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 UNUSED_SYMBOLS 54 bool "Enable unused/obsolete exported symbols" 55 default y if X86 56 help 57 Unused but exported symbols make the kernel needlessly bigger. For 58 that reason most of these unused exports will soon be removed. This 59 option is provided temporarily to provide a transition period in case 60 some external kernel module needs one of these symbols anyway. If you 61 encounter such a case in your module, consider if you are actually 62 using the right API. (rationale: since nobody in the kernel is using 63 this in a module, there is a pretty good chance it's actually the 64 wrong interface to use). If you really need the symbol, please send a 65 mail to the linux kernel mailing list mentioning the symbol and why 66 you really need it, and what the merge plan to the mainline kernel for 67 your module is. 68 69config DEBUG_FS 70 bool "Debug Filesystem" 71 depends on SYSFS 72 help 73 debugfs is a virtual file system that kernel developers use to put 74 debugging files into. Enable this option to be able to read and 75 write to these files. 76 77 For detailed documentation on the debugfs API, see 78 Documentation/DocBook/filesystems. 79 80 If unsure, say N. 81 82config HEADERS_CHECK 83 bool "Run 'make headers_check' when building vmlinux" 84 depends on !UML 85 help 86 This option will extract the user-visible kernel headers whenever 87 building the kernel, and will run basic sanity checks on them to 88 ensure that exported files do not attempt to include files which 89 were not exported, etc. 90 91 If you're making modifications to header files which are 92 relevant for userspace, say 'Y', and check the headers 93 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in 94 your build tree), to make sure they're suitable. 95 96config DEBUG_SECTION_MISMATCH 97 bool "Enable full Section mismatch analysis" 98 depends on UNDEFINED 99 # This option is on purpose disabled for now. 100 # It will be enabled when we are down to a resonable number 101 # of section mismatch warnings (< 10 for an allyesconfig build) 102 help 103 The section mismatch analysis checks if there are illegal 104 references from one section to another section. 105 Linux will during link or during runtime drop some sections 106 and any use of code/data previously in these sections will 107 most likely result in an oops. 108 In the code functions and variables are annotated with 109 __init, __devinit etc. (see full list in include/linux/init.h) 110 which results in the code/data being placed in specific sections. 111 The section mismatch analysis is always done after a full 112 kernel build but enabling this option will in addition 113 do the following: 114 - Add the option -fno-inline-functions-called-once to gcc 115 When inlining a function annotated __init in a non-init 116 function we would lose the section information and thus 117 the analysis would not catch the illegal reference. 118 This option tells gcc to inline less but will also 119 result in a larger kernel. 120 - Run the section mismatch analysis for each module/built-in.o 121 When we run the section mismatch analysis on vmlinux.o we 122 lose valueble information about where the mismatch was 123 introduced. 124 Running the analysis for each module/built-in.o file 125 will tell where the mismatch happens much closer to the 126 source. The drawback is that we will report the same 127 mismatch at least twice. 128 - Enable verbose reporting from modpost to help solving 129 the section mismatches reported. 130 131config DEBUG_KERNEL 132 bool "Kernel debugging" 133 help 134 Say Y here if you are developing drivers or trying to debug and 135 identify kernel problems. 136 137config DEBUG_SHIRQ 138 bool "Debug shared IRQ handlers" 139 depends on DEBUG_KERNEL && GENERIC_HARDIRQS 140 help 141 Enable this to generate a spurious interrupt as soon as a shared 142 interrupt handler is registered, and just before one is deregistered. 143 Drivers ought to be able to handle interrupts coming in at those 144 points; some don't and need to be caught. 145 146config DETECT_SOFTLOCKUP 147 bool "Detect Soft Lockups" 148 depends on DEBUG_KERNEL && !S390 149 default y 150 help 151 Say Y here to enable the kernel to detect "soft lockups", 152 which are bugs that cause the kernel to loop in kernel 153 mode for more than 60 seconds, without giving other tasks a 154 chance to run. 155 156 When a soft-lockup is detected, the kernel will print the 157 current stack trace (which you should report), but the 158 system will stay locked up. This feature has negligible 159 overhead. 