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 && 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 BKL 465 bool "Big Kernel Lock" if (SMP || PREEMPT) 466 default y 467 help 468 This is the traditional lock that is used in old code instead 469 of proper locking. All drivers that use the BKL should depend 470 on this symbol. 471 Say Y here unless you are working on removing the BKL. 472 473config DEBUG_LOCK_ALLOC 474 bool "Lock debugging: detect incorrect freeing of live locks" 475 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 476 select DEBUG_SPINLOCK 477 select DEBUG_MUTEXES 478 select LOCKDEP 479 help 480 This feature will check whether any held lock (spinlock, rwlock, 481 mutex or rwsem) is incorrectly freed by the kernel, via any of the 482 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 483 vfree(), etc.), whether a live lock is incorrectly reinitialized via 484 spin_lock_init()/mutex_init()/etc., or whether there is any lock 485 held during task exit. 486 487config PROVE_LOCKING 488 bool "Lock debugging: prove locking correctness" 489 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 490 select LOCKDEP 491 select DEBUG_SPINLOCK 492 select DEBUG_MUTEXES 493 select DEBUG_LOCK_ALLOC 494 select TRACE_IRQFLAGS 495 default n 496 help 497 This feature enables the kernel to prove that all locking 498 that occurs in the kernel runtime is mathematically 499 correct: that under no circumstance could an arbitrary (and 500 not yet triggered) combination of observed locking 501 sequences (on an arbitrary number of CPUs, running an 502 arbitrary number of tasks and interrupt contexts) cause a 503 deadlock. 504 505 In short, this feature enables the kernel to report locking 506 related deadlocks before they actually occur. 507 508 The proof does not depend on how hard and complex a 509 deadlock scenario would be to trigger: how many 510 participant CPUs, tasks and irq-contexts would be needed 511 for it to trigger. The proof also does not depend on 512 timing: if a race and a resulting deadlock is possible 513 theoretically (no matter how unlikely the race scenario 514 is), it will be proven so and will immediately be 515 reported by the kernel (once the event is observed that 516 makes the deadlock theoretically possible). 517 518 If a deadlock is impossible (i.e. the locking rules, as 519 observed by the kernel, are mathematically correct), the 520 kernel reports nothing. 521 522 NOTE: this feature can also be enabled for rwlocks, mutexes 523 and rwsems - in which case all dependencies between these 524 different locking variants are observed and mapped too, and 525 the proof of observed correctness is also maintained for an 526 arbitrary combination of these separate locking variants. 527 528 For more details, see Documentation/lockdep-design.txt. 529 530config PROVE_RCU 531 bool "RCU debugging: prove RCU correctness" 532 depends on PROVE_LOCKING 533 default n 534 help 535 This feature enables lockdep extensions that check for correct 536 use of RCU APIs. This is currently under development. Say Y 537 if you want to debug RCU usage or help work on the PROVE_RCU 538 feature. 539 540 Say N if you are unsure. 541 542config PROVE_RCU_REPEATEDLY 543 bool "RCU debugging: don't disable PROVE_RCU on first splat" 544 depends on PROVE_RCU 545 default n 546 help 547 By itself, PROVE_RCU will disable checking upon issuing the 548 first warning (or "splat"). This feature prevents such 549 disabling, allowing multiple RCU-lockdep warnings to be printed 550 on a single reboot. 551 552 Say Y to allow multiple RCU-lockdep warnings per boot. 553 554 Say N if you are unsure. 555 556config SPARSE_RCU_POINTER 557 bool "RCU debugging: sparse-based checks for pointer usage" 558 default n 559 help 560 This feature enables the __rcu sparse annotation for 561 RCU-protected pointers. This annotation will cause sparse 562 to flag any non-RCU used of annotated pointers. This can be 563 helpful when debugging RCU usage. Please note that this feature 564 is not intended to enforce code cleanliness; it is instead merely 565 a debugging aid. 566 567 Say Y to make sparse flag questionable use of RCU-protected pointers 568 569 Say N if you are unsure. 