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_OBJECTS_ENABLE_DEFAULT 256 int "debug_objects bootup default value (0-1)" 257 range 0 1 258 default "1" 259 depends on DEBUG_OBJECTS 260 help 261 Debug objects boot parameter default value 262 263config DEBUG_SLAB 264 bool "Debug slab memory allocations" 265 depends on DEBUG_KERNEL && SLAB 266 help 267 Say Y here to have the kernel do limited verification on memory 268 allocation as well as poisoning memory on free to catch use of freed 269 memory. This can make kmalloc/kfree-intensive workloads much slower. 270 271config DEBUG_SLAB_LEAK 272 bool "Memory leak debugging" 273 depends on DEBUG_SLAB 274 275config SLUB_DEBUG_ON 276 bool "SLUB debugging on by default" 277 depends on SLUB && SLUB_DEBUG 278 default n 279 help 280 Boot with debugging on by default. SLUB boots by default with 281 the runtime debug capabilities switched off. Enabling this is 282 equivalent to specifying the "slub_debug" parameter on boot. 283 There is no support for more fine grained debug control like 284 possible with slub_debug=xxx. SLUB debugging may be switched 285 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying 286 "slub_debug=-". 287 288config SLUB_STATS 289 default n 290 bool "Enable SLUB performance statistics" 291 depends on SLUB && SLUB_DEBUG && SYSFS 292 help 293 SLUB statistics are useful to debug SLUBs allocation behavior in 294 order find ways to optimize the allocator. This should never be 295 enabled for production use since keeping statistics slows down 296 the allocator by a few percentage points. The slabinfo command 297 supports the determination of the most active slabs to figure 298 out which slabs are relevant to a particular load. 299 Try running: slabinfo -DA 300 301config DEBUG_PREEMPT 302 bool "Debug preemptible kernel" 303 depends on DEBUG_KERNEL && PREEMPT && (TRACE_IRQFLAGS_SUPPORT || PPC64) 304 default y 305 help 306 If you say Y here then the kernel will use a debug variant of the 307 commonly used smp_processor_id() function and will print warnings 308 if kernel code uses it in a preemption-unsafe way. Also, the kernel 309 will detect preemption count underflows. 310 311config DEBUG_RT_MUTEXES 312 bool "RT Mutex debugging, deadlock detection" 313 depends on DEBUG_KERNEL && RT_MUTEXES 314 help 315 This allows rt mutex semantics violations and rt mutex related 316 deadlocks (lockups) to be detected and reported automatically. 317 318config DEBUG_PI_LIST 319 bool 320 default y 321 depends on DEBUG_RT_MUTEXES 322 323config RT_MUTEX_TESTER 324 bool "Built-in scriptable tester for rt-mutexes" 325 depends on DEBUG_KERNEL && RT_MUTEXES 326 help 327 This option enables a rt-mutex tester. 328 329config DEBUG_SPINLOCK 330 bool "Spinlock and rw-lock debugging: basic checks" 331 depends on DEBUG_KERNEL 332 help 333 Say Y here and build SMP to catch missing spinlock initialization 334 and certain other kinds of spinlock errors commonly made. This is 335 best used in conjunction with the NMI watchdog so that spinlock 336 deadlocks are also debuggable. 337 338config DEBUG_MUTEXES 339 bool "Mutex debugging: basic checks" 340 depends on DEBUG_KERNEL 341 help 342 This feature allows mutex semantics violations to be detected and 343 reported. 344 345config DEBUG_LOCK_ALLOC 346 bool "Lock debugging: detect incorrect freeing of live locks" 347 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 348 select DEBUG_SPINLOCK 349 select DEBUG_MUTEXES 350 select LOCKDEP 351 help 352 This feature will check whether any held lock (spinlock, rwlock, 353 mutex or rwsem) is incorrectly freed by the kernel, via any of the 354 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 355 vfree(), etc.), whether a live lock is incorrectly reinitialized via 356 spin_lock_init()/mutex_init()/etc., or whether there is any lock 357 held during task exit. 358 359config PROVE_LOCKING 360 bool "Lock debugging: prove locking correctness" 361 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 362 select LOCKDEP 363 select DEBUG_SPINLOCK 364 select DEBUG_MUTEXES 365 select DEBUG_LOCK_ALLOC 366 default n 367 help 368 This feature enables the kernel to prove that all locking 369 that occurs in the kernel runtime is mathematically 370 correct: that under no circumstance could an arbitrary (and 371 not yet triggered) combination of observed locking 372 sequences (on an arbitrary number of CPUs, running an 373 arbitrary number of tasks and interrupt contexts) cause a 374 deadlock. 375 376 In short, this feature enables the kernel to report locking 377 related deadlocks before they actually occur. 