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 depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED 246 depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST 247 help 248 Generate deduplicated BTF type information from DWARF debug info. 249 Turning this on expects presence of pahole tool, which will convert 250 DWARF type info into equivalent deduplicated BTF type info. 251 252config GDB_SCRIPTS 253 bool "Provide GDB scripts for kernel debugging" 254 depends on DEBUG_INFO 255 help 256 This creates the required links to GDB helper scripts in the 257 build directory. If you load vmlinux into gdb, the helper 258 scripts will be automatically imported by gdb as well, and 259 additional functions are available to analyze a Linux kernel 260 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst 261 for further details. 262 263config ENABLE_MUST_CHECK 264 bool "Enable __must_check logic" 265 default y 266 help 267 Enable the __must_check logic in the kernel build. Disable this to 268 suppress the "warning: ignoring return value of 'foo', declared with 269 attribute warn_unused_result" messages. 270 271config FRAME_WARN 272 int "Warn for stack frames larger than" 273 range 0 8192 274 default 2048 if GCC_PLUGIN_LATENT_ENTROPY 275 default 1280 if (!64BIT && PARISC) 276 default 1024 if (!64BIT && !PARISC) 277 default 2048 if 64BIT 278 help 279 Tell gcc to warn at build time for stack frames larger than this. 280 Setting this too low will cause a lot of warnings. 281 Setting it to 0 disables the warning. 282 283config STRIP_ASM_SYMS 284 bool "Strip assembler-generated symbols during link" 285 default n 286 help 287 Strip internal assembler-generated symbols during a link (symbols 288 that look like '.Lxxx') so they don't pollute the output of 289 get_wchan() and suchlike. 290 291config READABLE_ASM 292 bool "Generate readable assembler code" 293 depends on DEBUG_KERNEL 294 help 295 Disable some compiler optimizations that tend to generate human unreadable 296 assembler output. This may make the kernel slightly slower, but it helps 297 to keep kernel developers who have to stare a lot at assembler listings 298 sane. 299 300config HEADERS_INSTALL 301 bool "Install uapi headers to usr/include" 302 depends on !UML 303 help 304 This option will install uapi headers (headers exported to user-space) 305 into the usr/include directory for use during the kernel build. 306 This is unneeded for building the kernel itself, but needed for some 307 user-space program samples. It is also needed by some features such 308 as uapi header sanity checks. 309 310config DEBUG_SECTION_MISMATCH 311 bool "Enable full Section mismatch analysis" 312 help 313 The section mismatch analysis checks if there are illegal 314 references from one section to another section. 315 During linktime or runtime, some sections are dropped; 316 any use of code/data previously in these sections would 317 most likely result in an oops. 318 In the code, functions and variables are annotated with 319 __init,, etc. (see the full list in include/linux/init.h), 320 which results in the code/data being placed in specific sections. 321 The section mismatch analysis is always performed after a full 322 kernel build, and enabling this option causes the following 323 additional step to occur: 324 - Add the option -fno-inline-functions-called-once to gcc commands. 325 When inlining a function annotated with __init in a non-init 326 function, we would lose the section information and thus 327 the analysis would not catch the illegal reference. 328 This option tells gcc to inline less (but it does result in 329 a larger kernel). 330 331config SECTION_MISMATCH_WARN_ONLY 332 bool "Make section mismatch errors non-fatal" 333 default y 334 help 335 If you say N here, the build process will fail if there are any 336 section mismatch, instead of just throwing warnings. 337 338 If unsure, say Y. 339 340# 341# Select this config option from the architecture Kconfig, if it 342# is preferred to always offer frame pointers as a config 343# option on the architecture (regardless of KERNEL_DEBUG): 344# 345config ARCH_WANT_FRAME_POINTERS 346 bool 347 348config FRAME_POINTER 349 bool "Compile the kernel with frame pointers" 350 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS 351 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 352 help 353 If you say Y here the resulting kernel image will be slightly 354 larger and slower, but it gives very useful debugging information 355 in case of kernel bugs. (precise oopses/stacktraces/warnings) 356 357config STACK_VALIDATION 358 bool "Compile-time stack metadata validation" 359 depends on HAVE_STACK_VALIDATION 360 default n 361 help 362 Add compile-time checks to validate stack metadata, including frame 363 pointers (if CONFIG_FRAME_POINTER is enabled). This helps ensure 364 that runtime stack traces are more reliable. 365 366 This is also a prerequisite for generation of ORC unwind data, which 367 is needed for CONFIG_UNWINDER_ORC. 368 369 For more information, see 370 tools/objtool/Documentation/stack-validation.txt. 371 372config VMLINUX_VALIDATION 373 bool 374 depends on STACK_VALIDATION && DEBUG_ENTRY && !PARAVIRT 375 default y 376 377config DEBUG_FORCE_WEAK_PER_CPU 378 bool "Force weak per-cpu definitions" 379 depends on DEBUG_KERNEL 380 help 381 s390 and alpha require percpu variables in modules to be 382 defined weak to work around addressing range issue which 383 puts the following two restrictions on percpu variable 384 definitions. 385 386 1. percpu symbols must be unique whether static or not 387 2. percpu variables can't be defined inside a function 388 389 To ensure that generic code follows the above rules, this 390 option forces all percpu variables to be defined as weak. 391 392endmenu # "Compiler options" 393 394menu "Generic Kernel Debugging Instruments" 395 396config MAGIC_SYSRQ 397 bool "Magic SysRq key" 398 depends on !UML 399 help 400 If you say Y here, you will have some control over the system even 401 if the system crashes for example during kernel debugging (e.g., you 402 will be able to flush the buffer cache to disk, reboot the system 403 immediately or dump some status information). This is accomplished 404 by pressing various keys while holding SysRq (Alt+PrintScreen). It 405 also works on a serial console (on PC hardware at least), if you 406 send a BREAK and then within 5 seconds a command keypress. The 407 keys are documented in <file:Documentation/admin-guide/sysrq.rst>. 408 Don't say Y unless you really know what this hack does. 409 410config MAGIC_SYSRQ_DEFAULT_ENABLE 411 hex "Enable magic SysRq key functions by default" 412 depends on MAGIC_SYSRQ 413 default 0x1 414 help 415 Specifies which SysRq key functions are enabled by default. 416 This may be set to 1 or 0 to enable or disable them all, or 417 to a bitmask as described in Documentation/admin-guide/sysrq.rst. 418 419config MAGIC_SYSRQ_SERIAL 420 bool "Enable magic SysRq key over serial" 421 depends on MAGIC_SYSRQ 422 default y 423 help 424 Many embedded boards have a disconnected TTL level serial which can 425 generate some garbage that can lead to spurious false sysrq detects. 426 This option allows you to decide whether you want to enable the 427 magic SysRq key. 428 429config MAGIC_SYSRQ_SERIAL_SEQUENCE 430 string "Char sequence that enables magic SysRq over serial" 431 depends on MAGIC_SYSRQ_SERIAL 432 default "" 433 help 434 Specifies a sequence of characters that can follow BREAK to enable 435 SysRq on a serial console. 436 437 If unsure, leave an empty string and the option will not be enabled. 438 439config DEBUG_FS 440 bool "Debug Filesystem" 441 help 442 debugfs is a virtual file system that kernel developers use to put 443 debugging files into. Enable this option to be able to read and 444 write to these files. 445 446 For detailed documentation on the debugfs API, see 447 Documentation/filesystems/. 448 449 If unsure, say N. 450 451source "lib/Kconfig.kgdb" 452 453source "lib/Kconfig.ubsan" 454 455endmenu 456 457config DEBUG_KERNEL 458 bool "Kernel debugging" 459 help 460 Say Y here if you are developing drivers or trying to debug and 461 identify kernel problems. 462 463config DEBUG_MISC 464 bool "Miscellaneous debug code" 465 default DEBUG_KERNEL 466 depends on DEBUG_KERNEL 467 help 468 Say Y here if you need to enable miscellaneous debug code that should 469 be under a more specific debug option but isn't. 470 471 472menu "Memory Debugging" 473 474source "mm/Kconfig.debug" 475 476config DEBUG_OBJECTS 477 bool "Debug object operations" 478 depends on DEBUG_KERNEL 479 help 480 If you say Y here, additional code will be inserted into the 481 kernel to track the life time of various objects and validate 482 the operations on those objects. 