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 depends on UNDEFINED || (BLACKFIN) 106 default y 107 # This option is on purpose disabled for now. 108 # It will be enabled when we are down to a reasonable number 109 # of section mismatch warnings (< 10 for an allyesconfig build) 110 help 111 The section mismatch analysis checks if there are illegal 112 references from one section to another section. 113 Linux will during link or during runtime drop some sections 114 and any use of code/data previously in these sections will 115 most likely result in an oops. 116 In the code functions and variables are annotated with 117 __init, __devinit etc. (see full list in include/linux/init.h) 118 which results in the code/data being placed in specific sections. 119 The section mismatch analysis is always done after a full 120 kernel build but enabling this option will in addition 121 do the following: 122 - Add the option -fno-inline-functions-called-once to gcc 123 When inlining a function annotated __init in a non-init 124 function we would lose the section information and thus 125 the analysis would not catch the illegal reference. 126 This option tells gcc to inline less but will also 127 result in a larger kernel. 128 - Run the section mismatch analysis for each module/built-in.o 129 When we run the section mismatch analysis on vmlinux.o we 130 lose valueble information about where the mismatch was 131 introduced. 132 Running the analysis for each module/built-in.o file 133 will tell where the mismatch happens much closer to the 134 source. The drawback is that we will report the same 135 mismatch at least twice. 136 - Enable verbose reporting from modpost to help solving 137 the section mismatches reported. 138 139config DEBUG_KERNEL 140 bool "Kernel debugging" 141 help 142 Say Y here if you are developing drivers or trying to debug and 143 identify kernel problems. 144 145config DEBUG_SHIRQ 146 bool "Debug shared IRQ handlers" 147 depends on DEBUG_KERNEL && GENERIC_HARDIRQS 148 help 149 Enable this to generate a spurious interrupt as soon as a shared 150 interrupt handler is registered, and just before one is deregistered. 151 Drivers ought to be able to handle interrupts coming in at those 152 points; some don't and need to be caught. 153 154config LOCKUP_DETECTOR 155 bool "Detect Hard and Soft Lockups" 156 depends on DEBUG_KERNEL && !S390 157 help 158 Say Y here to enable the kernel to act as a watchdog to detect 159 hard and soft lockups. 160 161 Softlockups are bugs that cause the kernel to loop in kernel 162 mode for more than 60 seconds, without giving other tasks a 163 chance to run. The current stack trace is displayed upon 164 detection and the system will stay locked up. 165 166 Hardlockups are bugs that cause the CPU to loop in kernel mode 167 for more than 60 seconds, without letting other interrupts have a 168 chance to run. The current stack trace is displayed upon detection 169 and the system will stay locked up. 170 171 The overhead should be minimal. A periodic hrtimer runs to 172 generate interrupts and kick the watchdog task every 10-12 seconds. 173 An NMI is generated every 60 seconds or so to check for hardlockups. 174 175config HARDLOCKUP_DETECTOR 176 def_bool LOCKUP_DETECTOR && PERF_EVENTS && HAVE_PERF_EVENTS_NMI 177 178config BOOTPARAM_SOFTLOCKUP_PANIC 179 bool "Panic (Reboot) On Soft Lockups" 180 depends on LOCKUP_DETECTOR 181 help 182 Say Y here to enable the kernel to panic on "soft lockups", 183 which are bugs that cause the kernel to loop in kernel 184 mode for more than 60 seconds, without giving other tasks a 185 chance to run. 186 187 The panic can be used in combination with panic_timeout, 188 to cause the system to reboot automatically after a 189 lockup has been detected. This feature is useful for 190 high-availability systems that have uptime guarantees and 191 where a lockup must be resolved ASAP. 192 193 Say N if unsure. 194 195config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE 196 int 197 depends on LOCKUP_DETECTOR 198 range 0 1 199 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC 200 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC 201 202config DETECT_HUNG_TASK 203 bool "Detect Hung Tasks" 204 depends on DEBUG_KERNEL 205 default DETECT_SOFTLOCKUP 206 help 207 Say Y here to enable the kernel to detect "hung tasks", 208 which are bugs that cause the task to be stuck in 209 uninterruptible "D" state indefinitiley. 210 211 When a hung task is detected, the kernel will print the 212 current stack trace (which you should report), but the 213 task will stay in uninterruptible state. If lockdep is 214 enabled then all held locks will also be reported. This 215 feature has negligible overhead. 216 217config BOOTPARAM_HUNG_TASK_PANIC 218 bool "Panic (Reboot) On Hung Tasks" 219 depends on DETECT_HUNG_TASK 220 help 221 Say Y here to enable the kernel to panic on "hung tasks", 222 which are bugs that cause the kernel to leave a task stuck 223 in uninterruptible "D" state. 