1# SPDX-License-Identifier: GPL-2.0-only 2menu "Kernel hacking" 3 4menu "printk and dmesg options" 5 6config PRINTK_TIME 7 bool "Show timing information on printks" 8 depends on PRINTK 9 help 10 Selecting this option causes time stamps of the printk() 11 messages to be added to the output of the syslog() system 12 call and at the console. 13 14 The timestamp is always recorded internally, and exported 15 to /dev/kmsg. This flag just specifies if the timestamp should 16 be included, not that the timestamp is recorded. 17 18 The behavior is also controlled by the kernel command line 19 parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst 20 21config PRINTK_CALLER 22 bool "Show caller information on printks" 23 depends on PRINTK 24 help 25 Selecting this option causes printk() to add a caller "thread id" (if 26 in task context) or a caller "processor id" (if not in task context) 27 to every message. 28 29 This option is intended for environments where multiple threads 30 concurrently call printk() for many times, for it is difficult to 31 interpret without knowing where these lines (or sometimes individual 32 line which was divided into multiple lines due to race) came from. 33 34 Since toggling after boot makes the code racy, currently there is 35 no option to enable/disable at the kernel command line parameter or 36 sysfs interface. 37 38config CONSOLE_LOGLEVEL_DEFAULT 39 int "Default console loglevel (1-15)" 40 range 1 15 41 default "7" 42 help 43 Default loglevel to determine what will be printed on the console. 44 45 Setting a default here is equivalent to passing in loglevel=<x> in 46 the kernel bootargs. loglevel=<x> continues to override whatever 47 value is specified here as well. 48 49 Note: This does not affect the log level of un-prefixed printk() 50 usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT 51 option. 52 53config CONSOLE_LOGLEVEL_QUIET 54 int "quiet console loglevel (1-15)" 55 range 1 15 56 default "4" 57 help 58 loglevel to use when "quiet" is passed on the kernel commandline. 59 60 When "quiet" is passed on the kernel commandline this loglevel 61 will be used as the loglevel. IOW passing "quiet" will be the 62 equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>" 63 64config MESSAGE_LOGLEVEL_DEFAULT 65 int "Default message log level (1-7)" 66 range 1 7 67 default "4" 68 help 69 Default log level for printk statements with no specified priority. 70 71 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks 72 that are auditing their logs closely may want to set it to a lower 73 priority. 74 75 Note: This does not affect what message level gets printed on the console 76 by default. To change that, use loglevel=<x> in the kernel bootargs, 77 or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value. 78 79config BOOT_PRINTK_DELAY 80 bool "Delay each boot printk message by N milliseconds" 81 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY 82 help 83 This build option allows you to read kernel boot messages 84 by inserting a short delay after each one. The delay is 85 specified in milliseconds on the kernel command line, 86 using "boot_delay=N". 87 88 It is likely that you would also need to use "lpj=M" to preset 89 the "loops per jiffie" value. 90 See a previous boot log for the "lpj" value to use for your 91 system, and then set "lpj=M" before setting "boot_delay=N". 92 NOTE: Using this option may adversely affect SMP systems. 93 I.e., processors other than the first one may not boot up. 94 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect 95 what it believes to be lockup conditions. 96 97config DYNAMIC_DEBUG 98 bool "Enable dynamic printk() support" 99 default n 100 depends on PRINTK 101 depends on DEBUG_FS 102 help 103 104 Compiles debug level messages into the kernel, which would not 105 otherwise be available at runtime. These messages can then be 106 enabled/disabled based on various levels of scope - per source file, 107 function, module, format string, and line number. This mechanism 108 implicitly compiles in all pr_debug() and dev_dbg() calls, which 109 enlarges the kernel text size by about 2%. 110 111 If a source file is compiled with DEBUG flag set, any 112 pr_debug() calls in it are enabled by default, but can be 113 disabled at runtime as below. Note that DEBUG flag is 114 turned on by many CONFIG_*DEBUG* options. 115 116 Usage: 117 118 Dynamic debugging is controlled via the 'dynamic_debug/control' file, 119 which is contained in the 'debugfs' filesystem. Thus, the debugfs 120 filesystem must first be mounted before making use of this feature. 121 We refer the control file as: <debugfs>/dynamic_debug/control. This 122 file contains a list of the debug statements that can be enabled. The 123 format for each line of the file is: 124 125 filename:lineno [module]function flags format 126 127 filename : source file of the debug statement 128 lineno : line number of the debug statement 129 module : module that contains the debug statement 130 function : function that contains the debug statement 131 flags : '=p' means the line is turned 'on' for printing 132 format : the format used for the debug statement 133 134 From a live system: 135 136 nullarbor:~ # cat <debugfs>/dynamic_debug/control 137 # filename:lineno [module]function flags format 138 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012" 139 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012" 140 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012" 141 142 Example usage: 143 144 // enable the message at line 1603 of file svcsock.c 145 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' > 146 <debugfs>/dynamic_debug/control 147 148 // enable all the messages in file svcsock.c 149 nullarbor:~ # echo -n 'file svcsock.c +p' > 150 <debugfs>/dynamic_debug/control 151 152 // enable all the messages in the NFS server module 153 nullarbor:~ # echo -n 'module nfsd +p' > 154 <debugfs>/dynamic_debug/control 155 156 // enable all 12 messages in the function svc_process() 157 nullarbor:~ # echo -n 'func svc_process +p' > 158 <debugfs>/dynamic_debug/control 159 160 // disable all 12 messages in the function svc_process() 161 nullarbor:~ # echo -n 'func svc_process -p' > 162 <debugfs>/dynamic_debug/control 163 164 See Documentation/admin-guide/dynamic-debug-howto.rst for additional 165 information. 166 167endmenu # "printk and dmesg options" 168 169menu "Compile-time checks and compiler options" 170 171config DEBUG_INFO 172 bool "Compile the kernel with debug info" 173 depends on DEBUG_KERNEL && !COMPILE_TEST 174 help 175 If you say Y here the resulting kernel image will include 176 debugging info resulting in a larger kernel image. 177 This adds debug symbols to the kernel and modules (gcc -g), and 178 is needed if you intend to use kernel crashdump or binary object 179 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 180 Say Y here only if you plan to debug the kernel. 181 182 If unsure, say N. 183 184config DEBUG_INFO_REDUCED 185 bool "Reduce debugging information" 186 depends on DEBUG_INFO 187 help 188 If you say Y here gcc is instructed to generate less debugging 189 information for structure types. This means that tools that 190 need full debugging information (like kgdb or systemtap) won't 191 be happy. But if you merely need debugging information to 192 resolve line numbers there is no loss. Advantage is that 193 build directory object sizes shrink dramatically over a full 194 DEBUG_INFO build and compile times are reduced too. 195 Only works with newer gcc versions. 196 197config DEBUG_INFO_SPLIT 198 bool "Produce split debuginfo in .dwo files" 199 depends on DEBUG_INFO 200 depends on $(cc-option,-gsplit-dwarf) 201 help 202 Generate debug info into separate .dwo files. This significantly 203 reduces the build directory size for builds with DEBUG_INFO, 204 because it stores the information only once on disk in .dwo 205 files instead of multiple times in object files and executables. 206 In addition the debug information is also compressed. 207 208 Requires recent gcc (4.7+) and recent gdb/binutils. 209 Any tool that packages or reads debug information would need 210 to know about the .dwo files and include them. 211 Incompatible with older versions of ccache. 212 213config DEBUG_INFO_DWARF4 214 bool "Generate dwarf4 debuginfo" 215 depends on DEBUG_INFO 216 depends on $(cc-option,-gdwarf-4) 217 help 218 Generate dwarf4 debug info. This requires recent versions 219 of gcc and gdb. It makes the debug information larger. 220 But it significantly improves the success of resolving 221 variables in gdb on optimized code. 222 223config DEBUG_INFO_BTF 224 bool "Generate BTF typeinfo" 225 depends on DEBUG_INFO 226 help 227 Generate deduplicated BTF type information from DWARF debug info. 228 Turning this on expects presence of pahole tool, which will convert 229 DWARF type info into equivalent deduplicated BTF type info. 230 231config GDB_SCRIPTS 232 bool "Provide GDB scripts for kernel debugging" 233 depends on DEBUG_INFO 234 help 235 This creates the required links to GDB helper scripts in the 236 build directory. If you load vmlinux into gdb, the helper 237 scripts will be automatically imported by gdb as well, and 238 additional functions are available to analyze a Linux kernel 239 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst 240 for further details. 241 242config ENABLE_MUST_CHECK 243 bool "Enable __must_check logic" 244 default y 245 help 246 Enable the __must_check logic in the kernel build. Disable this to 247 suppress the "warning: ignoring return value of 'foo', declared with 248 attribute warn_unused_result" messages. 