1 2config PRINTK_TIME 3 bool "Show timing information on printks" 4 depends on PRINTK 5 help 6 Selecting this option causes time stamps of the printk() 7 messages to be added to the output of the syslog() system 8 call and at the console. 9 10 The timestamp is always recorded internally, and exported 11 to /dev/kmsg. This flag just specifies if the timestamp should 12 be included, not that the timestamp is recorded. 13 14 The behavior is also controlled by the kernel command line 15 parameter printk.time=1. See Documentation/kernel-parameters.txt 16 17config DEFAULT_MESSAGE_LOGLEVEL 18 int "Default message log level (1-7)" 19 range 1 7 20 default "4" 21 help 22 Default log level for printk statements with no specified priority. 23 24 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks 25 that are auditing their logs closely may want to set it to a lower 26 priority. 27 28config ENABLE_WARN_DEPRECATED 29 bool "Enable __deprecated logic" 30 default y 31 help 32 Enable the __deprecated logic in the kernel build. 33 Disable this to suppress the "warning: 'foo' is deprecated 34 (declared at kernel/power/somefile.c:1234)" messages. 35 36config ENABLE_MUST_CHECK 37 bool "Enable __must_check logic" 38 default y 39 help 40 Enable the __must_check logic in the kernel build. Disable this to 41 suppress the "warning: ignoring return value of 'foo', declared with 42 attribute warn_unused_result" messages. 43 44config FRAME_WARN 45 int "Warn for stack frames larger than (needs gcc 4.4)" 46 range 0 8192 47 default 1024 if !64BIT 48 default 2048 if 64BIT 49 help 50 Tell gcc to warn at build time for stack frames larger than this. 51 Setting this too low will cause a lot of warnings. 52 Setting it to 0 disables the warning. 53 Requires gcc 4.4 54 55config MAGIC_SYSRQ 56 bool "Magic SysRq key" 57 depends on !UML 58 help 59 If you say Y here, you will have some control over the system even 60 if the system crashes for example during kernel debugging (e.g., you 61 will be able to flush the buffer cache to disk, reboot the system 62 immediately or dump some status information). This is accomplished 63 by pressing various keys while holding SysRq (Alt+PrintScreen). It 64 also works on a serial console (on PC hardware at least), if you 65 send a BREAK and then within 5 seconds a command keypress. The 66 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y 67 unless you really know what this hack does. 68 69config STRIP_ASM_SYMS 70 bool "Strip assembler-generated symbols during link" 71 default n 72 help 73 Strip internal assembler-generated symbols during a link (symbols 74 that look like '.Lxxx') so they don't pollute the output of 75 get_wchan() and suchlike. 76 77config READABLE_ASM 78 bool "Generate readable assembler code" 79 depends on DEBUG_KERNEL 80 help 81 Disable some compiler optimizations that tend to generate human unreadable 82 assembler output. This may make the kernel slightly slower, but it helps 83 to keep kernel developers who have to stare a lot at assembler listings 84 sane. 85 86config UNUSED_SYMBOLS 87 bool "Enable unused/obsolete exported symbols" 88 default y if X86 89 help 90 Unused but exported symbols make the kernel needlessly bigger. For 91 that reason most of these unused exports will soon be removed. This 92 option is provided temporarily to provide a transition period in case 93 some external kernel module needs one of these symbols anyway. If you 94 encounter such a case in your module, consider if you are actually 95 using the right API. (rationale: since nobody in the kernel is using 96 this in a module, there is a pretty good chance it's actually the 97 wrong interface to use). If you really need the symbol, please send a 98 mail to the linux kernel mailing list mentioning the symbol and why 99 you really need it, and what the merge plan to the mainline kernel for 100 your module is. 101 102config DEBUG_FS 103 bool "Debug Filesystem" 104 help 105 debugfs is a virtual file system that kernel developers use to put 106 debugging files into. Enable this option to be able to read and 107 write to these files. 108 109 For detailed documentation on the debugfs API, see 110 Documentation/DocBook/filesystems. 111 112 If unsure, say N. 113 114config HEADERS_CHECK 115 bool "Run 'make headers_check' when building vmlinux" 116 depends on !UML 117 help 118 This option will extract the user-visible kernel headers whenever 119 building the kernel, and will run basic sanity checks on them to 120 ensure that exported files do not attempt to include files which 121 were not exported, etc. 122 123 If you're making modifications to header files which are 124 relevant for userspace, say 'Y', and check the headers 125 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in 126 your build tree), to make sure they're suitable. 127 128config DEBUG_SECTION_MISMATCH 129 bool "Enable full Section mismatch analysis" 130 help 131 The section mismatch analysis checks if there are illegal 132 references from one section to another section. 133 During linktime or runtime, some sections are dropped; 134 any use of code/data previously in these sections would 135 most likely result in an oops. 136 In the code, functions and variables are annotated with 137 __init, __devinit, etc. (see the full list in include/linux/init.h), 138 which results in the code/data being placed in specific sections. 139 The section mismatch analysis is always performed after a full 140 kernel build, and enabling this option causes the following 141 additional steps to occur: 142 - Add the option -fno-inline-functions-called-once to gcc commands. 143 When inlining a function annotated with __init in a non-init 144 function, we would lose the section information and thus 145 the analysis would not catch the illegal reference. 146 This option tells gcc to inline less (but it does result in 147 a larger kernel). 148 - Run the section mismatch analysis for each module/built-in.o file. 149 When we run the section mismatch analysis on vmlinux.o, we 150 lose valueble information about where the mismatch was 151 introduced. 152 Running the analysis for each module/built-in.o file 153 tells where the mismatch happens much closer to the 154 source. The drawback is that the same mismatch is 155 reported at least twice. 156 - Enable verbose reporting from modpost in order to help resolve 157 the section mismatches that are reported. 158 159config DEBUG_KERNEL 160 bool "Kernel debugging" 161 help 162 Say Y here if you are developing drivers or trying to debug and 163 identify kernel problems. 