224 225 The panic can be used in combination with panic_timeout, 226 to cause the system to reboot automatically after a 227 hung task has been detected. This feature is useful for 228 high-availability systems that have uptime guarantees and 229 where a hung tasks must be resolved ASAP. 230 231 Say N if unsure. 232 233config BOOTPARAM_HUNG_TASK_PANIC_VALUE 234 int 235 depends on DETECT_HUNG_TASK 236 range 0 1 237 default 0 if !BOOTPARAM_HUNG_TASK_PANIC 238 default 1 if BOOTPARAM_HUNG_TASK_PANIC 239 240config SCHED_DEBUG 241 bool "Collect scheduler debugging info" 242 depends on DEBUG_KERNEL && PROC_FS 243 default y 244 help 245 If you say Y here, the /proc/sched_debug file will be provided 246 that can help debug the scheduler. The runtime overhead of this 247 option is minimal. 248 249config SCHEDSTATS 250 bool "Collect scheduler statistics" 251 depends on DEBUG_KERNEL && PROC_FS 252 help 253 If you say Y here, additional code will be inserted into the 254 scheduler and related routines to collect statistics about 255 scheduler behavior and provide them in /proc/schedstat. These 256 stats may be useful for both tuning and debugging the scheduler 257 If you aren't debugging the scheduler or trying to tune a specific 258 application, you can say N to avoid the very slight overhead 259 this adds. 260 261config TIMER_STATS 262 bool "Collect kernel timers statistics" 263 depends on DEBUG_KERNEL && PROC_FS 264 help 265 If you say Y here, additional code will be inserted into the 266 timer routines to collect statistics about kernel timers being 267 reprogrammed. The statistics can be read from /proc/timer_stats. 268 The statistics collection is started by writing 1 to /proc/timer_stats, 269 writing 0 stops it. This feature is useful to collect information 270 about timer usage patterns in kernel and userspace. This feature 271 is lightweight if enabled in the kernel config but not activated 272 (it defaults to deactivated on bootup and will only be activated 273 if some application like powertop activates it explicitly). 274 275config DEBUG_OBJECTS 276 bool "Debug object operations" 277 depends on DEBUG_KERNEL 278 help 279 If you say Y here, additional code will be inserted into the 280 kernel to track the life time of various objects and validate 281 the operations on those objects. 282 283config DEBUG_OBJECTS_SELFTEST 284 bool "Debug objects selftest" 285 depends on DEBUG_OBJECTS 286 help 287 This enables the selftest of the object debug code. 288 289config DEBUG_OBJECTS_FREE 290 bool "Debug objects in freed memory" 291 depends on DEBUG_OBJECTS 292 help 293 This enables checks whether a k/v free operation frees an area 294 which contains an object which has not been deactivated 295 properly. This can make kmalloc/kfree-intensive workloads 296 much slower. 297 298config DEBUG_OBJECTS_TIMERS 299 bool "Debug timer objects" 300 depends on DEBUG_OBJECTS 301 help 302 If you say Y here, additional code will be inserted into the 303 timer routines to track the life time of timer objects and 304 validate the timer operations. 305 306config DEBUG_OBJECTS_WORK 307 bool "Debug work objects" 308 depends on DEBUG_OBJECTS 309 help 310 If you say Y here, additional code will be inserted into the 311 work queue routines to track the life time of work objects and 312 validate the work operations. 313 314config DEBUG_OBJECTS_RCU_HEAD 315 bool "Debug RCU callbacks objects" 316 depends on DEBUG_OBJECTS && PREEMPT 317 help 318 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 319 320config DEBUG_OBJECTS_ENABLE_DEFAULT 321 int "debug_objects bootup default value (0-1)" 322 range 0 1 323 default "1" 324 depends on DEBUG_OBJECTS 325 help 326 Debug objects boot parameter default value 327 328config DEBUG_SLAB 329 bool "Debug slab memory allocations" 330 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK 331 help 332 Say Y here to have the kernel do limited verification on memory 333 allocation as well as poisoning memory on free to catch use of freed 334 memory. This can make kmalloc/kfree-intensive workloads much slower. 335 336config DEBUG_SLAB_LEAK 337 bool "Memory leak debugging" 338 depends on DEBUG_SLAB 339 340config SLUB_DEBUG_ON 341 bool "SLUB debugging on by default" 342 depends on SLUB && SLUB_DEBUG && !KMEMCHECK 343 default n 344 help 345 Boot with debugging on by default. SLUB boots by default with 346 the runtime debug capabilities switched off. Enabling this is 347 equivalent to specifying the "slub_debug" parameter on boot. 348 There is no support for more fine grained debug control like 349 possible with slub_debug=xxx. SLUB debugging may be switched 350 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying 351 "slub_debug=-". 