249 250config FRAME_WARN 251 int "Warn for stack frames larger than (needs gcc 4.4)" 252 range 0 8192 253 default 2048 if GCC_PLUGIN_LATENT_ENTROPY 254 default 1280 if (!64BIT && PARISC) 255 default 1024 if (!64BIT && !PARISC) 256 default 2048 if 64BIT 257 help 258 Tell gcc to warn at build time for stack frames larger than this. 259 Setting this too low will cause a lot of warnings. 260 Setting it to 0 disables the warning. 261 Requires gcc 4.4 262 263config STRIP_ASM_SYMS 264 bool "Strip assembler-generated symbols during link" 265 default n 266 help 267 Strip internal assembler-generated symbols during a link (symbols 268 that look like '.Lxxx') so they don't pollute the output of 269 get_wchan() and suchlike. 270 271config READABLE_ASM 272 bool "Generate readable assembler code" 273 depends on DEBUG_KERNEL 274 help 275 Disable some compiler optimizations that tend to generate human unreadable 276 assembler output. This may make the kernel slightly slower, but it helps 277 to keep kernel developers who have to stare a lot at assembler listings 278 sane. 279 280config UNUSED_SYMBOLS 281 bool "Enable unused/obsolete exported symbols" 282 default y if X86 283 help 284 Unused but exported symbols make the kernel needlessly bigger. For 285 that reason most of these unused exports will soon be removed. This 286 option is provided temporarily to provide a transition period in case 287 some external kernel module needs one of these symbols anyway. If you 288 encounter such a case in your module, consider if you are actually 289 using the right API. (rationale: since nobody in the kernel is using 290 this in a module, there is a pretty good chance it's actually the 291 wrong interface to use). If you really need the symbol, please send a 292 mail to the linux kernel mailing list mentioning the symbol and why 293 you really need it, and what the merge plan to the mainline kernel for 294 your module is. 295 296config DEBUG_FS 297 bool "Debug Filesystem" 298 help 299 debugfs is a virtual file system that kernel developers use to put 300 debugging files into. Enable this option to be able to read and 301 write to these files. 302 303 For detailed documentation on the debugfs API, see 304 Documentation/filesystems/. 305 306 If unsure, say N. 307 308config HEADERS_INSTALL 309 bool "Install uapi headers to usr/include" 310 depends on !UML 311 help 312 This option will install uapi headers (headers exported to user-space) 313 into the usr/include directory for use during the kernel build. 314 This is unneeded for building the kernel itself, but needed for some 315 user-space program samples. It is also needed by some features such 316 as uapi header sanity checks. 317 318config HEADERS_CHECK 319 bool "Run sanity checks on uapi headers when building 'all'" 320 depends on HEADERS_INSTALL 321 help 322 This option will run basic sanity checks on uapi headers when 323 building the 'all' target, for example, ensure that they do not 324 attempt to include files which were not exported, etc. 325 326 If you're making modifications to header files which are 327 relevant for userspace, say 'Y'. 328 329config OPTIMIZE_INLINING 330 bool "Allow compiler to uninline functions marked 'inline'" 331 help 332 This option determines if the kernel forces gcc to inline the functions 333 developers have marked 'inline'. Doing so takes away freedom from gcc to 334 do what it thinks is best, which is desirable for the gcc 3.x series of 335 compilers. The gcc 4.x series have a rewritten inlining algorithm and 336 enabling this option will generate a smaller kernel there. Hopefully 337 this algorithm is so good that allowing gcc 4.x and above to make the 338 decision will become the default in the future. Until then this option 339 is there to test gcc for this. 340 341 If unsure, say N. 342 343config DEBUG_SECTION_MISMATCH 344 bool "Enable full Section mismatch analysis" 345 help 346 The section mismatch analysis checks if there are illegal 347 references from one section to another section. 348 During linktime or runtime, some sections are dropped; 349 any use of code/data previously in these sections would 350 most likely result in an oops. 351 In the code, functions and variables are annotated with 352 __init,, etc. (see the full list in include/linux/init.h), 353 which results in the code/data being placed in specific sections. 354 The section mismatch analysis is always performed after a full 355 kernel build, and enabling this option causes the following 356 additional steps to occur: 357 - Add the option -fno-inline-functions-called-once to gcc commands. 358 When inlining a function annotated with __init in a non-init 359 function, we would lose the section information and thus 360 the analysis would not catch the illegal reference. 361 This option tells gcc to inline less (but it does result in 362 a larger kernel). 363 - Run the section mismatch analysis for each module/built-in.a file. 364 When we run the section mismatch analysis on vmlinux.o, we 365 lose valuable information about where the mismatch was 366 introduced. 367 Running the analysis for each module/built-in.a file 368 tells where the mismatch happens much closer to the 369 source. The drawback is that the same mismatch is 370 reported at least twice. 371 - Enable verbose reporting from modpost in order to help resolve 372 the section mismatches that are reported. 373 374config SECTION_MISMATCH_WARN_ONLY 375 bool "Make section mismatch errors non-fatal" 376 default y 377 help 378 If you say N here, the build process will fail if there are any 379 section mismatch, instead of just throwing warnings. 380 381 If unsure, say Y. 382 383# 384# Select this config option from the architecture Kconfig, if it 385# is preferred to always offer frame pointers as a config 386# option on the architecture (regardless of KERNEL_DEBUG): 387# 388config ARCH_WANT_FRAME_POINTERS 389 bool 390 391config FRAME_POINTER 392 bool "Compile the kernel with frame pointers" 393 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS 394 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 395 help 396 If you say Y here the resulting kernel image will be slightly 397 larger and slower, but it gives very useful debugging information 398 in case of kernel bugs. (precise oopses/stacktraces/warnings) 399 400config STACK_VALIDATION 401 bool "Compile-time stack metadata validation" 402 depends on HAVE_STACK_VALIDATION 403 default n 404 help 405 Add compile-time checks to validate stack metadata, including frame 406 pointers (if CONFIG_FRAME_POINTER is enabled). This helps ensure 407 that runtime stack traces are more reliable. 408 409 This is also a prerequisite for generation of ORC unwind data, which 410 is needed for CONFIG_UNWINDER_ORC. 411 412 For more information, see 413 tools/objtool/Documentation/stack-validation.txt. 414 415config DEBUG_FORCE_WEAK_PER_CPU 416 bool "Force weak per-cpu definitions" 417 depends on DEBUG_KERNEL 418 help 419 s390 and alpha require percpu variables in modules to be 420 defined weak to work around addressing range issue which 421 puts the following two restrictions on percpu variable 422 definitions. 423 424 1. percpu symbols must be unique whether static or not 425 2. percpu variables can't be defined inside a function 426 427 To ensure that generic code follows the above rules, this 428 option forces all percpu variables to be defined as weak. 429 430endmenu # "Compiler options" 431 432config MAGIC_SYSRQ 433 bool "Magic SysRq key" 434 depends on !UML 435 help 436 If you say Y here, you will have some control over the system even 437 if the system crashes for example during kernel debugging (e.g., you 438 will be able to flush the buffer cache to disk, reboot the system 439 immediately or dump some status information). This is accomplished 440 by pressing various keys while holding SysRq (Alt+PrintScreen). It 441 also works on a serial console (on PC hardware at least), if you 442 send a BREAK and then within 5 seconds a command keypress. The 443 keys are documented in <file:Documentation/admin-guide/sysrq.rst>. 444 Don't say Y unless you really know what this hack does. 445 446config MAGIC_SYSRQ_DEFAULT_ENABLE 447 hex "Enable magic SysRq key functions by default" 448 depends on MAGIC_SYSRQ 449 default 0x1 450 help 451 Specifies which SysRq key functions are enabled by default. 452 This may be set to 1 or 0 to enable or disable them all, or 453 to a bitmask as described in Documentation/admin-guide/sysrq.rst. 454 455config MAGIC_SYSRQ_SERIAL 456 bool "Enable magic SysRq key over serial" 457 depends on MAGIC_SYSRQ 458 default y 459 help 460 Many embedded boards have a disconnected TTL level serial which can 461 generate some garbage that can lead to spurious false sysrq detects. 462 This option allows you to decide whether you want to enable the 463 magic SysRq key. 464 465config DEBUG_KERNEL 466 bool "Kernel debugging" 467 help 468 Say Y here if you are developing drivers or trying to debug and 469 identify kernel problems. 470 471config DEBUG_MISC 472 bool "Miscellaneous debug code" 473 default DEBUG_KERNEL 474 depends on DEBUG_KERNEL 475 help 476 Say Y here if you need to enable miscellaneous debug code that should 477 be under a more specific debug option but isn't. 478 479 480menu "Memory Debugging" 481 482source "mm/Kconfig.debug" 483 484config DEBUG_OBJECTS 485 bool "Debug object operations" 486 depends on DEBUG_KERNEL 487 help 488 If you say Y here, additional code will be inserted into the 489 kernel to track the life time of various objects and validate 490 the operations on those objects. 