164 165config DEBUG_SHIRQ 166 bool "Debug shared IRQ handlers" 167 depends on DEBUG_KERNEL && GENERIC_HARDIRQS 168 help 169 Enable this to generate a spurious interrupt as soon as a shared 170 interrupt handler is registered, and just before one is deregistered. 171 Drivers ought to be able to handle interrupts coming in at those 172 points; some don't and need to be caught. 173 174config LOCKUP_DETECTOR 175 bool "Detect Hard and Soft Lockups" 176 depends on DEBUG_KERNEL && !S390 177 help 178 Say Y here to enable the kernel to act as a watchdog to detect 179 hard and soft lockups. 180 181 Softlockups are bugs that cause the kernel to loop in kernel 182 mode for more than 20 seconds, without giving other tasks a 183 chance to run. The current stack trace is displayed upon 184 detection and the system will stay locked up. 185 186 Hardlockups are bugs that cause the CPU to loop in kernel mode 187 for more than 10 seconds, without letting other interrupts have a 188 chance to run. The current stack trace is displayed upon detection 189 and the system will stay locked up. 190 191 The overhead should be minimal. A periodic hrtimer runs to 192 generate interrupts and kick the watchdog task every 4 seconds. 193 An NMI is generated every 10 seconds or so to check for hardlockups. 194 195 The frequency of hrtimer and NMI events and the soft and hard lockup 196 thresholds can be controlled through the sysctl watchdog_thresh. 197 198config HARDLOCKUP_DETECTOR 199 def_bool LOCKUP_DETECTOR && PERF_EVENTS && HAVE_PERF_EVENTS_NMI && \ 200 !HAVE_NMI_WATCHDOG 201 202config BOOTPARAM_HARDLOCKUP_PANIC 203 bool "Panic (Reboot) On Hard Lockups" 204 depends on LOCKUP_DETECTOR 205 help 206 Say Y here to enable the kernel to panic on "hard lockups", 207 which are bugs that cause the kernel to loop in kernel 208 mode with interrupts disabled for more than 10 seconds (configurable 209 using the watchdog_thresh sysctl). 210 211 Say N if unsure. 212 213config BOOTPARAM_HARDLOCKUP_PANIC_VALUE 214 int 215 depends on LOCKUP_DETECTOR 216 range 0 1 217 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC 218 default 1 if BOOTPARAM_HARDLOCKUP_PANIC 219 220config BOOTPARAM_SOFTLOCKUP_PANIC 221 bool "Panic (Reboot) On Soft Lockups" 222 depends on LOCKUP_DETECTOR 223 help 224 Say Y here to enable the kernel to panic on "soft lockups", 225 which are bugs that cause the kernel to loop in kernel 226 mode for more than 20 seconds (configurable using the watchdog_thresh 227 sysctl), without giving other tasks a chance to run. 228 229 The panic can be used in combination with panic_timeout, 230 to cause the system to reboot automatically after a 231 lockup has been detected. This feature is useful for 232 high-availability systems that have uptime guarantees and 233 where a lockup must be resolved ASAP. 234 235 Say N if unsure. 236 237config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE 238 int 239 depends on LOCKUP_DETECTOR 240 range 0 1 241 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC 242 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC 243 244config PANIC_ON_OOPS 245 bool "Panic on Oops" if EXPERT 246 default n 247 help 248 Say Y here to enable the kernel to panic when it oopses. This 249 has the same effect as setting oops=panic on the kernel command 250 line. 251 252 This feature is useful to ensure that the kernel does not do 253 anything erroneous after an oops which could result in data 254 corruption or other issues. 255 256 Say N if unsure. 257 258config PANIC_ON_OOPS_VALUE 259 int 260 range 0 1 261 default 0 if !PANIC_ON_OOPS 262 default 1 if PANIC_ON_OOPS 263 264config DETECT_HUNG_TASK 265 bool "Detect Hung Tasks" 266 depends on DEBUG_KERNEL 267 default LOCKUP_DETECTOR 268 help 269 Say Y here to enable the kernel to detect "hung tasks", 270 which are bugs that cause the task to be stuck in 271 uninterruptible "D" state indefinitiley. 272 273 When a hung task is detected, the kernel will print the 274 current stack trace (which you should report), but the 275 task will stay in uninterruptible state. If lockdep is 276 enabled then all held locks will also be reported. This 277 feature has negligible overhead. 278 279config DEFAULT_HUNG_TASK_TIMEOUT 280 int "Default timeout for hung task detection (in seconds)" 281 depends on DETECT_HUNG_TASK 282 default 120 283 help 284 This option controls the default timeout (in seconds) used 285 to determine when a task has become non-responsive and should 286 be considered hung. 287 288 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 289 sysctl or by writing a value to 290 /proc/sys/kernel/hung_task_timeout_secs. 291 292 A timeout of 0 disables the check. The default is two minutes. 293 Keeping the default should be fine in most cases. 294 295config BOOTPARAM_HUNG_TASK_PANIC 296 bool "Panic (Reboot) On Hung Tasks" 297 depends on DETECT_HUNG_TASK 298 help 299 Say Y here to enable the kernel to panic on "hung tasks", 300 which are bugs that cause the kernel to leave a task stuck 301 in uninterruptible "D" state. 302 303 The panic can be used in combination with panic_timeout, 304 to cause the system to reboot automatically after a 305 hung task has been detected. This feature is useful for 306 high-availability systems that have uptime guarantees and 307 where a hung tasks must be resolved ASAP. 308 309 Say N if unsure. 310 311config BOOTPARAM_HUNG_TASK_PANIC_VALUE 312 int 313 depends on DETECT_HUNG_TASK 314 range 0 1 315 default 0 if !BOOTPARAM_HUNG_TASK_PANIC 316 default 1 if BOOTPARAM_HUNG_TASK_PANIC 317 318config SCHED_DEBUG 319 bool "Collect scheduler debugging info" 320 depends on DEBUG_KERNEL && PROC_FS 321 default y 322 help 323 If you say Y here, the /proc/sched_debug file will be provided 324 that can help debug the scheduler. The runtime overhead of this 325 option is minimal. 326 327config SCHEDSTATS 328 bool "Collect scheduler statistics" 329 depends on DEBUG_KERNEL && PROC_FS 330 help 331 If you say Y here, additional code will be inserted into the 332 scheduler and related routines to collect statistics about 333 scheduler behavior and provide them in /proc/schedstat. These 334 stats may be useful for both tuning and debugging the scheduler 335 If you aren't debugging the scheduler or trying to tune a specific 336 application, you can say N to avoid the very slight overhead 337 this adds. 338 339config TIMER_STATS 340 bool "Collect kernel timers statistics" 341 depends on DEBUG_KERNEL && PROC_FS 342 help 343 If you say Y here, additional code will be inserted into the 344 timer routines to collect statistics about kernel timers being 345 reprogrammed. The statistics can be read from /proc/timer_stats. 