483 484config DEBUG_OBJECTS_SELFTEST 485 bool "Debug objects selftest" 486 depends on DEBUG_OBJECTS 487 help 488 This enables the selftest of the object debug code. 489 490config DEBUG_OBJECTS_FREE 491 bool "Debug objects in freed memory" 492 depends on DEBUG_OBJECTS 493 help 494 This enables checks whether a k/v free operation frees an area 495 which contains an object which has not been deactivated 496 properly. This can make kmalloc/kfree-intensive workloads 497 much slower. 498 499config DEBUG_OBJECTS_TIMERS 500 bool "Debug timer objects" 501 depends on DEBUG_OBJECTS 502 help 503 If you say Y here, additional code will be inserted into the 504 timer routines to track the life time of timer objects and 505 validate the timer operations. 506 507config DEBUG_OBJECTS_WORK 508 bool "Debug work objects" 509 depends on DEBUG_OBJECTS 510 help 511 If you say Y here, additional code will be inserted into the 512 work queue routines to track the life time of work objects and 513 validate the work operations. 514 515config DEBUG_OBJECTS_RCU_HEAD 516 bool "Debug RCU callbacks objects" 517 depends on DEBUG_OBJECTS 518 help 519 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 520 521config DEBUG_OBJECTS_PERCPU_COUNTER 522 bool "Debug percpu counter objects" 523 depends on DEBUG_OBJECTS 524 help 525 If you say Y here, additional code will be inserted into the 526 percpu counter routines to track the life time of percpu counter 527 objects and validate the percpu counter operations. 528 529config DEBUG_OBJECTS_ENABLE_DEFAULT 530 int "debug_objects bootup default value (0-1)" 531 range 0 1 532 default "1" 533 depends on DEBUG_OBJECTS 534 help 535 Debug objects boot parameter default value 536 537config DEBUG_SLAB 538 bool "Debug slab memory allocations" 539 depends on DEBUG_KERNEL && SLAB 540 help 541 Say Y here to have the kernel do limited verification on memory 542 allocation as well as poisoning memory on free to catch use of freed 543 memory. This can make kmalloc/kfree-intensive workloads much slower. 544 545config SLUB_DEBUG_ON 546 bool "SLUB debugging on by default" 547 depends on SLUB && SLUB_DEBUG 548 default n 549 help 550 Boot with debugging on by default. SLUB boots by default with 551 the runtime debug capabilities switched off. Enabling this is 552 equivalent to specifying the "slub_debug" parameter on boot. 553 There is no support for more fine grained debug control like 554 possible with slub_debug=xxx. SLUB debugging may be switched 555 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying 556 "slub_debug=-". 557 558config SLUB_STATS 559 default n 560 bool "Enable SLUB performance statistics" 561 depends on SLUB && SYSFS 562 help 563 SLUB statistics are useful to debug SLUBs allocation behavior in 564 order find ways to optimize the allocator. This should never be 565 enabled for production use since keeping statistics slows down 566 the allocator by a few percentage points. The slabinfo command 567 supports the determination of the most active slabs to figure 568 out which slabs are relevant to a particular load. 569 Try running: slabinfo -DA 570 571config HAVE_DEBUG_KMEMLEAK 572 bool 573 574config DEBUG_KMEMLEAK 575 bool "Kernel memory leak detector" 576 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK 577 select DEBUG_FS 578 select STACKTRACE if STACKTRACE_SUPPORT 579 select KALLSYMS 580 select CRC32 581 help 582 Say Y here if you want to enable the memory leak 583 detector. The memory allocation/freeing is traced in a way 584 similar to the Boehm's conservative garbage collector, the 585 difference being that the orphan objects are not freed but 586 only shown in /sys/kernel/debug/kmemleak. Enabling this 587 feature will introduce an overhead to memory 588 allocations. See Documentation/dev-tools/kmemleak.rst for more 589 details. 590 591 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances 592 of finding leaks due to the slab objects poisoning. 593 594 In order to access the kmemleak file, debugfs needs to be 595 mounted (usually at /sys/kernel/debug). 596 597config DEBUG_KMEMLEAK_MEM_POOL_SIZE 598 int "Kmemleak memory pool size" 599 depends on DEBUG_KMEMLEAK 600 range 200 1000000 601 default 16000 602 help 603 Kmemleak must track all the memory allocations to avoid 604 reporting false positives. Since memory may be allocated or 605 freed before kmemleak is fully initialised, use a static pool 606 of metadata objects to track such callbacks. After kmemleak is 607 fully initialised, this memory pool acts as an emergency one 608 if slab allocations fail. 609 610config DEBUG_KMEMLEAK_TEST 611 tristate "Simple test for the kernel memory leak detector" 612 depends on DEBUG_KMEMLEAK && m 613 help 614 This option enables a module that explicitly leaks memory. 615 616 If unsure, say N. 617 618config DEBUG_KMEMLEAK_DEFAULT_OFF 619 bool "Default kmemleak to off" 620 depends on DEBUG_KMEMLEAK 621 help 622 Say Y here to disable kmemleak by default. It can then be enabled 623 on the command line via kmemleak=on. 624 625config DEBUG_KMEMLEAK_AUTO_SCAN 626 bool "Enable kmemleak auto scan thread on boot up" 627 default y 628 depends on DEBUG_KMEMLEAK 629 help 630 Depending on the cpu, kmemleak scan may be cpu intensive and can 631 stall user tasks at times. This option enables/disables automatic 632 kmemleak scan at boot up. 633 634 Say N here to disable kmemleak auto scan thread to stop automatic 635 scanning. Disabling this option disables automatic reporting of 636 memory leaks. 637 638 If unsure, say Y. 639 640config DEBUG_STACK_USAGE 641 bool "Stack utilization instrumentation" 642 depends on DEBUG_KERNEL && !IA64 643 help 644 Enables the display of the minimum amount of free stack which each 645 task has ever had available in the sysrq-T and sysrq-P debug output. 646 647 This option will slow down process creation somewhat. 648 649config SCHED_STACK_END_CHECK 650 bool "Detect stack corruption on calls to schedule()" 651 depends on DEBUG_KERNEL 652 default n 653 help 654 This option checks for a stack overrun on calls to schedule(). 655 If the stack end location is found to be over written always panic as 656 the content of the corrupted region can no longer be trusted. 657 This is to ensure no erroneous behaviour occurs which could result in 658 data corruption or a sporadic crash at a later stage once the region 659 is examined. The runtime overhead introduced is minimal. 660 661config ARCH_HAS_DEBUG_VM_PGTABLE 662 bool 663 help 664 An architecture should select this when it can successfully 665 build and run DEBUG_VM_PGTABLE. 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 DEBUG_VM_PGTABLE 703 bool "Debug arch page table for semantics compliance" 704 depends on MMU 705 depends on ARCH_HAS_DEBUG_VM_PGTABLE 706 default y if DEBUG_VM 707 help 708 This option provides a debug method which can be used to test 709 architecture page table helper functions on various platforms in 710 verifying if they comply with expected generic MM semantics. This 711 will help architecture code in making sure that any changes or 712 new additions of these helpers still conform to expected 713 semantics of the generic MM. Platforms will have to opt in for 714 this through ARCH_HAS_DEBUG_VM_PGTABLE. 715 716 If unsure, say N. 717 718config ARCH_HAS_DEBUG_VIRTUAL 719 bool 720 721config DEBUG_VIRTUAL 722 bool "Debug VM translations" 723 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL 724 help 725 Enable some costly sanity checks in virtual to page code. This can 726 catch mistakes with virt_to_page() and friends. 727 728 If unsure, say N. 729 730config DEBUG_NOMMU_REGIONS 731 bool "Debug the global anon/private NOMMU mapping region tree" 732 depends on DEBUG_KERNEL && !MMU 733 help 734 This option causes the global tree of anonymous and private mapping 735 regions to be regularly checked for invalid topology. 736 737config DEBUG_MEMORY_INIT 738 bool "Debug memory initialisation" if EXPERT 739 default !EXPERT 740 help 741 Enable this for additional checks during memory initialisation. 742 The sanity checks verify aspects of the VM such as the memory model 743 and other information provided by the architecture. Verbose 744 information will be printed at KERN_DEBUG loglevel depending 745 on the mminit_loglevel= command-line option. 746 747 If unsure, say Y 748 749config MEMORY_NOTIFIER_ERROR_INJECT 750 tristate "Memory hotplug notifier error injection module" 751 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION 752 help 753 This option provides the ability to inject artificial errors to 754 memory hotplug notifier chain callbacks. It is controlled through 755 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 756 757 If the notifier call chain should be failed with some events 758 notified, write the error code to "actions/<notifier event>/error". 759 760 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 761 762 # cd /sys/kernel/debug/notifier-error-inject/memory 763 # echo -12 > actions/MEM_GOING_OFFLINE/error 764 # echo offline > /sys/devices/system/memory/memoryXXX/state 765 bash: echo: write error: Cannot allocate memory 766 767 To compile this code as a module, choose M here: the module will 768 be called memory-notifier-error-inject. 