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_RB 505 bool "Debug VM red-black trees" 506 depends on DEBUG_VM 507 help 508 Enable this to turn on more extended checks in the virtual-memory 509 system that may impact performance. 510 511 If unsure, say N. 512 513config DEBUG_VIRTUAL 514 bool "Debug VM translations" 515 depends on DEBUG_KERNEL && X86 516 help 517 Enable some costly sanity checks in virtual to page code. This can 518 catch mistakes with virt_to_page() and friends. 519 520 If unsure, say N. 521 522config DEBUG_NOMMU_REGIONS 523 bool "Debug the global anon/private NOMMU mapping region tree" 524 depends on DEBUG_KERNEL && !MMU 525 help 526 This option causes the global tree of anonymous and private mapping 527 regions to be regularly checked for invalid topology. 528 529config DEBUG_MEMORY_INIT 530 bool "Debug memory initialisation" if EXPERT 531 default !EXPERT 532 help 533 Enable this for additional checks during memory initialisation. 534 The sanity checks verify aspects of the VM such as the memory model 535 and other information provided by the architecture. Verbose 536 information will be printed at KERN_DEBUG loglevel depending 537 on the mminit_loglevel= command-line option. 538 539 If unsure, say Y 540 541config MEMORY_NOTIFIER_ERROR_INJECT 542 tristate "Memory hotplug notifier error injection module" 543 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION 544 help 545 This option provides the ability to inject artificial errors to 546 memory hotplug notifier chain callbacks. It is controlled through 547 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 548 549 If the notifier call chain should be failed with some events 550 notified, write the error code to "actions/<notifier event>/error". 551 552 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 553 554 # cd /sys/kernel/debug/notifier-error-inject/memory 555 # echo -12 > actions/MEM_GOING_OFFLINE/error 556 # echo offline > /sys/devices/system/memory/memoryXXX/state 557 bash: echo: write error: Cannot allocate memory 558 559 To compile this code as a module, choose M here: the module will 560 be called memory-notifier-error-inject. 561 562 If unsure, say N. 563 564config DEBUG_PER_CPU_MAPS 565 bool "Debug access to per_cpu maps" 566 depends on DEBUG_KERNEL 567 depends on SMP 568 help 569 Say Y to verify that the per_cpu map being accessed has 570 been set up. This adds a fair amount of code to kernel memory 571 and decreases performance. 572 573 Say N if unsure. 574 575config DEBUG_HIGHMEM 576 bool "Highmem debugging" 577 depends on DEBUG_KERNEL && HIGHMEM 578 help 579 This options enables addition error checking for high memory systems. 580 Disable for production systems. 581 582config HAVE_DEBUG_STACKOVERFLOW 583 bool 584 585config DEBUG_STACKOVERFLOW 586 bool "Check for stack overflows" 587 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 588 ---help--- 589 Say Y here if you want to check for overflows of kernel, IRQ 590 and exception stacks (if your archicture uses them). This 591 option will show detailed messages if free stack space drops 592 below a certain limit. 593 594 These kinds of bugs usually occur when call-chains in the 595 kernel get too deep, especially when interrupts are 596 involved. 597 598 Use this in cases where you see apparently random memory 599 corruption, especially if it appears in 'struct thread_info' 600 601 If in doubt, say "N". 602 603source "lib/Kconfig.kmemcheck" 604 605endmenu # "Memory Debugging" 606 607config DEBUG_SHIRQ 608 bool "Debug shared IRQ handlers" 609 depends on DEBUG_KERNEL 610 help 611 Enable this to generate a spurious interrupt as soon as a shared 612 interrupt handler is registered, and just before one is deregistered. 613 Drivers ought to be able to handle interrupts coming in at those 614 points; some don't and need to be caught. 615 616menu "Debug Lockups and Hangs" 617 618config LOCKUP_DETECTOR 619 bool "Detect Hard and Soft Lockups" 620 depends on DEBUG_KERNEL && !S390 621 help 622 Say Y here to enable the kernel to act as a watchdog to detect 623 hard and soft lockups. 624 625 Softlockups are bugs that cause the kernel to loop in kernel 626 mode for more than 20 seconds, without giving other tasks a 627 chance to run. The current stack trace is displayed upon 628 detection and the system will stay locked up. 629 630 Hardlockups are bugs that cause the CPU to loop in kernel mode 631 for more than 10 seconds, without letting other interrupts have a 632 chance to run. The current stack trace is displayed upon detection 633 and the system will stay locked up. 634 635 The overhead should be minimal. A periodic hrtimer runs to 636 generate interrupts and kick the watchdog task every 4 seconds. 637 An NMI is generated every 10 seconds or so to check for hardlockups. 638 639 The frequency of hrtimer and NMI events and the soft and hard lockup 640 thresholds can be controlled through the sysctl watchdog_thresh. 