1# SPDX-License-Identifier: GPL-2.0-only 2menu "Kernel hacking" 3 4menu "printk and dmesg options" 5 6config PRINTK_TIME 7 bool "Show timing information on printks" 8 depends on PRINTK 9 help 10 Selecting this option causes time stamps of the printk() 11 messages to be added to the output of the syslog() system 12 call and at the console. 13 14 The timestamp is always recorded internally, and exported 15 to /dev/kmsg. This flag just specifies if the timestamp should 16 be included, not that the timestamp is recorded. 17 18 The behavior is also controlled by the kernel command line 19 parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst 20 21config PRINTK_CALLER 22 bool "Show caller information on printks" 23 depends on PRINTK 24 help 25 Selecting this option causes printk() to add a caller "thread id" (if 26 in task context) or a caller "processor id" (if not in task context) 27 to every message. 28 29 This option is intended for environments where multiple threads 30 concurrently call printk() for many times, for it is difficult to 31 interpret without knowing where these lines (or sometimes individual 32 line which was divided into multiple lines due to race) came from. 33 34 Since toggling after boot makes the code racy, currently there is 35 no option to enable/disable at the kernel command line parameter or 36 sysfs interface. 37 38config CONSOLE_LOGLEVEL_DEFAULT 39 int "Default console loglevel (1-15)" 40 range 1 15 41 default "7" 42 help 43 Default loglevel to determine what will be printed on the console. 44 45 Setting a default here is equivalent to passing in loglevel=<x> in 46 the kernel bootargs. loglevel=<x> continues to override whatever 47 value is specified here as well. 48 49 Note: This does not affect the log level of un-prefixed printk() 50 usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT 51 option. 52 53config CONSOLE_LOGLEVEL_QUIET 54 int "quiet console loglevel (1-15)" 55 range 1 15 56 default "4" 57 help 58 loglevel to use when "quiet" is passed on the kernel commandline. 59 60 When "quiet" is passed on the kernel commandline this loglevel 61 will be used as the loglevel. IOW passing "quiet" will be the 62 equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>" 63 64config MESSAGE_LOGLEVEL_DEFAULT 65 int "Default message log level (1-7)" 66 range 1 7 67 default "4" 68 help 69 Default log level for printk statements with no specified priority. 70 71 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks 72 that are auditing their logs closely may want to set it to a lower 73 priority. 74 75 Note: This does not affect what message level gets printed on the console 76 by default. To change that, use loglevel=<x> in the kernel bootargs, 77 or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value. 78 79config BOOT_PRINTK_DELAY 80 bool "Delay each boot printk message by N milliseconds" 81 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY 82 help 83 This build option allows you to read kernel boot messages 84 by inserting a short delay after each one. The delay is 85 specified in milliseconds on the kernel command line, 86 using "boot_delay=N". 87 88 It is likely that you would also need to use "lpj=M" to preset 89 the "loops per jiffie" value. 90 See a previous boot log for the "lpj" value to use for your 91 system, and then set "lpj=M" before setting "boot_delay=N". 92 NOTE: Using this option may adversely affect SMP systems. 93 I.e., processors other than the first one may not boot up. 94 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect 95 what it believes to be lockup conditions. 96 97config DYNAMIC_DEBUG 98 bool "Enable dynamic printk() support" 99 default n 100 depends on PRINTK 101 depends on (DEBUG_FS || PROC_FS) 102 help 103 104 Compiles debug level messages into the kernel, which would not 105 otherwise be available at runtime. These messages can then be 106 enabled/disabled based on various levels of scope - per source file, 107 function, module, format string, and line number. This mechanism 108 implicitly compiles in all pr_debug() and dev_dbg() calls, which 109 enlarges the kernel text size by about 2%. 110 111 If a source file is compiled with DEBUG flag set, any 112 pr_debug() calls in it are enabled by default, but can be 113 disabled at runtime as below. Note that DEBUG flag is 114 turned on by many CONFIG_*DEBUG* options. 115 116 Usage: 117 118 Dynamic debugging is controlled via the 'dynamic_debug/control' file, 119 which is contained in the 'debugfs' filesystem or procfs. 120 Thus, the debugfs or procfs filesystem must first be mounted before 121 making use of this feature. 122 We refer the control file as: <debugfs>/dynamic_debug/control. This 123 file contains a list of the debug statements that can be enabled. The 124 format for each line of the file is: 125 126 filename:lineno [module]function flags format 127 128 filename : source file of the debug statement 129 lineno : line number of the debug statement 130 module : module that contains the debug statement 131 function : function that contains the debug statement 132 flags : '=p' means the line is turned 'on' for printing 133 format : the format used for the debug statement 134 135 From a live system: 136 137 nullarbor:~ # cat <debugfs>/dynamic_debug/control 138 # filename:lineno [module]function flags format 139 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012" 140 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012" 141 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012" 142 143 Example usage: 144 145 // enable the message at line 1603 of file svcsock.c 146 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' > 147 <debugfs>/dynamic_debug/control 148 149 // enable all the messages in file svcsock.c 150 nullarbor:~ # echo -n 'file svcsock.c +p' > 151 <debugfs>/dynamic_debug/control 152 153 // enable all the messages in the NFS server module 154 nullarbor:~ # echo -n 'module nfsd +p' > 155 <debugfs>/dynamic_debug/control 156 157 // enable all 12 messages in the function svc_process() 158 nullarbor:~ # echo -n 'func svc_process +p' > 159 <debugfs>/dynamic_debug/control 160 161 // disable all 12 messages in the function svc_process() 162 nullarbor:~ # echo -n 'func svc_process -p' > 163 <debugfs>/dynamic_debug/control 164 165 See Documentation/admin-guide/dynamic-debug-howto.rst for additional 166 information. 167 168config SYMBOLIC_ERRNAME 169 bool "Support symbolic error names in printf" 170 default y if PRINTK 171 help 172 If you say Y here, the kernel's printf implementation will 173 be able to print symbolic error names such as ENOSPC instead 174 of the number 28. It makes the kernel image slightly larger 175 (about 3KB), but can make the kernel logs easier to read. 176 177config DEBUG_BUGVERBOSE 178 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT 179 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE) 180 default y 181 help 182 Say Y here to make BUG() panics output the file name and line number 183 of the BUG call as well as the EIP and oops trace. This aids 184 debugging but costs about 70-100K of memory. 185 186endmenu # "printk and dmesg options" 187 188menu "Compile-time checks and compiler options" 189 190config DEBUG_INFO 191 bool "Compile the kernel with debug info" 192 depends on DEBUG_KERNEL && !COMPILE_TEST 193 help 194 If you say Y here the resulting kernel image will include 195 debugging info resulting in a larger kernel image. 196 This adds debug symbols to the kernel and modules (gcc -g), and 197 is needed if you intend to use kernel crashdump or binary object 198 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 199 Say Y here only if you plan to debug the kernel. 200 201 If unsure, say N. 202 203config DEBUG_INFO_REDUCED 204 bool "Reduce debugging information" 205 depends on DEBUG_INFO 206 help 207 If you say Y here gcc is instructed to generate less debugging 208 information for structure types. This means that tools that 209 need full debugging information (like kgdb or systemtap) won't 210 be happy. But if you merely need debugging information to 211 resolve line numbers there is no loss. Advantage is that 212 build directory object sizes shrink dramatically over a full 213 DEBUG_INFO build and compile times are reduced too. 214 Only works with newer gcc versions. 215 216config DEBUG_INFO_SPLIT 217 bool "Produce split debuginfo in .dwo files" 218 depends on DEBUG_INFO 219 depends on $(cc-option,-gsplit-dwarf) 220 help 221 Generate debug info into separate .dwo files. This significantly 222 reduces the build directory size for builds with DEBUG_INFO, 223 because it stores the information only once on disk in .dwo 224 files instead of multiple times in object files and executables. 225 In addition the debug information is also compressed. 226 227 Requires recent gcc (4.7+) and recent gdb/binutils. 228 Any tool that packages or reads debug information would need 229 to know about the .dwo files and include them. 230 Incompatible with older versions of ccache. 231 232config DEBUG_INFO_DWARF4 233 bool "Generate dwarf4 debuginfo" 234 depends on DEBUG_INFO 235 depends on $(cc-option,-gdwarf-4) 236 help 237 Generate dwarf4 debug info. This requires recent versions 238 of gcc and gdb. It makes the debug information larger. 239 But it significantly improves the success of resolving 240 variables in gdb on optimized code. 241 242config DEBUG_INFO_BTF 243 bool "Generate BTF typeinfo" 244 depends on DEBUG_INFO 245 help 246 Generate deduplicated BTF type information from DWARF debug info. 247 Turning this on expects presence of pahole tool, which will convert 248 DWARF type info into equivalent deduplicated BTF type info. 249 250config GDB_SCRIPTS 251 bool "Provide GDB scripts for kernel debugging" 252 depends on DEBUG_INFO 253 help 254 This creates the required links to GDB helper scripts in the 255 build directory. If you load vmlinux into gdb, the helper 256 scripts will be automatically imported by gdb as well, and 257 additional functions are available to analyze a Linux kernel 258 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst 259 for further details. 