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 && !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 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 MAGIC_SYSRQ_DEFAULT_ENABLE 316 hex "Enable magic SysRq key functions by default" 317 depends on MAGIC_SYSRQ 318 default 0x1 319 help 320 Specifies which SysRq key functions are enabled by default. 321 This may be set to 1 or 0 to enable or disable them all, or 322 to a bitmask as described in Documentation/sysrq.txt. 323 324config DEBUG_KERNEL 325 bool "Kernel debugging" 326 help 327 Say Y here if you are developing drivers or trying to debug and 328 identify kernel problems. 329 330menu "Memory Debugging" 331 332source mm/Kconfig.debug 333 334config DEBUG_OBJECTS 335 bool "Debug object operations" 336 depends on DEBUG_KERNEL 337 help 338 If you say Y here, additional code will be inserted into the 339 kernel to track the life time of various objects and validate 340 the operations on those objects. 341 342config DEBUG_OBJECTS_SELFTEST 343 bool "Debug objects selftest" 344 depends on DEBUG_OBJECTS 345 help 346 This enables the selftest of the object debug code. 347 348config DEBUG_OBJECTS_FREE 349 bool "Debug objects in freed memory" 350 depends on DEBUG_OBJECTS 351 help 352 This enables checks whether a k/v free operation frees an area 353 which contains an object which has not been deactivated 354 properly. This can make kmalloc/kfree-intensive workloads 355 much slower. 356 357config DEBUG_OBJECTS_TIMERS 358 bool "Debug timer objects" 359 depends on DEBUG_OBJECTS 360 help 361 If you say Y here, additional code will be inserted into the 362 timer routines to track the life time of timer objects and 363 validate the timer operations. 364 365config DEBUG_OBJECTS_WORK 366 bool "Debug work objects" 367 depends on DEBUG_OBJECTS 368 help 369 If you say Y here, additional code will be inserted into the 370 work queue routines to track the life time of work objects and 371 validate the work operations. 372 373config DEBUG_OBJECTS_RCU_HEAD 374 bool "Debug RCU callbacks objects" 375 depends on DEBUG_OBJECTS 376 help 377 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 378 379config DEBUG_OBJECTS_PERCPU_COUNTER 380 bool "Debug percpu counter objects" 381 depends on DEBUG_OBJECTS 382 help 383 If you say Y here, additional code will be inserted into the 384 percpu counter routines to track the life time of percpu counter 385 objects and validate the percpu counter operations. 386 387config DEBUG_OBJECTS_ENABLE_DEFAULT 388 int "debug_objects bootup default value (0-1)" 389 range 0 1 390 default "1" 391 depends on DEBUG_OBJECTS 392 help 393 Debug objects boot parameter default value 394 395config DEBUG_SLAB 396 bool "Debug slab memory allocations" 397 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK 398 help 399 Say Y here to have the kernel do limited verification on memory 400 allocation as well as poisoning memory on free to catch use of freed 401 memory. This can make kmalloc/kfree-intensive workloads much slower. 402 403config DEBUG_SLAB_LEAK 404 bool "Memory leak debugging" 405 depends on DEBUG_SLAB 406 407config SLUB_DEBUG_ON 408 bool "SLUB debugging on by default" 409 depends on SLUB && SLUB_DEBUG && !KMEMCHECK 410 default n 411 help 412 Boot with debugging on by default. SLUB boots by default with 413 the runtime debug capabilities switched off. Enabling this is 414 equivalent to specifying the "slub_debug" parameter on boot. 415 There is no support for more fine grained debug control like 416 possible with slub_debug=xxx. SLUB debugging may be switched 417 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying 418 "slub_debug=-". 419 420config SLUB_STATS 421 default n 422 bool "Enable SLUB performance statistics" 423 depends on SLUB && SYSFS 424 help 425 SLUB statistics are useful to debug SLUBs allocation behavior in 426 order find ways to optimize the allocator. This should never be 427 enabled for production use since keeping statistics slows down 428 the allocator by a few percentage points. The slabinfo command 429 supports the determination of the most active slabs to figure 430 out which slabs are relevant to a particular load. 431 Try running: slabinfo -DA 432 433config HAVE_DEBUG_KMEMLEAK 434 bool 435 436config DEBUG_KMEMLEAK 437 bool "Kernel memory leak detector" 438 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK 439 select DEBUG_FS 440 select STACKTRACE if STACKTRACE_SUPPORT 441 select KALLSYMS 442 select CRC32 443 help 444 Say Y here if you want to enable the memory leak 445 detector. The memory allocation/freeing is traced in a way 446 similar to the Boehm's conservative garbage collector, the 447 difference being that the orphan objects are not freed but 448 only shown in /sys/kernel/debug/kmemleak. Enabling this 449 feature will introduce an overhead to memory 450 allocations. See Documentation/kmemleak.txt for more 451 details. 452 453 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances 454 of finding leaks due to the slab objects poisoning. 455 456 In order to access the kmemleak file, debugfs needs to be 457 mounted (usually at /sys/kernel/debug). 458 459config DEBUG_KMEMLEAK_EARLY_LOG_SIZE 460 int "Maximum kmemleak early log entries" 461 depends on DEBUG_KMEMLEAK 462 range 200 40000 463 default 400 464 help 465 Kmemleak must track all the memory allocations to avoid 466 reporting false positives. Since memory may be allocated or 467 freed before kmemleak is initialised, an early log buffer is 468 used to store these actions. If kmemleak reports "early log 469 buffer exceeded", please increase this value. 470 471config DEBUG_KMEMLEAK_TEST 472 tristate "Simple test for the kernel memory leak detector" 473 depends on DEBUG_KMEMLEAK && m 474 help 475 This option enables a module that explicitly leaks memory. 