1# SPDX-License-Identifier: GPL-2.0-only 2menu "Kernel hacking" 3 4menu "printk and dmesg options" 5 6config PRINTK_TIME 7 bool "Show timing information on printks" 8 depends on PRINTK 9 help 10 Selecting this option causes time stamps of the printk() 11 messages to be added to the output of the syslog() system 12 call and at the console. 13 14 The timestamp is always recorded internally, and exported 15 to /dev/kmsg. This flag just specifies if the timestamp should 16 be included, not that the timestamp is recorded. 17 18 The behavior is also controlled by the kernel command line 19 parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst 20 21config PRINTK_CALLER 22 bool "Show caller information on printks" 23 depends on PRINTK 24 help 25 Selecting this option causes printk() to add a caller "thread id" (if 26 in task context) or a caller "processor id" (if not in task context) 27 to every message. 28 29 This option is intended for environments where multiple threads 30 concurrently call printk() for many times, for it is difficult to 31 interpret without knowing where these lines (or sometimes individual 32 line which was divided into multiple lines due to race) came from. 33 34 Since toggling after boot makes the code racy, currently there is 35 no option to enable/disable at the kernel command line parameter or 36 sysfs interface. 37 38config CONSOLE_LOGLEVEL_DEFAULT 39 int "Default console loglevel (1-15)" 40 range 1 15 41 default "7" 42 help 43 Default loglevel to determine what will be printed on the console. 44 45 Setting a default here is equivalent to passing in loglevel=<x> in 46 the kernel bootargs. loglevel=<x> continues to override whatever 47 value is specified here as well. 48 49 Note: This does not affect the log level of un-prefixed printk() 50 usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT 51 option. 52 53config CONSOLE_LOGLEVEL_QUIET 54 int "quiet console loglevel (1-15)" 55 range 1 15 56 default "4" 57 help 58 loglevel to use when "quiet" is passed on the kernel commandline. 59 60 When "quiet" is passed on the kernel commandline this loglevel 61 will be used as the loglevel. IOW passing "quiet" will be the 62 equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>" 63 64config MESSAGE_LOGLEVEL_DEFAULT 65 int "Default message log level (1-7)" 66 range 1 7 67 default "4" 68 help 69 Default log level for printk statements with no specified priority. 70 71 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks 72 that are auditing their logs closely may want to set it to a lower 73 priority. 74 75 Note: This does not affect what message level gets printed on the console 76 by default. To change that, use loglevel=<x> in the kernel bootargs, 77 or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value. 78 79config BOOT_PRINTK_DELAY 80 bool "Delay each boot printk message by N milliseconds" 81 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY 82 help 83 This build option allows you to read kernel boot messages 84 by inserting a short delay after each one. The delay is 85 specified in milliseconds on the kernel command line, 86 using "boot_delay=N". 87 88 It is likely that you would also need to use "lpj=M" to preset 89 the "loops per jiffie" value. 90 See a previous boot log for the "lpj" value to use for your 91 system, and then set "lpj=M" before setting "boot_delay=N". 92 NOTE: Using this option may adversely affect SMP systems. 93 I.e., processors other than the first one may not boot up. 94 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect 95 what it believes to be lockup conditions. 96 97config DYNAMIC_DEBUG 98 bool "Enable dynamic printk() support" 99 default n 100 depends on PRINTK 101 depends on DEBUG_FS 102 help 103 104 Compiles debug level messages into the kernel, which would not 105 otherwise be available at runtime. These messages can then be 106 enabled/disabled based on various levels of scope - per source file, 107 function, module, format string, and line number. This mechanism 108 implicitly compiles in all pr_debug() and dev_dbg() calls, which 109 enlarges the kernel text size by about 2%. 110 111 If a source file is compiled with DEBUG flag set, any 112 pr_debug() calls in it are enabled by default, but can be 113 disabled at runtime as below. Note that DEBUG flag is 114 turned on by many CONFIG_*DEBUG* options. 115 116 Usage: 117 118 Dynamic debugging is controlled via the 'dynamic_debug/control' file, 119 which is contained in the 'debugfs' filesystem. Thus, the debugfs 120 filesystem must first be mounted before making use of this feature. 121 We refer the control file as: <debugfs>/dynamic_debug/control. This 122 file contains a list of the debug statements that can be enabled. The 123 format for each line of the file is: 124 125 filename:lineno [module]function flags format 126 127 filename : source file of the debug statement 128 lineno : line number of the debug statement 129 module : module that contains the debug statement 130 function : function that contains the debug statement 131 flags : '=p' means the line is turned 'on' for printing 132 format : the format used for the debug statement 133 134 From a live system: 135 136 nullarbor:~ # cat <debugfs>/dynamic_debug/control 137 # filename:lineno [module]function flags format 138 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012" 139 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012" 140 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012" 141 142 Example usage: 143 144 // enable the message at line 1603 of file svcsock.c 145 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' > 146 <debugfs>/dynamic_debug/control 147 148 // enable all the messages in file svcsock.c 149 nullarbor:~ # echo -n 'file svcsock.c +p' > 150 <debugfs>/dynamic_debug/control 151 152 // enable all the messages in the NFS server module 153 nullarbor:~ # echo -n 'module nfsd +p' > 154 <debugfs>/dynamic_debug/control 155 156 // enable all 12 messages in the function svc_process() 157 nullarbor:~ # echo -n 'func svc_process +p' > 158 <debugfs>/dynamic_debug/control 159 160 // disable all 12 messages in the function svc_process() 161 nullarbor:~ # echo -n 'func svc_process -p' > 162 <debugfs>/dynamic_debug/control 163 164 See Documentation/admin-guide/dynamic-debug-howto.rst for additional 165 information. 166 167endmenu # "printk and dmesg options" 168 169menu "Compile-time checks and compiler options" 170 171config DEBUG_INFO 172 bool "Compile the kernel with debug info" 173 depends on DEBUG_KERNEL && !COMPILE_TEST 174 help 175 If you say Y here the resulting kernel image will include 176 debugging info resulting in a larger kernel image. 177 This adds debug symbols to the kernel and modules (gcc -g), and 178 is needed if you intend to use kernel crashdump or binary object 179 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 180 Say Y here only if you plan to debug the kernel. 181 182 If unsure, say N. 183 184config DEBUG_INFO_REDUCED 185 bool "Reduce debugging information" 186 depends on DEBUG_INFO 187 help 188 If you say Y here gcc is instructed to generate less debugging 189 information for structure types. This means that tools that 190 need full debugging information (like kgdb or systemtap) won't 191 be happy. But if you merely need debugging information to 192 resolve line numbers there is no loss. Advantage is that 193 build directory object sizes shrink dramatically over a full 194 DEBUG_INFO build and compile times are reduced too. 195 Only works with newer gcc versions. 196 197config DEBUG_INFO_SPLIT 198 bool "Produce split debuginfo in .dwo files" 199 depends on DEBUG_INFO 200 depends on $(cc-option,-gsplit-dwarf) 201 help 202 Generate debug info into separate .dwo files. This significantly 203 reduces the build directory size for builds with DEBUG_INFO, 204 because it stores the information only once on disk in .dwo 205 files instead of multiple times in object files and executables. 206 In addition the debug information is also compressed. 207 208 Requires recent gcc (4.7+) and recent gdb/binutils. 209 Any tool that packages or reads debug information would need 210 to know about the .dwo files and include them. 211 Incompatible with older versions of ccache. 212 213config DEBUG_INFO_DWARF4 214 bool "Generate dwarf4 debuginfo" 215 depends on DEBUG_INFO 216 depends on $(cc-option,-gdwarf-4) 217 help 218 Generate dwarf4 debug info. This requires recent versions 219 of gcc and gdb. It makes the debug information larger. 220 But it significantly improves the success of resolving 221 variables in gdb on optimized code. 222 223config DEBUG_INFO_BTF 224 bool "Generate BTF typeinfo" 225 depends on DEBUG_INFO 226 help 227 Generate deduplicated BTF type information from DWARF debug info. 228 Turning this on expects presence of pahole tool, which will convert 229 DWARF type info into equivalent deduplicated BTF type info. 230 231config GDB_SCRIPTS 232 bool "Provide GDB scripts for kernel debugging" 233 depends on DEBUG_INFO 234 help 235 This creates the required links to GDB helper scripts in the 236 build directory. If you load vmlinux into gdb, the helper 237 scripts will be automatically imported by gdb as well, and 238 additional functions are available to analyze a Linux kernel 239 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst 240 for further details. 241 242config ENABLE_MUST_CHECK 243 bool "Enable __must_check logic" 244 default y 245 help 246 Enable the __must_check logic in the kernel build. Disable this to 247 suppress the "warning: ignoring return value of 'foo', declared with 248 attribute warn_unused_result" messages. 