 # filename:lineno [module]function flags format 139 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012" 140 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012" 141 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012" 142 143 Example usage: 144 145 // enable the message at line 1603 of file svcsock.c 146 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' > 147 <debugfs>/dynamic_debug/control 148 149 // enable all the messages in file svcsock.c 150 nullarbor:~ # echo -n 'file svcsock.c +p' > 151 <debugfs>/dynamic_debug/control 152 153 // enable all the messages in the NFS server module 154 nullarbor:~ # echo -n 'module nfsd +p' > 155 <debugfs>/dynamic_debug/control 156 157 // enable all 12 messages in the function svc_process() 158 nullarbor:~ # echo -n 'func svc_process +p' > 159 <debugfs>/dynamic_debug/control 160 161 // disable all 12 messages in the function svc_process() 162 nullarbor:~ # echo -n 'func svc_process -p' > 163 <debugfs>/dynamic_debug/control 164 165 See Documentation/admin-guide/dynamic-debug-howto.rst for additional 166 information. 167 168config SYMBOLIC_ERRNAME 169 bool "Support symbolic error names in printf" 170 default y if PRINTK 171 help 172 If you say Y here, the kernel's printf implementation will 173 be able to print symbolic error names such as ENOSPC instead 174 of the number 28. It makes the kernel image slightly larger 175 (about 3KB), but can make the kernel logs easier to read. 176 177config DEBUG_BUGVERBOSE 178 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT 179 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE) 180 default y 181 help 182 Say Y here to make BUG() panics output the file name and line number 183 of the BUG call as well as the EIP and oops trace. This aids 184 debugging but costs about 70-100K of memory. 185 186endmenu # "printk and dmesg options" 187 188menu "Compile-time checks and compiler options" 189 190config DEBUG_INFO 191 bool "Compile the kernel with debug info" 192 depends on DEBUG_KERNEL && !COMPILE_TEST 193 help 194 If you say Y here the resulting kernel image will include 195 debugging info resulting in a larger kernel image. 196 This adds debug symbols to the kernel and modules (gcc -g), and 197 is needed if you intend to use kernel crashdump or binary object 198 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 199 Say Y here only if you plan to debug the kernel. 200 201 If unsure, say N. 202 203config DEBUG_INFO_REDUCED 204 bool "Reduce debugging information" 205 depends on DEBUG_INFO 206 help 207 If you say Y here gcc is instructed to generate less debugging 208 information for structure types. This means that tools that 209 need full debugging information (like kgdb or systemtap) won't 210 be happy. But if you merely need debugging information to 211 resolve line numbers there is no loss. Advantage is that 212 build directory object sizes shrink dramatically over a full 213 DEBUG_INFO build and compile times are reduced too. 214 Only works with newer gcc versions. 215 216config DEBUG_INFO_SPLIT 217 bool "Produce split debuginfo in .dwo files" 218 depends on DEBUG_INFO 219 depends on $(cc-option,-gsplit-dwarf) 220 help 221 Generate debug info into separate .dwo files. This significantly 222 reduces the build directory size for builds with DEBUG_INFO, 223 because it stores the information only once on disk in .dwo 224 files instead of multiple times in object files and executables. 225 In addition the debug information is also compressed. 226 227 Requires recent gcc (4.7+) and recent gdb/binutils. 228 Any tool that packages or reads debug information would need 229 to know about the .dwo files and include them. 230 Incompatible with older versions of ccache. 231 232config DEBUG_INFO_DWARF4 233 bool "Generate dwarf4 debuginfo" 234 depends on DEBUG_INFO 235 depends on $(cc-option,-gdwarf-4) 236 help 237 Generate dwarf4 debug info. This requires recent versions 238 of gcc and gdb. It makes the debug information larger. 239 But it significantly improves the success of resolving 240 variables in gdb on optimized code. 241 242config DEBUG_INFO_BTF 243 bool "Generate BTF typeinfo" 244 depends on DEBUG_INFO 245 help 246 Generate deduplicated BTF type information from DWARF debug info. 247 Turning this on expects presence of pahole tool, which will convert 248 DWARF type info into equivalent deduplicated BTF type info. 249 250config GDB_SCRIPTS 251 bool "Provide GDB scripts for kernel debugging" 252 depends on DEBUG_INFO 253 help 254 This creates the required links to GDB helper scripts in the 255 build directory. If you load vmlinux into gdb, the helper 256 scripts will be automatically imported by gdb as well, and 257 additional functions are available to analyze a Linux kernel 258 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst 259 for further details. 260 261config ENABLE_MUST_CHECK 262 bool "Enable __must_check logic" 263 default y 264 help 265 Enable the __must_check logic in the kernel build. Disable this to 266 suppress the "warning: ignoring return value of 'foo', declared with 267 attribute warn_unused_result" messages. 268 269config FRAME_WARN 270 int "Warn for stack frames larger than (needs gcc 4.4)" 271 range 0 8192 272 default 2048 if GCC_PLUGIN_LATENT_ENTROPY 273 default 1280 if (!64BIT && PARISC) 274 default 1024 if (!64BIT && !PARISC) 275 default 2048 if 64BIT 276 help 277 Tell gcc to warn at build time for stack frames larger than this. 278 Setting this too low will cause a lot of warnings. 279 Setting it to 0 disables the warning. 280 Requires gcc 4.4 281 282config STRIP_ASM_SYMS 283 bool "Strip assembler-generated symbols during link" 284 default n 285 help 286 Strip internal assembler-generated symbols during a link (symbols 287 that look like '.Lxxx') so they don't pollute the output of 288 get_wchan() and suchlike. 289 290config READABLE_ASM 291 bool "Generate readable assembler code" 292 depends on DEBUG_KERNEL 293 help 294 Disable some compiler optimizations that tend to generate human unreadable 295 assembler output. This may make the kernel slightly slower, but it helps 296 to keep kernel developers who have to stare a lot at assembler listings 297 sane. 298 299config HEADERS_INSTALL 300 bool "Install uapi headers to usr/include" 301 depends on !UML 302 help 303 This option will install uapi headers (headers exported to user-space) 304 into the usr/include directory for use during the kernel build. 305 This is unneeded for building the kernel itself, but needed for some 306 user-space program samples. It is also needed by some features such 307 as uapi header sanity checks. 308 309config OPTIMIZE_INLINING 310 def_bool y 311 help 312 This option determines if the kernel forces gcc to inline the functions 313 developers have marked 'inline'. Doing so takes away freedom from gcc to 314 do what it thinks is best, which is desirable for the gcc 3.x series of 315 compilers. The gcc 4.x series have a rewritten inlining algorithm and 316 enabling this option will generate a smaller kernel there. Hopefully 317 this algorithm is so good that allowing gcc 4.x and above to make the 318 decision will become the default in the future. Until then this option 319 is there to test gcc for this. 320 321config DEBUG_SECTION_MISMATCH 322 bool "Enable full Section mismatch analysis" 323 help 324 The section mismatch analysis checks if there are illegal 325 references from one section to another section. 326 During linktime or runtime, some sections are dropped; 327 any use of code/data previously in these sections would 328 most likely result in an oops. 329 In the code, functions and variables are annotated with 330 __init,, etc. (see the full list in include/linux/init.h), 331 which results in the code/data being placed in specific sections. 332 The section mismatch analysis is always performed after a full 333 kernel build, and enabling this option causes the following 334 additional step to occur: 335 - Add the option -fno-inline-functions-called-once to gcc commands. 336 When inlining a function annotated with __init in a non-init 337 function, we would lose the section information and thus 338 the analysis would not catch the illegal reference. 339 This option tells gcc to inline less (but it does result in 340 a larger kernel). 341 342config SECTION_MISMATCH_WARN_ONLY 343 bool "Make section mismatch errors non-fatal" 344 default y 345 help 346 If you say N here, the build process will fail if there are any 347 section mismatch, instead of just throwing warnings. 348 349 If unsure, say Y. 350 351# 352# Select this config option from the architecture Kconfig, if it 353# is preferred to always offer frame pointers as a config 354# option on the architecture (regardless of KERNEL_DEBUG): 355# 356config ARCH_WANT_FRAME_POINTERS 357 bool 358 359config FRAME_POINTER 360 bool "Compile the kernel with frame pointers" 361 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS 362 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 363 help 364 If you say Y here the resulting kernel image will be slightly 365 larger and slower, but it gives very useful debugging information 366 in case of kernel bugs. (precise oopses/stacktraces/warnings) 367 368config STACK_VALIDATION 369 bool "Compile-time stack metadata validation" 370 depends on HAVE_STACK_VALIDATION 371 default n 372 help 373 Add compile-time checks to validate stack metadata, including frame 374 pointers (if CONFIG_FRAME_POINTER is enabled). This helps ensure 375 that runtime stack traces are more reliable. 