352 353config SLUB_STATS 354 default n 355 bool "Enable SLUB performance statistics" 356 depends on SLUB && SLUB_DEBUG && SYSFS 357 help 358 SLUB statistics are useful to debug SLUBs allocation behavior in 359 order find ways to optimize the allocator. This should never be 360 enabled for production use since keeping statistics slows down 361 the allocator by a few percentage points. The slabinfo command 362 supports the determination of the most active slabs to figure 363 out which slabs are relevant to a particular load. 364 Try running: slabinfo -DA 365 366config DEBUG_KMEMLEAK 367 bool "Kernel memory leak detector" 368 depends on DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && \ 369 (X86 || ARM || PPC || S390 || SPARC64 || SUPERH || MICROBLAZE) 370 371 select DEBUG_FS if SYSFS 372 select STACKTRACE if STACKTRACE_SUPPORT 373 select KALLSYMS 374 select CRC32 375 help 376 Say Y here if you want to enable the memory leak 377 detector. The memory allocation/freeing is traced in a way 378 similar to the Boehm's conservative garbage collector, the 379 difference being that the orphan objects are not freed but 380 only shown in /sys/kernel/debug/kmemleak. Enabling this 381 feature will introduce an overhead to memory 382 allocations. See Documentation/kmemleak.txt for more 383 details. 384 385 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances 386 of finding leaks due to the slab objects poisoning. 387 388 In order to access the kmemleak file, debugfs needs to be 389 mounted (usually at /sys/kernel/debug). 390 391config DEBUG_KMEMLEAK_EARLY_LOG_SIZE 392 int "Maximum kmemleak early log entries" 393 depends on DEBUG_KMEMLEAK 394 range 200 40000 395 default 400 396 help 397 Kmemleak must track all the memory allocations to avoid 398 reporting false positives. Since memory may be allocated or 399 freed before kmemleak is initialised, an early log buffer is 400 used to store these actions. If kmemleak reports "early log 401 buffer exceeded", please increase this value. 402 403config DEBUG_KMEMLEAK_TEST 404 tristate "Simple test for the kernel memory leak detector" 405 depends on DEBUG_KMEMLEAK 406 help 407 Say Y or M here to build a test for the kernel memory leak 408 detector. This option enables a module that explicitly leaks 409 memory. 410 411 If unsure, say N. 412 413config DEBUG_KMEMLEAK_DEFAULT_OFF 414 bool "Default kmemleak to off" 415 depends on DEBUG_KMEMLEAK 416 help 417 Say Y here to disable kmemleak by default. It can then be enabled 418 on the command line via kmemleak=on. 419 420config DEBUG_PREEMPT 421 bool "Debug preemptible kernel" 422 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT 423 default y 424 help 425 If you say Y here then the kernel will use a debug variant of the 426 commonly used smp_processor_id() function and will print warnings 427 if kernel code uses it in a preemption-unsafe way. Also, the kernel 428 will detect preemption count underflows. 429 430config DEBUG_RT_MUTEXES 431 bool "RT Mutex debugging, deadlock detection" 432 depends on DEBUG_KERNEL && RT_MUTEXES 433 help 434 This allows rt mutex semantics violations and rt mutex related 435 deadlocks (lockups) to be detected and reported automatically. 436 437config DEBUG_PI_LIST 438 bool 439 default y 440 depends on DEBUG_RT_MUTEXES 441 442config RT_MUTEX_TESTER 443 bool "Built-in scriptable tester for rt-mutexes" 444 depends on DEBUG_KERNEL && RT_MUTEXES 445 help 446 This option enables a rt-mutex tester. 447 448config DEBUG_SPINLOCK 449 bool "Spinlock and rw-lock debugging: basic checks" 450 depends on DEBUG_KERNEL 451 help 452 Say Y here and build SMP to catch missing spinlock initialization 453 and certain other kinds of spinlock errors commonly made. This is 454 best used in conjunction with the NMI watchdog so that spinlock 455 deadlocks are also debuggable. 456 457config DEBUG_MUTEXES 458 bool "Mutex debugging: basic checks" 459 depends on DEBUG_KERNEL 460 help 461 This feature allows mutex semantics violations to be detected and 462 reported. 463 464config DEBUG_LOCK_ALLOC 465 bool "Lock debugging: detect incorrect freeing of live locks" 466 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 467 select DEBUG_SPINLOCK 468 select DEBUG_MUTEXES 469 select LOCKDEP 470 help 471 This feature will check whether any held lock (spinlock, rwlock, 472 mutex or rwsem) is incorrectly freed by the kernel, via any of the 473 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 474 vfree(), etc.), whether a live lock is incorrectly reinitialized via 475 spin_lock_init()/mutex_init()/etc., or whether there is any lock 476 held during task exit. 477 478config PROVE_LOCKING 479 bool "Lock debugging: prove locking correctness" 480 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 481 select LOCKDEP 482 select DEBUG_SPINLOCK 483 select DEBUG_MUTEXES 484 select DEBUG_LOCK_ALLOC 485 select TRACE_IRQFLAGS 486 default n 487 help 488 This feature enables the kernel to prove that all locking 489 that occurs in the kernel runtime is mathematically 490 correct: that under no circumstance could an arbitrary (and 491 not yet triggered) combination of observed locking 492 sequences (on an arbitrary number of CPUs, running an 493 arbitrary number of tasks and interrupt contexts) cause a 494 deadlock. 495 496 In short, this feature enables the kernel to report locking 497 related deadlocks before they actually occur. 