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