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_NOMMU_REGIONS 516 bool "Debug the global anon/private NOMMU mapping region tree" 517 depends on DEBUG_KERNEL && !MMU 518 help 519 This option causes the global tree of anonymous and private mapping 520 regions to be regularly checked for invalid topology. 521 522config DEBUG_WRITECOUNT 523 bool "Debug filesystem writers count" 524 depends on DEBUG_KERNEL 525 help 526 Enable this to catch wrong use of the writers count in struct 527 vfsmount. This will increase the size of each file struct by 528 32 bits. 529 530 If unsure, say N. 531 532config DEBUG_MEMORY_INIT 533 bool "Debug memory initialisation" if EMBEDDED 534 default !EMBEDDED 535 help 536 Enable this for additional checks during memory initialisation. 537 The sanity checks verify aspects of the VM such as the memory model 538 and other information provided by the architecture. Verbose 539 information will be printed at KERN_DEBUG loglevel depending 540 on the mminit_loglevel= command-line option. 541 542 If unsure, say Y 543 544config DEBUG_LIST 545 bool "Debug linked list manipulation" 546 depends on DEBUG_KERNEL 547 help 548 Enable this to turn on extended checks in the linked-list 549 walking routines. 550 551 If unsure, say N. 552 553config DEBUG_SG 554 bool "Debug SG table operations" 555 depends on DEBUG_KERNEL 556 help 557 Enable this to turn on checks on scatter-gather tables. This can 558 help find problems with drivers that do not properly initialize 559 their sg tables. 560 561 If unsure, say N. 562 563config DEBUG_NOTIFIERS 564 bool "Debug notifier call chains" 565 depends on DEBUG_KERNEL 566 help 567 Enable this to turn on sanity checking for notifier call chains. 568 This is most useful for kernel developers to make sure that 569 modules properly unregister themselves from notifier chains. 570 This is a relatively cheap check but if you care about maximum 571 performance, say N. 572 573# 574# Select this config option from the architecture Kconfig, if it 575# it is preferred to always offer frame pointers as a config 576# option on the architecture (regardless of KERNEL_DEBUG): 577# 578config ARCH_WANT_FRAME_POINTERS 579 bool 580 help 581 582config FRAME_POINTER 583 bool "Compile the kernel with frame pointers" 584 depends on DEBUG_KERNEL && \ 585 (CRIS || M68K || M68KNOMMU || FRV || UML || S390 || \ 586 AVR32 || SUPERH || BLACKFIN || MN10300) || \ 587 ARCH_WANT_FRAME_POINTERS 588 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 589 help 590 If you say Y here the resulting kernel image will be slightly 591 larger and slower, but it gives very useful debugging information 592 in case of kernel bugs. (precise oopses/stacktraces/warnings) 593 594config BOOT_PRINTK_DELAY 595 bool "Delay each boot printk message by N milliseconds" 596 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY 597 help 598 This build option allows you to read kernel boot messages 599 by inserting a short delay after each one. The delay is 600 specified in milliseconds on the kernel command line, 601 using "boot_delay=N". 602 603 It is likely that you would also need to use "lpj=M" to preset 604 the "loops per jiffie" value. 605 See a previous boot log for the "lpj" value to use for your 606 system, and then set "lpj=M" before setting "boot_delay=N". 607 NOTE: Using this option may adversely affect SMP systems. 608 I.e., processors other than the first one may not boot up. 609 BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect 610 what it believes to be lockup conditions. 611 612config RCU_TORTURE_TEST 613 tristate "torture tests for RCU" 614 depends on DEBUG_KERNEL 615 default n 616 help 617 This option provides a kernel module that runs torture tests 618 on the RCU infrastructure. The kernel module may be built 619 after the fact on the running kernel to be tested, if desired. 620 621 Say Y here if you want RCU torture tests to be built into 622 the kernel. 623 Say M if you want the RCU torture tests to build as a module. 624 Say N if you are unsure. 625 626config RCU_TORTURE_TEST_RUNNABLE 627 bool "torture tests for RCU runnable by default" 628 depends on RCU_TORTURE_TEST = y 629 default n 630 help 631 This option provides a way to build the RCU torture tests 632 directly into the kernel without them starting up at boot 633 time. You can use /proc/sys/kernel/rcutorture_runnable 634 to manually override this setting. This /proc file is 635 available only when the RCU torture tests have been built 636 into the kernel. 637 638 Say Y here if you want the RCU torture tests to start during 639 boot (you probably don't). 