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 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 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_PREEMPT 340 bool "Debug preemptible kernel" 341 depends on DEBUG_KERNEL && PREEMPT && (TRACE_IRQFLAGS_SUPPORT || PPC64) 342 default y 343 help 344 If you say Y here then the kernel will use a debug variant of the 345 commonly used smp_processor_id() function and will print warnings 346 if kernel code uses it in a preemption-unsafe way. Also, the kernel 347 will detect preemption count underflows. 348 349config DEBUG_RT_MUTEXES 350 bool "RT Mutex debugging, deadlock detection" 351 depends on DEBUG_KERNEL && RT_MUTEXES 352 help 353 This allows rt mutex semantics violations and rt mutex related 354 deadlocks (lockups) to be detected and reported automatically. 355 356config DEBUG_PI_LIST 357 bool 358 default y 359 depends on DEBUG_RT_MUTEXES 360 361config RT_MUTEX_TESTER 362 bool "Built-in scriptable tester for rt-mutexes" 363 depends on DEBUG_KERNEL && RT_MUTEXES 364 help 365 This option enables a rt-mutex tester. 366 367config DEBUG_SPINLOCK 368 bool "Spinlock and rw-lock debugging: basic checks" 369 depends on DEBUG_KERNEL 370 help 371 Say Y here and build SMP to catch missing spinlock initialization 372 and certain other kinds of spinlock errors commonly made. This is 373 best used in conjunction with the NMI watchdog so that spinlock 374 deadlocks are also debuggable. 375 376config DEBUG_MUTEXES 377 bool "Mutex debugging: basic checks" 378 depends on DEBUG_KERNEL 379 help 380 This feature allows mutex semantics violations to be detected and 381 reported. 382 383config DEBUG_LOCK_ALLOC 384 bool "Lock debugging: detect incorrect freeing of live locks" 385 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 386 select DEBUG_SPINLOCK 387 select DEBUG_MUTEXES 388 select LOCKDEP 389 help 390 This feature will check whether any held lock (spinlock, rwlock, 391 mutex or rwsem) is incorrectly freed by the kernel, via any of the 392 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 393 vfree(), etc.), whether a live lock is incorrectly reinitialized via 394 spin_lock_init()/mutex_init()/etc., or whether there is any lock 395 held during task exit. 396 397config PROVE_LOCKING 398 bool "Lock debugging: prove locking correctness" 399 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 400 select LOCKDEP 401 select DEBUG_SPINLOCK 402 select DEBUG_MUTEXES 403 select DEBUG_LOCK_ALLOC 404 default n 405 help 406 This feature enables the kernel to prove that all locking 407 that occurs in the kernel runtime is mathematically 408 correct: that under no circumstance could an arbitrary (and 409 not yet triggered) combination of observed locking 410 sequences (on an arbitrary number of CPUs, running an 411 arbitrary number of tasks and interrupt contexts) cause a 412 deadlock. 413 414 In short, this feature enables the kernel to report locking 415 related deadlocks before they actually occur. 416 417 The proof does not depend on how hard and complex a 418 deadlock scenario would be to trigger: how many 419 participant CPUs, tasks and irq-contexts would be needed 420 for it to trigger. The proof also does not depend on 421 timing: if a race and a resulting deadlock is possible 422 theoretically (no matter how unlikely the race scenario 423 is), it will be proven so and will immediately be 424 reported by the kernel (once the event is observed that 425 makes the deadlock theoretically possible). 426 427 If a deadlock is impossible (i.e. the locking rules, as 428 observed by the kernel, are mathematically correct), the 429 kernel reports nothing. 430 431 NOTE: this feature can also be enabled for rwlocks, mutexes 432 and rwsems - in which case all dependencies between these 433 different locking variants are observed and mapped too, and 434 the proof of observed correctness is also maintained for an 435 arbitrary combination of these separate locking variants. 436 437 For more details, see Documentation/lockdep-design.txt. 438 439config LOCKDEP 440 bool 441 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 442 select STACKTRACE 443 select FRAME_POINTER if !X86 && !MIPS && !PPC && !ARM_UNWIND && !S390 444 select KALLSYMS 445 select KALLSYMS_ALL 446 447config LOCK_STAT 448 bool "Lock usage statistics" 449 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 450 select LOCKDEP 451 select DEBUG_SPINLOCK 452 select DEBUG_MUTEXES 453 select DEBUG_LOCK_ALLOC 454 default n 455 help 456 This feature enables tracking lock contention points 457 458 For more details, see Documentation/lockstat.txt 459 460config DEBUG_LOCKDEP 461 bool "Lock dependency engine debugging" 462 depends on DEBUG_KERNEL && LOCKDEP 463 help 464 If you say Y here, the lock dependency engine will do 465 additional runtime checks to debug itself, at the price 466 of more runtime overhead. 