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 If unsure, say N. 78 79config HEADERS_CHECK 80 bool "Run 'make headers_check' when building vmlinux" 81 depends on !UML 82 help 83 This option will extract the user-visible kernel headers whenever 84 building the kernel, and will run basic sanity checks on them to 85 ensure that exported files do not attempt to include files which 86 were not exported, etc. 87 88 If you're making modifications to header files which are 89 relevant for userspace, say 'Y', and check the headers 90 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in 91 your build tree), to make sure they're suitable. 92 93config DEBUG_SECTION_MISMATCH 94 bool "Enable full Section mismatch analysis" 95 depends on UNDEFINED 96 # This option is on purpose disabled for now. 97 # It will be enabled when we are down to a resonable number 98 # of section mismatch warnings (< 10 for an allyesconfig build) 99 help 100 The section mismatch analysis checks if there are illegal 101 references from one section to another section. 102 Linux will during link or during runtime drop some sections 103 and any use of code/data previously in these sections will 104 most likely result in an oops. 105 In the code functions and variables are annotated with 106 __init, __devinit etc. (see full list in include/linux/init.h) 107 which results in the code/data being placed in specific sections. 108 The section mismatch analysis is always done after a full 109 kernel build but enabling this option will in addition 110 do the following: 111 - Add the option -fno-inline-functions-called-once to gcc 112 When inlining a function annotated __init in a non-init 113 function we would lose the section information and thus 114 the analysis would not catch the illegal reference. 115 This option tells gcc to inline less but will also 116 result in a larger kernel. 117 - Run the section mismatch analysis for each module/built-in.o 118 When we run the section mismatch analysis on vmlinux.o we 119 lose valueble information about where the mismatch was 120 introduced. 121 Running the analysis for each module/built-in.o file 122 will tell where the mismatch happens much closer to the 123 source. The drawback is that we will report the same 124 mismatch at least twice. 125 - Enable verbose reporting from modpost to help solving 126 the section mismatches reported. 127 128config DEBUG_KERNEL 129 bool "Kernel debugging" 130 help 131 Say Y here if you are developing drivers or trying to debug and 132 identify kernel problems. 133 134config DEBUG_SHIRQ 135 bool "Debug shared IRQ handlers" 136 depends on DEBUG_KERNEL && GENERIC_HARDIRQS 137 help 138 Enable this to generate a spurious interrupt as soon as a shared 139 interrupt handler is registered, and just before one is deregistered. 140 Drivers ought to be able to handle interrupts coming in at those 141 points; some don't and need to be caught. 142 143config DETECT_SOFTLOCKUP 144 bool "Detect Soft Lockups" 145 depends on DEBUG_KERNEL && !S390 146 default y 147 help 148 Say Y here to enable the kernel to detect "soft lockups", 149 which are bugs that cause the kernel to loop in kernel 150 mode for more than 10 seconds, without giving other tasks a 151 chance to run. 152 153 When a soft-lockup is detected, the kernel will print the 154 current stack trace (which you should report), but the 155 system will stay locked up. This feature has negligible 156 overhead. 157 158 (Note that "hard lockups" are separate type of bugs that 159 can be detected via the NMI-watchdog, on platforms that 160 support it.) 161 162config SCHED_DEBUG 163 bool "Collect scheduler debugging info" 164 depends on DEBUG_KERNEL && PROC_FS 165 default y 166 help 167 If you say Y here, the /proc/sched_debug file will be provided 168 that can help debug the scheduler. The runtime overhead of this 169 option is minimal. 