376 377 This is also a prerequisite for generation of ORC unwind data, which 378 is needed for CONFIG_UNWINDER_ORC. 379 380 For more information, see 381 tools/objtool/Documentation/stack-validation.txt. 382 383config DEBUG_FORCE_WEAK_PER_CPU 384 bool "Force weak per-cpu definitions" 385 depends on DEBUG_KERNEL 386 help 387 s390 and alpha require percpu variables in modules to be 388 defined weak to work around addressing range issue which 389 puts the following two restrictions on percpu variable 390 definitions. 391 392 1. percpu symbols must be unique whether static or not 393 2. percpu variables can't be defined inside a function 394 395 To ensure that generic code follows the above rules, this 396 option forces all percpu variables to be defined as weak. 397 398endmenu # "Compiler options" 399 400menu "Generic Kernel Debugging Instruments" 401 402config MAGIC_SYSRQ 403 bool "Magic SysRq key" 404 depends on !UML 405 help 406 If you say Y here, you will have some control over the system even 407 if the system crashes for example during kernel debugging (e.g., you 408 will be able to flush the buffer cache to disk, reboot the system 409 immediately or dump some status information). This is accomplished 410 by pressing various keys while holding SysRq (Alt+PrintScreen). It 411 also works on a serial console (on PC hardware at least), if you 412 send a BREAK and then within 5 seconds a command keypress. The 413 keys are documented in <file:Documentation/admin-guide/sysrq.rst>. 414 Don't say Y unless you really know what this hack does. 415 416config MAGIC_SYSRQ_DEFAULT_ENABLE 417 hex "Enable magic SysRq key functions by default" 418 depends on MAGIC_SYSRQ 419 default 0x1 420 help 421 Specifies which SysRq key functions are enabled by default. 422 This may be set to 1 or 0 to enable or disable them all, or 423 to a bitmask as described in Documentation/admin-guide/sysrq.rst. 424 425config MAGIC_SYSRQ_SERIAL 426 bool "Enable magic SysRq key over serial" 427 depends on MAGIC_SYSRQ 428 default y 429 help 430 Many embedded boards have a disconnected TTL level serial which can 431 generate some garbage that can lead to spurious false sysrq detects. 432 This option allows you to decide whether you want to enable the 433 magic SysRq key. 434 435config DEBUG_FS 436 bool "Debug Filesystem" 437 help 438 debugfs is a virtual file system that kernel developers use to put 439 debugging files into. Enable this option to be able to read and 440 write to these files. 441 442 For detailed documentation on the debugfs API, see 443 Documentation/filesystems/. 444 445 If unsure, say N. 446 447source "lib/Kconfig.kgdb" 448 449source "lib/Kconfig.ubsan" 450 451endmenu 452 453config DEBUG_KERNEL 454 bool "Kernel debugging" 455 help 456 Say Y here if you are developing drivers or trying to debug and 457 identify kernel problems. 458 459config DEBUG_MISC 460 bool "Miscellaneous debug code" 461 default DEBUG_KERNEL 462 depends on DEBUG_KERNEL 463 help 464 Say Y here if you need to enable miscellaneous debug code that should 465 be under a more specific debug option but isn't. 466 467 468menu "Memory Debugging" 469 470source "mm/Kconfig.debug" 471 472config DEBUG_OBJECTS 473 bool "Debug object operations" 474 depends on DEBUG_KERNEL 475 help 476 If you say Y here, additional code will be inserted into the 477 kernel to track the life time of various objects and validate 478 the operations on those objects. 479 480config DEBUG_OBJECTS_SELFTEST 481 bool "Debug objects selftest" 482 depends on DEBUG_OBJECTS 483 help 484 This enables the selftest of the object debug code. 485 486config DEBUG_OBJECTS_FREE 487 bool "Debug objects in freed memory" 488 depends on DEBUG_OBJECTS 489 help 490 This enables checks whether a k/v free operation frees an area 491 which contains an object which has not been deactivated 492 properly. This can make kmalloc/kfree-intensive workloads 493 much slower. 494 495config DEBUG_OBJECTS_TIMERS 496 bool "Debug timer objects" 497 depends on DEBUG_OBJECTS 498 help 499 If you say Y here, additional code will be inserted into the 500 timer routines to track the life time of timer objects and 501 validate the timer operations. 502 503config DEBUG_OBJECTS_WORK 504 bool "Debug work objects" 505 depends on DEBUG_OBJECTS 506 help 507 If you say Y here, additional code will be inserted into the 508 work queue routines to track the life time of work objects and 509 validate the work operations. 510 511config DEBUG_OBJECTS_RCU_HEAD 512 bool "Debug RCU callbacks objects" 513 depends on DEBUG_OBJECTS 514 help 515 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 516 517config DEBUG_OBJECTS_PERCPU_COUNTER 518 bool "Debug percpu counter objects" 519 depends on DEBUG_OBJECTS 520 help 521 If you say Y here, additional code will be inserted into the 522 percpu counter routines to track the life time of percpu counter 523 objects and validate the percpu counter operations. 524 525config DEBUG_OBJECTS_ENABLE_DEFAULT 526 int "debug_objects bootup default value (0-1)" 527 range 0 1 528 default "1" 529 depends on DEBUG_OBJECTS 530 help 531 Debug objects boot parameter default value 532 533config DEBUG_SLAB 534 bool "Debug slab memory allocations" 535 depends on DEBUG_KERNEL && SLAB 536 help 537 Say Y here to have the kernel do limited verification on memory 538 allocation as well as poisoning memory on free to catch use of freed 539 memory. This can make kmalloc/kfree-intensive workloads much slower. 540 541config SLUB_DEBUG_ON 542 bool "SLUB debugging on by default" 543 depends on SLUB && SLUB_DEBUG 544 default n 545 help 546 Boot with debugging on by default. SLUB boots by default with 547 the runtime debug capabilities switched off. Enabling this is 548 equivalent to specifying the "slub_debug" parameter on boot. 549 There is no support for more fine grained debug control like 550 possible with slub_debug=xxx. SLUB debugging may be switched 551 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying 552 "slub_debug=-". 553 554config SLUB_STATS 555 default n 556 bool "Enable SLUB performance statistics" 557 depends on SLUB && SYSFS 558 help 559 SLUB statistics are useful to debug SLUBs allocation behavior in 560 order find ways to optimize the allocator. This should never be 561 enabled for production use since keeping statistics slows down 562 the allocator by a few percentage points. The slabinfo command 563 supports the determination of the most active slabs to figure 564 out which slabs are relevant to a particular load. 565 Try running: slabinfo -DA 566 567config HAVE_DEBUG_KMEMLEAK 568 bool 569 570config DEBUG_KMEMLEAK 571 bool "Kernel memory leak detector" 572 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK 573 select DEBUG_FS 574 select STACKTRACE if STACKTRACE_SUPPORT 575 select KALLSYMS 576 select CRC32 577 help 578 Say Y here if you want to enable the memory leak 579 detector. The memory allocation/freeing is traced in a way 580 similar to the Boehm's conservative garbage collector, the 581 difference being that the orphan objects are not freed but 582 only shown in /sys/kernel/debug/kmemleak. Enabling this 583 feature will introduce an overhead to memory 584 allocations. See Documentation/dev-tools/kmemleak.rst for more 585 details. 586 587 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances 588 of finding leaks due to the slab objects poisoning. 589 590 In order to access the kmemleak file, debugfs needs to be 591 mounted (usually at /sys/kernel/debug). 592 593config DEBUG_KMEMLEAK_MEM_POOL_SIZE 594 int "Kmemleak memory pool size" 595 depends on DEBUG_KMEMLEAK 596 range 200 1000000 597 default 16000 598 help 599 Kmemleak must track all the memory allocations to avoid 600 reporting false positives. Since memory may be allocated or 601 freed before kmemleak is fully initialised, use a static pool 602 of metadata objects to track such callbacks. After kmemleak is 603 fully initialised, this memory pool acts as an emergency one 604 if slab allocations fail. 605 606config DEBUG_KMEMLEAK_TEST 607 tristate "Simple test for the kernel memory leak detector" 608 depends on DEBUG_KMEMLEAK && m 609 help 610 This option enables a module that explicitly leaks memory. 611 612 If unsure, say N. 613 614config DEBUG_KMEMLEAK_DEFAULT_OFF 615 bool "Default kmemleak to off" 616 depends on DEBUG_KMEMLEAK 617 help 618 Say Y here to disable kmemleak by default. It can then be enabled 619 on the command line via kmemleak=on. 620 621config DEBUG_KMEMLEAK_AUTO_SCAN 622 bool "Enable kmemleak auto scan thread on boot up" 623 default y 624 depends on DEBUG_KMEMLEAK 625 help 626 Depending on the cpu, kmemleak scan may be cpu intensive and can 627 stall user tasks at times. This option enables/disables automatic 628 kmemleak scan at boot up. 629 630 Say N here to disable kmemleak auto scan thread to stop automatic 631 scanning. Disabling this option disables automatic reporting of 632 memory leaks. 