467 468config TRACE_IRQFLAGS 469 depends on DEBUG_KERNEL 470 bool 471 default y 472 depends on TRACE_IRQFLAGS_SUPPORT 473 depends on PROVE_LOCKING 474 475config DEBUG_SPINLOCK_SLEEP 476 bool "Spinlock debugging: sleep-inside-spinlock checking" 477 depends on DEBUG_KERNEL 478 help 479 If you say Y here, various routines which may sleep will become very 480 noisy if they are called with a spinlock held. 481 482config DEBUG_LOCKING_API_SELFTESTS 483 bool "Locking API boot-time self-tests" 484 depends on DEBUG_KERNEL 485 help 486 Say Y here if you want the kernel to run a short self-test during 487 bootup. The self-test checks whether common types of locking bugs 488 are detected by debugging mechanisms or not. (if you disable 489 lock debugging then those bugs wont be detected of course.) 490 The following locking APIs are covered: spinlocks, rwlocks, 491 mutexes and rwsems. 492 493config STACKTRACE 494 bool 495 depends on STACKTRACE_SUPPORT 496 497config DEBUG_KOBJECT 498 bool "kobject debugging" 499 depends on DEBUG_KERNEL 500 help 501 If you say Y here, some extra kobject debugging messages will be sent 502 to the syslog. 503 504config DEBUG_HIGHMEM 505 bool "Highmem debugging" 506 depends on DEBUG_KERNEL && HIGHMEM 507 help 508 This options enables addition error checking for high memory systems. 509 Disable for production systems. 510 511config DEBUG_BUGVERBOSE 512 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED 513 depends on BUG 514 depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \ 515 FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300 516 default !EMBEDDED 517 help 518 Say Y here to make BUG() panics output the file name and line number 519 of the BUG call as well as the EIP and oops trace. This aids 520 debugging but costs about 70-100K of memory. 521 522config DEBUG_INFO 523 bool "Compile the kernel with debug info" 524 depends on DEBUG_KERNEL 525 help 526 If you say Y here the resulting kernel image will include 527 debugging info resulting in a larger kernel image. 528 This adds debug symbols to the kernel and modules (gcc -g), and 529 is needed if you intend to use kernel crashdump or binary object 530 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 531 Say Y here only if you plan to debug the kernel. 532 533 If unsure, say N. 534 535config DEBUG_VM 536 bool "Debug VM" 537 depends on DEBUG_KERNEL 538 help 539 Enable this to turn on extended checks in the virtual-memory system 540 that may impact performance. 541 542 If unsure, say N. 543 544config DEBUG_VIRTUAL 545 bool "Debug VM translations" 546 depends on DEBUG_KERNEL && X86 547 help 548 Enable some costly sanity checks in virtual to page code. This can 549 catch mistakes with virt_to_page() and friends. 550 551 If unsure, say N. 552 553config DEBUG_NOMMU_REGIONS 554 bool "Debug the global anon/private NOMMU mapping region tree" 555 depends on DEBUG_KERNEL && !MMU 556 help 557 This option causes the global tree of anonymous and private mapping 558 regions to be regularly checked for invalid topology. 559 560config DEBUG_WRITECOUNT 561 bool "Debug filesystem writers count" 562 depends on DEBUG_KERNEL 563 help 564 Enable this to catch wrong use of the writers count in struct 565 vfsmount. This will increase the size of each file struct by 566 32 bits. 567 568 If unsure, say N. 569 570config DEBUG_MEMORY_INIT 571 bool "Debug memory initialisation" if EMBEDDED 572 default !EMBEDDED 573 help 574 Enable this for additional checks during memory initialisation. 575 The sanity checks verify aspects of the VM such as the memory model 576 and other information provided by the architecture. Verbose 577 information will be printed at KERN_DEBUG loglevel depending 578 on the mminit_loglevel= command-line option. 579 580 If unsure, say Y 581 582config DEBUG_LIST 583 bool "Debug linked list manipulation" 584 depends on DEBUG_KERNEL 585 help 586 Enable this to turn on extended checks in the linked-list 587 walking routines. 588 589 If unsure, say N. 590 591config DEBUG_SG 592 bool "Debug SG table operations" 593 depends on DEBUG_KERNEL 594 help 595 Enable this to turn on checks on scatter-gather tables. This can 596 help find problems with drivers that do not properly initialize 597 their sg tables. 