378 379 The proof does not depend on how hard and complex a 380 deadlock scenario would be to trigger: how many 381 participant CPUs, tasks and irq-contexts would be needed 382 for it to trigger. The proof also does not depend on 383 timing: if a race and a resulting deadlock is possible 384 theoretically (no matter how unlikely the race scenario 385 is), it will be proven so and will immediately be 386 reported by the kernel (once the event is observed that 387 makes the deadlock theoretically possible). 388 389 If a deadlock is impossible (i.e. the locking rules, as 390 observed by the kernel, are mathematically correct), the 391 kernel reports nothing. 392 393 NOTE: this feature can also be enabled for rwlocks, mutexes 394 and rwsems - in which case all dependencies between these 395 different locking variants are observed and mapped too, and 396 the proof of observed correctness is also maintained for an 397 arbitrary combination of these separate locking variants. 398 399 For more details, see Documentation/lockdep-design.txt. 400 401config LOCKDEP 402 bool 403 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 404 select STACKTRACE 405 select FRAME_POINTER if !X86 && !MIPS && !PPC 406 select KALLSYMS 407 select KALLSYMS_ALL 408 409config LOCK_STAT 410 bool "Lock usage statistics" 411 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 412 select LOCKDEP 413 select DEBUG_SPINLOCK 414 select DEBUG_MUTEXES 415 select DEBUG_LOCK_ALLOC 416 default n 417 help 418 This feature enables tracking lock contention points 419 420 For more details, see Documentation/lockstat.txt 421 422config DEBUG_LOCKDEP 423 bool "Lock dependency engine debugging" 424 depends on DEBUG_KERNEL && LOCKDEP 425 help 426 If you say Y here, the lock dependency engine will do 427 additional runtime checks to debug itself, at the price 428 of more runtime overhead. 429 430config TRACE_IRQFLAGS 431 depends on DEBUG_KERNEL 432 bool 433 default y 434 depends on TRACE_IRQFLAGS_SUPPORT 435 depends on PROVE_LOCKING 436 437config DEBUG_SPINLOCK_SLEEP 438 bool "Spinlock debugging: sleep-inside-spinlock checking" 439 depends on DEBUG_KERNEL 440 help 441 If you say Y here, various routines which may sleep will become very 442 noisy if they are called with a spinlock held. 443 444config DEBUG_LOCKING_API_SELFTESTS 445 bool "Locking API boot-time self-tests" 446 depends on DEBUG_KERNEL 447 help 448 Say Y here if you want the kernel to run a short self-test during 449 bootup. The self-test checks whether common types of locking bugs 450 are detected by debugging mechanisms or not. (if you disable 451 lock debugging then those bugs wont be detected of course.) 452 The following locking APIs are covered: spinlocks, rwlocks, 453 mutexes and rwsems. 454 455config STACKTRACE 456 bool 457 depends on STACKTRACE_SUPPORT 458 459config DEBUG_KOBJECT 460 bool "kobject debugging" 461 depends on DEBUG_KERNEL 462 help 463 If you say Y here, some extra kobject debugging messages will be sent 464 to the syslog. 465 466config DEBUG_HIGHMEM 467 bool "Highmem debugging" 468 depends on DEBUG_KERNEL && HIGHMEM 469 help 470 This options enables addition error checking for high memory systems. 471 Disable for production systems. 472 473config DEBUG_BUGVERBOSE 474 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED 475 depends on BUG 476 depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \ 477 FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300 478 default !EMBEDDED 479 help 480 Say Y here to make BUG() panics output the file name and line number 481 of the BUG call as well as the EIP and oops trace. This aids 482 debugging but costs about 70-100K of memory. 483 484config DEBUG_INFO 485 bool "Compile the kernel with debug info" 486 depends on DEBUG_KERNEL 487 help 488 If you say Y here the resulting kernel image will include 489 debugging info resulting in a larger kernel image. 490 This adds debug symbols to the kernel and modules (gcc -g), and 491 is needed if you intend to use kernel crashdump or binary object 492 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 493 Say Y here only if you plan to debug the kernel. 494 495 If unsure, say N. 496 497config DEBUG_VM 498 bool "Debug VM" 499 depends on DEBUG_KERNEL 500 help 501 Enable this to turn on extended checks in the virtual-memory system 502 that may impact performance. 503 504 If unsure, say N. 505 506config DEBUG_VIRTUAL 507 bool "Debug VM translations" 508 depends on DEBUG_KERNEL && X86 509 help 510 Enable some costly sanity checks in virtual to page code. This can 511 catch mistakes with virt_to_page() and friends. 