249 250config FRAME_WARN 251 int "Warn for stack frames larger than (needs gcc 4.4)" 252 range 0 8192 253 default 2048 if GCC_PLUGIN_LATENT_ENTROPY 254 default 1280 if (!64BIT && PARISC) 255 default 1024 if (!64BIT && !PARISC) 256 default 2048 if 64BIT 257 help 258 Tell gcc to warn at build time for stack frames larger than this. 259 Setting this too low will cause a lot of warnings. 260 Setting it to 0 disables the warning. 261 Requires gcc 4.4 262 263config STRIP_ASM_SYMS 264 bool "Strip assembler-generated symbols during link" 265 default n 266 help 267 Strip internal assembler-generated symbols during a link (symbols 268 that look like '.Lxxx') so they don't pollute the output of 269 get_wchan() and suchlike. 270 271config READABLE_ASM 272 bool "Generate readable assembler code" 273 depends on DEBUG_KERNEL 274 help 275 Disable some compiler optimizations that tend to generate human unreadable 276 assembler output. This may make the kernel slightly slower, but it helps 277 to keep kernel developers who have to stare a lot at assembler listings 278 sane. 279 280config UNUSED_SYMBOLS 281 bool "Enable unused/obsolete exported symbols" 282 default y if X86 283 help 284 Unused but exported symbols make the kernel needlessly bigger. For 285 that reason most of these unused exports will soon be removed. This 286 option is provided temporarily to provide a transition period in case 287 some external kernel module needs one of these symbols anyway. If you 288 encounter such a case in your module, consider if you are actually 289 using the right API. (rationale: since nobody in the kernel is using 290 this in a module, there is a pretty good chance it's actually the 291 wrong interface to use). If you really need the symbol, please send a 292 mail to the linux kernel mailing list mentioning the symbol and why 293 you really need it, and what the merge plan to the mainline kernel for 294 your module is. 295 296config DEBUG_FS 297 bool "Debug Filesystem" 298 help 299 debugfs is a virtual file system that kernel developers use to put 300 debugging files into. Enable this option to be able to read and 301 write to these files. 302 303 For detailed documentation on the debugfs API, see 304 Documentation/filesystems/. 305 306 If unsure, say N. 307 308config HEADERS_INSTALL 309 bool "Install uapi headers to usr/include" 310 depends on !UML 311 help 312 This option will install uapi headers (headers exported to user-space) 313 into the usr/include directory for use during the kernel build. 314 This is unneeded for building the kernel itself, but needed for some 315 user-space program samples. It is also needed by some features such 316 as uapi header sanity checks. 317 318config HEADERS_CHECK 319 bool "Run sanity checks on uapi headers when building 'all'" 320 depends on HEADERS_INSTALL 321 help 322 This option will run basic sanity checks on uapi headers when 323 building the 'all' target, for example, ensure that they do not 324 attempt to include files which were not exported, etc. 325 326 If you're making modifications to header files which are 327 relevant for userspace, say 'Y'. 328 329config OPTIMIZE_INLINING 330 bool "Allow compiler to uninline functions marked 'inline'" 331 help 332 This option determines if the kernel forces gcc to inline the functions 333 developers have marked 'inline'. Doing so takes away freedom from gcc to 334 do what it thinks is best, which is desirable for the gcc 3.x series of 335 compilers. The gcc 4.x series have a rewritten inlining algorithm and 336 enabling this option will generate a smaller kernel there. Hopefully 337 this algorithm is so good that allowing gcc 4.x and above to make the 338 decision will become the default in the future. Until then this option 339 is there to test gcc for this. 340 341 If unsure, say N. 342 343config DEBUG_SECTION_MISMATCH 344 bool "Enable full Section mismatch analysis" 345 help 346 The section mismatch analysis checks if there are illegal 347 references from one section to another section. 348 During linktime or runtime, some sections are dropped; 349 any use of code/data previously in these sections would 350 most likely result in an oops. 351 In the code, functions and variables are annotated with 352 __init,, etc. (see the full list in include/linux/init.h), 353 which results in the code/data being placed in specific sections. 354 The section mismatch analysis is always performed after a full 355 kernel build, and enabling this option causes the following 356 additional step to occur: 357 - Add the option -fno-inline-functions-called-once to gcc commands. 358 When inlining a function annotated with __init in a non-init 359 function, we would lose the section information and thus 360 the analysis would not catch the illegal reference. 361 This option tells gcc to inline less (but it does result in 362 a larger kernel). 363 364config SECTION_MISMATCH_WARN_ONLY 365 bool "Make section mismatch errors non-fatal" 366 default y 367 help 368 If you say N here, the build process will fail if there are any 369 section mismatch, instead of just throwing warnings. 370 371 If unsure, say Y. 372 373# 374# Select this config option from the architecture Kconfig, if it 375# is preferred to always offer frame pointers as a config 376# option on the architecture (regardless of KERNEL_DEBUG): 377# 378config ARCH_WANT_FRAME_POINTERS 379 bool 380 381config FRAME_POINTER 382 bool "Compile the kernel with frame pointers" 383 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS 384 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 385 help 386 If you say Y here the resulting kernel image will be slightly 387 larger and slower, but it gives very useful debugging information 388 in case of kernel bugs. (precise oopses/stacktraces/warnings) 389 390config STACK_VALIDATION 391 bool "Compile-time stack metadata validation" 392 depends on HAVE_STACK_VALIDATION 393 default n 394 help 395 Add compile-time checks to validate stack metadata, including frame 396 pointers (if CONFIG_FRAME_POINTER is enabled). This helps ensure 397 that runtime stack traces are more reliable. 398 399 This is also a prerequisite for generation of ORC unwind data, which 400 is needed for CONFIG_UNWINDER_ORC. 401 402 For more information, see 403 tools/objtool/Documentation/stack-validation.txt. 404 405config DEBUG_FORCE_WEAK_PER_CPU 406 bool "Force weak per-cpu definitions" 407 depends on DEBUG_KERNEL 408 help 409 s390 and alpha require percpu variables in modules to be 410 defined weak to work around addressing range issue which 411 puts the following two restrictions on percpu variable 412 definitions. 413 414 1. percpu symbols must be unique whether static or not 415 2. percpu variables can't be defined inside a function 416 417 To ensure that generic code follows the above rules, this 418 option forces all percpu variables to be defined as weak. 419 420endmenu # "Compiler options" 421 422config MAGIC_SYSRQ 423 bool "Magic SysRq key" 424 depends on !UML 425 help 426 If you say Y here, you will have some control over the system even 427 if the system crashes for example during kernel debugging (e.g., you 428 will be able to flush the buffer cache to disk, reboot the system 429 immediately or dump some status information). This is accomplished 430 by pressing various keys while holding SysRq (Alt+PrintScreen). It 431 also works on a serial console (on PC hardware at least), if you 432 send a BREAK and then within 5 seconds a command keypress. The 433 keys are documented in <file:Documentation/admin-guide/sysrq.rst>. 434 Don't say Y unless you really know what this hack does. 435 436config MAGIC_SYSRQ_DEFAULT_ENABLE 437 hex "Enable magic SysRq key functions by default" 438 depends on MAGIC_SYSRQ 439 default 0x1 440 help 441 Specifies which SysRq key functions are enabled by default. 442 This may be set to 1 or 0 to enable or disable them all, or 443 to a bitmask as described in Documentation/admin-guide/sysrq.rst. 444 445config MAGIC_SYSRQ_SERIAL 446 bool "Enable magic SysRq key over serial" 447 depends on MAGIC_SYSRQ 448 default y 449 help 450 Many embedded boards have a disconnected TTL level serial which can 451 generate some garbage that can lead to spurious false sysrq detects. 452 This option allows you to decide whether you want to enable the 453 magic SysRq key. 454 455config DEBUG_KERNEL 456 bool "Kernel debugging" 457 help 458 Say Y here if you are developing drivers or trying to debug and 459 identify kernel problems. 460 461config DEBUG_MISC 462 bool "Miscellaneous debug code" 463 default DEBUG_KERNEL 464 depends on DEBUG_KERNEL 465 help 466 Say Y here if you need to enable miscellaneous debug code that should 467 be under a more specific debug option but isn't. 468 469 470menu "Memory Debugging" 471 472source "mm/Kconfig.debug" 473 474config DEBUG_OBJECTS 475 bool "Debug object operations" 476 depends on DEBUG_KERNEL 477 help 478 If you say Y here, additional code will be inserted into the 479 kernel to track the life time of various objects and validate 480 the operations on those objects. 481 482config DEBUG_OBJECTS_SELFTEST 483 bool "Debug objects selftest" 484 depends on DEBUG_OBJECTS 485 help 486 This enables the selftest of the object debug code. 487 488config DEBUG_OBJECTS_FREE 489 bool "Debug objects in freed memory" 490 depends on DEBUG_OBJECTS 491 help 492 This enables checks whether a k/v free operation frees an area 493 which contains an object which has not been deactivated 494 properly. This can make kmalloc/kfree-intensive workloads 495 much slower. 496 497config DEBUG_OBJECTS_TIMERS 498 bool "Debug timer objects" 499 depends on DEBUG_OBJECTS 500 help 501 If you say Y here, additional code will be inserted into the 502 timer routines to track the life time of timer objects and 503 validate the timer operations. 