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. This feature 130 is lightweight if enabled in the kernel config but not activated 131 (it defaults to deactivated on bootup and will only be activated 132 if some application like powertop activates it explicitly). 133 134config DEBUG_SLAB 135 bool "Debug slab memory allocations" 136 depends on DEBUG_KERNEL && SLAB 137 help 138 Say Y here to have the kernel do limited verification on memory 139 allocation as well as poisoning memory on free to catch use of freed 140 memory. This can make kmalloc/kfree-intensive workloads much slower. 141 142config DEBUG_SLAB_LEAK 143 bool "Memory leak debugging" 144 depends on DEBUG_SLAB 145 146config DEBUG_PREEMPT 147 bool "Debug preemptible kernel" 148 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT 149 default y 150 help 151 If you say Y here then the kernel will use a debug variant of the 152 commonly used smp_processor_id() function and will print warnings 153 if kernel code uses it in a preemption-unsafe way. Also, the kernel 154 will detect preemption count underflows. 155 156config DEBUG_RT_MUTEXES 157 bool "RT Mutex debugging, deadlock detection" 158 depends on DEBUG_KERNEL && RT_MUTEXES 159 help 160 This allows rt mutex semantics violations and rt mutex related 161 deadlocks (lockups) to be detected and reported automatically. 162 163config DEBUG_PI_LIST 164 bool 165 default y 166 depends on DEBUG_RT_MUTEXES 167 168config RT_MUTEX_TESTER 169 bool "Built-in scriptable tester for rt-mutexes" 170 depends on DEBUG_KERNEL && RT_MUTEXES 171 help 172 This option enables a rt-mutex tester. 173 174config DEBUG_SPINLOCK 175 bool "Spinlock and rw-lock debugging: basic checks" 176 depends on DEBUG_KERNEL 177 help 178 Say Y here and build SMP to catch missing spinlock initialization 179 and certain other kinds of spinlock errors commonly made. This is 180 best used in conjunction with the NMI watchdog so that spinlock 181 deadlocks are also debuggable. 182 183config DEBUG_MUTEXES 184 bool "Mutex debugging: basic checks" 185 depends on DEBUG_KERNEL 186 help 187 This feature allows mutex semantics violations to be detected and 188 reported. 189 190config DEBUG_SEMAPHORE 191 bool "Semaphore debugging" 192 depends on DEBUG_KERNEL 193 depends on ALPHA || FRV 194 default n 195 help 196 If you say Y here then semaphore processing will issue lots of 197 verbose debugging messages. If you suspect a semaphore problem or a 198 kernel hacker asks for this option then say Y. Otherwise say N. 199 200config DEBUG_LOCK_ALLOC 201 bool "Lock debugging: detect incorrect freeing of live locks" 202 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 203 select DEBUG_SPINLOCK 204 select DEBUG_MUTEXES 205 select LOCKDEP 206 help 207 This feature will check whether any held lock (spinlock, rwlock, 208 mutex or rwsem) is incorrectly freed by the kernel, via any of the 209 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 210 vfree(), etc.), whether a live lock is incorrectly reinitialized via 211 spin_lock_init()/mutex_init()/etc., or whether there is any lock 212 held during task exit. 213 214config PROVE_LOCKING 215 bool "Lock debugging: prove locking correctness" 216 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 217 select LOCKDEP 218 select DEBUG_SPINLOCK 219 select DEBUG_MUTEXES 220 select DEBUG_LOCK_ALLOC 221 default n 222 help 223 This feature enables the kernel to prove that all locking 224 that occurs in the kernel runtime is mathematically 225 correct: that under no circumstance could an arbitrary (and 226 not yet triggered) combination of observed locking 227 sequences (on an arbitrary number of CPUs, running an 228 arbitrary number of tasks and interrupt contexts) cause a 229 deadlock. 230 231 In short, this feature enables the kernel to report locking 232 related deadlocks before they actually occur. 