512 513 If unsure, say N. 514 515config DEBUG_WRITECOUNT 516 bool "Debug filesystem writers count" 517 depends on DEBUG_KERNEL 518 help 519 Enable this to catch wrong use of the writers count in struct 520 vfsmount. This will increase the size of each file struct by 521 32 bits. 522 523 If unsure, say N. 524 525config DEBUG_MEMORY_INIT 526 bool "Debug memory initialisation" if EMBEDDED 527 default !EMBEDDED 528 help 529 Enable this for additional checks during memory initialisation. 530 The sanity checks verify aspects of the VM such as the memory model 531 and other information provided by the architecture. Verbose 532 information will be printed at KERN_DEBUG loglevel depending 533 on the mminit_loglevel= command-line option. 534 535 If unsure, say Y 536 537config DEBUG_LIST 538 bool "Debug linked list manipulation" 539 depends on DEBUG_KERNEL 540 help 541 Enable this to turn on extended checks in the linked-list 542 walking routines. 543 544 If unsure, say N. 545 546config DEBUG_SG 547 bool "Debug SG table operations" 548 depends on DEBUG_KERNEL 549 help 550 Enable this to turn on checks on scatter-gather tables. This can 551 help find problems with drivers that do not properly initialize 552 their sg tables. 553 554 If unsure, say N. 555 556config DEBUG_NOTIFIERS 557 bool "Debug notifier call chains" 558 depends on DEBUG_KERNEL 559 help 560 Enable this to turn on sanity checking for notifier call chains. 561 This is most useful for kernel developers to make sure that 562 modules properly unregister themselves from notifier chains. 563 This is a relatively cheap check but if you care about maximum 564 performance, say N. 565 566config FRAME_POINTER 567 bool "Compile the kernel with frame pointers" 568 depends on DEBUG_KERNEL && \ 569 (X86 || CRIS || M68K || M68KNOMMU || FRV || UML || S390 || \ 570 AVR32 || SUPERH || BLACKFIN || MN10300) 571 default y if DEBUG_INFO && UML 572 help 573 If you say Y here the resulting kernel image will be slightly larger 574 and slower, but it might give very useful debugging information on 575 some architectures or if you use external debuggers. 576 If you don't debug the kernel, you can say N. 577 578config BOOT_PRINTK_DELAY 579 bool "Delay each boot printk message by N milliseconds" 580 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY 581 help 582 This build option allows you to read kernel boot messages 583 by inserting a short delay after each one. The delay is 584 specified in milliseconds on the kernel command line, 585 using "boot_delay=N". 586 587 It is likely that you would also need to use "lpj=M" to preset 588 the "loops per jiffie" value. 589 See a previous boot log for the "lpj" value to use for your 590 system, and then set "lpj=M" before setting "boot_delay=N". 591 NOTE: Using this option may adversely affect SMP systems. 592 I.e., processors other than the first one may not boot up. 593 BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect 594 what it believes to be lockup conditions. 595 596config RCU_TORTURE_TEST 597 tristate "torture tests for RCU" 598 depends on DEBUG_KERNEL 599 default n 600 help 601 This option provides a kernel module that runs torture tests 602 on the RCU infrastructure. The kernel module may be built 603 after the fact on the running kernel to be tested, if desired. 604 605 Say Y here if you want RCU torture tests to be built into 606 the kernel. 607 Say M if you want the RCU torture tests to build as a module. 608 Say N if you are unsure. 609 610config RCU_TORTURE_TEST_RUNNABLE 611 bool "torture tests for RCU runnable by default" 612 depends on RCU_TORTURE_TEST = y 613 default n 614 help 615 This option provides a way to build the RCU torture tests 616 directly into the kernel without them starting up at boot 617 time. You can use /proc/sys/kernel/rcutorture_runnable 618 to manually override this setting. This /proc file is 619 available only when the RCU torture tests have been built 620 into the kernel. 621 622 Say Y here if you want the RCU torture tests to start during 623 boot (you probably don't). 624 Say N here if you want the RCU torture tests to start only 625 after being manually enabled via /proc. 626 627config RCU_CPU_STALL_DETECTOR 628 bool "Check for stalled CPUs delaying RCU grace periods" 629 depends on CLASSIC_RCU 630 default n 631 help 632 This option causes RCU to printk information on which 633 CPUs are delaying the current grace period, but only when 634 the grace period extends for excessive time periods. 