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 RT_MUTEX_TESTER 837 bool "Built-in scriptable tester for rt-mutexes" 838 depends on DEBUG_KERNEL && RT_MUTEXES 839 help 840 This option enables a rt-mutex tester. 841 842config DEBUG_SPINLOCK 843 bool "Spinlock and rw-lock debugging: basic checks" 844 depends on DEBUG_KERNEL 845 select UNINLINE_SPIN_UNLOCK 846 help 847 Say Y here and build SMP to catch missing spinlock initialization 848 and certain other kinds of spinlock errors commonly made. This is 849 best used in conjunction with the NMI watchdog so that spinlock 850 deadlocks are also debuggable. 851 852config DEBUG_MUTEXES 853 bool "Mutex debugging: basic checks" 854 depends on DEBUG_KERNEL 855 help 856 This feature allows mutex semantics violations to be detected and 857 reported. 858 859config DEBUG_WW_MUTEX_SLOWPATH 860 bool "Wait/wound mutex debugging: Slowpath testing" 861 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 862 select DEBUG_LOCK_ALLOC 863 select DEBUG_SPINLOCK 864 select DEBUG_MUTEXES 865 help 866 This feature enables slowpath testing for w/w mutex users by 867 injecting additional -EDEADLK wound/backoff cases. Together with 868 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 869 will test all possible w/w mutex interface abuse with the 870 exception of simply not acquiring all the required locks. 871 872config DEBUG_LOCK_ALLOC 873 bool "Lock debugging: detect incorrect freeing of live locks" 874 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 875 select DEBUG_SPINLOCK 876 select DEBUG_MUTEXES 877 select LOCKDEP 878 help 879 This feature will check whether any held lock (spinlock, rwlock, 880 mutex or rwsem) is incorrectly freed by the kernel, via any of the 881 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 882 vfree(), etc.), whether a live lock is incorrectly reinitialized via 883 spin_lock_init()/mutex_init()/etc., or whether there is any lock 884 held during task exit. 885 886config PROVE_LOCKING 887 bool "Lock debugging: prove locking correctness" 888 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 889 select LOCKDEP 890 select DEBUG_SPINLOCK 891 select DEBUG_MUTEXES 892 select DEBUG_LOCK_ALLOC 893 select TRACE_IRQFLAGS 894 default n 895 help 896 This feature enables the kernel to prove that all locking 897 that occurs in the kernel runtime is mathematically 898 correct: that under no circumstance could an arbitrary (and 899 not yet triggered) combination of observed locking 900 sequences (on an arbitrary number of CPUs, running an 901 arbitrary number of tasks and interrupt contexts) cause a 902 deadlock. 903 904 In short, this feature enables the kernel to report locking 905 related deadlocks before they actually occur. 906 907 The proof does not depend on how hard and complex a 908 deadlock scenario would be to trigger: how many 909 participant CPUs, tasks and irq-contexts would be needed 910 for it to trigger. The proof also does not depend on 911 timing: if a race and a resulting deadlock is possible 912 theoretically (no matter how unlikely the race scenario 913 is), it will be proven so and will immediately be 914 reported by the kernel (once the event is observed that 915 makes the deadlock theoretically possible). 916 917 If a deadlock is impossible (i.e. the locking rules, as 918 observed by the kernel, are mathematically correct), the 919 kernel reports nothing. 920 921 NOTE: this feature can also be enabled for rwlocks, mutexes 922 and rwsems - in which case all dependencies between these 923 different locking variants are observed and mapped too, and 924 the proof of observed correctness is also maintained for an 925 arbitrary combination of these separate locking variants. 926 927 For more details, see Documentation/lockdep-design.txt. 928 929config LOCKDEP 930 bool 931 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 932 select STACKTRACE 933 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC && !SCORE 934 select KALLSYMS 935 select KALLSYMS_ALL 936 937config LOCK_STAT 938 bool "Lock usage statistics" 939 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 940 select LOCKDEP 941 select DEBUG_SPINLOCK 942 select DEBUG_MUTEXES 943 select DEBUG_LOCK_ALLOC 944 default n 945 help 946 This feature enables tracking lock contention points 947 948 For more details, see Documentation/lockstat.txt 949 950 This also enables lock events required by "perf lock", 951 subcommand of perf. 952 If you want to use "perf lock", you also need to turn on 953 CONFIG_EVENT_TRACING. 