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 SCHEDSTATS 109 bool "Collect scheduler statistics" 110 depends on DEBUG_KERNEL && PROC_FS 111 help 112 If you say Y here, additional code will be inserted into the 113 scheduler and related routines to collect statistics about 114 scheduler behavior and provide them in /proc/schedstat. These 115 stats may be useful for both tuning and debugging the scheduler 116 If you aren't debugging the scheduler or trying to tune a specific 117 application, you can say N to avoid the very slight overhead 118 this adds. 119 120config TIMER_STATS 121 bool "Collect kernel timers statistics" 122 depends on DEBUG_KERNEL && PROC_FS 123 help 124 If you say Y here, additional code will be inserted into the 125 timer routines to collect statistics about kernel timers being 126 reprogrammed. The statistics can be read from /proc/timer_stats. 127 The statistics collection is started by writing 1 to /proc/timer_stats, 128 writing 0 stops it. This feature is useful to collect information 129 about timer usage patterns in kernel and userspace. 130 131config DEBUG_SLAB 132 bool "Debug slab memory allocations" 133 depends on DEBUG_KERNEL && SLAB 134 help 135 Say Y here to have the kernel do limited verification on memory 136 allocation as well as poisoning memory on free to catch use of freed 137 memory. This can make kmalloc/kfree-intensive workloads much slower. 138 139config DEBUG_SLAB_LEAK 140 bool "Memory leak debugging" 141 depends on DEBUG_SLAB 142 143config DEBUG_PREEMPT 144 bool "Debug preemptible kernel" 145 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT 146 default y 147 help 148 If you say Y here then the kernel will use a debug variant of the 149 commonly used smp_processor_id() function and will print warnings 150 if kernel code uses it in a preemption-unsafe way. Also, the kernel 151 will detect preemption count underflows. 152 153config DEBUG_RT_MUTEXES 154 bool "RT Mutex debugging, deadlock detection" 155 depends on DEBUG_KERNEL && RT_MUTEXES 156 help 157 This allows rt mutex semantics violations and rt mutex related 158 deadlocks (lockups) to be detected and reported automatically. 159 160config DEBUG_PI_LIST 161 bool 162 default y 163 depends on DEBUG_RT_MUTEXES 164 165config RT_MUTEX_TESTER 166 bool "Built-in scriptable tester for rt-mutexes" 167 depends on DEBUG_KERNEL && RT_MUTEXES 168 help 169 This option enables a rt-mutex tester. 170 171config DEBUG_SPINLOCK 172 bool "Spinlock and rw-lock debugging: basic checks" 173 depends on DEBUG_KERNEL 174 help 175 Say Y here and build SMP to catch missing spinlock initialization 176 and certain other kinds of spinlock errors commonly made. This is 177 best used in conjunction with the NMI watchdog so that spinlock 178 deadlocks are also debuggable. 179 180config DEBUG_MUTEXES 181 bool "Mutex debugging: basic checks" 182 depends on DEBUG_KERNEL 183 help 184 This feature allows mutex semantics violations to be detected and 185 reported. 186 187config DEBUG_SEMAPHORE 188 bool "Semaphore debugging" 189 depends on DEBUG_KERNEL 190 depends on ALPHA || FRV 191 default n 192 help 193 If you say Y here then semaphore processing will issue lots of 194 verbose debugging messages. If you suspect a semaphore problem or a 195 kernel hacker asks for this option then say Y. Otherwise say N. 196 197config DEBUG_LOCK_ALLOC 198 bool "Lock debugging: detect incorrect freeing of live locks" 199 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 200 select DEBUG_SPINLOCK 201 select DEBUG_MUTEXES 202 select LOCKDEP 203 help 204 This feature will check whether any held lock (spinlock, rwlock, 205 mutex or rwsem) is incorrectly freed by the kernel, via any of the 206 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 207 vfree(), etc.), whether a live lock is incorrectly reinitialized via 208 spin_lock_init()/mutex_init()/etc., or whether there is any lock 209 held during task exit. 210 211config PROVE_LOCKING 212 bool "Lock debugging: prove locking correctness" 213 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 214 select LOCKDEP 215 select DEBUG_SPINLOCK 216 select DEBUG_MUTEXES 217 select DEBUG_LOCK_ALLOC 218 default n 219 help 220 This feature enables the kernel to prove that all locking 221 that occurs in the kernel runtime is mathematically 222 correct: that under no circumstance could an arbitrary (and 223 not yet triggered) combination of observed locking 224 sequences (on an arbitrary number of CPUs, running an 225 arbitrary number of tasks and interrupt contexts) cause a 226 deadlock. 