633 634 If unsure, say Y. 635 636config DEBUG_STACK_USAGE 637 bool "Stack utilization instrumentation" 638 depends on DEBUG_KERNEL && !IA64 639 help 640 Enables the display of the minimum amount of free stack which each 641 task has ever had available in the sysrq-T and sysrq-P debug output. 642 643 This option will slow down process creation somewhat. 644 645config SCHED_STACK_END_CHECK 646 bool "Detect stack corruption on calls to schedule()" 647 depends on DEBUG_KERNEL 648 default n 649 help 650 This option checks for a stack overrun on calls to schedule(). 651 If the stack end location is found to be over written always panic as 652 the content of the corrupted region can no longer be trusted. 653 This is to ensure no erroneous behaviour occurs which could result in 654 data corruption or a sporadic crash at a later stage once the region 655 is examined. The runtime overhead introduced is minimal. 656 657config DEBUG_VM 658 bool "Debug VM" 659 depends on DEBUG_KERNEL 660 help 661 Enable this to turn on extended checks in the virtual-memory system 662 that may impact performance. 663 664 If unsure, say N. 665 666config DEBUG_VM_VMACACHE 667 bool "Debug VMA caching" 668 depends on DEBUG_VM 669 help 670 Enable this to turn on VMA caching debug information. Doing so 671 can cause significant overhead, so only enable it in non-production 672 environments. 673 674 If unsure, say N. 675 676config DEBUG_VM_RB 677 bool "Debug VM red-black trees" 678 depends on DEBUG_VM 679 help 680 Enable VM red-black tree debugging information and extra validations. 681 682 If unsure, say N. 683 684config DEBUG_VM_PGFLAGS 685 bool "Debug page-flags operations" 686 depends on DEBUG_VM 687 help 688 Enables extra validation on page flags operations. 689 690 If unsure, say N. 691 692config ARCH_HAS_DEBUG_VIRTUAL 693 bool 694 695config DEBUG_VIRTUAL 696 bool "Debug VM translations" 697 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL 698 help 699 Enable some costly sanity checks in virtual to page code. This can 700 catch mistakes with virt_to_page() and friends. 701 702 If unsure, say N. 703 704config DEBUG_NOMMU_REGIONS 705 bool "Debug the global anon/private NOMMU mapping region tree" 706 depends on DEBUG_KERNEL && !MMU 707 help 708 This option causes the global tree of anonymous and private mapping 709 regions to be regularly checked for invalid topology. 710 711config DEBUG_MEMORY_INIT 712 bool "Debug memory initialisation" if EXPERT 713 default !EXPERT 714 help 715 Enable this for additional checks during memory initialisation. 716 The sanity checks verify aspects of the VM such as the memory model 717 and other information provided by the architecture. Verbose 718 information will be printed at KERN_DEBUG loglevel depending 719 on the mminit_loglevel= command-line option. 720 721 If unsure, say Y 722 723config MEMORY_NOTIFIER_ERROR_INJECT 724 tristate "Memory hotplug notifier error injection module" 725 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION 726 help 727 This option provides the ability to inject artificial errors to 728 memory hotplug notifier chain callbacks. It is controlled through 729 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 730 731 If the notifier call chain should be failed with some events 732 notified, write the error code to "actions/<notifier event>/error". 733 734 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 735 736 # cd /sys/kernel/debug/notifier-error-inject/memory 737 # echo -12 > actions/MEM_GOING_OFFLINE/error 738 # echo offline > /sys/devices/system/memory/memoryXXX/state 739 bash: echo: write error: Cannot allocate memory 740 741 To compile this code as a module, choose M here: the module will 742 be called memory-notifier-error-inject. 743 744 If unsure, say N. 745 746config DEBUG_PER_CPU_MAPS 747 bool "Debug access to per_cpu maps" 748 depends on DEBUG_KERNEL 749 depends on SMP 750 help 751 Say Y to verify that the per_cpu map being accessed has 752 been set up. This adds a fair amount of code to kernel memory 753 and decreases performance. 754 755 Say N if unsure. 756 757config DEBUG_HIGHMEM 758 bool "Highmem debugging" 759 depends on DEBUG_KERNEL && HIGHMEM 760 help 761 This option enables additional error checking for high memory 762 systems. Disable for production systems. 763 764config HAVE_DEBUG_STACKOVERFLOW 765 bool 766 767config DEBUG_STACKOVERFLOW 768 bool "Check for stack overflows" 769 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 770 ---help--- 771 Say Y here if you want to check for overflows of kernel, IRQ 772 and exception stacks (if your architecture uses them). This 773 option will show detailed messages if free stack space drops 774 below a certain limit. 775 776 These kinds of bugs usually occur when call-chains in the 777 kernel get too deep, especially when interrupts are 778 involved. 779 780 Use this in cases where you see apparently random memory 781 corruption, especially if it appears in 'struct thread_info' 782 783 If in doubt, say "N". 784 785source "lib/Kconfig.kasan" 786 787endmenu # "Memory Debugging" 788 789config DEBUG_SHIRQ 790 bool "Debug shared IRQ handlers" 791 depends on DEBUG_KERNEL 792 help 793 Enable this to generate a spurious interrupt as soon as a shared 794 interrupt handler is registered, and just before one is deregistered. 795 Drivers ought to be able to handle interrupts coming in at those 796 points; some don't and need to be caught. 797 798menu "Debug Oops, Lockups and Hangs" 799 800config PANIC_ON_OOPS 801 bool "Panic on Oops" 802 help 803 Say Y here to enable the kernel to panic when it oopses. This 804 has the same effect as setting oops=panic on the kernel command 805 line. 806 807 This feature is useful to ensure that the kernel does not do 808 anything erroneous after an oops which could result in data 809 corruption or other issues. 810 811 Say N if unsure. 812 813config PANIC_ON_OOPS_VALUE 814 int 815 range 0 1 816 default 0 if !PANIC_ON_OOPS 817 default 1 if PANIC_ON_OOPS 818 819config PANIC_TIMEOUT 820 int "panic timeout" 821 default 0 822 help 823 Set the timeout value (in seconds) until a reboot occurs when the 824 the kernel panics. If n = 0, then we wait forever. A timeout 825 value n > 0 will wait n seconds before rebooting, while a timeout 826 value n < 0 will reboot immediately. 827 828config LOCKUP_DETECTOR 829 bool 830 831config SOFTLOCKUP_DETECTOR 832 bool "Detect Soft Lockups" 833 depends on DEBUG_KERNEL && !S390 834 select LOCKUP_DETECTOR 835 help 836 Say Y here to enable the kernel to act as a watchdog to detect 837 soft lockups. 838 839 Softlockups are bugs that cause the kernel to loop in kernel 840 mode for more than 20 seconds, without giving other tasks a 841 chance to run. The current stack trace is displayed upon 842 detection and the system will stay locked up. 843 844config BOOTPARAM_SOFTLOCKUP_PANIC 845 bool "Panic (Reboot) On Soft Lockups" 846 depends on SOFTLOCKUP_DETECTOR 847 help 848 Say Y here to enable the kernel to panic on "soft lockups", 849 which are bugs that cause the kernel to loop in kernel 850 mode for more than 20 seconds (configurable using the watchdog_thresh 851 sysctl), without giving other tasks a chance to run. 852 853 The panic can be used in combination with panic_timeout, 854 to cause the system to reboot automatically after a 855 lockup has been detected. This feature is useful for 856 high-availability systems that have uptime guarantees and 857 where a lockup must be resolved ASAP. 858 859 Say N if unsure. 860 861config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE 862 int 863 depends on SOFTLOCKUP_DETECTOR 864 range 0 1 865 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC 866 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC 867 868config HARDLOCKUP_DETECTOR_PERF 869 bool 870 select SOFTLOCKUP_DETECTOR 871 872# 873# Enables a timestamp based low pass filter to compensate for perf based 874# hard lockup detection which runs too fast due to turbo modes. 875# 876config HARDLOCKUP_CHECK_TIMESTAMP 877 bool 878 879# 880# arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard 881# lockup detector rather than the perf based detector. 882# 883config HARDLOCKUP_DETECTOR 884 bool "Detect Hard Lockups" 885 depends on DEBUG_KERNEL && !S390 886 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH 887 select LOCKUP_DETECTOR 888 select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF 889 select HARDLOCKUP_DETECTOR_ARCH if HAVE_HARDLOCKUP_DETECTOR_ARCH 890 help 891 Say Y here to enable the kernel to act as a watchdog to detect 892 hard lockups. 893 894 Hardlockups are bugs that cause the CPU to loop in kernel mode 895 for more than 10 seconds, without letting other interrupts have a 896 chance to run. The current stack trace is displayed upon detection 897 and the system will stay locked up. 898 899config BOOTPARAM_HARDLOCKUP_PANIC 900 bool "Panic (Reboot) On Hard Lockups" 901 depends on HARDLOCKUP_DETECTOR 902 help 903 Say Y here to enable the kernel to panic on "hard lockups", 904 which are bugs that cause the kernel to loop in kernel 905 mode with interrupts disabled for more than 10 seconds (configurable 906 using the watchdog_thresh sysctl). 