491 492config DEBUG_OBJECTS_SELFTEST 493 bool "Debug objects selftest" 494 depends on DEBUG_OBJECTS 495 help 496 This enables the selftest of the object debug code. 497 498config DEBUG_OBJECTS_FREE 499 bool "Debug objects in freed memory" 500 depends on DEBUG_OBJECTS 501 help 502 This enables checks whether a k/v free operation frees an area 503 which contains an object which has not been deactivated 504 properly. This can make kmalloc/kfree-intensive workloads 505 much slower. 506 507config DEBUG_OBJECTS_TIMERS 508 bool "Debug timer objects" 509 depends on DEBUG_OBJECTS 510 help 511 If you say Y here, additional code will be inserted into the 512 timer routines to track the life time of timer objects and 513 validate the timer operations. 514 515config DEBUG_OBJECTS_WORK 516 bool "Debug work objects" 517 depends on DEBUG_OBJECTS 518 help 519 If you say Y here, additional code will be inserted into the 520 work queue routines to track the life time of work objects and 521 validate the work operations. 522 523config DEBUG_OBJECTS_RCU_HEAD 524 bool "Debug RCU callbacks objects" 525 depends on DEBUG_OBJECTS 526 help 527 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 528 529config DEBUG_OBJECTS_PERCPU_COUNTER 530 bool "Debug percpu counter objects" 531 depends on DEBUG_OBJECTS 532 help 533 If you say Y here, additional code will be inserted into the 534 percpu counter routines to track the life time of percpu counter 535 objects and validate the percpu counter operations. 536 537config DEBUG_OBJECTS_ENABLE_DEFAULT 538 int "debug_objects bootup default value (0-1)" 539 range 0 1 540 default "1" 541 depends on DEBUG_OBJECTS 542 help 543 Debug objects boot parameter default value 544 545config DEBUG_SLAB 546 bool "Debug slab memory allocations" 547 depends on DEBUG_KERNEL && SLAB 548 help 549 Say Y here to have the kernel do limited verification on memory 550 allocation as well as poisoning memory on free to catch use of freed 551 memory. This can make kmalloc/kfree-intensive workloads much slower. 552 553config SLUB_DEBUG_ON 554 bool "SLUB debugging on by default" 555 depends on SLUB && SLUB_DEBUG 556 default n 557 help 558 Boot with debugging on by default. SLUB boots by default with 559 the runtime debug capabilities switched off. Enabling this is 560 equivalent to specifying the "slub_debug" parameter on boot. 561 There is no support for more fine grained debug control like 562 possible with slub_debug=xxx. SLUB debugging may be switched 563 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying 564 "slub_debug=-". 565 566config SLUB_STATS 567 default n 568 bool "Enable SLUB performance statistics" 569 depends on SLUB && SYSFS 570 help 571 SLUB statistics are useful to debug SLUBs allocation behavior in 572 order find ways to optimize the allocator. This should never be 573 enabled for production use since keeping statistics slows down 574 the allocator by a few percentage points. The slabinfo command 575 supports the determination of the most active slabs to figure 576 out which slabs are relevant to a particular load. 577 Try running: slabinfo -DA 578 579config HAVE_DEBUG_KMEMLEAK 580 bool 581 582config DEBUG_KMEMLEAK 583 bool "Kernel memory leak detector" 584 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK 585 select DEBUG_FS 586 select STACKTRACE if STACKTRACE_SUPPORT 587 select KALLSYMS 588 select CRC32 589 help 590 Say Y here if you want to enable the memory leak 591 detector. The memory allocation/freeing is traced in a way 592 similar to the Boehm's conservative garbage collector, the 593 difference being that the orphan objects are not freed but 594 only shown in /sys/kernel/debug/kmemleak. Enabling this 595 feature will introduce an overhead to memory 596 allocations. See Documentation/dev-tools/kmemleak.rst for more 597 details. 598 599 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances 600 of finding leaks due to the slab objects poisoning. 601 602 In order to access the kmemleak file, debugfs needs to be 603 mounted (usually at /sys/kernel/debug). 604 605config DEBUG_KMEMLEAK_EARLY_LOG_SIZE 606 int "Maximum kmemleak early log entries" 607 depends on DEBUG_KMEMLEAK 608 range 200 40000 609 default 400 610 help 611 Kmemleak must track all the memory allocations to avoid 612 reporting false positives. Since memory may be allocated or 613 freed before kmemleak is initialised, an early log buffer is 614 used to store these actions. If kmemleak reports "early log 615 buffer exceeded", please increase this value. 616 617config DEBUG_KMEMLEAK_TEST 618 tristate "Simple test for the kernel memory leak detector" 619 depends on DEBUG_KMEMLEAK && m 620 help 621 This option enables a module that explicitly leaks memory. 622 623 If unsure, say N. 624 625config DEBUG_KMEMLEAK_DEFAULT_OFF 626 bool "Default kmemleak to off" 627 depends on DEBUG_KMEMLEAK 628 help 629 Say Y here to disable kmemleak by default. It can then be enabled 630 on the command line via kmemleak=on. 631 632config DEBUG_KMEMLEAK_AUTO_SCAN 633 bool "Enable kmemleak auto scan thread on boot up" 634 default y 635 depends on DEBUG_KMEMLEAK 636 help 637 Depending on the cpu, kmemleak scan may be cpu intensive and can 638 stall user tasks at times. This option enables/disables automatic 639 kmemleak scan at boot up. 640 641 Say N here to disable kmemleak auto scan thread to stop automatic 642 scanning. Disabling this option disables automatic reporting of 643 memory leaks. 644 645 If unsure, say Y. 646 647config DEBUG_STACK_USAGE 648 bool "Stack utilization instrumentation" 649 depends on DEBUG_KERNEL && !IA64 650 help 651 Enables the display of the minimum amount of free stack which each 652 task has ever had available in the sysrq-T and sysrq-P debug output. 653 654 This option will slow down process creation somewhat. 655 656config DEBUG_VM 657 bool "Debug VM" 658 depends on DEBUG_KERNEL 659 help 660 Enable this to turn on extended checks in the virtual-memory system 661 that may impact performance. 662 663 If unsure, say N. 664 665config DEBUG_VM_VMACACHE 666 bool "Debug VMA caching" 667 depends on DEBUG_VM 668 help 669 Enable this to turn on VMA caching debug information. Doing so 670 can cause significant overhead, so only enable it in non-production 671 environments. 672 673 If unsure, say N. 674 675config DEBUG_VM_RB 676 bool "Debug VM red-black trees" 677 depends on DEBUG_VM 678 help 679 Enable VM red-black tree debugging information and extra validations. 680 681 If unsure, say N. 682 683config DEBUG_VM_PGFLAGS 684 bool "Debug page-flags operations" 685 depends on DEBUG_VM 686 help 687 Enables extra validation on page flags operations. 688 689 If unsure, say N. 690 691config ARCH_HAS_DEBUG_VIRTUAL 692 bool 693 694config DEBUG_VIRTUAL 695 bool "Debug VM translations" 696 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL 697 help 698 Enable some costly sanity checks in virtual to page code. This can 699 catch mistakes with virt_to_page() and friends. 700 701 If unsure, say N. 702 703config DEBUG_NOMMU_REGIONS 704 bool "Debug the global anon/private NOMMU mapping region tree" 705 depends on DEBUG_KERNEL && !MMU 706 help 707 This option causes the global tree of anonymous and private mapping 708 regions to be regularly checked for invalid topology. 709 710config DEBUG_MEMORY_INIT 711 bool "Debug memory initialisation" if EXPERT 712 default !EXPERT 713 help 714 Enable this for additional checks during memory initialisation. 715 The sanity checks verify aspects of the VM such as the memory model 716 and other information provided by the architecture. Verbose 717 information will be printed at KERN_DEBUG loglevel depending 718 on the mminit_loglevel= command-line option. 719 720 If unsure, say Y 721 722config MEMORY_NOTIFIER_ERROR_INJECT 723 tristate "Memory hotplug notifier error injection module" 724 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION 725 help 726 This option provides the ability to inject artificial errors to 727 memory hotplug notifier chain callbacks. It is controlled through 728 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 729 730 If the notifier call chain should be failed with some events 731 notified, write the error code to "actions/<notifier event>/error". 732 733 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 734 735 # cd /sys/kernel/debug/notifier-error-inject/memory 736 # echo -12 > actions/MEM_GOING_OFFLINE/error 737 # echo offline > /sys/devices/system/memory/memoryXXX/state 738 bash: echo: write error: Cannot allocate memory 739 740 To compile this code as a module, choose M here: the module will 741 be called memory-notifier-error-inject. 742 743 If unsure, say N. 744 745config DEBUG_PER_CPU_MAPS 746 bool "Debug access to per_cpu maps" 747 depends on DEBUG_KERNEL 748 depends on SMP 749 help 750 Say Y to verify that the per_cpu map being accessed has 751 been set up. This adds a fair amount of code to kernel memory 752 and decreases performance. 753 754 Say N if unsure. 755 756config DEBUG_HIGHMEM 757 bool "Highmem debugging" 758 depends on DEBUG_KERNEL && HIGHMEM 759 help 760 This option enables additional error checking for high memory 761 systems. Disable for production systems. 762 763config HAVE_DEBUG_STACKOVERFLOW 764 bool 765 766config DEBUG_STACKOVERFLOW 767 bool "Check for stack overflows" 768 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 769 ---help--- 770 Say Y here if you want to check for overflows of kernel, IRQ 771 and exception stacks (if your architecture uses them). This 772 option will show detailed messages if free stack space drops 773 below a certain limit. 774 775 These kinds of bugs usually occur when call-chains in the 776 kernel get too deep, especially when interrupts are 777 involved. 778 779 Use this in cases where you see apparently random memory 780 corruption, especially if it appears in 'struct thread_info' 781 782 If in doubt, say "N". 