641 642config HARDLOCKUP_DETECTOR 643 def_bool y 644 depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG 645 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI 646 647config BOOTPARAM_HARDLOCKUP_PANIC 648 bool "Panic (Reboot) On Hard Lockups" 649 depends on HARDLOCKUP_DETECTOR 650 help 651 Say Y here to enable the kernel to panic on "hard lockups", 652 which are bugs that cause the kernel to loop in kernel 653 mode with interrupts disabled for more than 10 seconds (configurable 654 using the watchdog_thresh sysctl). 655 656 Say N if unsure. 657 658config BOOTPARAM_HARDLOCKUP_PANIC_VALUE 659 int 660 depends on HARDLOCKUP_DETECTOR 661 range 0 1 662 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC 663 default 1 if BOOTPARAM_HARDLOCKUP_PANIC 664 665config BOOTPARAM_SOFTLOCKUP_PANIC 666 bool "Panic (Reboot) On Soft Lockups" 667 depends on LOCKUP_DETECTOR 668 help 669 Say Y here to enable the kernel to panic on "soft lockups", 670 which are bugs that cause the kernel to loop in kernel 671 mode for more than 20 seconds (configurable using the watchdog_thresh 672 sysctl), without giving other tasks a chance to run. 673 674 The panic can be used in combination with panic_timeout, 675 to cause the system to reboot automatically after a 676 lockup has been detected. This feature is useful for 677 high-availability systems that have uptime guarantees and 678 where a lockup must be resolved ASAP. 679 680 Say N if unsure. 681 682config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE 683 int 684 depends on LOCKUP_DETECTOR 685 range 0 1 686 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC 687 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC 688 689config DETECT_HUNG_TASK 690 bool "Detect Hung Tasks" 691 depends on DEBUG_KERNEL 692 default LOCKUP_DETECTOR 693 help 694 Say Y here to enable the kernel to detect "hung tasks", 695 which are bugs that cause the task to be stuck in 696 uninterruptible "D" state indefinitiley. 697 698 When a hung task is detected, the kernel will print the 699 current stack trace (which you should report), but the 700 task will stay in uninterruptible state. If lockdep is 701 enabled then all held locks will also be reported. This 702 feature has negligible overhead. 703 704config DEFAULT_HUNG_TASK_TIMEOUT 705 int "Default timeout for hung task detection (in seconds)" 706 depends on DETECT_HUNG_TASK 707 default 120 708 help 709 This option controls the default timeout (in seconds) used 710 to determine when a task has become non-responsive and should 711 be considered hung. 712 713 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 714 sysctl or by writing a value to 715 /proc/sys/kernel/hung_task_timeout_secs. 716 717 A timeout of 0 disables the check. The default is two minutes. 718 Keeping the default should be fine in most cases. 719 720config BOOTPARAM_HUNG_TASK_PANIC 721 bool "Panic (Reboot) On Hung Tasks" 722 depends on DETECT_HUNG_TASK 723 help 724 Say Y here to enable the kernel to panic on "hung tasks", 725 which are bugs that cause the kernel to leave a task stuck 726 in uninterruptible "D" state. 727 728 The panic can be used in combination with panic_timeout, 729 to cause the system to reboot automatically after a 730 hung task has been detected. This feature is useful for 731 high-availability systems that have uptime guarantees and 732 where a hung tasks must be resolved ASAP. 733 734 Say N if unsure. 735 736config BOOTPARAM_HUNG_TASK_PANIC_VALUE 737 int 738 depends on DETECT_HUNG_TASK 739 range 0 1 740 default 0 if !BOOTPARAM_HUNG_TASK_PANIC 741 default 1 if BOOTPARAM_HUNG_TASK_PANIC 742 743endmenu # "Debug lockups and hangs" 744 745config PANIC_ON_OOPS 746 bool "Panic on Oops" 747 help 748 Say Y here to enable the kernel to panic when it oopses. This 749 has the same effect as setting oops=panic on the kernel command 750 line. 751 752 This feature is useful to ensure that the kernel does not do 753 anything erroneous after an oops which could result in data 754 corruption or other issues. 755 756 Say N if unsure. 757 758config PANIC_ON_OOPS_VALUE 759 int 760 range 0 1 761 default 0 if !PANIC_ON_OOPS 762 default 1 if PANIC_ON_OOPS 763 764config PANIC_TIMEOUT 765 int "panic timeout" 766 default 0 767 help 768 Set the timeout value (in seconds) until a reboot occurs when the 769 the kernel panics. If n = 0, then we wait forever. A timeout 770 value n > 0 will wait n seconds before rebooting, while a timeout 771 value n < 0 will reboot immediately. 772 773config SCHED_DEBUG 774 bool "Collect scheduler debugging info" 775 depends on DEBUG_KERNEL && PROC_FS 776 default y 777 help 778 If you say Y here, the /proc/sched_debug file will be provided 779 that can help debug the scheduler. The runtime overhead of this 780 option is minimal. 