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 STRIP_ASM_SYMS 54 bool "Strip assembler-generated symbols during link" 55 default n 56 help 57 Strip internal assembler-generated symbols during a link (symbols 58 that look like '.Lxxx') so they don't pollute the output of 59 get_wchan() and suchlike. 60 61config UNUSED_SYMBOLS 62 bool "Enable unused/obsolete exported symbols" 63 default y if X86 64 help 65 Unused but exported symbols make the kernel needlessly bigger. For 66 that reason most of these unused exports will soon be removed. This 67 option is provided temporarily to provide a transition period in case 68 some external kernel module needs one of these symbols anyway. If you 69 encounter such a case in your module, consider if you are actually 70 using the right API. (rationale: since nobody in the kernel is using 71 this in a module, there is a pretty good chance it's actually the 72 wrong interface to use). If you really need the symbol, please send a 73 mail to the linux kernel mailing list mentioning the symbol and why 74 you really need it, and what the merge plan to the mainline kernel for 75 your module is. 76 77config DEBUG_FS 78 bool "Debug Filesystem" 79 depends on SYSFS 80 help 81 debugfs is a virtual file system that kernel developers use to put 82 debugging files into. Enable this option to be able to read and 83 write to these files. 84 85 For detailed documentation on the debugfs API, see 86 Documentation/DocBook/filesystems. 87 88 If unsure, say N. 89 90config HEADERS_CHECK 91 bool "Run 'make headers_check' when building vmlinux" 92 depends on !UML 93 help 94 This option will extract the user-visible kernel headers whenever 95 building the kernel, and will run basic sanity checks on them to 96 ensure that exported files do not attempt to include files which 97 were not exported, etc. 98 99 If you're making modifications to header files which are 100 relevant for userspace, say 'Y', and check the headers 101 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in 102 your build tree), to make sure they're suitable. 103 104config DEBUG_SECTION_MISMATCH 105 bool "Enable full Section mismatch analysis" 106 depends on UNDEFINED || (BLACKFIN) 107 default y 108 # This option is on purpose disabled for now. 109 # It will be enabled when we are down to a reasonable number 110 # of section mismatch warnings (< 10 for an allyesconfig build) 111 help 112 The section mismatch analysis checks if there are illegal 113 references from one section to another section. 114 Linux will during link or during runtime drop some sections 115 and any use of code/data previously in these sections will 116 most likely result in an oops. 117 In the code functions and variables are annotated with 118 __init, __devinit etc. (see full list in include/linux/init.h) 119 which results in the code/data being placed in specific sections. 120 The section mismatch analysis is always done after a full 121 kernel build but enabling this option will in addition 122 do the following: 123 - Add the option -fno-inline-functions-called-once to gcc 124 When inlining a function annotated __init in a non-init 125 function we would lose the section information and thus 126 the analysis would not catch the illegal reference. 127 This option tells gcc to inline less but will also 128 result in a larger kernel. 129 - Run the section mismatch analysis for each module/built-in.o 130 When we run the section mismatch analysis on vmlinux.o we 131 lose valueble information about where the mismatch was 132 introduced. 133 Running the analysis for each module/built-in.o file 134 will tell where the mismatch happens much closer to the 135 source. The drawback is that we will report the same 136 mismatch at least twice. 137 - Enable verbose reporting from modpost to help solving 138 the section mismatches reported. 139 140config DEBUG_KERNEL 141 bool "Kernel debugging" 142 help 143 Say Y here if you are developing drivers or trying to debug and 144 identify kernel problems. 145 146config DEBUG_SHIRQ 147 bool "Debug shared IRQ handlers" 148 depends on DEBUG_KERNEL && GENERIC_HARDIRQS 149 help 150 Enable this to generate a spurious interrupt as soon as a shared 151 interrupt handler is registered, and just before one is deregistered. 152 Drivers ought to be able to handle interrupts coming in at those 153 points; some don't and need to be caught. 154 155config DETECT_SOFTLOCKUP 156 bool "Detect Soft Lockups" 157 depends on DEBUG_KERNEL && !S390 158 default y 159 help 160 Say Y here to enable the kernel to detect "soft lockups", 161 which are bugs that cause the kernel to loop in kernel 162 mode for more than 60 seconds, without giving other tasks a 163 chance to run. 164 165 When a soft-lockup is detected, the kernel will print the 166 current stack trace (which you should report), but the 167 system will stay locked up. This feature has negligible 168 overhead. 