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" 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 280config STRIP_ASM_SYMS 281 bool "Strip assembler-generated symbols during link" 282 default n 283 help 284 Strip internal assembler-generated symbols during a link (symbols 285 that look like '.Lxxx') so they don't pollute the output of 286 get_wchan() and suchlike. 287 288config READABLE_ASM 289 bool "Generate readable assembler code" 290 depends on DEBUG_KERNEL 291 help 292 Disable some compiler optimizations that tend to generate human unreadable 293 assembler output. This may make the kernel slightly slower, but it helps 294 to keep kernel developers who have to stare a lot at assembler listings 295 sane. 296 297config HEADERS_INSTALL 298 bool "Install uapi headers to usr/include" 299 depends on !UML 300 help 301 This option will install uapi headers (headers exported to user-space) 302 into the usr/include directory for use during the kernel build. 303 This is unneeded for building the kernel itself, but needed for some 304 user-space program samples. It is also needed by some features such 305 as uapi header sanity checks. 306 307config OPTIMIZE_INLINING 308 def_bool y 309 help 310 This option determines if the kernel forces gcc to inline the functions 311 developers have marked 'inline'. Doing so takes away freedom from gcc to 312 do what it thinks is best, which is desirable for the gcc 3.x series of 313 compilers. The gcc 4.x series have a rewritten inlining algorithm and 314 enabling this option will generate a smaller kernel there. Hopefully 315 this algorithm is so good that allowing gcc 4.x and above to make the 316 decision will become the default in the future. Until then this option 317 is there to test gcc for this. 318 319config DEBUG_SECTION_MISMATCH 320 bool "Enable full Section mismatch analysis" 321 help 322 The section mismatch analysis checks if there are illegal 323 references from one section to another section. 324 During linktime or runtime, some sections are dropped; 325 any use of code/data previously in these sections would 326 most likely result in an oops. 327 In the code, functions and variables are annotated with 328 __init,, etc. (see the full list in include/linux/init.h), 329 which results in the code/data being placed in specific sections. 330 The section mismatch analysis is always performed after a full 331 kernel build, and enabling this option causes the following 332 additional step to occur: 333 - Add the option -fno-inline-functions-called-once to gcc commands. 334 When inlining a function annotated with __init in a non-init 335 function, we would lose the section information and thus 336 the analysis would not catch the illegal reference. 337 This option tells gcc to inline less (but it does result in 338 a larger kernel). 339 340config SECTION_MISMATCH_WARN_ONLY 341 bool "Make section mismatch errors non-fatal" 342 default y 343 help 344 If you say N here, the build process will fail if there are any 345 section mismatch, instead of just throwing warnings. 346 347 If unsure, say Y. 348 349# 350# Select this config option from the architecture Kconfig, if it 351# is preferred to always offer frame pointers as a config 352# option on the architecture (regardless of KERNEL_DEBUG): 353# 354config ARCH_WANT_FRAME_POINTERS 355 bool 356 357config FRAME_POINTER 358 bool "Compile the kernel with frame pointers" 359 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS 360 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 361 help 362 If you say Y here the resulting kernel image will be slightly 363 larger and slower, but it gives very useful debugging information 364 in case of kernel bugs. (precise oopses/stacktraces/warnings) 365 366config STACK_VALIDATION 367 bool "Compile-time stack metadata validation" 368 depends on HAVE_STACK_VALIDATION 369 default n 370 help 371 Add compile-time checks to validate stack metadata, including frame 372 pointers (if CONFIG_FRAME_POINTER is enabled). This helps ensure 373 that runtime stack traces are more reliable. 374 375 This is also a prerequisite for generation of ORC unwind data, which 376 is needed for CONFIG_UNWINDER_ORC. 377 378 For more information, see 379 tools/objtool/Documentation/stack-validation.txt. 380 381config DEBUG_FORCE_WEAK_PER_CPU 382 bool "Force weak per-cpu definitions" 383 depends on DEBUG_KERNEL 384 help 385 s390 and alpha require percpu variables in modules to be 386 defined weak to work around addressing range issue which 387 puts the following two restrictions on percpu variable 388 definitions. 389 390 1. percpu symbols must be unique whether static or not 391 2. percpu variables can't be defined inside a function 392 393 To ensure that generic code follows the above rules, this 394 option forces all percpu variables to be defined as weak. 395 396endmenu # "Compiler options" 397 398menu "Generic Kernel Debugging Instruments" 399 400config MAGIC_SYSRQ 401 bool "Magic SysRq key" 402 depends on !UML 403 help 404 If you say Y here, you will have some control over the system even 405 if the system crashes for example during kernel debugging (e.g., you 406 will be able to flush the buffer cache to disk, reboot the system 407 immediately or dump some status information). This is accomplished 408 by pressing various keys while holding SysRq (Alt+PrintScreen). It 409 also works on a serial console (on PC hardware at least), if you 410 send a BREAK and then within 5 seconds a command keypress. The 411 keys are documented in <file:Documentation/admin-guide/sysrq.rst>. 412 Don't say Y unless you really know what this hack does. 413 414config MAGIC_SYSRQ_DEFAULT_ENABLE 415 hex "Enable magic SysRq key functions by default" 416 depends on MAGIC_SYSRQ 417 default 0x1 418 help 419 Specifies which SysRq key functions are enabled by default. 420 This may be set to 1 or 0 to enable or disable them all, or 421 to a bitmask as described in Documentation/admin-guide/sysrq.rst. 422 423config MAGIC_SYSRQ_SERIAL 424 bool "Enable magic SysRq key over serial" 425 depends on MAGIC_SYSRQ 426 default y 427 help 428 Many embedded boards have a disconnected TTL level serial which can 429 generate some garbage that can lead to spurious false sysrq detects. 430 This option allows you to decide whether you want to enable the 431 magic SysRq key. 432 433config MAGIC_SYSRQ_SERIAL_SEQUENCE 434 string "Char sequence that enables magic SysRq over serial" 435 depends on MAGIC_SYSRQ_SERIAL 436 default "" 437 help 438 Specifies a sequence of characters that can follow BREAK to enable 439 SysRq on a serial console. 440 441 If unsure, leave an empty string and the option will not be enabled. 442 443config DEBUG_FS 444 bool "Debug Filesystem" 445 help 446 debugfs is a virtual file system that kernel developers use to put 447 debugging files into. Enable this option to be able to read and 448 write to these files. 449 450 For detailed documentation on the debugfs API, see 451 Documentation/filesystems/. 452 453 If unsure, say N. 454 455source "lib/Kconfig.kgdb" 456 457source "lib/Kconfig.ubsan" 458 459endmenu 460 461config DEBUG_KERNEL 462 bool "Kernel debugging" 463 help 464 Say Y here if you are developing drivers or trying to debug and 465 identify kernel problems. 466 467config DEBUG_MISC 468 bool "Miscellaneous debug code" 469 default DEBUG_KERNEL 470 depends on DEBUG_KERNEL 471 help 472 Say Y here if you need to enable miscellaneous debug code that should 473 be under a more specific debug option but isn't. 474 475 476menu "Memory Debugging" 477 478source "mm/Kconfig.debug" 479 480config DEBUG_OBJECTS 481 bool "Debug object operations" 482 depends on DEBUG_KERNEL 483 help 484 If you say Y here, additional code will be inserted into the 485 kernel to track the life time of various objects and validate 486 the operations on those objects. 487 488config DEBUG_OBJECTS_SELFTEST 489 bool "Debug objects selftest" 490 depends on DEBUG_OBJECTS 491 help 492 This enables the selftest of the object debug code. 493 494config DEBUG_OBJECTS_FREE 495 bool "Debug objects in freed memory" 496 depends on DEBUG_OBJECTS 497 help 498 This enables checks whether a k/v free operation frees an area 499 which contains an object which has not been deactivated 500 properly. This can make kmalloc/kfree-intensive workloads 501 much slower. 502 503config DEBUG_OBJECTS_TIMERS 504 bool "Debug timer objects" 505 depends on DEBUG_OBJECTS 506 help 507 If you say Y here, additional code will be inserted into the 508 timer routines to track the life time of timer objects and 509 validate the timer operations. 