783 784source "lib/Kconfig.kasan" 785 786endmenu # "Memory Debugging" 787 788config ARCH_HAS_KCOV 789 bool 790 help 791 An architecture should select this when it can successfully 792 build and run with CONFIG_KCOV. This typically requires 793 disabling instrumentation for some early boot code. 794 795config CC_HAS_SANCOV_TRACE_PC 796 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 797 798config KCOV 799 bool "Code coverage for fuzzing" 800 depends on ARCH_HAS_KCOV 801 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 802 select DEBUG_FS 803 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 804 help 805 KCOV exposes kernel code coverage information in a form suitable 806 for coverage-guided fuzzing (randomized testing). 807 808 If RANDOMIZE_BASE is enabled, PC values will not be stable across 809 different machines and across reboots. If you need stable PC values, 810 disable RANDOMIZE_BASE. 811 812 For more details, see Documentation/dev-tools/kcov.rst. 813 814config KCOV_ENABLE_COMPARISONS 815 bool "Enable comparison operands collection by KCOV" 816 depends on KCOV 817 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 818 help 819 KCOV also exposes operands of every comparison in the instrumented 820 code along with operand sizes and PCs of the comparison instructions. 821 These operands can be used by fuzzing engines to improve the quality 822 of fuzzing coverage. 823 824config KCOV_INSTRUMENT_ALL 825 bool "Instrument all code by default" 826 depends on KCOV 827 default y 828 help 829 If you are doing generic system call fuzzing (like e.g. syzkaller), 830 then you will want to instrument the whole kernel and you should 831 say y here. If you are doing more targeted fuzzing (like e.g. 832 filesystem fuzzing with AFL) then you will want to enable coverage 833 for more specific subsets of files, and should say n here. 834 835config DEBUG_SHIRQ 836 bool "Debug shared IRQ handlers" 837 depends on DEBUG_KERNEL 838 help 839 Enable this to generate a spurious interrupt as soon as a shared 840 interrupt handler is registered, and just before one is deregistered. 841 Drivers ought to be able to handle interrupts coming in at those 842 points; some don't and need to be caught. 843 844menu "Debug Lockups and Hangs" 845 846config LOCKUP_DETECTOR 847 bool 848 849config SOFTLOCKUP_DETECTOR 850 bool "Detect Soft Lockups" 851 depends on DEBUG_KERNEL && !S390 852 select LOCKUP_DETECTOR 853 help 854 Say Y here to enable the kernel to act as a watchdog to detect 855 soft lockups. 856 857 Softlockups are bugs that cause the kernel to loop in kernel 858 mode for more than 20 seconds, without giving other tasks a 859 chance to run. The current stack trace is displayed upon 860 detection and the system will stay locked up. 861 862config BOOTPARAM_SOFTLOCKUP_PANIC 863 bool "Panic (Reboot) On Soft Lockups" 864 depends on SOFTLOCKUP_DETECTOR 865 help 866 Say Y here to enable the kernel to panic on "soft lockups", 867 which are bugs that cause the kernel to loop in kernel 868 mode for more than 20 seconds (configurable using the watchdog_thresh 869 sysctl), without giving other tasks a chance to run. 870 871 The panic can be used in combination with panic_timeout, 872 to cause the system to reboot automatically after a 873 lockup has been detected. This feature is useful for 874 high-availability systems that have uptime guarantees and 875 where a lockup must be resolved ASAP. 876 877 Say N if unsure. 878 879config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE 880 int 881 depends on SOFTLOCKUP_DETECTOR 882 range 0 1 883 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC 884 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC 885 886config HARDLOCKUP_DETECTOR_PERF 887 bool 888 select SOFTLOCKUP_DETECTOR 889 890# 891# Enables a timestamp based low pass filter to compensate for perf based 892# hard lockup detection which runs too fast due to turbo modes. 893# 894config HARDLOCKUP_CHECK_TIMESTAMP 895 bool 896 897# 898# arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard 899# lockup detector rather than the perf based detector. 900# 901config HARDLOCKUP_DETECTOR 902 bool "Detect Hard Lockups" 903 depends on DEBUG_KERNEL && !S390 904 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH 905 select LOCKUP_DETECTOR 906 select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF 907 select HARDLOCKUP_DETECTOR_ARCH if HAVE_HARDLOCKUP_DETECTOR_ARCH 908 help 909 Say Y here to enable the kernel to act as a watchdog to detect 910 hard lockups. 911 912 Hardlockups are bugs that cause the CPU to loop in kernel mode 913 for more than 10 seconds, without letting other interrupts have a 914 chance to run. The current stack trace is displayed upon detection 915 and the system will stay locked up. 916 917config BOOTPARAM_HARDLOCKUP_PANIC 918 bool "Panic (Reboot) On Hard Lockups" 919 depends on HARDLOCKUP_DETECTOR 920 help 921 Say Y here to enable the kernel to panic on "hard lockups", 922 which are bugs that cause the kernel to loop in kernel 923 mode with interrupts disabled for more than 10 seconds (configurable 924 using the watchdog_thresh sysctl). 925 926 Say N if unsure. 927 928config BOOTPARAM_HARDLOCKUP_PANIC_VALUE 929 int 930 depends on HARDLOCKUP_DETECTOR 931 range 0 1 932 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC 933 default 1 if BOOTPARAM_HARDLOCKUP_PANIC 934 935config DETECT_HUNG_TASK 936 bool "Detect Hung Tasks" 937 depends on DEBUG_KERNEL 938 default SOFTLOCKUP_DETECTOR 939 help 940 Say Y here to enable the kernel to detect "hung tasks", 941 which are bugs that cause the task to be stuck in 942 uninterruptible "D" state indefinitely. 943 944 When a hung task is detected, the kernel will print the 945 current stack trace (which you should report), but the 946 task will stay in uninterruptible state. If lockdep is 947 enabled then all held locks will also be reported. This 948 feature has negligible overhead. 949 950config DEFAULT_HUNG_TASK_TIMEOUT 951 int "Default timeout for hung task detection (in seconds)" 952 depends on DETECT_HUNG_TASK 953 default 120 954 help 955 This option controls the default timeout (in seconds) used 956 to determine when a task has become non-responsive and should 957 be considered hung. 958 959 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 960 sysctl or by writing a value to 961 /proc/sys/kernel/hung_task_timeout_secs. 962 963 A timeout of 0 disables the check. The default is two minutes. 964 Keeping the default should be fine in most cases. 965 966config BOOTPARAM_HUNG_TASK_PANIC 967 bool "Panic (Reboot) On Hung Tasks" 968 depends on DETECT_HUNG_TASK 969 help 970 Say Y here to enable the kernel to panic on "hung tasks", 971 which are bugs that cause the kernel to leave a task stuck 972 in uninterruptible "D" state. 973 974 The panic can be used in combination with panic_timeout, 975 to cause the system to reboot automatically after a 976 hung task has been detected. This feature is useful for 977 high-availability systems that have uptime guarantees and 978 where a hung tasks must be resolved ASAP. 979 980 Say N if unsure. 981 982config BOOTPARAM_HUNG_TASK_PANIC_VALUE 983 int 984 depends on DETECT_HUNG_TASK 985 range 0 1 986 default 0 if !BOOTPARAM_HUNG_TASK_PANIC 987 default 1 if BOOTPARAM_HUNG_TASK_PANIC 988 989config WQ_WATCHDOG 990 bool "Detect Workqueue Stalls" 991 depends on DEBUG_KERNEL 992 help 993 Say Y here to enable stall detection on workqueues. If a 994 worker pool doesn't make forward progress on a pending work 995 item for over a given amount of time, 30s by default, a 996 warning message is printed along with dump of workqueue 997 state. This can be configured through kernel parameter 998 "workqueue.watchdog_thresh" and its sysfs counterpart. 999 1000endmenu # "Debug lockups and hangs" 1001 1002config PANIC_ON_OOPS 1003 bool "Panic on Oops" 1004 help 1005 Say Y here to enable the kernel to panic when it oopses. This 1006 has the same effect as setting oops=panic on the kernel command 1007 line. 1008 1009 This feature is useful to ensure that the kernel does not do 1010 anything erroneous after an oops which could result in data 1011 corruption or other issues. 1012 1013 Say N if unsure. 1014 1015config PANIC_ON_OOPS_VALUE 1016 int 1017 range 0 1 1018 default 0 if !PANIC_ON_OOPS 1019 default 1 if PANIC_ON_OOPS 1020 1021config PANIC_TIMEOUT 1022 int "panic timeout" 1023 default 0 1024 help 1025 Set the timeout value (in seconds) until a reboot occurs when the 1026 the kernel panics. If n = 0, then we wait forever. A timeout 1027 value n > 0 will wait n seconds before rebooting, while a timeout 1028 value n < 0 will reboot immediately. 1029 1030config SCHED_DEBUG 1031 bool "Collect scheduler debugging info" 1032 depends on DEBUG_KERNEL && PROC_FS 1033 default y 1034 help 1035 If you say Y here, the /proc/sched_debug file will be provided 1036 that can help debug the scheduler. The runtime overhead of this 1037 option is minimal. 1038 1039config SCHED_INFO 1040 bool 1041 default n 1042 1043config SCHEDSTATS 1044 bool "Collect scheduler statistics" 1045 depends on DEBUG_KERNEL && PROC_FS 1046 select SCHED_INFO 1047 help 1048 If you say Y here, additional code will be inserted into the 1049 scheduler and related routines to collect statistics about 1050 scheduler behavior and provide them in /proc/schedstat. These 1051 stats may be useful for both tuning and debugging the scheduler 1052 If you aren't debugging the scheduler or trying to tune a specific 1053 application, you can say N to avoid the very slight overhead 1054 this adds. 1055 1056config SCHED_STACK_END_CHECK 1057 bool "Detect stack corruption on calls to schedule()" 1058 depends on DEBUG_KERNEL 1059 default n 1060 help 1061 This option checks for a stack overrun on calls to schedule(). 