476 477 If unsure, say N. 478 479config DEBUG_KMEMLEAK_DEFAULT_OFF 480 bool "Default kmemleak to off" 481 depends on DEBUG_KMEMLEAK 482 help 483 Say Y here to disable kmemleak by default. It can then be enabled 484 on the command line via kmemleak=on. 485 486config DEBUG_STACK_USAGE 487 bool "Stack utilization instrumentation" 488 depends on DEBUG_KERNEL && !IA64 && !PARISC && !METAG 489 help 490 Enables the display of the minimum amount of free stack which each 491 task has ever had available in the sysrq-T and sysrq-P debug output. 492 493 This option will slow down process creation somewhat. 494 495config DEBUG_VM 496 bool "Debug VM" 497 depends on DEBUG_KERNEL 498 help 499 Enable this to turn on extended checks in the virtual-memory system 500 that may impact performance. 501 502 If unsure, say N. 503 504config DEBUG_VM_VMACACHE 505 bool "Debug VMA caching" 506 depends on DEBUG_VM 507 help 508 Enable this to turn on VMA caching debug information. Doing so 509 can cause significant overhead, so only enable it in non-production 510 environments. 511 512 If unsure, say N. 513 514config DEBUG_VM_RB 515 bool "Debug VM red-black trees" 516 depends on DEBUG_VM 517 help 518 Enable VM red-black tree debugging information and extra validations. 519 520 If unsure, say N. 521 522config DEBUG_VIRTUAL 523 bool "Debug VM translations" 524 depends on DEBUG_KERNEL && X86 525 help 526 Enable some costly sanity checks in virtual to page code. This can 527 catch mistakes with virt_to_page() and friends. 528 529 If unsure, say N. 530 531config DEBUG_NOMMU_REGIONS 532 bool "Debug the global anon/private NOMMU mapping region tree" 533 depends on DEBUG_KERNEL && !MMU 534 help 535 This option causes the global tree of anonymous and private mapping 536 regions to be regularly checked for invalid topology. 537 538config DEBUG_MEMORY_INIT 539 bool "Debug memory initialisation" if EXPERT 540 default !EXPERT 541 help 542 Enable this for additional checks during memory initialisation. 543 The sanity checks verify aspects of the VM such as the memory model 544 and other information provided by the architecture. Verbose 545 information will be printed at KERN_DEBUG loglevel depending 546 on the mminit_loglevel= command-line option. 547 548 If unsure, say Y 549 550config MEMORY_NOTIFIER_ERROR_INJECT 551 tristate "Memory hotplug notifier error injection module" 552 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION 553 help 554 This option provides the ability to inject artificial errors to 555 memory hotplug notifier chain callbacks. It is controlled through 556 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 557 558 If the notifier call chain should be failed with some events 559 notified, write the error code to "actions/<notifier event>/error". 560 561 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 562 563 # cd /sys/kernel/debug/notifier-error-inject/memory 564 # echo -12 > actions/MEM_GOING_OFFLINE/error 565 # echo offline > /sys/devices/system/memory/memoryXXX/state 566 bash: echo: write error: Cannot allocate memory 567 568 To compile this code as a module, choose M here: the module will 569 be called memory-notifier-error-inject. 570 571 If unsure, say N. 572 573config DEBUG_PER_CPU_MAPS 574 bool "Debug access to per_cpu maps" 575 depends on DEBUG_KERNEL 576 depends on SMP 577 help 578 Say Y to verify that the per_cpu map being accessed has 579 been set up. This adds a fair amount of code to kernel memory 580 and decreases performance. 581 582 Say N if unsure. 583 584config DEBUG_HIGHMEM 585 bool "Highmem debugging" 586 depends on DEBUG_KERNEL && HIGHMEM 587 help 588 This option enables additional error checking for high memory 589 systems. Disable for production systems. 590 591config HAVE_DEBUG_STACKOVERFLOW 592 bool 593 594config DEBUG_STACKOVERFLOW 595 bool "Check for stack overflows" 596 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 597 ---help--- 598 Say Y here if you want to check for overflows of kernel, IRQ 599 and exception stacks (if your archicture uses them). This 600 option will show detailed messages if free stack space drops 601 below a certain limit. 602 603 These kinds of bugs usually occur when call-chains in the 604 kernel get too deep, especially when interrupts are 605 involved. 606 607 Use this in cases where you see apparently random memory 608 corruption, especially if it appears in 'struct thread_info' 609 610 If in doubt, say "N". 611 612source "lib/Kconfig.kmemcheck" 613 614endmenu # "Memory Debugging" 615 616config DEBUG_SHIRQ 617 bool "Debug shared IRQ handlers" 618 depends on DEBUG_KERNEL 619 help 620 Enable this to generate a spurious interrupt as soon as a shared 621 interrupt handler is registered, and just before one is deregistered. 622 Drivers ought to be able to handle interrupts coming in at those 623 points; some don't and need to be caught. 624 625menu "Debug Lockups and Hangs" 626 627config LOCKUP_DETECTOR 628 bool "Detect Hard and Soft Lockups" 629 depends on DEBUG_KERNEL && !S390 630 help 631 Say Y here to enable the kernel to act as a watchdog to detect 632 hard and soft lockups. 633 634 Softlockups are bugs that cause the kernel to loop in kernel 635 mode for more than 20 seconds, without giving other tasks a 636 chance to run. The current stack trace is displayed upon 637 detection and the system will stay locked up. 638 639 Hardlockups are bugs that cause the CPU to loop in kernel mode 640 for more than 10 seconds, without letting other interrupts have a 641 chance to run. The current stack trace is displayed upon detection 642 and the system will stay locked up. 643 644 The overhead should be minimal. A periodic hrtimer runs to 645 generate interrupts and kick the watchdog task every 4 seconds. 646 An NMI is generated every 10 seconds or so to check for hardlockups. 647 648 The frequency of hrtimer and NMI events and the soft and hard lockup 649 thresholds can be controlled through the sysctl watchdog_thresh. 