510 511config DEBUG_OBJECTS_WORK 512 bool "Debug work objects" 513 depends on DEBUG_OBJECTS 514 help 515 If you say Y here, additional code will be inserted into the 516 work queue routines to track the life time of work objects and 517 validate the work operations. 518 519config DEBUG_OBJECTS_RCU_HEAD 520 bool "Debug RCU callbacks objects" 521 depends on DEBUG_OBJECTS 522 help 523 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 524 525config DEBUG_OBJECTS_PERCPU_COUNTER 526 bool "Debug percpu counter objects" 527 depends on DEBUG_OBJECTS 528 help 529 If you say Y here, additional code will be inserted into the 530 percpu counter routines to track the life time of percpu counter 531 objects and validate the percpu counter operations. 532 533config DEBUG_OBJECTS_ENABLE_DEFAULT 534 int "debug_objects bootup default value (0-1)" 535 range 0 1 536 default "1" 537 depends on DEBUG_OBJECTS 538 help 539 Debug objects boot parameter default value 540 541config DEBUG_SLAB 542 bool "Debug slab memory allocations" 543 depends on DEBUG_KERNEL && SLAB 544 help 545 Say Y here to have the kernel do limited verification on memory 546 allocation as well as poisoning memory on free to catch use of freed 547 memory. This can make kmalloc/kfree-intensive workloads much slower. 548 549config SLUB_DEBUG_ON 550 bool "SLUB debugging on by default" 551 depends on SLUB && SLUB_DEBUG 552 default n 553 help 554 Boot with debugging on by default. SLUB boots by default with 555 the runtime debug capabilities switched off. Enabling this is 556 equivalent to specifying the "slub_debug" parameter on boot. 557 There is no support for more fine grained debug control like 558 possible with slub_debug=xxx. SLUB debugging may be switched 559 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying 560 "slub_debug=-". 561 562config SLUB_STATS 563 default n 564 bool "Enable SLUB performance statistics" 565 depends on SLUB && SYSFS 566 help 567 SLUB statistics are useful to debug SLUBs allocation behavior in 568 order find ways to optimize the allocator. This should never be 569 enabled for production use since keeping statistics slows down 570 the allocator by a few percentage points. The slabinfo command 571 supports the determination of the most active slabs to figure 572 out which slabs are relevant to a particular load. 573 Try running: slabinfo -DA 574 575config HAVE_DEBUG_KMEMLEAK 576 bool 577 578config DEBUG_KMEMLEAK 579 bool "Kernel memory leak detector" 580 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK 581 select DEBUG_FS 582 select STACKTRACE if STACKTRACE_SUPPORT 583 select KALLSYMS 584 select CRC32 585 help 586 Say Y here if you want to enable the memory leak 587 detector. The memory allocation/freeing is traced in a way 588 similar to the Boehm's conservative garbage collector, the 589 difference being that the orphan objects are not freed but 590 only shown in /sys/kernel/debug/kmemleak. Enabling this 591 feature will introduce an overhead to memory 592 allocations. See Documentation/dev-tools/kmemleak.rst for more 593 details. 594 595 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances 596 of finding leaks due to the slab objects poisoning. 597 598 In order to access the kmemleak file, debugfs needs to be 599 mounted (usually at /sys/kernel/debug). 600 601config DEBUG_KMEMLEAK_MEM_POOL_SIZE 602 int "Kmemleak memory pool size" 603 depends on DEBUG_KMEMLEAK 604 range 200 1000000 605 default 16000 606 help 607 Kmemleak must track all the memory allocations to avoid 608 reporting false positives. Since memory may be allocated or 609 freed before kmemleak is fully initialised, use a static pool 610 of metadata objects to track such callbacks. After kmemleak is 611 fully initialised, this memory pool acts as an emergency one 612 if slab allocations fail. 613 614config DEBUG_KMEMLEAK_TEST 615 tristate "Simple test for the kernel memory leak detector" 616 depends on DEBUG_KMEMLEAK && m 617 help 618 This option enables a module that explicitly leaks memory. 619 620 If unsure, say N. 621 622config DEBUG_KMEMLEAK_DEFAULT_OFF 623 bool "Default kmemleak to off" 624 depends on DEBUG_KMEMLEAK 625 help 626 Say Y here to disable kmemleak by default. It can then be enabled 627 on the command line via kmemleak=on. 628 629config DEBUG_KMEMLEAK_AUTO_SCAN 630 bool "Enable kmemleak auto scan thread on boot up" 631 default y 632 depends on DEBUG_KMEMLEAK 633 help 634 Depending on the cpu, kmemleak scan may be cpu intensive and can 635 stall user tasks at times. This option enables/disables automatic 636 kmemleak scan at boot up. 637 638 Say N here to disable kmemleak auto scan thread to stop automatic 639 scanning. Disabling this option disables automatic reporting of 640 memory leaks. 641 642 If unsure, say Y. 643 644config DEBUG_STACK_USAGE 645 bool "Stack utilization instrumentation" 646 depends on DEBUG_KERNEL && !IA64 647 help 648 Enables the display of the minimum amount of free stack which each 649 task has ever had available in the sysrq-T and sysrq-P debug output. 650 651 This option will slow down process creation somewhat. 652 653config SCHED_STACK_END_CHECK 654 bool "Detect stack corruption on calls to schedule()" 655 depends on DEBUG_KERNEL 656 default n 657 help 658 This option checks for a stack overrun on calls to schedule(). 659 If the stack end location is found to be over written always panic as 660 the content of the corrupted region can no longer be trusted. 661 This is to ensure no erroneous behaviour occurs which could result in 662 data corruption or a sporadic crash at a later stage once the region 663 is examined. The runtime overhead introduced is minimal. 664 665config DEBUG_VM 666 bool "Debug VM" 667 depends on DEBUG_KERNEL 668 help 669 Enable this to turn on extended checks in the virtual-memory system 670 that may impact performance. 671 672 If unsure, say N. 673 674config DEBUG_VM_VMACACHE 675 bool "Debug VMA caching" 676 depends on DEBUG_VM 677 help 678 Enable this to turn on VMA caching debug information. Doing so 679 can cause significant overhead, so only enable it in non-production 680 environments. 681 682 If unsure, say N. 683 684config DEBUG_VM_RB 685 bool "Debug VM red-black trees" 686 depends on DEBUG_VM 687 help 688 Enable VM red-black tree debugging information and extra validations. 689 690 If unsure, say N. 691 692config DEBUG_VM_PGFLAGS 693 bool "Debug page-flags operations" 694 depends on DEBUG_VM 695 help 696 Enables extra validation on page flags operations. 697 698 If unsure, say N. 699 700config ARCH_HAS_DEBUG_VIRTUAL 701 bool 702 703config DEBUG_VIRTUAL 704 bool "Debug VM translations" 705 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL 706 help 707 Enable some costly sanity checks in virtual to page code. This can 708 catch mistakes with virt_to_page() and friends. 709 710 If unsure, say N. 711 712config DEBUG_NOMMU_REGIONS 713 bool "Debug the global anon/private NOMMU mapping region tree" 714 depends on DEBUG_KERNEL && !MMU 715 help 716 This option causes the global tree of anonymous and private mapping 717 regions to be regularly checked for invalid topology. 718 719config DEBUG_MEMORY_INIT 720 bool "Debug memory initialisation" if EXPERT 721 default !EXPERT 722 help 723 Enable this for additional checks during memory initialisation. 724 The sanity checks verify aspects of the VM such as the memory model 725 and other information provided by the architecture. Verbose 726 information will be printed at KERN_DEBUG loglevel depending 727 on the mminit_loglevel= command-line option. 728 729 If unsure, say Y 730 731config MEMORY_NOTIFIER_ERROR_INJECT 732 tristate "Memory hotplug notifier error injection module" 733 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION 734 help 735 This option provides the ability to inject artificial errors to 736 memory hotplug notifier chain callbacks. It is controlled through 737 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 738 739 If the notifier call chain should be failed with some events 740 notified, write the error code to "actions/<notifier event>/error". 741 742 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 743 744 # cd /sys/kernel/debug/notifier-error-inject/memory 745 # echo -12 > actions/MEM_GOING_OFFLINE/error 746 # echo offline > /sys/devices/system/memory/memoryXXX/state 747 bash: echo: write error: Cannot allocate memory 748 749 To compile this code as a module, choose M here: the module will 750 be called memory-notifier-error-inject. 