260 261config ENABLE_MUST_CHECK 262 bool "Enable __must_check logic" 263 default y 264 help 265 Enable the __must_check logic in the kernel build. Disable this to 266 suppress the "warning: ignoring return value of 'foo', declared with 267 attribute warn_unused_result" messages. 268 269config FRAME_WARN 270 int "Warn for stack frames larger than" 271 range 0 8192 272 default 2048 if GCC_PLUGIN_LATENT_ENTROPY 273 default 1280 if (!64BIT && PARISC) 274 default 1024 if (!64BIT && !PARISC) 275 default 2048 if 64BIT 276 help 277 Tell gcc to warn at build time for stack frames larger than this. 278 Setting this too low will cause a lot of warnings. 279 Setting it to 0 disables the warning. 280 281config STRIP_ASM_SYMS 282 bool "Strip assembler-generated symbols during link" 283 default n 284 help 285 Strip internal assembler-generated symbols during a link (symbols 286 that look like '.Lxxx') so they don't pollute the output of 287 get_wchan() and suchlike. 288 289config READABLE_ASM 290 bool "Generate readable assembler code" 291 depends on DEBUG_KERNEL 292 help 293 Disable some compiler optimizations that tend to generate human unreadable 294 assembler output. This may make the kernel slightly slower, but it helps 295 to keep kernel developers who have to stare a lot at assembler listings 296 sane. 297 298config HEADERS_INSTALL 299 bool "Install uapi headers to usr/include" 300 depends on !UML 301 help 302 This option will install uapi headers (headers exported to user-space) 303 into the usr/include directory for use during the kernel build. 304 This is unneeded for building the kernel itself, but needed for some 305 user-space program samples. It is also needed by some features such 306 as uapi header sanity checks. 307 308config OPTIMIZE_INLINING 309 def_bool y 310 help 311 This option determines if the kernel forces gcc to inline the functions 312 developers have marked 'inline'. Doing so takes away freedom from gcc to 313 do what it thinks is best, which is desirable for the gcc 3.x series of 314 compilers. The gcc 4.x series have a rewritten inlining algorithm and 315 enabling this option will generate a smaller kernel there. Hopefully 316 this algorithm is so good that allowing gcc 4.x and above to make the 317 decision will become the default in the future. Until then this option 318 is there to test gcc for this. 319 320config DEBUG_SECTION_MISMATCH 321 bool "Enable full Section mismatch analysis" 322 help 323 The section mismatch analysis checks if there are illegal 324 references from one section to another section. 325 During linktime or runtime, some sections are dropped; 326 any use of code/data previously in these sections would 327 most likely result in an oops. 328 In the code, functions and variables are annotated with 329 __init,, etc. (see the full list in include/linux/init.h), 330 which results in the code/data being placed in specific sections. 331 The section mismatch analysis is always performed after a full 332 kernel build, and enabling this option causes the following 333 additional step to occur: 334 - Add the option -fno-inline-functions-called-once to gcc commands. 335 When inlining a function annotated with __init in a non-init 336 function, we would lose the section information and thus 337 the analysis would not catch the illegal reference. 338 This option tells gcc to inline less (but it does result in 339 a larger kernel). 340 341config SECTION_MISMATCH_WARN_ONLY 342 bool "Make section mismatch errors non-fatal" 343 default y 344 help 345 If you say N here, the build process will fail if there are any 346 section mismatch, instead of just throwing warnings. 347 348 If unsure, say Y. 349 350# 351# Select this config option from the architecture Kconfig, if it 352# is preferred to always offer frame pointers as a config 353# option on the architecture (regardless of KERNEL_DEBUG): 354# 355config ARCH_WANT_FRAME_POINTERS 356 bool 357 358config FRAME_POINTER 359 bool "Compile the kernel with frame pointers" 360 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS 361 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 362 help 363 If you say Y here the resulting kernel image will be slightly 364 larger and slower, but it gives very useful debugging information 365 in case of kernel bugs. (precise oopses/stacktraces/warnings) 366 367config STACK_VALIDATION 368 bool "Compile-time stack metadata validation" 369 depends on HAVE_STACK_VALIDATION 370 default n 371 help 372 Add compile-time checks to validate stack metadata, including frame 373 pointers (if CONFIG_FRAME_POINTER is enabled). This helps ensure 374 that runtime stack traces are more reliable. 375 376 This is also a prerequisite for generation of ORC unwind data, which 377 is needed for CONFIG_UNWINDER_ORC. 378 379 For more information, see 380 tools/objtool/Documentation/stack-validation.txt. 381 382config DEBUG_FORCE_WEAK_PER_CPU 383 bool "Force weak per-cpu definitions" 384 depends on DEBUG_KERNEL 385 help 386 s390 and alpha require percpu variables in modules to be 387 defined weak to work around addressing range issue which 388 puts the following two restrictions on percpu variable 389 definitions. 390 391 1. percpu symbols must be unique whether static or not 392 2. percpu variables can't be defined inside a function 393 394 To ensure that generic code follows the above rules, this 395 option forces all percpu variables to be defined as weak. 396 397endmenu # "Compiler options" 398 399menu "Generic Kernel Debugging Instruments" 400 401config MAGIC_SYSRQ 402 bool "Magic SysRq key" 403 depends on !UML 404 help 405 If you say Y here, you will have some control over the system even 406 if the system crashes for example during kernel debugging (e.g., you 407 will be able to flush the buffer cache to disk, reboot the system 408 immediately or dump some status information). This is accomplished 409 by pressing various keys while holding SysRq (Alt+PrintScreen). It 410 also works on a serial console (on PC hardware at least), if you 411 send a BREAK and then within 5 seconds a command keypress. The 412 keys are documented in <file:Documentation/admin-guide/sysrq.rst>. 413 Don't say Y unless you really know what this hack does. 414 415config MAGIC_SYSRQ_DEFAULT_ENABLE 416 hex "Enable magic SysRq key functions by default" 417 depends on MAGIC_SYSRQ 418 default 0x1 419 help 420 Specifies which SysRq key functions are enabled by default. 421 This may be set to 1 or 0 to enable or disable them all, or 422 to a bitmask as described in Documentation/admin-guide/sysrq.rst. 423 424config MAGIC_SYSRQ_SERIAL 425 bool "Enable magic SysRq key over serial" 426 depends on MAGIC_SYSRQ 427 default y 428 help 429 Many embedded boards have a disconnected TTL level serial which can 430 generate some garbage that can lead to spurious false sysrq detects. 431 This option allows you to decide whether you want to enable the 432 magic SysRq key. 433 434config MAGIC_SYSRQ_SERIAL_SEQUENCE 435 string "Char sequence that enables magic SysRq over serial" 436 depends on MAGIC_SYSRQ_SERIAL 437 default "" 438 help 439 Specifies a sequence of characters that can follow BREAK to enable 440 SysRq on a serial console. 441 442 If unsure, leave an empty string and the option will not be enabled. 443 444config DEBUG_FS 445 bool "Debug Filesystem" 446 help 447 debugfs is a virtual file system that kernel developers use to put 448 debugging files into. Enable this option to be able to read and 449 write to these files. 450 451 For detailed documentation on the debugfs API, see 452 Documentation/filesystems/. 453 454 If unsure, say N. 455 456source "lib/Kconfig.kgdb" 457 458source "lib/Kconfig.ubsan" 459 460endmenu 461 462config DEBUG_KERNEL 463 bool "Kernel debugging" 464 help 465 Say Y here if you are developing drivers or trying to debug and 466 identify kernel problems. 467 468config DEBUG_MISC 469 bool "Miscellaneous debug code" 470 default DEBUG_KERNEL 471 depends on DEBUG_KERNEL 472 help 473 Say Y here if you need to enable miscellaneous debug code that should 474 be under a more specific debug option but isn't. 475 476 477menu "Memory Debugging" 478 479source "mm/Kconfig.debug" 480 481config DEBUG_OBJECTS 482 bool "Debug object operations" 483 depends on DEBUG_KERNEL 484 help 485 If you say Y here, additional code will be inserted into the 486 kernel to track the life time of various objects and validate 487 the operations on those objects. 488 489config DEBUG_OBJECTS_SELFTEST 490 bool "Debug objects selftest" 491 depends on DEBUG_OBJECTS 492 help 493 This enables the selftest of the object debug code. 494 495config DEBUG_OBJECTS_FREE 496 bool "Debug objects in freed memory" 497 depends on DEBUG_OBJECTS 498 help 499 This enables checks whether a k/v free operation frees an area 500 which contains an object which has not been deactivated 501 properly. This can make kmalloc/kfree-intensive workloads 502 much slower. 503 504config DEBUG_OBJECTS_TIMERS 505 bool "Debug timer objects" 506 depends on DEBUG_OBJECTS 507 help 508 If you say Y here, additional code will be inserted into the 509 timer routines to track the life time of timer objects and 510 validate the timer operations. 511 512config DEBUG_OBJECTS_WORK 513 bool "Debug work objects" 514 depends on DEBUG_OBJECTS 515 help 516 If you say Y here, additional code will be inserted into the 517 work queue routines to track the life time of work objects and 518 validate the work operations. 519 520config DEBUG_OBJECTS_RCU_HEAD 521 bool "Debug RCU callbacks objects" 522 depends on DEBUG_OBJECTS 523 help 524 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 525 526config DEBUG_OBJECTS_PERCPU_COUNTER 527 bool "Debug percpu counter objects" 528 depends on DEBUG_OBJECTS 529 help 530 If you say Y here, additional code will be inserted into the 531 percpu counter routines to track the life time of percpu counter 532 objects and validate the percpu counter operations. 