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 || \ 456 MICROBLAZE || TILE || ARM64) 457 458 select DEBUG_FS 459 select STACKTRACE if STACKTRACE_SUPPORT 460 select KALLSYMS 461 select CRC32 462 help 463 Say Y here if you want to enable the memory leak 464 detector. The memory allocation/freeing is traced in a way 465 similar to the Boehm's conservative garbage collector, the 466 difference being that the orphan objects are not freed but 467 only shown in /sys/kernel/debug/kmemleak. Enabling this 468 feature will introduce an overhead to memory 469 allocations. See Documentation/kmemleak.txt for more 470 details. 471 472 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances 473 of finding leaks due to the slab objects poisoning. 474 475 In order to access the kmemleak file, debugfs needs to be 476 mounted (usually at /sys/kernel/debug). 477 478config DEBUG_KMEMLEAK_EARLY_LOG_SIZE 479 int "Maximum kmemleak early log entries" 480 depends on DEBUG_KMEMLEAK 481 range 200 40000 482 default 400 483 help 484 Kmemleak must track all the memory allocations to avoid 485 reporting false positives. Since memory may be allocated or 486 freed before kmemleak is initialised, an early log buffer is 487 used to store these actions. If kmemleak reports "early log 488 buffer exceeded", please increase this value. 489 490config DEBUG_KMEMLEAK_TEST 491 tristate "Simple test for the kernel memory leak detector" 492 depends on DEBUG_KMEMLEAK && m 493 help 494 This option enables a module that explicitly leaks memory. 495 496 If unsure, say N. 497 498config DEBUG_KMEMLEAK_DEFAULT_OFF 499 bool "Default kmemleak to off" 500 depends on DEBUG_KMEMLEAK 501 help 502 Say Y here to disable kmemleak by default. It can then be enabled 503 on the command line via kmemleak=on. 504 505config DEBUG_PREEMPT 506 bool "Debug preemptible kernel" 507 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT 508 default y 509 help 510 If you say Y here then the kernel will use a debug variant of the 511 commonly used smp_processor_id() function and will print warnings 512 if kernel code uses it in a preemption-unsafe way. Also, the kernel 513 will detect preemption count underflows. 514 515config DEBUG_RT_MUTEXES 516 bool "RT Mutex debugging, deadlock detection" 517 depends on DEBUG_KERNEL && RT_MUTEXES 518 help 519 This allows rt mutex semantics violations and rt mutex related 520 deadlocks (lockups) to be detected and reported automatically. 521 522config DEBUG_PI_LIST 523 bool 524 default y 525 depends on DEBUG_RT_MUTEXES 526 527config RT_MUTEX_TESTER 528 bool "Built-in scriptable tester for rt-mutexes" 529 depends on DEBUG_KERNEL && RT_MUTEXES 530 help 531 This option enables a rt-mutex tester. 532 533config DEBUG_SPINLOCK 534 bool "Spinlock and rw-lock debugging: basic checks" 535 depends on DEBUG_KERNEL 536 select UNINLINE_SPIN_UNLOCK 537 help 538 Say Y here and build SMP to catch missing spinlock initialization 539 and certain other kinds of spinlock errors commonly made. This is 540 best used in conjunction with the NMI watchdog so that spinlock 541 deadlocks are also debuggable. 542 543config DEBUG_MUTEXES 544 bool "Mutex debugging: basic checks" 545 depends on DEBUG_KERNEL 546 help 547 This feature allows mutex semantics violations to be detected and 548 reported. 549 550config DEBUG_LOCK_ALLOC 551 bool "Lock debugging: detect incorrect freeing of live locks" 552 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 553 select DEBUG_SPINLOCK 554 select DEBUG_MUTEXES 555 select LOCKDEP 556 help 557 This feature will check whether any held lock (spinlock, rwlock, 558 mutex or rwsem) is incorrectly freed by the kernel, via any of the 559 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 560 vfree(), etc.), whether a live lock is incorrectly reinitialized via 561 spin_lock_init()/mutex_init()/etc., or whether there is any lock 562 held during task exit. 563 564config PROVE_LOCKING 565 bool "Lock debugging: prove locking correctness" 566 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 567 select LOCKDEP 568 select DEBUG_SPINLOCK 569 select DEBUG_MUTEXES 570 select DEBUG_LOCK_ALLOC 571 select TRACE_IRQFLAGS 572 default n 573 help 574 This feature enables the kernel to prove that all locking 575 that occurs in the kernel runtime is mathematically 576 correct: that under no circumstance could an arbitrary (and 577 not yet triggered) combination of observed locking 578 sequences (on an arbitrary number of CPUs, running an 579 arbitrary number of tasks and interrupt contexts) cause a 580 deadlock. 