169 170 (Note that "hard lockups" are separate type of bugs that 171 can be detected via the NMI-watchdog, on platforms that 172 support it.) 173 174config BOOTPARAM_SOFTLOCKUP_PANIC 175 bool "Panic (Reboot) On Soft Lockups" 176 depends on DETECT_SOFTLOCKUP 177 help 178 Say Y here to enable the kernel to panic on "soft lockups", 179 which are bugs that cause the kernel to loop in kernel 180 mode for more than 60 seconds, without giving other tasks a 181 chance to run. 182 183 The panic can be used in combination with panic_timeout, 184 to cause the system to reboot automatically after a 185 lockup has been detected. This feature is useful for 186 high-availability systems that have uptime guarantees and 187 where a lockup must be resolved ASAP. 188 189 Say N if unsure. 190 191config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE 192 int 193 depends on DETECT_SOFTLOCKUP 194 range 0 1 195 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC 196 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC 197 198config DETECT_HUNG_TASK 199 bool "Detect Hung Tasks" 200 depends on DEBUG_KERNEL 201 default DETECT_SOFTLOCKUP 202 help 203 Say Y here to enable the kernel to detect "hung tasks", 204 which are bugs that cause the task to be stuck in 205 uninterruptible "D" state indefinitiley. 206 207 When a hung task is detected, the kernel will print the 208 current stack trace (which you should report), but the 209 task will stay in uninterruptible state. If lockdep is 210 enabled then all held locks will also be reported. This 211 feature has negligible overhead. 212 213config BOOTPARAM_HUNG_TASK_PANIC 214 bool "Panic (Reboot) On Hung Tasks" 215 depends on DETECT_HUNG_TASK 216 help 217 Say Y here to enable the kernel to panic on "hung tasks", 218 which are bugs that cause the kernel to leave a task stuck 219 in uninterruptible "D" state. 220 221 The panic can be used in combination with panic_timeout, 222 to cause the system to reboot automatically after a 223 hung task has been detected. This feature is useful for 224 high-availability systems that have uptime guarantees and 225 where a hung tasks must be resolved ASAP. 226 227 Say N if unsure. 228 229config BOOTPARAM_HUNG_TASK_PANIC_VALUE 230 int 231 depends on DETECT_HUNG_TASK 232 range 0 1 233 default 0 if !BOOTPARAM_HUNG_TASK_PANIC 234 default 1 if BOOTPARAM_HUNG_TASK_PANIC 235 236config SCHED_DEBUG 237 bool "Collect scheduler debugging info" 238 depends on DEBUG_KERNEL && PROC_FS 239 default y 240 help 241 If you say Y here, the /proc/sched_debug file will be provided 242 that can help debug the scheduler. The runtime overhead of this 243 option is minimal. 244 245config SCHEDSTATS 246 bool "Collect scheduler statistics" 247 depends on DEBUG_KERNEL && PROC_FS 248 help 249 If you say Y here, additional code will be inserted into the 250 scheduler and related routines to collect statistics about 251 scheduler behavior and provide them in /proc/schedstat. These 252 stats may be useful for both tuning and debugging the scheduler 253 If you aren't debugging the scheduler or trying to tune a specific 254 application, you can say N to avoid the very slight overhead 255 this adds. 256 257config TIMER_STATS 258 bool "Collect kernel timers statistics" 259 depends on DEBUG_KERNEL && PROC_FS 260 help 261 If you say Y here, additional code will be inserted into the 262 timer routines to collect statistics about kernel timers being 263 reprogrammed. The statistics can be read from /proc/timer_stats. 264 The statistics collection is started by writing 1 to /proc/timer_stats, 265 writing 0 stops it. This feature is useful to collect information 266 about timer usage patterns in kernel and userspace. This feature 267 is lightweight if enabled in the kernel config but not activated 268 (it defaults to deactivated on bootup and will only be activated 269 if some application like powertop activates it explicitly). 270 271config DEBUG_OBJECTS 272 bool "Debug object operations" 273 depends on DEBUG_KERNEL 274 help 275 If you say Y here, additional code will be inserted into the 276 kernel to track the life time of various objects and validate 277 the operations on those objects. 278 279config DEBUG_OBJECTS_SELFTEST 280 bool "Debug objects selftest" 281 depends on DEBUG_OBJECTS 282 help 283 This enables the selftest of the object debug code. 284 285config DEBUG_OBJECTS_FREE 286 bool "Debug objects in freed memory" 287 depends on DEBUG_OBJECTS 288 help 289 This enables checks whether a k/v free operation frees an area 290 which contains an object which has not been deactivated 291 properly. This can make kmalloc/kfree-intensive workloads 292 much slower. 