346 The statistics collection is started by writing 1 to /proc/timer_stats, 347 writing 0 stops it. This feature is useful to collect information 348 about timer usage patterns in kernel and userspace. This feature 349 is lightweight if enabled in the kernel config but not activated 350 (it defaults to deactivated on bootup and will only be activated 351 if some application like powertop activates it explicitly). 352 353config DEBUG_OBJECTS 354 bool "Debug object operations" 355 depends on DEBUG_KERNEL 356 help 357 If you say Y here, additional code will be inserted into the 358 kernel to track the life time of various objects and validate 359 the operations on those objects. 360 361config DEBUG_OBJECTS_SELFTEST 362 bool "Debug objects selftest" 363 depends on DEBUG_OBJECTS 364 help 365 This enables the selftest of the object debug code. 366 367config DEBUG_OBJECTS_FREE 368 bool "Debug objects in freed memory" 369 depends on DEBUG_OBJECTS 370 help 371 This enables checks whether a k/v free operation frees an area 372 which contains an object which has not been deactivated 373 properly. This can make kmalloc/kfree-intensive workloads 374 much slower. 375 376config DEBUG_OBJECTS_TIMERS 377 bool "Debug timer objects" 378 depends on DEBUG_OBJECTS 379 help 380 If you say Y here, additional code will be inserted into the 381 timer routines to track the life time of timer objects and 382 validate the timer operations. 383 384config DEBUG_OBJECTS_WORK 385 bool "Debug work objects" 386 depends on DEBUG_OBJECTS 387 help 388 If you say Y here, additional code will be inserted into the 389 work queue routines to track the life time of work objects and 390 validate the work operations. 391 392config DEBUG_OBJECTS_RCU_HEAD 393 bool "Debug RCU callbacks objects" 394 depends on DEBUG_OBJECTS 395 help 396 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 397 398config DEBUG_OBJECTS_PERCPU_COUNTER 399 bool "Debug percpu counter objects" 400 depends on DEBUG_OBJECTS 401 help 402 If you say Y here, additional code will be inserted into the 403 percpu counter routines to track the life time of percpu counter 404 objects and validate the percpu counter operations. 405 406config DEBUG_OBJECTS_ENABLE_DEFAULT 407 int "debug_objects bootup default value (0-1)" 408 range 0 1 409 default "1" 410 depends on DEBUG_OBJECTS 411 help 412 Debug objects boot parameter default value 413 414config DEBUG_SLAB 415 bool "Debug slab memory allocations" 416 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK 417 help 418 Say Y here to have the kernel do limited verification on memory 419 allocation as well as poisoning memory on free to catch use of freed 420 memory. This can make kmalloc/kfree-intensive workloads much slower. 421 422config DEBUG_SLAB_LEAK 423 bool "Memory leak debugging" 424 depends on DEBUG_SLAB 425 426config SLUB_DEBUG_ON 427 bool "SLUB debugging on by default" 428 depends on SLUB && SLUB_DEBUG && !KMEMCHECK 429 default n 430 help 431 Boot with debugging on by default. SLUB boots by default with 432 the runtime debug capabilities switched off. Enabling this is 433 equivalent to specifying the "slub_debug" parameter on boot. 434 There is no support for more fine grained debug control like 435 possible with slub_debug=xxx. SLUB debugging may be switched 436 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying 437 "slub_debug=-". 438 439config SLUB_STATS 440 default n 441 bool "Enable SLUB performance statistics" 442 depends on SLUB && SYSFS 443 help 444 SLUB statistics are useful to debug SLUBs allocation behavior in 445 order find ways to optimize the allocator. This should never be 446 enabled for production use since keeping statistics slows down 447 the allocator by a few percentage points. The slabinfo command 448 supports the determination of the most active slabs to figure 449 out which slabs are relevant to a particular load. 450 Try running: slabinfo -DA 451 452config DEBUG_KMEMLEAK 453 bool "Kernel memory leak detector" 454 depends on DEBUG_KERNEL && EXPERIMENTAL && \ 455 (X86 || ARM || PPC || MIPS || S390 || SPARC64 || SUPERH || MICROBLAZE || TILE) 456 457 select DEBUG_FS 458 select STACKTRACE if STACKTRACE_SUPPORT 459 select KALLSYMS 460 select CRC32 461 help 462 Say Y here if you want to enable the memory leak 463 detector. The memory allocation/freeing is traced in a way 464 similar to the Boehm's conservative garbage collector, the 465 difference being that the orphan objects are not freed but 466 only shown in /sys/kernel/debug/kmemleak. Enabling this 467 feature will introduce an overhead to memory 468 allocations. See Documentation/kmemleak.txt for more 469 details. 470 471 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances 472 of finding leaks due to the slab objects poisoning. 473 474 In order to access the kmemleak file, debugfs needs to be 475 mounted (usually at /sys/kernel/debug). 476 477config DEBUG_KMEMLEAK_EARLY_LOG_SIZE 478 int "Maximum kmemleak early log entries" 479 depends on DEBUG_KMEMLEAK 480 range 200 40000 481 default 400 482 help 483 Kmemleak must track all the memory allocations to avoid 484 reporting false positives. Since memory may be allocated or 485 freed before kmemleak is initialised, an early log buffer is 486 used to store these actions. If kmemleak reports "early log 487 buffer exceeded", please increase this value. 488 489config DEBUG_KMEMLEAK_TEST 490 tristate "Simple test for the kernel memory leak detector" 491 depends on DEBUG_KMEMLEAK && m 492 help 493 This option enables a module that explicitly leaks memory. 494 495 If unsure, say N. 496 497config DEBUG_KMEMLEAK_DEFAULT_OFF 498 bool "Default kmemleak to off" 499 depends on DEBUG_KMEMLEAK 500 help 501 Say Y here to disable kmemleak by default. It can then be enabled 502 on the command line via kmemleak=on. 503 504config DEBUG_PREEMPT 505 bool "Debug preemptible kernel" 506 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT 507 default y 508 help 509 If you say Y here then the kernel will use a debug variant of the 510 commonly used smp_processor_id() function and will print warnings 511 if kernel code uses it in a preemption-unsafe way. Also, the kernel 512 will detect preemption count underflows. 513 514config DEBUG_RT_MUTEXES 515 bool "RT Mutex debugging, deadlock detection" 516 depends on DEBUG_KERNEL && RT_MUTEXES 517 help 518 This allows rt mutex semantics violations and rt mutex related 519 deadlocks (lockups) to be detected and reported automatically. 