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_MUST_CHECK 13 bool "Enable __must_check logic" 14 default y 15 help 16 Enable the __must_check logic in the kernel build. Disable this to 17 suppress the "warning: ignoring return value of 'foo', declared with 18 attribute warn_unused_result" messages. 19 20config MAGIC_SYSRQ 21 bool "Magic SysRq key" 22 depends on !UML 23 help 24 If you say Y here, you will have some control over the system even 25 if the system crashes for example during kernel debugging (e.g., you 26 will be able to flush the buffer cache to disk, reboot the system 27 immediately or dump some status information). This is accomplished 28 by pressing various keys while holding SysRq (Alt+PrintScreen). It 29 also works on a serial console (on PC hardware at least), if you 30 send a BREAK and then within 5 seconds a command keypress. The 31 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y 32 unless you really know what this hack does. 33 34config UNUSED_SYMBOLS 35 bool "Enable unused/obsolete exported symbols" 36 default y if X86 37 help 38 Unused but exported symbols make the kernel needlessly bigger. For 39 that reason most of these unused exports will soon be removed. This 40 option is provided temporarily to provide a transition period in case 41 some external kernel module needs one of these symbols anyway. If you 42 encounter such a case in your module, consider if you are actually 43 using the right API. (rationale: since nobody in the kernel is using 44 this in a module, there is a pretty good chance it's actually the 45 wrong interface to use). If you really need the symbol, please send a 46 mail to the linux kernel mailing list mentioning the symbol and why 47 you really need it, and what the merge plan to the mainline kernel for 48 your module is. 49 50config DEBUG_FS 51 bool "Debug Filesystem" 52 depends on SYSFS 53 help 54 debugfs is a virtual file system that kernel developers use to put 55 debugging files into. Enable this option to be able to read and 56 write to these files. 57 58 If unsure, say N. 59 60config HEADERS_CHECK 61 bool "Run 'make headers_check' when building vmlinux" 62 depends on !UML 63 help 64 This option will extract the user-visible kernel headers whenever 65 building the kernel, and will run basic sanity checks on them to 66 ensure that exported files do not attempt to include files which 67 were not exported, etc. 68 69 If you're making modifications to header files which are 70 relevant for userspace, say 'Y', and check the headers 71 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in 72 your build tree), to make sure they're suitable. 73 74config DEBUG_KERNEL 75 bool "Kernel debugging" 76 help 77 Say Y here if you are developing drivers or trying to debug and 78 identify kernel problems. 79 80config DEBUG_SHIRQ 81 bool "Debug shared IRQ handlers" 82 depends on DEBUG_KERNEL && GENERIC_HARDIRQS 83 help 84 Enable this to generate a spurious interrupt as soon as a shared 85 interrupt handler is registered, and just before one is deregistered. 86 Drivers ought to be able to handle interrupts coming in at those 87 points; some don't and need to be caught. 88 89config DETECT_SOFTLOCKUP 90 bool "Detect Soft Lockups" 91 depends on DEBUG_KERNEL && !S390 92 default y 93 help 94 Say Y here to enable the kernel to detect "soft lockups", 95 which are bugs that cause the kernel to loop in kernel 96 mode for more than 10 seconds, without giving other tasks a 97 chance to run. 98 99 When a soft-lockup is detected, the kernel will print the 100 current stack trace (which you should report), but the 101 system will stay locked up. This feature has negligible 102 overhead. 103 104 (Note that "hard lockups" are separate type of bugs that 105 can be detected via the NMI-watchdog, on platforms that 106 support it.) 107 108config SCHED_DEBUG 109 bool "Collect scheduler debugging info" 110 depends on DEBUG_KERNEL && PROC_FS 111 default y 112 help 113 If you say Y here, the /proc/sched_debug file will be provided 114 that can help debug the scheduler. The runtime overhead of this 115 option is minimal. 