1062 If the stack end location is found to be over written always panic as 1063 the content of the corrupted region can no longer be trusted. 1064 This is to ensure no erroneous behaviour occurs which could result in 1065 data corruption or a sporadic crash at a later stage once the region 1066 is examined. The runtime overhead introduced is minimal. 1067 1068config DEBUG_TIMEKEEPING 1069 bool "Enable extra timekeeping sanity checking" 1070 help 1071 This option will enable additional timekeeping sanity checks 1072 which may be helpful when diagnosing issues where timekeeping 1073 problems are suspected. 1074 1075 This may include checks in the timekeeping hotpaths, so this 1076 option may have a (very small) performance impact to some 1077 workloads. 1078 1079 If unsure, say N. 1080 1081config DEBUG_PREEMPT 1082 bool "Debug preemptible kernel" 1083 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT 1084 default y 1085 help 1086 If you say Y here then the kernel will use a debug variant of the 1087 commonly used smp_processor_id() function and will print warnings 1088 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1089 will detect preemption count underflows. 1090 1091menu "Lock Debugging (spinlocks, mutexes, etc...)" 1092 1093config LOCK_DEBUGGING_SUPPORT 1094 bool 1095 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1096 default y 1097 1098config PROVE_LOCKING 1099 bool "Lock debugging: prove locking correctness" 1100 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1101 select LOCKDEP 1102 select DEBUG_SPINLOCK 1103 select DEBUG_MUTEXES 1104 select DEBUG_RT_MUTEXES if RT_MUTEXES 1105 select DEBUG_RWSEMS 1106 select DEBUG_WW_MUTEX_SLOWPATH 1107 select DEBUG_LOCK_ALLOC 1108 select TRACE_IRQFLAGS 1109 default n 1110 help 1111 This feature enables the kernel to prove that all locking 1112 that occurs in the kernel runtime is mathematically 1113 correct: that under no circumstance could an arbitrary (and 1114 not yet triggered) combination of observed locking 1115 sequences (on an arbitrary number of CPUs, running an 1116 arbitrary number of tasks and interrupt contexts) cause a 1117 deadlock. 1118 1119 In short, this feature enables the kernel to report locking 1120 related deadlocks before they actually occur. 1121 1122 The proof does not depend on how hard and complex a 1123 deadlock scenario would be to trigger: how many 1124 participant CPUs, tasks and irq-contexts would be needed 1125 for it to trigger. The proof also does not depend on 1126 timing: if a race and a resulting deadlock is possible 1127 theoretically (no matter how unlikely the race scenario 1128 is), it will be proven so and will immediately be 1129 reported by the kernel (once the event is observed that 1130 makes the deadlock theoretically possible). 1131 1132 If a deadlock is impossible (i.e. the locking rules, as 1133 observed by the kernel, are mathematically correct), the 1134 kernel reports nothing. 1135 1136 NOTE: this feature can also be enabled for rwlocks, mutexes 1137 and rwsems - in which case all dependencies between these 1138 different locking variants are observed and mapped too, and 1139 the proof of observed correctness is also maintained for an 1140 arbitrary combination of these separate locking variants. 1141 1142 For more details, see Documentation/locking/lockdep-design.rst. 1143 1144config LOCK_STAT 1145 bool "Lock usage statistics" 1146 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1147 select LOCKDEP 1148 select DEBUG_SPINLOCK 1149 select DEBUG_MUTEXES 1150 select DEBUG_RT_MUTEXES if RT_MUTEXES 1151 select DEBUG_LOCK_ALLOC 1152 default n 1153 help 1154 This feature enables tracking lock contention points 1155 1156 For more details, see Documentation/locking/lockstat.rst 1157 1158 This also enables lock events required by "perf lock", 1159 subcommand of perf. 1160 If you want to use "perf lock", you also need to turn on 1161 CONFIG_EVENT_TRACING. 1162 1163 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1164 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1165 1166config DEBUG_RT_MUTEXES 1167 bool "RT Mutex debugging, deadlock detection" 1168 depends on DEBUG_KERNEL && RT_MUTEXES 1169 help 1170 This allows rt mutex semantics violations and rt mutex related 1171 deadlocks (lockups) to be detected and reported automatically. 1172 1173config DEBUG_SPINLOCK 1174 bool "Spinlock and rw-lock debugging: basic checks" 1175 depends on DEBUG_KERNEL 1176 select UNINLINE_SPIN_UNLOCK 1177 help 1178 Say Y here and build SMP to catch missing spinlock initialization 1179 and certain other kinds of spinlock errors commonly made. This is 1180 best used in conjunction with the NMI watchdog so that spinlock 1181 deadlocks are also debuggable. 1182 1183config DEBUG_MUTEXES 1184 bool "Mutex debugging: basic checks" 1185 depends on DEBUG_KERNEL 1186 help 1187 This feature allows mutex semantics violations to be detected and 1188 reported. 1189 1190config DEBUG_WW_MUTEX_SLOWPATH 1191 bool "Wait/wound mutex debugging: Slowpath testing" 1192 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1193 select DEBUG_LOCK_ALLOC 1194 select DEBUG_SPINLOCK 1195 select DEBUG_MUTEXES 1196 help 1197 This feature enables slowpath testing for w/w mutex users by 1198 injecting additional -EDEADLK wound/backoff cases. Together with 1199 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1200 will test all possible w/w mutex interface abuse with the 1201 exception of simply not acquiring all the required locks. 1202 Note that this feature can introduce significant overhead, so 1203 it really should not be enabled in a production or distro kernel, 1204 even a debug kernel. If you are a driver writer, enable it. If 1205 you are a distro, do not. 1206 1207config DEBUG_RWSEMS 1208 bool "RW Semaphore debugging: basic checks" 1209 depends on DEBUG_KERNEL 1210 help 1211 This debugging feature allows mismatched rw semaphore locks 1212 and unlocks to be detected and reported. 1213 1214config DEBUG_LOCK_ALLOC 1215 bool "Lock debugging: detect incorrect freeing of live locks" 1216 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1217 select DEBUG_SPINLOCK 1218 select DEBUG_MUTEXES 1219 select DEBUG_RT_MUTEXES if RT_MUTEXES 1220 select LOCKDEP 1221 help 1222 This feature will check whether any held lock (spinlock, rwlock, 1223 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1224 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1225 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1226 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1227 held during task exit. 1228 1229config LOCKDEP 1230 bool 1231 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1232 select STACKTRACE 1233 select FRAME_POINTER if !MIPS && !PPC && !ARM && !S390 && !MICROBLAZE && !ARC && !X86 1234 select KALLSYMS 1235 select KALLSYMS_ALL 1236 1237config LOCKDEP_SMALL 1238 bool 1239 1240config DEBUG_LOCKDEP 1241 bool "Lock dependency engine debugging" 1242 depends on DEBUG_KERNEL && LOCKDEP 1243 help 1244 If you say Y here, the lock dependency engine will do 1245 additional runtime checks to debug itself, at the price 1246 of more runtime overhead. 1247 1248config DEBUG_ATOMIC_SLEEP 1249 bool "Sleep inside atomic section checking" 1250 select PREEMPT_COUNT 1251 depends on DEBUG_KERNEL 1252 depends on !ARCH_NO_PREEMPT 1253 help 1254 If you say Y here, various routines which may sleep will become very 1255 noisy if they are called inside atomic sections: when a spinlock is 1256 held, inside an rcu read side critical section, inside preempt disabled 1257 sections, inside an interrupt, etc... 1258 1259config DEBUG_LOCKING_API_SELFTESTS 1260 bool "Locking API boot-time self-tests" 1261 depends on DEBUG_KERNEL 1262 help 1263 Say Y here if you want the kernel to run a short self-test during 1264 bootup. The self-test checks whether common types of locking bugs 1265 are detected by debugging mechanisms or not. (if you disable 1266 lock debugging then those bugs wont be detected of course.) 1267 The following locking APIs are covered: spinlocks, rwlocks, 1268 mutexes and rwsems. 1269 1270config LOCK_TORTURE_TEST 1271 tristate "torture tests for locking" 1272 depends on DEBUG_KERNEL 1273 select TORTURE_TEST 1274 help 1275 This option provides a kernel module that runs torture tests 1276 on kernel locking primitives. The kernel module may be built 1277 after the fact on the running kernel to be tested, if desired. 1278 1279 Say Y here if you want kernel locking-primitive torture tests 1280 to be built into the kernel. 1281 Say M if you want these torture tests to build as a module. 1282 Say N if you are unsure. 1283 1284config WW_MUTEX_SELFTEST 1285 tristate "Wait/wound mutex selftests" 1286 help 1287 This option provides a kernel module that runs tests on the 1288 on the struct ww_mutex locking API. 1289 1290 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1291 with this test harness. 1292 1293 Say M if you want these self tests to build as a module. 1294 Say N if you are unsure. 1295 1296endmenu # lock debugging 1297 1298config TRACE_IRQFLAGS 1299 bool 1300 help 1301 Enables hooks to interrupt enabling and disabling for 1302 either tracing or lock debugging. 1303 1304config STACKTRACE 1305 bool "Stack backtrace support" 1306 depends on STACKTRACE_SUPPORT 1307 help 1308 This option causes the kernel to create a /proc/pid/stack for 1309 every process, showing its current stack trace. 1310 It is also used by various kernel debugging features that require 1311 stack trace generation. 