227 228 In short, this feature enables the kernel to report locking 229 related deadlocks before they actually occur. 230 231 The proof does not depend on how hard and complex a 232 deadlock scenario would be to trigger: how many 233 participant CPUs, tasks and irq-contexts would be needed 234 for it to trigger. The proof also does not depend on 235 timing: if a race and a resulting deadlock is possible 236 theoretically (no matter how unlikely the race scenario 237 is), it will be proven so and will immediately be 238 reported by the kernel (once the event is observed that 239 makes the deadlock theoretically possible). 240 241 If a deadlock is impossible (i.e. the locking rules, as 242 observed by the kernel, are mathematically correct), the 243 kernel reports nothing. 244 245 NOTE: this feature can also be enabled for rwlocks, mutexes 246 and rwsems - in which case all dependencies between these 247 different locking variants are observed and mapped too, and 248 the proof of observed correctness is also maintained for an 249 arbitrary combination of these separate locking variants. 250 251 For more details, see Documentation/lockdep-design.txt. 252 253config LOCKDEP 254 bool 255 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 256 select STACKTRACE 257 select FRAME_POINTER if !X86 && !MIPS 258 select KALLSYMS 259 select KALLSYMS_ALL 260 261config DEBUG_LOCKDEP 262 bool "Lock dependency engine debugging" 263 depends on DEBUG_KERNEL && LOCKDEP 264 help 265 If you say Y here, the lock dependency engine will do 266 additional runtime checks to debug itself, at the price 267 of more runtime overhead. 268 269config TRACE_IRQFLAGS 270 depends on DEBUG_KERNEL 271 bool 272 default y 273 depends on TRACE_IRQFLAGS_SUPPORT 274 depends on PROVE_LOCKING 275 276config DEBUG_SPINLOCK_SLEEP 277 bool "Spinlock debugging: sleep-inside-spinlock checking" 278 depends on DEBUG_KERNEL 279 help 280 If you say Y here, various routines which may sleep will become very 281 noisy if they are called with a spinlock held. 282 283config DEBUG_LOCKING_API_SELFTESTS 284 bool "Locking API boot-time self-tests" 285 depends on DEBUG_KERNEL 286 help 287 Say Y here if you want the kernel to run a short self-test during 288 bootup. The self-test checks whether common types of locking bugs 289 are detected by debugging mechanisms or not. (if you disable 290 lock debugging then those bugs wont be detected of course.) 291 The following locking APIs are covered: spinlocks, rwlocks, 292 mutexes and rwsems. 293 294config STACKTRACE 295 bool 296 depends on DEBUG_KERNEL 297 depends on STACKTRACE_SUPPORT 298 299config DEBUG_KOBJECT 300 bool "kobject debugging" 301 depends on DEBUG_KERNEL 302 help 303 If you say Y here, some extra kobject debugging messages will be sent 304 to the syslog. 305 306config DEBUG_HIGHMEM 307 bool "Highmem debugging" 308 depends on DEBUG_KERNEL && HIGHMEM 309 help 310 This options enables addition error checking for high memory systems. 311 Disable for production systems. 312 313config DEBUG_BUGVERBOSE 314 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED 315 depends on BUG 316 depends on ARM || ARM26 || AVR32 || M32R || M68K || SPARC32 || SPARC64 || FRV || SUPERH || GENERIC_BUG || BFIN 317 default !EMBEDDED 318 help 319 Say Y here to make BUG() panics output the file name and line number 320 of the BUG call as well as the EIP and oops trace. This aids 321 debugging but costs about 70-100K of memory. 322 323config DEBUG_INFO 324 bool "Compile the kernel with debug info" 325 depends on DEBUG_KERNEL 326 help 327 If you say Y here the resulting kernel image will include 328 debugging info resulting in a larger kernel image. 