293 294config DEBUG_OBJECTS_TIMERS 295 bool "Debug timer objects" 296 depends on DEBUG_OBJECTS 297 help 298 If you say Y here, additional code will be inserted into the 299 timer routines to track the life time of timer objects and 300 validate the timer operations. 301 302config DEBUG_OBJECTS_WORK 303 bool "Debug work objects" 304 depends on DEBUG_OBJECTS 305 help 306 If you say Y here, additional code will be inserted into the 307 work queue routines to track the life time of work objects and 308 validate the work operations. 309 310config DEBUG_OBJECTS_ENABLE_DEFAULT 311 int "debug_objects bootup default value (0-1)" 312 range 0 1 313 default "1" 314 depends on DEBUG_OBJECTS 315 help 316 Debug objects boot parameter default value 317 318config DEBUG_SLAB 319 bool "Debug slab memory allocations" 320 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK 321 help 322 Say Y here to have the kernel do limited verification on memory 323 allocation as well as poisoning memory on free to catch use of freed 324 memory. This can make kmalloc/kfree-intensive workloads much slower. 325 326config DEBUG_SLAB_LEAK 327 bool "Memory leak debugging" 328 depends on DEBUG_SLAB 329 330config SLUB_DEBUG_ON 331 bool "SLUB debugging on by default" 332 depends on SLUB && SLUB_DEBUG && !KMEMCHECK 333 default n 334 help 335 Boot with debugging on by default. SLUB boots by default with 336 the runtime debug capabilities switched off. Enabling this is 337 equivalent to specifying the "slub_debug" parameter on boot. 338 There is no support for more fine grained debug control like 339 possible with slub_debug=xxx. SLUB debugging may be switched 340 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying 341 "slub_debug=-". 342 343config SLUB_STATS 344 default n 345 bool "Enable SLUB performance statistics" 346 depends on SLUB && SLUB_DEBUG && SYSFS 347 help 348 SLUB statistics are useful to debug SLUBs allocation behavior in 349 order find ways to optimize the allocator. This should never be 350 enabled for production use since keeping statistics slows down 351 the allocator by a few percentage points. The slabinfo command 352 supports the determination of the most active slabs to figure 353 out which slabs are relevant to a particular load. 354 Try running: slabinfo -DA 355 356config DEBUG_KMEMLEAK 357 bool "Kernel memory leak detector" 358 depends on DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && \ 359 (X86 || ARM || PPC || S390 || SPARC64 || SUPERH || MICROBLAZE) 360 361 select DEBUG_FS if SYSFS 362 select STACKTRACE if STACKTRACE_SUPPORT 363 select KALLSYMS 364 select CRC32 365 help 366 Say Y here if you want to enable the memory leak 367 detector. The memory allocation/freeing is traced in a way 368 similar to the Boehm's conservative garbage collector, the 369 difference being that the orphan objects are not freed but 370 only shown in /sys/kernel/debug/kmemleak. Enabling this 371 feature will introduce an overhead to memory 372 allocations. See Documentation/kmemleak.txt for more 373 details. 374 375 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances 376 of finding leaks due to the slab objects poisoning. 377 378 In order to access the kmemleak file, debugfs needs to be 379 mounted (usually at /sys/kernel/debug). 380 381config DEBUG_KMEMLEAK_EARLY_LOG_SIZE 382 int "Maximum kmemleak early log entries" 383 depends on DEBUG_KMEMLEAK 384 range 200 40000 385 default 400 386 help 387 Kmemleak must track all the memory allocations to avoid 388 reporting false positives. Since memory may be allocated or 389 freed before kmemleak is initialised, an early log buffer is 390 used to store these actions. If kmemleak reports "early log 391 buffer exceeded", please increase this value. 392 393config DEBUG_KMEMLEAK_TEST 394 tristate "Simple test for the kernel memory leak detector" 395 depends on DEBUG_KMEMLEAK 396 help 397 Say Y or M here to build a test for the kernel memory leak 398 detector. This option enables a module that explicitly leaks 399 memory. 400 401 If unsure, say N. 402 403config DEBUG_PREEMPT 404 bool "Debug preemptible kernel" 405 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT 406 default y 407 help 408 If you say Y here then the kernel will use a debug variant of the 409 commonly used smp_processor_id() function and will print warnings 410 if kernel code uses it in a preemption-unsafe way. Also, the kernel 411 will detect preemption count underflows. 412 413config DEBUG_RT_MUTEXES 414 bool "RT Mutex debugging, deadlock detection" 415 depends on DEBUG_KERNEL && RT_MUTEXES 416 help 417 This allows rt mutex semantics violations and rt mutex related 418 deadlocks (lockups) to be detected and reported automatically. 419 420config DEBUG_PI_LIST 421 bool 422 default y 423 depends on DEBUG_RT_MUTEXES 424 425config RT_MUTEX_TESTER 426 bool "Built-in scriptable tester for rt-mutexes" 427 depends on DEBUG_KERNEL && RT_MUTEXES 428 help 429 This option enables a rt-mutex tester. 