954 955 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 956 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 957 958config DEBUG_LOCKDEP 959 bool "Lock dependency engine debugging" 960 depends on DEBUG_KERNEL && LOCKDEP 961 help 962 If you say Y here, the lock dependency engine will do 963 additional runtime checks to debug itself, at the price 964 of more runtime overhead. 965 966config DEBUG_ATOMIC_SLEEP 967 bool "Sleep inside atomic section checking" 968 select PREEMPT_COUNT 969 depends on DEBUG_KERNEL 970 help 971 If you say Y here, various routines which may sleep will become very 972 noisy if they are called inside atomic sections: when a spinlock is 973 held, inside an rcu read side critical section, inside preempt disabled 974 sections, inside an interrupt, etc... 975 976config DEBUG_LOCKING_API_SELFTESTS 977 bool "Locking API boot-time self-tests" 978 depends on DEBUG_KERNEL 979 help 980 Say Y here if you want the kernel to run a short self-test during 981 bootup. The self-test checks whether common types of locking bugs 982 are detected by debugging mechanisms or not. (if you disable 983 lock debugging then those bugs wont be detected of course.) 984 The following locking APIs are covered: spinlocks, rwlocks, 985 mutexes and rwsems. 986 987config LOCK_TORTURE_TEST 988 tristate "torture tests for locking" 989 depends on DEBUG_KERNEL 990 select TORTURE_TEST 991 default n 992 help 993 This option provides a kernel module that runs torture tests 994 on kernel locking primitives. The kernel module may be built 995 after the fact on the running kernel to be tested, if desired. 996 997 Say Y here if you want kernel locking-primitive torture tests 998 to be built into the kernel. 999 Say M if you want these torture tests to build as a module. 1000 Say N if you are unsure. 1001 1002endmenu # lock debugging 1003 1004config TRACE_IRQFLAGS 1005 bool 1006 help 1007 Enables hooks to interrupt enabling and disabling for 1008 either tracing or lock debugging. 1009 1010config STACKTRACE 1011 bool 1012 depends on STACKTRACE_SUPPORT 1013 1014config DEBUG_KOBJECT 1015 bool "kobject debugging" 1016 depends on DEBUG_KERNEL 1017 help 1018 If you say Y here, some extra kobject debugging messages will be sent 1019 to the syslog. 1020 1021config DEBUG_KOBJECT_RELEASE 1022 bool "kobject release debugging" 1023 depends on DEBUG_OBJECTS_TIMERS 1024 help 1025 kobjects are reference counted objects. This means that their 1026 last reference count put is not predictable, and the kobject can 1027 live on past the point at which a driver decides to drop it's 1028 initial reference to the kobject gained on allocation. An 1029 example of this would be a struct device which has just been 1030 unregistered. 1031 1032 However, some buggy drivers assume that after such an operation, 1033 the memory backing the kobject can be immediately freed. This 1034 goes completely against the principles of a refcounted object. 1035 1036 If you say Y here, the kernel will delay the release of kobjects 1037 on the last reference count to improve the visibility of this 1038 kind of kobject release bug. 1039 1040config HAVE_DEBUG_BUGVERBOSE 1041 bool 1042 1043config DEBUG_BUGVERBOSE 1044 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT 1045 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE) 1046 default y 1047 help 1048 Say Y here to make BUG() panics output the file name and line number 1049 of the BUG call as well as the EIP and oops trace. This aids 1050 debugging but costs about 70-100K of memory. 1051 1052config DEBUG_LIST 1053 bool "Debug linked list manipulation" 1054 depends on DEBUG_KERNEL 1055 help 1056 Enable this to turn on extended checks in the linked-list 1057 walking routines. 1058 1059 If unsure, say N. 1060 1061config DEBUG_PI_LIST 1062 bool "Debug priority linked list manipulation" 1063 depends on DEBUG_KERNEL 1064 help 1065 Enable this to turn on extended checks in the priority-ordered 1066 linked-list (plist) walking routines. This checks the entire 1067 list multiple times during each manipulation. 