650 651config HARDLOCKUP_DETECTOR 652 def_bool y 653 depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG 654 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI 655 656config BOOTPARAM_HARDLOCKUP_PANIC 657 bool "Panic (Reboot) On Hard Lockups" 658 depends on HARDLOCKUP_DETECTOR 659 help 660 Say Y here to enable the kernel to panic on "hard lockups", 661 which are bugs that cause the kernel to loop in kernel 662 mode with interrupts disabled for more than 10 seconds (configurable 663 using the watchdog_thresh sysctl). 664 665 Say N if unsure. 666 667config BOOTPARAM_HARDLOCKUP_PANIC_VALUE 668 int 669 depends on HARDLOCKUP_DETECTOR 670 range 0 1 671 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC 672 default 1 if BOOTPARAM_HARDLOCKUP_PANIC 673 674config BOOTPARAM_SOFTLOCKUP_PANIC 675 bool "Panic (Reboot) On Soft Lockups" 676 depends on LOCKUP_DETECTOR 677 help 678 Say Y here to enable the kernel to panic on "soft lockups", 679 which are bugs that cause the kernel to loop in kernel 680 mode for more than 20 seconds (configurable using the watchdog_thresh 681 sysctl), without giving other tasks a chance to run. 682 683 The panic can be used in combination with panic_timeout, 684 to cause the system to reboot automatically after a 685 lockup has been detected. This feature is useful for 686 high-availability systems that have uptime guarantees and 687 where a lockup must be resolved ASAP. 688 689 Say N if unsure. 690 691config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE 692 int 693 depends on LOCKUP_DETECTOR 694 range 0 1 695 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC 696 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC 697 698config DETECT_HUNG_TASK 699 bool "Detect Hung Tasks" 700 depends on DEBUG_KERNEL 701 default LOCKUP_DETECTOR 702 help 703 Say Y here to enable the kernel to detect "hung tasks", 704 which are bugs that cause the task to be stuck in 705 uninterruptible "D" state indefinitiley. 706 707 When a hung task is detected, the kernel will print the 708 current stack trace (which you should report), but the 709 task will stay in uninterruptible state. If lockdep is 710 enabled then all held locks will also be reported. This 711 feature has negligible overhead. 712 713config DEFAULT_HUNG_TASK_TIMEOUT 714 int "Default timeout for hung task detection (in seconds)" 715 depends on DETECT_HUNG_TASK 716 default 120 717 help 718 This option controls the default timeout (in seconds) used 719 to determine when a task has become non-responsive and should 720 be considered hung. 721 722 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 723 sysctl or by writing a value to 724 /proc/sys/kernel/hung_task_timeout_secs. 725 726 A timeout of 0 disables the check. The default is two minutes. 727 Keeping the default should be fine in most cases. 728 729config BOOTPARAM_HUNG_TASK_PANIC 730 bool "Panic (Reboot) On Hung Tasks" 731 depends on DETECT_HUNG_TASK 732 help 733 Say Y here to enable the kernel to panic on "hung tasks", 734 which are bugs that cause the kernel to leave a task stuck 735 in uninterruptible "D" state. 736 737 The panic can be used in combination with panic_timeout, 738 to cause the system to reboot automatically after a 739 hung task has been detected. This feature is useful for 740 high-availability systems that have uptime guarantees and 741 where a hung tasks must be resolved ASAP. 742 743 Say N if unsure. 744 745config BOOTPARAM_HUNG_TASK_PANIC_VALUE 746 int 747 depends on DETECT_HUNG_TASK 748 range 0 1 749 default 0 if !BOOTPARAM_HUNG_TASK_PANIC 750 default 1 if BOOTPARAM_HUNG_TASK_PANIC 751 752endmenu # "Debug lockups and hangs" 753 754config PANIC_ON_OOPS 755 bool "Panic on Oops" 756 help 757 Say Y here to enable the kernel to panic when it oopses. This 758 has the same effect as setting oops=panic on the kernel command 759 line. 760 761 This feature is useful to ensure that the kernel does not do 762 anything erroneous after an oops which could result in data 763 corruption or other issues. 764 765 Say N if unsure. 766 767config PANIC_ON_OOPS_VALUE 768 int 769 range 0 1 770 default 0 if !PANIC_ON_OOPS 771 default 1 if PANIC_ON_OOPS 772 773config PANIC_TIMEOUT 774 int "panic timeout" 775 default 0 776 help 777 Set the timeout value (in seconds) until a reboot occurs when the 778 the kernel panics. If n = 0, then we wait forever. A timeout 779 value n > 0 will wait n seconds before rebooting, while a timeout 780 value n < 0 will reboot immediately. 781 782config SCHED_DEBUG 783 bool "Collect scheduler debugging info" 784 depends on DEBUG_KERNEL && PROC_FS 785 default y 786 help 787 If you say Y here, the /proc/sched_debug file will be provided 788 that can help debug the scheduler. The runtime overhead of this 789 option is minimal. 790 791config SCHEDSTATS 792 bool "Collect scheduler statistics" 793 depends on DEBUG_KERNEL && PROC_FS 794 help 795 If you say Y here, additional code will be inserted into the 796 scheduler and related routines to collect statistics about 797 scheduler behavior and provide them in /proc/schedstat. These 798 stats may be useful for both tuning and debugging the scheduler 799 If you aren't debugging the scheduler or trying to tune a specific 800 application, you can say N to avoid the very slight overhead 801 this adds. 802 803config TIMER_STATS 804 bool "Collect kernel timers statistics" 805 depends on DEBUG_KERNEL && PROC_FS 806 help 807 If you say Y here, additional code will be inserted into the 808 timer routines to collect statistics about kernel timers being 809 reprogrammed. The statistics can be read from /proc/timer_stats. 810 The statistics collection is started by writing 1 to /proc/timer_stats, 811 writing 0 stops it. This feature is useful to collect information 812 about timer usage patterns in kernel and userspace. This feature 813 is lightweight if enabled in the kernel config but not activated 814 (it defaults to deactivated on bootup and will only be activated 815 if some application like powertop activates it explicitly). 