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 depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED 245 depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST 246 help 247 Generate deduplicated BTF type information from DWARF debug info. 248 Turning this on expects presence of pahole tool, which will convert 249 DWARF type info into equivalent deduplicated BTF type info. 250 251config GDB_SCRIPTS 252 bool "Provide GDB scripts for kernel debugging" 253 depends on DEBUG_INFO 254 help 255 This creates the required links to GDB helper scripts in the 256 build directory. If you load vmlinux into gdb, the helper 257 scripts will be automatically imported by gdb as well, and 258 additional functions are available to analyze a Linux kernel 259 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst 260 for further details. 261 262config ENABLE_MUST_CHECK 263 bool "Enable __must_check logic" 264 default y 265 help 266 Enable the __must_check logic in the kernel build. Disable this to 267 suppress the "warning: ignoring return value of 'foo', declared with 268 attribute warn_unused_result" messages. 269 270config FRAME_WARN 271 int "Warn for stack frames larger than" 272 range 0 8192 273 default 2048 if GCC_PLUGIN_LATENT_ENTROPY 274 default 1280 if (!64BIT && PARISC) 275 default 1024 if (!64BIT && !PARISC) 276 default 2048 if 64BIT 277 help 278 Tell gcc to warn at build time for stack frames larger than this. 279 Setting this too low will cause a lot of warnings. 280 Setting it to 0 disables the warning. 281 282config STRIP_ASM_SYMS 283 bool "Strip assembler-generated symbols during link" 284 default n 285 help 286 Strip internal assembler-generated symbols during a link (symbols 287 that look like '.Lxxx') so they don't pollute the output of 288 get_wchan() and suchlike. 289 290config READABLE_ASM 291 bool "Generate readable assembler code" 292 depends on DEBUG_KERNEL 293 help 294 Disable some compiler optimizations that tend to generate human unreadable 295 assembler output. This may make the kernel slightly slower, but it helps 296 to keep kernel developers who have to stare a lot at assembler listings 297 sane. 298 299config HEADERS_INSTALL 300 bool "Install uapi headers to usr/include" 301 depends on !UML 302 help 303 This option will install uapi headers (headers exported to user-space) 304 into the usr/include directory for use during the kernel build. 305 This is unneeded for building the kernel itself, but needed for some 306 user-space program samples. It is also needed by some features such 307 as uapi header sanity checks. 308 309config OPTIMIZE_INLINING 310 def_bool y 311 help 312 This option determines if the kernel forces gcc to inline the functions 313 developers have marked 'inline'. Doing so takes away freedom from gcc to 314 do what it thinks is best, which is desirable for the gcc 3.x series of 315 compilers. The gcc 4.x series have a rewritten inlining algorithm and 316 enabling this option will generate a smaller kernel there. Hopefully 317 this algorithm is so good that allowing gcc 4.x and above to make the 318 decision will become the default in the future. Until then this option 319 is there to test gcc for this. 320 321config DEBUG_SECTION_MISMATCH 322 bool "Enable full Section mismatch analysis" 323 help 324 The section mismatch analysis checks if there are illegal 325 references from one section to another section. 326 During linktime or runtime, some sections are dropped; 327 any use of code/data previously in these sections would 328 most likely result in an oops. 329 In the code, functions and variables are annotated with 330 __init,, etc. (see the full list in include/linux/init.h), 331 which results in the code/data being placed in specific sections. 332 The section mismatch analysis is always performed after a full 333 kernel build, and enabling this option causes the following 334 additional step to occur: 335 - Add the option -fno-inline-functions-called-once to gcc commands. 336 When inlining a function annotated with __init in a non-init 337 function, we would lose the section information and thus 338 the analysis would not catch the illegal reference. 339 This option tells gcc to inline less (but it does result in 340 a larger kernel). 341 342config SECTION_MISMATCH_WARN_ONLY 343 bool "Make section mismatch errors non-fatal" 344 default y 345 help 346 If you say N here, the build process will fail if there are any 347 section mismatch, instead of just throwing warnings. 348 349 If unsure, say Y. 350 351# 352# Select this config option from the architecture Kconfig, if it 353# is preferred to always offer frame pointers as a config 354# option on the architecture (regardless of KERNEL_DEBUG): 355# 356config ARCH_WANT_FRAME_POINTERS 357 bool 358 359config FRAME_POINTER 360 bool "Compile the kernel with frame pointers" 361 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS 362 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 363 help 364 If you say Y here the resulting kernel image will be slightly 365 larger and slower, but it gives very useful debugging information 366 in case of kernel bugs. (precise oopses/stacktraces/warnings) 367 368config STACK_VALIDATION 369 bool "Compile-time stack metadata validation" 370 depends on HAVE_STACK_VALIDATION 371 default n 372 help 373 Add compile-time checks to validate stack metadata, including frame 374 pointers (if CONFIG_FRAME_POINTER is enabled). This helps ensure 375 that runtime stack traces are more reliable. 376 377 This is also a prerequisite for generation of ORC unwind data, which 378 is needed for CONFIG_UNWINDER_ORC. 379 380 For more information, see 381 tools/objtool/Documentation/stack-validation.txt. 382 383config DEBUG_FORCE_WEAK_PER_CPU 384 bool "Force weak per-cpu definitions" 385 depends on DEBUG_KERNEL 386 help 387 s390 and alpha require percpu variables in modules to be 388 defined weak to work around addressing range issue which 389 puts the following two restrictions on percpu variable 390 definitions. 391 392 1. percpu symbols must be unique whether static or not 393 2. percpu variables can't be defined inside a function 394 395 To ensure that generic code follows the above rules, this 396 option forces all percpu variables to be defined as weak. 397 398endmenu # "Compiler options" 399 400menu "Generic Kernel Debugging Instruments" 401 402config MAGIC_SYSRQ 403 bool "Magic SysRq key" 404 depends on !UML 405 help 406 If you say Y here, you will have some control over the system even 407 if the system crashes for example during kernel debugging (e.g., you 408 will be able to flush the buffer cache to disk, reboot the system 409 immediately or dump some status information). This is accomplished 410 by pressing various keys while holding SysRq (Alt+PrintScreen). It 411 also works on a serial console (on PC hardware at least), if you 412 send a BREAK and then within 5 seconds a command keypress. The 413 keys are documented in <file:Documentation/admin-guide/sysrq.rst>. 414 Don't say Y unless you really know what this hack does. 415 416config MAGIC_SYSRQ_DEFAULT_ENABLE 417 hex "Enable magic SysRq key functions by default" 418 depends on MAGIC_SYSRQ 419 default 0x1 420 help 421 Specifies which SysRq key functions are enabled by default. 422 This may be set to 1 or 0 to enable or disable them all, or 423 to a bitmask as described in Documentation/admin-guide/sysrq.rst. 424 425config MAGIC_SYSRQ_SERIAL 426 bool "Enable magic SysRq key over serial" 427 depends on MAGIC_SYSRQ 428 default y 429 help 430 Many embedded boards have a disconnected TTL level serial which can 431 generate some garbage that can lead to spurious false sysrq detects. 432 This option allows you to decide whether you want to enable the 433 magic SysRq key. 434 435config MAGIC_SYSRQ_SERIAL_SEQUENCE 436 string "Char sequence that enables magic SysRq over serial" 437 depends on MAGIC_SYSRQ_SERIAL 438 default "" 439 help 440 Specifies a sequence of characters that can follow BREAK to enable 441 SysRq on a serial console. 442 443 If unsure, leave an empty string and the option will not be enabled. 444 445config DEBUG_FS 446 bool "Debug Filesystem" 447 help 448 debugfs is a virtual file system that kernel developers use to put 449 debugging files into. Enable this option to be able to read and 450 write to these files. 451 452 For detailed documentation on the debugfs API, see 453 Documentation/filesystems/. 454 455 If unsure, say N. 456 457source "lib/Kconfig.kgdb" 458 459source "lib/Kconfig.ubsan" 460 461endmenu 462 463config DEBUG_KERNEL 464 bool "Kernel debugging" 465 help 466 Say Y here if you are developing drivers or trying to debug and 467 identify kernel problems. 