1068 1069 If unsure, say N. 1070 1071config DEBUG_SG 1072 bool "Debug SG table operations" 1073 depends on DEBUG_KERNEL 1074 help 1075 Enable this to turn on checks on scatter-gather tables. This can 1076 help find problems with drivers that do not properly initialize 1077 their sg tables. 1078 1079 If unsure, say N. 1080 1081config DEBUG_NOTIFIERS 1082 bool "Debug notifier call chains" 1083 depends on DEBUG_KERNEL 1084 help 1085 Enable this to turn on sanity checking for notifier call chains. 1086 This is most useful for kernel developers to make sure that 1087 modules properly unregister themselves from notifier chains. 1088 This is a relatively cheap check but if you care about maximum 1089 performance, say N. 1090 1091config DEBUG_CREDENTIALS 1092 bool "Debug credential management" 1093 depends on DEBUG_KERNEL 1094 help 1095 Enable this to turn on some debug checking for credential 1096 management. The additional code keeps track of the number of 1097 pointers from task_structs to any given cred struct, and checks to 1098 see that this number never exceeds the usage count of the cred 1099 struct. 1100 1101 Furthermore, if SELinux is enabled, this also checks that the 1102 security pointer in the cred struct is never seen to be invalid. 1103 1104 If unsure, say N. 1105 1106menu "RCU Debugging" 1107 1108config PROVE_RCU 1109 bool "RCU debugging: prove RCU correctness" 1110 depends on PROVE_LOCKING 1111 default n 1112 help 1113 This feature enables lockdep extensions that check for correct 1114 use of RCU APIs. This is currently under development. Say Y 1115 if you want to debug RCU usage or help work on the PROVE_RCU 1116 feature. 1117 1118 Say N if you are unsure. 1119 1120config PROVE_RCU_REPEATEDLY 1121 bool "RCU debugging: don't disable PROVE_RCU on first splat" 1122 depends on PROVE_RCU 1123 default n 1124 help 1125 By itself, PROVE_RCU will disable checking upon issuing the 1126 first warning (or "splat"). This feature prevents such 1127 disabling, allowing multiple RCU-lockdep warnings to be printed 1128 on a single reboot. 1129 1130 Say Y to allow multiple RCU-lockdep warnings per boot. 1131 1132 Say N if you are unsure. 1133 1134config PROVE_RCU_DELAY 1135 bool "RCU debugging: preemptible RCU race provocation" 1136 depends on DEBUG_KERNEL && PREEMPT_RCU 1137 default n 1138 help 1139 There is a class of races that involve an unlikely preemption 1140 of __rcu_read_unlock() just after ->rcu_read_lock_nesting has 1141 been set to INT_MIN. This feature inserts a delay at that 1142 point to increase the probability of these races. 1143 1144 Say Y to increase probability of preemption of __rcu_read_unlock(). 1145 1146 Say N if you are unsure. 1147 1148config SPARSE_RCU_POINTER 1149 bool "RCU debugging: sparse-based checks for pointer usage" 1150 default n 1151 help 1152 This feature enables the __rcu sparse annotation for 1153 RCU-protected pointers. This annotation will cause sparse 1154 to flag any non-RCU used of annotated pointers. This can be 1155 helpful when debugging RCU usage. Please note that this feature 1156 is not intended to enforce code cleanliness; it is instead merely 1157 a debugging aid. 1158 1159 Say Y to make sparse flag questionable use of RCU-protected pointers 1160 1161 Say N if you are unsure. 1162 1163config TORTURE_TEST 1164 tristate 1165 default n 1166 1167config RCU_TORTURE_TEST 1168 tristate "torture tests for RCU" 1169 depends on DEBUG_KERNEL 1170 select TORTURE_TEST 1171 default n 1172 help 1173 This option provides a kernel module that runs torture tests 1174 on the RCU infrastructure. The kernel module may be built 1175 after the fact on the running kernel to be tested, if desired. 1176 1177 Say Y here if you want RCU torture tests to be built into 1178 the kernel. 1179 Say M if you want the RCU torture tests to build as a module. 1180 Say N if you are unsure. 