1menu "printk and dmesg options" 2 3config PRINTK_TIME 4 bool "Show timing information on printks" 5 depends on PRINTK 6 help 7 Selecting this option causes time stamps of the printk() 8 messages to be added to the output of the syslog() system 9 call and at the console. 10 11 The timestamp is always recorded internally, and exported 12 to /dev/kmsg. This flag just specifies if the timestamp should 13 be included, not that the timestamp is recorded. 14 15 The behavior is also controlled by the kernel command line 16 parameter printk.time=1. See Documentation/kernel-parameters.txt 17 18config MESSAGE_LOGLEVEL_DEFAULT 19 int "Default message log level (1-7)" 20 range 1 7 21 default "4" 22 help 23 Default log level for printk statements with no specified priority. 24 25 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks 26 that are auditing their logs closely may want to set it to a lower 27 priority. 28 29config BOOT_PRINTK_DELAY 30 bool "Delay each boot printk message by N milliseconds" 31 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY 32 help 33 This build option allows you to read kernel boot messages 34 by inserting a short delay after each one. The delay is 35 specified in milliseconds on the kernel command line, 36 using "boot_delay=N". 37 38 It is likely that you would also need to use "lpj=M" to preset 39 the "loops per jiffie" value. 40 See a previous boot log for the "lpj" value to use for your 41 system, and then set "lpj=M" before setting "boot_delay=N". 42 NOTE: Using this option may adversely affect SMP systems. 43 I.e., processors other than the first one may not boot up. 44 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect 45 what it believes to be lockup conditions. 46 47config DYNAMIC_DEBUG 48 bool "Enable dynamic printk() support" 49 default n 50 depends on PRINTK 51 depends on DEBUG_FS 52 help 53 54 Compiles debug level messages into the kernel, which would not 55 otherwise be available at runtime. These messages can then be 56 enabled/disabled based on various levels of scope - per source file, 57 function, module, format string, and line number. This mechanism 58 implicitly compiles in all pr_debug() and dev_dbg() calls, which 59 enlarges the kernel text size by about 2%. 60 61 If a source file is compiled with DEBUG flag set, any 62 pr_debug() calls in it are enabled by default, but can be 63 disabled at runtime as below. Note that DEBUG flag is 64 turned on by many CONFIG_*DEBUG* options. 65 66 Usage: 67 68 Dynamic debugging is controlled via the 'dynamic_debug/control' file, 69 which is contained in the 'debugfs' filesystem. Thus, the debugfs 70 filesystem must first be mounted before making use of this feature. 71 We refer the control file as: <debugfs>/dynamic_debug/control. This 72 file contains a list of the debug statements that can be enabled. The 73 format for each line of the file is: 74 75 filename:lineno [module]function flags format 76 77 filename : source file of the debug statement 78 lineno : line number of the debug statement 79 module : module that contains the debug statement 80 function : function that contains the debug statement 81 flags : '=p' means the line is turned 'on' for printing 82 format : the format used for the debug statement 83 84 From a live system: 85 86 nullarbor:~ # cat <debugfs>/dynamic_debug/control 87 # filename:lineno [module]function flags format 88 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012" 89 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012" 90 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012" 91 92 Example usage: 93 94 // enable the message at line 1603 of file svcsock.c 95 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' > 96 <debugfs>/dynamic_debug/control 97 98 // enable all the messages in file svcsock.c 99 nullarbor:~ # echo -n 'file svcsock.c +p' > 100 <debugfs>/dynamic_debug/control 101 102 // enable all the messages in the NFS server module 103 nullarbor:~ # echo -n 'module nfsd +p' > 104 <debugfs>/dynamic_debug/control 105 106 // enable all 12 messages in the function svc_process() 107 nullarbor:~ # echo -n 'func svc_process +p' > 108 <debugfs>/dynamic_debug/control 109 110 // disable all 12 messages in the function svc_process() 111 nullarbor:~ # echo -n 'func svc_process -p' > 112 <debugfs>/dynamic_debug/control 113 114 See Documentation/dynamic-debug-howto.txt for additional information. 115 116endmenu # "printk and dmesg options" 117 118menu "Compile-time checks and compiler options" 119 120config DEBUG_INFO 121 bool "Compile the kernel with debug info" 122 depends on DEBUG_KERNEL && !COMPILE_TEST 123 help 124 If you say Y here the resulting kernel image will include 125 debugging info resulting in a larger kernel image. 126 This adds debug symbols to the kernel and modules (gcc -g), and 127 is needed if you intend to use kernel crashdump or binary object 128 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 129 Say Y here only if you plan to debug the kernel. 130 131 If unsure, say N. 132 133config DEBUG_INFO_REDUCED 134 bool "Reduce debugging information" 135 depends on DEBUG_INFO 136 help 137 If you say Y here gcc is instructed to generate less debugging 138 information for structure types. This means that tools that 139 need full debugging information (like kgdb or systemtap) won't 140 be happy. But if you merely need debugging information to 141 resolve line numbers there is no loss. Advantage is that 142 build directory object sizes shrink dramatically over a full 143 DEBUG_INFO build and compile times are reduced too. 144 Only works with newer gcc versions. 145 146config DEBUG_INFO_SPLIT 147 bool "Produce split debuginfo in .dwo files" 148 depends on DEBUG_INFO 149 help 150 Generate debug info into separate .dwo files. This significantly 151 reduces the build directory size for builds with DEBUG_INFO, 152 because it stores the information only once on disk in .dwo 153 files instead of multiple times in object files and executables. 154 In addition the debug information is also compressed. 155 156 Requires recent gcc (4.7+) and recent gdb/binutils. 157 Any tool that packages or reads debug information would need 158 to know about the .dwo files and include them. 159 Incompatible with older versions of ccache. 160 161config DEBUG_INFO_DWARF4 162 bool "Generate dwarf4 debuginfo" 163 depends on DEBUG_INFO 164 help 165 Generate dwarf4 debug info. This requires recent versions 166 of gcc and gdb. It makes the debug information larger. 167 But it significantly improves the success of resolving 168 variables in gdb on optimized code. 169 170config ENABLE_WARN_DEPRECATED 171 bool "Enable __deprecated logic" 172 default y 173 help 174 Enable the __deprecated logic in the kernel build. 175 Disable this to suppress the "warning: 'foo' is deprecated 176 (declared at kernel/power/somefile.c:1234)" messages. 177 178config ENABLE_MUST_CHECK 179 bool "Enable __must_check logic" 180 default y 181 help 182 Enable the __must_check logic in the kernel build. Disable this to 183 suppress the "warning: ignoring return value of 'foo', declared with 184 attribute warn_unused_result" messages. 185 186config FRAME_WARN 187 int "Warn for stack frames larger than (needs gcc 4.4)" 188 range 0 8192 189 default 1024 if !64BIT 190 default 2048 if 64BIT 191 help 192 Tell gcc to warn at build time for stack frames larger than this. 193 Setting this too low will cause a lot of warnings. 194 Setting it to 0 disables the warning. 195 Requires gcc 4.4 196 197config STRIP_ASM_SYMS 198 bool "Strip assembler-generated symbols during link" 199 default n 200 help 201 Strip internal assembler-generated symbols during a link (symbols 202 that look like '.Lxxx') so they don't pollute the output of 203 get_wchan() and suchlike. 