329 This adds debug symbols to the kernel and modules (gcc -g), and 330 is needed if you intend to use kernel crashdump or binary object 331 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 332 Say Y here only if you plan to debug the kernel. 333 334 If unsure, say N. 335 336config DEBUG_VM 337 bool "Debug VM" 338 depends on DEBUG_KERNEL 339 help 340 Enable this to turn on extended checks in the virtual-memory system 341 that may impact performance. 342 343 If unsure, say N. 344 345config DEBUG_LIST 346 bool "Debug linked list manipulation" 347 depends on DEBUG_KERNEL 348 help 349 Enable this to turn on extended checks in the linked-list 350 walking routines. 351 352 If unsure, say N. 353 354config FRAME_POINTER 355 bool "Compile the kernel with frame pointers" 356 depends on DEBUG_KERNEL && (X86 || CRIS || M68K || M68KNOMMU || FRV || UML || S390 || AVR32 || SUPERH || BFIN) 357 default y if DEBUG_INFO && UML 358 help 359 If you say Y here the resulting kernel image will be slightly larger 360 and slower, but it might give very useful debugging information on 361 some architectures or if you use external debuggers. 362 If you don't debug the kernel, you can say N. 363 364config FORCED_INLINING 365 bool "Force gcc to inline functions marked 'inline'" 366 depends on DEBUG_KERNEL 367 default y 368 help 369 This option determines if the kernel forces gcc to inline the functions 370 developers have marked 'inline'. Doing so takes away freedom from gcc to 371 do what it thinks is best, which is desirable for the gcc 3.x series of 372 compilers. The gcc 4.x series have a rewritten inlining algorithm and 373 disabling this option will generate a smaller kernel there. Hopefully 374 this algorithm is so good that allowing gcc4 to make the decision can 375 become the default in the future, until then this option is there to 376 test gcc for this. 377 378config RCU_TORTURE_TEST 379 tristate "torture tests for RCU" 380 depends on DEBUG_KERNEL 381 default n 382 help 383 This option provides a kernel module that runs torture tests 384 on the RCU infrastructure. The kernel module may be built 385 after the fact on the running kernel to be tested, if desired. 386 387 Say Y here if you want RCU torture tests to start automatically 388 at boot time (you probably don't). 389 Say M if you want the RCU torture tests to build as a module. 390 Say N if you are unsure. 391 392config LKDTM 393 tristate "Linux Kernel Dump Test Tool Module" 394 depends on DEBUG_KERNEL 395 depends on KPROBES 396 default n 397 help 398 This module enables testing of the different dumping mechanisms by 399 inducing system failures at predefined crash points. 400 If you don't need it: say N 401 Choose M here to compile this code as a module. The module will be 402 called lkdtm. 403 404 Documentation on how to use the module can be found in 405 drivers/misc/lkdtm.c 406 407config FAULT_INJECTION 408 bool "Fault-injection framework" 409 depends on DEBUG_KERNEL 410 help 411 Provide fault-injection framework. 412 For more details, see Documentation/fault-injection/. 413 414config FAILSLAB 415 bool "Fault-injection capability for kmalloc" 416 depends on FAULT_INJECTION 417 help 418 Provide fault-injection capability for kmalloc. 419 420config FAIL_PAGE_ALLOC 421 bool "Fault-injection capabilitiy for alloc_pages()" 422 depends on FAULT_INJECTION 423 help 424 Provide fault-injection capability for alloc_pages(). 425 426config FAIL_MAKE_REQUEST 427 bool "Fault-injection capability for disk IO" 428 depends on FAULT_INJECTION 429 help 430 Provide fault-injection capability for disk IO. 431 432config FAULT_INJECTION_DEBUG_FS 433 bool "Debugfs entries for fault-injection capabilities" 434 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 435 help 436 Enable configuration of fault-injection capabilities via debugfs. 437 438config FAULT_INJECTION_STACKTRACE_FILTER 439 bool "stacktrace filter for fault-injection capabilities" 440 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 441 depends on !X86_64 442 select STACKTRACE 443 select FRAME_POINTER 444 help 445 Provide stacktrace filter for fault-injection capabilities 446