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 SCHED_DEBUG 190 bool "Collect scheduler debugging info" 191 depends on DEBUG_KERNEL && PROC_FS 192 default y 193 help 194 If you say Y here, the /proc/sched_debug file will be provided 195 that can help debug the scheduler. The runtime overhead of this 196 option is minimal. 197 198config SCHEDSTATS 199 bool "Collect scheduler statistics" 200 depends on DEBUG_KERNEL && PROC_FS 201 help 202 If you say Y here, additional code will be inserted into the 203 scheduler and related routines to collect statistics about 204 scheduler behavior and provide them in /proc/schedstat. These 205 stats may be useful for both tuning and debugging the scheduler 206 If you aren't debugging the scheduler or trying to tune a specific 207 application, you can say N to avoid the very slight overhead 208 this adds. 209 210config TIMER_STATS 211 bool "Collect kernel timers statistics" 212 depends on DEBUG_KERNEL && PROC_FS 213 help 214 If you say Y here, additional code will be inserted into the 215 timer routines to collect statistics about kernel timers being 216 reprogrammed. The statistics can be read from /proc/timer_stats. 217 The statistics collection is started by writing 1 to /proc/timer_stats, 218 writing 0 stops it. This feature is useful to collect information 219 about timer usage patterns in kernel and userspace. This feature 220 is lightweight if enabled in the kernel config but not activated 221 (it defaults to deactivated on bootup and will only be activated 222 if some application like powertop activates it explicitly). 223 224config DEBUG_OBJECTS 225 bool "Debug object operations" 226 depends on DEBUG_KERNEL 227 help 228 If you say Y here, additional code will be inserted into the 229 kernel to track the life time of various objects and validate 230 the operations on those objects. 231 232config DEBUG_OBJECTS_SELFTEST 233 bool "Debug objects selftest" 234 depends on DEBUG_OBJECTS 235 help 236 This enables the selftest of the object debug code. 237 238config DEBUG_OBJECTS_FREE 239 bool "Debug objects in freed memory" 240 depends on DEBUG_OBJECTS 241 help 242 This enables checks whether a k/v free operation frees an area 243 which contains an object which has not been deactivated 244 properly. This can make kmalloc/kfree-intensive workloads 245 much slower. 246 247config DEBUG_OBJECTS_TIMERS 248 bool "Debug timer objects" 249 depends on DEBUG_OBJECTS 250 help 251 If you say Y here, additional code will be inserted into the 252 timer routines to track the life time of timer objects and 253 validate the timer operations. 254 255config DEBUG_SLAB 256 bool "Debug slab memory allocations" 257 depends on DEBUG_KERNEL && SLAB 258 help 259 Say Y here to have the kernel do limited verification on memory 260 allocation as well as poisoning memory on free to catch use of freed 261 memory. This can make kmalloc/kfree-intensive workloads much slower. 262 263config DEBUG_SLAB_LEAK 264 bool "Memory leak debugging" 265 depends on DEBUG_SLAB 266 267config SLUB_DEBUG_ON 268 bool "SLUB debugging on by default" 269 depends on SLUB && SLUB_DEBUG 270 default n 271 help 272 Boot with debugging on by default. SLUB boots by default with 273 the runtime debug capabilities switched off. Enabling this is 274 equivalent to specifying the "slub_debug" parameter on boot. 275 There is no support for more fine grained debug control like 276 possible with slub_debug=xxx. SLUB debugging may be switched 277 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying 278 "slub_debug=-". 279 280config SLUB_STATS 281 default n 282 bool "Enable SLUB performance statistics" 283 depends on SLUB && SLUB_DEBUG && SYSFS 284 help 285 SLUB statistics are useful to debug SLUBs allocation behavior in 286 order find ways to optimize the allocator. This should never be 287 enabled for production use since keeping statistics slows down 288 the allocator by a few percentage points. The slabinfo command 289 supports the determination of the most active slabs to figure 290 out which slabs are relevant to a particular load. 291 Try running: slabinfo -DA 292 293config DEBUG_PREEMPT 294 bool "Debug preemptible kernel" 295 depends on DEBUG_KERNEL && PREEMPT && (TRACE_IRQFLAGS_SUPPORT || PPC64) 296 default y 297 help 298 If you say Y here then the kernel will use a debug variant of the 299 commonly used smp_processor_id() function and will print warnings 300 if kernel code uses it in a preemption-unsafe way. Also, the kernel 301 will detect preemption count underflows. 