430 431config DEBUG_SPINLOCK 432 bool "Spinlock and rw-lock debugging: basic checks" 433 depends on DEBUG_KERNEL 434 help 435 Say Y here and build SMP to catch missing spinlock initialization 436 and certain other kinds of spinlock errors commonly made. This is 437 best used in conjunction with the NMI watchdog so that spinlock 438 deadlocks are also debuggable. 439 440config DEBUG_MUTEXES 441 bool "Mutex debugging: basic checks" 442 depends on DEBUG_KERNEL 443 help 444 This feature allows mutex semantics violations to be detected and 445 reported. 446 447config DEBUG_LOCK_ALLOC 448 bool "Lock debugging: detect incorrect freeing of live locks" 449 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 450 select DEBUG_SPINLOCK 451 select DEBUG_MUTEXES 452 select LOCKDEP 453 help 454 This feature will check whether any held lock (spinlock, rwlock, 455 mutex or rwsem) is incorrectly freed by the kernel, via any of the 456 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 457 vfree(), etc.), whether a live lock is incorrectly reinitialized via 458 spin_lock_init()/mutex_init()/etc., or whether there is any lock 459 held during task exit. 460 461config PROVE_LOCKING 462 bool "Lock debugging: prove locking correctness" 463 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 464 select LOCKDEP 465 select DEBUG_SPINLOCK 466 select DEBUG_MUTEXES 467 select DEBUG_LOCK_ALLOC 468 default n 469 help 470 This feature enables the kernel to prove that all locking 471 that occurs in the kernel runtime is mathematically 472 correct: that under no circumstance could an arbitrary (and 473 not yet triggered) combination of observed locking 474 sequences (on an arbitrary number of CPUs, running an 475 arbitrary number of tasks and interrupt contexts) cause a 476 deadlock. 477 478 In short, this feature enables the kernel to report locking 479 related deadlocks before they actually occur. 480 481 The proof does not depend on how hard and complex a 482 deadlock scenario would be to trigger: how many 483 participant CPUs, tasks and irq-contexts would be needed 484 for it to trigger. The proof also does not depend on 485 timing: if a race and a resulting deadlock is possible 486 theoretically (no matter how unlikely the race scenario 487 is), it will be proven so and will immediately be 488 reported by the kernel (once the event is observed that 489 makes the deadlock theoretically possible). 490 491 If a deadlock is impossible (i.e. the locking rules, as 492 observed by the kernel, are mathematically correct), the 493 kernel reports nothing. 494 495 NOTE: this feature can also be enabled for rwlocks, mutexes 496 and rwsems - in which case all dependencies between these 497 different locking variants are observed and mapped too, and 498 the proof of observed correctness is also maintained for an 499 arbitrary combination of these separate locking variants. 500 501 For more details, see Documentation/lockdep-design.txt. 502 503config PROVE_RCU 504 bool "RCU debugging: prove RCU correctness" 505 depends on PROVE_LOCKING 506 default n 507 help 508 This feature enables lockdep extensions that check for correct 509 use of RCU APIs. This is currently under development. Say Y 510 if you want to debug RCU usage or help work on the PROVE_RCU 511 feature. 512 513 Say N if you are unsure. 514 515config LOCKDEP 516 bool 517 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 518 select STACKTRACE 519 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 520 select KALLSYMS 521 select KALLSYMS_ALL 522 523config LOCK_STAT 524 bool "Lock usage statistics" 525 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 526 select LOCKDEP 527 select DEBUG_SPINLOCK 528 select DEBUG_MUTEXES 529 select DEBUG_LOCK_ALLOC 530 default n 531 help 532 This feature enables tracking lock contention points 533 534 For more details, see Documentation/lockstat.txt 535 536 This also enables lock events required by "perf lock", 537 subcommand of perf. 538 If you want to use "perf lock", you also need to turn on 539 CONFIG_EVENT_TRACING. 540 541 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 542 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 543 544config DEBUG_LOCKDEP 545 bool "Lock dependency engine debugging" 546 depends on DEBUG_KERNEL && LOCKDEP 547 help 548 If you say Y here, the lock dependency engine will do 549 additional runtime checks to debug itself, at the price 550 of more runtime overhead. 