640 Say N here if you want the RCU torture tests to start only 641 after being manually enabled via /proc. 642 643config RCU_CPU_STALL_DETECTOR 644 bool "Check for stalled CPUs delaying RCU grace periods" 645 depends on CLASSIC_RCU || TREE_RCU 646 default n 647 help 648 This option causes RCU to printk information on which 649 CPUs are delaying the current grace period, but only when 650 the grace period extends for excessive time periods. 651 652 Say Y if you want RCU to perform such checks. 653 654 Say N if you are unsure. 655 656config KPROBES_SANITY_TEST 657 bool "Kprobes sanity tests" 658 depends on DEBUG_KERNEL 659 depends on KPROBES 660 default n 661 help 662 This option provides for testing basic kprobes functionality on 663 boot. A sample kprobe, jprobe and kretprobe are inserted and 664 verified for functionality. 665 666 Say N if you are unsure. 667 668config BACKTRACE_SELF_TEST 669 tristate "Self test for the backtrace code" 670 depends on DEBUG_KERNEL 671 default n 672 help 673 This option provides a kernel module that can be used to test 674 the kernel stack backtrace code. This option is not useful 675 for distributions or general kernels, but only for kernel 676 developers working on architecture code. 677 678 Note that if you want to also test saved backtraces, you will 679 have to enable STACKTRACE as well. 680 681 Say N if you are unsure. 682 683config DEBUG_BLOCK_EXT_DEVT 684 bool "Force extended block device numbers and spread them" 685 depends on DEBUG_KERNEL 686 depends on BLOCK 687 default n 688 help 689 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON 690 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT 691 YOU ARE DOING. Distros, please enable this and fix whatever 692 is broken. 693 694 Conventionally, block device numbers are allocated from 695 predetermined contiguous area. However, extended block area 696 may introduce non-contiguous block device numbers. This 697 option forces most block device numbers to be allocated from 698 the extended space and spreads them to discover kernel or 699 userland code paths which assume predetermined contiguous 700 device number allocation. 701 702 Note that turning on this debug option shuffles all the 703 device numbers for all IDE and SCSI devices including libata 704 ones, so root partition specified using device number 705 directly (via rdev or root=MAJ:MIN) won't work anymore. 706 Textual device names (root=/dev/sdXn) will continue to work. 707 708 Say N if you are unsure. 709 710config LKDTM 711 tristate "Linux Kernel Dump Test Tool Module" 712 depends on DEBUG_KERNEL 713 depends on KPROBES 714 depends on BLOCK 715 default n 716 help 717 This module enables testing of the different dumping mechanisms by 718 inducing system failures at predefined crash points. 719 If you don't need it: say N 720 Choose M here to compile this code as a module. The module will be 721 called lkdtm. 722 723 Documentation on how to use the module can be found in 724 drivers/misc/lkdtm.c 725 726config FAULT_INJECTION 727 bool "Fault-injection framework" 728 depends on DEBUG_KERNEL 729 help 730 Provide fault-injection framework. 731 For more details, see Documentation/fault-injection/. 732 733config FAILSLAB 734 bool "Fault-injection capability for kmalloc" 735 depends on FAULT_INJECTION 736 depends on SLAB || SLUB 737 help 738 Provide fault-injection capability for kmalloc. 739 740config FAIL_PAGE_ALLOC 741 bool "Fault-injection capabilitiy for alloc_pages()" 742 depends on FAULT_INJECTION 743 help 744 Provide fault-injection capability for alloc_pages(). 745 746config FAIL_MAKE_REQUEST 747 bool "Fault-injection capability for disk IO" 748 depends on FAULT_INJECTION && BLOCK 749 help 750 Provide fault-injection capability for disk IO. 751 752config FAIL_IO_TIMEOUT 753 bool "Faul-injection capability for faking disk interrupts" 754 depends on FAULT_INJECTION && BLOCK 755 help 756 Provide fault-injection capability on end IO handling. This 757 will make the block layer "forget" an interrupt as configured, 758 thus exercising the error handling. 759 760 Only works with drivers that use the generic timeout handling, 761 for others it wont do anything. 762 763config FAULT_INJECTION_DEBUG_FS 764 bool "Debugfs entries for fault-injection capabilities" 765 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 766 help 767 Enable configuration of fault-injection capabilities via debugfs. 