302 303config DEBUG_RT_MUTEXES 304 bool "RT Mutex debugging, deadlock detection" 305 depends on DEBUG_KERNEL && RT_MUTEXES 306 help 307 This allows rt mutex semantics violations and rt mutex related 308 deadlocks (lockups) to be detected and reported automatically. 309 310config DEBUG_PI_LIST 311 bool 312 default y 313 depends on DEBUG_RT_MUTEXES 314 315config RT_MUTEX_TESTER 316 bool "Built-in scriptable tester for rt-mutexes" 317 depends on DEBUG_KERNEL && RT_MUTEXES 318 help 319 This option enables a rt-mutex tester. 320 321config DEBUG_SPINLOCK 322 bool "Spinlock and rw-lock debugging: basic checks" 323 depends on DEBUG_KERNEL 324 help 325 Say Y here and build SMP to catch missing spinlock initialization 326 and certain other kinds of spinlock errors commonly made. This is 327 best used in conjunction with the NMI watchdog so that spinlock 328 deadlocks are also debuggable. 329 330config DEBUG_MUTEXES 331 bool "Mutex debugging: basic checks" 332 depends on DEBUG_KERNEL 333 help 334 This feature allows mutex semantics violations to be detected and 335 reported. 336 337config DEBUG_LOCK_ALLOC 338 bool "Lock debugging: detect incorrect freeing of live locks" 339 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 340 select DEBUG_SPINLOCK 341 select DEBUG_MUTEXES 342 select LOCKDEP 343 help 344 This feature will check whether any held lock (spinlock, rwlock, 345 mutex or rwsem) is incorrectly freed by the kernel, via any of the 346 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 347 vfree(), etc.), whether a live lock is incorrectly reinitialized via 348 spin_lock_init()/mutex_init()/etc., or whether there is any lock 349 held during task exit. 350 351config PROVE_LOCKING 352 bool "Lock debugging: prove locking correctness" 353 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 354 select LOCKDEP 355 select DEBUG_SPINLOCK 356 select DEBUG_MUTEXES 357 select DEBUG_LOCK_ALLOC 358 default n 359 help 360 This feature enables the kernel to prove that all locking 361 that occurs in the kernel runtime is mathematically 362 correct: that under no circumstance could an arbitrary (and 363 not yet triggered) combination of observed locking 364 sequences (on an arbitrary number of CPUs, running an 365 arbitrary number of tasks and interrupt contexts) cause a 366 deadlock. 367 368 In short, this feature enables the kernel to report locking 369 related deadlocks before they actually occur. 370 371 The proof does not depend on how hard and complex a 372 deadlock scenario would be to trigger: how many 373 participant CPUs, tasks and irq-contexts would be needed 374 for it to trigger. The proof also does not depend on 375 timing: if a race and a resulting deadlock is possible 376 theoretically (no matter how unlikely the race scenario 377 is), it will be proven so and will immediately be 378 reported by the kernel (once the event is observed that 379 makes the deadlock theoretically possible). 380 381 If a deadlock is impossible (i.e. the locking rules, as 382 observed by the kernel, are mathematically correct), the 383 kernel reports nothing. 384 385 NOTE: this feature can also be enabled for rwlocks, mutexes 386 and rwsems - in which case all dependencies between these 387 different locking variants are observed and mapped too, and 388 the proof of observed correctness is also maintained for an 389 arbitrary combination of these separate locking variants. 