504 505config DEBUG_OBJECTS_WORK 506 bool "Debug work objects" 507 depends on DEBUG_OBJECTS 508 help 509 If you say Y here, additional code will be inserted into the 510 work queue routines to track the life time of work objects and 511 validate the work operations. 512 513config DEBUG_OBJECTS_RCU_HEAD 514 bool "Debug RCU callbacks objects" 515 depends on DEBUG_OBJECTS 516 help 517 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 518 519config DEBUG_OBJECTS_PERCPU_COUNTER 520 bool "Debug percpu counter objects" 521 depends on DEBUG_OBJECTS 522 help 523 If you say Y here, additional code will be inserted into the 524 percpu counter routines to track the life time of percpu counter 525 objects and validate the percpu counter operations. 526 527config DEBUG_OBJECTS_ENABLE_DEFAULT 528 int "debug_objects bootup default value (0-1)" 529 range 0 1 530 default "1" 531 depends on DEBUG_OBJECTS 532 help 533 Debug objects boot parameter default value 534 535config DEBUG_SLAB 536 bool "Debug slab memory allocations" 537 depends on DEBUG_KERNEL && SLAB 538 help 539 Say Y here to have the kernel do limited verification on memory 540 allocation as well as poisoning memory on free to catch use of freed 541 memory. This can make kmalloc/kfree-intensive workloads much slower. 542 543config SLUB_DEBUG_ON 544 bool "SLUB debugging on by default" 545 depends on SLUB && SLUB_DEBUG 546 default n 547 help 548 Boot with debugging on by default. SLUB boots by default with 549 the runtime debug capabilities switched off. Enabling this is 550 equivalent to specifying the "slub_debug" parameter on boot. 551 There is no support for more fine grained debug control like 552 possible with slub_debug=xxx. SLUB debugging may be switched 553 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying 554 "slub_debug=-". 555 556config SLUB_STATS 557 default n 558 bool "Enable SLUB performance statistics" 559 depends on SLUB && SYSFS 560 help 561 SLUB statistics are useful to debug SLUBs allocation behavior in 562 order find ways to optimize the allocator. This should never be 563 enabled for production use since keeping statistics slows down 564 the allocator by a few percentage points. The slabinfo command 565 supports the determination of the most active slabs to figure 566 out which slabs are relevant to a particular load. 567 Try running: slabinfo -DA 568 569config HAVE_DEBUG_KMEMLEAK 570 bool 571 572config DEBUG_KMEMLEAK 573 bool "Kernel memory leak detector" 574 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK 575 select DEBUG_FS 576 select STACKTRACE if STACKTRACE_SUPPORT 577 select KALLSYMS 578 select CRC32 579 help 580 Say Y here if you want to enable the memory leak 581 detector. The memory allocation/freeing is traced in a way 582 similar to the Boehm's conservative garbage collector, the 583 difference being that the orphan objects are not freed but 584 only shown in /sys/kernel/debug/kmemleak. Enabling this 585 feature will introduce an overhead to memory 586 allocations. See Documentation/dev-tools/kmemleak.rst for more 587 details. 588 589 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances 590 of finding leaks due to the slab objects poisoning. 591 592 In order to access the kmemleak file, debugfs needs to be 593 mounted (usually at /sys/kernel/debug). 594 595config DEBUG_KMEMLEAK_EARLY_LOG_SIZE 596 int "Maximum kmemleak early log entries" 597 depends on DEBUG_KMEMLEAK 598 range 200 40000 599 default 400 600 help 601 Kmemleak must track all the memory allocations to avoid 602 reporting false positives. Since memory may be allocated or 603 freed before kmemleak is initialised, an early log buffer is 604 used to store these actions. If kmemleak reports "early log 605 buffer exceeded", please increase this value. 606 607config DEBUG_KMEMLEAK_TEST 608 tristate "Simple test for the kernel memory leak detector" 609 depends on DEBUG_KMEMLEAK && m 610 help 611 This option enables a module that explicitly leaks memory. 612 613 If unsure, say N. 614 615config DEBUG_KMEMLEAK_DEFAULT_OFF 616 bool "Default kmemleak to off" 617 depends on DEBUG_KMEMLEAK 618 help 619 Say Y here to disable kmemleak by default. It can then be enabled 620 on the command line via kmemleak=on. 621 622config DEBUG_KMEMLEAK_AUTO_SCAN 623 bool "Enable kmemleak auto scan thread on boot up" 624 default y 625 depends on DEBUG_KMEMLEAK 626 help 627 Depending on the cpu, kmemleak scan may be cpu intensive and can 628 stall user tasks at times. This option enables/disables automatic 629 kmemleak scan at boot up. 630 631 Say N here to disable kmemleak auto scan thread to stop automatic 632 scanning. Disabling this option disables automatic reporting of 633 memory leaks. 634 635 If unsure, say Y. 636 637config DEBUG_STACK_USAGE 638 bool "Stack utilization instrumentation" 639 depends on DEBUG_KERNEL && !IA64 640 help 641 Enables the display of the minimum amount of free stack which each 642 task has ever had available in the sysrq-T and sysrq-P debug output. 643 644 This option will slow down process creation somewhat. 645 646config DEBUG_VM 647 bool "Debug VM" 648 depends on DEBUG_KERNEL 649 help 650 Enable this to turn on extended checks in the virtual-memory system 651 that may impact performance. 652 653 If unsure, say N. 654 655config DEBUG_VM_VMACACHE 656 bool "Debug VMA caching" 657 depends on DEBUG_VM 658 help 659 Enable this to turn on VMA caching debug information. Doing so 660 can cause significant overhead, so only enable it in non-production 661 environments. 662 663 If unsure, say N. 664 665config DEBUG_VM_RB 666 bool "Debug VM red-black trees" 667 depends on DEBUG_VM 668 help 669 Enable VM red-black tree debugging information and extra validations. 670 671 If unsure, say N. 672 673config DEBUG_VM_PGFLAGS 674 bool "Debug page-flags operations" 675 depends on DEBUG_VM 676 help 677 Enables extra validation on page flags operations. 678 679 If unsure, say N. 680 681config ARCH_HAS_DEBUG_VIRTUAL 682 bool 683 684config DEBUG_VIRTUAL 685 bool "Debug VM translations" 686 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL 687 help 688 Enable some costly sanity checks in virtual to page code. This can 689 catch mistakes with virt_to_page() and friends. 690 691 If unsure, say N. 692 693config DEBUG_NOMMU_REGIONS 694 bool "Debug the global anon/private NOMMU mapping region tree" 695 depends on DEBUG_KERNEL && !MMU 696 help 697 This option causes the global tree of anonymous and private mapping 698 regions to be regularly checked for invalid topology. 699 700config DEBUG_MEMORY_INIT 701 bool "Debug memory initialisation" if EXPERT 702 default !EXPERT 703 help 704 Enable this for additional checks during memory initialisation. 705 The sanity checks verify aspects of the VM such as the memory model 706 and other information provided by the architecture. Verbose 707 information will be printed at KERN_DEBUG loglevel depending 708 on the mminit_loglevel= command-line option. 709 710 If unsure, say Y 711 712config MEMORY_NOTIFIER_ERROR_INJECT 713 tristate "Memory hotplug notifier error injection module" 714 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION 715 help 716 This option provides the ability to inject artificial errors to 717 memory hotplug notifier chain callbacks. It is controlled through 718 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 719 720 If the notifier call chain should be failed with some events 721 notified, write the error code to "actions/<notifier event>/error". 722 723 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 724 725 # cd /sys/kernel/debug/notifier-error-inject/memory 726 # echo -12 > actions/MEM_GOING_OFFLINE/error 727 # echo offline > /sys/devices/system/memory/memoryXXX/state 728 bash: echo: write error: Cannot allocate memory 729 730 To compile this code as a module, choose M here: the module will 731 be called memory-notifier-error-inject. 732 733 If unsure, say N. 734 735config DEBUG_PER_CPU_MAPS 736 bool "Debug access to per_cpu maps" 737 depends on DEBUG_KERNEL 738 depends on SMP 739 help 740 Say Y to verify that the per_cpu map being accessed has 741 been set up. This adds a fair amount of code to kernel memory 742 and decreases performance. 743 744 Say N if unsure. 745 746config DEBUG_HIGHMEM 747 bool "Highmem debugging" 748 depends on DEBUG_KERNEL && HIGHMEM 749 help 750 This option enables additional error checking for high memory 751 systems. Disable for production systems. 752 753config HAVE_DEBUG_STACKOVERFLOW 754 bool 755 756config DEBUG_STACKOVERFLOW 757 bool "Check for stack overflows" 758 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 759 ---help--- 760 Say Y here if you want to check for overflows of kernel, IRQ 761 and exception stacks (if your architecture uses them). This 762 option will show detailed messages if free stack space drops 763 below a certain limit. 764 765 These kinds of bugs usually occur when call-chains in the 766 kernel get too deep, especially when interrupts are 767 involved. 768 769 Use this in cases where you see apparently random memory 770 corruption, especially if it appears in 'struct thread_info' 771 772 If in doubt, say "N". 773 774source "lib/Kconfig.kasan" 775 776endmenu # "Memory Debugging" 777 778config ARCH_HAS_KCOV 779 bool 780 help 781 An architecture should select this when it can successfully 782 build and run with CONFIG_KCOV. This typically requires 783 disabling instrumentation for some early boot code. 784 785config CC_HAS_SANCOV_TRACE_PC 786 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 787 788config KCOV 789 bool "Code coverage for fuzzing" 790 depends on ARCH_HAS_KCOV 791 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 792 select DEBUG_FS 793 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 794 help 795 KCOV exposes kernel code coverage information in a form suitable 796 for coverage-guided fuzzing (randomized testing). 