116 117config SCHEDSTATS 118 bool "Collect scheduler statistics" 119 depends on DEBUG_KERNEL && PROC_FS 120 help 121 If you say Y here, additional code will be inserted into the 122 scheduler and related routines to collect statistics about 123 scheduler behavior and provide them in /proc/schedstat. These 124 stats may be useful for both tuning and debugging the scheduler 125 If you aren't debugging the scheduler or trying to tune a specific 126 application, you can say N to avoid the very slight overhead 127 this adds. 128 129config TIMER_STATS 130 bool "Collect kernel timers statistics" 131 depends on DEBUG_KERNEL && PROC_FS 132 help 133 If you say Y here, additional code will be inserted into the 134 timer routines to collect statistics about kernel timers being 135 reprogrammed. The statistics can be read from /proc/timer_stats. 136 The statistics collection is started by writing 1 to /proc/timer_stats, 137 writing 0 stops it. This feature is useful to collect information 138 about timer usage patterns in kernel and userspace. This feature 139 is lightweight if enabled in the kernel config but not activated 140 (it defaults to deactivated on bootup and will only be activated 141 if some application like powertop activates it explicitly). 142 143config DEBUG_SLAB 144 bool "Debug slab memory allocations" 145 depends on DEBUG_KERNEL && SLAB 146 help 147 Say Y here to have the kernel do limited verification on memory 148 allocation as well as poisoning memory on free to catch use of freed 149 memory. This can make kmalloc/kfree-intensive workloads much slower. 150 151config DEBUG_SLAB_LEAK 152 bool "Memory leak debugging" 153 depends on DEBUG_SLAB 154 155config DEBUG_PREEMPT 156 bool "Debug preemptible kernel" 157 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT 158 default y 159 help 160 If you say Y here then the kernel will use a debug variant of the 161 commonly used smp_processor_id() function and will print warnings 162 if kernel code uses it in a preemption-unsafe way. Also, the kernel 163 will detect preemption count underflows. 164 165config DEBUG_RT_MUTEXES 166 bool "RT Mutex debugging, deadlock detection" 167 depends on DEBUG_KERNEL && RT_MUTEXES 168 help 169 This allows rt mutex semantics violations and rt mutex related 170 deadlocks (lockups) to be detected and reported automatically. 171 172config DEBUG_PI_LIST 173 bool 174 default y 175 depends on DEBUG_RT_MUTEXES 176 177config RT_MUTEX_TESTER 178 bool "Built-in scriptable tester for rt-mutexes" 179 depends on DEBUG_KERNEL && RT_MUTEXES 180 help 181 This option enables a rt-mutex tester. 182 183config DEBUG_SPINLOCK 184 bool "Spinlock and rw-lock debugging: basic checks" 185 depends on DEBUG_KERNEL 186 help 187 Say Y here and build SMP to catch missing spinlock initialization 188 and certain other kinds of spinlock errors commonly made. This is 189 best used in conjunction with the NMI watchdog so that spinlock 190 deadlocks are also debuggable. 191 192config DEBUG_MUTEXES 193 bool "Mutex debugging: basic checks" 194 depends on DEBUG_KERNEL 195 help 196 This feature allows mutex semantics violations to be detected and 197 reported. 198 199config DEBUG_SEMAPHORE 200 bool "Semaphore debugging" 201 depends on DEBUG_KERNEL 202 depends on ALPHA || FRV 203 default n 204 help 205 If you say Y here then semaphore processing will issue lots of 206 verbose debugging messages. If you suspect a semaphore problem or a 207 kernel hacker asks for this option then say Y. Otherwise say N. 208 209config DEBUG_LOCK_ALLOC 210 bool "Lock debugging: detect incorrect freeing of live locks" 211 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 212 select DEBUG_SPINLOCK 213 select DEBUG_MUTEXES 214 select LOCKDEP 215 help 216 This feature will check whether any held lock (spinlock, rwlock, 217 mutex or rwsem) is incorrectly freed by the kernel, via any of the 218 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 219 vfree(), etc.), whether a live lock is incorrectly reinitialized via 220 spin_lock_init()/mutex_init()/etc., or whether there is any lock 221 held during task exit. 222 223config PROVE_LOCKING 224 bool "Lock debugging: prove locking correctness" 225 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 226 select LOCKDEP 227 select DEBUG_SPINLOCK 228 select DEBUG_MUTEXES 229 select DEBUG_LOCK_ALLOC 230 default n 231 help 232 This feature enables the kernel to prove that all locking 233 that occurs in the kernel runtime is mathematically 234 correct: that under no circumstance could an arbitrary (and 235 not yet triggered) combination of observed locking 236 sequences (on an arbitrary number of CPUs, running an 237 arbitrary number of tasks and interrupt contexts) cause a 238 deadlock. 