1181 1182config RCU_TORTURE_TEST_RUNNABLE 1183 bool "torture tests for RCU runnable by default" 1184 depends on RCU_TORTURE_TEST = y 1185 default n 1186 help 1187 This option provides a way to build the RCU torture tests 1188 directly into the kernel without them starting up at boot 1189 time. You can use /proc/sys/kernel/rcutorture_runnable 1190 to manually override this setting. This /proc file is 1191 available only when the RCU torture tests have been built 1192 into the kernel. 1193 1194 Say Y here if you want the RCU torture tests to start during 1195 boot (you probably don't). 1196 Say N here if you want the RCU torture tests to start only 1197 after being manually enabled via /proc. 1198 1199config RCU_CPU_STALL_TIMEOUT 1200 int "RCU CPU stall timeout in seconds" 1201 depends on RCU_STALL_COMMON 1202 range 3 300 1203 default 21 1204 help 1205 If a given RCU grace period extends more than the specified 1206 number of seconds, a CPU stall warning is printed. If the 1207 RCU grace period persists, additional CPU stall warnings are 1208 printed at more widely spaced intervals. 1209 1210config RCU_CPU_STALL_VERBOSE 1211 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR" 1212 depends on TREE_PREEMPT_RCU 1213 default y 1214 help 1215 This option causes RCU to printk detailed per-task information 1216 for any tasks that are stalling the current RCU grace period. 1217 1218 Say N if you are unsure. 1219 1220 Say Y if you want to enable such checks. 1221 1222config RCU_CPU_STALL_INFO 1223 bool "Print additional diagnostics on RCU CPU stall" 1224 depends on (TREE_RCU || TREE_PREEMPT_RCU) && DEBUG_KERNEL 1225 default n 1226 help 1227 For each stalled CPU that is aware of the current RCU grace 1228 period, print out additional per-CPU diagnostic information 1229 regarding scheduling-clock ticks, idle state, and, 1230 for RCU_FAST_NO_HZ kernels, idle-entry state. 1231 1232 Say N if you are unsure. 1233 1234 Say Y if you want to enable such diagnostics. 1235 1236config RCU_TRACE 1237 bool "Enable tracing for RCU" 1238 depends on DEBUG_KERNEL 1239 select TRACE_CLOCK 1240 help 1241 This option provides tracing in RCU which presents stats 1242 in debugfs for debugging RCU implementation. 1243 1244 Say Y here if you want to enable RCU tracing 1245 Say N if you are unsure. 1246 1247endmenu # "RCU Debugging" 1248 1249config DEBUG_BLOCK_EXT_DEVT 1250 bool "Force extended block device numbers and spread them" 1251 depends on DEBUG_KERNEL 1252 depends on BLOCK 1253 default n 1254 help 1255 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON 1256 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT 1257 YOU ARE DOING. Distros, please enable this and fix whatever 1258 is broken. 1259 1260 Conventionally, block device numbers are allocated from 1261 predetermined contiguous area. However, extended block area 1262 may introduce non-contiguous block device numbers. This 1263 option forces most block device numbers to be allocated from 1264 the extended space and spreads them to discover kernel or 1265 userland code paths which assume predetermined contiguous 1266 device number allocation. 1267 1268 Note that turning on this debug option shuffles all the 1269 device numbers for all IDE and SCSI devices including libata 1270 ones, so root partition specified using device number 1271 directly (via rdev or root=MAJ:MIN) won't work anymore. 1272 Textual device names (root=/dev/sdXn) will continue to work. 1273 1274 Say N if you are unsure. 1275 1276config NOTIFIER_ERROR_INJECTION 1277 tristate "Notifier error injection" 1278 depends on DEBUG_KERNEL 1279 select DEBUG_FS 1280 help 1281 This option provides the ability to inject artificial errors to 1282 specified notifier chain callbacks. It is useful to test the error 1283 handling of notifier call chain failures. 1284 1285 Say N if unsure. 1286 1287config CPU_NOTIFIER_ERROR_INJECT 1288 tristate "CPU notifier error injection module" 1289 depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION 1290 help 1291 This option provides a kernel module that can be used to test 1292 the error handling of the cpu notifiers by injecting artificial 1293 errors to CPU notifier chain callbacks. It is controlled through 1294 debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu 1295 1296 If the notifier call chain should be failed with some events 1297 notified, write the error code to "actions/<notifier event>/error". 