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