390 391 For more details, see Documentation/lockdep-design.txt. 392 393config LOCKDEP 394 bool 395 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 396 select STACKTRACE 397 select FRAME_POINTER if !X86 && !MIPS && !PPC 398 select KALLSYMS 399 select KALLSYMS_ALL 400 401config LOCK_STAT 402 bool "Lock usage statistics" 403 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 404 select LOCKDEP 405 select DEBUG_SPINLOCK 406 select DEBUG_MUTEXES 407 select DEBUG_LOCK_ALLOC 408 default n 409 help 410 This feature enables tracking lock contention points 411 412 For more details, see Documentation/lockstat.txt 413 414config DEBUG_LOCKDEP 415 bool "Lock dependency engine debugging" 416 depends on DEBUG_KERNEL && LOCKDEP 417 help 418 If you say Y here, the lock dependency engine will do 419 additional runtime checks to debug itself, at the price 420 of more runtime overhead. 421 422config TRACE_IRQFLAGS 423 depends on DEBUG_KERNEL 424 bool 425 default y 426 depends on TRACE_IRQFLAGS_SUPPORT 427 depends on PROVE_LOCKING 428 429config DEBUG_SPINLOCK_SLEEP 430 bool "Spinlock debugging: sleep-inside-spinlock checking" 431 depends on DEBUG_KERNEL 432 help 433 If you say Y here, various routines which may sleep will become very 434 noisy if they are called with a spinlock held. 435 436config DEBUG_LOCKING_API_SELFTESTS 437 bool "Locking API boot-time self-tests" 438 depends on DEBUG_KERNEL 439 help 440 Say Y here if you want the kernel to run a short self-test during 441 bootup. The self-test checks whether common types of locking bugs 442 are detected by debugging mechanisms or not. (if you disable 443 lock debugging then those bugs wont be detected of course.) 444 The following locking APIs are covered: spinlocks, rwlocks, 445 mutexes and rwsems. 446 447config STACKTRACE 448 bool 449 depends on STACKTRACE_SUPPORT 450 451config DEBUG_KOBJECT 452 bool "kobject debugging" 453 depends on DEBUG_KERNEL 454 help 455 If you say Y here, some extra kobject debugging messages will be sent 456 to the syslog. 457 458config DEBUG_HIGHMEM 459 bool "Highmem debugging" 460 depends on DEBUG_KERNEL && HIGHMEM 461 help 462 This options enables addition error checking for high memory systems. 463 Disable for production systems. 464 465config DEBUG_BUGVERBOSE 466 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED 467 depends on BUG 468 depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \ 469 FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300 470 default !EMBEDDED 471 help 472 Say Y here to make BUG() panics output the file name and line number 473 of the BUG call as well as the EIP and oops trace. This aids 474 debugging but costs about 70-100K of memory. 475 476config DEBUG_INFO 477 bool "Compile the kernel with debug info" 478 depends on DEBUG_KERNEL 479 help 480 If you say Y here the resulting kernel image will include 481 debugging info resulting in a larger kernel image. 482 This adds debug symbols to the kernel and modules (gcc -g), and 483 is needed if you intend to use kernel crashdump or binary object 484 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 485 Say Y here only if you plan to debug the kernel. 486 487 If unsure, say N. 488 489config DEBUG_VM 490 bool "Debug VM" 491 depends on DEBUG_KERNEL 492 help 493 Enable this to turn on extended checks in the virtual-memory system 494 that may impact performance. 495 496 If unsure, say N. 497 498config DEBUG_VIRTUAL 499 bool "Debug VM translations" 500 depends on DEBUG_KERNEL && X86 501 help 502 Enable some costly sanity checks in virtual to page code. This can 503 catch mistakes with virt_to_page() and friends. 504 505 If unsure, say N. 506 507config DEBUG_WRITECOUNT 508 bool "Debug filesystem writers count" 509 depends on DEBUG_KERNEL 510 help 511 Enable this to catch wrong use of the writers count in struct 512 vfsmount. This will increase the size of each file struct by 513 32 bits. 514 515 If unsure, say N. 516 517config DEBUG_MEMORY_INIT 518 bool "Debug memory initialisation" if EMBEDDED 519 default !EMBEDDED 520 help 521 Enable this for additional checks during memory initialisation. 