816 817config DEBUG_PREEMPT 818 bool "Debug preemptible kernel" 819 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT 820 default y 821 help 822 If you say Y here then the kernel will use a debug variant of the 823 commonly used smp_processor_id() function and will print warnings 824 if kernel code uses it in a preemption-unsafe way. Also, the kernel 825 will detect preemption count underflows. 826 827menu "Lock Debugging (spinlocks, mutexes, etc...)" 828 829config DEBUG_RT_MUTEXES 830 bool "RT Mutex debugging, deadlock detection" 831 depends on DEBUG_KERNEL && RT_MUTEXES 832 help 833 This allows rt mutex semantics violations and rt mutex related 834 deadlocks (lockups) to be detected and reported automatically. 835 836config DEBUG_PI_LIST 837 bool 838 default y 839 depends on DEBUG_RT_MUTEXES 840 841config RT_MUTEX_TESTER 842 bool "Built-in scriptable tester for rt-mutexes" 843 depends on DEBUG_KERNEL && RT_MUTEXES 844 help 845 This option enables a rt-mutex tester. 846 847config DEBUG_SPINLOCK 848 bool "Spinlock and rw-lock debugging: basic checks" 849 depends on DEBUG_KERNEL 850 select UNINLINE_SPIN_UNLOCK 851 help 852 Say Y here and build SMP to catch missing spinlock initialization 853 and certain other kinds of spinlock errors commonly made. This is 854 best used in conjunction with the NMI watchdog so that spinlock 855 deadlocks are also debuggable. 856 857config DEBUG_MUTEXES 858 bool "Mutex debugging: basic checks" 859 depends on DEBUG_KERNEL 860 help 861 This feature allows mutex semantics violations to be detected and 862 reported. 863 864config DEBUG_WW_MUTEX_SLOWPATH 865 bool "Wait/wound mutex debugging: Slowpath testing" 866 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 867 select DEBUG_LOCK_ALLOC 868 select DEBUG_SPINLOCK 869 select DEBUG_MUTEXES 870 help 871 This feature enables slowpath testing for w/w mutex users by 872 injecting additional -EDEADLK wound/backoff cases. Together with 873 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 874 will test all possible w/w mutex interface abuse with the 875 exception of simply not acquiring all the required locks. 876 877config DEBUG_LOCK_ALLOC 878 bool "Lock debugging: detect incorrect freeing of live locks" 879 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 880 select DEBUG_SPINLOCK 881 select DEBUG_MUTEXES 882 select LOCKDEP 883 help 884 This feature will check whether any held lock (spinlock, rwlock, 885 mutex or rwsem) is incorrectly freed by the kernel, via any of the 886 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 887 vfree(), etc.), whether a live lock is incorrectly reinitialized via 888 spin_lock_init()/mutex_init()/etc., or whether there is any lock 889 held during task exit. 890 891config PROVE_LOCKING 892 bool "Lock debugging: prove locking correctness" 893 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 894 select LOCKDEP 895 select DEBUG_SPINLOCK 896 select DEBUG_MUTEXES 897 select DEBUG_LOCK_ALLOC 898 select TRACE_IRQFLAGS 899 default n 900 help 901 This feature enables the kernel to prove that all locking 902 that occurs in the kernel runtime is mathematically 903 correct: that under no circumstance could an arbitrary (and 904 not yet triggered) combination of observed locking 905 sequences (on an arbitrary number of CPUs, running an 906 arbitrary number of tasks and interrupt contexts) cause a 907 deadlock. 908 909 In short, this feature enables the kernel to report locking 910 related deadlocks before they actually occur. 911 912 The proof does not depend on how hard and complex a 913 deadlock scenario would be to trigger: how many 914 participant CPUs, tasks and irq-contexts would be needed 915 for it to trigger. The proof also does not depend on 916 timing: if a race and a resulting deadlock is possible 917 theoretically (no matter how unlikely the race scenario 918 is), it will be proven so and will immediately be 919 reported by the kernel (once the event is observed that 920 makes the deadlock theoretically possible). 921 922 If a deadlock is impossible (i.e. the locking rules, as 923 observed by the kernel, are mathematically correct), the 924 kernel reports nothing. 925 926 NOTE: this feature can also be enabled for rwlocks, mutexes 927 and rwsems - in which case all dependencies between these 928 different locking variants are observed and mapped too, and 929 the proof of observed correctness is also maintained for an 930 arbitrary combination of these separate locking variants. 931 932 For more details, see Documentation/lockdep-design.txt. 933 934config LOCKDEP 935 bool 936 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 937 select STACKTRACE 938 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC 939 select KALLSYMS 940 select KALLSYMS_ALL 941 942config LOCK_STAT 943 bool "Lock usage statistics" 944 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 945 select LOCKDEP 946 select DEBUG_SPINLOCK 947 select DEBUG_MUTEXES 948 select DEBUG_LOCK_ALLOC 949 default n 950 help 951 This feature enables tracking lock contention points 952 953 For more details, see Documentation/lockstat.txt 954 955 This also enables lock events required by "perf lock", 956 subcommand of perf. 957 If you want to use "perf lock", you also need to turn on 958 CONFIG_EVENT_TRACING. 959 960 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 961 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 962 963config DEBUG_LOCKDEP 964 bool "Lock dependency engine debugging" 965 depends on DEBUG_KERNEL && LOCKDEP 966 help 967 If you say Y here, the lock dependency engine will do 968 additional runtime checks to debug itself, at the price 969 of more runtime overhead. 