520 521config DEBUG_PI_LIST 522 bool 523 default y 524 depends on DEBUG_RT_MUTEXES 525 526config RT_MUTEX_TESTER 527 bool "Built-in scriptable tester for rt-mutexes" 528 depends on DEBUG_KERNEL && RT_MUTEXES 529 help 530 This option enables a rt-mutex tester. 531 532config DEBUG_SPINLOCK 533 bool "Spinlock and rw-lock debugging: basic checks" 534 depends on DEBUG_KERNEL 535 select UNINLINE_SPIN_UNLOCK 536 help 537 Say Y here and build SMP to catch missing spinlock initialization 538 and certain other kinds of spinlock errors commonly made. This is 539 best used in conjunction with the NMI watchdog so that spinlock 540 deadlocks are also debuggable. 541 542config DEBUG_MUTEXES 543 bool "Mutex debugging: basic checks" 544 depends on DEBUG_KERNEL 545 help 546 This feature allows mutex semantics violations to be detected and 547 reported. 548 549config DEBUG_LOCK_ALLOC 550 bool "Lock debugging: detect incorrect freeing of live locks" 551 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 552 select DEBUG_SPINLOCK 553 select DEBUG_MUTEXES 554 select LOCKDEP 555 help 556 This feature will check whether any held lock (spinlock, rwlock, 557 mutex or rwsem) is incorrectly freed by the kernel, via any of the 558 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 559 vfree(), etc.), whether a live lock is incorrectly reinitialized via 560 spin_lock_init()/mutex_init()/etc., or whether there is any lock 561 held during task exit. 562 563config PROVE_LOCKING 564 bool "Lock debugging: prove locking correctness" 565 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 566 select LOCKDEP 567 select DEBUG_SPINLOCK 568 select DEBUG_MUTEXES 569 select DEBUG_LOCK_ALLOC 570 select TRACE_IRQFLAGS 571 default n 572 help 573 This feature enables the kernel to prove that all locking 574 that occurs in the kernel runtime is mathematically 575 correct: that under no circumstance could an arbitrary (and 576 not yet triggered) combination of observed locking 577 sequences (on an arbitrary number of CPUs, running an 578 arbitrary number of tasks and interrupt contexts) cause a 579 deadlock. 580 581 In short, this feature enables the kernel to report locking 582 related deadlocks before they actually occur. 583 584 The proof does not depend on how hard and complex a 585 deadlock scenario would be to trigger: how many 586 participant CPUs, tasks and irq-contexts would be needed 587 for it to trigger. The proof also does not depend on 588 timing: if a race and a resulting deadlock is possible 589 theoretically (no matter how unlikely the race scenario 590 is), it will be proven so and will immediately be 591 reported by the kernel (once the event is observed that 592 makes the deadlock theoretically possible). 593 594 If a deadlock is impossible (i.e. the locking rules, as 595 observed by the kernel, are mathematically correct), the 596 kernel reports nothing. 597 598 NOTE: this feature can also be enabled for rwlocks, mutexes 599 and rwsems - in which case all dependencies between these 600 different locking variants are observed and mapped too, and 601 the proof of observed correctness is also maintained for an 602 arbitrary combination of these separate locking variants. 603 604 For more details, see Documentation/lockdep-design.txt. 605 606config PROVE_RCU 607 bool "RCU debugging: prove RCU correctness" 608 depends on PROVE_LOCKING 609 default n 610 help 611 This feature enables lockdep extensions that check for correct 612 use of RCU APIs. This is currently under development. Say Y 613 if you want to debug RCU usage or help work on the PROVE_RCU 614 feature. 615 616 Say N if you are unsure. 617 618config PROVE_RCU_REPEATEDLY 619 bool "RCU debugging: don't disable PROVE_RCU on first splat" 620 depends on PROVE_RCU 621 default n 622 help 623 By itself, PROVE_RCU will disable checking upon issuing the 624 first warning (or "splat"). This feature prevents such 625 disabling, allowing multiple RCU-lockdep warnings to be printed 626 on a single reboot. 627 628 Say Y to allow multiple RCU-lockdep warnings per boot. 629 630 Say N if you are unsure. 631 632config SPARSE_RCU_POINTER 633 bool "RCU debugging: sparse-based checks for pointer usage" 634 default n 635 help 636 This feature enables the __rcu sparse annotation for 637 RCU-protected pointers. This annotation will cause sparse 638 to flag any non-RCU used of annotated pointers. This can be 639 helpful when debugging RCU usage. Please note that this feature 640 is not intended to enforce code cleanliness; it is instead merely 641 a debugging aid. 642 643 Say Y to make sparse flag questionable use of RCU-protected pointers 644 645 Say N if you are unsure. 646 647config LOCKDEP 648 bool 649 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 650 select STACKTRACE 651 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE 652 select KALLSYMS 653 select KALLSYMS_ALL 654 655config LOCK_STAT 656 bool "Lock usage statistics" 657 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 658 select LOCKDEP 659 select DEBUG_SPINLOCK 660 select DEBUG_MUTEXES 661 select DEBUG_LOCK_ALLOC 662 default n 663 help 664 This feature enables tracking lock contention points 665 666 For more details, see Documentation/lockstat.txt 667 668 This also enables lock events required by "perf lock", 669 subcommand of perf. 670 If you want to use "perf lock", you also need to turn on 671 CONFIG_EVENT_TRACING. 672 673 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 674 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 675 676config DEBUG_LOCKDEP 677 bool "Lock dependency engine debugging" 678 depends on DEBUG_KERNEL && LOCKDEP 679 help 680 If you say Y here, the lock dependency engine will do 681 additional runtime checks to debug itself, at the price 682 of more runtime overhead. 683 684config TRACE_IRQFLAGS 685 bool 686 help 687 Enables hooks to interrupt enabling and disabling for 688 either tracing or lock debugging. 689 690config DEBUG_ATOMIC_SLEEP 691 bool "Sleep inside atomic section checking" 692 select PREEMPT_COUNT 693 depends on DEBUG_KERNEL 694 help 695 If you say Y here, various routines which may sleep will become very 696 noisy if they are called inside atomic sections: when a spinlock is 697 held, inside an rcu read side critical section, inside preempt disabled 698 sections, inside an interrupt, etc... 699 700config DEBUG_LOCKING_API_SELFTESTS 701 bool "Locking API boot-time self-tests" 702 depends on DEBUG_KERNEL 703 help 704 Say Y here if you want the kernel to run a short self-test during 705 bootup. The self-test checks whether common types of locking bugs 706 are detected by debugging mechanisms or not. (if you disable 707 lock debugging then those bugs wont be detected of course.) 