907 908 Say N if unsure. 909 910config BOOTPARAM_HARDLOCKUP_PANIC_VALUE 911 int 912 depends on HARDLOCKUP_DETECTOR 913 range 0 1 914 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC 915 default 1 if BOOTPARAM_HARDLOCKUP_PANIC 916 917config DETECT_HUNG_TASK 918 bool "Detect Hung Tasks" 919 depends on DEBUG_KERNEL 920 default SOFTLOCKUP_DETECTOR 921 help 922 Say Y here to enable the kernel to detect "hung tasks", 923 which are bugs that cause the task to be stuck in 924 uninterruptible "D" state indefinitely. 925 926 When a hung task is detected, the kernel will print the 927 current stack trace (which you should report), but the 928 task will stay in uninterruptible state. If lockdep is 929 enabled then all held locks will also be reported. This 930 feature has negligible overhead. 931 932config DEFAULT_HUNG_TASK_TIMEOUT 933 int "Default timeout for hung task detection (in seconds)" 934 depends on DETECT_HUNG_TASK 935 default 120 936 help 937 This option controls the default timeout (in seconds) used 938 to determine when a task has become non-responsive and should 939 be considered hung. 940 941 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 942 sysctl or by writing a value to 943 /proc/sys/kernel/hung_task_timeout_secs. 944 945 A timeout of 0 disables the check. The default is two minutes. 946 Keeping the default should be fine in most cases. 947 948config BOOTPARAM_HUNG_TASK_PANIC 949 bool "Panic (Reboot) On Hung Tasks" 950 depends on DETECT_HUNG_TASK 951 help 952 Say Y here to enable the kernel to panic on "hung tasks", 953 which are bugs that cause the kernel to leave a task stuck 954 in uninterruptible "D" state. 955 956 The panic can be used in combination with panic_timeout, 957 to cause the system to reboot automatically after a 958 hung task has been detected. This feature is useful for 959 high-availability systems that have uptime guarantees and 960 where a hung tasks must be resolved ASAP. 961 962 Say N if unsure. 963 964config BOOTPARAM_HUNG_TASK_PANIC_VALUE 965 int 966 depends on DETECT_HUNG_TASK 967 range 0 1 968 default 0 if !BOOTPARAM_HUNG_TASK_PANIC 969 default 1 if BOOTPARAM_HUNG_TASK_PANIC 970 971config WQ_WATCHDOG 972 bool "Detect Workqueue Stalls" 973 depends on DEBUG_KERNEL 974 help 975 Say Y here to enable stall detection on workqueues. If a 976 worker pool doesn't make forward progress on a pending work 977 item for over a given amount of time, 30s by default, a 978 warning message is printed along with dump of workqueue 979 state. This can be configured through kernel parameter 980 "workqueue.watchdog_thresh" and its sysfs counterpart. 981 982endmenu # "Debug lockups and hangs" 983 984menu "Scheduler Debugging" 985 986config SCHED_DEBUG 987 bool "Collect scheduler debugging info" 988 depends on DEBUG_KERNEL && PROC_FS 989 default y 990 help 991 If you say Y here, the /proc/sched_debug file will be provided 992 that can help debug the scheduler. The runtime overhead of this 993 option is minimal. 994 995config SCHED_INFO 996 bool 997 default n 998 999config SCHEDSTATS 1000 bool "Collect scheduler statistics" 1001 depends on DEBUG_KERNEL && PROC_FS 1002 select SCHED_INFO 1003 help 1004 If you say Y here, additional code will be inserted into the 1005 scheduler and related routines to collect statistics about 1006 scheduler behavior and provide them in /proc/schedstat. These 1007 stats may be useful for both tuning and debugging the scheduler 1008 If you aren't debugging the scheduler or trying to tune a specific 1009 application, you can say N to avoid the very slight overhead 1010 this adds. 1011 1012endmenu 1013 1014config DEBUG_TIMEKEEPING 1015 bool "Enable extra timekeeping sanity checking" 1016 help 1017 This option will enable additional timekeeping sanity checks 1018 which may be helpful when diagnosing issues where timekeeping 1019 problems are suspected. 1020 1021 This may include checks in the timekeeping hotpaths, so this 1022 option may have a (very small) performance impact to some 1023 workloads. 1024 1025 If unsure, say N. 1026 1027config DEBUG_PREEMPT 1028 bool "Debug preemptible kernel" 1029 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1030 default y 1031 help 1032 If you say Y here then the kernel will use a debug variant of the 1033 commonly used smp_processor_id() function and will print warnings 1034 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1035 will detect preemption count underflows. 1036 1037menu "Lock Debugging (spinlocks, mutexes, etc...)" 1038 1039config LOCK_DEBUGGING_SUPPORT 1040 bool 1041 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1042 default y 1043 1044config PROVE_LOCKING 1045 bool "Lock debugging: prove locking correctness" 1046 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1047 select LOCKDEP 1048 select DEBUG_SPINLOCK 1049 select DEBUG_MUTEXES 1050 select DEBUG_RT_MUTEXES if RT_MUTEXES 1051 select DEBUG_RWSEMS 1052 select DEBUG_WW_MUTEX_SLOWPATH 1053 select DEBUG_LOCK_ALLOC 1054 select TRACE_IRQFLAGS 1055 default n 1056 help 1057 This feature enables the kernel to prove that all locking 1058 that occurs in the kernel runtime is mathematically 1059 correct: that under no circumstance could an arbitrary (and 1060 not yet triggered) combination of observed locking 1061 sequences (on an arbitrary number of CPUs, running an 1062 arbitrary number of tasks and interrupt contexts) cause a 1063 deadlock. 1064 1065 In short, this feature enables the kernel to report locking 1066 related deadlocks before they actually occur. 1067 1068 The proof does not depend on how hard and complex a 1069 deadlock scenario would be to trigger: how many 1070 participant CPUs, tasks and irq-contexts would be needed 1071 for it to trigger. The proof also does not depend on 1072 timing: if a race and a resulting deadlock is possible 1073 theoretically (no matter how unlikely the race scenario 1074 is), it will be proven so and will immediately be 1075 reported by the kernel (once the event is observed that 1076 makes the deadlock theoretically possible). 1077 1078 If a deadlock is impossible (i.e. the locking rules, as 1079 observed by the kernel, are mathematically correct), the 1080 kernel reports nothing. 1081 1082 NOTE: this feature can also be enabled for rwlocks, mutexes 1083 and rwsems - in which case all dependencies between these 1084 different locking variants are observed and mapped too, and 1085 the proof of observed correctness is also maintained for an 1086 arbitrary combination of these separate locking variants. 1087 1088 For more details, see Documentation/locking/lockdep-design.rst. 1089 1090config LOCK_STAT 1091 bool "Lock usage statistics" 1092 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1093 select LOCKDEP 1094 select DEBUG_SPINLOCK 1095 select DEBUG_MUTEXES 1096 select DEBUG_RT_MUTEXES if RT_MUTEXES 1097 select DEBUG_LOCK_ALLOC 1098 default n 1099 help 1100 This feature enables tracking lock contention points 1101 1102 For more details, see Documentation/locking/lockstat.rst 1103 1104 This also enables lock events required by "perf lock", 1105 subcommand of perf. 1106 If you want to use "perf lock", you also need to turn on 1107 CONFIG_EVENT_TRACING. 1108 1109 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1110 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1111 1112config DEBUG_RT_MUTEXES 1113 bool "RT Mutex debugging, deadlock detection" 1114 depends on DEBUG_KERNEL && RT_MUTEXES 1115 help 1116 This allows rt mutex semantics violations and rt mutex related 1117 deadlocks (lockups) to be detected and reported automatically. 1118 1119config DEBUG_SPINLOCK 1120 bool "Spinlock and rw-lock debugging: basic checks" 1121 depends on DEBUG_KERNEL 1122 select UNINLINE_SPIN_UNLOCK 1123 help 1124 Say Y here and build SMP to catch missing spinlock initialization 1125 and certain other kinds of spinlock errors commonly made. This is 1126 best used in conjunction with the NMI watchdog so that spinlock 1127 deadlocks are also debuggable. 1128 1129config DEBUG_MUTEXES 1130 bool "Mutex debugging: basic checks" 1131 depends on DEBUG_KERNEL 1132 help 1133 This feature allows mutex semantics violations to be detected and 1134 reported. 1135 1136config DEBUG_WW_MUTEX_SLOWPATH 1137 bool "Wait/wound mutex debugging: Slowpath testing" 1138 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1139 select DEBUG_LOCK_ALLOC 1140 select DEBUG_SPINLOCK 1141 select DEBUG_MUTEXES 1142 help 1143 This feature enables slowpath testing for w/w mutex users by 1144 injecting additional -EDEADLK wound/backoff cases. Together with 1145 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1146 will test all possible w/w mutex interface abuse with the 1147 exception of simply not acquiring all the required locks. 