1312 1313config WARN_ALL_UNSEEDED_RANDOM 1314 bool "Warn for all uses of unseeded randomness" 1315 default n 1316 help 1317 Some parts of the kernel contain bugs relating to their use of 1318 cryptographically secure random numbers before it's actually possible 1319 to generate those numbers securely. This setting ensures that these 1320 flaws don't go unnoticed, by enabling a message, should this ever 1321 occur. This will allow people with obscure setups to know when things 1322 are going wrong, so that they might contact developers about fixing 1323 it. 1324 1325 Unfortunately, on some models of some architectures getting 1326 a fully seeded CRNG is extremely difficult, and so this can 1327 result in dmesg getting spammed for a surprisingly long 1328 time. This is really bad from a security perspective, and 1329 so architecture maintainers really need to do what they can 1330 to get the CRNG seeded sooner after the system is booted. 1331 However, since users cannot do anything actionable to 1332 address this, by default the kernel will issue only a single 1333 warning for the first use of unseeded randomness. 1334 1335 Say Y here if you want to receive warnings for all uses of 1336 unseeded randomness. This will be of use primarily for 1337 those developers interested in improving the security of 1338 Linux kernels running on their architecture (or 1339 subarchitecture). 1340 1341config DEBUG_KOBJECT 1342 bool "kobject debugging" 1343 depends on DEBUG_KERNEL 1344 help 1345 If you say Y here, some extra kobject debugging messages will be sent 1346 to the syslog. 1347 1348config DEBUG_KOBJECT_RELEASE 1349 bool "kobject release debugging" 1350 depends on DEBUG_OBJECTS_TIMERS 1351 help 1352 kobjects are reference counted objects. This means that their 1353 last reference count put is not predictable, and the kobject can 1354 live on past the point at which a driver decides to drop it's 1355 initial reference to the kobject gained on allocation. An 1356 example of this would be a struct device which has just been 1357 unregistered. 1358 1359 However, some buggy drivers assume that after such an operation, 1360 the memory backing the kobject can be immediately freed. This 1361 goes completely against the principles of a refcounted object. 1362 1363 If you say Y here, the kernel will delay the release of kobjects 1364 on the last reference count to improve the visibility of this 1365 kind of kobject release bug. 1366 1367config HAVE_DEBUG_BUGVERBOSE 1368 bool 1369 1370config DEBUG_BUGVERBOSE 1371 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT 1372 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE) 1373 default y 1374 help 1375 Say Y here to make BUG() panics output the file name and line number 1376 of the BUG call as well as the EIP and oops trace. This aids 1377 debugging but costs about 70-100K of memory. 1378 1379config DEBUG_LIST 1380 bool "Debug linked list manipulation" 1381 depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION 1382 help 1383 Enable this to turn on extended checks in the linked-list 1384 walking routines. 1385 1386 If unsure, say N. 1387 1388config DEBUG_PLIST 1389 bool "Debug priority linked list manipulation" 1390 depends on DEBUG_KERNEL 1391 help 1392 Enable this to turn on extended checks in the priority-ordered 1393 linked-list (plist) walking routines. This checks the entire 1394 list multiple times during each manipulation. 1395 1396 If unsure, say N. 1397 1398config DEBUG_SG 1399 bool "Debug SG table operations" 1400 depends on DEBUG_KERNEL 1401 help 1402 Enable this to turn on checks on scatter-gather tables. This can 1403 help find problems with drivers that do not properly initialize 1404 their sg tables. 1405 1406 If unsure, say N. 1407 1408config DEBUG_NOTIFIERS 1409 bool "Debug notifier call chains" 1410 depends on DEBUG_KERNEL 1411 help 1412 Enable this to turn on sanity checking for notifier call chains. 1413 This is most useful for kernel developers to make sure that 1414 modules properly unregister themselves from notifier chains. 1415 This is a relatively cheap check but if you care about maximum 1416 performance, say N. 1417 1418config DEBUG_CREDENTIALS 1419 bool "Debug credential management" 1420 depends on DEBUG_KERNEL 1421 help 1422 Enable this to turn on some debug checking for credential 1423 management. The additional code keeps track of the number of 1424 pointers from task_structs to any given cred struct, and checks to 1425 see that this number never exceeds the usage count of the cred 1426 struct. 1427 1428 Furthermore, if SELinux is enabled, this also checks that the 1429 security pointer in the cred struct is never seen to be invalid. 1430 1431 If unsure, say N. 1432 1433source "kernel/rcu/Kconfig.debug" 1434 1435config DEBUG_WQ_FORCE_RR_CPU 1436 bool "Force round-robin CPU selection for unbound work items" 1437 depends on DEBUG_KERNEL 1438 default n 1439 help 1440 Workqueue used to implicitly guarantee that work items queued 1441 without explicit CPU specified are put on the local CPU. This 1442 guarantee is no longer true and while local CPU is still 1443 preferred work items may be put on foreign CPUs. Kernel 1444 parameter "workqueue.debug_force_rr_cpu" is added to force 1445 round-robin CPU selection to flush out usages which depend on the 1446 now broken guarantee. This config option enables the debug 1447 feature by default. When enabled, memory and cache locality will 1448 be impacted. 1449 1450config DEBUG_BLOCK_EXT_DEVT 1451 bool "Force extended block device numbers and spread them" 1452 depends on DEBUG_KERNEL 1453 depends on BLOCK 1454 default n 1455 help 1456 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON 1457 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT 1458 YOU ARE DOING. Distros, please enable this and fix whatever 1459 is broken. 1460 1461 Conventionally, block device numbers are allocated from 1462 predetermined contiguous area. However, extended block area 1463 may introduce non-contiguous block device numbers. This 1464 option forces most block device numbers to be allocated from 1465 the extended space and spreads them to discover kernel or 1466 userland code paths which assume predetermined contiguous 1467 device number allocation. 1468 1469 Note that turning on this debug option shuffles all the 1470 device numbers for all IDE and SCSI devices including libata 1471 ones, so root partition specified using device number 1472 directly (via rdev or root=MAJ:MIN) won't work anymore. 1473 Textual device names (root=/dev/sdXn) will continue to work. 1474 1475 Say N if you are unsure. 1476 1477config CPU_HOTPLUG_STATE_CONTROL 1478 bool "Enable CPU hotplug state control" 1479 depends on DEBUG_KERNEL 1480 depends on HOTPLUG_CPU 1481 default n 1482 help 1483 Allows to write steps between "offline" and "online" to the CPUs 1484 sysfs target file so states can be stepped granular. This is a debug 1485 option for now as the hotplug machinery cannot be stopped and 1486 restarted at arbitrary points yet. 1487 1488 Say N if your are unsure. 1489 1490config NOTIFIER_ERROR_INJECTION 1491 tristate "Notifier error injection" 1492 depends on DEBUG_KERNEL 1493 select DEBUG_FS 1494 help 1495 This option provides the ability to inject artificial errors to 1496 specified notifier chain callbacks. It is useful to test the error 1497 handling of notifier call chain failures. 1498 1499 Say N if unsure. 1500 1501config PM_NOTIFIER_ERROR_INJECT 1502 tristate "PM notifier error injection module" 1503 depends on PM && NOTIFIER_ERROR_INJECTION 1504 default m if PM_DEBUG 1505 help 1506 This option provides the ability to inject artificial errors to 1507 PM notifier chain callbacks. It is controlled through debugfs 1508 interface /sys/kernel/debug/notifier-error-inject/pm 1509 1510 If the notifier call chain should be failed with some events 1511 notified, write the error code to "actions/<notifier event>/error". 1512 1513 Example: Inject PM suspend error (-12 = -ENOMEM) 1514 1515 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1516 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1517 # echo mem > /sys/power/state 1518 bash: echo: write error: Cannot allocate memory 1519 1520 To compile this code as a module, choose M here: the module will 1521 be called pm-notifier-error-inject. 1522 1523 If unsure, say N. 1524 1525config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1526 tristate "OF reconfig notifier error injection module" 1527 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1528 help 1529 This option provides the ability to inject artificial errors to 1530 OF reconfig notifier chain callbacks. It is controlled 1531 through debugfs interface under 1532 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1533 1534 If the notifier call chain should be failed with some events 1535 notified, write the error code to "actions/<notifier event>/error". 1536 1537 To compile this code as a module, choose M here: the module will 1538 be called of-reconfig-notifier-error-inject. 1539 1540 If unsure, say N. 1541 1542config NETDEV_NOTIFIER_ERROR_INJECT 1543 tristate "Netdev notifier error injection module" 1544 depends on NET && NOTIFIER_ERROR_INJECTION 1545 help 1546 This option provides the ability to inject artificial errors to 1547 netdevice notifier chain callbacks. It is controlled through debugfs 1548 interface /sys/kernel/debug/notifier-error-inject/netdev 1549 1550 If the notifier call chain should be failed with some events 1551 notified, write the error code to "actions/<notifier event>/error". 1552 1553 Example: Inject netdevice mtu change error (-22 = -EINVAL) 1554 1555 # cd /sys/kernel/debug/notifier-error-inject/netdev 1556 # echo -22 > actions/NETDEV_CHANGEMTU/error 1557 # ip link set eth0 mtu 1024 1558 RTNETLINK answers: Invalid argument 1559 1560 To compile this code as a module, choose M here: the module will 1561 be called netdev-notifier-error-inject. 