160 161 (Note that "hard lockups" are separate type of bugs that 162 can be detected via the NMI-watchdog, on platforms that 163 support it.) 164 165config BOOTPARAM_SOFTLOCKUP_PANIC 166 bool "Panic (Reboot) On Soft Lockups" 167 depends on DETECT_SOFTLOCKUP 168 help 169 Say Y here to enable the kernel to panic on "soft lockups", 170 which are bugs that cause the kernel to loop in kernel 171 mode for more than 60 seconds, without giving other tasks a 172 chance to run. 173 174 The panic can be used in combination with panic_timeout, 175 to cause the system to reboot automatically after a 176 lockup has been detected. This feature is useful for 177 high-availability systems that have uptime guarantees and 178 where a lockup must be resolved ASAP. 179 180 Say N if unsure. 181 182config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE 183 int 184 depends on DETECT_SOFTLOCKUP 185 range 0 1 186 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC 187 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC 188 189config DETECT_HUNG_TASK 190 bool "Detect Hung Tasks" 191 depends on DEBUG_KERNEL 192 default DETECT_SOFTLOCKUP 193 help 194 Say Y here to enable the kernel to detect "hung tasks", 195 which are bugs that cause the task to be stuck in 196 uninterruptible "D" state indefinitiley. 197 198 When a hung task is detected, the kernel will print the 199 current stack trace (which you should report), but the 200 task will stay in uninterruptible state. If lockdep is 201 enabled then all held locks will also be reported. This 202 feature has negligible overhead. 203 204config BOOTPARAM_HUNG_TASK_PANIC 205 bool "Panic (Reboot) On Hung Tasks" 206 depends on DETECT_HUNG_TASK 207 help 208 Say Y here to enable the kernel to panic on "hung tasks", 209 which are bugs that cause the kernel to leave a task stuck 210 in uninterruptible "D" state. 211 212 The panic can be used in combination with panic_timeout, 213 to cause the system to reboot automatically after a 214 hung task has been detected. This feature is useful for 215 high-availability systems that have uptime guarantees and 216 where a hung tasks must be resolved ASAP. 217 218 Say N if unsure. 219 220config BOOTPARAM_HUNG_TASK_PANIC_VALUE 221 int 222 depends on DETECT_HUNG_TASK 223 range 0 1 224 default 0 if !BOOTPARAM_HUNG_TASK_PANIC 225 default 1 if BOOTPARAM_HUNG_TASK_PANIC 226 227config SCHED_DEBUG 228 bool "Collect scheduler debugging info" 229 depends on DEBUG_KERNEL && PROC_FS 230 default y 231 help 232 If you say Y here, the /proc/sched_debug file will be provided 233 that can help debug the scheduler. The runtime overhead of this 234 option is minimal. 235 236config SCHEDSTATS 237 bool "Collect scheduler statistics" 238 depends on DEBUG_KERNEL && PROC_FS 239 help 240 If you say Y here, additional code will be inserted into the 241 scheduler and related routines to collect statistics about 242 scheduler behavior and provide them in /proc/schedstat. These 243 stats may be useful for both tuning and debugging the scheduler 244 If you aren't debugging the scheduler or trying to tune a specific 245 application, you can say N to avoid the very slight overhead 246 this adds. 247 248config TIMER_STATS 249 bool "Collect kernel timers statistics" 250 depends on DEBUG_KERNEL && PROC_FS 251 help 252 If you say Y here, additional code will be inserted into the 253 timer routines to collect statistics about kernel timers being 254 reprogrammed. The statistics can be read from /proc/timer_stats. 255 The statistics collection is started by writing 1 to /proc/timer_stats, 256 writing 0 stops it. This feature is useful to collect information 257 about timer usage patterns in kernel and userspace. This feature 258 is lightweight if enabled in the kernel config but not activated 259 (it defaults to deactivated on bootup and will only be activated 260 if some application like powertop activates it explicitly). 261 262config DEBUG_OBJECTS 263 bool "Debug object operations" 264 depends on DEBUG_KERNEL 265 help 266 If you say Y here, additional code will be inserted into the 267 kernel to track the life time of various objects and validate 268 the operations on those objects. 