769 770 If unsure, say N. 771 772config DEBUG_PER_CPU_MAPS 773 bool "Debug access to per_cpu maps" 774 depends on DEBUG_KERNEL 775 depends on SMP 776 help 777 Say Y to verify that the per_cpu map being accessed has 778 been set up. This adds a fair amount of code to kernel memory 779 and decreases performance. 780 781 Say N if unsure. 782 783config DEBUG_HIGHMEM 784 bool "Highmem debugging" 785 depends on DEBUG_KERNEL && HIGHMEM 786 help 787 This option enables additional error checking for high memory 788 systems. Disable for production systems. 789 790config HAVE_DEBUG_STACKOVERFLOW 791 bool 792 793config DEBUG_STACKOVERFLOW 794 bool "Check for stack overflows" 795 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 796 ---help--- 797 Say Y here if you want to check for overflows of kernel, IRQ 798 and exception stacks (if your architecture uses them). This 799 option will show detailed messages if free stack space drops 800 below a certain limit. 801 802 These kinds of bugs usually occur when call-chains in the 803 kernel get too deep, especially when interrupts are 804 involved. 805 806 Use this in cases where you see apparently random memory 807 corruption, especially if it appears in 'struct thread_info' 808 809 If in doubt, say "N". 810 811source "lib/Kconfig.kasan" 812 813endmenu # "Memory Debugging" 814 815config DEBUG_SHIRQ 816 bool "Debug shared IRQ handlers" 817 depends on DEBUG_KERNEL 818 help 819 Enable this to generate a spurious interrupt as soon as a shared 820 interrupt handler is registered, and just before one is deregistered. 821 Drivers ought to be able to handle interrupts coming in at those 822 points; some don't and need to be caught. 823 824menu "Debug Oops, Lockups and Hangs" 825 826config PANIC_ON_OOPS 827 bool "Panic on Oops" 828 help 829 Say Y here to enable the kernel to panic when it oopses. This 830 has the same effect as setting oops=panic on the kernel command 831 line. 832 833 This feature is useful to ensure that the kernel does not do 834 anything erroneous after an oops which could result in data 835 corruption or other issues. 836 837 Say N if unsure. 838 839config PANIC_ON_OOPS_VALUE 840 int 841 range 0 1 842 default 0 if !PANIC_ON_OOPS 843 default 1 if PANIC_ON_OOPS 844 845config PANIC_TIMEOUT 846 int "panic timeout" 847 default 0 848 help 849 Set the timeout value (in seconds) until a reboot occurs when the 850 the kernel panics. If n = 0, then we wait forever. A timeout 851 value n > 0 will wait n seconds before rebooting, while a timeout 852 value n < 0 will reboot immediately. 853 854config LOCKUP_DETECTOR 855 bool 856 857config SOFTLOCKUP_DETECTOR 858 bool "Detect Soft Lockups" 859 depends on DEBUG_KERNEL && !S390 860 select LOCKUP_DETECTOR 861 help 862 Say Y here to enable the kernel to act as a watchdog to detect 863 soft lockups. 864 865 Softlockups are bugs that cause the kernel to loop in kernel 866 mode for more than 20 seconds, without giving other tasks a 867 chance to run. The current stack trace is displayed upon 868 detection and the system will stay locked up. 869 870config BOOTPARAM_SOFTLOCKUP_PANIC 871 bool "Panic (Reboot) On Soft Lockups" 872 depends on SOFTLOCKUP_DETECTOR 873 help 874 Say Y here to enable the kernel to panic on "soft lockups", 875 which are bugs that cause the kernel to loop in kernel 876 mode for more than 20 seconds (configurable using the watchdog_thresh 877 sysctl), without giving other tasks a chance to run. 878 879 The panic can be used in combination with panic_timeout, 880 to cause the system to reboot automatically after a 881 lockup has been detected. This feature is useful for 882 high-availability systems that have uptime guarantees and 883 where a lockup must be resolved ASAP. 884 885 Say N if unsure. 886 887config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE 888 int 889 depends on SOFTLOCKUP_DETECTOR 890 range 0 1 891 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC 892 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC 893 894config HARDLOCKUP_DETECTOR_PERF 895 bool 896 select SOFTLOCKUP_DETECTOR 897 898# 899# Enables a timestamp based low pass filter to compensate for perf based 900# hard lockup detection which runs too fast due to turbo modes. 901# 902config HARDLOCKUP_CHECK_TIMESTAMP 903 bool 904 905# 906# arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard 907# lockup detector rather than the perf based detector. 908# 909config HARDLOCKUP_DETECTOR 910 bool "Detect Hard Lockups" 911 depends on DEBUG_KERNEL && !S390 912 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH 913 select LOCKUP_DETECTOR 914 select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF 915 select HARDLOCKUP_DETECTOR_ARCH if HAVE_HARDLOCKUP_DETECTOR_ARCH 916 help 917 Say Y here to enable the kernel to act as a watchdog to detect 918 hard lockups. 919 920 Hardlockups are bugs that cause the CPU to loop in kernel mode 921 for more than 10 seconds, without letting other interrupts have a 922 chance to run. The current stack trace is displayed upon detection 923 and the system will stay locked up. 924 925config BOOTPARAM_HARDLOCKUP_PANIC 926 bool "Panic (Reboot) On Hard Lockups" 927 depends on HARDLOCKUP_DETECTOR 928 help 929 Say Y here to enable the kernel to panic on "hard lockups", 930 which are bugs that cause the kernel to loop in kernel 931 mode with interrupts disabled for more than 10 seconds (configurable 932 using the watchdog_thresh sysctl). 933 934 Say N if unsure. 935 936config BOOTPARAM_HARDLOCKUP_PANIC_VALUE 937 int 938 depends on HARDLOCKUP_DETECTOR 939 range 0 1 940 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC 941 default 1 if BOOTPARAM_HARDLOCKUP_PANIC 942 943config DETECT_HUNG_TASK 944 bool "Detect Hung Tasks" 945 depends on DEBUG_KERNEL 946 default SOFTLOCKUP_DETECTOR 947 help 948 Say Y here to enable the kernel to detect "hung tasks", 949 which are bugs that cause the task to be stuck in 950 uninterruptible "D" state indefinitely. 951 952 When a hung task is detected, the kernel will print the 953 current stack trace (which you should report), but the 954 task will stay in uninterruptible state. If lockdep is 955 enabled then all held locks will also be reported. This 956 feature has negligible overhead. 957 958config DEFAULT_HUNG_TASK_TIMEOUT 959 int "Default timeout for hung task detection (in seconds)" 960 depends on DETECT_HUNG_TASK 961 default 120 962 help 963 This option controls the default timeout (in seconds) used 964 to determine when a task has become non-responsive and should 965 be considered hung. 966 967 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 968 sysctl or by writing a value to 969 /proc/sys/kernel/hung_task_timeout_secs. 970 971 A timeout of 0 disables the check. The default is two minutes. 972 Keeping the default should be fine in most cases. 973 974config BOOTPARAM_HUNG_TASK_PANIC 975 bool "Panic (Reboot) On Hung Tasks" 976 depends on DETECT_HUNG_TASK 977 help 978 Say Y here to enable the kernel to panic on "hung tasks", 979 which are bugs that cause the kernel to leave a task stuck 980 in uninterruptible "D" state. 981 982 The panic can be used in combination with panic_timeout, 983 to cause the system to reboot automatically after a 984 hung task has been detected. This feature is useful for 985 high-availability systems that have uptime guarantees and 986 where a hung tasks must be resolved ASAP. 987 988 Say N if unsure. 989 990config BOOTPARAM_HUNG_TASK_PANIC_VALUE 991 int 992 depends on DETECT_HUNG_TASK 993 range 0 1 994 default 0 if !BOOTPARAM_HUNG_TASK_PANIC 995 default 1 if BOOTPARAM_HUNG_TASK_PANIC 996 997config WQ_WATCHDOG 998 bool "Detect Workqueue Stalls" 999 depends on DEBUG_KERNEL 1000 help 1001 Say Y here to enable stall detection on workqueues. If a 1002 worker pool doesn't make forward progress on a pending work 1003 item for over a given amount of time, 30s by default, a 1004 warning message is printed along with dump of workqueue 1005 state. This can be configured through kernel parameter 1006 "workqueue.watchdog_thresh" and its sysfs counterpart. 1007 1008config TEST_LOCKUP 1009 tristate "Test module to generate lockups" 1010 help 1011 This builds the "test_lockup" module that helps to make sure 1012 that watchdogs and lockup detectors are working properly. 1013 1014 Depending on module parameters it could emulate soft or hard 1015 lockup, "hung task", or locking arbitrary lock for a long time. 1016 Also it could generate series of lockups with cooling-down periods. 1017 1018 If unsure, say N. 1019 1020endmenu # "Debug lockups and hangs" 1021 1022menu "Scheduler Debugging" 1023 1024config SCHED_DEBUG 1025 bool "Collect scheduler debugging info" 1026 depends on DEBUG_KERNEL && PROC_FS 1027 default y 1028 help 1029 If you say Y here, the /proc/sched_debug file will be provided 1030 that can help debug the scheduler. The runtime overhead of this 1031 option is minimal. 