498 499 The proof does not depend on how hard and complex a 500 deadlock scenario would be to trigger: how many 501 participant CPUs, tasks and irq-contexts would be needed 502 for it to trigger. The proof also does not depend on 503 timing: if a race and a resulting deadlock is possible 504 theoretically (no matter how unlikely the race scenario 505 is), it will be proven so and will immediately be 506 reported by the kernel (once the event is observed that 507 makes the deadlock theoretically possible). 508 509 If a deadlock is impossible (i.e. the locking rules, as 510 observed by the kernel, are mathematically correct), the 511 kernel reports nothing. 512 513 NOTE: this feature can also be enabled for rwlocks, mutexes 514 and rwsems - in which case all dependencies between these 515 different locking variants are observed and mapped too, and 516 the proof of observed correctness is also maintained for an 517 arbitrary combination of these separate locking variants. 518 519 For more details, see Documentation/lockdep-design.txt. 520 521config PROVE_RCU 522 bool "RCU debugging: prove RCU correctness" 523 depends on PROVE_LOCKING 524 default n 525 help 526 This feature enables lockdep extensions that check for correct 527 use of RCU APIs. This is currently under development. Say Y 528 if you want to debug RCU usage or help work on the PROVE_RCU 529 feature. 530 531 Say N if you are unsure. 532 533config PROVE_RCU_REPEATEDLY 534 bool "RCU debugging: don't disable PROVE_RCU on first splat" 535 depends on PROVE_RCU 536 default n 537 help 538 By itself, PROVE_RCU will disable checking upon issuing the 539 first warning (or "splat"). This feature prevents such 540 disabling, allowing multiple RCU-lockdep warnings to be printed 541 on a single reboot. 542 543 Say Y to allow multiple RCU-lockdep warnings per boot. 544 545 Say N if you are unsure. 546 547config SPARSE_RCU_POINTER 548 bool "RCU debugging: sparse-based checks for pointer usage" 549 default n 550 help 551 This feature enables the __rcu sparse annotation for 552 RCU-protected pointers. This annotation will cause sparse 553 to flag any non-RCU used of annotated pointers. This can be 554 helpful when debugging RCU usage. Please note that this feature 555 is not intended to enforce code cleanliness; it is instead merely 556 a debugging aid. 557 558 Say Y to make sparse flag questionable use of RCU-protected pointers 559 560 Say N if you are unsure. 561 562config LOCKDEP 563 bool 564 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 565 select STACKTRACE 566 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE 567 select KALLSYMS 568 select KALLSYMS_ALL 569 570config LOCK_STAT 571 bool "Lock usage statistics" 572 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 573 select LOCKDEP 574 select DEBUG_SPINLOCK 575 select DEBUG_MUTEXES 576 select DEBUG_LOCK_ALLOC 577 default n 578 help 579 This feature enables tracking lock contention points 580 581 For more details, see Documentation/lockstat.txt 582 583 This also enables lock events required by "perf lock", 584 subcommand of perf. 585 If you want to use "perf lock", you also need to turn on 586 CONFIG_EVENT_TRACING. 587 588 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 589 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 590 591config DEBUG_LOCKDEP 592 bool "Lock dependency engine debugging" 593 depends on DEBUG_KERNEL && LOCKDEP 594 help 595 If you say Y here, the lock dependency engine will do 596 additional runtime checks to debug itself, at the price 597 of more runtime overhead. 598 599config TRACE_IRQFLAGS 600 bool 601 help 602 Enables hooks to interrupt enabling and disabling for 603 either tracing or lock debugging. 604 605config DEBUG_SPINLOCK_SLEEP 606 bool "Spinlock debugging: sleep-inside-spinlock checking" 607 depends on DEBUG_KERNEL 608 help 609 If you say Y here, various routines which may sleep will become very 610 noisy if they are called with a spinlock held. 611 612config DEBUG_LOCKING_API_SELFTESTS 613 bool "Locking API boot-time self-tests" 614 depends on DEBUG_KERNEL 615 help 616 Say Y here if you want the kernel to run a short self-test during 617 bootup. The self-test checks whether common types of locking bugs 618 are detected by debugging mechanisms or not. (if you disable 619 lock debugging then those bugs wont be detected of course.) 620 The following locking APIs are covered: spinlocks, rwlocks, 621 mutexes and rwsems. 622 623config STACKTRACE 624 bool 625 depends on STACKTRACE_SUPPORT 626 627config DEBUG_KOBJECT 628 bool "kobject debugging" 629 depends on DEBUG_KERNEL 630 help 631 If you say Y here, some extra kobject debugging messages will be sent 632 to the syslog. 633 634config DEBUG_HIGHMEM 635 bool "Highmem debugging" 636 depends on DEBUG_KERNEL && HIGHMEM 637 help 638 This options enables addition error checking for high memory systems. 639 Disable for production systems. 