170 171config SCHEDSTATS 172 bool "Collect scheduler statistics" 173 depends on DEBUG_KERNEL && PROC_FS 174 help 175 If you say Y here, additional code will be inserted into the 176 scheduler and related routines to collect statistics about 177 scheduler behavior and provide them in /proc/schedstat. These 178 stats may be useful for both tuning and debugging the scheduler 179 If you aren't debugging the scheduler or trying to tune a specific 180 application, you can say N to avoid the very slight overhead 181 this adds. 182 183config TIMER_STATS 184 bool "Collect kernel timers statistics" 185 depends on DEBUG_KERNEL && PROC_FS 186 help 187 If you say Y here, additional code will be inserted into the 188 timer routines to collect statistics about kernel timers being 189 reprogrammed. The statistics can be read from /proc/timer_stats. 190 The statistics collection is started by writing 1 to /proc/timer_stats, 191 writing 0 stops it. This feature is useful to collect information 192 about timer usage patterns in kernel and userspace. This feature 193 is lightweight if enabled in the kernel config but not activated 194 (it defaults to deactivated on bootup and will only be activated 195 if some application like powertop activates it explicitly). 196 197config DEBUG_SLAB 198 bool "Debug slab memory allocations" 199 depends on DEBUG_KERNEL && SLAB 200 help 201 Say Y here to have the kernel do limited verification on memory 202 allocation as well as poisoning memory on free to catch use of freed 203 memory. This can make kmalloc/kfree-intensive workloads much slower. 204 205config DEBUG_SLAB_LEAK 206 bool "Memory leak debugging" 207 depends on DEBUG_SLAB 208 209config SLUB_DEBUG_ON 210 bool "SLUB debugging on by default" 211 depends on SLUB && SLUB_DEBUG 212 default n 213 help 214 Boot with debugging on by default. SLUB boots by default with 215 the runtime debug capabilities switched off. Enabling this is 216 equivalent to specifying the "slub_debug" parameter on boot. 217 There is no support for more fine grained debug control like 218 possible with slub_debug=xxx. SLUB debugging may be switched 219 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying 220 "slub_debug=-". 221 222config SLUB_STATS 223 default n 224 bool "Enable SLUB performance statistics" 225 depends on SLUB && SLUB_DEBUG && SYSFS 226 help 227 SLUB statistics are useful to debug SLUBs allocation behavior in 228 order find ways to optimize the allocator. This should never be 229 enabled for production use since keeping statistics slows down 230 the allocator by a few percentage points. The slabinfo command 231 supports the determination of the most active slabs to figure 232 out which slabs are relevant to a particular load. 233 Try running: slabinfo -DA 234 235config DEBUG_PREEMPT 236 bool "Debug preemptible kernel" 237 depends on DEBUG_KERNEL && PREEMPT && (TRACE_IRQFLAGS_SUPPORT || PPC64) 238 default y 239 help 240 If you say Y here then the kernel will use a debug variant of the 241 commonly used smp_processor_id() function and will print warnings 242 if kernel code uses it in a preemption-unsafe way. Also, the kernel 243 will detect preemption count underflows. 244 245config DEBUG_RT_MUTEXES 246 bool "RT Mutex debugging, deadlock detection" 247 depends on DEBUG_KERNEL && RT_MUTEXES 248 help 249 This allows rt mutex semantics violations and rt mutex related 250 deadlocks (lockups) to be detected and reported automatically. 251 252config DEBUG_PI_LIST 253 bool 254 default y 255 depends on DEBUG_RT_MUTEXES 256 257config RT_MUTEX_TESTER 258 bool "Built-in scriptable tester for rt-mutexes" 259 depends on DEBUG_KERNEL && RT_MUTEXES 260 help 261 This option enables a rt-mutex tester. 262 263config DEBUG_SPINLOCK 264 bool "Spinlock and rw-lock debugging: basic checks" 265 depends on DEBUG_KERNEL 266 help 267 Say Y here and build SMP to catch missing spinlock initialization 268 and certain other kinds of spinlock errors commonly made. This is 269 best used in conjunction with the NMI watchdog so that spinlock 270 deadlocks are also debuggable. 271 272config DEBUG_MUTEXES 273 bool "Mutex debugging: basic checks" 274 depends on DEBUG_KERNEL 275 help 276 This feature allows mutex semantics violations to be detected and 277 reported. 