533 534config DEBUG_OBJECTS_ENABLE_DEFAULT 535 int "debug_objects bootup default value (0-1)" 536 range 0 1 537 default "1" 538 depends on DEBUG_OBJECTS 539 help 540 Debug objects boot parameter default value 541 542config DEBUG_SLAB 543 bool "Debug slab memory allocations" 544 depends on DEBUG_KERNEL && SLAB 545 help 546 Say Y here to have the kernel do limited verification on memory 547 allocation as well as poisoning memory on free to catch use of freed 548 memory. This can make kmalloc/kfree-intensive workloads much slower. 549 550config SLUB_DEBUG_ON 551 bool "SLUB debugging on by default" 552 depends on SLUB && SLUB_DEBUG 553 default n 554 help 555 Boot with debugging on by default. SLUB boots by default with 556 the runtime debug capabilities switched off. Enabling this is 557 equivalent to specifying the "slub_debug" parameter on boot. 558 There is no support for more fine grained debug control like 559 possible with slub_debug=xxx. SLUB debugging may be switched 560 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying 561 "slub_debug=-". 562 563config SLUB_STATS 564 default n 565 bool "Enable SLUB performance statistics" 566 depends on SLUB && SYSFS 567 help 568 SLUB statistics are useful to debug SLUBs allocation behavior in 569 order find ways to optimize the allocator. This should never be 570 enabled for production use since keeping statistics slows down 571 the allocator by a few percentage points. The slabinfo command 572 supports the determination of the most active slabs to figure 573 out which slabs are relevant to a particular load. 574 Try running: slabinfo -DA 575 576config HAVE_DEBUG_KMEMLEAK 577 bool 578 579config DEBUG_KMEMLEAK 580 bool "Kernel memory leak detector" 581 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK 582 select DEBUG_FS 583 select STACKTRACE if STACKTRACE_SUPPORT 584 select KALLSYMS 585 select CRC32 586 help 587 Say Y here if you want to enable the memory leak 588 detector. The memory allocation/freeing is traced in a way 589 similar to the Boehm's conservative garbage collector, the 590 difference being that the orphan objects are not freed but 591 only shown in /sys/kernel/debug/kmemleak. Enabling this 592 feature will introduce an overhead to memory 593 allocations. See Documentation/dev-tools/kmemleak.rst for more 594 details. 595 596 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances 597 of finding leaks due to the slab objects poisoning. 598 599 In order to access the kmemleak file, debugfs needs to be 600 mounted (usually at /sys/kernel/debug). 601 602config DEBUG_KMEMLEAK_MEM_POOL_SIZE 603 int "Kmemleak memory pool size" 604 depends on DEBUG_KMEMLEAK 605 range 200 1000000 606 default 16000 607 help 608 Kmemleak must track all the memory allocations to avoid 609 reporting false positives. Since memory may be allocated or 610 freed before kmemleak is fully initialised, use a static pool 611 of metadata objects to track such callbacks. After kmemleak is 612 fully initialised, this memory pool acts as an emergency one 613 if slab allocations fail. 614 615config DEBUG_KMEMLEAK_TEST 616 tristate "Simple test for the kernel memory leak detector" 617 depends on DEBUG_KMEMLEAK && m 618 help 619 This option enables a module that explicitly leaks memory. 620 621 If unsure, say N. 622 623config DEBUG_KMEMLEAK_DEFAULT_OFF 624 bool "Default kmemleak to off" 625 depends on DEBUG_KMEMLEAK 626 help 627 Say Y here to disable kmemleak by default. It can then be enabled 628 on the command line via kmemleak=on. 629 630config DEBUG_KMEMLEAK_AUTO_SCAN 631 bool "Enable kmemleak auto scan thread on boot up" 632 default y 633 depends on DEBUG_KMEMLEAK 634 help 635 Depending on the cpu, kmemleak scan may be cpu intensive and can 636 stall user tasks at times. This option enables/disables automatic 637 kmemleak scan at boot up. 638 639 Say N here to disable kmemleak auto scan thread to stop automatic 640 scanning. Disabling this option disables automatic reporting of 641 memory leaks. 642 643 If unsure, say Y. 644 645config DEBUG_STACK_USAGE 646 bool "Stack utilization instrumentation" 647 depends on DEBUG_KERNEL && !IA64 648 help 649 Enables the display of the minimum amount of free stack which each 650 task has ever had available in the sysrq-T and sysrq-P debug output. 651 652 This option will slow down process creation somewhat. 653 654config SCHED_STACK_END_CHECK 655 bool "Detect stack corruption on calls to schedule()" 656 depends on DEBUG_KERNEL 657 default n 658 help 659 This option checks for a stack overrun on calls to schedule(). 660 If the stack end location is found to be over written always panic as 661 the content of the corrupted region can no longer be trusted. 662 This is to ensure no erroneous behaviour occurs which could result in 663 data corruption or a sporadic crash at a later stage once the region 664 is examined. The runtime overhead introduced is minimal. 665 666config DEBUG_VM 667 bool "Debug VM" 668 depends on DEBUG_KERNEL 669 help 670 Enable this to turn on extended checks in the virtual-memory system 671 that may impact performance. 672 673 If unsure, say N. 674 675config DEBUG_VM_VMACACHE 676 bool "Debug VMA caching" 677 depends on DEBUG_VM 678 help 679 Enable this to turn on VMA caching debug information. Doing so 680 can cause significant overhead, so only enable it in non-production 681 environments. 682 683 If unsure, say N. 684 685config DEBUG_VM_RB 686 bool "Debug VM red-black trees" 687 depends on DEBUG_VM 688 help 689 Enable VM red-black tree debugging information and extra validations. 690 691 If unsure, say N. 692 693config DEBUG_VM_PGFLAGS 694 bool "Debug page-flags operations" 695 depends on DEBUG_VM 696 help 697 Enables extra validation on page flags operations. 698 699 If unsure, say N. 700 701config ARCH_HAS_DEBUG_VIRTUAL 702 bool 703 704config DEBUG_VIRTUAL 705 bool "Debug VM translations" 706 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL 707 help 708 Enable some costly sanity checks in virtual to page code. This can 709 catch mistakes with virt_to_page() and friends. 710 711 If unsure, say N. 712 713config DEBUG_NOMMU_REGIONS 714 bool "Debug the global anon/private NOMMU mapping region tree" 715 depends on DEBUG_KERNEL && !MMU 716 help 717 This option causes the global tree of anonymous and private mapping 718 regions to be regularly checked for invalid topology. 719 720config DEBUG_MEMORY_INIT 721 bool "Debug memory initialisation" if EXPERT 722 default !EXPERT 723 help 724 Enable this for additional checks during memory initialisation. 725 The sanity checks verify aspects of the VM such as the memory model 726 and other information provided by the architecture. Verbose 727 information will be printed at KERN_DEBUG loglevel depending 728 on the mminit_loglevel= command-line option. 729 730 If unsure, say Y 731 732config MEMORY_NOTIFIER_ERROR_INJECT 733 tristate "Memory hotplug notifier error injection module" 734 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION 735 help 736 This option provides the ability to inject artificial errors to 737 memory hotplug notifier chain callbacks. It is controlled through 738 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 739 740 If the notifier call chain should be failed with some events 741 notified, write the error code to "actions/<notifier event>/error". 742 743 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 744 745 # cd /sys/kernel/debug/notifier-error-inject/memory 746 # echo -12 > actions/MEM_GOING_OFFLINE/error 747 # echo offline > /sys/devices/system/memory/memoryXXX/state 748 bash: echo: write error: Cannot allocate memory 749 750 To compile this code as a module, choose M here: the module will 751 be called memory-notifier-error-inject. 752 753 If unsure, say N. 754 755config DEBUG_PER_CPU_MAPS 756 bool "Debug access to per_cpu maps" 757 depends on DEBUG_KERNEL 758 depends on SMP 759 help 760 Say Y to verify that the per_cpu map being accessed has 761 been set up. This adds a fair amount of code to kernel memory 762 and decreases performance. 763 764 Say N if unsure. 765 766config DEBUG_HIGHMEM 767 bool "Highmem debugging" 768 depends on DEBUG_KERNEL && HIGHMEM 769 help 770 This option enables additional error checking for high memory 771 systems. Disable for production systems. 772 773config HAVE_DEBUG_STACKOVERFLOW 774 bool 775 776config DEBUG_STACKOVERFLOW 777 bool "Check for stack overflows" 778 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 779 ---help--- 780 Say Y here if you want to check for overflows of kernel, IRQ 781 and exception stacks (if your architecture uses them). This 782 option will show detailed messages if free stack space drops 783 below a certain limit. 784 785 These kinds of bugs usually occur when call-chains in the 786 kernel get too deep, especially when interrupts are 787 involved. 788 789 Use this in cases where you see apparently random memory 790 corruption, especially if it appears in 'struct thread_info' 791 792 If in doubt, say "N". 793 794source "lib/Kconfig.kasan" 795 796endmenu # "Memory Debugging" 797 798config DEBUG_SHIRQ 799 bool "Debug shared IRQ handlers" 800 depends on DEBUG_KERNEL 801 help 802 Enable this to generate a spurious interrupt as soon as a shared 803 interrupt handler is registered, and just before one is deregistered. 804 Drivers ought to be able to handle interrupts coming in at those 805 points; some don't and need to be caught. 806 807menu "Debug Oops, Lockups and Hangs" 808 809config PANIC_ON_OOPS 810 bool "Panic on Oops" 811 help 812 Say Y here to enable the kernel to panic when it oopses. This 813 has the same effect as setting oops=panic on the kernel command 814 line. 815 816 This feature is useful to ensure that the kernel does not do 817 anything erroneous after an oops which could result in data 818 corruption or other issues. 