581 582 In short, this feature enables the kernel to report locking 583 related deadlocks before they actually occur. 584 585 The proof does not depend on how hard and complex a 586 deadlock scenario would be to trigger: how many 587 participant CPUs, tasks and irq-contexts would be needed 588 for it to trigger. The proof also does not depend on 589 timing: if a race and a resulting deadlock is possible 590 theoretically (no matter how unlikely the race scenario 591 is), it will be proven so and will immediately be 592 reported by the kernel (once the event is observed that 593 makes the deadlock theoretically possible). 594 595 If a deadlock is impossible (i.e. the locking rules, as 596 observed by the kernel, are mathematically correct), the 597 kernel reports nothing. 598 599 NOTE: this feature can also be enabled for rwlocks, mutexes 600 and rwsems - in which case all dependencies between these 601 different locking variants are observed and mapped too, and 602 the proof of observed correctness is also maintained for an 603 arbitrary combination of these separate locking variants. 604 605 For more details, see Documentation/lockdep-design.txt. 606 607config PROVE_RCU 608 bool "RCU debugging: prove RCU correctness" 609 depends on PROVE_LOCKING 610 default n 611 help 612 This feature enables lockdep extensions that check for correct 613 use of RCU APIs. This is currently under development. Say Y 614 if you want to debug RCU usage or help work on the PROVE_RCU 615 feature. 616 617 Say N if you are unsure. 618 619config PROVE_RCU_REPEATEDLY 620 bool "RCU debugging: don't disable PROVE_RCU on first splat" 621 depends on PROVE_RCU 622 default n 623 help 624 By itself, PROVE_RCU will disable checking upon issuing the 625 first warning (or "splat"). This feature prevents such 626 disabling, allowing multiple RCU-lockdep warnings to be printed 627 on a single reboot. 628 629 Say Y to allow multiple RCU-lockdep warnings per boot. 630 631 Say N if you are unsure. 632 633config PROVE_RCU_DELAY 634 bool "RCU debugging: preemptible RCU race provocation" 635 depends on DEBUG_KERNEL && PREEMPT_RCU 636 default n 637 help 638 There is a class of races that involve an unlikely preemption 639 of __rcu_read_unlock() just after ->rcu_read_lock_nesting has 640 been set to INT_MIN. This feature inserts a delay at that 641 point to increase the probability of these races. 642 643 Say Y to increase probability of preemption of __rcu_read_unlock(). 644 645 Say N if you are unsure. 646 647config SPARSE_RCU_POINTER 648 bool "RCU debugging: sparse-based checks for pointer usage" 649 default n 650 help 651 This feature enables the __rcu sparse annotation for 652 RCU-protected pointers. This annotation will cause sparse 653 to flag any non-RCU used of annotated pointers. This can be 654 helpful when debugging RCU usage. Please note that this feature 655 is not intended to enforce code cleanliness; it is instead merely 656 a debugging aid. 657 658 Say Y to make sparse flag questionable use of RCU-protected pointers 659 660 Say N if you are unsure. 661 662config LOCKDEP 663 bool 664 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 665 select STACKTRACE 666 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE 667 select KALLSYMS 668 select KALLSYMS_ALL 669 670config LOCK_STAT 671 bool "Lock usage statistics" 672 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 673 select LOCKDEP 674 select DEBUG_SPINLOCK 675 select DEBUG_MUTEXES 676 select DEBUG_LOCK_ALLOC 677 default n 678 help 679 This feature enables tracking lock contention points 680 681 For more details, see Documentation/lockstat.txt 682 683 This also enables lock events required by "perf lock", 684 subcommand of perf. 685 If you want to use "perf lock", you also need to turn on 686 CONFIG_EVENT_TRACING. 687 688 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 689 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 690 691config DEBUG_LOCKDEP 692 bool "Lock dependency engine debugging" 693 depends on DEBUG_KERNEL && LOCKDEP 694 help 695 If you say Y here, the lock dependency engine will do 696 additional runtime checks to debug itself, at the price 697 of more runtime overhead. 698 699config TRACE_IRQFLAGS 700 bool 701 help 702 Enables hooks to interrupt enabling and disabling for 703 either tracing or lock debugging. 