635 636 Say Y if you want RCU to perform such checks. 637 638 Say N if you are unsure. 639 640config RCU_CPU_STALL_DETECTOR 641 bool "Check for stalled CPUs delaying RCU grace periods" 642 depends on CLASSIC_RCU || TREE_RCU 643 default n 644 help 645 This option causes RCU to printk information on which 646 CPUs are delaying the current grace period, but only when 647 the grace period extends for excessive time periods. 648 649 Say Y if you want RCU to perform such checks. 650 651 Say N if you are unsure. 652 653config KPROBES_SANITY_TEST 654 bool "Kprobes sanity tests" 655 depends on DEBUG_KERNEL 656 depends on KPROBES 657 default n 658 help 659 This option provides for testing basic kprobes functionality on 660 boot. A sample kprobe, jprobe and kretprobe are inserted and 661 verified for functionality. 662 663 Say N if you are unsure. 664 665config BACKTRACE_SELF_TEST 666 tristate "Self test for the backtrace code" 667 depends on DEBUG_KERNEL 668 default n 669 help 670 This option provides a kernel module that can be used to test 671 the kernel stack backtrace code. This option is not useful 672 for distributions or general kernels, but only for kernel 673 developers working on architecture code. 674 675 Note that if you want to also test saved backtraces, you will 676 have to enable STACKTRACE as well. 677 678 Say N if you are unsure. 679 680config DEBUG_BLOCK_EXT_DEVT 681 bool "Force extended block device numbers and spread them" 682 depends on DEBUG_KERNEL 683 depends on BLOCK 684 default n 685 help 686 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON 687 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT 688 YOU ARE DOING. Distros, please enable this and fix whatever 689 is broken. 690 691 Conventionally, block device numbers are allocated from 692 predetermined contiguous area. However, extended block area 693 may introduce non-contiguous block device numbers. This 694 option forces most block device numbers to be allocated from 695 the extended space and spreads them to discover kernel or 696 userland code paths which assume predetermined contiguous 697 device number allocation. 698 699 Note that turning on this debug option shuffles all the 700 device numbers for all IDE and SCSI devices including libata 701 ones, so root partition specified using device number 702 directly (via rdev or root=MAJ:MIN) won't work anymore. 703 Textual device names (root=/dev/sdXn) will continue to work. 704 705 Say N if you are unsure. 706 707config LKDTM 708 tristate "Linux Kernel Dump Test Tool Module" 709 depends on DEBUG_KERNEL 710 depends on KPROBES 711 depends on BLOCK 712 default n 713 help 714 This module enables testing of the different dumping mechanisms by 715 inducing system failures at predefined crash points. 716 If you don't need it: say N 717 Choose M here to compile this code as a module. The module will be 718 called lkdtm. 719 720 Documentation on how to use the module can be found in 721 drivers/misc/lkdtm.c 722 723config FAULT_INJECTION 724 bool "Fault-injection framework" 725 depends on DEBUG_KERNEL 726 help 727 Provide fault-injection framework. 728 For more details, see Documentation/fault-injection/. 729 730config FAILSLAB 731 bool "Fault-injection capability for kmalloc" 732 depends on FAULT_INJECTION 733 depends on SLAB || SLUB 734 help 735 Provide fault-injection capability for kmalloc. 736 737config FAIL_PAGE_ALLOC 738 bool "Fault-injection capabilitiy for alloc_pages()" 739 depends on FAULT_INJECTION 740 help 741 Provide fault-injection capability for alloc_pages(). 742 743config FAIL_MAKE_REQUEST 744 bool "Fault-injection capability for disk IO" 745 depends on FAULT_INJECTION && BLOCK 746 help 747 Provide fault-injection capability for disk IO. 748 749config FAIL_IO_TIMEOUT 750 bool "Faul-injection capability for faking disk interrupts" 751 depends on FAULT_INJECTION && BLOCK 752 help 753 Provide fault-injection capability on end IO handling. This 754 will make the block layer "forget" an interrupt as configured, 755 thus exercising the error handling. 756 757 Only works with drivers that use the generic timeout handling, 758 for others it wont do anything. 759 760config FAULT_INJECTION_DEBUG_FS 761 bool "Debugfs entries for fault-injection capabilities" 762 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 763 help 764 Enable configuration of fault-injection capabilities via debugfs. 