598 599 If unsure, say N. 600 601config DEBUG_NOTIFIERS 602 bool "Debug notifier call chains" 603 depends on DEBUG_KERNEL 604 help 605 Enable this to turn on sanity checking for notifier call chains. 606 This is most useful for kernel developers to make sure that 607 modules properly unregister themselves from notifier chains. 608 This is a relatively cheap check but if you care about maximum 609 performance, say N. 610 611# 612# Select this config option from the architecture Kconfig, if it 613# it is preferred to always offer frame pointers as a config 614# option on the architecture (regardless of KERNEL_DEBUG): 615# 616config ARCH_WANT_FRAME_POINTERS 617 bool 618 help 619 620config FRAME_POINTER 621 bool "Compile the kernel with frame pointers" 622 depends on DEBUG_KERNEL && \ 623 (CRIS || M68K || M68KNOMMU || FRV || UML || \ 624 AVR32 || SUPERH || BLACKFIN || MN10300) || \ 625 ARCH_WANT_FRAME_POINTERS 626 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 627 help 628 If you say Y here the resulting kernel image will be slightly 629 larger and slower, but it gives very useful debugging information 630 in case of kernel bugs. (precise oopses/stacktraces/warnings) 631 632config BOOT_PRINTK_DELAY 633 bool "Delay each boot printk message by N milliseconds" 634 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY 635 help 636 This build option allows you to read kernel boot messages 637 by inserting a short delay after each one. The delay is 638 specified in milliseconds on the kernel command line, 639 using "boot_delay=N". 640 641 It is likely that you would also need to use "lpj=M" to preset 642 the "loops per jiffie" value. 643 See a previous boot log for the "lpj" value to use for your 644 system, and then set "lpj=M" before setting "boot_delay=N". 645 NOTE: Using this option may adversely affect SMP systems. 646 I.e., processors other than the first one may not boot up. 647 BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect 648 what it believes to be lockup conditions. 649 650config RCU_TORTURE_TEST 651 tristate "torture tests for RCU" 652 depends on DEBUG_KERNEL 653 default n 654 help 655 This option provides a kernel module that runs torture tests 656 on the RCU infrastructure. The kernel module may be built 657 after the fact on the running kernel to be tested, if desired. 658 659 Say Y here if you want RCU torture tests to be built into 660 the kernel. 661 Say M if you want the RCU torture tests to build as a module. 662 Say N if you are unsure. 663 664config RCU_TORTURE_TEST_RUNNABLE 665 bool "torture tests for RCU runnable by default" 666 depends on RCU_TORTURE_TEST = y 667 default n 668 help 669 This option provides a way to build the RCU torture tests 670 directly into the kernel without them starting up at boot 671 time. You can use /proc/sys/kernel/rcutorture_runnable 672 to manually override this setting. This /proc file is 673 available only when the RCU torture tests have been built 674 into the kernel. 675 676 Say Y here if you want the RCU torture tests to start during 677 boot (you probably don't). 678 Say N here if you want the RCU torture tests to start only 679 after being manually enabled via /proc. 680 681config RCU_CPU_STALL_DETECTOR 682 bool "Check for stalled CPUs delaying RCU grace periods" 683 depends on CLASSIC_RCU || TREE_RCU 684 default n 685 help 686 This option causes RCU to printk information on which 687 CPUs are delaying the current grace period, but only when 688 the grace period extends for excessive time periods. 689 690 Say Y if you want RCU to perform such checks. 691 692 Say N if you are unsure. 693 694config KPROBES_SANITY_TEST 695 bool "Kprobes sanity tests" 696 depends on DEBUG_KERNEL 697 depends on KPROBES 698 default n 699 help 700 This option provides for testing basic kprobes functionality on 701 boot. A sample kprobe, jprobe and kretprobe are inserted and 702 verified for functionality. 703 704 Say N if you are unsure. 705 706config BACKTRACE_SELF_TEST 707 tristate "Self test for the backtrace code" 708 depends on DEBUG_KERNEL 709 default n 710 help 711 This option provides a kernel module that can be used to test 712 the kernel stack backtrace code. This option is not useful 713 for distributions or general kernels, but only for kernel 714 developers working on architecture code. 715 716 Note that if you want to also test saved backtraces, you will 717 have to enable STACKTRACE as well. 718 719 Say N if you are unsure. 