704 705config DEBUG_ATOMIC_SLEEP 706 bool "Sleep inside atomic section checking" 707 select PREEMPT_COUNT 708 depends on DEBUG_KERNEL 709 help 710 If you say Y here, various routines which may sleep will become very 711 noisy if they are called inside atomic sections: when a spinlock is 712 held, inside an rcu read side critical section, inside preempt disabled 713 sections, inside an interrupt, etc... 714 715config DEBUG_LOCKING_API_SELFTESTS 716 bool "Locking API boot-time self-tests" 717 depends on DEBUG_KERNEL 718 help 719 Say Y here if you want the kernel to run a short self-test during 720 bootup. The self-test checks whether common types of locking bugs 721 are detected by debugging mechanisms or not. (if you disable 722 lock debugging then those bugs wont be detected of course.) 723 The following locking APIs are covered: spinlocks, rwlocks, 724 mutexes and rwsems. 725 726config STACKTRACE 727 bool 728 depends on STACKTRACE_SUPPORT 729 730config DEBUG_STACK_USAGE 731 bool "Stack utilization instrumentation" 732 depends on DEBUG_KERNEL && !IA64 && !PARISC 733 help 734 Enables the display of the minimum amount of free stack which each 735 task has ever had available in the sysrq-T and sysrq-P debug output. 736 737 This option will slow down process creation somewhat. 738 739config DEBUG_KOBJECT 740 bool "kobject debugging" 741 depends on DEBUG_KERNEL 742 help 743 If you say Y here, some extra kobject debugging messages will be sent 744 to the syslog. 745 746config DEBUG_HIGHMEM 747 bool "Highmem debugging" 748 depends on DEBUG_KERNEL && HIGHMEM 749 help 750 This options enables addition error checking for high memory systems. 751 Disable for production systems. 752 753config DEBUG_BUGVERBOSE 754 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT 755 depends on BUG 756 depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \ 757 FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300 || \ 758 TILE || ARM64 759 default y 760 help 761 Say Y here to make BUG() panics output the file name and line number 762 of the BUG call as well as the EIP and oops trace. This aids 763 debugging but costs about 70-100K of memory. 764 765config DEBUG_INFO 766 bool "Compile the kernel with debug info" 767 depends on DEBUG_KERNEL 768 help 769 If you say Y here the resulting kernel image will include 770 debugging info resulting in a larger kernel image. 771 This adds debug symbols to the kernel and modules (gcc -g), and 772 is needed if you intend to use kernel crashdump or binary object 773 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 774 Say Y here only if you plan to debug the kernel. 775 776 If unsure, say N. 777 778config DEBUG_INFO_REDUCED 779 bool "Reduce debugging information" 780 depends on DEBUG_INFO 781 help 782 If you say Y here gcc is instructed to generate less debugging 783 information for structure types. This means that tools that 784 need full debugging information (like kgdb or systemtap) won't 785 be happy. But if you merely need debugging information to 786 resolve line numbers there is no loss. Advantage is that 787 build directory object sizes shrink dramatically over a full 788 DEBUG_INFO build and compile times are reduced too. 789 Only works with newer gcc versions. 790 791config DEBUG_VM 792 bool "Debug VM" 793 depends on DEBUG_KERNEL 794 help 795 Enable this to turn on extended checks in the virtual-memory system 796 that may impact performance. 797 798 If unsure, say N. 799 800config DEBUG_VIRTUAL 801 bool "Debug VM translations" 802 depends on DEBUG_KERNEL && X86 803 help 804 Enable some costly sanity checks in virtual to page code. This can 805 catch mistakes with virt_to_page() and friends. 806 807 If unsure, say N. 808 809config DEBUG_NOMMU_REGIONS 810 bool "Debug the global anon/private NOMMU mapping region tree" 811 depends on DEBUG_KERNEL && !MMU 812 help 813 This option causes the global tree of anonymous and private mapping 814 regions to be regularly checked for invalid topology. 815 816config DEBUG_WRITECOUNT 817 bool "Debug filesystem writers count" 818 depends on DEBUG_KERNEL 819 help 820 Enable this to catch wrong use of the writers count in struct 821 vfsmount. This will increase the size of each file struct by 822 32 bits. 823 824 If unsure, say N. 825 826config DEBUG_MEMORY_INIT 827 bool "Debug memory initialisation" if EXPERT 828 default !EXPERT 829 help 830 Enable this for additional checks during memory initialisation. 831 The sanity checks verify aspects of the VM such as the memory model 832 and other information provided by the architecture. Verbose 833 information will be printed at KERN_DEBUG loglevel depending 834 on the mminit_loglevel= command-line option. 