1148 Note that this feature can introduce significant overhead, so 1149 it really should not be enabled in a production or distro kernel, 1150 even a debug kernel. If you are a driver writer, enable it. If 1151 you are a distro, do not. 1152 1153config DEBUG_RWSEMS 1154 bool "RW Semaphore debugging: basic checks" 1155 depends on DEBUG_KERNEL 1156 help 1157 This debugging feature allows mismatched rw semaphore locks 1158 and unlocks to be detected and reported. 1159 1160config DEBUG_LOCK_ALLOC 1161 bool "Lock debugging: detect incorrect freeing of live locks" 1162 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1163 select DEBUG_SPINLOCK 1164 select DEBUG_MUTEXES 1165 select DEBUG_RT_MUTEXES if RT_MUTEXES 1166 select LOCKDEP 1167 help 1168 This feature will check whether any held lock (spinlock, rwlock, 1169 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1170 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1171 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1172 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1173 held during task exit. 1174 1175config LOCKDEP 1176 bool 1177 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1178 select STACKTRACE 1179 select FRAME_POINTER if !MIPS && !PPC && !ARM && !S390 && !MICROBLAZE && !ARC && !X86 1180 select KALLSYMS 1181 select KALLSYMS_ALL 1182 1183config LOCKDEP_SMALL 1184 bool 1185 1186config DEBUG_LOCKDEP 1187 bool "Lock dependency engine debugging" 1188 depends on DEBUG_KERNEL && LOCKDEP 1189 help 1190 If you say Y here, the lock dependency engine will do 1191 additional runtime checks to debug itself, at the price 1192 of more runtime overhead. 1193 1194config DEBUG_ATOMIC_SLEEP 1195 bool "Sleep inside atomic section checking" 1196 select PREEMPT_COUNT 1197 depends on DEBUG_KERNEL 1198 depends on !ARCH_NO_PREEMPT 1199 help 1200 If you say Y here, various routines which may sleep will become very 1201 noisy if they are called inside atomic sections: when a spinlock is 1202 held, inside an rcu read side critical section, inside preempt disabled 1203 sections, inside an interrupt, etc... 1204 1205config DEBUG_LOCKING_API_SELFTESTS 1206 bool "Locking API boot-time self-tests" 1207 depends on DEBUG_KERNEL 1208 help 1209 Say Y here if you want the kernel to run a short self-test during 1210 bootup. The self-test checks whether common types of locking bugs 1211 are detected by debugging mechanisms or not. (if you disable 1212 lock debugging then those bugs wont be detected of course.) 1213 The following locking APIs are covered: spinlocks, rwlocks, 1214 mutexes and rwsems. 1215 1216config LOCK_TORTURE_TEST 1217 tristate "torture tests for locking" 1218 depends on DEBUG_KERNEL 1219 select TORTURE_TEST 1220 help 1221 This option provides a kernel module that runs torture tests 1222 on kernel locking primitives. The kernel module may be built 1223 after the fact on the running kernel to be tested, if desired. 1224 1225 Say Y here if you want kernel locking-primitive torture tests 1226 to be built into the kernel. 1227 Say M if you want these torture tests to build as a module. 1228 Say N if you are unsure. 1229 1230config WW_MUTEX_SELFTEST 1231 tristate "Wait/wound mutex selftests" 1232 help 1233 This option provides a kernel module that runs tests on the 1234 on the struct ww_mutex locking API. 1235 1236 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1237 with this test harness. 1238 1239 Say M if you want these self tests to build as a module. 1240 Say N if you are unsure. 1241 1242endmenu # lock debugging 1243 1244config TRACE_IRQFLAGS 1245 bool 1246 help 1247 Enables hooks to interrupt enabling and disabling for 1248 either tracing or lock debugging. 1249 1250config STACKTRACE 1251 bool "Stack backtrace support" 1252 depends on STACKTRACE_SUPPORT 1253 help 1254 This option causes the kernel to create a /proc/pid/stack for 1255 every process, showing its current stack trace. 1256 It is also used by various kernel debugging features that require 1257 stack trace generation. 1258 1259config WARN_ALL_UNSEEDED_RANDOM 1260 bool "Warn for all uses of unseeded randomness" 1261 default n 1262 help 1263 Some parts of the kernel contain bugs relating to their use of 1264 cryptographically secure random numbers before it's actually possible 1265 to generate those numbers securely. This setting ensures that these 1266 flaws don't go unnoticed, by enabling a message, should this ever 1267 occur. This will allow people with obscure setups to know when things 1268 are going wrong, so that they might contact developers about fixing 1269 it. 1270 1271 Unfortunately, on some models of some architectures getting 1272 a fully seeded CRNG is extremely difficult, and so this can 1273 result in dmesg getting spammed for a surprisingly long 1274 time. This is really bad from a security perspective, and 1275 so architecture maintainers really need to do what they can 1276 to get the CRNG seeded sooner after the system is booted. 1277 However, since users cannot do anything actionable to 1278 address this, by default the kernel will issue only a single 1279 warning for the first use of unseeded randomness. 1280 1281 Say Y here if you want to receive warnings for all uses of 1282 unseeded randomness. This will be of use primarily for 1283 those developers interested in improving the security of 1284 Linux kernels running on their architecture (or 1285 subarchitecture). 1286 1287config DEBUG_KOBJECT 1288 bool "kobject debugging" 1289 depends on DEBUG_KERNEL 1290 help 1291 If you say Y here, some extra kobject debugging messages will be sent 1292 to the syslog. 1293 1294config DEBUG_KOBJECT_RELEASE 1295 bool "kobject release debugging" 1296 depends on DEBUG_OBJECTS_TIMERS 1297 help 1298 kobjects are reference counted objects. This means that their 1299 last reference count put is not predictable, and the kobject can 1300 live on past the point at which a driver decides to drop it's 1301 initial reference to the kobject gained on allocation. An 1302 example of this would be a struct device which has just been 1303 unregistered. 1304 1305 However, some buggy drivers assume that after such an operation, 1306 the memory backing the kobject can be immediately freed. This 1307 goes completely against the principles of a refcounted object. 1308 1309 If you say Y here, the kernel will delay the release of kobjects 1310 on the last reference count to improve the visibility of this 1311 kind of kobject release bug. 1312 1313config HAVE_DEBUG_BUGVERBOSE 1314 bool 1315 1316menu "Debug kernel data structures" 1317 1318config DEBUG_LIST 1319 bool "Debug linked list manipulation" 1320 depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION 1321 help 1322 Enable this to turn on extended checks in the linked-list 1323 walking routines. 1324 1325 If unsure, say N. 1326 1327config DEBUG_PLIST 1328 bool "Debug priority linked list manipulation" 1329 depends on DEBUG_KERNEL 1330 help 1331 Enable this to turn on extended checks in the priority-ordered 1332 linked-list (plist) walking routines. This checks the entire 1333 list multiple times during each manipulation. 1334 1335 If unsure, say N. 1336 1337config DEBUG_SG 1338 bool "Debug SG table operations" 1339 depends on DEBUG_KERNEL 1340 help 1341 Enable this to turn on checks on scatter-gather tables. This can 1342 help find problems with drivers that do not properly initialize 1343 their sg tables. 1344 1345 If unsure, say N. 1346 1347config DEBUG_NOTIFIERS 1348 bool "Debug notifier call chains" 1349 depends on DEBUG_KERNEL 1350 help 1351 Enable this to turn on sanity checking for notifier call chains. 1352 This is most useful for kernel developers to make sure that 1353 modules properly unregister themselves from notifier chains. 1354 This is a relatively cheap check but if you care about maximum 1355 performance, say N. 1356 1357config BUG_ON_DATA_CORRUPTION 1358 bool "Trigger a BUG when data corruption is detected" 1359 select DEBUG_LIST 1360 help 1361 Select this option if the kernel should BUG when it encounters 1362 data corruption in kernel memory structures when they get checked 1363 for validity. 1364 1365 If unsure, say N. 1366 1367endmenu 1368 1369config DEBUG_CREDENTIALS 1370 bool "Debug credential management" 1371 depends on DEBUG_KERNEL 1372 help 1373 Enable this to turn on some debug checking for credential 1374 management. The additional code keeps track of the number of 1375 pointers from task_structs to any given cred struct, and checks to 1376 see that this number never exceeds the usage count of the cred 1377 struct. 1378 1379 Furthermore, if SELinux is enabled, this also checks that the 1380 security pointer in the cred struct is never seen to be invalid. 1381 1382 If unsure, say N. 1383 1384source "kernel/rcu/Kconfig.debug" 1385 1386config DEBUG_WQ_FORCE_RR_CPU 1387 bool "Force round-robin CPU selection for unbound work items" 1388 depends on DEBUG_KERNEL 1389 default n 1390 help 1391 Workqueue used to implicitly guarantee that work items queued 1392 without explicit CPU specified are put on the local CPU. This 1393 guarantee is no longer true and while local CPU is still 1394 preferred work items may be put on foreign CPUs. Kernel 1395 parameter "workqueue.debug_force_rr_cpu" is added to force 1396 round-robin CPU selection to flush out usages which depend on the 1397 now broken guarantee. This config option enables the debug 1398 feature by default. When enabled, memory and cache locality will 1399 be impacted. 