708 The following locking APIs are covered: spinlocks, rwlocks, 709 mutexes and rwsems. 710 711config STACKTRACE 712 bool 713 depends on STACKTRACE_SUPPORT 714 715config DEBUG_STACK_USAGE 716 bool "Stack utilization instrumentation" 717 depends on DEBUG_KERNEL && !IA64 && !PARISC 718 help 719 Enables the display of the minimum amount of free stack which each 720 task has ever had available in the sysrq-T and sysrq-P debug output. 721 722 This option will slow down process creation somewhat. 723 724config DEBUG_KOBJECT 725 bool "kobject debugging" 726 depends on DEBUG_KERNEL 727 help 728 If you say Y here, some extra kobject debugging messages will be sent 729 to the syslog. 730 731config DEBUG_HIGHMEM 732 bool "Highmem debugging" 733 depends on DEBUG_KERNEL && HIGHMEM 734 help 735 This options enables addition error checking for high memory systems. 736 Disable for production systems. 737 738config DEBUG_BUGVERBOSE 739 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT 740 depends on BUG 741 depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \ 742 FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300 || TILE 743 default y 744 help 745 Say Y here to make BUG() panics output the file name and line number 746 of the BUG call as well as the EIP and oops trace. This aids 747 debugging but costs about 70-100K of memory. 748 749config DEBUG_INFO 750 bool "Compile the kernel with debug info" 751 depends on DEBUG_KERNEL 752 help 753 If you say Y here the resulting kernel image will include 754 debugging info resulting in a larger kernel image. 755 This adds debug symbols to the kernel and modules (gcc -g), and 756 is needed if you intend to use kernel crashdump or binary object 757 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 758 Say Y here only if you plan to debug the kernel. 759 760 If unsure, say N. 761 762config DEBUG_INFO_REDUCED 763 bool "Reduce debugging information" 764 depends on DEBUG_INFO 765 help 766 If you say Y here gcc is instructed to generate less debugging 767 information for structure types. This means that tools that 768 need full debugging information (like kgdb or systemtap) won't 769 be happy. But if you merely need debugging information to 770 resolve line numbers there is no loss. Advantage is that 771 build directory object sizes shrink dramatically over a full 772 DEBUG_INFO build and compile times are reduced too. 773 Only works with newer gcc versions. 774 775config DEBUG_VM 776 bool "Debug VM" 777 depends on DEBUG_KERNEL 778 help 779 Enable this to turn on extended checks in the virtual-memory system 780 that may impact performance. 781 782 If unsure, say N. 783 784config DEBUG_VIRTUAL 785 bool "Debug VM translations" 786 depends on DEBUG_KERNEL && X86 787 help 788 Enable some costly sanity checks in virtual to page code. This can 789 catch mistakes with virt_to_page() and friends. 790 791 If unsure, say N. 792 793config DEBUG_NOMMU_REGIONS 794 bool "Debug the global anon/private NOMMU mapping region tree" 795 depends on DEBUG_KERNEL && !MMU 796 help 797 This option causes the global tree of anonymous and private mapping 798 regions to be regularly checked for invalid topology. 799 800config DEBUG_WRITECOUNT 801 bool "Debug filesystem writers count" 802 depends on DEBUG_KERNEL 803 help 804 Enable this to catch wrong use of the writers count in struct 805 vfsmount. This will increase the size of each file struct by 806 32 bits. 807 808 If unsure, say N. 809 810config DEBUG_MEMORY_INIT 811 bool "Debug memory initialisation" if EXPERT 812 default !EXPERT 813 help 814 Enable this for additional checks during memory initialisation. 815 The sanity checks verify aspects of the VM such as the memory model 816 and other information provided by the architecture. Verbose 817 information will be printed at KERN_DEBUG loglevel depending 818 on the mminit_loglevel= command-line option. 819 820 If unsure, say Y 821 822config DEBUG_LIST 823 bool "Debug linked list manipulation" 824 depends on DEBUG_KERNEL 825 help 826 Enable this to turn on extended checks in the linked-list 827 walking routines. 828 829 If unsure, say N. 830 831config TEST_LIST_SORT 832 bool "Linked list sorting test" 833 depends on DEBUG_KERNEL 834 help 835 Enable this to turn on 'list_sort()' function test. This test is 836 executed only once during system boot, so affects only boot time. 837 838 If unsure, say N. 839 840config DEBUG_SG 841 bool "Debug SG table operations" 842 depends on DEBUG_KERNEL 843 help 844 Enable this to turn on checks on scatter-gather tables. This can 845 help find problems with drivers that do not properly initialize 846 their sg tables. 847 848 If unsure, say N. 849 850config DEBUG_NOTIFIERS 851 bool "Debug notifier call chains" 852 depends on DEBUG_KERNEL 853 help 854 Enable this to turn on sanity checking for notifier call chains. 855 This is most useful for kernel developers to make sure that 856 modules properly unregister themselves from notifier chains. 857 This is a relatively cheap check but if you care about maximum 858 performance, say N. 859 860config DEBUG_CREDENTIALS 861 bool "Debug credential management" 862 depends on DEBUG_KERNEL 863 help 864 Enable this to turn on some debug checking for credential 865 management. The additional code keeps track of the number of 866 pointers from task_structs to any given cred struct, and checks to 867 see that this number never exceeds the usage count of the cred 868 struct. 869 870 Furthermore, if SELinux is enabled, this also checks that the 871 security pointer in the cred struct is never seen to be invalid. 872 873 If unsure, say N. 874 875# 876# Select this config option from the architecture Kconfig, if it 877# is preferred to always offer frame pointers as a config 878# option on the architecture (regardless of KERNEL_DEBUG): 879# 880config ARCH_WANT_FRAME_POINTERS 881 bool 882 help 883 884config FRAME_POINTER 885 bool "Compile the kernel with frame pointers" 886 depends on DEBUG_KERNEL && \ 887 (CRIS || M68K || FRV || UML || \ 888 AVR32 || SUPERH || BLACKFIN || MN10300) || \ 889 ARCH_WANT_FRAME_POINTERS 890 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 891 help 892 If you say Y here the resulting kernel image will be slightly 893 larger and slower, but it gives very useful debugging information 894 in case of kernel bugs. (precise oopses/stacktraces/warnings) 895 896config BOOT_PRINTK_DELAY 897 bool "Delay each boot printk message by N milliseconds" 898 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY 899 help 900 This build option allows you to read kernel boot messages 901 by inserting a short delay after each one. The delay is 902 specified in milliseconds on the kernel command line, 903 using "boot_delay=N". 