1032 1033config SCHED_INFO 1034 bool 1035 default n 1036 1037config SCHEDSTATS 1038 bool "Collect scheduler statistics" 1039 depends on DEBUG_KERNEL && PROC_FS 1040 select SCHED_INFO 1041 help 1042 If you say Y here, additional code will be inserted into the 1043 scheduler and related routines to collect statistics about 1044 scheduler behavior and provide them in /proc/schedstat. These 1045 stats may be useful for both tuning and debugging the scheduler 1046 If you aren't debugging the scheduler or trying to tune a specific 1047 application, you can say N to avoid the very slight overhead 1048 this adds. 1049 1050endmenu 1051 1052config DEBUG_TIMEKEEPING 1053 bool "Enable extra timekeeping sanity checking" 1054 help 1055 This option will enable additional timekeeping sanity checks 1056 which may be helpful when diagnosing issues where timekeeping 1057 problems are suspected. 1058 1059 This may include checks in the timekeeping hotpaths, so this 1060 option may have a (very small) performance impact to some 1061 workloads. 1062 1063 If unsure, say N. 1064 1065config DEBUG_PREEMPT 1066 bool "Debug preemptible kernel" 1067 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1068 default y 1069 help 1070 If you say Y here then the kernel will use a debug variant of the 1071 commonly used smp_processor_id() function and will print warnings 1072 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1073 will detect preemption count underflows. 1074 1075menu "Lock Debugging (spinlocks, mutexes, etc...)" 1076 1077config LOCK_DEBUGGING_SUPPORT 1078 bool 1079 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1080 default y 1081 1082config PROVE_LOCKING 1083 bool "Lock debugging: prove locking correctness" 1084 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1085 select LOCKDEP 1086 select DEBUG_SPINLOCK 1087 select DEBUG_MUTEXES 1088 select DEBUG_RT_MUTEXES if RT_MUTEXES 1089 select DEBUG_RWSEMS 1090 select DEBUG_WW_MUTEX_SLOWPATH 1091 select DEBUG_LOCK_ALLOC 1092 select TRACE_IRQFLAGS 1093 default n 1094 help 1095 This feature enables the kernel to prove that all locking 1096 that occurs in the kernel runtime is mathematically 1097 correct: that under no circumstance could an arbitrary (and 1098 not yet triggered) combination of observed locking 1099 sequences (on an arbitrary number of CPUs, running an 1100 arbitrary number of tasks and interrupt contexts) cause a 1101 deadlock. 1102 1103 In short, this feature enables the kernel to report locking 1104 related deadlocks before they actually occur. 1105 1106 The proof does not depend on how hard and complex a 1107 deadlock scenario would be to trigger: how many 1108 participant CPUs, tasks and irq-contexts would be needed 1109 for it to trigger. The proof also does not depend on 1110 timing: if a race and a resulting deadlock is possible 1111 theoretically (no matter how unlikely the race scenario 1112 is), it will be proven so and will immediately be 1113 reported by the kernel (once the event is observed that 1114 makes the deadlock theoretically possible). 1115 1116 If a deadlock is impossible (i.e. the locking rules, as 1117 observed by the kernel, are mathematically correct), the 1118 kernel reports nothing. 1119 1120 NOTE: this feature can also be enabled for rwlocks, mutexes 1121 and rwsems - in which case all dependencies between these 1122 different locking variants are observed and mapped too, and 1123 the proof of observed correctness is also maintained for an 1124 arbitrary combination of these separate locking variants. 1125 1126 For more details, see Documentation/locking/lockdep-design.rst. 1127 1128config PROVE_RAW_LOCK_NESTING 1129 bool "Enable raw_spinlock - spinlock nesting checks" 1130 depends on PROVE_LOCKING 1131 default n 1132 help 1133 Enable the raw_spinlock vs. spinlock nesting checks which ensure 1134 that the lock nesting rules for PREEMPT_RT enabled kernels are 1135 not violated. 1136 1137 NOTE: There are known nesting problems. So if you enable this 1138 option expect lockdep splats until these problems have been fully 1139 addressed which is work in progress. This config switch allows to 1140 identify and analyze these problems. It will be removed and the 1141 check permanentely enabled once the main issues have been fixed. 1142 1143 If unsure, select N. 1144 1145config LOCK_STAT 1146 bool "Lock usage statistics" 1147 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1148 select LOCKDEP 1149 select DEBUG_SPINLOCK 1150 select DEBUG_MUTEXES 1151 select DEBUG_RT_MUTEXES if RT_MUTEXES 1152 select DEBUG_LOCK_ALLOC 1153 default n 1154 help 1155 This feature enables tracking lock contention points 1156 1157 For more details, see Documentation/locking/lockstat.rst 1158 1159 This also enables lock events required by "perf lock", 1160 subcommand of perf. 1161 If you want to use "perf lock", you also need to turn on 1162 CONFIG_EVENT_TRACING. 1163 1164 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1165 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1166 1167config DEBUG_RT_MUTEXES 1168 bool "RT Mutex debugging, deadlock detection" 1169 depends on DEBUG_KERNEL && RT_MUTEXES 1170 help 1171 This allows rt mutex semantics violations and rt mutex related 1172 deadlocks (lockups) to be detected and reported automatically. 1173 1174config DEBUG_SPINLOCK 1175 bool "Spinlock and rw-lock debugging: basic checks" 1176 depends on DEBUG_KERNEL 1177 select UNINLINE_SPIN_UNLOCK 1178 help 1179 Say Y here and build SMP to catch missing spinlock initialization 1180 and certain other kinds of spinlock errors commonly made. This is 1181 best used in conjunction with the NMI watchdog so that spinlock 1182 deadlocks are also debuggable. 1183 1184config DEBUG_MUTEXES 1185 bool "Mutex debugging: basic checks" 1186 depends on DEBUG_KERNEL 1187 help 1188 This feature allows mutex semantics violations to be detected and 1189 reported. 1190 1191config DEBUG_WW_MUTEX_SLOWPATH 1192 bool "Wait/wound mutex debugging: Slowpath testing" 1193 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1194 select DEBUG_LOCK_ALLOC 1195 select DEBUG_SPINLOCK 1196 select DEBUG_MUTEXES 1197 help 1198 This feature enables slowpath testing for w/w mutex users by 1199 injecting additional -EDEADLK wound/backoff cases. Together with 1200 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1201 will test all possible w/w mutex interface abuse with the 1202 exception of simply not acquiring all the required locks. 1203 Note that this feature can introduce significant overhead, so 1204 it really should not be enabled in a production or distro kernel, 1205 even a debug kernel. If you are a driver writer, enable it. If 1206 you are a distro, do not. 1207 1208config DEBUG_RWSEMS 1209 bool "RW Semaphore debugging: basic checks" 1210 depends on DEBUG_KERNEL 1211 help 1212 This debugging feature allows mismatched rw semaphore locks 1213 and unlocks to be detected and reported. 1214 1215config DEBUG_LOCK_ALLOC 1216 bool "Lock debugging: detect incorrect freeing of live locks" 1217 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1218 select DEBUG_SPINLOCK 1219 select DEBUG_MUTEXES 1220 select DEBUG_RT_MUTEXES if RT_MUTEXES 1221 select LOCKDEP 1222 help 1223 This feature will check whether any held lock (spinlock, rwlock, 1224 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1225 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1226 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1227 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1228 held during task exit. 1229 1230config LOCKDEP 1231 bool 1232 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1233 select STACKTRACE 1234 select FRAME_POINTER if !MIPS && !PPC && !ARM && !S390 && !MICROBLAZE && !ARC && !X86 1235 select KALLSYMS 1236 select KALLSYMS_ALL 1237 1238config LOCKDEP_SMALL 1239 bool 1240 1241config DEBUG_LOCKDEP 1242 bool "Lock dependency engine debugging" 1243 depends on DEBUG_KERNEL && LOCKDEP 1244 help 1245 If you say Y here, the lock dependency engine will do 1246 additional runtime checks to debug itself, at the price 1247 of more runtime overhead. 1248 1249config DEBUG_ATOMIC_SLEEP 1250 bool "Sleep inside atomic section checking" 1251 select PREEMPT_COUNT 1252 depends on DEBUG_KERNEL 1253 depends on !ARCH_NO_PREEMPT 1254 help 1255 If you say Y here, various routines which may sleep will become very 1256 noisy if they are called inside atomic sections: when a spinlock is 1257 held, inside an rcu read side critical section, inside preempt disabled 1258 sections, inside an interrupt, etc... 1259 1260config DEBUG_LOCKING_API_SELFTESTS 1261 bool "Locking API boot-time self-tests" 1262 depends on DEBUG_KERNEL 1263 help 1264 Say Y here if you want the kernel to run a short self-test during 1265 bootup. The self-test checks whether common types of locking bugs 1266 are detected by debugging mechanisms or not. (if you disable 1267 lock debugging then those bugs wont be detected of course.) 1268 The following locking APIs are covered: spinlocks, rwlocks, 1269 mutexes and rwsems. 