468 469config DEBUG_MISC 470 bool "Miscellaneous debug code" 471 default DEBUG_KERNEL 472 depends on DEBUG_KERNEL 473 help 474 Say Y here if you need to enable miscellaneous debug code that should 475 be under a more specific debug option but isn't. 476 477 478menu "Memory Debugging" 479 480source "mm/Kconfig.debug" 481 482config DEBUG_OBJECTS 483 bool "Debug object operations" 484 depends on DEBUG_KERNEL 485 help 486 If you say Y here, additional code will be inserted into the 487 kernel to track the life time of various objects and validate 488 the operations on those objects. 489 490config DEBUG_OBJECTS_SELFTEST 491 bool "Debug objects selftest" 492 depends on DEBUG_OBJECTS 493 help 494 This enables the selftest of the object debug code. 495 496config DEBUG_OBJECTS_FREE 497 bool "Debug objects in freed memory" 498 depends on DEBUG_OBJECTS 499 help 500 This enables checks whether a k/v free operation frees an area 501 which contains an object which has not been deactivated 502 properly. This can make kmalloc/kfree-intensive workloads 503 much slower. 504 505config DEBUG_OBJECTS_TIMERS 506 bool "Debug timer objects" 507 depends on DEBUG_OBJECTS 508 help 509 If you say Y here, additional code will be inserted into the 510 timer routines to track the life time of timer objects and 511 validate the timer operations. 512 513config DEBUG_OBJECTS_WORK 514 bool "Debug work objects" 515 depends on DEBUG_OBJECTS 516 help 517 If you say Y here, additional code will be inserted into the 518 work queue routines to track the life time of work objects and 519 validate the work operations. 520 521config DEBUG_OBJECTS_RCU_HEAD 522 bool "Debug RCU callbacks objects" 523 depends on DEBUG_OBJECTS 524 help 525 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 526 527config DEBUG_OBJECTS_PERCPU_COUNTER 528 bool "Debug percpu counter objects" 529 depends on DEBUG_OBJECTS 530 help 531 If you say Y here, additional code will be inserted into the 532 percpu counter routines to track the life time of percpu counter 533 objects and validate the percpu counter operations. 534 535config DEBUG_OBJECTS_ENABLE_DEFAULT 536 int "debug_objects bootup default value (0-1)" 537 range 0 1 538 default "1" 539 depends on DEBUG_OBJECTS 540 help 541 Debug objects boot parameter default value 542 543config DEBUG_SLAB 544 bool "Debug slab memory allocations" 545 depends on DEBUG_KERNEL && SLAB 546 help 547 Say Y here to have the kernel do limited verification on memory 548 allocation as well as poisoning memory on free to catch use of freed 549 memory. This can make kmalloc/kfree-intensive workloads much slower. 550 551config SLUB_DEBUG_ON 552 bool "SLUB debugging on by default" 553 depends on SLUB && SLUB_DEBUG 554 default n 555 help 556 Boot with debugging on by default. SLUB boots by default with 557 the runtime debug capabilities switched off. Enabling this is 558 equivalent to specifying the "slub_debug" parameter on boot. 559 There is no support for more fine grained debug control like 560 possible with slub_debug=xxx. SLUB debugging may be switched 561 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying 562 "slub_debug=-". 563 564config SLUB_STATS 565 default n 566 bool "Enable SLUB performance statistics" 567 depends on SLUB && SYSFS 568 help 569 SLUB statistics are useful to debug SLUBs allocation behavior in 570 order find ways to optimize the allocator. This should never be 571 enabled for production use since keeping statistics slows down 572 the allocator by a few percentage points. The slabinfo command 573 supports the determination of the most active slabs to figure 574 out which slabs are relevant to a particular load. 575 Try running: slabinfo -DA 576 577config HAVE_DEBUG_KMEMLEAK 578 bool 579 580config DEBUG_KMEMLEAK 581 bool "Kernel memory leak detector" 582 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK 583 select DEBUG_FS 584 select STACKTRACE if STACKTRACE_SUPPORT 585 select KALLSYMS 586 select CRC32 587 help 588 Say Y here if you want to enable the memory leak 589 detector. The memory allocation/freeing is traced in a way 590 similar to the Boehm's conservative garbage collector, the 591 difference being that the orphan objects are not freed but 592 only shown in /sys/kernel/debug/kmemleak. Enabling this 593 feature will introduce an overhead to memory 594 allocations. See Documentation/dev-tools/kmemleak.rst for more 595 details. 596 597 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances 598 of finding leaks due to the slab objects poisoning. 599 600 In order to access the kmemleak file, debugfs needs to be 601 mounted (usually at /sys/kernel/debug). 602 603config DEBUG_KMEMLEAK_MEM_POOL_SIZE 604 int "Kmemleak memory pool size" 605 depends on DEBUG_KMEMLEAK 606 range 200 1000000 607 default 16000 608 help 609 Kmemleak must track all the memory allocations to avoid 610 reporting false positives. Since memory may be allocated or 611 freed before kmemleak is fully initialised, use a static pool 612 of metadata objects to track such callbacks. After kmemleak is 613 fully initialised, this memory pool acts as an emergency one 614 if slab allocations fail. 615 616config DEBUG_KMEMLEAK_TEST 617 tristate "Simple test for the kernel memory leak detector" 618 depends on DEBUG_KMEMLEAK && m 619 help 620 This option enables a module that explicitly leaks memory. 621 622 If unsure, say N. 623 624config DEBUG_KMEMLEAK_DEFAULT_OFF 625 bool "Default kmemleak to off" 626 depends on DEBUG_KMEMLEAK 627 help 628 Say Y here to disable kmemleak by default. It can then be enabled 629 on the command line via kmemleak=on. 630 631config DEBUG_KMEMLEAK_AUTO_SCAN 632 bool "Enable kmemleak auto scan thread on boot up" 633 default y 634 depends on DEBUG_KMEMLEAK 635 help 636 Depending on the cpu, kmemleak scan may be cpu intensive and can 637 stall user tasks at times. This option enables/disables automatic 638 kmemleak scan at boot up. 639 640 Say N here to disable kmemleak auto scan thread to stop automatic 641 scanning. Disabling this option disables automatic reporting of 642 memory leaks. 643 644 If unsure, say Y. 645 646config DEBUG_STACK_USAGE 647 bool "Stack utilization instrumentation" 648 depends on DEBUG_KERNEL && !IA64 649 help 650 Enables the display of the minimum amount of free stack which each 651 task has ever had available in the sysrq-T and sysrq-P debug output. 652 653 This option will slow down process creation somewhat. 654 655config SCHED_STACK_END_CHECK 656 bool "Detect stack corruption on calls to schedule()" 657 depends on DEBUG_KERNEL 658 default n 659 help 660 This option checks for a stack overrun on calls to schedule(). 661 If the stack end location is found to be over written always panic as 662 the content of the corrupted region can no longer be trusted. 663 This is to ensure no erroneous behaviour occurs which could result in 664 data corruption or a sporadic crash at a later stage once the region 665 is examined. The runtime overhead introduced is minimal. 666 667config DEBUG_VM 668 bool "Debug VM" 669 depends on DEBUG_KERNEL 670 help 671 Enable this to turn on extended checks in the virtual-memory system 672 that may impact performance. 673 674 If unsure, say N. 675 676config DEBUG_VM_VMACACHE 677 bool "Debug VMA caching" 678 depends on DEBUG_VM 679 help 680 Enable this to turn on VMA caching debug information. Doing so 681 can cause significant overhead, so only enable it in non-production 682 environments. 683 684 If unsure, say N. 685 686config DEBUG_VM_RB 687 bool "Debug VM red-black trees" 688 depends on DEBUG_VM 689 help 690 Enable VM red-black tree debugging information and extra validations. 691 692 If unsure, say N. 693 694config DEBUG_VM_PGFLAGS 695 bool "Debug page-flags operations" 696 depends on DEBUG_VM 697 help 698 Enables extra validation on page flags operations. 699 700 If unsure, say N. 701 702config ARCH_HAS_DEBUG_VIRTUAL 703 bool 704 705config DEBUG_VIRTUAL 706 bool "Debug VM translations" 707 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL 708 help 709 Enable some costly sanity checks in virtual to page code. This can 710 catch mistakes with virt_to_page() and friends. 711 712 If unsure, say N. 713 714config DEBUG_NOMMU_REGIONS 715 bool "Debug the global anon/private NOMMU mapping region tree" 716 depends on DEBUG_KERNEL && !MMU 717 help 718 This option causes the global tree of anonymous and private mapping 719 regions to be regularly checked for invalid topology. 720 721config DEBUG_MEMORY_INIT 722 bool "Debug memory initialisation" if EXPERT 723 default !EXPERT 724 help 725 Enable this for additional checks during memory initialisation. 726 The sanity checks verify aspects of the VM such as the memory model 727 and other information provided by the architecture. Verbose 728 information will be printed at KERN_DEBUG loglevel depending 729 on the mminit_loglevel= command-line option. 