1298 1299 Example: Inject CPU offline error (-1 == -EPERM) 1300 1301 # cd /sys/kernel/debug/notifier-error-inject/cpu 1302 # echo -1 > actions/CPU_DOWN_PREPARE/error 1303 # echo 0 > /sys/devices/system/cpu/cpu1/online 1304 bash: echo: write error: Operation not permitted 1305 1306 To compile this code as a module, choose M here: the module will 1307 be called cpu-notifier-error-inject. 1308 1309 If unsure, say N. 1310 1311config PM_NOTIFIER_ERROR_INJECT 1312 tristate "PM notifier error injection module" 1313 depends on PM && NOTIFIER_ERROR_INJECTION 1314 default m if PM_DEBUG 1315 help 1316 This option provides the ability to inject artificial errors to 1317 PM notifier chain callbacks. It is controlled through debugfs 1318 interface /sys/kernel/debug/notifier-error-inject/pm 1319 1320 If the notifier call chain should be failed with some events 1321 notified, write the error code to "actions/<notifier event>/error". 1322 1323 Example: Inject PM suspend error (-12 = -ENOMEM) 1324 1325 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1326 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1327 # echo mem > /sys/power/state 1328 bash: echo: write error: Cannot allocate memory 1329 1330 To compile this code as a module, choose M here: the module will 1331 be called pm-notifier-error-inject. 1332 1333 If unsure, say N. 1334 1335config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1336 tristate "OF reconfig notifier error injection module" 1337 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1338 help 1339 This option provides the ability to inject artificial errors to 1340 OF reconfig notifier chain callbacks. It is controlled 1341 through debugfs interface under 1342 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1343 1344 If the notifier call chain should be failed with some events 1345 notified, write the error code to "actions/<notifier event>/error". 1346 1347 To compile this code as a module, choose M here: the module will 1348 be called of-reconfig-notifier-error-inject. 1349 1350 If unsure, say N. 1351 1352config FAULT_INJECTION 1353 bool "Fault-injection framework" 1354 depends on DEBUG_KERNEL 1355 help 1356 Provide fault-injection framework. 1357 For more details, see Documentation/fault-injection/. 1358 1359config FAILSLAB 1360 bool "Fault-injection capability for kmalloc" 1361 depends on FAULT_INJECTION 1362 depends on SLAB || SLUB 1363 help 1364 Provide fault-injection capability for kmalloc. 1365 1366config FAIL_PAGE_ALLOC 1367 bool "Fault-injection capabilitiy for alloc_pages()" 1368 depends on FAULT_INJECTION 1369 help 1370 Provide fault-injection capability for alloc_pages(). 1371 1372config FAIL_MAKE_REQUEST 1373 bool "Fault-injection capability for disk IO" 1374 depends on FAULT_INJECTION && BLOCK 1375 help 1376 Provide fault-injection capability for disk IO. 1377 1378config FAIL_IO_TIMEOUT 1379 bool "Fault-injection capability for faking disk interrupts" 1380 depends on FAULT_INJECTION && BLOCK 1381 help 1382 Provide fault-injection capability on end IO handling. This 1383 will make the block layer "forget" an interrupt as configured, 1384 thus exercising the error handling. 1385 1386 Only works with drivers that use the generic timeout handling, 1387 for others it wont do anything. 1388 1389config FAIL_MMC_REQUEST 1390 bool "Fault-injection capability for MMC IO" 1391 select DEBUG_FS 1392 depends on FAULT_INJECTION && MMC 1393 help 1394 Provide fault-injection capability for MMC IO. 1395 This will make the mmc core return data errors. This is 1396 useful to test the error handling in the mmc block device 1397 and to test how the mmc host driver handles retries from 1398 the block device. 1399 1400config FAULT_INJECTION_DEBUG_FS 1401 bool "Debugfs entries for fault-injection capabilities" 1402 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 1403 help 1404 Enable configuration of fault-injection capabilities via debugfs. 