204 205config READABLE_ASM 206 bool "Generate readable assembler code" 207 depends on DEBUG_KERNEL 208 help 209 Disable some compiler optimizations that tend to generate human unreadable 210 assembler output. This may make the kernel slightly slower, but it helps 211 to keep kernel developers who have to stare a lot at assembler listings 212 sane. 213 214config UNUSED_SYMBOLS 215 bool "Enable unused/obsolete exported symbols" 216 default y if X86 217 help 218 Unused but exported symbols make the kernel needlessly bigger. For 219 that reason most of these unused exports will soon be removed. This 220 option is provided temporarily to provide a transition period in case 221 some external kernel module needs one of these symbols anyway. If you 222 encounter such a case in your module, consider if you are actually 223 using the right API. (rationale: since nobody in the kernel is using 224 this in a module, there is a pretty good chance it's actually the 225 wrong interface to use). If you really need the symbol, please send a 226 mail to the linux kernel mailing list mentioning the symbol and why 227 you really need it, and what the merge plan to the mainline kernel for 228 your module is. 229 230config DEBUG_FS 231 bool "Debug Filesystem" 232 help 233 debugfs is a virtual file system that kernel developers use to put 234 debugging files into. Enable this option to be able to read and 235 write to these files. 236 237 For detailed documentation on the debugfs API, see 238 Documentation/DocBook/filesystems. 239 240 If unsure, say N. 241 242config HEADERS_CHECK 243 bool "Run 'make headers_check' when building vmlinux" 244 depends on !UML 245 help 246 This option will extract the user-visible kernel headers whenever 247 building the kernel, and will run basic sanity checks on them to 248 ensure that exported files do not attempt to include files which 249 were not exported, etc. 250 251 If you're making modifications to header files which are 252 relevant for userspace, say 'Y', and check the headers 253 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in 254 your build tree), to make sure they're suitable. 255 256config DEBUG_SECTION_MISMATCH 257 bool "Enable full Section mismatch analysis" 258 help 259 The section mismatch analysis checks if there are illegal 260 references from one section to another section. 261 During linktime or runtime, some sections are dropped; 262 any use of code/data previously in these sections would 263 most likely result in an oops. 264 In the code, functions and variables are annotated with 265 __init,, etc. (see the full list in include/linux/init.h), 266 which results in the code/data being placed in specific sections. 267 The section mismatch analysis is always performed after a full 268 kernel build, and enabling this option causes the following 269 additional steps to occur: 270 - Add the option -fno-inline-functions-called-once to gcc commands. 271 When inlining a function annotated with __init in a non-init 272 function, we would lose the section information and thus 273 the analysis would not catch the illegal reference. 274 This option tells gcc to inline less (but it does result in 275 a larger kernel). 276 - Run the section mismatch analysis for each module/built-in.o file. 277 When we run the section mismatch analysis on vmlinux.o, we 278 lose valueble information about where the mismatch was 279 introduced. 280 Running the analysis for each module/built-in.o file 281 tells where the mismatch happens much closer to the 282 source. The drawback is that the same mismatch is 283 reported at least twice. 284 - Enable verbose reporting from modpost in order to help resolve 285 the section mismatches that are reported. 286 287# 288# Select this config option from the architecture Kconfig, if it 289# is preferred to always offer frame pointers as a config 290# option on the architecture (regardless of KERNEL_DEBUG): 291# 292config ARCH_WANT_FRAME_POINTERS 293 bool 294 help 295 296config FRAME_POINTER 297 bool "Compile the kernel with frame pointers" 298 depends on DEBUG_KERNEL && \ 299 (CRIS || M68K || FRV || UML || \ 300 AVR32 || SUPERH || BLACKFIN || MN10300 || METAG) || \ 301 ARCH_WANT_FRAME_POINTERS 302 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 303 help 304 If you say Y here the resulting kernel image will be slightly 305 larger and slower, but it gives very useful debugging information 306 in case of kernel bugs. (precise oopses/stacktraces/warnings) 307 308config DEBUG_FORCE_WEAK_PER_CPU 309 bool "Force weak per-cpu definitions" 310 depends on DEBUG_KERNEL 311 help 312 s390 and alpha require percpu variables in modules to be 313 defined weak to work around addressing range issue which 314 puts the following two restrictions on percpu variable 315 definitions. 316 317 1. percpu symbols must be unique whether static or not 318 2. percpu variables can't be defined inside a function 319 320 To ensure that generic code follows the above rules, this 321 option forces all percpu variables to be defined as weak. 322 323endmenu # "Compiler options" 324 325config MAGIC_SYSRQ 326 bool "Magic SysRq key" 327 depends on !UML 328 help 329 If you say Y here, you will have some control over the system even 330 if the system crashes for example during kernel debugging (e.g., you 331 will be able to flush the buffer cache to disk, reboot the system 332 immediately or dump some status information). This is accomplished 333 by pressing various keys while holding SysRq (Alt+PrintScreen). It 334 also works on a serial console (on PC hardware at least), if you 335 send a BREAK and then within 5 seconds a command keypress. The 336 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y 337 unless you really know what this hack does. 338 339config MAGIC_SYSRQ_DEFAULT_ENABLE 340 hex "Enable magic SysRq key functions by default" 341 depends on MAGIC_SYSRQ 342 default 0x1 343 help 344 Specifies which SysRq key functions are enabled by default. 345 This may be set to 1 or 0 to enable or disable them all, or 346 to a bitmask as described in Documentation/sysrq.txt. 347 348config DEBUG_KERNEL 349 bool "Kernel debugging" 350 help 351 Say Y here if you are developing drivers or trying to debug and 352 identify kernel problems. 353 354menu "Memory Debugging" 355 356source mm/Kconfig.debug 357 358config DEBUG_OBJECTS 359 bool "Debug object operations" 360 depends on DEBUG_KERNEL 361 help 362 If you say Y here, additional code will be inserted into the 363 kernel to track the life time of various objects and validate 364 the operations on those objects. 365 366config DEBUG_OBJECTS_SELFTEST 367 bool "Debug objects selftest" 368 depends on DEBUG_OBJECTS 369 help 370 This enables the selftest of the object debug code. 371 372config DEBUG_OBJECTS_FREE 373 bool "Debug objects in freed memory" 374 depends on DEBUG_OBJECTS 375 help 376 This enables checks whether a k/v free operation frees an area 377 which contains an object which has not been deactivated 378 properly. This can make kmalloc/kfree-intensive workloads 379 much slower. 380 381config DEBUG_OBJECTS_TIMERS 382 bool "Debug timer objects" 383 depends on DEBUG_OBJECTS 384 help 385 If you say Y here, additional code will be inserted into the 386 timer routines to track the life time of timer objects and 387 validate the timer operations. 388 389config DEBUG_OBJECTS_WORK 390 bool "Debug work objects" 391 depends on DEBUG_OBJECTS 392 help 393 If you say Y here, additional code will be inserted into the 394 work queue routines to track the life time of work objects and 395 validate the work operations. 396 397config DEBUG_OBJECTS_RCU_HEAD 398 bool "Debug RCU callbacks objects" 399 depends on DEBUG_OBJECTS 400 help 401 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 402 403config DEBUG_OBJECTS_PERCPU_COUNTER 404 bool "Debug percpu counter objects" 405 depends on DEBUG_OBJECTS 406 help 407 If you say Y here, additional code will be inserted into the 408 percpu counter routines to track the life time of percpu counter 409 objects and validate the percpu counter operations. 