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 MAGIC_SYSRQ 29 bool "Magic SysRq key" 30 depends on !UML 31 help 32 If you say Y here, you will have some control over the system even 33 if the system crashes for example during kernel debugging (e.g., you 34 will be able to flush the buffer cache to disk, reboot the system 35 immediately or dump some status information). This is accomplished 36 by pressing various keys while holding SysRq (Alt+PrintScreen). It 37 also works on a serial console (on PC hardware at least), if you 38 send a BREAK and then within 5 seconds a command keypress. The 39 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y 40 unless you really know what this hack does. 41 42config UNUSED_SYMBOLS 43 bool "Enable unused/obsolete exported symbols" 44 default y if X86 45 help 46 Unused but exported symbols make the kernel needlessly bigger. For 47 that reason most of these unused exports will soon be removed. This 48 option is provided temporarily to provide a transition period in case 49 some external kernel module needs one of these symbols anyway. If you 50 encounter such a case in your module, consider if you are actually 51 using the right API. (rationale: since nobody in the kernel is using 52 this in a module, there is a pretty good chance it's actually the 53 wrong interface to use). If you really need the symbol, please send a 54 mail to the linux kernel mailing list mentioning the symbol and why 55 you really need it, and what the merge plan to the mainline kernel for 56 your module is. 57 58config DEBUG_FS 59 bool "Debug Filesystem" 60 depends on SYSFS 61 help 62 debugfs is a virtual file system that kernel developers use to put 63 debugging files into. Enable this option to be able to read and 64 write to these files. 65 66 If unsure, say N. 67 68config HEADERS_CHECK 69 bool "Run 'make headers_check' when building vmlinux" 70 depends on !UML 71 help 72 This option will extract the user-visible kernel headers whenever 73 building the kernel, and will run basic sanity checks on them to 74 ensure that exported files do not attempt to include files which 75 were not exported, etc. 76 77 If you're making modifications to header files which are 78 relevant for userspace, say 'Y', and check the headers 79 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in 80 your build tree), to make sure they're suitable. 81 82config DEBUG_KERNEL 83 bool "Kernel debugging" 84 help 85 Say Y here if you are developing drivers or trying to debug and 86 identify kernel problems. 87 88config DEBUG_SHIRQ 89 bool "Debug shared IRQ handlers" 90 depends on DEBUG_KERNEL && GENERIC_HARDIRQS 91 help 92 Enable this to generate a spurious interrupt as soon as a shared 93 interrupt handler is registered, and just before one is deregistered. 94 Drivers ought to be able to handle interrupts coming in at those 95 points; some don't and need to be caught. 96 97config DETECT_SOFTLOCKUP 98 bool "Detect Soft Lockups" 99 depends on DEBUG_KERNEL && !S390 100 default y 101 help 102 Say Y here to enable the kernel to detect "soft lockups", 103 which are bugs that cause the kernel to loop in kernel 104 mode for more than 10 seconds, without giving other tasks a 105 chance to run. 106 107 When a soft-lockup is detected, the kernel will print the 108 current stack trace (which you should report), but the 109 system will stay locked up. This feature has negligible 110 overhead. 111 112 (Note that "hard lockups" are separate type of bugs that 113 can be detected via the NMI-watchdog, on platforms that 114 support it.) 115 116config SCHED_DEBUG 117 bool "Collect scheduler debugging info" 118 depends on DEBUG_KERNEL && PROC_FS 119 default y 120 help 121 If you say Y here, the /proc/sched_debug file will be provided 122 that can help debug the scheduler. The runtime overhead of this 123 option is minimal. 124 125config SCHEDSTATS 126 bool "Collect scheduler statistics" 127 depends on DEBUG_KERNEL && PROC_FS 128 help 129 If you say Y here, additional code will be inserted into the 130 scheduler and related routines to collect statistics about 131 scheduler behavior and provide them in /proc/schedstat. These 132 stats may be useful for both tuning and debugging the scheduler 133 If you aren't debugging the scheduler or trying to tune a specific 134 application, you can say N to avoid the very slight overhead 135 this adds. 136 137config TIMER_STATS 138 bool "Collect kernel timers statistics" 139 depends on DEBUG_KERNEL && PROC_FS 140 help 141 If you say Y here, additional code will be inserted into the 142 timer routines to collect statistics about kernel timers being 143 reprogrammed. The statistics can be read from /proc/timer_stats. 