1562 1563 If unsure, say N. 1564 1565config FUNCTION_ERROR_INJECTION 1566 def_bool y 1567 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 1568 1569config FAULT_INJECTION 1570 bool "Fault-injection framework" 1571 depends on DEBUG_KERNEL 1572 help 1573 Provide fault-injection framework. 1574 For more details, see Documentation/fault-injection/. 1575 1576config FAILSLAB 1577 bool "Fault-injection capability for kmalloc" 1578 depends on FAULT_INJECTION 1579 depends on SLAB || SLUB 1580 help 1581 Provide fault-injection capability for kmalloc. 1582 1583config FAIL_PAGE_ALLOC 1584 bool "Fault-injection capabilitiy for alloc_pages()" 1585 depends on FAULT_INJECTION 1586 help 1587 Provide fault-injection capability for alloc_pages(). 1588 1589config FAIL_MAKE_REQUEST 1590 bool "Fault-injection capability for disk IO" 1591 depends on FAULT_INJECTION && BLOCK 1592 help 1593 Provide fault-injection capability for disk IO. 1594 1595config FAIL_IO_TIMEOUT 1596 bool "Fault-injection capability for faking disk interrupts" 1597 depends on FAULT_INJECTION && BLOCK 1598 help 1599 Provide fault-injection capability on end IO handling. This 1600 will make the block layer "forget" an interrupt as configured, 1601 thus exercising the error handling. 1602 1603 Only works with drivers that use the generic timeout handling, 1604 for others it wont do anything. 1605 1606config FAIL_FUTEX 1607 bool "Fault-injection capability for futexes" 1608 select DEBUG_FS 1609 depends on FAULT_INJECTION && FUTEX 1610 help 1611 Provide fault-injection capability for futexes. 1612 1613config FAULT_INJECTION_DEBUG_FS 1614 bool "Debugfs entries for fault-injection capabilities" 1615 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 1616 help 1617 Enable configuration of fault-injection capabilities via debugfs. 1618 1619config FAIL_FUNCTION 1620 bool "Fault-injection capability for functions" 1621 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 1622 help 1623 Provide function-based fault-injection capability. 1624 This will allow you to override a specific function with a return 1625 with given return value. As a result, function caller will see 1626 an error value and have to handle it. This is useful to test the 1627 error handling in various subsystems. 1628 1629config FAIL_MMC_REQUEST 1630 bool "Fault-injection capability for MMC IO" 1631 depends on FAULT_INJECTION_DEBUG_FS && MMC 1632 help 1633 Provide fault-injection capability for MMC IO. 1634 This will make the mmc core return data errors. This is 1635 useful to test the error handling in the mmc block device 1636 and to test how the mmc host driver handles retries from 1637 the block device. 1638 1639config FAULT_INJECTION_STACKTRACE_FILTER 1640 bool "stacktrace filter for fault-injection capabilities" 1641 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 1642 depends on !X86_64 1643 select STACKTRACE 1644 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86 1645 help 1646 Provide stacktrace filter for fault-injection capabilities 1647 1648config LATENCYTOP 1649 bool "Latency measuring infrastructure" 1650 depends on DEBUG_KERNEL 1651 depends on STACKTRACE_SUPPORT 1652 depends on PROC_FS 1653 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86 1654 select KALLSYMS 1655 select KALLSYMS_ALL 1656 select STACKTRACE 1657 select SCHEDSTATS 1658 select SCHED_DEBUG 1659 help 1660 Enable this option if you want to use the LatencyTOP tool 1661 to find out which userspace is blocking on what kernel operations. 1662 1663source "kernel/trace/Kconfig" 1664 1665config PROVIDE_OHCI1394_DMA_INIT 1666 bool "Remote debugging over FireWire early on boot" 1667 depends on PCI && X86 1668 help 1669 If you want to debug problems which hang or crash the kernel early 1670 on boot and the crashing machine has a FireWire port, you can use 1671 this feature to remotely access the memory of the crashed machine 1672 over FireWire. This employs remote DMA as part of the OHCI1394 1673 specification which is now the standard for FireWire controllers. 1674 1675 With remote DMA, you can monitor the printk buffer remotely using 1676 firescope and access all memory below 4GB using fireproxy from gdb. 1677 Even controlling a kernel debugger is possible using remote DMA. 1678 1679 Usage: 1680 1681 If ohci1394_dma=early is used as boot parameter, it will initialize 1682 all OHCI1394 controllers which are found in the PCI config space. 1683 1684 As all changes to the FireWire bus such as enabling and disabling 1685 devices cause a bus reset and thereby disable remote DMA for all 1686 devices, be sure to have the cable plugged and FireWire enabled on 1687 the debugging host before booting the debug target for debugging. 1688 1689 This code (~1k) is freed after boot. By then, the firewire stack 1690 in charge of the OHCI-1394 controllers should be used instead. 1691 1692 See Documentation/debugging-via-ohci1394.txt for more information. 1693 1694menuconfig RUNTIME_TESTING_MENU 1695 bool "Runtime Testing" 1696 def_bool y 1697 1698if RUNTIME_TESTING_MENU 1699 1700config LKDTM 1701 tristate "Linux Kernel Dump Test Tool Module" 1702 depends on DEBUG_FS 1703 help 1704 This module enables testing of the different dumping mechanisms by 1705 inducing system failures at predefined crash points. 1706 If you don't need it: say N 1707 Choose M here to compile this code as a module. The module will be 1708 called lkdtm. 1709 1710 Documentation on how to use the module can be found in 1711 Documentation/fault-injection/provoke-crashes.rst 1712 1713config TEST_LIST_SORT 1714 tristate "Linked list sorting test" 1715 depends on DEBUG_KERNEL || m 1716 help 1717 Enable this to turn on 'list_sort()' function test. This test is 1718 executed only once during system boot (so affects only boot time), 1719 or at module load time. 1720 1721 If unsure, say N. 1722 1723config TEST_SORT 1724 tristate "Array-based sort test" 1725 depends on DEBUG_KERNEL || m 1726 help 1727 This option enables the self-test function of 'sort()' at boot, 1728 or at module load time. 1729 1730 If unsure, say N. 1731 1732config KPROBES_SANITY_TEST 1733 bool "Kprobes sanity tests" 1734 depends on DEBUG_KERNEL 1735 depends on KPROBES 1736 help 1737 This option provides for testing basic kprobes functionality on 1738 boot. Samples of kprobe and kretprobe are inserted and 1739 verified for functionality. 1740 1741 Say N if you are unsure. 1742 1743config BACKTRACE_SELF_TEST 1744 tristate "Self test for the backtrace code" 1745 depends on DEBUG_KERNEL 1746 help 1747 This option provides a kernel module that can be used to test 1748 the kernel stack backtrace code. This option is not useful 1749 for distributions or general kernels, but only for kernel 1750 developers working on architecture code. 1751 1752 Note that if you want to also test saved backtraces, you will 1753 have to enable STACKTRACE as well. 1754 1755 Say N if you are unsure. 1756 1757config RBTREE_TEST 1758 tristate "Red-Black tree test" 1759 depends on DEBUG_KERNEL 1760 help 1761 A benchmark measuring the performance of the rbtree library. 1762 Also includes rbtree invariant checks. 1763 1764config REED_SOLOMON_TEST 1765 tristate "Reed-Solomon library test" 1766 depends on DEBUG_KERNEL || m 1767 select REED_SOLOMON 1768 select REED_SOLOMON_ENC16 1769 select REED_SOLOMON_DEC16 1770 help 1771 This option enables the self-test function of rslib at boot, 1772 or at module load time. 1773 1774 If unsure, say N. 1775 1776config INTERVAL_TREE_TEST 1777 tristate "Interval tree test" 1778 depends on DEBUG_KERNEL 1779 select INTERVAL_TREE 1780 help 1781 A benchmark measuring the performance of the interval tree library 1782 1783config PERCPU_TEST 1784 tristate "Per cpu operations test" 1785 depends on m && DEBUG_KERNEL 1786 help 1787 Enable this option to build test module which validates per-cpu 1788 operations. 1789 1790 If unsure, say N. 1791 1792config ATOMIC64_SELFTEST 1793 tristate "Perform an atomic64_t self-test" 1794 help 1795 Enable this option to test the atomic64_t functions at boot or 1796 at module load time. 1797 1798 If unsure, say N. 1799 1800config ASYNC_RAID6_TEST 1801 tristate "Self test for hardware accelerated raid6 recovery" 1802 depends on ASYNC_RAID6_RECOV 1803 select ASYNC_MEMCPY 1804 ---help--- 1805 This is a one-shot self test that permutes through the 1806 recovery of all the possible two disk failure scenarios for a 1807 N-disk array. Recovery is performed with the asynchronous 1808 raid6 recovery routines, and will optionally use an offload 1809 engine if one is available. 1810 1811 If unsure, say N. 1812 1813config TEST_HEXDUMP 1814 tristate "Test functions located in the hexdump module at runtime" 1815 1816config TEST_STRING_HELPERS 1817 tristate "Test functions located in the string_helpers module at runtime" 1818 1819config TEST_STRSCPY 1820 tristate "Test strscpy*() family of functions at runtime" 1821 1822config TEST_KSTRTOX 1823 tristate "Test kstrto*() family of functions at runtime" 1824 1825config TEST_PRINTF 1826 tristate "Test printf() family of functions at runtime" 1827 1828config TEST_BITMAP 1829 tristate "Test bitmap_*() family of functions at runtime" 1830 help 1831 Enable this option to test the bitmap functions at boot. 1832 1833 If unsure, say N. 1834 1835config TEST_BITFIELD 1836 tristate "Test bitfield functions at runtime" 1837 help 1838 Enable this option to test the bitfield functions at boot. 1839 1840 If unsure, say N. 1841 1842config TEST_UUID 1843 tristate "Test functions located in the uuid module at runtime" 1844 1845config TEST_XARRAY 1846 tristate "Test the XArray code at runtime" 1847 1848config TEST_OVERFLOW 1849 tristate "Test check_*_overflow() functions at runtime" 1850 1851config TEST_RHASHTABLE 1852 tristate "Perform selftest on resizable hash table" 1853 help 1854 Enable this option to test the rhashtable functions at boot. 1855 1856 If unsure, say N. 1857 1858config TEST_HASH 1859 tristate "Perform selftest on hash functions" 1860 help 1861 Enable this option to test the kernel's integer (<linux/hash.h>), 1862 string (<linux/stringhash.h>), and siphash (<linux/siphash.h>) 1863 hash functions on boot (or module load). 