1400 1401config DEBUG_BLOCK_EXT_DEVT 1402 bool "Force extended block device numbers and spread them" 1403 depends on DEBUG_KERNEL 1404 depends on BLOCK 1405 default n 1406 help 1407 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON 1408 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT 1409 YOU ARE DOING. Distros, please enable this and fix whatever 1410 is broken. 1411 1412 Conventionally, block device numbers are allocated from 1413 predetermined contiguous area. However, extended block area 1414 may introduce non-contiguous block device numbers. This 1415 option forces most block device numbers to be allocated from 1416 the extended space and spreads them to discover kernel or 1417 userland code paths which assume predetermined contiguous 1418 device number allocation. 1419 1420 Note that turning on this debug option shuffles all the 1421 device numbers for all IDE and SCSI devices including libata 1422 ones, so root partition specified using device number 1423 directly (via rdev or root=MAJ:MIN) won't work anymore. 1424 Textual device names (root=/dev/sdXn) will continue to work. 1425 1426 Say N if you are unsure. 1427 1428config CPU_HOTPLUG_STATE_CONTROL 1429 bool "Enable CPU hotplug state control" 1430 depends on DEBUG_KERNEL 1431 depends on HOTPLUG_CPU 1432 default n 1433 help 1434 Allows to write steps between "offline" and "online" to the CPUs 1435 sysfs target file so states can be stepped granular. This is a debug 1436 option for now as the hotplug machinery cannot be stopped and 1437 restarted at arbitrary points yet. 1438 1439 Say N if your are unsure. 1440 1441config LATENCYTOP 1442 bool "Latency measuring infrastructure" 1443 depends on DEBUG_KERNEL 1444 depends on STACKTRACE_SUPPORT 1445 depends on PROC_FS 1446 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86 1447 select KALLSYMS 1448 select KALLSYMS_ALL 1449 select STACKTRACE 1450 select SCHEDSTATS 1451 select SCHED_DEBUG 1452 help 1453 Enable this option if you want to use the LatencyTOP tool 1454 to find out which userspace is blocking on what kernel operations. 1455 1456source "kernel/trace/Kconfig" 1457 1458config PROVIDE_OHCI1394_DMA_INIT 1459 bool "Remote debugging over FireWire early on boot" 1460 depends on PCI && X86 1461 help 1462 If you want to debug problems which hang or crash the kernel early 1463 on boot and the crashing machine has a FireWire port, you can use 1464 this feature to remotely access the memory of the crashed machine 1465 over FireWire. This employs remote DMA as part of the OHCI1394 1466 specification which is now the standard for FireWire controllers. 1467 1468 With remote DMA, you can monitor the printk buffer remotely using 1469 firescope and access all memory below 4GB using fireproxy from gdb. 1470 Even controlling a kernel debugger is possible using remote DMA. 1471 1472 Usage: 1473 1474 If ohci1394_dma=early is used as boot parameter, it will initialize 1475 all OHCI1394 controllers which are found in the PCI config space. 1476 1477 As all changes to the FireWire bus such as enabling and disabling 1478 devices cause a bus reset and thereby disable remote DMA for all 1479 devices, be sure to have the cable plugged and FireWire enabled on 1480 the debugging host before booting the debug target for debugging. 1481 1482 This code (~1k) is freed after boot. By then, the firewire stack 1483 in charge of the OHCI-1394 controllers should be used instead. 1484 1485 See Documentation/debugging-via-ohci1394.txt for more information. 1486 1487source "samples/Kconfig" 1488 1489config ARCH_HAS_DEVMEM_IS_ALLOWED 1490 bool 1491 1492config STRICT_DEVMEM 1493 bool "Filter access to /dev/mem" 1494 depends on MMU && DEVMEM 1495 depends on ARCH_HAS_DEVMEM_IS_ALLOWED 1496 default y if PPC || X86 || ARM64 1497 help 1498 If this option is disabled, you allow userspace (root) access to all 1499 of memory, including kernel and userspace memory. Accidental 1500 access to this is obviously disastrous, but specific access can 1501 be used by people debugging the kernel. Note that with PAT support 1502 enabled, even in this case there are restrictions on /dev/mem 1503 use due to the cache aliasing requirements. 1504 1505 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 1506 file only allows userspace access to PCI space and the BIOS code and 1507 data regions. This is sufficient for dosemu and X and all common 1508 users of /dev/mem. 1509 1510 If in doubt, say Y. 1511 1512config IO_STRICT_DEVMEM 1513 bool "Filter I/O access to /dev/mem" 1514 depends on STRICT_DEVMEM 1515 help 1516 If this option is disabled, you allow userspace (root) access to all 1517 io-memory regardless of whether a driver is actively using that 1518 range. Accidental access to this is obviously disastrous, but 1519 specific access can be used by people debugging kernel drivers. 1520 1521 If this option is switched on, the /dev/mem file only allows 1522 userspace access to *idle* io-memory ranges (see /proc/iomem) This 1523 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 1524 if the driver using a given range cannot be disabled. 1525 1526 If in doubt, say Y. 1527 1528menu "$(SRCARCH) Debugging" 1529 1530source "arch/$(SRCARCH)/Kconfig.debug" 1531 1532endmenu 1533 1534menu "Kernel Testing and Coverage" 1535 1536source "lib/kunit/Kconfig" 1537 1538config NOTIFIER_ERROR_INJECTION 1539 tristate "Notifier error injection" 1540 depends on DEBUG_KERNEL 1541 select DEBUG_FS 1542 help 1543 This option provides the ability to inject artificial errors to 1544 specified notifier chain callbacks. It is useful to test the error 1545 handling of notifier call chain failures. 1546 1547 Say N if unsure. 1548 1549config PM_NOTIFIER_ERROR_INJECT 1550 tristate "PM notifier error injection module" 1551 depends on PM && NOTIFIER_ERROR_INJECTION 1552 default m if PM_DEBUG 1553 help 1554 This option provides the ability to inject artificial errors to 1555 PM notifier chain callbacks. It is controlled through debugfs 1556 interface /sys/kernel/debug/notifier-error-inject/pm 1557 1558 If the notifier call chain should be failed with some events 1559 notified, write the error code to "actions/<notifier event>/error". 1560 1561 Example: Inject PM suspend error (-12 = -ENOMEM) 1562 1563 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1564 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1565 # echo mem > /sys/power/state 1566 bash: echo: write error: Cannot allocate memory 1567 1568 To compile this code as a module, choose M here: the module will 1569 be called pm-notifier-error-inject. 1570 1571 If unsure, say N. 1572 1573config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1574 tristate "OF reconfig notifier error injection module" 1575 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1576 help 1577 This option provides the ability to inject artificial errors to 1578 OF reconfig notifier chain callbacks. It is controlled 1579 through debugfs interface under 1580 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1581 1582 If the notifier call chain should be failed with some events 1583 notified, write the error code to "actions/<notifier event>/error". 1584 1585 To compile this code as a module, choose M here: the module will 1586 be called of-reconfig-notifier-error-inject. 1587 1588 If unsure, say N. 1589 1590config NETDEV_NOTIFIER_ERROR_INJECT 1591 tristate "Netdev notifier error injection module" 1592 depends on NET && NOTIFIER_ERROR_INJECTION 1593 help 1594 This option provides the ability to inject artificial errors to 1595 netdevice notifier chain callbacks. It is controlled through debugfs 1596 interface /sys/kernel/debug/notifier-error-inject/netdev 1597 1598 If the notifier call chain should be failed with some events 1599 notified, write the error code to "actions/<notifier event>/error". 1600 1601 Example: Inject netdevice mtu change error (-22 = -EINVAL) 1602 1603 # cd /sys/kernel/debug/notifier-error-inject/netdev 1604 # echo -22 > actions/NETDEV_CHANGEMTU/error 1605 # ip link set eth0 mtu 1024 1606 RTNETLINK answers: Invalid argument 1607 1608 To compile this code as a module, choose M here: the module will 1609 be called netdev-notifier-error-inject. 1610 1611 If unsure, say N. 1612 1613config FUNCTION_ERROR_INJECTION 1614 def_bool y 1615 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 1616 1617config FAULT_INJECTION 1618 bool "Fault-injection framework" 1619 depends on DEBUG_KERNEL 1620 help 1621 Provide fault-injection framework. 1622 For more details, see Documentation/fault-injection/. 1623 1624config FAILSLAB 1625 bool "Fault-injection capability for kmalloc" 1626 depends on FAULT_INJECTION 1627 depends on SLAB || SLUB 1628 help 1629 Provide fault-injection capability for kmalloc. 1630 1631config FAIL_PAGE_ALLOC 1632 bool "Fault-injection capabilitiy for alloc_pages()" 1633 depends on FAULT_INJECTION 1634 help 1635 Provide fault-injection capability for alloc_pages(). 