751 752 If unsure, say N. 753 754config DEBUG_PER_CPU_MAPS 755 bool "Debug access to per_cpu maps" 756 depends on DEBUG_KERNEL 757 depends on SMP 758 help 759 Say Y to verify that the per_cpu map being accessed has 760 been set up. This adds a fair amount of code to kernel memory 761 and decreases performance. 762 763 Say N if unsure. 764 765config DEBUG_HIGHMEM 766 bool "Highmem debugging" 767 depends on DEBUG_KERNEL && HIGHMEM 768 help 769 This option enables additional error checking for high memory 770 systems. Disable for production systems. 771 772config HAVE_DEBUG_STACKOVERFLOW 773 bool 774 775config DEBUG_STACKOVERFLOW 776 bool "Check for stack overflows" 777 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 778 ---help--- 779 Say Y here if you want to check for overflows of kernel, IRQ 780 and exception stacks (if your architecture uses them). This 781 option will show detailed messages if free stack space drops 782 below a certain limit. 783 784 These kinds of bugs usually occur when call-chains in the 785 kernel get too deep, especially when interrupts are 786 involved. 787 788 Use this in cases where you see apparently random memory 789 corruption, especially if it appears in 'struct thread_info' 790 791 If in doubt, say "N". 792 793source "lib/Kconfig.kasan" 794 795endmenu # "Memory Debugging" 796 797config DEBUG_SHIRQ 798 bool "Debug shared IRQ handlers" 799 depends on DEBUG_KERNEL 800 help 801 Enable this to generate a spurious interrupt as soon as a shared 802 interrupt handler is registered, and just before one is deregistered. 803 Drivers ought to be able to handle interrupts coming in at those 804 points; some don't and need to be caught. 805 806menu "Debug Oops, Lockups and Hangs" 807 808config PANIC_ON_OOPS 809 bool "Panic on Oops" 810 help 811 Say Y here to enable the kernel to panic when it oopses. This 812 has the same effect as setting oops=panic on the kernel command 813 line. 814 815 This feature is useful to ensure that the kernel does not do 816 anything erroneous after an oops which could result in data 817 corruption or other issues. 818 819 Say N if unsure. 820 821config PANIC_ON_OOPS_VALUE 822 int 823 range 0 1 824 default 0 if !PANIC_ON_OOPS 825 default 1 if PANIC_ON_OOPS 826 827config PANIC_TIMEOUT 828 int "panic timeout" 829 default 0 830 help 831 Set the timeout value (in seconds) until a reboot occurs when the 832 the kernel panics. If n = 0, then we wait forever. A timeout 833 value n > 0 will wait n seconds before rebooting, while a timeout 834 value n < 0 will reboot immediately. 835 836config LOCKUP_DETECTOR 837 bool 838 839config SOFTLOCKUP_DETECTOR 840 bool "Detect Soft Lockups" 841 depends on DEBUG_KERNEL && !S390 842 select LOCKUP_DETECTOR 843 help 844 Say Y here to enable the kernel to act as a watchdog to detect 845 soft lockups. 846 847 Softlockups are bugs that cause the kernel to loop in kernel 848 mode for more than 20 seconds, without giving other tasks a 849 chance to run. The current stack trace is displayed upon 850 detection and the system will stay locked up. 851 852config BOOTPARAM_SOFTLOCKUP_PANIC 853 bool "Panic (Reboot) On Soft Lockups" 854 depends on SOFTLOCKUP_DETECTOR 855 help 856 Say Y here to enable the kernel to panic on "soft lockups", 857 which are bugs that cause the kernel to loop in kernel 858 mode for more than 20 seconds (configurable using the watchdog_thresh 859 sysctl), without giving other tasks a chance to run. 860 861 The panic can be used in combination with panic_timeout, 862 to cause the system to reboot automatically after a 863 lockup has been detected. This feature is useful for 864 high-availability systems that have uptime guarantees and 865 where a lockup must be resolved ASAP. 866 867 Say N if unsure. 868 869config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE 870 int 871 depends on SOFTLOCKUP_DETECTOR 872 range 0 1 873 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC 874 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC 875 876config HARDLOCKUP_DETECTOR_PERF 877 bool 878 select SOFTLOCKUP_DETECTOR 879 880# 881# Enables a timestamp based low pass filter to compensate for perf based 882# hard lockup detection which runs too fast due to turbo modes. 883# 884config HARDLOCKUP_CHECK_TIMESTAMP 885 bool 886 887# 888# arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard 889# lockup detector rather than the perf based detector. 890# 891config HARDLOCKUP_DETECTOR 892 bool "Detect Hard Lockups" 893 depends on DEBUG_KERNEL && !S390 894 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH 895 select LOCKUP_DETECTOR 896 select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF 897 select HARDLOCKUP_DETECTOR_ARCH if HAVE_HARDLOCKUP_DETECTOR_ARCH 898 help 899 Say Y here to enable the kernel to act as a watchdog to detect 900 hard lockups. 901 902 Hardlockups are bugs that cause the CPU to loop in kernel mode 903 for more than 10 seconds, without letting other interrupts have a 904 chance to run. The current stack trace is displayed upon detection 905 and the system will stay locked up. 906 907config BOOTPARAM_HARDLOCKUP_PANIC 908 bool "Panic (Reboot) On Hard Lockups" 909 depends on HARDLOCKUP_DETECTOR 910 help 911 Say Y here to enable the kernel to panic on "hard lockups", 912 which are bugs that cause the kernel to loop in kernel 913 mode with interrupts disabled for more than 10 seconds (configurable 914 using the watchdog_thresh sysctl). 915 916 Say N if unsure. 917 918config BOOTPARAM_HARDLOCKUP_PANIC_VALUE 919 int 920 depends on HARDLOCKUP_DETECTOR 921 range 0 1 922 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC 923 default 1 if BOOTPARAM_HARDLOCKUP_PANIC 924 925config DETECT_HUNG_TASK 926 bool "Detect Hung Tasks" 927 depends on DEBUG_KERNEL 928 default SOFTLOCKUP_DETECTOR 929 help 930 Say Y here to enable the kernel to detect "hung tasks", 931 which are bugs that cause the task to be stuck in 932 uninterruptible "D" state indefinitely. 933 934 When a hung task is detected, the kernel will print the 935 current stack trace (which you should report), but the 936 task will stay in uninterruptible state. If lockdep is 937 enabled then all held locks will also be reported. This 938 feature has negligible overhead. 939 940config DEFAULT_HUNG_TASK_TIMEOUT 941 int "Default timeout for hung task detection (in seconds)" 942 depends on DETECT_HUNG_TASK 943 default 120 944 help 945 This option controls the default timeout (in seconds) used 946 to determine when a task has become non-responsive and should 947 be considered hung. 948 949 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 950 sysctl or by writing a value to 951 /proc/sys/kernel/hung_task_timeout_secs. 952 953 A timeout of 0 disables the check. The default is two minutes. 954 Keeping the default should be fine in most cases. 955 956config BOOTPARAM_HUNG_TASK_PANIC 957 bool "Panic (Reboot) On Hung Tasks" 958 depends on DETECT_HUNG_TASK 959 help 960 Say Y here to enable the kernel to panic on "hung tasks", 961 which are bugs that cause the kernel to leave a task stuck 962 in uninterruptible "D" state. 963 964 The panic can be used in combination with panic_timeout, 965 to cause the system to reboot automatically after a 966 hung task has been detected. This feature is useful for 967 high-availability systems that have uptime guarantees and 968 where a hung tasks must be resolved ASAP. 969 970 Say N if unsure. 971 972config BOOTPARAM_HUNG_TASK_PANIC_VALUE 973 int 974 depends on DETECT_HUNG_TASK 975 range 0 1 976 default 0 if !BOOTPARAM_HUNG_TASK_PANIC 977 default 1 if BOOTPARAM_HUNG_TASK_PANIC 978 979config WQ_WATCHDOG 980 bool "Detect Workqueue Stalls" 981 depends on DEBUG_KERNEL 982 help 983 Say Y here to enable stall detection on workqueues. If a 984 worker pool doesn't make forward progress on a pending work 985 item for over a given amount of time, 30s by default, a 986 warning message is printed along with dump of workqueue 987 state. This can be configured through kernel parameter 988 "workqueue.watchdog_thresh" and its sysfs counterpart. 989 990endmenu # "Debug lockups and hangs" 991 992menu "Scheduler Debugging" 993 994config SCHED_DEBUG 995 bool "Collect scheduler debugging info" 996 depends on DEBUG_KERNEL && PROC_FS 997 default y 998 help 999 If you say Y here, the /proc/sched_debug file will be provided 1000 that can help debug the scheduler. The runtime overhead of this 1001 option is minimal. 