640 641config DEBUG_BUGVERBOSE 642 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED 643 depends on BUG 644 depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \ 645 FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300 646 default y 647 help 648 Say Y here to make BUG() panics output the file name and line number 649 of the BUG call as well as the EIP and oops trace. This aids 650 debugging but costs about 70-100K of memory. 651 652config DEBUG_INFO 653 bool "Compile the kernel with debug info" 654 depends on DEBUG_KERNEL 655 help 656 If you say Y here the resulting kernel image will include 657 debugging info resulting in a larger kernel image. 658 This adds debug symbols to the kernel and modules (gcc -g), and 659 is needed if you intend to use kernel crashdump or binary object 660 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 661 Say Y here only if you plan to debug the kernel. 662 663 If unsure, say N. 664 665config DEBUG_INFO_REDUCED 666 bool "Reduce debugging information" 667 depends on DEBUG_INFO 668 help 669 If you say Y here gcc is instructed to generate less debugging 670 information for structure types. This means that tools that 671 need full debugging information (like kgdb or systemtap) won't 672 be happy. But if you merely need debugging information to 673 resolve line numbers there is no loss. Advantage is that 674 build directory object sizes shrink dramatically over a full 675 DEBUG_INFO build and compile times are reduced too. 676 Only works with newer gcc versions. 677 678config DEBUG_VM 679 bool "Debug VM" 680 depends on DEBUG_KERNEL 681 help 682 Enable this to turn on extended checks in the virtual-memory system 683 that may impact performance. 684 685 If unsure, say N. 686 687config DEBUG_VIRTUAL 688 bool "Debug VM translations" 689 depends on DEBUG_KERNEL && X86 690 help 691 Enable some costly sanity checks in virtual to page code. This can 692 catch mistakes with virt_to_page() and friends. 693 694 If unsure, say N. 695 696config DEBUG_NOMMU_REGIONS 697 bool "Debug the global anon/private NOMMU mapping region tree" 698 depends on DEBUG_KERNEL && !MMU 699 help 700 This option causes the global tree of anonymous and private mapping 701 regions to be regularly checked for invalid topology. 702 703config DEBUG_WRITECOUNT 704 bool "Debug filesystem writers count" 705 depends on DEBUG_KERNEL 706 help 707 Enable this to catch wrong use of the writers count in struct 708 vfsmount. This will increase the size of each file struct by 709 32 bits. 710 711 If unsure, say N. 712 713config DEBUG_MEMORY_INIT 714 bool "Debug memory initialisation" if EMBEDDED 715 default !EMBEDDED 716 help 717 Enable this for additional checks during memory initialisation. 718 The sanity checks verify aspects of the VM such as the memory model 719 and other information provided by the architecture. Verbose 720 information will be printed at KERN_DEBUG loglevel depending 721 on the mminit_loglevel= command-line option. 722 723 If unsure, say Y 724 725config DEBUG_LIST 726 bool "Debug linked list manipulation" 727 depends on DEBUG_KERNEL 728 help 729 Enable this to turn on extended checks in the linked-list 730 walking routines. 731 732 If unsure, say N. 733 734config DEBUG_SG 735 bool "Debug SG table operations" 736 depends on DEBUG_KERNEL 737 help 738 Enable this to turn on checks on scatter-gather tables. This can 739 help find problems with drivers that do not properly initialize 740 their sg tables. 741 742 If unsure, say N. 743 744config DEBUG_NOTIFIERS 745 bool "Debug notifier call chains" 746 depends on DEBUG_KERNEL 747 help 748 Enable this to turn on sanity checking for notifier call chains. 749 This is most useful for kernel developers to make sure that 750 modules properly unregister themselves from notifier chains. 751 This is a relatively cheap check but if you care about maximum 752 performance, say N. 753 754config DEBUG_CREDENTIALS 755 bool "Debug credential management" 756 depends on DEBUG_KERNEL 757 help 758 Enable this to turn on some debug checking for credential 759 management. The additional code keeps track of the number of 760 pointers from task_structs to any given cred struct, and checks to 761 see that this number never exceeds the usage count of the cred 762 struct. 763 764 Furthermore, if SELinux is enabled, this also checks that the 765 security pointer in the cred struct is never seen to be invalid. 766 767 If unsure, say N. 768 769# 770# Select this config option from the architecture Kconfig, if it 771# it is preferred to always offer frame pointers as a config 772# option on the architecture (regardless of KERNEL_DEBUG): 773# 774config ARCH_WANT_FRAME_POINTERS 775 bool 776 help 777 778config FRAME_POINTER 779 bool "Compile the kernel with frame pointers" 780 depends on DEBUG_KERNEL && \ 781 (CRIS || M68K || M68KNOMMU || FRV || UML || \ 782 AVR32 || SUPERH || BLACKFIN || MN10300) || \ 783 ARCH_WANT_FRAME_POINTERS 784 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 785 help 786 If you say Y here the resulting kernel image will be slightly 787 larger and slower, but it gives very useful debugging information 788 in case of kernel bugs. (precise oopses/stacktraces/warnings) 789 790config BOOT_PRINTK_DELAY 791 bool "Delay each boot printk message by N milliseconds" 792 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY 793 help 794 This build option allows you to read kernel boot messages 795 by inserting a short delay after each one. The delay is 796 specified in milliseconds on the kernel command line, 797 using "boot_delay=N". 