819 820 Say N if unsure. 821 822config PANIC_ON_OOPS_VALUE 823 int 824 range 0 1 825 default 0 if !PANIC_ON_OOPS 826 default 1 if PANIC_ON_OOPS 827 828config PANIC_TIMEOUT 829 int "panic timeout" 830 default 0 831 help 832 Set the timeout value (in seconds) until a reboot occurs when the 833 the kernel panics. If n = 0, then we wait forever. A timeout 834 value n > 0 will wait n seconds before rebooting, while a timeout 835 value n < 0 will reboot immediately. 836 837config LOCKUP_DETECTOR 838 bool 839 840config SOFTLOCKUP_DETECTOR 841 bool "Detect Soft Lockups" 842 depends on DEBUG_KERNEL && !S390 843 select LOCKUP_DETECTOR 844 help 845 Say Y here to enable the kernel to act as a watchdog to detect 846 soft lockups. 847 848 Softlockups are bugs that cause the kernel to loop in kernel 849 mode for more than 20 seconds, without giving other tasks a 850 chance to run. The current stack trace is displayed upon 851 detection and the system will stay locked up. 852 853config BOOTPARAM_SOFTLOCKUP_PANIC 854 bool "Panic (Reboot) On Soft Lockups" 855 depends on SOFTLOCKUP_DETECTOR 856 help 857 Say Y here to enable the kernel to panic on "soft lockups", 858 which are bugs that cause the kernel to loop in kernel 859 mode for more than 20 seconds (configurable using the watchdog_thresh 860 sysctl), without giving other tasks a chance to run. 861 862 The panic can be used in combination with panic_timeout, 863 to cause the system to reboot automatically after a 864 lockup has been detected. This feature is useful for 865 high-availability systems that have uptime guarantees and 866 where a lockup must be resolved ASAP. 867 868 Say N if unsure. 869 870config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE 871 int 872 depends on SOFTLOCKUP_DETECTOR 873 range 0 1 874 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC 875 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC 876 877config HARDLOCKUP_DETECTOR_PERF 878 bool 879 select SOFTLOCKUP_DETECTOR 880 881# 882# Enables a timestamp based low pass filter to compensate for perf based 883# hard lockup detection which runs too fast due to turbo modes. 884# 885config HARDLOCKUP_CHECK_TIMESTAMP 886 bool 887 888# 889# arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard 890# lockup detector rather than the perf based detector. 891# 892config HARDLOCKUP_DETECTOR 893 bool "Detect Hard Lockups" 894 depends on DEBUG_KERNEL && !S390 895 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH 896 select LOCKUP_DETECTOR 897 select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF 898 select HARDLOCKUP_DETECTOR_ARCH if HAVE_HARDLOCKUP_DETECTOR_ARCH 899 help 900 Say Y here to enable the kernel to act as a watchdog to detect 901 hard lockups. 902 903 Hardlockups are bugs that cause the CPU to loop in kernel mode 904 for more than 10 seconds, without letting other interrupts have a 905 chance to run. The current stack trace is displayed upon detection 906 and the system will stay locked up. 907 908config BOOTPARAM_HARDLOCKUP_PANIC 909 bool "Panic (Reboot) On Hard Lockups" 910 depends on HARDLOCKUP_DETECTOR 911 help 912 Say Y here to enable the kernel to panic on "hard lockups", 913 which are bugs that cause the kernel to loop in kernel 914 mode with interrupts disabled for more than 10 seconds (configurable 915 using the watchdog_thresh sysctl). 916 917 Say N if unsure. 918 919config BOOTPARAM_HARDLOCKUP_PANIC_VALUE 920 int 921 depends on HARDLOCKUP_DETECTOR 922 range 0 1 923 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC 924 default 1 if BOOTPARAM_HARDLOCKUP_PANIC 925 926config DETECT_HUNG_TASK 927 bool "Detect Hung Tasks" 928 depends on DEBUG_KERNEL 929 default SOFTLOCKUP_DETECTOR 930 help 931 Say Y here to enable the kernel to detect "hung tasks", 932 which are bugs that cause the task to be stuck in 933 uninterruptible "D" state indefinitely. 934 935 When a hung task is detected, the kernel will print the 936 current stack trace (which you should report), but the 937 task will stay in uninterruptible state. If lockdep is 938 enabled then all held locks will also be reported. This 939 feature has negligible overhead. 940 941config DEFAULT_HUNG_TASK_TIMEOUT 942 int "Default timeout for hung task detection (in seconds)" 943 depends on DETECT_HUNG_TASK 944 default 120 945 help 946 This option controls the default timeout (in seconds) used 947 to determine when a task has become non-responsive and should 948 be considered hung. 949 950 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 951 sysctl or by writing a value to 952 /proc/sys/kernel/hung_task_timeout_secs. 953 954 A timeout of 0 disables the check. The default is two minutes. 955 Keeping the default should be fine in most cases. 956 957config BOOTPARAM_HUNG_TASK_PANIC 958 bool "Panic (Reboot) On Hung Tasks" 959 depends on DETECT_HUNG_TASK 960 help 961 Say Y here to enable the kernel to panic on "hung tasks", 962 which are bugs that cause the kernel to leave a task stuck 963 in uninterruptible "D" state. 964 965 The panic can be used in combination with panic_timeout, 966 to cause the system to reboot automatically after a 967 hung task has been detected. This feature is useful for 968 high-availability systems that have uptime guarantees and 969 where a hung tasks must be resolved ASAP. 970 971 Say N if unsure. 972 973config BOOTPARAM_HUNG_TASK_PANIC_VALUE 974 int 975 depends on DETECT_HUNG_TASK 976 range 0 1 977 default 0 if !BOOTPARAM_HUNG_TASK_PANIC 978 default 1 if BOOTPARAM_HUNG_TASK_PANIC 979 980config WQ_WATCHDOG 981 bool "Detect Workqueue Stalls" 982 depends on DEBUG_KERNEL 983 help 984 Say Y here to enable stall detection on workqueues. If a 985 worker pool doesn't make forward progress on a pending work 986 item for over a given amount of time, 30s by default, a 987 warning message is printed along with dump of workqueue 988 state. This can be configured through kernel parameter 989 "workqueue.watchdog_thresh" and its sysfs counterpart. 990 991endmenu # "Debug lockups and hangs" 992 993menu "Scheduler Debugging" 994 995config SCHED_DEBUG 996 bool "Collect scheduler debugging info" 997 depends on DEBUG_KERNEL && PROC_FS 998 default y 999 help 1000 If you say Y here, the /proc/sched_debug file will be provided 1001 that can help debug the scheduler. The runtime overhead of this 1002 option is minimal. 1003 1004config SCHED_INFO 1005 bool 1006 default n 1007 1008config SCHEDSTATS 1009 bool "Collect scheduler statistics" 1010 depends on DEBUG_KERNEL && PROC_FS 1011 select SCHED_INFO 1012 help 1013 If you say Y here, additional code will be inserted into the 1014 scheduler and related routines to collect statistics about 1015 scheduler behavior and provide them in /proc/schedstat. These 1016 stats may be useful for both tuning and debugging the scheduler 1017 If you aren't debugging the scheduler or trying to tune a specific 1018 application, you can say N to avoid the very slight overhead 1019 this adds. 1020 1021endmenu 1022 1023config DEBUG_TIMEKEEPING 1024 bool "Enable extra timekeeping sanity checking" 1025 help 1026 This option will enable additional timekeeping sanity checks 1027 which may be helpful when diagnosing issues where timekeeping 1028 problems are suspected. 1029 1030 This may include checks in the timekeeping hotpaths, so this 1031 option may have a (very small) performance impact to some 1032 workloads. 1033 1034 If unsure, say N. 1035 1036config DEBUG_PREEMPT 1037 bool "Debug preemptible kernel" 1038 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1039 default y 1040 help 1041 If you say Y here then the kernel will use a debug variant of the 1042 commonly used smp_processor_id() function and will print warnings 1043 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1044 will detect preemption count underflows. 1045 1046menu "Lock Debugging (spinlocks, mutexes, etc...)" 1047 1048config LOCK_DEBUGGING_SUPPORT 1049 bool 1050 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1051 default y 1052 1053config PROVE_LOCKING 1054 bool "Lock debugging: prove locking correctness" 1055 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1056 select LOCKDEP 1057 select DEBUG_SPINLOCK 1058 select DEBUG_MUTEXES 1059 select DEBUG_RT_MUTEXES if RT_MUTEXES 1060 select DEBUG_RWSEMS 1061 select DEBUG_WW_MUTEX_SLOWPATH 1062 select DEBUG_LOCK_ALLOC 1063 select TRACE_IRQFLAGS 1064 default n 1065 help 1066 This feature enables the kernel to prove that all locking 1067 that occurs in the kernel runtime is mathematically 1068 correct: that under no circumstance could an arbitrary (and 1069 not yet triggered) combination of observed locking 1070 sequences (on an arbitrary number of CPUs, running an 1071 arbitrary number of tasks and interrupt contexts) cause a 1072 deadlock. 1073 1074 In short, this feature enables the kernel to report locking 1075 related deadlocks before they actually occur. 1076 1077 The proof does not depend on how hard and complex a 1078 deadlock scenario would be to trigger: how many 1079 participant CPUs, tasks and irq-contexts would be needed 1080 for it to trigger. The proof also does not depend on 1081 timing: if a race and a resulting deadlock is possible 1082 theoretically (no matter how unlikely the race scenario 1083 is), it will be proven so and will immediately be 1084 reported by the kernel (once the event is observed that 1085 makes the deadlock theoretically possible). 1086 1087 If a deadlock is impossible (i.e. the locking rules, as 1088 observed by the kernel, are mathematically correct), the 1089 kernel reports nothing. 1090 1091 NOTE: this feature can also be enabled for rwlocks, mutexes 1092 and rwsems - in which case all dependencies between these 1093 different locking variants are observed and mapped too, and 1094 the proof of observed correctness is also maintained for an 1095 arbitrary combination of these separate locking variants. 