1270 1271config LOCK_TORTURE_TEST 1272 tristate "torture tests for locking" 1273 depends on DEBUG_KERNEL 1274 select TORTURE_TEST 1275 help 1276 This option provides a kernel module that runs torture tests 1277 on kernel locking primitives. The kernel module may be built 1278 after the fact on the running kernel to be tested, if desired. 1279 1280 Say Y here if you want kernel locking-primitive torture tests 1281 to be built into the kernel. 1282 Say M if you want these torture tests to build as a module. 1283 Say N if you are unsure. 1284 1285config WW_MUTEX_SELFTEST 1286 tristate "Wait/wound mutex selftests" 1287 help 1288 This option provides a kernel module that runs tests on the 1289 on the struct ww_mutex locking API. 1290 1291 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1292 with this test harness. 1293 1294 Say M if you want these self tests to build as a module. 1295 Say N if you are unsure. 1296 1297endmenu # lock debugging 1298 1299config TRACE_IRQFLAGS 1300 bool 1301 help 1302 Enables hooks to interrupt enabling and disabling for 1303 either tracing or lock debugging. 1304 1305config STACKTRACE 1306 bool "Stack backtrace support" 1307 depends on STACKTRACE_SUPPORT 1308 help 1309 This option causes the kernel to create a /proc/pid/stack for 1310 every process, showing its current stack trace. 1311 It is also used by various kernel debugging features that require 1312 stack trace generation. 1313 1314config WARN_ALL_UNSEEDED_RANDOM 1315 bool "Warn for all uses of unseeded randomness" 1316 default n 1317 help 1318 Some parts of the kernel contain bugs relating to their use of 1319 cryptographically secure random numbers before it's actually possible 1320 to generate those numbers securely. This setting ensures that these 1321 flaws don't go unnoticed, by enabling a message, should this ever 1322 occur. This will allow people with obscure setups to know when things 1323 are going wrong, so that they might contact developers about fixing 1324 it. 1325 1326 Unfortunately, on some models of some architectures getting 1327 a fully seeded CRNG is extremely difficult, and so this can 1328 result in dmesg getting spammed for a surprisingly long 1329 time. This is really bad from a security perspective, and 1330 so architecture maintainers really need to do what they can 1331 to get the CRNG seeded sooner after the system is booted. 1332 However, since users cannot do anything actionable to 1333 address this, by default the kernel will issue only a single 1334 warning for the first use of unseeded randomness. 1335 1336 Say Y here if you want to receive warnings for all uses of 1337 unseeded randomness. This will be of use primarily for 1338 those developers interested in improving the security of 1339 Linux kernels running on their architecture (or 1340 subarchitecture). 1341 1342config DEBUG_KOBJECT 1343 bool "kobject debugging" 1344 depends on DEBUG_KERNEL 1345 help 1346 If you say Y here, some extra kobject debugging messages will be sent 1347 to the syslog. 1348 1349config DEBUG_KOBJECT_RELEASE 1350 bool "kobject release debugging" 1351 depends on DEBUG_OBJECTS_TIMERS 1352 help 1353 kobjects are reference counted objects. This means that their 1354 last reference count put is not predictable, and the kobject can 1355 live on past the point at which a driver decides to drop it's 1356 initial reference to the kobject gained on allocation. An 1357 example of this would be a struct device which has just been 1358 unregistered. 1359 1360 However, some buggy drivers assume that after such an operation, 1361 the memory backing the kobject can be immediately freed. This 1362 goes completely against the principles of a refcounted object. 1363 1364 If you say Y here, the kernel will delay the release of kobjects 1365 on the last reference count to improve the visibility of this 1366 kind of kobject release bug. 1367 1368config HAVE_DEBUG_BUGVERBOSE 1369 bool 1370 1371menu "Debug kernel data structures" 1372 1373config DEBUG_LIST 1374 bool "Debug linked list manipulation" 1375 depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION 1376 help 1377 Enable this to turn on extended checks in the linked-list 1378 walking routines. 1379 1380 If unsure, say N. 1381 1382config DEBUG_PLIST 1383 bool "Debug priority linked list manipulation" 1384 depends on DEBUG_KERNEL 1385 help 1386 Enable this to turn on extended checks in the priority-ordered 1387 linked-list (plist) walking routines. This checks the entire 1388 list multiple times during each manipulation. 1389 1390 If unsure, say N. 1391 1392config DEBUG_SG 1393 bool "Debug SG table operations" 1394 depends on DEBUG_KERNEL 1395 help 1396 Enable this to turn on checks on scatter-gather tables. This can 1397 help find problems with drivers that do not properly initialize 1398 their sg tables. 1399 1400 If unsure, say N. 1401 1402config DEBUG_NOTIFIERS 1403 bool "Debug notifier call chains" 1404 depends on DEBUG_KERNEL 1405 help 1406 Enable this to turn on sanity checking for notifier call chains. 1407 This is most useful for kernel developers to make sure that 1408 modules properly unregister themselves from notifier chains. 1409 This is a relatively cheap check but if you care about maximum 1410 performance, say N. 1411 1412config BUG_ON_DATA_CORRUPTION 1413 bool "Trigger a BUG when data corruption is detected" 1414 select DEBUG_LIST 1415 help 1416 Select this option if the kernel should BUG when it encounters 1417 data corruption in kernel memory structures when they get checked 1418 for validity. 1419 1420 If unsure, say N. 1421 1422endmenu 1423 1424config DEBUG_CREDENTIALS 1425 bool "Debug credential management" 1426 depends on DEBUG_KERNEL 1427 help 1428 Enable this to turn on some debug checking for credential 1429 management. The additional code keeps track of the number of 1430 pointers from task_structs to any given cred struct, and checks to 1431 see that this number never exceeds the usage count of the cred 1432 struct. 1433 1434 Furthermore, if SELinux is enabled, this also checks that the 1435 security pointer in the cred struct is never seen to be invalid. 1436 1437 If unsure, say N. 1438 1439source "kernel/rcu/Kconfig.debug" 1440 1441config DEBUG_WQ_FORCE_RR_CPU 1442 bool "Force round-robin CPU selection for unbound work items" 1443 depends on DEBUG_KERNEL 1444 default n 1445 help 1446 Workqueue used to implicitly guarantee that work items queued 1447 without explicit CPU specified are put on the local CPU. This 1448 guarantee is no longer true and while local CPU is still 1449 preferred work items may be put on foreign CPUs. Kernel 1450 parameter "workqueue.debug_force_rr_cpu" is added to force 1451 round-robin CPU selection to flush out usages which depend on the 1452 now broken guarantee. This config option enables the debug 1453 feature by default. When enabled, memory and cache locality will 1454 be impacted. 1455 1456config DEBUG_BLOCK_EXT_DEVT 1457 bool "Force extended block device numbers and spread them" 1458 depends on DEBUG_KERNEL 1459 depends on BLOCK 1460 default n 1461 help 1462 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON 1463 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT 1464 YOU ARE DOING. Distros, please enable this and fix whatever 1465 is broken. 1466 1467 Conventionally, block device numbers are allocated from 1468 predetermined contiguous area. However, extended block area 1469 may introduce non-contiguous block device numbers. This 1470 option forces most block device numbers to be allocated from 1471 the extended space and spreads them to discover kernel or 1472 userland code paths which assume predetermined contiguous 1473 device number allocation. 1474 1475 Note that turning on this debug option shuffles all the 1476 device numbers for all IDE and SCSI devices including libata 1477 ones, so root partition specified using device number 1478 directly (via rdev or root=MAJ:MIN) won't work anymore. 1479 Textual device names (root=/dev/sdXn) will continue to work. 1480 1481 Say N if you are unsure. 1482 1483config CPU_HOTPLUG_STATE_CONTROL 1484 bool "Enable CPU hotplug state control" 1485 depends on DEBUG_KERNEL 1486 depends on HOTPLUG_CPU 1487 default n 1488 help 1489 Allows to write steps between "offline" and "online" to the CPUs 1490 sysfs target file so states can be stepped granular. This is a debug 1491 option for now as the hotplug machinery cannot be stopped and 1492 restarted at arbitrary points yet. 1493 1494 Say N if your are unsure. 1495 1496config LATENCYTOP 1497 bool "Latency measuring infrastructure" 1498 depends on DEBUG_KERNEL 1499 depends on STACKTRACE_SUPPORT 1500 depends on PROC_FS 1501 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86 1502 select KALLSYMS 1503 select KALLSYMS_ALL 1504 select STACKTRACE 1505 select SCHEDSTATS 1506 select SCHED_DEBUG 1507 help 1508 Enable this option if you want to use the LatencyTOP tool 1509 to find out which userspace is blocking on what kernel operations. 