233 234 The proof does not depend on how hard and complex a 235 deadlock scenario would be to trigger: how many 236 participant CPUs, tasks and irq-contexts would be needed 237 for it to trigger. The proof also does not depend on 238 timing: if a race and a resulting deadlock is possible 239 theoretically (no matter how unlikely the race scenario 240 is), it will be proven so and will immediately be 241 reported by the kernel (once the event is observed that 242 makes the deadlock theoretically possible). 243 244 If a deadlock is impossible (i.e. the locking rules, as 245 observed by the kernel, are mathematically correct), the 246 kernel reports nothing. 247 248 NOTE: this feature can also be enabled for rwlocks, mutexes 249 and rwsems - in which case all dependencies between these 250 different locking variants are observed and mapped too, and 251 the proof of observed correctness is also maintained for an 252 arbitrary combination of these separate locking variants. 253 254 For more details, see Documentation/lockdep-design.txt. 255 256config LOCKDEP 257 bool 258 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 259 select STACKTRACE 260 select FRAME_POINTER if !X86 && !MIPS 261 select KALLSYMS 262 select KALLSYMS_ALL 263 264config DEBUG_LOCKDEP 265 bool "Lock dependency engine debugging" 266 depends on DEBUG_KERNEL && LOCKDEP 267 help 268 If you say Y here, the lock dependency engine will do 269 additional runtime checks to debug itself, at the price 270 of more runtime overhead. 271 272config TRACE_IRQFLAGS 273 depends on DEBUG_KERNEL 274 bool 275 default y 276 depends on TRACE_IRQFLAGS_SUPPORT 277 depends on PROVE_LOCKING 278 279config DEBUG_SPINLOCK_SLEEP 280 bool "Spinlock debugging: sleep-inside-spinlock checking" 281 depends on DEBUG_KERNEL 282 help 283 If you say Y here, various routines which may sleep will become very 284 noisy if they are called with a spinlock held. 285 286config DEBUG_LOCKING_API_SELFTESTS 287 bool "Locking API boot-time self-tests" 288 depends on DEBUG_KERNEL 289 help 290 Say Y here if you want the kernel to run a short self-test during 291 bootup. The self-test checks whether common types of locking bugs 292 are detected by debugging mechanisms or not. (if you disable 293 lock debugging then those bugs wont be detected of course.) 294 The following locking APIs are covered: spinlocks, rwlocks, 295 mutexes and rwsems. 296 297config STACKTRACE 298 bool 299 depends on DEBUG_KERNEL 300 depends on STACKTRACE_SUPPORT 301 302config DEBUG_KOBJECT 303 bool "kobject debugging" 304 depends on DEBUG_KERNEL 305 help 306 If you say Y here, some extra kobject debugging messages will be sent 307 to the syslog. 308 309config DEBUG_HIGHMEM 310 bool "Highmem debugging" 311 depends on DEBUG_KERNEL && HIGHMEM 312 help 313 This options enables addition error checking for high memory systems. 314 Disable for production systems. 315 316config DEBUG_BUGVERBOSE 317 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED 318 depends on BUG 319 depends on ARM || ARM26 || AVR32 || M32R || M68K || SPARC32 || SPARC64 || FRV || SUPERH || GENERIC_BUG || BFIN 320 default !EMBEDDED 321 help 322 Say Y here to make BUG() panics output the file name and line number 323 of the BUG call as well as the EIP and oops trace. This aids 324 debugging but costs about 70-100K of memory. 325 326config DEBUG_INFO 327 bool "Compile the kernel with debug info" 328 depends on DEBUG_KERNEL 329 help 330 If you say Y here the resulting kernel image will include 331 debugging info resulting in a larger kernel image. 332 This adds debug symbols to the kernel and modules (gcc -g), and 333 is needed if you intend to use kernel crashdump or binary object 334 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 335 Say Y here only if you plan to debug the kernel. 