570 571config LOCKDEP 572 bool 573 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 574 select STACKTRACE 575 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE 576 select KALLSYMS 577 select KALLSYMS_ALL 578 579config LOCK_STAT 580 bool "Lock usage statistics" 581 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 582 select LOCKDEP 583 select DEBUG_SPINLOCK 584 select DEBUG_MUTEXES 585 select DEBUG_LOCK_ALLOC 586 default n 587 help 588 This feature enables tracking lock contention points 589 590 For more details, see Documentation/lockstat.txt 591 592 This also enables lock events required by "perf lock", 593 subcommand of perf. 594 If you want to use "perf lock", you also need to turn on 595 CONFIG_EVENT_TRACING. 596 597 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 598 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 599 600config DEBUG_LOCKDEP 601 bool "Lock dependency engine debugging" 602 depends on DEBUG_KERNEL && LOCKDEP 603 help 604 If you say Y here, the lock dependency engine will do 605 additional runtime checks to debug itself, at the price 606 of more runtime overhead. 607 608config TRACE_IRQFLAGS 609 bool 610 help 611 Enables hooks to interrupt enabling and disabling for 612 either tracing or lock debugging. 613 614config DEBUG_SPINLOCK_SLEEP 615 bool "Spinlock debugging: sleep-inside-spinlock checking" 616 depends on DEBUG_KERNEL 617 help 618 If you say Y here, various routines which may sleep will become very 619 noisy if they are called with a spinlock held. 620 621config DEBUG_LOCKING_API_SELFTESTS 622 bool "Locking API boot-time self-tests" 623 depends on DEBUG_KERNEL 624 help 625 Say Y here if you want the kernel to run a short self-test during 626 bootup. The self-test checks whether common types of locking bugs 627 are detected by debugging mechanisms or not. (if you disable 628 lock debugging then those bugs wont be detected of course.) 629 The following locking APIs are covered: spinlocks, rwlocks, 630 mutexes and rwsems. 631 632config STACKTRACE 633 bool 634 depends on STACKTRACE_SUPPORT 635 636config DEBUG_KOBJECT 637 bool "kobject debugging" 638 depends on DEBUG_KERNEL 639 help 640 If you say Y here, some extra kobject debugging messages will be sent 641 to the syslog. 642 643config DEBUG_HIGHMEM 644 bool "Highmem debugging" 645 depends on DEBUG_KERNEL && HIGHMEM 646 help 647 This options enables addition error checking for high memory systems. 648 Disable for production systems. 649 650config DEBUG_BUGVERBOSE 651 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED 652 depends on BUG 653 depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \ 654 FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300 655 default y 656 help 657 Say Y here to make BUG() panics output the file name and line number 658 of the BUG call as well as the EIP and oops trace. This aids 659 debugging but costs about 70-100K of memory. 660 661config DEBUG_INFO 662 bool "Compile the kernel with debug info" 663 depends on DEBUG_KERNEL 664 help 665 If you say Y here the resulting kernel image will include 666 debugging info resulting in a larger kernel image. 667 This adds debug symbols to the kernel and modules (gcc -g), and 668 is needed if you intend to use kernel crashdump or binary object 669 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 670 Say Y here only if you plan to debug the kernel. 671 672 If unsure, say N. 673 674config DEBUG_INFO_REDUCED 675 bool "Reduce debugging information" 676 depends on DEBUG_INFO 677 help 678 If you say Y here gcc is instructed to generate less debugging 679 information for structure types. This means that tools that 680 need full debugging information (like kgdb or systemtap) won't 681 be happy. But if you merely need debugging information to 682 resolve line numbers there is no loss. Advantage is that 683 build directory object sizes shrink dramatically over a full 684 DEBUG_INFO build and compile times are reduced too. 685 Only works with newer gcc versions. 686 687config DEBUG_VM 688 bool "Debug VM" 689 depends on DEBUG_KERNEL 690 help 691 Enable this to turn on extended checks in the virtual-memory system 692 that may impact performance. 693 694 If unsure, say N. 695 696config DEBUG_VIRTUAL 697 bool "Debug VM translations" 698 depends on DEBUG_KERNEL && X86 699 help 700 Enable some costly sanity checks in virtual to page code. This can 701 catch mistakes with virt_to_page() and friends. 702 703 If unsure, say N. 704 705config DEBUG_NOMMU_REGIONS 706 bool "Debug the global anon/private NOMMU mapping region tree" 707 depends on DEBUG_KERNEL && !MMU 708 help 709 This option causes the global tree of anonymous and private mapping 710 regions to be regularly checked for invalid topology. 