781 782config SCHEDSTATS 783 bool "Collect scheduler statistics" 784 depends on DEBUG_KERNEL && PROC_FS 785 help 786 If you say Y here, additional code will be inserted into the 787 scheduler and related routines to collect statistics about 788 scheduler behavior and provide them in /proc/schedstat. These 789 stats may be useful for both tuning and debugging the scheduler 790 If you aren't debugging the scheduler or trying to tune a specific 791 application, you can say N to avoid the very slight overhead 792 this adds. 793 794config TIMER_STATS 795 bool "Collect kernel timers statistics" 796 depends on DEBUG_KERNEL && PROC_FS 797 help 798 If you say Y here, additional code will be inserted into the 799 timer routines to collect statistics about kernel timers being 800 reprogrammed. The statistics can be read from /proc/timer_stats. 801 The statistics collection is started by writing 1 to /proc/timer_stats, 802 writing 0 stops it. This feature is useful to collect information 803 about timer usage patterns in kernel and userspace. This feature 804 is lightweight if enabled in the kernel config but not activated 805 (it defaults to deactivated on bootup and will only be activated 806 if some application like powertop activates it explicitly). 807 808config DEBUG_PREEMPT 809 bool "Debug preemptible kernel" 810 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT 811 default y 812 help 813 If you say Y here then the kernel will use a debug variant of the 814 commonly used smp_processor_id() function and will print warnings 815 if kernel code uses it in a preemption-unsafe way. Also, the kernel 816 will detect preemption count underflows. 817 818menu "Lock Debugging (spinlocks, mutexes, etc...)" 819 820config DEBUG_RT_MUTEXES 821 bool "RT Mutex debugging, deadlock detection" 822 depends on DEBUG_KERNEL && RT_MUTEXES 823 help 824 This allows rt mutex semantics violations and rt mutex related 825 deadlocks (lockups) to be detected and reported automatically. 826 827config DEBUG_PI_LIST 828 bool 829 default y 830 depends on DEBUG_RT_MUTEXES 831 832config RT_MUTEX_TESTER 833 bool "Built-in scriptable tester for rt-mutexes" 834 depends on DEBUG_KERNEL && RT_MUTEXES 835 help 836 This option enables a rt-mutex tester. 837 838config DEBUG_SPINLOCK 839 bool "Spinlock and rw-lock debugging: basic checks" 840 depends on DEBUG_KERNEL 841 select UNINLINE_SPIN_UNLOCK 842 help 843 Say Y here and build SMP to catch missing spinlock initialization 844 and certain other kinds of spinlock errors commonly made. This is 845 best used in conjunction with the NMI watchdog so that spinlock 846 deadlocks are also debuggable. 847 848config DEBUG_MUTEXES 849 bool "Mutex debugging: basic checks" 850 depends on DEBUG_KERNEL 851 help 852 This feature allows mutex semantics violations to be detected and 853 reported. 854 855config DEBUG_WW_MUTEX_SLOWPATH 856 bool "Wait/wound mutex debugging: Slowpath testing" 857 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 858 select DEBUG_LOCK_ALLOC 859 select DEBUG_SPINLOCK 860 select DEBUG_MUTEXES 861 help 862 This feature enables slowpath testing for w/w mutex users by 863 injecting additional -EDEADLK wound/backoff cases. Together with 864 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 865 will test all possible w/w mutex interface abuse with the 866 exception of simply not acquiring all the required locks. 867 868config DEBUG_LOCK_ALLOC 869 bool "Lock debugging: detect incorrect freeing of live locks" 870 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 871 select DEBUG_SPINLOCK 872 select DEBUG_MUTEXES 873 select LOCKDEP 874 help 875 This feature will check whether any held lock (spinlock, rwlock, 876 mutex or rwsem) is incorrectly freed by the kernel, via any of the 877 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 878 vfree(), etc.), whether a live lock is incorrectly reinitialized via 879 spin_lock_init()/mutex_init()/etc., or whether there is any lock 880 held during task exit. 881 882config PROVE_LOCKING 883 bool "Lock debugging: prove locking correctness" 884 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 885 select LOCKDEP 886 select DEBUG_SPINLOCK 887 select DEBUG_MUTEXES 888 select DEBUG_LOCK_ALLOC 889 select TRACE_IRQFLAGS 890 default n 891 help 892 This feature enables the kernel to prove that all locking 893 that occurs in the kernel runtime is mathematically 894 correct: that under no circumstance could an arbitrary (and 895 not yet triggered) combination of observed locking 896 sequences (on an arbitrary number of CPUs, running an 897 arbitrary number of tasks and interrupt contexts) cause a 898 deadlock. 899 900 In short, this feature enables the kernel to report locking 901 related deadlocks before they actually occur. 902 903 The proof does not depend on how hard and complex a 904 deadlock scenario would be to trigger: how many 905 participant CPUs, tasks and irq-contexts would be needed 906 for it to trigger. The proof also does not depend on 907 timing: if a race and a resulting deadlock is possible 908 theoretically (no matter how unlikely the race scenario 909 is), it will be proven so and will immediately be 910 reported by the kernel (once the event is observed that 911 makes the deadlock theoretically possible). 