1002 1003config SCHED_INFO 1004 bool 1005 default n 1006 1007config SCHEDSTATS 1008 bool "Collect scheduler statistics" 1009 depends on DEBUG_KERNEL && PROC_FS 1010 select SCHED_INFO 1011 help 1012 If you say Y here, additional code will be inserted into the 1013 scheduler and related routines to collect statistics about 1014 scheduler behavior and provide them in /proc/schedstat. These 1015 stats may be useful for both tuning and debugging the scheduler 1016 If you aren't debugging the scheduler or trying to tune a specific 1017 application, you can say N to avoid the very slight overhead 1018 this adds. 1019 1020endmenu 1021 1022config DEBUG_TIMEKEEPING 1023 bool "Enable extra timekeeping sanity checking" 1024 help 1025 This option will enable additional timekeeping sanity checks 1026 which may be helpful when diagnosing issues where timekeeping 1027 problems are suspected. 1028 1029 This may include checks in the timekeeping hotpaths, so this 1030 option may have a (very small) performance impact to some 1031 workloads. 1032 1033 If unsure, say N. 1034 1035config DEBUG_PREEMPT 1036 bool "Debug preemptible kernel" 1037 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1038 default y 1039 help 1040 If you say Y here then the kernel will use a debug variant of the 1041 commonly used smp_processor_id() function and will print warnings 1042 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1043 will detect preemption count underflows. 1044 1045menu "Lock Debugging (spinlocks, mutexes, etc...)" 1046 1047config LOCK_DEBUGGING_SUPPORT 1048 bool 1049 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1050 default y 1051 1052config PROVE_LOCKING 1053 bool "Lock debugging: prove locking correctness" 1054 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1055 select LOCKDEP 1056 select DEBUG_SPINLOCK 1057 select DEBUG_MUTEXES 1058 select DEBUG_RT_MUTEXES if RT_MUTEXES 1059 select DEBUG_RWSEMS 1060 select DEBUG_WW_MUTEX_SLOWPATH 1061 select DEBUG_LOCK_ALLOC 1062 select TRACE_IRQFLAGS 1063 default n 1064 help 1065 This feature enables the kernel to prove that all locking 1066 that occurs in the kernel runtime is mathematically 1067 correct: that under no circumstance could an arbitrary (and 1068 not yet triggered) combination of observed locking 1069 sequences (on an arbitrary number of CPUs, running an 1070 arbitrary number of tasks and interrupt contexts) cause a 1071 deadlock. 1072 1073 In short, this feature enables the kernel to report locking 1074 related deadlocks before they actually occur. 1075 1076 The proof does not depend on how hard and complex a 1077 deadlock scenario would be to trigger: how many 1078 participant CPUs, tasks and irq-contexts would be needed 1079 for it to trigger. The proof also does not depend on 1080 timing: if a race and a resulting deadlock is possible 1081 theoretically (no matter how unlikely the race scenario 1082 is), it will be proven so and will immediately be 1083 reported by the kernel (once the event is observed that 1084 makes the deadlock theoretically possible). 1085 1086 If a deadlock is impossible (i.e. the locking rules, as 1087 observed by the kernel, are mathematically correct), the 1088 kernel reports nothing. 1089 1090 NOTE: this feature can also be enabled for rwlocks, mutexes 1091 and rwsems - in which case all dependencies between these 1092 different locking variants are observed and mapped too, and 1093 the proof of observed correctness is also maintained for an 1094 arbitrary combination of these separate locking variants. 1095 1096 For more details, see Documentation/locking/lockdep-design.rst. 1097 1098config PROVE_RAW_LOCK_NESTING 1099 bool "Enable raw_spinlock - spinlock nesting checks" 1100 depends on PROVE_LOCKING 1101 default n 1102 help 1103 Enable the raw_spinlock vs. spinlock nesting checks which ensure 1104 that the lock nesting rules for PREEMPT_RT enabled kernels are 1105 not violated. 1106 1107 NOTE: There are known nesting problems. So if you enable this 1108 option expect lockdep splats until these problems have been fully 1109 addressed which is work in progress. This config switch allows to 1110 identify and analyze these problems. It will be removed and the 1111 check permanentely enabled once the main issues have been fixed. 1112 1113 If unsure, select N. 1114 1115config LOCK_STAT 1116 bool "Lock usage statistics" 1117 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1118 select LOCKDEP 1119 select DEBUG_SPINLOCK 1120 select DEBUG_MUTEXES 1121 select DEBUG_RT_MUTEXES if RT_MUTEXES 1122 select DEBUG_LOCK_ALLOC 1123 default n 1124 help 1125 This feature enables tracking lock contention points 1126 1127 For more details, see Documentation/locking/lockstat.rst 1128 1129 This also enables lock events required by "perf lock", 1130 subcommand of perf. 1131 If you want to use "perf lock", you also need to turn on 1132 CONFIG_EVENT_TRACING. 1133 1134 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1135 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1136 1137config DEBUG_RT_MUTEXES 1138 bool "RT Mutex debugging, deadlock detection" 1139 depends on DEBUG_KERNEL && RT_MUTEXES 1140 help 1141 This allows rt mutex semantics violations and rt mutex related 1142 deadlocks (lockups) to be detected and reported automatically. 1143 1144config DEBUG_SPINLOCK 1145 bool "Spinlock and rw-lock debugging: basic checks" 1146 depends on DEBUG_KERNEL 1147 select UNINLINE_SPIN_UNLOCK 1148 help 1149 Say Y here and build SMP to catch missing spinlock initialization 1150 and certain other kinds of spinlock errors commonly made. This is 1151 best used in conjunction with the NMI watchdog so that spinlock 1152 deadlocks are also debuggable. 1153 1154config DEBUG_MUTEXES 1155 bool "Mutex debugging: basic checks" 1156 depends on DEBUG_KERNEL 1157 help 1158 This feature allows mutex semantics violations to be detected and 1159 reported. 1160 1161config DEBUG_WW_MUTEX_SLOWPATH 1162 bool "Wait/wound mutex debugging: Slowpath testing" 1163 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1164 select DEBUG_LOCK_ALLOC 1165 select DEBUG_SPINLOCK 1166 select DEBUG_MUTEXES 1167 help 1168 This feature enables slowpath testing for w/w mutex users by 1169 injecting additional -EDEADLK wound/backoff cases. Together with 1170 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1171 will test all possible w/w mutex interface abuse with the 1172 exception of simply not acquiring all the required locks. 1173 Note that this feature can introduce significant overhead, so 1174 it really should not be enabled in a production or distro kernel, 1175 even a debug kernel. If you are a driver writer, enable it. If 1176 you are a distro, do not. 1177 1178config DEBUG_RWSEMS 1179 bool "RW Semaphore debugging: basic checks" 1180 depends on DEBUG_KERNEL 1181 help 1182 This debugging feature allows mismatched rw semaphore locks 1183 and unlocks to be detected and reported. 1184 1185config DEBUG_LOCK_ALLOC 1186 bool "Lock debugging: detect incorrect freeing of live locks" 1187 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1188 select DEBUG_SPINLOCK 1189 select DEBUG_MUTEXES 1190 select DEBUG_RT_MUTEXES if RT_MUTEXES 1191 select LOCKDEP 1192 help 1193 This feature will check whether any held lock (spinlock, rwlock, 1194 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1195 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1196 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1197 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1198 held during task exit. 1199 1200config LOCKDEP 1201 bool 1202 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1203 select STACKTRACE 1204 select FRAME_POINTER if !MIPS && !PPC && !ARM && !S390 && !MICROBLAZE && !ARC && !X86 1205 select KALLSYMS 1206 select KALLSYMS_ALL 1207 1208config LOCKDEP_SMALL 1209 bool 1210 1211config DEBUG_LOCKDEP 1212 bool "Lock dependency engine debugging" 1213 depends on DEBUG_KERNEL && LOCKDEP 1214 help 1215 If you say Y here, the lock dependency engine will do 1216 additional runtime checks to debug itself, at the price 1217 of more runtime overhead. 1218 1219config DEBUG_ATOMIC_SLEEP 1220 bool "Sleep inside atomic section checking" 1221 select PREEMPT_COUNT 1222 depends on DEBUG_KERNEL 1223 depends on !ARCH_NO_PREEMPT 1224 help 1225 If you say Y here, various routines which may sleep will become very 1226 noisy if they are called inside atomic sections: when a spinlock is 1227 held, inside an rcu read side critical section, inside preempt disabled 1228 sections, inside an interrupt, etc... 1229 1230config DEBUG_LOCKING_API_SELFTESTS 1231 bool "Locking API boot-time self-tests" 1232 depends on DEBUG_KERNEL 1233 help 1234 Say Y here if you want the kernel to run a short self-test during 1235 bootup. The self-test checks whether common types of locking bugs 1236 are detected by debugging mechanisms or not. (if you disable 1237 lock debugging then those bugs wont be detected of course.) 