711 712config DEBUG_WRITECOUNT 713 bool "Debug filesystem writers count" 714 depends on DEBUG_KERNEL 715 help 716 Enable this to catch wrong use of the writers count in struct 717 vfsmount. This will increase the size of each file struct by 718 32 bits. 719 720 If unsure, say N. 721 722config DEBUG_MEMORY_INIT 723 bool "Debug memory initialisation" if EMBEDDED 724 default !EMBEDDED 725 help 726 Enable this for additional checks during memory initialisation. 727 The sanity checks verify aspects of the VM such as the memory model 728 and other information provided by the architecture. Verbose 729 information will be printed at KERN_DEBUG loglevel depending 730 on the mminit_loglevel= command-line option. 731 732 If unsure, say Y 733 734config DEBUG_LIST 735 bool "Debug linked list manipulation" 736 depends on DEBUG_KERNEL 737 help 738 Enable this to turn on extended checks in the linked-list 739 walking routines. 740 741 If unsure, say N. 742 743config DEBUG_SG 744 bool "Debug SG table operations" 745 depends on DEBUG_KERNEL 746 help 747 Enable this to turn on checks on scatter-gather tables. This can 748 help find problems with drivers that do not properly initialize 749 their sg tables. 750 751 If unsure, say N. 752 753config DEBUG_NOTIFIERS 754 bool "Debug notifier call chains" 755 depends on DEBUG_KERNEL 756 help 757 Enable this to turn on sanity checking for notifier call chains. 758 This is most useful for kernel developers to make sure that 759 modules properly unregister themselves from notifier chains. 760 This is a relatively cheap check but if you care about maximum 761 performance, say N. 762 763config DEBUG_CREDENTIALS 764 bool "Debug credential management" 765 depends on DEBUG_KERNEL 766 help 767 Enable this to turn on some debug checking for credential 768 management. The additional code keeps track of the number of 769 pointers from task_structs to any given cred struct, and checks to 770 see that this number never exceeds the usage count of the cred 771 struct. 772 773 Furthermore, if SELinux is enabled, this also checks that the 774 security pointer in the cred struct is never seen to be invalid. 775 776 If unsure, say N. 777 778# 779# Select this config option from the architecture Kconfig, if it 780# it is preferred to always offer frame pointers as a config 781# option on the architecture (regardless of KERNEL_DEBUG): 782# 783config ARCH_WANT_FRAME_POINTERS 784 bool 785 help 786 787config FRAME_POINTER 788 bool "Compile the kernel with frame pointers" 789 depends on DEBUG_KERNEL && \ 790 (CRIS || M68K || M68KNOMMU || FRV || UML || \ 791 AVR32 || SUPERH || BLACKFIN || MN10300) || \ 792 ARCH_WANT_FRAME_POINTERS 793 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 794 help 795 If you say Y here the resulting kernel image will be slightly 796 larger and slower, but it gives very useful debugging information 797 in case of kernel bugs. (precise oopses/stacktraces/warnings) 798 799config BOOT_PRINTK_DELAY 800 bool "Delay each boot printk message by N milliseconds" 801 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY 802 help 803 This build option allows you to read kernel boot messages 804 by inserting a short delay after each one. The delay is 805 specified in milliseconds on the kernel command line, 806 using "boot_delay=N". 807 808 It is likely that you would also need to use "lpj=M" to preset 809 the "loops per jiffie" value. 810 See a previous boot log for the "lpj" value to use for your 811 system, and then set "lpj=M" before setting "boot_delay=N". 812 NOTE: Using this option may adversely affect SMP systems. 813 I.e., processors other than the first one may not boot up. 814 BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect 815 what it believes to be lockup conditions. 816 817config RCU_TORTURE_TEST 818 tristate "torture tests for RCU" 819 depends on DEBUG_KERNEL 820 default n 821 help 822 This option provides a kernel module that runs torture tests 823 on the RCU infrastructure. The kernel module may be built 824 after the fact on the running kernel to be tested, if desired. 825 826 Say Y here if you want RCU torture tests to be built into 827 the kernel. 828 Say M if you want the RCU torture tests to build as a module. 829 Say N if you are unsure. 830 831config RCU_TORTURE_TEST_RUNNABLE 832 bool "torture tests for RCU runnable by default" 833 depends on RCU_TORTURE_TEST = y 834 default n 835 help 836 This option provides a way to build the RCU torture tests 837 directly into the kernel without them starting up at boot 838 time. You can use /proc/sys/kernel/rcutorture_runnable 839 to manually override this setting. This /proc file is 840 available only when the RCU torture tests have been built 841 into the kernel. 