912 913 If a deadlock is impossible (i.e. the locking rules, as 914 observed by the kernel, are mathematically correct), the 915 kernel reports nothing. 916 917 NOTE: this feature can also be enabled for rwlocks, mutexes 918 and rwsems - in which case all dependencies between these 919 different locking variants are observed and mapped too, and 920 the proof of observed correctness is also maintained for an 921 arbitrary combination of these separate locking variants. 922 923 For more details, see Documentation/lockdep-design.txt. 924 925config LOCKDEP 926 bool 927 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 928 select STACKTRACE 929 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC 930 select KALLSYMS 931 select KALLSYMS_ALL 932 933config LOCK_STAT 934 bool "Lock usage statistics" 935 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 936 select LOCKDEP 937 select DEBUG_SPINLOCK 938 select DEBUG_MUTEXES 939 select DEBUG_LOCK_ALLOC 940 default n 941 help 942 This feature enables tracking lock contention points 943 944 For more details, see Documentation/lockstat.txt 945 946 This also enables lock events required by "perf lock", 947 subcommand of perf. 948 If you want to use "perf lock", you also need to turn on 949 CONFIG_EVENT_TRACING. 950 951 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 952 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 953 954config DEBUG_LOCKDEP 955 bool "Lock dependency engine debugging" 956 depends on DEBUG_KERNEL && LOCKDEP 957 help 958 If you say Y here, the lock dependency engine will do 959 additional runtime checks to debug itself, at the price 960 of more runtime overhead. 961 962config DEBUG_ATOMIC_SLEEP 963 bool "Sleep inside atomic section checking" 964 select PREEMPT_COUNT 965 depends on DEBUG_KERNEL 966 help 967 If you say Y here, various routines which may sleep will become very 968 noisy if they are called inside atomic sections: when a spinlock is 969 held, inside an rcu read side critical section, inside preempt disabled 970 sections, inside an interrupt, etc... 971 972config DEBUG_LOCKING_API_SELFTESTS 973 bool "Locking API boot-time self-tests" 974 depends on DEBUG_KERNEL 975 help 976 Say Y here if you want the kernel to run a short self-test during 977 bootup. The self-test checks whether common types of locking bugs 978 are detected by debugging mechanisms or not. (if you disable 979 lock debugging then those bugs wont be detected of course.) 980 The following locking APIs are covered: spinlocks, rwlocks, 981 mutexes and rwsems. 982 983endmenu # lock debugging 984 985config TRACE_IRQFLAGS 986 bool 987 help 988 Enables hooks to interrupt enabling and disabling for 989 either tracing or lock debugging. 990 991config STACKTRACE 992 bool 993 depends on STACKTRACE_SUPPORT 994 995config DEBUG_KOBJECT 996 bool "kobject debugging" 997 depends on DEBUG_KERNEL 998 help 999 If you say Y here, some extra kobject debugging messages will be sent 1000 to the syslog. 1001 1002config DEBUG_KOBJECT_RELEASE 1003 bool "kobject release debugging" 1004 depends on DEBUG_OBJECTS_TIMERS 1005 help 1006 kobjects are reference counted objects. This means that their 1007 last reference count put is not predictable, and the kobject can 1008 live on past the point at which a driver decides to drop it's 1009 initial reference to the kobject gained on allocation. An 1010 example of this would be a struct device which has just been 1011 unregistered. 1012 1013 However, some buggy drivers assume that after such an operation, 1014 the memory backing the kobject can be immediately freed. This 1015 goes completely against the principles of a refcounted object. 1016 1017 If you say Y here, the kernel will delay the release of kobjects 1018 on the last reference count to improve the visibility of this 1019 kind of kobject release bug. 1020 1021config HAVE_DEBUG_BUGVERBOSE 1022 bool 1023 1024config DEBUG_BUGVERBOSE 1025 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT 1026 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE) 1027 default y 1028 help 1029 Say Y here to make BUG() panics output the file name and line number 1030 of the BUG call as well as the EIP and oops trace. This aids 1031 debugging but costs about 70-100K of memory. 1032 1033config DEBUG_WRITECOUNT 1034 bool "Debug filesystem writers count" 1035 depends on DEBUG_KERNEL 1036 help 1037 Enable this to catch wrong use of the writers count in struct 1038 vfsmount. This will increase the size of each file struct by 1039 32 bits. 1040 1041 If unsure, say N. 1042 1043config DEBUG_LIST 1044 bool "Debug linked list manipulation" 1045 depends on DEBUG_KERNEL 1046 help 1047 Enable this to turn on extended checks in the linked-list 1048 walking routines. 1049 1050 If unsure, say N. 1051 1052config DEBUG_SG 1053 bool "Debug SG table operations" 1054 depends on DEBUG_KERNEL 1055 help 1056 Enable this to turn on checks on scatter-gather tables. This can 1057 help find problems with drivers that do not properly initialize 1058 their sg tables. 