269 270config DEBUG_OBJECTS_SELFTEST 271 bool "Debug objects selftest" 272 depends on DEBUG_OBJECTS 273 help 274 This enables the selftest of the object debug code. 275 276config DEBUG_OBJECTS_FREE 277 bool "Debug objects in freed memory" 278 depends on DEBUG_OBJECTS 279 help 280 This enables checks whether a k/v free operation frees an area 281 which contains an object which has not been deactivated 282 properly. This can make kmalloc/kfree-intensive workloads 283 much slower. 284 285config DEBUG_OBJECTS_TIMERS 286 bool "Debug timer objects" 287 depends on DEBUG_OBJECTS 288 help 289 If you say Y here, additional code will be inserted into the 290 timer routines to track the life time of timer objects and 291 validate the timer operations. 292 293config DEBUG_OBJECTS_ENABLE_DEFAULT 294 int "debug_objects bootup default value (0-1)" 295 range 0 1 296 default "1" 297 depends on DEBUG_OBJECTS 298 help 299 Debug objects boot parameter default value 300 301config DEBUG_SLAB 302 bool "Debug slab memory allocations" 303 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK 304 help 305 Say Y here to have the kernel do limited verification on memory 306 allocation as well as poisoning memory on free to catch use of freed 307 memory. This can make kmalloc/kfree-intensive workloads much slower. 308 309config DEBUG_SLAB_LEAK 310 bool "Memory leak debugging" 311 depends on DEBUG_SLAB 312 313config SLUB_DEBUG_ON 314 bool "SLUB debugging on by default" 315 depends on SLUB && SLUB_DEBUG && !KMEMCHECK 316 default n 317 help 318 Boot with debugging on by default. SLUB boots by default with 319 the runtime debug capabilities switched off. Enabling this is 320 equivalent to specifying the "slub_debug" parameter on boot. 321 There is no support for more fine grained debug control like 322 possible with slub_debug=xxx. SLUB debugging may be switched 323 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying 324 "slub_debug=-". 325 326config SLUB_STATS 327 default n 328 bool "Enable SLUB performance statistics" 329 depends on SLUB && SLUB_DEBUG && SYSFS 330 help 331 SLUB statistics are useful to debug SLUBs allocation behavior in 332 order find ways to optimize the allocator. This should never be 333 enabled for production use since keeping statistics slows down 334 the allocator by a few percentage points. The slabinfo command 335 supports the determination of the most active slabs to figure 336 out which slabs are relevant to a particular load. 337 Try running: slabinfo -DA 338 339config DEBUG_KMEMLEAK 340 bool "Kernel memory leak detector" 341 depends on DEBUG_KERNEL && EXPERIMENTAL && (X86 || ARM) && \ 342 !MEMORY_HOTPLUG 343 select DEBUG_FS if SYSFS 344 select STACKTRACE if STACKTRACE_SUPPORT 345 select KALLSYMS 346 help 347 Say Y here if you want to enable the memory leak 348 detector. The memory allocation/freeing is traced in a way 349 similar to the Boehm's conservative garbage collector, the 350 difference being that the orphan objects are not freed but 351 only shown in /sys/kernel/debug/kmemleak. Enabling this 352 feature will introduce an overhead to memory 353 allocations. See Documentation/kmemleak.txt for more 354 details. 355 356 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances 357 of finding leaks due to the slab objects poisoning. 358 359 In order to access the kmemleak file, debugfs needs to be 360 mounted (usually at /sys/kernel/debug). 361 362config DEBUG_KMEMLEAK_EARLY_LOG_SIZE 363 int "Maximum kmemleak early log entries" 364 depends on DEBUG_KMEMLEAK 365 range 200 2000 366 default 400 367 help 368 Kmemleak must track all the memory allocations to avoid 369 reporting false positives. Since memory may be allocated or 370 freed before kmemleak is initialised, an early log buffer is 371 used to store these actions. If kmemleak reports "early log 372 buffer exceeded", please increase this value. 373 374config DEBUG_KMEMLEAK_TEST 375 tristate "Simple test for the kernel memory leak detector" 376 depends on DEBUG_KMEMLEAK 377 help 378 Say Y or M here to build a test for the kernel memory leak 379 detector. This option enables a module that explicitly leaks 380 memory. 381 382 If unsure, say N. 383 384config DEBUG_PREEMPT 385 bool "Debug preemptible kernel" 386 depends on DEBUG_KERNEL && PREEMPT && (TRACE_IRQFLAGS_SUPPORT || PPC64) 387 default y 388 help 389 If you say Y here then the kernel will use a debug variant of the 390 commonly used smp_processor_id() function and will print warnings 391 if kernel code uses it in a preemption-unsafe way. Also, the kernel 392 will detect preemption count underflows. 