835 836 If unsure, say Y 837 838config DEBUG_LIST 839 bool "Debug linked list manipulation" 840 depends on DEBUG_KERNEL 841 help 842 Enable this to turn on extended checks in the linked-list 843 walking routines. 844 845 If unsure, say N. 846 847config TEST_LIST_SORT 848 bool "Linked list sorting test" 849 depends on DEBUG_KERNEL 850 help 851 Enable this to turn on 'list_sort()' function test. This test is 852 executed only once during system boot, so affects only boot time. 853 854 If unsure, say N. 855 856config DEBUG_SG 857 bool "Debug SG table operations" 858 depends on DEBUG_KERNEL 859 help 860 Enable this to turn on checks on scatter-gather tables. This can 861 help find problems with drivers that do not properly initialize 862 their sg tables. 863 864 If unsure, say N. 865 866config DEBUG_NOTIFIERS 867 bool "Debug notifier call chains" 868 depends on DEBUG_KERNEL 869 help 870 Enable this to turn on sanity checking for notifier call chains. 871 This is most useful for kernel developers to make sure that 872 modules properly unregister themselves from notifier chains. 873 This is a relatively cheap check but if you care about maximum 874 performance, say N. 875 876config DEBUG_CREDENTIALS 877 bool "Debug credential management" 878 depends on DEBUG_KERNEL 879 help 880 Enable this to turn on some debug checking for credential 881 management. The additional code keeps track of the number of 882 pointers from task_structs to any given cred struct, and checks to 883 see that this number never exceeds the usage count of the cred 884 struct. 885 886 Furthermore, if SELinux is enabled, this also checks that the 887 security pointer in the cred struct is never seen to be invalid. 888 889 If unsure, say N. 890 891# 892# Select this config option from the architecture Kconfig, if it 893# is preferred to always offer frame pointers as a config 894# option on the architecture (regardless of KERNEL_DEBUG): 895# 896config ARCH_WANT_FRAME_POINTERS 897 bool 898 help 899 900config FRAME_POINTER 901 bool "Compile the kernel with frame pointers" 902 depends on DEBUG_KERNEL && \ 903 (CRIS || M68K || FRV || UML || \ 904 AVR32 || SUPERH || BLACKFIN || MN10300) || \ 905 ARCH_WANT_FRAME_POINTERS 906 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 907 help 908 If you say Y here the resulting kernel image will be slightly 909 larger and slower, but it gives very useful debugging information 910 in case of kernel bugs. (precise oopses/stacktraces/warnings) 911 912config BOOT_PRINTK_DELAY 913 bool "Delay each boot printk message by N milliseconds" 914 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY 915 help 916 This build option allows you to read kernel boot messages 917 by inserting a short delay after each one. The delay is 918 specified in milliseconds on the kernel command line, 919 using "boot_delay=N". 920 921 It is likely that you would also need to use "lpj=M" to preset 922 the "loops per jiffie" value. 923 See a previous boot log for the "lpj" value to use for your 924 system, and then set "lpj=M" before setting "boot_delay=N". 925 NOTE: Using this option may adversely affect SMP systems. 926 I.e., processors other than the first one may not boot up. 927 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect 928 what it believes to be lockup conditions. 929 930config RCU_TORTURE_TEST 931 tristate "torture tests for RCU" 932 depends on DEBUG_KERNEL 933 default n 934 help 935 This option provides a kernel module that runs torture tests 936 on the RCU infrastructure. The kernel module may be built 937 after the fact on the running kernel to be tested, if desired. 938 939 Say Y here if you want RCU torture tests to be built into 940 the kernel. 941 Say M if you want the RCU torture tests to build as a module. 942 Say N if you are unsure. 943 944config RCU_TORTURE_TEST_RUNNABLE 945 bool "torture tests for RCU runnable by default" 946 depends on RCU_TORTURE_TEST = y 947 default n 948 help 949 This option provides a way to build the RCU torture tests 950 directly into the kernel without them starting up at boot 951 time. You can use /proc/sys/kernel/rcutorture_runnable 952 to manually override this setting. This /proc file is 953 available only when the RCU torture tests have been built 954 into the kernel. 955 956 Say Y here if you want the RCU torture tests to start during 957 boot (you probably don't). 