410 411config DEBUG_OBJECTS_ENABLE_DEFAULT 412 int "debug_objects bootup default value (0-1)" 413 range 0 1 414 default "1" 415 depends on DEBUG_OBJECTS 416 help 417 Debug objects boot parameter default value 418 419config DEBUG_SLAB 420 bool "Debug slab memory allocations" 421 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK 422 help 423 Say Y here to have the kernel do limited verification on memory 424 allocation as well as poisoning memory on free to catch use of freed 425 memory. This can make kmalloc/kfree-intensive workloads much slower. 426 427config DEBUG_SLAB_LEAK 428 bool "Memory leak debugging" 429 depends on DEBUG_SLAB 430 431config SLUB_DEBUG_ON 432 bool "SLUB debugging on by default" 433 depends on SLUB && SLUB_DEBUG && !KMEMCHECK 434 default n 435 help 436 Boot with debugging on by default. SLUB boots by default with 437 the runtime debug capabilities switched off. Enabling this is 438 equivalent to specifying the "slub_debug" parameter on boot. 439 There is no support for more fine grained debug control like 440 possible with slub_debug=xxx. SLUB debugging may be switched 441 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying 442 "slub_debug=-". 443 444config SLUB_STATS 445 default n 446 bool "Enable SLUB performance statistics" 447 depends on SLUB && SYSFS 448 help 449 SLUB statistics are useful to debug SLUBs allocation behavior in 450 order find ways to optimize the allocator. This should never be 451 enabled for production use since keeping statistics slows down 452 the allocator by a few percentage points. The slabinfo command 453 supports the determination of the most active slabs to figure 454 out which slabs are relevant to a particular load. 455 Try running: slabinfo -DA 456 457config HAVE_DEBUG_KMEMLEAK 458 bool 459 460config DEBUG_KMEMLEAK 461 bool "Kernel memory leak detector" 462 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK 463 select DEBUG_FS 464 select STACKTRACE if STACKTRACE_SUPPORT 465 select KALLSYMS 466 select CRC32 467 help 468 Say Y here if you want to enable the memory leak 469 detector. The memory allocation/freeing is traced in a way 470 similar to the Boehm's conservative garbage collector, the 471 difference being that the orphan objects are not freed but 472 only shown in /sys/kernel/debug/kmemleak. Enabling this 473 feature will introduce an overhead to memory 474 allocations. See Documentation/kmemleak.txt for more 475 details. 476 477 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances 478 of finding leaks due to the slab objects poisoning. 479 480 In order to access the kmemleak file, debugfs needs to be 481 mounted (usually at /sys/kernel/debug). 482 483config DEBUG_KMEMLEAK_EARLY_LOG_SIZE 484 int "Maximum kmemleak early log entries" 485 depends on DEBUG_KMEMLEAK 486 range 200 40000 487 default 400 488 help 489 Kmemleak must track all the memory allocations to avoid 490 reporting false positives. Since memory may be allocated or 491 freed before kmemleak is initialised, an early log buffer is 492 used to store these actions. If kmemleak reports "early log 493 buffer exceeded", please increase this value. 494 495config DEBUG_KMEMLEAK_TEST 496 tristate "Simple test for the kernel memory leak detector" 497 depends on DEBUG_KMEMLEAK && m 498 help 499 This option enables a module that explicitly leaks memory. 500 501 If unsure, say N. 502 503config DEBUG_KMEMLEAK_DEFAULT_OFF 504 bool "Default kmemleak to off" 505 depends on DEBUG_KMEMLEAK 506 help 507 Say Y here to disable kmemleak by default. It can then be enabled 508 on the command line via kmemleak=on. 509 510config DEBUG_STACK_USAGE 511 bool "Stack utilization instrumentation" 512 depends on DEBUG_KERNEL && !IA64 && !PARISC && !METAG 513 help 514 Enables the display of the minimum amount of free stack which each 515 task has ever had available in the sysrq-T and sysrq-P debug output. 516 517 This option will slow down process creation somewhat. 518 519config DEBUG_VM 520 bool "Debug VM" 521 depends on DEBUG_KERNEL 522 help 523 Enable this to turn on extended checks in the virtual-memory system 524 that may impact performance. 525 526 If unsure, say N. 527 528config DEBUG_VM_VMACACHE 529 bool "Debug VMA caching" 530 depends on DEBUG_VM 531 help 532 Enable this to turn on VMA caching debug information. Doing so 533 can cause significant overhead, so only enable it in non-production 534 environments. 535 536 If unsure, say N. 537 538config DEBUG_VM_RB 539 bool "Debug VM red-black trees" 540 depends on DEBUG_VM 541 help 542 Enable VM red-black tree debugging information and extra validations. 543 544 If unsure, say N. 545 546config DEBUG_VIRTUAL 547 bool "Debug VM translations" 548 depends on DEBUG_KERNEL && X86 549 help 550 Enable some costly sanity checks in virtual to page code. This can 551 catch mistakes with virt_to_page() and friends. 552 553 If unsure, say N. 554 555config DEBUG_NOMMU_REGIONS 556 bool "Debug the global anon/private NOMMU mapping region tree" 557 depends on DEBUG_KERNEL && !MMU 558 help 559 This option causes the global tree of anonymous and private mapping 560 regions to be regularly checked for invalid topology. 561 562config DEBUG_MEMORY_INIT 563 bool "Debug memory initialisation" if EXPERT 564 default !EXPERT 565 help 566 Enable this for additional checks during memory initialisation. 567 The sanity checks verify aspects of the VM such as the memory model 568 and other information provided by the architecture. Verbose 569 information will be printed at KERN_DEBUG loglevel depending 570 on the mminit_loglevel= command-line option. 571 572 If unsure, say Y 573 574config MEMORY_NOTIFIER_ERROR_INJECT 575 tristate "Memory hotplug notifier error injection module" 576 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION 577 help 578 This option provides the ability to inject artificial errors to 579 memory hotplug notifier chain callbacks. It is controlled through 580 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 581 582 If the notifier call chain should be failed with some events 583 notified, write the error code to "actions/<notifier event>/error". 584 585 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 586 587 # cd /sys/kernel/debug/notifier-error-inject/memory 588 # echo -12 > actions/MEM_GOING_OFFLINE/error 589 # echo offline > /sys/devices/system/memory/memoryXXX/state 590 bash: echo: write error: Cannot allocate memory 591 592 To compile this code as a module, choose M here: the module will 593 be called memory-notifier-error-inject. 594 595 If unsure, say N. 596 597config DEBUG_PER_CPU_MAPS 598 bool "Debug access to per_cpu maps" 599 depends on DEBUG_KERNEL 600 depends on SMP 601 help 602 Say Y to verify that the per_cpu map being accessed has 603 been set up. This adds a fair amount of code to kernel memory 604 and decreases performance. 605 606 Say N if unsure. 607 608config DEBUG_HIGHMEM 609 bool "Highmem debugging" 610 depends on DEBUG_KERNEL && HIGHMEM 611 help 612 This option enables additional error checking for high memory 613 systems. Disable for production systems. 614 615config HAVE_DEBUG_STACKOVERFLOW 616 bool 617 618config DEBUG_STACKOVERFLOW 619 bool "Check for stack overflows" 620 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 621 ---help--- 622 Say Y here if you want to check for overflows of kernel, IRQ 623 and exception stacks (if your archicture uses them). This 624 option will show detailed messages if free stack space drops 625 below a certain limit. 626 627 These kinds of bugs usually occur when call-chains in the 628 kernel get too deep, especially when interrupts are 629 involved. 630 631 Use this in cases where you see apparently random memory 632 corruption, especially if it appears in 'struct thread_info' 633 634 If in doubt, say "N". 