239 240 In short, this feature enables the kernel to report locking 241 related deadlocks before they actually occur. 242 243 The proof does not depend on how hard and complex a 244 deadlock scenario would be to trigger: how many 245 participant CPUs, tasks and irq-contexts would be needed 246 for it to trigger. The proof also does not depend on 247 timing: if a race and a resulting deadlock is possible 248 theoretically (no matter how unlikely the race scenario 249 is), it will be proven so and will immediately be 250 reported by the kernel (once the event is observed that 251 makes the deadlock theoretically possible). 252 253 If a deadlock is impossible (i.e. the locking rules, as 254 observed by the kernel, are mathematically correct), the 255 kernel reports nothing. 256 257 NOTE: this feature can also be enabled for rwlocks, mutexes 258 and rwsems - in which case all dependencies between these 259 different locking variants are observed and mapped too, and 260 the proof of observed correctness is also maintained for an 261 arbitrary combination of these separate locking variants. 262 263 For more details, see Documentation/lockdep-design.txt. 264 265config LOCKDEP 266 bool 267 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 268 select STACKTRACE 269 select FRAME_POINTER if !X86 && !MIPS 270 select KALLSYMS 271 select KALLSYMS_ALL 272 273config DEBUG_LOCKDEP 274 bool "Lock dependency engine debugging" 275 depends on DEBUG_KERNEL && LOCKDEP 276 help 277 If you say Y here, the lock dependency engine will do 278 additional runtime checks to debug itself, at the price 279 of more runtime overhead. 280 281config TRACE_IRQFLAGS 282 depends on DEBUG_KERNEL 283 bool 284 default y 285 depends on TRACE_IRQFLAGS_SUPPORT 286 depends on PROVE_LOCKING 287 288config DEBUG_SPINLOCK_SLEEP 289 bool "Spinlock debugging: sleep-inside-spinlock checking" 290 depends on DEBUG_KERNEL 291 help 292 If you say Y here, various routines which may sleep will become very 293 noisy if they are called with a spinlock held. 294 295config DEBUG_LOCKING_API_SELFTESTS 296 bool "Locking API boot-time self-tests" 297 depends on DEBUG_KERNEL 298 help 299 Say Y here if you want the kernel to run a short self-test during 300 bootup. The self-test checks whether common types of locking bugs 301 are detected by debugging mechanisms or not. (if you disable 302 lock debugging then those bugs wont be detected of course.) 303 The following locking APIs are covered: spinlocks, rwlocks, 304 mutexes and rwsems. 305 306config STACKTRACE 307 bool 308 depends on DEBUG_KERNEL 309 depends on STACKTRACE_SUPPORT 310 311config DEBUG_KOBJECT 312 bool "kobject debugging" 313 depends on DEBUG_KERNEL 314 help 315 If you say Y here, some extra kobject debugging messages will be sent 316 to the syslog. 317 318config DEBUG_HIGHMEM 319 bool "Highmem debugging" 320 depends on DEBUG_KERNEL && HIGHMEM 321 help 322 This options enables addition error checking for high memory systems. 323 Disable for production systems. 324 325config DEBUG_BUGVERBOSE 326 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED 327 depends on BUG 328 depends on ARM || ARM26 || AVR32 || M32R || M68K || SPARC32 || SPARC64 || FRV || SUPERH || GENERIC_BUG || BFIN 329 default !EMBEDDED 330 help 331 Say Y here to make BUG() panics output the file name and line number 332 of the BUG call as well as the EIP and oops trace. This aids 333 debugging but costs about 70-100K of memory. 334 335config DEBUG_INFO 336 bool "Compile the kernel with debug info" 337 depends on DEBUG_KERNEL 338 help 339 If you say Y here the resulting kernel image will include 340 debugging info resulting in a larger kernel image. 