730 731 If unsure, say Y 732 733config MEMORY_NOTIFIER_ERROR_INJECT 734 tristate "Memory hotplug notifier error injection module" 735 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION 736 help 737 This option provides the ability to inject artificial errors to 738 memory hotplug notifier chain callbacks. It is controlled through 739 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 740 741 If the notifier call chain should be failed with some events 742 notified, write the error code to "actions/<notifier event>/error". 743 744 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 745 746 # cd /sys/kernel/debug/notifier-error-inject/memory 747 # echo -12 > actions/MEM_GOING_OFFLINE/error 748 # echo offline > /sys/devices/system/memory/memoryXXX/state 749 bash: echo: write error: Cannot allocate memory 750 751 To compile this code as a module, choose M here: the module will 752 be called memory-notifier-error-inject. 753 754 If unsure, say N. 755 756config DEBUG_PER_CPU_MAPS 757 bool "Debug access to per_cpu maps" 758 depends on DEBUG_KERNEL 759 depends on SMP 760 help 761 Say Y to verify that the per_cpu map being accessed has 762 been set up. This adds a fair amount of code to kernel memory 763 and decreases performance. 764 765 Say N if unsure. 766 767config DEBUG_HIGHMEM 768 bool "Highmem debugging" 769 depends on DEBUG_KERNEL && HIGHMEM 770 help 771 This option enables additional error checking for high memory 772 systems. Disable for production systems. 773 774config HAVE_DEBUG_STACKOVERFLOW 775 bool 776 777config DEBUG_STACKOVERFLOW 778 bool "Check for stack overflows" 779 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 780 ---help--- 781 Say Y here if you want to check for overflows of kernel, IRQ 782 and exception stacks (if your architecture uses them). This 783 option will show detailed messages if free stack space drops 784 below a certain limit. 785 786 These kinds of bugs usually occur when call-chains in the 787 kernel get too deep, especially when interrupts are 788 involved. 789 790 Use this in cases where you see apparently random memory 791 corruption, especially if it appears in 'struct thread_info' 792 793 If in doubt, say "N". 794 795source "lib/Kconfig.kasan" 796 797endmenu # "Memory Debugging" 798 799config DEBUG_SHIRQ 800 bool "Debug shared IRQ handlers" 801 depends on DEBUG_KERNEL 802 help 803 Enable this to generate a spurious interrupt as soon as a shared 804 interrupt handler is registered, and just before one is deregistered. 805 Drivers ought to be able to handle interrupts coming in at those 806 points; some don't and need to be caught. 807 808menu "Debug Oops, Lockups and Hangs" 809 810config PANIC_ON_OOPS 811 bool "Panic on Oops" 812 help 813 Say Y here to enable the kernel to panic when it oopses. This 814 has the same effect as setting oops=panic on the kernel command 815 line. 816 817 This feature is useful to ensure that the kernel does not do 818 anything erroneous after an oops which could result in data 819 corruption or other issues. 820 821 Say N if unsure. 822 823config PANIC_ON_OOPS_VALUE 824 int 825 range 0 1 826 default 0 if !PANIC_ON_OOPS 827 default 1 if PANIC_ON_OOPS 828 829config PANIC_TIMEOUT 830 int "panic timeout" 831 default 0 832 help 833 Set the timeout value (in seconds) until a reboot occurs when the 834 the kernel panics. If n = 0, then we wait forever. A timeout 835 value n > 0 will wait n seconds before rebooting, while a timeout 836 value n < 0 will reboot immediately. 837 838config LOCKUP_DETECTOR 839 bool 840 841config SOFTLOCKUP_DETECTOR 842 bool "Detect Soft Lockups" 843 depends on DEBUG_KERNEL && !S390 844 select LOCKUP_DETECTOR 845 help 846 Say Y here to enable the kernel to act as a watchdog to detect 847 soft lockups. 848 849 Softlockups are bugs that cause the kernel to loop in kernel 850 mode for more than 20 seconds, without giving other tasks a 851 chance to run. The current stack trace is displayed upon 852 detection and the system will stay locked up. 853 854config BOOTPARAM_SOFTLOCKUP_PANIC 855 bool "Panic (Reboot) On Soft Lockups" 856 depends on SOFTLOCKUP_DETECTOR 857 help 858 Say Y here to enable the kernel to panic on "soft lockups", 859 which are bugs that cause the kernel to loop in kernel 860 mode for more than 20 seconds (configurable using the watchdog_thresh 861 sysctl), without giving other tasks a chance to run. 862 863 The panic can be used in combination with panic_timeout, 864 to cause the system to reboot automatically after a 865 lockup has been detected. This feature is useful for 866 high-availability systems that have uptime guarantees and 867 where a lockup must be resolved ASAP. 868 869 Say N if unsure. 870 871config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE 872 int 873 depends on SOFTLOCKUP_DETECTOR 874 range 0 1 875 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC 876 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC 877 878config HARDLOCKUP_DETECTOR_PERF 879 bool 880 select SOFTLOCKUP_DETECTOR 881 882# 883# Enables a timestamp based low pass filter to compensate for perf based 884# hard lockup detection which runs too fast due to turbo modes. 885# 886config HARDLOCKUP_CHECK_TIMESTAMP 887 bool 888 889# 890# arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard 891# lockup detector rather than the perf based detector. 892# 893config HARDLOCKUP_DETECTOR 894 bool "Detect Hard Lockups" 895 depends on DEBUG_KERNEL && !S390 896 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH 897 select LOCKUP_DETECTOR 898 select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF 899 select HARDLOCKUP_DETECTOR_ARCH if HAVE_HARDLOCKUP_DETECTOR_ARCH 900 help 901 Say Y here to enable the kernel to act as a watchdog to detect 902 hard lockups. 903 904 Hardlockups are bugs that cause the CPU to loop in kernel mode 905 for more than 10 seconds, without letting other interrupts have a 906 chance to run. The current stack trace is displayed upon detection 907 and the system will stay locked up. 908 909config BOOTPARAM_HARDLOCKUP_PANIC 910 bool "Panic (Reboot) On Hard Lockups" 911 depends on HARDLOCKUP_DETECTOR 912 help 913 Say Y here to enable the kernel to panic on "hard lockups", 914 which are bugs that cause the kernel to loop in kernel 915 mode with interrupts disabled for more than 10 seconds (configurable 916 using the watchdog_thresh sysctl). 917 918 Say N if unsure. 919 920config BOOTPARAM_HARDLOCKUP_PANIC_VALUE 921 int 922 depends on HARDLOCKUP_DETECTOR 923 range 0 1 924 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC 925 default 1 if BOOTPARAM_HARDLOCKUP_PANIC 926 927config DETECT_HUNG_TASK 928 bool "Detect Hung Tasks" 929 depends on DEBUG_KERNEL 930 default SOFTLOCKUP_DETECTOR 931 help 932 Say Y here to enable the kernel to detect "hung tasks", 933 which are bugs that cause the task to be stuck in 934 uninterruptible "D" state indefinitely. 935 936 When a hung task is detected, the kernel will print the 937 current stack trace (which you should report), but the 938 task will stay in uninterruptible state. If lockdep is 939 enabled then all held locks will also be reported. This 940 feature has negligible overhead. 941 942config DEFAULT_HUNG_TASK_TIMEOUT 943 int "Default timeout for hung task detection (in seconds)" 944 depends on DETECT_HUNG_TASK 945 default 120 946 help 947 This option controls the default timeout (in seconds) used 948 to determine when a task has become non-responsive and should 949 be considered hung. 950 951 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 952 sysctl or by writing a value to 953 /proc/sys/kernel/hung_task_timeout_secs. 954 955 A timeout of 0 disables the check. The default is two minutes. 956 Keeping the default should be fine in most cases. 957 958config BOOTPARAM_HUNG_TASK_PANIC 959 bool "Panic (Reboot) On Hung Tasks" 960 depends on DETECT_HUNG_TASK 961 help 962 Say Y here to enable the kernel to panic on "hung tasks", 963 which are bugs that cause the kernel to leave a task stuck 964 in uninterruptible "D" state. 965 966 The panic can be used in combination with panic_timeout, 967 to cause the system to reboot automatically after a 968 hung task has been detected. This feature is useful for 969 high-availability systems that have uptime guarantees and 970 where a hung tasks must be resolved ASAP. 971 972 Say N if unsure. 973 974config BOOTPARAM_HUNG_TASK_PANIC_VALUE 975 int 976 depends on DETECT_HUNG_TASK 977 range 0 1 978 default 0 if !BOOTPARAM_HUNG_TASK_PANIC 979 default 1 if BOOTPARAM_HUNG_TASK_PANIC 980 981config WQ_WATCHDOG 982 bool "Detect Workqueue Stalls" 983 depends on DEBUG_KERNEL 984 help 985 Say Y here to enable stall detection on workqueues. If a 986 worker pool doesn't make forward progress on a pending work 987 item for over a given amount of time, 30s by default, a 988 warning message is printed along with dump of workqueue 989 state. This can be configured through kernel parameter 990 "workqueue.watchdog_thresh" and its sysfs counterpart. 