1405 1406config FAULT_INJECTION_STACKTRACE_FILTER 1407 bool "stacktrace filter for fault-injection capabilities" 1408 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 1409 depends on !X86_64 1410 select STACKTRACE 1411 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC && !SCORE 1412 help 1413 Provide stacktrace filter for fault-injection capabilities 1414 1415config LATENCYTOP 1416 bool "Latency measuring infrastructure" 1417 depends on HAVE_LATENCYTOP_SUPPORT 1418 depends on DEBUG_KERNEL 1419 depends on STACKTRACE_SUPPORT 1420 depends on PROC_FS 1421 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC 1422 select KALLSYMS 1423 select KALLSYMS_ALL 1424 select STACKTRACE 1425 select SCHEDSTATS 1426 select SCHED_DEBUG 1427 help 1428 Enable this option if you want to use the LatencyTOP tool 1429 to find out which userspace is blocking on what kernel operations. 1430 1431config ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS 1432 bool 1433 1434config DEBUG_STRICT_USER_COPY_CHECKS 1435 bool "Strict user copy size checks" 1436 depends on ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS 1437 depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING 1438 help 1439 Enabling this option turns a certain set of sanity checks for user 1440 copy operations into compile time failures. 1441 1442 The copy_from_user() etc checks are there to help test if there 1443 are sufficient security checks on the length argument of 1444 the copy operation, by having gcc prove that the argument is 1445 within bounds. 1446 1447 If unsure, say N. 1448 1449source kernel/trace/Kconfig 1450 1451menu "Runtime Testing" 1452 1453config LKDTM 1454 tristate "Linux Kernel Dump Test Tool Module" 1455 depends on DEBUG_FS 1456 depends on BLOCK 1457 default n 1458 help 1459 This module enables testing of the different dumping mechanisms by 1460 inducing system failures at predefined crash points. 1461 If you don't need it: say N 1462 Choose M here to compile this code as a module. The module will be 1463 called lkdtm. 1464 1465 Documentation on how to use the module can be found in 1466 Documentation/fault-injection/provoke-crashes.txt 1467 1468config TEST_LIST_SORT 1469 bool "Linked list sorting test" 1470 depends on DEBUG_KERNEL 1471 help 1472 Enable this to turn on 'list_sort()' function test. This test is 1473 executed only once during system boot, so affects only boot time. 1474 1475 If unsure, say N. 1476 1477config KPROBES_SANITY_TEST 1478 bool "Kprobes sanity tests" 1479 depends on DEBUG_KERNEL 1480 depends on KPROBES 1481 default n 1482 help 1483 This option provides for testing basic kprobes functionality on 1484 boot. A sample kprobe, jprobe and kretprobe are inserted and 1485 verified for functionality. 1486 1487 Say N if you are unsure. 1488 1489config BACKTRACE_SELF_TEST 1490 tristate "Self test for the backtrace code" 1491 depends on DEBUG_KERNEL 1492 default n 1493 help 1494 This option provides a kernel module that can be used to test 1495 the kernel stack backtrace code. This option is not useful 1496 for distributions or general kernels, but only for kernel 1497 developers working on architecture code. 1498 1499 Note that if you want to also test saved backtraces, you will 1500 have to enable STACKTRACE as well. 1501 1502 Say N if you are unsure. 1503 1504config RBTREE_TEST 1505 tristate "Red-Black tree test" 1506 depends on DEBUG_KERNEL 1507 help 1508 A benchmark measuring the performance of the rbtree library. 1509 Also includes rbtree invariant checks. 1510 1511config INTERVAL_TREE_TEST 1512 tristate "Interval tree test" 1513 depends on m && DEBUG_KERNEL 1514 select INTERVAL_TREE 1515 help 1516 A benchmark measuring the performance of the interval tree library 1517 1518config PERCPU_TEST 1519 tristate "Per cpu operations test" 1520 depends on m && DEBUG_KERNEL 1521 help 1522 Enable this option to build test module which validates per-cpu 1523 operations. 1524 1525 If unsure, say N. 1526 1527config ATOMIC64_SELFTEST 1528 bool "Perform an atomic64_t self-test at boot" 1529 help 1530 Enable this option to test the atomic64_t functions at boot. 1531 1532 If unsure, say N. 1533 1534config ASYNC_RAID6_TEST 1535 tristate "Self test for hardware accelerated raid6 recovery" 1536 depends on ASYNC_RAID6_RECOV 1537 select ASYNC_MEMCPY 1538 ---help--- 1539 This is a one-shot self test that permutes through the 1540 recovery of all the possible two disk failure scenarios for a 1541 N-disk array. Recovery is performed with the asynchronous 1542 raid6 recovery routines, and will optionally use an offload 1543 engine if one is available. 