144 The statistics collection is started by writing 1 to /proc/timer_stats, 145 writing 0 stops it. This feature is useful to collect information 146 about timer usage patterns in kernel and userspace. This feature 147 is lightweight if enabled in the kernel config but not activated 148 (it defaults to deactivated on bootup and will only be activated 149 if some application like powertop activates it explicitly). 150 151config DEBUG_SLAB 152 bool "Debug slab memory allocations" 153 depends on DEBUG_KERNEL && SLAB 154 help 155 Say Y here to have the kernel do limited verification on memory 156 allocation as well as poisoning memory on free to catch use of freed 157 memory. This can make kmalloc/kfree-intensive workloads much slower. 158 159config DEBUG_SLAB_LEAK 160 bool "Memory leak debugging" 161 depends on DEBUG_SLAB 162 163config SLUB_DEBUG_ON 164 bool "SLUB debugging on by default" 165 depends on SLUB && SLUB_DEBUG 166 default n 167 help 168 Boot with debugging on by default. SLUB boots by default with 169 the runtime debug capabilities switched off. Enabling this is 170 equivalent to specifying the "slub_debug" parameter on boot. 171 There is no support for more fine grained debug control like 172 possible with slub_debug=xxx. SLUB debugging may be switched 173 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying 174 "slub_debug=-". 175 176config DEBUG_PREEMPT 177 bool "Debug preemptible kernel" 178 depends on DEBUG_KERNEL && PREEMPT && (TRACE_IRQFLAGS_SUPPORT || PPC64) 179 default y 180 help 181 If you say Y here then the kernel will use a debug variant of the 182 commonly used smp_processor_id() function and will print warnings 183 if kernel code uses it in a preemption-unsafe way. Also, the kernel 184 will detect preemption count underflows. 185 186config DEBUG_RT_MUTEXES 187 bool "RT Mutex debugging, deadlock detection" 188 depends on DEBUG_KERNEL && RT_MUTEXES 189 help 190 This allows rt mutex semantics violations and rt mutex related 191 deadlocks (lockups) to be detected and reported automatically. 192 193config DEBUG_PI_LIST 194 bool 195 default y 196 depends on DEBUG_RT_MUTEXES 197 198config RT_MUTEX_TESTER 199 bool "Built-in scriptable tester for rt-mutexes" 200 depends on DEBUG_KERNEL && RT_MUTEXES 201 help 202 This option enables a rt-mutex tester. 203 204config DEBUG_SPINLOCK 205 bool "Spinlock and rw-lock debugging: basic checks" 206 depends on DEBUG_KERNEL 207 help 208 Say Y here and build SMP to catch missing spinlock initialization 209 and certain other kinds of spinlock errors commonly made. This is 210 best used in conjunction with the NMI watchdog so that spinlock 211 deadlocks are also debuggable. 212 213config DEBUG_MUTEXES 214 bool "Mutex debugging: basic checks" 215 depends on DEBUG_KERNEL 216 help 217 This feature allows mutex semantics violations to be detected and 218 reported. 219 220config DEBUG_SEMAPHORE 221 bool "Semaphore debugging" 222 depends on DEBUG_KERNEL 223 depends on ALPHA || FRV 224 default n 225 help 226 If you say Y here then semaphore processing will issue lots of 227 verbose debugging messages. If you suspect a semaphore problem or a 228 kernel hacker asks for this option then say Y. Otherwise say N. 229 230config DEBUG_LOCK_ALLOC 231 bool "Lock debugging: detect incorrect freeing of live locks" 232 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 233 select DEBUG_SPINLOCK 234 select DEBUG_MUTEXES 235 select LOCKDEP 236 help 237 This feature will check whether any held lock (spinlock, rwlock, 238 mutex or rwsem) is incorrectly freed by the kernel, via any of the 239 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 240 vfree(), etc.), whether a live lock is incorrectly reinitialized via 241 spin_lock_init()/mutex_init()/etc., or whether there is any lock 242 held during task exit. 243 244config PROVE_LOCKING 245 bool "Lock debugging: prove locking correctness" 246 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 247 select LOCKDEP 248 select DEBUG_SPINLOCK 249 select DEBUG_MUTEXES 250 select DEBUG_LOCK_ALLOC 251 default n 252 help 253 This feature enables the kernel to prove that all locking 254 that occurs in the kernel runtime is mathematically 255 correct: that under no circumstance could an arbitrary (and 256 not yet triggered) combination of observed locking 257 sequences (on an arbitrary number of CPUs, running an 258 arbitrary number of tasks and interrupt contexts) cause a 259 deadlock. 