635 636source "lib/Kconfig.kmemcheck" 637 638endmenu # "Memory Debugging" 639 640config DEBUG_SHIRQ 641 bool "Debug shared IRQ handlers" 642 depends on DEBUG_KERNEL 643 help 644 Enable this to generate a spurious interrupt as soon as a shared 645 interrupt handler is registered, and just before one is deregistered. 646 Drivers ought to be able to handle interrupts coming in at those 647 points; some don't and need to be caught. 648 649menu "Debug Lockups and Hangs" 650 651config LOCKUP_DETECTOR 652 bool "Detect Hard and Soft Lockups" 653 depends on DEBUG_KERNEL && !S390 654 help 655 Say Y here to enable the kernel to act as a watchdog to detect 656 hard and soft lockups. 657 658 Softlockups are bugs that cause the kernel to loop in kernel 659 mode for more than 20 seconds, without giving other tasks a 660 chance to run. The current stack trace is displayed upon 661 detection and the system will stay locked up. 662 663 Hardlockups are bugs that cause the CPU to loop in kernel mode 664 for more than 10 seconds, without letting other interrupts have a 665 chance to run. The current stack trace is displayed upon detection 666 and the system will stay locked up. 667 668 The overhead should be minimal. A periodic hrtimer runs to 669 generate interrupts and kick the watchdog task every 4 seconds. 670 An NMI is generated every 10 seconds or so to check for hardlockups. 671 672 The frequency of hrtimer and NMI events and the soft and hard lockup 673 thresholds can be controlled through the sysctl watchdog_thresh. 674 675config HARDLOCKUP_DETECTOR 676 def_bool y 677 depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG 678 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI 679 680config BOOTPARAM_HARDLOCKUP_PANIC 681 bool "Panic (Reboot) On Hard Lockups" 682 depends on HARDLOCKUP_DETECTOR 683 help 684 Say Y here to enable the kernel to panic on "hard lockups", 685 which are bugs that cause the kernel to loop in kernel 686 mode with interrupts disabled for more than 10 seconds (configurable 687 using the watchdog_thresh sysctl). 688 689 Say N if unsure. 690 691config BOOTPARAM_HARDLOCKUP_PANIC_VALUE 692 int 693 depends on HARDLOCKUP_DETECTOR 694 range 0 1 695 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC 696 default 1 if BOOTPARAM_HARDLOCKUP_PANIC 697 698config BOOTPARAM_SOFTLOCKUP_PANIC 699 bool "Panic (Reboot) On Soft Lockups" 700 depends on LOCKUP_DETECTOR 701 help 702 Say Y here to enable the kernel to panic on "soft lockups", 703 which are bugs that cause the kernel to loop in kernel 704 mode for more than 20 seconds (configurable using the watchdog_thresh 705 sysctl), without giving other tasks a chance to run. 706 707 The panic can be used in combination with panic_timeout, 708 to cause the system to reboot automatically after a 709 lockup has been detected. This feature is useful for 710 high-availability systems that have uptime guarantees and 711 where a lockup must be resolved ASAP. 712 713 Say N if unsure. 714 715config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE 716 int 717 depends on LOCKUP_DETECTOR 718 range 0 1 719 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC 720 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC 721 722config DETECT_HUNG_TASK 723 bool "Detect Hung Tasks" 724 depends on DEBUG_KERNEL 725 default LOCKUP_DETECTOR 726 help 727 Say Y here to enable the kernel to detect "hung tasks", 728 which are bugs that cause the task to be stuck in 729 uninterruptible "D" state indefinitiley. 730 731 When a hung task is detected, the kernel will print the 732 current stack trace (which you should report), but the 733 task will stay in uninterruptible state. If lockdep is 734 enabled then all held locks will also be reported. This 735 feature has negligible overhead. 736 737config DEFAULT_HUNG_TASK_TIMEOUT 738 int "Default timeout for hung task detection (in seconds)" 739 depends on DETECT_HUNG_TASK 740 default 120 741 help 742 This option controls the default timeout (in seconds) used 743 to determine when a task has become non-responsive and should 744 be considered hung. 745 746 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 747 sysctl or by writing a value to 748 /proc/sys/kernel/hung_task_timeout_secs. 749 750 A timeout of 0 disables the check. The default is two minutes. 751 Keeping the default should be fine in most cases. 752 753config BOOTPARAM_HUNG_TASK_PANIC 754 bool "Panic (Reboot) On Hung Tasks" 755 depends on DETECT_HUNG_TASK 756 help 757 Say Y here to enable the kernel to panic on "hung tasks", 758 which are bugs that cause the kernel to leave a task stuck 759 in uninterruptible "D" state. 760 761 The panic can be used in combination with panic_timeout, 762 to cause the system to reboot automatically after a 763 hung task has been detected. This feature is useful for 764 high-availability systems that have uptime guarantees and 765 where a hung tasks must be resolved ASAP. 766 767 Say N if unsure. 768 769config BOOTPARAM_HUNG_TASK_PANIC_VALUE 770 int 771 depends on DETECT_HUNG_TASK 772 range 0 1 773 default 0 if !BOOTPARAM_HUNG_TASK_PANIC 774 default 1 if BOOTPARAM_HUNG_TASK_PANIC 775 776endmenu # "Debug lockups and hangs" 777 778config PANIC_ON_OOPS 779 bool "Panic on Oops" 780 help 781 Say Y here to enable the kernel to panic when it oopses. This 782 has the same effect as setting oops=panic on the kernel command 783 line. 784 785 This feature is useful to ensure that the kernel does not do 786 anything erroneous after an oops which could result in data 787 corruption or other issues. 788 789 Say N if unsure. 790 791config PANIC_ON_OOPS_VALUE 792 int 793 range 0 1 794 default 0 if !PANIC_ON_OOPS 795 default 1 if PANIC_ON_OOPS 796 797config PANIC_TIMEOUT 798 int "panic timeout" 799 default 0 800 help 801 Set the timeout value (in seconds) until a reboot occurs when the 802 the kernel panics. If n = 0, then we wait forever. A timeout 803 value n > 0 will wait n seconds before rebooting, while a timeout 804 value n < 0 will reboot immediately. 805 806config SCHED_DEBUG 807 bool "Collect scheduler debugging info" 808 depends on DEBUG_KERNEL && PROC_FS 809 default y 810 help 811 If you say Y here, the /proc/sched_debug file will be provided 812 that can help debug the scheduler. The runtime overhead of this 813 option is minimal. 814 815config SCHEDSTATS 816 bool "Collect scheduler statistics" 817 depends on DEBUG_KERNEL && PROC_FS 818 help 819 If you say Y here, additional code will be inserted into the 820 scheduler and related routines to collect statistics about 821 scheduler behavior and provide them in /proc/schedstat. These 822 stats may be useful for both tuning and debugging the scheduler 823 If you aren't debugging the scheduler or trying to tune a specific 824 application, you can say N to avoid the very slight overhead 825 this adds. 826 827config SCHED_STACK_END_CHECK 828 bool "Detect stack corruption on calls to schedule()" 829 depends on DEBUG_KERNEL 830 default n 831 help 832 This option checks for a stack overrun on calls to schedule(). 833 If the stack end location is found to be over written always panic as 834 the content of the corrupted region can no longer be trusted. 835 This is to ensure no erroneous behaviour occurs which could result in 836 data corruption or a sporadic crash at a later stage once the region 837 is examined. The runtime overhead introduced is minimal. 838 839config TIMER_STATS 840 bool "Collect kernel timers statistics" 841 depends on DEBUG_KERNEL && PROC_FS 842 help 843 If you say Y here, additional code will be inserted into the 844 timer routines to collect statistics about kernel timers being 845 reprogrammed. The statistics can be read from /proc/timer_stats. 