797 798 If RANDOMIZE_BASE is enabled, PC values will not be stable across 799 different machines and across reboots. If you need stable PC values, 800 disable RANDOMIZE_BASE. 801 802 For more details, see Documentation/dev-tools/kcov.rst. 803 804config KCOV_ENABLE_COMPARISONS 805 bool "Enable comparison operands collection by KCOV" 806 depends on KCOV 807 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 808 help 809 KCOV also exposes operands of every comparison in the instrumented 810 code along with operand sizes and PCs of the comparison instructions. 811 These operands can be used by fuzzing engines to improve the quality 812 of fuzzing coverage. 813 814config KCOV_INSTRUMENT_ALL 815 bool "Instrument all code by default" 816 depends on KCOV 817 default y 818 help 819 If you are doing generic system call fuzzing (like e.g. syzkaller), 820 then you will want to instrument the whole kernel and you should 821 say y here. If you are doing more targeted fuzzing (like e.g. 822 filesystem fuzzing with AFL) then you will want to enable coverage 823 for more specific subsets of files, and should say n here. 824 825config DEBUG_SHIRQ 826 bool "Debug shared IRQ handlers" 827 depends on DEBUG_KERNEL 828 help 829 Enable this to generate a spurious interrupt as soon as a shared 830 interrupt handler is registered, and just before one is deregistered. 831 Drivers ought to be able to handle interrupts coming in at those 832 points; some don't and need to be caught. 833 834menu "Debug Lockups and Hangs" 835 836config LOCKUP_DETECTOR 837 bool 838 839config SOFTLOCKUP_DETECTOR 840 bool "Detect Soft Lockups" 841 depends on DEBUG_KERNEL && !S390 842 select LOCKUP_DETECTOR 843 help 844 Say Y here to enable the kernel to act as a watchdog to detect 845 soft lockups. 846 847 Softlockups are bugs that cause the kernel to loop in kernel 848 mode for more than 20 seconds, without giving other tasks a 849 chance to run. The current stack trace is displayed upon 850 detection and the system will stay locked up. 851 852config BOOTPARAM_SOFTLOCKUP_PANIC 853 bool "Panic (Reboot) On Soft Lockups" 854 depends on SOFTLOCKUP_DETECTOR 855 help 856 Say Y here to enable the kernel to panic on "soft lockups", 857 which are bugs that cause the kernel to loop in kernel 858 mode for more than 20 seconds (configurable using the watchdog_thresh 859 sysctl), without giving other tasks a chance to run. 860 861 The panic can be used in combination with panic_timeout, 862 to cause the system to reboot automatically after a 863 lockup has been detected. This feature is useful for 864 high-availability systems that have uptime guarantees and 865 where a lockup must be resolved ASAP. 866 867 Say N if unsure. 868 869config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE 870 int 871 depends on SOFTLOCKUP_DETECTOR 872 range 0 1 873 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC 874 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC 875 876config HARDLOCKUP_DETECTOR_PERF 877 bool 878 select SOFTLOCKUP_DETECTOR 879 880# 881# Enables a timestamp based low pass filter to compensate for perf based 882# hard lockup detection which runs too fast due to turbo modes. 883# 884config HARDLOCKUP_CHECK_TIMESTAMP 885 bool 886 887# 888# arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard 889# lockup detector rather than the perf based detector. 890# 891config HARDLOCKUP_DETECTOR 892 bool "Detect Hard Lockups" 893 depends on DEBUG_KERNEL && !S390 894 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH 895 select LOCKUP_DETECTOR 896 select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF 897 select HARDLOCKUP_DETECTOR_ARCH if HAVE_HARDLOCKUP_DETECTOR_ARCH 898 help 899 Say Y here to enable the kernel to act as a watchdog to detect 900 hard lockups. 901 902 Hardlockups are bugs that cause the CPU to loop in kernel mode 903 for more than 10 seconds, without letting other interrupts have a 904 chance to run. The current stack trace is displayed upon detection 905 and the system will stay locked up. 906 907config BOOTPARAM_HARDLOCKUP_PANIC 908 bool "Panic (Reboot) On Hard Lockups" 909 depends on HARDLOCKUP_DETECTOR 910 help 911 Say Y here to enable the kernel to panic on "hard lockups", 912 which are bugs that cause the kernel to loop in kernel 913 mode with interrupts disabled for more than 10 seconds (configurable 914 using the watchdog_thresh sysctl). 915 916 Say N if unsure. 917 918config BOOTPARAM_HARDLOCKUP_PANIC_VALUE 919 int 920 depends on HARDLOCKUP_DETECTOR 921 range 0 1 922 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC 923 default 1 if BOOTPARAM_HARDLOCKUP_PANIC 924 925config DETECT_HUNG_TASK 926 bool "Detect Hung Tasks" 927 depends on DEBUG_KERNEL 928 default SOFTLOCKUP_DETECTOR 929 help 930 Say Y here to enable the kernel to detect "hung tasks", 931 which are bugs that cause the task to be stuck in 932 uninterruptible "D" state indefinitely. 933 934 When a hung task is detected, the kernel will print the 935 current stack trace (which you should report), but the 936 task will stay in uninterruptible state. If lockdep is 937 enabled then all held locks will also be reported. This 938 feature has negligible overhead. 939 940config DEFAULT_HUNG_TASK_TIMEOUT 941 int "Default timeout for hung task detection (in seconds)" 942 depends on DETECT_HUNG_TASK 943 default 120 944 help 945 This option controls the default timeout (in seconds) used 946 to determine when a task has become non-responsive and should 947 be considered hung. 948 949 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 950 sysctl or by writing a value to 951 /proc/sys/kernel/hung_task_timeout_secs. 952 953 A timeout of 0 disables the check. The default is two minutes. 954 Keeping the default should be fine in most cases. 955 956config BOOTPARAM_HUNG_TASK_PANIC 957 bool "Panic (Reboot) On Hung Tasks" 958 depends on DETECT_HUNG_TASK 959 help 960 Say Y here to enable the kernel to panic on "hung tasks", 961 which are bugs that cause the kernel to leave a task stuck 962 in uninterruptible "D" state. 963 964 The panic can be used in combination with panic_timeout, 965 to cause the system to reboot automatically after a 966 hung task has been detected. This feature is useful for 967 high-availability systems that have uptime guarantees and 968 where a hung tasks must be resolved ASAP. 969 970 Say N if unsure. 971 972config BOOTPARAM_HUNG_TASK_PANIC_VALUE 973 int 974 depends on DETECT_HUNG_TASK 975 range 0 1 976 default 0 if !BOOTPARAM_HUNG_TASK_PANIC 977 default 1 if BOOTPARAM_HUNG_TASK_PANIC 978 979config WQ_WATCHDOG 980 bool "Detect Workqueue Stalls" 981 depends on DEBUG_KERNEL 982 help 983 Say Y here to enable stall detection on workqueues. If a 984 worker pool doesn't make forward progress on a pending work 985 item for over a given amount of time, 30s by default, a 986 warning message is printed along with dump of workqueue 987 state. This can be configured through kernel parameter 988 "workqueue.watchdog_thresh" and its sysfs counterpart. 989 990endmenu # "Debug lockups and hangs" 991 992config PANIC_ON_OOPS 993 bool "Panic on Oops" 994 help 995 Say Y here to enable the kernel to panic when it oopses. This 996 has the same effect as setting oops=panic on the kernel command 997 line. 998 999 This feature is useful to ensure that the kernel does not do 1000 anything erroneous after an oops which could result in data 1001 corruption or other issues. 1002 1003 Say N if unsure. 1004 1005config PANIC_ON_OOPS_VALUE 1006 int 1007 range 0 1 1008 default 0 if !PANIC_ON_OOPS 1009 default 1 if PANIC_ON_OOPS 1010 1011config PANIC_TIMEOUT 1012 int "panic timeout" 1013 default 0 1014 help 1015 Set the timeout value (in seconds) until a reboot occurs when the 1016 the kernel panics. If n = 0, then we wait forever. A timeout 1017 value n > 0 will wait n seconds before rebooting, while a timeout 1018 value n < 0 will reboot immediately. 1019 1020config SCHED_DEBUG 1021 bool "Collect scheduler debugging info" 1022 depends on DEBUG_KERNEL && PROC_FS 1023 default y 1024 help 1025 If you say Y here, the /proc/sched_debug file will be provided 1026 that can help debug the scheduler. The runtime overhead of this 1027 option is minimal. 1028 1029config SCHED_INFO 1030 bool 1031 default n 1032 1033config SCHEDSTATS 1034 bool "Collect scheduler statistics" 1035 depends on DEBUG_KERNEL && PROC_FS 1036 select SCHED_INFO 1037 help 1038 If you say Y here, additional code will be inserted into the 1039 scheduler and related routines to collect statistics about 1040 scheduler behavior and provide them in /proc/schedstat. These 1041 stats may be useful for both tuning and debugging the scheduler 1042 If you aren't debugging the scheduler or trying to tune a specific 1043 application, you can say N to avoid the very slight overhead 1044 this adds. 1045 1046config SCHED_STACK_END_CHECK 1047 bool "Detect stack corruption on calls to schedule()" 1048 depends on DEBUG_KERNEL 1049 default n 1050 help 1051 This option checks for a stack overrun on calls to schedule(). 1052 If the stack end location is found to be over written always panic as 1053 the content of the corrupted region can no longer be trusted. 1054 This is to ensure no erroneous behaviour occurs which could result in 1055 data corruption or a sporadic crash at a later stage once the region 1056 is examined. The runtime overhead introduced is minimal. 