278 279config DEBUG_LOCK_ALLOC 280 bool "Lock debugging: detect incorrect freeing of live locks" 281 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 282 select DEBUG_SPINLOCK 283 select DEBUG_MUTEXES 284 select LOCKDEP 285 help 286 This feature will check whether any held lock (spinlock, rwlock, 287 mutex or rwsem) is incorrectly freed by the kernel, via any of the 288 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 289 vfree(), etc.), whether a live lock is incorrectly reinitialized via 290 spin_lock_init()/mutex_init()/etc., or whether there is any lock 291 held during task exit. 292 293config PROVE_LOCKING 294 bool "Lock debugging: prove locking correctness" 295 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 296 select LOCKDEP 297 select DEBUG_SPINLOCK 298 select DEBUG_MUTEXES 299 select DEBUG_LOCK_ALLOC 300 default n 301 help 302 This feature enables the kernel to prove that all locking 303 that occurs in the kernel runtime is mathematically 304 correct: that under no circumstance could an arbitrary (and 305 not yet triggered) combination of observed locking 306 sequences (on an arbitrary number of CPUs, running an 307 arbitrary number of tasks and interrupt contexts) cause a 308 deadlock. 309 310 In short, this feature enables the kernel to report locking 311 related deadlocks before they actually occur. 312 313 The proof does not depend on how hard and complex a 314 deadlock scenario would be to trigger: how many 315 participant CPUs, tasks and irq-contexts would be needed 316 for it to trigger. The proof also does not depend on 317 timing: if a race and a resulting deadlock is possible 318 theoretically (no matter how unlikely the race scenario 319 is), it will be proven so and will immediately be 320 reported by the kernel (once the event is observed that 321 makes the deadlock theoretically possible). 322 323 If a deadlock is impossible (i.e. the locking rules, as 324 observed by the kernel, are mathematically correct), the 325 kernel reports nothing. 326 327 NOTE: this feature can also be enabled for rwlocks, mutexes 328 and rwsems - in which case all dependencies between these 329 different locking variants are observed and mapped too, and 330 the proof of observed correctness is also maintained for an 331 arbitrary combination of these separate locking variants. 332 333 For more details, see Documentation/lockdep-design.txt. 334 335config LOCKDEP 336 bool 337 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 338 select STACKTRACE 339 select FRAME_POINTER if !X86 && !MIPS 340 select KALLSYMS 341 select KALLSYMS_ALL 342 343config LOCK_STAT 344 bool "Lock usage statistics" 345 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 346 select LOCKDEP 347 select DEBUG_SPINLOCK 348 select DEBUG_MUTEXES 349 select DEBUG_LOCK_ALLOC 350 default n 351 help 352 This feature enables tracking lock contention points 353 354 For more details, see Documentation/lockstat.txt 355 356config DEBUG_LOCKDEP 357 bool "Lock dependency engine debugging" 358 depends on DEBUG_KERNEL && LOCKDEP 359 help 360 If you say Y here, the lock dependency engine will do 361 additional runtime checks to debug itself, at the price 362 of more runtime overhead. 363 364config TRACE_IRQFLAGS 365 depends on DEBUG_KERNEL 366 bool 367 default y 368 depends on TRACE_IRQFLAGS_SUPPORT 369 depends on PROVE_LOCKING 370 371config DEBUG_SPINLOCK_SLEEP 372 bool "Spinlock debugging: sleep-inside-spinlock checking" 373 depends on DEBUG_KERNEL 374 help 375 If you say Y here, various routines which may sleep will become very 376 noisy if they are called with a spinlock held. 377 378config DEBUG_LOCKING_API_SELFTESTS 379 bool "Locking API boot-time self-tests" 380 depends on DEBUG_KERNEL 381 help 382 Say Y here if you want the kernel to run a short self-test during 383 bootup. The self-test checks whether common types of locking bugs 384 are detected by debugging mechanisms or not. (if you disable 385 lock debugging then those bugs wont be detected of course.) 386 The following locking APIs are covered: spinlocks, rwlocks, 387 mutexes and rwsems. 388 389config STACKTRACE 390 bool 391 depends on DEBUG_KERNEL 392 depends on STACKTRACE_SUPPORT 393 394config DEBUG_KOBJECT 395 bool "kobject debugging" 396 depends on DEBUG_KERNEL 397 help 398 If you say Y here, some extra kobject debugging messages will be sent 399 to the syslog. 400 401config DEBUG_HIGHMEM 402 bool "Highmem debugging" 403 depends on DEBUG_KERNEL && HIGHMEM 404 help 405 This options enables addition error checking for high memory systems. 