1238 The following locking APIs are covered: spinlocks, rwlocks, 1239 mutexes and rwsems. 1240 1241config LOCK_TORTURE_TEST 1242 tristate "torture tests for locking" 1243 depends on DEBUG_KERNEL 1244 select TORTURE_TEST 1245 help 1246 This option provides a kernel module that runs torture tests 1247 on kernel locking primitives. The kernel module may be built 1248 after the fact on the running kernel to be tested, if desired. 1249 1250 Say Y here if you want kernel locking-primitive torture tests 1251 to be built into the kernel. 1252 Say M if you want these torture tests to build as a module. 1253 Say N if you are unsure. 1254 1255config WW_MUTEX_SELFTEST 1256 tristate "Wait/wound mutex selftests" 1257 help 1258 This option provides a kernel module that runs tests on the 1259 on the struct ww_mutex locking API. 1260 1261 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1262 with this test harness. 1263 1264 Say M if you want these self tests to build as a module. 1265 Say N if you are unsure. 1266 1267endmenu # lock debugging 1268 1269config TRACE_IRQFLAGS 1270 bool 1271 help 1272 Enables hooks to interrupt enabling and disabling for 1273 either tracing or lock debugging. 1274 1275config STACKTRACE 1276 bool "Stack backtrace support" 1277 depends on STACKTRACE_SUPPORT 1278 help 1279 This option causes the kernel to create a /proc/pid/stack for 1280 every process, showing its current stack trace. 1281 It is also used by various kernel debugging features that require 1282 stack trace generation. 1283 1284config WARN_ALL_UNSEEDED_RANDOM 1285 bool "Warn for all uses of unseeded randomness" 1286 default n 1287 help 1288 Some parts of the kernel contain bugs relating to their use of 1289 cryptographically secure random numbers before it's actually possible 1290 to generate those numbers securely. This setting ensures that these 1291 flaws don't go unnoticed, by enabling a message, should this ever 1292 occur. This will allow people with obscure setups to know when things 1293 are going wrong, so that they might contact developers about fixing 1294 it. 1295 1296 Unfortunately, on some models of some architectures getting 1297 a fully seeded CRNG is extremely difficult, and so this can 1298 result in dmesg getting spammed for a surprisingly long 1299 time. This is really bad from a security perspective, and 1300 so architecture maintainers really need to do what they can 1301 to get the CRNG seeded sooner after the system is booted. 1302 However, since users cannot do anything actionable to 1303 address this, by default the kernel will issue only a single 1304 warning for the first use of unseeded randomness. 1305 1306 Say Y here if you want to receive warnings for all uses of 1307 unseeded randomness. This will be of use primarily for 1308 those developers interested in improving the security of 1309 Linux kernels running on their architecture (or 1310 subarchitecture). 1311 1312config DEBUG_KOBJECT 1313 bool "kobject debugging" 1314 depends on DEBUG_KERNEL 1315 help 1316 If you say Y here, some extra kobject debugging messages will be sent 1317 to the syslog. 1318 1319config DEBUG_KOBJECT_RELEASE 1320 bool "kobject release debugging" 1321 depends on DEBUG_OBJECTS_TIMERS 1322 help 1323 kobjects are reference counted objects. This means that their 1324 last reference count put is not predictable, and the kobject can 1325 live on past the point at which a driver decides to drop it's 1326 initial reference to the kobject gained on allocation. An 1327 example of this would be a struct device which has just been 1328 unregistered. 1329 1330 However, some buggy drivers assume that after such an operation, 1331 the memory backing the kobject can be immediately freed. This 1332 goes completely against the principles of a refcounted object. 1333 1334 If you say Y here, the kernel will delay the release of kobjects 1335 on the last reference count to improve the visibility of this 1336 kind of kobject release bug. 1337 1338config HAVE_DEBUG_BUGVERBOSE 1339 bool 1340 1341menu "Debug kernel data structures" 1342 1343config DEBUG_LIST 1344 bool "Debug linked list manipulation" 1345 depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION 1346 help 1347 Enable this to turn on extended checks in the linked-list 1348 walking routines. 1349 1350 If unsure, say N. 1351 1352config DEBUG_PLIST 1353 bool "Debug priority linked list manipulation" 1354 depends on DEBUG_KERNEL 1355 help 1356 Enable this to turn on extended checks in the priority-ordered 1357 linked-list (plist) walking routines. This checks the entire 1358 list multiple times during each manipulation. 1359 1360 If unsure, say N. 1361 1362config DEBUG_SG 1363 bool "Debug SG table operations" 1364 depends on DEBUG_KERNEL 1365 help 1366 Enable this to turn on checks on scatter-gather tables. This can 1367 help find problems with drivers that do not properly initialize 1368 their sg tables. 1369 1370 If unsure, say N. 1371 1372config DEBUG_NOTIFIERS 1373 bool "Debug notifier call chains" 1374 depends on DEBUG_KERNEL 1375 help 1376 Enable this to turn on sanity checking for notifier call chains. 1377 This is most useful for kernel developers to make sure that 1378 modules properly unregister themselves from notifier chains. 1379 This is a relatively cheap check but if you care about maximum 1380 performance, say N. 1381 1382config BUG_ON_DATA_CORRUPTION 1383 bool "Trigger a BUG when data corruption is detected" 1384 select DEBUG_LIST 1385 help 1386 Select this option if the kernel should BUG when it encounters 1387 data corruption in kernel memory structures when they get checked 1388 for validity. 1389 1390 If unsure, say N. 1391 1392endmenu 1393 1394config DEBUG_CREDENTIALS 1395 bool "Debug credential management" 1396 depends on DEBUG_KERNEL 1397 help 1398 Enable this to turn on some debug checking for credential 1399 management. The additional code keeps track of the number of 1400 pointers from task_structs to any given cred struct, and checks to 1401 see that this number never exceeds the usage count of the cred 1402 struct. 1403 1404 Furthermore, if SELinux is enabled, this also checks that the 1405 security pointer in the cred struct is never seen to be invalid. 1406 1407 If unsure, say N. 1408 1409source "kernel/rcu/Kconfig.debug" 1410 1411config DEBUG_WQ_FORCE_RR_CPU 1412 bool "Force round-robin CPU selection for unbound work items" 1413 depends on DEBUG_KERNEL 1414 default n 1415 help 1416 Workqueue used to implicitly guarantee that work items queued 1417 without explicit CPU specified are put on the local CPU. This 1418 guarantee is no longer true and while local CPU is still 1419 preferred work items may be put on foreign CPUs. Kernel 1420 parameter "workqueue.debug_force_rr_cpu" is added to force 1421 round-robin CPU selection to flush out usages which depend on the 1422 now broken guarantee. This config option enables the debug 1423 feature by default. When enabled, memory and cache locality will 1424 be impacted. 1425 1426config DEBUG_BLOCK_EXT_DEVT 1427 bool "Force extended block device numbers and spread them" 1428 depends on DEBUG_KERNEL 1429 depends on BLOCK 1430 default n 1431 help 1432 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON 1433 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT 1434 YOU ARE DOING. Distros, please enable this and fix whatever 1435 is broken. 1436 1437 Conventionally, block device numbers are allocated from 1438 predetermined contiguous area. However, extended block area 1439 may introduce non-contiguous block device numbers. This 1440 option forces most block device numbers to be allocated from 1441 the extended space and spreads them to discover kernel or 1442 userland code paths which assume predetermined contiguous 1443 device number allocation. 1444 1445 Note that turning on this debug option shuffles all the 1446 device numbers for all IDE and SCSI devices including libata 1447 ones, so root partition specified using device number 1448 directly (via rdev or root=MAJ:MIN) won't work anymore. 1449 Textual device names (root=/dev/sdXn) will continue to work. 1450 1451 Say N if you are unsure. 1452 1453config CPU_HOTPLUG_STATE_CONTROL 1454 bool "Enable CPU hotplug state control" 1455 depends on DEBUG_KERNEL 1456 depends on HOTPLUG_CPU 1457 default n 1458 help 1459 Allows to write steps between "offline" and "online" to the CPUs 1460 sysfs target file so states can be stepped granular. This is a debug 1461 option for now as the hotplug machinery cannot be stopped and 1462 restarted at arbitrary points yet. 1463 1464 Say N if your are unsure. 