1057 1058config DEBUG_TIMEKEEPING 1059 bool "Enable extra timekeeping sanity checking" 1060 help 1061 This option will enable additional timekeeping sanity checks 1062 which may be helpful when diagnosing issues where timekeeping 1063 problems are suspected. 1064 1065 This may include checks in the timekeeping hotpaths, so this 1066 option may have a (very small) performance impact to some 1067 workloads. 1068 1069 If unsure, say N. 1070 1071config DEBUG_PREEMPT 1072 bool "Debug preemptible kernel" 1073 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT 1074 default y 1075 help 1076 If you say Y here then the kernel will use a debug variant of the 1077 commonly used smp_processor_id() function and will print warnings 1078 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1079 will detect preemption count underflows. 1080 1081menu "Lock Debugging (spinlocks, mutexes, etc...)" 1082 1083config LOCK_DEBUGGING_SUPPORT 1084 bool 1085 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1086 default y 1087 1088config PROVE_LOCKING 1089 bool "Lock debugging: prove locking correctness" 1090 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1091 select LOCKDEP 1092 select DEBUG_SPINLOCK 1093 select DEBUG_MUTEXES 1094 select DEBUG_RT_MUTEXES if RT_MUTEXES 1095 select DEBUG_RWSEMS 1096 select DEBUG_WW_MUTEX_SLOWPATH 1097 select DEBUG_LOCK_ALLOC 1098 select TRACE_IRQFLAGS 1099 default n 1100 help 1101 This feature enables the kernel to prove that all locking 1102 that occurs in the kernel runtime is mathematically 1103 correct: that under no circumstance could an arbitrary (and 1104 not yet triggered) combination of observed locking 1105 sequences (on an arbitrary number of CPUs, running an 1106 arbitrary number of tasks and interrupt contexts) cause a 1107 deadlock. 1108 1109 In short, this feature enables the kernel to report locking 1110 related deadlocks before they actually occur. 1111 1112 The proof does not depend on how hard and complex a 1113 deadlock scenario would be to trigger: how many 1114 participant CPUs, tasks and irq-contexts would be needed 1115 for it to trigger. The proof also does not depend on 1116 timing: if a race and a resulting deadlock is possible 1117 theoretically (no matter how unlikely the race scenario 1118 is), it will be proven so and will immediately be 1119 reported by the kernel (once the event is observed that 1120 makes the deadlock theoretically possible). 1121 1122 If a deadlock is impossible (i.e. the locking rules, as 1123 observed by the kernel, are mathematically correct), the 1124 kernel reports nothing. 1125 1126 NOTE: this feature can also be enabled for rwlocks, mutexes 1127 and rwsems - in which case all dependencies between these 1128 different locking variants are observed and mapped too, and 1129 the proof of observed correctness is also maintained for an 1130 arbitrary combination of these separate locking variants. 1131 1132 For more details, see Documentation/locking/lockdep-design.rst. 1133 1134config LOCK_STAT 1135 bool "Lock usage statistics" 1136 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1137 select LOCKDEP 1138 select DEBUG_SPINLOCK 1139 select DEBUG_MUTEXES 1140 select DEBUG_RT_MUTEXES if RT_MUTEXES 1141 select DEBUG_LOCK_ALLOC 1142 default n 1143 help 1144 This feature enables tracking lock contention points 1145 1146 For more details, see Documentation/locking/lockstat.rst 1147 1148 This also enables lock events required by "perf lock", 1149 subcommand of perf. 1150 If you want to use "perf lock", you also need to turn on 1151 CONFIG_EVENT_TRACING. 1152 1153 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1154 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1155 1156config DEBUG_RT_MUTEXES 1157 bool "RT Mutex debugging, deadlock detection" 1158 depends on DEBUG_KERNEL && RT_MUTEXES 1159 help 1160 This allows rt mutex semantics violations and rt mutex related 1161 deadlocks (lockups) to be detected and reported automatically. 1162 1163config DEBUG_SPINLOCK 1164 bool "Spinlock and rw-lock debugging: basic checks" 1165 depends on DEBUG_KERNEL 1166 select UNINLINE_SPIN_UNLOCK 1167 help 1168 Say Y here and build SMP to catch missing spinlock initialization 1169 and certain other kinds of spinlock errors commonly made. This is 1170 best used in conjunction with the NMI watchdog so that spinlock 1171 deadlocks are also debuggable. 1172 1173config DEBUG_MUTEXES 1174 bool "Mutex debugging: basic checks" 1175 depends on DEBUG_KERNEL 1176 help 1177 This feature allows mutex semantics violations to be detected and 1178 reported. 1179 1180config DEBUG_WW_MUTEX_SLOWPATH 1181 bool "Wait/wound mutex debugging: Slowpath testing" 1182 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1183 select DEBUG_LOCK_ALLOC 1184 select DEBUG_SPINLOCK 1185 select DEBUG_MUTEXES 1186 help 1187 This feature enables slowpath testing for w/w mutex users by 1188 injecting additional -EDEADLK wound/backoff cases. Together with 1189 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1190 will test all possible w/w mutex interface abuse with the 1191 exception of simply not acquiring all the required locks. 1192 Note that this feature can introduce significant overhead, so 1193 it really should not be enabled in a production or distro kernel, 1194 even a debug kernel. If you are a driver writer, enable it. If 1195 you are a distro, do not. 1196 1197config DEBUG_RWSEMS 1198 bool "RW Semaphore debugging: basic checks" 1199 depends on DEBUG_KERNEL 1200 help 1201 This debugging feature allows mismatched rw semaphore locks 1202 and unlocks to be detected and reported. 1203 1204config DEBUG_LOCK_ALLOC 1205 bool "Lock debugging: detect incorrect freeing of live locks" 1206 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1207 select DEBUG_SPINLOCK 1208 select DEBUG_MUTEXES 1209 select DEBUG_RT_MUTEXES if RT_MUTEXES 1210 select LOCKDEP 1211 help 1212 This feature will check whether any held lock (spinlock, rwlock, 1213 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1214 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1215 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1216 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1217 held during task exit. 1218 1219config LOCKDEP 1220 bool 1221 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1222 select STACKTRACE 1223 select FRAME_POINTER if !MIPS && !PPC && !ARM && !S390 && !MICROBLAZE && !ARC && !X86 1224 select KALLSYMS 1225 select KALLSYMS_ALL 1226 1227config LOCKDEP_SMALL 1228 bool 1229 1230config DEBUG_LOCKDEP 1231 bool "Lock dependency engine debugging" 1232 depends on DEBUG_KERNEL && LOCKDEP 1233 help 1234 If you say Y here, the lock dependency engine will do 1235 additional runtime checks to debug itself, at the price 1236 of more runtime overhead. 1237 1238config DEBUG_ATOMIC_SLEEP 1239 bool "Sleep inside atomic section checking" 1240 select PREEMPT_COUNT 1241 depends on DEBUG_KERNEL 1242 depends on !ARCH_NO_PREEMPT 1243 help 1244 If you say Y here, various routines which may sleep will become very 1245 noisy if they are called inside atomic sections: when a spinlock is 1246 held, inside an rcu read side critical section, inside preempt disabled 1247 sections, inside an interrupt, etc... 1248 1249config DEBUG_LOCKING_API_SELFTESTS 1250 bool "Locking API boot-time self-tests" 1251 depends on DEBUG_KERNEL 1252 help 1253 Say Y here if you want the kernel to run a short self-test during 1254 bootup. The self-test checks whether common types of locking bugs 1255 are detected by debugging mechanisms or not. (if you disable 1256 lock debugging then those bugs wont be detected of course.) 1257 The following locking APIs are covered: spinlocks, rwlocks, 1258 mutexes and rwsems. 1259 1260config LOCK_TORTURE_TEST 1261 tristate "torture tests for locking" 1262 depends on DEBUG_KERNEL 1263 select TORTURE_TEST 1264 help 1265 This option provides a kernel module that runs torture tests 1266 on kernel locking primitives. The kernel module may be built 1267 after the fact on the running kernel to be tested, if desired. 1268 1269 Say Y here if you want kernel locking-primitive torture tests 1270 to be built into the kernel. 1271 Say M if you want these torture tests to build as a module. 1272 Say N if you are unsure. 1273 1274config WW_MUTEX_SELFTEST 1275 tristate "Wait/wound mutex selftests" 1276 help 1277 This option provides a kernel module that runs tests on the 1278 on the struct ww_mutex locking API. 1279 1280 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1281 with this test harness. 1282 1283 Say M if you want these self tests to build as a module. 1284 Say N if you are unsure. 1285 1286endmenu # lock debugging 1287 1288config TRACE_IRQFLAGS 1289 bool 1290 help 1291 Enables hooks to interrupt enabling and disabling for 1292 either tracing or lock debugging. 1293 1294config STACKTRACE 1295 bool "Stack backtrace support" 1296 depends on STACKTRACE_SUPPORT 1297 help 1298 This option causes the kernel to create a /proc/pid/stack for 1299 every process, showing its current stack trace. 1300 It is also used by various kernel debugging features that require 1301 stack trace generation. 1302 1303config WARN_ALL_UNSEEDED_RANDOM 1304 bool "Warn for all uses of unseeded randomness" 1305 default n 1306 help 1307 Some parts of the kernel contain bugs relating to their use of 1308 cryptographically secure random numbers before it's actually possible 1309 to generate those numbers securely. This setting ensures that these 1310 flaws don't go unnoticed, by enabling a message, should this ever 1311 occur. This will allow people with obscure setups to know when things 1312 are going wrong, so that they might contact developers about fixing 1313 it. 1314 1315 Unfortunately, on some models of some architectures getting 1316 a fully seeded CRNG is extremely difficult, and so this can 1317 result in dmesg getting spammed for a surprisingly long 1318 time. This is really bad from a security perspective, and 1319 so architecture maintainers really need to do what they can 1320 to get the CRNG seeded sooner after the system is booted. 