958 Say N here if you want the RCU torture tests to start only 959 after being manually enabled via /proc. 960 961config RCU_CPU_STALL_TIMEOUT 962 int "RCU CPU stall timeout in seconds" 963 depends on TREE_RCU || TREE_PREEMPT_RCU 964 range 3 300 965 default 60 966 help 967 If a given RCU grace period extends more than the specified 968 number of seconds, a CPU stall warning is printed. If the 969 RCU grace period persists, additional CPU stall warnings are 970 printed at more widely spaced intervals. 971 972config RCU_CPU_STALL_VERBOSE 973 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR" 974 depends on TREE_PREEMPT_RCU 975 default y 976 help 977 This option causes RCU to printk detailed per-task information 978 for any tasks that are stalling the current RCU grace period. 979 980 Say N if you are unsure. 981 982 Say Y if you want to enable such checks. 983 984config RCU_CPU_STALL_INFO 985 bool "Print additional diagnostics on RCU CPU stall" 986 depends on (TREE_RCU || TREE_PREEMPT_RCU) && DEBUG_KERNEL 987 default n 988 help 989 For each stalled CPU that is aware of the current RCU grace 990 period, print out additional per-CPU diagnostic information 991 regarding scheduling-clock ticks, idle state, and, 992 for RCU_FAST_NO_HZ kernels, idle-entry state. 993 994 Say N if you are unsure. 995 996 Say Y if you want to enable such diagnostics. 997 998config RCU_TRACE 999 bool "Enable tracing for RCU" 1000 depends on DEBUG_KERNEL 1001 help 1002 This option provides tracing in RCU which presents stats 1003 in debugfs for debugging RCU implementation. 1004 1005 Say Y here if you want to enable RCU tracing 1006 Say N if you are unsure. 1007 1008config KPROBES_SANITY_TEST 1009 bool "Kprobes sanity tests" 1010 depends on DEBUG_KERNEL 1011 depends on KPROBES 1012 default n 1013 help 1014 This option provides for testing basic kprobes functionality on 1015 boot. A sample kprobe, jprobe and kretprobe are inserted and 1016 verified for functionality. 1017 1018 Say N if you are unsure. 1019 1020config BACKTRACE_SELF_TEST 1021 tristate "Self test for the backtrace code" 1022 depends on DEBUG_KERNEL 1023 default n 1024 help 1025 This option provides a kernel module that can be used to test 1026 the kernel stack backtrace code. This option is not useful 1027 for distributions or general kernels, but only for kernel 1028 developers working on architecture code. 1029 1030 Note that if you want to also test saved backtraces, you will 1031 have to enable STACKTRACE as well. 1032 1033 Say N if you are unsure. 1034 1035config DEBUG_BLOCK_EXT_DEVT 1036 bool "Force extended block device numbers and spread them" 1037 depends on DEBUG_KERNEL 1038 depends on BLOCK 1039 default n 1040 help 1041 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON 1042 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT 1043 YOU ARE DOING. Distros, please enable this and fix whatever 1044 is broken. 1045 1046 Conventionally, block device numbers are allocated from 1047 predetermined contiguous area. However, extended block area 1048 may introduce non-contiguous block device numbers. This 1049 option forces most block device numbers to be allocated from 1050 the extended space and spreads them to discover kernel or 1051 userland code paths which assume predetermined contiguous 1052 device number allocation. 1053 1054 Note that turning on this debug option shuffles all the 1055 device numbers for all IDE and SCSI devices including libata 1056 ones, so root partition specified using device number 1057 directly (via rdev or root=MAJ:MIN) won't work anymore. 1058 Textual device names (root=/dev/sdXn) will continue to work. 1059 1060 Say N if you are unsure. 1061 1062config DEBUG_FORCE_WEAK_PER_CPU 1063 bool "Force weak per-cpu definitions" 1064 depends on DEBUG_KERNEL 1065 help 1066 s390 and alpha require percpu variables in modules to be 1067 defined weak to work around addressing range issue which 1068 puts the following two restrictions on percpu variable 1069 definitions. 1070 1071 1. percpu symbols must be unique whether static or not 1072 2. percpu variables can't be defined inside a function 1073 1074 To ensure that generic code follows the above rules, this 1075 option forces all percpu variables to be defined as weak. 1076 1077config DEBUG_PER_CPU_MAPS 1078 bool "Debug access to per_cpu maps" 1079 depends on DEBUG_KERNEL 1080 depends on SMP 1081 help 1082 Say Y to verify that the per_cpu map being accessed has 1083 been set up. This adds a fair amount of code to kernel memory 1084 and decreases performance. 1085 1086 Say N if unsure. 