260 261 In short, this feature enables the kernel to report locking 262 related deadlocks before they actually occur. 263 264 The proof does not depend on how hard and complex a 265 deadlock scenario would be to trigger: how many 266 participant CPUs, tasks and irq-contexts would be needed 267 for it to trigger. The proof also does not depend on 268 timing: if a race and a resulting deadlock is possible 269 theoretically (no matter how unlikely the race scenario 270 is), it will be proven so and will immediately be 271 reported by the kernel (once the event is observed that 272 makes the deadlock theoretically possible). 273 274 If a deadlock is impossible (i.e. the locking rules, as 275 observed by the kernel, are mathematically correct), the 276 kernel reports nothing. 277 278 NOTE: this feature can also be enabled for rwlocks, mutexes 279 and rwsems - in which case all dependencies between these 280 different locking variants are observed and mapped too, and 281 the proof of observed correctness is also maintained for an 282 arbitrary combination of these separate locking variants. 283 284 For more details, see Documentation/lockdep-design.txt. 285 286config LOCKDEP 287 bool 288 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 289 select STACKTRACE 290 select FRAME_POINTER if !X86 && !MIPS 291 select KALLSYMS 292 select KALLSYMS_ALL 293 294config LOCK_STAT 295 bool "Lock usage statistics" 296 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 297 select LOCKDEP 298 select DEBUG_SPINLOCK 299 select DEBUG_MUTEXES 300 select DEBUG_LOCK_ALLOC 301 default n 302 help 303 This feature enables tracking lock contention points 304 305 For more details, see Documentation/lockstat.txt 306 307config DEBUG_LOCKDEP 308 bool "Lock dependency engine debugging" 309 depends on DEBUG_KERNEL && LOCKDEP 310 help 311 If you say Y here, the lock dependency engine will do 312 additional runtime checks to debug itself, at the price 313 of more runtime overhead. 314 315config TRACE_IRQFLAGS 316 depends on DEBUG_KERNEL 317 bool 318 default y 319 depends on TRACE_IRQFLAGS_SUPPORT 320 depends on PROVE_LOCKING 321 322config DEBUG_SPINLOCK_SLEEP 323 bool "Spinlock debugging: sleep-inside-spinlock checking" 324 depends on DEBUG_KERNEL 325 help 326 If you say Y here, various routines which may sleep will become very 327 noisy if they are called with a spinlock held. 328 329config DEBUG_LOCKING_API_SELFTESTS 330 bool "Locking API boot-time self-tests" 331 depends on DEBUG_KERNEL 332 help 333 Say Y here if you want the kernel to run a short self-test during 334 bootup. The self-test checks whether common types of locking bugs 335 are detected by debugging mechanisms or not. (if you disable 336 lock debugging then those bugs wont be detected of course.) 337 The following locking APIs are covered: spinlocks, rwlocks, 338 mutexes and rwsems. 339 340config STACKTRACE 341 bool 342 depends on DEBUG_KERNEL 343 depends on STACKTRACE_SUPPORT 344 345config DEBUG_KOBJECT 346 bool "kobject debugging" 347 depends on DEBUG_KERNEL 348 help 349 If you say Y here, some extra kobject debugging messages will be sent 350 to the syslog. 351 352config DEBUG_HIGHMEM 353 bool "Highmem debugging" 354 depends on DEBUG_KERNEL && HIGHMEM 355 help 356 This options enables addition error checking for high memory systems. 357 Disable for production systems. 358 359config DEBUG_BUGVERBOSE 360 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED 361 depends on BUG 362 depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || FRV || SUPERH || GENERIC_BUG || BLACKFIN 363 default !EMBEDDED 364 help 365 Say Y here to make BUG() panics output the file name and line number 366 of the BUG call as well as the EIP and oops trace. This aids 367 debugging but costs about 70-100K of memory. 368 369config DEBUG_INFO 370 bool "Compile the kernel with debug info" 371 depends on DEBUG_KERNEL 372 help 373 If you say Y here the resulting kernel image will include 374 debugging info resulting in a larger kernel image. 375 This adds debug symbols to the kernel and modules (gcc -g), and 376 is needed if you intend to use kernel crashdump or binary object 377 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 378 Say Y here only if you plan to debug the kernel. 379 380 If unsure, say N. 381 382config DEBUG_VM 383 bool "Debug VM" 384 depends on DEBUG_KERNEL 385 help 386 Enable this to turn on extended checks in the virtual-memory system 387 that may impact performance. 388 389 If unsure, say N. 390 391config DEBUG_LIST 392 bool "Debug linked list manipulation" 393 depends on DEBUG_KERNEL 394 help 395 Enable this to turn on extended checks in the linked-list 396 walking routines. 