846 The statistics collection is started by writing 1 to /proc/timer_stats, 847 writing 0 stops it. This feature is useful to collect information 848 about timer usage patterns in kernel and userspace. This feature 849 is lightweight if enabled in the kernel config but not activated 850 (it defaults to deactivated on bootup and will only be activated 851 if some application like powertop activates it explicitly). 852 853config DEBUG_PREEMPT 854 bool "Debug preemptible kernel" 855 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT 856 default y 857 help 858 If you say Y here then the kernel will use a debug variant of the 859 commonly used smp_processor_id() function and will print warnings 860 if kernel code uses it in a preemption-unsafe way. Also, the kernel 861 will detect preemption count underflows. 862 863menu "Lock Debugging (spinlocks, mutexes, etc...)" 864 865config DEBUG_RT_MUTEXES 866 bool "RT Mutex debugging, deadlock detection" 867 depends on DEBUG_KERNEL && RT_MUTEXES 868 help 869 This allows rt mutex semantics violations and rt mutex related 870 deadlocks (lockups) to be detected and reported automatically. 871 872config RT_MUTEX_TESTER 873 bool "Built-in scriptable tester for rt-mutexes" 874 depends on DEBUG_KERNEL && RT_MUTEXES && BROKEN 875 help 876 This option enables a rt-mutex tester. 877 878config DEBUG_SPINLOCK 879 bool "Spinlock and rw-lock debugging: basic checks" 880 depends on DEBUG_KERNEL 881 select UNINLINE_SPIN_UNLOCK 882 help 883 Say Y here and build SMP to catch missing spinlock initialization 884 and certain other kinds of spinlock errors commonly made. This is 885 best used in conjunction with the NMI watchdog so that spinlock 886 deadlocks are also debuggable. 887 888config DEBUG_MUTEXES 889 bool "Mutex debugging: basic checks" 890 depends on DEBUG_KERNEL 891 help 892 This feature allows mutex semantics violations to be detected and 893 reported. 894 895config DEBUG_WW_MUTEX_SLOWPATH 896 bool "Wait/wound mutex debugging: Slowpath testing" 897 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 898 select DEBUG_LOCK_ALLOC 899 select DEBUG_SPINLOCK 900 select DEBUG_MUTEXES 901 help 902 This feature enables slowpath testing for w/w mutex users by 903 injecting additional -EDEADLK wound/backoff cases. Together with 904 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 905 will test all possible w/w mutex interface abuse with the 906 exception of simply not acquiring all the required locks. 907 Note that this feature can introduce significant overhead, so 908 it really should not be enabled in a production or distro kernel, 909 even a debug kernel. If you are a driver writer, enable it. If 910 you are a distro, do not. 911 912config DEBUG_LOCK_ALLOC 913 bool "Lock debugging: detect incorrect freeing of live locks" 914 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 915 select DEBUG_SPINLOCK 916 select DEBUG_MUTEXES 917 select LOCKDEP 918 help 919 This feature will check whether any held lock (spinlock, rwlock, 920 mutex or rwsem) is incorrectly freed by the kernel, via any of the 921 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 922 vfree(), etc.), whether a live lock is incorrectly reinitialized via 923 spin_lock_init()/mutex_init()/etc., or whether there is any lock 924 held during task exit. 925 926config PROVE_LOCKING 927 bool "Lock debugging: prove locking correctness" 928 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 929 select LOCKDEP 930 select DEBUG_SPINLOCK 931 select DEBUG_MUTEXES 932 select DEBUG_LOCK_ALLOC 933 select TRACE_IRQFLAGS 934 default n 935 help 936 This feature enables the kernel to prove that all locking 937 that occurs in the kernel runtime is mathematically 938 correct: that under no circumstance could an arbitrary (and 939 not yet triggered) combination of observed locking 940 sequences (on an arbitrary number of CPUs, running an 941 arbitrary number of tasks and interrupt contexts) cause a 942 deadlock. 943 944 In short, this feature enables the kernel to report locking 945 related deadlocks before they actually occur. 946 947 The proof does not depend on how hard and complex a 948 deadlock scenario would be to trigger: how many 949 participant CPUs, tasks and irq-contexts would be needed 950 for it to trigger. The proof also does not depend on 951 timing: if a race and a resulting deadlock is possible 952 theoretically (no matter how unlikely the race scenario 953 is), it will be proven so and will immediately be 954 reported by the kernel (once the event is observed that 955 makes the deadlock theoretically possible). 956 957 If a deadlock is impossible (i.e. the locking rules, as 958 observed by the kernel, are mathematically correct), the 959 kernel reports nothing. 960 961 NOTE: this feature can also be enabled for rwlocks, mutexes 962 and rwsems - in which case all dependencies between these 963 different locking variants are observed and mapped too, and 964 the proof of observed correctness is also maintained for an 965 arbitrary combination of these separate locking variants. 966 967 For more details, see Documentation/locking/lockdep-design.txt. 968 969config LOCKDEP 970 bool 971 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 972 select STACKTRACE 973 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC && !SCORE 974 select KALLSYMS 975 select KALLSYMS_ALL 976 977config LOCK_STAT 978 bool "Lock usage statistics" 979 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 980 select LOCKDEP 981 select DEBUG_SPINLOCK 982 select DEBUG_MUTEXES 983 select DEBUG_LOCK_ALLOC 984 default n 985 help 986 This feature enables tracking lock contention points 987 988 For more details, see Documentation/locking/lockstat.txt 989 990 This also enables lock events required by "perf lock", 991 subcommand of perf. 992 If you want to use "perf lock", you also need to turn on 993 CONFIG_EVENT_TRACING. 994 995 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 996 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 997 998config DEBUG_LOCKDEP 999 bool "Lock dependency engine debugging" 1000 depends on DEBUG_KERNEL && LOCKDEP 1001 help 1002 If you say Y here, the lock dependency engine will do 1003 additional runtime checks to debug itself, at the price 1004 of more runtime overhead. 1005 1006config DEBUG_ATOMIC_SLEEP 1007 bool "Sleep inside atomic section checking" 1008 select PREEMPT_COUNT 1009 depends on DEBUG_KERNEL 1010 help 1011 If you say Y here, various routines which may sleep will become very 1012 noisy if they are called inside atomic sections: when a spinlock is 1013 held, inside an rcu read side critical section, inside preempt disabled 1014 sections, inside an interrupt, etc... 1015 1016config DEBUG_LOCKING_API_SELFTESTS 1017 bool "Locking API boot-time self-tests" 1018 depends on DEBUG_KERNEL 1019 help 1020 Say Y here if you want the kernel to run a short self-test during 1021 bootup. The self-test checks whether common types of locking bugs 1022 are detected by debugging mechanisms or not. (if you disable 1023 lock debugging then those bugs wont be detected of course.) 1024 The following locking APIs are covered: spinlocks, rwlocks, 1025 mutexes and rwsems. 1026 1027config LOCK_TORTURE_TEST 1028 tristate "torture tests for locking" 1029 depends on DEBUG_KERNEL 1030 select TORTURE_TEST 1031 default n 1032 help 1033 This option provides a kernel module that runs torture tests 1034 on kernel locking primitives. The kernel module may be built 1035 after the fact on the running kernel to be tested, if desired. 1036 1037 Say Y here if you want kernel locking-primitive torture tests 1038 to be built into the kernel. 1039 Say M if you want these torture tests to build as a module. 1040 Say N if you are unsure. 1041 1042endmenu # lock debugging 1043 1044config TRACE_IRQFLAGS 1045 bool 1046 help 1047 Enables hooks to interrupt enabling and disabling for 1048 either tracing or lock debugging. 1049 1050config STACKTRACE 1051 bool "Stack backtrace support" 1052 depends on STACKTRACE_SUPPORT 1053 help 1054 This option causes the kernel to create a /proc/pid/stack for 1055 every process, showing its current stack trace. 