1087 1088config LKDTM 1089 tristate "Linux Kernel Dump Test Tool Module" 1090 depends on DEBUG_FS 1091 depends on BLOCK 1092 default n 1093 help 1094 This module enables testing of the different dumping mechanisms by 1095 inducing system failures at predefined crash points. 1096 If you don't need it: say N 1097 Choose M here to compile this code as a module. The module will be 1098 called lkdtm. 1099 1100 Documentation on how to use the module can be found in 1101 Documentation/fault-injection/provoke-crashes.txt 1102 1103config NOTIFIER_ERROR_INJECTION 1104 tristate "Notifier error injection" 1105 depends on DEBUG_KERNEL 1106 select DEBUG_FS 1107 help 1108 This option provides the ability to inject artifical errors to 1109 specified notifier chain callbacks. It is useful to test the error 1110 handling of notifier call chain failures. 1111 1112 Say N if unsure. 1113 1114config CPU_NOTIFIER_ERROR_INJECT 1115 tristate "CPU notifier error injection module" 1116 depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION 1117 help 1118 This option provides a kernel module that can be used to test 1119 the error handling of the cpu notifiers by injecting artifical 1120 errors to CPU notifier chain callbacks. It is controlled through 1121 debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu 1122 1123 If the notifier call chain should be failed with some events 1124 notified, write the error code to "actions/<notifier event>/error". 1125 1126 Example: Inject CPU offline error (-1 == -EPERM) 1127 1128 # cd /sys/kernel/debug/notifier-error-inject/cpu 1129 # echo -1 > actions/CPU_DOWN_PREPARE/error 1130 # echo 0 > /sys/devices/system/cpu/cpu1/online 1131 bash: echo: write error: Operation not permitted 1132 1133 To compile this code as a module, choose M here: the module will 1134 be called cpu-notifier-error-inject. 1135 1136 If unsure, say N. 1137 1138config PM_NOTIFIER_ERROR_INJECT 1139 tristate "PM notifier error injection module" 1140 depends on PM && NOTIFIER_ERROR_INJECTION 1141 default m if PM_DEBUG 1142 help 1143 This option provides the ability to inject artifical errors to 1144 PM notifier chain callbacks. It is controlled through debugfs 1145 interface /sys/kernel/debug/notifier-error-inject/pm 1146 1147 If the notifier call chain should be failed with some events 1148 notified, write the error code to "actions/<notifier event>/error". 1149 1150 Example: Inject PM suspend error (-12 = -ENOMEM) 1151 1152 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1153 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1154 # echo mem > /sys/power/state 1155 bash: echo: write error: Cannot allocate memory 1156 1157 To compile this code as a module, choose M here: the module will 1158 be called pm-notifier-error-inject. 1159 1160 If unsure, say N. 1161 1162config MEMORY_NOTIFIER_ERROR_INJECT 1163 tristate "Memory hotplug notifier error injection module" 1164 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION 1165 help 1166 This option provides the ability to inject artifical errors to 1167 memory hotplug notifier chain callbacks. It is controlled through 1168 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 1169 1170 If the notifier call chain should be failed with some events 1171 notified, write the error code to "actions/<notifier event>/error". 1172 1173 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 1174 1175 # cd /sys/kernel/debug/notifier-error-inject/memory 1176 # echo -12 > actions/MEM_GOING_OFFLINE/error 1177 # echo offline > /sys/devices/system/memory/memoryXXX/state 1178 bash: echo: write error: Cannot allocate memory 1179 1180 To compile this code as a module, choose M here: the module will 1181 be called pSeries-reconfig-notifier-error-inject. 1182 1183 If unsure, say N. 1184 1185config PSERIES_RECONFIG_NOTIFIER_ERROR_INJECT 1186 tristate "pSeries reconfig notifier error injection module" 1187 depends on PPC_PSERIES && NOTIFIER_ERROR_INJECTION 1188 help 1189 This option provides the ability to inject artifical errors to 1190 pSeries reconfig notifier chain callbacks. It is controlled 1191 through debugfs interface under 1192 /sys/kernel/debug/notifier-error-inject/pSeries-reconfig/ 1193 1194 If the notifier call chain should be failed with some events 1195 notified, write the error code to "actions/<notifier event>/error". 1196 1197 To compile this code as a module, choose M here: the module will 1198 be called memory-notifier-error-inject. 