522 The sanity checks verify aspects of the VM such as the memory model 523 and other information provided by the architecture. Verbose 524 information will be printed at KERN_DEBUG loglevel depending 525 on the mminit_loglevel= command-line option. 526 527 If unsure, say Y 528 529config DEBUG_LIST 530 bool "Debug linked list manipulation" 531 depends on DEBUG_KERNEL 532 help 533 Enable this to turn on extended checks in the linked-list 534 walking routines. 535 536 If unsure, say N. 537 538config DEBUG_SG 539 bool "Debug SG table operations" 540 depends on DEBUG_KERNEL 541 help 542 Enable this to turn on checks on scatter-gather tables. This can 543 help find problems with drivers that do not properly initialize 544 their sg tables. 545 546 If unsure, say N. 547 548config FRAME_POINTER 549 bool "Compile the kernel with frame pointers" 550 depends on DEBUG_KERNEL && \ 551 (X86 || CRIS || M68K || M68KNOMMU || FRV || UML || S390 || \ 552 AVR32 || SUPERH || BLACKFIN || MN10300) 553 default y if DEBUG_INFO && UML 554 help 555 If you say Y here the resulting kernel image will be slightly larger 556 and slower, but it might give very useful debugging information on 557 some architectures or if you use external debuggers. 558 If you don't debug the kernel, you can say N. 559 560config BOOT_PRINTK_DELAY 561 bool "Delay each boot printk message by N milliseconds" 562 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY 563 help 564 This build option allows you to read kernel boot messages 565 by inserting a short delay after each one. The delay is 566 specified in milliseconds on the kernel command line, 567 using "boot_delay=N". 568 569 It is likely that you would also need to use "lpj=M" to preset 570 the "loops per jiffie" value. 571 See a previous boot log for the "lpj" value to use for your 572 system, and then set "lpj=M" before setting "boot_delay=N". 573 NOTE: Using this option may adversely affect SMP systems. 574 I.e., processors other than the first one may not boot up. 575 BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect 576 what it believes to be lockup conditions. 577 578config RCU_TORTURE_TEST 579 tristate "torture tests for RCU" 580 depends on DEBUG_KERNEL 581 default n 582 help 583 This option provides a kernel module that runs torture tests 584 on the RCU infrastructure. The kernel module may be built 585 after the fact on the running kernel to be tested, if desired. 586 587 Say Y here if you want RCU torture tests to be built into 588 the kernel. 589 Say M if you want the RCU torture tests to build as a module. 590 Say N if you are unsure. 591 592config RCU_TORTURE_TEST_RUNNABLE 593 bool "torture tests for RCU runnable by default" 594 depends on RCU_TORTURE_TEST = y 595 default n 596 help 597 This option provides a way to build the RCU torture tests 598 directly into the kernel without them starting up at boot 599 time. You can use /proc/sys/kernel/rcutorture_runnable 600 to manually override this setting. This /proc file is 601 available only when the RCU torture tests have been built 602 into the kernel. 603 604 Say Y here if you want the RCU torture tests to start during 605 boot (you probably don't). 606 Say N here if you want the RCU torture tests to start only 607 after being manually enabled via /proc. 608 609config RCU_CPU_STALL_DETECTOR 610 bool "Check for stalled CPUs delaying RCU grace periods" 611 depends on CLASSIC_RCU 612 default n 613 help 614 This option causes RCU to printk information on which 615 CPUs are delaying the current grace period, but only when 616 the grace period extends for excessive time periods. 617 618 Say Y if you want RCU to perform such checks. 619 620 Say N if you are unsure. 621 622config KPROBES_SANITY_TEST 623 bool "Kprobes sanity tests" 624 depends on DEBUG_KERNEL 625 depends on KPROBES 626 default n 627 help 628 This option provides for testing basic kprobes functionality on 629 boot. A sample kprobe, jprobe and kretprobe are inserted and 630 verified for functionality. 631 632 Say N if you are unsure. 