991 992endmenu # "Debug lockups and hangs" 993 994menu "Scheduler Debugging" 995 996config SCHED_DEBUG 997 bool "Collect scheduler debugging info" 998 depends on DEBUG_KERNEL && PROC_FS 999 default y 1000 help 1001 If you say Y here, the /proc/sched_debug file will be provided 1002 that can help debug the scheduler. The runtime overhead of this 1003 option is minimal. 1004 1005config SCHED_INFO 1006 bool 1007 default n 1008 1009config SCHEDSTATS 1010 bool "Collect scheduler statistics" 1011 depends on DEBUG_KERNEL && PROC_FS 1012 select SCHED_INFO 1013 help 1014 If you say Y here, additional code will be inserted into the 1015 scheduler and related routines to collect statistics about 1016 scheduler behavior and provide them in /proc/schedstat. These 1017 stats may be useful for both tuning and debugging the scheduler 1018 If you aren't debugging the scheduler or trying to tune a specific 1019 application, you can say N to avoid the very slight overhead 1020 this adds. 1021 1022endmenu 1023 1024config DEBUG_TIMEKEEPING 1025 bool "Enable extra timekeeping sanity checking" 1026 help 1027 This option will enable additional timekeeping sanity checks 1028 which may be helpful when diagnosing issues where timekeeping 1029 problems are suspected. 1030 1031 This may include checks in the timekeeping hotpaths, so this 1032 option may have a (very small) performance impact to some 1033 workloads. 1034 1035 If unsure, say N. 1036 1037config DEBUG_PREEMPT 1038 bool "Debug preemptible kernel" 1039 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1040 default y 1041 help 1042 If you say Y here then the kernel will use a debug variant of the 1043 commonly used smp_processor_id() function and will print warnings 1044 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1045 will detect preemption count underflows. 1046 1047menu "Lock Debugging (spinlocks, mutexes, etc...)" 1048 1049config LOCK_DEBUGGING_SUPPORT 1050 bool 1051 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1052 default y 1053 1054config PROVE_LOCKING 1055 bool "Lock debugging: prove locking correctness" 1056 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1057 select LOCKDEP 1058 select DEBUG_SPINLOCK 1059 select DEBUG_MUTEXES 1060 select DEBUG_RT_MUTEXES if RT_MUTEXES 1061 select DEBUG_RWSEMS 1062 select DEBUG_WW_MUTEX_SLOWPATH 1063 select DEBUG_LOCK_ALLOC 1064 select TRACE_IRQFLAGS 1065 default n 1066 help 1067 This feature enables the kernel to prove that all locking 1068 that occurs in the kernel runtime is mathematically 1069 correct: that under no circumstance could an arbitrary (and 1070 not yet triggered) combination of observed locking 1071 sequences (on an arbitrary number of CPUs, running an 1072 arbitrary number of tasks and interrupt contexts) cause a 1073 deadlock. 1074 1075 In short, this feature enables the kernel to report locking 1076 related deadlocks before they actually occur. 1077 1078 The proof does not depend on how hard and complex a 1079 deadlock scenario would be to trigger: how many 1080 participant CPUs, tasks and irq-contexts would be needed 1081 for it to trigger. The proof also does not depend on 1082 timing: if a race and a resulting deadlock is possible 1083 theoretically (no matter how unlikely the race scenario 1084 is), it will be proven so and will immediately be 1085 reported by the kernel (once the event is observed that 1086 makes the deadlock theoretically possible). 1087 1088 If a deadlock is impossible (i.e. the locking rules, as 1089 observed by the kernel, are mathematically correct), the 1090 kernel reports nothing. 1091 1092 NOTE: this feature can also be enabled for rwlocks, mutexes 1093 and rwsems - in which case all dependencies between these 1094 different locking variants are observed and mapped too, and 1095 the proof of observed correctness is also maintained for an 1096 arbitrary combination of these separate locking variants. 1097 1098 For more details, see Documentation/locking/lockdep-design.rst. 1099 1100config PROVE_RAW_LOCK_NESTING 1101 bool "Enable raw_spinlock - spinlock nesting checks" 1102 depends on PROVE_LOCKING 1103 default n 1104 help 1105 Enable the raw_spinlock vs. spinlock nesting checks which ensure 1106 that the lock nesting rules for PREEMPT_RT enabled kernels are 1107 not violated. 1108 1109 NOTE: There are known nesting problems. So if you enable this 1110 option expect lockdep splats until these problems have been fully 1111 addressed which is work in progress. This config switch allows to 1112 identify and analyze these problems. It will be removed and the 1113 check permanentely enabled once the main issues have been fixed. 1114 1115 If unsure, select N. 1116 1117config LOCK_STAT 1118 bool "Lock usage statistics" 1119 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1120 select LOCKDEP 1121 select DEBUG_SPINLOCK 1122 select DEBUG_MUTEXES 1123 select DEBUG_RT_MUTEXES if RT_MUTEXES 1124 select DEBUG_LOCK_ALLOC 1125 default n 1126 help 1127 This feature enables tracking lock contention points 1128 1129 For more details, see Documentation/locking/lockstat.rst 1130 1131 This also enables lock events required by "perf lock", 1132 subcommand of perf. 1133 If you want to use "perf lock", you also need to turn on 1134 CONFIG_EVENT_TRACING. 1135 1136 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1137 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1138 1139config DEBUG_RT_MUTEXES 1140 bool "RT Mutex debugging, deadlock detection" 1141 depends on DEBUG_KERNEL && RT_MUTEXES 1142 help 1143 This allows rt mutex semantics violations and rt mutex related 1144 deadlocks (lockups) to be detected and reported automatically. 1145 1146config DEBUG_SPINLOCK 1147 bool "Spinlock and rw-lock debugging: basic checks" 1148 depends on DEBUG_KERNEL 1149 select UNINLINE_SPIN_UNLOCK 1150 help 1151 Say Y here and build SMP to catch missing spinlock initialization 1152 and certain other kinds of spinlock errors commonly made. This is 1153 best used in conjunction with the NMI watchdog so that spinlock 1154 deadlocks are also debuggable. 1155 1156config DEBUG_MUTEXES 1157 bool "Mutex debugging: basic checks" 1158 depends on DEBUG_KERNEL 1159 help 1160 This feature allows mutex semantics violations to be detected and 1161 reported. 1162 1163config DEBUG_WW_MUTEX_SLOWPATH 1164 bool "Wait/wound mutex debugging: Slowpath testing" 1165 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1166 select DEBUG_LOCK_ALLOC 1167 select DEBUG_SPINLOCK 1168 select DEBUG_MUTEXES 1169 help 1170 This feature enables slowpath testing for w/w mutex users by 1171 injecting additional -EDEADLK wound/backoff cases. Together with 1172 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1173 will test all possible w/w mutex interface abuse with the 1174 exception of simply not acquiring all the required locks. 1175 Note that this feature can introduce significant overhead, so 1176 it really should not be enabled in a production or distro kernel, 1177 even a debug kernel. If you are a driver writer, enable it. If 1178 you are a distro, do not. 1179 1180config DEBUG_RWSEMS 1181 bool "RW Semaphore debugging: basic checks" 1182 depends on DEBUG_KERNEL 1183 help 1184 This debugging feature allows mismatched rw semaphore locks 1185 and unlocks to be detected and reported. 1186 1187config DEBUG_LOCK_ALLOC 1188 bool "Lock debugging: detect incorrect freeing of live locks" 1189 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1190 select DEBUG_SPINLOCK 1191 select DEBUG_MUTEXES 1192 select DEBUG_RT_MUTEXES if RT_MUTEXES 1193 select LOCKDEP 1194 help 1195 This feature will check whether any held lock (spinlock, rwlock, 1196 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1197 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1198 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1199 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1200 held during task exit. 1201 1202config LOCKDEP 1203 bool 1204 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1205 select STACKTRACE 1206 select FRAME_POINTER if !MIPS && !PPC && !ARM && !S390 && !MICROBLAZE && !ARC && !X86 1207 select KALLSYMS 1208 select KALLSYMS_ALL 1209 1210config LOCKDEP_SMALL 1211 bool 1212 1213config DEBUG_LOCKDEP 1214 bool "Lock dependency engine debugging" 1215 depends on DEBUG_KERNEL && LOCKDEP 1216 help 1217 If you say Y here, the lock dependency engine will do 1218 additional runtime checks to debug itself, at the price 1219 of more runtime overhead. 