393 394config DEBUG_RT_MUTEXES 395 bool "RT Mutex debugging, deadlock detection" 396 depends on DEBUG_KERNEL && RT_MUTEXES 397 help 398 This allows rt mutex semantics violations and rt mutex related 399 deadlocks (lockups) to be detected and reported automatically. 400 401config DEBUG_PI_LIST 402 bool 403 default y 404 depends on DEBUG_RT_MUTEXES 405 406config RT_MUTEX_TESTER 407 bool "Built-in scriptable tester for rt-mutexes" 408 depends on DEBUG_KERNEL && RT_MUTEXES 409 help 410 This option enables a rt-mutex tester. 411 412config DEBUG_SPINLOCK 413 bool "Spinlock and rw-lock debugging: basic checks" 414 depends on DEBUG_KERNEL 415 help 416 Say Y here and build SMP to catch missing spinlock initialization 417 and certain other kinds of spinlock errors commonly made. This is 418 best used in conjunction with the NMI watchdog so that spinlock 419 deadlocks are also debuggable. 420 421config DEBUG_MUTEXES 422 bool "Mutex debugging: basic checks" 423 depends on DEBUG_KERNEL 424 help 425 This feature allows mutex semantics violations to be detected and 426 reported. 427 428config DEBUG_LOCK_ALLOC 429 bool "Lock debugging: detect incorrect freeing of live locks" 430 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 431 select DEBUG_SPINLOCK 432 select DEBUG_MUTEXES 433 select LOCKDEP 434 help 435 This feature will check whether any held lock (spinlock, rwlock, 436 mutex or rwsem) is incorrectly freed by the kernel, via any of the 437 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 438 vfree(), etc.), whether a live lock is incorrectly reinitialized via 439 spin_lock_init()/mutex_init()/etc., or whether there is any lock 440 held during task exit. 441 442config PROVE_LOCKING 443 bool "Lock debugging: prove locking correctness" 444 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 445 select LOCKDEP 446 select DEBUG_SPINLOCK 447 select DEBUG_MUTEXES 448 select DEBUG_LOCK_ALLOC 449 default n 450 help 451 This feature enables the kernel to prove that all locking 452 that occurs in the kernel runtime is mathematically 453 correct: that under no circumstance could an arbitrary (and 454 not yet triggered) combination of observed locking 455 sequences (on an arbitrary number of CPUs, running an 456 arbitrary number of tasks and interrupt contexts) cause a 457 deadlock. 458 459 In short, this feature enables the kernel to report locking 460 related deadlocks before they actually occur. 461 462 The proof does not depend on how hard and complex a 463 deadlock scenario would be to trigger: how many 464 participant CPUs, tasks and irq-contexts would be needed 465 for it to trigger. The proof also does not depend on 466 timing: if a race and a resulting deadlock is possible 467 theoretically (no matter how unlikely the race scenario 468 is), it will be proven so and will immediately be 469 reported by the kernel (once the event is observed that 470 makes the deadlock theoretically possible). 471 472 If a deadlock is impossible (i.e. the locking rules, as 473 observed by the kernel, are mathematically correct), the 474 kernel reports nothing. 475 476 NOTE: this feature can also be enabled for rwlocks, mutexes 477 and rwsems - in which case all dependencies between these 478 different locking variants are observed and mapped too, and 479 the proof of observed correctness is also maintained for an 480 arbitrary combination of these separate locking variants. 481 482 For more details, see Documentation/lockdep-design.txt. 483 484config LOCKDEP 485 bool 486 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 487 select STACKTRACE 488 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 489 select KALLSYMS 490 select KALLSYMS_ALL 491 492config LOCK_STAT 493 bool "Lock usage statistics" 494 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 495 select LOCKDEP 496 select DEBUG_SPINLOCK 497 select DEBUG_MUTEXES 498 select DEBUG_LOCK_ALLOC 499 default n 500 help 501 This feature enables tracking lock contention points 502 503 For more details, see Documentation/lockstat.txt 504 505config DEBUG_LOCKDEP 506 bool "Lock dependency engine debugging" 507 depends on DEBUG_KERNEL && LOCKDEP 508 help 509 If you say Y here, the lock dependency engine will do 510 additional runtime checks to debug itself, at the price 511 of more runtime overhead. 