970 971config DEBUG_ATOMIC_SLEEP 972 bool "Sleep inside atomic section checking" 973 select PREEMPT_COUNT 974 depends on DEBUG_KERNEL 975 help 976 If you say Y here, various routines which may sleep will become very 977 noisy if they are called inside atomic sections: when a spinlock is 978 held, inside an rcu read side critical section, inside preempt disabled 979 sections, inside an interrupt, etc... 980 981config DEBUG_LOCKING_API_SELFTESTS 982 bool "Locking API boot-time self-tests" 983 depends on DEBUG_KERNEL 984 help 985 Say Y here if you want the kernel to run a short self-test during 986 bootup. The self-test checks whether common types of locking bugs 987 are detected by debugging mechanisms or not. (if you disable 988 lock debugging then those bugs wont be detected of course.) 989 The following locking APIs are covered: spinlocks, rwlocks, 990 mutexes and rwsems. 991 992config LOCK_TORTURE_TEST 993 tristate "torture tests for locking" 994 depends on DEBUG_KERNEL 995 select TORTURE_TEST 996 default n 997 help 998 This option provides a kernel module that runs torture tests 999 on kernel locking primitives. The kernel module may be built 1000 after the fact on the running kernel to be tested, if desired. 1001 1002 Say Y here if you want kernel locking-primitive torture tests 1003 to be built into the kernel. 1004 Say M if you want these torture tests to build as a module. 1005 Say N if you are unsure. 1006 1007endmenu # lock debugging 1008 1009config TRACE_IRQFLAGS 1010 bool 1011 help 1012 Enables hooks to interrupt enabling and disabling for 1013 either tracing or lock debugging. 1014 1015config STACKTRACE 1016 bool 1017 depends on STACKTRACE_SUPPORT 1018 1019config DEBUG_KOBJECT 1020 bool "kobject debugging" 1021 depends on DEBUG_KERNEL 1022 help 1023 If you say Y here, some extra kobject debugging messages will be sent 1024 to the syslog. 1025 1026config DEBUG_KOBJECT_RELEASE 1027 bool "kobject release debugging" 1028 depends on DEBUG_OBJECTS_TIMERS 1029 help 1030 kobjects are reference counted objects. This means that their 1031 last reference count put is not predictable, and the kobject can 1032 live on past the point at which a driver decides to drop it's 1033 initial reference to the kobject gained on allocation. An 1034 example of this would be a struct device which has just been 1035 unregistered. 1036 1037 However, some buggy drivers assume that after such an operation, 1038 the memory backing the kobject can be immediately freed. This 1039 goes completely against the principles of a refcounted object. 1040 1041 If you say Y here, the kernel will delay the release of kobjects 1042 on the last reference count to improve the visibility of this 1043 kind of kobject release bug. 1044 1045config HAVE_DEBUG_BUGVERBOSE 1046 bool 1047 1048config DEBUG_BUGVERBOSE 1049 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT 1050 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE) 1051 default y 1052 help 1053 Say Y here to make BUG() panics output the file name and line number 1054 of the BUG call as well as the EIP and oops trace. This aids 1055 debugging but costs about 70-100K of memory. 1056 1057config DEBUG_LIST 1058 bool "Debug linked list manipulation" 1059 depends on DEBUG_KERNEL 1060 help 1061 Enable this to turn on extended checks in the linked-list 1062 walking routines. 1063 1064 If unsure, say N. 1065 1066config DEBUG_SG 1067 bool "Debug SG table operations" 1068 depends on DEBUG_KERNEL 1069 help 1070 Enable this to turn on checks on scatter-gather tables. This can 1071 help find problems with drivers that do not properly initialize 1072 their sg tables. 1073 1074 If unsure, say N. 1075 1076config DEBUG_NOTIFIERS 1077 bool "Debug notifier call chains" 1078 depends on DEBUG_KERNEL 1079 help 1080 Enable this to turn on sanity checking for notifier call chains. 1081 This is most useful for kernel developers to make sure that 1082 modules properly unregister themselves from notifier chains. 1083 This is a relatively cheap check but if you care about maximum 1084 performance, say N. 1085 1086config DEBUG_CREDENTIALS 1087 bool "Debug credential management" 1088 depends on DEBUG_KERNEL 1089 help 1090 Enable this to turn on some debug checking for credential 1091 management. The additional code keeps track of the number of 1092 pointers from task_structs to any given cred struct, and checks to 1093 see that this number never exceeds the usage count of the cred 1094 struct. 1095 1096 Furthermore, if SELinux is enabled, this also checks that the 1097 security pointer in the cred struct is never seen to be invalid. 1098 1099 If unsure, say N. 1100 1101menu "RCU Debugging" 1102 1103config PROVE_RCU 1104 bool "RCU debugging: prove RCU correctness" 1105 depends on PROVE_LOCKING 1106 default n 1107 help 1108 This feature enables lockdep extensions that check for correct 1109 use of RCU APIs. This is currently under development. Say Y 1110 if you want to debug RCU usage or help work on the PROVE_RCU 1111 feature. 1112 1113 Say N if you are unsure. 1114 1115config PROVE_RCU_REPEATEDLY 1116 bool "RCU debugging: don't disable PROVE_RCU on first splat" 1117 depends on PROVE_RCU 1118 default n 1119 help 1120 By itself, PROVE_RCU will disable checking upon issuing the 1121 first warning (or "splat"). This feature prevents such 1122 disabling, allowing multiple RCU-lockdep warnings to be printed 1123 on a single reboot. 1124 1125 Say Y to allow multiple RCU-lockdep warnings per boot. 1126 1127 Say N if you are unsure. 1128 1129config PROVE_RCU_DELAY 1130 bool "RCU debugging: preemptible RCU race provocation" 1131 depends on DEBUG_KERNEL && PREEMPT_RCU 1132 default n 1133 help 1134 There is a class of races that involve an unlikely preemption 1135 of __rcu_read_unlock() just after ->rcu_read_lock_nesting has 1136 been set to INT_MIN. This feature inserts a delay at that 1137 point to increase the probability of these races. 1138 1139 Say Y to increase probability of preemption of __rcu_read_unlock(). 1140 1141 Say N if you are unsure. 