1636 1637config FAIL_MAKE_REQUEST 1638 bool "Fault-injection capability for disk IO" 1639 depends on FAULT_INJECTION && BLOCK 1640 help 1641 Provide fault-injection capability for disk IO. 1642 1643config FAIL_IO_TIMEOUT 1644 bool "Fault-injection capability for faking disk interrupts" 1645 depends on FAULT_INJECTION && BLOCK 1646 help 1647 Provide fault-injection capability on end IO handling. This 1648 will make the block layer "forget" an interrupt as configured, 1649 thus exercising the error handling. 1650 1651 Only works with drivers that use the generic timeout handling, 1652 for others it wont do anything. 1653 1654config FAIL_FUTEX 1655 bool "Fault-injection capability for futexes" 1656 select DEBUG_FS 1657 depends on FAULT_INJECTION && FUTEX 1658 help 1659 Provide fault-injection capability for futexes. 1660 1661config FAULT_INJECTION_DEBUG_FS 1662 bool "Debugfs entries for fault-injection capabilities" 1663 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 1664 help 1665 Enable configuration of fault-injection capabilities via debugfs. 1666 1667config FAIL_FUNCTION 1668 bool "Fault-injection capability for functions" 1669 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 1670 help 1671 Provide function-based fault-injection capability. 1672 This will allow you to override a specific function with a return 1673 with given return value. As a result, function caller will see 1674 an error value and have to handle it. This is useful to test the 1675 error handling in various subsystems. 1676 1677config FAIL_MMC_REQUEST 1678 bool "Fault-injection capability for MMC IO" 1679 depends on FAULT_INJECTION_DEBUG_FS && MMC 1680 help 1681 Provide fault-injection capability for MMC IO. 1682 This will make the mmc core return data errors. This is 1683 useful to test the error handling in the mmc block device 1684 and to test how the mmc host driver handles retries from 1685 the block device. 1686 1687config FAULT_INJECTION_STACKTRACE_FILTER 1688 bool "stacktrace filter for fault-injection capabilities" 1689 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 1690 depends on !X86_64 1691 select STACKTRACE 1692 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86 1693 help 1694 Provide stacktrace filter for fault-injection capabilities 1695 1696config ARCH_HAS_KCOV 1697 bool 1698 help 1699 An architecture should select this when it can successfully 1700 build and run with CONFIG_KCOV. This typically requires 1701 disabling instrumentation for some early boot code. 1702 1703config CC_HAS_SANCOV_TRACE_PC 1704 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 1705 1706 1707config KCOV 1708 bool "Code coverage for fuzzing" 1709 depends on ARCH_HAS_KCOV 1710 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 1711 select DEBUG_FS 1712 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 1713 help 1714 KCOV exposes kernel code coverage information in a form suitable 1715 for coverage-guided fuzzing (randomized testing). 1716 1717 If RANDOMIZE_BASE is enabled, PC values will not be stable across 1718 different machines and across reboots. If you need stable PC values, 1719 disable RANDOMIZE_BASE. 1720 1721 For more details, see Documentation/dev-tools/kcov.rst. 1722 1723config KCOV_ENABLE_COMPARISONS 1724 bool "Enable comparison operands collection by KCOV" 1725 depends on KCOV 1726 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 1727 help 1728 KCOV also exposes operands of every comparison in the instrumented 1729 code along with operand sizes and PCs of the comparison instructions. 1730 These operands can be used by fuzzing engines to improve the quality 1731 of fuzzing coverage. 1732 1733config KCOV_INSTRUMENT_ALL 1734 bool "Instrument all code by default" 1735 depends on KCOV 1736 default y 1737 help 1738 If you are doing generic system call fuzzing (like e.g. syzkaller), 1739 then you will want to instrument the whole kernel and you should 1740 say y here. If you are doing more targeted fuzzing (like e.g. 1741 filesystem fuzzing with AFL) then you will want to enable coverage 1742 for more specific subsets of files, and should say n here. 1743 1744menuconfig RUNTIME_TESTING_MENU 1745 bool "Runtime Testing" 1746 def_bool y 1747 1748if RUNTIME_TESTING_MENU 1749 1750config LKDTM 1751 tristate "Linux Kernel Dump Test Tool Module" 1752 depends on DEBUG_FS 1753 help 1754 This module enables testing of the different dumping mechanisms by 1755 inducing system failures at predefined crash points. 1756 If you don't need it: say N 1757 Choose M here to compile this code as a module. The module will be 1758 called lkdtm. 1759 1760 Documentation on how to use the module can be found in 1761 Documentation/fault-injection/provoke-crashes.rst 1762 1763config TEST_LIST_SORT 1764 tristate "Linked list sorting test" 1765 depends on DEBUG_KERNEL || m 1766 help 1767 Enable this to turn on 'list_sort()' function test. This test is 1768 executed only once during system boot (so affects only boot time), 1769 or at module load time. 1770 1771 If unsure, say N. 1772 1773config TEST_SORT 1774 tristate "Array-based sort test" 1775 depends on DEBUG_KERNEL || m 1776 help 1777 This option enables the self-test function of 'sort()' at boot, 1778 or at module load time. 1779 1780 If unsure, say N. 1781 1782config KPROBES_SANITY_TEST 1783 bool "Kprobes sanity tests" 1784 depends on DEBUG_KERNEL 1785 depends on KPROBES 1786 help 1787 This option provides for testing basic kprobes functionality on 1788 boot. Samples of kprobe and kretprobe are inserted and 1789 verified for functionality. 1790 1791 Say N if you are unsure. 1792 1793config BACKTRACE_SELF_TEST 1794 tristate "Self test for the backtrace code" 1795 depends on DEBUG_KERNEL 1796 help 1797 This option provides a kernel module that can be used to test 1798 the kernel stack backtrace code. This option is not useful 1799 for distributions or general kernels, but only for kernel 1800 developers working on architecture code. 1801 1802 Note that if you want to also test saved backtraces, you will 1803 have to enable STACKTRACE as well. 1804 1805 Say N if you are unsure. 1806 1807config RBTREE_TEST 1808 tristate "Red-Black tree test" 1809 depends on DEBUG_KERNEL 1810 help 1811 A benchmark measuring the performance of the rbtree library. 1812 Also includes rbtree invariant checks. 1813 1814config REED_SOLOMON_TEST 1815 tristate "Reed-Solomon library test" 1816 depends on DEBUG_KERNEL || m 1817 select REED_SOLOMON 1818 select REED_SOLOMON_ENC16 1819 select REED_SOLOMON_DEC16 1820 help 1821 This option enables the self-test function of rslib at boot, 1822 or at module load time. 1823 1824 If unsure, say N. 1825 1826config INTERVAL_TREE_TEST 1827 tristate "Interval tree test" 1828 depends on DEBUG_KERNEL 1829 select INTERVAL_TREE 1830 help 1831 A benchmark measuring the performance of the interval tree library 1832 1833config PERCPU_TEST 1834 tristate "Per cpu operations test" 1835 depends on m && DEBUG_KERNEL 1836 help 1837 Enable this option to build test module which validates per-cpu 1838 operations. 1839 1840 If unsure, say N. 1841 1842config ATOMIC64_SELFTEST 1843 tristate "Perform an atomic64_t self-test" 1844 help 1845 Enable this option to test the atomic64_t functions at boot or 1846 at module load time. 1847 1848 If unsure, say N. 1849 1850config ASYNC_RAID6_TEST 1851 tristate "Self test for hardware accelerated raid6 recovery" 1852 depends on ASYNC_RAID6_RECOV 1853 select ASYNC_MEMCPY 1854 ---help--- 1855 This is a one-shot self test that permutes through the 1856 recovery of all the possible two disk failure scenarios for a 1857 N-disk array. Recovery is performed with the asynchronous 1858 raid6 recovery routines, and will optionally use an offload 1859 engine if one is available. 1860 1861 If unsure, say N. 1862 1863config TEST_HEXDUMP 1864 tristate "Test functions located in the hexdump module at runtime" 1865 1866config TEST_STRING_HELPERS 1867 tristate "Test functions located in the string_helpers module at runtime" 1868 1869config TEST_STRSCPY 1870 tristate "Test strscpy*() family of functions at runtime" 1871 1872config TEST_KSTRTOX 1873 tristate "Test kstrto*() family of functions at runtime" 1874 1875config TEST_PRINTF 1876 tristate "Test printf() family of functions at runtime" 1877 1878config TEST_BITMAP 1879 tristate "Test bitmap_*() family of functions at runtime" 1880 help 1881 Enable this option to test the bitmap functions at boot. 1882 1883 If unsure, say N. 1884 1885config TEST_BITFIELD 1886 tristate "Test bitfield functions at runtime" 1887 help 1888 Enable this option to test the bitfield functions at boot. 1889 1890 If unsure, say N. 1891 1892config TEST_UUID 1893 tristate "Test functions located in the uuid module at runtime" 1894 1895config TEST_XARRAY 1896 tristate "Test the XArray code at runtime" 1897 1898config TEST_OVERFLOW 1899 tristate "Test check_*_overflow() functions at runtime" 1900 1901config TEST_RHASHTABLE 1902 tristate "Perform selftest on resizable hash table" 1903 help 1904 Enable this option to test the rhashtable functions at boot. 1905 1906 If unsure, say N. 1907 1908config TEST_HASH 1909 tristate "Perform selftest on hash functions" 1910 help 1911 Enable this option to test the kernel's integer (<linux/hash.h>), 1912 string (<linux/stringhash.h>), and siphash (<linux/siphash.h>) 1913 hash functions on boot (or module load). 