551 552config TRACE_IRQFLAGS 553 depends on DEBUG_KERNEL 554 bool 555 default y 556 depends on TRACE_IRQFLAGS_SUPPORT 557 depends on PROVE_LOCKING 558 559config DEBUG_SPINLOCK_SLEEP 560 bool "Spinlock debugging: sleep-inside-spinlock checking" 561 depends on DEBUG_KERNEL 562 help 563 If you say Y here, various routines which may sleep will become very 564 noisy if they are called with a spinlock held. 565 566config DEBUG_LOCKING_API_SELFTESTS 567 bool "Locking API boot-time self-tests" 568 depends on DEBUG_KERNEL 569 help 570 Say Y here if you want the kernel to run a short self-test during 571 bootup. The self-test checks whether common types of locking bugs 572 are detected by debugging mechanisms or not. (if you disable 573 lock debugging then those bugs wont be detected of course.) 574 The following locking APIs are covered: spinlocks, rwlocks, 575 mutexes and rwsems. 576 577config STACKTRACE 578 bool 579 depends on STACKTRACE_SUPPORT 580 581config DEBUG_KOBJECT 582 bool "kobject debugging" 583 depends on DEBUG_KERNEL 584 help 585 If you say Y here, some extra kobject debugging messages will be sent 586 to the syslog. 587 588config DEBUG_HIGHMEM 589 bool "Highmem debugging" 590 depends on DEBUG_KERNEL && HIGHMEM 591 help 592 This options enables addition error checking for high memory systems. 593 Disable for production systems. 594 595config DEBUG_BUGVERBOSE 596 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED 597 depends on BUG 598 depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \ 599 FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300 600 default y 601 help 602 Say Y here to make BUG() panics output the file name and line number 603 of the BUG call as well as the EIP and oops trace. This aids 604 debugging but costs about 70-100K of memory. 605 606config DEBUG_INFO 607 bool "Compile the kernel with debug info" 608 depends on DEBUG_KERNEL 609 help 610 If you say Y here the resulting kernel image will include 611 debugging info resulting in a larger kernel image. 612 This adds debug symbols to the kernel and modules (gcc -g), and 613 is needed if you intend to use kernel crashdump or binary object 614 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 615 Say Y here only if you plan to debug the kernel. 616 617 If unsure, say N. 618 619config DEBUG_VM 620 bool "Debug VM" 621 depends on DEBUG_KERNEL 622 help 623 Enable this to turn on extended checks in the virtual-memory system 624 that may impact performance. 625 626 If unsure, say N. 627 628config DEBUG_VIRTUAL 629 bool "Debug VM translations" 630 depends on DEBUG_KERNEL && X86 631 help 632 Enable some costly sanity checks in virtual to page code. This can 633 catch mistakes with virt_to_page() and friends. 634 635 If unsure, say N. 636 637config DEBUG_NOMMU_REGIONS 638 bool "Debug the global anon/private NOMMU mapping region tree" 639 depends on DEBUG_KERNEL && !MMU 640 help 641 This option causes the global tree of anonymous and private mapping 642 regions to be regularly checked for invalid topology. 643 644config DEBUG_WRITECOUNT 645 bool "Debug filesystem writers count" 646 depends on DEBUG_KERNEL 647 help 648 Enable this to catch wrong use of the writers count in struct 649 vfsmount. This will increase the size of each file struct by 650 32 bits. 651 652 If unsure, say N. 653 654config DEBUG_MEMORY_INIT 655 bool "Debug memory initialisation" if EMBEDDED 656 default !EMBEDDED 657 help 658 Enable this for additional checks during memory initialisation. 659 The sanity checks verify aspects of the VM such as the memory model 660 and other information provided by the architecture. Verbose 661 information will be printed at KERN_DEBUG loglevel depending 662 on the mminit_loglevel= command-line option. 663 664 If unsure, say Y 665 666config DEBUG_LIST 667 bool "Debug linked list manipulation" 668 depends on DEBUG_KERNEL 669 help 670 Enable this to turn on extended checks in the linked-list 671 walking routines. 672 673 If unsure, say N. 674 675config DEBUG_SG 676 bool "Debug SG table operations" 677 depends on DEBUG_KERNEL 678 help 679 Enable this to turn on checks on scatter-gather tables. This can 680 help find problems with drivers that do not properly initialize 681 their sg tables. 682 683 If unsure, say N. 684 685config DEBUG_NOTIFIERS 686 bool "Debug notifier call chains" 687 depends on DEBUG_KERNEL 688 help 689 Enable this to turn on sanity checking for notifier call chains. 690 This is most useful for kernel developers to make sure that 691 modules properly unregister themselves from notifier chains. 692 This is a relatively cheap check but if you care about maximum 693 performance, say N. 694 695config DEBUG_CREDENTIALS 696 bool "Debug credential management" 697 depends on DEBUG_KERNEL 698 help 699 Enable this to turn on some debug checking for credential 700 management. The additional code keeps track of the number of 701 pointers from task_structs to any given cred struct, and checks to 702 see that this number never exceeds the usage count of the cred 703 struct. 