798 799 It is likely that you would also need to use "lpj=M" to preset 800 the "loops per jiffie" value. 801 See a previous boot log for the "lpj" value to use for your 802 system, and then set "lpj=M" before setting "boot_delay=N". 803 NOTE: Using this option may adversely affect SMP systems. 804 I.e., processors other than the first one may not boot up. 805 BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect 806 what it believes to be lockup conditions. 807 808config RCU_TORTURE_TEST 809 tristate "torture tests for RCU" 810 depends on DEBUG_KERNEL 811 default n 812 help 813 This option provides a kernel module that runs torture tests 814 on the RCU infrastructure. The kernel module may be built 815 after the fact on the running kernel to be tested, if desired. 816 817 Say Y here if you want RCU torture tests to be built into 818 the kernel. 819 Say M if you want the RCU torture tests to build as a module. 820 Say N if you are unsure. 821 822config RCU_TORTURE_TEST_RUNNABLE 823 bool "torture tests for RCU runnable by default" 824 depends on RCU_TORTURE_TEST = y 825 default n 826 help 827 This option provides a way to build the RCU torture tests 828 directly into the kernel without them starting up at boot 829 time. You can use /proc/sys/kernel/rcutorture_runnable 830 to manually override this setting. This /proc file is 831 available only when the RCU torture tests have been built 832 into the kernel. 833 834 Say Y here if you want the RCU torture tests to start during 835 boot (you probably don't). 836 Say N here if you want the RCU torture tests to start only 837 after being manually enabled via /proc. 838 839config RCU_CPU_STALL_DETECTOR 840 bool "Check for stalled CPUs delaying RCU grace periods" 841 depends on TREE_RCU || TREE_PREEMPT_RCU 842 default y 843 help 844 This option causes RCU to printk information on which 845 CPUs are delaying the current grace period, but only when 846 the grace period extends for excessive time periods. 847 848 Say N if you want to disable such checks. 849 850 Say Y if you are unsure. 851 852config RCU_CPU_STALL_TIMEOUT 853 int "RCU CPU stall timeout in seconds" 854 depends on RCU_CPU_STALL_DETECTOR 855 range 3 300 856 default 60 857 help 858 If a given RCU grace period extends more than the specified 859 number of seconds, a CPU stall warning is printed. If the 860 RCU grace period persists, additional CPU stall warnings are 861 printed at more widely spaced intervals. 862 863config RCU_CPU_STALL_DETECTOR_RUNNABLE 864 bool "RCU CPU stall checking starts automatically at boot" 865 depends on RCU_CPU_STALL_DETECTOR 866 default y 867 help 868 If set, start checking for RCU CPU stalls immediately on 869 boot. Otherwise, RCU CPU stall checking must be manually 870 enabled. 871 872 Say Y if you are unsure. 873 874 Say N if you wish to suppress RCU CPU stall checking during boot. 875 876config RCU_CPU_STALL_VERBOSE 877 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR" 878 depends on RCU_CPU_STALL_DETECTOR && TREE_PREEMPT_RCU 879 default y 880 help 881 This option causes RCU to printk detailed per-task information 882 for any tasks that are stalling the current RCU grace period. 883 884 Say N if you are unsure. 885 886 Say Y if you want to enable such checks. 887 888config KPROBES_SANITY_TEST 889 bool "Kprobes sanity tests" 890 depends on DEBUG_KERNEL 891 depends on KPROBES 892 default n 893 help 894 This option provides for testing basic kprobes functionality on 895 boot. A sample kprobe, jprobe and kretprobe are inserted and 896 verified for functionality. 897 898 Say N if you are unsure. 899 900config BACKTRACE_SELF_TEST 901 tristate "Self test for the backtrace code" 902 depends on DEBUG_KERNEL 903 default n 904 help 905 This option provides a kernel module that can be used to test 906 the kernel stack backtrace code. This option is not useful 907 for distributions or general kernels, but only for kernel 908 developers working on architecture code. 909 910 Note that if you want to also test saved backtraces, you will 911 have to enable STACKTRACE as well. 912 913 Say N if you are unsure. 914 915config DEBUG_BLOCK_EXT_DEVT 916 bool "Force extended block device numbers and spread them" 917 depends on DEBUG_KERNEL 918 depends on BLOCK 919 default n 920 help 921 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON 922 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT 923 YOU ARE DOING. Distros, please enable this and fix whatever 924 is broken. 