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 LOG_BUF_SHIFT 90 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" if DEBUG_KERNEL 91 range 12 21 92 default 17 if S390 || LOCKDEP 93 default 16 if X86_NUMAQ || IA64 94 default 15 if SMP 95 default 14 96 help 97 Select kernel log buffer size as a power of 2. 98 Defaults and Examples: 99 17 => 128 KB for S/390 100 16 => 64 KB for x86 NUMAQ or IA-64 101 15 => 32 KB for SMP 102 14 => 16 KB for uniprocessor 103 13 => 8 KB 104 12 => 4 KB 105 106config DETECT_SOFTLOCKUP 107 bool "Detect Soft Lockups" 108 depends on DEBUG_KERNEL && !S390 109 default y 110 help 111 Say Y here to enable the kernel to detect "soft lockups", 112 which are bugs that cause the kernel to loop in kernel 113 mode for more than 10 seconds, without giving other tasks a 114 chance to run. 115 116 When a soft-lockup is detected, the kernel will print the 117 current stack trace (which you should report), but the 118 system will stay locked up. This feature has negligible 119 overhead. 120 121 (Note that "hard lockups" are separate type of bugs that 122 can be detected via the NMI-watchdog, on platforms that 123 support it.) 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. 147 148config DEBUG_SLAB 149 bool "Debug slab memory allocations" 150 depends on DEBUG_KERNEL && SLAB 151 help 152 Say Y here to have the kernel do limited verification on memory 153 allocation as well as poisoning memory on free to catch use of freed 154 memory. This can make kmalloc/kfree-intensive workloads much slower. 155 156config DEBUG_SLAB_LEAK 157 bool "Memory leak debugging" 158 depends on DEBUG_SLAB 159 160config DEBUG_PREEMPT 161 bool "Debug preemptible kernel" 162 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT 163 default y 164 help 165 If you say Y here then the kernel will use a debug variant of the 166 commonly used smp_processor_id() function and will print warnings 167 if kernel code uses it in a preemption-unsafe way. Also, the kernel 168 will detect preemption count underflows. 169 170config DEBUG_RT_MUTEXES 171 bool "RT Mutex debugging, deadlock detection" 172 depends on DEBUG_KERNEL && RT_MUTEXES 173 help 174 This allows rt mutex semantics violations and rt mutex related 175 deadlocks (lockups) to be detected and reported automatically. 176 177config DEBUG_PI_LIST 178 bool 179 default y 180 depends on DEBUG_RT_MUTEXES 181 182config RT_MUTEX_TESTER 183 bool "Built-in scriptable tester for rt-mutexes" 184 depends on DEBUG_KERNEL && RT_MUTEXES 185 help 186 This option enables a rt-mutex tester. 187 188config DEBUG_SPINLOCK 189 bool "Spinlock and rw-lock debugging: basic checks" 190 depends on DEBUG_KERNEL 191 help 192 Say Y here and build SMP to catch missing spinlock initialization 193 and certain other kinds of spinlock errors commonly made. This is 194 best used in conjunction with the NMI watchdog so that spinlock 195 deadlocks are also debuggable. 196 197config DEBUG_MUTEXES 198 bool "Mutex debugging: basic checks" 199 depends on DEBUG_KERNEL 200 help 201 This feature allows mutex semantics violations to be detected and 202 reported. 203 204config DEBUG_SEMAPHORE 205 bool "Semaphore debugging" 206 depends on DEBUG_KERNEL 207 depends on ALPHA || FRV 208 default n 209 help 210 If you say Y here then semaphore processing will issue lots of 211 verbose debugging messages. If you suspect a semaphore problem or a 212 kernel hacker asks for this option then say Y. Otherwise say N. 213 214config DEBUG_LOCK_ALLOC 215 bool "Lock debugging: detect incorrect freeing of live locks" 216 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 217 select DEBUG_SPINLOCK 218 select DEBUG_MUTEXES 219 select LOCKDEP 220 help 221 This feature will check whether any held lock (spinlock, rwlock, 222 mutex or rwsem) is incorrectly freed by the kernel, via any of the 223 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 224 vfree(), etc.), whether a live lock is incorrectly reinitialized via 225 spin_lock_init()/mutex_init()/etc., or whether there is any lock 226 held during task exit. 227 228config PROVE_LOCKING 229 bool "Lock debugging: prove locking correctness" 230 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 231 select LOCKDEP 232 select DEBUG_SPINLOCK 233 select DEBUG_MUTEXES 234 select DEBUG_LOCK_ALLOC 235 default n 236 help 237 This feature enables the kernel to prove that all locking 238 that occurs in the kernel runtime is mathematically 239 correct: that under no circumstance could an arbitrary (and 240 not yet triggered) combination of observed locking 241 sequences (on an arbitrary number of CPUs, running an 242 arbitrary number of tasks and interrupt contexts) cause a 243 deadlock. 