1220 1221config DEBUG_ATOMIC_SLEEP 1222 bool "Sleep inside atomic section checking" 1223 select PREEMPT_COUNT 1224 depends on DEBUG_KERNEL 1225 depends on !ARCH_NO_PREEMPT 1226 help 1227 If you say Y here, various routines which may sleep will become very 1228 noisy if they are called inside atomic sections: when a spinlock is 1229 held, inside an rcu read side critical section, inside preempt disabled 1230 sections, inside an interrupt, etc... 1231 1232config DEBUG_LOCKING_API_SELFTESTS 1233 bool "Locking API boot-time self-tests" 1234 depends on DEBUG_KERNEL 1235 help 1236 Say Y here if you want the kernel to run a short self-test during 1237 bootup. The self-test checks whether common types of locking bugs 1238 are detected by debugging mechanisms or not. (if you disable 1239 lock debugging then those bugs wont be detected of course.) 1240 The following locking APIs are covered: spinlocks, rwlocks, 1241 mutexes and rwsems. 1242 1243config LOCK_TORTURE_TEST 1244 tristate "torture tests for locking" 1245 depends on DEBUG_KERNEL 1246 select TORTURE_TEST 1247 help 1248 This option provides a kernel module that runs torture tests 1249 on kernel locking primitives. The kernel module may be built 1250 after the fact on the running kernel to be tested, if desired. 1251 1252 Say Y here if you want kernel locking-primitive torture tests 1253 to be built into the kernel. 1254 Say M if you want these torture tests to build as a module. 1255 Say N if you are unsure. 1256 1257config WW_MUTEX_SELFTEST 1258 tristate "Wait/wound mutex selftests" 1259 help 1260 This option provides a kernel module that runs tests on the 1261 on the struct ww_mutex locking API. 1262 1263 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1264 with this test harness. 1265 1266 Say M if you want these self tests to build as a module. 1267 Say N if you are unsure. 1268 1269endmenu # lock debugging 1270 1271config TRACE_IRQFLAGS 1272 bool 1273 help 1274 Enables hooks to interrupt enabling and disabling for 1275 either tracing or lock debugging. 1276 1277config STACKTRACE 1278 bool "Stack backtrace support" 1279 depends on STACKTRACE_SUPPORT 1280 help 1281 This option causes the kernel to create a /proc/pid/stack for 1282 every process, showing its current stack trace. 1283 It is also used by various kernel debugging features that require 1284 stack trace generation. 1285 1286config WARN_ALL_UNSEEDED_RANDOM 1287 bool "Warn for all uses of unseeded randomness" 1288 default n 1289 help 1290 Some parts of the kernel contain bugs relating to their use of 1291 cryptographically secure random numbers before it's actually possible 1292 to generate those numbers securely. This setting ensures that these 1293 flaws don't go unnoticed, by enabling a message, should this ever 1294 occur. This will allow people with obscure setups to know when things 1295 are going wrong, so that they might contact developers about fixing 1296 it. 1297 1298 Unfortunately, on some models of some architectures getting 1299 a fully seeded CRNG is extremely difficult, and so this can 1300 result in dmesg getting spammed for a surprisingly long 1301 time. This is really bad from a security perspective, and 1302 so architecture maintainers really need to do what they can 1303 to get the CRNG seeded sooner after the system is booted. 1304 However, since users cannot do anything actionable to 1305 address this, by default the kernel will issue only a single 1306 warning for the first use of unseeded randomness. 1307 1308 Say Y here if you want to receive warnings for all uses of 1309 unseeded randomness. This will be of use primarily for 1310 those developers interested in improving the security of 1311 Linux kernels running on their architecture (or 1312 subarchitecture). 1313 1314config DEBUG_KOBJECT 1315 bool "kobject debugging" 1316 depends on DEBUG_KERNEL 1317 help 1318 If you say Y here, some extra kobject debugging messages will be sent 1319 to the syslog. 1320 1321config DEBUG_KOBJECT_RELEASE 1322 bool "kobject release debugging" 1323 depends on DEBUG_OBJECTS_TIMERS 1324 help 1325 kobjects are reference counted objects. This means that their 1326 last reference count put is not predictable, and the kobject can 1327 live on past the point at which a driver decides to drop it's 1328 initial reference to the kobject gained on allocation. An 1329 example of this would be a struct device which has just been 1330 unregistered. 1331 1332 However, some buggy drivers assume that after such an operation, 1333 the memory backing the kobject can be immediately freed. This 1334 goes completely against the principles of a refcounted object. 1335 1336 If you say Y here, the kernel will delay the release of kobjects 1337 on the last reference count to improve the visibility of this 1338 kind of kobject release bug. 1339 1340config HAVE_DEBUG_BUGVERBOSE 1341 bool 1342 1343menu "Debug kernel data structures" 1344 1345config DEBUG_LIST 1346 bool "Debug linked list manipulation" 1347 depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION 1348 help 1349 Enable this to turn on extended checks in the linked-list 1350 walking routines. 1351 1352 If unsure, say N. 1353 1354config DEBUG_PLIST 1355 bool "Debug priority linked list manipulation" 1356 depends on DEBUG_KERNEL 1357 help 1358 Enable this to turn on extended checks in the priority-ordered 1359 linked-list (plist) walking routines. This checks the entire 1360 list multiple times during each manipulation. 1361 1362 If unsure, say N. 1363 1364config DEBUG_SG 1365 bool "Debug SG table operations" 1366 depends on DEBUG_KERNEL 1367 help 1368 Enable this to turn on checks on scatter-gather tables. This can 1369 help find problems with drivers that do not properly initialize 1370 their sg tables. 1371 1372 If unsure, say N. 1373 1374config DEBUG_NOTIFIERS 1375 bool "Debug notifier call chains" 1376 depends on DEBUG_KERNEL 1377 help 1378 Enable this to turn on sanity checking for notifier call chains. 1379 This is most useful for kernel developers to make sure that 1380 modules properly unregister themselves from notifier chains. 1381 This is a relatively cheap check but if you care about maximum 1382 performance, say N. 1383 1384config BUG_ON_DATA_CORRUPTION 1385 bool "Trigger a BUG when data corruption is detected" 1386 select DEBUG_LIST 1387 help 1388 Select this option if the kernel should BUG when it encounters 1389 data corruption in kernel memory structures when they get checked 1390 for validity. 1391 1392 If unsure, say N. 1393 1394endmenu 1395 1396config DEBUG_CREDENTIALS 1397 bool "Debug credential management" 1398 depends on DEBUG_KERNEL 1399 help 1400 Enable this to turn on some debug checking for credential 1401 management. The additional code keeps track of the number of 1402 pointers from task_structs to any given cred struct, and checks to 1403 see that this number never exceeds the usage count of the cred 1404 struct. 1405 1406 Furthermore, if SELinux is enabled, this also checks that the 1407 security pointer in the cred struct is never seen to be invalid. 1408 1409 If unsure, say N. 1410 1411source "kernel/rcu/Kconfig.debug" 1412 1413config DEBUG_WQ_FORCE_RR_CPU 1414 bool "Force round-robin CPU selection for unbound work items" 1415 depends on DEBUG_KERNEL 1416 default n 1417 help 1418 Workqueue used to implicitly guarantee that work items queued 1419 without explicit CPU specified are put on the local CPU. This 1420 guarantee is no longer true and while local CPU is still 1421 preferred work items may be put on foreign CPUs. Kernel 1422 parameter "workqueue.debug_force_rr_cpu" is added to force 1423 round-robin CPU selection to flush out usages which depend on the 1424 now broken guarantee. This config option enables the debug 1425 feature by default. When enabled, memory and cache locality will 1426 be impacted. 1427 1428config DEBUG_BLOCK_EXT_DEVT 1429 bool "Force extended block device numbers and spread them" 1430 depends on DEBUG_KERNEL 1431 depends on BLOCK 1432 default n 1433 help 1434 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON 1435 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT 1436 YOU ARE DOING. Distros, please enable this and fix whatever 1437 is broken. 1438 1439 Conventionally, block device numbers are allocated from 1440 predetermined contiguous area. However, extended block area 1441 may introduce non-contiguous block device numbers. This 1442 option forces most block device numbers to be allocated from 1443 the extended space and spreads them to discover kernel or 1444 userland code paths which assume predetermined contiguous 1445 device number allocation. 1446 1447 Note that turning on this debug option shuffles all the 1448 device numbers for all IDE and SCSI devices including libata 1449 ones, so root partition specified using device number 1450 directly (via rdev or root=MAJ:MIN) won't work anymore. 