842 843 Say Y here if you want the RCU torture tests to start during 844 boot (you probably don't). 845 Say N here if you want the RCU torture tests to start only 846 after being manually enabled via /proc. 847 848config RCU_CPU_STALL_DETECTOR 849 bool "Check for stalled CPUs delaying RCU grace periods" 850 depends on TREE_RCU || TREE_PREEMPT_RCU 851 default y 852 help 853 This option causes RCU to printk information on which 854 CPUs are delaying the current grace period, but only when 855 the grace period extends for excessive time periods. 856 857 Say N if you want to disable such checks. 858 859 Say Y if you are unsure. 860 861config RCU_CPU_STALL_TIMEOUT 862 int "RCU CPU stall timeout in seconds" 863 depends on RCU_CPU_STALL_DETECTOR 864 range 3 300 865 default 60 866 help 867 If a given RCU grace period extends more than the specified 868 number of seconds, a CPU stall warning is printed. If the 869 RCU grace period persists, additional CPU stall warnings are 870 printed at more widely spaced intervals. 871 872config RCU_CPU_STALL_DETECTOR_RUNNABLE 873 bool "RCU CPU stall checking starts automatically at boot" 874 depends on RCU_CPU_STALL_DETECTOR 875 default y 876 help 877 If set, start checking for RCU CPU stalls immediately on 878 boot. Otherwise, RCU CPU stall checking must be manually 879 enabled. 880 881 Say Y if you are unsure. 882 883 Say N if you wish to suppress RCU CPU stall checking during boot. 884 885config RCU_CPU_STALL_VERBOSE 886 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR" 887 depends on RCU_CPU_STALL_DETECTOR && TREE_PREEMPT_RCU 888 default y 889 help 890 This option causes RCU to printk detailed per-task information 891 for any tasks that are stalling the current RCU grace period. 892 893 Say N if you are unsure. 894 895 Say Y if you want to enable such checks. 896 897config KPROBES_SANITY_TEST 898 bool "Kprobes sanity tests" 899 depends on DEBUG_KERNEL 900 depends on KPROBES 901 default n 902 help 903 This option provides for testing basic kprobes functionality on 904 boot. A sample kprobe, jprobe and kretprobe are inserted and 905 verified for functionality. 906 907 Say N if you are unsure. 908 909config BACKTRACE_SELF_TEST 910 tristate "Self test for the backtrace code" 911 depends on DEBUG_KERNEL 912 default n 913 help 914 This option provides a kernel module that can be used to test 915 the kernel stack backtrace code. This option is not useful 916 for distributions or general kernels, but only for kernel 917 developers working on architecture code. 918 919 Note that if you want to also test saved backtraces, you will 920 have to enable STACKTRACE as well. 921 922 Say N if you are unsure. 923 924config DEBUG_BLOCK_EXT_DEVT 925 bool "Force extended block device numbers and spread them" 926 depends on DEBUG_KERNEL 927 depends on BLOCK 928 default n 929 help 930 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON 931 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT 932 YOU ARE DOING. Distros, please enable this and fix whatever 933 is broken. 934 935 Conventionally, block device numbers are allocated from 936 predetermined contiguous area. However, extended block area 937 may introduce non-contiguous block device numbers. This 938 option forces most block device numbers to be allocated from 939 the extended space and spreads them to discover kernel or 940 userland code paths which assume predetermined contiguous 941 device number allocation. 942 943 Note that turning on this debug option shuffles all the 944 device numbers for all IDE and SCSI devices including libata 945 ones, so root partition specified using device number 946 directly (via rdev or root=MAJ:MIN) won't work anymore. 947 Textual device names (root=/dev/sdXn) will continue to work. 948 949 Say N if you are unsure. 950 951config DEBUG_FORCE_WEAK_PER_CPU 952 bool "Force weak per-cpu definitions" 953 depends on DEBUG_KERNEL 954 help 955 s390 and alpha require percpu variables in modules to be 956 defined weak to work around addressing range issue which 957 puts the following two restrictions on percpu variable 958 definitions. 