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