406 Disable for production systems. 407 408config DEBUG_BUGVERBOSE 409 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED 410 depends on BUG 411 depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \ 412 FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300 413 default !EMBEDDED 414 help 415 Say Y here to make BUG() panics output the file name and line number 416 of the BUG call as well as the EIP and oops trace. This aids 417 debugging but costs about 70-100K of memory. 418 419config DEBUG_INFO 420 bool "Compile the kernel with debug info" 421 depends on DEBUG_KERNEL 422 help 423 If you say Y here the resulting kernel image will include 424 debugging info resulting in a larger kernel image. 425 This adds debug symbols to the kernel and modules (gcc -g), and 426 is needed if you intend to use kernel crashdump or binary object 427 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 428 Say Y here only if you plan to debug the kernel. 429 430 If unsure, say N. 431 432config DEBUG_VM 433 bool "Debug VM" 434 depends on DEBUG_KERNEL 435 help 436 Enable this to turn on extended checks in the virtual-memory system 437 that may impact performance. 438 439 If unsure, say N. 440 441config DEBUG_WRITECOUNT 442 bool "Debug filesystem writers count" 443 depends on DEBUG_KERNEL 444 help 445 Enable this to catch wrong use of the writers count in struct 446 vfsmount. This will increase the size of each file struct by 447 32 bits. 448 449 If unsure, say N. 450 451config DEBUG_LIST 452 bool "Debug linked list manipulation" 453 depends on DEBUG_KERNEL 454 help 455 Enable this to turn on extended checks in the linked-list 456 walking routines. 457 458 If unsure, say N. 459 460config DEBUG_SG 461 bool "Debug SG table operations" 462 depends on DEBUG_KERNEL 463 help 464 Enable this to turn on checks on scatter-gather tables. This can 465 help find problems with drivers that do not properly initialize 466 their sg tables. 467 468 If unsure, say N. 469 470config FRAME_POINTER 471 bool "Compile the kernel with frame pointers" 472 depends on DEBUG_KERNEL && \ 473 (X86 || CRIS || M68K || M68KNOMMU || FRV || UML || S390 || \ 474 AVR32 || SUPERH || BLACKFIN || MN10300) 475 default y if DEBUG_INFO && UML 476 help 477 If you say Y here the resulting kernel image will be slightly larger 478 and slower, but it might give very useful debugging information on 479 some architectures or if you use external debuggers. 480 If you don't debug the kernel, you can say N. 481 482config BOOT_PRINTK_DELAY 483 bool "Delay each boot printk message by N milliseconds" 484 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY 485 help 486 This build option allows you to read kernel boot messages 487 by inserting a short delay after each one. The delay is 488 specified in milliseconds on the kernel command line, 489 using "boot_delay=N". 490 491 It is likely that you would also need to use "lpj=M" to preset 492 the "loops per jiffie" value. 493 See a previous boot log for the "lpj" value to use for your 494 system, and then set "lpj=M" before setting "boot_delay=N". 495 NOTE: Using this option may adversely affect SMP systems. 496 I.e., processors other than the first one may not boot up. 497 BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect 498 what it believes to be lockup conditions. 499 500config RCU_TORTURE_TEST 501 tristate "torture tests for RCU" 502 depends on DEBUG_KERNEL 503 depends on m 504 default n 505 help 506 This option provides a kernel module that runs torture tests 507 on the RCU infrastructure. The kernel module may be built 508 after the fact on the running kernel to be tested, if desired. 509 510 Say M if you want the RCU torture tests to build as a module. 511 Say N if you are unsure. 512 513config KPROBES_SANITY_TEST 514 bool "Kprobes sanity tests" 515 depends on DEBUG_KERNEL 516 depends on KPROBES 517 default n 518 help 519 This option provides for testing basic kprobes functionality on 520 boot. A sample kprobe, jprobe and kretprobe are inserted and 521 verified for functionality. 522 523 Say N if you are unsure. 