959 960 1. percpu symbols must be unique whether static or not 961 2. percpu variables can't be defined inside a function 962 963 To ensure that generic code follows the above rules, this 964 option forces all percpu variables to be defined as weak. 965 966config LKDTM 967 tristate "Linux Kernel Dump Test Tool Module" 968 depends on DEBUG_FS 969 depends on BLOCK 970 default n 971 help 972 This module enables testing of the different dumping mechanisms by 973 inducing system failures at predefined crash points. 974 If you don't need it: say N 975 Choose M here to compile this code as a module. The module will be 976 called lkdtm. 977 978 Documentation on how to use the module can be found in 979 Documentation/fault-injection/provoke-crashes.txt 980 981config CPU_NOTIFIER_ERROR_INJECT 982 tristate "CPU notifier error injection module" 983 depends on HOTPLUG_CPU && DEBUG_KERNEL 984 help 985 This option provides a kernel module that can be used to test 986 the error handling of the cpu notifiers 987 988 To compile this code as a module, choose M here: the module will 989 be called cpu-notifier-error-inject. 990 991 If unsure, say N. 992 993config FAULT_INJECTION 994 bool "Fault-injection framework" 995 depends on DEBUG_KERNEL 996 help 997 Provide fault-injection framework. 998 For more details, see Documentation/fault-injection/. 999 1000config FAILSLAB 1001 bool "Fault-injection capability for kmalloc" 1002 depends on FAULT_INJECTION 1003 depends on SLAB || SLUB 1004 help 1005 Provide fault-injection capability for kmalloc. 1006 1007config FAIL_PAGE_ALLOC 1008 bool "Fault-injection capabilitiy for alloc_pages()" 1009 depends on FAULT_INJECTION 1010 help 1011 Provide fault-injection capability for alloc_pages(). 1012 1013config FAIL_MAKE_REQUEST 1014 bool "Fault-injection capability for disk IO" 1015 depends on FAULT_INJECTION && BLOCK 1016 help 1017 Provide fault-injection capability for disk IO. 1018 1019config FAIL_IO_TIMEOUT 1020 bool "Fault-injection capability for faking disk interrupts" 1021 depends on FAULT_INJECTION && BLOCK 1022 help 1023 Provide fault-injection capability on end IO handling. This 1024 will make the block layer "forget" an interrupt as configured, 1025 thus exercising the error handling. 1026 1027 Only works with drivers that use the generic timeout handling, 1028 for others it wont do anything. 1029 1030config FAULT_INJECTION_DEBUG_FS 1031 bool "Debugfs entries for fault-injection capabilities" 1032 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 1033 help 1034 Enable configuration of fault-injection capabilities via debugfs. 1035 1036config FAULT_INJECTION_STACKTRACE_FILTER 1037 bool "stacktrace filter for fault-injection capabilities" 1038 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 1039 depends on !X86_64 1040 select STACKTRACE 1041 select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE 1042 help 1043 Provide stacktrace filter for fault-injection capabilities 1044 1045config LATENCYTOP 1046 bool "Latency measuring infrastructure" 1047 depends on HAVE_LATENCYTOP_SUPPORT 1048 depends on DEBUG_KERNEL 1049 depends on STACKTRACE_SUPPORT 1050 depends on PROC_FS 1051 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE 1052 select KALLSYMS 1053 select KALLSYMS_ALL 1054 select STACKTRACE 1055 select SCHEDSTATS 1056 select SCHED_DEBUG 1057 help 1058 Enable this option if you want to use the LatencyTOP tool 1059 to find out which userspace is blocking on what kernel operations. 1060 1061config SYSCTL_SYSCALL_CHECK 1062 bool "Sysctl checks" 1063 depends on SYSCTL 1064 ---help--- 1065 sys_sysctl uses binary paths that have been found challenging 1066 to properly maintain and use. This enables checks that help 1067 you to keep things correct. 1068 1069source mm/Kconfig.debug 1070source kernel/trace/Kconfig 1071 1072config PROVIDE_OHCI1394_DMA_INIT 1073 bool "Remote debugging over FireWire early on boot" 1074 depends on PCI && X86 1075 help 1076 If you want to debug problems which hang or crash the kernel early 1077 on boot and the crashing machine has a FireWire port, you can use 1078 this feature to remotely access the memory of the crashed machine 1079 over FireWire. This employs remote DMA as part of the OHCI1394 1080 specification which is now the standard for FireWire controllers. 1081 1082 With remote DMA, you can monitor the printk buffer remotely using 1083 firescope and access all memory below 4GB using fireproxy from gdb. 1084 Even controlling a kernel debugger is possible using remote DMA. 1085 1086 Usage: 1087 1088 If ohci1394_dma=early is used as boot parameter, it will initialize 1089 all OHCI1394 controllers which are found in the PCI config space. 