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