1864 1865 This is intended to help people writing architecture-specific 1866 optimized versions. If unsure, say N. 1867 1868config TEST_IDA 1869 tristate "Perform selftest on IDA functions" 1870 1871config TEST_PARMAN 1872 tristate "Perform selftest on priority array manager" 1873 depends on PARMAN 1874 help 1875 Enable this option to test priority array manager on boot 1876 (or module load). 1877 1878 If unsure, say N. 1879 1880config TEST_IRQ_TIMINGS 1881 bool "IRQ timings selftest" 1882 depends on IRQ_TIMINGS 1883 help 1884 Enable this option to test the irq timings code on boot. 1885 1886 If unsure, say N. 1887 1888config TEST_LKM 1889 tristate "Test module loading with 'hello world' module" 1890 depends on m 1891 help 1892 This builds the "test_module" module that emits "Hello, world" 1893 on printk when loaded. It is designed to be used for basic 1894 evaluation of the module loading subsystem (for example when 1895 validating module verification). It lacks any extra dependencies, 1896 and will not normally be loaded by the system unless explicitly 1897 requested by name. 1898 1899 If unsure, say N. 1900 1901config TEST_VMALLOC 1902 tristate "Test module for stress/performance analysis of vmalloc allocator" 1903 default n 1904 depends on MMU 1905 depends on m 1906 help 1907 This builds the "test_vmalloc" module that should be used for 1908 stress and performance analysis. So, any new change for vmalloc 1909 subsystem can be evaluated from performance and stability point 1910 of view. 1911 1912 If unsure, say N. 1913 1914config TEST_USER_COPY 1915 tristate "Test user/kernel boundary protections" 1916 depends on m 1917 help 1918 This builds the "test_user_copy" module that runs sanity checks 1919 on the copy_to/from_user infrastructure, making sure basic 1920 user/kernel boundary testing is working. If it fails to load, 1921 a regression has been detected in the user/kernel memory boundary 1922 protections. 1923 1924 If unsure, say N. 1925 1926config TEST_BPF 1927 tristate "Test BPF filter functionality" 1928 depends on m && NET 1929 help 1930 This builds the "test_bpf" module that runs various test vectors 1931 against the BPF interpreter or BPF JIT compiler depending on the 1932 current setting. This is in particular useful for BPF JIT compiler 1933 development, but also to run regression tests against changes in 1934 the interpreter code. It also enables test stubs for eBPF maps and 1935 verifier used by user space verifier testsuite. 1936 1937 If unsure, say N. 1938 1939config TEST_BLACKHOLE_DEV 1940 tristate "Test blackhole netdev functionality" 1941 depends on m && NET 1942 help 1943 This builds the "test_blackhole_dev" module that validates the 1944 data path through this blackhole netdev. 1945 1946 If unsure, say N. 1947 1948config FIND_BIT_BENCHMARK 1949 tristate "Test find_bit functions" 1950 help 1951 This builds the "test_find_bit" module that measure find_*_bit() 1952 functions performance. 1953 1954 If unsure, say N. 1955 1956config TEST_FIRMWARE 1957 tristate "Test firmware loading via userspace interface" 1958 depends on FW_LOADER 1959 help 1960 This builds the "test_firmware" module that creates a userspace 1961 interface for testing firmware loading. This can be used to 1962 control the triggering of firmware loading without needing an 1963 actual firmware-using device. The contents can be rechecked by 1964 userspace. 1965 1966 If unsure, say N. 1967 1968config TEST_SYSCTL 1969 tristate "sysctl test driver" 1970 depends on PROC_SYSCTL 1971 help 1972 This builds the "test_sysctl" module. This driver enables to test the 1973 proc sysctl interfaces available to drivers safely without affecting 1974 production knobs which might alter system functionality. 1975 1976 If unsure, say N. 1977 1978config TEST_UDELAY 1979 tristate "udelay test driver" 1980 help 1981 This builds the "udelay_test" module that helps to make sure 1982 that udelay() is working properly. 1983 1984 If unsure, say N. 1985 1986config TEST_STATIC_KEYS 1987 tristate "Test static keys" 1988 depends on m 1989 help 1990 Test the static key interfaces. 1991 1992 If unsure, say N. 1993 1994config TEST_KMOD 1995 tristate "kmod stress tester" 1996 depends on m 1997 depends on NETDEVICES && NET_CORE && INET # for TUN 1998 depends on BLOCK 1999 select TEST_LKM 2000 select XFS_FS 2001 select TUN 2002 select BTRFS_FS 2003 help 2004 Test the kernel's module loading mechanism: kmod. kmod implements 2005 support to load modules using the Linux kernel's usermode helper. 2006 This test provides a series of tests against kmod. 2007 2008 Although technically you can either build test_kmod as a module or 2009 into the kernel we disallow building it into the kernel since 2010 it stress tests request_module() and this will very likely cause 2011 some issues by taking over precious threads available from other 2012 module load requests, ultimately this could be fatal. 2013 2014 To run tests run: 2015 2016 tools/testing/selftests/kmod/kmod.sh --help 2017 2018 If unsure, say N. 2019 2020config TEST_DEBUG_VIRTUAL 2021 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 2022 depends on DEBUG_VIRTUAL 2023 help 2024 Test the kernel's ability to detect incorrect calls to 2025 virt_to_phys() done against the non-linear part of the 2026 kernel's virtual address map. 2027 2028 If unsure, say N. 2029 2030config TEST_MEMCAT_P 2031 tristate "Test memcat_p() helper function" 2032 help 2033 Test the memcat_p() helper for correctly merging two 2034 pointer arrays together. 2035 2036 If unsure, say N. 2037 2038config TEST_LIVEPATCH 2039 tristate "Test livepatching" 2040 default n 2041 depends on DYNAMIC_DEBUG 2042 depends on LIVEPATCH 2043 depends on m 2044 help 2045 Test kernel livepatching features for correctness. The tests will 2046 load test modules that will be livepatched in various scenarios. 2047 2048 To run all the livepatching tests: 2049 2050 make -C tools/testing/selftests TARGETS=livepatch run_tests 2051 2052 Alternatively, individual tests may be invoked: 2053 2054 tools/testing/selftests/livepatch/test-callbacks.sh 2055 tools/testing/selftests/livepatch/test-livepatch.sh 2056 tools/testing/selftests/livepatch/test-shadow-vars.sh 2057 2058 If unsure, say N. 2059 2060config TEST_OBJAGG 2061 tristate "Perform selftest on object aggreration manager" 2062 default n 2063 depends on OBJAGG 2064 help 2065 Enable this option to test object aggregation manager on boot 2066 (or module load). 2067 2068 2069config TEST_STACKINIT 2070 tristate "Test level of stack variable initialization" 2071 help 2072 Test if the kernel is zero-initializing stack variables and 2073 padding. Coverage is controlled by compiler flags, 2074 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2075 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2076 2077 If unsure, say N. 2078 2079endif # RUNTIME_TESTING_MENU 2080 2081config MEMTEST 2082 bool "Memtest" 2083 ---help--- 2084 This option adds a kernel parameter 'memtest', which allows memtest 2085 to be set. 2086 memtest=0, mean disabled; -- default 2087 memtest=1, mean do 1 test pattern; 2088 ... 2089 memtest=17, mean do 17 test patterns. 2090 If you are unsure how to answer this question, answer N. 2091 2092config BUG_ON_DATA_CORRUPTION 2093 bool "Trigger a BUG when data corruption is detected" 2094 select DEBUG_LIST 2095 help 2096 Select this option if the kernel should BUG when it encounters 2097 data corruption in kernel memory structures when they get checked 2098 for validity. 2099 2100 If unsure, say N. 2101 2102source "samples/Kconfig" 2103 2104source "lib/Kconfig.kgdb" 2105 2106source "lib/Kconfig.ubsan" 2107 2108config ARCH_HAS_DEVMEM_IS_ALLOWED 2109 bool 2110 2111config STRICT_DEVMEM 2112 bool "Filter access to /dev/mem" 2113 depends on MMU && DEVMEM 2114 depends on ARCH_HAS_DEVMEM_IS_ALLOWED 2115 default y if PPC || X86 || ARM64 2116 ---help--- 2117 If this option is disabled, you allow userspace (root) access to all 2118 of memory, including kernel and userspace memory. Accidental 2119 access to this is obviously disastrous, but specific access can 2120 be used by people debugging the kernel. Note that with PAT support 2121 enabled, even in this case there are restrictions on /dev/mem 2122 use due to the cache aliasing requirements. 2123 2124 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 2125 file only allows userspace access to PCI space and the BIOS code and 2126 data regions. This is sufficient for dosemu and X and all common 2127 users of /dev/mem. 2128 2129 If in doubt, say Y. 2130 2131config IO_STRICT_DEVMEM 2132 bool "Filter I/O access to /dev/mem" 2133 depends on STRICT_DEVMEM 2134 ---help--- 2135 If this option is disabled, you allow userspace (root) access to all 2136 io-memory regardless of whether a driver is actively using that 2137 range. Accidental access to this is obviously disastrous, but 2138 specific access can be used by people debugging kernel drivers. 2139 2140 If this option is switched on, the /dev/mem file only allows 2141 userspace access to *idle* io-memory ranges (see /proc/iomem) This 2142 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 2143 if the driver using a given range cannot be disabled. 2144 2145 If in doubt, say Y. 2146 2147source "arch/$(SRCARCH)/Kconfig.debug" 2148 2149endmenu # Kernel hacking 2150