925 926 Conventionally, block device numbers are allocated from 927 predetermined contiguous area. However, extended block area 928 may introduce non-contiguous block device numbers. This 929 option forces most block device numbers to be allocated from 930 the extended space and spreads them to discover kernel or 931 userland code paths which assume predetermined contiguous 932 device number allocation. 933 934 Note that turning on this debug option shuffles all the 935 device numbers for all IDE and SCSI devices including libata 936 ones, so root partition specified using device number 937 directly (via rdev or root=MAJ:MIN) won't work anymore. 938 Textual device names (root=/dev/sdXn) will continue to work. 939 940 Say N if you are unsure. 941 942config DEBUG_FORCE_WEAK_PER_CPU 943 bool "Force weak per-cpu definitions" 944 depends on DEBUG_KERNEL 945 help 946 s390 and alpha require percpu variables in modules to be 947 defined weak to work around addressing range issue which 948 puts the following two restrictions on percpu variable 949 definitions. 950 951 1. percpu symbols must be unique whether static or not 952 2. percpu variables can't be defined inside a function 953 954 To ensure that generic code follows the above rules, this 955 option forces all percpu variables to be defined as weak. 956 957config LKDTM 958 tristate "Linux Kernel Dump Test Tool Module" 959 depends on DEBUG_FS 960 depends on BLOCK 961 default n 962 help 963 This module enables testing of the different dumping mechanisms by 964 inducing system failures at predefined crash points. 965 If you don't need it: say N 966 Choose M here to compile this code as a module. The module will be 967 called lkdtm. 968 969 Documentation on how to use the module can be found in 970 Documentation/fault-injection/provoke-crashes.txt 971 972config CPU_NOTIFIER_ERROR_INJECT 973 tristate "CPU notifier error injection module" 974 depends on HOTPLUG_CPU && DEBUG_KERNEL 975 help 976 This option provides a kernel module that can be used to test 977 the error handling of the cpu notifiers 978 979 To compile this code as a module, choose M here: the module will 980 be called cpu-notifier-error-inject. 981 982 If unsure, say N. 983 984config FAULT_INJECTION 985 bool "Fault-injection framework" 986 depends on DEBUG_KERNEL 987 help 988 Provide fault-injection framework. 989 For more details, see Documentation/fault-injection/. 990 991config FAILSLAB 992 bool "Fault-injection capability for kmalloc" 993 depends on FAULT_INJECTION 994 depends on SLAB || SLUB 995 help 996 Provide fault-injection capability for kmalloc. 997 998config FAIL_PAGE_ALLOC 999 bool "Fault-injection capabilitiy for alloc_pages()" 1000 depends on FAULT_INJECTION 1001 help 1002 Provide fault-injection capability for alloc_pages(). 1003 1004config FAIL_MAKE_REQUEST 1005 bool "Fault-injection capability for disk IO" 1006 depends on FAULT_INJECTION && BLOCK 1007 help 1008 Provide fault-injection capability for disk IO. 1009 1010config FAIL_IO_TIMEOUT 1011 bool "Fault-injection capability for faking disk interrupts" 1012 depends on FAULT_INJECTION && BLOCK 1013 help 1014 Provide fault-injection capability on end IO handling. This 1015 will make the block layer "forget" an interrupt as configured, 1016 thus exercising the error handling. 1017 1018 Only works with drivers that use the generic timeout handling, 1019 for others it wont do anything. 1020 1021config FAULT_INJECTION_DEBUG_FS 1022 bool "Debugfs entries for fault-injection capabilities" 1023 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 1024 help 1025 Enable configuration of fault-injection capabilities via debugfs. 1026 1027config FAULT_INJECTION_STACKTRACE_FILTER 1028 bool "stacktrace filter for fault-injection capabilities" 1029 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 1030 depends on !X86_64 1031 select STACKTRACE 1032 select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE 1033 help 1034 Provide stacktrace filter for fault-injection capabilities 1035 1036config LATENCYTOP 1037 bool "Latency measuring infrastructure" 1038 depends on HAVE_LATENCYTOP_SUPPORT 1039 depends on DEBUG_KERNEL 1040 depends on STACKTRACE_SUPPORT 1041 depends on PROC_FS 1042 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE 1043 select KALLSYMS 1044 select KALLSYMS_ALL 1045 select STACKTRACE 1046 select SCHEDSTATS 1047 select SCHED_DEBUG 1048 help 1049 Enable this option if you want to use the LatencyTOP tool 1050 to find out which userspace is blocking on what kernel operations. 1051 1052config SYSCTL_SYSCALL_CHECK 1053 bool "Sysctl checks" 1054 depends on SYSCTL 1055 ---help--- 1056 sys_sysctl uses binary paths that have been found challenging 1057 to properly maintain and use. This enables checks that help 1058 you to keep things correct. 1059 1060source mm/Kconfig.debug 1061source kernel/trace/Kconfig 1062 1063config PROVIDE_OHCI1394_DMA_INIT 1064 bool "Remote debugging over FireWire early on boot" 1065 depends on PCI && X86 1066 help 1067 If you want to debug problems which hang or crash the kernel early 1068 on boot and the crashing machine has a FireWire port, you can use 1069 this feature to remotely access the memory of the crashed machine 1070 over FireWire. This employs remote DMA as part of the OHCI1394 1071 specification which is now the standard for FireWire controllers. 