1465 1466config LATENCYTOP 1467 bool "Latency measuring infrastructure" 1468 depends on DEBUG_KERNEL 1469 depends on STACKTRACE_SUPPORT 1470 depends on PROC_FS 1471 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86 1472 select KALLSYMS 1473 select KALLSYMS_ALL 1474 select STACKTRACE 1475 select SCHEDSTATS 1476 select SCHED_DEBUG 1477 help 1478 Enable this option if you want to use the LatencyTOP tool 1479 to find out which userspace is blocking on what kernel operations. 1480 1481source "kernel/trace/Kconfig" 1482 1483config PROVIDE_OHCI1394_DMA_INIT 1484 bool "Remote debugging over FireWire early on boot" 1485 depends on PCI && X86 1486 help 1487 If you want to debug problems which hang or crash the kernel early 1488 on boot and the crashing machine has a FireWire port, you can use 1489 this feature to remotely access the memory of the crashed machine 1490 over FireWire. This employs remote DMA as part of the OHCI1394 1491 specification which is now the standard for FireWire controllers. 1492 1493 With remote DMA, you can monitor the printk buffer remotely using 1494 firescope and access all memory below 4GB using fireproxy from gdb. 1495 Even controlling a kernel debugger is possible using remote DMA. 1496 1497 Usage: 1498 1499 If ohci1394_dma=early is used as boot parameter, it will initialize 1500 all OHCI1394 controllers which are found in the PCI config space. 1501 1502 As all changes to the FireWire bus such as enabling and disabling 1503 devices cause a bus reset and thereby disable remote DMA for all 1504 devices, be sure to have the cable plugged and FireWire enabled on 1505 the debugging host before booting the debug target for debugging. 1506 1507 This code (~1k) is freed after boot. By then, the firewire stack 1508 in charge of the OHCI-1394 controllers should be used instead. 1509 1510 See Documentation/debugging-via-ohci1394.txt for more information. 1511 1512source "samples/Kconfig" 1513 1514config ARCH_HAS_DEVMEM_IS_ALLOWED 1515 bool 1516 1517config STRICT_DEVMEM 1518 bool "Filter access to /dev/mem" 1519 depends on MMU && DEVMEM 1520 depends on ARCH_HAS_DEVMEM_IS_ALLOWED 1521 default y if PPC || X86 || ARM64 1522 help 1523 If this option is disabled, you allow userspace (root) access to all 1524 of memory, including kernel and userspace memory. Accidental 1525 access to this is obviously disastrous, but specific access can 1526 be used by people debugging the kernel. Note that with PAT support 1527 enabled, even in this case there are restrictions on /dev/mem 1528 use due to the cache aliasing requirements. 1529 1530 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 1531 file only allows userspace access to PCI space and the BIOS code and 1532 data regions. This is sufficient for dosemu and X and all common 1533 users of /dev/mem. 1534 1535 If in doubt, say Y. 1536 1537config IO_STRICT_DEVMEM 1538 bool "Filter I/O access to /dev/mem" 1539 depends on STRICT_DEVMEM 1540 help 1541 If this option is disabled, you allow userspace (root) access to all 1542 io-memory regardless of whether a driver is actively using that 1543 range. Accidental access to this is obviously disastrous, but 1544 specific access can be used by people debugging kernel drivers. 1545 1546 If this option is switched on, the /dev/mem file only allows 1547 userspace access to *idle* io-memory ranges (see /proc/iomem) This 1548 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 1549 if the driver using a given range cannot be disabled. 1550 1551 If in doubt, say Y. 1552 1553menu "$(SRCARCH) Debugging" 1554 1555source "arch/$(SRCARCH)/Kconfig.debug" 1556 1557endmenu 1558 1559menu "Kernel Testing and Coverage" 1560 1561source "lib/kunit/Kconfig" 1562 1563config NOTIFIER_ERROR_INJECTION 1564 tristate "Notifier error injection" 1565 depends on DEBUG_KERNEL 1566 select DEBUG_FS 1567 help 1568 This option provides the ability to inject artificial errors to 1569 specified notifier chain callbacks. It is useful to test the error 1570 handling of notifier call chain failures. 1571 1572 Say N if unsure. 1573 1574config PM_NOTIFIER_ERROR_INJECT 1575 tristate "PM notifier error injection module" 1576 depends on PM && NOTIFIER_ERROR_INJECTION 1577 default m if PM_DEBUG 1578 help 1579 This option provides the ability to inject artificial errors to 1580 PM notifier chain callbacks. It is controlled through debugfs 1581 interface /sys/kernel/debug/notifier-error-inject/pm 1582 1583 If the notifier call chain should be failed with some events 1584 notified, write the error code to "actions/<notifier event>/error". 1585 1586 Example: Inject PM suspend error (-12 = -ENOMEM) 1587 1588 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1589 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1590 # echo mem > /sys/power/state 1591 bash: echo: write error: Cannot allocate memory 1592 1593 To compile this code as a module, choose M here: the module will 1594 be called pm-notifier-error-inject. 1595 1596 If unsure, say N. 1597 1598config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1599 tristate "OF reconfig notifier error injection module" 1600 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1601 help 1602 This option provides the ability to inject artificial errors to 1603 OF reconfig notifier chain callbacks. It is controlled 1604 through debugfs interface under 1605 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1606 1607 If the notifier call chain should be failed with some events 1608 notified, write the error code to "actions/<notifier event>/error". 1609 1610 To compile this code as a module, choose M here: the module will 1611 be called of-reconfig-notifier-error-inject. 1612 1613 If unsure, say N. 1614 1615config NETDEV_NOTIFIER_ERROR_INJECT 1616 tristate "Netdev notifier error injection module" 1617 depends on NET && NOTIFIER_ERROR_INJECTION 1618 help 1619 This option provides the ability to inject artificial errors to 1620 netdevice notifier chain callbacks. It is controlled through debugfs 1621 interface /sys/kernel/debug/notifier-error-inject/netdev 1622 1623 If the notifier call chain should be failed with some events 1624 notified, write the error code to "actions/<notifier event>/error". 1625 1626 Example: Inject netdevice mtu change error (-22 = -EINVAL) 1627 1628 # cd /sys/kernel/debug/notifier-error-inject/netdev 1629 # echo -22 > actions/NETDEV_CHANGEMTU/error 1630 # ip link set eth0 mtu 1024 1631 RTNETLINK answers: Invalid argument 1632 1633 To compile this code as a module, choose M here: the module will 1634 be called netdev-notifier-error-inject. 1635 1636 If unsure, say N. 1637 1638config FUNCTION_ERROR_INJECTION 1639 def_bool y 1640 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 1641 1642config FAULT_INJECTION 1643 bool "Fault-injection framework" 1644 depends on DEBUG_KERNEL 1645 help 1646 Provide fault-injection framework. 1647 For more details, see Documentation/fault-injection/. 1648 1649config FAILSLAB 1650 bool "Fault-injection capability for kmalloc" 1651 depends on FAULT_INJECTION 1652 depends on SLAB || SLUB 1653 help 1654 Provide fault-injection capability for kmalloc. 1655 1656config FAIL_PAGE_ALLOC 1657 bool "Fault-injection capabilitiy for alloc_pages()" 1658 depends on FAULT_INJECTION 1659 help 1660 Provide fault-injection capability for alloc_pages(). 1661 1662config FAIL_MAKE_REQUEST 1663 bool "Fault-injection capability for disk IO" 1664 depends on FAULT_INJECTION && BLOCK 1665 help 1666 Provide fault-injection capability for disk IO. 1667 1668config FAIL_IO_TIMEOUT 1669 bool "Fault-injection capability for faking disk interrupts" 1670 depends on FAULT_INJECTION && BLOCK 1671 help 1672 Provide fault-injection capability on end IO handling. This 1673 will make the block layer "forget" an interrupt as configured, 1674 thus exercising the error handling. 1675 1676 Only works with drivers that use the generic timeout handling, 1677 for others it wont do anything. 1678 1679config FAIL_FUTEX 1680 bool "Fault-injection capability for futexes" 1681 select DEBUG_FS 1682 depends on FAULT_INJECTION && FUTEX 1683 help 1684 Provide fault-injection capability for futexes. 1685 1686config FAULT_INJECTION_DEBUG_FS 1687 bool "Debugfs entries for fault-injection capabilities" 1688 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 1689 help 1690 Enable configuration of fault-injection capabilities via debugfs. 1691 1692config FAIL_FUNCTION 1693 bool "Fault-injection capability for functions" 1694 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 1695 help 1696 Provide function-based fault-injection capability. 