633 634config BACKTRACE_SELF_TEST 635 tristate "Self test for the backtrace code" 636 depends on DEBUG_KERNEL 637 default n 638 help 639 This option provides a kernel module that can be used to test 640 the kernel stack backtrace code. This option is not useful 641 for distributions or general kernels, but only for kernel 642 developers working on architecture code. 643 644 Note that if you want to also test saved backtraces, you will 645 have to enable STACKTRACE as well. 646 647 Say N if you are unsure. 648 649config DEBUG_BLOCK_EXT_DEVT 650 bool "Force extended block device numbers and spread them" 651 depends on DEBUG_KERNEL 652 depends on BLOCK 653 default n 654 help 655 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON 656 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT 657 YOU ARE DOING. Distros, please enable this and fix whatever 658 is broken. 659 660 Conventionally, block device numbers are allocated from 661 predetermined contiguous area. However, extended block area 662 may introduce non-contiguous block device numbers. This 663 option forces most block device numbers to be allocated from 664 the extended space and spreads them to discover kernel or 665 userland code paths which assume predetermined contiguous 666 device number allocation. 667 668 Note that turning on this debug option shuffles all the 669 device numbers for all IDE and SCSI devices including libata 670 ones, so root partition specified using device number 671 directly (via rdev or root=MAJ:MIN) won't work anymore. 672 Textual device names (root=/dev/sdXn) will continue to work. 673 674 Say N if you are unsure. 675 676config LKDTM 677 tristate "Linux Kernel Dump Test Tool Module" 678 depends on DEBUG_KERNEL 679 depends on KPROBES 680 depends on BLOCK 681 default n 682 help 683 This module enables testing of the different dumping mechanisms by 684 inducing system failures at predefined crash points. 685 If you don't need it: say N 686 Choose M here to compile this code as a module. The module will be 687 called lkdtm. 688 689 Documentation on how to use the module can be found in 690 drivers/misc/lkdtm.c 691 692config FAULT_INJECTION 693 bool "Fault-injection framework" 694 depends on DEBUG_KERNEL 695 help 696 Provide fault-injection framework. 697 For more details, see Documentation/fault-injection/. 698 699config FAILSLAB 700 bool "Fault-injection capability for kmalloc" 701 depends on FAULT_INJECTION 702 help 703 Provide fault-injection capability for kmalloc. 704 705config FAIL_PAGE_ALLOC 706 bool "Fault-injection capabilitiy for alloc_pages()" 707 depends on FAULT_INJECTION 708 help 709 Provide fault-injection capability for alloc_pages(). 710 711config FAIL_MAKE_REQUEST 712 bool "Fault-injection capability for disk IO" 713 depends on FAULT_INJECTION && BLOCK 714 help 715 Provide fault-injection capability for disk IO. 716 717config FAIL_IO_TIMEOUT 718 bool "Faul-injection capability for faking disk interrupts" 719 depends on FAULT_INJECTION && BLOCK 720 help 721 Provide fault-injection capability on end IO handling. This 722 will make the block layer "forget" an interrupt as configured, 723 thus exercising the error handling. 724 725 Only works with drivers that use the generic timeout handling, 726 for others it wont do anything. 727 728config FAULT_INJECTION_DEBUG_FS 729 bool "Debugfs entries for fault-injection capabilities" 730 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 731 help 732 Enable configuration of fault-injection capabilities via debugfs. 733 734config FAULT_INJECTION_STACKTRACE_FILTER 735 bool "stacktrace filter for fault-injection capabilities" 736 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 737 depends on !X86_64 738 select STACKTRACE 739 select FRAME_POINTER if !PPC 740 help 741 Provide stacktrace filter for fault-injection capabilities 742 743config LATENCYTOP 744 bool "Latency measuring infrastructure" 745 select FRAME_POINTER if !MIPS && !PPC 746 select KALLSYMS 747 select KALLSYMS_ALL 748 select STACKTRACE 749 select SCHEDSTATS 750 select SCHED_DEBUG 751 depends on HAVE_LATENCYTOP_SUPPORT 752 help 753 Enable this option if you want to use the LatencyTOP tool 754 to find out which userspace is blocking on what kernel operations. 