1914 1915 This is intended to help people writing architecture-specific 1916 optimized versions. If unsure, say N. 1917 1918config TEST_IDA 1919 tristate "Perform selftest on IDA functions" 1920 1921config TEST_PARMAN 1922 tristate "Perform selftest on priority array manager" 1923 depends on PARMAN 1924 help 1925 Enable this option to test priority array manager on boot 1926 (or module load). 1927 1928 If unsure, say N. 1929 1930config TEST_IRQ_TIMINGS 1931 bool "IRQ timings selftest" 1932 depends on IRQ_TIMINGS 1933 help 1934 Enable this option to test the irq timings code on boot. 1935 1936 If unsure, say N. 1937 1938config TEST_LKM 1939 tristate "Test module loading with 'hello world' module" 1940 depends on m 1941 help 1942 This builds the "test_module" module that emits "Hello, world" 1943 on printk when loaded. It is designed to be used for basic 1944 evaluation of the module loading subsystem (for example when 1945 validating module verification). It lacks any extra dependencies, 1946 and will not normally be loaded by the system unless explicitly 1947 requested by name. 1948 1949 If unsure, say N. 1950 1951config TEST_VMALLOC 1952 tristate "Test module for stress/performance analysis of vmalloc allocator" 1953 default n 1954 depends on MMU 1955 depends on m 1956 help 1957 This builds the "test_vmalloc" module that should be used for 1958 stress and performance analysis. So, any new change for vmalloc 1959 subsystem can be evaluated from performance and stability point 1960 of view. 1961 1962 If unsure, say N. 1963 1964config TEST_USER_COPY 1965 tristate "Test user/kernel boundary protections" 1966 depends on m 1967 help 1968 This builds the "test_user_copy" module that runs sanity checks 1969 on the copy_to/from_user infrastructure, making sure basic 1970 user/kernel boundary testing is working. If it fails to load, 1971 a regression has been detected in the user/kernel memory boundary 1972 protections. 1973 1974 If unsure, say N. 1975 1976config TEST_BPF 1977 tristate "Test BPF filter functionality" 1978 depends on m && NET 1979 help 1980 This builds the "test_bpf" module that runs various test vectors 1981 against the BPF interpreter or BPF JIT compiler depending on the 1982 current setting. This is in particular useful for BPF JIT compiler 1983 development, but also to run regression tests against changes in 1984 the interpreter code. It also enables test stubs for eBPF maps and 1985 verifier used by user space verifier testsuite. 1986 1987 If unsure, say N. 1988 1989config TEST_BLACKHOLE_DEV 1990 tristate "Test blackhole netdev functionality" 1991 depends on m && NET 1992 help 1993 This builds the "test_blackhole_dev" module that validates the 1994 data path through this blackhole netdev. 1995 1996 If unsure, say N. 1997 1998config FIND_BIT_BENCHMARK 1999 tristate "Test find_bit functions" 2000 help 2001 This builds the "test_find_bit" module that measure find_*_bit() 2002 functions performance. 2003 2004 If unsure, say N. 2005 2006config TEST_FIRMWARE 2007 tristate "Test firmware loading via userspace interface" 2008 depends on FW_LOADER 2009 help 2010 This builds the "test_firmware" module that creates a userspace 2011 interface for testing firmware loading. This can be used to 2012 control the triggering of firmware loading without needing an 2013 actual firmware-using device. The contents can be rechecked by 2014 userspace. 2015 2016 If unsure, say N. 2017 2018config TEST_SYSCTL 2019 tristate "sysctl test driver" 2020 depends on PROC_SYSCTL 2021 help 2022 This builds the "test_sysctl" module. This driver enables to test the 2023 proc sysctl interfaces available to drivers safely without affecting 2024 production knobs which might alter system functionality. 2025 2026 If unsure, say N. 2027 2028config SYSCTL_KUNIT_TEST 2029 tristate "KUnit test for sysctl" 2030 depends on KUNIT 2031 help 2032 This builds the proc sysctl unit test, which runs on boot. 2033 Tests the API contract and implementation correctness of sysctl. 2034 For more information on KUnit and unit tests in general please refer 2035 to the KUnit documentation in Documentation/dev-tools/kunit/. 2036 2037 If unsure, say N. 2038 2039config LIST_KUNIT_TEST 2040 tristate "KUnit Test for Kernel Linked-list structures" 2041 depends on KUNIT 2042 help 2043 This builds the linked list KUnit test suite. 2044 It tests that the API and basic functionality of the list_head type 2045 and associated macros. 2046 2047 KUnit tests run during boot and output the results to the debug log 2048 in TAP format (http://testanything.org/). Only useful for kernel devs 2049 running the KUnit test harness, and not intended for inclusion into a 2050 production build. 2051 2052 For more information on KUnit and unit tests in general please refer 2053 to the KUnit documentation in Documentation/dev-tools/kunit/. 2054 2055 If unsure, say N. 2056 2057config TEST_UDELAY 2058 tristate "udelay test driver" 2059 help 2060 This builds the "udelay_test" module that helps to make sure 2061 that udelay() is working properly. 2062 2063 If unsure, say N. 2064 2065config TEST_STATIC_KEYS 2066 tristate "Test static keys" 2067 depends on m 2068 help 2069 Test the static key interfaces. 2070 2071 If unsure, say N. 2072 2073config TEST_KMOD 2074 tristate "kmod stress tester" 2075 depends on m 2076 depends on NETDEVICES && NET_CORE && INET # for TUN 2077 depends on BLOCK 2078 select TEST_LKM 2079 select XFS_FS 2080 select TUN 2081 select BTRFS_FS 2082 help 2083 Test the kernel's module loading mechanism: kmod. kmod implements 2084 support to load modules using the Linux kernel's usermode helper. 2085 This test provides a series of tests against kmod. 2086 2087 Although technically you can either build test_kmod as a module or 2088 into the kernel we disallow building it into the kernel since 2089 it stress tests request_module() and this will very likely cause 2090 some issues by taking over precious threads available from other 2091 module load requests, ultimately this could be fatal. 2092 2093 To run tests run: 2094 2095 tools/testing/selftests/kmod/kmod.sh --help 2096 2097 If unsure, say N. 2098 2099config TEST_DEBUG_VIRTUAL 2100 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 2101 depends on DEBUG_VIRTUAL 2102 help 2103 Test the kernel's ability to detect incorrect calls to 2104 virt_to_phys() done against the non-linear part of the 2105 kernel's virtual address map. 2106 2107 If unsure, say N. 2108 2109config TEST_MEMCAT_P 2110 tristate "Test memcat_p() helper function" 2111 help 2112 Test the memcat_p() helper for correctly merging two 2113 pointer arrays together. 2114 2115 If unsure, say N. 2116 2117config TEST_LIVEPATCH 2118 tristate "Test livepatching" 2119 default n 2120 depends on DYNAMIC_DEBUG 2121 depends on LIVEPATCH 2122 depends on m 2123 help 2124 Test kernel livepatching features for correctness. The tests will 2125 load test modules that will be livepatched in various scenarios. 2126 2127 To run all the livepatching tests: 2128 2129 make -C tools/testing/selftests TARGETS=livepatch run_tests 2130 2131 Alternatively, individual tests may be invoked: 2132 2133 tools/testing/selftests/livepatch/test-callbacks.sh 2134 tools/testing/selftests/livepatch/test-livepatch.sh 2135 tools/testing/selftests/livepatch/test-shadow-vars.sh 2136 2137 If unsure, say N. 2138 2139config TEST_OBJAGG 2140 tristate "Perform selftest on object aggreration manager" 2141 default n 2142 depends on OBJAGG 2143 help 2144 Enable this option to test object aggregation manager on boot 2145 (or module load). 2146 2147 2148config TEST_STACKINIT 2149 tristate "Test level of stack variable initialization" 2150 help 2151 Test if the kernel is zero-initializing stack variables and 2152 padding. Coverage is controlled by compiler flags, 2153 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2154 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2155 2156 If unsure, say N. 2157 2158config TEST_MEMINIT 2159 tristate "Test heap/page initialization" 2160 help 2161 Test if the kernel is zero-initializing heap and page allocations. 2162 This can be useful to test init_on_alloc and init_on_free features. 2163 2164 If unsure, say N. 2165 2166endif # RUNTIME_TESTING_MENU 2167 2168config MEMTEST 2169 bool "Memtest" 2170 ---help--- 2171 This option adds a kernel parameter 'memtest', which allows memtest 2172 to be set. 2173 memtest=0, mean disabled; -- default 2174 memtest=1, mean do 1 test pattern; 2175 ... 2176 memtest=17, mean do 17 test patterns. 2177 If you are unsure how to answer this question, answer N. 2178 2179 2180 2181config HYPERV_TESTING 2182 bool "Microsoft Hyper-V driver testing" 2183 default n 2184 depends on HYPERV && DEBUG_FS 2185 help 2186 Select this option to enable Hyper-V vmbus testing. 2187 2188endmenu # "Kernel Testing and Coverage" 2189 2190endmenu # Kernel hacking 2191