704 705 Furthermore, if SELinux is enabled, this also checks that the 706 security pointer in the cred struct is never seen to be invalid. 707 708 If unsure, say N. 709 710# 711# Select this config option from the architecture Kconfig, if it 712# it is preferred to always offer frame pointers as a config 713# option on the architecture (regardless of KERNEL_DEBUG): 714# 715config ARCH_WANT_FRAME_POINTERS 716 bool 717 help 718 719config FRAME_POINTER 720 bool "Compile the kernel with frame pointers" 721 depends on DEBUG_KERNEL && \ 722 (CRIS || M68K || M68KNOMMU || FRV || UML || \ 723 AVR32 || SUPERH || BLACKFIN || MN10300) || \ 724 ARCH_WANT_FRAME_POINTERS 725 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 726 help 727 If you say Y here the resulting kernel image will be slightly 728 larger and slower, but it gives very useful debugging information 729 in case of kernel bugs. (precise oopses/stacktraces/warnings) 730 731config BOOT_PRINTK_DELAY 732 bool "Delay each boot printk message by N milliseconds" 733 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY 734 help 735 This build option allows you to read kernel boot messages 736 by inserting a short delay after each one. The delay is 737 specified in milliseconds on the kernel command line, 738 using "boot_delay=N". 739 740 It is likely that you would also need to use "lpj=M" to preset 741 the "loops per jiffie" value. 742 See a previous boot log for the "lpj" value to use for your 743 system, and then set "lpj=M" before setting "boot_delay=N". 744 NOTE: Using this option may adversely affect SMP systems. 745 I.e., processors other than the first one may not boot up. 746 BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect 747 what it believes to be lockup conditions. 748 749config RCU_TORTURE_TEST 750 tristate "torture tests for RCU" 751 depends on DEBUG_KERNEL 752 default n 753 help 754 This option provides a kernel module that runs torture tests 755 on the RCU infrastructure. The kernel module may be built 756 after the fact on the running kernel to be tested, if desired. 757 758 Say Y here if you want RCU torture tests to be built into 759 the kernel. 760 Say M if you want the RCU torture tests to build as a module. 761 Say N if you are unsure. 762 763config RCU_TORTURE_TEST_RUNNABLE 764 bool "torture tests for RCU runnable by default" 765 depends on RCU_TORTURE_TEST = y 766 default n 767 help 768 This option provides a way to build the RCU torture tests 769 directly into the kernel without them starting up at boot 770 time. You can use /proc/sys/kernel/rcutorture_runnable 771 to manually override this setting. This /proc file is 772 available only when the RCU torture tests have been built 773 into the kernel. 774 775 Say Y here if you want the RCU torture tests to start during 776 boot (you probably don't). 777 Say N here if you want the RCU torture tests to start only 778 after being manually enabled via /proc. 779 780config RCU_CPU_STALL_DETECTOR 781 bool "Check for stalled CPUs delaying RCU grace periods" 782 depends on TREE_RCU || TREE_PREEMPT_RCU 783 default y 784 help 785 This option causes RCU to printk information on which 786 CPUs are delaying the current grace period, but only when 787 the grace period extends for excessive time periods. 788 789 Say N if you want to disable such checks. 790 791 Say Y if you are unsure. 792 793config RCU_CPU_STALL_VERBOSE 794 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR" 795 depends on RCU_CPU_STALL_DETECTOR && TREE_PREEMPT_RCU 796 default n 797 help 798 This option causes RCU to printk detailed per-task information 799 for any tasks that are stalling the current RCU grace period. 800 801 Say N if you are unsure. 802 803 Say Y if you want to enable such checks. 804 805config KPROBES_SANITY_TEST 806 bool "Kprobes sanity tests" 807 depends on DEBUG_KERNEL 808 depends on KPROBES 809 default n 810 help 811 This option provides for testing basic kprobes functionality on 812 boot. A sample kprobe, jprobe and kretprobe are inserted and 813 verified for functionality. 814 815 Say N if you are unsure. 816 817config BACKTRACE_SELF_TEST 818 tristate "Self test for the backtrace code" 819 depends on DEBUG_KERNEL 820 default n 821 help 822 This option provides a kernel module that can be used to test 823 the kernel stack backtrace code. This option is not useful 824 for distributions or general kernels, but only for kernel 825 developers working on architecture code. 826 827 Note that if you want to also test saved backtraces, you will 828 have to enable STACKTRACE as well. 829 830 Say N if you are unsure. 831 832config DEBUG_BLOCK_EXT_DEVT 833 bool "Force extended block device numbers and spread them" 834 depends on DEBUG_KERNEL 835 depends on BLOCK 836 default n 837 help 838 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON 839 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT 840 YOU ARE DOING. Distros, please enable this and fix whatever 841 is broken. 