1059 1060 If unsure, say N. 1061 1062config DEBUG_NOTIFIERS 1063 bool "Debug notifier call chains" 1064 depends on DEBUG_KERNEL 1065 help 1066 Enable this to turn on sanity checking for notifier call chains. 1067 This is most useful for kernel developers to make sure that 1068 modules properly unregister themselves from notifier chains. 1069 This is a relatively cheap check but if you care about maximum 1070 performance, say N. 1071 1072config DEBUG_CREDENTIALS 1073 bool "Debug credential management" 1074 depends on DEBUG_KERNEL 1075 help 1076 Enable this to turn on some debug checking for credential 1077 management. The additional code keeps track of the number of 1078 pointers from task_structs to any given cred struct, and checks to 1079 see that this number never exceeds the usage count of the cred 1080 struct. 1081 1082 Furthermore, if SELinux is enabled, this also checks that the 1083 security pointer in the cred struct is never seen to be invalid. 1084 1085 If unsure, say N. 1086 1087menu "RCU Debugging" 1088 1089config PROVE_RCU 1090 bool "RCU debugging: prove RCU correctness" 1091 depends on PROVE_LOCKING 1092 default n 1093 help 1094 This feature enables lockdep extensions that check for correct 1095 use of RCU APIs. This is currently under development. Say Y 1096 if you want to debug RCU usage or help work on the PROVE_RCU 1097 feature. 1098 1099 Say N if you are unsure. 1100 1101config PROVE_RCU_REPEATEDLY 1102 bool "RCU debugging: don't disable PROVE_RCU on first splat" 1103 depends on PROVE_RCU 1104 default n 1105 help 1106 By itself, PROVE_RCU will disable checking upon issuing the 1107 first warning (or "splat"). This feature prevents such 1108 disabling, allowing multiple RCU-lockdep warnings to be printed 1109 on a single reboot. 1110 1111 Say Y to allow multiple RCU-lockdep warnings per boot. 1112 1113 Say N if you are unsure. 1114 1115config PROVE_RCU_DELAY 1116 bool "RCU debugging: preemptible RCU race provocation" 1117 depends on DEBUG_KERNEL && PREEMPT_RCU 1118 default n 1119 help 1120 There is a class of races that involve an unlikely preemption 1121 of __rcu_read_unlock() just after ->rcu_read_lock_nesting has 1122 been set to INT_MIN. This feature inserts a delay at that 1123 point to increase the probability of these races. 1124 1125 Say Y to increase probability of preemption of __rcu_read_unlock(). 1126 1127 Say N if you are unsure. 1128 1129config SPARSE_RCU_POINTER 1130 bool "RCU debugging: sparse-based checks for pointer usage" 1131 default n 1132 help 1133 This feature enables the __rcu sparse annotation for 1134 RCU-protected pointers. This annotation will cause sparse 1135 to flag any non-RCU used of annotated pointers. This can be 1136 helpful when debugging RCU usage. Please note that this feature 1137 is not intended to enforce code cleanliness; it is instead merely 1138 a debugging aid. 1139 1140 Say Y to make sparse flag questionable use of RCU-protected pointers 1141 1142 Say N if you are unsure. 1143 1144config RCU_TORTURE_TEST 1145 tristate "torture tests for RCU" 1146 depends on DEBUG_KERNEL 1147 default n 1148 help 1149 This option provides a kernel module that runs torture tests 1150 on the RCU infrastructure. The kernel module may be built 1151 after the fact on the running kernel to be tested, if desired. 1152 1153 Say Y here if you want RCU torture tests to be built into 1154 the kernel. 1155 Say M if you want the RCU torture tests to build as a module. 1156 Say N if you are unsure. 1157 1158config RCU_TORTURE_TEST_RUNNABLE 1159 bool "torture tests for RCU runnable by default" 1160 depends on RCU_TORTURE_TEST = y 1161 default n 1162 help 1163 This option provides a way to build the RCU torture tests 1164 directly into the kernel without them starting up at boot 1165 time. You can use /proc/sys/kernel/rcutorture_runnable 1166 to manually override this setting. This /proc file is 1167 available only when the RCU torture tests have been built 1168 into the kernel. 1169 1170 Say Y here if you want the RCU torture tests to start during 1171 boot (you probably don't). 1172 Say N here if you want the RCU torture tests to start only 1173 after being manually enabled via /proc. 1174 1175config RCU_CPU_STALL_TIMEOUT 1176 int "RCU CPU stall timeout in seconds" 1177 depends on RCU_STALL_COMMON 1178 range 3 300 1179 default 21 1180 help 1181 If a given RCU grace period extends more than the specified 1182 number of seconds, a CPU stall warning is printed. If the 1183 RCU grace period persists, additional CPU stall warnings are 1184 printed at more widely spaced intervals. 1185 1186config RCU_CPU_STALL_VERBOSE 1187 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR" 1188 depends on TREE_PREEMPT_RCU 1189 default y 1190 help 1191 This option causes RCU to printk detailed per-task information 1192 for any tasks that are stalling the current RCU grace period. 1193 1194 Say N if you are unsure. 1195 1196 Say Y if you want to enable such checks. 