1451 Textual device names (root=/dev/sdXn) will continue to work. 1452 1453 Say N if you are unsure. 1454 1455config CPU_HOTPLUG_STATE_CONTROL 1456 bool "Enable CPU hotplug state control" 1457 depends on DEBUG_KERNEL 1458 depends on HOTPLUG_CPU 1459 default n 1460 help 1461 Allows to write steps between "offline" and "online" to the CPUs 1462 sysfs target file so states can be stepped granular. This is a debug 1463 option for now as the hotplug machinery cannot be stopped and 1464 restarted at arbitrary points yet. 1465 1466 Say N if your are unsure. 1467 1468config LATENCYTOP 1469 bool "Latency measuring infrastructure" 1470 depends on DEBUG_KERNEL 1471 depends on STACKTRACE_SUPPORT 1472 depends on PROC_FS 1473 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86 1474 select KALLSYMS 1475 select KALLSYMS_ALL 1476 select STACKTRACE 1477 select SCHEDSTATS 1478 select SCHED_DEBUG 1479 help 1480 Enable this option if you want to use the LatencyTOP tool 1481 to find out which userspace is blocking on what kernel operations. 1482 1483source "kernel/trace/Kconfig" 1484 1485config PROVIDE_OHCI1394_DMA_INIT 1486 bool "Remote debugging over FireWire early on boot" 1487 depends on PCI && X86 1488 help 1489 If you want to debug problems which hang or crash the kernel early 1490 on boot and the crashing machine has a FireWire port, you can use 1491 this feature to remotely access the memory of the crashed machine 1492 over FireWire. This employs remote DMA as part of the OHCI1394 1493 specification which is now the standard for FireWire controllers. 1494 1495 With remote DMA, you can monitor the printk buffer remotely using 1496 firescope and access all memory below 4GB using fireproxy from gdb. 1497 Even controlling a kernel debugger is possible using remote DMA. 1498 1499 Usage: 1500 1501 If ohci1394_dma=early is used as boot parameter, it will initialize 1502 all OHCI1394 controllers which are found in the PCI config space. 1503 1504 As all changes to the FireWire bus such as enabling and disabling 1505 devices cause a bus reset and thereby disable remote DMA for all 1506 devices, be sure to have the cable plugged and FireWire enabled on 1507 the debugging host before booting the debug target for debugging. 1508 1509 This code (~1k) is freed after boot. By then, the firewire stack 1510 in charge of the OHCI-1394 controllers should be used instead. 1511 1512 See Documentation/debugging-via-ohci1394.txt for more information. 1513 1514source "samples/Kconfig" 1515 1516config ARCH_HAS_DEVMEM_IS_ALLOWED 1517 bool 1518 1519config STRICT_DEVMEM 1520 bool "Filter access to /dev/mem" 1521 depends on MMU && DEVMEM 1522 depends on ARCH_HAS_DEVMEM_IS_ALLOWED 1523 default y if PPC || X86 || ARM64 1524 help 1525 If this option is disabled, you allow userspace (root) access to all 1526 of memory, including kernel and userspace memory. Accidental 1527 access to this is obviously disastrous, but specific access can 1528 be used by people debugging the kernel. Note that with PAT support 1529 enabled, even in this case there are restrictions on /dev/mem 1530 use due to the cache aliasing requirements. 1531 1532 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 1533 file only allows userspace access to PCI space and the BIOS code and 1534 data regions. This is sufficient for dosemu and X and all common 1535 users of /dev/mem. 1536 1537 If in doubt, say Y. 1538 1539config IO_STRICT_DEVMEM 1540 bool "Filter I/O access to /dev/mem" 1541 depends on STRICT_DEVMEM 1542 help 1543 If this option is disabled, you allow userspace (root) access to all 1544 io-memory regardless of whether a driver is actively using that 1545 range. Accidental access to this is obviously disastrous, but 1546 specific access can be used by people debugging kernel drivers. 1547 1548 If this option is switched on, the /dev/mem file only allows 1549 userspace access to *idle* io-memory ranges (see /proc/iomem) This 1550 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 1551 if the driver using a given range cannot be disabled. 1552 1553 If in doubt, say Y. 1554 1555menu "$(SRCARCH) Debugging" 1556 1557source "arch/$(SRCARCH)/Kconfig.debug" 1558 1559endmenu 1560 1561menu "Kernel Testing and Coverage" 1562 1563source "lib/kunit/Kconfig" 1564 1565config NOTIFIER_ERROR_INJECTION 1566 tristate "Notifier error injection" 1567 depends on DEBUG_KERNEL 1568 select DEBUG_FS 1569 help 1570 This option provides the ability to inject artificial errors to 1571 specified notifier chain callbacks. It is useful to test the error 1572 handling of notifier call chain failures. 1573 1574 Say N if unsure. 1575 1576config PM_NOTIFIER_ERROR_INJECT 1577 tristate "PM notifier error injection module" 1578 depends on PM && NOTIFIER_ERROR_INJECTION 1579 default m if PM_DEBUG 1580 help 1581 This option provides the ability to inject artificial errors to 1582 PM notifier chain callbacks. It is controlled through debugfs 1583 interface /sys/kernel/debug/notifier-error-inject/pm 1584 1585 If the notifier call chain should be failed with some events 1586 notified, write the error code to "actions/<notifier event>/error". 1587 1588 Example: Inject PM suspend error (-12 = -ENOMEM) 1589 1590 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1591 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1592 # echo mem > /sys/power/state 1593 bash: echo: write error: Cannot allocate memory 1594 1595 To compile this code as a module, choose M here: the module will 1596 be called pm-notifier-error-inject. 1597 1598 If unsure, say N. 1599 1600config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1601 tristate "OF reconfig notifier error injection module" 1602 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1603 help 1604 This option provides the ability to inject artificial errors to 1605 OF reconfig notifier chain callbacks. It is controlled 1606 through debugfs interface under 1607 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1608 1609 If the notifier call chain should be failed with some events 1610 notified, write the error code to "actions/<notifier event>/error". 1611 1612 To compile this code as a module, choose M here: the module will 1613 be called of-reconfig-notifier-error-inject. 1614 1615 If unsure, say N. 1616 1617config NETDEV_NOTIFIER_ERROR_INJECT 1618 tristate "Netdev notifier error injection module" 1619 depends on NET && NOTIFIER_ERROR_INJECTION 1620 help 1621 This option provides the ability to inject artificial errors to 1622 netdevice notifier chain callbacks. It is controlled through debugfs 1623 interface /sys/kernel/debug/notifier-error-inject/netdev 1624 1625 If the notifier call chain should be failed with some events 1626 notified, write the error code to "actions/<notifier event>/error". 1627 1628 Example: Inject netdevice mtu change error (-22 = -EINVAL) 1629 1630 # cd /sys/kernel/debug/notifier-error-inject/netdev 1631 # echo -22 > actions/NETDEV_CHANGEMTU/error 1632 # ip link set eth0 mtu 1024 1633 RTNETLINK answers: Invalid argument 1634 1635 To compile this code as a module, choose M here: the module will 1636 be called netdev-notifier-error-inject. 1637 1638 If unsure, say N. 1639 1640config FUNCTION_ERROR_INJECTION 1641 def_bool y 1642 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 1643 1644config FAULT_INJECTION 1645 bool "Fault-injection framework" 1646 depends on DEBUG_KERNEL 1647 help 1648 Provide fault-injection framework. 1649 For more details, see Documentation/fault-injection/. 1650 1651config FAILSLAB 1652 bool "Fault-injection capability for kmalloc" 1653 depends on FAULT_INJECTION 1654 depends on SLAB || SLUB 1655 help 1656 Provide fault-injection capability for kmalloc. 1657 1658config FAIL_PAGE_ALLOC 1659 bool "Fault-injection capabilitiy for alloc_pages()" 1660 depends on FAULT_INJECTION 1661 help 1662 Provide fault-injection capability for alloc_pages(). 1663 1664config FAIL_MAKE_REQUEST 1665 bool "Fault-injection capability for disk IO" 1666 depends on FAULT_INJECTION && BLOCK 1667 help 1668 Provide fault-injection capability for disk IO. 1669 1670config FAIL_IO_TIMEOUT 1671 bool "Fault-injection capability for faking disk interrupts" 1672 depends on FAULT_INJECTION && BLOCK 1673 help 1674 Provide fault-injection capability on end IO handling. This 1675 will make the block layer "forget" an interrupt as configured, 1676 thus exercising the error handling. 1677 1678 Only works with drivers that use the generic timeout handling, 1679 for others it wont do anything. 1680 1681config FAIL_FUTEX 1682 bool "Fault-injection capability for futexes" 1683 select DEBUG_FS 1684 depends on FAULT_INJECTION && FUTEX 1685 help 1686 Provide fault-injection capability for futexes. 1687 1688config FAULT_INJECTION_DEBUG_FS 1689 bool "Debugfs entries for fault-injection capabilities" 1690 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 1691 help 1692 Enable configuration of fault-injection capabilities via debugfs. 