1142 1143config SPARSE_RCU_POINTER 1144 bool "RCU debugging: sparse-based checks for pointer usage" 1145 default n 1146 help 1147 This feature enables the __rcu sparse annotation for 1148 RCU-protected pointers. This annotation will cause sparse 1149 to flag any non-RCU used of annotated pointers. This can be 1150 helpful when debugging RCU usage. Please note that this feature 1151 is not intended to enforce code cleanliness; it is instead merely 1152 a debugging aid. 1153 1154 Say Y to make sparse flag questionable use of RCU-protected pointers 1155 1156 Say N if you are unsure. 1157 1158config TORTURE_TEST 1159 tristate 1160 default n 1161 1162config RCU_TORTURE_TEST 1163 tristate "torture tests for RCU" 1164 depends on DEBUG_KERNEL 1165 select TORTURE_TEST 1166 default n 1167 help 1168 This option provides a kernel module that runs torture tests 1169 on the RCU infrastructure. The kernel module may be built 1170 after the fact on the running kernel to be tested, if desired. 1171 1172 Say Y here if you want RCU torture tests to be built into 1173 the kernel. 1174 Say M if you want the RCU torture tests to build as a module. 1175 Say N if you are unsure. 1176 1177config RCU_TORTURE_TEST_RUNNABLE 1178 bool "torture tests for RCU runnable by default" 1179 depends on RCU_TORTURE_TEST = y 1180 default n 1181 help 1182 This option provides a way to build the RCU torture tests 1183 directly into the kernel without them starting up at boot 1184 time. You can use /proc/sys/kernel/rcutorture_runnable 1185 to manually override this setting. This /proc file is 1186 available only when the RCU torture tests have been built 1187 into the kernel. 1188 1189 Say Y here if you want the RCU torture tests to start during 1190 boot (you probably don't). 1191 Say N here if you want the RCU torture tests to start only 1192 after being manually enabled via /proc. 1193 1194config RCU_CPU_STALL_TIMEOUT 1195 int "RCU CPU stall timeout in seconds" 1196 depends on RCU_STALL_COMMON 1197 range 3 300 1198 default 21 1199 help 1200 If a given RCU grace period extends more than the specified 1201 number of seconds, a CPU stall warning is printed. If the 1202 RCU grace period persists, additional CPU stall warnings are 1203 printed at more widely spaced intervals. 1204 1205config RCU_CPU_STALL_VERBOSE 1206 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR" 1207 depends on TREE_PREEMPT_RCU 1208 default y 1209 help 1210 This option causes RCU to printk detailed per-task information 1211 for any tasks that are stalling the current RCU grace period. 1212 1213 Say N if you are unsure. 1214 1215 Say Y if you want to enable such checks. 1216 1217config RCU_CPU_STALL_INFO 1218 bool "Print additional diagnostics on RCU CPU stall" 1219 depends on (TREE_RCU || TREE_PREEMPT_RCU) && DEBUG_KERNEL 1220 default n 1221 help 1222 For each stalled CPU that is aware of the current RCU grace 1223 period, print out additional per-CPU diagnostic information 1224 regarding scheduling-clock ticks, idle state, and, 1225 for RCU_FAST_NO_HZ kernels, idle-entry state. 1226 1227 Say N if you are unsure. 1228 1229 Say Y if you want to enable such diagnostics. 1230 1231config RCU_TRACE 1232 bool "Enable tracing for RCU" 1233 depends on DEBUG_KERNEL 1234 select TRACE_CLOCK 1235 help 1236 This option provides tracing in RCU which presents stats 1237 in debugfs for debugging RCU implementation. 1238 1239 Say Y here if you want to enable RCU tracing 1240 Say N if you are unsure. 1241 1242endmenu # "RCU Debugging" 1243 1244config DEBUG_BLOCK_EXT_DEVT 1245 bool "Force extended block device numbers and spread them" 1246 depends on DEBUG_KERNEL 1247 depends on BLOCK 1248 default n 1249 help 1250 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON 1251 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT 1252 YOU ARE DOING. Distros, please enable this and fix whatever 1253 is broken. 1254 1255 Conventionally, block device numbers are allocated from 1256 predetermined contiguous area. However, extended block area 1257 may introduce non-contiguous block device numbers. This 1258 option forces most block device numbers to be allocated from 1259 the extended space and spreads them to discover kernel or 1260 userland code paths which assume predetermined contiguous 1261 device number allocation. 1262 1263 Note that turning on this debug option shuffles all the 1264 device numbers for all IDE and SCSI devices including libata 1265 ones, so root partition specified using device number 1266 directly (via rdev or root=MAJ:MIN) won't work anymore. 1267 Textual device names (root=/dev/sdXn) will continue to work. 1268 1269 Say N if you are unsure. 1270 1271config NOTIFIER_ERROR_INJECTION 1272 tristate "Notifier error injection" 1273 depends on DEBUG_KERNEL 1274 select DEBUG_FS 1275 help 1276 This option provides the ability to inject artificial errors to 1277 specified notifier chain callbacks. It is useful to test the error 1278 handling of notifier call chain failures. 1279 1280 Say N if unsure. 1281 1282config CPU_NOTIFIER_ERROR_INJECT 1283 tristate "CPU notifier error injection module" 1284 depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION 1285 help 1286 This option provides a kernel module that can be used to test 1287 the error handling of the cpu notifiers by injecting artificial 1288 errors to CPU notifier chain callbacks. It is controlled through 1289 debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu 1290 1291 If the notifier call chain should be failed with some events 1292 notified, write the error code to "actions/<notifier event>/error". 1293 1294 Example: Inject CPU offline error (-1 == -EPERM) 1295 1296 # cd /sys/kernel/debug/notifier-error-inject/cpu 1297 # echo -1 > actions/CPU_DOWN_PREPARE/error 1298 # echo 0 > /sys/devices/system/cpu/cpu1/online 1299 bash: echo: write error: Operation not permitted 1300 1301 To compile this code as a module, choose M here: the module will 1302 be called cpu-notifier-error-inject. 