512 513config TRACE_IRQFLAGS 514 depends on DEBUG_KERNEL 515 bool 516 default y 517 depends on TRACE_IRQFLAGS_SUPPORT 518 depends on PROVE_LOCKING 519 520config DEBUG_SPINLOCK_SLEEP 521 bool "Spinlock debugging: sleep-inside-spinlock checking" 522 depends on DEBUG_KERNEL 523 help 524 If you say Y here, various routines which may sleep will become very 525 noisy if they are called with a spinlock held. 526 527config DEBUG_LOCKING_API_SELFTESTS 528 bool "Locking API boot-time self-tests" 529 depends on DEBUG_KERNEL 530 help 531 Say Y here if you want the kernel to run a short self-test during 532 bootup. The self-test checks whether common types of locking bugs 533 are detected by debugging mechanisms or not. (if you disable 534 lock debugging then those bugs wont be detected of course.) 535 The following locking APIs are covered: spinlocks, rwlocks, 536 mutexes and rwsems. 537 538config STACKTRACE 539 bool 540 depends on STACKTRACE_SUPPORT 541 542config DEBUG_KOBJECT 543 bool "kobject debugging" 544 depends on DEBUG_KERNEL 545 help 546 If you say Y here, some extra kobject debugging messages will be sent 547 to the syslog. 548 549config DEBUG_HIGHMEM 550 bool "Highmem debugging" 551 depends on DEBUG_KERNEL && HIGHMEM 552 help 553 This options enables addition error checking for high memory systems. 554 Disable for production systems. 555 556config DEBUG_BUGVERBOSE 557 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED 558 depends on BUG 559 depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \ 560 FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300 561 default !EMBEDDED 562 help 563 Say Y here to make BUG() panics output the file name and line number 564 of the BUG call as well as the EIP and oops trace. This aids 565 debugging but costs about 70-100K of memory. 566 567config DEBUG_INFO 568 bool "Compile the kernel with debug info" 569 depends on DEBUG_KERNEL 570 help 571 If you say Y here the resulting kernel image will include 572 debugging info resulting in a larger kernel image. 573 This adds debug symbols to the kernel and modules (gcc -g), and 574 is needed if you intend to use kernel crashdump or binary object 575 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 576 Say Y here only if you plan to debug the kernel. 577 578 If unsure, say N. 579 580config DEBUG_VM 581 bool "Debug VM" 582 depends on DEBUG_KERNEL 583 help 584 Enable this to turn on extended checks in the virtual-memory system 585 that may impact performance. 586 587 If unsure, say N. 588 589config DEBUG_VIRTUAL 590 bool "Debug VM translations" 591 depends on DEBUG_KERNEL && X86 592 help 593 Enable some costly sanity checks in virtual to page code. This can 594 catch mistakes with virt_to_page() and friends. 595 596 If unsure, say N. 597 598config DEBUG_NOMMU_REGIONS 599 bool "Debug the global anon/private NOMMU mapping region tree" 600 depends on DEBUG_KERNEL && !MMU 601 help 602 This option causes the global tree of anonymous and private mapping 603 regions to be regularly checked for invalid topology. 604 605config DEBUG_WRITECOUNT 606 bool "Debug filesystem writers count" 607 depends on DEBUG_KERNEL 608 help 609 Enable this to catch wrong use of the writers count in struct 610 vfsmount. This will increase the size of each file struct by 611 32 bits. 612 613 If unsure, say N. 614 615config DEBUG_MEMORY_INIT 616 bool "Debug memory initialisation" if EMBEDDED 617 default !EMBEDDED 618 help 619 Enable this for additional checks during memory initialisation. 620 The sanity checks verify aspects of the VM such as the memory model 621 and other information provided by the architecture. Verbose 622 information will be printed at KERN_DEBUG loglevel depending 623 on the mminit_loglevel= command-line option. 624 625 If unsure, say Y 626 627config DEBUG_LIST 628 bool "Debug linked list manipulation" 629 depends on DEBUG_KERNEL 630 help 631 Enable this to turn on extended checks in the linked-list 632 walking routines. 633 634 If unsure, say N. 635 636config DEBUG_SG 637 bool "Debug SG table operations" 638 depends on DEBUG_KERNEL 639 help 640 Enable this to turn on checks on scatter-gather tables. This can 641 help find problems with drivers that do not properly initialize 642 their sg tables. 643 644 If unsure, say N. 645 646config DEBUG_NOTIFIERS 647 bool "Debug notifier call chains" 648 depends on DEBUG_KERNEL 649 help 650 Enable this to turn on sanity checking for notifier call chains. 651 This is most useful for kernel developers to make sure that 652 modules properly unregister themselves from notifier chains. 