720 721config DEBUG_BLOCK_EXT_DEVT 722 bool "Force extended block device numbers and spread them" 723 depends on DEBUG_KERNEL 724 depends on BLOCK 725 default n 726 help 727 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON 728 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT 729 YOU ARE DOING. Distros, please enable this and fix whatever 730 is broken. 731 732 Conventionally, block device numbers are allocated from 733 predetermined contiguous area. However, extended block area 734 may introduce non-contiguous block device numbers. This 735 option forces most block device numbers to be allocated from 736 the extended space and spreads them to discover kernel or 737 userland code paths which assume predetermined contiguous 738 device number allocation. 739 740 Note that turning on this debug option shuffles all the 741 device numbers for all IDE and SCSI devices including libata 742 ones, so root partition specified using device number 743 directly (via rdev or root=MAJ:MIN) won't work anymore. 744 Textual device names (root=/dev/sdXn) will continue to work. 745 746 Say N if you are unsure. 747 748config LKDTM 749 tristate "Linux Kernel Dump Test Tool Module" 750 depends on DEBUG_KERNEL 751 depends on KPROBES 752 depends on BLOCK 753 default n 754 help 755 This module enables testing of the different dumping mechanisms by 756 inducing system failures at predefined crash points. 757 If you don't need it: say N 758 Choose M here to compile this code as a module. The module will be 759 called lkdtm. 760 761 Documentation on how to use the module can be found in 762 drivers/misc/lkdtm.c 763 764config FAULT_INJECTION 765 bool "Fault-injection framework" 766 depends on DEBUG_KERNEL 767 help 768 Provide fault-injection framework. 769 For more details, see Documentation/fault-injection/. 770 771config FAILSLAB 772 bool "Fault-injection capability for kmalloc" 773 depends on FAULT_INJECTION 774 depends on SLAB || SLUB 775 help 776 Provide fault-injection capability for kmalloc. 777 778config FAIL_PAGE_ALLOC 779 bool "Fault-injection capabilitiy for alloc_pages()" 780 depends on FAULT_INJECTION 781 help 782 Provide fault-injection capability for alloc_pages(). 783 784config FAIL_MAKE_REQUEST 785 bool "Fault-injection capability for disk IO" 786 depends on FAULT_INJECTION && BLOCK 787 help 788 Provide fault-injection capability for disk IO. 789 790config FAIL_IO_TIMEOUT 791 bool "Faul-injection capability for faking disk interrupts" 792 depends on FAULT_INJECTION && BLOCK 793 help 794 Provide fault-injection capability on end IO handling. This 795 will make the block layer "forget" an interrupt as configured, 796 thus exercising the error handling. 797 798 Only works with drivers that use the generic timeout handling, 799 for others it wont do anything. 800 801config FAULT_INJECTION_DEBUG_FS 802 bool "Debugfs entries for fault-injection capabilities" 803 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 804 help 805 Enable configuration of fault-injection capabilities via debugfs. 806 807config FAULT_INJECTION_STACKTRACE_FILTER 808 bool "stacktrace filter for fault-injection capabilities" 809 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 810 depends on !X86_64 811 select STACKTRACE 812 select FRAME_POINTER if !PPC && !S390 813 help 814 Provide stacktrace filter for fault-injection capabilities 815 816config LATENCYTOP 817 bool "Latency measuring infrastructure" 818 select FRAME_POINTER if !MIPS && !PPC && !S390 819 select KALLSYMS 820 select KALLSYMS_ALL 821 select STACKTRACE 822 select SCHEDSTATS 823 select SCHED_DEBUG 824 depends on HAVE_LATENCYTOP_SUPPORT 825 help 826 Enable this option if you want to use the LatencyTOP tool 827 to find out which userspace is blocking on what kernel operations. 828 829config SYSCTL_SYSCALL_CHECK 830 bool "Sysctl checks" 831 depends on SYSCTL_SYSCALL 832 ---help--- 833 sys_sysctl uses binary paths that have been found challenging 834 to properly maintain and use. This enables checks that help 835 you to keep things correct. 836 837source mm/Kconfig.debug 838source kernel/trace/Kconfig 839 840config PROVIDE_OHCI1394_DMA_INIT 841 bool "Remote debugging over FireWire early on boot" 842 depends on PCI && X86 843 help 844 If you want to debug problems which hang or crash the kernel early 845 on boot and the crashing machine has a FireWire port, you can use 846 this feature to remotely access the memory of the crashed machine 847 over FireWire. This employs remote DMA as part of the OHCI1394 848 specification which is now the standard for FireWire controllers. 