1544 1545 If unsure, say N. 1546 1547config TEST_STRING_HELPERS 1548 tristate "Test functions located in the string_helpers module at runtime" 1549 1550config TEST_KSTRTOX 1551 tristate "Test kstrto*() family of functions at runtime" 1552 1553endmenu # runtime tests 1554 1555config PROVIDE_OHCI1394_DMA_INIT 1556 bool "Remote debugging over FireWire early on boot" 1557 depends on PCI && X86 1558 help 1559 If you want to debug problems which hang or crash the kernel early 1560 on boot and the crashing machine has a FireWire port, you can use 1561 this feature to remotely access the memory of the crashed machine 1562 over FireWire. This employs remote DMA as part of the OHCI1394 1563 specification which is now the standard for FireWire controllers. 1564 1565 With remote DMA, you can monitor the printk buffer remotely using 1566 firescope and access all memory below 4GB using fireproxy from gdb. 1567 Even controlling a kernel debugger is possible using remote DMA. 1568 1569 Usage: 1570 1571 If ohci1394_dma=early is used as boot parameter, it will initialize 1572 all OHCI1394 controllers which are found in the PCI config space. 1573 1574 As all changes to the FireWire bus such as enabling and disabling 1575 devices cause a bus reset and thereby disable remote DMA for all 1576 devices, be sure to have the cable plugged and FireWire enabled on 1577 the debugging host before booting the debug target for debugging. 1578 1579 This code (~1k) is freed after boot. By then, the firewire stack 1580 in charge of the OHCI-1394 controllers should be used instead. 1581 1582 See Documentation/debugging-via-ohci1394.txt for more information. 1583 1584config BUILD_DOCSRC 1585 bool "Build targets in Documentation/ tree" 1586 depends on HEADERS_CHECK 1587 help 1588 This option attempts to build objects from the source files in the 1589 kernel Documentation/ tree. 1590 1591 Say N if you are unsure. 1592 1593config DMA_API_DEBUG 1594 bool "Enable debugging of DMA-API usage" 1595 depends on HAVE_DMA_API_DEBUG 1596 help 1597 Enable this option to debug the use of the DMA API by device drivers. 1598 With this option you will be able to detect common bugs in device 1599 drivers like double-freeing of DMA mappings or freeing mappings that 1600 were never allocated. 1601 1602 This also attempts to catch cases where a page owned by DMA is 1603 accessed by the cpu in a way that could cause data corruption. For 1604 example, this enables cow_user_page() to check that the source page is 1605 not undergoing DMA. 1606 1607 This option causes a performance degradation. Use only if you want to 1608 debug device drivers and dma interactions. 1609 1610 If unsure, say N. 1611 1612config TEST_MODULE 1613 tristate "Test module loading with 'hello world' module" 1614 default n 1615 depends on m 1616 help 1617 This builds the "test_module" module that emits "Hello, world" 1618 on printk when loaded. It is designed to be used for basic 1619 evaluation of the module loading subsystem (for example when 1620 validating module verification). It lacks any extra dependencies, 1621 and will not normally be loaded by the system unless explicitly 1622 requested by name. 1623 1624 If unsure, say N. 1625 1626config TEST_USER_COPY 1627 tristate "Test user/kernel boundary protections" 1628 default n 1629 depends on m 1630 help 1631 This builds the "test_user_copy" module that runs sanity checks 1632 on the copy_to/from_user infrastructure, making sure basic 1633 user/kernel boundary testing is working. If it fails to load, 1634 a regression has been detected in the user/kernel memory boundary 1635 protections. 1636 1637 If unsure, say N. 1638 1639config TEST_BPF 1640 tristate "Test BPF filter functionality" 1641 default n 1642 depends on m && NET 1643 help 1644 This builds the "test_bpf" module that runs various test vectors 1645 against the BPF interpreter or BPF JIT compiler depending on the 1646 current setting. This is in particular useful for BPF JIT compiler 1647 development, but also to run regression tests against changes in 1648 the interpreter code. 1649 1650 If unsure, say N. 1651 1652source "samples/Kconfig" 1653 1654source "lib/Kconfig.kgdb" 1655 1656