1056 It is also used by various kernel debugging features that require 1057 stack trace generation. 1058 1059config DEBUG_KOBJECT 1060 bool "kobject debugging" 1061 depends on DEBUG_KERNEL 1062 help 1063 If you say Y here, some extra kobject debugging messages will be sent 1064 to the syslog. 1065 1066config DEBUG_KOBJECT_RELEASE 1067 bool "kobject release debugging" 1068 depends on DEBUG_OBJECTS_TIMERS 1069 help 1070 kobjects are reference counted objects. This means that their 1071 last reference count put is not predictable, and the kobject can 1072 live on past the point at which a driver decides to drop it's 1073 initial reference to the kobject gained on allocation. An 1074 example of this would be a struct device which has just been 1075 unregistered. 1076 1077 However, some buggy drivers assume that after such an operation, 1078 the memory backing the kobject can be immediately freed. This 1079 goes completely against the principles of a refcounted object. 1080 1081 If you say Y here, the kernel will delay the release of kobjects 1082 on the last reference count to improve the visibility of this 1083 kind of kobject release bug. 1084 1085config HAVE_DEBUG_BUGVERBOSE 1086 bool 1087 1088config DEBUG_BUGVERBOSE 1089 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT 1090 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE) 1091 default y 1092 help 1093 Say Y here to make BUG() panics output the file name and line number 1094 of the BUG call as well as the EIP and oops trace. This aids 1095 debugging but costs about 70-100K of memory. 1096 1097config DEBUG_LIST 1098 bool "Debug linked list manipulation" 1099 depends on DEBUG_KERNEL 1100 help 1101 Enable this to turn on extended checks in the linked-list 1102 walking routines. 1103 1104 If unsure, say N. 1105 1106config DEBUG_PI_LIST 1107 bool "Debug priority linked list manipulation" 1108 depends on DEBUG_KERNEL 1109 help 1110 Enable this to turn on extended checks in the priority-ordered 1111 linked-list (plist) walking routines. This checks the entire 1112 list multiple times during each manipulation. 1113 1114 If unsure, say N. 1115 1116config DEBUG_SG 1117 bool "Debug SG table operations" 1118 depends on DEBUG_KERNEL 1119 help 1120 Enable this to turn on checks on scatter-gather tables. This can 1121 help find problems with drivers that do not properly initialize 1122 their sg tables. 1123 1124 If unsure, say N. 1125 1126config DEBUG_NOTIFIERS 1127 bool "Debug notifier call chains" 1128 depends on DEBUG_KERNEL 1129 help 1130 Enable this to turn on sanity checking for notifier call chains. 1131 This is most useful for kernel developers to make sure that 1132 modules properly unregister themselves from notifier chains. 1133 This is a relatively cheap check but if you care about maximum 1134 performance, say N. 1135 1136config DEBUG_CREDENTIALS 1137 bool "Debug credential management" 1138 depends on DEBUG_KERNEL 1139 help 1140 Enable this to turn on some debug checking for credential 1141 management. The additional code keeps track of the number of 1142 pointers from task_structs to any given cred struct, and checks to 1143 see that this number never exceeds the usage count of the cred 1144 struct. 1145 1146 Furthermore, if SELinux is enabled, this also checks that the 1147 security pointer in the cred struct is never seen to be invalid. 1148 1149 If unsure, say N. 1150 1151menu "RCU Debugging" 1152 1153config PROVE_RCU 1154 bool "RCU debugging: prove RCU correctness" 1155 depends on PROVE_LOCKING 1156 default n 1157 help 1158 This feature enables lockdep extensions that check for correct 1159 use of RCU APIs. This is currently under development. Say Y 1160 if you want to debug RCU usage or help work on the PROVE_RCU 1161 feature. 1162 1163 Say N if you are unsure. 1164 1165config PROVE_RCU_REPEATEDLY 1166 bool "RCU debugging: don't disable PROVE_RCU on first splat" 1167 depends on PROVE_RCU 1168 default n 1169 help 1170 By itself, PROVE_RCU will disable checking upon issuing the 1171 first warning (or "splat"). This feature prevents such 1172 disabling, allowing multiple RCU-lockdep warnings to be printed 1173 on a single reboot. 1174 1175 Say Y to allow multiple RCU-lockdep warnings per boot. 1176 1177 Say N if you are unsure. 1178 1179config SPARSE_RCU_POINTER 1180 bool "RCU debugging: sparse-based checks for pointer usage" 1181 default n 1182 help 1183 This feature enables the __rcu sparse annotation for 1184 RCU-protected pointers. This annotation will cause sparse 1185 to flag any non-RCU used of annotated pointers. This can be 1186 helpful when debugging RCU usage. Please note that this feature 1187 is not intended to enforce code cleanliness; it is instead merely 1188 a debugging aid. 1189 1190 Say Y to make sparse flag questionable use of RCU-protected pointers 1191 1192 Say N if you are unsure. 1193 1194config TORTURE_TEST 1195 tristate 1196 default n 1197 1198config RCU_TORTURE_TEST 1199 tristate "torture tests for RCU" 1200 depends on DEBUG_KERNEL 1201 select TORTURE_TEST 1202 default n 1203 help 1204 This option provides a kernel module that runs torture tests 1205 on the RCU infrastructure. The kernel module may be built 1206 after the fact on the running kernel to be tested, if desired. 1207 1208 Say Y here if you want RCU torture tests to be built into 1209 the kernel. 1210 Say M if you want the RCU torture tests to build as a module. 1211 Say N if you are unsure. 1212 1213config RCU_TORTURE_TEST_RUNNABLE 1214 bool "torture tests for RCU runnable by default" 1215 depends on RCU_TORTURE_TEST = y 1216 default n 1217 help 1218 This option provides a way to build the RCU torture tests 1219 directly into the kernel without them starting up at boot 1220 time. You can use /proc/sys/kernel/rcutorture_runnable 1221 to manually override this setting. This /proc file is 1222 available only when the RCU torture tests have been built 1223 into the kernel. 1224 1225 Say Y here if you want the RCU torture tests to start during 1226 boot (you probably don't). 1227 Say N here if you want the RCU torture tests to start only 1228 after being manually enabled via /proc. 1229 1230config RCU_CPU_STALL_TIMEOUT 1231 int "RCU CPU stall timeout in seconds" 1232 depends on RCU_STALL_COMMON 1233 range 3 300 1234 default 21 1235 help 1236 If a given RCU grace period extends more than the specified 1237 number of seconds, a CPU stall warning is printed. If the 1238 RCU grace period persists, additional CPU stall warnings are 1239 printed at more widely spaced intervals. 1240 1241config RCU_CPU_STALL_VERBOSE 1242 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR" 1243 depends on TREE_PREEMPT_RCU 1244 default y 1245 help 1246 This option causes RCU to printk detailed per-task information 1247 for any tasks that are stalling the current RCU grace period. 1248 1249 Say N if you are unsure. 1250 1251 Say Y if you want to enable such checks. 1252 1253config RCU_CPU_STALL_INFO 1254 bool "Print additional diagnostics on RCU CPU stall" 1255 depends on (TREE_RCU || TREE_PREEMPT_RCU) && DEBUG_KERNEL 1256 default n 1257 help 1258 For each stalled CPU that is aware of the current RCU grace 1259 period, print out additional per-CPU diagnostic information 1260 regarding scheduling-clock ticks, idle state, and, 1261 for RCU_FAST_NO_HZ kernels, idle-entry state. 1262 1263 Say N if you are unsure. 1264 1265 Say Y if you want to enable such diagnostics. 1266 1267config RCU_TRACE 1268 bool "Enable tracing for RCU" 1269 depends on DEBUG_KERNEL 1270 select TRACE_CLOCK 1271 help 1272 This option provides tracing in RCU which presents stats 1273 in debugfs for debugging RCU implementation. 1274 1275 Say Y here if you want to enable RCU tracing 1276 Say N if you are unsure. 