904 905 It is likely that you would also need to use "lpj=M" to preset 906 the "loops per jiffie" value. 907 See a previous boot log for the "lpj" value to use for your 908 system, and then set "lpj=M" before setting "boot_delay=N". 909 NOTE: Using this option may adversely affect SMP systems. 910 I.e., processors other than the first one may not boot up. 911 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect 912 what it believes to be lockup conditions. 913 914config RCU_TORTURE_TEST 915 tristate "torture tests for RCU" 916 depends on DEBUG_KERNEL 917 default n 918 help 919 This option provides a kernel module that runs torture tests 920 on the RCU infrastructure. The kernel module may be built 921 after the fact on the running kernel to be tested, if desired. 922 923 Say Y here if you want RCU torture tests to be built into 924 the kernel. 925 Say M if you want the RCU torture tests to build as a module. 926 Say N if you are unsure. 927 928config RCU_TORTURE_TEST_RUNNABLE 929 bool "torture tests for RCU runnable by default" 930 depends on RCU_TORTURE_TEST = y 931 default n 932 help 933 This option provides a way to build the RCU torture tests 934 directly into the kernel without them starting up at boot 935 time. You can use /proc/sys/kernel/rcutorture_runnable 936 to manually override this setting. This /proc file is 937 available only when the RCU torture tests have been built 938 into the kernel. 939 940 Say Y here if you want the RCU torture tests to start during 941 boot (you probably don't). 942 Say N here if you want the RCU torture tests to start only 943 after being manually enabled via /proc. 944 945config RCU_CPU_STALL_TIMEOUT 946 int "RCU CPU stall timeout in seconds" 947 depends on TREE_RCU || TREE_PREEMPT_RCU 948 range 3 300 949 default 60 950 help 951 If a given RCU grace period extends more than the specified 952 number of seconds, a CPU stall warning is printed. If the 953 RCU grace period persists, additional CPU stall warnings are 954 printed at more widely spaced intervals. 955 956config RCU_CPU_STALL_VERBOSE 957 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR" 958 depends on TREE_PREEMPT_RCU 959 default y 960 help 961 This option causes RCU to printk detailed per-task information 962 for any tasks that are stalling the current RCU grace period. 963 964 Say N if you are unsure. 965 966 Say Y if you want to enable such checks. 967 968config RCU_CPU_STALL_INFO 969 bool "Print additional diagnostics on RCU CPU stall" 970 depends on (TREE_RCU || TREE_PREEMPT_RCU) && DEBUG_KERNEL 971 default n 972 help 973 For each stalled CPU that is aware of the current RCU grace 974 period, print out additional per-CPU diagnostic information 975 regarding scheduling-clock ticks, idle state, and, 976 for RCU_FAST_NO_HZ kernels, idle-entry state. 977 978 Say N if you are unsure. 979 980 Say Y if you want to enable such diagnostics. 981 982config RCU_TRACE 983 bool "Enable tracing for RCU" 984 depends on DEBUG_KERNEL 985 help 986 This option provides tracing in RCU which presents stats 987 in debugfs for debugging RCU implementation. 988 989 Say Y here if you want to enable RCU tracing 990 Say N if you are unsure. 991 992config KPROBES_SANITY_TEST 993 bool "Kprobes sanity tests" 994 depends on DEBUG_KERNEL 995 depends on KPROBES 996 default n 997 help 998 This option provides for testing basic kprobes functionality on 999 boot. A sample kprobe, jprobe and kretprobe are inserted and 1000 verified for functionality.
1001 1002 Say N if you are unsure. 1003 1004config BACKTRACE_SELF_TEST 1005 tristate "Self test for the backtrace code" 1006 depends on DEBUG_KERNEL 1007 default n 1008 help 1009 This option provides a kernel module that can be used to test 1010 the kernel stack backtrace code. This option is not useful 1011 for distributions or general kernels, but only for kernel 1012 developers working on architecture code. 1013 1014 Note that if you want to also test saved backtraces, you will 1015 have to enable STACKTRACE as well. 1016 1017 Say N if you are unsure. 1018 1019config DEBUG_BLOCK_EXT_DEVT 1020 bool "Force extended block device numbers and spread them" 1021 depends on DEBUG_KERNEL 1022 depends on BLOCK 1023 default n 1024 help 1025 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON 1026 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT 1027 YOU ARE DOING. Distros, please enable this and fix whatever 1028 is broken. 1029 1030 Conventionally, block device numbers are allocated from 1031 predetermined contiguous area. However, extended block area 1032 may introduce non-contiguous block device numbers. This 1033 option forces most block device numbers to be allocated from 1034 the extended space and spreads them to discover kernel or 1035 userland code paths which assume predetermined contiguous 1036 device number allocation. 1037 1038 Note that turning on this debug option shuffles all the 1039 device numbers for all IDE and SCSI devices including libata 1040 ones, so root partition specified using device number 1041 directly (via rdev or root=MAJ:MIN) won't work anymore. 1042 Textual device names (root=/dev/sdXn) will continue to work. 1043 1044 Say N if you are unsure. 1045 1046config DEBUG_FORCE_WEAK_PER_CPU 1047 bool "Force weak per-cpu definitions" 1048 depends on DEBUG_KERNEL 1049 help 1050 s390 and alpha require percpu variables in modules to be 1051 defined weak to work around addressing range issue which 1052 puts the following two restrictions on percpu variable 1053 definitions. 1054 1055 1. percpu symbols must be unique whether static or not 1056 2. percpu variables can't be defined inside a function 1057 1058 To ensure that generic code follows the above rules, this 1059 option forces all percpu variables to be defined as weak. 1060 1061config DEBUG_PER_CPU_MAPS 1062 bool "Debug access to per_cpu maps" 1063 depends on DEBUG_KERNEL 1064 depends on SMP 1065 help 1066 Say Y to verify that the per_cpu map being accessed has 1067 been set up. This adds a fair amount of code to kernel memory 1068 and decreases performance. 1069 1070 Say N if unsure. 1071 1072config LKDTM 1073 tristate "Linux Kernel Dump Test Tool Module" 1074 depends on DEBUG_FS 1075 depends on BLOCK 1076 default n 1077 help 1078 This module enables testing of the different dumping mechanisms by 1079 inducing system failures at predefined crash points. 