341 This adds debug symbols to the kernel and modules (gcc -g), and 342 is needed if you intend to use kernel crashdump or binary object 343 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 344 Say Y here only if you plan to debug the kernel. 345 346 If unsure, say N. 347 348config DEBUG_VM 349 bool "Debug VM" 350 depends on DEBUG_KERNEL 351 help 352 Enable this to turn on extended checks in the virtual-memory system 353 that may impact performance. 354 355 If unsure, say N. 356 357config DEBUG_LIST 358 bool "Debug linked list manipulation" 359 depends on DEBUG_KERNEL 360 help 361 Enable this to turn on extended checks in the linked-list 362 walking routines. 363 364 If unsure, say N. 365 366config FRAME_POINTER 367 bool "Compile the kernel with frame pointers" 368 depends on DEBUG_KERNEL && (X86 || CRIS || M68K || M68KNOMMU || FRV || UML || S390 || AVR32 || SUPERH || BFIN) 369 default y if DEBUG_INFO && UML 370 help 371 If you say Y here the resulting kernel image will be slightly larger 372 and slower, but it might give very useful debugging information on 373 some architectures or if you use external debuggers. 374 If you don't debug the kernel, you can say N. 375 376config FORCED_INLINING 377 bool "Force gcc to inline functions marked 'inline'" 378 depends on DEBUG_KERNEL 379 default y 380 help 381 This option determines if the kernel forces gcc to inline the functions 382 developers have marked 'inline'. Doing so takes away freedom from gcc to 383 do what it thinks is best, which is desirable for the gcc 3.x series of 384 compilers. The gcc 4.x series have a rewritten inlining algorithm and 385 disabling this option will generate a smaller kernel there. Hopefully 386 this algorithm is so good that allowing gcc4 to make the decision can 387 become the default in the future, until then this option is there to 388 test gcc for this. 389 390config RCU_TORTURE_TEST 391 tristate "torture tests for RCU" 392 depends on DEBUG_KERNEL 393 depends on m 394 default n 395 help 396 This option provides a kernel module that runs torture tests 397 on the RCU infrastructure. The kernel module may be built 398 after the fact on the running kernel to be tested, if desired. 399 400 Say M if you want the RCU torture tests to build as a module. 401 Say N if you are unsure. 402 403config LKDTM 404 tristate "Linux Kernel Dump Test Tool Module" 405 depends on DEBUG_KERNEL 406 depends on KPROBES 407 default n 408 help 409 This module enables testing of the different dumping mechanisms by 410 inducing system failures at predefined crash points. 411 If you don't need it: say N 412 Choose M here to compile this code as a module. The module will be 413 called lkdtm. 414 415 Documentation on how to use the module can be found in 416 drivers/misc/lkdtm.c 417 418config FAULT_INJECTION 419 bool "Fault-injection framework" 420 depends on DEBUG_KERNEL 421 help 422 Provide fault-injection framework. 423 For more details, see Documentation/fault-injection/. 424 425config FAILSLAB 426 bool "Fault-injection capability for kmalloc" 427 depends on FAULT_INJECTION 428 help 429 Provide fault-injection capability for kmalloc. 430 431config FAIL_PAGE_ALLOC 432 bool "Fault-injection capabilitiy for alloc_pages()" 433 depends on FAULT_INJECTION 434 help 435 Provide fault-injection capability for alloc_pages(). 436 437config FAIL_MAKE_REQUEST 438 bool "Fault-injection capability for disk IO" 439 depends on FAULT_INJECTION 440 help 441 Provide fault-injection capability for disk IO. 442 443config FAULT_INJECTION_DEBUG_FS 444 bool "Debugfs entries for fault-injection capabilities" 445 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 446 help 447 Enable configuration of fault-injection capabilities via debugfs. 448 449config FAULT_INJECTION_STACKTRACE_FILTER 450 bool "stacktrace filter for fault-injection capabilities" 451 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 452 depends on !X86_64 453 select STACKTRACE 454 select FRAME_POINTER 455 help 456 Provide stacktrace filter for fault-injection capabilities 457