653 This is a relatively cheap check but if you care about maximum 654 performance, say N. 655 656# 657# Select this config option from the architecture Kconfig, if it 658# it is preferred to always offer frame pointers as a config 659# option on the architecture (regardless of KERNEL_DEBUG): 660# 661config ARCH_WANT_FRAME_POINTERS 662 bool 663 help 664 665config FRAME_POINTER 666 bool "Compile the kernel with frame pointers" 667 depends on DEBUG_KERNEL && \ 668 (CRIS || M68K || M68KNOMMU || FRV || UML || \ 669 AVR32 || SUPERH || BLACKFIN || MN10300) || \ 670 ARCH_WANT_FRAME_POINTERS 671 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 672 help 673 If you say Y here the resulting kernel image will be slightly 674 larger and slower, but it gives very useful debugging information 675 in case of kernel bugs. (precise oopses/stacktraces/warnings) 676 677config BOOT_PRINTK_DELAY 678 bool "Delay each boot printk message by N milliseconds" 679 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY 680 help 681 This build option allows you to read kernel boot messages 682 by inserting a short delay after each one. The delay is 683 specified in milliseconds on the kernel command line, 684 using "boot_delay=N". 685 686 It is likely that you would also need to use "lpj=M" to preset 687 the "loops per jiffie" value. 688 See a previous boot log for the "lpj" value to use for your 689 system, and then set "lpj=M" before setting "boot_delay=N". 690 NOTE: Using this option may adversely affect SMP systems. 691 I.e., processors other than the first one may not boot up. 692 BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect 693 what it believes to be lockup conditions. 694 695config RCU_TORTURE_TEST 696 tristate "torture tests for RCU" 697 depends on DEBUG_KERNEL 698 default n 699 help 700 This option provides a kernel module that runs torture tests 701 on the RCU infrastructure. The kernel module may be built 702 after the fact on the running kernel to be tested, if desired. 703 704 Say Y here if you want RCU torture tests to be built into 705 the kernel. 706 Say M if you want the RCU torture tests to build as a module. 707 Say N if you are unsure. 708 709config RCU_TORTURE_TEST_RUNNABLE 710 bool "torture tests for RCU runnable by default" 711 depends on RCU_TORTURE_TEST = y 712 default n 713 help 714 This option provides a way to build the RCU torture tests 715 directly into the kernel without them starting up at boot 716 time. You can use /proc/sys/kernel/rcutorture_runnable 717 to manually override this setting. This /proc file is 718 available only when the RCU torture tests have been built 719 into the kernel. 720 721 Say Y here if you want the RCU torture tests to start during 722 boot (you probably don't). 723 Say N here if you want the RCU torture tests to start only 724 after being manually enabled via /proc. 725 726config RCU_CPU_STALL_DETECTOR 727 bool "Check for stalled CPUs delaying RCU grace periods" 728 depends on CLASSIC_RCU || TREE_RCU 729 default n 730 help 731 This option causes RCU to printk information on which 732 CPUs are delaying the current grace period, but only when 733 the grace period extends for excessive time periods. 734 735 Say Y if you want RCU to perform such checks. 736 737 Say N if you are unsure. 738 739config KPROBES_SANITY_TEST 740 bool "Kprobes sanity tests" 741 depends on DEBUG_KERNEL 742 depends on KPROBES 743 default n 744 help 745 This option provides for testing basic kprobes functionality on 746 boot. A sample kprobe, jprobe and kretprobe are inserted and 747 verified for functionality. 748 749 Say N if you are unsure. 750 751config BACKTRACE_SELF_TEST 752 tristate "Self test for the backtrace code" 753 depends on DEBUG_KERNEL 754 default n 755 help 756 This option provides a kernel module that can be used to test 757 the kernel stack backtrace code. This option is not useful 758 for distributions or general kernels, but only for kernel 759 developers working on architecture code. 760 761 Note that if you want to also test saved backtraces, you will 762 have to enable STACKTRACE as well. 763 764 Say N if you are unsure. 765 766config DEBUG_BLOCK_EXT_DEVT 767 bool "Force extended block device numbers and spread them" 768 depends on DEBUG_KERNEL 769 depends on BLOCK 770 default n 771 help 772 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON 773 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT 774 YOU ARE DOING. Distros, please enable this and fix whatever 775 is broken. 