1197 1198config RCU_CPU_STALL_INFO 1199 bool "Print additional diagnostics on RCU CPU stall" 1200 depends on (TREE_RCU || TREE_PREEMPT_RCU) && DEBUG_KERNEL 1201 default n 1202 help 1203 For each stalled CPU that is aware of the current RCU grace 1204 period, print out additional per-CPU diagnostic information 1205 regarding scheduling-clock ticks, idle state, and, 1206 for RCU_FAST_NO_HZ kernels, idle-entry state. 1207 1208 Say N if you are unsure. 1209 1210 Say Y if you want to enable such diagnostics. 1211 1212config RCU_TRACE 1213 bool "Enable tracing for RCU" 1214 depends on DEBUG_KERNEL 1215 select TRACE_CLOCK 1216 help 1217 This option provides tracing in RCU which presents stats 1218 in debugfs for debugging RCU implementation. 1219 1220 Say Y here if you want to enable RCU tracing 1221 Say N if you are unsure. 1222 1223endmenu # "RCU Debugging" 1224 1225config DEBUG_BLOCK_EXT_DEVT 1226 bool "Force extended block device numbers and spread them" 1227 depends on DEBUG_KERNEL 1228 depends on BLOCK 1229 default n 1230 help 1231 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON 1232 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT 1233 YOU ARE DOING. Distros, please enable this and fix whatever 1234 is broken. 1235 1236 Conventionally, block device numbers are allocated from 1237 predetermined contiguous area. However, extended block area 1238 may introduce non-contiguous block device numbers. This 1239 option forces most block device numbers to be allocated from 1240 the extended space and spreads them to discover kernel or 1241 userland code paths which assume predetermined contiguous 1242 device number allocation. 1243 1244 Note that turning on this debug option shuffles all the 1245 device numbers for all IDE and SCSI devices including libata 1246 ones, so root partition specified using device number 1247 directly (via rdev or root=MAJ:MIN) won't work anymore. 1248 Textual device names (root=/dev/sdXn) will continue to work. 1249 1250 Say N if you are unsure. 1251 1252config NOTIFIER_ERROR_INJECTION 1253 tristate "Notifier error injection" 1254 depends on DEBUG_KERNEL 1255 select DEBUG_FS 1256 help 1257 This option provides the ability to inject artificial errors to 1258 specified notifier chain callbacks. It is useful to test the error 1259 handling of notifier call chain failures. 1260 1261 Say N if unsure. 1262 1263config CPU_NOTIFIER_ERROR_INJECT 1264 tristate "CPU notifier error injection module" 1265 depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION 1266 help 1267 This option provides a kernel module that can be used to test 1268 the error handling of the cpu notifiers by injecting artificial 1269 errors to CPU notifier chain callbacks. It is controlled through 1270 debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu 1271 1272 If the notifier call chain should be failed with some events 1273 notified, write the error code to "actions/<notifier event>/error". 1274 1275 Example: Inject CPU offline error (-1 == -EPERM) 1276 1277 # cd /sys/kernel/debug/notifier-error-inject/cpu 1278 # echo -1 > actions/CPU_DOWN_PREPARE/error 1279 # echo 0 > /sys/devices/system/cpu/cpu1/online 1280 bash: echo: write error: Operation not permitted 1281 1282 To compile this code as a module, choose M here: the module will 1283 be called cpu-notifier-error-inject. 1284 1285 If unsure, say N. 1286 1287config PM_NOTIFIER_ERROR_INJECT 1288 tristate "PM notifier error injection module" 1289 depends on PM && NOTIFIER_ERROR_INJECTION 1290 default m if PM_DEBUG 1291 help 1292 This option provides the ability to inject artificial errors to 1293 PM notifier chain callbacks. It is controlled through debugfs 1294 interface /sys/kernel/debug/notifier-error-inject/pm 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 PM suspend error (-12 = -ENOMEM) 1300 1301 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1302 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1303 # echo mem > /sys/power/state 1304 bash: echo: write error: Cannot allocate memory 1305 1306 To compile this code as a module, choose M here: the module will 1307 be called pm-notifier-error-inject. 1308 1309 If unsure, say N. 1310 1311config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1312 tristate "OF reconfig notifier error injection module" 1313 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1314 help 1315 This option provides the ability to inject artificial errors to 1316 OF reconfig notifier chain callbacks. It is controlled 1317 through debugfs interface under 1318 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 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 To compile this code as a module, choose M here: the module will 1324 be called of-reconfig-notifier-error-inject. 1325 1326 If unsure, say N. 1327 1328config FAULT_INJECTION 1329 bool "Fault-injection framework" 1330 depends on DEBUG_KERNEL 1331 help 1332 Provide fault-injection framework. 1333 For more details, see Documentation/fault-injection/. 