1321 However, since users cannot do anything actionable to 1322 address this, by default the kernel will issue only a single 1323 warning for the first use of unseeded randomness. 1324 1325 Say Y here if you want to receive warnings for all uses of 1326 unseeded randomness. This will be of use primarily for 1327 those developers interested in improving the security of 1328 Linux kernels running on their architecture (or 1329 subarchitecture). 1330 1331config DEBUG_KOBJECT 1332 bool "kobject debugging" 1333 depends on DEBUG_KERNEL 1334 help 1335 If you say Y here, some extra kobject debugging messages will be sent 1336 to the syslog. 1337 1338config DEBUG_KOBJECT_RELEASE 1339 bool "kobject release debugging" 1340 depends on DEBUG_OBJECTS_TIMERS 1341 help 1342 kobjects are reference counted objects. This means that their 1343 last reference count put is not predictable, and the kobject can 1344 live on past the point at which a driver decides to drop it's 1345 initial reference to the kobject gained on allocation. An 1346 example of this would be a struct device which has just been 1347 unregistered. 1348 1349 However, some buggy drivers assume that after such an operation, 1350 the memory backing the kobject can be immediately freed. This 1351 goes completely against the principles of a refcounted object. 1352 1353 If you say Y here, the kernel will delay the release of kobjects 1354 on the last reference count to improve the visibility of this 1355 kind of kobject release bug. 1356 1357config HAVE_DEBUG_BUGVERBOSE 1358 bool 1359 1360config DEBUG_BUGVERBOSE 1361 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT 1362 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE) 1363 default y 1364 help 1365 Say Y here to make BUG() panics output the file name and line number 1366 of the BUG call as well as the EIP and oops trace. This aids 1367 debugging but costs about 70-100K of memory. 1368 1369config DEBUG_LIST 1370 bool "Debug linked list manipulation" 1371 depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION 1372 help 1373 Enable this to turn on extended checks in the linked-list 1374 walking routines. 1375 1376 If unsure, say N. 1377 1378config DEBUG_PLIST 1379 bool "Debug priority linked list manipulation" 1380 depends on DEBUG_KERNEL 1381 help 1382 Enable this to turn on extended checks in the priority-ordered 1383 linked-list (plist) walking routines. This checks the entire 1384 list multiple times during each manipulation. 1385 1386 If unsure, say N. 1387 1388config DEBUG_SG 1389 bool "Debug SG table operations" 1390 depends on DEBUG_KERNEL 1391 help 1392 Enable this to turn on checks on scatter-gather tables. This can 1393 help find problems with drivers that do not properly initialize 1394 their sg tables. 1395 1396 If unsure, say N. 1397 1398config DEBUG_NOTIFIERS 1399 bool "Debug notifier call chains" 1400 depends on DEBUG_KERNEL 1401 help 1402 Enable this to turn on sanity checking for notifier call chains. 1403 This is most useful for kernel developers to make sure that 1404 modules properly unregister themselves from notifier chains. 1405 This is a relatively cheap check but if you care about maximum 1406 performance, say N. 1407 1408config DEBUG_CREDENTIALS 1409 bool "Debug credential management" 1410 depends on DEBUG_KERNEL 1411 help 1412 Enable this to turn on some debug checking for credential 1413 management. The additional code keeps track of the number of 1414 pointers from task_structs to any given cred struct, and checks to 1415 see that this number never exceeds the usage count of the cred 1416 struct. 1417 1418 Furthermore, if SELinux is enabled, this also checks that the 1419 security pointer in the cred struct is never seen to be invalid. 1420 1421 If unsure, say N. 1422 1423source "kernel/rcu/Kconfig.debug" 1424 1425config DEBUG_WQ_FORCE_RR_CPU 1426 bool "Force round-robin CPU selection for unbound work items" 1427 depends on DEBUG_KERNEL 1428 default n 1429 help 1430 Workqueue used to implicitly guarantee that work items queued 1431 without explicit CPU specified are put on the local CPU. This 1432 guarantee is no longer true and while local CPU is still 1433 preferred work items may be put on foreign CPUs. Kernel 1434 parameter "workqueue.debug_force_rr_cpu" is added to force 1435 round-robin CPU selection to flush out usages which depend on the 1436 now broken guarantee. This config option enables the debug 1437 feature by default. When enabled, memory and cache locality will 1438 be impacted. 1439 1440config DEBUG_BLOCK_EXT_DEVT 1441 bool "Force extended block device numbers and spread them" 1442 depends on DEBUG_KERNEL 1443 depends on BLOCK 1444 default n 1445 help 1446 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON 1447 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT 1448 YOU ARE DOING. Distros, please enable this and fix whatever 1449 is broken. 1450 1451 Conventionally, block device numbers are allocated from 1452 predetermined contiguous area. However, extended block area 1453 may introduce non-contiguous block device numbers. This 1454 option forces most block device numbers to be allocated from 1455 the extended space and spreads them to discover kernel or 1456 userland code paths which assume predetermined contiguous 1457 device number allocation. 1458 1459 Note that turning on this debug option shuffles all the 1460 device numbers for all IDE and SCSI devices including libata 1461 ones, so root partition specified using device number 1462 directly (via rdev or root=MAJ:MIN) won't work anymore. 1463 Textual device names (root=/dev/sdXn) will continue to work. 1464 1465 Say N if you are unsure. 1466 1467config CPU_HOTPLUG_STATE_CONTROL 1468 bool "Enable CPU hotplug state control" 1469 depends on DEBUG_KERNEL 1470 depends on HOTPLUG_CPU 1471 default n 1472 help 1473 Allows to write steps between "offline" and "online" to the CPUs 1474 sysfs target file so states can be stepped granular. This is a debug 1475 option for now as the hotplug machinery cannot be stopped and 1476 restarted at arbitrary points yet. 1477 1478 Say N if your are unsure. 1479 1480config NOTIFIER_ERROR_INJECTION 1481 tristate "Notifier error injection" 1482 depends on DEBUG_KERNEL 1483 select DEBUG_FS 1484 help 1485 This option provides the ability to inject artificial errors to 1486 specified notifier chain callbacks. It is useful to test the error 1487 handling of notifier call chain failures. 1488 1489 Say N if unsure. 1490 1491config PM_NOTIFIER_ERROR_INJECT 1492 tristate "PM notifier error injection module" 1493 depends on PM && NOTIFIER_ERROR_INJECTION 1494 default m if PM_DEBUG 1495 help 1496 This option provides the ability to inject artificial errors to 1497 PM notifier chain callbacks. It is controlled through debugfs 1498 interface /sys/kernel/debug/notifier-error-inject/pm 1499 1500 If the notifier call chain should be failed with some events 1501 notified, write the error code to "actions/<notifier event>/error". 1502 1503 Example: Inject PM suspend error (-12 = -ENOMEM) 1504 1505 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1506 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1507 # echo mem > /sys/power/state 1508 bash: echo: write error: Cannot allocate memory 1509 1510 To compile this code as a module, choose M here: the module will 1511 be called pm-notifier-error-inject. 1512 1513 If unsure, say N. 1514 1515config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1516 tristate "OF reconfig notifier error injection module" 1517 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1518 help 1519 This option provides the ability to inject artificial errors to 1520 OF reconfig notifier chain callbacks. It is controlled 1521 through debugfs interface under 1522 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1523 1524 If the notifier call chain should be failed with some events 1525 notified, write the error code to "actions/<notifier event>/error". 1526 1527 To compile this code as a module, choose M here: the module will 1528 be called of-reconfig-notifier-error-inject. 1529 1530 If unsure, say N. 1531 1532config NETDEV_NOTIFIER_ERROR_INJECT 1533 tristate "Netdev notifier error injection module" 1534 depends on NET && NOTIFIER_ERROR_INJECTION 1535 help 1536 This option provides the ability to inject artificial errors to 1537 netdevice notifier chain callbacks. It is controlled through debugfs 1538 interface /sys/kernel/debug/notifier-error-inject/netdev 1539 1540 If the notifier call chain should be failed with some events 1541 notified, write the error code to "actions/<notifier event>/error". 1542 1543 Example: Inject netdevice mtu change error (-22 = -EINVAL) 1544 1545 # cd /sys/kernel/debug/notifier-error-inject/netdev 1546 # echo -22 > actions/NETDEV_CHANGEMTU/error 1547 # ip link set eth0 mtu 1024 1548 RTNETLINK answers: Invalid argument 1549 1550 To compile this code as a module, choose M here: the module will 1551 be called netdev-notifier-error-inject. 1552 1553 If unsure, say N. 1554 1555config FUNCTION_ERROR_INJECTION 1556 def_bool y 1557 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 1558 1559config FAULT_INJECTION 1560 bool "Fault-injection framework" 1561 depends on DEBUG_KERNEL 1562 help 1563 Provide fault-injection framework. 1564 For more details, see Documentation/fault-injection/. 