1096 1097 For more details, see Documentation/locking/lockdep-design.rst. 1098 1099config PROVE_RAW_LOCK_NESTING 1100 bool "Enable raw_spinlock - spinlock nesting checks" 1101 depends on PROVE_LOCKING 1102 default n 1103 help 1104 Enable the raw_spinlock vs. spinlock nesting checks which ensure 1105 that the lock nesting rules for PREEMPT_RT enabled kernels are 1106 not violated. 1107 1108 NOTE: There are known nesting problems. So if you enable this 1109 option expect lockdep splats until these problems have been fully 1110 addressed which is work in progress. This config switch allows to 1111 identify and analyze these problems. It will be removed and the 1112 check permanentely enabled once the main issues have been fixed. 1113 1114 If unsure, select N. 1115 1116config LOCK_STAT 1117 bool "Lock usage statistics" 1118 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1119 select LOCKDEP 1120 select DEBUG_SPINLOCK 1121 select DEBUG_MUTEXES 1122 select DEBUG_RT_MUTEXES if RT_MUTEXES 1123 select DEBUG_LOCK_ALLOC 1124 default n 1125 help 1126 This feature enables tracking lock contention points 1127 1128 For more details, see Documentation/locking/lockstat.rst 1129 1130 This also enables lock events required by "perf lock", 1131 subcommand of perf. 1132 If you want to use "perf lock", you also need to turn on 1133 CONFIG_EVENT_TRACING. 1134 1135 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1136 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1137 1138config DEBUG_RT_MUTEXES 1139 bool "RT Mutex debugging, deadlock detection" 1140 depends on DEBUG_KERNEL && RT_MUTEXES 1141 help 1142 This allows rt mutex semantics violations and rt mutex related 1143 deadlocks (lockups) to be detected and reported automatically. 1144 1145config DEBUG_SPINLOCK 1146 bool "Spinlock and rw-lock debugging: basic checks" 1147 depends on DEBUG_KERNEL 1148 select UNINLINE_SPIN_UNLOCK 1149 help 1150 Say Y here and build SMP to catch missing spinlock initialization 1151 and certain other kinds of spinlock errors commonly made. This is 1152 best used in conjunction with the NMI watchdog so that spinlock 1153 deadlocks are also debuggable. 1154 1155config DEBUG_MUTEXES 1156 bool "Mutex debugging: basic checks" 1157 depends on DEBUG_KERNEL 1158 help 1159 This feature allows mutex semantics violations to be detected and 1160 reported. 1161 1162config DEBUG_WW_MUTEX_SLOWPATH 1163 bool "Wait/wound mutex debugging: Slowpath testing" 1164 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1165 select DEBUG_LOCK_ALLOC 1166 select DEBUG_SPINLOCK 1167 select DEBUG_MUTEXES 1168 help 1169 This feature enables slowpath testing for w/w mutex users by 1170 injecting additional -EDEADLK wound/backoff cases. Together with 1171 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1172 will test all possible w/w mutex interface abuse with the 1173 exception of simply not acquiring all the required locks. 1174 Note that this feature can introduce significant overhead, so 1175 it really should not be enabled in a production or distro kernel, 1176 even a debug kernel. If you are a driver writer, enable it. If 1177 you are a distro, do not. 1178 1179config DEBUG_RWSEMS 1180 bool "RW Semaphore debugging: basic checks" 1181 depends on DEBUG_KERNEL 1182 help 1183 This debugging feature allows mismatched rw semaphore locks 1184 and unlocks to be detected and reported. 1185 1186config DEBUG_LOCK_ALLOC 1187 bool "Lock debugging: detect incorrect freeing of live locks" 1188 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1189 select DEBUG_SPINLOCK 1190 select DEBUG_MUTEXES 1191 select DEBUG_RT_MUTEXES if RT_MUTEXES 1192 select LOCKDEP 1193 help 1194 This feature will check whether any held lock (spinlock, rwlock, 1195 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1196 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1197 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1198 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1199 held during task exit. 1200 1201config LOCKDEP 1202 bool 1203 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1204 select STACKTRACE 1205 select FRAME_POINTER if !MIPS && !PPC && !ARM && !S390 && !MICROBLAZE && !ARC && !X86 1206 select KALLSYMS 1207 select KALLSYMS_ALL 1208 1209config LOCKDEP_SMALL 1210 bool 1211 1212config DEBUG_LOCKDEP 1213 bool "Lock dependency engine debugging" 1214 depends on DEBUG_KERNEL && LOCKDEP 1215 help 1216 If you say Y here, the lock dependency engine will do 1217 additional runtime checks to debug itself, at the price 1218 of more runtime overhead. 1219 1220config DEBUG_ATOMIC_SLEEP 1221 bool "Sleep inside atomic section checking" 1222 select PREEMPT_COUNT 1223 depends on DEBUG_KERNEL 1224 depends on !ARCH_NO_PREEMPT 1225 help 1226 If you say Y here, various routines which may sleep will become very 1227 noisy if they are called inside atomic sections: when a spinlock is 1228 held, inside an rcu read side critical section, inside preempt disabled 1229 sections, inside an interrupt, etc... 1230 1231config DEBUG_LOCKING_API_SELFTESTS 1232 bool "Locking API boot-time self-tests" 1233 depends on DEBUG_KERNEL 1234 help 1235 Say Y here if you want the kernel to run a short self-test during 1236 bootup. The self-test checks whether common types of locking bugs 1237 are detected by debugging mechanisms or not. (if you disable 1238 lock debugging then those bugs wont be detected of course.) 1239 The following locking APIs are covered: spinlocks, rwlocks, 1240 mutexes and rwsems. 1241 1242config LOCK_TORTURE_TEST 1243 tristate "torture tests for locking" 1244 depends on DEBUG_KERNEL 1245 select TORTURE_TEST 1246 help 1247 This option provides a kernel module that runs torture tests 1248 on kernel locking primitives. The kernel module may be built 1249 after the fact on the running kernel to be tested, if desired. 1250 1251 Say Y here if you want kernel locking-primitive torture tests 1252 to be built into the kernel. 1253 Say M if you want these torture tests to build as a module. 1254 Say N if you are unsure. 1255 1256config WW_MUTEX_SELFTEST 1257 tristate "Wait/wound mutex selftests" 1258 help 1259 This option provides a kernel module that runs tests on the 1260 on the struct ww_mutex locking API. 1261 1262 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1263 with this test harness. 1264 1265 Say M if you want these self tests to build as a module. 1266 Say N if you are unsure. 1267 1268endmenu # lock debugging 1269 1270config TRACE_IRQFLAGS 1271 bool 1272 help 1273 Enables hooks to interrupt enabling and disabling for 1274 either tracing or lock debugging. 1275 1276config STACKTRACE 1277 bool "Stack backtrace support" 1278 depends on STACKTRACE_SUPPORT 1279 help 1280 This option causes the kernel to create a /proc/pid/stack for 1281 every process, showing its current stack trace. 1282 It is also used by various kernel debugging features that require 1283 stack trace generation. 1284 1285config WARN_ALL_UNSEEDED_RANDOM 1286 bool "Warn for all uses of unseeded randomness" 1287 default n 1288 help 1289 Some parts of the kernel contain bugs relating to their use of 1290 cryptographically secure random numbers before it's actually possible 1291 to generate those numbers securely. This setting ensures that these 1292 flaws don't go unnoticed, by enabling a message, should this ever 1293 occur. This will allow people with obscure setups to know when things 1294 are going wrong, so that they might contact developers about fixing 1295 it. 1296 1297 Unfortunately, on some models of some architectures getting 1298 a fully seeded CRNG is extremely difficult, and so this can 1299 result in dmesg getting spammed for a surprisingly long 1300 time. This is really bad from a security perspective, and 1301 so architecture maintainers really need to do what they can 1302 to get the CRNG seeded sooner after the system is booted. 1303 However, since users cannot do anything actionable to 1304 address this, by default the kernel will issue only a single 1305 warning for the first use of unseeded randomness. 1306 1307 Say Y here if you want to receive warnings for all uses of 1308 unseeded randomness. This will be of use primarily for 1309 those developers interested in improving the security of 1310 Linux kernels running on their architecture (or 1311 subarchitecture). 1312 1313config DEBUG_KOBJECT 1314 bool "kobject debugging" 1315 depends on DEBUG_KERNEL 1316 help 1317 If you say Y here, some extra kobject debugging messages will be sent 1318 to the syslog. 1319 1320config DEBUG_KOBJECT_RELEASE 1321 bool "kobject release debugging" 1322 depends on DEBUG_OBJECTS_TIMERS 1323 help 1324 kobjects are reference counted objects. This means that their 1325 last reference count put is not predictable, and the kobject can 1326 live on past the point at which a driver decides to drop it's 1327 initial reference to the kobject gained on allocation. An 1328 example of this would be a struct device which has just been 1329 unregistered. 1330 1331 However, some buggy drivers assume that after such an operation, 1332 the memory backing the kobject can be immediately freed. This 1333 goes completely against the principles of a refcounted object. 1334 1335 If you say Y here, the kernel will delay the release of kobjects 1336 on the last reference count to improve the visibility of this 1337 kind of kobject release bug. 1338 1339config HAVE_DEBUG_BUGVERBOSE 1340 bool 1341 1342menu "Debug kernel data structures" 1343 1344config DEBUG_LIST 1345 bool "Debug linked list manipulation" 1346 depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION 1347 help 1348 Enable this to turn on extended checks in the linked-list 1349 walking routines. 1350 1351 If unsure, say N. 1352 1353config DEBUG_PLIST 1354 bool "Debug priority linked list manipulation" 1355 depends on DEBUG_KERNEL 1356 help 1357 Enable this to turn on extended checks in the priority-ordered 1358 linked-list (plist) walking routines. This checks the entire 1359 list multiple times during each manipulation. 