244 245 In short, this feature enables the kernel to report locking 246 related deadlocks before they actually occur. 247 248 The proof does not depend on how hard and complex a 249 deadlock scenario would be to trigger: how many 250 participant CPUs, tasks and irq-contexts would be needed 251 for it to trigger. The proof also does not depend on 252 timing: if a race and a resulting deadlock is possible 253 theoretically (no matter how unlikely the race scenario 254 is), it will be proven so and will immediately be 255 reported by the kernel (once the event is observed that 256 makes the deadlock theoretically possible). 257 258 If a deadlock is impossible (i.e. the locking rules, as 259 observed by the kernel, are mathematically correct), the 260 kernel reports nothing. 261 262 NOTE: this feature can also be enabled for rwlocks, mutexes 263 and rwsems - in which case all dependencies between these 264 different locking variants are observed and mapped too, and 265 the proof of observed correctness is also maintained for an 266 arbitrary combination of these separate locking variants. 267 268 For more details, see Documentation/lockdep-design.txt. 269 270config LOCKDEP 271 bool 272 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 273 select STACKTRACE 274 select FRAME_POINTER if !X86 && !MIPS 275 select KALLSYMS 276 select KALLSYMS_ALL 277 278config DEBUG_LOCKDEP 279 bool "Lock dependency engine debugging" 280 depends on DEBUG_KERNEL && LOCKDEP 281 help 282 If you say Y here, the lock dependency engine will do 283 additional runtime checks to debug itself, at the price 284 of more runtime overhead. 285 286config TRACE_IRQFLAGS 287 depends on DEBUG_KERNEL 288 bool 289 default y 290 depends on TRACE_IRQFLAGS_SUPPORT 291 depends on PROVE_LOCKING 292 293config DEBUG_SPINLOCK_SLEEP 294 bool "Spinlock debugging: sleep-inside-spinlock checking" 295 depends on DEBUG_KERNEL 296 help 297 If you say Y here, various routines which may sleep will become very 298 noisy if they are called with a spinlock held. 299 300config DEBUG_LOCKING_API_SELFTESTS 301 bool "Locking API boot-time self-tests" 302 depends on DEBUG_KERNEL 303 help 304 Say Y here if you want the kernel to run a short self-test during 305 bootup. The self-test checks whether common types of locking bugs 306 are detected by debugging mechanisms or not. (if you disable 307 lock debugging then those bugs wont be detected of course.) 308 The following locking APIs are covered: spinlocks, rwlocks, 309 mutexes and rwsems. 310 311config STACKTRACE 312 bool 313 depends on DEBUG_KERNEL 314 depends on STACKTRACE_SUPPORT 315 316config DEBUG_KOBJECT 317 bool "kobject debugging" 318 depends on DEBUG_KERNEL 319 help 320 If you say Y here, some extra kobject debugging messages will be sent 321 to the syslog. 322 323config DEBUG_HIGHMEM 324 bool "Highmem debugging" 325 depends on DEBUG_KERNEL && HIGHMEM 326 help 327 This options enables addition error checking for high memory systems. 328 Disable for production systems. 329 330config DEBUG_BUGVERBOSE 331 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED 332 depends on BUG 333 depends on ARM || ARM26 || AVR32 || M32R || M68K || SPARC32 || SPARC64 || FRV || SUPERH || GENERIC_BUG || BFIN 334 default !EMBEDDED 335 help 336 Say Y here to make BUG() panics output the file name and line number 337 of the BUG call as well as the EIP and oops trace. This aids 338 debugging but costs about 70-100K of memory. 339 340config DEBUG_INFO 341 bool "Compile the kernel with debug info" 342 depends on DEBUG_KERNEL 343 help 344 If you say Y here the resulting kernel image will include 345 debugging info resulting in a larger kernel image. 