1199 1200 If unsure, say N. 1201 1202config FAULT_INJECTION 1203 bool "Fault-injection framework" 1204 depends on DEBUG_KERNEL 1205 help 1206 Provide fault-injection framework. 1207 For more details, see Documentation/fault-injection/. 1208 1209config FAILSLAB 1210 bool "Fault-injection capability for kmalloc" 1211 depends on FAULT_INJECTION 1212 depends on SLAB || SLUB 1213 help 1214 Provide fault-injection capability for kmalloc. 1215 1216config FAIL_PAGE_ALLOC 1217 bool "Fault-injection capabilitiy for alloc_pages()" 1218 depends on FAULT_INJECTION 1219 help 1220 Provide fault-injection capability for alloc_pages(). 1221 1222config FAIL_MAKE_REQUEST 1223 bool "Fault-injection capability for disk IO" 1224 depends on FAULT_INJECTION && BLOCK 1225 help 1226 Provide fault-injection capability for disk IO. 1227 1228config FAIL_IO_TIMEOUT 1229 bool "Fault-injection capability for faking disk interrupts" 1230 depends on FAULT_INJECTION && BLOCK 1231 help 1232 Provide fault-injection capability on end IO handling. This 1233 will make the block layer "forget" an interrupt as configured, 1234 thus exercising the error handling. 1235 1236 Only works with drivers that use the generic timeout handling, 1237 for others it wont do anything. 1238 1239config FAIL_MMC_REQUEST 1240 bool "Fault-injection capability for MMC IO" 1241 select DEBUG_FS 1242 depends on FAULT_INJECTION && MMC 1243 help 1244 Provide fault-injection capability for MMC IO. 1245 This will make the mmc core return data errors. This is 1246 useful to test the error handling in the mmc block device 1247 and to test how the mmc host driver handles retries from 1248 the block device. 1249 1250config FAULT_INJECTION_DEBUG_FS 1251 bool "Debugfs entries for fault-injection capabilities" 1252 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 1253 help 1254 Enable configuration of fault-injection capabilities via debugfs. 1255 1256config FAULT_INJECTION_STACKTRACE_FILTER 1257 bool "stacktrace filter for fault-injection capabilities" 1258 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 1259 depends on !X86_64 1260 select STACKTRACE 1261 select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND 1262 help 1263 Provide stacktrace filter for fault-injection capabilities 1264 1265config LATENCYTOP 1266 bool "Latency measuring infrastructure" 1267 depends on HAVE_LATENCYTOP_SUPPORT 1268 depends on DEBUG_KERNEL 1269 depends on STACKTRACE_SUPPORT 1270 depends on PROC_FS 1271 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND 1272 select KALLSYMS 1273 select KALLSYMS_ALL 1274 select STACKTRACE 1275 select SCHEDSTATS 1276 select SCHED_DEBUG 1277 help 1278 Enable this option if you want to use the LatencyTOP tool 1279 to find out which userspace is blocking on what kernel operations. 1280 1281source mm/Kconfig.debug 1282source kernel/trace/Kconfig 1283 1284config PROVIDE_OHCI1394_DMA_INIT 1285 bool "Remote debugging over FireWire early on boot" 1286 depends on PCI && X86 1287 help 1288 If you want to debug problems which hang or crash the kernel early 1289 on boot and the crashing machine has a FireWire port, you can use 1290 this feature to remotely access the memory of the crashed machine 1291 over FireWire. This employs remote DMA as part of the OHCI1394 1292 specification which is now the standard for FireWire controllers. 1293 1294 With remote DMA, you can monitor the printk buffer remotely using 1295 firescope and access all memory below 4GB using fireproxy from gdb. 1296 Even controlling a kernel debugger is possible using remote DMA. 1297 1298 Usage: 1299 1300 If ohci1394_dma=early is used as boot parameter, it will initialize 1301 all OHCI1394 controllers which are found in the PCI config space. 1302 1303 As all changes to the FireWire bus such as enabling and disabling 1304 devices cause a bus reset and thereby disable remote DMA for all 1305 devices, be sure to have the cable plugged and FireWire enabled on 1306 the debugging host before booting the debug target for debugging. 1307 1308 This code (~1k) is freed after boot. By then, the firewire stack 1309 in charge of the OHCI-1394 controllers should be used instead. 1310 1311 See Documentation/debugging-via-ohci1394.txt for more information. 1312 1313config FIREWIRE_OHCI_REMOTE_DMA 1314 bool "Remote debugging over FireWire with firewire-ohci" 1315 depends on FIREWIRE_OHCI 1316 help 1317 This option lets you use the FireWire bus for remote debugging 1318 with help of the firewire-ohci driver. It enables unfiltered 1319 remote DMA in firewire-ohci. 1320 See Documentation/debugging-via-ohci1394.txt for more information. 