1510 1511source "kernel/trace/Kconfig" 1512 1513config PROVIDE_OHCI1394_DMA_INIT 1514 bool "Remote debugging over FireWire early on boot" 1515 depends on PCI && X86 1516 help 1517 If you want to debug problems which hang or crash the kernel early 1518 on boot and the crashing machine has a FireWire port, you can use 1519 this feature to remotely access the memory of the crashed machine 1520 over FireWire. This employs remote DMA as part of the OHCI1394 1521 specification which is now the standard for FireWire controllers. 1522 1523 With remote DMA, you can monitor the printk buffer remotely using 1524 firescope and access all memory below 4GB using fireproxy from gdb. 1525 Even controlling a kernel debugger is possible using remote DMA. 1526 1527 Usage: 1528 1529 If ohci1394_dma=early is used as boot parameter, it will initialize 1530 all OHCI1394 controllers which are found in the PCI config space. 1531 1532 As all changes to the FireWire bus such as enabling and disabling 1533 devices cause a bus reset and thereby disable remote DMA for all 1534 devices, be sure to have the cable plugged and FireWire enabled on 1535 the debugging host before booting the debug target for debugging. 1536 1537 This code (~1k) is freed after boot. By then, the firewire stack 1538 in charge of the OHCI-1394 controllers should be used instead. 1539 1540 See Documentation/core-api/debugging-via-ohci1394.rst for more information. 1541 1542source "samples/Kconfig" 1543 1544config ARCH_HAS_DEVMEM_IS_ALLOWED 1545 bool 1546 1547config STRICT_DEVMEM 1548 bool "Filter access to /dev/mem" 1549 depends on MMU && DEVMEM 1550 depends on ARCH_HAS_DEVMEM_IS_ALLOWED 1551 default y if PPC || X86 || ARM64 1552 help 1553 If this option is disabled, you allow userspace (root) access to all 1554 of memory, including kernel and userspace memory. Accidental 1555 access to this is obviously disastrous, but specific access can 1556 be used by people debugging the kernel. Note that with PAT support 1557 enabled, even in this case there are restrictions on /dev/mem 1558 use due to the cache aliasing requirements. 1559 1560 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 1561 file only allows userspace access to PCI space and the BIOS code and 1562 data regions. This is sufficient for dosemu and X and all common 1563 users of /dev/mem. 1564 1565 If in doubt, say Y. 1566 1567config IO_STRICT_DEVMEM 1568 bool "Filter I/O access to /dev/mem" 1569 depends on STRICT_DEVMEM 1570 help 1571 If this option is disabled, you allow userspace (root) access to all 1572 io-memory regardless of whether a driver is actively using that 1573 range. Accidental access to this is obviously disastrous, but 1574 specific access can be used by people debugging kernel drivers. 1575 1576 If this option is switched on, the /dev/mem file only allows 1577 userspace access to *idle* io-memory ranges (see /proc/iomem) This 1578 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 1579 if the driver using a given range cannot be disabled. 1580 1581 If in doubt, say Y. 1582 1583menu "$(SRCARCH) Debugging" 1584 1585source "arch/$(SRCARCH)/Kconfig.debug" 1586 1587endmenu 1588 1589menu "Kernel Testing and Coverage" 1590 1591source "lib/kunit/Kconfig" 1592 1593config NOTIFIER_ERROR_INJECTION 1594 tristate "Notifier error injection" 1595 depends on DEBUG_KERNEL 1596 select DEBUG_FS 1597 help 1598 This option provides the ability to inject artificial errors to 1599 specified notifier chain callbacks. It is useful to test the error 1600 handling of notifier call chain failures. 1601 1602 Say N if unsure. 1603 1604config PM_NOTIFIER_ERROR_INJECT 1605 tristate "PM notifier error injection module" 1606 depends on PM && NOTIFIER_ERROR_INJECTION 1607 default m if PM_DEBUG 1608 help 1609 This option provides the ability to inject artificial errors to 1610 PM notifier chain callbacks. It is controlled through debugfs 1611 interface /sys/kernel/debug/notifier-error-inject/pm 1612 1613 If the notifier call chain should be failed with some events 1614 notified, write the error code to "actions/<notifier event>/error". 1615 1616 Example: Inject PM suspend error (-12 = -ENOMEM) 1617 1618 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1619 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1620 # echo mem > /sys/power/state 1621 bash: echo: write error: Cannot allocate memory 1622 1623 To compile this code as a module, choose M here: the module will 1624 be called pm-notifier-error-inject. 1625 1626 If unsure, say N. 1627 1628config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1629 tristate "OF reconfig notifier error injection module" 1630 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1631 help 1632 This option provides the ability to inject artificial errors to 1633 OF reconfig notifier chain callbacks. It is controlled 1634 through debugfs interface under 1635 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1636 1637 If the notifier call chain should be failed with some events 1638 notified, write the error code to "actions/<notifier event>/error". 1639 1640 To compile this code as a module, choose M here: the module will 1641 be called of-reconfig-notifier-error-inject. 1642 1643 If unsure, say N. 1644 1645config NETDEV_NOTIFIER_ERROR_INJECT 1646 tristate "Netdev notifier error injection module" 1647 depends on NET && NOTIFIER_ERROR_INJECTION 1648 help 1649 This option provides the ability to inject artificial errors to 1650 netdevice notifier chain callbacks. It is controlled through debugfs 1651 interface /sys/kernel/debug/notifier-error-inject/netdev 1652 1653 If the notifier call chain should be failed with some events 1654 notified, write the error code to "actions/<notifier event>/error". 1655 1656 Example: Inject netdevice mtu change error (-22 = -EINVAL) 1657 1658 # cd /sys/kernel/debug/notifier-error-inject/netdev 1659 # echo -22 > actions/NETDEV_CHANGEMTU/error 1660 # ip link set eth0 mtu 1024 1661 RTNETLINK answers: Invalid argument 1662 1663 To compile this code as a module, choose M here: the module will 1664 be called netdev-notifier-error-inject. 1665 1666 If unsure, say N. 1667 1668config FUNCTION_ERROR_INJECTION 1669 def_bool y 1670 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 1671 1672config FAULT_INJECTION 1673 bool "Fault-injection framework" 1674 depends on DEBUG_KERNEL 1675 help 1676 Provide fault-injection framework. 1677 For more details, see Documentation/fault-injection/. 1678 1679config FAILSLAB 1680 bool "Fault-injection capability for kmalloc" 1681 depends on FAULT_INJECTION 1682 depends on SLAB || SLUB 1683 help 1684 Provide fault-injection capability for kmalloc. 1685 1686config FAIL_PAGE_ALLOC 1687 bool "Fault-injection capability for alloc_pages()" 1688 depends on FAULT_INJECTION 1689 help 1690 Provide fault-injection capability for alloc_pages(). 1691 1692config FAIL_MAKE_REQUEST 1693 bool "Fault-injection capability for disk IO" 1694 depends on FAULT_INJECTION && BLOCK 1695 help 1696 Provide fault-injection capability for disk IO. 1697 1698config FAIL_IO_TIMEOUT 1699 bool "Fault-injection capability for faking disk interrupts" 1700 depends on FAULT_INJECTION && BLOCK 1701 help 1702 Provide fault-injection capability on end IO handling. This 1703 will make the block layer "forget" an interrupt as configured, 1704 thus exercising the error handling. 1705 1706 Only works with drivers that use the generic timeout handling, 1707 for others it wont do anything. 1708 1709config FAIL_FUTEX 1710 bool "Fault-injection capability for futexes" 1711 select DEBUG_FS 1712 depends on FAULT_INJECTION && FUTEX 1713 help 1714 Provide fault-injection capability for futexes. 1715 1716config FAULT_INJECTION_DEBUG_FS 1717 bool "Debugfs entries for fault-injection capabilities" 1718 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 1719 help 1720 Enable configuration of fault-injection capabilities via debugfs. 1721 1722config FAIL_FUNCTION 1723 bool "Fault-injection capability for functions" 1724 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 1725 help 1726 Provide function-based fault-injection capability. 1727 This will allow you to override a specific function with a return 1728 with given return value. As a result, function caller will see 1729 an error value and have to handle it. This is useful to test the 1730 error handling in various subsystems. 1731 1732config FAIL_MMC_REQUEST 1733 bool "Fault-injection capability for MMC IO" 1734 depends on FAULT_INJECTION_DEBUG_FS && MMC 1735 help 1736 Provide fault-injection capability for MMC IO. 1737 This will make the mmc core return data errors. This is 1738 useful to test the error handling in the mmc block device 1739 and to test how the mmc host driver handles retries from 1740 the block device. 