346 This adds debug symbols to the kernel and modules (gcc -g), and 347 is needed if you intend to use kernel crashdump or binary object 348 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 349 Say Y here only if you plan to debug the kernel. 350 351 If unsure, say N. 352 353config DEBUG_VM 354 bool "Debug VM" 355 depends on DEBUG_KERNEL 356 help 357 Enable this to turn on extended checks in the virtual-memory system 358 that may impact performance. 359 360 If unsure, say N. 361 362config DEBUG_LIST 363 bool "Debug linked list manipulation" 364 depends on DEBUG_KERNEL 365 help 366 Enable this to turn on extended checks in the linked-list 367 walking routines. 368 369 If unsure, say N. 370 371config FRAME_POINTER 372 bool "Compile the kernel with frame pointers" 373 depends on DEBUG_KERNEL && (X86 || CRIS || M68K || M68KNOMMU || FRV || UML || S390 || AVR32 || SUPERH || BFIN) 374 default y if DEBUG_INFO && UML 375 help 376 If you say Y here the resulting kernel image will be slightly larger 377 and slower, but it might give very useful debugging information on 378 some architectures or if you use external debuggers. 379 If you don't debug the kernel, you can say N. 380 381config FORCED_INLINING 382 bool "Force gcc to inline functions marked 'inline'" 383 depends on DEBUG_KERNEL 384 default y 385 help 386 This option determines if the kernel forces gcc to inline the functions 387 developers have marked 'inline'. Doing so takes away freedom from gcc to 388 do what it thinks is best, which is desirable for the gcc 3.x series of 389 compilers. The gcc 4.x series have a rewritten inlining algorithm and 390 disabling this option will generate a smaller kernel there. Hopefully 391 this algorithm is so good that allowing gcc4 to make the decision can 392 become the default in the future, until then this option is there to 393 test gcc for this. 394 395config RCU_TORTURE_TEST 396 tristate "torture tests for RCU" 397 depends on DEBUG_KERNEL 398 default n 399 help 400 This option provides a kernel module that runs torture tests 401 on the RCU infrastructure. The kernel module may be built 402 after the fact on the running kernel to be tested, if desired. 403 404 Say Y here if you want RCU torture tests to start automatically 405 at boot time (you probably don't). 406 Say M if you want the RCU torture tests to build as a module. 407 Say N if you are unsure. 408 409config LKDTM 410 tristate "Linux Kernel Dump Test Tool Module" 411 depends on DEBUG_KERNEL 412 depends on KPROBES 413 default n 414 help 415 This module enables testing of the different dumping mechanisms by 416 inducing system failures at predefined crash points. 417 If you don't need it: say N 418 Choose M here to compile this code as a module. The module will be 419 called lkdtm. 420 421 Documentation on how to use the module can be found in 422 drivers/misc/lkdtm.c 423 424config FAULT_INJECTION 425 bool "Fault-injection framework" 426 depends on DEBUG_KERNEL 427 help 428 Provide fault-injection framework. 429 For more details, see Documentation/fault-injection/. 430 431config FAILSLAB 432 bool "Fault-injection capability for kmalloc" 433 depends on FAULT_INJECTION 434 help 435 Provide fault-injection capability for kmalloc. 436 437config FAIL_PAGE_ALLOC 438 bool "Fault-injection capabilitiy for alloc_pages()" 439 depends on FAULT_INJECTION 440 help 441 Provide fault-injection capability for alloc_pages(). 442 443config FAIL_MAKE_REQUEST 444 bool "Fault-injection capability for disk IO" 445 depends on FAULT_INJECTION 446 help 447 Provide fault-injection capability for disk IO. 448 449config FAULT_INJECTION_DEBUG_FS 450 bool "Debugfs entries for fault-injection capabilities" 451 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 452 help 453 Enable configuration of fault-injection capabilities via debugfs. 454 455config FAULT_INJECTION_STACKTRACE_FILTER 456 bool "stacktrace filter for fault-injection capabilities" 457 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 458 select STACKTRACE 459 select FRAME_POINTER 460 help 461 Provide stacktrace filter for fault-injection capabilities 462