1565 1566config FAILSLAB 1567 bool "Fault-injection capability for kmalloc" 1568 depends on FAULT_INJECTION 1569 depends on SLAB || SLUB 1570 help 1571 Provide fault-injection capability for kmalloc. 1572 1573config FAIL_PAGE_ALLOC 1574 bool "Fault-injection capabilitiy for alloc_pages()" 1575 depends on FAULT_INJECTION 1576 help 1577 Provide fault-injection capability for alloc_pages(). 1578 1579config FAIL_MAKE_REQUEST 1580 bool "Fault-injection capability for disk IO" 1581 depends on FAULT_INJECTION && BLOCK 1582 help 1583 Provide fault-injection capability for disk IO. 1584 1585config FAIL_IO_TIMEOUT 1586 bool "Fault-injection capability for faking disk interrupts" 1587 depends on FAULT_INJECTION && BLOCK 1588 help 1589 Provide fault-injection capability on end IO handling. This 1590 will make the block layer "forget" an interrupt as configured, 1591 thus exercising the error handling. 1592 1593 Only works with drivers that use the generic timeout handling, 1594 for others it wont do anything. 1595 1596config FAIL_FUTEX 1597 bool "Fault-injection capability for futexes" 1598 select DEBUG_FS 1599 depends on FAULT_INJECTION && FUTEX 1600 help 1601 Provide fault-injection capability for futexes. 1602 1603config FAULT_INJECTION_DEBUG_FS 1604 bool "Debugfs entries for fault-injection capabilities" 1605 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 1606 help 1607 Enable configuration of fault-injection capabilities via debugfs. 1608 1609config FAIL_FUNCTION 1610 bool "Fault-injection capability for functions" 1611 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 1612 help 1613 Provide function-based fault-injection capability. 1614 This will allow you to override a specific function with a return 1615 with given return value. As a result, function caller will see 1616 an error value and have to handle it. This is useful to test the 1617 error handling in various subsystems. 1618 1619config FAIL_MMC_REQUEST 1620 bool "Fault-injection capability for MMC IO" 1621 depends on FAULT_INJECTION_DEBUG_FS && MMC 1622 help 1623 Provide fault-injection capability for MMC IO. 1624 This will make the mmc core return data errors. This is 1625 useful to test the error handling in the mmc block device 1626 and to test how the mmc host driver handles retries from 1627 the block device. 1628 1629config FAULT_INJECTION_STACKTRACE_FILTER 1630 bool "stacktrace filter for fault-injection capabilities" 1631 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 1632 depends on !X86_64 1633 select STACKTRACE 1634 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86 1635 help 1636 Provide stacktrace filter for fault-injection capabilities 1637 1638config LATENCYTOP 1639 bool "Latency measuring infrastructure" 1640 depends on DEBUG_KERNEL 1641 depends on STACKTRACE_SUPPORT 1642 depends on PROC_FS 1643 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86 1644 select KALLSYMS 1645 select KALLSYMS_ALL 1646 select STACKTRACE 1647 select SCHEDSTATS 1648 select SCHED_DEBUG 1649 help 1650 Enable this option if you want to use the LatencyTOP tool 1651 to find out which userspace is blocking on what kernel operations. 1652 1653source "kernel/trace/Kconfig" 1654 1655config PROVIDE_OHCI1394_DMA_INIT 1656 bool "Remote debugging over FireWire early on boot" 1657 depends on PCI && X86 1658 help 1659 If you want to debug problems which hang or crash the kernel early 1660 on boot and the crashing machine has a FireWire port, you can use 1661 this feature to remotely access the memory of the crashed machine 1662 over FireWire. This employs remote DMA as part of the OHCI1394 1663 specification which is now the standard for FireWire controllers. 1664 1665 With remote DMA, you can monitor the printk buffer remotely using 1666 firescope and access all memory below 4GB using fireproxy from gdb. 1667 Even controlling a kernel debugger is possible using remote DMA. 1668 1669 Usage: 1670 1671 If ohci1394_dma=early is used as boot parameter, it will initialize 1672 all OHCI1394 controllers which are found in the PCI config space. 1673 1674 As all changes to the FireWire bus such as enabling and disabling 1675 devices cause a bus reset and thereby disable remote DMA for all 1676 devices, be sure to have the cable plugged and FireWire enabled on 1677 the debugging host before booting the debug target for debugging. 1678 1679 This code (~1k) is freed after boot. By then, the firewire stack 1680 in charge of the OHCI-1394 controllers should be used instead. 1681 1682 See Documentation/debugging-via-ohci1394.txt for more information. 1683 1684menuconfig RUNTIME_TESTING_MENU 1685 bool "Runtime Testing" 1686 def_bool y 1687 1688if RUNTIME_TESTING_MENU 1689 1690config LKDTM 1691 tristate "Linux Kernel Dump Test Tool Module" 1692 depends on DEBUG_FS 1693 help 1694 This module enables testing of the different dumping mechanisms by 1695 inducing system failures at predefined crash points. 1696 If you don't need it: say N 1697 Choose M here to compile this code as a module. The module will be 1698 called lkdtm. 1699 1700 Documentation on how to use the module can be found in 1701 Documentation/fault-injection/provoke-crashes.rst 1702 1703config TEST_LIST_SORT 1704 tristate "Linked list sorting test" 1705 depends on DEBUG_KERNEL || m 1706 help 1707 Enable this to turn on 'list_sort()' function test. This test is 1708 executed only once during system boot (so affects only boot time), 1709 or at module load time. 1710 1711 If unsure, say N. 1712 1713config TEST_SORT 1714 tristate "Array-based sort test" 1715 depends on DEBUG_KERNEL || m 1716 help 1717 This option enables the self-test function of 'sort()' at boot, 1718 or at module load time. 1719 1720 If unsure, say N. 1721 1722config KPROBES_SANITY_TEST 1723 bool "Kprobes sanity tests" 1724 depends on DEBUG_KERNEL 1725 depends on KPROBES 1726 help 1727 This option provides for testing basic kprobes functionality on 1728 boot. Samples of kprobe and kretprobe are inserted and 1729 verified for functionality. 1730 1731 Say N if you are unsure. 1732 1733config BACKTRACE_SELF_TEST 1734 tristate "Self test for the backtrace code" 1735 depends on DEBUG_KERNEL 1736 help 1737 This option provides a kernel module that can be used to test 1738 the kernel stack backtrace code. This option is not useful 1739 for distributions or general kernels, but only for kernel 1740 developers working on architecture code. 1741 1742 Note that if you want to also test saved backtraces, you will 1743 have to enable STACKTRACE as well. 1744 1745 Say N if you are unsure. 1746 1747config RBTREE_TEST 1748 tristate "Red-Black tree test" 1749 depends on DEBUG_KERNEL 1750 help 1751 A benchmark measuring the performance of the rbtree library. 1752 Also includes rbtree invariant checks. 1753 1754config REED_SOLOMON_TEST 1755 tristate "Reed-Solomon library test" 1756 depends on DEBUG_KERNEL || m 1757 select REED_SOLOMON 1758 select REED_SOLOMON_ENC16 1759 select REED_SOLOMON_DEC16 1760 help 1761 This option enables the self-test function of rslib at boot, 1762 or at module load time. 1763 1764 If unsure, say N. 1765 1766config INTERVAL_TREE_TEST 1767 tristate "Interval tree test" 1768 depends on DEBUG_KERNEL 1769 select INTERVAL_TREE 1770 help 1771 A benchmark measuring the performance of the interval tree library 1772 1773config PERCPU_TEST 1774 tristate "Per cpu operations test" 1775 depends on m && DEBUG_KERNEL 1776 help 1777 Enable this option to build test module which validates per-cpu 1778 operations. 1779 1780 If unsure, say N. 1781 1782config ATOMIC64_SELFTEST 1783 tristate "Perform an atomic64_t self-test" 1784 help 1785 Enable this option to test the atomic64_t functions at boot or 1786 at module load time. 1787 1788 If unsure, say N. 1789 1790config ASYNC_RAID6_TEST 1791 tristate "Self test for hardware accelerated raid6 recovery" 1792 depends on ASYNC_RAID6_RECOV 1793 select ASYNC_MEMCPY 1794 ---help--- 1795 This is a one-shot self test that permutes through the 1796 recovery of all the possible two disk failure scenarios for a 1797 N-disk array. Recovery is performed with the asynchronous 1798 raid6 recovery routines, and will optionally use an offload 1799 engine if one is available. 1800 1801 If unsure, say N. 1802 1803config TEST_HEXDUMP 1804 tristate "Test functions located in the hexdump module at runtime" 1805 1806config TEST_STRING_HELPERS 1807 tristate "Test functions located in the string_helpers module at runtime" 1808 1809config TEST_STRSCPY 1810 tristate "Test strscpy*() family of functions at runtime" 1811 1812config TEST_KSTRTOX 1813 tristate "Test kstrto*() family of functions at runtime" 1814 1815config TEST_PRINTF 1816 tristate "Test printf() family of functions at runtime" 1817 1818config TEST_BITMAP 1819 tristate "Test bitmap_*() family of functions at runtime" 1820 help 1821 Enable this option to test the bitmap functions at boot. 1822 1823 If unsure, say N. 1824 1825config TEST_BITFIELD 1826 tristate "Test bitfield functions at runtime" 1827 help 1828 Enable this option to test the bitfield functions at boot. 1829 1830 If unsure, say N. 1831 1832config TEST_UUID 1833 tristate "Test functions located in the uuid module at runtime" 1834 1835config TEST_XARRAY 1836 tristate "Test the XArray code at runtime" 1837 1838config TEST_OVERFLOW 1839 tristate "Test check_*_overflow() functions at runtime" 1840 1841config TEST_RHASHTABLE 1842 tristate "Perform selftest on resizable hash table" 1843 help 1844 Enable this option to test the rhashtable functions at boot. 1845 1846 If unsure, say N. 1847 1848config TEST_HASH 1849 tristate "Perform selftest on hash functions" 1850 help 1851 Enable this option to test the kernel's integer (<linux/hash.h>), 1852 string (<linux/stringhash.h>), and siphash (<linux/siphash.h>) 1853 hash functions on boot (or module load). 