1697 This will allow you to override a specific function with a return 1698 with given return value. As a result, function caller will see 1699 an error value and have to handle it. This is useful to test the 1700 error handling in various subsystems. 1701 1702config FAIL_MMC_REQUEST 1703 bool "Fault-injection capability for MMC IO" 1704 depends on FAULT_INJECTION_DEBUG_FS && MMC 1705 help 1706 Provide fault-injection capability for MMC IO. 1707 This will make the mmc core return data errors. This is 1708 useful to test the error handling in the mmc block device 1709 and to test how the mmc host driver handles retries from 1710 the block device. 1711 1712config FAULT_INJECTION_STACKTRACE_FILTER 1713 bool "stacktrace filter for fault-injection capabilities" 1714 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 1715 depends on !X86_64 1716 select STACKTRACE 1717 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86 1718 help 1719 Provide stacktrace filter for fault-injection capabilities 1720 1721config ARCH_HAS_KCOV 1722 bool 1723 help 1724 An architecture should select this when it can successfully 1725 build and run with CONFIG_KCOV. This typically requires 1726 disabling instrumentation for some early boot code. 1727 1728config CC_HAS_SANCOV_TRACE_PC 1729 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 1730 1731 1732config KCOV 1733 bool "Code coverage for fuzzing" 1734 depends on ARCH_HAS_KCOV 1735 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 1736 select DEBUG_FS 1737 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 1738 help 1739 KCOV exposes kernel code coverage information in a form suitable 1740 for coverage-guided fuzzing (randomized testing). 1741 1742 If RANDOMIZE_BASE is enabled, PC values will not be stable across 1743 different machines and across reboots. If you need stable PC values, 1744 disable RANDOMIZE_BASE. 1745 1746 For more details, see Documentation/dev-tools/kcov.rst. 1747 1748config KCOV_ENABLE_COMPARISONS 1749 bool "Enable comparison operands collection by KCOV" 1750 depends on KCOV 1751 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 1752 help 1753 KCOV also exposes operands of every comparison in the instrumented 1754 code along with operand sizes and PCs of the comparison instructions. 1755 These operands can be used by fuzzing engines to improve the quality 1756 of fuzzing coverage. 1757 1758config KCOV_INSTRUMENT_ALL 1759 bool "Instrument all code by default" 1760 depends on KCOV 1761 default y 1762 help 1763 If you are doing generic system call fuzzing (like e.g. syzkaller), 1764 then you will want to instrument the whole kernel and you should 1765 say y here. If you are doing more targeted fuzzing (like e.g. 1766 filesystem fuzzing with AFL) then you will want to enable coverage 1767 for more specific subsets of files, and should say n here. 1768 1769menuconfig RUNTIME_TESTING_MENU 1770 bool "Runtime Testing" 1771 def_bool y 1772 1773if RUNTIME_TESTING_MENU 1774 1775config LKDTM 1776 tristate "Linux Kernel Dump Test Tool Module" 1777 depends on DEBUG_FS 1778 help 1779 This module enables testing of the different dumping mechanisms by 1780 inducing system failures at predefined crash points. 1781 If you don't need it: say N 1782 Choose M here to compile this code as a module. The module will be 1783 called lkdtm. 1784 1785 Documentation on how to use the module can be found in 1786 Documentation/fault-injection/provoke-crashes.rst 1787 1788config TEST_LIST_SORT 1789 tristate "Linked list sorting test" 1790 depends on DEBUG_KERNEL || m 1791 help 1792 Enable this to turn on 'list_sort()' function test. This test is 1793 executed only once during system boot (so affects only boot time), 1794 or at module load time. 1795 1796 If unsure, say N. 1797 1798config TEST_MIN_HEAP 1799 tristate "Min heap test" 1800 depends on DEBUG_KERNEL || m 1801 help 1802 Enable this to turn on min heap function tests. This test is 1803 executed only once during system boot (so affects only boot time), 1804 or at module load time. 1805 1806 If unsure, say N. 1807 1808config TEST_SORT 1809 tristate "Array-based sort test" 1810 depends on DEBUG_KERNEL || m 1811 help 1812 This option enables the self-test function of 'sort()' at boot, 1813 or at module load time. 1814 1815 If unsure, say N. 1816 1817config KPROBES_SANITY_TEST 1818 bool "Kprobes sanity tests" 1819 depends on DEBUG_KERNEL 1820 depends on KPROBES 1821 help 1822 This option provides for testing basic kprobes functionality on 1823 boot. Samples of kprobe and kretprobe are inserted and 1824 verified for functionality. 1825 1826 Say N if you are unsure. 1827 1828config BACKTRACE_SELF_TEST 1829 tristate "Self test for the backtrace code" 1830 depends on DEBUG_KERNEL 1831 help 1832 This option provides a kernel module that can be used to test 1833 the kernel stack backtrace code. This option is not useful 1834 for distributions or general kernels, but only for kernel 1835 developers working on architecture code. 1836 1837 Note that if you want to also test saved backtraces, you will 1838 have to enable STACKTRACE as well. 1839 1840 Say N if you are unsure. 1841 1842config RBTREE_TEST 1843 tristate "Red-Black tree test" 1844 depends on DEBUG_KERNEL 1845 help 1846 A benchmark measuring the performance of the rbtree library. 1847 Also includes rbtree invariant checks. 1848 1849config REED_SOLOMON_TEST 1850 tristate "Reed-Solomon library test" 1851 depends on DEBUG_KERNEL || m 1852 select REED_SOLOMON 1853 select REED_SOLOMON_ENC16 1854 select REED_SOLOMON_DEC16 1855 help 1856 This option enables the self-test function of rslib at boot, 1857 or at module load time. 1858 1859 If unsure, say N. 1860 1861config INTERVAL_TREE_TEST 1862 tristate "Interval tree test" 1863 depends on DEBUG_KERNEL 1864 select INTERVAL_TREE 1865 help 1866 A benchmark measuring the performance of the interval tree library 1867 1868config PERCPU_TEST 1869 tristate "Per cpu operations test" 1870 depends on m && DEBUG_KERNEL 1871 help 1872 Enable this option to build test module which validates per-cpu 1873 operations. 1874 1875 If unsure, say N. 1876 1877config ATOMIC64_SELFTEST 1878 tristate "Perform an atomic64_t self-test" 1879 help 1880 Enable this option to test the atomic64_t functions at boot or 1881 at module load time. 1882 1883 If unsure, say N. 1884 1885config ASYNC_RAID6_TEST 1886 tristate "Self test for hardware accelerated raid6 recovery" 1887 depends on ASYNC_RAID6_RECOV 1888 select ASYNC_MEMCPY 1889 ---help--- 1890 This is a one-shot self test that permutes through the 1891 recovery of all the possible two disk failure scenarios for a 1892 N-disk array. Recovery is performed with the asynchronous 1893 raid6 recovery routines, and will optionally use an offload 1894 engine if one is available. 1895 1896 If unsure, say N. 1897 1898config TEST_HEXDUMP 1899 tristate "Test functions located in the hexdump module at runtime" 1900 1901config TEST_STRING_HELPERS 1902 tristate "Test functions located in the string_helpers module at runtime" 1903 1904config TEST_STRSCPY 1905 tristate "Test strscpy*() family of functions at runtime" 1906 1907config TEST_KSTRTOX 1908 tristate "Test kstrto*() family of functions at runtime" 1909 1910config TEST_PRINTF 1911 tristate "Test printf() family of functions at runtime" 1912 1913config TEST_BITMAP 1914 tristate "Test bitmap_*() family of functions at runtime" 1915 help 1916 Enable this option to test the bitmap functions at boot. 1917 1918 If unsure, say N. 1919 1920config TEST_BITFIELD 1921 tristate "Test bitfield functions at runtime" 1922 help 1923 Enable this option to test the bitfield functions at boot. 1924 1925 If unsure, say N. 1926 1927config TEST_UUID 1928 tristate "Test functions located in the uuid module at runtime" 1929 1930config TEST_XARRAY 1931 tristate "Test the XArray code at runtime" 1932 1933config TEST_OVERFLOW 1934 tristate "Test check_*_overflow() functions at runtime" 1935 1936config TEST_RHASHTABLE 1937 tristate "Perform selftest on resizable hash table" 1938 help 1939 Enable this option to test the rhashtable functions at boot. 1940 1941 If unsure, say N. 1942 1943config TEST_HASH 1944 tristate "Perform selftest on hash functions" 1945 help 1946 Enable this option to test the kernel's integer (<linux/hash.h>), 1947 string (<linux/stringhash.h>), and siphash (<linux/siphash.h>) 1948 hash functions on boot (or module load). 1949 1950 This is intended to help people writing architecture-specific 1951 optimized versions. If unsure, say N. 1952 1953config TEST_IDA 1954 tristate "Perform selftest on IDA functions" 1955 1956config TEST_PARMAN 1957 tristate "Perform selftest on priority array manager" 1958 depends on PARMAN 1959 help 1960 Enable this option to test priority array manager on boot 1961 (or module load). 