776 777 Conventionally, block device numbers are allocated from 778 predetermined contiguous area. However, extended block area 779 may introduce non-contiguous block device numbers. This 780 option forces most block device numbers to be allocated from 781 the extended space and spreads them to discover kernel or 782 userland code paths which assume predetermined contiguous 783 device number allocation. 784 785 Note that turning on this debug option shuffles all the 786 device numbers for all IDE and SCSI devices including libata 787 ones, so root partition specified using device number 788 directly (via rdev or root=MAJ:MIN) won't work anymore. 789 Textual device names (root=/dev/sdXn) will continue to work. 790 791 Say N if you are unsure. 792 793config LKDTM 794 tristate "Linux Kernel Dump Test Tool Module" 795 depends on DEBUG_KERNEL 796 depends on KPROBES 797 depends on BLOCK 798 default n 799 help 800 This module enables testing of the different dumping mechanisms by 801 inducing system failures at predefined crash points. 802 If you don't need it: say N 803 Choose M here to compile this code as a module. The module will be 804 called lkdtm. 805 806 Documentation on how to use the module can be found in 807 drivers/misc/lkdtm.c 808 809config FAULT_INJECTION 810 bool "Fault-injection framework" 811 depends on DEBUG_KERNEL 812 help 813 Provide fault-injection framework. 814 For more details, see Documentation/fault-injection/. 815 816config FAILSLAB 817 bool "Fault-injection capability for kmalloc" 818 depends on FAULT_INJECTION 819 depends on SLAB || SLUB 820 help 821 Provide fault-injection capability for kmalloc. 822 823config FAIL_PAGE_ALLOC 824 bool "Fault-injection capabilitiy for alloc_pages()" 825 depends on FAULT_INJECTION 826 help 827 Provide fault-injection capability for alloc_pages(). 828 829config FAIL_MAKE_REQUEST 830 bool "Fault-injection capability for disk IO" 831 depends on FAULT_INJECTION && BLOCK 832 help 833 Provide fault-injection capability for disk IO. 834 835config FAIL_IO_TIMEOUT 836 bool "Faul-injection capability for faking disk interrupts" 837 depends on FAULT_INJECTION && BLOCK 838 help 839 Provide fault-injection capability on end IO handling. This 840 will make the block layer "forget" an interrupt as configured, 841 thus exercising the error handling. 842 843 Only works with drivers that use the generic timeout handling, 844 for others it wont do anything. 845 846config FAULT_INJECTION_DEBUG_FS 847 bool "Debugfs entries for fault-injection capabilities" 848 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 849 help 850 Enable configuration of fault-injection capabilities via debugfs. 851 852config FAULT_INJECTION_STACKTRACE_FILTER 853 bool "stacktrace filter for fault-injection capabilities" 854 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 855 depends on !X86_64 856 select STACKTRACE 857 select FRAME_POINTER if !PPC && !S390 858 help 859 Provide stacktrace filter for fault-injection capabilities 860 861config LATENCYTOP 862 bool "Latency measuring infrastructure" 863 select FRAME_POINTER if !MIPS && !PPC && !S390 864 select KALLSYMS 865 select KALLSYMS_ALL 866 select STACKTRACE 867 select SCHEDSTATS 868 select SCHED_DEBUG 869 depends on HAVE_LATENCYTOP_SUPPORT 870 help 871 Enable this option if you want to use the LatencyTOP tool 872 to find out which userspace is blocking on what kernel operations. 873 874config SYSCTL_SYSCALL_CHECK 875 bool "Sysctl checks" 876 depends on SYSCTL_SYSCALL 877 ---help--- 878 sys_sysctl uses binary paths that have been found challenging 879 to properly maintain and use. This enables checks that help 880 you to keep things correct. 881 882source mm/Kconfig.debug 883source kernel/trace/Kconfig 884 885config PROVIDE_OHCI1394_DMA_INIT 886 bool "Remote debugging over FireWire early on boot" 887 depends on PCI && X86 888 help 889 If you want to debug problems which hang or crash the kernel early 890 on boot and the crashing machine has a FireWire port, you can use 891 this feature to remotely access the memory of the crashed machine 892 over FireWire. This employs remote DMA as part of the OHCI1394 893 specification which is now the standard for FireWire controllers. 