1072 1073 With remote DMA, you can monitor the printk buffer remotely using 1074 firescope and access all memory below 4GB using fireproxy from gdb. 1075 Even controlling a kernel debugger is possible using remote DMA. 1076 1077 Usage: 1078 1079 If ohci1394_dma=early is used as boot parameter, it will initialize 1080 all OHCI1394 controllers which are found in the PCI config space. 1081 1082 As all changes to the FireWire bus such as enabling and disabling 1083 devices cause a bus reset and thereby disable remote DMA for all 1084 devices, be sure to have the cable plugged and FireWire enabled on 1085 the debugging host before booting the debug target for debugging. 1086 1087 This code (~1k) is freed after boot. By then, the firewire stack 1088 in charge of the OHCI-1394 controllers should be used instead. 1089 1090 See Documentation/debugging-via-ohci1394.txt for more information. 1091 1092config FIREWIRE_OHCI_REMOTE_DMA 1093 bool "Remote debugging over FireWire with firewire-ohci" 1094 depends on FIREWIRE_OHCI 1095 help 1096 This option lets you use the FireWire bus for remote debugging 1097 with help of the firewire-ohci driver. It enables unfiltered 1098 remote DMA in firewire-ohci. 1099 See Documentation/debugging-via-ohci1394.txt for more information. 1100 1101 If unsure, say N. 1102 1103config BUILD_DOCSRC 1104 bool "Build targets in Documentation/ tree" 1105 depends on HEADERS_CHECK 1106 help 1107 This option attempts to build objects from the source files in the 1108 kernel Documentation/ tree. 1109 1110 Say N if you are unsure. 1111 1112config DYNAMIC_DEBUG 1113 bool "Enable dynamic printk() support" 1114 default n 1115 depends on PRINTK 1116 depends on DEBUG_FS 1117 help 1118 1119 Compiles debug level messages into the kernel, which would not 1120 otherwise be available at runtime. These messages can then be 1121 enabled/disabled based on various levels of scope - per source file, 1122 function, module, format string, and line number. This mechanism 1123 implicitly enables all pr_debug() and dev_dbg() calls. The impact of 1124 this compile option is a larger kernel text size of about 2%. 1125 1126 Usage: 1127 1128 Dynamic debugging is controlled via the 'dynamic_debug/control' file, 1129 which is contained in the 'debugfs' filesystem. Thus, the debugfs 1130 filesystem must first be mounted before making use of this feature. 1131 We refer the control file as: <debugfs>/dynamic_debug/control. This 1132 file contains a list of the debug statements that can be enabled. The 1133 format for each line of the file is: 1134 1135 filename:lineno [module]function flags format 1136 1137 filename : source file of the debug statement 1138 lineno : line number of the debug statement 1139 module : module that contains the debug statement 1140 function : function that contains the debug statement 1141 flags : 'p' means the line is turned 'on' for printing 1142 format : the format used for the debug statement 1143 1144 From a live system: 1145 1146 nullarbor:~ # cat <debugfs>/dynamic_debug/control 1147 # filename:lineno [module]function flags format 1148 fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012" 1149 fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012" 1150 fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012" 1151 1152 Example usage: 1153 1154 // enable the message at line 1603 of file svcsock.c 1155 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' > 1156 <debugfs>/dynamic_debug/control 1157 1158 // enable all the messages in file svcsock.c 1159 nullarbor:~ # echo -n 'file svcsock.c +p' > 1160 <debugfs>/dynamic_debug/control 1161 1162 // enable all the messages in the NFS server module 1163 nullarbor:~ # echo -n 'module nfsd +p' > 1164 <debugfs>/dynamic_debug/control 1165 1166 // enable all 12 messages in the function svc_process() 1167 nullarbor:~ # echo -n 'func svc_process +p' > 1168 <debugfs>/dynamic_debug/control 1169 1170 // disable all 12 messages in the function svc_process() 1171 nullarbor:~ # echo -n 'func svc_process -p' > 1172 <debugfs>/dynamic_debug/control 1173 1174 See Documentation/dynamic-debug-howto.txt for additional information. 1175 1176config DMA_API_DEBUG 1177 bool "Enable debugging of DMA-API usage" 1178 depends on HAVE_DMA_API_DEBUG 1179 help 1180 Enable this option to debug the use of the DMA API by device drivers. 1181 With this option you will be able to detect common bugs in device 1182 drivers like double-freeing of DMA mappings or freeing mappings that 1183 were never allocated. 1184 This option causes a performance degredation. Use only if you want 1185 to debug device drivers. If unsure, say N. 1186 1187config ATOMIC64_SELFTEST 1188 bool "Perform an atomic64_t self-test at boot" 1189 help 1190 Enable this option to test the atomic64_t functions at boot. 1191 1192 If unsure, say N. 1193 1194source "samples/Kconfig" 1195 1196source "lib/Kconfig.kgdb" 1197 1198source "lib/Kconfig.kmemcheck" 1199