1334 1335config FAILSLAB 1336 bool "Fault-injection capability for kmalloc" 1337 depends on FAULT_INJECTION 1338 depends on SLAB || SLUB 1339 help 1340 Provide fault-injection capability for kmalloc. 1341 1342config FAIL_PAGE_ALLOC 1343 bool "Fault-injection capabilitiy for alloc_pages()" 1344 depends on FAULT_INJECTION 1345 help 1346 Provide fault-injection capability for alloc_pages(). 1347 1348config FAIL_MAKE_REQUEST 1349 bool "Fault-injection capability for disk IO" 1350 depends on FAULT_INJECTION && BLOCK 1351 help 1352 Provide fault-injection capability for disk IO. 1353 1354config FAIL_IO_TIMEOUT 1355 bool "Fault-injection capability for faking disk interrupts" 1356 depends on FAULT_INJECTION && BLOCK 1357 help 1358 Provide fault-injection capability on end IO handling. This 1359 will make the block layer "forget" an interrupt as configured, 1360 thus exercising the error handling. 1361 1362 Only works with drivers that use the generic timeout handling, 1363 for others it wont do anything. 1364 1365config FAIL_MMC_REQUEST 1366 bool "Fault-injection capability for MMC IO" 1367 select DEBUG_FS 1368 depends on FAULT_INJECTION && MMC 1369 help 1370 Provide fault-injection capability for MMC IO. 1371 This will make the mmc core return data errors. This is 1372 useful to test the error handling in the mmc block device 1373 and to test how the mmc host driver handles retries from 1374 the block device. 1375 1376config FAULT_INJECTION_DEBUG_FS 1377 bool "Debugfs entries for fault-injection capabilities" 1378 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 1379 help 1380 Enable configuration of fault-injection capabilities via debugfs. 1381 1382config FAULT_INJECTION_STACKTRACE_FILTER 1383 bool "stacktrace filter for fault-injection capabilities" 1384 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 1385 depends on !X86_64 1386 select STACKTRACE 1387 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC 1388 help 1389 Provide stacktrace filter for fault-injection capabilities 1390 1391config LATENCYTOP 1392 bool "Latency measuring infrastructure" 1393 depends on HAVE_LATENCYTOP_SUPPORT 1394 depends on DEBUG_KERNEL 1395 depends on STACKTRACE_SUPPORT 1396 depends on PROC_FS 1397 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC 1398 select KALLSYMS 1399 select KALLSYMS_ALL 1400 select STACKTRACE 1401 select SCHEDSTATS 1402 select SCHED_DEBUG 1403 help 1404 Enable this option if you want to use the LatencyTOP tool 1405 to find out which userspace is blocking on what kernel operations. 1406 1407config ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS 1408 bool 1409 1410config DEBUG_STRICT_USER_COPY_CHECKS 1411 bool "Strict user copy size checks" 1412 depends on ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS 1413 depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING 1414 help 1415 Enabling this option turns a certain set of sanity checks for user 1416 copy operations into compile time failures. 1417 1418 The copy_from_user() etc checks are there to help test if there 1419 are sufficient security checks on the length argument of 1420 the copy operation, by having gcc prove that the argument is 1421 within bounds. 1422 1423 If unsure, say N. 1424 1425source kernel/trace/Kconfig 1426 1427menu "Runtime Testing" 1428 1429config LKDTM 1430 tristate "Linux Kernel Dump Test Tool Module" 1431 depends on DEBUG_FS 1432 depends on BLOCK 1433 default n 1434 help 1435 This module enables testing of the different dumping mechanisms by 1436 inducing system failures at predefined crash points. 1437 If you don't need it: say N 1438 Choose M here to compile this code as a module. The module will be 1439 called lkdtm. 1440 1441 Documentation on how to use the module can be found in 1442 Documentation/fault-injection/provoke-crashes.txt 1443 1444config TEST_LIST_SORT 1445 bool "Linked list sorting test" 1446 depends on DEBUG_KERNEL 1447 help 1448 Enable this to turn on 'list_sort()' function test. This test is 1449 executed only once during system boot, so affects only boot time. 1450 1451 If unsure, say N. 1452 1453config KPROBES_SANITY_TEST 1454 bool "Kprobes sanity tests" 1455 depends on DEBUG_KERNEL 1456 depends on KPROBES 1457 default n 1458 help 1459 This option provides for testing basic kprobes functionality on 1460 boot. A sample kprobe, jprobe and kretprobe are inserted and 1461 verified for functionality. 1462 1463 Say N if you are unsure. 1464 1465config BACKTRACE_SELF_TEST 1466 tristate "Self test for the backtrace code" 1467 depends on DEBUG_KERNEL 1468 default n 1469 help 1470 This option provides a kernel module that can be used to test 1471 the kernel stack backtrace code. This option is not useful 1472 for distributions or general kernels, but only for kernel 1473 developers working on architecture code. 1474 1475 Note that if you want to also test saved backtraces, you will 1476 have to enable STACKTRACE as well. 1477 1478 Say N if you are unsure. 