1303 1304 If unsure, say N. 1305 1306config PM_NOTIFIER_ERROR_INJECT 1307 tristate "PM notifier error injection module" 1308 depends on PM && NOTIFIER_ERROR_INJECTION 1309 default m if PM_DEBUG 1310 help 1311 This option provides the ability to inject artificial errors to 1312 PM notifier chain callbacks. It is controlled through debugfs 1313 interface /sys/kernel/debug/notifier-error-inject/pm 1314 1315 If the notifier call chain should be failed with some events 1316 notified, write the error code to "actions/<notifier event>/error". 1317 1318 Example: Inject PM suspend error (-12 = -ENOMEM) 1319 1320 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1321 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1322 # echo mem > /sys/power/state 1323 bash: echo: write error: Cannot allocate memory 1324 1325 To compile this code as a module, choose M here: the module will 1326 be called pm-notifier-error-inject. 1327 1328 If unsure, say N. 1329 1330config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1331 tristate "OF reconfig notifier error injection module" 1332 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1333 help 1334 This option provides the ability to inject artificial errors to 1335 OF reconfig notifier chain callbacks. It is controlled 1336 through debugfs interface under 1337 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1338 1339 If the notifier call chain should be failed with some events 1340 notified, write the error code to "actions/<notifier event>/error". 1341 1342 To compile this code as a module, choose M here: the module will 1343 be called of-reconfig-notifier-error-inject. 1344 1345 If unsure, say N. 1346 1347config FAULT_INJECTION 1348 bool "Fault-injection framework" 1349 depends on DEBUG_KERNEL 1350 help 1351 Provide fault-injection framework. 1352 For more details, see Documentation/fault-injection/. 1353 1354config FAILSLAB 1355 bool "Fault-injection capability for kmalloc" 1356 depends on FAULT_INJECTION 1357 depends on SLAB || SLUB 1358 help 1359 Provide fault-injection capability for kmalloc. 1360 1361config FAIL_PAGE_ALLOC 1362 bool "Fault-injection capabilitiy for alloc_pages()" 1363 depends on FAULT_INJECTION 1364 help 1365 Provide fault-injection capability for alloc_pages(). 1366 1367config FAIL_MAKE_REQUEST 1368 bool "Fault-injection capability for disk IO" 1369 depends on FAULT_INJECTION && BLOCK 1370 help 1371 Provide fault-injection capability for disk IO. 1372 1373config FAIL_IO_TIMEOUT 1374 bool "Fault-injection capability for faking disk interrupts" 1375 depends on FAULT_INJECTION && BLOCK 1376 help 1377 Provide fault-injection capability on end IO handling. This 1378 will make the block layer "forget" an interrupt as configured, 1379 thus exercising the error handling. 1380 1381 Only works with drivers that use the generic timeout handling, 1382 for others it wont do anything. 1383 1384config FAIL_MMC_REQUEST 1385 bool "Fault-injection capability for MMC IO" 1386 select DEBUG_FS 1387 depends on FAULT_INJECTION && MMC 1388 help 1389 Provide fault-injection capability for MMC IO. 1390 This will make the mmc core return data errors. This is 1391 useful to test the error handling in the mmc block device 1392 and to test how the mmc host driver handles retries from 1393 the block device. 1394 1395config FAULT_INJECTION_DEBUG_FS 1396 bool "Debugfs entries for fault-injection capabilities" 1397 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 1398 help 1399 Enable configuration of fault-injection capabilities via debugfs. 1400 1401config FAULT_INJECTION_STACKTRACE_FILTER 1402 bool "stacktrace filter for fault-injection capabilities" 1403 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 1404 depends on !X86_64 1405 select STACKTRACE 1406 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC 1407 help 1408 Provide stacktrace filter for fault-injection capabilities 1409 1410config LATENCYTOP 1411 bool "Latency measuring infrastructure" 1412 depends on HAVE_LATENCYTOP_SUPPORT 1413 depends on DEBUG_KERNEL 1414 depends on STACKTRACE_SUPPORT 1415 depends on PROC_FS 1416 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC 1417 select KALLSYMS 1418 select KALLSYMS_ALL 1419 select STACKTRACE 1420 select SCHEDSTATS 1421 select SCHED_DEBUG 1422 help 1423 Enable this option if you want to use the LatencyTOP tool 1424 to find out which userspace is blocking on what kernel operations. 1425 1426config ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS 1427 bool 1428 1429config DEBUG_STRICT_USER_COPY_CHECKS 1430 bool "Strict user copy size checks" 1431 depends on ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS 1432 depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING 1433 help 1434 Enabling this option turns a certain set of sanity checks for user 1435 copy operations into compile time failures. 1436 1437 The copy_from_user() etc checks are there to help test if there 1438 are sufficient security checks on the length argument of 1439 the copy operation, by having gcc prove that the argument is 1440 within bounds. 1441 1442 If unsure, say N. 1443 1444source kernel/trace/Kconfig 1445 1446menu "Runtime Testing" 1447 1448config LKDTM 1449 tristate "Linux Kernel Dump Test Tool Module" 1450 depends on DEBUG_FS 1451 depends on BLOCK 1452 default n 1453 help 1454 This module enables testing of the different dumping mechanisms by 1455 inducing system failures at predefined crash points. 1456 If you don't need it: say N 1457 Choose M here to compile this code as a module. The module will be 1458 called lkdtm. 