755 756config SYSCTL_SYSCALL_CHECK 757 bool "Sysctl checks" 758 depends on SYSCTL_SYSCALL 759 ---help--- 760 sys_sysctl uses binary paths that have been found challenging 761 to properly maintain and use. This enables checks that help 762 you to keep things correct. 763 764source kernel/trace/Kconfig 765 766config PROVIDE_OHCI1394_DMA_INIT 767 bool "Remote debugging over FireWire early on boot" 768 depends on PCI && X86 769 help 770 If you want to debug problems which hang or crash the kernel early 771 on boot and the crashing machine has a FireWire port, you can use 772 this feature to remotely access the memory of the crashed machine 773 over FireWire. This employs remote DMA as part of the OHCI1394 774 specification which is now the standard for FireWire controllers. 775 776 With remote DMA, you can monitor the printk buffer remotely using 777 firescope and access all memory below 4GB using fireproxy from gdb. 778 Even controlling a kernel debugger is possible using remote DMA. 779 780 Usage: 781 782 If ohci1394_dma=early is used as boot parameter, it will initialize 783 all OHCI1394 controllers which are found in the PCI config space. 784 785 As all changes to the FireWire bus such as enabling and disabling 786 devices cause a bus reset and thereby disable remote DMA for all 787 devices, be sure to have the cable plugged and FireWire enabled on 788 the debugging host before booting the debug target for debugging. 789 790 This code (~1k) is freed after boot. By then, the firewire stack 791 in charge of the OHCI-1394 controllers should be used instead. 792 793 See Documentation/debugging-via-ohci1394.txt for more information. 794 795config FIREWIRE_OHCI_REMOTE_DMA 796 bool "Remote debugging over FireWire with firewire-ohci" 797 depends on FIREWIRE_OHCI 798 help 799 This option lets you use the FireWire bus for remote debugging 800 with help of the firewire-ohci driver. It enables unfiltered 801 remote DMA in firewire-ohci. 802 See Documentation/debugging-via-ohci1394.txt for more information. 803 804 If unsure, say N. 805 806menuconfig BUILD_DOCSRC 807 bool "Build targets in Documentation/ tree" 808 depends on HEADERS_CHECK 809 help 810 This option attempts to build objects from the source files in the 811 kernel Documentation/ tree. 812 813 Say N if you are unsure. 814 815config DYNAMIC_PRINTK_DEBUG 816 bool "Enable dynamic printk() call support" 817 default n 818 depends on PRINTK 819 select PRINTK_DEBUG 820 help 821 822 Compiles debug level messages into the kernel, which would not 823 otherwise be available at runtime. These messages can then be 824 enabled/disabled on a per module basis. This mechanism implicitly 825 enables all pr_debug() and dev_dbg() calls. The impact of this 826 compile option is a larger kernel text size of about 2%. 827 828 Usage: 829 830 Dynamic debugging is controlled by the debugfs file, 831 dynamic_printk/modules. This file contains a list of the modules that 832 can be enabled. The format of the file is the module name, followed 833 by a set of flags that can be enabled. The first flag is always the 834 'enabled' flag. For example: 835 836 <module_name> <enabled=0/1> 837 . 838 . 839 . 840 841 <module_name> : Name of the module in which the debug call resides 842 <enabled=0/1> : whether the messages are enabled or not 843 844 From a live system: 845 846 snd_hda_intel enabled=0 847 fixup enabled=0 848 driver enabled=0 849 850 Enable a module: 851 852 $echo "set enabled=1 <module_name>" > dynamic_printk/modules 853 854 Disable a module: 855 856 $echo "set enabled=0 <module_name>" > dynamic_printk/modules 857 858 Enable all modules: 859 860 $echo "set enabled=1 all" > dynamic_printk/modules 861 862 Disable all modules: 863 864 $echo "set enabled=0 all" > dynamic_printk/modules 865 866 Finally, passing "dynamic_printk" at the command line enables 867 debugging for all modules. This mode can be turned off via the above 868 disable command. 869 870source "samples/Kconfig" 871 872source "lib/Kconfig.kgdb" 873