1962 1963 If unsure, say N. 1964 1965config TEST_IRQ_TIMINGS 1966 bool "IRQ timings selftest" 1967 depends on IRQ_TIMINGS 1968 help 1969 Enable this option to test the irq timings code on boot. 1970 1971 If unsure, say N. 1972 1973config TEST_LKM 1974 tristate "Test module loading with 'hello world' module" 1975 depends on m 1976 help 1977 This builds the "test_module" module that emits "Hello, world" 1978 on printk when loaded. It is designed to be used for basic 1979 evaluation of the module loading subsystem (for example when 1980 validating module verification). It lacks any extra dependencies, 1981 and will not normally be loaded by the system unless explicitly 1982 requested by name. 1983 1984 If unsure, say N. 1985 1986config TEST_VMALLOC 1987 tristate "Test module for stress/performance analysis of vmalloc allocator" 1988 default n 1989 depends on MMU 1990 depends on m 1991 help 1992 This builds the "test_vmalloc" module that should be used for 1993 stress and performance analysis. So, any new change for vmalloc 1994 subsystem can be evaluated from performance and stability point 1995 of view. 1996 1997 If unsure, say N. 1998 1999config TEST_USER_COPY 2000 tristate "Test user/kernel boundary protections" 2001 depends on m 2002 help 2003 This builds the "test_user_copy" module that runs sanity checks 2004 on the copy_to/from_user infrastructure, making sure basic 2005 user/kernel boundary testing is working. If it fails to load, 2006 a regression has been detected in the user/kernel memory boundary 2007 protections. 2008 2009 If unsure, say N. 2010 2011config TEST_BPF 2012 tristate "Test BPF filter functionality" 2013 depends on m && NET 2014 help 2015 This builds the "test_bpf" module that runs various test vectors 2016 against the BPF interpreter or BPF JIT compiler depending on the 2017 current setting. This is in particular useful for BPF JIT compiler 2018 development, but also to run regression tests against changes in 2019 the interpreter code. It also enables test stubs for eBPF maps and 2020 verifier used by user space verifier testsuite. 2021 2022 If unsure, say N. 2023 2024config TEST_BLACKHOLE_DEV 2025 tristate "Test blackhole netdev functionality" 2026 depends on m && NET 2027 help 2028 This builds the "test_blackhole_dev" module that validates the 2029 data path through this blackhole netdev. 2030 2031 If unsure, say N. 2032 2033config FIND_BIT_BENCHMARK 2034 tristate "Test find_bit functions" 2035 help 2036 This builds the "test_find_bit" module that measure find_*_bit() 2037 functions performance. 2038 2039 If unsure, say N. 2040 2041config TEST_FIRMWARE 2042 tristate "Test firmware loading via userspace interface" 2043 depends on FW_LOADER 2044 help 2045 This builds the "test_firmware" module that creates a userspace 2046 interface for testing firmware loading. This can be used to 2047 control the triggering of firmware loading without needing an 2048 actual firmware-using device. The contents can be rechecked by 2049 userspace. 2050 2051 If unsure, say N. 2052 2053config TEST_SYSCTL 2054 tristate "sysctl test driver" 2055 depends on PROC_SYSCTL 2056 help 2057 This builds the "test_sysctl" module. This driver enables to test the 2058 proc sysctl interfaces available to drivers safely without affecting 2059 production knobs which might alter system functionality. 2060 2061 If unsure, say N. 2062 2063config SYSCTL_KUNIT_TEST 2064 tristate "KUnit test for sysctl" 2065 depends on KUNIT 2066 help 2067 This builds the proc sysctl unit test, which runs on boot. 2068 Tests the API contract and implementation correctness of sysctl. 2069 For more information on KUnit and unit tests in general please refer 2070 to the KUnit documentation in Documentation/dev-tools/kunit/. 2071 2072 If unsure, say N. 2073 2074config LIST_KUNIT_TEST 2075 tristate "KUnit Test for Kernel Linked-list structures" 2076 depends on KUNIT 2077 help 2078 This builds the linked list KUnit test suite. 2079 It tests that the API and basic functionality of the list_head type 2080 and associated macros. 2081 2082 KUnit tests run during boot and output the results to the debug log 2083 in TAP format (http://testanything.org/). Only useful for kernel devs 2084 running the KUnit test harness, and not intended for inclusion into a 2085 production build. 2086 2087 For more information on KUnit and unit tests in general please refer 2088 to the KUnit documentation in Documentation/dev-tools/kunit/. 2089 2090 If unsure, say N. 2091 2092config TEST_UDELAY 2093 tristate "udelay test driver" 2094 help 2095 This builds the "udelay_test" module that helps to make sure 2096 that udelay() is working properly. 2097 2098 If unsure, say N. 2099 2100config TEST_STATIC_KEYS 2101 tristate "Test static keys" 2102 depends on m 2103 help 2104 Test the static key interfaces. 2105 2106 If unsure, say N. 2107 2108config TEST_KMOD 2109 tristate "kmod stress tester" 2110 depends on m 2111 depends on NETDEVICES && NET_CORE && INET # for TUN 2112 depends on BLOCK 2113 select TEST_LKM 2114 select XFS_FS 2115 select TUN 2116 select BTRFS_FS 2117 help 2118 Test the kernel's module loading mechanism: kmod. kmod implements 2119 support to load modules using the Linux kernel's usermode helper. 2120 This test provides a series of tests against kmod. 2121 2122 Although technically you can either build test_kmod as a module or 2123 into the kernel we disallow building it into the kernel since 2124 it stress tests request_module() and this will very likely cause 2125 some issues by taking over precious threads available from other 2126 module load requests, ultimately this could be fatal. 2127 2128 To run tests run: 2129 2130 tools/testing/selftests/kmod/kmod.sh --help 2131 2132 If unsure, say N. 2133 2134config TEST_DEBUG_VIRTUAL 2135 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 2136 depends on DEBUG_VIRTUAL 2137 help 2138 Test the kernel's ability to detect incorrect calls to 2139 virt_to_phys() done against the non-linear part of the 2140 kernel's virtual address map. 2141 2142 If unsure, say N. 2143 2144config TEST_MEMCAT_P 2145 tristate "Test memcat_p() helper function" 2146 help 2147 Test the memcat_p() helper for correctly merging two 2148 pointer arrays together. 2149 2150 If unsure, say N. 2151 2152config TEST_LIVEPATCH 2153 tristate "Test livepatching" 2154 default n 2155 depends on DYNAMIC_DEBUG 2156 depends on LIVEPATCH 2157 depends on m 2158 help 2159 Test kernel livepatching features for correctness. The tests will 2160 load test modules that will be livepatched in various scenarios. 2161 2162 To run all the livepatching tests: 2163 2164 make -C tools/testing/selftests TARGETS=livepatch run_tests 2165 2166 Alternatively, individual tests may be invoked: 2167 2168 tools/testing/selftests/livepatch/test-callbacks.sh 2169 tools/testing/selftests/livepatch/test-livepatch.sh 2170 tools/testing/selftests/livepatch/test-shadow-vars.sh 2171 2172 If unsure, say N. 2173 2174config TEST_OBJAGG 2175 tristate "Perform selftest on object aggreration manager" 2176 default n 2177 depends on OBJAGG 2178 help 2179 Enable this option to test object aggregation manager on boot 2180 (or module load). 2181 2182 2183config TEST_STACKINIT 2184 tristate "Test level of stack variable initialization" 2185 help 2186 Test if the kernel is zero-initializing stack variables and 2187 padding. Coverage is controlled by compiler flags, 2188 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2189 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2190 2191 If unsure, say N. 2192 2193config TEST_MEMINIT 2194 tristate "Test heap/page initialization" 2195 help 2196 Test if the kernel is zero-initializing heap and page allocations. 2197 This can be useful to test init_on_alloc and init_on_free features. 2198 2199 If unsure, say N. 2200 2201endif # RUNTIME_TESTING_MENU 2202 2203config MEMTEST 2204 bool "Memtest" 2205 ---help--- 2206 This option adds a kernel parameter 'memtest', which allows memtest 2207 to be set. 2208 memtest=0, mean disabled; -- default 2209 memtest=1, mean do 1 test pattern; 2210 ... 2211 memtest=17, mean do 17 test patterns. 2212 If you are unsure how to answer this question, answer N. 2213 2214 2215 2216config HYPERV_TESTING 2217 bool "Microsoft Hyper-V driver testing" 2218 default n 2219 depends on HYPERV && DEBUG_FS 2220 help 2221 Select this option to enable Hyper-V vmbus testing. 2222 2223endmenu # "Kernel Testing and Coverage" 2224 2225endmenu # Kernel hacking 2226