1693 1694config FAIL_FUNCTION 1695 bool "Fault-injection capability for functions" 1696 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 1697 help 1698 Provide function-based fault-injection capability. 1699 This will allow you to override a specific function with a return 1700 with given return value. As a result, function caller will see 1701 an error value and have to handle it. This is useful to test the 1702 error handling in various subsystems. 1703 1704config FAIL_MMC_REQUEST 1705 bool "Fault-injection capability for MMC IO" 1706 depends on FAULT_INJECTION_DEBUG_FS && MMC 1707 help 1708 Provide fault-injection capability for MMC IO. 1709 This will make the mmc core return data errors. This is 1710 useful to test the error handling in the mmc block device 1711 and to test how the mmc host driver handles retries from 1712 the block device. 1713 1714config FAULT_INJECTION_STACKTRACE_FILTER 1715 bool "stacktrace filter for fault-injection capabilities" 1716 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 1717 depends on !X86_64 1718 select STACKTRACE 1719 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86 1720 help 1721 Provide stacktrace filter for fault-injection capabilities 1722 1723config ARCH_HAS_KCOV 1724 bool 1725 help 1726 An architecture should select this when it can successfully 1727 build and run with CONFIG_KCOV. This typically requires 1728 disabling instrumentation for some early boot code. 1729 1730config CC_HAS_SANCOV_TRACE_PC 1731 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 1732 1733 1734config KCOV 1735 bool "Code coverage for fuzzing" 1736 depends on ARCH_HAS_KCOV 1737 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 1738 select DEBUG_FS 1739 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 1740 help 1741 KCOV exposes kernel code coverage information in a form suitable 1742 for coverage-guided fuzzing (randomized testing). 1743 1744 If RANDOMIZE_BASE is enabled, PC values will not be stable across 1745 different machines and across reboots. If you need stable PC values, 1746 disable RANDOMIZE_BASE. 1747 1748 For more details, see Documentation/dev-tools/kcov.rst. 1749 1750config KCOV_ENABLE_COMPARISONS 1751 bool "Enable comparison operands collection by KCOV" 1752 depends on KCOV 1753 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 1754 help 1755 KCOV also exposes operands of every comparison in the instrumented 1756 code along with operand sizes and PCs of the comparison instructions. 1757 These operands can be used by fuzzing engines to improve the quality 1758 of fuzzing coverage. 1759 1760config KCOV_INSTRUMENT_ALL 1761 bool "Instrument all code by default" 1762 depends on KCOV 1763 default y 1764 help 1765 If you are doing generic system call fuzzing (like e.g. syzkaller), 1766 then you will want to instrument the whole kernel and you should 1767 say y here. If you are doing more targeted fuzzing (like e.g. 1768 filesystem fuzzing with AFL) then you will want to enable coverage 1769 for more specific subsets of files, and should say n here. 1770 1771menuconfig RUNTIME_TESTING_MENU 1772 bool "Runtime Testing" 1773 def_bool y 1774 1775if RUNTIME_TESTING_MENU 1776 1777config LKDTM 1778 tristate "Linux Kernel Dump Test Tool Module" 1779 depends on DEBUG_FS 1780 help 1781 This module enables testing of the different dumping mechanisms by 1782 inducing system failures at predefined crash points. 1783 If you don't need it: say N 1784 Choose M here to compile this code as a module. The module will be 1785 called lkdtm. 1786 1787 Documentation on how to use the module can be found in 1788 Documentation/fault-injection/provoke-crashes.rst 1789 1790config TEST_LIST_SORT 1791 tristate "Linked list sorting test" 1792 depends on DEBUG_KERNEL || m 1793 help 1794 Enable this to turn on 'list_sort()' function test. This test is 1795 executed only once during system boot (so affects only boot time), 1796 or at module load time. 1797 1798 If unsure, say N. 1799 1800config TEST_MIN_HEAP 1801 tristate "Min heap test" 1802 depends on DEBUG_KERNEL || m 1803 help 1804 Enable this to turn on min heap function tests. This test is 1805 executed only once during system boot (so affects only boot time), 1806 or at module load time. 1807 1808 If unsure, say N. 1809 1810config TEST_SORT 1811 tristate "Array-based sort test" 1812 depends on DEBUG_KERNEL || m 1813 help 1814 This option enables the self-test function of 'sort()' at boot, 1815 or at module load time. 1816 1817 If unsure, say N. 1818 1819config KPROBES_SANITY_TEST 1820 bool "Kprobes sanity tests" 1821 depends on DEBUG_KERNEL 1822 depends on KPROBES 1823 help 1824 This option provides for testing basic kprobes functionality on 1825 boot. Samples of kprobe and kretprobe are inserted and 1826 verified for functionality. 1827 1828 Say N if you are unsure. 1829 1830config BACKTRACE_SELF_TEST 1831 tristate "Self test for the backtrace code" 1832 depends on DEBUG_KERNEL 1833 help 1834 This option provides a kernel module that can be used to test 1835 the kernel stack backtrace code. This option is not useful 1836 for distributions or general kernels, but only for kernel 1837 developers working on architecture code. 1838 1839 Note that if you want to also test saved backtraces, you will 1840 have to enable STACKTRACE as well. 1841 1842 Say N if you are unsure. 1843 1844config RBTREE_TEST 1845 tristate "Red-Black tree test" 1846 depends on DEBUG_KERNEL 1847 help 1848 A benchmark measuring the performance of the rbtree library. 1849 Also includes rbtree invariant checks. 1850 1851config REED_SOLOMON_TEST 1852 tristate "Reed-Solomon library test" 1853 depends on DEBUG_KERNEL || m 1854 select REED_SOLOMON 1855 select REED_SOLOMON_ENC16 1856 select REED_SOLOMON_DEC16 1857 help 1858 This option enables the self-test function of rslib at boot, 1859 or at module load time. 1860 1861 If unsure, say N. 1862 1863config INTERVAL_TREE_TEST 1864 tristate "Interval tree test" 1865 depends on DEBUG_KERNEL 1866 select INTERVAL_TREE 1867 help 1868 A benchmark measuring the performance of the interval tree library 1869 1870config PERCPU_TEST 1871 tristate "Per cpu operations test" 1872 depends on m && DEBUG_KERNEL 1873 help 1874 Enable this option to build test module which validates per-cpu 1875 operations. 1876 1877 If unsure, say N. 1878 1879config ATOMIC64_SELFTEST 1880 tristate "Perform an atomic64_t self-test" 1881 help 1882 Enable this option to test the atomic64_t functions at boot or 1883 at module load time. 1884 1885 If unsure, say N. 1886 1887config ASYNC_RAID6_TEST 1888 tristate "Self test for hardware accelerated raid6 recovery" 1889 depends on ASYNC_RAID6_RECOV 1890 select ASYNC_MEMCPY 1891 ---help--- 1892 This is a one-shot self test that permutes through the 1893 recovery of all the possible two disk failure scenarios for a 1894 N-disk array. Recovery is performed with the asynchronous 1895 raid6 recovery routines, and will optionally use an offload 1896 engine if one is available. 1897 1898 If unsure, say N. 1899 1900config TEST_HEXDUMP 1901 tristate "Test functions located in the hexdump module at runtime" 1902 1903config TEST_STRING_HELPERS 1904 tristate "Test functions located in the string_helpers module at runtime" 1905 1906config TEST_STRSCPY 1907 tristate "Test strscpy*() family of functions at runtime" 1908 1909config TEST_KSTRTOX 1910 tristate "Test kstrto*() family of functions at runtime" 1911 1912config TEST_PRINTF 1913 tristate "Test printf() family of functions at runtime" 1914 1915config TEST_BITMAP 1916 tristate "Test bitmap_*() family of functions at runtime" 1917 help 1918 Enable this option to test the bitmap functions at boot. 1919 1920 If unsure, say N. 1921 1922config TEST_BITFIELD 1923 tristate "Test bitfield functions at runtime" 1924 help 1925 Enable this option to test the bitfield functions at boot. 1926 1927 If unsure, say N. 1928 1929config TEST_UUID 1930 tristate "Test functions located in the uuid module at runtime" 1931 1932config TEST_XARRAY 1933 tristate "Test the XArray code at runtime" 1934 1935config TEST_OVERFLOW 1936 tristate "Test check_*_overflow() functions at runtime" 1937 1938config TEST_RHASHTABLE 1939 tristate "Perform selftest on resizable hash table" 1940 help 1941 Enable this option to test the rhashtable functions at boot. 1942 1943 If unsure, say N. 1944 1945config TEST_HASH 1946 tristate "Perform selftest on hash functions" 1947 help 1948 Enable this option to test the kernel's integer (<linux/hash.h>), 1949 string (<linux/stringhash.h>), and siphash (<linux/siphash.h>) 1950 hash functions on boot (or module load). 