1080 If you don't need it: say N 1081 Choose M here to compile this code as a module. The module will be 1082 called lkdtm. 1083 1084 Documentation on how to use the module can be found in 1085 Documentation/fault-injection/provoke-crashes.txt 1086 1087config NOTIFIER_ERROR_INJECTION 1088 tristate "Notifier error injection" 1089 depends on DEBUG_KERNEL 1090 select DEBUG_FS 1091 help 1092 This option provides the ability to inject artifical errors to 1093 specified notifier chain callbacks. It is useful to test the error 1094 handling of notifier call chain failures. 1095 1096 Say N if unsure. 1097 1098config CPU_NOTIFIER_ERROR_INJECT 1099 tristate "CPU notifier error injection module" 1100 depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION 1101 help 1102 This option provides a kernel module that can be used to test 1103 the error handling of the cpu notifiers by injecting artifical 1104 errors to CPU notifier chain callbacks. It is controlled through 1105 debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu 1106 1107 If the notifier call chain should be failed with some events 1108 notified, write the error code to "actions/<notifier event>/error". 1109 1110 Example: Inject CPU offline error (-1 == -EPERM) 1111 1112 # cd /sys/kernel/debug/notifier-error-inject/cpu 1113 # echo -1 > actions/CPU_DOWN_PREPARE/error 1114 # echo 0 > /sys/devices/system/cpu/cpu1/online 1115 bash: echo: write error: Operation not permitted 1116 1117 To compile this code as a module, choose M here: the module will 1118 be called cpu-notifier-error-inject. 1119 1120 If unsure, say N. 1121 1122config PM_NOTIFIER_ERROR_INJECT 1123 tristate "PM notifier error injection module" 1124 depends on PM && NOTIFIER_ERROR_INJECTION 1125 default m if PM_DEBUG 1126 help 1127 This option provides the ability to inject artifical errors to 1128 PM notifier chain callbacks. It is controlled through debugfs 1129 interface /sys/kernel/debug/notifier-error-inject/pm 1130 1131 If the notifier call chain should be failed with some events 1132 notified, write the error code to "actions/<notifier event>/error". 1133 1134 Example: Inject PM suspend error (-12 = -ENOMEM) 1135 1136 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1137 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1138 # echo mem > /sys/power/state 1139 bash: echo: write error: Cannot allocate memory 1140 1141 To compile this code as a module, choose M here: the module will 1142 be called pm-notifier-error-inject. 1143 1144 If unsure, say N. 1145 1146config MEMORY_NOTIFIER_ERROR_INJECT 1147 tristate "Memory hotplug notifier error injection module" 1148 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION 1149 help 1150 This option provides the ability to inject artifical errors to 1151 memory hotplug notifier chain callbacks. It is controlled through 1152 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 1153 1154 If the notifier call chain should be failed with some events 1155 notified, write the error code to "actions/<notifier event>/error". 1156 1157 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 1158 1159 # cd /sys/kernel/debug/notifier-error-inject/memory 1160 # echo -12 > actions/MEM_GOING_OFFLINE/error 1161 # echo offline > /sys/devices/system/memory/memoryXXX/state 1162 bash: echo: write error: Cannot allocate memory 1163 1164 To compile this code as a module, choose M here: the module will 1165 be called pSeries-reconfig-notifier-error-inject. 1166 1167 If unsure, say N. 1168 1169config PSERIES_RECONFIG_NOTIFIER_ERROR_INJECT 1170 tristate "pSeries reconfig notifier error injection module" 1171 depends on PPC_PSERIES && NOTIFIER_ERROR_INJECTION 1172 help 1173 This option provides the ability to inject artifical errors to 1174 pSeries reconfig notifier chain callbacks. It is controlled 1175 through debugfs interface under 1176 /sys/kernel/debug/notifier-error-inject/pSeries-reconfig/ 1177 1178 If the notifier call chain should be failed with some events 1179 notified, write the error code to "actions/<notifier event>/error". 1180 1181 To compile this code as a module, choose M here: the module will 1182 be called memory-notifier-error-inject. 1183 1184 If unsure, say N. 1185 1186config FAULT_INJECTION 1187 bool "Fault-injection framework" 1188 depends on DEBUG_KERNEL 1189 help 1190 Provide fault-injection framework. 1191 For more details, see Documentation/fault-injection/. 1192 1193config FAILSLAB 1194 bool "Fault-injection capability for kmalloc" 1195 depends on FAULT_INJECTION 1196 depends on SLAB || SLUB 1197 help 1198 Provide fault-injection capability for kmalloc. 1199 1200config FAIL_PAGE_ALLOC 1201 bool "Fault-injection capabilitiy for alloc_pages()" 1202 depends on FAULT_INJECTION 1203 help 1204 Provide fault-injection capability for alloc_pages(). 1205 1206config FAIL_MAKE_REQUEST 1207 bool "Fault-injection capability for disk IO" 1208 depends on FAULT_INJECTION && BLOCK 1209 help 1210 Provide fault-injection capability for disk IO. 1211 1212config FAIL_IO_TIMEOUT 1213 bool "Fault-injection capability for faking disk interrupts" 1214 depends on FAULT_INJECTION && BLOCK 1215 help 1216 Provide fault-injection capability on end IO handling. This 1217 will make the block layer "forget" an interrupt as configured, 1218 thus exercising the error handling. 1219 1220 Only works with drivers that use the generic timeout handling, 1221 for others it wont do anything. 1222 1223config FAIL_MMC_REQUEST 1224 bool "Fault-injection capability for MMC IO" 1225 select DEBUG_FS 1226 depends on FAULT_INJECTION && MMC 1227 help 1228 Provide fault-injection capability for MMC IO. 1229 This will make the mmc core return data errors. This is 1230 useful to test the error handling in the mmc block device 1231 and to test how the mmc host driver handles retries from 1232 the block device. 1233 1234config FAULT_INJECTION_DEBUG_FS 1235 bool "Debugfs entries for fault-injection capabilities" 1236 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 1237 help 1238 Enable configuration of fault-injection capabilities via debugfs. 1239 1240config FAULT_INJECTION_STACKTRACE_FILTER 1241 bool "stacktrace filter for fault-injection capabilities" 1242 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 1243 depends on !X86_64 1244 select STACKTRACE 1245 select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND 1246 help 1247 Provide stacktrace filter for fault-injection capabilities 1248 1249config LATENCYTOP 1250 bool "Latency measuring infrastructure" 1251 depends on HAVE_LATENCYTOP_SUPPORT 1252 depends on DEBUG_KERNEL 1253 depends on STACKTRACE_SUPPORT 1254 depends on PROC_FS 1255 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND 1256 select KALLSYMS 1257 select KALLSYMS_ALL 1258 select STACKTRACE 1259 select SCHEDSTATS 1260 select SCHED_DEBUG 1261 help 1262 Enable this option if you want to use the LatencyTOP tool 1263 to find out which userspace is blocking on what kernel operations. 