336 337 If unsure, say N. 338 339config DEBUG_VM 340 bool "Debug VM" 341 depends on DEBUG_KERNEL 342 help 343 Enable this to turn on extended checks in the virtual-memory system 344 that may impact performance. 345 346 If unsure, say N. 347 348config DEBUG_LIST 349 bool "Debug linked list manipulation" 350 depends on DEBUG_KERNEL 351 help 352 Enable this to turn on extended checks in the linked-list 353 walking routines. 354 355 If unsure, say N. 356 357config FRAME_POINTER 358 bool "Compile the kernel with frame pointers" 359 depends on DEBUG_KERNEL && (X86 || CRIS || M68K || M68KNOMMU || FRV || UML || S390 || AVR32 || SUPERH || BFIN) 360 default y if DEBUG_INFO && UML 361 help 362 If you say Y here the resulting kernel image will be slightly larger 363 and slower, but it might give very useful debugging information on 364 some architectures or if you use external debuggers. 365 If you don't debug the kernel, you can say N. 366 367config FORCED_INLINING 368 bool "Force gcc to inline functions marked 'inline'" 369 depends on DEBUG_KERNEL 370 default y 371 help 372 This option determines if the kernel forces gcc to inline the functions 373 developers have marked 'inline'. Doing so takes away freedom from gcc to 374 do what it thinks is best, which is desirable for the gcc 3.x series of 375 compilers. The gcc 4.x series have a rewritten inlining algorithm and 376 disabling this option will generate a smaller kernel there. Hopefully 377 this algorithm is so good that allowing gcc4 to make the decision can 378 become the default in the future, until then this option is there to 379 test gcc for this. 380 381config RCU_TORTURE_TEST 382 tristate "torture tests for RCU" 383 depends on DEBUG_KERNEL 384 depends on m 385 default n 386 help 387 This option provides a kernel module that runs torture tests 388 on the RCU infrastructure. The kernel module may be built 389 after the fact on the running kernel to be tested, if desired. 390 391 Say M if you want the RCU torture tests to build as a module. 392 Say N if you are unsure. 393 394config LKDTM 395 tristate "Linux Kernel Dump Test Tool Module" 396 depends on DEBUG_KERNEL 397 depends on KPROBES 398 default n 399 help 400 This module enables testing of the different dumping mechanisms by 401 inducing system failures at predefined crash points. 402 If you don't need it: say N 403 Choose M here to compile this code as a module. The module will be 404 called lkdtm. 405 406 Documentation on how to use the module can be found in 407 drivers/misc/lkdtm.c 408 409config FAULT_INJECTION 410 bool "Fault-injection framework" 411 depends on DEBUG_KERNEL 412 help 413 Provide fault-injection framework. 414 For more details, see Documentation/fault-injection/. 415 416config FAILSLAB 417 bool "Fault-injection capability for kmalloc" 418 depends on FAULT_INJECTION 419 help 420 Provide fault-injection capability for kmalloc. 421 422config FAIL_PAGE_ALLOC 423 bool "Fault-injection capabilitiy for alloc_pages()" 424 depends on FAULT_INJECTION 425 help 426 Provide fault-injection capability for alloc_pages(). 427 428config FAIL_MAKE_REQUEST 429 bool "Fault-injection capability for disk IO" 430 depends on FAULT_INJECTION 431 help 432 Provide fault-injection capability for disk IO. 433 434config FAULT_INJECTION_DEBUG_FS 435 bool "Debugfs entries for fault-injection capabilities" 436 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 437 help 438 Enable configuration of fault-injection capabilities via debugfs. 439 440config FAULT_INJECTION_STACKTRACE_FILTER 441 bool "stacktrace filter for fault-injection capabilities" 442 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 443 depends on !X86_64 444 select STACKTRACE 445 select FRAME_POINTER 446 help 447 Provide stacktrace filter for fault-injection capabilities 448