765 766config FAULT_INJECTION_STACKTRACE_FILTER 767 bool "stacktrace filter for fault-injection capabilities" 768 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 769 depends on !X86_64 770 select STACKTRACE 771 select FRAME_POINTER if !PPC 772 help 773 Provide stacktrace filter for fault-injection capabilities 774 775config LATENCYTOP 776 bool "Latency measuring infrastructure" 777 select FRAME_POINTER if !MIPS && !PPC 778 select KALLSYMS 779 select KALLSYMS_ALL 780 select STACKTRACE 781 select SCHEDSTATS 782 select SCHED_DEBUG 783 depends on HAVE_LATENCYTOP_SUPPORT 784 help 785 Enable this option if you want to use the LatencyTOP tool 786 to find out which userspace is blocking on what kernel operations. 787 788config SYSCTL_SYSCALL_CHECK 789 bool "Sysctl checks" 790 depends on SYSCTL_SYSCALL 791 ---help--- 792 sys_sysctl uses binary paths that have been found challenging 793 to properly maintain and use. This enables checks that help 794 you to keep things correct. 795 796source kernel/trace/Kconfig 797 798config PROVIDE_OHCI1394_DMA_INIT 799 bool "Remote debugging over FireWire early on boot" 800 depends on PCI && X86 801 help 802 If you want to debug problems which hang or crash the kernel early 803 on boot and the crashing machine has a FireWire port, you can use 804 this feature to remotely access the memory of the crashed machine 805 over FireWire. This employs remote DMA as part of the OHCI1394 806 specification which is now the standard for FireWire controllers. 807 808 With remote DMA, you can monitor the printk buffer remotely using 809 firescope and access all memory below 4GB using fireproxy from gdb. 810 Even controlling a kernel debugger is possible using remote DMA. 811 812 Usage: 813 814 If ohci1394_dma=early is used as boot parameter, it will initialize 815 all OHCI1394 controllers which are found in the PCI config space. 816 817 As all changes to the FireWire bus such as enabling and disabling 818 devices cause a bus reset and thereby disable remote DMA for all 819 devices, be sure to have the cable plugged and FireWire enabled on 820 the debugging host before booting the debug target for debugging. 821 822 This code (~1k) is freed after boot. By then, the firewire stack 823 in charge of the OHCI-1394 controllers should be used instead. 824 825 See Documentation/debugging-via-ohci1394.txt for more information. 826 827config FIREWIRE_OHCI_REMOTE_DMA 828 bool "Remote debugging over FireWire with firewire-ohci" 829 depends on FIREWIRE_OHCI 830 help 831 This option lets you use the FireWire bus for remote debugging 832 with help of the firewire-ohci driver. It enables unfiltered 833 remote DMA in firewire-ohci. 834 See Documentation/debugging-via-ohci1394.txt for more information. 835 836 If unsure, say N. 837 838menuconfig BUILD_DOCSRC 839 bool "Build targets in Documentation/ tree" 840 depends on HEADERS_CHECK 841 help 842 This option attempts to build objects from the source files in the 843 kernel Documentation/ tree. 844 845 Say N if you are unsure. 846 847config DYNAMIC_PRINTK_DEBUG 848 bool "Enable dynamic printk() call support" 849 default n 850 depends on PRINTK 851 select PRINTK_DEBUG 852 help 853 854 Compiles debug level messages into the kernel, which would not 855 otherwise be available at runtime. These messages can then be 856 enabled/disabled on a per module basis. This mechanism implicitly 857 enables all pr_debug() and dev_dbg() calls. The impact of this 858 compile option is a larger kernel text size of about 2%. 859 860 Usage: 861 862 Dynamic debugging is controlled by the debugfs file, 863 dynamic_printk/modules. This file contains a list of the modules that 864 can be enabled. The format of the file is the module name, followed 865 by a set of flags that can be enabled. The first flag is always the 866 'enabled' flag. For example: 867 868 <module_name> <enabled=0/1> 869 . 870 . 871 . 872 873 <module_name> : Name of the module in which the debug call resides 874 <enabled=0/1> : whether the messages are enabled or not 875 876 From a live system: 877 878 snd_hda_intel enabled=0 879 fixup enabled=0 880 driver enabled=0 881 882 Enable a module: 883 884 $echo "set enabled=1 <module_name>" > dynamic_printk/modules 885 886 Disable a module: 887 888 $echo "set enabled=0 <module_name>" > dynamic_printk/modules 889 890 Enable all modules: 891 892 $echo "set enabled=1 all" > dynamic_printk/modules 893 894 Disable all modules: 895 896 $echo "set enabled=0 all" > dynamic_printk/modules 897 898 Finally, passing "dynamic_printk" at the command line enables 899 debugging for all modules. This mode can be turned off via the above 900 disable command. 901 902source "samples/Kconfig" 903 904source "lib/Kconfig.kgdb" 905