1741 1742config FAULT_INJECTION_STACKTRACE_FILTER 1743 bool "stacktrace filter for fault-injection capabilities" 1744 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 1745 depends on !X86_64 1746 select STACKTRACE 1747 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86 1748 help 1749 Provide stacktrace filter for fault-injection capabilities 1750 1751config ARCH_HAS_KCOV 1752 bool 1753 help 1754 An architecture should select this when it can successfully 1755 build and run with CONFIG_KCOV. This typically requires 1756 disabling instrumentation for some early boot code. 1757 1758config CC_HAS_SANCOV_TRACE_PC 1759 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 1760 1761 1762config KCOV 1763 bool "Code coverage for fuzzing" 1764 depends on ARCH_HAS_KCOV 1765 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 1766 select DEBUG_FS 1767 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 1768 help 1769 KCOV exposes kernel code coverage information in a form suitable 1770 for coverage-guided fuzzing (randomized testing). 1771 1772 If RANDOMIZE_BASE is enabled, PC values will not be stable across 1773 different machines and across reboots. If you need stable PC values, 1774 disable RANDOMIZE_BASE. 1775 1776 For more details, see Documentation/dev-tools/kcov.rst. 1777 1778config KCOV_ENABLE_COMPARISONS 1779 bool "Enable comparison operands collection by KCOV" 1780 depends on KCOV 1781 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 1782 help 1783 KCOV also exposes operands of every comparison in the instrumented 1784 code along with operand sizes and PCs of the comparison instructions. 1785 These operands can be used by fuzzing engines to improve the quality 1786 of fuzzing coverage. 1787 1788config KCOV_INSTRUMENT_ALL 1789 bool "Instrument all code by default" 1790 depends on KCOV 1791 default y 1792 help 1793 If you are doing generic system call fuzzing (like e.g. syzkaller), 1794 then you will want to instrument the whole kernel and you should 1795 say y here. If you are doing more targeted fuzzing (like e.g. 1796 filesystem fuzzing with AFL) then you will want to enable coverage 1797 for more specific subsets of files, and should say n here. 1798 1799config KCOV_IRQ_AREA_SIZE 1800 hex "Size of interrupt coverage collection area in words" 1801 depends on KCOV 1802 default 0x40000 1803 help 1804 KCOV uses preallocated per-cpu areas to collect coverage from 1805 soft interrupts. This specifies the size of those areas in the 1806 number of unsigned long words. 1807 1808menuconfig RUNTIME_TESTING_MENU 1809 bool "Runtime Testing" 1810 def_bool y 1811 1812if RUNTIME_TESTING_MENU 1813 1814config LKDTM 1815 tristate "Linux Kernel Dump Test Tool Module" 1816 depends on DEBUG_FS 1817 help 1818 This module enables testing of the different dumping mechanisms by 1819 inducing system failures at predefined crash points. 1820 If you don't need it: say N 1821 Choose M here to compile this code as a module. The module will be 1822 called lkdtm. 1823 1824 Documentation on how to use the module can be found in 1825 Documentation/fault-injection/provoke-crashes.rst 1826 1827config TEST_LIST_SORT 1828 tristate "Linked list sorting test" 1829 depends on DEBUG_KERNEL || m 1830 help 1831 Enable this to turn on 'list_sort()' function test. This test is 1832 executed only once during system boot (so affects only boot time), 1833 or at module load time. 1834 1835 If unsure, say N. 1836 1837config TEST_MIN_HEAP 1838 tristate "Min heap test" 1839 depends on DEBUG_KERNEL || m 1840 help 1841 Enable this to turn on min heap function tests. This test is 1842 executed only once during system boot (so affects only boot time), 1843 or at module load time. 1844 1845 If unsure, say N. 1846 1847config TEST_SORT 1848 tristate "Array-based sort test" 1849 depends on DEBUG_KERNEL || m 1850 help 1851 This option enables the self-test function of 'sort()' at boot, 1852 or at module load time. 1853 1854 If unsure, say N. 1855 1856config KPROBES_SANITY_TEST 1857 bool "Kprobes sanity tests" 1858 depends on DEBUG_KERNEL 1859 depends on KPROBES 1860 help 1861 This option provides for testing basic kprobes functionality on 1862 boot. Samples of kprobe and kretprobe are inserted and 1863 verified for functionality. 1864 1865 Say N if you are unsure. 1866 1867config BACKTRACE_SELF_TEST 1868 tristate "Self test for the backtrace code" 1869 depends on DEBUG_KERNEL 1870 help 1871 This option provides a kernel module that can be used to test 1872 the kernel stack backtrace code. This option is not useful 1873 for distributions or general kernels, but only for kernel 1874 developers working on architecture code. 1875 1876 Note that if you want to also test saved backtraces, you will 1877 have to enable STACKTRACE as well. 1878 1879 Say N if you are unsure. 1880 1881config RBTREE_TEST 1882 tristate "Red-Black tree test" 1883 depends on DEBUG_KERNEL 1884 help 1885 A benchmark measuring the performance of the rbtree library. 1886 Also includes rbtree invariant checks. 1887 1888config REED_SOLOMON_TEST 1889 tristate "Reed-Solomon library test" 1890 depends on DEBUG_KERNEL || m 1891 select REED_SOLOMON 1892 select REED_SOLOMON_ENC16 1893 select REED_SOLOMON_DEC16 1894 help 1895 This option enables the self-test function of rslib at boot, 1896 or at module load time. 1897 1898 If unsure, say N. 1899 1900config INTERVAL_TREE_TEST 1901 tristate "Interval tree test" 1902 depends on DEBUG_KERNEL 1903 select INTERVAL_TREE 1904 help 1905 A benchmark measuring the performance of the interval tree library 1906 1907config PERCPU_TEST 1908 tristate "Per cpu operations test" 1909 depends on m && DEBUG_KERNEL 1910 help 1911 Enable this option to build test module which validates per-cpu 1912 operations. 1913 1914 If unsure, say N. 1915 1916config ATOMIC64_SELFTEST 1917 tristate "Perform an atomic64_t self-test" 1918 help 1919 Enable this option to test the atomic64_t functions at boot or 1920 at module load time. 1921 1922 If unsure, say N. 1923 1924config ASYNC_RAID6_TEST 1925 tristate "Self test for hardware accelerated raid6 recovery" 1926 depends on ASYNC_RAID6_RECOV 1927 select ASYNC_MEMCPY 1928 ---help--- 1929 This is a one-shot self test that permutes through the 1930 recovery of all the possible two disk failure scenarios for a 1931 N-disk array. Recovery is performed with the asynchronous 1932 raid6 recovery routines, and will optionally use an offload 1933 engine if one is available. 1934 1935 If unsure, say N. 1936 1937config TEST_HEXDUMP 1938 tristate "Test functions located in the hexdump module at runtime" 1939 1940config TEST_STRING_HELPERS 1941 tristate "Test functions located in the string_helpers module at runtime" 1942 1943config TEST_STRSCPY 1944 tristate "Test strscpy*() family of functions at runtime" 1945 1946config TEST_KSTRTOX 1947 tristate "Test kstrto*() family of functions at runtime" 1948 1949config TEST_PRINTF 1950 tristate "Test printf() family of functions at runtime" 1951 1952config TEST_BITMAP 1953 tristate "Test bitmap_*() family of functions at runtime" 1954 help 1955 Enable this option to test the bitmap functions at boot. 1956 1957 If unsure, say N. 1958 1959config TEST_BITFIELD 1960 tristate "Test bitfield functions at runtime" 1961 help 1962 Enable this option to test the bitfield functions at boot. 1963 1964 If unsure, say N. 1965 1966config TEST_UUID 1967 tristate "Test functions located in the uuid module at runtime" 1968 1969config TEST_XARRAY 1970 tristate "Test the XArray code at runtime" 1971 1972config TEST_OVERFLOW 1973 tristate "Test check_*_overflow() functions at runtime" 1974 1975config TEST_RHASHTABLE 1976 tristate "Perform selftest on resizable hash table" 1977 help 1978 Enable this option to test the rhashtable functions at boot. 1979 1980 If unsure, say N. 1981 1982config TEST_HASH 1983 tristate "Perform selftest on hash functions" 1984 help 1985 Enable this option to test the kernel's integer (<linux/hash.h>), 1986 string (<linux/stringhash.h>), and siphash (<linux/siphash.h>) 1987 hash functions on boot (or module load). 1988 1989 This is intended to help people writing architecture-specific 1990 optimized versions. If unsure, say N. 1991 1992config TEST_IDA 1993 tristate "Perform selftest on IDA functions" 1994 1995config TEST_PARMAN 1996 tristate "Perform selftest on priority array manager" 1997 depends on PARMAN 1998 help 1999 Enable this option to test priority array manager on boot 2000 (or module load). 2001 2002 If unsure, say N. 2003 2004config TEST_IRQ_TIMINGS 2005 bool "IRQ timings selftest" 2006 depends on IRQ_TIMINGS 2007 help 2008 Enable this option to test the irq timings code on boot. 2009 2010 If unsure, say N. 2011 2012config TEST_LKM 2013 tristate "Test module loading with 'hello world' module" 2014 depends on m 2015 help 2016 This builds the "test_module" module that emits "Hello, world" 2017 on printk when loaded. It is designed to be used for basic 2018 evaluation of the module loading subsystem (for example when 2019 validating module verification). It lacks any extra dependencies, 2020 and will not normally be loaded by the system unless explicitly 2021 requested by name. 2022 2023 If unsure, say N. 2024 2025config TEST_BITOPS 2026 tristate "Test module for compilation of clear_bit/set_bit operations" 2027 depends on m 2028 help 2029 This builds the "test_bitops" module that is much like the 2030 TEST_LKM module except that it does a basic exercise of the 2031 clear_bit and set_bit macros to make sure there are no compiler 2032 warnings from C=1 sparse checker or -Wextra compilations. It has 2033 no dependencies and doesn't run or load unless explicitly requested 2034 by name. for example: modprobe test_bitops. 