1479 1480config RBTREE_TEST 1481 tristate "Red-Black tree test" 1482 depends on DEBUG_KERNEL 1483 help 1484 A benchmark measuring the performance of the rbtree library. 1485 Also includes rbtree invariant checks. 1486 1487config INTERVAL_TREE_TEST 1488 tristate "Interval tree test" 1489 depends on m && DEBUG_KERNEL 1490 help 1491 A benchmark measuring the performance of the interval tree library 1492 1493config PERCPU_TEST 1494 tristate "Per cpu operations test" 1495 depends on m && DEBUG_KERNEL 1496 help 1497 Enable this option to build test module which validates per-cpu 1498 operations. 1499 1500 If unsure, say N. 1501 1502config ATOMIC64_SELFTEST 1503 bool "Perform an atomic64_t self-test at boot" 1504 help 1505 Enable this option to test the atomic64_t functions at boot. 1506 1507 If unsure, say N. 1508 1509config ASYNC_RAID6_TEST 1510 tristate "Self test for hardware accelerated raid6 recovery" 1511 depends on ASYNC_RAID6_RECOV 1512 select ASYNC_MEMCPY 1513 ---help--- 1514 This is a one-shot self test that permutes through the 1515 recovery of all the possible two disk failure scenarios for a 1516 N-disk array. Recovery is performed with the asynchronous 1517 raid6 recovery routines, and will optionally use an offload 1518 engine if one is available. 1519 1520 If unsure, say N. 1521 1522config TEST_STRING_HELPERS 1523 tristate "Test functions located in the string_helpers module at runtime" 1524 1525config TEST_KSTRTOX 1526 tristate "Test kstrto*() family of functions at runtime" 1527 1528endmenu # runtime tests 1529 1530config PROVIDE_OHCI1394_DMA_INIT 1531 bool "Remote debugging over FireWire early on boot" 1532 depends on PCI && X86 1533 help 1534 If you want to debug problems which hang or crash the kernel early 1535 on boot and the crashing machine has a FireWire port, you can use 1536 this feature to remotely access the memory of the crashed machine 1537 over FireWire. This employs remote DMA as part of the OHCI1394 1538 specification which is now the standard for FireWire controllers. 1539 1540 With remote DMA, you can monitor the printk buffer remotely using 1541 firescope and access all memory below 4GB using fireproxy from gdb. 1542 Even controlling a kernel debugger is possible using remote DMA. 1543 1544 Usage: 1545 1546 If ohci1394_dma=early is used as boot parameter, it will initialize 1547 all OHCI1394 controllers which are found in the PCI config space. 1548 1549 As all changes to the FireWire bus such as enabling and disabling 1550 devices cause a bus reset and thereby disable remote DMA for all 1551 devices, be sure to have the cable plugged and FireWire enabled on 1552 the debugging host before booting the debug target for debugging. 1553 1554 This code (~1k) is freed after boot. By then, the firewire stack 1555 in charge of the OHCI-1394 controllers should be used instead. 1556 1557 See Documentation/debugging-via-ohci1394.txt for more information. 1558 1559config BUILD_DOCSRC 1560 bool "Build targets in Documentation/ tree" 1561 depends on HEADERS_CHECK 1562 help 1563 This option attempts to build objects from the source files in the 1564 kernel Documentation/ tree. 1565 1566 Say N if you are unsure. 1567 1568config DMA_API_DEBUG 1569 bool "Enable debugging of DMA-API usage" 1570 depends on HAVE_DMA_API_DEBUG 1571 help 1572 Enable this option to debug the use of the DMA API by device drivers. 1573 With this option you will be able to detect common bugs in device 1574 drivers like double-freeing of DMA mappings or freeing mappings that 1575 were never allocated. 1576 1577 This also attempts to catch cases where a page owned by DMA is 1578 accessed by the cpu in a way that could cause data corruption. For 1579 example, this enables cow_user_page() to check that the source page is 1580 not undergoing DMA. 1581 1582 This option causes a performance degradation. Use only if you want to 1583 debug device drivers and dma interactions. 1584 1585 If unsure, say N. 1586 1587config TEST_MODULE 1588 tristate "Test module loading with 'hello world' module" 1589 default n 1590 depends on m 1591 help 1592 This builds the "test_module" module that emits "Hello, world" 1593 on printk when loaded. It is designed to be used for basic 1594 evaluation of the module loading subsystem (for example when 1595 validating module verification). It lacks any extra dependencies, 1596 and will not normally be loaded by the system unless explicitly 1597 requested by name. 1598 1599 If unsure, say N. 1600 1601config TEST_USER_COPY 1602 tristate "Test user/kernel boundary protections" 1603 default n 1604 depends on m 1605 help 1606 This builds the "test_user_copy" module that runs sanity checks 1607 on the copy_to/from_user infrastructure, making sure basic 1608 user/kernel boundary testing is working. If it fails to load, 1609 a regression has been detected in the user/kernel memory boundary 1610 protections. 1611 1612 If unsure, say N. 1613 1614source "samples/Kconfig" 1615 1616source "lib/Kconfig.kgdb" 1617 1618