397 398 If unsure, say N. 399 400config DEBUG_SG 401 bool "Debug SG table operations" 402 depends on DEBUG_KERNEL 403 help 404 Enable this to turn on checks on scatter-gather tables. This can 405 help find problems with drivers that do not properly initialize 406 their sg tables. 407 408 If unsure, say N. 409 410config FRAME_POINTER 411 bool "Compile the kernel with frame pointers" 412 depends on DEBUG_KERNEL && (X86 || CRIS || M68K || M68KNOMMU || FRV || UML || S390 || AVR32 || SUPERH || BLACKFIN) 413 default y if DEBUG_INFO && UML 414 help 415 If you say Y here the resulting kernel image will be slightly larger 416 and slower, but it might give very useful debugging information on 417 some architectures or if you use external debuggers. 418 If you don't debug the kernel, you can say N. 419 420config FORCED_INLINING 421 bool "Force gcc to inline functions marked 'inline'" 422 depends on DEBUG_KERNEL 423 default y 424 help 425 This option determines if the kernel forces gcc to inline the functions 426 developers have marked 'inline'. Doing so takes away freedom from gcc to 427 do what it thinks is best, which is desirable for the gcc 3.x series of 428 compilers. The gcc 4.x series have a rewritten inlining algorithm and 429 disabling this option will generate a smaller kernel there. Hopefully 430 this algorithm is so good that allowing gcc4 to make the decision can 431 become the default in the future, until then this option is there to 432 test gcc for this. 433 434config BOOT_PRINTK_DELAY 435 bool "Delay each boot printk message by N milliseconds" 436 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY 437 help 438 This build option allows you to read kernel boot messages 439 by inserting a short delay after each one. The delay is 440 specified in milliseconds on the kernel command line, 441 using "boot_delay=N". 442 443 It is likely that you would also need to use "lpj=M" to preset 444 the "loops per jiffie" value. 445 See a previous boot log for the "lpj" value to use for your 446 system, and then set "lpj=M" before setting "boot_delay=N". 447 NOTE: Using this option may adversely affect SMP systems. 448 I.e., processors other than the first one may not boot up. 449 BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect 450 what it believes to be lockup conditions. 451 452config RCU_TORTURE_TEST 453 tristate "torture tests for RCU" 454 depends on DEBUG_KERNEL 455 depends on m 456 default n 457 help 458 This option provides a kernel module that runs torture tests 459 on the RCU infrastructure. The kernel module may be built 460 after the fact on the running kernel to be tested, if desired. 461 462 Say M if you want the RCU torture tests to build as a module. 463 Say N if you are unsure. 464 465config LKDTM 466 tristate "Linux Kernel Dump Test Tool Module" 467 depends on DEBUG_KERNEL 468 depends on KPROBES 469 default n 470 help 471 This module enables testing of the different dumping mechanisms by 472 inducing system failures at predefined crash points. 473 If you don't need it: say N 474 Choose M here to compile this code as a module. The module will be 475 called lkdtm. 476 477 Documentation on how to use the module can be found in 478 drivers/misc/lkdtm.c 479 480config FAULT_INJECTION 481 bool "Fault-injection framework" 482 depends on DEBUG_KERNEL 483 help 484 Provide fault-injection framework. 485 For more details, see Documentation/fault-injection/. 486 487config FAILSLAB 488 bool "Fault-injection capability for kmalloc" 489 depends on FAULT_INJECTION 490 help 491 Provide fault-injection capability for kmalloc. 492 493config FAIL_PAGE_ALLOC 494 bool "Fault-injection capabilitiy for alloc_pages()" 495 depends on FAULT_INJECTION 496 help 497 Provide fault-injection capability for alloc_pages(). 498 499config FAIL_MAKE_REQUEST 500 bool "Fault-injection capability for disk IO" 501 depends on FAULT_INJECTION 502 help 503 Provide fault-injection capability for disk IO. 504 505config FAULT_INJECTION_DEBUG_FS 506 bool "Debugfs entries for fault-injection capabilities" 507 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 508 help 509 Enable configuration of fault-injection capabilities via debugfs. 510 511config FAULT_INJECTION_STACKTRACE_FILTER 512 bool "stacktrace filter for fault-injection capabilities" 513 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 514 depends on !X86_64 515 select STACKTRACE 516 select FRAME_POINTER 517 help 518 Provide stacktrace filter for fault-injection capabilities 519 520source "samples/Kconfig" 521