842 843 Conventionally, block device numbers are allocated from 844 predetermined contiguous area. However, extended block area 845 may introduce non-contiguous block device numbers. This 846 option forces most block device numbers to be allocated from 847 the extended space and spreads them to discover kernel or 848 userland code paths which assume predetermined contiguous 849 device number allocation. 850 851 Note that turning on this debug option shuffles all the 852 device numbers for all IDE and SCSI devices including libata 853 ones, so root partition specified using device number 854 directly (via rdev or root=MAJ:MIN) won't work anymore. 855 Textual device names (root=/dev/sdXn) will continue to work. 856 857 Say N if you are unsure. 858 859config DEBUG_FORCE_WEAK_PER_CPU 860 bool "Force weak per-cpu definitions" 861 depends on DEBUG_KERNEL 862 help 863 s390 and alpha require percpu variables in modules to be 864 defined weak to work around addressing range issue which 865 puts the following two restrictions on percpu variable 866 definitions. 867 868 1. percpu symbols must be unique whether static or not 869 2. percpu variables can't be defined inside a function 870 871 To ensure that generic code follows the above rules, this 872 option forces all percpu variables to be defined as weak. 873 874config LKDTM 875 tristate "Linux Kernel Dump Test Tool Module" 876 depends on DEBUG_FS 877 depends on BLOCK 878 default n 879 help 880 This module enables testing of the different dumping mechanisms by 881 inducing system failures at predefined crash points. 882 If you don't need it: say N 883 Choose M here to compile this code as a module. The module will be 884 called lkdtm. 885 886 Documentation on how to use the module can be found in 887 Documentation/fault-injection/provoke-crashes.txt 888 889config FAULT_INJECTION 890 bool "Fault-injection framework" 891 depends on DEBUG_KERNEL 892 help 893 Provide fault-injection framework. 894 For more details, see Documentation/fault-injection/. 895 896config FAILSLAB 897 bool "Fault-injection capability for kmalloc" 898 depends on FAULT_INJECTION 899 depends on SLAB || SLUB 900 help 901 Provide fault-injection capability for kmalloc. 902 903config FAIL_PAGE_ALLOC 904 bool "Fault-injection capabilitiy for alloc_pages()" 905 depends on FAULT_INJECTION 906 help 907 Provide fault-injection capability for alloc_pages(). 908 909config FAIL_MAKE_REQUEST 910 bool "Fault-injection capability for disk IO" 911 depends on FAULT_INJECTION && BLOCK 912 help 913 Provide fault-injection capability for disk IO. 914 915config FAIL_IO_TIMEOUT 916 bool "Faul-injection capability for faking disk interrupts" 917 depends on FAULT_INJECTION && BLOCK 918 help 919 Provide fault-injection capability on end IO handling. This 920 will make the block layer "forget" an interrupt as configured, 921 thus exercising the error handling. 922 923 Only works with drivers that use the generic timeout handling, 924 for others it wont do anything. 925 926config FAULT_INJECTION_DEBUG_FS 927 bool "Debugfs entries for fault-injection capabilities" 928 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 929 help 930 Enable configuration of fault-injection capabilities via debugfs. 931 932config FAULT_INJECTION_STACKTRACE_FILTER 933 bool "stacktrace filter for fault-injection capabilities" 934 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 935 depends on !X86_64 936 select STACKTRACE 937 select FRAME_POINTER if !PPC && !S390 938 help 939 Provide stacktrace filter for fault-injection capabilities 940 941config LATENCYTOP 942 bool "Latency measuring infrastructure" 943 select FRAME_POINTER if !MIPS && !PPC && !S390 944 select KALLSYMS 945 select KALLSYMS_ALL 946 select STACKTRACE 947 select SCHEDSTATS 948 select SCHED_DEBUG 949 depends on HAVE_LATENCYTOP_SUPPORT 950 help 951 Enable this option if you want to use the LatencyTOP tool 952 to find out which userspace is blocking on what kernel operations. 953 954config SYSCTL_SYSCALL_CHECK 955 bool "Sysctl checks" 956 depends on SYSCTL 957 ---help--- 958 sys_sysctl uses binary paths that have been found challenging 959 to properly maintain and use. This enables checks that help 960 you to keep things correct. 961 962source mm/Kconfig.debug 963source kernel/trace/Kconfig 964 965config PROVIDE_OHCI1394_DMA_INIT 966 bool "Remote debugging over FireWire early on boot" 967 depends on PCI && X86 968 help 969 If you want to debug problems which hang or crash the kernel early 970 on boot and the crashing machine has a FireWire port, you can use 971 this feature to remotely access the memory of the crashed machine 972 over FireWire. This employs remote DMA as part of the OHCI1394 973 specification which is now the standard for FireWire controllers. 