849 850 With remote DMA, you can monitor the printk buffer remotely using 851 firescope and access all memory below 4GB using fireproxy from gdb. 852 Even controlling a kernel debugger is possible using remote DMA. 853 854 Usage: 855 856 If ohci1394_dma=early is used as boot parameter, it will initialize 857 all OHCI1394 controllers which are found in the PCI config space. 858 859 As all changes to the FireWire bus such as enabling and disabling 860 devices cause a bus reset and thereby disable remote DMA for all 861 devices, be sure to have the cable plugged and FireWire enabled on 862 the debugging host before booting the debug target for debugging. 863 864 This code (~1k) is freed after boot. By then, the firewire stack 865 in charge of the OHCI-1394 controllers should be used instead. 866 867 See Documentation/debugging-via-ohci1394.txt for more information. 868 869config FIREWIRE_OHCI_REMOTE_DMA 870 bool "Remote debugging over FireWire with firewire-ohci" 871 depends on FIREWIRE_OHCI 872 help 873 This option lets you use the FireWire bus for remote debugging 874 with help of the firewire-ohci driver. It enables unfiltered 875 remote DMA in firewire-ohci. 876 See Documentation/debugging-via-ohci1394.txt for more information. 877 878 If unsure, say N. 879 880config BUILD_DOCSRC 881 bool "Build targets in Documentation/ tree" 882 depends on HEADERS_CHECK 883 help 884 This option attempts to build objects from the source files in the 885 kernel Documentation/ tree. 886 887 Say N if you are unsure. 888 889config DYNAMIC_DEBUG 890 bool "Enable dynamic printk() support" 891 default n 892 depends on PRINTK 893 depends on DEBUG_FS 894 help 895 896 Compiles debug level messages into the kernel, which would not 897 otherwise be available at runtime. These messages can then be 898 enabled/disabled based on various levels of scope - per source file, 899 function, module, format string, and line number. This mechanism 900 implicitly enables all pr_debug() and dev_dbg() calls. The impact of 901 this compile option is a larger kernel text size of about 2%. 902 903 Usage: 904 905 Dynamic debugging is controlled via the 'dynamic_debug/ddebug' file, 906 which is contained in the 'debugfs' filesystem. Thus, the debugfs 907 filesystem must first be mounted before making use of this feature. 908 We refer the control file as: <debugfs>/dynamic_debug/ddebug. This 909 file contains a list of the debug statements that can be enabled. The 910 format for each line of the file is: 911 912 filename:lineno [module]function flags format 913 914 filename : source file of the debug statement 915 lineno : line number of the debug statement 916 module : module that contains the debug statement 917 function : function that contains the debug statement 918 flags : 'p' means the line is turned 'on' for printing 919 format : the format used for the debug statement 920 921 From a live system: 922 923 nullarbor:~ # cat <debugfs>/dynamic_debug/ddebug 924 # filename:lineno [module]function flags format 925 fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012" 926 fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012" 927 fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012" 928 929 Example usage: 930 931 // enable the message at line 1603 of file svcsock.c 932 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' > 933 <debugfs>/dynamic_debug/ddebug 934 935 // enable all the messages in file svcsock.c 936 nullarbor:~ # echo -n 'file svcsock.c +p' > 937 <debugfs>/dynamic_debug/ddebug 938 939 // enable all the messages in the NFS server module 940 nullarbor:~ # echo -n 'module nfsd +p' > 941 <debugfs>/dynamic_debug/ddebug 942 943 // enable all 12 messages in the function svc_process() 944 nullarbor:~ # echo -n 'func svc_process +p' > 945 <debugfs>/dynamic_debug/ddebug 946 947 // disable all 12 messages in the function svc_process() 948 nullarbor:~ # echo -n 'func svc_process -p' > 949 <debugfs>/dynamic_debug/ddebug 950 951 See Documentation/dynamic-debug-howto.txt for additional information. 952 953config DMA_API_DEBUG 954 bool "Enable debugging of DMA-API usage" 955 depends on HAVE_DMA_API_DEBUG 956 help 957 Enable this option to debug the use of the DMA API by device drivers. 958 With this option you will be able to detect common bugs in device 959 drivers like double-freeing of DMA mappings or freeing mappings that 960 were never allocated. 961 This option causes a performance degredation. Use only if you want 962 to debug device drivers. If unsure, say N. 963 964source "samples/Kconfig" 965 966source "lib/Kconfig.kgdb" 967