2035 2036 If unsure, say N. 2037 2038config TEST_VMALLOC 2039 tristate "Test module for stress/performance analysis of vmalloc allocator" 2040 default n 2041 depends on MMU 2042 depends on m 2043 help 2044 This builds the "test_vmalloc" module that should be used for 2045 stress and performance analysis. So, any new change for vmalloc 2046 subsystem can be evaluated from performance and stability point 2047 of view. 2048 2049 If unsure, say N. 2050 2051config TEST_USER_COPY 2052 tristate "Test user/kernel boundary protections" 2053 depends on m 2054 help 2055 This builds the "test_user_copy" module that runs sanity checks 2056 on the copy_to/from_user infrastructure, making sure basic 2057 user/kernel boundary testing is working. If it fails to load, 2058 a regression has been detected in the user/kernel memory boundary 2059 protections. 2060 2061 If unsure, say N. 2062 2063config TEST_BPF 2064 tristate "Test BPF filter functionality" 2065 depends on m && NET 2066 help 2067 This builds the "test_bpf" module that runs various test vectors 2068 against the BPF interpreter or BPF JIT compiler depending on the 2069 current setting. This is in particular useful for BPF JIT compiler 2070 development, but also to run regression tests against changes in 2071 the interpreter code. It also enables test stubs for eBPF maps and 2072 verifier used by user space verifier testsuite. 2073 2074 If unsure, say N. 2075 2076config TEST_BLACKHOLE_DEV 2077 tristate "Test blackhole netdev functionality" 2078 depends on m && NET 2079 help 2080 This builds the "test_blackhole_dev" module that validates the 2081 data path through this blackhole netdev. 2082 2083 If unsure, say N. 2084 2085config FIND_BIT_BENCHMARK 2086 tristate "Test find_bit functions" 2087 help 2088 This builds the "test_find_bit" module that measure find_*_bit() 2089 functions performance. 2090 2091 If unsure, say N. 2092 2093config TEST_FIRMWARE 2094 tristate "Test firmware loading via userspace interface" 2095 depends on FW_LOADER 2096 help 2097 This builds the "test_firmware" module that creates a userspace 2098 interface for testing firmware loading. This can be used to 2099 control the triggering of firmware loading without needing an 2100 actual firmware-using device. The contents can be rechecked by 2101 userspace. 2102 2103 If unsure, say N. 2104 2105config TEST_SYSCTL 2106 tristate "sysctl test driver" 2107 depends on PROC_SYSCTL 2108 help 2109 This builds the "test_sysctl" module. This driver enables to test the 2110 proc sysctl interfaces available to drivers safely without affecting 2111 production knobs which might alter system functionality. 2112 2113 If unsure, say N. 2114 2115config SYSCTL_KUNIT_TEST 2116 tristate "KUnit test for sysctl" 2117 depends on KUNIT 2118 help 2119 This builds the proc sysctl unit test, which runs on boot. 2120 Tests the API contract and implementation correctness of sysctl. 2121 For more information on KUnit and unit tests in general please refer 2122 to the KUnit documentation in Documentation/dev-tools/kunit/. 2123 2124 If unsure, say N. 2125 2126config LIST_KUNIT_TEST 2127 tristate "KUnit Test for Kernel Linked-list structures" 2128 depends on KUNIT 2129 help 2130 This builds the linked list KUnit test suite. 2131 It tests that the API and basic functionality of the list_head type 2132 and associated macros. 2133 2134 KUnit tests run during boot and output the results to the debug log 2135 in TAP format (http://testanything.org/). Only useful for kernel devs 2136 running the KUnit test harness, and not intended for inclusion into a 2137 production build. 2138 2139 For more information on KUnit and unit tests in general please refer 2140 to the KUnit documentation in Documentation/dev-tools/kunit/. 2141 2142 If unsure, say N. 2143 2144config LINEAR_RANGES_TEST 2145 tristate "KUnit test for linear_ranges" 2146 depends on KUNIT 2147 select LINEAR_RANGES 2148 help 2149 This builds the linear_ranges unit test, which runs on boot. 2150 Tests the linear_ranges logic correctness. 2151 For more information on KUnit and unit tests in general please refer 2152 to the KUnit documentation in Documentation/dev-tools/kunit/. 2153 2154 If unsure, say N. 2155 2156config TEST_UDELAY 2157 tristate "udelay test driver" 2158 help 2159 This builds the "udelay_test" module that helps to make sure 2160 that udelay() is working properly. 2161 2162 If unsure, say N. 2163 2164config TEST_STATIC_KEYS 2165 tristate "Test static keys" 2166 depends on m 2167 help 2168 Test the static key interfaces. 2169 2170 If unsure, say N. 2171 2172config TEST_KMOD 2173 tristate "kmod stress tester" 2174 depends on m 2175 depends on NETDEVICES && NET_CORE && INET # for TUN 2176 depends on BLOCK 2177 select TEST_LKM 2178 select XFS_FS 2179 select TUN 2180 select BTRFS_FS 2181 help 2182 Test the kernel's module loading mechanism: kmod. kmod implements 2183 support to load modules using the Linux kernel's usermode helper. 2184 This test provides a series of tests against kmod. 2185 2186 Although technically you can either build test_kmod as a module or 2187 into the kernel we disallow building it into the kernel since 2188 it stress tests request_module() and this will very likely cause 2189 some issues by taking over precious threads available from other 2190 module load requests, ultimately this could be fatal. 2191 2192 To run tests run: 2193 2194 tools/testing/selftests/kmod/kmod.sh --help 2195 2196 If unsure, say N. 2197 2198config TEST_DEBUG_VIRTUAL 2199 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 2200 depends on DEBUG_VIRTUAL 2201 help 2202 Test the kernel's ability to detect incorrect calls to 2203 virt_to_phys() done against the non-linear part of the 2204 kernel's virtual address map. 2205 2206 If unsure, say N. 2207 2208config TEST_MEMCAT_P 2209 tristate "Test memcat_p() helper function" 2210 help 2211 Test the memcat_p() helper for correctly merging two 2212 pointer arrays together. 2213 2214 If unsure, say N. 2215 2216config TEST_LIVEPATCH 2217 tristate "Test livepatching" 2218 default n 2219 depends on DYNAMIC_DEBUG 2220 depends on LIVEPATCH 2221 depends on m 2222 help 2223 Test kernel livepatching features for correctness. The tests will 2224 load test modules that will be livepatched in various scenarios. 2225 2226 To run all the livepatching tests: 2227 2228 make -C tools/testing/selftests TARGETS=livepatch run_tests 2229 2230 Alternatively, individual tests may be invoked: 2231 2232 tools/testing/selftests/livepatch/test-callbacks.sh 2233 tools/testing/selftests/livepatch/test-livepatch.sh 2234 tools/testing/selftests/livepatch/test-shadow-vars.sh 2235 2236 If unsure, say N. 2237 2238config TEST_OBJAGG 2239 tristate "Perform selftest on object aggreration manager" 2240 default n 2241 depends on OBJAGG 2242 help 2243 Enable this option to test object aggregation manager on boot 2244 (or module load). 2245 2246 2247config TEST_STACKINIT 2248 tristate "Test level of stack variable initialization" 2249 help 2250 Test if the kernel is zero-initializing stack variables and 2251 padding. Coverage is controlled by compiler flags, 2252 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2253 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2254 2255 If unsure, say N. 2256 2257config TEST_MEMINIT 2258 tristate "Test heap/page initialization" 2259 help 2260 Test if the kernel is zero-initializing heap and page allocations. 2261 This can be useful to test init_on_alloc and init_on_free features. 2262 2263 If unsure, say N. 2264 2265config TEST_HMM 2266 tristate "Test HMM (Heterogeneous Memory Management)" 2267 depends on TRANSPARENT_HUGEPAGE 2268 depends on DEVICE_PRIVATE 2269 select HMM_MIRROR 2270 select MMU_NOTIFIER 2271 help 2272 This is a pseudo device driver solely for testing HMM. 2273 Say M here if you want to build the HMM test module. 2274 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests. 2275 2276 If unsure, say N. 2277 2278endif # RUNTIME_TESTING_MENU 2279 2280config MEMTEST 2281 bool "Memtest" 2282 ---help--- 2283 This option adds a kernel parameter 'memtest', which allows memtest 2284 to be set. 2285 memtest=0, mean disabled; -- default 2286 memtest=1, mean do 1 test pattern; 2287 ... 2288 memtest=17, mean do 17 test patterns. 2289 If you are unsure how to answer this question, answer N. 2290 2291 2292 2293config HYPERV_TESTING 2294 bool "Microsoft Hyper-V driver testing" 2295 default n 2296 depends on HYPERV && DEBUG_FS 2297 help 2298 Select this option to enable Hyper-V vmbus testing. 2299 2300endmenu # "Kernel Testing and Coverage" 2301 2302endmenu # Kernel hacking 2303