1360 1361 If unsure, say N. 1362 1363config DEBUG_SG 1364 bool "Debug SG table operations" 1365 depends on DEBUG_KERNEL 1366 help 1367 Enable this to turn on checks on scatter-gather tables. This can 1368 help find problems with drivers that do not properly initialize 1369 their sg tables. 1370 1371 If unsure, say N. 1372 1373config DEBUG_NOTIFIERS 1374 bool "Debug notifier call chains" 1375 depends on DEBUG_KERNEL 1376 help 1377 Enable this to turn on sanity checking for notifier call chains. 1378 This is most useful for kernel developers to make sure that 1379 modules properly unregister themselves from notifier chains. 1380 This is a relatively cheap check but if you care about maximum 1381 performance, say N. 1382 1383config BUG_ON_DATA_CORRUPTION 1384 bool "Trigger a BUG when data corruption is detected" 1385 select DEBUG_LIST 1386 help 1387 Select this option if the kernel should BUG when it encounters 1388 data corruption in kernel memory structures when they get checked 1389 for validity. 1390 1391 If unsure, say N. 1392 1393endmenu 1394 1395config DEBUG_CREDENTIALS 1396 bool "Debug credential management" 1397 depends on DEBUG_KERNEL 1398 help 1399 Enable this to turn on some debug checking for credential 1400 management. The additional code keeps track of the number of 1401 pointers from task_structs to any given cred struct, and checks to 1402 see that this number never exceeds the usage count of the cred 1403 struct. 1404 1405 Furthermore, if SELinux is enabled, this also checks that the 1406 security pointer in the cred struct is never seen to be invalid. 1407 1408 If unsure, say N. 1409 1410source "kernel/rcu/Kconfig.debug" 1411 1412config DEBUG_WQ_FORCE_RR_CPU 1413 bool "Force round-robin CPU selection for unbound work items" 1414 depends on DEBUG_KERNEL 1415 default n 1416 help 1417 Workqueue used to implicitly guarantee that work items queued 1418 without explicit CPU specified are put on the local CPU. This 1419 guarantee is no longer true and while local CPU is still 1420 preferred work items may be put on foreign CPUs. Kernel 1421 parameter "workqueue.debug_force_rr_cpu" is added to force 1422 round-robin CPU selection to flush out usages which depend on the 1423 now broken guarantee. This config option enables the debug 1424 feature by default. When enabled, memory and cache locality will 1425 be impacted. 1426 1427config DEBUG_BLOCK_EXT_DEVT 1428 bool "Force extended block device numbers and spread them" 1429 depends on DEBUG_KERNEL 1430 depends on BLOCK 1431 default n 1432 help 1433 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON 1434 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT 1435 YOU ARE DOING. Distros, please enable this and fix whatever 1436 is broken. 1437 1438 Conventionally, block device numbers are allocated from 1439 predetermined contiguous area. However, extended block area 1440 may introduce non-contiguous block device numbers. This 1441 option forces most block device numbers to be allocated from 1442 the extended space and spreads them to discover kernel or 1443 userland code paths which assume predetermined contiguous 1444 device number allocation. 1445 1446 Note that turning on this debug option shuffles all the 1447 device numbers for all IDE and SCSI devices including libata 1448 ones, so root partition specified using device number 1449 directly (via rdev or root=MAJ:MIN) won't work anymore. 1450 Textual device names (root=/dev/sdXn) will continue to work. 1451 1452 Say N if you are unsure. 1453 1454config CPU_HOTPLUG_STATE_CONTROL 1455 bool "Enable CPU hotplug state control" 1456 depends on DEBUG_KERNEL 1457 depends on HOTPLUG_CPU 1458 default n 1459 help 1460 Allows to write steps between "offline" and "online" to the CPUs 1461 sysfs target file so states can be stepped granular. This is a debug 1462 option for now as the hotplug machinery cannot be stopped and 1463 restarted at arbitrary points yet. 1464 1465 Say N if your are unsure. 1466 1467config LATENCYTOP 1468 bool "Latency measuring infrastructure" 1469 depends on DEBUG_KERNEL 1470 depends on STACKTRACE_SUPPORT 1471 depends on PROC_FS 1472 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86 1473 select KALLSYMS 1474 select KALLSYMS_ALL 1475 select STACKTRACE 1476 select SCHEDSTATS 1477 select SCHED_DEBUG 1478 help 1479 Enable this option if you want to use the LatencyTOP tool 1480 to find out which userspace is blocking on what kernel operations. 1481 1482source "kernel/trace/Kconfig" 1483 1484config PROVIDE_OHCI1394_DMA_INIT 1485 bool "Remote debugging over FireWire early on boot" 1486 depends on PCI && X86 1487 help 1488 If you want to debug problems which hang or crash the kernel early 1489 on boot and the crashing machine has a FireWire port, you can use 1490 this feature to remotely access the memory of the crashed machine 1491 over FireWire. This employs remote DMA as part of the OHCI1394 1492 specification which is now the standard for FireWire controllers. 1493 1494 With remote DMA, you can monitor the printk buffer remotely using 1495 firescope and access all memory below 4GB using fireproxy from gdb. 1496 Even controlling a kernel debugger is possible using remote DMA. 1497 1498 Usage: 1499 1500 If ohci1394_dma=early is used as boot parameter, it will initialize 1501 all OHCI1394 controllers which are found in the PCI config space. 1502 1503 As all changes to the FireWire bus such as enabling and disabling 1504 devices cause a bus reset and thereby disable remote DMA for all 1505 devices, be sure to have the cable plugged and FireWire enabled on 1506 the debugging host before booting the debug target for debugging. 1507 1508 This code (~1k) is freed after boot. By then, the firewire stack 1509 in charge of the OHCI-1394 controllers should be used instead. 1510 1511 See Documentation/debugging-via-ohci1394.txt for more information. 1512 1513source "samples/Kconfig" 1514 1515config ARCH_HAS_DEVMEM_IS_ALLOWED 1516 bool 1517 1518config STRICT_DEVMEM 1519 bool "Filter access to /dev/mem" 1520 depends on MMU && DEVMEM 1521 depends on ARCH_HAS_DEVMEM_IS_ALLOWED 1522 default y if PPC || X86 || ARM64 1523 help 1524 If this option is disabled, you allow userspace (root) access to all 1525 of memory, including kernel and userspace memory. Accidental 1526 access to this is obviously disastrous, but specific access can 1527 be used by people debugging the kernel. Note that with PAT support 1528 enabled, even in this case there are restrictions on /dev/mem 1529 use due to the cache aliasing requirements. 1530 1531 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 1532 file only allows userspace access to PCI space and the BIOS code and 1533 data regions. This is sufficient for dosemu and X and all common 1534 users of /dev/mem. 1535 1536 If in doubt, say Y. 1537 1538config IO_STRICT_DEVMEM 1539 bool "Filter I/O access to /dev/mem" 1540 depends on STRICT_DEVMEM 1541 help 1542 If this option is disabled, you allow userspace (root) access to all 1543 io-memory regardless of whether a driver is actively using that 1544 range. Accidental access to this is obviously disastrous, but 1545 specific access can be used by people debugging kernel drivers. 1546 1547 If this option is switched on, the /dev/mem file only allows 1548 userspace access to *idle* io-memory ranges (see /proc/iomem) This 1549 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 1550 if the driver using a given range cannot be disabled. 1551 1552 If in doubt, say Y. 1553 1554menu "$(SRCARCH) Debugging" 1555 1556source "arch/$(SRCARCH)/Kconfig.debug" 1557 1558endmenu 1559 1560menu "Kernel Testing and Coverage" 1561 1562source "lib/kunit/Kconfig" 1563 1564config NOTIFIER_ERROR_INJECTION 1565 tristate "Notifier error injection" 1566 depends on DEBUG_KERNEL 1567 select DEBUG_FS 1568 help 1569 This option provides the ability to inject artificial errors to 1570 specified notifier chain callbacks. It is useful to test the error 1571 handling of notifier call chain failures. 1572 1573 Say N if unsure. 1574 1575config PM_NOTIFIER_ERROR_INJECT 1576 tristate "PM notifier error injection module" 1577 depends on PM && NOTIFIER_ERROR_INJECTION 1578 default m if PM_DEBUG 1579 help 1580 This option provides the ability to inject artificial errors to 1581 PM notifier chain callbacks. It is controlled through debugfs 1582 interface /sys/kernel/debug/notifier-error-inject/pm 1583 1584 If the notifier call chain should be failed with some events 1585 notified, write the error code to "actions/<notifier event>/error". 1586 1587 Example: Inject PM suspend error (-12 = -ENOMEM) 1588 1589 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1590 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1591 # echo mem > /sys/power/state 1592 bash: echo: write error: Cannot allocate memory 1593 1594 To compile this code as a module, choose M here: the module will 1595 be called pm-notifier-error-inject. 1596 1597 If unsure, say N. 1598 1599config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1600 tristate "OF reconfig notifier error injection module" 1601 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1602 help 1603 This option provides the ability to inject artificial errors to 1604 OF reconfig notifier chain callbacks. It is controlled 1605 through debugfs interface under 1606 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1607 1608 If the notifier call chain should be failed with some events 1609 notified, write the error code to "actions/<notifier event>/error". 1610 1611 To compile this code as a module, choose M here: the module will 1612 be called of-reconfig-notifier-error-inject. 1613 1614 If unsure, say N. 1615 1616config NETDEV_NOTIFIER_ERROR_INJECT 1617 tristate "Netdev notifier error injection module" 1618 depends on NET && NOTIFIER_ERROR_INJECTION 1619 help 1620 This option provides the ability to inject artificial errors to 1621 netdevice notifier chain callbacks. It is controlled through debugfs 1622 interface /sys/kernel/debug/notifier-error-inject/netdev 1623 1624 If the notifier call chain should be failed with some events 1625 notified, write the error code to "actions/<notifier event>/error". 