1090 1091 As all changes to the FireWire bus such as enabling and disabling 1092 devices cause a bus reset and thereby disable remote DMA for all 1093 devices, be sure to have the cable plugged and FireWire enabled on 1094 the debugging host before booting the debug target for debugging. 1095 1096 This code (~1k) is freed after boot. By then, the firewire stack 1097 in charge of the OHCI-1394 controllers should be used instead. 1098 1099 See Documentation/debugging-via-ohci1394.txt for more information. 1100 1101config FIREWIRE_OHCI_REMOTE_DMA 1102 bool "Remote debugging over FireWire with firewire-ohci" 1103 depends on FIREWIRE_OHCI 1104 help 1105 This option lets you use the FireWire bus for remote debugging 1106 with help of the firewire-ohci driver. It enables unfiltered 1107 remote DMA in firewire-ohci. 1108 See Documentation/debugging-via-ohci1394.txt for more information. 1109 1110 If unsure, say N. 1111 1112config BUILD_DOCSRC 1113 bool "Build targets in Documentation/ tree" 1114 depends on HEADERS_CHECK 1115 help 1116 This option attempts to build objects from the source files in the 1117 kernel Documentation/ tree. 1118 1119 Say N if you are unsure. 1120 1121config DYNAMIC_DEBUG 1122 bool "Enable dynamic printk() support" 1123 default n 1124 depends on PRINTK 1125 depends on DEBUG_FS 1126 help 1127 1128 Compiles debug level messages into the kernel, which would not 1129 otherwise be available at runtime. These messages can then be 1130 enabled/disabled based on various levels of scope - per source file, 1131 function, module, format string, and line number. This mechanism 1132 implicitly enables all pr_debug() and dev_dbg() calls. The impact of 1133 this compile option is a larger kernel text size of about 2%. 1134 1135 Usage: 1136 1137 Dynamic debugging is controlled via the 'dynamic_debug/control' file, 1138 which is contained in the 'debugfs' filesystem. Thus, the debugfs 1139 filesystem must first be mounted before making use of this feature. 1140 We refer the control file as: <debugfs>/dynamic_debug/control. This 1141 file contains a list of the debug statements that can be enabled. The 1142 format for each line of the file is: 1143 1144 filename:lineno [module]function flags format 1145 1146 filename : source file of the debug statement 1147 lineno : line number of the debug statement 1148 module : module that contains the debug statement 1149 function : function that contains the debug statement 1150 flags : 'p' means the line is turned 'on' for printing 1151 format : the format used for the debug statement 1152 1153 From a live system: 1154 1155 nullarbor:~ # cat <debugfs>/dynamic_debug/control 1156 # filename:lineno [module]function flags format 1157 fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012" 1158 fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012" 1159 fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012" 1160 1161 Example usage: 1162 1163 // enable the message at line 1603 of file svcsock.c 1164 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' > 1165 <debugfs>/dynamic_debug/control 1166 1167 // enable all the messages in file svcsock.c 1168 nullarbor:~ # echo -n 'file svcsock.c +p' > 1169 <debugfs>/dynamic_debug/control 1170 1171 // enable all the messages in the NFS server module 1172 nullarbor:~ # echo -n 'module nfsd +p' > 1173 <debugfs>/dynamic_debug/control 1174 1175 // enable all 12 messages in the function svc_process() 1176 nullarbor:~ # echo -n 'func svc_process +p' > 1177 <debugfs>/dynamic_debug/control 1178 1179 // disable all 12 messages in the function svc_process() 1180 nullarbor:~ # echo -n 'func svc_process -p' > 1181 <debugfs>/dynamic_debug/control 1182 1183 See Documentation/dynamic-debug-howto.txt for additional information. 1184 1185config DMA_API_DEBUG 1186 bool "Enable debugging of DMA-API usage" 1187 depends on HAVE_DMA_API_DEBUG 1188 help 1189 Enable this option to debug the use of the DMA API by device drivers. 1190 With this option you will be able to detect common bugs in device 1191 drivers like double-freeing of DMA mappings or freeing mappings that 1192 were never allocated. 1193 This option causes a performance degredation. Use only if you want 1194 to debug device drivers. If unsure, say N. 1195 1196config ATOMIC64_SELFTEST 1197 bool "Perform an atomic64_t self-test at boot" 1198 help 1199 Enable this option to test the atomic64_t functions at boot. 1200 1201 If unsure, say N. 1202 1203source "samples/Kconfig" 1204 1205source "lib/Kconfig.kgdb" 1206 1207source "lib/Kconfig.kmemcheck" 1208