894 895 With remote DMA, you can monitor the printk buffer remotely using 896 firescope and access all memory below 4GB using fireproxy from gdb. 897 Even controlling a kernel debugger is possible using remote DMA. 898 899 Usage: 900 901 If ohci1394_dma=early is used as boot parameter, it will initialize 902 all OHCI1394 controllers which are found in the PCI config space. 903 904 As all changes to the FireWire bus such as enabling and disabling 905 devices cause a bus reset and thereby disable remote DMA for all 906 devices, be sure to have the cable plugged and FireWire enabled on 907 the debugging host before booting the debug target for debugging. 908 909 This code (~1k) is freed after boot. By then, the firewire stack 910 in charge of the OHCI-1394 controllers should be used instead. 911 912 See Documentation/debugging-via-ohci1394.txt for more information. 913 914config FIREWIRE_OHCI_REMOTE_DMA 915 bool "Remote debugging over FireWire with firewire-ohci" 916 depends on FIREWIRE_OHCI 917 help 918 This option lets you use the FireWire bus for remote debugging 919 with help of the firewire-ohci driver. It enables unfiltered 920 remote DMA in firewire-ohci. 921 See Documentation/debugging-via-ohci1394.txt for more information. 922 923 If unsure, say N. 924 925config BUILD_DOCSRC 926 bool "Build targets in Documentation/ tree" 927 depends on HEADERS_CHECK 928 help 929 This option attempts to build objects from the source files in the 930 kernel Documentation/ tree. 931 932 Say N if you are unsure. 933 934config DYNAMIC_DEBUG 935 bool "Enable dynamic printk() support" 936 default n 937 depends on PRINTK 938 depends on DEBUG_FS 939 help 940 941 Compiles debug level messages into the kernel, which would not 942 otherwise be available at runtime. These messages can then be 943 enabled/disabled based on various levels of scope - per source file, 944 function, module, format string, and line number. This mechanism 945 implicitly enables all pr_debug() and dev_dbg() calls. The impact of 946 this compile option is a larger kernel text size of about 2%. 947 948 Usage: 949 950 Dynamic debugging is controlled via the 'dynamic_debug/ddebug' file, 951 which is contained in the 'debugfs' filesystem. Thus, the debugfs 952 filesystem must first be mounted before making use of this feature. 953 We refer the control file as: <debugfs>/dynamic_debug/ddebug. This 954 file contains a list of the debug statements that can be enabled. The 955 format for each line of the file is: 956 957 filename:lineno [module]function flags format 958 959 filename : source file of the debug statement 960 lineno : line number of the debug statement 961 module : module that contains the debug statement 962 function : function that contains the debug statement 963 flags : 'p' means the line is turned 'on' for printing 964 format : the format used for the debug statement 965 966 From a live system: 967 968 nullarbor:~ # cat <debugfs>/dynamic_debug/ddebug 969 # filename:lineno [module]function flags format 970 fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012" 971 fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012" 972 fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012" 973 974 Example usage: 975 976 // enable the message at line 1603 of file svcsock.c 977 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' > 978 <debugfs>/dynamic_debug/ddebug 979 980 // enable all the messages in file svcsock.c 981 nullarbor:~ # echo -n 'file svcsock.c +p' > 982 <debugfs>/dynamic_debug/ddebug 983 984 // enable all the messages in the NFS server module 985 nullarbor:~ # echo -n 'module nfsd +p' > 986 <debugfs>/dynamic_debug/ddebug 987 988 // enable all 12 messages in the function svc_process() 989 nullarbor:~ # echo -n 'func svc_process +p' > 990 <debugfs>/dynamic_debug/ddebug 991 992 // disable all 12 messages in the function svc_process() 993 nullarbor:~ # echo -n 'func svc_process -p' > 994 <debugfs>/dynamic_debug/ddebug 995 996 See Documentation/dynamic-debug-howto.txt for additional information. 997 998config DMA_API_DEBUG 999 bool "Enable debugging of DMA-API usage" 1000 depends on HAVE_DMA_API_DEBUG 1001 help 1002 Enable this option to debug the use of the DMA API by device drivers. 1003 With this option you will be able to detect common bugs in device 1004 drivers like double-freeing of DMA mappings or freeing mappings that 1005 were never allocated. 1006 This option causes a performance degredation. Use only if you want 1007 to debug device drivers. If unsure, say N. 1008 1009source "samples/Kconfig" 1010 1011source "lib/Kconfig.kgdb" 1012 1013source "lib/Kconfig.kmemcheck" 1014