1626 1627 Example: Inject netdevice mtu change error (-22 = -EINVAL) 1628 1629 # cd /sys/kernel/debug/notifier-error-inject/netdev 1630 # echo -22 > actions/NETDEV_CHANGEMTU/error 1631 # ip link set eth0 mtu 1024 1632 RTNETLINK answers: Invalid argument 1633 1634 To compile this code as a module, choose M here: the module will 1635 be called netdev-notifier-error-inject. 1636 1637 If unsure, say N. 1638 1639config FUNCTION_ERROR_INJECTION 1640 def_bool y 1641 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 1642 1643config FAULT_INJECTION 1644 bool "Fault-injection framework" 1645 depends on DEBUG_KERNEL 1646 help 1647 Provide fault-injection framework. 1648 For more details, see Documentation/fault-injection/. 1649 1650config FAILSLAB 1651 bool "Fault-injection capability for kmalloc" 1652 depends on FAULT_INJECTION 1653 depends on SLAB || SLUB 1654 help 1655 Provide fault-injection capability for kmalloc. 1656 1657config FAIL_PAGE_ALLOC 1658 bool "Fault-injection capabilitiy for alloc_pages()" 1659 depends on FAULT_INJECTION 1660 help 1661 Provide fault-injection capability for alloc_pages(). 1662 1663config FAIL_MAKE_REQUEST 1664 bool "Fault-injection capability for disk IO" 1665 depends on FAULT_INJECTION && BLOCK 1666 help 1667 Provide fault-injection capability for disk IO. 1668 1669config FAIL_IO_TIMEOUT 1670 bool "Fault-injection capability for faking disk interrupts" 1671 depends on FAULT_INJECTION && BLOCK 1672 help 1673 Provide fault-injection capability on end IO handling. This 1674 will make the block layer "forget" an interrupt as configured, 1675 thus exercising the error handling. 1676 1677 Only works with drivers that use the generic timeout handling, 1678 for others it wont do anything. 1679 1680config FAIL_FUTEX 1681 bool "Fault-injection capability for futexes" 1682 select DEBUG_FS 1683 depends on FAULT_INJECTION && FUTEX 1684 help 1685 Provide fault-injection capability for futexes. 1686 1687config FAULT_INJECTION_DEBUG_FS 1688 bool "Debugfs entries for fault-injection capabilities" 1689 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 1690 help 1691 Enable configuration of fault-injection capabilities via debugfs. 1692 1693config FAIL_FUNCTION 1694 bool "Fault-injection capability for functions" 1695 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 1696 help 1697 Provide function-based fault-injection capability. 1698 This will allow you to override a specific function with a return 1699 with given return value. As a result, function caller will see 1700 an error value and have to handle it. This is useful to test the 1701 error handling in various subsystems. 1702 1703config FAIL_MMC_REQUEST 1704 bool "Fault-injection capability for MMC IO" 1705 depends on FAULT_INJECTION_DEBUG_FS && MMC 1706 help 1707 Provide fault-injection capability for MMC IO. 1708 This will make the mmc core return data errors. This is 1709 useful to test the error handling in the mmc block device 1710 and to test how the mmc host driver handles retries from 1711 the block device. 1712 1713config FAULT_INJECTION_STACKTRACE_FILTER 1714 bool "stacktrace filter for fault-injection capabilities" 1715 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 1716 depends on !X86_64 1717 select STACKTRACE 1718 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86 1719 help 1720 Provide stacktrace filter for fault-injection capabilities 1721 1722config ARCH_HAS_KCOV 1723 bool 1724 help 1725 An architecture should select this when it can successfully 1726 build and run with CONFIG_KCOV. This typically requires 1727 disabling instrumentation for some early boot code. 1728 1729config CC_HAS_SANCOV_TRACE_PC 1730 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 1731 1732 1733config KCOV 1734 bool "Code coverage for fuzzing" 1735 depends on ARCH_HAS_KCOV 1736 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 1737 select DEBUG_FS 1738 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 1739 help 1740 KCOV exposes kernel code coverage information in a form suitable 1741 for coverage-guided fuzzing (randomized testing). 1742 1743 If RANDOMIZE_BASE is enabled, PC values will not be stable across 1744 different machines and across reboots. If you need stable PC values, 1745 disable RANDOMIZE_BASE. 1746 1747 For more details, see Documentation/dev-tools/kcov.rst. 1748 1749config KCOV_ENABLE_COMPARISONS 1750 bool "Enable comparison operands collection by KCOV" 1751 depends on KCOV 1752 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 1753 help 1754 KCOV also exposes operands of every comparison in the instrumented 1755 code along with operand sizes and PCs of the comparison instructions. 1756 These operands can be used by fuzzing engines to improve the quality 1757 of fuzzing coverage. 1758 1759config KCOV_INSTRUMENT_ALL 1760 bool "Instrument all code by default" 1761 depends on KCOV 1762 default y 1763 help 1764 If you are doing generic system call fuzzing (like e.g. syzkaller), 1765 then you will want to instrument the whole kernel and you should 1766 say y here. If you are doing more targeted fuzzing (like e.g. 1767 filesystem fuzzing with AFL) then you will want to enable coverage 1768 for more specific subsets of files, and should say n here. 1769 1770menuconfig RUNTIME_TESTING_MENU 1771 bool "Runtime Testing" 1772 def_bool y 1773 1774if RUNTIME_TESTING_MENU 1775 1776config LKDTM 1777 tristate "Linux Kernel Dump Test Tool Module" 1778 depends on DEBUG_FS 1779 help 1780 This module enables testing of the different dumping mechanisms by 1781 inducing system failures at predefined crash points. 1782 If you don't need it: say N 1783 Choose M here to compile this code as a module. The module will be 1784 called lkdtm. 1785 1786 Documentation on how to use the module can be found in 1787 Documentation/fault-injection/provoke-crashes.rst 1788 1789config TEST_LIST_SORT 1790 tristate "Linked list sorting test" 1791 depends on DEBUG_KERNEL || m 1792 help 1793 Enable this to turn on 'list_sort()' function test. This test is 1794 executed only once during system boot (so affects only boot time), 1795 or at module load time. 1796 1797 If unsure, say N. 1798 1799config TEST_MIN_HEAP 1800 tristate "Min heap test" 1801 depends on DEBUG_KERNEL || m 1802 help 1803 Enable this to turn on min heap function tests. This test is 1804 executed only once during system boot (so affects only boot time), 1805 or at module load time. 1806 1807 If unsure, say N. 1808 1809config TEST_SORT 1810 tristate "Array-based sort test" 1811 depends on DEBUG_KERNEL || m 1812 help 1813 This option enables the self-test function of 'sort()' at boot, 1814 or at module load time. 1815 1816 If unsure, say N. 1817 1818config KPROBES_SANITY_TEST 1819 bool "Kprobes sanity tests" 1820 depends on DEBUG_KERNEL 1821 depends on KPROBES 1822 help 1823 This option provides for testing basic kprobes functionality on 1824 boot. Samples of kprobe and kretprobe are inserted and 1825 verified for functionality. 1826 1827 Say N if you are unsure. 1828 1829config BACKTRACE_SELF_TEST 1830 tristate "Self test for the backtrace code" 1831 depends on DEBUG_KERNEL 1832 help 1833 This option provides a kernel module that can be used to test 1834 the kernel stack backtrace code. This option is not useful 1835 for distributions or general kernels, but only for kernel 1836 developers working on architecture code. 1837 1838 Note that if you want to also test saved backtraces, you will 1839 have to enable STACKTRACE as well. 1840 1841 Say N if you are unsure. 1842 1843config RBTREE_TEST 1844 tristate "Red-Black tree test" 1845 depends on DEBUG_KERNEL 1846 help 1847 A benchmark measuring the performance of the rbtree library. 1848 Also includes rbtree invariant checks. 1849 1850config REED_SOLOMON_TEST 1851 tristate "Reed-Solomon library test" 1852 depends on DEBUG_KERNEL || m 1853 select REED_SOLOMON 1854 select REED_SOLOMON_ENC16 1855 select REED_SOLOMON_DEC16 1856 help 1857 This option enables the self-test function of rslib at boot, 1858 or at module load time. 1859 1860 If unsure, say N. 1861 1862config INTERVAL_TREE_TEST 1863 tristate "Interval tree test" 1864 depends on DEBUG_KERNEL 1865 select INTERVAL_TREE 1866 help 1867 A benchmark measuring the performance of the interval tree library 1868 1869config PERCPU_TEST 1870 tristate "Per cpu operations test" 1871 depends on m && DEBUG_KERNEL 1872 help 1873 Enable this option to build test module which validates per-cpu 1874 operations. 1875 1876 If unsure, say N. 1877 1878config ATOMIC64_SELFTEST 1879 tristate "Perform an atomic64_t self-test" 1880 help 1881 Enable this option to test the atomic64_t functions at boot or 1882 at module load time. 1883 1884 If unsure, say N. 1885 1886config ASYNC_RAID6_TEST 1887 tristate "Self test for hardware accelerated raid6 recovery" 1888 depends on ASYNC_RAID6_RECOV 1889 select ASYNC_MEMCPY 1890 ---help--- 1891 This is a one-shot self test that permutes through the 1892 recovery of all the possible two disk failure scenarios for a 1893 N-disk array. Recovery is performed with the asynchronous 1894 raid6 recovery routines, and will optionally use an offload 1895 engine if one is available. 