524 525config BACKTRACE_SELF_TEST 526 tristate "Self test for the backtrace code" 527 depends on DEBUG_KERNEL 528 default n 529 help 530 This option provides a kernel module that can be used to test 531 the kernel stack backtrace code. This option is not useful 532 for distributions or general kernels, but only for kernel 533 developers working on architecture code. 534 535 Say N if you are unsure. 536 537config LKDTM 538 tristate "Linux Kernel Dump Test Tool Module" 539 depends on DEBUG_KERNEL 540 depends on KPROBES 541 depends on BLOCK 542 default n 543 help 544 This module enables testing of the different dumping mechanisms by 545 inducing system failures at predefined crash points. 546 If you don't need it: say N 547 Choose M here to compile this code as a module. The module will be 548 called lkdtm. 549 550 Documentation on how to use the module can be found in 551 drivers/misc/lkdtm.c 552 553config FAULT_INJECTION 554 bool "Fault-injection framework" 555 depends on DEBUG_KERNEL 556 help 557 Provide fault-injection framework. 558 For more details, see Documentation/fault-injection/. 559 560config FAILSLAB 561 bool "Fault-injection capability for kmalloc" 562 depends on FAULT_INJECTION 563 help 564 Provide fault-injection capability for kmalloc. 565 566config FAIL_PAGE_ALLOC 567 bool "Fault-injection capabilitiy for alloc_pages()" 568 depends on FAULT_INJECTION 569 help 570 Provide fault-injection capability for alloc_pages(). 571 572config FAIL_MAKE_REQUEST 573 bool "Fault-injection capability for disk IO" 574 depends on FAULT_INJECTION 575 help 576 Provide fault-injection capability for disk IO. 577 578config FAULT_INJECTION_DEBUG_FS 579 bool "Debugfs entries for fault-injection capabilities" 580 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 581 help 582 Enable configuration of fault-injection capabilities via debugfs. 583 584config FAULT_INJECTION_STACKTRACE_FILTER 585 bool "stacktrace filter for fault-injection capabilities" 586 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 587 depends on !X86_64 588 select STACKTRACE 589 select FRAME_POINTER 590 help 591 Provide stacktrace filter for fault-injection capabilities 592 593config LATENCYTOP 594 bool "Latency measuring infrastructure" 595 select FRAME_POINTER if !MIPS 596 select KALLSYMS 597 select KALLSYMS_ALL 598 select STACKTRACE 599 select SCHEDSTATS 600 select SCHED_DEBUG 601 depends on HAVE_LATENCYTOP_SUPPORT 602 help 603 Enable this option if you want to use the LatencyTOP tool 604 to find out which userspace is blocking on what kernel operations. 605 606config PROVIDE_OHCI1394_DMA_INIT 607 bool "Remote debugging over FireWire early on boot" 608 depends on PCI && X86 609 help 610 If you want to debug problems which hang or crash the kernel early 611 on boot and the crashing machine has a FireWire port, you can use 612 this feature to remotely access the memory of the crashed machine 613 over FireWire. This employs remote DMA as part of the OHCI1394 614 specification which is now the standard for FireWire controllers. 615 616 With remote DMA, you can monitor the printk buffer remotely using 617 firescope and access all memory below 4GB using fireproxy from gdb. 618 Even controlling a kernel debugger is possible using remote DMA. 619 620 Usage: 621 622 If ohci1394_dma=early is used as boot parameter, it will initialize 623 all OHCI1394 controllers which are found in the PCI config space. 624 625 As all changes to the FireWire bus such as enabling and disabling 626 devices cause a bus reset and thereby disable remote DMA for all 627 devices, be sure to have the cable plugged and FireWire enabled on 628 the debugging host before booting the debug target for debugging. 629 630 This code (~1k) is freed after boot. By then, the firewire stack 631 in charge of the OHCI-1394 controllers should be used instead. 632 633 See Documentation/debugging-via-ohci1394.txt for more information. 634 635config FIREWIRE_OHCI_REMOTE_DMA 636 bool "Remote debugging over FireWire with firewire-ohci" 637 depends on FIREWIRE_OHCI 638 help 639 This option lets you use the FireWire bus for remote debugging 640 with help of the firewire-ohci driver. It enables unfiltered 641 remote DMA in firewire-ohci. 642 See Documentation/debugging-via-ohci1394.txt for more information. 643 644 If unsure, say N. 645 646source "samples/Kconfig" 647 648source "lib/Kconfig.kgdb" 649