1321 1322 If unsure, say N. 1323 1324config BUILD_DOCSRC 1325 bool "Build targets in Documentation/ tree" 1326 depends on HEADERS_CHECK 1327 help 1328 This option attempts to build objects from the source files in the 1329 kernel Documentation/ tree. 1330 1331 Say N if you are unsure. 1332 1333config DYNAMIC_DEBUG 1334 bool "Enable dynamic printk() support" 1335 default n 1336 depends on PRINTK 1337 depends on DEBUG_FS 1338 help 1339 1340 Compiles debug level messages into the kernel, which would not 1341 otherwise be available at runtime. These messages can then be 1342 enabled/disabled based on various levels of scope - per source file, 1343 function, module, format string, and line number. This mechanism 1344 implicitly compiles in all pr_debug() and dev_dbg() calls, which 1345 enlarges the kernel text size by about 2%. 1346 1347 If a source file is compiled with DEBUG flag set, any 1348 pr_debug() calls in it are enabled by default, but can be 1349 disabled at runtime as below. Note that DEBUG flag is 1350 turned on by many CONFIG_*DEBUG* options. 1351 1352 Usage: 1353 1354 Dynamic debugging is controlled via the 'dynamic_debug/control' file, 1355 which is contained in the 'debugfs' filesystem. Thus, the debugfs 1356 filesystem must first be mounted before making use of this feature. 1357 We refer the control file as: <debugfs>/dynamic_debug/control. This 1358 file contains a list of the debug statements that can be enabled. The 1359 format for each line of the file is: 1360 1361 filename:lineno [module]function flags format 1362 1363 filename : source file of the debug statement 1364 lineno : line number of the debug statement 1365 module : module that contains the debug statement 1366 function : function that contains the debug statement 1367 flags : '=p' means the line is turned 'on' for printing 1368 format : the format used for the debug statement 1369 1370 From a live system: 1371 1372 nullarbor:~ # cat <debugfs>/dynamic_debug/control 1373 # filename:lineno [module]function flags format 1374 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012" 1375 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012" 1376 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012" 1377 1378 Example usage: 1379 1380 // enable the message at line 1603 of file svcsock.c 1381 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' > 1382 <debugfs>/dynamic_debug/control 1383 1384 // enable all the messages in file svcsock.c 1385 nullarbor:~ # echo -n 'file svcsock.c +p' > 1386 <debugfs>/dynamic_debug/control 1387 1388 // enable all the messages in the NFS server module 1389 nullarbor:~ # echo -n 'module nfsd +p' > 1390 <debugfs>/dynamic_debug/control 1391 1392 // enable all 12 messages in the function svc_process() 1393 nullarbor:~ # echo -n 'func svc_process +p' > 1394 <debugfs>/dynamic_debug/control 1395 1396 // disable all 12 messages in the function svc_process() 1397 nullarbor:~ # echo -n 'func svc_process -p' > 1398 <debugfs>/dynamic_debug/control 1399 1400 See Documentation/dynamic-debug-howto.txt for additional information. 1401 1402config DMA_API_DEBUG 1403 bool "Enable debugging of DMA-API usage" 1404 depends on HAVE_DMA_API_DEBUG 1405 help 1406 Enable this option to debug the use of the DMA API by device drivers. 1407 With this option you will be able to detect common bugs in device 1408 drivers like double-freeing of DMA mappings or freeing mappings that 1409 were never allocated. 1410 This option causes a performance degredation. Use only if you want 1411 to debug device drivers. If unsure, say N. 1412 1413config ATOMIC64_SELFTEST 1414 bool "Perform an atomic64_t self-test at boot" 1415 help 1416 Enable this option to test the atomic64_t functions at boot. 1417 1418 If unsure, say N. 1419 1420config ASYNC_RAID6_TEST 1421 tristate "Self test for hardware accelerated raid6 recovery" 1422 depends on ASYNC_RAID6_RECOV 1423 select ASYNC_MEMCPY 1424 ---help--- 1425 This is a one-shot self test that permutes through the 1426 recovery of all the possible two disk failure scenarios for a 1427 N-disk array. Recovery is performed with the asynchronous 1428 raid6 recovery routines, and will optionally use an offload 1429 engine if one is available. 1430 1431 If unsure, say N. 1432 1433source "samples/Kconfig" 1434 1435source "lib/Kconfig.kgdb" 1436 1437source "lib/Kconfig.kmemcheck" 1438 1439config TEST_KSTRTOX 1440 tristate "Test kstrto*() family of functions at runtime" 1441