1459 1460 Documentation on how to use the module can be found in 1461 Documentation/fault-injection/provoke-crashes.txt 1462 1463config TEST_LIST_SORT 1464 bool "Linked list sorting test" 1465 depends on DEBUG_KERNEL 1466 help 1467 Enable this to turn on 'list_sort()' function test. This test is 1468 executed only once during system boot, so affects only boot time. 1469 1470 If unsure, say N. 1471 1472config KPROBES_SANITY_TEST 1473 bool "Kprobes sanity tests" 1474 depends on DEBUG_KERNEL 1475 depends on KPROBES 1476 default n 1477 help 1478 This option provides for testing basic kprobes functionality on 1479 boot. A sample kprobe, jprobe and kretprobe are inserted and 1480 verified for functionality. 1481 1482 Say N if you are unsure. 1483 1484config BACKTRACE_SELF_TEST 1485 tristate "Self test for the backtrace code" 1486 depends on DEBUG_KERNEL 1487 default n 1488 help 1489 This option provides a kernel module that can be used to test 1490 the kernel stack backtrace code. This option is not useful 1491 for distributions or general kernels, but only for kernel 1492 developers working on architecture code. 1493 1494 Note that if you want to also test saved backtraces, you will 1495 have to enable STACKTRACE as well. 1496 1497 Say N if you are unsure. 1498 1499config RBTREE_TEST 1500 tristate "Red-Black tree test" 1501 depends on DEBUG_KERNEL 1502 help 1503 A benchmark measuring the performance of the rbtree library. 1504 Also includes rbtree invariant checks. 1505 1506config INTERVAL_TREE_TEST 1507 tristate "Interval tree test" 1508 depends on m && DEBUG_KERNEL 1509 help 1510 A benchmark measuring the performance of the interval tree library 1511 1512config PERCPU_TEST 1513 tristate "Per cpu operations test" 1514 depends on m && DEBUG_KERNEL 1515 help 1516 Enable this option to build test module which validates per-cpu 1517 operations. 1518 1519 If unsure, say N. 1520 1521config ATOMIC64_SELFTEST 1522 bool "Perform an atomic64_t self-test at boot" 1523 help 1524 Enable this option to test the atomic64_t functions at boot. 1525 1526 If unsure, say N. 1527 1528config ASYNC_RAID6_TEST 1529 tristate "Self test for hardware accelerated raid6 recovery" 1530 depends on ASYNC_RAID6_RECOV 1531 select ASYNC_MEMCPY 1532 ---help--- 1533 This is a one-shot self test that permutes through the 1534 recovery of all the possible two disk failure scenarios for a 1535 N-disk array. Recovery is performed with the asynchronous 1536 raid6 recovery routines, and will optionally use an offload 1537 engine if one is available. 1538 1539 If unsure, say N. 1540 1541config TEST_STRING_HELPERS 1542 tristate "Test functions located in the string_helpers module at runtime" 1543 1544config TEST_KSTRTOX 1545 tristate "Test kstrto*() family of functions at runtime" 1546 1547endmenu # runtime tests 1548 1549config PROVIDE_OHCI1394_DMA_INIT 1550 bool "Remote debugging over FireWire early on boot" 1551 depends on PCI && X86 1552 help 1553 If you want to debug problems which hang or crash the kernel early 1554 on boot and the crashing machine has a FireWire port, you can use 1555 this feature to remotely access the memory of the crashed machine 1556 over FireWire. This employs remote DMA as part of the OHCI1394 1557 specification which is now the standard for FireWire controllers. 1558 1559 With remote DMA, you can monitor the printk buffer remotely using 1560 firescope and access all memory below 4GB using fireproxy from gdb. 1561 Even controlling a kernel debugger is possible using remote DMA. 1562 1563 Usage: 1564 1565 If ohci1394_dma=early is used as boot parameter, it will initialize 1566 all OHCI1394 controllers which are found in the PCI config space. 1567 1568 As all changes to the FireWire bus such as enabling and disabling 1569 devices cause a bus reset and thereby disable remote DMA for all 1570 devices, be sure to have the cable plugged and FireWire enabled on 1571 the debugging host before booting the debug target for debugging. 1572 1573 This code (~1k) is freed after boot. By then, the firewire stack 1574 in charge of the OHCI-1394 controllers should be used instead. 1575 1576 See Documentation/debugging-via-ohci1394.txt for more information. 1577 1578config BUILD_DOCSRC 1579 bool "Build targets in Documentation/ tree" 1580 depends on HEADERS_CHECK 1581 help 1582 This option attempts to build objects from the source files in the 1583 kernel Documentation/ tree. 1584 1585 Say N if you are unsure. 1586 1587config DMA_API_DEBUG 1588 bool "Enable debugging of DMA-API usage" 1589 depends on HAVE_DMA_API_DEBUG 1590 help 1591 Enable this option to debug the use of the DMA API by device drivers. 1592 With this option you will be able to detect common bugs in device 1593 drivers like double-freeing of DMA mappings or freeing mappings that 1594 were never allocated. 1595 1596 This also attempts to catch cases where a page owned by DMA is 1597 accessed by the cpu in a way that could cause data corruption. For 1598 example, this enables cow_user_page() to check that the source page is 1599 not undergoing DMA. 1600 1601 This option causes a performance degradation. Use only if you want to 1602 debug device drivers and dma interactions. 1603 1604 If unsure, say N. 1605 1606config TEST_MODULE 1607 tristate "Test module loading with 'hello world' module" 1608 default n 1609 depends on m 1610 help 1611 This builds the "test_module" module that emits "Hello, world" 1612 on printk when loaded. It is designed to be used for basic 1613 evaluation of the module loading subsystem (for example when 1614 validating module verification). It lacks any extra dependencies, 1615 and will not normally be loaded by the system unless explicitly 1616 requested by name. 1617 1618 If unsure, say N. 1619 1620config TEST_USER_COPY 1621 tristate "Test user/kernel boundary protections" 1622 default n 1623 depends on m 1624 help 1625 This builds the "test_user_copy" module that runs sanity checks 1626 on the copy_to/from_user infrastructure, making sure basic 1627 user/kernel boundary testing is working. If it fails to load, 1628 a regression has been detected in the user/kernel memory boundary 1629 protections. 1630 1631 If unsure, say N. 1632 1633source "samples/Kconfig" 1634 1635source "lib/Kconfig.kgdb" 1636 1637