1264 1265source mm/Kconfig.debug 1266source kernel/trace/Kconfig 1267 1268config PROVIDE_OHCI1394_DMA_INIT 1269 bool "Remote debugging over FireWire early on boot" 1270 depends on PCI && X86 1271 help 1272 If you want to debug problems which hang or crash the kernel early 1273 on boot and the crashing machine has a FireWire port, you can use 1274 this feature to remotely access the memory of the crashed machine 1275 over FireWire. This employs remote DMA as part of the OHCI1394 1276 specification which is now the standard for FireWire controllers. 1277 1278 With remote DMA, you can monitor the printk buffer remotely using 1279 firescope and access all memory below 4GB using fireproxy from gdb. 1280 Even controlling a kernel debugger is possible using remote DMA. 1281 1282 Usage: 1283 1284 If ohci1394_dma=early is used as boot parameter, it will initialize 1285 all OHCI1394 controllers which are found in the PCI config space. 1286 1287 As all changes to the FireWire bus such as enabling and disabling 1288 devices cause a bus reset and thereby disable remote DMA for all 1289 devices, be sure to have the cable plugged and FireWire enabled on 1290 the debugging host before booting the debug target for debugging. 1291 1292 This code (~1k) is freed after boot. By then, the firewire stack 1293 in charge of the OHCI-1394 controllers should be used instead. 1294 1295 See Documentation/debugging-via-ohci1394.txt for more information. 1296 1297config FIREWIRE_OHCI_REMOTE_DMA 1298 bool "Remote debugging over FireWire with firewire-ohci" 1299 depends on FIREWIRE_OHCI 1300 help 1301 This option lets you use the FireWire bus for remote debugging 1302 with help of the firewire-ohci driver. It enables unfiltered 1303 remote DMA in firewire-ohci. 1304 See Documentation/debugging-via-ohci1394.txt for more information. 1305 1306 If unsure, say N. 1307 1308config BUILD_DOCSRC 1309 bool "Build targets in Documentation/ tree" 1310 depends on HEADERS_CHECK 1311 help 1312 This option attempts to build objects from the source files in the 1313 kernel Documentation/ tree. 1314 1315 Say N if you are unsure. 1316 1317config DYNAMIC_DEBUG 1318 bool "Enable dynamic printk() support" 1319 default n 1320 depends on PRINTK 1321 depends on DEBUG_FS 1322 help 1323 1324 Compiles debug level messages into the kernel, which would not 1325 otherwise be available at runtime. These messages can then be 1326 enabled/disabled based on various levels of scope - per source file, 1327 function, module, format string, and line number. This mechanism 1328 implicitly compiles in all pr_debug() and dev_dbg() calls, which 1329 enlarges the kernel text size by about 2%. 1330 1331 If a source file is compiled with DEBUG flag set, any 1332 pr_debug() calls in it are enabled by default, but can be 1333 disabled at runtime as below. Note that DEBUG flag is 1334 turned on by many CONFIG_*DEBUG* options. 1335 1336 Usage: 1337 1338 Dynamic debugging is controlled via the 'dynamic_debug/control' file, 1339 which is contained in the 'debugfs' filesystem. Thus, the debugfs 1340 filesystem must first be mounted before making use of this feature. 1341 We refer the control file as: <debugfs>/dynamic_debug/control. This 1342 file contains a list of the debug statements that can be enabled. The 1343 format for each line of the file is: 1344 1345 filename:lineno [module]function flags format 1346 1347 filename : source file of the debug statement 1348 lineno : line number of the debug statement 1349 module : module that contains the debug statement 1350 function : function that contains the debug statement 1351 flags : '=p' means the line is turned 'on' for printing 1352 format : the format used for the debug statement 1353 1354 From a live system: 1355 1356 nullarbor:~ # cat <debugfs>/dynamic_debug/control 1357 # filename:lineno [module]function flags format 1358 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012" 1359 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012" 1360 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012" 1361 1362 Example usage: 1363 1364 // enable the message at line 1603 of file svcsock.c 1365 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' > 1366 <debugfs>/dynamic_debug/control 1367 1368 // enable all the messages in file svcsock.c 1369 nullarbor:~ # echo -n 'file svcsock.c +p' > 1370 <debugfs>/dynamic_debug/control 1371 1372 // enable all the messages in the NFS server module 1373 nullarbor:~ # echo -n 'module nfsd +p' > 1374 <debugfs>/dynamic_debug/control 1375 1376 // enable all 12 messages in the function svc_process() 1377 nullarbor:~ # echo -n 'func svc_process +p' > 1378 <debugfs>/dynamic_debug/control 1379 1380 // disable all 12 messages in the function svc_process() 1381 nullarbor:~ # echo -n 'func svc_process -p' > 1382 <debugfs>/dynamic_debug/control 1383 1384 See Documentation/dynamic-debug-howto.txt for additional information. 1385 1386config DMA_API_DEBUG 1387 bool "Enable debugging of DMA-API usage" 1388 depends on HAVE_DMA_API_DEBUG 1389 help 1390 Enable this option to debug the use of the DMA API by device drivers. 1391 With this option you will be able to detect common bugs in device 1392 drivers like double-freeing of DMA mappings or freeing mappings that 1393 were never allocated. 1394 This option causes a performance degredation. Use only if you want 1395 to debug device drivers. If unsure, say N. 1396 1397config ATOMIC64_SELFTEST 1398 bool "Perform an atomic64_t self-test at boot" 1399 help 1400 Enable this option to test the atomic64_t functions at boot. 1401 1402 If unsure, say N. 1403 1404config ASYNC_RAID6_TEST 1405 tristate "Self test for hardware accelerated raid6 recovery" 1406 depends on ASYNC_RAID6_RECOV 1407 select ASYNC_MEMCPY 1408 ---help--- 1409 This is a one-shot self test that permutes through the 1410 recovery of all the possible two disk failure scenarios for a 1411 N-disk array. Recovery is performed with the asynchronous 1412 raid6 recovery routines, and will optionally use an offload 1413 engine if one is available. 1414 1415 If unsure, say N. 1416 1417source "samples/Kconfig" 1418 1419source "lib/Kconfig.kgdb" 1420 1421source "lib/Kconfig.kmemcheck" 1422 1423config TEST_KSTRTOX 1424 tristate "Test kstrto*() family of functions at runtime" 1425