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