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