974 975 With remote DMA, you can monitor the printk buffer remotely using 976 firescope and access all memory below 4GB using fireproxy from gdb. 977 Even controlling a kernel debugger is possible using remote DMA. 978 979 Usage: 980 981 If ohci1394_dma=early is used as boot parameter, it will initialize 982 all OHCI1394 controllers which are found in the PCI config space. 983 984 As all changes to the FireWire bus such as enabling and disabling 985 devices cause a bus reset and thereby disable remote DMA for all 986 devices, be sure to have the cable plugged and FireWire enabled on 987 the debugging host before booting the debug target for debugging. 988 989 This code (~1k) is freed after boot. By then, the firewire stack 990 in charge of the OHCI-1394 controllers should be used instead. 991 992 See Documentation/debugging-via-ohci1394.txt for more information. 993 994config FIREWIRE_OHCI_REMOTE_DMA 995 bool "Remote debugging over FireWire with firewire-ohci" 996 depends on FIREWIRE_OHCI 997 help 998 This option lets you use the FireWire bus for remote debugging 999 with help of the firewire-ohci driver. It enables unfiltered 1000 remote DMA in firewire-ohci.
1001 See Documentation/debugging-via-ohci1394.txt for more information. 1002 1003 If unsure, say N. 1004 1005config BUILD_DOCSRC 1006 bool "Build targets in Documentation/ tree" 1007 depends on HEADERS_CHECK 1008 help 1009 This option attempts to build objects from the source files in the 1010 kernel Documentation/ tree. 1011 1012 Say N if you are unsure. 1013 1014config DYNAMIC_DEBUG 1015 bool "Enable dynamic printk() support" 1016 default n 1017 depends on PRINTK 1018 depends on DEBUG_FS 1019 help 1020 1021 Compiles debug level messages into the kernel, which would not 1022 otherwise be available at runtime. These messages can then be 1023 enabled/disabled based on various levels of scope - per source file, 1024 function, module, format string, and line number. This mechanism 1025 implicitly enables all pr_debug() and dev_dbg() calls. The impact of 1026 this compile option is a larger kernel text size of about 2%. 1027 1028 Usage: 1029 1030 Dynamic debugging is controlled via the 'dynamic_debug/ddebug' file, 1031 which is contained in the 'debugfs' filesystem. Thus, the debugfs 1032 filesystem must first be mounted before making use of this feature. 1033 We refer the control file as: <debugfs>/dynamic_debug/ddebug. This 1034 file contains a list of the debug statements that can be enabled. The 1035 format for each line of the file is: 1036 1037 filename:lineno [module]function flags format 1038 1039 filename : source file of the debug statement 1040 lineno : line number of the debug statement 1041 module : module that contains the debug statement 1042 function : function that contains the debug statement 1043 flags : 'p' means the line is turned 'on' for printing 1044 format : the format used for the debug statement 1045 1046 From a live system: 1047 1048 nullarbor:~ # cat <debugfs>/dynamic_debug/ddebug 1049 # filename:lineno [module]function flags format 1050 fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012" 1051 fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012" 1052 fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012" 1053 1054 Example usage: 1055 1056 // enable the message at line 1603 of file svcsock.c 1057 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' > 1058 <debugfs>/dynamic_debug/ddebug 1059 1060 // enable all the messages in file svcsock.c 1061 nullarbor:~ # echo -n 'file svcsock.c +p' > 1062 <debugfs>/dynamic_debug/ddebug 1063 1064 // enable all the messages in the NFS server module 1065 nullarbor:~ # echo -n 'module nfsd +p' > 1066 <debugfs>/dynamic_debug/ddebug 1067 1068 // enable all 12 messages in the function svc_process() 1069 nullarbor:~ # echo -n 'func svc_process +p' > 1070 <debugfs>/dynamic_debug/ddebug 1071 1072 // disable all 12 messages in the function svc_process() 1073 nullarbor:~ # echo -n 'func svc_process -p' > 1074 <debugfs>/dynamic_debug/ddebug 1075 1076 See Documentation/dynamic-debug-howto.txt for additional information. 1077 1078config DMA_API_DEBUG 1079 bool "Enable debugging of DMA-API usage" 1080 depends on HAVE_DMA_API_DEBUG 1081 help 1082 Enable this option to debug the use of the DMA API by device drivers. 1083 With this option you will be able to detect common bugs in device 1084 drivers like double-freeing of DMA mappings or freeing mappings that 1085 were never allocated. 1086 This option causes a performance degredation. Use only if you want 1087 to debug device drivers. If unsure, say N. 1088 1089source "samples/Kconfig" 1090 1091source "lib/Kconfig.kgdb" 1092 1093source "lib/Kconfig.kmemcheck" 1094