1951 1952 This is intended to help people writing architecture-specific 1953 optimized versions. If unsure, say N. 1954 1955config TEST_IDA 1956 tristate "Perform selftest on IDA functions" 1957 1958config TEST_PARMAN 1959 tristate "Perform selftest on priority array manager" 1960 depends on PARMAN 1961 help 1962 Enable this option to test priority array manager on boot 1963 (or module load). 1964 1965 If unsure, say N. 1966 1967config TEST_IRQ_TIMINGS 1968 bool "IRQ timings selftest" 1969 depends on IRQ_TIMINGS 1970 help 1971 Enable this option to test the irq timings code on boot. 1972 1973 If unsure, say N. 1974 1975config TEST_LKM 1976 tristate "Test module loading with 'hello world' module" 1977 depends on m 1978 help 1979 This builds the "test_module" module that emits "Hello, world" 1980 on printk when loaded. It is designed to be used for basic 1981 evaluation of the module loading subsystem (for example when 1982 validating module verification). It lacks any extra dependencies, 1983 and will not normally be loaded by the system unless explicitly 1984 requested by name. 1985 1986 If unsure, say N. 1987 1988config TEST_VMALLOC 1989 tristate "Test module for stress/performance analysis of vmalloc allocator" 1990 default n 1991 depends on MMU 1992 depends on m 1993 help 1994 This builds the "test_vmalloc" module that should be used for 1995 stress and performance analysis. So, any new change for vmalloc 1996 subsystem can be evaluated from performance and stability point 1997 of view. 1998 1999 If unsure, say N. 2000 2001config TEST_USER_COPY 2002 tristate "Test user/kernel boundary protections" 2003 depends on m 2004 help 2005 This builds the "test_user_copy" module that runs sanity checks 2006 on the copy_to/from_user infrastructure, making sure basic 2007 user/kernel boundary testing is working. If it fails to load, 2008 a regression has been detected in the user/kernel memory boundary 2009 protections. 2010 2011 If unsure, say N. 2012 2013config TEST_BPF 2014 tristate "Test BPF filter functionality" 2015 depends on m && NET 2016 help 2017 This builds the "test_bpf" module that runs various test vectors 2018 against the BPF interpreter or BPF JIT compiler depending on the 2019 current setting. This is in particular useful for BPF JIT compiler 2020 development, but also to run regression tests against changes in 2021 the interpreter code. It also enables test stubs for eBPF maps and 2022 verifier used by user space verifier testsuite. 2023 2024 If unsure, say N. 2025 2026config TEST_BLACKHOLE_DEV 2027 tristate "Test blackhole netdev functionality" 2028 depends on m && NET 2029 help 2030 This builds the "test_blackhole_dev" module that validates the 2031 data path through this blackhole netdev. 2032 2033 If unsure, say N. 2034 2035config FIND_BIT_BENCHMARK 2036 tristate "Test find_bit functions" 2037 help 2038 This builds the "test_find_bit" module that measure find_*_bit() 2039 functions performance. 2040 2041 If unsure, say N. 2042 2043config TEST_FIRMWARE 2044 tristate "Test firmware loading via userspace interface" 2045 depends on FW_LOADER 2046 help 2047 This builds the "test_firmware" module that creates a userspace 2048 interface for testing firmware loading. This can be used to 2049 control the triggering of firmware loading without needing an 2050 actual firmware-using device. The contents can be rechecked by 2051 userspace. 2052 2053 If unsure, say N. 2054 2055config TEST_SYSCTL 2056 tristate "sysctl test driver" 2057 depends on PROC_SYSCTL 2058 help 2059 This builds the "test_sysctl" module. This driver enables to test the 2060 proc sysctl interfaces available to drivers safely without affecting 2061 production knobs which might alter system functionality. 2062 2063 If unsure, say N. 2064 2065config SYSCTL_KUNIT_TEST 2066 tristate "KUnit test for sysctl" 2067 depends on KUNIT 2068 help 2069 This builds the proc sysctl unit test, which runs on boot. 2070 Tests the API contract and implementation correctness of sysctl. 2071 For more information on KUnit and unit tests in general please refer 2072 to the KUnit documentation in Documentation/dev-tools/kunit/. 2073 2074 If unsure, say N. 2075 2076config LIST_KUNIT_TEST 2077 tristate "KUnit Test for Kernel Linked-list structures" 2078 depends on KUNIT 2079 help 2080 This builds the linked list KUnit test suite. 2081 It tests that the API and basic functionality of the list_head type 2082 and associated macros. 2083 2084 KUnit tests run during boot and output the results to the debug log 2085 in TAP format (http://testanything.org/). Only useful for kernel devs 2086 running the KUnit test harness, and not intended for inclusion into a 2087 production build. 2088 2089 For more information on KUnit and unit tests in general please refer 2090 to the KUnit documentation in Documentation/dev-tools/kunit/. 2091 2092 If unsure, say N. 2093 2094config TEST_UDELAY 2095 tristate "udelay test driver" 2096 help 2097 This builds the "udelay_test" module that helps to make sure 2098 that udelay() is working properly. 2099 2100 If unsure, say N. 2101 2102config TEST_STATIC_KEYS 2103 tristate "Test static keys" 2104 depends on m 2105 help 2106 Test the static key interfaces. 2107 2108 If unsure, say N. 2109 2110config TEST_KMOD 2111 tristate "kmod stress tester" 2112 depends on m 2113 depends on NETDEVICES && NET_CORE && INET # for TUN 2114 depends on BLOCK 2115 select TEST_LKM 2116 select XFS_FS 2117 select TUN 2118 select BTRFS_FS 2119 help 2120 Test the kernel's module loading mechanism: kmod. kmod implements 2121 support to load modules using the Linux kernel's usermode helper. 2122 This test provides a series of tests against kmod. 2123 2124 Although technically you can either build test_kmod as a module or 2125 into the kernel we disallow building it into the kernel since 2126 it stress tests request_module() and this will very likely cause 2127 some issues by taking over precious threads available from other 2128 module load requests, ultimately this could be fatal. 2129 2130 To run tests run: 2131 2132 tools/testing/selftests/kmod/kmod.sh --help 2133 2134 If unsure, say N. 2135 2136config TEST_DEBUG_VIRTUAL 2137 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 2138 depends on DEBUG_VIRTUAL 2139 help 2140 Test the kernel's ability to detect incorrect calls to 2141 virt_to_phys() done against the non-linear part of the 2142 kernel's virtual address map. 2143 2144 If unsure, say N. 2145 2146config TEST_MEMCAT_P 2147 tristate "Test memcat_p() helper function" 2148 help 2149 Test the memcat_p() helper for correctly merging two 2150 pointer arrays together. 2151 2152 If unsure, say N. 2153 2154config TEST_LIVEPATCH 2155 tristate "Test livepatching" 2156 default n 2157 depends on DYNAMIC_DEBUG 2158 depends on LIVEPATCH 2159 depends on m 2160 help 2161 Test kernel livepatching features for correctness. The tests will 2162 load test modules that will be livepatched in various scenarios. 2163 2164 To run all the livepatching tests: 2165 2166 make -C tools/testing/selftests TARGETS=livepatch run_tests 2167 2168 Alternatively, individual tests may be invoked: 2169 2170 tools/testing/selftests/livepatch/test-callbacks.sh 2171 tools/testing/selftests/livepatch/test-livepatch.sh 2172 tools/testing/selftests/livepatch/test-shadow-vars.sh 2173 2174 If unsure, say N. 2175 2176config TEST_OBJAGG 2177 tristate "Perform selftest on object aggreration manager" 2178 default n 2179 depends on OBJAGG 2180 help 2181 Enable this option to test object aggregation manager on boot 2182 (or module load). 2183 2184 2185config TEST_STACKINIT 2186 tristate "Test level of stack variable initialization" 2187 help 2188 Test if the kernel is zero-initializing stack variables and 2189 padding. Coverage is controlled by compiler flags, 2190 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2191 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2192 2193 If unsure, say N. 2194 2195config TEST_MEMINIT 2196 tristate "Test heap/page initialization" 2197 help 2198 Test if the kernel is zero-initializing heap and page allocations. 2199 This can be useful to test init_on_alloc and init_on_free features. 2200 2201 If unsure, say N. 2202 2203endif # RUNTIME_TESTING_MENU 2204 2205config MEMTEST 2206 bool "Memtest" 2207 ---help--- 2208 This option adds a kernel parameter 'memtest', which allows memtest 2209 to be set. 2210 memtest=0, mean disabled; -- default 2211 memtest=1, mean do 1 test pattern; 2212 ... 2213 memtest=17, mean do 17 test patterns. 2214 If you are unsure how to answer this question, answer N. 2215 2216 2217 2218config HYPERV_TESTING 2219 bool "Microsoft Hyper-V driver testing" 2220 default n 2221 depends on HYPERV && DEBUG_FS 2222 help 2223 Select this option to enable Hyper-V vmbus testing. 2224 2225endmenu # "Kernel Testing and Coverage" 2226 2227endmenu # Kernel hacking 2228