1277 1278endmenu # "RCU Debugging" 1279 1280config DEBUG_BLOCK_EXT_DEVT 1281 bool "Force extended block device numbers and spread them" 1282 depends on DEBUG_KERNEL 1283 depends on BLOCK 1284 default n 1285 help 1286 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON 1287 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT 1288 YOU ARE DOING. Distros, please enable this and fix whatever 1289 is broken. 1290 1291 Conventionally, block device numbers are allocated from 1292 predetermined contiguous area. However, extended block area 1293 may introduce non-contiguous block device numbers. This 1294 option forces most block device numbers to be allocated from 1295 the extended space and spreads them to discover kernel or 1296 userland code paths which assume predetermined contiguous 1297 device number allocation. 1298 1299 Note that turning on this debug option shuffles all the 1300 device numbers for all IDE and SCSI devices including libata 1301 ones, so root partition specified using device number 1302 directly (via rdev or root=MAJ:MIN) won't work anymore. 1303 Textual device names (root=/dev/sdXn) will continue to work. 1304 1305 Say N if you are unsure. 1306 1307config NOTIFIER_ERROR_INJECTION 1308 tristate "Notifier error injection" 1309 depends on DEBUG_KERNEL 1310 select DEBUG_FS 1311 help 1312 This option provides the ability to inject artificial errors to 1313 specified notifier chain callbacks. It is useful to test the error 1314 handling of notifier call chain failures. 1315 1316 Say N if unsure. 1317 1318config CPU_NOTIFIER_ERROR_INJECT 1319 tristate "CPU notifier error injection module" 1320 depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION 1321 help 1322 This option provides a kernel module that can be used to test 1323 the error handling of the cpu notifiers by injecting artificial 1324 errors to CPU notifier chain callbacks. It is controlled through 1325 debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu 1326 1327 If the notifier call chain should be failed with some events 1328 notified, write the error code to "actions/<notifier event>/error". 1329 1330 Example: Inject CPU offline error (-1 == -EPERM) 1331 1332 # cd /sys/kernel/debug/notifier-error-inject/cpu 1333 # echo -1 > actions/CPU_DOWN_PREPARE/error 1334 # echo 0 > /sys/devices/system/cpu/cpu1/online 1335 bash: echo: write error: Operation not permitted 1336 1337 To compile this code as a module, choose M here: the module will 1338 be called cpu-notifier-error-inject. 1339 1340 If unsure, say N. 1341 1342config PM_NOTIFIER_ERROR_INJECT 1343 tristate "PM notifier error injection module" 1344 depends on PM && NOTIFIER_ERROR_INJECTION 1345 default m if PM_DEBUG 1346 help 1347 This option provides the ability to inject artificial errors to 1348 PM notifier chain callbacks. It is controlled through debugfs 1349 interface /sys/kernel/debug/notifier-error-inject/pm 1350 1351 If the notifier call chain should be failed with some events 1352 notified, write the error code to "actions/<notifier event>/error". 1353 1354 Example: Inject PM suspend error (-12 = -ENOMEM) 1355 1356 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1357 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1358 # echo mem > /sys/power/state 1359 bash: echo: write error: Cannot allocate memory 1360 1361 To compile this code as a module, choose M here: the module will 1362 be called pm-notifier-error-inject. 1363 1364 If unsure, say N. 1365 1366config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1367 tristate "OF reconfig notifier error injection module" 1368 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1369 help 1370 This option provides the ability to inject artificial errors to 1371 OF reconfig notifier chain callbacks. It is controlled 1372 through debugfs interface under 1373 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1374 1375 If the notifier call chain should be failed with some events 1376 notified, write the error code to "actions/<notifier event>/error". 1377 1378 To compile this code as a module, choose M here: the module will 1379 be called of-reconfig-notifier-error-inject. 1380 1381 If unsure, say N. 1382 1383config FAULT_INJECTION 1384 bool "Fault-injection framework" 1385 depends on DEBUG_KERNEL 1386 help 1387 Provide fault-injection framework. 1388 For more details, see Documentation/fault-injection/. 1389 1390config FAILSLAB 1391 bool "Fault-injection capability for kmalloc" 1392 depends on FAULT_INJECTION 1393 depends on SLAB || SLUB 1394 help 1395 Provide fault-injection capability for kmalloc. 1396 1397config FAIL_PAGE_ALLOC 1398 bool "Fault-injection capabilitiy for alloc_pages()" 1399 depends on FAULT_INJECTION 1400 help 1401 Provide fault-injection capability for alloc_pages(). 1402 1403config FAIL_MAKE_REQUEST 1404 bool "Fault-injection capability for disk IO" 1405 depends on FAULT_INJECTION && BLOCK 1406 help 1407 Provide fault-injection capability for disk IO. 1408 1409config FAIL_IO_TIMEOUT 1410 bool "Fault-injection capability for faking disk interrupts" 1411 depends on FAULT_INJECTION && BLOCK 1412 help 1413 Provide fault-injection capability on end IO handling. This 1414 will make the block layer "forget" an interrupt as configured, 1415 thus exercising the error handling. 1416 1417 Only works with drivers that use the generic timeout handling, 1418 for others it wont do anything. 1419 1420config FAIL_MMC_REQUEST 1421 bool "Fault-injection capability for MMC IO" 1422 select DEBUG_FS 1423 depends on FAULT_INJECTION && MMC 1424 help 1425 Provide fault-injection capability for MMC IO. 1426 This will make the mmc core return data errors. This is 1427 useful to test the error handling in the mmc block device 1428 and to test how the mmc host driver handles retries from 1429 the block device. 1430 1431config FAULT_INJECTION_DEBUG_FS 1432 bool "Debugfs entries for fault-injection capabilities" 1433 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 1434 help 1435 Enable configuration of fault-injection capabilities via debugfs. 1436 1437config FAULT_INJECTION_STACKTRACE_FILTER 1438 bool "stacktrace filter for fault-injection capabilities" 1439 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 1440 depends on !X86_64 1441 select STACKTRACE 1442 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC && !SCORE 1443 help 1444 Provide stacktrace filter for fault-injection capabilities 1445 1446config LATENCYTOP 1447 bool "Latency measuring infrastructure" 1448 depends on HAVE_LATENCYTOP_SUPPORT 1449 depends on DEBUG_KERNEL 1450 depends on STACKTRACE_SUPPORT 1451 depends on PROC_FS 1452 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC 1453 select KALLSYMS 1454 select KALLSYMS_ALL 1455 select STACKTRACE 1456 select SCHEDSTATS 1457 select SCHED_DEBUG 1458 help 1459 Enable this option if you want to use the LatencyTOP tool 1460 to find out which userspace is blocking on what kernel operations. 1461 1462config ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS 1463 bool 1464 1465config DEBUG_STRICT_USER_COPY_CHECKS 1466 bool "Strict user copy size checks" 1467 depends on ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS 1468 depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING 1469 help 1470 Enabling this option turns a certain set of sanity checks for user 1471 copy operations into compile time failures. 1472 1473 The copy_from_user() etc checks are there to help test if there 1474 are sufficient security checks on the length argument of 1475 the copy operation, by having gcc prove that the argument is 1476 within bounds. 1477 1478 If unsure, say N. 1479 1480source kernel/trace/Kconfig 1481 1482menu "Runtime Testing" 1483 1484config LKDTM 1485 tristate "Linux Kernel Dump Test Tool Module" 1486 depends on DEBUG_FS 1487 depends on BLOCK 1488 default n 1489 help 1490 This module enables testing of the different dumping mechanisms by 1491 inducing system failures at predefined crash points. 