1896 1897 If unsure, say N. 1898 1899config TEST_HEXDUMP 1900 tristate "Test functions located in the hexdump module at runtime" 1901 1902config TEST_STRING_HELPERS 1903 tristate "Test functions located in the string_helpers module at runtime" 1904 1905config TEST_STRSCPY 1906 tristate "Test strscpy*() family of functions at runtime" 1907 1908config TEST_KSTRTOX 1909 tristate "Test kstrto*() family of functions at runtime" 1910 1911config TEST_PRINTF 1912 tristate "Test printf() family of functions at runtime" 1913 1914config TEST_BITMAP 1915 tristate "Test bitmap_*() family of functions at runtime" 1916 help 1917 Enable this option to test the bitmap functions at boot. 1918 1919 If unsure, say N. 1920 1921config TEST_BITFIELD 1922 tristate "Test bitfield functions at runtime" 1923 help 1924 Enable this option to test the bitfield functions at boot. 1925 1926 If unsure, say N. 1927 1928config TEST_UUID 1929 tristate "Test functions located in the uuid module at runtime" 1930 1931config TEST_XARRAY 1932 tristate "Test the XArray code at runtime" 1933 1934config TEST_OVERFLOW 1935 tristate "Test check_*_overflow() functions at runtime" 1936 1937config TEST_RHASHTABLE 1938 tristate "Perform selftest on resizable hash table" 1939 help 1940 Enable this option to test the rhashtable functions at boot. 1941 1942 If unsure, say N. 1943 1944config TEST_HASH 1945 tristate "Perform selftest on hash functions" 1946 help 1947 Enable this option to test the kernel's integer (<linux/hash.h>), 1948 string (<linux/stringhash.h>), and siphash (<linux/siphash.h>) 1949 hash functions on boot (or module load). 1950 1951 This is intended to help people writing architecture-specific 1952 optimized versions. If unsure, say N. 1953 1954config TEST_IDA 1955 tristate "Perform selftest on IDA functions" 1956 1957config TEST_PARMAN 1958 tristate "Perform selftest on priority array manager" 1959 depends on PARMAN 1960 help 1961 Enable this option to test priority array manager on boot 1962 (or module load). 1963 1964 If unsure, say N. 1965 1966config TEST_IRQ_TIMINGS 1967 bool "IRQ timings selftest" 1968 depends on IRQ_TIMINGS 1969 help 1970 Enable this option to test the irq timings code on boot. 1971 1972 If unsure, say N. 1973 1974config TEST_LKM 1975 tristate "Test module loading with 'hello world' module" 1976 depends on m 1977 help 1978 This builds the "test_module" module that emits "Hello, world" 1979 on printk when loaded. It is designed to be used for basic 1980 evaluation of the module loading subsystem (for example when 1981 validating module verification). It lacks any extra dependencies, 1982 and will not normally be loaded by the system unless explicitly 1983 requested by name. 1984 1985 If unsure, say N. 1986 1987config TEST_VMALLOC 1988 tristate "Test module for stress/performance analysis of vmalloc allocator" 1989 default n 1990 depends on MMU 1991 depends on m 1992 help 1993 This builds the "test_vmalloc" module that should be used for 1994 stress and performance analysis. So, any new change for vmalloc 1995 subsystem can be evaluated from performance and stability point 1996 of view. 1997 1998 If unsure, say N. 1999 2000config TEST_USER_COPY 2001 tristate "Test user/kernel boundary protections" 2002 depends on m 2003 help 2004 This builds the "test_user_copy" module that runs sanity checks 2005 on the copy_to/from_user infrastructure, making sure basic 2006 user/kernel boundary testing is working. If it fails to load, 2007 a regression has been detected in the user/kernel memory boundary 2008 protections. 2009 2010 If unsure, say N. 2011 2012config TEST_BPF 2013 tristate "Test BPF filter functionality" 2014 depends on m && NET 2015 help 2016 This builds the "test_bpf" module that runs various test vectors 2017 against the BPF interpreter or BPF JIT compiler depending on the 2018 current setting. This is in particular useful for BPF JIT compiler 2019 development, but also to run regression tests against changes in 2020 the interpreter code. It also enables test stubs for eBPF maps and 2021 verifier used by user space verifier testsuite. 2022 2023 If unsure, say N. 2024 2025config TEST_BLACKHOLE_DEV 2026 tristate "Test blackhole netdev functionality" 2027 depends on m && NET 2028 help 2029 This builds the "test_blackhole_dev" module that validates the 2030 data path through this blackhole netdev. 2031 2032 If unsure, say N. 2033 2034config FIND_BIT_BENCHMARK 2035 tristate "Test find_bit functions" 2036 help 2037 This builds the "test_find_bit" module that measure find_*_bit() 2038 functions performance. 2039 2040 If unsure, say N. 2041 2042config TEST_FIRMWARE 2043 tristate "Test firmware loading via userspace interface" 2044 depends on FW_LOADER 2045 help 2046 This builds the "test_firmware" module that creates a userspace 2047 interface for testing firmware loading. This can be used to 2048 control the triggering of firmware loading without needing an 2049 actual firmware-using device. The contents can be rechecked by 2050 userspace. 2051 2052 If unsure, say N. 2053 2054config TEST_SYSCTL 2055 tristate "sysctl test driver" 2056 depends on PROC_SYSCTL 2057 help 2058 This builds the "test_sysctl" module. This driver enables to test the 2059 proc sysctl interfaces available to drivers safely without affecting 2060 production knobs which might alter system functionality. 2061 2062 If unsure, say N. 2063 2064config SYSCTL_KUNIT_TEST 2065 tristate "KUnit test for sysctl" 2066 depends on KUNIT 2067 help 2068 This builds the proc sysctl unit test, which runs on boot. 2069 Tests the API contract and implementation correctness of sysctl. 2070 For more information on KUnit and unit tests in general please refer 2071 to the KUnit documentation in Documentation/dev-tools/kunit/. 2072 2073 If unsure, say N. 2074 2075config LIST_KUNIT_TEST 2076 tristate "KUnit Test for Kernel Linked-list structures" 2077 depends on KUNIT 2078 help 2079 This builds the linked list KUnit test suite. 2080 It tests that the API and basic functionality of the list_head type 2081 and associated macros. 2082 2083 KUnit tests run during boot and output the results to the debug log 2084 in TAP format (http://testanything.org/). Only useful for kernel devs 2085 running the KUnit test harness, and not intended for inclusion into a 2086 production build. 2087 2088 For more information on KUnit and unit tests in general please refer 2089 to the KUnit documentation in Documentation/dev-tools/kunit/. 2090 2091 If unsure, say N. 2092 2093config TEST_UDELAY 2094 tristate "udelay test driver" 2095 help 2096 This builds the "udelay_test" module that helps to make sure 2097 that udelay() is working properly. 2098 2099 If unsure, say N. 2100 2101config TEST_STATIC_KEYS 2102 tristate "Test static keys" 2103 depends on m 2104 help 2105 Test the static key interfaces. 2106 2107 If unsure, say N. 2108 2109config TEST_KMOD 2110 tristate "kmod stress tester" 2111 depends on m 2112 depends on NETDEVICES && NET_CORE && INET # for TUN 2113 depends on BLOCK 2114 select TEST_LKM 2115 select XFS_FS 2116 select TUN 2117 select BTRFS_FS 2118 help 2119 Test the kernel's module loading mechanism: kmod. kmod implements 2120 support to load modules using the Linux kernel's usermode helper. 2121 This test provides a series of tests against kmod. 2122 2123 Although technically you can either build test_kmod as a module or 2124 into the kernel we disallow building it into the kernel since 2125 it stress tests request_module() and this will very likely cause 2126 some issues by taking over precious threads available from other 2127 module load requests, ultimately this could be fatal. 2128 2129 To run tests run: 2130 2131 tools/testing/selftests/kmod/kmod.sh --help 2132 2133 If unsure, say N. 2134 2135config TEST_DEBUG_VIRTUAL 2136 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 2137 depends on DEBUG_VIRTUAL 2138 help 2139 Test the kernel's ability to detect incorrect calls to 2140 virt_to_phys() done against the non-linear part of the 2141 kernel's virtual address map. 2142 2143 If unsure, say N. 2144 2145config TEST_MEMCAT_P 2146 tristate "Test memcat_p() helper function" 2147 help 2148 Test the memcat_p() helper for correctly merging two 2149 pointer arrays together. 2150 2151 If unsure, say N. 2152 2153config TEST_LIVEPATCH 2154 tristate "Test livepatching" 2155 default n 2156 depends on DYNAMIC_DEBUG 2157 depends on LIVEPATCH 2158 depends on m 2159 help 2160 Test kernel livepatching features for correctness. The tests will 2161 load test modules that will be livepatched in various scenarios. 2162 2163 To run all the livepatching tests: 2164 2165 make -C tools/testing/selftests TARGETS=livepatch run_tests 2166 2167 Alternatively, individual tests may be invoked: 2168 2169 tools/testing/selftests/livepatch/test-callbacks.sh 2170 tools/testing/selftests/livepatch/test-livepatch.sh 2171 tools/testing/selftests/livepatch/test-shadow-vars.sh 2172 2173 If unsure, say N. 2174 2175config TEST_OBJAGG 2176 tristate "Perform selftest on object aggreration manager" 2177 default n 2178 depends on OBJAGG 2179 help 2180 Enable this option to test object aggregation manager on boot 2181 (or module load). 2182 2183 2184config TEST_STACKINIT 2185 tristate "Test level of stack variable initialization" 2186 help 2187 Test if the kernel is zero-initializing stack variables and 2188 padding. Coverage is controlled by compiler flags, 2189 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2190 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2191 2192 If unsure, say N. 2193 2194config TEST_MEMINIT 2195 tristate "Test heap/page initialization" 2196 help 2197 Test if the kernel is zero-initializing heap and page allocations. 2198 This can be useful to test init_on_alloc and init_on_free features. 2199 2200 If unsure, say N. 2201 2202endif # RUNTIME_TESTING_MENU 2203 2204config MEMTEST 2205 bool "Memtest" 2206 ---help--- 2207 This option adds a kernel parameter 'memtest', which allows memtest 2208 to be set. 2209 memtest=0, mean disabled; -- default 2210 memtest=1, mean do 1 test pattern; 2211 ... 2212 memtest=17, mean do 17 test patterns. 2213 If you are unsure how to answer this question, answer N. 2214 2215 2216 2217config HYPERV_TESTING 2218 bool "Microsoft Hyper-V driver testing" 2219 default n 2220 depends on HYPERV && DEBUG_FS 2221 help 2222 Select this option to enable Hyper-V vmbus testing. 2223 2224endmenu # "Kernel Testing and Coverage" 2225 2226endmenu # Kernel hacking 2227