1854 1855 This is intended to help people writing architecture-specific 1856 optimized versions. If unsure, say N. 1857 1858config TEST_IDA 1859 tristate "Perform selftest on IDA functions" 1860 1861config TEST_PARMAN 1862 tristate "Perform selftest on priority array manager" 1863 depends on PARMAN 1864 help 1865 Enable this option to test priority array manager on boot 1866 (or module load). 1867 1868 If unsure, say N. 1869 1870config TEST_IRQ_TIMINGS 1871 bool "IRQ timings selftest" 1872 depends on IRQ_TIMINGS 1873 help 1874 Enable this option to test the irq timings code on boot. 1875 1876 If unsure, say N. 1877 1878config TEST_LKM 1879 tristate "Test module loading with 'hello world' module" 1880 depends on m 1881 help 1882 This builds the "test_module" module that emits "Hello, world" 1883 on printk when loaded. It is designed to be used for basic 1884 evaluation of the module loading subsystem (for example when 1885 validating module verification). It lacks any extra dependencies, 1886 and will not normally be loaded by the system unless explicitly 1887 requested by name. 1888 1889 If unsure, say N. 1890 1891config TEST_VMALLOC 1892 tristate "Test module for stress/performance analysis of vmalloc allocator" 1893 default n 1894 depends on MMU 1895 depends on m 1896 help 1897 This builds the "test_vmalloc" module that should be used for 1898 stress and performance analysis. So, any new change for vmalloc 1899 subsystem can be evaluated from performance and stability point 1900 of view. 1901 1902 If unsure, say N. 1903 1904config TEST_USER_COPY 1905 tristate "Test user/kernel boundary protections" 1906 depends on m 1907 help 1908 This builds the "test_user_copy" module that runs sanity checks 1909 on the copy_to/from_user infrastructure, making sure basic 1910 user/kernel boundary testing is working. If it fails to load, 1911 a regression has been detected in the user/kernel memory boundary 1912 protections. 1913 1914 If unsure, say N. 1915 1916config TEST_BPF 1917 tristate "Test BPF filter functionality" 1918 depends on m && NET 1919 help 1920 This builds the "test_bpf" module that runs various test vectors 1921 against the BPF interpreter or BPF JIT compiler depending on the 1922 current setting. This is in particular useful for BPF JIT compiler 1923 development, but also to run regression tests against changes in 1924 the interpreter code. It also enables test stubs for eBPF maps and 1925 verifier used by user space verifier testsuite. 1926 1927 If unsure, say N. 1928 1929config TEST_BLACKHOLE_DEV 1930 tristate "Test blackhole netdev functionality" 1931 depends on m && NET 1932 help 1933 This builds the "test_blackhole_dev" module that validates the 1934 data path through this blackhole netdev. 1935 1936 If unsure, say N. 1937 1938config FIND_BIT_BENCHMARK 1939 tristate "Test find_bit functions" 1940 help 1941 This builds the "test_find_bit" module that measure find_*_bit() 1942 functions performance. 1943 1944 If unsure, say N. 1945 1946config TEST_FIRMWARE 1947 tristate "Test firmware loading via userspace interface" 1948 depends on FW_LOADER 1949 help 1950 This builds the "test_firmware" module that creates a userspace 1951 interface for testing firmware loading. This can be used to 1952 control the triggering of firmware loading without needing an 1953 actual firmware-using device. The contents can be rechecked by 1954 userspace. 1955 1956 If unsure, say N. 1957 1958config TEST_SYSCTL 1959 tristate "sysctl test driver" 1960 depends on PROC_SYSCTL 1961 help 1962 This builds the "test_sysctl" module. This driver enables to test the 1963 proc sysctl interfaces available to drivers safely without affecting 1964 production knobs which might alter system functionality. 1965 1966 If unsure, say N. 1967 1968config TEST_UDELAY 1969 tristate "udelay test driver" 1970 help 1971 This builds the "udelay_test" module that helps to make sure 1972 that udelay() is working properly. 1973 1974 If unsure, say N. 1975 1976config TEST_STATIC_KEYS 1977 tristate "Test static keys" 1978 depends on m 1979 help 1980 Test the static key interfaces. 1981 1982 If unsure, say N. 1983 1984config TEST_KMOD 1985 tristate "kmod stress tester" 1986 depends on m 1987 depends on NETDEVICES && NET_CORE && INET # for TUN 1988 depends on BLOCK 1989 select TEST_LKM 1990 select XFS_FS 1991 select TUN 1992 select BTRFS_FS 1993 help 1994 Test the kernel's module loading mechanism: kmod. kmod implements 1995 support to load modules using the Linux kernel's usermode helper. 1996 This test provides a series of tests against kmod. 1997 1998 Although technically you can either build test_kmod as a module or 1999 into the kernel we disallow building it into the kernel since 2000 it stress tests request_module() and this will very likely cause 2001 some issues by taking over precious threads available from other 2002 module load requests, ultimately this could be fatal. 2003 2004 To run tests run: 2005 2006 tools/testing/selftests/kmod/kmod.sh --help 2007 2008 If unsure, say N. 2009 2010config TEST_DEBUG_VIRTUAL 2011 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 2012 depends on DEBUG_VIRTUAL 2013 help 2014 Test the kernel's ability to detect incorrect calls to 2015 virt_to_phys() done against the non-linear part of the 2016 kernel's virtual address map. 2017 2018 If unsure, say N. 2019 2020config TEST_MEMCAT_P 2021 tristate "Test memcat_p() helper function" 2022 help 2023 Test the memcat_p() helper for correctly merging two 2024 pointer arrays together. 2025 2026 If unsure, say N. 2027 2028config TEST_LIVEPATCH 2029 tristate "Test livepatching" 2030 default n 2031 depends on DYNAMIC_DEBUG 2032 depends on LIVEPATCH 2033 depends on m 2034 help 2035 Test kernel livepatching features for correctness. The tests will 2036 load test modules that will be livepatched in various scenarios. 2037 2038 To run all the livepatching tests: 2039 2040 make -C tools/testing/selftests TARGETS=livepatch run_tests 2041 2042 Alternatively, individual tests may be invoked: 2043 2044 tools/testing/selftests/livepatch/test-callbacks.sh 2045 tools/testing/selftests/livepatch/test-livepatch.sh 2046 tools/testing/selftests/livepatch/test-shadow-vars.sh 2047 2048 If unsure, say N. 2049 2050config TEST_OBJAGG 2051 tristate "Perform selftest on object aggreration manager" 2052 default n 2053 depends on OBJAGG 2054 help 2055 Enable this option to test object aggregation manager on boot 2056 (or module load). 2057 2058 2059config TEST_STACKINIT 2060 tristate "Test level of stack variable initialization" 2061 help 2062 Test if the kernel is zero-initializing stack variables and 2063 padding. Coverage is controlled by compiler flags, 2064 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2065 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2066 2067 If unsure, say N. 2068 2069config TEST_MEMINIT 2070 tristate "Test heap/page initialization" 2071 help 2072 Test if the kernel is zero-initializing heap and page allocations. 2073 This can be useful to test init_on_alloc and init_on_free features. 2074 2075 If unsure, say N. 2076 2077endif # RUNTIME_TESTING_MENU 2078 2079config MEMTEST 2080 bool "Memtest" 2081 ---help--- 2082 This option adds a kernel parameter 'memtest', which allows memtest 2083 to be set. 2084 memtest=0, mean disabled; -- default 2085 memtest=1, mean do 1 test pattern; 2086 ... 2087 memtest=17, mean do 17 test patterns. 2088 If you are unsure how to answer this question, answer N. 2089 2090config BUG_ON_DATA_CORRUPTION 2091 bool "Trigger a BUG when data corruption is detected" 2092 select DEBUG_LIST 2093 help 2094 Select this option if the kernel should BUG when it encounters 2095 data corruption in kernel memory structures when they get checked 2096 for validity. 2097 2098 If unsure, say N. 2099 2100source "samples/Kconfig" 2101 2102source "lib/Kconfig.kgdb" 2103 2104source "lib/Kconfig.ubsan" 2105 2106config ARCH_HAS_DEVMEM_IS_ALLOWED 2107 bool 2108 2109config STRICT_DEVMEM 2110 bool "Filter access to /dev/mem" 2111 depends on MMU && DEVMEM 2112 depends on ARCH_HAS_DEVMEM_IS_ALLOWED 2113 default y if PPC || X86 || ARM64 2114 ---help--- 2115 If this option is disabled, you allow userspace (root) access to all 2116 of memory, including kernel and userspace memory. Accidental 2117 access to this is obviously disastrous, but specific access can 2118 be used by people debugging the kernel. Note that with PAT support 2119 enabled, even in this case there are restrictions on /dev/mem 2120 use due to the cache aliasing requirements. 2121 2122 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 2123 file only allows userspace access to PCI space and the BIOS code and 2124 data regions. This is sufficient for dosemu and X and all common 2125 users of /dev/mem. 2126 2127 If in doubt, say Y. 2128 2129config IO_STRICT_DEVMEM 2130 bool "Filter I/O access to /dev/mem" 2131 depends on STRICT_DEVMEM 2132 ---help--- 2133 If this option is disabled, you allow userspace (root) access to all 2134 io-memory regardless of whether a driver is actively using that 2135 range. Accidental access to this is obviously disastrous, but 2136 specific access can be used by people debugging kernel drivers. 2137 2138 If this option is switched on, the /dev/mem file only allows 2139 userspace access to *idle* io-memory ranges (see /proc/iomem) This 2140 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 2141 if the driver using a given range cannot be disabled. 2142 2143 If in doubt, say Y. 2144 2145source "arch/$(SRCARCH)/Kconfig.debug" 2146 2147endmenu # Kernel hacking 2148