1492 If you don't need it: say N 1493 Choose M here to compile this code as a module. The module will be 1494 called lkdtm. 1495 1496 Documentation on how to use the module can be found in 1497 Documentation/fault-injection/provoke-crashes.txt 1498 1499config TEST_LIST_SORT 1500 bool "Linked list sorting test" 1501 depends on DEBUG_KERNEL 1502 help 1503 Enable this to turn on 'list_sort()' function test. This test is 1504 executed only once during system boot, so affects only boot time. 1505 1506 If unsure, say N. 1507 1508config KPROBES_SANITY_TEST 1509 bool "Kprobes sanity tests" 1510 depends on DEBUG_KERNEL 1511 depends on KPROBES 1512 default n 1513 help 1514 This option provides for testing basic kprobes functionality on 1515 boot. A sample kprobe, jprobe and kretprobe are inserted and 1516 verified for functionality. 1517 1518 Say N if you are unsure. 1519 1520config BACKTRACE_SELF_TEST 1521 tristate "Self test for the backtrace code" 1522 depends on DEBUG_KERNEL 1523 default n 1524 help 1525 This option provides a kernel module that can be used to test 1526 the kernel stack backtrace code. This option is not useful 1527 for distributions or general kernels, but only for kernel 1528 developers working on architecture code. 1529 1530 Note that if you want to also test saved backtraces, you will 1531 have to enable STACKTRACE as well. 1532 1533 Say N if you are unsure. 1534 1535config RBTREE_TEST 1536 tristate "Red-Black tree test" 1537 depends on DEBUG_KERNEL 1538 help 1539 A benchmark measuring the performance of the rbtree library. 1540 Also includes rbtree invariant checks. 1541 1542config INTERVAL_TREE_TEST 1543 tristate "Interval tree test" 1544 depends on m && DEBUG_KERNEL 1545 select INTERVAL_TREE 1546 help 1547 A benchmark measuring the performance of the interval tree library 1548 1549config PERCPU_TEST 1550 tristate "Per cpu operations test" 1551 depends on m && DEBUG_KERNEL 1552 help 1553 Enable this option to build test module which validates per-cpu 1554 operations. 1555 1556 If unsure, say N. 1557 1558config ATOMIC64_SELFTEST 1559 bool "Perform an atomic64_t self-test at boot" 1560 help 1561 Enable this option to test the atomic64_t functions at boot. 1562 1563 If unsure, say N. 1564 1565config ASYNC_RAID6_TEST 1566 tristate "Self test for hardware accelerated raid6 recovery" 1567 depends on ASYNC_RAID6_RECOV 1568 select ASYNC_MEMCPY 1569 ---help--- 1570 This is a one-shot self test that permutes through the 1571 recovery of all the possible two disk failure scenarios for a 1572 N-disk array. Recovery is performed with the asynchronous 1573 raid6 recovery routines, and will optionally use an offload 1574 engine if one is available. 1575 1576 If unsure, say N. 1577 1578config TEST_STRING_HELPERS 1579 tristate "Test functions located in the string_helpers module at runtime" 1580 1581config TEST_KSTRTOX 1582 tristate "Test kstrto*() family of functions at runtime" 1583 1584config TEST_RHASHTABLE 1585 bool "Perform selftest on resizable hash table" 1586 default n 1587 help 1588 Enable this option to test the rhashtable functions at boot. 1589 1590 If unsure, say N. 1591 1592endmenu # runtime tests 1593 1594config PROVIDE_OHCI1394_DMA_INIT 1595 bool "Remote debugging over FireWire early on boot" 1596 depends on PCI && X86 1597 help 1598 If you want to debug problems which hang or crash the kernel early 1599 on boot and the crashing machine has a FireWire port, you can use 1600 this feature to remotely access the memory of the crashed machine 1601 over FireWire. This employs remote DMA as part of the OHCI1394 1602 specification which is now the standard for FireWire controllers. 1603 1604 With remote DMA, you can monitor the printk buffer remotely using 1605 firescope and access all memory below 4GB using fireproxy from gdb. 1606 Even controlling a kernel debugger is possible using remote DMA. 1607 1608 Usage: 1609 1610 If ohci1394_dma=early is used as boot parameter, it will initialize 1611 all OHCI1394 controllers which are found in the PCI config space. 1612 1613 As all changes to the FireWire bus such as enabling and disabling 1614 devices cause a bus reset and thereby disable remote DMA for all 1615 devices, be sure to have the cable plugged and FireWire enabled on 1616 the debugging host before booting the debug target for debugging. 1617 1618 This code (~1k) is freed after boot. By then, the firewire stack 1619 in charge of the OHCI-1394 controllers should be used instead. 1620 1621 See Documentation/debugging-via-ohci1394.txt for more information. 1622 1623config BUILD_DOCSRC 1624 bool "Build targets in Documentation/ tree" 1625 depends on HEADERS_CHECK 1626 help 1627 This option attempts to build objects from the source files in the 1628 kernel Documentation/ tree. 1629 1630 Say N if you are unsure. 1631 1632config DMA_API_DEBUG 1633 bool "Enable debugging of DMA-API usage" 1634 depends on HAVE_DMA_API_DEBUG 1635 help 1636 Enable this option to debug the use of the DMA API by device drivers. 1637 With this option you will be able to detect common bugs in device 1638 drivers like double-freeing of DMA mappings or freeing mappings that 1639 were never allocated. 1640 1641 This also attempts to catch cases where a page owned by DMA is 1642 accessed by the cpu in a way that could cause data corruption. For 1643 example, this enables cow_user_page() to check that the source page is 1644 not undergoing DMA. 1645 1646 This option causes a performance degradation. Use only if you want to 1647 debug device drivers and dma interactions. 1648 1649 If unsure, say N. 1650 1651config TEST_LKM 1652 tristate "Test module loading with 'hello world' module" 1653 default n 1654 depends on m 1655 help 1656 This builds the "test_module" module that emits "Hello, world" 1657 on printk when loaded. It is designed to be used for basic 1658 evaluation of the module loading subsystem (for example when 1659 validating module verification). It lacks any extra dependencies, 1660 and will not normally be loaded by the system unless explicitly 1661 requested by name. 1662 1663 If unsure, say N. 1664 1665config TEST_USER_COPY 1666 tristate "Test user/kernel boundary protections" 1667 default n 1668 depends on m 1669 help 1670 This builds the "test_user_copy" module that runs sanity checks 1671 on the copy_to/from_user infrastructure, making sure basic 1672 user/kernel boundary testing is working. If it fails to load, 1673 a regression has been detected in the user/kernel memory boundary 1674 protections. 1675 1676 If unsure, say N. 1677 1678config TEST_BPF 1679 tristate "Test BPF filter functionality" 1680 default n 1681 depends on m && NET 1682 help 1683 This builds the "test_bpf" module that runs various test vectors 1684 against the BPF interpreter or BPF JIT compiler depending on the 1685 current setting. This is in particular useful for BPF JIT compiler 1686 development, but also to run regression tests against changes in 1687 the interpreter code. It also enables test stubs for eBPF maps and 1688 verifier used by user space verifier testsuite. 1689 1690 If unsure, say N. 1691 1692config TEST_FIRMWARE 1693 tristate "Test firmware loading via userspace interface" 1694 default n 1695 depends on FW_LOADER 1696 help 1697 This builds the "test_firmware" module that creates a userspace 1698 interface for testing firmware loading. This can be used to 1699 control the triggering of firmware loading without needing an 1700 actual firmware-using device. The contents can be rechecked by 1701 userspace. 1702 1703 If unsure, say N. 1704 1705config TEST_UDELAY 1706 tristate "udelay test driver" 1707 default n 1708 help 1709 This builds the "udelay_test" module that helps to make sure 1710 that udelay() is working properly. 1711 1712 If unsure, say N. 1713 1714source "samples/Kconfig" 1715 1716source "lib/Kconfig.kgdb" 1717 1718