768 769config FAULT_INJECTION_STACKTRACE_FILTER 770 bool "stacktrace filter for fault-injection capabilities" 771 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 772 depends on !X86_64 773 select STACKTRACE 774 select FRAME_POINTER if !PPC 775 help 776 Provide stacktrace filter for fault-injection capabilities 777 778config LATENCYTOP 779 bool "Latency measuring infrastructure" 780 select FRAME_POINTER if !MIPS && !PPC 781 select KALLSYMS 782 select KALLSYMS_ALL 783 select STACKTRACE 784 select SCHEDSTATS 785 select SCHED_DEBUG 786 depends on HAVE_LATENCYTOP_SUPPORT 787 help 788 Enable this option if you want to use the LatencyTOP tool 789 to find out which userspace is blocking on what kernel operations. 790 791config SYSCTL_SYSCALL_CHECK 792 bool "Sysctl checks" 793 depends on SYSCTL_SYSCALL 794 ---help--- 795 sys_sysctl uses binary paths that have been found challenging 796 to properly maintain and use. This enables checks that help 797 you to keep things correct. 798 799source kernel/trace/Kconfig 800 801config PROVIDE_OHCI1394_DMA_INIT 802 bool "Remote debugging over FireWire early on boot" 803 depends on PCI && X86 804 help 805 If you want to debug problems which hang or crash the kernel early 806 on boot and the crashing machine has a FireWire port, you can use 807 this feature to remotely access the memory of the crashed machine 808 over FireWire. This employs remote DMA as part of the OHCI1394 809 specification which is now the standard for FireWire controllers. 810 811 With remote DMA, you can monitor the printk buffer remotely using 812 firescope and access all memory below 4GB using fireproxy from gdb. 813 Even controlling a kernel debugger is possible using remote DMA. 814 815 Usage: 816 817 If ohci1394_dma=early is used as boot parameter, it will initialize 818 all OHCI1394 controllers which are found in the PCI config space. 819 820 As all changes to the FireWire bus such as enabling and disabling 821 devices cause a bus reset and thereby disable remote DMA for all 822 devices, be sure to have the cable plugged and FireWire enabled on 823 the debugging host before booting the debug target for debugging. 824 825 This code (~1k) is freed after boot. By then, the firewire stack 826 in charge of the OHCI-1394 controllers should be used instead. 827 828 See Documentation/debugging-via-ohci1394.txt for more information. 829 830config FIREWIRE_OHCI_REMOTE_DMA 831 bool "Remote debugging over FireWire with firewire-ohci" 832 depends on FIREWIRE_OHCI 833 help 834 This option lets you use the FireWire bus for remote debugging 835 with help of the firewire-ohci driver. It enables unfiltered 836 remote DMA in firewire-ohci. 837 See Documentation/debugging-via-ohci1394.txt for more information. 838 839 If unsure, say N. 840 841config BUILD_DOCSRC 842 bool "Build targets in Documentation/ tree" 843 depends on HEADERS_CHECK 844 help 845 This option attempts to build objects from the source files in the 846 kernel Documentation/ tree. 847 848 Say N if you are unsure. 849 850config DYNAMIC_PRINTK_DEBUG 851 bool "Enable dynamic printk() call support" 852 default n 853 depends on PRINTK 854 select PRINTK_DEBUG 855 help 856 857 Compiles debug level messages into the kernel, which would not 858 otherwise be available at runtime. These messages can then be 859 enabled/disabled on a per module basis. This mechanism implicitly 860 enables all pr_debug() and dev_dbg() calls. The impact of this 861 compile option is a larger kernel text size of about 2%. 862 863 Usage: 864 865 Dynamic debugging is controlled by the debugfs file, 866 dynamic_printk/modules. This file contains a list of the modules that 867 can be enabled. The format of the file is the module name, followed 868 by a set of flags that can be enabled. The first flag is always the 869 'enabled' flag. For example: 870 871 <module_name> <enabled=0/1> 872 . 873 . 874 . 875 876 <module_name> : Name of the module in which the debug call resides 877 <enabled=0/1> : whether the messages are enabled or not 878 879 From a live system: 880 881 snd_hda_intel enabled=0 882 fixup enabled=0 883 driver enabled=0 884 885 Enable a module: 886 887 $echo "set enabled=1 <module_name>" > dynamic_printk/modules 888 889 Disable a module: 890 891 $echo "set enabled=0 <module_name>" > dynamic_printk/modules 892 893 Enable all modules: 894 895 $echo "set enabled=1 all" > dynamic_printk/modules 896 897 Disable all modules: 898 899 $echo "set enabled=0 all" > dynamic_printk/modules 900 901 Finally, passing "dynamic_printk" at the command line enables 902 debugging for all modules. This mode can be turned off via the above 903 disable command. 904 905source "samples/Kconfig" 906 907source "lib/Kconfig.kgdb" 908